The Study On The Heat Recovery Of The Bottom Slag In 300MW Circulating Fluidized Bed Boiler

As the energy situation continues to deteriorate, the resources of the coal increasing scarce, experts and scholars are looking for a variety of effective ways to saving energy and reducing consumption. The consumption of coal in China is mainly used for the thermal power. While China’s thermal power plant coal consumption is larger, but the efficiency of thermal power plants of only 37%. The most part of the energy consumed in the hot slag which the boiler has depleted, and the heat of the slag with no reasonable recycling. To solve this problem, selected a circulating fluidized bed boiler unit as the research object in domestic, and study of its bottom heat slag recycling, and selecting reasonable design scheme to raise the thermal efficiency, so as to reduce the coal consumption, achieve the purpose of energy saving production.In this paper, putting the slag discharged systems of circulating fluidized bed unit as the research object and introducing the characteristic of different type of slag coolers firstly. Combining with the different characteristics of three slag discharged style on circulating fluidized bed boiler, the most suitable slag discharged style for 300 MW circulating fluidized bed boiler is determined finally, and this style which could make the unit operating safely and stably.Secondly, using the method of equivalent heat drop on the study of heat recovery from slag of the boiler. Installing the slag cooler as the equipment to recover the heat of slag on the recycled regenerative system of the unit. Then the local variations of resulting system is analyzed with the method of equivalent heat drop. The slag cooler is seen as a low pressure heater. To design different ways of slag cooler connecting to the recycled regenerative system. And select three different operating conditions, respectively, after the slag cooler connected to the system, the total quantity of heat the slag cooler is recycled, the rate of heat consumption of the unit, the amount of coal consumption, the new steam power was calculated. Compared with pure heat recovery system, the best layout plan of slag cooler makes the unit heat consumption rate and the amount of coal consumption reduced.Finally, exergy is a measure of energy quality standards, and exergy analysis method can reflect the essence of the system energy utilization. Exergy analysis method are applied to the study of slag heat recovery. Based on the data in the field of cold slag are calculated respectively monomer exergy efficiency and system exergy efficiency. Through the MATLAB command to fitting curve, and the exergy efficiency are used as a measure of slag heat utilization. Using parallel selection method as a optimization way to optimize the temperature of the wind and the water out of the slag cooler. In this way to make the slag cooler of monomer exergy efficiency and system efficiency to achieve the best value.