Hello,
i have found an interesting page for answering a lot of questions in accordance with steam and steam boilers SPIRAX SARCO - THE BOILER HOUSE.
I was searching for solutions for direct water level control principles and controls because the benefits of indirect water level control on a steam boiler through a float valve in the hotwell are not available to me.
Best Dietrich
SPIRAX SARCO - The Boiler House
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Re: SPIRAX SARCO - The Boiler House
For many years I have used Sarco Thermodynamic Traps to automatically control the water level in my boilers.
Mounting the Thermodynamic trap on a tee fitting, in parallel with the boiler center "try cock", will prohibit the boiler water level from rising above this point. When the boiler water level is lower than this point, the trap is closed, and no flow of condensate or steam out of the boiler will occur. When the boiler water level rises,the trap goes into action, and discharges excess boiler water, and water level in the boiler cannot rise above this point.
The condensate discharge of the trap is directed back to the hotwell, or back to the feedwater tank, or overboard. A float style trap could also be used, however I have found the thermodynamic traps work perfectly at steam pressured up to 600 PSI (40 Bar). The boiler feed pump must always provide at least 100% of the steaming rate, but all steam plants already have this requirement.
A small counterflow heat exchanger, with pumped feedwater passing to the boiler, and trap discharge flowing in the opposite direction, will recover some of the energy that the trap might waste. This is a very minor point if the feedwater pump flow is only slightly larger than the steaming rate, and the heat exchanger is entirely optional. I have made this heat exchanger from common brass compression tees, with a 3/8 inch (10mm) diameter feed tube mounted inside a 5/8 inch (15mm) trap discharge line.
There is another method that works as well, and with no moving parts, no electricity, and fully automatic action, but that is another story.
Mounting the Thermodynamic trap on a tee fitting, in parallel with the boiler center "try cock", will prohibit the boiler water level from rising above this point. When the boiler water level is lower than this point, the trap is closed, and no flow of condensate or steam out of the boiler will occur. When the boiler water level rises,the trap goes into action, and discharges excess boiler water, and water level in the boiler cannot rise above this point.
The condensate discharge of the trap is directed back to the hotwell, or back to the feedwater tank, or overboard. A float style trap could also be used, however I have found the thermodynamic traps work perfectly at steam pressured up to 600 PSI (40 Bar). The boiler feed pump must always provide at least 100% of the steaming rate, but all steam plants already have this requirement.
A small counterflow heat exchanger, with pumped feedwater passing to the boiler, and trap discharge flowing in the opposite direction, will recover some of the energy that the trap might waste. This is a very minor point if the feedwater pump flow is only slightly larger than the steaming rate, and the heat exchanger is entirely optional. I have made this heat exchanger from common brass compression tees, with a 3/8 inch (10mm) diameter feed tube mounted inside a 5/8 inch (15mm) trap discharge line.
There is another method that works as well, and with no moving parts, no electricity, and fully automatic action, but that is another story.