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# Natural Gas for steam boiler

## Natural Gas for steam boiler

(OP)
Hi All:

I'm making some ball park figure calculations to estimate how much a laundry steam press would represent in terms of natural gas consumption at the steam boiler but I'm getting some numbers that don't seem right, but I can't find where my potential mistake might be.

Data:
Steam press consumption: 3kg/h
he:2,107 kJ/kg-5 bar saturated steam Specific enthalpy evaporation
Estimated steam boiler and distribution efficiency: 0.85
Natural Gas Density: 0.80kg/m3
Natural Gas Calorific Power (kW/kg):14.5
Heat Transfer rate of a steam condensing system:
q(KW)=he*steam flow rate (Kg/s)

Calculations:
q=1.76 kW equivalent to q(year)=15,382kW/year
Total NG (kg) needed to produce steam: 15,382/14.5/0.85=1,248 kg of natural gas-equivalent to 1,560m3 NG per year

It has been quite a while since I did this type of exercise so I'm afraid I'm missing something.

Is my approach correct?

Thanks a lot for your help on this.

Replies continue below

### RE: Natural Gas for steam boiler

I didn't go through your numbers, but I would approach this as a two part problem.
1. heat rate of boiler, how much gas is required to make some quantity of steam at some enthalpy
2. The steam consumption of the unit corrected for distribution and change in enthalpy

You should be able to reasonably verify each of these independently, make it easier.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

### RE: Natural Gas for steam boiler

Just off the top, 1560 m3 in a year is 6.29 cubic feet per hour, which is about 6290 btuh. That is not even the size of a small domestic water heater.

### RE: Natural Gas for steam boiler

I seem to recall having heard somewhere that for such small quantities of steam an electric boiler is sometimes the most cost-effective solution, depending upon energy costs and the A or A's HJ.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

### RE: Natural Gas for steam boiler

#### Quote (MedicineEng)

q=1.76 kW equivalent to q(year)=15,382kW/year
The figure 15382 should be kWh/year=55.38x10^6 kJ/year
Natural gas heating value should be close to 40,000 kJ/kg

So your yearly natural gas consumption should be 55.38x10^6/0.85/40000=1629 kg/year

Engineers, think what we have done to the environment !https://www.linkedin.com/in/goutam-das-59743b30/

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