Spray Drying II

ok ladies and gentlemen we shake this is

part 2 of spray dryers spray drying

excuse it there's basically some

comments on control systems I don't want

to get into the area of control systems

but one of the problems with dryers

generally speaking is getting the proper

process measurements like I'll let

mousse Chirk of outlet moisture from the

air or the gas stream anyway so we use

the outlet temperature not moisture but

temperature outlet temperature controls

and feed rate or see rate of material to

be spray dried and the inlet temperature

to the dryer controls of fuel

consumption rate or combustion rate so

one way of two basic control systems two

different types or potentially use the

outlet temperature to control the feed

rate to the heater the outlet

temperature controls fuel rate to the

heater the feed pump is either fixed or

manually controlled so if we look at

those two control systems we have the

spray chamber the exit exhaust air from

this chamber the spray drying chamber

goes to a temperature indicator control

which then goes to the feed pump for the

fluid let's see if the temperatures high

and then you feed more fee and that will

cause the exit temperature to drop at

the same time you have the heater and

basically of hope to fix the inlet

temperature to the dryer right or the

drying chamber you go to a temperature

indicator and controller that then goes

to control the control valve for the

fuel so these are two

basically control systems the cold

temperature says bad more fuel hot

temperature says to reduce the fuel

anyway as opposed to that you use second

control scheme as you use the exit air

through a temperature indicator and

control are going to fuel fuel heater a

fuel supply then that goes to change the

inlet temperature of the dryer so here

the dryer Inlet temperatures pretty much

fixed here the inlet temperature of the

dryer its variable or more variable I

should say depending upon exactly what's

happening with the fuel pump or this

theme color rate this is indicated

manual control so you fix the minute of

feed at fixed rate that should fix the

exhaust temperature which then fixes the

feed flow rate to the eater and it also

would fix the inlet dryer temperature

but it strikes me I don't know which

controls system would be better the TI

and the TL or the temperature inlet to

the dryer next to the dryer are the two

design variables to a spare tire talked

a little bit some additions to your

control system you might put in a wheel

balancer for rotary atomizers you might

put in a broken bag detector for your

bag houses oh you could for nozzles you

can calculate the flow number for your

nozzles flow number is really flow area

for your nozzles you can calculate that

you can possibly calculate that online

it's the modern tour the where clogging

of your nozzles the area of the nozzle

is fundamental to determining the drop

or you may add and gas the liquid ratio

monitor or air to liquid ratio for two

fluid nozzles that should have a minimum

amount to air having twice the mass flow

rate as the liquid typically with two

fluid nozzles you're looking for the gas

stream to cause the atomization there's

very little pressure drop available to

because liquid they cause the

atomization if the gas fails or the air

fails you and two fluid nozzle it will

drip it will likely drip man's control

systems well there's all kinds of layers

of control you can put in you can have

feedback feed-forward cascade control

control sequences timing sequences

interlocks alarms etc electrical checks

all kinds of sub control systems

controlling the feed which we see

controlling the gas fans atomization

control controlling the pressure drop

that may require pressure controller

weighing systems pneumatically

transported thematic transport system

powder discharge system bangali scrubber

baghouses control and cleaning systems

of rotary airlocks then you might get

into man-machine interface situations or

controller sequences and decoupling so

you know all kinds of feed-forward and

stuff feedback computer control

feed-forward multiple input multi output

big a big data

I'm sure it's evolving these tightly let

the vendor supplies of the control

system and then add as I said these are

several of the items you might wish to

add to what degree to what level and to

what degree new advanced control systems

have been used in spray dryers Israeli a

company specific some companies don't

want to change anything some companies

are interested

control-enter locks one of the

interesting things is concept of

interlocks and elementary chemical

engineering control courses interlocks

are rather are hardly ever mentioned but

they ensure a level safety let's see

what some of them are one interlock

ensures the exhaust fan cannot be turned

on before a supply fan if the exhaust

fan is turned on this will create a

negative pressure in the chamber and of

course it might be overridden if the

door is open chamber doors of interlocks

prevent burner ignition unless the

burner fuel pump is on whether there's

the combustion fans on and where the

dryer fans are on you don't want a

situation where their heat generation

going on but it stays there he

accumulated he came away and could lead

to problems so you want obviously burned

the stuff but then get it out of there

interlock to prevent feed from rotor

atomizer to breath feed when the rotary

atomizer is not running so what would

happen is the atomizer is not running

the feed would just drip off the wheel

down into the chamber and lead to

problems later interlocks to prevent the

main driver fans from being on when the

cooling fans are not including fans cool

potentially hot areas to prevent buildup

of burnt material and it locks to

prevent personnel from entering the

dryer chamber when the dryer is in

operation do you enter a dryer in

operation it might be like entering a

snow saw or having snow falling

interlock to shut down dryer when I fail

your water flow to the wet scrubber core

obviously or switch the water feed I

don't know if I want a water feed unless

I'm cleaning I guess if I take a look at

a rotary wheel right and you generate

cleaning sprays so it'd be interesting

to see I'm we're always interested in

whether I can clean my equipment or not

so thinking about using your atomizer

instead of generating particles or drops

to generate flow rate to the law or

worse down your inner rate are more

interlocks more control systems

overlapping upon each other anyway

additional con comments on dryers

psychrometric charts and some datum just

rattle off some few things here straight

divers are use one for their high Inlet

temperatures too many materials require

size required size shape density and

other properties they cannot be made any

other way

so like we said the agglomeration

process in a fluidized bed or excuse me

you do the spray drying followed by a

fluid bed spray dryers are loaded or

limited to liquid feeds and high

evaporation loads energy and flow

requirements let me the liquid feeds

have high evaporation loads energy

requirements spray dryers and use for a

wide range of materials and many designs

are available liquids to be sprayed in a

uniform pattern hopefully no mild

distribution of feed and a uniform non

pulsing flow of heated air

now having said that maybe pulsing there

might be helpful in some cases but for

the most part you want nice uniform flow

of air not all liquids can be sprayed by

a straight spray dried alright staking

your Daiki materials basically when

you're dry and they become sticky and

tacky

and that would lead to all sorts of

problems some materials go through a

sticky phase during the airborne stage

and can only be spray dried interesting

if we go to the favors book and look at

different fluid properties like

viscosity surface tension

air-to-liquid ratios right we find that

we have the Weber number the Weber

number is right here in the parentheses

the ozog number which is sitting here

the lever number takes into account the

Sauter mean diameter excuse me

over years of solder main diameter here

certs its surface tension and the SOG

number takes into account viscosity and

the ALR takes into account air-to-liquid

ratios their gas to liquid properties

can be modified some way I mean surface

tension is pretty well fixed can't vary

that too much viscosity you can change

due to temperature you can run hot vs.

