1、凝汽器测试和在 TQNPC下各工况的热力分析摘要凝汽器是核电厂的一个重要辅助系统。整个机组的热力效益就是决定于凝汽器的表现。清洁因素和凝汽器应有的压力是两个最重要的指标。这两个估计参数的定义和推论将在这篇文章中详细的说明和分类。并且凝汽器的各种工况点将会得到分析。海水温度，管路水流速度和海水压力变化速度对机组单元的影响也会被计算出来。然而计算方法简单，但可以为简单的电站提供参考性、指导性意见。关键词：凝汽器；表现测试；各工况；TQNPC；1 简介凝汽器是核电厂的一个重要辅助系统，整个机组的热力效益就是决定于凝汽器的表现。通过比较和分析凝汽器表现内在因素，得出影响凝汽器表现的最主要因素有如下几个
2、：冷却水入口温度，冷却水流量，凝汽器负荷，冷却管污染程度，空气漏入凝汽器量，凝汽器冷却区域。冷却水入口温度和凝汽器热交换区域完全决定于自然环境和设计参数。总的来说，凝汽器冷却区域有明显的边界。冷却水流量能够适合 VWO 工况下的热交换需要，除非循环水泵和循环水系统工作异常，对于运行的凝汽器，凝汽器热力负荷冷却水管的污染程度和漏入凝汽器空气量是影响凝汽器的重要因素。清洁因素和凝汽器位于适当的压力的两个重要的评价指标，但定义和计算方法有一些不同，即意味着，在本文章中，TQNPC 的表现测试数据将用于评价凝汽器的表现，也用于详细说明和解释这两个参数。2 计算式凝汽器的热力平衡方程是（1）（ tKAt
3、KAtWccQmpwp/1ln)(2然后（2）12twt（3）21mlntwst（4）ts凝汽器总体传热系数 K 是一个重要的描述凝汽器表现的参数，它集合各种影响凝汽器表现的因素。在这篇文章中，国际通用的 Heat Transfer Society（HEI）公式将会被使用，如下：（5）mtcHEI103凝汽器清洁因素凝汽器清洁程度是一个描述管道清洁程度的参数，它表明了旧新管子在同样的流速和蒸汽温度下，热交换程度的比例。凝汽器清洁程度是冷却管道清洁程度的平均综合。假设在相同的工作条件下，新管子热交换程度是 Kc，旧管子热交换程度是Kf，故清洁程度定义为如下：Cf=Kf/Kc （6）Hu Hong
4、hua 提出了另外一种算法来定义清洁程度 Cf，如下：（7）fDHEITKfCfD 是在依据 KEI 标准计算 KHEI 的过程中，作为清洁程度。另外，文献5提出清洁程度计算方法。（8）mKt0c是清洁程度， K0 是热交换程度， 是冷却水入口温度修正系数， 是ct m管材和壁厚修正系数。冷却水管清洁程度关系式看似矛盾，其实他们的关系如下。Kf 和 Kc 在 6 式中分别代表了污染了的管子和新管子的传热程度，但他们都是在被污染的情况下做测试得出来的。在公式 7 中，作者提出了清洁程度是测试的传热程度和 KHEI 的比值，然后被修正为 CfD。在公式 8，清洁程度的表达式不同于表达式 7，他是公
5、式 6 的推论，修正系数 CfD 被消除了。故实际上公式 7 和公式 8 是同一种计算方法公式 6.7.8，虽然有着同一种物理意义，但却有着完全不一样的计算方式和表达式。文献4中列出了各种测试中的因素，这些因素影响了传热程度。这些实验数据需要计算更加准确。在中国，我们也称这些数据为国家标准，因此，这些测试数据被用于判断凝汽器清洁程度。下列方程式从这些数据并且结合 HEI 标准得出：（9）20 8.163.097.126VK（10）1t 938tt（11）2m4.5 h方程式 12 由方程式 4 各种情况得出（12）chtthKthV10 1c1*)029.298.(4658.63.然后我们用方
6、程式和实验数据计算出了在 TQNPC 情况下的凝汽器表现，结果如表 1：表 1 凝汽器清洁程度计算结果参数 单位 设计值 PT-01 PT-02管径 mm 25.4 25.4 25.4壁厚 mm 0.65 0.65 0.65海水流速 m/s 1.97 2.02 1.98冷却水进口温度 18.8 18.8 14.9冷却水出口温度 27.8 27.5 23.8清洁程度 0.85 0.82 0.77传热程度 kW/(m2) 2880 2825 2总的传热程度变化 kW/(m2) -54.7 -396.6流速影响 kW/(m2) 34.7 8.2壁厚影响 kW/(m2) 0 0水温影响 kW/(m2)
7、 -1.2 -150.8污染程度影响 kW/(m2) -89.5 -252.9测试的清洁程度和设计值的比例 % 3.1 10.24 凝汽器修正压力我们可以根据 HEI 标准的传热方程式得出以下结论：冷却水温度越高，传热程度越高。循环水流动压力越大，传热程度越高。同理，冷却水管越干净，传热程度越高。反之亦然。当凝汽器表现测试运行时，冷却水温度不太可能刚好与设计值一致（例如20）。冷却水压力也一样不可能刚好与设计值一致。传热程度修正方程可写为如下式子：Kc=KtFvFtFc （13）Fv= （14）TDV（15）t1（16）fTDcCF在上面积是中 Kc 是修正以后的传热程度，Fc 是流动速率修正
8、参数，Ft 是水温修正参数，Fc 是清洁程度修正参数。TQNPC 的凝汽器压力修正参数被上几式计算出来，结果列于表 2 中。可以看出，压力 4.91Kpa,比设计值 4.90Kpa 大，这表明，凝汽器表现差于设计值。5 凝汽器各工况热力表现分析蒸汽凝结温度 ts 在 17 式中由运行实际决定，与之一一对应的饱和压力称为凝汽器压力。（17）tt1s基于不同海水温度的凝汽器压力曲线可以用式子 1.2.3.4.17 计算出来，通过这几个式子的迭代计算，可以将结果画于图 1 中。图 1 不同海水温度下的凝汽器压力曲线可以看出，在同一凝汽器传热区域、结构形式、热负荷、冷却水容积流量、真空密封和冷却水管清
9、洁程度下，冷却水温升，凝汽器压力升值。当温度连续不到地增加，凝汽器压力增加地越来越快。根据运行参数如海水温度，海水容积流量和凝汽器设计参数，我们也能根据以上方程得到一定的冷却水管堵塞率下，凝汽器压力和机组做功输出的关系曲线，结果如图 2 和图 3.图 2 基于不同冷却水管堵塞率的凝汽器压力图 3 不同冷却水管堵塞率下的机组输出功率从图 2 和图 3 可以看出在堵塞率为 2%时，凝汽器压力是 4.93Kpa.可以总结出：管子堵塞率低时对机组输出无明显影响。测试工况下的海水容积流量比设计值大，故海水容积流量对机组输出改变率也被分析了出来，如图 4.图 4 不同海水容积流量下的机组输出改变率海水质量
10、流量是 39441.2KG/s，比设计值 36833.5KG/s 大 6.5%。根据轻微增加的输出方法6.7,如果质量流量降至设计值，机组输出减少 1.7MW，如果海水流量增加 10%，机组输出可增加 1.9MW。基于海水泵曲线和泵功，可以计算出，可节约泵功 380.7KW，但机组输出降低了 1.7MW，故测试工况下机组经济效益比设计容积流量工况下的好。6结论凝汽器是核电厂的一个重要辅助系统，整个机组的热力效益很大程度上决定于凝汽器表现，清洁程度和凝汽器压力是两个重要的评价指标。这两个评价指标的定义和推论会在此文章中得以详细解释和分类说明。凝汽器在各种工况下的表现也会得到分析。海水温度、冷却水
11、管堵塞率和海水容积流量对机组输出影响被计算出来。计算方法是简单的，可以为简单的电站提供参考性、指导性意见。参考文献1 The Peoples Republic of China National Development and Reform Commission. “DL/T1078-2007 Performance Test Code on Steam Surface Condensers operation,” Bei-jing, 2007.2 The American Society of Mechanical Engineers, “ASME PTC12.2 1998, Perform
