Spray Drying I

hi everyone we're gonna spend a few

hours or so talking about spray drying

up you couldn't endure through it it'd

be quite interesting anyway three or

four major sources for this is or are

sources for this

kokin Dumont with their process trying

practice book and Kay McKay master is

drying handbook this 1985 backed up by

Stanley Wallace's book

not this one necessarily but the other

one the earlier one and hopefully we

have some interesting stuff for you

so then we'll talk about the general

aspects of spray drying spray raining

and use a sprays has to create large

surface areas for drying it is a

continuous one-step particle formation

process feed solutions and suspensions

or pastes and the product are powders

granulars and aggregates a development

of st spray drying as resulting in a

highly competitive process for drying a

wide range of products and i think i

took this from Astra's about whole bunch

of stuff out there all sorts of areas

from middle or mineral to dye stuffs

pesticides anyway whole sorts all a

bunch of equipment different types of

equipment involved and use the equipment

as well

there's an old broken-down straighter I

buy it now $22,000 kind of an

interesting statement

anyway used equipment this is a listing

of tests and totally told drying

facilities out there here followed up

this list is provided to you by cook and

and or do Dumont I'm not quite sure they

probably both worked on it by that

stands for spray basically those are

spray dryers spray dryers spray dryers

fires ah direct indirect eating

capabilities dry driving capabilities

once through partial recycle close cycle

none of these apparently accept why

rotary trade go back one anyway nice

list

very nice list by from cooking Dumont

spray drying a spraying drying shoes we

spray drying sorry handles a wide

variety of products meet specifications

laid down by a diverse by diverse

industries major advantage few dryers

take pumpable liquids and discharged dry

powder particles produces a specific

particle size and moisture content over

the entire range continuous easy

adaptable full automatic control with

fast response times wide range of

versatile designs available applications

to eat sensitive materials Andals

corrosive embrace of pumpable stuff

slurry space melts solutions of course

it's more it this could be a long-term

objectives i

have more compact to lower energy

consuming dryers lots of specialized

subsections in spray drying spray freeze

drying this may freeze drying spray

cooling spray reactions spray absorption

anyway

we take a look at surface area you why

you're making a lot of use of large

surface area for some purpose if we take

one cubic meter of liquid Minh and we

break it down into drops of 300 microns

each how many drops do we have well we

get up to about seven point one times

ten to this xi drop knock drops so

there's a whole bunch of drops being

produced then you ask one cubic meter of

liquid goes to the surface area of those

drops so how each of those jobs has the

surface area drops having three 300

microns in diameter how much square area

are there is there excuse me 20,000

square meters so I don't know if you

appreciate that there's a whole bunch of

area whole bunch of area all fairly

uniform and seeing approximately the

same environment the 300 microns and you

eliminates diffusion as a drying

limitation you have such huge area

diffusions pain in the neck okay you

don't want to be diffusion control

because it usually means along the

processing times diffusion is acting of

course everywhere all the time but you

don't want it to control so the way you

do that you have a large surface areas

disadvantages for spray drying high

fabrication costs high installation cost

needs support medium structures and

buildings this units are physically

larger that's these confection Dyer has

poor thermal efficiencies 20 30 % large

amounts of that's efficiency 20-30

percent efficient large amounts of

low-grade waste heat may require

expensive heat exchange equipment which

handles powder layer a latent powder

Laden air at saturated nurses near

saturated conditions

Lowell Inlet temperatures of 300 degrees

centigrade typically your weather inlet

temperatures inlet temperature to a

dryer is set by the temperature at which

material starts to degrade on you

temperatures at which a product

aggregation typically you're shooting

for the highest applications go to the

extreme from the most delicate

conditions of food and pharma to high

tonnage for bulk chemicals or heavy

chemicals so what's involved

well yeah it's like I should point out

that there's a video out there on direct

drying you should review that so that

would take care explaining this heating

gas then there's a video out there on

atomization you should view view that so

the spray drying involves heating a gas

exposing it to liquid which is the

atomization combining one and two eating

liquid drops moisture is removed from

the solid moistures picked up by the gas

or by the air so you have the sensible

heat the moisture in the air air picks

up the moisture that's lost from the

solids

organization is usually done with

nozzles or rotary atomizer you can also

have two fluid atomizers as well nozzles

use pressure drop rotary atomizers use

central little energy nozzles wide range

of sizes and designs typically a fuller

lower flow rates the rotary atomizers if

you're going to high flow rates you're

going to have to have duplication you're

gonna have to have many nozzles so to

speak also the nozzles are not unless

you have nozzles that have a turn down

ratio most nozzles are for a fixed flow

for expression drop if course there's

nozzles out there that have turned our

ratio turned our ratios maximum fluoride

to minimum flow rate one to ten ten to

one

or I can go one to forty or 1 to 50 with

some of the more post more complicated

designs rotary atomizers wheels are fed

centrally low pressure operations major

variables fee rate rotational speed and

geometry

those are the fundamental you have the

material properties you have the

operating conditions and you have the

geometry three of the fundamental

variables of process design wide range

of spray characteristics wheels handle

very high flow rates veins are the

wheels are high wide straight or curved

bushings I will show you those later

they're circular or square bushes are

used to handle abrasive feeds bushings

there there's holes in spray dryer

wheels and to spray dryer wheels are

very expensive and bushings are added to

the holes to have them as the items that

were

and then when they we're through there

you're near that condition they exchange

for news there were once this includes

vein plates cups and inverted bowls

disks are used to be coarse spray

requirements again I highly recommend my

course on atomization or excuse me my

videos on atomization rotaries are

reliable easy to operate handles

fluctuating feed rates high feed rates

without duplication handles abrasive

feeds particle size is controlled by

wheel speed rotary atomizers produced

particles around 30 to 120 microns

nozzles have coarser particles around

120 250 microns pressure controls feed

rate spray characteristics and particle

size pressures are very I can't be very

high okay so that means you gotta have a

source or high pressure to fluid nozzles

are four there's three one three main

ways rotary nozzle and to fluid

atomizers basically you use a second

fluid to blow apart a high viscosity

material typically so two fluid nozzles

if you get too high viscosity or used

material you're trying to atomized as

high in viscosity you go to two fluids

producing medium coarseness in which

case with the fluid atomizers the

important variable one of the important

variables is the air to liquid ratio or

the gas to liquid ratio it's a ratio of

mass flow rates although I would have a

tendency to want to talk about momentum

flow rates typically the literature is

focused on mass flow rates

atomizer selection depends upon the

nature of the feed characteristic design

characteristics of the dry product

increasing power input always decreases

particle size for any engineering

operation you always need to pay

attention to power input power input and

if you don't know how to calculate power

input then you should spend some time

and figuring out how to do it so

increasing power input decreases

particle size increasing flow rate at

the same power increases particle size

higher viscosity

higher surface tension results and

larger particles now higher viscosity

are taking care of with a USAG number

discussed in my atomization course high

surface tension is taken care of in the

Weber number so these are two

dimensionless groups that you need to

find out about there's excellent video I

think SOG number let me spell that for

you Oh H SOR GE I think I'm sure I'm

brutalizing it but video shows different

values of that dimensionless group how

the breakage occurs two major

resistances or factors in drop breakage

is or formation of drops size s casa t

police doesn't want to move basically

and the other one is surface tension if

you have a high surface tension than

them then the drop will be around very

very around and essentially under both

of these conditions you will have a very

good strong unbreakable particle or drop

anyway rotary atomizers have great

flexibility and ease of operation often

selected over nozzles

spraying sprays contact spray contacting

drying air this is the one of the

important things while you talk to a

spray dryer company okay

typically you know not atomization is

pretty well understood and the drying is

pretty well understood the mystery is

the airflow rates and how they're

distributed in the dryer now that's

that's why you talked to a sprayer

there's a number of reasons why you talk

to a spray dryer company right

however one of them is how the air

circulated in their dryers determine the

position of the atomizer relative in

relation to the dry air an important

factor that's the design that is a great

effect on dry products many positions of

possible contact is either co-current

counter coin or a mixed so here I've

lifted this I'm not sure from stanley's

but I'm not sure where I stay here

anyway co-current co-current concur mix

con well we have is f 4 feet g 4 gas so

we have feet coming at 40 degrees okay

and hits hot air alright or I guess so

we have low temperatures liquid hitting

high-temperature gas and circulates

around the I suspect this is gas

temperatures perhaps ah feet comes in it

for 20 degrees sorry product particles

leave at 90 degrees and that guess these

are degrees centigrade and cast leaves

at 120 so that yes essentially that's a

picks up moisture it drops in

temperature so the sensible heat if gas

goes into evaporating the liquid and the

liquid heats up a bit so the liquid

material comes in at 20 and eventually

the particle leaves at 90 greasy and

this

would be coconut operations here we have

also co-current operations here we have

counter-current operations here I guess

you can say that the highest temperature

gas meets eyes temperature particles and

again you can see the the gas cooling

down as it picks up moisture and you can

see the feed heating up and leaves as

part a part of it leaves those particles

a ton in 20 so this is counter current

and then we have some sort of mixed flow

whether it be a fountain arrangement

from this feed okay gas comes in 450

leads a ton and 25 and the particles

leave at 95 you wanna you can see the

particle 1995 500 then you have one

higher than that Kocher excuse me

counter current operations again the

product sees the high as it leaves that

sees the highest temperature gas and

counter current we also have what might

be referred to as protective cooling 99

so as the feed comes in at 20 degrees

its evaporating away evaporating away

evaporating away it's not heating up

okay as much as you might anticipate

right because evaporative cooling going

on alright so here we have a large

temperature difference but little

product communication going on so I want

you to do an experiment for me it's

pretty simple I want you to take a

shower it's pretty simple and as the hot

water comes out it's probably I don't

know under the 20 fair and I put your

hand up around the shower header and

fuel out of this and then

drop your hand down further on down to

your shoulder and see how much cooler it

is and as the drop comes out of the

shower header it's thought but

evaporative cooler thing it reaches your

body that's an example of evaporative

cooling another example is in the

cooking of french fries I mean if you

put french fries in a hot oil and the

hot oil is 300 degree centigrade say or

two underneath centigrade much hotter

