Compressors engine-driven

Compressors are usually high-cost items, but easily correlated by brake horsepower vs. S/horsepower. Variations in engine-driven reciprocating compressor prices can be caused by the type of driver, the speed (the slower the speed the more costly, but the more reliable), the total discharge pressure, and the size. 

Figure 3-4. Cutaway of a two-stage piston engine driven compressor. Courtesy of Dresser-Rand)...

While ricn common, engine-driven centrifugal compressors are used. This combination is desirable for low-ratio applications and in fuel cost situations where the high engine efficiency is attractive. The difference in rotating speeds (engine 300-600 rpm, compressor 3,000-5,000 rpm -t-) requires the use of a speed increaser. 

Late in the field life it is desirable to compress the 100 MMscfd for the example field downstream of the separator from 800 psig at 100°F to l.(XX) psig. An engine-driven separable compressor is available from surplus. The engine is rated for 1,600 hp at 900 rpm. Horsepower is proportional to speed. The compressor frame has six 7-in, bore by 6.0-in. stroke double-acting cylinders with a minimum clearance of 17.92%, a rod load limit of 25,000 lb, and rod diameter of 1.75 in. Assume k = 1.26, Z, -0.88, and Zd = 0.85. 

Given An engine-driven compressor to handle 244 cfm natural gas (gravity = 0.658) at intake conditions of 90 psig and SOT, to discharge at 150 psig k = 1.27. 

Figure 14-33. Gas engine driven parallel compression cylinders in process gas plant service. Note that the front side of gas engines are on the right with high-pressure compressor cylinders extending horizontally left. Also note the suction side pulsation drums on top of compressor cylinders, mid-way. (Used by permission Cooper-Cameron Corporation, Reciprocating Products Division.)...

Vapor released and ignited from exhaust of engine driven compressor resulting in explosion. 

One dry chemical extinguisher (3-A 10-B-C) should be provided on a combustion engine driven vehicle, compressor, or welding machine. 

In a gas engine-driven chiller, the engine produces mechanical shaft power that is used for operating a chiller compressor. Such chillers are very similar to conventional electiic-diiven chillers. The only difference is that the electric motor that drives the compressor in an electric chiller is replaced with a reciprocating engine. 

Note that, as a rule, compressors are driven by electrical engines, and efficiencies of power stations ate below 0.5 (conversion of chemical into electrical energy). Using such electrical engines the above minimum percentages of the processes 1-4 have approximately to be doubled. 

Conduct air quality tests annually on internal combustion engine-driven airline respirator compressors to ensure proper air quality. 

Engineering Data are collected on the number of failures of piston rings in the legs of steam-driven compressors. Engineers are interested in determining the probability of piston failure in each leg and whether the failure varies among the compressors. 

On a typical pipeline, compressor stations are located at 81—161-km intervals and may contain up to 15 compressors. These stations may use either gas-turbine, reciprocating-engine, and/or motor-driven centrifugal compressors capable of boosting pipeline pressure and keeping gas moving at an average speed of about 24 km/h. Gas-turbine-driven units are the most popular. 

Power Take-Off From Engine or Transmission. This type of system is limited to tmcks and there are several take-off means available. Most are some form of electric power generation equipment, belt-driven from the engine crankshaft, which produces either a regulated a-c voltage or rectified direct current for the compressor and fan motors in the body. 

The compressor can be driven by electric motors, gas or steam turbiaes, or internal combustion (usually diesel) engines. The compressor can also be a steam-driven ejector (Fig. 7b), which improves plant reUabiUty because of its simplicity and absence of moving parts, but also reduces its efficiency because an ejector is less efficient than a mechanical compressor. In all of the therm ally driven devices, turbiaes, engines, and the ejector mentioned hereia, the exhaust heat can be used for process efficiency improvement, or for desalination by an additional distillation plant. Figure 8 shows a flow diagram of the vertical-tube vapor compression process. 

But the idea of gas turbine itself can be traced back to a 1791 patent by Barber, who wrote of the basic concept of a heat engine for power generation. Air and gas were to be compressed and burned to produce combustion products these were to be used to drive a turbine producing a work output. The compressor could be driven independently (along the lines of Whittle s early thoughts) or by the turbine itself if it was producing enough work. 

High-speed units are typically engine or electric motor driven, although turbine drivers have also been used. Engines or turbines can be either natural gas or diesel fueled. By far the most common driver for a high-speed compressor is a natural gas driven engine. 

Industrial gas turbines are available as either single-shaft or multishaft engines. The turbine illustrated in Figure 16-6 has a single shaft. Both the air compressor and the power turbine section operate off the same shaft and thus rotate at the same speed. As illustrated in Figure 16-14, in a multi-shaft unit some of the power turbine wheels are on the same shaft as the air compressor, while the remainder of the power turbine wheels are on a separate shaft that provides power to the driven equipment. The speed of the wheels of the power turbine that provide the... 

Figure 16-16 shows the performance characteristic of a split-shaft turbine where the only power output limitation is the maximum allowable temperature at the inlet of the turbine section. In actual practice a torque limit, increased exhaust temperature, loss of turbine efficiency, aud/or a lubrication problem on the driven equipment usually preclude operating at very low power turbine speeds. The useful characteristic of the split-shaft engine is its ability to supply a more or less constant horsepower output over a wide range of power turbine speeds. The air compressor essentially sets a power level and the output shaft attains a speed to pnivide the required torque balance. Compressors, pumps, and various mechanical tinvc systems make very good applications for split-shaft designs. 

Mechanical efficiency is the ratio of compressor cylinder indicated horsepower to the brake horsepower. Efficiency values range from 90-93% for direct-driven cylinders to 87-90% for steam engine units. The efficiency of the driver is not included. 

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