Compressor Characteristics

In all static surge-detection devices, the actual plienonemon of flow reversal (surge) is not directly monitored. What is monitored are other conditions related to surge. Control limits are set from past experience and a study of compressor characteristics. 

Electric motors above 5,000 hp are custom-designed for the specific application, taking into consideration compressor characteristics and the power system parameter limitations. 

In designing for vacuum, credit may be taken for the fact that a vacuum situation may not create a full vacuum. Thus, not all vessels or equipment need be designed for a 100 % vacuinn situation. For example, if the vacuum situation is created by a blocked suction in a compressor circuit and the vacuum created is limited to 10 psia by die compressor characteristics, the system needs only to be designed for 10 psia. 

Figure 12-61. Manufacturer s typical centrifugal compressor characteristic curve.

Figure 12-86 shows the effect of changing speed on the compressor characteristic curve. The speed can be adjusted to meet a desired point on the system curve. This is the most popular form of control. 

Gaseous hydrogen may be carried widely by pipelines. Pipeline transportation costs are divided into three components energy, compressor capital cost, and pipeline capital cost. Pipeline transportation costs are affected by the pipeline characteristics, compressor characteristics, production rate, transportation distance, and hydrogen properties. Unlike other transportation options, the methodology used in HjSim to determine pipeline transportation costs is not drawn from Amos (1998) work, as it offers users considerably more options than just a single pipeline. The basic assumptions regarding the pipeline and compressor characteristics are summarized in Table 7.9. 

Pipeline and compressor characteristic assumptions Pipeline cost estimates... 

Law compressor A particular compressor characteristic (see companding) used in telephone representation of speech signals. 

FIGURE 3.9 Compressor characteristic curve of turbocharger GT35 and surge control line... 

In this part we have investigated the effect of this mechanism on performance of system. For this purpose we compared pressure ratio versus modified flow rate curve of a compressor with compressor characteristic curve for totally open wastage in 1,800 2,200 and 3,000 rpm. The comparisons have been illustrated in Figures 3.11 and 3.12. According to Figure 3.11, the performance of compressor in rotation of 3,200 rpm is in safe region and faraway of surge and... 

Each of the methods of control affects the compressor curve to produce a set of curves called the compressor map (Figure 7.28). The various curves show the compressor characteristic at different values of the parameter being varied, such as inlet valve setting or speed. At each crossing of a compressor curve and a system curve, specific operating points occur which, collectively, estabhsh the controllable range. 

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