running cooler properties may be

modified somewhat either heating or

cooling diluting usually it's not

desirable right typical particle size

for spray drying is 20 to 150 microns

larger size particles come from larger

drops which need larger diameters or

taller

tall chambers large drops come from

large orifices small drops come from

small orifices big drops come from

wheels rotating at low speeds and high

flow rates so they're all sort of fits

together small sizes cannot be made at

the high capacity except at high

atomization power inputs nozzles are

more economic

it's way in different directions maybe

this is much simpler if there's no I

pressure pump fees or non-uniform

nozzles then the plug and do not operate

uniformly of solids content viscosity

vary and you can have them start

spitting at you so to speak you have air

in the line that's also interesting as

you pull down on a tank and the drink

empties the feed and there's good

possibility of air entering the line and

things aren't so great under that set of

circumstances abrasion enlarges of the

orifice as I said daddy was talking to a

young lady in France there she was from

France and I thought to her she had a

valve and her lying

she had a 300 psi pressure drop across

the valve and she wanted to know why the

valve disappeared after a month

basically since high pressure drops at

high velocities and high abrasion levels

multiple nozzles are often needed for

high production rates frequent cleaning

replacements are normal I can't expect

the nozzle to last forever there is a

tendency to believe that nozzles do last

forever but they really don't they

disappear they become part of your

product two fluid nozzles get their

energy from compressed air or this hope

so right so too expensive with AI

capacities that's what two fluid nozzles

are two fluid nozzles accommodating

fever I don't know you know maybe this

is too expensive it's sort of a vague

term right two fluid nozzles accommodate

feed rate and changes to changes better

than regular nozzles right it's a

broader range of particle sizes wheels

and this can be used in virtually all

applications

some types produce very uniform drops

like

it's like cotton candy you should review

my course on atomization and you should

also review my course on drying drying

one and driving two wheels are preferred

at eye capacity because in the

horizontal spray speeds are very high

this is the twenty thousand rpm that's

fast dry drive mechanic mechanisms are

far more complex and costly compared to

nozzles sometimes need ice be motor run

and high frequencies require accurate

balancing and skilled maintenance wheel

balancers are available all right so no

shutdown is needed for balancing however

there's a diminishing return on this yes

wheel balancer can balance your wheel

keep protect your bearings however after

a while the build-up could be so

substantial that the next failure could

be catastrophic in other words the wheel

balancer will let problems will give you

a sense of complacency and let problems

grow and they grow and then while ah you

have a major shutdown where the wheel

balancer no longer can do the job wheels

can only be used in chambers large

enough to accept horizontal space

however the horizontal sprays can bend

the airflow so you have a sort of an

assignment for you I want you to go put

your lawn sprinkler outside sprinkle

your lawn and get an idea of the

distribution that's produced from your

lawn sprinkler and I want you to go view

the same sprinkling going on when you

have a high velocity wind and you can

get the idea of how horizontal sprays

can be bent with high flows or air flow

to

verse chambers who's got the chambers

short chambers tall chambers rectangular

boxes all kinds of things

YS range of applications conical towers

with co-current air patterns right

conical towers residence times five to

thirty seconds maybe as high as 60

seconds for towers now we're talking

about presidents time of the gas flow we

don't know for sure

with the residence time of the particle

service so you might put in a tracer in

the particles and see when they come out

you know put in some red beads or

something like that or somehow I'll put

in some particle indicator you make

larger particles a low capacity small

chamber small diameter tall chambers are

used mixed flow chambers increases

exposures let's go back so here we have

our chambers tall towers and a G would

be a box some sort of thing like any

bird came who's thought the chamber here

we have five four two figures for two is

here and you have some comments conical

cylinder with cyclone power box where

it's used

what sort of atomization what type of

flow you have give you an idea of the

flow pattern spraying upward and gives

you the maximum travel then say travel

distance co-current upward again without

a costly large diameter chamber spray

dryers with fluidized beds that we

mentioned

now there are spray dryer with belt

dryers possible chambers mounted

directly over the mesh belt matted mat

to conveying material through the

various zones for processing anyway what

we have here some just some data

basically the type of material you're

spraying on skim milk eggs coffee tea

right sort of moisture content going in

75 microns excuse me

75 percent moisture 85 percent moisture

outlet the percent moisture that's a

substantial moisture reduction gentle a

temperature 271 and 10 leaving C degrees

C parallel flow cold currently this is

what that means interesting to compare

your performance with some of these any

lace more data we have the material we

have coffee again and like temperature

in exit temperature al percent wire in

the feed or percent moisture evaporation

rate so you know this is 18 18 feet

diameter 18 feet high spray wheel fan

capacity so Wallace's book 1988

excellent book Wallace's book in 1988

I'm sure I lifted this from there I

found that my steak and some gather data

dry products

micron-sized typically you're looking

power input you very seldom see that but

it's like kilowatt hours is energy

basically per volume basic fundamental

unit of power input bulk densities

versus Inlet air temperatures you see

some relationships versus percent solids

in the feed and again I highly recommend

you review my course on trying right and

if you do that and you'll notice the two

big things that matter is Inlet

temperature of the dryer and the outlet

temperature the dryer and when the two

cross you have this combination of inlet

temperature and exit temperature you

have that evaporation capability I'm

assuming boil water and up here I have

five hundred coming in and two on and I

have that evaporation rate okay I'm not

sure I'll have to go back and check the

reference exactly what BLSA is I'm sure

somebody will tell me if they get this

far my videos anyway product number I

guess it's some sort of placement along

this x-axis okay psychrometric charts

yes again the following is really from

my drying course my general drying

course I won't need to go through these

simple calculations that were done in my

drying course but basically at the end

of all this

try that one right there try one back so

that one obviously a couple things you

pick the inlet temperature you pick the

exit temperature those are three points

here so I'll show the your this chart

later fairly quickly onward but again

review my course on drying this is from

their summary there's some range design

is roughed in you after you do that go

through my course rock ten the amount of

water evaporate or moisture evaporate at

the air flow rate and the heating rate

these are the big things for a dryer now

you have a clothes dryer at home and

what does the clothes dryer did alone

well it's very similar to any dryer

direct dryer right you heat up the air

you have to have a flow rate to heat up

here and then the hot air goes in to

your dryer to evaporate moisture so in

the dryer design typically you have you

pick now you got a design a young design

students picking is your choice exit

moisture Inlet dryer temperature exit

dryer temperature usually no inlet

temperature and conditions in the

moisture and usually you know the bone

dry mass flow rate anyway the reason why

you

use such a chart as this is one of the

major reasons here you have moisture for

dry air here you have enthalpy for dry

air now this is really moisture for time

for dry air for time so moisture

evaporated basically for time versus

drive air flow rate for time and on the

x-axis you have the heating / time / air

flow rate by time so you have the three

basic variables you have the air flow

rate that's bone dry air for time you

have the heating rate for time and then

you have the evaporation though so

suppose for example you want to quickly

envision taking your supply air which is

was at sixty and now you're going to

bump it up to keep it at the same

moisture content but you're going to

bump it up using a heat exchanger where

you move it from here to there and you

want to see what effect does that have

right well if I project it up and I'm

heating with natural gas basically in

that I mean the propane or whatever

there's moisture increase to the heating

requirement so this line is tilted

upward now that moisture requirement for

this is non no heat exchanger you have

this situation occurring so I have these

two situations X is for the variables

where I have used as glassed heat to

heat the supply air that's what that was

done the heating done laid down now give

you an idea of whether that's economic

or not right this is free well you have

it so you might as well use it so you

line up the two streams and you boost

your inlet from here over here now as a

percent of total

burn you can quickly do an analysis this

length maybe about 18 now to 20 to 60 or

58 so that would be what 38 and then the

total would be 22 170 or so so you have

38 divided by a hundred and seventy so

excuse me 170 well I got to take that

170 - the 20 here so - 20 makes it down

to 150 so I have 38 divided by 150 in

this region so I get an idea how much

energy on saving and we can do a quick

calculation on that how much you say if

I clicked off X X for entering it why do

you enter it x1 she may want your

internet one now you're in at 1x save

about 34 BTUs per pound of dry air then

you come along I multiply by air flow

rate so you're saving air flow rate

