Talking about the operation of the waste heat boiler

　　As we all know, the boiler that uses the sensible heat of exhaust gas and the waste heat after incineration of the waste as the heat source is called a waste heat boiler, also known as a waste heat boiler. Therefore, we advocate the development of waste heat utilization, energy conservation and emission reduction, which play a good role in protecting energy and increasing the quality of the living environment. In the design of a waste heat boiler, how to reasonably divide the temperature zone is the basis for rationally arranging its heating surface and limiting the use of waste heat. Given its inlet flue temperature, there are two requirements for the exhaust temperature. One is to limit the exhaust temperature, requiring the exhaust temperature to be within a reasonable range; the other is not to limit the exhaust temperature, requiring Use waste heat to the limit.

　　In either case, for the utilization of medium and low temperature waste heat, the narrow temperature difference directly affects its evaporation and the layout of the heating surface. The narrow point temperature difference is also called the nodal temperature difference, which is the small temperature difference between the flue gas at the outlet of the evaporator and the heated saturated water vapor during the heat exchange process. With the change of the narrow point temperature difference, its relative total heat exchange area, relative evaporation capacity, and relative flue gas temperature also change accordingly. When the narrow point temperature difference decreases, its exhaust gas temperature will drop, the amount of flue gas waste heat recovery will increase, and the steam output will increase accordingly, which corresponds to a high waste heat boiler thermal efficiency, but the average heat transfer temperature difference will decrease accordingly. , It will increase its heat exchange area and manufacturing costs. Therefore, when choosing a narrow temperature difference, attention should be paid to economic rationality. Because the exhaust gas temperature is restricted by various conditions such as heat transfer, environment, users, etc., in the calculation process of boiler evaporation, there are two methods for calculating evaporation, that is, calculating the evaporation according to the exhaust temperature and calculating the evaporation according to the narrow point.

　　Calculating the evaporation capacity according to the narrow point is to select the small narrow point temperature difference under economic conditions, and the obtained evaporation capacity is the evaporation capacity of the boiler under economic conditions, and the exhaust gas temperature is the exhaust gas temperature under economic conditions. , The use of narrow points to calculate boiler evaporation and exhaust gas temperature is more stable, more accurate and more economical. When the narrow point temperature difference decreases, due to the larger increase in the heat exchange area of ​​the waste heat boiler, the boiler investment cost will increase a lot; but when the narrow point temperature difference is larger than the design point value, the total investment cost and unit heat recovery cost However, the degree of reduction has to be moderated. From the perspective of investment cost and waste heat utilization efficiency, there is a problem of how to reasonably select the narrow point temperature difference of the waste heat boiler. The narrow point temperature difference is an important basis for confirming the heat exchange area, evaporation capacity, and exhaust gas temperature of the waste heat boiler. For this reason, we must consider the narrow point temperature difference when designing the waste heat boiler, and confirm that a reasonable narrow point temperature difference is a prerequisite for reasonable economic skills. At present, the general range of the narrow point temperature difference is 10-20℃, and the low temperature can reach 7℃.