浅析汽轮机轴封系统经济性定量计算及分析中英文.doc

/ /浅析汽轮机轴封系统经济性定量计算及分析中英文汽轮机轴封系统的作用是防止蒸汽从轴封漏出至大气，并防止空气进入汽轮机和凝汽器。汽轮机轴封用汽一般来源于正压轴封的漏汽，同时向负压轴封提供轴封用汽，当轴封用汽量不足时，由辅助蒸汽补充。由于轴封系统用汽不仅有工质损失，还伴随着热量损失，会使机组的经济性降低。因此，定量分析轴封用汽及其回收利用系统对于提高机组经济性具有十分重要的意义。Turbine shaft seal systems role is to prevent the steam from the shaft seal leakage to the atmosphere, and prevent air from entering the steam turbine and condenser. Leakage steam general Yu Zheng pressure seal of turbine shaft seal, and seal with steam to the negative pressure seal, shaft seal steam consumption is insufficient, supplemented by the auxiliary steam. Because the shaft seal system of steam is not only the medium loss, accompanied by loss of heat, will make the economy of units to reduce. Therefore, quantitative analysis of steam and the significance of recycling system of shaft seal is very important to improve unit economy has.某电厂机组轴封系统介绍The shaft seal system of a power plant某电厂百万机组汽轮机是由上海汽轮机厂和德国SIEMENS联合设计制造的四缸四排汽超超临界凝汽式汽轮机。西门子技术汽轮机对轴封蒸汽温度有严格要求，当转子温度在300以上时，轴封汽温要求在2803202。在高负荷范围内，从高压缸轴封漏汽至轴封蒸汽母管的蒸汽温度可能使低压轴封的温度超过允许值。为了降低低压轴封蒸汽温度，辅汽供轴封蒸汽调节阀开启，注入相对冷的外部蒸汽进入轴封蒸汽母管。同时为了维持轴封母管压力，轴封溢流调节阀开启，溢流蒸汽直接进入凝汽器。Steam turbine in a power plant unit is made by millions of joint design of Shanghai steam turbine plant and the German SIEMENS four cylinder four exhaust ultra supercritical steam turbine. Siemens technology for steam turbine has strict requirements on the shaft seal steam temperature, when the temperature over 300 , shaft seal steam temperature is 280 320 2. In the high load range, steam temperature from the high pressure cylinder shaft gland leakage to the shaft seal steam pipe may cause low seal temperature exceeds the allowed value. In order to reduce the low pressure shaft seal steam temperature, auxiliary steam seal steam regulating valve for opening, injecting steam relatively cold into the seal steam pipe. At the same time, in order to maintain the seal pipe pressure, overflow valve seal open, overflow direct steam entering the condenser. 轴封系统经济性定量计算及分析由于轴封用汽不再进入汽轮机作功，属于带热量工质离开了系统；轴封溢流蒸汽回收利用，属于系统内部的热量和工质的利用，对于以上热经济性问题，可以借助等效热降法进行局部定量分析。轴封用汽经济性定量分析Economic quantitative calculation and analysis of shaft seal system for shaft seal steam into the turbine belongs to no longer work, with the heat medium left system; seal overflow steam recycling, utilization of heat and fluid belongs to the system, the thermal economic problem, can have the aid of equivalent heat drop method for partial quantitative analysis. The quantitative analysis using the economic gland根据上述分析，在高负荷范围内，需要辅助蒸汽来冷却轴封蒸汽来保证低压轴封蒸汽不超温。根据轴封系统设计，机组正常运行时辅助蒸汽有两路汽源：冷段再热蒸汽和四段抽汽。Based on the above analysis, in the high load range, need the auxiliary cooling steam seal steam to ensure low pressure steam gland without excess temperature. According to the shaft seal system design, the unit normal operation of auxiliary steam has two steam source: cold reheat steam and extraction four. 若辅汽来自冷段再热蒸汽，则损失的功为：式中，为辅汽用汽份额；使循环吸热量减少：系统经济性相对变化：若辅汽来自四段抽汽，则损失的功为：系统经济性相对变化：由此得到热耗率相对变化：以辅汽供轴封1t/h蒸汽为例，由此得到辅汽用汽分别来源于冷段再热蒸汽和四段抽汽时热经济性比较结果。If the auxiliary steam from cold reheat steam, the loss of power: type, auxiliary steam steam share; the circulation heat reduction: relative changes in economic system: if the auxiliary steam from extraction four, the loss of power : the relative change of economic system: the heat consumption rate of relative change : the auxiliary steam for steam seal 1t/h as an example, the auxiliary steam steam respectively from the cold reheat steam and extraction four thermal economy comparison results.