might be thirty nine thousand three

thousand nine hundred and fifty three

you're saving 34 BTUs per pound or I'm

saving something like one point three so

- the time stand of the fourth BTUs per

hour I don't know if that's matters to

you or not right how much cost that is

remember natural gas went down by a

factor of ten right up around the 20s

going to do so you have substantial

natural gas costs reduced now if you're

not eating with gas but you're doing

electrical right your electric drill

went down by what a third or fourth 36

divided by 30

150 anyway here we go now the exit

temperature you pick and so you have the

only

temperature coming in at 300 Fahrenheit

the exit temperature you pick okay let's

take a look at this straight up is just

heat loss only right B is he lost with

heat and feed now he did feed will give

you a slight tilt here in other words

you eat the air which is this line and

then you put in a little bit of heat

with your feed so now instead of one

source of energy I have two sources of

energy one being in the air and the

other being heated feet so that's gonna

slant the line sort of like this and the

heating rate of your feed has got to be

the difference between two and three be

down here on the x-axis if you wanted to

do heated feed if you wanted to do he

lost a huge exchanger I put in the

internal heat exchanger inside the

drying chamber then the heating heat

exchanger obviously is going to put in

heat so the amount of heat that it puts

in puts it over here so it would be up

here round three you can see I've

certainly moved away from a and B

situation here and I'm already up to up

in this region so I'm going about thirty

twenty eight percent moisture consuming

twenty to eight point zero two eight

mooster say in this region up to point

oh four three boys sure in this region

so I have a substantial increase in

moisture being picked up and again this

is an exchanger inside the trying

chamber right

B I have heated feet in here I'll have

an exchanger inside the Dukes the more

eating so and by having an exchanger

inside even though I have exes exit

temperature still at 200 I have picked

up of moisture say from two eight two

four three so I've picked up a

substantial amounts of moisture here

okay now these are psychrometric charts

right so if I have any any interaction

between say hydrocarbon and another gas

I would have a psychometric chart for

that well I'm not sure long time since I

thought food engineering but I think at

one time there was a process to remove

caffeine from coffee and they use text

saying to remove caffeine from coffee

and then they dried to hexane and God

they had to remove the hexane from the

coffee so they would spray dry they

would get coffee out the bottom and

hexane out the top so next thing was

being removed from the coffee liquor so

we have the heating going on then we

have the drying operation now then since

this hexane we want to have a condenser

and the condenser will condense out the

hexane back to the original starting

conditions so we pull hexane office of

liquid coffee will come on out instant

coffee will come out of as a solids flow

not showing here but I'm just saying

that these types of psychometric charts

available for all kinds of different

stuff all kinds of different stuff

okay and all you gotta do is create

these and you have these lines of

temperature sitting here this would be

your your Inlet temperature your exit

temperature any way short-cut

two variables of importance inlet

temperature next to temperature here I

have inlet temperature heavy line a 400

and my exit temperature 200 so I'm

sitting right there I dropped down

shortcut chart for air water again I

have the air flow rate versus the

evaporation rate and then over here I

have the heat load versus the

evaporation rate so I got to figure out

what I want as the evaporation rate that

will then fix this is 7/2 I can

calculate the air flow right and I can

calculate the heat load or how much heat

I gotta put in for them so at this

entrance inlet and exit kind of cool I

think a lot of computer programs and if

I'm not mistaken what's that language

basic basically computer language I

don't know if they're still available

about anyway part of AIChE this is a

close up shortcut chart again charts

provide understanding is easy

visualization and interpretation very

useful and quick no computer simulations

it's not opaque it's very easy to see

what a little bit of preheat to the feed

will do whether I have an internal heat

exchanger or whether I have a convincing

system convincing me benzene and

taking it out so this is a cycle in here

get out the benzene anyway effective

operating variables I mean consumption

effective Inlet temperature basically

increase in the inlet air temperature

decreases heating requirements ten to

twenty percent leads to ten to twenty

percent right reduction in fuel always

feed if the maximum percents all as

possible right very important see what

else do we have here trying is expensive

moisture reduction saves money and

increasing from fifty to sixty percent

then reduce heat load by fifty percent

that's pretty extraordinary so maximum

solids is where the feedstock can no

longer be easily atomized or pumpable

hmm

dewatering techniques might be of use a

concentrator might be abuse infiltration

one of the things you try to do is

concentrate your solids increased solids

and feed can lead lead to any chamber

deposits right increase in solids lead

to increase in drop size lower

evaporation rates you leave running into

the particle becoming an object in the

flow and it hits the wall oven spray

dryers operate at low solids and low

temperatures because of feed properties

depends upon the ability of delicate try

delicate products to withstand

aggregation three primary ways of

removing solids without heat filtration

certification and decantation of course

we haven't mentioned that there are

thickeners there

preconditioners often used in

evaporation excuse me are often used in

filtration there are some difficult

processes in their own right the

filtration can be difficult they can be

very unpredictable

some can be very easy like letting the

liquid just sit there decantation is

really an expensive li easy drainage is

very easy solids against solids handling

is an issue there are various thickening

methods as well he required to evaporate

water is the same as independent solids

present he required he go into the cells

is small and compared to heat going to

evaporation you can avoid or reduce

water content and so and of course my

best recommendation is avoid drying is

all possible so feed as dry as possible

and don't drive unless you need it ok

higher delta-t higher lower he

requirement hmm the thermodynamic thing

I'll have to figure out what that meant

maybe it's used shortcut charts to make

comparisons there you go so let's go

back and see using the shortcut charts

whether that makes any sense

higher the Delta P so what does higher

is Delta D me I'm going from say this

point to this point to this point to

this point what happens right so the

difference here is 50 the difference

here is 75 so I have a higher delta T

and have a higher eat load then I go so

my lines going through here I go from 50

75 to 100 so I'm following that line up

so it gives me a trend

I have higher Delta T's going this way

so always I always like to check things

to make sure they are true and this see

if that was true it's supposed to give

you a lower heat requirement to see if

that's true going back through here I

have heat load for operation rate so I'm

going from here to there with increasing

delta T and it looks like my ego is

increasing so and then look at that it

drops down here I have 150 here I have

200 and I have 3 300 so I'm going from

here to there to there and I'm also

increasing along that line so I put

question marks on this when I was first

teaching this I didn't believe that you

didn't believe that statement and I had

no way of making sure it was right or

wrong so I like questions markets and

right now it seems to be wrong I used

shortcut charts to make comparisons

increasing Delta P is increased by

increasing inlet and lowering outlet or

outlet means higher residual moisture

and product leaves increases further

process requirements after drying maybe

maybe not you may be able to use that

moisture to advantage you may wish to

sell that moisture so I become part of

the sale wait ah some of my best friends

love to sell Lake Michigan to the

American public right and you know if

you're making ice cream air is cheap so

you put a whole bunch of air in your ice

cream just as a comment and so maybe I

want to sell water right

now their comment ice-cream they're

allowed to put 50% of air and ice-cream

if you take a look at that from an

economic point of view air doesn't cost

anything it makes the product more you

can scoop ice cream easier when it's

aerated 3 it doesn't have calories the

only bad thing you're putting air in ice

cream is it reduces the weight feel a

weight okay so you have an assignment I

want you to watch ice cream melt okay

it's a very simple assignment and watch

the foaming coming out of inexpensive

ice cream now I don't know if ben and

jerry's but some in their ice cream i

don't think so it's hard to dip and as a

result less air besides people like

light and fluffy desserts what do you

think anyway just this is social comment

to break the up break the monotony here

effective partial recycling exhaust

they're open cycle exhaustive the

atmosphere is a large heat loss dam as

large he thus i'll attend church here

maybe i enough to achieve desirable

moisture contact recycling exhaust air

preheats the air supply to recover some

of the waste heat reduces the fuel

consumption it's good good thing less

heat loss to the environment that

destroys the environment or helps the

environment this soon assume it destroys

the environment fuel savings up to 20

percent have been obtained with partial

recycle or the exit template temperature

exceeds 120 120 means there's a lot more

heat in there if it's 110 not so much my

successful application requires about

120 dried product is heat resistant okay

fines and train and recycle can we

and Inlet temperature well it depends

upon how you're doing recovering the

heat all right

[Music]

