Posted by lou christou on June 11, 2001 at 23:46:00:
In Reply to: Re: calculation of circulation posted by Tarzan on June 11, 2001 at 07:08:42:
: : How can I calculate the circulation in natural
: : circulated water tube boilers with working pressure
: : 10 - 30 bar ? Computer programs ? Litterature ?
: : Leif Brandstedt
: Leif, circulation is dependant on design of a particular boiler. The size and number of downcomer tubes in relation to the size and number of generating tubes. The location of the burners, location of baffles in the tube banks, even the arrangement of tubes in the tube banks all have impact on circulation.....it's difficult to plug all that into a formula that can be applied to all W/T boilers.
: Boiler designers insure that any given boiler will first reach the end point of combustion before the end point of carry over and last, the end point of circulation....so, I'm sure they have methods to make their calculations.
: I think your best bet for the information you seek might be to ask one of the manufacturers tech guys.
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Leif,
All boiler manufacturers will have their own, in house programs for the calculation of natural circulation. Unfortunately these programs are proprietary items and are unlikely to be released.
Any circulation program will look ata finite number of circuits and junctions. It will solve simultaneous equations for continuity, pressure loss and static head to give flows in each circuit.
The above is extremely tedious for a large number of circuits, hence the programs. However, if you can reduce the number of circuits to say three or four, you can solve graphically to get a reasonable idea of overall circulation.