How to deal with and prevent corrosion and scaling in the air preheaters of petrochemical heating furnaces?
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How to deal with and prevent corrosion and scaling in the air preheaters of petrochemical heating furnaces? With the continuous advancement of energy-saving efforts, there are increasing demands for lower flue gas temperatures in tubular furnaces. However, severe low-temperature dew point corrosion often occurs on the heat exchange surfaces of waste heat recovery equipment such as air preheaters and waste heat boilers; within less than a year of operation, these surfaces can become severely corroded and perforated, preventing the tubular furnace from functioning properly. It can be said that low-temperature dew point corrosion has become the main obstacle to reducing the flue gas temperature of tubular furnaces and improving thermal efficiency.
Generally speaking, to prevent dew point corrosion, it is necessary to maintain an appropriate exhaust gas temperature; however, too high an exhaust gas temperature can reduce the thermal efficiency of the heating furnace. Let’s take this device as an example to discuss it. This is a reforming unit equipped with two air preheating systems: one for cylindrical furnaces and one for square furnaces. Unlike others, the cylinder furnace air preheater is equipped with a combustion heater that uses flue gas to heat the fuel gas; the temperature of the heated fuel gas is around 260 degrees Celsius. This gas then enters the corrosion inhibitor reaction reactor, where, in simple terms, the fuel gas is desulfurized and dechlorinated before being put to use again. For square furnaces, steam generators and air preheaters are used, allowing a theoretical thermal efficiency of 95%; the exhaust gas temperature at the outlet of the preheater is also around 80 degrees Celsius