Page 22 - Petroleum Production Engineering, A Computer-Assisted Approach

Guo, Boyun / Computer Assited Petroleum Production Engg 0750682701_chap01 Final Proof page 10 4.1.2007 6:12pm Compositor Name: SJoearun

1/10 PETROLEUM PRODUCTION ENGINEERING FUNDAMENTALS
Discharge Discharge

P 2 P 2

Piston
Piston Rod d L

d r

L s

P 1 P 1
Suction Suction
Figure 1.14 Double-action piston pump.

piston stroke and the double-action piston stroke. The Asshown in Fig. 1.15, reciprocating compressors have more
double-action stroke is used for duplex (two pistons) moving parts and, therefore, lower mechanical efficiencies
pumps. The single-action stroke is used for pumps with than rotary compressors. Each cylinder assembly of a recip-
three pistons or greater (e.g., triplex pump). Figure 1.14 rocating compressor consists of a piston, cylinder, cylinder
shows how a duplex pump works. More information heads, suction and discharge valves, and other parts neces-
about pumps is presented in Chapter 11. sary to convert rotary motion to reciprocation motion.
A reciprocating compressor is designed for a certain range
of compression ratios through the selection of proper piston
displacement and clearance volume within the cylinder.
1.6 Gas Compressor This clearance volume can be either fixed or variable,
Compressors are used for providing gas pressure required depending on the extent of the operation range and the
to transport gas with pipelines and to lift oil in gas-lift percent of load variation desired. A typical reciprocating
operations. The compressors used in today’s natural gas compressor can deliver a volumetric gas flow rate up to
production industry fall into two distinct types: reciprocat- 30,000 cubic feet per minute (cfm) at a discharge pressure
ing and rotary compressors. Reciprocating compressors are up to 10,000 psig.
most commonly used in the natural gas industry. They are Rotary compressors are divided into two classes: the
built for practically all pressures and volumetric capacities. centrifugal compressor and the rotary blower. A centrifu-

Piston Cylinder
Suction Head
Valve
Piston
Rod

Crosshead

Connecting Rod

Wrist
Pin
Crankshaft Cylinder

Discharge
Valve
Figure 1.15 Elements of a typical reciprocating compressor. (Courtesy Petroleum Extension Services.)