2 replies to this topic

[Darshan Soni]

Hi,
 
I'm new on cheresourses.com , Its really great source of knowledge for the fresh engineers like me in the field.

 

My Question is: Which are the practical & easily applicable ways to increase the efficiency of the compressors being used in CNG (compressed natural gas) application?

 

Details: Here at our CNG stations we are using

1. Intermech's BBR series 1200 SCMH compresor
   • Horizontal
   • Opposed balanced
   • intercooled
   • Tandem piston in HP side
   • Pressurized crank case
   • 160 KW motor driven, direct coupled
2. Cameron's superior series 650 SCMH compressor
   • CFA 32 crank case
   • Horizontal
   • Opposed balanced
   • intercooled
   • Tandem piston in HP side
   • Non Pressurized crank case
   • 90 KW motor driven, direct coupled
3. Burckhardt's CU series 650 SCMH compressor.
   • W type
   • intercolled
   • pressurized crank case
   • 90 KW Motor driven, belt coupled
4. Ruzza make 350 SCMH hydraulik booster compressor

• For Reciprocating compressors in 1,2 & 3, Suction pressure / 1st stage inlet = 12 - 19 Barg & Final discharge pressure = 240 - 245 Barg
• For hydraulik compressor in 4, suction pressure ranges from 40 barg to 190 barg & final discharge pressure is 240-245 barg

[Art Montemayor]

Darshan:

 

Obtain a copy of Norm Lieberman’s book, “A Working Guide to Process Equipment” and carefully read and digest the material he presents in:

• Chapter 27, Gas Compression: The Basic Idea;
• Chapter 29, Reciprocating Compressors; and,
• Chapter 30, Compressor Efficiency.

As Norm explains, there are really only two practical sorts of compressor efficiency:

1. Adiabatic efficiency; and
2. Volumetric efficiency.

Norm develops a third form that he calls “Relative Efficiency – a means to compare efficiencies (not calculate them) in a specific machine or between two compressors.

 

What you are operating in your facility are natural gas compressors designed for a scope or work that differs from more efficient process compressors.  Some of the machines you mention are relatively high speed, fast wear – and therefore not designed for continuous, cost effective, competitive operation.  In fact, these compressor packages are mostly designed to compete in selling price rather than in long-term performance.  As a result, you should not expect to extract more efficient operation out of this type of design than what they were designed to produce.

 

Other than cooling the suction and interstage flows to as low a temperature as you can, there isn’t much more you can do to increase the adiabatic efficiency of these type of small, fast rpm compressors.

[Darshan Soni]

Thank you so much sir.

 

our all reciprocating compressors are designed at optimum suction pressure of 19 Barg (both 1200 SCMH & 650 SCMH compressors).

We are operating the compressors at 19 barg suction pressure; Increasing suction pressure will benefit us in terms of power consumption?Up to %of optimum suction pressure (19 barg) we should increase the suction pressure?