Cryogrind Sem Rep (1)

8/12/2019 Cryogrind Sem Rep (1)

1/22

A

Seminar Report

On

STEAM POWER PLANT

By

S.Hemant Kumar Reddy

11!1"#$

%EPARTMENT O& ME'HAN('AL EN)(NEER(N)

*()NAN (NST(T+TE O& TE'HNOLO), AN% MANA)EMENT

BERHAMP+R

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2/22

RTIFI ATThis is to certify that the seminar report entitled STEAM POWER PLANT

has been submitted by S.HEMANT K+MAR RE%%, under my guidance in

partial fulfillment of the degree of Bachelor of Technology in Mechanical

Engineering in Biju Patnaik Uniersity of Technology! "ourkela during the

academic year #$1%$1'(

)uided by* Mr( Priyabata +ahu

,ead -f .epartment!

.epartment of Mechanical Engineering

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A KNOWL DG M NT

/ aail this opportunity to place my profound gratitude to my guide Mr.

Priya-ata Sau/ .epartment of Mechanical Engineering for his constant

superision! inspiration and encouragement! right from the beginning of the seminar

report entitled STEAM POWER PLANT.

/ am also indebted to %r. Pra-u Pra0ad Mi0ra! ,-. of Mechanical

Engineering! for his help and adice in completion of this seminar report(

0inally! / ould like to e2tend my sincere thanks to all my friends and all

persons ho hae rendered their aluable help directly or indirectly in the

completion of this seminar report(

+(,emant 3umar "eddy"egd( 4o* 1$$1%$1#'5 .epartment of Mechanical Engineering

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ABSTRACT6ryogenic grinding permits heat&sensitie! thermoplastic! and elastic

materials to be economically ground to ery small particle si7es( The cryogenic

process actually embrittle a material prior to si7e reduction and controls heat

buildup in the grinding e8uipment( The result is high product 8uality and system

productiity(

6ryogenic grinding inoles cooling a material belo its embitterment

temperature ith a cryogenic fluid! typically li8uid nitrogen or! in certain

applications! carbon dio2ide( 9fter cooling! the material is fed into an impact mill

here it is reduced in si7e primarily by brittle fracture

6ryogenic grinding is used for grinding spices! thermoplastics!

Elastomers! color concentrates! and similar materials( /t is also used to recoer a

ariety of scrap materials! such as factory scrap rubber and scrap tires! and to

separate the components in composite materials(

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ONT NTS

SL NO. TOP(' NAME PA)E

1. INTRODUCTION

6

2. APPLICATIONS OF CRYOGENICS

7

3. CRYOGENIC GRINDING PROCESS

8

4. CRYOGENIC GRINDING SYSTEM

9

5. CRYOGENIC GRINDING TECHNOLOGY

10

6. ADVANTAGES OF CRYOGRINDING

11

7. APPLICATIONS OF CRYOGRINDING

12

8. PROLEMS !ITH CONVENTIONAL GRINDING

14

9. CRYOGRINDING !ITH LI"UID NITROGEN

15

10. !OR#ING OF CRYOGRINDING PLANT

17

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11. RESULTS OF E$PERIMENTAL STUDIES

19

12. FUTURE PROSPECTS

20

13. ILIOGRAPHY

21

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1.INTRODUCTION

The term 6ryogenics< originates from )reek ord hich means creation

or production by means of cold( 9s prices for energy and ra materials rise and

concern for the enironment makes safe aste disposal difficult and 6ostly! resource

recoery becomes a ital matter for today=s business( 6ryogenic grinding technology

can efficiently grind most tough materials and can also facilitate 6ryogenic recycling

of tough composite materials and multi component scrap( The heart of this technology

is the 6">-&)"/4. +>+TEM( /t employs a cryogenic process to embrittle and

grind materials to achiee consistent particle si7e for a ide range of products( The

cryogenic process also has a uni8ue capability for recycling difficult to separate

composite materials(

6ryogenic grinding is a method of podering herbs at sub&7ero

temperatures ranging from $ to minus 5$?0( The herbs are fro7en ith li8uid

nitrogen as they are being ground( This process does not damage or alter the

chemical composition of the plant in any ay( 4ormal grinding processes hich do

not use a cooling system can reach up to #$$?0( These high temperatures can reduce

olatile components and heat&sensitie constituents in herbs( The cryogenic grinding

process starts ith air&dried herbs! rather than free7e&dried herbs(

+olid materials are ground or puleri7ed by ay of hammer mills! attrition

mills! granulators or other e8uipment( 9 smaller particle si7e is usually needed to

enhance the further processing of the solid! as in mi2ing ith other materials( 9

finer particle also helps in melting of rubber and plastics for molding( ,oeer!