than the boy you'll notice is that

french fry bubbles and the question is

pretty simple what's causing the french

fried a bubble like that

and second is what's the temperature of

the french fry even though the auto oil

is 200 C the french fry is actually most

likely at a hundred degrees C because

the boiling that's occurring around that

french fry is water evaporating off and

the water boils at 100 degrees C so when

a french fries sitting in hot oil it is

100 degrees C no matter what the

temperature is of the oil that's B's

being protected by evaporative cooling

however after a while a lot of the

moisture leaves the french fry okay and

it heats up and as it heats up the

french fries turn brown so the same sort

of principle happens there's a lot of

protection and due to the liquid being

boiled off for evaporative cooling

keeping it cool now West they have you

know a hot Arizona area they have

humidifiers out on the outside on their

patios they spray a fine mist of water

and as the water evaporates increasing

humidity of course a lowers the

surrounding air temperature the same

sort of thing happens here

they give you an appreciation for the

temperature distributions and spray

dryer so if we take a look

fee may be similar to boiling liquid

drops boiling liquid film boiling film

example I want you to go and watch these

three videos on YouTube so you haven't

realized it or not YouTube's extremely

powerful videos on YouTube are extremely

powerful in a education I wouldn't be a

bit surprised

somehow factors into education in the

future but so many people's put so much

fantastic stuff on YouTube it's

unbelievable

so making molasses I want you to watch

I'll note molasses haze países molasses

happening it's a sustainable sweetness

anyway I want you to sit down and take

these and go watch them moral molasses

down and my thought is there's

similarity to boiling down molasses

which thickens the molasses right to the

liquid drops floating around in your

spray dryer the boiler takes place in

these molasses is very similar liquid

drops boiling now give you an idea of

transposition so to speak physics are

the same atoms through different

locations called current operations

spray is directed into hot air into hot

air entering by air I mean gas okay

product in the air passes through the

dryer in the same direction why they use

for each sensitive materials okay it's

heat sensitive materials because again

you have evaporative cooling going on

protects the product separation times

are short product is not subject to heat

aggregation

right like the temperature is low due to

evaporation evaporative cooling again

drop temperature approaches wet bulb

temperature air becomes much colder much

cooler

lower temperature conditions are and

almost the entire chamber okay radio

trajectories of the rotary atomizer can

be controlled to prevent excessive

deposits on the spray chairing chamber a

drying chamber you can control spray

angle spray angle is often given in all

sorts of technical information but

spread just as a single operating

without any confinement or whatever

there's a spray angle there and for a

wheel it's 360 degrees flat right but

you can bend that believe it or not by

air of air flow rate and baffling you

can bend a horizontal spray into a shape

of an umbrella if you like it takes

talent that Erica takes understanding

but it's it would be a good way of

understanding flow in your spray dry air

chamber in fact I would go so far as to

say you ought to build a model you know

build a very small scale model say you

have a dryer ten feet in diameter or 20

feet diameter so you build a model of it

at 1 foot in diameter you put in the

Vaseline or gates or vanes on how you

are going to control the air being

control it that way in a small scale

model you could possibly control it

large scale model it'd be quite an

adventure for you to do that ok counter

current spraying air enters of the

opposite ends of the dryer

utilization however it subjects the

driest particle to the hottest Airstream

right there's your product deterioration

problem insensitivity meets requirements

of non heat sensitive products upward

stream of air reduces particles tall

velocity upper stream of air increases

the residence time in the chamber needed

for complete evaporation mix low

incorporates both counter and co-current

powders subjected the higher particle

temperatures of course free-flowing

powders can be produced in small

chambers okay air flow rate

predetermines rating the agree

evaporation the influence influences the

passage of spray through the drying

chamber as I said you can bend the air

flow rate can bend the spray angles

expand them out reduce them both

influence the concentration of particles

along the dryer wall influences the

extent to which semi dry particles

reenter the hot zone out areas around

the air dispersor product terms how best

to contact the air and the spray counter

current artists air contacts to ice

particles

best suited for coarse high bulk density

particles that can withstand very hot

environments low porosity due to reduced

tendency to expand rapidly fracture

evaporation and fracture during

evaporation so when the particle

eventually sees the hottest air right

that means somewhere the wettest

particle sees the coolest air so it

reduces rapid evaporation and hence

lower porosity okay so this counter

current means lower prosity I

I cooker highest air contacts

droplets at their maximum moisture

content best suited for materials that

can't withstand high temperatures rapid

evaporation prevents high droplet

temperatures operation rapid evaporation

may expand a fracture to give a

non-porous spherical excuse me non

spherical porous particle again this is

a boiling molasses syndrome here or

similarity and because boiling molasses

if it was to be frozen would be a low

bulk density but potentially of is of

course of concern okay

chamber design in the air introduced

well let's try it again we've power

you're saying similar things as we did

earlier here's the example this is okay

they're going in the same direction

there's a co-current this is counter

current and this is mixed give you an

idea what they are the drying chamber in

your introduction selected clinging to

the required particle size required

particle form porous or non porous

temperature to which the part of dry

particle can be subjective lots of lots

of choices current use for fine products

that are needed 120 microns with low

product temperatures at all times lower

than the outlet gas by say 25 degrees

Coker pressure

this is rotary up here co-current

pressure nozzle towers used for coarse

products with low temperatures

carick are used for course products I

product temperature for heat treated for

heat treatment right obviously you have

seat sensitive materials but then just

on the opposite of that you have some

materials that require heat treating eye

product temperature for heat treatment

instead of heat sensitivity where you

ruined the product you actually are

trying to heat treat the product for

special porosity bulk densities or teas

hardness effects in my dryer course our

video threat drying video I gave a

listing of all the different ways

material can be damaged during drying

and the case hardening effect there's a

lot more other things that can happen to

material as well besides case hardly

mixed flow used for coarse product with

low product mperatures product it's not

so heat sensitive and because I tolerate

some heat treatment dryers of limited

size and volume okay any of individual

particles evaporation takes place from a

saturated vapor film at the particle

surface well maybe yes maybe no of

course there's a some sort of vapor film

coming right out of liquid but whether

it is there's some sort of vapor coming

out of liquid where it forms a film or

not is another question if it's a

bubbling surface with lots of surface

renewal happening around it I'm not sure

that's an important issue so you can

basically both can happen right there's

very little film formed or there's a

whole bunch of film form I suspect there

very little film is formed temperature

approaches wet bulb temperature to stay

you have constant rate drying or

constant falling rate drying constant

rate plenty of liquid around for

evaporation and maintaining saturated

conditions liquid may diffuse to the

surface not enough liquid falling rate

remaining saturated condition

evaporation depends upon the state of

the rate of liquid through the dry dried

surface shop thickness of the dry

surface shale increases with time which

decreases the evaporation rate some

wills by the way produce liquid sheets

and also ligaments so the focus on drops

is well-deserved

but you also gotta recognize the liquid

sheets are being created as well

substantial point of well liquid sheets

eventually break down into drops drops

go and go to particles I'm particularly

interested in knowing how particle size

or if you're drying something that has a

particle size contained in it like

you're drying a slurry how the particle

size affects the atomization which then

affects the drying because I can

envision y'all trying to dry a slurry of

needles that behavior the needle length

would be could have a profound effect on

size of the particle so now there are

the more interesting particle shapes

like if you're driving flakes now with

that slurry made up of flakes or slimes

how would that happen substantial part

of the evaporation takes place when

surfaces are saturated and cooled drying

chamber and air flow provides the

residence time for removal of desired

amount of moisture product leaves the

dryer before any significant temperature

rise can occur or which would cause heat

damage well my

there is a whole bunch of material in

there but basically wall build-up for

example will stay there and experiencing

damage one of the reasons why or one of

the reasons why you don't want to use

the spray dryer is you have all built up

as a result will all build up you can

have the material steady in there for

long times and hence ruling them

occasionally it would drop off the wall

and enter your pot extreme so this is a

being so what you're looking for your

product leaves dry wood for any

significant temperature rise that's what

you're looking for it doesn't

necessarily mean that's what you did

particle size distribution distribution

goes significant change during drying

different products exhibit different

evaporation characteristics some expand

or collapse some fracture some

disintegrate particles become porous

irregularly-shaped other becomes

spherically shaped and dents change of

particle shape dry characteristics are

closely related to drying rate anyway so

let's take a look the relationship

between drop size and particle size drop

size again my atomization course you

have a number of reliable correlations

on how to predict drop size and the

question is I have a certain drop size

and I have the moisture ratios vary

moisture to solid ratios for light

conditions and dry conditions

I use a small W for moisture to solids

capital W for wet me anyway and thee for

dry conditions so one of the neat things

about solids way it's constant for the

particle it's a constant right the

moisture is which

changing the weight of the particle so

we have the weight fraction to find us

this and if we take solid weight divided

through top and bottom we have this

equation so we have 1 plus w e're there

1 over 1 plus W and typically you know

what moisture solid ratio wet and the

moisture to solid ratio dried what you

have coming in is feed you know that and

typically you know what you want to dry

down to this is the weight percent at

the beginning and the drying so we can

have this relationship initial salts can

tend the drop is I have if you work out

the units I have the volume times the

density times the weight fraction I I

have the final concentration this is the

wet density this is the dry density I

have the particle diameter dry and I

have the particle diameter wet I have

wet moisture fraction I have dry

moisture fraction these two equations

one and two are equal to each other and

the only thing I don't know is the ratio

DW to DD which I do these substitutions

in take the cube root and I got a

relationship between the diameter of the

drop or the diameter of a D being dry

right go back subscript D these four

guys double use for wet you come back

here look sorry

DS for dry DS for what I know all those

variables here so I can calculate

give me a sample calculation here

typically I am looking at wet maybe

1,300 kilograms per cubic meter 50/50

moisture right or ww2 whatever that

definition was drying down a point we

substituted in calculate I quickly find