12、ance Test Code on Steam Surface Condensers,” New York.1998.H. H. Hu, X. P. Wang and Y. Yang, “Test and Correction Method of Condenser Performance in Large Generating Unit,”3 Power Station Power Station Auxiliaries, No. 12, 2004, pp. 13-174 Heat Exchange Institute, “Standards for Steam Surface Conden
13、sers,” 9th Edition.Ohio.1995.5 The Peoples Republic of China National Development and Reform Commission, “DL/T932-2005 Guide of Op-eration and Maintenance for the Condenser and Vacuum System of Power Plant,” Beijing, 2005.6 D. M. Xu, Y. Ke and S. Y. Wang Shiyong, “The General Calculation Method and
14、Its Application of Turbine Back Pressure,” Thermal Power Engineering, Vol. 25, No. 6, 2010, pp. 605-6847 Q. S. Zhao, D. B. Deng and Y. Liu, “The Accurate Ther-mal Performance History Files of Wet Steam Turbine in Nuclear Power Plant,” 2012 Asia-Pacific Power and En-ergy Engineering Conference, shang
15、hai, 28-31 March 2012.原文The Condenser Performance Test and Thermal Performance Analysis of Variable Conditions in TQNPCQingsen Zhao1, Debing Deng1, Yong Liu1, Wei Chen1, Jiayong Wang1, Jun Xiang2, Song Hu21The Mal Power Technology Center, Suzhou Nuclear Power Research Institute, Suzhou, China2State
16、Key Laboratory of Coal Combustion, Huazhong University of Science andTechnology, Wuhan,China Email: , Received March, 2013ABSTRACTCondenser is one of the important auxiliary equipments in nuclear power plants. The thermal efficiency of the entire unit was depended on the condenser performance. Clean
17、liness factor and condenser corrected pressure are the two most important evaluation indexes. The definition and derivation of these two evaluation indexes were elaborated and clari-fied in this paper. And the condenser performance at variable conditions was analyzed. The seawater temperature, pipe
18、plugging rate and seawater volume rate effect on unit output was calculated. The calculation method was simple, which can provide reference guidance for similar power plant.Keywords: Condenser; Performance Test; Variable Condition; TQNPC1. IntroductionCondenser is one of the important auxiliary equi
19、pments in nuclear power plants. The thermal efficiency of the entire unit was mostly depended on the condenser per-formance.The main factors affect the operation of the condenser performance in the following areas, through the analysis and comparison of the condenser performance impact factors. For
20、example: cooling water inlet temperature, cooling water flow rate, condenser thermal load, cooling tubes fouling, the amount of air leaking into the con-denser, condenser cooling area. The cooling water inlet temperature and the condenser heat transfer area were depended entirely on the natural cond
21、itions and design value. In general, condenser cooling area had sufficient margin. The cooling water flow rate could meet the need of the heat transfer in VWO condition, unless the circu-lating pump and circulating water system failure. For the operating condenser, the condenser thermal load, the co
22、oling tubes fouling and the amount of air leaking into the condenser were the key factors to influence perform-ance of condenser.Cleanliness factor and condenser corrected pressure are the two most important evaluation indexes. But the definitions and calculation methods had some different meaning,
