Application of heat pipe heat exchanger in petrochemical industry
The main point of this solution is to use a spiral tube air preheater in the inlet section of the flue gas in the high temperature zone and a heat pipe air preheater in the low temperature zone. Spiral trough tube air preheater has simple structure, heat transfer coefficient is 30% higher than common air preheater, can withstand higher temperature, and can work stably in 450 °C flue gas for a long time, and the cost is low. Since there is no problem of acid corrosion in the high temperature zone, placing the spiral preheater in the high temperature section will not cause the risk of perforation and leakage due to acid corrosion. In the low temperature stage, using a heat pipe air preheater, the heat pipe can be used to adjust the wall temperature characteristics and then increase the wall temperature of the heating surface, so as to avoid the acid dew point to ensure the safety of the heating surface.
This solution gives full play to the advantages of the two types of air preheater, the spiral groove tube and the heat tube, and avoids the disadvantages, so satisfactory results can be obtained. The solution has the advantages of light weight, low cost, high safety and reliability, simple operation and adjustment. In the starting conditions, the maximum operating temperature of the heat pipe is only 215 °C, within its safe use.
In order to ensure the reliability of winter operation, a preheater is installed at the air inlet of the heat pipe preheater. By increasing the inlet air temperature, the operating temperature of the heating surface is increased and condensation is avoided.