Compressors Drive systems

The total compressor power input is the net power delivered to the compressor drive shaft by the prime mover system. This is... 

F. Fraschetti, P. L. Ferrara, U. Philippini, Centrifugal compressor arrangement and drive systems in A. V. Slack, G. Russel James (eds.) Ammonia part III, Marcel Dekker Inc, New York 1977, p. 11-45. 

A9.2.7 Pneumatic Driving System. The.incoming air from compressor is cleaned, filtered, and dehumidified before il accumulator tank. A relief valve controls the maximum pressiirei in the tank. A pressure regulator controls. the pressiire of the air prior to its entry into the pneumatic shuttle system through the solenoid-operated valves that govern... 

Gas turbine Seleaion of gas turbines, like any other drive system, is based on economics. The availability of gas in such remote areas as deserts and offshore platforms makes it a prime source of power in these locations. Gas turbines are used in various applications, including gas transmission, gas lift, liquid pumping, gas reinjection, and process compressors. Air is compressed in the gas turbine by the centrifugal compressor and is discharged into a reverse flow annular combuster in which fuel is injected through nozzles. The transition dua directs tfie hot gas into a gas gener-... 

However, this power loss is just the power delivered to the rotor of the compressor. This power comes from an electric motor, which has an efficiency of less than 1, and there are also losses in the connecting shaft and the bearings of the compressor rotor. If we express the combined efficiency of the motor and drive system as r m, then Ihe electrical power used will be greater than the compressor power by a factor of I/rjm, and so there will be a loss of electrical power given by the equation... 

Since compressed air is supplied by a compressor. Great care must be taken to insure certain types of equipment are operating in a safe manner. Safety devices for a compressed air system should be checked frequently. Compressors should be equipped with pressure rehef valves and pressure gauges. The air intakes must be installed and equipped so as to ensure that only clean uncontaminated air enters the compressor. Air filters installed on the compressor intake cilitate this. Before any repair work is done on the pressure system of a eompressor, the pressure is to be bled off and the system locked-out. All compressors must be operated and lubricated in accordance with the manufacturer s recommendations. Signs are to be posted to warn of the automatic starting feature of compressors. The belt drive system is to be totally enclosed to provide protection fiom any contact... 

Nuclear Radiation Effects. Components of a nuclear reactor system that require lubrication include control-rod drives, coolant circulating pumps or compressors, motor-operated valves, and fuel handling devices, and, of course, are exposed to varying amounts of ionising (14). 

The steam balance in the plant shown in Figure 2 enables all pumps and blowers to be turbine-driven by high pressure steam from the boiler. The low pressure exhaust system is used in the reboiler of the recovery system and the condensate returns to the boiler. Although there is generally some excess power capacity in the high pressure steam for driving other equipment, eg, compressors in the carbon dioxide Hquefaction plant, all the steam produced by the boiler is condensed in the recovery system. This provides a weU-balanced plant ia which few external utiUties are required and combustion conditions can be controlled to maintain efficient operation. 

The main power source is a 2,200 kW rated motor, which drives two high-speed pinions through integral gears. The first stage of the compressor operates at 17,900 rpm, while the second and third stages operate at 21,800 rpm. The unit is controlled by a local control system, but operators can also monitor the operating parameters from the plant control room. 

Water injection, or steam injection systems, are being used extensively to augment power. Corrosion problems in the compressor diffuser and combustor have not been found to be major problems. The increase in work and efficiency with a reduction in NO makes the process very attractive. Split-shaft cycles are attractive for use in variable-speed mechanical drives. The off-design characteristics of such an engine are high efficiency and high torque at low speeds. 

The work required to drive the turbine eompressor is reduced by lowering the compressor inlet temperature thus increasing the output work of the turbine. Figure 2-35 is a schematic of the evaporative gas turbine and its effect on the Brayton cycle. The volumetric flow of most turbines is constant and therefore by increasing the mass flow, power increases in an inverse proportion to the temperature of the inlet air. The psychometric chart shown shows that the cooling is limited especially in high humid conditions. It is a very low cost option and can be installed very easily. This technique does not however increase the efficiency of the turbine. The turbine inlet temperature is lowered by about 18 °F (10 °C), if the outside temperature is around 90 °F (32 °C). The cost of an evaporative cooling system runs around 50/kw. 

The fuel. skid. This could contain a gas compressor if the fuel gas pressure is low and a knockout drum for any liquid contamination that the gas may have. The requirement of fuel gas pressure is that it should be operated at a minimum of 50-70 psi (3.5-4.83 Bar) above the compressor discharge pressure. The compressor and its motor drive fall under the drive level hierarchy. In the case of liquid fuels, the skid may also contain a fuel treatment plant, which would have centrifuges, electrostatic precipitators, fuel additive pumps, and other equipment. These could be directly controlled by the D-CS system, which would then report its readiness to the gas turbine controller. 

Instrument and Plant Air Systems. A typical setup for a large plant could include three to four 50% instrument air compressors and two 100% plant air compressors, with steam drives for normally operated units and electrical drives for spares. Common practice would provide an interconnection to allow makeup from plant air into instrument air, but not vice versa, and two sets (two 100% driers per set—one on-stream and one regenerating) of 1007c instrument air driers. Two main receivers on instrument air near the compressors with several minutes holdup time and satellite receivers at process trains would be likely and proper for feasibility cost estimating. 

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