How is the boiler backpressure calculated?
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Dear teachers, how is the boiler backpressure calculated? Can the back pressure of the boiler be reduced by increasing the height of the chimney? If the back pressure decreases by 1000 Pa, how much higher does the chimney need to be? Thank you!
Refer to the Standard Methods for Design and Calculation of Industrial Boilers – Calculation of Smoke and Air Resistance in Industrial Boilers
You can search for the calculation method for boiler chimneys on Baidu. There are many prerequisites. Reduce back pressure by increasing the height of the chimney. It’s unrealistic. At a smoke exhaust temperature of 150 degrees Celsius, only 3 Pa of pressure is generated per meter. At a smoke exhaust temperature of 400 degrees Celsius, only 7 Pa of pressure is generated per meter. This is just my personal opinion; feel free to keep discussing it. This post was last edited by eddy-8280103 on 2009-2-19 13:39.]
The chimney draft force ΔP = 12.67 × h × (273/T0 – 273/T1), where: h is the height of the chimney in meters; T1 is the absolute temperature of the flue gas in K; T0 is the absolute temperature of the surrounding atmosphere in K. The calculation results show that for flue gas at 200°C, the draft force increases by 45 Pa for every 10-meter increase in chimney height (without taking into account the resistance of the chimney). Therefore, this approach is not practical
The calculation of back pressure is now also largely based on empirical values, taking into account factors such as the furnace chamber, flue ducts, and bends. As for using a chimney to reduce back pressure, it is not feasible; as mentioned above, the chimney itself has frictional losses along its length.
Thank you all for the tips! :handshake