remember moisture is recycled - okay

that's great doctor feed temperatures

increase in feed temperatures reduces

the heat requirements so you want to run

hot basic that's pretty simple run hot

don't cool don't lose heat before the

dryer and it might try installation

they're preheating up step by the way

generally speaking thermal insulation is

put on for safety reasons usually and

then you have energy savings preheating

helps to reduce peak viscosity that

results in better atomization possibly

prevents feed crystallization yeah

that's in the realm of likelihood the

line freezes on you you heat it up a

little bit you trace the lines with

heating so uh and help you play what

happens games what happens if I'd leave

Lou's feet due to crystalline

crystallization remember I'm pushing the

feed to higher and higher solids and

that way I'm pushing it towards higher

and higher constant higher and higher

crystallization probability rarely is

preheat Don to improve the thermal

efficiency some heat exchangers can

handle and trains particulates

so shell and tube is not one of those

well let me rephrase that if you put the

particle size particulates on the shell

side you're asking for problems anyway

these heat exchangers can recover our

waste heat investments investments can

usually be justified payback times and

site-specific but you're looking one two

three years right are there liquid

beneficial and outlet temperatures are

the range of 90 to 130 before we were

saying had to be

hundred-and-twenty are about raves that

what we were saying up here

where was the 120 now we're saying it's

beneficial fuel savings of 20 30 percent

it's possible so it tends probably to be

site specific guides for reducing heat

costs even cuz he have a good

housekeeping ready later my excuse me

regular maintenance you want this okay

we took a short break we're back

guidelines for reducing heating costs

good housekeeping with regular

maintenance inspection especially burner

assembly have good dryer cleanliness

help server and stoppages avoids

deposits have corrected drying

operations by maintaining correct

temperatures and feed conditions monitor

the feed and feed conditions question is

is your feet changing on you and how do

you know that it isn't changing on you

you don't want over dry very important

you got a spec for the moisture content

leaving the dryer don't get it don't get

more than desired minimize long startups

and shutdowns yes guidelines for correct

process operations fees apply highest

possible solids maintain insulation

intact

do not use higher outlet temperatures

and necessary rectify all hot air leaks

use as high an inlet temperature and low

in the outlet temperatures possible

instead of two-stage driving partial

recycle especially about the layers 110

now we've already seen we had 120 now

130 now we have 110 can see consider

each exchange rate outlets is above 100

there you go so now we are I don't

20 under intent and on dirty so it

really is a function of what your energy

costs are I mean if you're out in the

Middle where they flare gas freely

flared gas then thriving he does three I

would imagine or considerably low

consider D humidifying the air for humid

locations use a scrubber to preheat pre

concentrate to feed improve insulation

filter air intake that's true strain

feed for materials a clogged atomizer

sale you might have a strainer in there

outlet air is usually controlled by the

inlet air temperature and feed rate and

fans whine at the end the one at the

accent exit of the cyclone to stay fans

and a push-pull arrangement don't want

fans to experience solids too much fans

at the exit causes the drying chamber to

be under a slight vacuum by the way dust

will collect on rotating fan blades if

you have a box a fan at home or ceiling

fan you'll notice that solids in a home

environment accumulates on the fan

blades helps with leaks to have the

particle collection system collect the

particles that's pretty cute at the fan

free of solids as much as possible fans

will collect on the fan blade so what

we're talking about possible arrangement

you're pushing it in and you're pulling

it out notice here it's after the

cyclone not before the cyclone right

because there's substantial solids

leaving here only a one fan system

usually for small dryers on the exit I

these devices wheel balancers fan

balancers these devices exist and keeps

keeps everything a good operation good

idea to prevent too many shutdowns

catastrophic failure may occur if

cleaving is neglected right bumped or

reconstituted type thanks usually to two

tanks feeder need strainer design piping

systems for easy cleaning and

maintenance don't want may want recycle

product to change the feed that's

interesting

back recycled back material to change

the feed characteristics

pumps are usually rotary Plaza

displacement diaphragm pumps are for

irregular shape and a base of feeds what

bothers me is the word positive

displacement and slurries

now that is an interesting combination

that's positive placement usually

implies close clearances and close

clearances means the slurries means

abrasion likely numerous cases of

pretreatment blending with additives

correcting the ph value all kinds of

things atmospheric air is usually is

usually the supply source filter to

remove airborne particles above five

microns must mix there with atomizer

fluid for a pea evaporation must dry

feed sufficiently before reaching before

our spray reaches the wall now that's

the time of flight calculation how long

does it take to evaporate and how long

it takes to have a relief you reach the

wall the dark Arthur the favours book

the favors book on atomization has an

entire chapter on the calculation of

time of flight and it's lets its

calculations there's a model there are

several models on what beat what happens

or in the material

as it evaporates what happens was it

goes to the wall theory must agree with

fact I suspect just as a quick asks X

estimate very crude of course the will

tip speed will be the velocity of the

particle leaving and assuming no

reduction no drag reduction due to the

surrounding air that will speed will

indicate how long it takes for the

particle to reach the wall that's if

it's a big particle okay big drop just

say the wheel speed is that's the

velocity of the particle you got the

distance between the wheel and the wall

that gives you the time of flight and

you also have the idea of how many drops

are made and that would they give you

the evaporation gives you you have the

number drops our particles formed or

number drops formed then you can

calculate you know you measure or have

an idea of the evaporation load involved

you can calculate the individual

evaporation per drop in the interest in

calculation right you know the

evaporation load you know the number of

drops so you know how much evaporation

occurs per drop and that's got to occur

quickly you don't want liquid reaching

the wall let's try the feed sufficiently

before the spray reaches the chamber a

wall prevents wall buildup shoulders are

washed regularly yeah you got the air

filter right you got the filter in the

feed air chamber disperses can affect

drop size distribution of course drops

hitting other drops usually involves

angular2 Bains would swirl the air

swirling keeps the stuff off the wall of

course see we're assuming that the

the rotational speed of the impeller is

the same as the velocity to drop but we

didn't say if the air is swirling that

this is to the wall is a lot larger

right because the drop will have a

tendency to swirl as well and as swirls

over a larger distance than that between

the atomizer and the wall so the

swirling air is going to help you out

there okay anyway I give you some

comments on how they're doing

calculations operation per drop rotary

atomizer is likely generate their own

airflow right

that's very true basically rotor a

rotary atomizers to be cynical about it

or take a different perspective

rotary atomizers or nothing but fans to

push air around with a little bit of

liquid on it how's that anyway

drying chambers all sorts main objective

is to provide enough residence time for

drying don't degrade the particle don't

have wall buildup particle discharge

should be excuse me product discharge

must be continuous discharge method is

conducive for product specs discharge

usually at the base of the chamber

general designs co-current counter

current mixed all kinds of other chamber

options are available many our patent

didn't my major one main reason to dr.

