basic of thermo & reciprocating compressor

8/18/2019 Basic of Thermo & Reciprocating Compressor

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Thermodynamics Thermodynamics

Thermodynamics is the study ofthe eects of work, heat, andenergy on a system.

Thermodynamics is onlyconcerned with macroscopic(large-scale)&microscopic

changes and observations


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The aws of Thermodynamics! The aws of Thermodynamics!

"ummary"ummary#eroth aw If two systems are each in thermal equilibrium

with a third, they are also in thermalequilibrium with each other.

%irst aw The increase in internal energy of a closedsystem is equal to the dierence of the heatsupplied to the system and the work done byit: ΔU ! " #

"econd aw $eat cannot spontaneously %ow from a

colder location to a hotter location. Third aw

The entropy of all systems and of all states ofa system is smallest at absolute ero 3


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Thermodynamic "ystems Thermodynamic "ystems

5


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Thermodynamic 'rocesses Thermodynamic 'rocesses Isobaric process : the pressure is constant.

Isochoric process : the volume is constant.

Isothermal process :the temperature is constant.

Adiabatic process : no heat enters or leaves the

system; i.e. Q = 0.

Isentropic process : the entropy is constant. It is also

known as reversible adiabatic process.

Isenthalpic rocess: occurs at a constant !nthalpy

"


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The deal as aw The deal as aw Ideal gas law ! '* + mT or 'v + T,

where m is the no. of kmoles, v is the volume per kmole, T is the absolutetemperature in , and the gas constant + ./01 2 033 45(.kmol).

%or a constant 6uantity of gas, '1*15T1 + '2*25T2.

Avogadro's law ! %or a given mass of an ideal gas, the volume andamount (moles n) of the gas are directly proportional if the temperature and pressure are constant. * is proportional to moles n

v/n=k

##

##

T increasingT increasing

$$ $$

V increasingV increasing

P increasingP increasing

http://en.wikipedia.org/wiki/Ideal_gashttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Ideal_gas


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The energy balance for a The energy balance for a

steady-7ow device (nole,steady-7ow device (nole,

compressor, turbine and pump)compressor, turbine and pump)

with one inlet and one e2it is!with one inlet and one e2it is!


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%luid 8oving 96uipment%luid 8oving 96uipment

%luids are moved throu&h 'low systems usin& compressors,

pumps, 'ans and blowers. (uch devices increase the mechanical

ener&y o' the 'luid. $he additional ener&y can be used to increase

) #elocity *'low rate+) ressure) !levation


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:;":;"

COMPONENT Intake Air Filters : Preven d!" and a#$"p%eri& i#p!riie" 'r$# enering

&$#pre""$r. D!" &a!"e" "i&ing vave"* "&$red &yinder"* e+&e""ive ,eare&.

Compressor : 'ressuries the air

Inter-stage Coolers : Red!&e %e e#pera!re $' %e air (ga") -e'$re iener" %e ne+ "age $ red!&e %e ,$r $' &$#pre""i$n and in&rea"ee''i&ien&y. T%ey &an -e ,aer$r air&$$ed.

After Coolers : Red!&e %e e#pera!re $' %e di"&%arge air* and %ere-yred!&e %e #$i"!re &arrying &apa&iy $' air.

Air-drers : Air dryer" are !"ed $ re#$ve #$i"!re* a" air '$r in"r!#enand pne!#ai& e/!ip#en need" $ -e reaivey 'ree $' any #$i"!re. T%e

#$i"!re i" re#$ved -y "!ing ad"$r-en" $r re'rigeran dryer"* $r "ae $'%e ar %eae"" dryer".

Moist!re Traps : Air rap" are !"ed '$r re#$va $' #$i"!re in %e&$#pre""ed air di"ri-!i$n ine". T%ey re"e#-e "ea# rap" ,%erein %eair i" rapped and #$i"!re i" re#$ved.

"ecei#ers : Depending $n %e "y"e# re/!ire#en"* $ne $r #$re airre&eiver" are generay pr$vided $ red!&e $!p! p!"ai$n" and pre""!revariai$n".


