Boiler natural gas requirement

[mechanicblues]

Hi, is there a rule of thumb or a formula to calculate natural gas requirement of a boiler, (only known value is boiler,s output, in kW)?

 

[metengr]

mechanicblues;
Is this a new boiler or an existing boiler? If it is existing, what type of fuel was originally specified for the boiler?

We have several large Power Boilers that were retrofitted to burn natural gas to avoid large deratings and one or two units that can burn 100% natural gas, if required.

 

[rmw]

It is something that has to be calculated. You have to take into account the amount of heat transferred to the water to make steam, all the losses and there are several to consider, blow down, stack losses, insulation and radiation losses, etc. Then you will arrive at how much gas is required to produce that much KW output.

This can vary depending upon whether you have air preheat, economizers, O2 trim control; a myriad of factors.

rmw

 

[mechanicblues]

metengr,
It is a new 3500 kw boiler. The fuel will be natural gas.

 

[athomas236]

If we guess a GCV of 52MJ/kg and a gross efficiency of 80% then the gas requirement can be estimated as:

(3500/1000)/(52*80)*100 which is 0.084kg/s or 670 lb/hour

regards,

athomas236

 

[mechanicblues]

Thank you all.

 

[kbs]

Another "Rule of thumb"-
3500kw output is 4375kw input at 80% gross eff.
4375kw = 14927500btu/hr. (cv1000btu/cu.ft.)

Cheers
kbs