How to reduce the flue gas temperature in a heating furnace and improve the furnace’s thermal efficiency? ?
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The leader gave a task to make a small adjustment. In the diesel hydrogenation unit, the temperature at the inlet of the reaction furnace is around 240 degrees, while the temperature at the outlet is around 270 degrees. The temperature in the flue is around 220 degrees. The management thinks that this temperature in the flue is too high; is it possible to bring it down to around 180 or 190 degrees? How can the flue gas temperature be reduced further? Thank you for your helpful advice. :)
If the economy permits, it is possible to consider adding forced heat exchange devices such as heat pipe air preheaters to use the waste heat from flue gases to heat the air fed into the furnace, thereby improving thermal efficiency.
This post was last edited by qugd on 2011-3-9 at 11:49. There are various ways to improve thermal efficiency, and the factors that influence it are also complex. Controlling excess oxygen is one way to improve fuel combustion efficiency; at the same time, it is also necessary to improve the combustion conditions of the fuel and enhance insulation measures. Simply reducing the flue gas temperature is not advisable, as too low a flue gas temperature can lead to insufficient negative pressure in the furnace and poor exhaust flow; moreover, condensation of water vapor in the flue gases can cause corrosion. You guys are really amateurs when it comes to this.
The fuel can be adjusted; a fuel with a higher calorific value results in a smaller flame. By properly controlling the opening degree of the flue dampers, the flue temperature can be reduced
Control the oxygen content in the chimney and make use of the waste heat from the exhaust gases; just look at the design of refineries and chemical plants to see this.
There are two types: one is a waste heat boiler, and the other is an air preheater. A waste heat boiler transfers the energy from flue gas to water; the resulting hot water is then fed into the heating system. An air preheater can also be used to preheat the air in the furnace, thereby reducing fuel consumption
I don’t entirely agree with the opinion expressed on the third floor. The level of exhaust gas temperature mainly depends on how much heat is absorbed by the convection chamber from the flue gases exiting the radiation chamber; if more heat is absorbed by the convection chamber, the exhaust gas temperature is lower, and if less heat is absorbed, it is higher. When the heating furnace operates for a long time, ash accumulation on the walls of the convection chamber can reduce heat transfer, thereby increasing the exhaust gas temperature. This has no direct relation to negative pressure. If it is related to negative pressure, it is believed that this is caused by a decrease in the furnace temperature, and in that case the production requirements cannot be met. Currently, to address high flue gas temperatures, waste heat recovery systems are commonly used; heat pipes or heated water are employed to extract heat and warm air or other media in order to reduce the flue gas temperature, which is generally kept between 150 and 170°, with some values being even lower. Dew point corrosion is primarily determined by the sulfur content of the fuel.
Adding a preheater can save fuel.
Flue gas can cause dew point corrosion; the boiling point of concentrated H2SO4 is 304 degrees Celsius, so the temperature shouldn’t be too low