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COMPRESSOR BASICS

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					COMPRESSOR BASICS
    TYPES OF COMPRESSORS
   POSITIVE DISPLACEMENT
    COMPRESSOR

   CENTRIFUGAL COMPRESSOR
    POSITIVE DISPLACEMENT
         COMPRESSOR
 PD COMPRSSOR WORK BY TRAPPING
  A CERTAIN AMOUNT OF GAS AND
  FORCING IT INTO A SMALLER VOLUME
 A COMMON TYPE OF PD COMPR. IS
  RECIPROCATING COMPRESSOR.
 TWO OF THE MAIN PARTS OF
  RECIPROCATING COMP. ARE
  CYLINDER AND A PISTON
 GAS ENTERS THE CYLINDER AND IS
  TRAPPED INSIDE THE CYLINDER. THE
  GAS IS THEN FORCED INTO A
  SMALLER SPACE BY THE ACTION OF
  THE PISTON.
 FORCING THE GAS IN SMALLER
  SPACE INCREASES THE PRESSURE,
  THE COMPRESSED GAS IS THEN
  DISCHARGED.
    CENTRIFUGAL COMPRESSOR
   IT USES A DEVICE CALLED IMPELLER TO
    SPIN THE GAS AROUND
   THE ACTION OF THE IMPELLER
    ACCELERATE OR INCREASES THE SPEED
    OF THE GAS FLOW. IT GIVES THE GAS
    ENERGY.
   AS THE GAS FLOWS OUT IT SPEED OUT
    AND SLOW DOWN AND ITS ENERGY IS
    CONVERTED INTO PRESSURE
SHARING CHARACTERSTICS
 COMPRSSORS ARE RATED FOR
  DISCHARGE PRESSUR AND FLOW
  RATE
 ALL COMPRESSORS REQUIRE SOME
  FORM OF DRIVE MECHANISM
 ELECTRIC MOTORS ARE COMMONLY
  USED DRIVES.
    COMPRESSOR HAZARD
 MOVING PARTS
 HOT SURFACE
 NOICY
 LEAKS FROM THE GAS SYSTEM
 FLAMMABLE EXPLOSIVE GASES
  (SPARK PRODUCING EQUIPMENT
  SHOULD NEVER BE USED)
           ACCESSORIES
   LUBRICATION

