The Study Of Low Reheater Temperature And Capacity-increasing For Reheater Of300MW Boiler

With the increasing pressure of energy-saving and environmental protection, the power plants have taken many effective means of renovation to improve market competitiveness. One of the relatively effective energy-saving measures used by many power plants presently to improve economic benefits and reduce heat consumption of units is to renovate the through-flow of steam turbine. Renovating the through-flow of steam turbine will not only improve the high pressure cylinder efficiency, but also reduce the exhaust temperature and change the matching between the exhaust temperature of high pressure cylinder and the heating capacity of the reheater, and then leading to the low reheater temperature which affects the energy-saving effect of the through-flow renovation of steam turbine, at the same time creates pressure to the boiler operation.The problem of reheater temperature long-term low and unable to achieve the rated temperature, which caused by the through-flow renovation of steam turbine in certain300MW boiler, is investigated in this paper. Through analyzing the adjustment test data of reheater temperature, the influence factors of reheater temperature are concluded and the reasons resulting in the lower reheater temperature are summarized, which is the bigger deviation between reheater temperature and the original design of boiler. In this case, the boiler reheater system mainly includes wall-type reheater, intermediate temperature reheater, high temperature reheater. According to different position of increasing heating surface, three kinds of reconstruction plan was put forward in this paper, after considering various factors comprehensively, the scheme of conducting capacity-increasing toward intermediate temperature reheater heating surface was finally chosen. Then, the checking thermal calculation for the reconstruction plan was conducted, which was completed basing on the former Soviet union thermal calculation standard in1973, combined with the relatively new furnace outlet smoke temperature calculation method and three points warehouse rotary air preheater calculation method and computer programming. Finally, the performance tests for the reconstructing boiler were conducted and the situation of reheater temperature and the boiler thermal efficiency were measured and calculated in this paper, the results showed that the reconstruction improved the reheater temperature effectively without reducing the boiler thermal efficiency, thoroughly solved the problem of low reheater temperature occurred in the operation and maximize the efficiency of the through-flow renovation of steam turbine. The successful reconstruction of the example in this paper has some reference value for other boilers which meet the similar problems.