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:


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Types of compressor

Type of

compressor

Positive

displacementDynamic

Reciprocating Rotary Centrifugal !ial


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:ompressor:ompressor selectionselection


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:apacity of compressor:apacity of compressor

:apacity of :ompressor basicallyindicated by following twoparameter

0.'ressure?.%;@


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#hat is &'("#hat is &'(" )apacity of a)apacity of a

)ompressor*)ompressor* The %;@ is the volume of air drawn

into a compressor from theatmosphere. ;fter compression and

cooling the air is returned to theoriginal temperature but it is at highpressure

"uppose atmospheric condition are

'a Ta and *a(the %;@) and thecompressed condition are p , * and T


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"ome deAnations"ome deAnations

Bore + :ylinder diameter. "troke + @istance through which the piston moves. The two e2treme positions of the piston are known as

head-end and crank-end dead centers. :learance *olume (:l) ! *olume occupied by the 7uid

when the piston is at head-end dead centre. 'iston @isplacement ('@) ! *olume, a piston sweeps

through. :ompression atio (rv) ! atio of cylinder volume with

the piston at crank-end dead centre to the cylinder

volume with the piston at head-end dead centre. 8echanical 9Cciency ! which gives an

indication of the

losses occurring between the piston and driving shaft.


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)ompressor )ompressor +ciency+ciency

(e-nitions(e-nitions

Isothermal Efficiency

Isothermal Efficiency =

Actual measured input power

IsothermalPower

Isothermal power(kW) = P1 x Q1 x loer!"#$%

P1 = A&solute intake pressure k! cm'

Q1 = ree air deliered m"!hr$r = Pressure ratio P'!P1


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)ompressor )ompressor +ciency+ciency

(e-nitions(e-nitions

Volumetric Efficiency

"(ree air deli)ered m !min

*olumetric efficiency =+ompressor displacement

+ompressor ,isplacement = Π x ,' x - x . x χ x n

/

, = +ylinder &ore0 metre

- = +ylinder stroke0 metre

. = +ompressor speed rpmχ = 1 for sinle actin and

' for dou&le actin cylinders

n = o$ of cylinders


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eciprocatingeciprocating

:ompressors:ompressors Types

0. "ingle acting

The working 7uid compressed at

only one side of the piston

?. @ouble acting

The working 7uid compressed

alternately on both sides of thepiston.


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rame !"2# $ 1%&"Prame !"2# $ 1%&"P0%rame

;ssly.

?nner Dead

;ssly. (')/:ylinder

;ssly. (')

1


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rame Cross Sl(de Crank s)a*+ andrame Cross Sl(de Crank s)a*+ and

Conne,+(ng rod assem-l.Conne,+(ng rod assem-l. 0. Breather

??.:rosshead

?/. :rossDead Hut

/E.:onnecting od

13.Big 9ndBearing

/F.:onnecting rod Bolt

?,?I.

"tud,Hut

+) +) ; t l t l; t l t l


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rea+)er:rea+)er: ; vent or valve to release; vent or valve to release

pressurepressure

or to allow air to move freely aroundor to allow air to move freely around

something.something.Cross)ead! s a mechanism used in large

and reciprocating compressors to eliminate

sideways pressure on the piston.

Conne,+(ng Rod: connects the piston to the crank or crankshaft. Together with the

crank, they form a simple mechanism that

converts reciprocating motion into rotatingmotion.


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:rank :ase:rank :ase1?. Belt wheel

0/.


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O(l Seal R(ngO(l Seal R(ng !t prevent the oil the!t prevent the oil the

oil to 7ow furtheroil to 7ow further

0aske+! is a mechanical seal which Alls the space between

two or more mating surfaces, generally to prevent

leakage from or into the Joined obJects while under

compression.

C(r,l(p! t is a type of fastener or retaining ring

consisting of a semi7e2ible metal ring with open ends

which can be snapped into place, into a machined groove on a

dowel pin or other part to permit rotation but to

prevent lateral movement. There are two basic types! nternal and e2ternal, referring to whether they

are Atted into a bore or over a shaft.


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Cross !ead P(n : t connects the piston tothe connecting rod and provides abearing for the connecting rod to pivot

upon as the piston moves.

#)rs+ was)er: Thrust washers are long-wearing 7at bearings in the shape of awasher that transmit and resolve a2ial

forces in rotating mechanisms to keepcomponents aligned along a shaft.