that wet diameter to dry diameter I have

this dry diameters 0.65 what diameter so

a 100 micron drop goes to 65 micron drop

of course this calculation assumes no

breakage and assumes round spheres

they'll break each right or to waste

like those I don't like those but anyway

this calculation is sort of an

idealistic calculation because you will

have particle attrition or particle

breakage attrition being breakage

another word for breaking anyway so it's

kind of interesting that you can sit

there and calculate dry particle size

two wet drop size if you characterize

your wet drop size then you can get the

idea of try particle size however again

highly realistic I just as a guide give

you a feel a better feel for your spray

dryer two ways of handling solids right

particle discharge one you have the

atomization drying chamber the product

falls out the bottom and come bottom and

air and in training power goes out

through cyclone and you have secondary

discharge now this means there's two

discharges which increases as a

complexity

and this you have everything goes out

the bottom goes the cyclone total

potable discharge from one point here

goes out so you have to do nothing

primary separation takes place at the

base of the drying chamber

jari of products fall to the base small

fraction of some training in air and

captured by a cyclone cyclones are dry

collectors and followed by what

scrubbers okay alternatives dry

collectors or bag houses or bag filters

electrostatic precipitators I don't know

bag filters you'd have a vacuum sweeper

at home that's a bag filter you've got

the dry particles off your carpet going

up probably in a cyclone and some of

some of the operations involved cyclones

very visual to collect them stuff choice

of equipment depends upon powder loading

of the air leaving the drying chamber

and you're looking for acceptable

acceptable efficiencies of recovery

classification occurs and this operation

and classification occurs some of the

large heavy particles are over here and

the findings are over here whereas over

here they're all clumped together plus

the large particles will experience

nutrition going in this line so your

your chances of increasing fines

production is higher in this design less

fines here and you already have them

separated or I should say partially

separated now this here should go

through perhaps another cyclone there's

nothing wrong with staging cyclones or

nest of cyclones perhaps then

electrostatic precipitator of

rubber or baghouse and then eventually

if the solids concentrations are still

there or something nasty is still there

you burn it so I don't know I said

classification occurs this form of

classification sometimes useful normally

the two power powders are combined and

conveyed to the discharge area okay

second method recovery takes place in

seventh equipment separation separation

equipment places great importance on

separation efficiency often used because

it doesn't need product conveying system

okay separation of dry product from pair

effects powder powder properties because

of mechanical handling okay

excessive mechanical handling can

produce powders with very high

percentage of fines so okay let's start

and talk about types of spray drying you

have open cycle close cycle self and

their ties II cycles and other cycles as

well as we come up with open cycle hot

air and air dries air exits the

atmosphere close cycle well the problem

with open cycle is you have oxygen for

one thing in there oxygen causes dryer

fires oxygen causes product aggregation

oxygen is not necessarily desirable so

then you run in a nitrogen atmosphere

basically you have nitrogen coming in

nitrogen tries nitrogen recycles

and their castles prevent forensics the

explosions organic solvents are

evaporated and recovered as well so if

you're going to run with solvents and

then you probably want to run a nerd or

closed-cycle within their guests self

and their tizen cycles basically you

start with oxygen and then over

operational times reduced below 6% and

this was by controlling the amount of

excess combustion air and the direct

heaters so self inert eysies essentially

removed the oxygen and as a result you

approach in their conditions so here's a

listing of those open cycle closed cycle

then you have semi closed partial

recycle semi closed source standards

semi closed self inert izing a drying is

air and they're gas air with low oxygen

heating is direct you have indirect dry

heating here by direct heating basically

the hot gases are added directly to the

spray there's no wall and contact this

is if you have a ball in contact that

just adds another resistance the heat

transfer efficiency goes up really high

when you have direct or higher when you

have direct and applications you have

the developed for old idea now developed

for develop for developed for thermal

efficiency he used to be a long long

time ago I shouldn't say a long time ago

natural gas was expensive al natural gas

was very cheap a few years ago we had an

energy crisis now we don't have and

energy crisis ten years ago there was a

great emphasis on energy savings in

spray drying that may still take place

but it seems to be not nearly as urgent

as it once was

semi-closed only a fraction of air

bleeds to the atmosphere this occurs the

standard standard design partial recycle

to stage of all stage designs special

designs aseptic special cooling systems

Lions return so let's take a look at an

open design again open the cycle layouts

feed comes in the air comes in a is new

air and wine is the spray chamber

product out the bottom the air passes

through the exit air passes through a

bank of cyclones for apps or

electrostatic precipitators passes

through bag house they all should first

pass through a cyclone cyclones are so

cheap maybe a white scrubber

cyclone scrubber most common cheapest

high-efficiency particular loss can be

closely controlled particulate loss can

be closely controlled 25 milligrams per

cubic meter often cyclones can't be used

for a high abrasive materials bag Al's

use very fine particles are produced

when particles are too small to be

removed from cyclone scrubbers use where

an atmospheric emissions must be

negligible at 10 milligrams per cubic

meter use when the product is very

friable and collection requires minimum

mechanical treatment herbicides and

pigments are examples they need a backup

wet scrubber for bag ruptures if we have

a bag sitting here right and it becomes

loaded or heavy loading on it polo

gravity may cause it to rip and little

hole goes and as a result air exits

through that hole bypasses the

filtration anyway so bag house is 10

milligrams per cubic meter okay

vector static precipitators used for i

gas flow rate so little pressure drops

while maintaining collection

efficiencies establish layout and the

mining industries use when cyclones

can't well I used ones

quit scrubbers can't do the water

storages many mining locations have no

water all our processing is geared to an

ample amount of water and if you don't

have ample amounts of water processing

has to be changed closed cycle based

upon recycling and reusing the gas

medium inert gas like nitrogen use for

new

help solve problems with conventional

methods use uses an airtight design

operating a little pressure above

atmosphere so leaks out it's

particularly useful for flammable

solvents complete solvent recovery

whenever you're drying toxic materials

anyway it looks like this first thing

you want to note is three is indirect

heater basically this is a heat

exchanger okay there's three major types

of heat exchangers right shell them to

plating plate heat exchanger and a

spiral it smells really nice exchanger

for low pressures under both plate and

spiral the heat exchangers are useful

under 300 so 300 psi

yeah under 300 psi so we have indirect

exchanger there's a wall here between

the heating and the cooling so do you

want to heat this up you want to heat

this stream up so this is the heater

liquid phase indirect heater heats this

gas phase up hits the feed feed

separates and the particles at the

bottom goes through cyclone then it goes

to a wet scrubber also a condenser right

because you want to take the air back

you want to remove the concentrated

material here take the gas phase back to

the original entry point and we'll show

you that little later probably in part

two if I do have a part two so the feed

comes in separates out and the product

and the liquid comes out over here okay

so you may have two products streams one

courser one finds

then I'm not convinced that everything

got out with this wet scrubber condenser

here - condenser they take it material

back to the original input but also a

scrubber so this liquid may actually

contain solids in it this may require

some sort of filtration involved which

brings up my other short course or

videos on filtration 1 & 2 here we have

a operate this condenser look we

got aa relatively hot gases we may not

want to cool it but it may help us to

cool it but then we got them up here and

reheated so anyway there's other ways if

there are other ways of heating this

stream rather than an indirect heater

see what we got closed cycle reasons for

it absolutely no atmospheric pollution

is permitted explosion fires mixtures

can form with air that's why you

enclosed with inerts

closed in fire risks with organic

solvents then possibly if you had an

oxygen in contact with your product then

you have oxidation effects so I mean

your designs are airtight high

efficiency product recovery either

cyclones or bag filters drying gas

recondition solvent recovery and excrete

condenser solvent recovery this go back

it comes in with the feed see the fees

so our liquid here and the liquid is the

solvent then it comes out over here

nothing comes out up here everything

condenser has an exit up here and the

condenser has an exit down here you may

have some recycle going on here

seems to indicate

Oh airtight higher efficiencies trinary

conditioning solvent recovery in the

scrubber condenser successful closed

cycle operations require precise

temperature control and scrubber to

condenser usually obtained using

available cooling water or brine for eye

boiling solvents like ethanol may need a

exchanger cooler compressor for cooling

low boiling solvent like acetone okay

other features air tight operates like

pressure to prevent any inward leakage

of air from outside so if it's going to

leak it's going to leak from the inside

out this differs from open cycle which

operates under a slight back and wear

stuff from the outside can come on in

questions we'll skip the questions other

closed cycle we have semi closed cycle

itself in there dyzee

farmer and two-stage system layouts the

farmer stuff can be quite complicated

now okay

semi closed obviously it's a cross

between open and closed it's not there

tight operates under a slight vacuum you

have two major types partial drying

medium recycle major drying medium

recycle partial drying adopted to

utilize way heating exhaust air although

I say natural gas is not very expensive

these days

they could drop by a factor of 10 this

is now February 24th 2020 so natural

gases

however you know utility bill is a

utility bill and it can be quite high

even though

natural gas is cheap so you may wish to

adopt it to utilize waste heat and

reduce fuel dryers see what we got here

now this would be a partial recycle that

means you have the spray dryer dry

collector making your product now after

I collector maybe cyclone then it splits

here some of its setback and this is a

hot stream still odd

so let's fit back and then you put in

waste heat and what bothers me is this

waste gas because if I put in waste gas

and yet waste gas back out so you want

to put in if waste gas doesn't come out

over here then it cumulates in there and

not a good idea

unless of course this is a direct burner

where you're burning it so you have fuel

and combustion air coming in now then

the if you have a burner in here that's

fine that way you can burn that waste

gas or the waste in that gas but you do

the split up here and recycle this is a

hot stream and that stream puts a less

of a load on the burner right and save

your money and the hot stream also then

goes to the condenser and discharges

through the atmosphere but I don't want

that waste heat to come out of the

heater

I want burn in there down here we have

the majority recycled okay again from

the direct scrubber goes to the scrubber

which then goes to recycle to the

so we could potentially have solids

coming a very fine amount of solids

coming out of this condenser of course

we're losing a lot of the heat here all

right we did heat recovery here some but