   COOLING

   FILTERING
    LUBRICATION SYSTEM
 MAIN FUNCTION IS TO REDUCE
  FRICTION BETWEEN THE MOVING
  PARTS
 LUBRICATION HELPS COOLING THE
  COMPRESSOR MOVING PARTS AND
  HELP PREVENT THE LEAKING GAS
  OUT OF COMPRESSOR.
            DESCRIPTION
   OIL FROM THE COMPRESSOR FLOWS INTO
    THE OIL PUMP.THE OIL IS THEN PUMPED
    THROUGH FILTER WHICH REMOVES ANY
    SOLID PARTICLE FROM THE OIL.
   OIL FLOWS THROUGH THE HEAT
    EXCHANGER WHERE IT IS COOLED
   FROM HEAT EXCHANGER MOST OF THE OIL
    FLOWS DIRECTLY TO COMPRESSOR
    LUBRICATION.
 REST OF THE OIL GOES TO OILER.
 OILER SUPPLIES A SMALL AMOUNT OF
  OIL TO THE COMPRESSOR CYLINDER
 THE OIL LUBRICTES THE PISTON
  RINGS AND HELPS SEAL THE SPACE
  BETWEEN THE CYLINDER WALL AND
  THE RING.
              COOLING
   WHEN A GAS IS COMPRESSED HEAT IS
    PRODUCED THIS HEAT CAN CAUSE TWO
    PROBLEM
    1. EXCESS HEAT CAN BREAK DOWN OIL
       CAUSING IT TO BE LOOSE ITS
       LUBRICATING CHARECTORSTIC
    2. GASED EXPAND WHEN THEY ARE
       HEATED SINCE COMPRESSOR IS
       DESINGED TO COMPRESS GASES THE
       EFFECT CREATE ADDITIONAL FORCE
       WHICH COMPRESSOR MUST OVERCOME.
          HEAT REMOVAL
   AIR COOLING AND WATER COOLING
    ARE TWO TECHNIQUES
    1. AN AIR COOLED COMPRESSOR
       EASILY IDENTIFIED BY MEAL FINS
       ON ITS CASING
       THE FINS PROVIDE INCREASED
       SURFACE AREA.
  2. ANOTHER WAY TO REMOVE THE
     EXCESS HEAT IS TO COOL THE GAS
     AFTER THE COMPRESSION IS
     COMPLETE, THE DEVICE THAT
     DOES THIS IS AN AFTERCOOLER OR
     INTERCOOLER
 DEPENDING UPON ITS LOCATION
  THESE EXCHANGERS ARE
  CLASSIFIED AS INTERCOOLER OF
  AFTER COOLER.
    INSTRUMENTATION AND
          CONTROL
 THE PROPER OPERATION OF COMP.
  DEPENDS UPON INSTRUMENTAITON
  AND CONTROL DEVICES
 THESE DEVICES ALLOWS THE
  COMPRESSOR TO BE STARTED AND
  STOPPED.
 THEY PROVIDE INFORMATION ABOUT
  THE COMPRESSOR OPERATING
  CONDITIONS
 THEY MAINTAIN THE VALUES OF
  PROCESS VARIABLES
 THEY KEEP THE COMPRESSOR
  OPERATION STABLE
 THEY CAN SHUT DOWN THE
  COMPRESSOR IF UNSAFE CONDTITON
  OCCURED
 CONTROL PANEL MAY HAVE
  CONTROL TO REGULATE THE SPEED
 CONTROL PANEL ME ALSO CONTAIN
  ALARMS THAT LET THE PERSONNEL
  KNOW WHEN ABNORMAL AND
  POTENTIAL DAMAGING CONDITION
  EXISTS
 PRESSURE CONTROLLER CONTROLS
  THE DISCHARGE PRESSUR AND IF IT
  DEVIATES CONTROLLER
  MANUPULATE THE INLET FLOW
        SURGE CONTROL
   FOR A GIVEN DISCHARGE PRESSURE
    A COMPRESSOR HAS A CERTAIN
    MINIMUM FLOW RATE. BELOW THIS
    FLOW RATE THE COMPRESSOR
    BECOME UNSTABLE. A DECREASE IN
    FLOW BELOW THE MINIMUM FLOW
    CAN CAUSE A SERIES OF
    MOMENTARY REVERSAL OF FLOW
    THROUGH THE COMPRESSOR. THIS
    SITUATIION IS CALLED SURGE
 SURGING RESULTS IN VIOLENT
  FLUCTUATIONS IN DISCHARGE
  PRESSURE.
 WHEN AN ELECTRIC MOTOR IS USED
  AS DRIVER SURGING CAN CAUSE
  EXTREME VARIANTION IN MOTOR
  CURRENT.
 SYMPTOMS OF SURGING ARE LOW
  GAS FLOW, EXCESSIVE VIBRATION
  AND BANGING SOUND INSIDE
  COMPRESSOR
 TO PREVENT THE SURGING THE
  FLOW RATE OF THE GAS THRU THE
  COMPRESSOR MUST BE KEPT ABOVE
  THE MINIMUM STABLE FLOW RATE OR
  SURGE POINT
 WHEN THE DEMAND IS LOW FLOW
  RATE IS MAINTAINED BY
  RECIRCULATING THE PORTION FROM
  DISCHARGE TO BACK TO
  COMPRESSOR.
          START UP
 PREPARING THE COMPRESSOR FOR
  STARTUP
 WARMING UP THE COMPRESSOR
 STARTING THE GAS FLOW THRU
  COMPRESSOR
 COMPRESSORS GAS SUPPLY IS
  AVAILABLE, CONTROLS ARE SET IN
  POSITIONS.
 VALVE LINE UP MEANS ALL THE
  VALVE ARE PROPERLY SET.
 START THE COMPRESSOR
  AUXILARIES AND MAKE SURE THEY
  ARE OPERATING PROPERLY.
 OPERATOR MUST CHECK THE
  COMPRESSOR AND MAKE SURE THAT
  NO ABNORMAL CONDITION EXISTS.
 IF THE COMPRESSOR HANDLES THE
  FLAMMABLE GAS IT MUST BE PURGE
  WITH AN INERT GAS LIKE NITORGEN.
 ONCE PURGED IT CAN BE STARTED
  AND KEPT IN WARMING UP.
 ONCE THE COMPRESSOR AND ITS
  PARTS RUNS FOR A WHILE AT A LOW
  SPEED THE COMPRSSOR CAN BE
  BROUGHT UP TO NORMAL SPEED.
 THIS INVOLVES THE INCREASE OF
  SPEED AT CERTAIN RATE CALLED
  RAMP RATE
 CRITICAL SPEED – FOR CETRUFUGAL
  COMPRSSOR CERTAIN ROTATIONAL
  SPEED CAUSE SEVERE VIBRATION, IT
  IS CALLED CRITICAL SPEED.
 IT IS DUE TO PHYSICAL
  CHARECTORSTIC OF MOVING PARTS
  OF COMPRESSOR.
 WHEN A CRITICAL SPEED IS REACHED
  THE RAMP SPEED IS USUALLY
  INCREADED TO PASS THROUGH THE
  CRITICAL SPEED.
         OPERATION
 ONCE STARTED COMPRESSOR
  SHOULD BE CHECKED ROUTINELY.
 WHILE CHECKING A COMPRSSOR
  OPERATOR MUST KEEP IN MIND THAT
  IT OPERATES AT VERY HIGH SPEED.
 AN IMPORTANT PART OF CHECKING A
  COMPRSSOR IS TO LISTEN TO THE
  ABNORMAL SOUND.
 IT IS IMPORTANT TO CHECK THE
  COMPRESSOR BEARING FOR
  EXCESSIVE VIBRATION AND
  OVERHEATING IT INDICATE
  PROBABLE BEARING FAILURE.
 COMPRESSOR AUXILIARY CHECK IS
  IMPORTANT DURING OPERATION OF
  COMP. LIKE OIL LEVEL IS IN NORMAL
  RANGE,OIL IS CLEAR AND NOT MILKY.
 OIL PRESSURE IS IMPORTANT
  PARAMETER TO CHECK, INIDCATE
  MALFUNCTION OF OIL PUMP OR OIL
  LEAK IN SYSTEM.
   OIL PARAMETER IS CRITICAL
    PARAMETER, HIGHER THAN NORMAL
    OIL PRESSURE INDICATES THE
    CLOGGING OF SOME PART IN OIL
    LUBRICATION SYSTEM.

				
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