drying spray drying companies for their

chamber airflow knowledge and chamber

chamber who's got the chamber there's

all kinds of chamber chambers anyway

just give you this list chamber chamber

who's got the chamber but I discharge

lots of different designs was discharged

curves at the base signs remain in

trainee and gas that's in the air stream

one design of sonic liquid pals up below

the air vortex another is the sweeper on

the bottom of the screw conveyor that's

interesting design another

I may have side discharge or sweeper

centrally mounted discharge sweepers

pneumatically conveying can be used the

product doesn't forma stick perform

sticky lumps Aryan product exhaust ducts

must be high enough to convey the

product there you go cool air and

exhaust mail cooler air and exhaust

ducts may help chamber wall aids and

product discharge air wall cooling or

air sweeps the wall could be used

chambers and vibrators are mounted on

the walls because vibration or hammering

chamber wall must be low for sticky

products double wall cooling rotating

air booms and tangential air sweeps help

up here you can also have chains inside

you could have dangling change the hell

outside you have a hammers or vibrators

perhaps see the change would sweep back

and forth hopefully used to maximize

profuse to maximize product and reduce

excessive release of the powder to the

atmosphere right so we're talking about

recovery product from exhaust gas wet

and dry equipment used try products

begged off and sent for further

processing but what may be recycled is a

feed pretreatment I mean anyway what may

also be sent to further processing or

consider the additional product or a

waste we don't want to call anything a

waste it's just considered a how can I

say at the by product we have our

typical clean Xenia cyclones thousands

precipitators cyclones are real cheap

right there's nothing to them

we're just metella by quality is not a

fact that accept attrition effects

cyclones can change particle size

particle size distribution so we have

wet scrubbers what cyclones Hydra clones

or fluid clones array their fans

sometimes install there's a secondary

stage you have a fan that's right there

you spray water on there you go

water comes liquid concentration often

too low for recycle or economic recovery

in our past or affluent treatment I

apologize for these but what's really

unique is a item I know basically you

tilt your computer screen right right

you take this and turn it on its side

and then you got instead of me fussing

around seeing if I can rotate this you

can rotate your computer it'll be the

same effect and what we have we have we

look by filters we can have by braiding

baghouses

reverse air jet bay houses we can

blowing air ring by bank houses by

houses by houses peg houses looks like

we have all dots here no dots here and

we're at the bottom little bacterial

growth all that's there looks like all

three are equivalent except for right

here and this is for easy to clean star

means the notes suitability and the

whatever its means so high air

throughput I powder lodi's row powder

loadings anyway you can look at it on

the side bag houses now we have cyclones

dantana covers everything what is that

nothing wrong with us cheap old cyclone

wraparound and let the engine Inlet

probably the same thing

and then we have scrubbers and gravity

settlers and we had electrostatic

precipitators plate type and we have our

various requirements see what cleaning

is looks like we can clean except our

electric say except I don't know if

there's that that's not a doctor so

there you are some tables to help you

understand cleaning operations better

cyclones a bag felt there's widely use

low-cost easy maintenance I don't know

if bag filters are easy many men's

efficiencies are somewhat high enough so

that secondary stages usually not needed

however our cyclones are not a hundred

percent petition bag houses or bike

loaders are virtually under percent

efficient we can get some numbers little

later bag advantages offset the cleaning

difficulties and high maintenance bags

can also tear so you may eat a bag

detector what is that when all burn air

or as a bag detector just a metal device

and when a particle it's a it's changing

this charge and they recorded charge all

burn a you be you are as a broken bag

detector very sensitive very sensitive

so I hope you have liner and have

something in quite a lint bag tears come

from loading okay

also probably if you have your bags

vibrating in their their motion motion

causes repeat where because of the place

where repeated motion will eventually

tear the bag perhaps down tines from bag

houses can be lengthy that's bad you

cyclones first followed by bags cyclones

handles a volume my bags handle the

cleaning

saikhan so far you deal with in bags

battery of cyclones might be considered

impossible how long on the interesting

things you get worried about the numbers

here when something says is 95%

efficient efficient you go oh wow that's

great

however you got five point five percent

products still there right so it's

getting through so this may be great

efficiency but it's still still has some

problems with it generally there's no

hard and fast rules for exhaust cleaning

well my favorite answer to every

engineering question it depends if you

take a look of engineering questions

they're usually under specified okay

there's always further questions and

they answered all engineering questions

it depends and when you say it depends

it makes you look profoundly smart right

all this person knows something he's

going to give me options so you run down

through the options anyway we have

regular conventional cyclone and those

are the dimensions then we have this

dual vortex separator in other words

there's a vortex down here and there's a

vortex up here and I'm not sure what

exactly this lines supposed to represent

but I suspect the flow goes through it

and you have a large solids go through

here and here I'm not quite sure what

this does secondary airflow to drive the

vortex this is probably some sort of

rotator give you a swirling action and

passing through veins to further give

you swirling action and what we have

here are standard bag filter we have

microns size one two three and we have

the efficiency so if you get the four

microns or three microns you're already

at

99% efficient bandwidth efficiency great

career for cycling specified in example

four twelve seven we don't have by

Eragon you play micron sizes right I

hate to ask this question I do have your

efficiency curves for cyclones number

one and number two how much have they

changed over time because this cyclone

will eventually abrade away and

disappear perhaps or better yet and more

interesting comment it's what you think

is inside is not there anymore

friend of mine mixing consultant for a

big very famous company and he was doing

a site visit to plant and he walked by

this two big huge tank and they shaft

was rotating around and thank was filled

with water or a liquid and my friend

asked the player manager is there

anything in that tank is there an

impeller and I think in the plant

manager says oh yeah yeah yeah no

problem there's impelling that thing

it's a new time they passed the same

tank and had pretty much the same

exchange

yes yes yes of course there's an

impeller in that thing so two hundred

four o'clock the afternoon when my

friend was leaving he left it was

allowed to leave early passed by the

tank and this time the plant manager got

upset with him and I'll show you there's

an impeller in that thing so he drained

the tank and as the liquid level was

dropping they looked inside them it

looked like a candy cane sucked down to

a point during Christmas time you know

so as the liquid level dropped the

diameter of the shaft became thinner and

thinner and thinner saw the impeller was

long gone

and obviously the plant manager didn't

know what was in the tank equipment and

the thing you would think that's that's

fundamental knowledge huh

let's go on pilot studies president

Stein dry out lies anyway art spray

drying mass and energy balances are

available DD rated air drying drying

rate air flow rates lots of information

equipment lots are still missing and so

we still go with an art he depends upon

experience basically principles not

based upon not based upon more

theoretical approaches limitation major

limitation the ability expressed the

interaction and droughts with

surrounding air there you go that may be

changing will get some of the computer

simulations later the ability to

determine the particle and airflow

patterns in the drying chamber again

this is the idea you've set up a

confetti flow system then with a

videotape and you can gain some

understanding about what flow systems

you have ah do a scale model right hence

specifications and desires here models

are based upon existing

vestro experience that's being non

theoretical procedures designs are

variable and there are manufacturers the

way you design something is fairly

simple you just let the manufacturers do

it I'm teaching the design course in

college and I never say that to the

students the best way to do design they

let somebody else do it okay

I mean when I want a mobile do I go

design the automobile I don't know

so same thing you can get somebody who

knows a whole bunch missing a punter

actually dropping surrounding the air

particle and airflow awaits in the

chamber these unknowns are solved by the

manufacturer when you have the air dryer

dispersed or atomizer and spray chamber

air specified these three items

determine the interactions drops

surrounding air particle flow patterns

there you go so this is

the icing on the cake so discreet

multi-phase flow like evaporating drops

in here and it's bait chamber is Bobby

on commercial computer computation at

the present time this may no longer be

true however a boiling drop ie these

drops are going to boil down to a solid

and that boiling is again doing them in

that molasses analogy might be quite

different than what you think it is

single procedure will never be

universally applies to any sets of

correlations will have limited value I

like doing tests at the plant level

objective is to have a practical

approaches and guidelines you're not

looking for exact answers here what

you're looking for are trends you tend

to think this is better not that's

better NIST

so you eventually will it down to what's

the best choice and that's done by

comparisons right not necessarily by

calculations but by experimentation or

planted plant operations so the

objectives have practical approaches and

guidelines by the plant tests figure

optimum performance and importance of

residence times basic type Co Karen

Concord mixed in Lenexa temperatures

while obtaining powder qualities these

are the qualities moisture size bulk

density color flavor texture flow

ability require residence times for

design properties while avoiding wall

buildup time a flight for particles from

an atomizer that's our friend the favors

book little chapter on calculation of

time of flight when you got finished

with all sorts of calculations you gotta