since all this goes to the scrubber

condenser the cooling system take the

heat out of course if I take the heat

out of my wet scrubber right here I have

the cooling going on so this is C which

would be what coolant I eat at my

coolant which could potentially go to

heating up my feed right a little bit of

pinch technology there where your

matching heating and cooling

requirements with different streams if

you haven't tried or thought of pitch

technology its applied to a single spray

dryer unit probably be eminent Aegis to

you let's see what we got

partial dried we already talked about

that well let's see

recycle depends upon water content and

the dry air going to the drying chamber

okay depends upon the required outlet

temperature to maintain the desired

residual moisture up to 50% of exhaust

gas can be recycled in most cases where

the outlet temperatures are above 120 C

has led to have 20% reduction in fuel

consumption that's through utility bill

especially if the outlet temperatures

are high allows the use of a smaller

scrubber for cleaning a smaller amount

of guests see if some of the gas goes

this way

you don't have to clean it right there

use your scrubber operation requirements

and lowers the cost of your scrubbing

action open cycle designs can be built

to partial recycled designs so you have

an open cycle there's not much you have

to do here right yeah basically open

cycle if we take a look the open cycle

this line was not there so that's open

cycle BAM now a closed cycle or semi

partial recycle you have this line here

that's all there is

so how open cycle designs can be rebuilt

fairly easily

major dry and me recycled to distinct

uses depending upon direct or indirect

the first thing we want to do is take a

look at indirect heating that means we

have a heat exchanger there's the medium

standard drying components are used the

plant is not airtight amount of the air

then it equals the amount of air

entering through the leakage or and or

direct air injection direct air

injection becomes part of the combustion

air operates under a slight vacuum so

let's take a look at this this beast so

all we're doing here is what are we

doing we have the standard pretty much

all the standard here it's essentially

open cycle then we add in this the fuel

comes in and air comes in and gets put

into a combustion chamber and it's burnt

separately then this stream three it's

indirect so there's a wall here between

these two streams and this heat

exchanger right now the kicker is

hopefully the scrubber condenser has

removed most of the particulate right

but maybe some of it has a been removed

so then you bleed astray

into here which will burn off let you

burn off that material so yeah the fuel

and air coming in you have cooling

coming in here okay you have the liquid

condensed water discharged which may

have particulate in it which then you

need of course the filter so this is

kind of indirect heating okay so if we

take a look

major majority meaning recycle indirect

heating we already talked about this and

used for aqueous feedstocks that have

odor toxicity problems but no explosion

fire hazards so the idea of the bleed

here this is a gas bleed right first off

you gotta realize the gas is all

contained here right however the gas may

it contain obnoxious material and you

may have to bleed some of it off right

eirick of a small bleed to the

atmosphere but that has to be exited

through a combustion use when indirect

he's necessary to prevent contact the

powder and combustion okay feedstocks

have odor toxicity problems but no

exposure ferrous small vent volume

containing toxic odour particles is

passed through the burner area and

deactivation there'd be odor izing takes

place popular choice and for herbicide

drying

now oh and you have direct eating right

DIRECTV yeah that's the limitation here

well

the inlet temperature maybe this is a

heat exchanger it's less efficient than

you think as a result it may limit your

capabilities and heating up the air

inlet temperature year so if I go to

DIRECTV now I no longer have a heat

exchanger I have DirecTV heats added

directly so I can have higher Inlet

driving temperatures you know thank you

higher thermal efficiencies the volume

exhaust gas is lower and partial recycle

design volume is vented equivalent of

volume of production products yeah I've

complete combustion is obtained very

little access to air is use the process

is self inert izing and self and there

tyson is desirable so let's take a look

at that we have basically recycles

Thomas we've once through recycle I'm

not once through obviously it's not semi

closed recycle you have the standard

products at the bottom you have the

standard liquid you have the standard

cooling what you have here is the air

and fuel coming in plus the recycle gas

okay hopefully you'll burn down the gas

to low oxygen level which means self

advertising you have no weight mainly

nitrogen in here and I cannot worry

about this bleed to the atmosphere I

would also have a tendency to put a

burner on that to make sure nothing gets

out that's bad stuff where you get rid

of bad stuff as you burn it

this liquid make and as bothers me here

as well you may contain a particulate

amount of material which I may they'll

probably be fine I could potentially

have a bag housed in here or I would put

you know bag house here would be very

very low concentration material and the

exit stream anyway think not that of a

gossip a houses are expensive and

difficult I would have a brain at burn

system their self and their tidy systems

is used for aqueous feeds when the dry

product must not contact air or oxygen

used to prevent the risk of powder

explosions or product segregation

through oxidation oxidation ideal for

minimizing emissions amount of air

leaking from the system is much smaller

than the amount of drying air system

usually as a direct fire-eater

preferably gas freezing combustion

control combustion control causes

recycle gas the low oxygen content

that's what you want oxygen is not your

friend constructed from a standard spray

drying compounds much cheaper than pure

air tight closed systems no demand for

nitrogen or other inert gases no need

for leak proof system high Inlet

temperatures can be used could eat

economy do die the temperatures chamber

operates under slight vacuum little

chance of the powder blowing out to the

atmosphere can be used can only be used

for aqueous feeds obviously organic

solvents need a true closed recycle

system right obviously you can't

you can't have this recycle stream you

can't have solvents in this stream here

they give a rope kicker to your heater

that wouldn't it you wouldn't

necessarily have solvents could burn off

right in there oh the interesting is

that if you test that statement okay

organic solids needing that true closed

system use for materials that exhibit

undesirable older generation and/or are

toxic during drying direct bending of

auxin pot exhaust is not permitted with

such materials removal of toxic

materials odor removal very high

temperatures can be used to deactivate

and deodorized special heat recovery

economizers used oxygen contents usually

out at 4% through the combustion

theaters combustion at the heater so

some comments about that where were we I

think we were here furthermore direct or

complete key activation and deodorizing

event volume is at ease around seven

hundred eighty eight hundred degrees

centigrade

recovery of this heat is done by

economizer built in the heater into the

heater economizer preheats and capacity

air part of the recycled medium okay

normally in like drying temperature

dryers lower than the desired or the

required eater temperature recycles

drying methi medium bypassing the heater

section is achieved to achieve a drying

temperature so you ask some sort of by

bypassing any feed-forward I

the exit temperature of a heater can be

quite AI whereas the inlet temperature

to the spray dryer is likely to be lower

than the exit heater temperature so you

need some sort of bypassing stream to

reduce the heat or temperature down to

the temperature necessary for the spray

dryer okay so this is when I was saying

that the complicated system so if I go

back up to this thing this heater here

maybe was running very hot I may be for

some of this flow around here to put it

in this stream and then I'd probably

have a some sort of mixer so I have the

Hyatts

hot gases in the cool gases and that way

I have the high exit temperature the

heater which has to be lived with but

then I diluted down to make the inlet

temperature to the dryer controllable

effect that stream bypass stream would

be quite useful in controlling the inlet

temperature to the spray dryer lots of

neat things that could be done again the

inlet drying temperature is lower than

the heater temperature exit heater

temperature now validation of

pharmaceutical systems well there there

are flow diagrams for those they're

quite complicated to explain for

products pharmaceuticals pesticides

dyestuffs other applications appear

since designs protect the environment

typical environmental hazards powder

emissions to the atmosphere odour

emissions to the atmosphere powder air

explosions or fire hazards toxic or

active material emissions to the

atmosphere so we got nasty stuff

coming into the atmosphere designs

prevent hazards from exiting the dryer

typically pass material through a flame

at high temperatures that they scare of

a lot of stuff okay typically to stage

layout see so all the designs that we've

covered at one stage capable of

producing the desired product quality

satisfactory particle size distribution

residual moisture and bulk density okay

hopefully obviously one stage dryers

represent the majority of spray dryers

in operation today hmm Mary oh there is

a need for improved quality product

quality increased thermal efficiencies

so increase the number increases in the

number and complexity of products have

occurred time specifications have also

become more difficult you don't want the

material in the dryer too long and it

may take a change the taste the texture

the flavor the odor in other words we

were talking about toxic odors or

toxicity just the reverse of that is you

want a certain fragrance or you want a

certain flavor you want to you don't

want it in there too long because you

may lose those more delicate properties

that they're desirable in your product

so the retention time should be kept

really low here same so overall that's

what the Tyne specifications overall is

more difficult to try with only one

stage so there we go

when this occurs difficulty in driving

with one stage to try stage dryers

should be used common the combination is

spray dryers followed by a fluid bet

there's some designs

now what I have run across we have with

spray beds where you have the spray

dryer up here and then a fluidized bed

at the bottom of the spray dryer and

they're called spray beds now there are

advantages and disadvantages when I have

them separated like this I can control

this part of the system independent of

changes in this system if I had a spray

bad if I change the spray

characteristics I immediately upset the

spray bed by keeping them separate that

does not happen so over here we have a

three a stationary bad back mix blood

flow design hmm I don't know what they

mean plug flow when they say fluid bed

that's interesting back mixed as well

understood it with that fluid bed but

stationary vibrating fluid bed over here

you have AI braiders fluid bed cyclones

or four there you have a a heater this

is indicating a heat exchanger this is

also indicating exchanger of some sort

maybe he gasps anyway go through here so

and the reason why you would have a

spray dryer followed by a fluidized bed

is that fluidized beds insta sized insta

sized your material in other words

you'll make a very fine particle up here

and what you want to do is agglomerate

them okay cause them to a long way so

this fluid bed may actually contain a

have a binder spray in it and which

glues particles together but not and the

bed itself has enough agitation that the

particle size reaches a certain size and

that's it and you have glued a number of

particles together

that are highly porous structure and

it's highly desirable for installation

you're going to have stuff that's inside

dissolves quickly so one two-stage

riders I attaches fluid bed to the spray

dryer two types well there's a lot of

types of fluid ice beds but the ones

listed here and yeah and then the

concept of spray beds like again spray

beds would be put the fluid ice bed

inside the dryer spray dryer so you have

a spray bed now the reason for that is

you eliminate all costs capital costs

