Boiler Efficiency 2

[Murdul]

Our boiler is burning very inefficiently. I have modelled our system with SSAT software for Excel and made my own calculations and I get the same results.

We have a 20,000lb/hr fire tube boiler. We burn Natural Gas. On average our the facility only draws 6,000lb/hr steam at 140psi. I have calculated our fuel to steam efficiency at ~60%. I assumed 1030BTU/CF of N.G.

Would the low load account for the low efficiency of the boiler?

Is there any other way to increase our efficiency other than buying a smaller boiler?

I have checked the traps, looked for leaks.

Currently we do not have condensate return, actually you'll love this we pump our condensate into our cooling water system.

I would like to hear some suggestions we could make to increase efficiency.

Thank you

 

[rmw]

TBP, that was an euphamistic way of saying 'if you can get funds' because I have found that it is hard to get the accountants to agree to what is needed for technical reasons.

I recommend the meter and the calibration of the current instrumentation, e.g. O2 meter, as well as other improvements, but I can just picture the reaction of those that control the purse strings.

My point was to move to the fixes and the limiting parameters whether or not they turned loose of the funds to buy the needed instrumentation.

rmw

 

[davefitz]

I am sure that if you contact the boiler OEm or the various burner mfr's , you will find that there are new burners developed specifically of the California market that have wide turndown, ultra low Nox, and very low excess air requirements. In the case of small industrila boilers, the same techmology that is ued to lower Nox will also yield higher boiler efficiency due to lower excess air operation.

 

[chicopee]

Here are some statistics for FT boilers. I am assuming that you have a Scotch Marine type which is probably the most efficient of all the 5 types of FT boilers.
Steaming rates: 5 to 7 lbs/hr per ft^2 of heating surface
: should not exceed the 7 lbs/hr-ft^2
Efficiency :75% to 80%
(steam generation to fuel input to boiler)
(w/o econmizer,superheater and air preheater)
You can easily determine the burner max firing rate by using the above stats.