由表2可知，在相同用汽量的情况下，辅汽来自冷段再热蒸汽时，热耗率增加值要高于四段抽汽。因此，正常运行时应采用四段抽汽供辅汽的运行方式。轴封溢流蒸汽回收利用经济性定量分析Table 2 shows, in the same steam amount, auxiliary steam from cold reheat steam, the heat consumption rate increased to more than four stage extraction steam. Therefore, during normal operation should adopt the operation mode of extraction four for the auxiliary steam. Economic analysis of quantitative seal overflow steam recycling按原有设计，轴封溢流蒸汽直接进入到了凝汽器，如果能将这部分热量回收利用，不仅能增加装置效率，同时也能够降低凝汽器的热负荷。根据等效热降法，若将轴封溢流蒸汽回收利用于加热器，将排挤段回热抽汽，从而获得的回收功为：式中：为轴封溢流蒸汽回收利用份额；为轴封溢流蒸汽焓kJ/kg；为段回热抽汽焓kJ/kg；为段回热抽汽效率；局部变动的热经济性相对变化：由此得到热耗率相对变化：根据现场试验数据，满负荷工况下，轴封溢流蒸汽压力约115kPa(a)，压力均大于7段抽汽压力和8段抽汽压力。图2对比了轴封溢流蒸汽分别回收利用于7号低加和8号低加时的热耗率减少量，结果显示轴封溢流蒸汽回收利用于7号低加的热经济性明显好于其回收利用于8号低加。According to the original design, shaft seal overflow steam directly into the condenser, if this part of the heat recovery and utilization, not only can increase the system efficiency, but also can reduce the heat load of condenser. Based on the equivalent heat drop method, if the seal overflow steam recycling on the heater, will crowd out section of regenerative steam, power recovery so as to obtain: Type: Seal overflow steam recycling share for shaft seal overflow; steam enthalpy of kJ/kg; for the period of regenerative steam enthalpy of kJ/kg; for the period of regenerative steam relative change of efficiency; thermal economy of local changes: the heat consumption rate of relative change: Based on the field test data, full load condition, the steam pressure seal overflow of about 115kPa ( a ), pressure is greater than 7 stage extraction steam pressure and 8 stage extraction steam pressure. Fig. 2 Comparison of the shaft seal steam recycling overflow respectively in 7 and 8, low and low heat consumption rate reduce the amount of overtime, results show that the thermal economy of the shaft seal overflow steam recycling in 7 low and was better than that of its recovery in 8 low and.改造后的热经济性评价Thermal economic evaluation after transformation机组在大修期间将轴封溢流蒸汽回收到了7号低加，为评价此次回收利用的经济性效果，记录了轴封溢流到7号调节阀关闭前后相关参数的变化，如表3所示。该统计时间段内，负荷维持1000MW稳定，同时辅汽供轴封调阀开度维持10.3%不变。在轴封溢流蒸汽至7号低加调节阀关闭后，7号低加温升降低了0.3，疏水温度降低了0.3，由此推算进入7号低加的轴封溢流蒸汽为6.15t/h左右。根据图2，回收6.15t/h轴封溢流蒸汽到7号低加，使热耗率减少约4.131kJ/kWh，供电煤耗减少约0.16g/kWh.The unit will seal overflow steam recovery to 7 lower during overhaul, the economic evaluation for the effect of the recycling, recorded the changes seal overflow to the 7 regulating valve before and after the closure of the relevant parameters, such as shown in table 3. The statistical period, load to maintain 1000MW stability, while the auxiliary steam for seal regulating valve opening remained unchanged at 10.3%. In the seal overflow steam to 7 lower adjusting valve closed, 7 low temperature lifting low 0.3 , hydrophobic temperature 0.3 lower, which projected into the 7 lower seal overflow steam for about 6.15t/h. According to figure 2, recovery of 6.15t/h seal overflow steam to 7 lower, the heat consumption rate is reduced by about 4.131kJ/kWh, power consumption is reduced by about 0.16g/kWh.本文利用等效热降法对某百万超超临界机组的轴封系统进行了定量热经济性分析，得到了以下结论：在相同轴封用汽量的情况下，供轴封的辅汽来自四段抽汽比其来自冷段再热蒸汽更为经济；轴封溢流蒸汽回收利用于7号低加的热经济性明显好于其回收利用于8号低加；回收6.15t/h轴封溢流蒸汽到7号低加，使热耗率减少约4.131kJ/kWh，供电煤耗减少约0.16g/kWh.以上分析结果对汽轮机经济运行和节能技术改造提供