【作者】 赵宁；

【导师】 张春发；

【作者基本信息】 华北电力大学（河北） ， 热能工程， 2008， 博士

【摘要】 目前我国能源供需日趋紧张、用电需求量日益增大,用电结构也发生了很大的变化,因此机组经常处于变工况乃至深度变工况运行中。与此同时电力行业节能问题正受到越来越多的关注。因此需要对汽轮机进行详细的变工况计算从而得出在工况变化时汽轮机的运行经济性,进而达到优化运行实现节能降耗的目的,但目前机组变工况理论明显滞后,已经成为影响电厂安全经济运行、实现现代化管理的主要制约因素之一。汽轮机变工况计算的基础是级变工况,而级变工况难点是末级变工况计算。用统一的解析函数进行级的变工况计算是不可能的。本文首先研究了级喷嘴压比和整级压比与级流量之间的关系,根据背压降低时喷嘴先达到临界状态还是动叶先达到临界状态,将级的类型分为Ⅰ、Ⅱ和0三种类型的级并推导出级流型判别准则,并研究在实用变工况范围内蒸汽轮机级的类型与级的设计几何参数之间的关系。分别求出各个类型级和级组的临界压力比,结合一个级组内各级在某一工况下的压力比,便可以判断级组内有无一级达到临界。本文在变工况计算中用整级彭台门系数来代替喷嘴彭台门系数以简化运算,并证明在正常运行工况时,此改变对效率的影响很小,在工程计算中完全可以适用。验证了加入了级临界压力比的改进型Flugle公式的正确性,即其不仅能够应用于中间级的计算,而且可以应用于末几级的计算,乃至末级的计算(非超临界工况),而且误差很小,精度较高。通过应用改进的Flugle公式对汽轮机中间级进行顺序变工况核算,在计算排汽焓时以汽轮机末级抽汽或次末级抽汽(过热蒸汽状态)为计算起点,根据初始假定的末级流量和现场实际的末级前热力状态和背压,用汽轮机变工况流型判别准则,判别级的流型,然后从末级前参数开始顺序进行一次级的变工况核算,得到新的排汽焓和排汽干度,最后算得机组的排汽焓。最后本文通过对火电厂热力系统变工况运行条件下系统各种运行环境参数应达值的确定,结合火电厂热经济性状态方程,确定出机组在不同运行条件下的主蒸汽压力的最优值。代入到顺序变工况计算中就可以得到各级的参数应达值。并将上述所有计算方法应用到SIS系统的性能计算和能损分析中,对热力系统的主要热经济性指标进行实时的在线计算,对影响机组热经济性的运行参数进行连续监督和分析,实时诊断机组的运行能损的分布情况,定量计算这些偏差所引起的能量损失并分析导致这些损失的原因,使机组经济运行。更多还原

【Abstract】 At present, with the demand of the energy has become more and more tensional, the demand of the electricity is increasing, and the contribution to the electricity has also been changed, the steam turbine unit is often in non-designed condition, even more in the condition which is far away from the designed condition. Meanwhile, the issue on the saving-energy in the power industry has been paid more and more attention. Therefore, the varying condition of the steam turbine should be calculated carefully in order that the operating economy of the steam turbine is gotten in the change of the condition in order to optimizing the operation which also can save energy and lower the energy consumption. However, the lag of the theory on the varying condition of the unit has become one of the main restricting factors of affecting the economical operation of the safety of the power plant and realizing the modern management.The basis of calculation of varying behavior of steam turbine is stage varying behavior. It is impossible to calculate the varying condition of the stage with the unified analytic function. First, the relation of the nozzle pressure ratio、the stage pressure ratio and the stage flow was studied, and the stage can be dividedⅠ、Ⅱand 0 type stage with that the nuzzle reached critical state first or the blade reaches critical state first in the condition of stage initial parameter remains the same and stage back pressure lowers gradually. And the relation of the type of the stage and the design geometric parameter of the stage was studied in utility varying condition range, further more, the stage critical pressure ratio and the stage group critical pressure ratio can be got, then we can judg whether there is a critical stage inside the stage group by the stage pressure ratio of the stage group.In this paper, the nozzle PENGTAIMEN coefficient was substituted by the stage PENGTAIMEN coefficient in the varying condition calculation for simplifying the calculation. That was not influence the efficiency of the steam turbine nearly, it was wholly appliance in project calculation. The correctness of the Flugle formula using the stage critical pressure ratio was verified in this paper, we can find that the formula not only can be used in the intermediate stage, but also can be used in the final stage of the steam turbine (not supercritical condition). And the calculation error was very tiny; the calculation accuracy was very high.The sequence varying condition calculation of the intermediate stage can be made with the improved Flugle formula. As for the calculation of the exhaust enthalpy, we give a sequential varying condition calculation that starts with steam extraction of the final stage or the second final stage (superheated steam condition). According to the initially assumed final stage flow, and the thermodynamic parameters before the final stage, also the backpressure, we can distinguish the flow patterns of the stage by a discriminant criteria. Then we can conduct a stage varying condition calculation of primary stage in sequence from the front final stage parameter, so the new exhaust steam enthalpy and the exhaust steam dryness can be got. So the precise exhaust enthalpy can be got easily.Finally, in this paper, the optimizing initial steam pressure of the unit can be gotten in the different operating condition, through fixing the operating target value of operating parameter of thermodynamic system in the varying condition in the power plant, and combining the thermo-economy state equation, and putting it to the sequence varying condition calculation to get the operating target value of the parameter of all levels. The calculating way mentioned above also can be applied into the performance calculation and the analysis of the energy consumption of SIS, through which the main economy indexes of thermodynamic system can be calculated on line, and the operating parameter of affecting the thermo-economy of unit can be supervised and analyzed continuously. The distribution of the loss of energy of the unit can be diagnosed on-line, and we calculate the loss of energy and analyses the cause of that, it will make the steam turbine operated economically.更多还原