How to deal with the issue of excessive flue gas emission temperature in the waste heat boiler used for blowing air?
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Our company uses briquette gas generation, and we have an air blowing recovery system in place. However, the temperature of the flue gas is always above the specified limit; the required range is 120–150, while the actual temperature is usually above 170. The oxygen content in the flue gas is relatively normal, ranging between 5% and 6%. The exhaust fan is run at full capacity, and the blower is set to level 5 out of 6. I would like to ask for advice on how to address this issue
Control peroxide level； And does scaling affect heat transfer?
This estimate is due to insufficient heat exchange. Scaling can have a significant impact on heat transfer, either due to insufficient design margin.
“The process parameter is 120–150 ». What kind of fuel is used? Is corrosion caused by dew point a concern? ?
We use briquette gas generation; the gas used for combustion contains a small amount of make-up air: 5% CO, 2% H2, 0.8% CH4, 15% CO2, 0.5% O2, and 74.7% N2. There is also vent gas with 56.2% H2, 12.4% CH4, 30.4% N2 + AR. I suspect that scaling or the accumulation of ash might be the cause!
By reducing the oxygen content, it is possible to control the outlet temperature effectively. Generally, the oxygen content at the outlet of the exhaust fan for such gases is kept between 2-3%. This not only helps to save fuel but also enables better control of the outlet temperature. After all, with less flue gas, the temperature at the outlet of the exhaust fan will definitely drop after heat exchange. However, the temperature should not be too low, as too low a temperature can lead to the formation of acids when nitrogen oxides, sulfides, and other substances combine with condensed water, thereby causing corrosion of the equipment.