Research On Boiler's Temperature Regulation And Overall Performance Of 1000MW Double Reheat Ultra- Supercritical Power Plant

The double reheat ultra-supercritical technology is one of the main development directions for coal-fired power plants to further improve power generation efficiency.Compared with primary reheat units,the structure of double reheat ultra-supercritical units is more complicated and the regulation and operation is more strict.Energy distribution is more complicated and its temperature control is more difficult.Therefore,it is necessary to conduct in-depth systematic research on the temperature regulation method and unit performance of the double reheat unit.In this paper,two different types of 1000 MW double reheat ultra-supercritical units are taken as the main research objects,and the temperature regulation methods of the two are studied and analyzed according to the field operation experimental data.At the same time,based on the exergy analysis method,the exergy loss and from the perspective of efficiency,the boiler performance and overall performance of different types of units were compared and analyzed to reveal the thermodynamic perfection of different types of double reheat ultrasupercritical unit boilers under different temperature regulation methods and the overall energy utilization and transformation of the unit..According to the temperature regulation method of different types of 1000 MW double reheat ultra-supercritical units,the research on the actual operating characteristics of the boilers found that the vertical and horizontal swing angles of the burner nozzles in the SB boiler changed the main steam temperature and the reheat steam temperature.All of them will have an impact.When the main burner is oscillating vertically,the change of boiler steam temperature is the most sensitive;the amount of flue gas recirculation in HB boiler is increased,which is beneficial to the increase of steam temperature and boiler performance,and the horizontal swing angle of flue gas recirculation spout when steam temperature changes are most sensitive.The burner swings and adjusts temperature,has high sensitivity and simple operation,but needs to be adjusted with the use of the tail flue gas baffle;the flue gas recirculation has a large temperature regulation range and good effect,but it is necessary to consider the problem that the reheater tube wall is easy to overheat.And the difficulty and cost of operation will increase.Based on the constructed exergy analysis model and method,the performance of different types of 1000 MW double reheat ultra-supercritical boilers under different temperature regulation methods shows that the vertical swing angle of the burner will affect the performance of the boiler.The vertical angle of the main burner is 80%.When the vertical swing angle of 80% and SOFA is between 50% and 70%,the SB boiler has the best temperature regulation effect,the minimum exergy loss,the highest exergy efficiency and the best performance.Changing the horizontal angle of the burnout or flue gas recirculation nozzles can increase the energy utilization of the boiler.Compared with different types of 1000 MW double reheat ultra-supercritical boilers,HB boilers have high energy utilization.Flue gas recirculation can improve the thermodynamic perfection of boilers,but it will increase the difficulty of operation.Further analysis of the overall performance of the HB unit found that the unit enthalpy loss is mainly concentrated in the boiler system,mainly from fuel combustion and heat transfer surface heat transfer,in the regenerative heater #1,#3 with high pressure and#7 with low pressure exergy losses are large,and the sensitivity study shows that the main steam and reheat steam parameters have a significant impact on the performance of the unit.Through comparative analysis of the performance of different types of 1000 MW double reheat ultrasupercritical units,it is shown that the main sources of exergy losses of different types of units are fuel combustion,furnace heat transfer and steam turbine work,but the combustion of flue gas recirculation is adopted.The method can more effectively utilize the energy generated by the boiler,and the overall performance of the unit is better.