7 replies to this topic

[katy]

Hi,

I want to optimize 3 stage compressor. I dont have any data regarding compressor. Just know inlet, dischrage pr. Using pressure ratios how can I design a spreadsheet for running simulation.

[Bobby Strain]

So, what kind of compressor is this? Do you have a process simulator like HYSYS? Is there condensation between stages?
You can access software at Dresser's website. And you can download reciprocating machine software from Ariel.

Bobby

[katy]

Thank you Booby.
They are reciprocating compressors. I am using hysys. 3 stage compression is for gas processing

[Art Montemayor]

Katy:

No one in the processing industry “optimizes” the design of a reciprocating compressor except the actual compressor manufacturers. And what they optimize is the capacities and economics of achieving those capacities. You have absolutely no say or decision in their results – unless you have enough money to finance their subsequent design and warranties in order to meet your dimensioned specifications.

However, if you like to run simulation programs and want to calculate what you consider an “optimized” compressor design, you are certainly free to spend your time doing that. But if you try to use your results to specify to a compressor manufacturer what to build for your application, you will soon discover you have wasted your valuable time.

Reciprocating manufacturers have already “designed” and “optimized” their product(s). All you have to do is resort to studying their brochures and literature. They have standardized their cylinder types, sizes, and shapes. They have also standardized the strokes of the machines they will produce and at what rpms they will operate. All this means that they can “fit” your volumetric capacity specifications complete with the pressures required by resorting to a combination of their cylinders, frames, and rpms. And they will do this bearing in mind that they are competing with other manufacturers. Therefore, they are very careful about what you give importance to and what you are willing to pay for the warranted performance.

What you, as a user (or customer) is expected to specify to them is:

• The gas to be compressed and its specific composition;
• The suction pressure and temperature;
• The total discharge pressure;
• The desired number of stages;
• The desired inter-stage pressure (if needed);
• The selected type of driver;
• Various other specifics such as lubrication, cooling media, piston speed, capacity controls, etc.

The manufacturer will furnish you with all the results obtained by using their recommend model of machine and driver.

What are you looking to find out by running your “simulation”?

[kkala]

'katy', on 09 Oct 2012 - 9:34 PM, said:

I want to optimize 3 stage compressor. I dont have any data regarding compressor. Just know inlet, dischrage pr. Using pressure ratios how can I design a spreadsheet for running simulation.

Agreeing to above post No 4, have you read about ideally optimum interstage pressures of a reciprocating compressor (to minimise consumed power)? If you have not, attached "recips.pdf" can be useful (p. 10, bottom). A lot of books report the subject (I recall it from student courses).
First interstage pressure would be p1*(p2/p1)^(1/3), second p1*(p2/p1)^(2/3), where p1=inlet pressure and p2=outlet (3rd stage) pressure, in absolute (not gauge) units (e.g. p1=1atm a, p2=8 atma, then 1st stage=2 atma, 2nd stage 4 atma).
Probably you look into this subject for some simplified knowledge to face Vendors later.

Attached Files

•  recips.pdf   535.95KB   187 downloads

Edited by kkala, 21 October 2012 - 04:22 PM.

[Propacket]

Katy,
There is only thing which you can use to evaluate what you name optimization;Interstage Pressure. You can calculate and play with interstage pressure to reach an OPTIMUM solution. However it will always be confirmed/optimized by the compressor vendor. Sometimes we have to offer budget cost and do not have enough time to get it designed from the vendor. In such cases, we always mark our proposal with "interstage pressure to be optimized by the compressor vendor".

[katy]

Thank you Montemayor,

Actually i am lack of datasheets of the compressors.But i have some plant data.

[Art Montemayor]

Katy:

What are you looking to find out by running your “simulation”?