Crank P(n/0dgeon P(n: :onnects the

piston to the connecting rod and provides abearing for the connecting rod to pivotupon as the piston moves


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'iston 'arts'iston 'arts

0.'iston;ssembly

?.idering

/.'istoning

1."leeveforpiston


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'iston'iston ing! 'iston rings,ing! 'iston rings,mounted on the pistons ofmounted on the pistons of

lubricated or non-lube (oil free)lubricated or non-lube (oil free)

compressors, are designed tocompressors, are designed to

ensure that the gas isensure that the gas iscompressed and to provide acompressed and to provide a

seal between the piston and theseal between the piston and the

cylinder.cylinder.

ider ing!The functionof rider rings, usedmainly in oil free ormini-lube compressors,

is to support or guidethe piston and rodassembly and preventcontact between thepiston and the cylinder

(risk of seiure).


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"e6uence of operation"e6uence of operation


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deal indicator diagramdeal indicator diagram


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The total work interaction The total work interaction

per cycle !per cycle !


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C)(,ago Pnema+(,: or over a ,en+r.C)(,ago Pnema+(,: or over a ,en+r.

C)(,ago Pnema+(, )as represen+edC)(,ago Pnema+(, )as represen+ed

+og) +ools des(gned +o make +og) o-s+og) +ools des(gned +o make +og) o-s

eas(ereas(er=ay back in 1445 4ohn =. @untley realied that constructionworkers in particular had a need for many tools that werenKtyet available. De founded :hicago 'neumatic Tool :ompanyand set out on a lifelong mission to provide all types ofindustries and companies the tools necessary for theirsuccess.


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"#$% seals an a&reement to manu'acture the &en' diesel engine ,

used in various racin& cars in !urope at the time.

"#()s hica&o neumatic construction and minin& e-uipment is used in

the buildin& o' the

incoln $unnel, /ew ork

$riborou&h 1rid&e, /ew ork

hica&o subway system

1oulder 2am, ri4ona

rand oulee 2am, 6ashin&ton!i&ht dams comprisin& the $ennessee #alley uthority 'lood control and

power &eneration pro7ect

olden ate suspension brid&e, (an %rancisco

"#*)s In response to war e''ort demands, develops the +hot

dimpling machine,- a device that heats rivets to 8,000 de&rees

%ahrenheit"#.)s hica&o neumatic customi4es tools 'or the production o' new

aircra't desi&ns: the &oeing /(/ and /*/,

"#0/ tlas Copco ac1uires Chicago Pneumatic Tool Company


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:hicago 'neumatic:hicago 'neumatic

:ompetition:ompetition9lgi 96uipmentngersoll rand

evathi :p


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@eAnition@eAnition

;n apparatus or machine for raising, driving, e2hausting 7uid, by means of a piston, plunger, orset of rotating vanes


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rinciple o' operation

entri'u&al 'orce*throwin&+

ositive displacement

*physically pushin&+


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Type of PumpsType of Pumps

Classified by operating principlePump Classification

,ynamicPositie

,isplacement

+entrifual .pecial effect 2otary 2eciprocatin

Internal

ear

External

ear -o&e

.lide

ane

3thers (e$$Impulse0 4uoyancy)

Pumps

,ynamicPositie

,isplacement

+entrifual .pecial effect 2otary 2eciprocatin

Internal

ear

External

ear -o&e

.lide

ane

3thers (e$$Impulse0 4uoyancy)

Pumps


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:entrifugal 'umps:entrifugal 'umps9ost common type o' pumpin& machinery. $here are many types, si4es, and

desi&ns 'rom various manu'acturers who also publish operatin& characteristics o'each pump in the 'orm o' per'ormance *pump+ curves. $he device pictured on the

cover pa&e is a centri'u&al pump.

ump curves describe head delivered, pump e''iciency, and net positive suction

head */(+ 'or a properly operatin& speci'ic model pump.

entri'u&al pumps are &enerally used where hi&h 'low rates and moderate head

increases are re-uired.

Terms to be familiarTerms to be familiar


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Terms to be familiar Terms to be familiar

withwith

mpeller-

transmit

energy topressure

*olute- water

passes andpressure is

increased


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#)(s ma,)(ne ,ons(s+s o* an

IMPELLER ro+a+(ng w(+)(n a ,ase 8d(9ser

;(


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=orking principles=orking principles

centrifugal pumpscentrifugal pumps


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!ead (s a +erm *or e>press(ng *ee+ o* wa+er,olmn

!ead ,an also -e ,onver+ed +o pressre

LDeadLLDeadL

"))

feet*(2( P3I

"eser#oirof Fl!id

Press!re

$a!ge


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DeadDead

Dead and pressure areinterchangeable terms providedthat they are e2pressed in their

correct units. The conversion of all pressure

terms into units of e6uivalent

head simpliAes most pumpcalculations.

