WET GAS COMPRESSOR 1. C1 and C2 C2 are non condensa condensable ble gases. gases. So So with with increa increase se in main column column pressure LPG and other heavier components condenses.So, to separate them from LPG Wet Gas Compressor is reuired. !bsorption occurs at high pressures and low temp..So, to ma"imi#e LPG pressure of gas reuired is more.So, WGC is reuired. 2 $itrogen pressure in lube oil tan% &' (.) %g*cm 2 $itrogen pressure in suppl+ header &' %g*cm2 -. uffer gas suppl+ pressure
&' )./ %g*cm2
(. 0he buffer buffer gas is used for for sealing sealing purpo purpose. se. t preve prevents nts lea%ag lea%age e of h+drocarbon from casing to atmosphere. . $itrogen $itrogen is is used used as separat separation ion gas. gas. t separ separates ates the lube lube oil oil and h+drocarbon. h+drocarbon. t is applied near bearings. ). 0he differ differenti ential al pressur pressure e is the the differen difference ce in press pressure ure betwee betweenn two points. . Lube oil circulati circulation on is is reuire reuired d for for followi following ng purpo purposes. ses. 13 t removes removes heat heat produced produced and %eeps %eeps the the rotating rotating parts parts in cool cool condition. 23 t avoids the friction friction between between the moving and and stationar+ stationar+ parts. -3 t gives gives smooth smooth movement movement to movin movingg parts. parts. 4ue to this lube oil temp. also also increases.So, increases.So, that it is sent bac% bac% to lube oil tan% and then cooled in cooler and then supplied to the bearings. /. Contro Controll oil pressu pressure re &' 1-. 1-. %g*cm2 %g*cm2 t is used in 13 5+dr 5+drau auli licc ampl amplif ifie ierr 23 006
-3 7mergenc+ Governor (3 ladder 3 Steam 0urbine Governor )3 oil relief valve 8 solenoid9it is normall+ closed3 :. !ccumulator contains $itrogen bladder. nitiall+ the oil is accumulated due to control oil pressure. When the control oil pressure decreases then $itrogen creates pressure . so, the control oil from accumulator is supplied. 1;. 0he h+draulic amplifier converts the electrical signals into h+draulic pressure for steam turbine governor. 11. n case of emergenc+ when the lube oil stopped to the compressor at !t that time lube oil inlet line to the rundown tan% or overhead tan% having an orifice through which the lube oil is directl+ supplied to the lube oil suppl+ line and through it to the bearings. 12. f the lube oil pressure is high then it can increase the vibration of the shaft. f it is low then it indicates improper lubrication. 1-. Lube oil inlet to cooler is at about C as it ta%es heat from the bearing of the compressor. Lube oil cooler cools the lube oil up to the temp. below ( C. f the lube oil suppl+ temp. is more then its viscosit+ will decrease. So, it will not create proper film between stationar+ and moving parts which will minimi#e the friction. 1(. 0he 0C69temp. control valve3 is provided at the lube oil cooler b+pass f lube oil temp. after cooler is less than reuired then 0C6 will open !nd b+pass the lube oil. f lube oil temp. after cooler is higher than reuired then 0C6 will close. So, more oil will pass through cooler. 1. f the lube oil temp. is lower than -; C ,for that purpose an electrical 5eater is provided.
1). 0here are two pumps for lube oil circulation. 13 <=P &' main oil pump 9
;./ %g*cm2 11 %g*cm2 1/. 0here are seven93 impellers in WGC. Which are close t+pe impellers. 1:. 0here are two t+pes of bearings in WGC 13 0hrust bearing &' 2 23 ?ournal bearing &' ( 2;.0hrust bearing@' t is used to prevent a"ial motion of the rotating shaft 0here b+ maintaining its a"ial position of the rotor !ssembl+ within the compressor ?ournal bearing &' t is used to support the rotor load in stead+ state and 0o control the rotor position. 21. 0here total ( seals in WGC 2 lab+rinth t+pe and 2 dr+ gas seal. 22. 0he seal is reuired to prevent the lea%age of h+drocarbon in the atmosphere. 2-. Lube oil tests& 13 viscosit+ 23 copper test9 corrosion and acidit+3 -3 moisture (3 wear particle 9value of o"idation3 2(.4ecrease in lube oil pressure Arom compressor base plate 2. t removes an+ moisture, dust, corrosive gases to the atmosphere b+
preventing their contact with oil. 2. n compressor power reuired for adiabatic compression is greater 0han the power reuired for isothermal 9 constant temp.3 compression So, to %eep process isothermal as far as possible inter stage coolers are necessar+. 2). Water and 5+drocarbon doesnBt get separated in inter stage drum due ver+ low retention time. 2. Wash water is inected in 1st stage discharge to dissolve salts such as ammonium choride. 2/. Aor C;1 first stage suction strainer delta P 2;(.2 mm WC Aor C1 second stage suction strainer delta p 1;2.) mm WC 2:. 006 means trip and throttle valve t is having spring action due to control oil pressure. f control oil pressure decreases then spring will loose tension and it will close cut off the steam suppl+ to the governor and the compressor trips, -;.arring gear is provided to run the shaft at (rpm so that to provide unif uniform sagging and e"pansion of the shaft. -1. 0rip speed of WGC is -2 rpm -2. 0his is the speed at which shaft vibration is more and can damage the Shaft. --. n WGC coupling is fle"ible diaphragm t+pe and does not need lubrication. -(. Compressor will trip in following circumstances. 13 low suction flow 23 Liuid level in compressor suction drum high -3 Low lube oil or control oil pressure (3 0emp of 1st and 2nd stage discharge increases. 3 Liuid level in compressor inter stage drum is high
)3 6ibration of shaft. -. Warm up is reuired to avoid thermal shoc% and damage. -). Gland steam condenser is reuired to condense the steam coming out Arom governor bottom. -. 5P steam in turbine temp -:1 C Pressure (- %g*cm2 -/. (2 -:. Governor is a devise that controls the flow of steam to the turbine at a desired value without hunting. (;.
