Flue gas exhaust temperature of the heating furnace flue gas recovery system in the atmospheric and vacuum distillation unit
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We are a atmospheric and vacuum distillation unit; during this maintenance period, a new flue gas recovery system was installed, and it has worked very well – the flue gas temperature has dropped from around 270 degrees to around 60 degrees. Currently, there is an excessive amount of condensate in the flue, and water must be drained every 2 hours. The flue suffered corrosion and perforation just a few months after it was put into use. How can this be solved?
This may be caused by dew point corrosion; the temperature can be increased appropriately. Or line the flue to prevent flue corrosion.
This post was last edited by cn2009 on 2019-1-25 at 15:31. It’s concentrated sulfuric acid; the equipment will be damaged very quickly. A bypass should be installed in the air preheater to increase the exhaust temperature of the air preheater. As for how high this temperature should be, it depends on the type of fuel being used; a dew point analysis should be conducted； Or utilize the residual heat from the equipment to preheat the cold air before it enters the air preheater
This post was last edited by FrozenRiver on 2019-1-25 at 20:28. Same as mentioned above; it’s probably caused by dew point corrosion. There are two solutions: 1. Appropriately raise the flue gas temperature； 2. Improve fuels and add flue gas desulfurization facilities, etc. Initially, our unit used a heat pipe preheater; later, it was replaced with a heavy-duty air preheater. Currently, the flue gas temperature is around 124°C, and no significant perforation has occurred
Increase the exhaust temperature so that it is above the corrosion level at the leakage points. The second method is to apply an anti-corrosion lining; however, the effect isn’t very good. The fiberglass lining tends to peel off easily
The response of increasing the flue gas temperature goes against the original intention of recovering heat. It is heresy. We use two methods: 1. The air preheater is made of corrosion-resistant steel. 2. Deep desulfurization of fuel gas.
The exhaust temperature is too low; it is recommended to keep it above 110°
One should not focus solely on waste heat recovery; equipment performance must also be taken into consideration. Generally, it is not recommended that the exhaust temperature from the chimney be lower than 135°C. By the time work stops for equipment maintenance, the amount of money that can be earned from recovering that waste heat will be relatively insignificant
1. Usually, increase the exhaust temperature slightly. 2. When inspectors are on site, appropriately lower the flue gas temperature.
Increase the flue gas temperature. The flue gas temperature should not be this low; such a low temperature leads to corrosion caused by the dew point of the flue gas. It is possible to analyze the dew point of the flue gas based on the characteristics of the fuel, and then raise the flue gas temperature to 10-20 degrees above that dew point temperature℃
The dew point temperature of the flue gas is calculated based on the sulfur dioxide content in it. Generally, the exhaust gas temperature should be about 10 degrees higher than the dew point temperature; a difference of 20 degrees leads to a 1 percentage point decrease in the efficiency of the heating furnace.