Posted by Rod Nissen on December 01, 2001 at 06:43:05:
In Reply to: reducing system pressure posted by Dan Romeo on November 29, 2001 at 18:38:53:
Firstly what are you doing with the steam? If, as I suspect it is process heating then by reducing the steam pressure and applying the reduced pressure to heat a load (ie condense the steam), you will transfer more heat. This is because the latent heat given up is higher the lower the pressure is. Of course you need to have a temperature differential between the steam and fluid it is heating. Look at steam tables to check the temp of the steam at a particular pressure. Often a reduced pressure of around 30psig is adequate. Now you need to do the reducing at the heat exchanger, because it is more efficient to transfer the steam from the boiler at the highest pressure. This reduces the size of pipe required (because of the steam's lower specific vol.). Reducuing the pipe size, reduces its surface area, so reducing radiated heat losses and also reguires less insulation.
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