1. PRODUCTION TRAINING PACKAGE 11.1
RECIPROCATING COMPRESSOR
THIS TRAINING PACKAGE IS DEVIDED INTO TWO PARTS
PTP 11.1 : PRINCIPLES & COMPONENTS
PTP 11.2 : OPERATION & ACCESSORIES

2. PRODUCTION TRAINING PACKAGE 11.1
RECIPROCATING COMPRESSOR
PTP 11.1 : PRINCIPLES & COMPONENTS

3. Reciprocating Compressor Principles
Why Compressors are used in PDO Operations?
- To increase the Natural gas pressure
Consequently
To utilise the Gas in the process
To Export or to Sale the Gas
To inject or to lift to Enhance the oil production
DIFFERENT TYPES OF COMPRESSORS ARE USED IN PDO

4. Reciprocating Compressor Principles
Types of Compressors:

5. Reciprocating Compressor Principles

6. With the help of Cylinder and Piston
Reciprocating Compressor Principles
Principles:
Positive Displacement compressor
Operates by volumetric displacement
Most operates with reciprocating- back and forth or up and down - motion
Some with rotary motion
PRESSURE INCREASES WHEN THE GAS IS FORCED TO OCCUPY A
SMALLER VOLUME.
Greater the reduction in volume -
Greater the increase in Pressure
With the help of Cylinder and Piston
These are High Head and Low Throughput Machines

7. Reciprocating Compressor Principles
Depends on its Function it is categorised:
1. Single Acting Reciprocating Compressor:
DISCHARGE
CYLINDER
PISTON
SUCTION
One revolution: One forward stroke & one back ward stroke or
One suction stroke & one discharge stroke.
One discharge per revolution
Compression taking place on one side of the piston

8. Reciprocating Compressor Principles
2. Double Acting Reciprocating Compressor:
One revolution:
Two suction stroke &
Two discharge stroke
Suction stroke and Discharge
strokes are simultaneously
Two discharge/Two suction
per revolution-
Crankcase end and head-end
Compression taking place on both side of the piston

9. Reciprocating Compressor Components
External Components:
FLYWHEEL
CROSSHEAD
COMPARTMENT
FRAME/CRANKCASE
DRIVER
PULSATION
DAMPENER
SUCTION VALVE
SEAL COMPARTMENT
DISCHARGE VALVE
CYLINDER

10. Reciprocating Compressor Components
Internal Components:

11. Reciprocating Compressor
External Components:
1. Driver:
May vary with the size of the machine
Availability of energy source.
Commonly Electric motor - run at constant speed, require capacity control
Another - Gas Engine - Speed controller available, require more maintenance
than Electric motor.
Gas/Steam driven turbines are the last alternative.
2. Fly Wheel:
To avoid any surge of power due to reciprocating action
3. Frame/Crankcase:
To provide high strength at a reasonable weight.
In the side walls - Saddles are machined for the crankshaft main bearing shells
The frame serves as a reservoir for lubricating oil
On non-drive end, the main lub oil pump is fitted.

12. Reciprocating Compressor
External Components: conti-
4. Cross Head Compartment:
Consist of the shoe and cross-head guide
Access through side door to carry out alignment and clearance checks.
5. Seal Compartment:
consists of the gas and oil scraper seal.
Access through side door to carry out leakage checks.
6. Cylinder:
Are cover with water jackets for cooling purpose.
Piston travels To and Fro with a liner.
7. Pulsation Dampener:
To absorb the intermittent pulsation due to reciprocating action.
Surge the gas pulses.
Each on suction and discharge

13. Reciprocating Compressor
External Components:conti-
8. Suction / Discharge valves:
Acts as Non return valves.
Let the gas enter / discharge at specific pressure.
Suction valves fitted on top and discharge valves are fitted on bottom
of the cylinder.
Consists of valve seat, valve guard, valve plates etc.

14. Reciprocating Compressor
External Components:conti-
Across Section of a Discharge Valve
A worn or damage valve allows gas to back leak.
Sudden chilling on hot valve can break valve plate.
Gas should be free of liquid.

