Compressor, centrifugal screw

Compressor centrifugal, screw or reciprocating electric motor, steam turbine, or other driver... 

For ease of illustration we will consider the characteristics and behaviour of a centrifugal pump which is similar in behaviour to radial/axial flow fans and centrifugal/screw compressors. Figure 63 shows the mechanical connection of a flow valve to control the output of the pump or the discharge of the fluid through the throttle of the valve. Figure 6.39 illustrates the characteristics of the pump ... 

Data from an existing collection system were analyzed for failure modes and distribution. The results of Pareto analyses indicate the principal causes of failure. A few values of mean times to maintenance action (MTBM) are given for ethylene plant pumps (85 electric driven centrifugal pumps over a 19-month period), and ethylbenzene-styrene monomer plant equipment from 10 months data 4 gas compressors, 3 screw conveyors, 121 pumps, and 235 other items... 

Motor-driven, multistage reciprocating compressors have reportedly been the most popular choice for aeroderivatives. Motor-driven, oil-fiooded screw compressors are also used in some cases. High horsepower, multistage centrifugal compressors, similar to those used at many pipeline compressor stations, may be required for the newer heavy-duty units if the distribution pipeline pressure is insufficient (see Pipelines). Gas turbines have more stringent fuel-gas specifications in terms of cleanliness than do gas-fired boilers. Thus oil- and water-knockout systems, coalescing filters, and fine-mesh filters are used. 

Of the gas turbine-compressor combinations previously mentioned, gas turbines are by far the most frequently used as drivers for centrifugal compressors. Next in use would be axial compressors and, on occasion, the gas turbine is used as a driver for the larger screw compressors. There... 

While many of the applications use the expander to drive a generator, a compressor is a good alternative candidate for the load. Expanders are generally custom-sized and can, therefore, be readily matched to the centrifugal or axial compressor. It also will match the screw compressor of the dry type, at least in the larger frames, Basic sizing to the compressor should follow the same guidelines as for steam turbines. 

Figure 11-21A. Typical centrifugal compressor with economizer packaged refrigeration system. Note that screw-type or even reciprocating compressors can be used in such a system. (Used by permission Cat. 521-727, 1995. Carrier Corporation, a United Technologies Company.)...

The reciprocating, centrifugal and rotary-screw compressors described in the chapter covering this equipment design and selection are also used in refrigerant service. Sev-... 

In much the same manner as pumps, compressors are classified as one of two general classes positive displacement or dynamic (see Figure 3-68) [23]. These two general classes of compressors are the same as that for pumps. The positive displacement class of compressors is an intermittent flow device, which is usually a reciprocating piston compressor or a rotary compressor (e.g., sliding vane, screws, etc.). The dynamic class of compressor is a continuous flow device, which is usually an axial-flow or centrifugal compressor (or mix of the two). 

Piston, screw and centrifugal compressors are used. As many chemical processes, such as oil refining, may have cheap waste heat, large absorption systems will also be found. 

Large systems working at temperatures above freezing may be able to use centrifugal compressors, but the pressure ratio is not favourable. Most heat pumps will have reciprocating or screw compressors. Refrigerants are those in general use. 

Compressors, turbines, fans Centrifugal compressors Reciprocating compressors Screw compressors Turbines... 

The refrigeration compressor is usually the most expensive equipment of small-scale liquefaction plants. Smaller units may employ screw or reciprocating compressors, whereas centrifugal compressors always are used in larger units. Driver selection is a key decision point in project development, and can be either turbine, gas engine or electric motor. 

Therefore, negative pressure was decreased to reduce tramp air. Also, the operational reciprocating compressor was replaced by a centrifugal rotary screw type compressor. Further, ash build up on the boiler superheater tubes was a problem, impeding heat transfer to cool down the flue gas. This problem was resolved by using acoustics to cause the ash to fall off the superheater and economizer tubes. This allowed lower fuel consumption, resulting in decreased NOx emissions.1... 

Compression power accounts for more than 80% of the total energy required in the production of industrial gases and the liquefaction of natural gas. In order to minimize the cost and maintenance of cryogenic facilities, special care must be exercised to select the appropriate compression system. The three major types of compressors widely used today are reciprocating, centrifugal, and screw. Currently, there is no particular type of compressor that is generally preferred for all applications. The final selection will ultimately depend on the specific application as well as the effect of plant site and existing facilities. 

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