many materials are either ery soft or ery tough at room temperatures( By cooling

to cryogenic temperatures ith li8uid nitrogen! these may be embrittled and easily

fractured into small particles(

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9 scientifically controlled study using four herbs as conducted at

0rontier ,erbs in the 0all of 1@@;! comparing cryogenic grinding methods ith

normal grinding methods( The herbs tested included feerfe! goldenseal! alerian

and echinacea( /n all cases the cryogenically ground herb contained greater amounts

of the constituents tested( 0eerfe herb shoed the greatest difference! ith the

cryogenically ground herb containing #1(A higher leels of parthenolide! the

primary actie constituent( Calerian root shoed an 1A(5 increase in alerenic

acid hen cryogenically ground( )oldenseal root shoed a 1;(' increase in

berberine and 1$(5 increase in hydrastine( Dastly! Echinacea purpurea root shoed

a 1#(1 increase in total phenolic content in the cryogenically ground root( Test

results ere obtained by ,PD6 high performance li8uid chromatographyF methods(

6ryogenic grinding as shon to significantly affect actie constituent

leels in herbs( Test results shoed an aerage increase of 1:(; in constituents

tested in four medicinal herbs hen they ere ground cryogenically( The range as

1$(5 to #1(A! indicating that some herbs are affected more than others by the

temperatures at hich theyGre ground(

2. APPLICATION OF CRYOGENICS

The major areas in hich cryogenics find its applications are * &

1( )a0 (ndu0tryH in air separation( The olume of production of nitrogen and

-2ygen by cryogenic separation of air is the important of the separation of

air! refrigeration and separation( /n the separation column! the difference in

the boiling points of the constituents of air is used to separate them out(

#( 9s te 0oure o2 3a0( 0or e2ample! the breathing o2ygen needed for the

pilots of the fighter aircraft is supplied by apori7ing li8uid o2ygen on board(

/n this ay is a eight reduction of ;: and space reduction of A:(

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%( (n 0pae re0earH as rocket propellant and for space simulation( The most

important adantage of cryogenic fuels is that these hae ery high specific

impulse hen compared to other fuels specific impulse is kgs of thrust

produced per kg of propellant per secF( The alue is appro2imately :$$ for

cryogenic fuels hereas it is about #:$ for alcohol o2ygen mi2ture(

'( (n -io4o3yH for preseration and in treatment of diseases(

:( (n 2ood indu0tryH for food handling and processing

;( (n e4etroni0H both semiconductor and superconductor electronics for better

signal to noise ratio speed etc

5( (n mi0e44aneou0 app4iation0 such as cryogenic grinding ! free7ing

pipelines for repairs! shrink fitting! fire fighting! etc

A( (n mediine H Magnetic "esonance /maging! Magnetic "esonance

+pectroscopy M"+F! Magneto 6ardio )raphy M6)F! etc(

@( (nnu4ear and i3 5 ener3y py0i0

1$( Meta4 2a-riation

3.CRYOGENIC GRINDING PROCESS

+ince almost all materials embrittle hen e2posed to cold temperatures!

cryogenic si7e reduction utili7es the cold energy aailable from li8uid nitrogen to

cool! embrittle and inert materials prior to and or during the grinding process( 9ll

materials hich due to their specific properties at ambient temperatures are elastic!

hae lo melting points! contain olatile or oily substances! hae lo combustion

temperatures and are sensitie to o2ygen! are ideal candidates for cryogenic si7e

reduction(

Physical properties of li8uid nitrogen is produced by the separation of air

into its components in an air separation plant and is distributed in acuum insulated

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transport essels to the end user here it is stored in a acuum insulated storage

essel till it is used( 9t atmospheric pressure li8uid nitrogen is at a temperature of H

%#$ deg 0 and possesses a latent energy content of @' BTUIDB resulting in a total

cooling energy content of 15@(; BTUIDB( 4itrogen is anon&flammable! non to2ic

and inert gas hich makes up 5A($@ of the air e breathe( /t has the characteristics

of an inert gas! e2cept at highly eleated temperatures! and does not form any

compound under normal temperatures and pressure( .ran from the li8uid phase!

nitrogen generally has a purity of @@(@@A ith a de point less than H 1$$ deg 0

and is ery dry(

Di8uid 4itrogen at 55(; 3 is used to embrittle a material prior to si7e

reduction( -nce brittle the material is much easier to grind( Jhen 6">-&)"/4.

