5 replies to this topic

[processengbd]

My client intent to cool the feed gas prior to Two Phase separator.

 

Plant Feed gas (Natural Gas) Temperature 140 F

Its Hydrate formation temperature is at 68 deg F

 

We have two stage pressure reduction form 1700 psig to 1200 psig prior to Two phase separator.

 

My client has suggested a water cooled heat exchanger with a  cooling tower. 

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We recommend fined tube heat exchanger with water spray on the outside.

 

Can you please suggest a type of heat exchnager.

[ankur2061]

processengbd,

 

Why not an air-cooled heat exchanger with mechanical louvres or variable speed fans unless you have constraints which you have not mentioned in your post?

 

Have you planned to address hydrate formation due to cooling?

 

Regards,

Ankur

[processengbd]

Mr Art,

 

Thank you for your comment.

 

In summer air gets heated up to about 110 F. LMTD gets really small sometime. We had to add very big surface area. So we thought water cooled heat exchnager might be more effective.

 

Besides some of the air cooler (regeneration gas cooler) is not performing well.They can not take the heat load in some of the existing plant.

 

We have stand by water bath heater for any low temperature situation to avert hydrate formation. 

 

Regards

Processengbd

[ankur2061]

Processengbd,

 

Large surface area for an ACHE is a layout and capital cost issue. If layout is not a constraint then you should be doing a Cost-Benefit-Analysis for a Water Cooled heat exchanger and an ACHE to come to a conclusion for the Life Cycle cost for the given design life of your facliities. In middle-east where summer ambient temperatures can go as high as 45 to 50°C, air-cooled exchangers are frequetly used. One of the obvious incentives of using ACHE's in a desert environment is that water is a scarce commodity.

 

"Approach temperature" is the correct terminology to mention whether an ACHE will work satisfactorily or not. Normally the minimum approach temperature recommended for design of ACHE's is 10°C. It means that a well designed and properly functioning ACHE will should give a outlet process fluid temperature equal to or below 10°C of the maximum ambient air temperature.

 

Hope this helps.

 

Regards,

Ankur.

[processengbd]

Thank you Mr Ankur for your comment.

 

Can you please direct me to any literature regarding cost calculation of this two process.

 

Air Cooled Heat Exchnager

Water Cooled Heat Exchnager 

 

Regards

Processengbd

[RockDock]

Are you going to run your TEG unit at 1200 psig? Bringing the pressure down to 900 psig would achieve the same temperature as an air cooler would likely give you. That is free cooling...