: i


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:onversion %actors Between:onversion %actors Between

Dead and 'ressureDead and 'ressure!ead 8*ee+ o* l(

231 / Sp 0r

Pressre (n PSI = !ead 8(n *ee+ > Sp0r / 231

PSI (s Ponds per S


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Diameter of

the Impeller

Thickness

of the impeller

:entrifugal mpellers:entrifugal mpellers

Thicker the mpeller- 8ore =ater

arger the @;89T9 - 8ore 'ressure

ncrease the "peed - 8ore =ater and

'ressure

Impeller

%anes

+4ye of theImpeller-

5ater

4ntrance

Two-"tage :entrifugalTwo-"tage :entrifugal


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Two "tage :entrifugal Two "tage :entrifugal'umps'umps

Two mpellerswithin a singlehousing

◦ ;llow deliveryin*olume(parallel) or 'ressure

(series)


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$hrust balance in a multista&e pump


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'ositive @isplacement'ositive @isplacement

'umps'umps$o move 'luids positive displacement pumps admit a 'i


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Reciprocating Pumps

) Piston typeVertical6 Hori'ontal 6 double acting

) Plunger type

) Diaphragm pump


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2iaphra&m pumps


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2iaphra&m pumps


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2iaphra&m eciprocatin& pumps


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p & p & p p

1asic principle is similar to a reciprocatin& plun&er pump>lun&er pressuri4es the hydraulic oil which when pressuri4ed pushes the

diaphra&m and dischar&e starts.

(troke len&th can be ad7usted and hence the dosin& 'low rate.

/o direct contact o' plun&er with the solution.

2irect contact is only with diaphra&m * neoprene, $e'lon etc+

7igure "8 The air valve directs

i d i t th b k id f


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2 i a

p h r a & m =

e c i p r o c a t i n & p u m p s

pressuri'ed air to the back side of

diaphragm 992 The compressed air is

applied directly to the li1uid column

separated by elastomeric diaphragms2

The compressed air moves thediaphragm a:ay from the center block

of the pump2 The opposite diaphragm is

pulled in by the shaft connected to the

pressuri'ed diaphragm2 Diaphragm 9&9

is no: on its air e!haust stroke; airbehind the diaphragm has been forced

out to atmosphere through the e!haust

port of the pump2 The movement of

diaphragm 9&9 to:ard the center block

of the pump creates a vacuum :ithin the

chamber 9&92 tmospheric pressure

forces fluid into the inlet manifold

forcing the inlet ball off its seat2


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2 i a

p h r a & m =

e c i p r o c a t i n & p u m p s

diaphragm, diaphragm99, reaches

the limit of its discharge stroke, the

air valve redirects pressuri'ed air to

the back side of diaphragm 9&92 The

pressuri'ed air forces diaphragm 9&9a:ay from the center block :hile

pulling diaphragm 99 to the center

block2 Diaphragm 9&9 forces the inlet

valve ball onto its seat due to the

hydraulic forces developed2 Thesesame hydraulic forces lift the

discharge valve ball, forcing fluid

flo: to flo: through the pump

discharge2 The movement of

diaphragm 99 to the center block of

the pump creates a vacuum :ithin

li1uid chamber 992 tmospheric

pressure forces fluid into the inlet

manifold of the pump2 The inlet valve

ball is forced off its seat allo:ing the

fluid being transferred to fill the

2iaphra&m eciprocatin& pumps


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7igure (8 =pon completion of the

stroke, the air valve again redirectsair to the back side of diaphragm

99, and starts diaphragm 9&9 on

its air e!haust stroke2 s the pump

reaches its original starting point,

each diaphragm has gone through

one air e!haust or one fluiddischarge stroke2 This constitutes

one complete pumping cycle2 The

pump may take several cycles to

become completely primed

depending on the conditions of theapplication2


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>ear and scre:

pumps

)i&h pressure and viscous 'luids)?sed in (amd 'or lube and seal oil

pumps air booster o' ammonia, 80@

A


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>ear pumps

)i&h pressure and viscous'luids

! seal oil pumps


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3ee the solution is pushed out of

the pump physically


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Bnly one &ear is used * !

basic of thermo & reciprocating compressor

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