sit there and ask is this reasonable is

it plausible the relationship between

outlet temperature

oh Sh boy stur yeah optimum feeding they

have complete atomization with product

quality continuous operation can be

achieved ancillary hammers air Bruns and

sweeps selection of atomizer operating

conditions rotary pressure to fluid I

would dude site visits get the vendor

give you a list of people using their

equipment go out and visit them alright

talk to the maintenance crew talk to

everybody I prefer to talk to everybody

I learned everything from everybody you

know system a constant absorbing and

information so you know maintenance

people are you know don't have a PhD

from a university but they may have

equivalent PhD and maintenance rain a

suitable dye collection final exhaust

air cleanings samples for evaporation

market analysis area go market analysis

there ain't no thing you don't want to

make unless you can sell it you got to

be able to sell it

alright phases for operation product all

this information helps and skill up ok

let's see what we got here

so alright certain a produces certain

specialty products so there we go

different geometries slurries slightly

abrasive pumpable pastes mmm so your

wheel becomes a mudslinger in a sense

alright pumpable pace kara

karen scale up first off you realize

that big difference in scale no i i'm

more difficult to dry in small test

dryers

due to the closer proximity of the wall

any deposits and tests must be

evaluation whether they occur on the

large scale yeah very true and scale up

lots of things happen in the lab the

happen in plan right lots of things up

in a pilot plant that doesn't happen a

lamb excuse me that doesn't happen their

plan so there's a whole bunch of things

that are don't scale okay I ran across

the guy who's very proud of himself and

he should be now of course he was the

person behind funding the process anyway

he was doing some studies and it failed

on a lab I mean he utterly failed my lab

so he says well should I scale this up

intermediate level and see what happened

ah

might as well so he scaled it up

intermediate level again pretty much a

complete failure and he said there's a

you know he went full-scale the process

worked so I failed on a small-scale

field on the pilot plant scale and

worked on the plant scale now how do you

figure that huh

it means that scale-up is a tricky area

and lots of phenomena that happened on

the large scale do not happen on the

small scale and vice-versa large small

scale large scale for example okay this

morning you may have gotten up and

turned on the faucet and your kitchen

your kitchen or your bathroom whatever

it's a two inch or an inch pipe right

flow rate comes out no problem you turn

it on and off without paying much

attention you don't expect any water

hammer or shockwaves in your processing

line okay

next door down the road from you is this

huge gasoline pipeline or huge pipeline

whatever it's in it and it's three feet

diameter it is moving at a very high

velocity say ten feet a second okay

maybe three feet a second and it happens

to be 15 miles long how long do you

think it's going to stay

to shut that pipeline down yes my mother

kept track of these chaps shutting down

such a pipeline and took him a whole

morning four hours worth and she was

very upset that we had such lazy man

working shutting down that pipeline

anyway you know big things take time

big things take time and that's a major

difference in the small-scale and

large-scale you take a small baby baby's

moving around all the time especially

when it's a toddler rights and that and

into this older people don't do that

kind of activity right you take a small

child he bounces around everywhere your

parents just sitting there so a small

scale a large scale big difference and

they expect scale up to work if the

scale small scale tests fail and doesn't

rule out the successful operation on a

large scale small scale test surface

area is extremely important volumes not

so much large scale tests volume is

important surface is not so important

it's an L over L squared for area L

cubed for volume it's an L squared L

cubed effect and if you want a design

mistake there it is sizing equipment you

have l squared L cubed effects

everywhere if you don't pay attention to

that sort of thing you're going to pay a

price

small and large scale effects are

different due to heat transfer heat

transfer large scale versus heat

transfer small scale small scale heat

transfer is easy

that's why small people or small animals

will just think people will die in a

blizzard

whereas larger people are likely to be

more survived more easily in a blizzard

anyway there's all kinds of examples of

where small scale or rapid heat transfer

versus large scale which you

the each answer is very slow correct

operating temperature large-scale or

lower than that indicated by pilot

plants yeah

various things in here differences in

size number one small dryers limit

particle size large tires can produce

coarse particles with difference in

particle size distribution difference

number two small dryers lose heat more

readily and large dryers this is what

we're talking about so you have

differences in hygroscopic and

thermoplastic materials different size

difference three a relationship between

small R scale dependent upon the product

difficulty generalized relationships

dust row experience is vital and

proprietary there you go what's really

funny about proprietary stuff is that

well it could be extremely important or

it could be worthless but its

proprietary all spray dryers offer test

facilities I don't know if all I'm do

but anyway nevermind file it buy

equipment ability could kind of conduct

co-current tests rotary or nozzle

ability operate open closed or semi

closed should have the ability to

produce finds and courses should have

the ability to handle a two is ninety

two his speeds should have the ability

to operate the safe manner represents a

sizable investment I like to always go

on the cheap myself I didn't my

department had comes to me since I got

all this money I want to spend them and

he says why don't we buy new laboratory

equipment for the unit ops lab I look at

and say sir I'm an engineer I don't need

equipment I can use what I have and do

retrofits on it he gets very upset they

can't spend his money or wastes his

money

really this is

I'm sure masters welcome masters

obviously was a superior gentleman of

great knowledge there's no question

about it anyway that's drier well you

have what our sizes we want to look for

the size two and 1/2 meters different

variations one and a half to two metre

diameters and down here one the one and

a half meters 0.8 to one meters there we

go so looks like we want one meter and

above different particle sizes being

produced the atomizer what type of

heating ancillary equipment and the best

place to get the equipment quickly is

used equipment market also combine that

you buy the equipment and use the

equipment

people and create a bunch of people I

imagine take it to a local machine shop

you have control over everything ah

get your pilot bank real quick the

bigger the better for a pilot plant

uh-uh

no actually there's a you want have

versatility and with things Ling and get

very large become pretty much fixed so

to add versatility you one smaller size

and so you have a trade-off there are

some statements here about exhaust

systems of all dryers permit

installation of cyclone strike wet

scrubbers bench scale studies before

pilot plant studies Wilhelm maybe yes

maybe no select the formulations most

suitable from CI lab tests like the most

suitable atomizer effect formulations

evaluation assessing the suitability of

material to spray drying results

obtaining representative powder samples

confirm Optive operation ability

optimizing conditions determine

ancillary equipment residence time now

this is a personally from one to ten I

never did care for residence times

essentially because I'm not quite sure

whether they're all that useful like

resident Stein's aren't useful okay some

point I have a student comes to my comes

into my course nine o'clock it comes in

quickly falls asleep sweeps through the

entire course

excuse me sleeps through the entire

lecturer I get up try to leave before he

wakes up I don't want to wake them up

it's horrible getting woken up anyway I

try to sneak out anyway easy in there

sleeping so lots of materials will enter

a tank and not participate in the

operations in that tank

obviously spray dryers that's not it

kind of happen unless of course there's

a side stream that trickles down the

side wall which is from a plug or hole

in the feed pipe or misdirected nozzle

or one side of the wheel has got

substantially more liquid coming off of

it to the other side of the wheel and

Iowa stream running down the wall so all

those are relation residence time then

we got two residence time the air we

could probably figure that out since the

air is probably well distributed you

could take volume divided by air flow

rate and get some sort of residence time

for the air

now then the real serious question is

what's the residence time for the drops

how long does the water or the liquid

run down the wall before it exits is it

part of the product stream have you

noticed it in the particle stream at the

exit

what's a residence time of the drops

what's the residence time of the

particles serbian wall built up is there

a dusting of the material on the wall so

the air residence time is probably

pretty cool I mean you got that nailed

down but the particle residence time now

that's a real how can I say a conundrum

control room anyway so usually a process

volume divided by flow rate now then if

you break this down according your

particle size and you take individual

particle sizes their residence time is

going to be huge

so flow rate of a certain particle size

is going to be very low and it's going

to supposedly be in there for an awful

long time so you gotta worry about

hold up volume of your particles and

that determines your residence time so

if you got the material to thank bottom

and excuse me in the cone and it's there

for 20 to 30 minutes before it comes out

and it's exposed to the conditions then

residence time for the product is

another matter residence time for the

product it's the holdup volume of the

product in the chamber divided by the

exit flow rate of the product so air is

easy it residence time for these solids

or the drops are different manner

what's the residence time of a drop

before it all evaporates hold up volume

of the product may not be known you

whether there's timers use determination

of chamber volume you gotta have a flow

rate chamber volumes should have

velocities I suspect below 60 meters of

second excuse me

60 feet a second or below 30 feet a

second which is abrasion level

velocities so there's a certain chamber

flow our velocities that I have

determination of particle drying time

from the favours book it's often assumed

that the minimum particle residence time

is the residence time of the air well

that may be true or it may not be true

much much most products as it was it's

