5 replies to this topic

[ankur2061]

wanttolearnprocess,

Use the search feature of the forum, plenty of information is available related to compressor selection. One link is:

http://www.cheresour...ssor-selection/

For centrifugal compressors "Dry Gas Seals" are preferred which you can look up at:

http://www.cheresour...r-seal-systems/

For various kind of compressor sealing systems refer some good books on compressors. Books on compressors are listed at:

http://www.cheresour...gn-engineering/

Regards,
Ankur.

[Art Montemayor]

Wanttolearn:

What are the specific maintenance problems that you are experiencing with a liquid ring compressor? What are you compressing, the pressures involved, and the liquid piston medium being used in the machine?

[Art Montemayor]

Wantolearn:

You are compressing a complex, potentially hazardous vapor mixture in one compression stage with a compression ratio of 6.14. And your discharge product has only 76 ^oC. That says a lot for a process engineer seeking the “perfect” gas compressor.

Of course, there is no perfect compressor. There are only appropriate compressors for the specified job – and each one has its draw backs or trade-offs. The liquid ring compressor is no exception. However, if I had a compression application and the liquid ring compressor was one acceptable candidate, I would certainly evaluate it first and consider it as my choice unless it was defeated by one of the other types. The following is an attempt to list some of the favorable traits of the Liquid Ring Compressor:

• It is the only positive displacement compressor yet devised by engineers that approaches an ideal isothermal compression; isothermal compression is “ideal” thermodynamic compression that yields the theoretical minimum power requirement;
• It is a positive displacement machine that has no physical contact between its moving parts contributing to the compression;
• It is a positive displacement machine that has a rotating piston – eliminating the need for a crank, connecting rod, and crosshead. It also is devoid of any compressor valves. Maintenance, wear, vibrations, noise, lubrication, inter and aftercoolers, and forced lubrication are essentially eliminated.
• By using a liquid piston, the compressor can handle problem gases that have entrained dust or solids; the compression chamber acts as a mechanical scrubber and literally “washes” the dust particles out of the gas;
• Because of its simplicity (the only contact surfaces are those of the shaft seal), the machine has maximum operating time and minimum downtime and wear;
• The machine is such an ideal positive displacement device that, when used as vacuum pump, it can produce 35 Torr of vacuum – something a centrifugal compressor can never aspire to even think about.

A centrifugal compressor can claim minimum wear because it also has only seal wearing parts; however, it falls well short of expectations against the positive displacement and isothermal features of the liquid ring machine.

You should not have any mechanical problems with a liquid ring compressor. The fact that you are means that something is wrong in the installation, the operation, or the basic design of the machine. You should have already made this known to the supplier and fabricator of your compressor. There should be a reasonable solution to your problem and you should contact them. We certainly are in no position to judge or even guess what the problem is. What I can state is that the compressor’s shaft should last a lifetime. There is no reason to accept a broken compressor shaft taking place. This should never happer.