system is used to recycle composite or multi component materials! to separate

phenomena occur( 0irst! since each component generally ould hae a different

coefficient of thermal contraction! high thermal stresses are created at the interface

beteen the components due to rapid cryogenic cooling( +econd! because each

component material embrittles at different temperatures! it allos selectie

embritlement! hich further enhances separation effectieness( The most brittle

components ill undergo greater si7e reduction( Through careful control of thermal

stress and embritlement ith operating temperature! cleaner separation and recoery

of indiidual components are achieed(

4.CRYOGENIC GRINDING SYSTEM

Jhen using the system! measurable and repeatable results are obtained for

lab or productions calculations( Mills range in si7e from 5&1I# ,P to #$$ ,P( Jith

our cryogenic grinding unit an understanding deelops ith interaction of

e8uipment components and operating parameters( 0actors such as consistent feedrate! precise temperature measurement! mill operating parameters and pressure

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control are critical to the ealuation of cryogenic grinding and cryogenic grinding

systems(

5.CRYOGENIC GRINDING TECHNOLOGY

0or puleri7ing many materials! cryogenic grinding technology increases

productiity and loers poer costs( Many elastic or KsoftK materials are ery

difficult to puleri7e! re8uiring long cycle times and high energy consumption( This

combination decreased productiity and increased costs unnecessarily( 6ryogenic

grinding inoles cooling a material belo its embrittlement temperature ith a

cryogenic fluid! typically li8uid nitrogen or! in certain applications! carbon dio2ide(

9fter cooling! the material is fed into an impact mill here it is reduced in si7e

primarily by brittle fracture( This process has seeral benefits*

9bility to process relatiely KsoftK or elastic materials that cannot

otherise be ground

/ncreased throughput

"educed poer consumption

+maller si7e particles

Minimal loss of olatile components

Doer capital inestment

Probably the greatest benefit proided by cryogenic grinding is the ability

to grind KsoftK or elastic materials that otherise could not be ground! or could be

ground only ith long cycle times and high energy use( By embrittling the material!

fine poder or crumb can be obtained easily and ith a minimum e2penditure of

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energy( Because embrittled material grinds easily! the throughput for a gien mill is

substantially increased and less poer is used per pound of material ground(

6ryogenic grinding also reduces the material to particle si7es difficult or

impossible to attain ith ambient temperature grinding( The dry! cold! inert

atmosphere in hich the grinding occurs minimi7es reaction ith the material and

reduces the loss of olatile components( Jhen processing composite materials!

cryogenic grinding usually makes it easy to separate the arious materials(

6ryogenic grinding is used for grinding spices! thermoplastics! elastomers!

color concentrates! and similar materials( /t is also used to recoer a ariety of scrap

materials! such as factory scrap rubber and scrap tires! and to separate the

components in composite materials(

6.ADVANTAGES OF CRYOGRINDING

1( ,igher production rate

#( Doer energy consumption

%( 0iner particle si7e

'( More uniform particle distribution

:( Doer grinding cost

;( 4o heat generation hich is good hile grinding spices!

pharmaceuticals and scrap plastics

5( Proides an inert atmosphere thus eliminating the possibility of

o2idation

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7.APPLICATIONS OF CRYOGENIC GRINDING

'ryo)rindin3 o2 0tee4

The large amount of thermal energy generated during machining and grinding at

high speed and feed rate raises the temperature at the cutting 7ones e2cessiely(

This eleated temperature leel under large cutting stresses accelerates plastic

deformation and ear of cutting edges leading to increased cutting forces and

premature tool failure( 6ooling ith conentional cutting fluids in the form of

jet or mist is unable to sole the problem( /n such cases cryogenic cooling by

agents like li8uid nitrogen ill improe the situation( /n the case of cryogenic

grinding! the li8uid nitrogen from a reseroir under air pressure comes out a jet

from a no77le to the spot here cooling is desired( The jet impinges on the ork

surface at the grinding point from a suitable distance and angle( The amount of

temperature reduction due to cryocooling ill increase the grinding depth(

Because of the e2treme cooling action! the life of the grinding heelLs ill be

increased(

Termop4a0ti0

To hich 4ylon! PC6! Polyethylene! and polypropylene belong are commonly

used in podered form! for but not limited to! a ariety of applications such as

adhesies! podered coatings! fillers! resins and plastics sintering and moulding(

These poders generally can only be produced in high production rates and fine

particle si7es utili7ing cryogenic si7e reduction(

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Termo 0et0

To hich natural and synthetic rubbers belong are important recyclable

materials( Under cryogenic si7e reduction these materials can economically and

at high production rates be ground into fine poders! used as filler! be recycled(