not much higher than the air residence

time so drying so the drying can take

place there you go product exit flow is

much smaller than the air exit flow

optimum residence time for a product is

the time for the completion of desired

moisture removal with the minimum

increase in temperatures dry product the

longer it's in there the more likely it

will heat up sort of like if I take

french fries I've dried the french fries

by boiling off the water and are drawn

in a fryer right so now the french fry

has lost lost a lot of moisture and it's

dried and now it starts to brown and

browns because it's at a higher

temperature it's no longer being

protectively cooled by the evaporating

water and a temperature the french fry

increases and increases some more and i

get the burning reactions on the surface

okay so the so your question is how long

is the french fry in the fryer before it

starts to turn brown or before it starts

to turn charcoal charcoal charcoal level

notice the residence time of a french

fry in a fryer is much longer than the

residence time of the evaporating

moisture out of the french fry so we

have coarse ways

need longer residence time than fine

sprays for the same moisture content of

course sprays means big drops so depends

upon the atomization ability of your

atomizer course versus fine lower

temperature temperatures are required

residence time can be very long the idea

tall towers residence time cover range

from five seconds to several minutes

larger residence times usually mean

bigger structures bigger drying chambers

short residence times 5 to 20 seconds

semi dry state can withstand turbulent

the air handling can withstand contact

with hot air can be dried in cyclone

dryer a long residence time about 40

seconds heat sensitive need lower drying

temperatures can tree stand

Kent cannot withstand high temperature

airs air particles are freefall against

the rising air flow meet tall counter

current towers ok counter current if the

Coker and quickly leave counter current

and slow it down a bit dried and Coker

and there are divers in rotary air two

to forty seconds so we have our range or

residence times here now I'm going to

clip through these summaries of steps

for a drier layout design well the

system open closed semi closed this is

getting away from everything we just

talked about this is a completely new

subject dryer designs well up here

you're gonna have standard self

advertising here we have counter current

mixed rotary pressure to fluid and

residence time short long medium any

pretreatment mmm Inlet temperature

selection obviously got spend some time

to see what the grade you

product I mean excuse me what degrades

your liquid your feed may be quite

protective mm-hmm

by the liquid on it outlet temperature

as low as possible

hating input direct or indirect you do

not want to have indirect drying unless

you required all right air dispenser I

mean all kinds of air dispensers really

want a swirling action at least I would

think you want to swirling actually keep

things off the wall more what side of

things do you have in the way of

particle collection whether you run wet

cyclones

I would imagine what cyclones are quite

efficient in collecting particles and

you have a chamber atomizer selections

minimum brining chambers at maximum

evaporation capacities with rotary

atomizers Wow other components heaters

fans pumps another collectors assessment

of hazards which can be quite enormous

right that's explosions and fire risks

minimum ignition temperatures in the

cloud by air foam for metal exposure

concentration minimum ignition energy

expects right there maximizing explosion

pressures while oxygen concentrations

where ignitions won't occur the toxicity

factor chemical activity of the

emissions where was that I was at Jack

Daniel's distillery and for some reason

these trees were coated with some of

some of the products from the distillery

I don't know I was I didn't might have

known

local fauna recognized safe procedures

available on a crisis safe emission

limits safe level of working

environments safety an exception that

limits its kind of odor generation

deodorizing and temperature

I would certainly visit the Chemical

Safety Board videos on safety and their

and just see if they have any dryer they

have dust explosions quite quite often

but then they have potential drying

accidents that have happened see if you

have any information on that then any

previous accidents recently and there

are accidents blow up to plants so then

you don't have any place to go to work

you know I mean a terrible and you ain't

got a place to go to work that's why you

have to stay on with the life right

anyway particles closed systems ends la

negra systems anyway about your

particles what do you have and I've gone

through this with my question and

grinding and any way that serveth

particles I like this way and I have

this particle distribution and when I

lose my static charge they fall off and

now over here size measurements you

actually believe your size measurements

like going right but you sure recognize

two major areas of size measurements a

Stokes drag region and regions where you

have large particles so you have Stokes

drag measurements and then you have

large particle measurements I was

listening to this chap talk about the

device that he was secure the equipment

that he had their cell about how to

measure particle size distribution

and he was dealing with granular

materials and I asked him what happens

if you have a flake hopefully and

without skipping a beat he said

multiplied by 2.6

I was quite amused by his answer anyway

greater iid power greater strength

greater impact strength smoother

irregular-shaped

he'll regular sharp edges you don't want

sharp edged edges for an initiator

explosion initiator and you don't wanna

you want abrasive edges so there's just

some comments about solids

these are the actual particles and these

are simulations of the particles the way

would help to realize that you don't

even start worrying about particle shape

and what you're doing is you're adding

all these harmonics together anyway

there's mathematics to that skip it I

sort of lifted this from question and

grinding to extremes exists between the

influence of the material in the dryer

shape character being dried has little

influence on shape spray dryer has

little influence the character of the

material being dried as the most

influence of the lines shape spray

drying has little influence then on the

other hand you can have the spray drying

methods most influential in shape flow

regime and material properties have

little influence right so you have to

exchange the Machine controls or the

material control so reality I somewhere

in between I thought that was kind of

interesting I lifted that from the

crushing and grinding book right and so

we have non solvent or excuse me non

aqueous solids his system

many materials are first produced in

organic solvent okay sometimes it

softens to replace with water before

drying however so air and water not

difficult G Wells open cycle however in

some applications switching to water is

not possible so now you have to worry

about solvent evaporation in a closed

drying cycle right cheap low cost many

disadvantages okay the idea is we do

heating we do the drying and then we

need to be convincing and we start all

over again

solids come out one side the liquid

comes out of the condenser unit as the

other side pink comes in basically

hexane with whatever its carry so the

psychometric chart is for xane and

nitrogen so if you're going to have a

solvent with another gas or with the gas

you got to come up with this

psychometric chart for that combination

so you grab a hold of a local

thermodynamics and you pay them a little

money and out pops the site chart for

that combination or if you're fortunate

to have a thermodynamics is in the

company you give them the site ask them

to develop the site chart for you so

we'll leave it that that you got sight

chart and I assume you can do that okay

a major disadvantage

hazards and handling solvents design

complexities of a closed system overall

drying solvents another realm of drying

water NetherRealm from drying water you

have exposure limit slower explosion

limits and upper explosion limits

anything above the upper explosion limit

right should be considered unsafe

because the upper explosion limit can

easily be diluted

to where reaches the explosion limit or

gets to the location where this is an

explosive mixture so anything above you

L is unsafe anything between these two

is obviously unsafe now the lower

explosion limits kind of flaky to

because you know I don't want to hurt

your feelings but gas is separate right

so the concentration and one layer of

gas can be quite different than the

concentration and another layer guests

case in point

there was a second floor where there

were storage tanks for carbon

tetrachloride and so the top of the tank

became saturated with carbon Tet and

overflowed and along the side walls of

the tank went down the first floor and

over the weekend formed a carbon Tet

layer gas layer and down on the first

floor and a people came to work started

up the the way you called lift it was

gas-powered high lift and because the

carbon Tet layer was still below the

ignition

there wasn't any accident however they

left the machine on during lunch time

the carbon Tet that raised up to the

level of the ignition due to the that

was gas powered and the system exploded

on them so whenever you're dealing with

gas you gotta watch out it may mean it

may separate onion

have you ever seen fog in the morning

it's quite separated out for the rest

and he with the upper explosion limit to

make sure can easily be diluted and

reach the explosion limit gases can

separate heavier gases Sinclair gases

rise hotter gases rise right co2 gases

saying gases are most often considered

well mixed but they're not I don't know

you gotta you gotta recognize nature's

out to get you I don't know if you

realize this it's just from a

pessimistic point of view

Nature has a habit of reaching out and

killing y'all oh no you gotta you know

you gotta be cynical about weather

mother nature likes you or not so I am

always suspicious I'm suspicious I'm

suspicious

uh-huh never trust the obvious standard

safety problem causes many many

explosions and again Chemical Safety

Board you look under separating gas

explosions and see what you come up with

the gas is 1/4 the LEL it could be tense

potentially separated in two volumes one

which is above the LEL to lower

explosion women never trust the gas gas

forms explosive mixtures with most

solvents they need is to avoid oxygen

air can't be used as a dry meaning of

solving systems trying gas or drying

media must not cause any problems with

solvent or product so typically you're

looking for a non reacting gas you're

looking for an inert gas seeing recycle

nitrogen comes to mind carbon dioxide

comes to mind I'm not quite I'm not

quite comfortable with methane either

these two I know don't burn methane

however if there's a leak and methane

comes out of the leak you could have a

little torch there at that week I'd be