involved or you reduce imbalance that

substantially with a spray bed however

as I said earlier the sensitivities of

operating two different systems why you

spray dryer and fluid bed together in

one same same unit can be quite

cumbersome oh yeah I've talked to

several people about this and then when

chap says us terrible so sensitive you

can't get in you know it can only be run

at 1/5 there's one fixed set of

conditions and nothing more you know

hope to pray you're at those conditions

because it's extremely delicate another

person says hey it's the best thing

since sliced bread

so now anyway you have different people

giving you different evaluations on the

same piece of equipment it could be the

fact that the applications are different

but anyway this stage drains helpful low

residual moisture content in the

particle lower particle temperatures

changes the particle size distribution

either by classification or

agglomeration and approved several

efficiencies spray

just can't do everything retirees can't

do everything he can't resist your

moisture try to lessen play 1% cannot be

achieved in spray dry allowing residents

times of need staying an external fluid

bed chiefing low moisture content

usually requires bone dry air relatively

low humidity by the way the air you

might realize air is filthy right so you

might want to filter your air you might

even dehumidifier your air I will talk

about those effects a little later

powder may be cooled to a certain

temperature prior to packing your

storage would be cooler it's just the

equipment for that factor of continuous

use for powder temperatures above 50

degrees

that's centigrade for a lower if you

want powder temperatures below 50

degrees the conditioned air may be

required power dirt temperatures are

lowest in co-current dryers okay proof

powder form and mayhap and beef through

classification or glomer ation you're

going to classify something you probably

want a certain fraction and you recycle

the rest of it collaboration is kind of

tricky but that's you should listen to

my courses on agglomeration I have three

different accommodation videos

classification fluid bed velocities can

be adjusted to control fine scary off

removal findings can be returned in a

drying chamber for a real long raishin

resore collected separately fine i

always like this finds may be used and

really long rationed

I think the fines that's nothing to do

with drying you take them to another

another process and you agglomerate them

and you may have a new product

Spider Riders operated a little outlet

temperature to obtain moisture in the

product the moisture can be used in

making a glamour and a spray dryer

afterwards in a fluid bed dry on the

outside wet on the inside the moisture

will migrate out and help to alum rate

the powders fluidized beds are excellent

agglomerates one chap said performing

agglomeration that cannot be obtained by

other methods and this is the idea of

insta sizing your what that means it's

dissolves really quickly so there's a

concern about drying rate or dissolution

rate I should say fines are out of

control

however they can be exonerated thermal

efficiencies improve additional with

additional equipment and temperature

drops higher Inlet temperatures lead to

product degradation lower Inlet outlet

temperatures increase residual moisture

so you're looking for higher Inlet and

lower exit temperatures and two-stage

drying improves thermal efficiencies no

loss of quality and the product

increasing capacity of the dryer

new developments as I already talked

about this spray beds fluidized bed

inside spray tower saves on casa having

two separate units looks good on paper

kiss principles violated keep it simple

KISS principle keep it simple you do not

want complexity in operations in

industry they want to be simple

operations everything simple steps that

way you'll have pure air processing

problems maybe he's very touchy to

operate when you have a spray bed right

and he tend to lack nimbleness

flexibility robustness right aseptic

design basically giant a product under

extremely clean conditions product is

free from

lamination foreign matter basically

going made possible through the use of

high-temperature HEPA filters I

efficiency particulate air filter

sterilized liquid filters in contaminate

contaminant free atomization and

discharge hepa filters everywhere so

three we have up here we have of

sterilized filter cap figure out that is

and whether it's sterile or not you have

a bad stream coming in and the question

is is it sterile this is sterile and it

leaves of course there's a I got a story

to tell you the operator one of the

operator cartridge folder he had 50 150

cartridges to put in this cartridge

filter he got tired of doing it and so

next time he changed out the filters

filter cartridges he put in on only 149

cartridges instead of they have required

150 he didn't have to change out the

filters anymore nobody ever noticed

right so I'm sure that should not be

encouraged but it does happen right so

we have a HEPA filter here this is 6

that's a heater 5 a is the HEPA 5 a is a

pre-filter atomizing air 2 fluid nozzle

a what PI B is pre-filter dryer don't

worry about how they filter that and 7

is that the filters here we go and here

we go

they're filtering after the heat

exchanger burn filtering after heat

exchanger so you have feed dry products

eight what's a clean

for packing 6 or indirect heaters and

direct air heaters no combustion

products and direct heaters are probably

required to hepa filters filtering the

streams making sure the X is protected

pretty well covered at all every stream

has been this Q here is leaving so

that's not much of a problem

hopefully q resembles it's too fluid

atomizer you have air going up here

problem is you don't have a high

pressure air often times in two fluid

nozzles you need the air or guess the

liquid flow rates to be two that's just

a rule of thumb it would appear to be

two from the technical data fish I mean

if it was point one the air wouldn't

have any effect whatsoever right but if

it's two three ten then the air will

have an effect okay but you have to

sources of air air which means two

sources of contamination with this five

B okay

anyway special Cooley designs used for

each sensitive products or mo plastics

hydroscopic materials and materials

having low softening points used for

products oh yeah

softening point used for products that

have a tendency to form deposits on the

dryer law ever got posits can mean

lengthy residence times and possible

degradation of quality fines return

fines are out of control it's a very

famous statement

sir control finds a return to the

process promotes elaboration since the

process products often exhibit self

binding characteristics leads to a

coarser production of course leads to a

production of coarser and free-flowing

powders often dust free so here's the

three methods one finds he shoot right

up into the abner atomizer Itemizer is

discharging this will by the way if this

is a real atomizer it's moving a whole

bunch of air as well so the finds will

go possibly in the Airstream okay you

could inject finds right and the

perimeter of the atomizer again or the

finds go in the bottom down here reject

them at the bottom hmm okay three ways

those finds up under the atomizer wheel

avoids the possibility of science

entering hot air we're a product

aggregation occurs introduce the

findings to the chamber ceiling we turn

the finds of the face in the drying

chamber collaboration may occur later in

fluid beds in other words right here

these finds have to go out at the bottom

and by the fact that they're inside this

fluid bed which may be at higher

temperatures they may a gamma ray or

catch on to larger particles piggyback a

larger particles okay some effects of

operating variables close attention

to be paid to atomization spray air

contacting evaporation and product air

separation and babies each operation

affects the properties product to some

degree atomization feed characteristics

feed properties have effects on particle

size distribution bulk density

appearance moisture and other properties

right the ones that are non measurable

spray contact evaporation effects on Bob

density appearance moisture viability

aroma flavor texture other non

measurable quantities skipped again

spray air contacting effects on both

density appearance moisture fly ability

around my other flavors okay product

separation effects particle attrition

and fines important variables are

summarized below be careful these are

generated generalizations anyway okay

product air separation effects particle

attrition fines important variables are

summarized below be careful these are

generalizations atomization energy and

operating variables increasing energy

rotational speed nozzle pressure al R or

air liquid ratio or gas the liquid ratio

in two fluid nozzles will most leaning

decrease particle size but at some point

diminishing returns occur the shape of

the particle size of U distribution may

not change much producing greater

amounts of fines may form a product of

higher bulk density again the smaller

particles may well be more dense than

the larger ones and the smaller

particles may fill the voids between

larger particles

e increases in fee viscosity increases

in solids these solids the reduction in

temperature will produce coarser

particles surface tension doesn't change

much in value often but often control as

a final particle or drop size the Weber

number effect low viscosity materials

typically making drops it's a Weber

number effective crop diameter is

proportional Weber number to minus 5/6

power minus 0.5 power and increase in

feed solids increases both density and

kerosene feed rate produces coarser

particles okay more what are the

favorite course of the particles rotary

and nozzles have different that

different is good next slide

patterns both are flexible and could

produce sprays similar characteristics

generally rotaries produce finer

particles nozzles produce coarser

particles all right let's move on down

here okay rotaries are preferred for

large drying requirements nozzles

require duplication repeated nozzles so

instead of one nozzle you'll be looking

at a nozzle header with many many

nozzles which complicates things a bit

of course rotary is complicated by the

fact that they have a 360 degree flat

spray coming off which needs to be bent

ok nozzles require duplication to be

larger spray requirements training

requirements many spray nozzles can be

altered by changing the vane design on

wheels huh that means you have to buy

another wheel and good anyway number

Heights with lengths of vanes determine

the amount of liquid at the point of

atomization

ok air flow rates control to some extent

the residence time of the product in the

drying chamber

an increase in residence time leads to

greater reduction in moisture content

okay it makes sense all this makes

relatively interesting the outcomes seem

reasonable reduce air velocities help

protect product recovery from drying

chamber help product recovery from drain

chambers air flurry impart determines

how the product is being handle and the

properties of the product well the air

causing vertical attrition and nutrition

is going to produce a lot of fines than

more gentle or air-quote gentle or air

or whatever that actually means you're

looking for bigger particles less

attrition then the dry drying

temperatures increase increase in

Illinois dryer temperatures think

increase their drying capacity to the

dryer now that's true and let higher

Inlet temperatures lead to higher

efficiencies increased temperatures

cause higher evaporation rates they

often cause a reduction in bulk density

high evaporation leads to more porous

particles fast evaporation more bubbling

so to speak so I like the Mineta

molasses analogy higher vibration rates

cause more porous and fragmented

particles a la drying temperature should

be kept it in their range to maintain

powder packing and flow requirements the

increasing outlet temperature decreases

moisture content okay also means more

airflow rate probably lower outlet

temperatures produce a powder high and

moisture content which may be needed

subsequent glomer ation processes such

as insulation ancillary equipment may be

needed to handle i powders high moisture

powders and spray drying followed by

fluid

as a natural fit other dryers may also

fall of spray dryer as well for example

belt dryer these combinations have been

less studied in anyway let's go onto

some wheel effects wheel designs

atomizer pumping air pumping and spray

air contacting spray and air contacting

wheels are going around extremely high

rpm then they pump a lot of air that's

