Gas-Compressor Station

a station for raising the pressure of natural gas during its extraction, transport, and storage. Types of gas-compressor stations include head (pressure) and line stations for gas mains, stations for underground gas storage facilities, and stations for pumping gas back into a gas-bearing layer. The main technical performance factors of gas-compressor stations are capacity, power, gas compression ratio, and maximum operating pressure.

Head compressor stations on gas mains raise the pressure of the gas flowing from the gas field, starting from the moment when the pressure in the gas-bearing layer falls below the level that provides the rated operating pressure at the entrance to the gas pipeline. The power and compression ratio of the head compressor station build up gradually as the pressure in the gas-bearing layer drops, throughout the entire period of continuous removal of gas from the deposit. During a period of decreasing extraction, gas is removed from a deposit in an amount determined by the power of the head station, which may reach 100 megawatts (MW; 100,000 kW) and more. A station’s compression ratio (the ratio between inlet and outlet pressure) increases from 1.2-1.5 to 5-10 toward the end of the operation.

Line compressor stations on gas mains compensate for the reduction of pressure in a pipeline and maintain it at the rated level. The compression ratio and power outputs of line compressor stations depend on the capacity and technical and economic indexes of the compressor installations and the overall station equipment. The operating pressure and the distance between line compressor stations (75-150 km) depend on the pipeline parameters and are determined by technical and economic considerations of the gas main as a whole. The range of operating characteristics for line gas-compressor stations is as follows: compression ratio, 1.25-1.7; operating pressure, 5.5-8 meganewtons per sq m (MN/m²), or 55-80 kilograms-force per sq cm (kgf/cm²); power output, 3-75 MW; daily capacity, 5-100 million cu m. The discovery of large deposits of natural gas and the high efficiency of large-capacity gas pipeline mains are creating a tendency toward further increases in the power of line compressor stations—up to 150-200 MW, with a daily capacity of 300 million cu m.

Gas-compressor stations for underground gas storage facilities provide for the pumping of gas for transportation during periods of excess gas pipeline capacity. In the period when gas is removed from the underground storage facilities, gas-compressor stations can be used for transmitting gas to consumers. The pressure range within which gas-compressor stations for underground storage facilities operate is 1.5-15 MN/m² (15-150 kgf/cm²) during the pumping of gas. The lower level depends on the pressure of the gas being fed from the gas pipeline, and the higher level depends on the limiting pressure of the gas in the storage reservoir. The power output of such compressor stations may be as high as 50 MW.

Gas-compressor stations for pumping gas back into gas-bearing layers are part of the complex for the processing of natural gas during the exploitation of gas-condensate deposits when it is necessary in the course of production to maintain the pressure in the gas formation in order to prevent the fallout of condensate associated with the phenomenon of reverse condensation. The intake pressure and power of a compressor station for pumping gas back into a gas-bearing layer are determined by the technical and economic factors of the conditions under which the deposit is being exploited. The intake pressure is usually 14-15 MN/m², and the outlet pressure reaches 40-50 MN/m² (400-500 kgf/cm²).

The technological equipment of a gas-compressor station consists primarily of compressor installations—centrifugal blowers driven by a gas-turbine or electric motors, and compressors driven by gas engines. The capacity of compressor installations may reach 15 MW. The use of a centrifugal blower driven by a gas turbine installation rated at 25 MW or more is planned for high-capacity line gas-compressor stations. The production system of a gas-compressor station includes a compressor shop; apparatus for the purification, drying, and cooling of the gas; a power plant for its own needs (a step-down substation for electric driven gas compressor stations); a communications center; and service and repair facilities. There is also a control room. The compressor shop units are controlled from local or centralized control panels, depending on the degree of automation. Fully automated gas-compressor stations are operated by remote control from central control rooms.