Ade0i6e0 7 Wa8e0

These materials at ambient temperature are generally pliable and sticky and hen

ground ould form e2cessie deposits in the mill building up heat! increasing

energy re8uirement and eentually shutting don the si7e reduction process(

Under cryogenic temperatures these products become brittle and can be

puleri7ed ith much less energy and ithout forming deposits(

E8p4o0i6e0

E2plosies e2plode hen their ignition temperature! in the presence of o2ygen! is

achieed( 6ryogenic si7e reduction performs to tasks hen grinding e2plosies

it reduces the temperature of the material ell belo its ignition temperature and

remoes the o2ygen from the system thereby eliminating the possibility of

combustion( The product to be ground is filled into the olumetric scre feeder

here it is metered at a specific rate into the cryogenic pre&cooler( /n thecryogenic pre&cooler li8uid nitrogen is injected and combines ith the product

thereby cooling and embrittling the product( The product is then transported!

along ith the cold gas generated by the eaporation of the li8uid nitrogen! to the

grinding mill here it is puleri7ed( The puleri7ed product then goes through a

classifier here it is separated into arious particle si7es and packaged( +hould

oersi7e material e2ist this can be fed back into the olumetric feeder and

recycled into the system( The cold gas from the mill is recycled through the filter

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or bag&house and makeup air back into the mill( E2cessie cold gas is ented out(

/n addition the cold dry nitrogen gas keeps both the classifier and bag&house free

of moisture and inert! preenting the possibility of dust e2plosions and buildup of

product(

Spie0

+pices like Pepper! cinnamon! chilly! )inger! 6umin seed! 4utmeg! )loe etc(!

hae a characteristic taste and aroma( These characteristic 8ualities are essential

in them to hae their alue as Nspice=( These 8ualities e2ist in them due to the

presence of etheric oils ithin( The etheric oils hae their boiling points ranging

don to :$o6( .uring conentional grinding! due to the heat produced by friction!

the temperature of ground spices shoots up to about @$o6! here by most of the

etheric oils oil off resulting in inferior 8uality of the ground product( This inferior

8uality is eident by the reduced taste and aroma(

8.PROBLEMS WITH CONVENTION GRINDING

Lo00 o2 eteri oi4

The applied energy gets dissipated in the form of heat O@@F and hence the

temperature in the grinding 7one rises to more than @$o6 resulting in loss of

etheric oils hose boiling point ary from :$o6 to %#$o6( This results in the

inferior 8uality of the ground product(

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'4o33in3 and 3ummin3 o2 te mi44

+pices like nutmeg! cloe! cinnamon! etc((! contain high leel of fat hile

capsicum! chilli! etc! contain high moisture content( These cause clogging and

gumming of mill thus affecting the throughput and 8uality of the ground

product( ,igh moisture content materials often stick to the parts of the mill(

O8idation and re4ated de3radation

.ue to intimate cyclone effect of the air in the icinity of grinding 7one!

aromatic substances in materials o2idi7e and become rancid( /n addition the

formation of fresh and e2posed surfaces due to grinding! accelerates the

process of o2idation(

.ADVANTAGES OF CRYOGRINDING WITH LI!UID

NITROGEN

Hi3er retention o2 eteri oi40

.ue to loer operating temperatures! the etheric oils ill be retained in

the product almost to the original leel( ,ence the ground product ill

obiously be better in taste and aroma! ith the improed alue as

Nspice=(

Pre6ention o2 o8idation and ranidity

The heat deeloped during grinding ill be absorbed by li8uid nitrogen

hich in turn ill be conerted to apour( These apours e2pel any air

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in the mill and produce an inert atmosphere during grinding( This

eliminates the possibility of o2idation( To add to this! an ine2pensie!

dry and inert atmosphere for storage and package of ground product is

created(

(nrea0ed trou3put and po9er 0a6in3

.ue to usage of li8uid nitrogen! the ra material becomes brittle( This

in turn keeps the oil and moisture content in the crystalli7ed condition

during grinding and aoids clogging( 9t the same time hen the

material is brittle! less poer is re8uired to crush( Thus cooling ith

li8uid nitrogen increases the throughput due to reduction in specific

energy re8uirement(

&iner parti4e 0i:e

6ryo)rinding results in finer particle si7es of the ground spices( This

eliminates speckling problems and reduces the settling rate of spice

poders in li8uid preparation(

Redution in miro-ia4 4oad

By cooling ith li8uid nitrogen! some bacteria=s hich some others

may become dormant( Thus! hen the ground product is armed to the

room temperature in the inert atmosphere of nitrogenF one e2pects

considerable reduction in microbial load(

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Po00i-i4ity o2 2ine 3rindin3 o2 di22iu4t 0pie0