an interesting way of identifying leaks

by again I don't like that idea the

basic premise of safety is you really

want to run scared I mean you want to

run scared okay I don't know how brave

you are but I don't want to be dead and

brave okay anyway just a social comment

their products or solvents may be

hazardous toxic required to close system

solvents may be valuable and recovery is

an economic necessity most organic

compounds are flammable recoveries by

condensation examples are here sometimes

it's cost-effective to evaporate the

solvent even though it could be replaced

by by water you know you just let this

thing sit there and agitate it with an

impeller and you'll have a natural

operation occurring so put that through

a condenser and don't spray drying

solvents usually dictated by a process

solvents could be suited to drying

operation okay the best way to avoid a

difficult problem is of course go around

it easy you solve and slowly need no

hazards it cannot be managed causes no

drying problems well collaboration is a

major driving problem solvents may be a

mixture there you go

miscible or partially miscible now

you've just raised the level of

difficulty I think just as a comment

here complex drying low boiling comes

off first higher boiling right residual

moisture information

sparse make sure the solvents may be

more trouble than they're worth

condensation may be an issue yeah

multi-component condensation is an issue

they do a distillation column fairly

easily or they can design heat

exchangers fairly easily but a condenser

with multi phases in it Multi immiscible

and then miscible liquids varying heat

heat capacity is varying boiling

temperatures ahead it's not quite an

interesting device you have there okay

make sure solvents may be more problem

than they're worth let's go on

multi-component condensation is tricky

you have diffusion variables form a

diffusion barriers form multi-component

solvents are an alternative but unlikely

better than a single solvent efficient

solvent drying just like water proved

with higher Inlet temperatures lower

outlet temperatures improved with low

duty ie low inland oyster again I can

imagine that with the solvent situation

decantation wouldn't hurt let it sit

there and a moisture will flow out

quality of drying gas determines

equipment size approach to saturation

determines product moisture and there we

go solid drying problems may not need

spray drying initial drying rates faster

than water because alone eat late meat

solvents usually have lower you can keep

them water so I think evaporate just

sitting there can cause problems

separates before the drops formed that

would be like in cotton candy or party

string string filaments clustering

discrete particles if this happens you

own the is greater our clusters may be

held together through static cling

hopefully static charge hopefully there

in any oxygen around

clusters may have loose bulk density and

are mostly and are almost always

unacceptable

there you go solving drying slow driving

rate slow the drying rate and drop rate

for mation possibly dilute to set it's a

solution generally not a good idea

lower Inlet temperatures produce large

drops okay

cooling gas may be introduced to contact

the liquid maiden information

moisture content outlet gas can be sent

at sixty times greater than air water I

mean the evaporation maybe that's a lot

basically lower the evaporation rate by

lowering the driving force for operation

you need to get the saturated gas out of

the drying chamber often the solids have

an affinity for the solvent this causes

a solid solid solid they have a higher

moisture content lower moisture contents

could be reached with higher outlet

temperatures for the gas for this solid

and gas longer exposure times and

secondary follow-up drier even traces of

solvent may be unacceptable I mean can

you imagine getting instant coffee with

tastes of hexane in it I mean I don't

even know affects things permitted

anymore must be something else they're

using this is oppositeday or water

drying retain water is generally

harmless where it serves as the serves a

useful purpose closed systems

requirements recovery solvent because of

its value of safety environmental

reasons prevent explosive mixtures

solvent with air recycled drying gas

because of its value wells all the

solvent coveri of all the solvent

prevents vapor escape sparks or other

initial surfaces dry them dried to

moisture content and will you harmful

effects of solvents in the product where

might necessarily precautions for

toxicity and hazards here should be

indirect

right indirect dryer we went over

indirect trying not to bleed should be

much smaller than the air water systems

the amount of bleed if you have a bleed

is that it passes through a flame

scrubber serves as a backup collector

and condenser okay

yeah fed solids to cool gas sufficiently

convinced the vapor P is the same

solvent as if the tubular condenser

should be used but would suffer from a

very low heat transfer rate due to low

pressure inert gases design okay

take a look at some design I have to

consider the properties of each solvent

design separates a solvent from the

solids separate to solvent from the gas

recycle the gas major prevent no to

build up weeks in or creates explosive

mixtures or in or out create explosive

mixtures I word itself indicating less

dangerous

you don't want buildup of oxygen is a

big one our leaks herself indicating

most dangerous occurs with systems that

operate positive pressure washing and

levels should be analyzed on a

continuous basis with special care doing

start up start up starting up right the

whole bloody thing is filled with an air

right hazards of solids mandate extreme

caution the handling and equipment

design Godrej exists for some solvents

viral controls exist for some solvents

special problem not recognized I don't

know if it's not recognized or not but

static charge boat

just pumping a solvent through a pipe

can cause a spark okay now the question

is what do you use with that spark if

you have no oxygen around your okay one

case in point

benzene through a plastic pipe looked up

lit up like a fluorescent light to a

bright light bulb and if it had oxygen

you got buffs the area right because it

would be altered could ignite an

explosion if released need to ground

everything wrong cables from flanges

around flask ground everything used on

sparking moving parts and tools on that

explosion proof so they claim I like

explosion proof right explosion proof

until it isn't non Sparky motors

minimize leads good flanger seals

doubled mechanical seals gas cooling

purging used by Gauss's uses an air -

you might collect up that there gas

produces gas to be bled out any

introduced gas has to be bled out cost

drying volumes much lower than water

systems latent heat of vaporizations

much smaller much higher ratio solvent

to gas much IR carrying capacity of gas

to take away the solvents almost always

the lower energy costs and small vessels

again you know a single solid and the

solids just put in a pot make sure

everything stirred up and draw a vacuum

or heat it a little bit have a condenser

at the top and away you go you avoid

spray drying altogether you don't want

to complicate things you want to keep it

simple

kiss principle right costs for total

system operating costs may not be lower

in additional anions closing

Loup adding the condenser providing

explosion of any indirect heaters upper

limit maximum drying temperatures three

or four 50c or four twenty five tissue

items may need to rework the solvent by

distillation right special building

features explosion venting

slowly improve equipment iron surance

cost you want to put this in more

explosion proof facilities in other

words you know if there's going to be an

explosion you want to know you want to

direct that explode explosion to a

certain certain direction bunkers what's

your called right anyway our insurance

pass interesting twist sometimes it's

possible to use a solvent as a drying

gas this eliminates inert gas

requirements solvent has to be

superheated much smaller equipment

condenses simple without in there gas

when requirement dry outlet has to be

well above the solvent boiling point

right which means you're going to be

high temperatures prevents condensation

and the dryer may be difficult to reach

desired moisture content may require a

second dryer nothing wrong with staging

cleanup example cleaning out be used to

solving said closed system right you

need the right equipment saw was

representative toxicity problem-solving

soft so give off toxic monomers product

receiver needs monitoring a product with

incomplete drying gives off vapor and

forms an explosive mixture and the

collector are often difficult to seal

collector completely or adequately okay

I just thought I'd throw out some of

these obviously 2008 it's a long time

ago and they claim this is recent

develop some spray drying so we

these chaps all very capable people I'm

sure what's interesting is look at this

stuff they're spray drying and creating

see so man look at that thing why that's

gotta be unique that's fairly

interesting as well then we have these

things Jase oh man you see the spheres

have puffed up and then shrunken down

there must be an exit hole somewhere

same are they here these things started

out as a very big sphere and as they

cool down you had to fusion whatever

coming out really cool stuff huh

spray drying CFP there's a book on it I

think there's in a book

yeah that's your assignment I want you

to buy this book and read it I mean it's

probably 2 or 3 inches thick 10 pages

the night bring you up to the recent

stuff and it spray drying and of course

I love you too

it's one of the reasons why my my videos

on YouTube I think it's very fascinating

all the information that's on the

YouTube so I like going to school I need

to you can see ligaments breaking you

can see break up a liquid Jets and

binging jet diameters to fluid nozzle

stuff dancing water spray curlers they

have one where they have two jets

meeting creating droplets and in space

and then they cross section the the

computer simulation ok and fantastic

video Oh sock number they also have a

video showing Boggs Oh H SOR GE I think

maybe the spelling maybe we saw also has

some videos yeah those are get one too

under pretty cool anyway I leave videos

on YouTube again fantastic

I guess that closes it out and I leave

you with happy drying to you spray

drying to you and again the major books

that I use Cooke and Dumont I was

fortunate enough to work with them a

great bunch of guys

masters I was too young to know and

Wallace did a fantastic job with this

process chemical process equipment the

first book came out it's really great

book and of course I'm sure these guys

did something to improve it but anyway

again the videos oh I love these surface

tension videos and you can watch o SOG

number videos it's great well that

concludes my spray drying lectures I

hope you enjoy them I hope it makes you

some some gives you some information ok

I hope I helped you out when your spray

drying anyway I'm going to turn it off

and stop the recording now