Reciprocating & centrifugal compressors maintenance cost

[Arunkumargupta]

What should I take as annual repair and maintenace cost for reciprocating and centrifugal compressors in feasibility studies.

 

[25362]

This is a difficult one. The experience of one user differs from that of another. The number, type and size of compressors as well as the compressed gas quality and the skill of operators and maintenance people.

Maintenance departments plan shutdowns and inspections every 12 to 16 months.
There are operators that take compressors out of production substituting capacity from rental units.

In one instance, parts and labour on air compressors (rotary, screw, and reciprocating) dropped markedly when switching from a mineral oil based lube to synthetic PAOs.

One would tend to use some % of the compressor cost -as new- to estimate the yearly cost for feasibility studies.

 

[July]

Typically maintenance costs on reciprocating machines are more than for centrifugals. If you are comparing the 2 options, this could be a factorto be considered. In fact there sre systems where we provide no spares for a centrifugal machine but the reciprocating machines are spared.

 

[Hookem]

First, consider fuel. Is the amount of fuel "non-valued" or "valued", that is, is the amount of consumption considered an expense? And, how much of that can be considered as free of royalties, per the lease agreements, as this percentage reduces the amount of the charge. Additionally, what is the compression ratio? At 2:1, fuel may only be 3-4% of throughput. At 12:1 (esp. with multi-stage recip's), fuel may be 10 - 14% of throughput.

Second, consider lube oil and other consumables. Include OEM lube oil changes (crankcase capacity, etc.). Will synthetics be required? or permitted?

Third, consider personnel costs of operating, starting, stopping, monitoring, planning, load analysis, performance monitoring, etc. Is the location remote? or in major area with lots of infrastructure? Are far away are skilled personnel? How well are they trained on that particular OEM equipment?

Fourth, consider longetivity. If the expected life is short, overhauls may not need to be considered (in which case you ought to consider leasing anyway). If the expected like is long, overhauls must be considered (and you must take OEM recommmendations with a pound of sald). You must either have, or get, similar equipment multi-year operating experiences.

Fifth, consult, ask, research, dig, etc. A lot of operating companies accounting records are not set up track what we engineers really need.

Good Luck.