Page 188 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Be st Practice 3 .14 Compressor Best Practices

Fig 3.14.9 Stage and section performance (1st and 2nd impellers fouled)

Therefore, periodic condition monitoring of compressor discussed in a previous section. How then can we prevent
performance can provide advance warning to correct compres- fouling if possible? And how can we correct fouling, if and when
sor internal deficiencies at the first opportunity. it occurs? Can we correct fouling on-line? These are important
questions that must be answered. Figure 3.14.11 presents so-
lutions for preventing and correcting fouling.
Detecting fouling by condition monitoring

As previously discussed, the mechanism of fouling involves non-
uniform accumulation and removal of debris from the impeller
Preventive measures
or blade row, which results in a performance design change in Process control
the mass accumulation of the foulant on the impeller. This Proper inlet air filter selection and maintenance
action will change the rotor balance and the phase angle (the Condition monitoring (gas pressure, temperature and vibration)
heavy spot) of the unbalance. The suggested condition moni- On-line solvent injection
toring practice to detect and confirm fouling is presented in Impeller or blade coatings
Figure 3.14.10. Corrective measures
Slow roll or stationary wash
On-line random washing

Trend radial vibration and phase angle – a random change in Fig 3.14.11 Preventing and correcting fouling
both parameters indicates fouling
Trend compressor head and efficiency. Plot results on
compressor test curve – an increasing deficiency margin Preventing fouling
confirms fouling
Listed below are proven methods for preventing fouling.
1. Process control e Accurate control of process conditions
Fig 3.14.10 Condition monitoring guidelines to determine fouling
can prevent fouling in applications where polymers can be
formed. Control of temperature is usually the most important.
The following applications can be affected by excessive process
Preventing and correcting fouling
temperature:
Thus far we have seen how fouling can occur and how it can - Ethylene cracked gas
cause surge. The detrimental effects of surge have been - Linear low density polyethylene

162