15. Reciprocating Compressor
External Components:conti-
Valve internals:
Valves must be properly installed
Means:
- Suction valve: you can depress the
plate in toward the centre of the
cylinder.
- Discharge valve: you can depress the
away from the cylinder.
When a valve leaks:
-The gas returning through the valve
is hotter and valve become hotter.
- Detected by measuring skin
temperature of valve cover.
- To be checked by operator in morning
hours

16. Reciprocating Compressor
Internal Components:
1. Crank Shaft:
To convert rotary motion from driver to reciprocating motion to the piston through connecting rods and cross-head.
Oil holes are drilled for the lubricating purpose.
Non driven end gear wheel drives the main lube oil pump.

17. Reciprocating Compressor
2. Connecting Rod:
Connect the crank shaft and the cross head.
Both ends are equipped with heavy duty sleeve bearing.
Big end bearing and Small end bearing.

18. Reciprocating Compressor
3. Cross Head:
Connects the connecting rod and piston rod.
Made of cast steel and have white metal surfaces.
Lubricated through main oil system.
Moves on the cross head guides.
Shims are installed at the cross-head shoes for vertical alignment.

19. Reciprocating Compressor
4. Cross Head Guide:
Housing is provided with inspection holes and covers.
Easy access through this doors for maintenance/inspection.
Where no gas leakage is allowed, two distance pieces are built between the
cylinder and cross-head guide.
5. Piston Rod:
Made of high quality steel alloy.
Are heat treated to provide a harder and stronger finish.
Heavy chrome plated to protect against H2S.

20. Reciprocating Compressor
6. Stuffing Box:
Used for separation of the compressor cylinders to the atmosphere as well as
between the cross-head section and distance piece.
Each section consist of two PTEF rings and a back-up ring
Numbers of sections depends on differential pressure between compressor
discharge pressure and the atmosphere.
Stuffing boxes can be lubricated or non-lubricated, water cooled or
non-water cooled according to deferent design.
7. Packing:
Prevents compressed gas leak along
the piston rod.
Mostly used metallic rings.
Rings are arranged in pairs in each
cup and are made in segments.
The segments held against the piston
rod by garter spring.
Could be of fibre, plastic or metal.
Carbon or Teflon - used when
packing must be free of lubricant

21. Reciprocating Compressor
Gas leakage of Packing:
- Have sets of rings scraper or wiper near cross-head
Single-acting wiper either prevent oil leak from crank
case to cylinder or to either side.
Double-acting wipers removes both cylinder oil and
crankcase oil from the rod. Wipers scrapes the oil into
the distance piece and get drained.
A rising temp. at the vents indicates excessive leakage.
The gland packing has connections for CW, LO and
a vent.

22. Reciprocating Compressor
8. Piston:
Solid and Hollow Piston
Hollow
Made of Cast iron - usually made solid
Low-speed compressor(up to 330 rpm.
High-speed compressor( rpm)
More than 7” in dia. Usually made hollow..
Manufacturers specify the amount of clearance required.
To assemble cold piston, make the piston end clearance greater at the head-end
of the cylinder.( 1/3 on the crank case end and 2/3 at the head-end)

23. Reciprocating Compressor
9. Piston ring:
Provide a seal to minimise a leak.
Also carry heat from the cylinder.
Compressor’s cooling system carries most of the heat.
Rings are made of material that wears more rapidly than cylinder or liner.
Made of bronze, cast iron, bakelite, teflon etc.
Material cause low friction.
Ring grooves should be very accurate.
Minimum allowable clearance 0.3 mm9between piston and cylinder walls.

24. Reciprocating Compressor
10. Cylinder assembly:
Cylinder bore and Liner - to reduce reconditioning cost.
Worn liner needs to be replaced.
Due to the weight of the piston, wear is usually at the bottom of the cylinder.
Misalign liner:
Oil holes in the liner always aligned with the lubricator inlet.
Misalign liner can cause plug or close the inlet.

25. Reciprocating Compressor
11. Bearings:
Bearing shell should be inspected for cracks, chips, scratches and wiping.
Typical cause for high temperature-
- blockage in the oil supply.
- Inadequate oil flow.
- tight bearing clearance.
- Crankshaft misalignment
12. Oil wiper Rings:
To prevent crankcase oil from passing into the cylinder.
To prevent condensate from entering the crankcase.
Normally two or three wiper rings are used in an oil seal.
Two types
- Designed to turn back a large volume of oil along the rod.
- Oil wiped from the rod drains into an annular and back into the crankcase.