2 replies to this topic

[bevon]

Hello All,

 

I am currently working on a academic project that requires me to evaluate the performance of a natural gas compression system aboard an offshore platform with a focus primarily in the compressors and not on the ancillary components. The system used for gas lift consist of the following arrangement

 

1) Four individual 3 stage Ingersoll Rand (IR)integral compressors connected in parallel

 

2) Three individual 3 stage Solar (SR)centrifugal compressors connected also in parallel

 

3) The cumulative outputs of the IR and SR compressors are discharged at the same pressures of 1000 psia, temperature 95 (degree F) and flow rate 65 mmScf/d via two six inch pipelines also connected in parallel that eventually meet and combine discharge flows on a single 8 inch line. The suction pressure and flow rate seen by each individual compressor is 35 psia and 60mmscf/d respectively.

 

All the physical and mechanical data such as pressure ratios per stage, cylinder clearance stroke size, temperature between stages etc are given for both the IR and SR compressors but what worries me is the following statement

 

"The sum of the nominal capacity for all units is 75 mmScf/d"

 

I have reviewed literature to determine what this statement means precisely but most are vague and I am left with the following questions,

 

1) Is the total  nominal capacity referring to the design capacity of the entire system or individual compressors?

 

2) How can I go about computing the actual capacity seen by both the integral reciprocating and centrifugal units to check if there is bottle necking or available capacity for inserting systems such as ejectors (surface jet pumps) to help  with increasing reliability? 

 

Thanks for any assistance lent,

[PingPong]

Your questions requires a lot of additional information, most importantly:

- original datasheets and performance curves of all compressors;

- original design gas compositions as well as present gas compositions;

- process flow diagrams of the complete compression system showing original design operating data such as temperature, pressure and flowrates;

- DCS screen prints of the complete compression system showing actual present operation temperatures, pressures and flowrates;

- P&ID diagrams of the complete compression system, from the point in the suction system where the pressure is controlled, up to a point in the discharge system where the pressure is controlled.

 

Also good to have are:

- control description and logic diagrams of the complete compression system;

- cause & effect diagrams of the complete compression system safeguarding.

 

1) Is the total  nominal capacity referring to the design capacity of the entire system or individual compressors?

Impossible to say without above listed required information.

Note also that a compressor does not really process Standard cubic feets, bit Actual cubic feets.

[bevon]

It is apparent that I have bitten of more than I can chew with this project, thanks for painting a holistic picture of the process requirements.