4 replies to this topic

[Nirmal els]

Dear members,

I need to design a gas processing plant capacity for 0.5 mmscmd and composition are Methane-92.12,Ethane-2.07, H2S-0.0, CO2-3.36, N2-0.86

 

As per my calculation, 41 m3 (C2-20, C3-12, C4-9) of NGL can be produced if NGL extraction unit is installed. I presume, installing dehydration using molecular sieve to be carried out only during NGL extraction economically feasible, otherwise TEG is enough to maintain pipeline quality.

Water to be removed is around 70 lb/mmscf.

Wellhead pressure: 45 Kg/cm2 and Pipeline pressure: 75  ksc (Planning to install compressor at the upstream of Dehydration process)

 

The following are my queries:

 

1. Whether my assumption regarding Considering techno-commercial feasibility, Is it economical to design NGL extraction process for 25 MT/D?

2. Can we use molecular sieves compare to amine unit, which suffice the need of dehydration & CO2 removal or can I leave CO2 in the pipeline?

3. If possible, I need CAPEX and OPEX of different gas treatment process to compare economics of process.

 

Thanks

Edited by Nirmal els, 24 August 2018 - 04:43 AM.

[Bobby Strain]

You can forget about NGL extraction with this small amount of natural gas. CO₂ removal depends on your pipeline spec.

 

Bobby

[Nirmal els]

Thanks Mr. Bobby. 

 

Natural gas is saturated with water and hydrocarbon mist at wellhead conditions. Can I use condensation (using refrigerant) or TEG dehydration, which would be economical to maintain standard pipeline quality of gas? 

[Bobby Strain]

There is no standard pipeline gas quality. If you can separate the liquids in a separator, and the separated gas does not require removing any heavier hydrocarbons to meet heating value or other specifications, you may need only minimal treatment. CO₂ removal if necessary followed by glycol dehydration. You didn't mention H₂S or other sulfur content. Nitrogen content is one of the specifications to be met also.

 

Bobby

[Nirmal els]

H2S is nil and CO2 in pipeline should be < 4%. I'm planning to design a separator to separate heavy hydrocarbon. Considering these conditions, which is the best process to choose TEG, Condensation using refrigeration. I left dehydration using molecular sieve due to high cost. Also I planned to put booster compressor in the upstream of dehydration unit to reduce the load of dehydration unit. But my maintenance engineer is telling it would reduce the efficiency of compressor. How can make a trade-off between these two costs. Where can put my booster compressor?

 

Thanks