By use of lo temperatures! the ra materials become brittle hich

causes fibers to shatter( Thus fibrous spices like ginger can be ground

easily to finer particle si7e( ,igh oil content spices like nutmeg can be

ground easily( 6ryo)rinding can be employed for grinding green

spices like chilies ith no pre&drying and also ith the retention of its

original colour(

1".WOR#ING OF CRYOGRINDING PLANT

The spice to be ground is cleaned manually and fed in to the hopper( 0rom

the outlet of the hopper the spice enters in to the ibratory feeder! hich is

positioned ith a small inclination toards the entry of the helical scre coneyor(

The ibratory feeder has a proision to control the feed rate(

The helical scre coneyor has a total length of a metre here the fed

material traels hori7ontally to the grinding mill( The scre coneyor is drien by a

$(5: 3J drie ith reduction gear and inerter control( Di8uid nitrogen from a

storage container is sprayed into the scre coneyor( The time of stay of spice in the

coneyor can be adjusted by arying the speed of the dries( 9 censor monitors the

temperature of the ground spice and the li8uid nitrogen spray is optimi7ed using

automatic feed back control(

The grinding mill is drien by a :(: 3J! % H phase!:$ ,7 motor( The millis connected ith the motor by a flat belt beteen the motor pulley and the mill

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pulley( /nside the mill! stud disc is mounted on the shaft( The circularly projecting

studs fit beteen the similar projecting studs from the rear of the front door( The

spice to be ground gets locked beteen the studs of the rotating disc and studs of the

stationary disc( Jhen the mill is running! the spice gets crushed beteen the studs

and comes out through an optional siee as a ground product(

To the bottom of the mill a collecting bin is housed here the ground

product gets collected( The bottom of this tapering collecting bin! a rotary ale is

mounted hich is drien by a $(%5 3J motor( The rotary ale has A

compartments mounted radially in the same plane( The product! hich comes out of

the rotary ale! is lifted to the storage container by the ,apman ,eli2 coneyor(

This is drien by a $(%5 3J motor( The apori7ed nitrogen from the mill is sucked

by a centrifugal bloer and through the filter assembly if fed back to the mill(

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11.RESULTS OF E$PERIMENTAL STUDIES WITH PEPPER

E8perimenta4 0tudie0 9ere arried out on te 0amp4e0 under di22erent

ondition0;

*o4ati4e oi4 ontent and 24a6or omponent0

The pepper contains the oil&bearing cells mainly in the skin and

toards the tip of the corte2( Jhen the pepper is ground these cells are

broken and olatile oils and flaour components eaporate causing

aroma( /n 6ryo)rinding higher percentage of oils and flaor

components are retained hen compared ith conentionally ground

products( The comparison is shon belo(

+l( 4o( 6omponents 6ryoground F 6onentional)round F

1( Moisture 1%($$ 11($$

#( Colatile -il #(;1 1(1:

%(

0laour compounds

relatie concentrationF &

Pinene!

Dimonene

1('$

A(%$

$(#@

1(1A

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Trou3put o2 te Mi44

0or a constant current of ;9! the throughput of the mill by

6ryo)rinding as :$ 3gIhour at&:$o6F! hich as #(#: times than

that of conentional grinding producing a throughput of ## 3gIhour(

This analysis clearly illustrates a throughput of ##: kgIhour against

the rated throughput of 1$$ kgIhour by conentional method at room

temperatureF could be easily be attained by 6ryo)rinding by suitable

modification of the scre cooler and by ibratory feeder(

12.FUTURE PROSPECTS

9s the cost of ra materials and energy is increasing day by day! it is ery

necessary to use optimum 8uantity and at the same time getting the re8uired 8uality(

By using 6ryo)rinding technology these aspects can be met efficiently( By using

this e can also recycle tough and composite materials( /t has many significant

adantages oer conentional grinding( This also leads to alue addition to the

product( 6ryo)rinding is economically iable! if li8uid nitrogen costs are not

formidable( By adopting 6ryo)rinding technology the leading spice industries of

our country ill earn considerable foreign e2change by e2porting more alue added

processed spices! in place of e2porting hole spices( The techni8ue can be easily

e2tended to processing of PC6 and industrial aste plastics in ie of recycling of

non&biodegradable materials(

13.BIBLIOGRAPHY

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Cryogrind Sem Rep (1)