Mobile Compressors

8/19/2019 Mobile Compressors

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MobileCompressors

Recognize, name and state the function of each component in acompressed air system.

Use graphical symbols to represent a compressed system.

Dene terminology relating to compressed air supply systems i.e.

a). compressor rating b). free air delivery c). absolute pressure d).

atmospheric pressure e). gauge pressure f). relief pressure

Describe mobile and stationary compressor cooling requirements.

State the need for speed and pressure control, and describe theconstruction and operation of dierent regulating systems.

Describe the construction and operation of!

a). single and multistage rotary compressors

b). single and multistage reciprocating compressors


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Describe the construction and operation of!

a). single and multistage rotary compressorsb). single and multistage reciprocating compressors

Describe rotary and reciprocating compressor lubrication systems.

State the starting, running and stopping procedures for mobilecompressors.

"ist #or$ing practices and servicing requirements of mobilecompressors.

Describe reasons for using and the types and construction of ltersand #ater separators in a mobile compressor air system.

Objectives continues…


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MobileCompressorsIntroduction

%he term &pneuma' comes from the gree$s meaning breath or #ind.(neumatics is the study of air movement %oday pneumatics is mainly understood to mean the application of air asa #or$ing medium in industry, especially the driving and controlling ofmachines.


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Components Air Filter

%o remove dust particles and dirt from the air being suc$edin Air silencer

Dampens out nose First stage compressor * machine, #hich usually suc$s in air and compressessame so that it ultimately occupies a smaller volume. %he

resulting air #ill not only occupy a smaller volume, it #illhave a higher pressure and higher temperature


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Intercooler +or$s li$e a heat echanger and lo#er the density of thecompressed air bet#een stages Second stage compressor * second phase of compression, #hich further increases air-o#rate temperature

Drive motor (rovides drive to the t#ostage compressor system.


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Relief alve

/aintains system pressure, #or$s li$e an unloadervalve !ressure gauges *n instrument that reads pressure contained in

the system After"cooler +or$s li$e a heat echanger and lo#er thedensity of the compressed air after stages Automatic Drain #raps

Drains condensate in air tan$s and at variouspoints in the system


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Moisture separator +or$s together #ith the autodrain valve by containing

moisture and #ater out of thesystem Air receiver 0or storage

Stop valve 0or air receiver protection Safet$ valve

1ac$ up for the stop valve

0or graphical symbols, usenotes on air bra$es


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#erminolog$ Free air deliver$

%his is the actual quantity of air delivered,epressed in l2s 3m42min) at the conditions oftemperature and pressure eisting at the inlet to thecompressor. %his gure is lo#er than the pistondisplacement due to the fact that no compressorcan be 5667 e8cient

Compressor rating%capacit$ (iston displacement is the volume s#ept by the rststage piston or pistons i.e. bore r.p.m

Relief pressure /aimum pressure reached before ehausting air tothe atmosphere #hen the required pressure iseceeded


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Atmosp&eric !ressure

%his is a pressure #hich varies the #orld over and -uctuates#ith #eather conditions. 9ts is also dependent upon altitude Absolute !ressure %his is a pressure measured from a base of absolute zero. +e

breathe air at a pressure of approimately 5:.; pounds persquare inch absolute 3psi). +e don't notice this pressurebecause it is al#ays around us and its called atmosphericpressure.


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Advantages

*ir is available in unlimited quantities

every#here >ompressed air is easily conveyed in pipelines

even over larger distances

>ompressed air can be stored >ompressed air need not be returned. 9t can be

vented to atmosphere after it has performed#or$

>ompressed air is eplosion ? proof. %hus, no

epensive protective equipment againsteplosion is necessary


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>ompressed air is insensitive to temperature -uctuations. %his ensures reliable operation even in etremetemperature conditions.

>ompressed air is clean. %his is especially important in

the food, #ood, tetile and leather industries.

@perating elements for compressed air operation are ofsimple and inepensive construction

>ompressed air is fast. %hus high operational speeds can

be attained

Speeds and forces of the pneumatics elements can beinnitely adAusted.


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Disadvantages >ompressed air is a relatively epensive means of

conveying energy. %he higher energy costs are ,ho#ever, largely compensated by the cheaperelements, simple and more compact equipment

>ompressed air requires good conditioning. Bo dirt or

moisture residues may be contained in it 3#ear ontools and equipment).