one of the first things we go to state

right now the amount of air is large

very much very large anyway wheel

designs numerous designs are available

designs to have a design that imparts a

product with a desirable process prior

desirable characteristics standard will

design the straight veins usually 18 to

36 range due to fabricate no special

liquid distribution techniques clog free

air pumping in a rectangular or oval

channels that's a problem air will air

at the air or gas will aerate your feed

you're no longer feeding a liquid stream

on the wheel but you're being feeding

foam on the wheel nozzle atomizer will

small diameter orifices instead of

channels air pumping substantially

reduced less flow area higher the

density ya product aeration is minimized

this is a good sign and this is the

highest possible bulk density usually

you're after high bulk densities you do

not want low bulk densities basically

because of packing you know if you're

shipping to 20 pounds in a cubic foot

that's pretty low packing rate overall

density

we go back and catch that or you have

wheel nozzle atomizer wheel okay

balls only relatively small feed rates

okay many wheels are used over straight

vanes used for higher bulk density IR

production intensifies the product pairs

as the feed approaches the excellent

channel exit you're looking at seven to

10% increase in bulk densities over

straight straight vanes polluted air and

product has reduced important to

products containing fat whole milk for

example steam wheels steam flows

alongside the wheels on side feed and

the wheels replaces air around the

wheels steam minimizes particle

expansion during initial stages of

drying or the initial stages of boiling

results in higher bulk densities you can

actually form more solid particles

factor for products that exhibit film

foiling characteristics film forming

characteristics you put a pot on the

stove pot of milk on the stove and cook

a heated you'll shoot you'll produce a

film on top of the milk just to give you

an idea of something that forms a foam

steam reduces air pumping ok wheels for

corrosive feed fabricate the wheel from

corrosive resistance metal postulate

eight postulate and titanium Bane wheels

for breastfeeds well significant where

corrosion occurs at ten twenty meters

you can put that in your memory bank

that means 30 feet to sixty feet a

second

one solution is use wear resistant

inserts wear plates inserts are

replaceable obviously their braces

designs wear resistant centered bushings

used in deaeration also are used here 24

bushings for wheel it's not uncommon

bushings are rotated after significant

wear and bushings can be made of all

sorts of stuff

right solid wear a lot liners create

created from the feet itself basically

oftentimes the way you create a liner

for some vessel or whatever is you let

the feed build up on it for a while

during the startup of dry spray also

used large capacity wheels he has double

tier or more wheel designs each levels

fed by a distributor I use multiple

levels a liquid loading on each vane is

kept low complete atomization occurs at

I feed rates possible problem was wheels

flooding that's often the interesting

point if say you had and suddenly a

massive buildup on your material on your

wheel it's not flow channels are

significantly reduced will will become

flooded that's kind of an interesting

idea where feed rate is larger than the

amount of atomized so you having a lot

of atomized put the feed rates larger

than that designs to prevent flooding is

a vendor question anyway there's a tip

that I took these pictures from narrow I

think appreciate their contribution I

think these that pushing this is an

indication of bushing and okay and

pushing some other wheels indicate

bushings in there

double-decker there

these look like they're hot anyway by

hot I mean there's information on them

disk atomization vaneless bowls cups and

plates well you got to recognize that at

the perimeter here of these disks and

things they're direct drop production

the big drops a few daughters but big

drops they can also have ligaments

coming off very feet very uniform

ligaments

that's how cotton Keeney is made how

party string is maybe there's no break

up and the liquid can come off as a

liquid sheep now again if your atomizing

a slurry I'm always interested in the

particle size versus the drop size and

atomization of slurries I'm quite sure

there's a solid what is it the diameter

of the solid that the diameters drop

becomes important and some slurry that's

how much it can be considered a

homogeneous liquid and other slurries

they can and then you have particles

particle shape effects where you

suddenly have flat plates lining up with

each other or needles lining up with

each other so anyway again I encourage

you to look with my video on atomization

and the feed rate this diameter

rotational speed that goes back there's

calculations for when drops are produced

when ligaments are produced or when

sheets are formed basically said the

inside a bowl pressed against the ball

flows outward to the edge of the ball

plates can also be used difference

between plates cups is the cone angle

plates have 180 degrees

bowls and cups let's um give you an

example this is the underneath it is 360

degrees and then if you have one of

these that bangle come off

however dictated by the geometry disk

atomization little use in commercial Dre

spray drying operations well this really

depends upon whether you are a uniform

prop size or not if you want to use

these this one right here ligaments give

you uniform drop size okay

and for some commercial applications

uniform drop size the equivalent to a

lot of money okay

I've been around several companies where

they're seeking ten micron drops plus or

minus one micron very sharp

distributions ah and they have reasons

for that anyway so well it depends right

little use in commercial spray drying

operate well it depends upon what

commercial means often applied for

coarse particles at high production

rates multi-tiered plates are used for

high-capacity dryers used in special

applications can be used for coarse

fairly homogeneous sprays problems with

the Bayesian will occur

can spray patterns they and I have not

been used in a large degree in spray

drying now having said that I suspected

somebody out there uses flat sprays

let's fly what sprays can let you zoom

your dryer a sprayer you have say a

square box or square rectangle you have

flat space that space flats way anyway

every time you say it's not used

somebody will pop up with an application

that uses it and there will be some

advantage that they cite it's being a

reason for why they use it so that's the

way industry is there's a whole variety

of different things that actually work

alright holocrons well-suited for

co-current operations spray cones can

rarely align itself with co-current flow

drops readily contact the drying air

when they're slowly in the same

direction sort of spaced from solid cone

nozzles have less interaction okay solid

cones are useful for counter current

operations where the spray meets the

full face of the drying air when a

hollow cone sprays contact counter

current here at greater degree wall

deposits may occur right hollow cone in

contact with counter current upward air

expand out the cone angle unfortunately

it would increase more flow to the wall

and obviously this is a small chamber

effect especially in small chambers you

know where you worry about size effects

here or small chamber you're always

going to have serious wall buildup

problems problems are important unless

you have them all right mixed flow

chambers if solid seats co-current first

nice hollow counts the space he's

counter card first use a solid cone

right

okay anyway manages the two fluid

nozzles I was in Europe giving this

course and the chap chap came up to me

and said the biggest trend in the

industry is to fluid nozzles nice is

okay and he was disappointed in my

response that I did not thoroughly agree

with him I agree with most everybody

because most everybody is often right

all right your grade so you know two

fluid ounces big trends okay let's talk

about it produce a spray of i uniformity

I am ionization small drop size this is

true if the second fluid the fluid

that's doing the atomizing it's doing a

good job if we gas the liquid ratio is

not high enough what you have is the

dripping okay I ran across the petroleum

company that was using a how can I put a

plant made or hell made a two fluid

atomizer burning off their nasties in a

combustion chamber and the nasties that

are dripping since a tripping component

to there was a puddle of nasty stuff on

the right below the atomizer so is it

too fluid atomizer is doing a great job

except for the fact that whatever reason

the thing tripped and if you have a low

gas to liquid ratio and you will the gas

is ineffective and your atomization

depends upon the liquid stream and the

liquid screening may not be up to snuff

so to speak up to the abilities of doing

its own atomization okay usually I have

large orifices for feed there's two

types of two fluids internal and

external

these are nozzles of course to internal

mixed an external mixed

internal mixed has a problem with one

stream may back up into another stream

that ain't healthy does not need I

pressure feed pump that's true what it

needs is a high pressure gas pump that's

why it needs the high pressure has got

to be available you're not relying on

the liquid to do the atomization ie

you're not you're not relying on the

feed to do the atomization you're

relying on the gas to be doing the

atomization but I really like through

fluid atomization atomizers you have

Mary we're in a petrochemical industry

that's really they're not called to a

fluid atomization they're atomizers are

called flash drums you have this huge

pressure drop across the Norris of

hydrocarbons and they basically flash

off the low hydrocarbon and the the

heavy stick around big old drops

anyway flash comes another really kick a

kick about two fluid atomizers is

instead of weighing about pressure I a

high pressure drop you run it boiling in

other words you flash John runs boiling

right you put the gas in there where you

put two liquids in there and you heat up

one of one of the liquids has a boiling

point lower boiling point and it will be

the one that flashes as it goes through

the orifice so you heat it up under

pressure above its boiling point push it

push it through the orifice and wallah

you have one heck of an atomizer I'll

tell you forget about pumps forget about

high pressures

well you gotta worry about back

pressures as the things going to atomize

you want to obviously have the flow go

out the orifice so you have enough

pressure to prevent the backflash might

be considered anyway these two fluid

nozzles are

they sell them right okay it's too fluid

atomizers but there's a lot of homemade

to fluid atomizers out there that are

not called atomizers okay there he puts

again you put two liquids through an

orifice then you heat them before going

through and you heat one above the

liquid to phase liquid above the boiling

point of one of those phases you got our

wine eyelashes atomizer disadvantages to

fluid atomizers usually have small angle

i or orifices for gas stream more

tendency for plugging by the way all the

disadvantages here obviously okay all

right may or may not be significant

right need filtered compressed air or

clean steam again you have steam and you

have stream obviously you can atomized

with whatever you want steam is not

uncommon that's available too and it's

already got a lot of heat energy and

high cost of an air compressor i cost of

producing atomized there any

requirements for atomized air cold

atomizer air reduces evaporative cooling

capabilities as much as twenty percent

now a little nozzle efficiencies put

this whole area of two fluid nozzles are

kind of cool because there's a lot of

different techniques and strategies you

might want to go about especially if you

run boiling boiling through an atomizer

two fluid rotating cup atomizers

rotating cup with air direction at the

rim things are very fine spray low

viscosity atomizes i viscosity course

drops okay spray angles maybe saw very

small can be do

located for larger dryers disadvantage

of the two-fluid rotating atomizers the

same as two fluid nozzle atomizers right

for the same advantages as well be run

boiling would be quite interesting

selection of an atomizer well simple

construction easy maintenance that

leaves out wheels sorry

wheels require delicate you know after

rotating at 40,000 rpm you just don't

pick a person off the street to do the

maintenance you know what I mean

[Music]

