When selecting a suitable compressor type for wellhead gas, multiple factors need to be considered, including gas properties, flow rate, pressure requirements, usage environment, and economic costs. The following are several common types of compressors and their suitability evaluation as Wellhead Gas Compressors:
Piston compressor
Working principle: The rotational motion of the driving machine is converted into the reciprocating motion of the piston through the crank connecting rod mechanism. By relying on the reciprocating motion of the piston in the cylinder and the automatic opening and closing of the intake and exhaust valves, the gas periodically enters the working chamber of the cylinder for compression and discharge.
Applicable scenarios: Piston compressors are suitable for low flow, high pressure applications, and pressure levels belong to medium pressure, high pressure, and ultra-high pressure levels. Its displacement range is wide, and it is less affected by changes in exhaust pressure. When the medium changes heavily, the changes in its volumetric displacement and exhaust pressure are also relatively small.
Advantages and disadvantages:
Advantages: Low price, easy to use, long lifespan, wide pressure range, and minimal impact of gas volume regulation on pressure.
Disadvantages: Complex structure, large volume, multiple vulnerable parts, heavy maintenance workload, and relatively high maintenance costs. During operation, there is significant vibration and noise, and the equipment installation foundation requires high standards.
Screw compressor
Working principle: By meshing two rotors with helical gears, gas is compressed and discharged.
Applicable scenarios: Screw compressors are suitable for medium flow and pressure applications, with the characteristic of forced gas transmission. The displacement is almost not affected by the exhaust pressure, and the operation is smooth, the vibration is small, the exhaust is stable, and it can maintain high efficiency in a wide range.
Advantages and disadvantages:
Advantages: Large displacement, low vibration, small size, smooth operation, few vulnerable parts, long service life, stable gas supply, generally does not require a gas storage tank.
Disadvantage: The noise during operation is relatively loud, and soundproofing measures need to be taken. After long-term operation, the clearance between the screws will increase, and regular repair or replacement costs are relatively high.
Centrifugal compressor
Working principle: The gas is accelerated by one or more rotating impellers (usually on the side), and the main airflow is radial, using centrifugal force to compress the gas from the inlet to the outlet.
Applicable scenarios: Centrifugal compressors are suitable for high flow and low pressure applications, with high flow and power, which is conducive to energy conservation.
Advantages and disadvantages:
Advantages: Light weight, compact structure, reliable operation, long service life, few vulnerable parts, easy operation and maintenance, easy to achieve automation and large-scale production.
Disadvantages: The operation is relatively complex, the noise is high, the maintenance cost is high, and it is not suitable for situations where the gas volume is too small and the pressure ratio is too high.
Comprehensive evaluation
Gas properties: If the wellhead gas contains a large amount of liquid or solid impurities, a screw compressor may be more suitable because there is a gap between the rotor teeth, which can withstand liquid impact and compress gases containing liquid or dust.
Flow and pressure requirements: Select the appropriate compressor type based on the flow and pressure requirements of the wellhead gas. Piston compressors are suitable for high-pressure, low flow scenarios; Screw compressors are suitable for medium flow and pressure scenarios; Centrifugal compressors are suitable for high flow and low-pressure scenarios.
Economic cost: Consider the purchase cost, operating cost, and maintenance cost of the compressor. Screw compressors and centrifugal compressors usually have high purchase costs, but they operate stably and have relatively low maintenance costs; Piston compressors have lower purchase costs, but maintenance costs may be higher.
In summary, which type of compressor is more suitable as a wellhead gas compressor depends on specific wellhead conditions, gas properties, flow and pressure requirements, as well as economic costs and other factors. In practical applications, a comprehensive evaluation should be conducted based on the specific situation to select the most suitable compressor type.
