6 replies to this topic

[Babu Prasad]

Our plant equipped with propane refrigeration compressor driven with gas turbine. This four stage compressor utilized to compress the propane vapour generated from chiller and cooler used for product and feed gas chilling. Propane vapour from discharge compressor condensed with air cooler and liquid stored and distributed through surge drum to varies chiller. The air cooler inlet temperature designed 47 °C whereas ambient temperature during peak summer time reaches 55 °C, hence condensation of propane vapour by air cooler is getting restricted which gives high load to turbine. Further turbine power also restricted due to high air intake temperature (due to high ambient ) and deliver less power to refrigeration compressor. In order to maintain required suction flow, the refrigeration compressor’s antisurge valves open and offload the machine in turn it affects user chiller/cooler performance and force to reduce plant feed intake. To overcome this issue following proposal being considered . Kindly share your comments on this suggestion. Pls share any other possibilities to overcome this issue.

1. Turbine vendor suggesting Evaporative Cooling method at air intake of turbine to cool the air utilized for combustion sothat turbine power and efficiency increase as inlet air temperature reduce.

2. In compressor side, if combined refrigeration medium of propane and butane at ratio of 75% and 25% maintained, sothat mixture of propane and butane will bring down condensation point to the some extent there by compressed pressure ratio can be reduced in turn it reduce power requirement from turbine.

[Bobby Strain]

Item 1 is a good idea. Item 2 seems a bit hokey. You must consider the chiller requirements as well as the condenser.

 

Bobby

[ColinR33]

I agree with Bobby.  Use the evaporative cooling on the suction and on the condenser.  Alternatively you can check the condenser design and see if a redesign based on the higher ambient temperature is feasible (additional cooler bays if you have the space available).  You may also want to check the system insulation, if the ambient temperature is superheating the suction stream too much, perhaps you need better/thicker insulation to reduce the amount of superheat.  If you start mixing butane with your refrigerant propane you will lose chiller performance (trust me, I know, we had a client who put a propane/butane mix into the propane refrig system we supplied and then cam screaming to us because it was not cooling down the process enough - changed out to proper refrigerant grade propane and no more problem).

[Root]

Item one, hot air always help for better combustion and no need to address this issue, and Item two you need to check operating conditions and if possible then apply some deluge system (water sprinkler on propane air fan coolers). and if you need more support then attach PFD of your system.

[Bobby Strain]

Root,

      You need to review gas turbine fundamentals and understand that the turbine air compressor handles more air at lower temperature with reduced power required. And, water spray will work for a short period. Until the minerals deposited by the evaporating water foul the surface.

How did you come up with this bad advice?

 

Bobby

[Babu Prasad]

Thanks all of you  for your valuable input.

Mr. Bobby/Mr. Colin I agree, Item 2 is not possible as we may not attain required product outlet temperature at chiller outlet . Mr. Colin, Good idea to check insulation . There is plan to be revamp the insulation as it worn out. additional cooler bays was ruled out due to high cost run Mr. Root . water sprinkler on propane air fan coolers was suggested by our team as temporary remedy until additional sea water condenser procured. As Mr Bobby said scaling/ minerals deposit may be concern if water deluge used but there is a plan to use Demineralized water for this purpose. hope it will minimize scaling deposit . .

[Bobby Strain]

Just remember that demin water is corrosive to carbon steel.

 

Bobby