will right balance the wheel you use a

wheel balancer again I suggest you

review the course on atomization various

available in various sizes of course

that's what you're looking for vertical

size control some changes and operating

conditions operated using standard

feeding equipment atomizer suitable for

operational flexibility handles where

drop release is compatible to Draya

Draya dryer chamber right spray pattern

compatible to dryer chamber atomizer

provides complete atomization power

requirements are reasonable again pyro

requirements very important pressure

drop columns while your nitric flow rate

pressure drop if I have a nozzle it's a

pressure drop across the nozzle across

the nozzle not in the piping system

across the nozzle times volumetric flow

rate is the power requirement or power

being used by that nozzle similar

calculations can be done with wheels

power central to engineering and should

always be calculated for your equipment

and then I assure you where I would

guess that you haven't calculated the

power requirement or the power of wheels

right

which would be

some sort of Rho V squared my times

volumetric flow rate Rho density

velocity squared volumetric flow rate

might Plus you check your units units or

your friends anyway ditional comments

rotary and nozzle provide all capacity

requirements of low intermediate and

high flow rates okay that's good got a

lot of versatility right here atomizers

are better at high capacities okay

nozzles reach duplication high

capacities at duplication okay fire

requirements are the same order of

magnitude apparently a power rarely

determines that amaze or selection you

need to do the power calculations though

just so you don't remain ignorant

apologize for that I'm sure nobody said

there's any more in the world nozzle

efficiency is really important if

nozzles successful I mean if you got a

working system then don't fight it you

know I've always wondered people

improving the wheel they wanted more

roundness to a wheel by the way trying

to obtain more or wine round this to a

wheel is it's not to think about it drop

size distributions are similar at low

and animated flow rates yeah Weber

number effects maximum minimum drive

sizes their selection criteria find

sprays you have these atomizers

intermediate sizes you have these

atomizers course sigh course sizes

pressure nozzles bang discs fine sprays

I would go with a cup

amazing when I essentially create a mist

and the again ligament I would try to

have a uniform drop size around 50

microns probably for very fine sprays

and I would be looking for if I was to

try to incorporate that in a liquid I

would want to have it touched by caching

mechanism falling liquid curtain to

catch the material whether the atomizer

more flexible too often just changing it

will speed nozzles are more adaptable

hmm basically what they mean is nozzles

can be changed out easily positioned

mixed counter-current co-current are

possible nozzles are just a hunk of

metal right no moving parts the pressure

was generated elsewhere right rotary

atomizers require and generate a

rotating air power rotary atomizer of

course then nozzles as well is going to

generate a lot of airflow or gas flow

low viscosity non corrosive abrasive

fields wheels and nozzles that equals

success wheels can handle corrosive

abrasive in powder feeds mills and

pneumatic to fluid nozzles can handle

materials that cause pumping problems

right this is high pressure high

viscosity materials that caused pumping

problems pneumatically to fluid nozzles

are used for four-eyed viscosity and

non-newtonian materials useful to base

atomizer selection on past experience

there you go lab and pilot plant

experience atomizer selection is not an

exact science for example time spray

drying milk in the US I'll probably use

the nozzle if I'm spray drying in your

probably use wheels so there's no real

exact science

each atomizer field dryer combination as

cases where performance suffers hence

are unsuitable obviously pressure

nozzles are unsuitable for slurries

fiber slurries nozzles will clog now

these will clog below 0.3 millimeters

and they'll clogged with just simply

water water contains enough

contamination of 0.3 millimeter that can

easily clog pneumatic two fluid nozzles

should not be used for feed that cannot

withstand high impact there's high

impact between the month lower than

another and for instance if you had

protein molecules or long-chain polymer

molecules or other stuff ah

and they might have the high pressure

drop might rip apart the the polymer

chains needs continued long-chain

polymer polymer polymers form threads

it's interesting threads famed paint

atomizers this is cotton candy type

behavior here right if you look at you

got an assignment I want you to do I

want you to go buy some cotton candy and

I want you to see how uniform those

threads are and the sugar fibers that

make up cotton candy then I want you to

go to the carnival where the cotton

candy is made and I want you to watch

the ice be rotating Cup that they make

cotton candy from then I want you to

figure out the diameter of the threads

in cotton candy and then I want you to

figure out what the controlling

parameter is between making threads and

making drops

and I suspect it may be something to do

with higher viscosities as you approach

the drying of candy of sugar water she's

drying sugar water you're going to

approach higher viscosity is cousin sir

concentration goes up and up and up all

kinds of cool stuff you can do and

retrofit selections based upon what fits

the existing design ah yes retrofits

oftentimes whatever the design was for a

plant that's been changed it's been

changed by a retrofit and if that didn't

work out it's been changed again to

another retrofit so plants often undergo

changes and rather dramatic changes

especially when they're not working and

the idea of retrofits is very common

there is no such thing as a fixed

process you're always looking for ways

of getting better performance the dryer

chamber determines the atomizer the

position of inlet and exit air ducts of

the Eternity often determines the

atomizer fire chamber determines the

atomizer if you have a tall tower dryer

you use nozzles before then the new

atomizer will use nozzles so we collapse

all this stuff down what do we got we

quickly find a comment on atomizer

selection not often a clear-cut choice

often done by the elimination of poor

choices there you go poor choices you're

playing a nice process Sherlock Holmes

so to speak

air pumping effects we'll take a short

break here and resume ok let's talk a

little bit about air pumping effects

first off a little is not okay little is

understood energy going to pumping air

can be relatively can be high relative

to energy going to atomization so

there's an area different excuse me

there's an energy difference there but

air pumping can aerate the fluid or can

aerate the liquid in the atomizer the

feed then becomes a foam which can

affect product quality obviously a foam

feed will reduce bulk density or

probably will reduce both density and

will design can help reduce the aeration

effects so they will air pumping effects

in spray dry or spray drying air mixing

near the wheel my effects the spray dry

spray air contacting or mixing near the

wheel this mixing effect appears in

pilot scale equipment or where the

distance from the wheel to the wall is

small air pumping and liquid inter Inlet

air can interact and form recirculation

flow flows that can cause material

deposits on the walls step to minimizing

air pumping better designs minimum

clearances between the wheels and

casings will designs to minimize

aeration bleed cold air the wheel casing

clearances fill fill in the

recirculation volumes well that may not

be a great idea take that back

display air contact very important if it

determines the rate of drying the

extended drying space shape chamber air

dispersing designs must create a flow

pattern

which prevents wall all deposits many

drier designs and interdependencies doe

general relations relationships are

available the amount of published

literature's in fest limited most about

small dryers fine sprays move under

complete influence the air coarse sprays

are more independent of the airflow

correct their dispersing stands out as

an essential requirement for successful

spray drying that's both true and again

this is where the spray drying companies

the vendors come in handy and we have

some fun there we have air coming in

counter-current

air leaving these are more or less

pictures of Coker encounter current

operations here we have a rotary

disperser right below the slurry feed

here we have a vane rain gas dispersed

there the air comes in tangentially goes

around the ring here we have spray spray

nozzles inside we have the gas coming

alongside those spray nozzles to fluid

pneumatic spraying there are nozzle

dryers anyway so we have these are from

masters boat so just took those thank

you for thank masters for this knowledge

in the ceiling volute air rotation by

angle Danes cone angle is bent to match

the chamber air and spray any way you

have the idea coming in through veins up

here our veins are actually in the cone

and you want enough air this is the

horizontal spray you want enough air to

boat AB and the spray you have cele

vanes upper wall pollutant

you have a balloon up here hot air in as

this tangential flow probably that would

prevent hot or cold air and a hot air

coming through the veins tangential air

in flow rotates in the chamber again the

cone angle is bent to the chamber okay

one of the interesting comments that was

once made they had spray nozzle or spray

wheel below a entry region and due to a

back circulation entry region draught

uber tube basically a large diameter

tube then the wheel set just below that

tangent that inlet tube there was a back

circulation and the back circulation

called will cost wah-wah buildup of

material on that tube and a huge inlet

tube duck basically wall circulation

caused build up along the outside

perimeter of that tube in the way you

saw the problem and you just go in and

cut off the portion there the build-up

occurred oh but that will ruin the

warranty well which do you want a

process which has a wall built up in

there substantially or do you want one

that is not under warranty and doesn't

have the wall build up there we have a

center air dispersor comes in here

rotation controlled by angled vanes and

rotates in the chamber so of the three a

and B are better than the CC as the

potential having more wall buildup

material C and this here the air is

bending the flow here the air is coming

in bending the flow downward here the

air is going upward or maybe have an

upward component to it it doesn't bend

the cone the spray downward but it may

