Steam Generation

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7barg steam has a ΔH_fg of 2048kJ/kg whereas for 3barg it is 2134kJ/kg. So more steam will be used to effect the same heating duty.

However, the saturation temperature at 7barg is 170.4degC whereas for 3barg it is 143.6degC, so in principle if the exchanger, piping and trap can take the higher pressure and temperature then the exchanger duty can be increased without re-sizing it.

In summary, there is no economic saving to be had by increasing the steam pressure though there may be justifiable process reasons for doing it.

Thanks for the inputs

But if my rate of heating is increasing at 7 barg than it means I have to spend less steam and moreover the moisture content will be less , hence it will reduce the steam consumption?

huhhh? you gotta love the ease with which he did that (pwslack). but you can believe that your right. Are your sure your not confusing time and temperature? And that part about moisture really had me lost.

Yes i am talking about time , heating will be done in less time so overall steam consumption will get reduced, about moisture i mean to say that wet steam load is more at 3 bar than at 7 bar

Efficiency = heat used(latent heat)/heat put in (total heat).

Heating at say 150 psi = 858 btu/1197 btu x 100 = 71% .

Heating at 100 psi = 882 btu/1190 btu x 100 = 74.1%.

Heating at 5 psi = 961 btu/1156 btu x 100 = 83.1%.

Hence gain in efficiency at 5 psi = 12.1% and at 100 psi = 9%

Therefore, it is gain in efficiency when using lower pressure of 3 bar than 7 bar or 10 bar.

Moreover, for Heat Exchangers operating pressure 3.5 bar and lower recommended so as not to damage the plates/tubes.

suggest you email me at duconems@yahoo.com and I will mail you all calculation & formulas.

Hi

Please send me the calculations and formulas, my mail id is munish.prashar@gmail.com

Thanks

Assuming inlet water temp 15 C , heating 12 m3 /hr to 80C

At 7 bar = 12000 x 4.2 x (80-15)/2048 = 1600 kg/hr steam required

At 3 bar = 12000 x 4.2 x (80-15)/2134 = 1535 kg/hr steam required

Hence at a lower pressure there is a saving potential.

Hello Guest.

Steam insertion at 7 bar is Steam much hotter than at 3 bar. Therefore savings are made.

Should you want to save further money insert a steam turbine in your system. All heat is then transfered to your water plus you have free electricity.

1 litre of Steam per second at 9 bar pressure produces 720 watts

Cheers

Peter

Steam insertion at 7 bar is Steam much hotter than at 3 bar.

At reduced pressure the steam has a higher latent heat content and hence saving at 3 bar. Check your steam tables.

save further money insert a steam turbine in your system - How do you expect him to insert a steam turbine in the system? His steam is saturated and at pressure of 7~10 bar. Can you please describe what you have in mind.

Hello ducon,

I take it at some point there be a pipe attached to the boiler. By attaching a steam turbine into that pipe theres a good chance steam will pass through the turbine causing it to rotate. To maximise the bar pressure the closer the turbine to the boiler the better. The amount of electrical production is dependant on the bar pressure and litres per second passing through the turbine.

Cheers

Peter