Regarding the issue of heat loss in boilers
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I have some questions regarding the heat losses of boilers. Please advise as follows: 1. The chemical incomplete combustion loss q3 – taking layer-fired chain boilers as an example, the recommended values in the \"Methods for Designing and Calculating Industrial Boilers\" are 0.5~2 for bituminous coal and 0.5~1 for anthracite. The same applies to reciprocating grate boilers. Does a higher volatile content in the fuel result in a larger value for q3? 2. The mechanical incomplete combustion loss q4: Again, taking the layer-fired chain boiler as an example, the recommended values in the \"Design and Calculation Methods for Industrial Boilers\" are 8–12 for three types of bituminous coal, and 10–15 for anthracite. Does a higher volatility content of the fuel result in a lower value of q4? For the existing corn straw briquettes, the fuel composition is as follows: Carbon Cy % 42.75, Hydrogen Hy % 3.82, Oxygen Oy % 37.86, Nitrogen Ny % 0.73, Sulfur Sy % 0.12, Ash Ay % 6.9, Moisture Wy % 7.82, Volatile matter Vy % 70.7. The lower heating value Qdwy is 3739.67 Kcal/Kg. When performing thermal calculations, I use values of 3 for q3 and 6 for q4. Are these values reasonable? What should be the most reasonable value? I look forward to your guidance.
When performing thermal calculations, I use 3 for q3 and 6 for q4. Are these values reasonable? What should be the most reasonable value? I look forward to your guidance. ============= I’d venture to say that corn straw has a relatively high volatile content; the higher the volatile content, the easier it is to initiate combustion. The loss due to incomplete mechanical combustion is much smaller, definitely far less than that of coal. Take Q4 as 6; it seems about right. As for the losses due to incomplete chemical combustion, it depends on the choice of excess air coefficient and the residence time of the flue gases in the furnace; for biomass combustion, I don’t think these values are very high. Setting q3 at 3 seems a bit high to me. Lacking experience, it’s purely speculative; please point out any mistakes.
According to what’s said on the second floor, purely in terms of counterbalance efficiency, is the thermal efficiency higher when burning straw rather than coal?
Based on comprehensive thermodynamic calculations, the thermal efficiency of straw boilers is higher than that of coal-fired boilers, with chain grate boilers achieving around 84%.