actually bend it up in the reverse

direction so then it's more likely to

have wall built up here and here since

the opportunity of bending the spray

angle has been missed so has the

advantage of how they're going right to

the spray there you go so the crack and

wheel discharged rotating same direction

you have more control a counter current

discharge more mixing along Benjamin

more often decreases I was going to say

actually increases but more decreed may

often greater density of materials that

build up on the surface of the atomizer

here we have a couple more there we have

a bloomin one two three basically here

we have a perforated she straining veins

perforated sheets as well

perforated sheet straightening bins bent

the vanes are used the river air is

dispersed across the cross section what

you want to have well you got to decide

what you want out but one thing is often

the choices have uniform air have

uniform and you need probably out of

some pressure drop across the sheet

fluidized beds typically you're looking

for it to get uniform airflow through a

fluidized bed you want one third to

pressure drop across the support grid

here I'm not sure exactly how I get

uniform thrown but I want maybe even

targeted flow maybe I don't want

anything at the wall but a lot in

to bend the liquid angle there let's

catch what I said up there

okay covered that yeah I would have

walls dispersor tangential or volute in

without air central dispersor here wall

Brussels dispersion another one

horizontal veins when vertical rings

bust old pipe are commonly used

Priscilla Priscilla and again we have

ceiling or based dispersants depending

upon the nozzle location there we have

the B is a fountain type now I guess we

have to think that this is also a

fountain type all these are sort of

fountain types so they're all and third

into gravity but today is not anyway it

doesn't hurt to do visual studies using

a small plastic model to gain some sort

of information now what size do you go

to well I bought it Plexiglas tank there

was three foot in diameter that cost me

$900 at the time he just take a sheet of

plastic and bend it over and seal it a

lot of information possibly using

plastic models I would expect the

vendors already have their plastic

models but the idea would be you have

all sorts of ways of putting in air and

all sorts of geometries and you put in a

the problem would be the surface would

be com opaque after startup so you run a

tempt I mean you run it just with plain

air you could run it with confetti in

there to be flow markers that way you

can see on

inside what the different flow patterns

are and how those change and you do it

on a relatively large scale like I said

three meters a three feet diameter would

probably be a nice size understand

things and then the flow markers he

would done you obviously can't use the

the the particles themselves cuz you

wouldn't be able to see in so you use

confetti low concentrations of pathetic

maybe you can see what happens

the old common statement is of pictures

are worth a thousand words and if you

have a video you have lots and lots of

pictures so how are you gaining

understanding the idea of a confetti air

circulation in a tank you make the tanks

such that you have this large

cylindrical tank and then you have

inserts to give you a a slanted wall

this person here around the nozzle leads

to faster drying rates better

utilization of chamber volume lots of

interesting interest interesting

combinations but if you notice this

presentation this it's the week this is

the area of weaknesses spray drying

really it is and hence the the weakness

of the presentation no no I did my best

in our subject you know anyway I'm just

kidding

hmm operating effects and effects on

dried product properties effects depend

upon product drying characteristics

particle size is controlled by wheel

speed four wheels I feed rates may

result in higher residual moisture

content I our bulk density increased

feed temperatures may increase bulk

density improve atomization

decrease bulk densities for easy

analyzable

feeds right so increase/decrease made

here 8 to feed and increase bulk density

when it says improve atomization what

that means is smaller drop size bulk

densities increase upon powder cooling

it's interesting again I want you to do

my experiment there's experiment I want

you do I want you to take some ground

coffee in one of those what the big

coffee cans you see you know about a

player in 10 inches in diameter maybe 10

inches high and I want you to empty out

the coffee grounds you buy a new filled

up totally you empty out about 50% of

the coffee grounds you put the time

major the heights off the bottom put the

top on the coffee ground can plastic top

usually and then I rotated ya rotated

around around around around and then

after about 10 to 20 revolutions you put

it down on the countertop take the lid

off and I want you to notice the ice

change that's occurred due to the

tumbling action alright so that's a

comment on bulk density here I have a

can of coffee under one set of bulk

densities and then if I rotate it by the

rotation I probably increase to static

charge on the particles hence they have

a tendency to expand away from each

other and I have a lower bulk density

now I don't know whether you live in a

humid climate or not but suppose you're

dry it's dry on the inside you're in an

air conditioning and that usually means

dry dry earth and I want you to do the

same trick and expand it out amount of

coffee and your coffee can and then I

measured major the heights and then I

want you to put outside where you have

high humidity and that is what happens

after a while as the humidity diffuses

into the

the static charge is shorted out so to

speak because of the moisture and that

coffee tends to collapse so this

business about a moving stream an

electrical charge you need to pay

attention to that not only could that

capably could possibly kill you it also

will affect your bulk densities okay so

lots of people have died of static

charge discharges whenever you have

anything moving you'll have a static

charge potential static charge buildup

that's how electrical generators work

basically I have some moving sucks

charge anyway case in point this is a

chemistry laboratory the director

research walked into this organic

chemistry lab and there was a crackling

sound and the director asked the chemist

what that sound was and the chemist said

that he didn't really know and so the

director of chemistry what the director

walked over and turned the lights off

and there was this plastic pipe that was

lit up like a fluorescent light bulb

light tube and it was lit up with tiny

Sparks and it was a plastic pipe with

benzene running through it so he could

imagine all they needed was the a batiks

the end of that plastic pipe exposes to

an oxygen source and away you go it

would not necessarily be a pretty sight

okay let's see where were we

powder from rotary atomizers usually

have a higher bulk density than the

power from nozzles bulk density depends

upon particle size bulk density also

that depends upon particle shape depends

upon particle charge electrostatics

depends upon

obviously lots of things viability

depends in part upon particle size but

powder bulk density depends upon packing

upon packing depends on particle size

distribution wider distributions have

higher bulk densities smaller particle

sizes fitting in between larger particle

sizes hence higher bulk densities

increase in feed solids increased bulk

density there you go there are

exceptions the aeration decreases bulk

density spray foam for very porous

particles as possible in other words if

you have very porous particles then you

definitely want to spray foam suspension

to give you higher ball Kenzie's and

solutions interesting do your mechanism

of drying increasing moisture content

increases bulk density okay we also

reduce air pumping increases bulk

density replacing air within a wheel

with steam now there's a steam injection

around the atomizer increases bulk

density the injection of steam will slow

down the boiling to some degree and it

won't be as foamy as the boiling

molasses analogy so I was slowing it

down that means there's going to be more

solids less foamy means slower diameters

same solace lower diameters increasing

inlet air temperature decreases bulk

density reducing outlet air temperature

increases residual moisture content and

increases bulk density having contacting

where the letter s' drops meet the

hottest air minimizes bulk density so

this would be Co current dryer began you

I am have causes the boiling bubbling

and as a result

see the drops aren't evaporating they're

really doing it phase changed there

excuse me that

moisture is not really evaporating in

the sense of hot vapor coming off a cup

of coffee but instead it's more like

boiling from the vapor coming off of

boiling situational illiquid pot water

on the stove big difference between a

cup of coffee cooling down and boiling a

wire on the stove high counter current

drying increases bulk density mechanical

handling causes attrition

it increases both density reduction and

static charge increases bulk density

static electricity is something that

there's not very many people are

accustomed to or talked about so you

need to pay attention through this

additional tricks to increase both

density at a binding agent this improves

the particle strength reduces of

prevents ballooning I guess that means

boiling during evaporation so this

probably came from masters book

ballooning now I'm not sure I guess they

mean boiling during evaporation allows

the operations that higher solids

content injecting steam we've mentioned

already replaces air increases both

density by 30% drops have less Kalinin

air I would say included air I would so

cluded and feed pre crystallized feed

solution as a cold suspension

comfortable suspension can decrease

Vulcan City okay interesting just as a

comment pressure swirl nozzle as

centrifugal force inside of it this is a

pressure swirl because of the swirling

action you have significant potentially

D mixing going on in your flow in a

pressure swirl nozzle so portions of

your

leaving liquid sheep one side will be

high solids and the interior side will

be just liquids so the concentration of

spray you're assuming it's all the same

concentration may not be all the same

concentration there may be a

concentration difference in a hollow

cone nozzle for example between the

other portions of the sheet and the

inner portions of the sheet that's kind

of a cool thing to see if it happens d

mixing often occurs when you don't don't

pay attention to it drops reached their

boiling points than impervious and semi

imperious surface layer forms moisture