Page 174 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Be st Practice 3 .11 Compressor Best Practices

Fig 3.11.7 Turbo-compressor impeller head
change and curve shape summary

stage in a multistage compressor. Depending on the impeller flow or stonewall region of the performance curve. In the
selection, this change could have an adverse effect on the op- choke flow region, the head produced by the compressor
eration of a dynamic compressor, causing surge and corre- approaches zero since the gas velocity is equal to its sonic
sponding high vibration, temperature, flow changes, etc. velocity.
Figure 3.11.11 shows the effect on compressor section
performance that results from a change in the molecular
The effect on power weight of the gas. As previously discussed, molecular weight
changes can result in compressor stage mismatching, which
As shown in Figure 3.11.10, dynamic compressor required can cause significant mechanical damage to the compressor
power increases directly with gas density up to the choke train.

Fig 3.11.8 The effect of process changes on the system resistance curve

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