3 replies to this topic

[vsedhuraman]

Dear sir,

 

         I need to calculate the KW(Btu/h) requirement for Vacuum loop boiler (Heat Driven Technology).

 

Description of System : Natural gas @ high pressure flow thru the single pass heat exchanger and this Natural gas to be heated upto 2 - 4° C from the inlet temperature. Natural gas pipe is located inside the Condenser and steam to condenser will be generated from Evaporator. Evaporator is operated under vacuum pressure and heating fluid will be Glycol + Water Mixer inside the evaporator.

 

Burners are used to Heat the Glycol + Water mixture(Evaporator) to generate steam under vacuum pressure and the generated steam is passed thru Heat exchanger and this steam is used to heat the Natural Gas flow thru the pipe and the condensate will be return to evaporator.

 

I have used the formulas to calculate the KW (Boiler) based on Natural Gas Flow and Temperature difference.

 

Q = m. Cp . Delta T.

 

From Customer I have received inputs as mentioned Below ,

Natural Gas Flow : 35000 m³/hr

Pressure : 440 psig (Inlet) & 225 psig ( Outlet)

Specific Heat of Gas : 0.66 Btu / Lbm °F

Temperature Difference : 2 °C

 

Based on the above inputs, I have calculated the Boiler KW is = ~50 KW.

 

Please advice on the above calculation, Whether the calculation is correct or I missed something. Experts advice is required.

 

Regards,

 

Vijay

 

 

 

 

[breizh]

Hi ,

Provide a schematic of your process (PFD or PID) will all parameters available ( Flow rate, composition, temperature, pressure) it will save words and mitigate the risk of confusion.

 

Breizh

[vsedhuraman]

Hi,

 

 Thank you for your reply,

I am attaching the required details. Based on the Natural Gas Flow and Temperature to be increased, i need to calculate the boiler KW requirement. How much Btu's/hr required to heat the Natural gas from 4 °C to 6°C based on the pressure and Flow as mentioned in PFD.

 

 

Regards,

 

Vijay

Attached Thumbnails

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[breizh]

Hi,

you want to perform a heat balance on the natural gas, right ?

 

H Ng inlet  = cp Ng inlet *(Tinlet-tef ) 

similarly 

H Ng outlet  = cp Ng outlet *(Toutlet-tef ) 

 

Q exchanged = m*( Houtlet -Hinlet) 

with m= Qv* density NG 

 

50 KW seems not reasonable ....... 

 

missing data :

density of NG at different pressure/temperature , outlet or inlet condition

heat capacity at different pressures (outlet and inlet )

 

note 0 : you have mass conservation not volume conservation , QV is not constant.

note 1: make you don't mix up the units , consider to work with one system only, either SI or British .

note 2: you may find missing data on your NG bill or ask the supplier,

here in Thailand PTT : http://pttinternet.p...egas/online.asp

 

Hope this is clear 

 

Breizh