9t is not possible to achieve uniform and constantpiston speeds 3*ir is compressible)


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Compressed air is economical only up to a certain force. Owing to

the commonly used working pressure of 700 kPa, the limit is at

about 20 000 to 30 000 ewton, depending on the tra!el and the

speed "if the force which is re#uired e$ceeds this le!el, hydraulics is

applied.

%he e$haust is loud. &s a result of the intensi!e de!elopment work

on materials for silencing purposes, this problem has howe!er now

largely been sol!ed.

%he oil mist mi$ed with the air for lubricating the e#uipment escapes

with the e$haust to atmosphere.


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#$pes of Compressors Reciprocating

ylinder head>onCrod>ran$shaft

"ubricated by the engine"ubrication System


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Rotar$

Rotor

anes@il lubricating pumpDrive coupling

BoteE oil mist is eAected into the air stream for components

lubrication


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Scre' Compressor


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Scre' compressoroperation(


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Root blo'er


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Compressor cooling re)uirements

9ncreased cooling surfaces area

* continuous supply of cooling #ater

/etals #ith ecellent thermal conductivity

=ood ventilation


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>ooling ns on smallercompressors allo# the

heat to be removed byradiation. "argercompressors areequipped #ith anadditional fan toremove heat.

CompressorCooling

+ater circulationcooling or fresh#ater cooling.


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*&$ !ressure control or !ressure regulation+ (ressure control for economical reasons. %o avoid thecompressor from over running Usually the discharge is the control variable

%ypes of control depends on prime mover2 engine distribution net#or$ *utomatic 3speed variation, inlet throttling, unloading onCotype)


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(ressure Regulation

http://var/www/apps/conversion/tmp/scratch_2/Types%20of%20Compressors.docxhttp://var/www/apps/conversion/tmp/scratch_2/Types%20of%20Compressors.docx


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Air ,lters - *aterseparators

!urpose of air ,lters %he lter is intended toetract particles of dirtfrom the air and allo#

condensate to collect bedrained o. %he air lter used mayeither be the dry or #ettype

!urpose of 'aterseparator %o trap any #ater that maycondense in the system


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Compressor lubrication !urpose

%he lubricator is intended to enrich thecompressed air #ith air and oil mist in orderto ensure lubrication of the moving parts inpneumatic devices Starting. running - stopping procedure

Refer to notes


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Startup !rocedure for Motor"Driven

Compressors(

(roceed as follo#sE

@pen all shuto valves bet#een compressor

and receiver.

/a$e sure compressor is unloaded. >onsult

the manufacturerFs instructions for procedure.

%urn on cooling #ater, if provided. %horoughly

vent cylinder Aac$ets and coolers if vents are

provided.

%urn compressor over by hand to see that all

parts are free. Start compressor motor.

+hen up to speed, apply load if machine is

running smoothly.


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Startup !rocedure for Steam"Driven Reciprocating

Compressors.

(roceed as follo#sE

@pen all shuto valves bet#een compressor and receiver.

%urn on cooling #ater services ensuring cylinder Aac$ets and

coolers are thoroughly vented.

/a$e sure compressor is unloaded by opening the separator

drain valve or the compressor cylinder indicator coc$s.

@pen valve chest, ehaust, and steam cylinder drain valves.

@pen the drain valve on the steam admission line above the

throttle valve. +hen all condensation has drained from the

line and the pipe is hot, close the drain valve until it is open

approimately oneCfourth of a turn.

>rac$ opens the throttle valve and allo#s the steam cylinder

to #arm up.


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@pen steam ehaust valve.

Slo#ly open the throttle valve and allo# the

governor to ta$e over control.

>lose the drain valves #hen steam discharge is free

of condensate.

+hen the compressor is up to speed, slo#ly build

up the load.


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Startup !rocedure for /e' or Over&auled

Compressors(

+hen starting a ne# compressor, or one that has been

overhauled, allo# the compressor to run unloaded for 5

or G hours to give the running surfaces a polished nish.

(eriodically chec$ for overheating.

1uild up load gradually over a period of several hours.

*fter a fe# days of operation, shut do#n compressor and

rechec$ all cylinder head, valve cover, cylinder -ange,

shaft cover, and foundation bolts for tightness.GC:

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Mobile Compressors

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