23、in this paper, the performance test data of TQNPC was used to evaluate the condenser performance, and to elaborate and clear these two definitions.The FormulasThe thermal balance equation of condenser was:Q Wc p (t w 2 - t w1 ) Wc p t KAtm (1) KA ln(1 t / t)andt t w 2 tw1 (2)tw 2 tw1tm (3)ts tw1lnt
24、ts w 2 t t s tw2 (4)The condenser overall heat transfer coefficient K was important parameter to description condenser perform-ance, which combined a variety of factors effected con-denser performance. In this paper, the international Heat Transfer Society (HEI) formula was used, as followsKHEI K0 c
25、 t 1m (5)3. Condenser Cleanliness CoefficientsThe condenser cleanliness coefficients was one of the parameters to characterize the tube dirt degree, which indicated that the ratio of heat transfer coefficient about the old and the new tubes at the same flow rates and steam temperature. The condenser
26、 cleanliness coefficient was the average of all the cooling pipe cleanliness coef-ficients 1.Assuming the same operating conditions, the heat transfer coefficient of the new cooling pipes was Kc, the old cooling pipes of the hheat transfer coefficien was Kf.so cleanliness coefficient as follows2: Cf
27、=Kf/Kc （6）Hu Honghua 3 proposed another algorithm of Cf, as follows（7）fDHEITCKfCfD was the selected cleanliness coefficient during the calculation of KHEI according the HEI standard 4. In addition, the reference 5 proposed the following cleaning coefficient calculation method. （8）mKt0cC was cleanlin
28、ess coefficient, K0 was heat transfer coef-ficient, t was the cooling water inlet temperature correc-tion factor, m was Pipe material and tube wall thickness correction factor. These cooling pipe cleaning coefficient formulas seemed contradict, their relationship was as follows.Kf and Kc in formula
29、6 was heat transfer coefficients of fouling pipes and new pipes，respectively. But they were measured by the fouling resistance test. In formula 7, the author proposed that the cleanliness coefficient was the ratio of test transfer coefficient and KHEI, and was cor-rected with CfD. In formula 8, the
30、expression of cleanli-ness coefficient was different with formula 7, it was de-duced by formula 6, and corrected CfD was eliminated. So formulas 7 and 8, actually were a calculation method. The formula 6 and 7 and 8, although the same physical meaning, but has a completely different calculation and
31、methods of expression.Reference 4 lists various components test data which impacted the heat transfer coefficient. These experimen-tal data had proven to be more accurately. In China we also refer to these data in national standard. Therefore, these test data was used to judge the condenser cleanli-
32、ness coefficient.The following equations were obtained by fitting these test data in HEI standard. （9）20 8.163.097.126VK（10）1t 938tt（11）2m4.5 hThe equation 12 was obtained by the differentiation of equation 4.（12）chtthKthV10 1c1*)029.298.(4658.63.Then we calculated the condenser performance of TQNPC
33、 using the equation 12 and test data. The results were shown in Table 1.We can get the values of the pipes cleanliness using the above equations, and we can also get the amount of influence of factors on heat transfer coefficient. The condenser cleanliness coefficient was 0.82 in PT-01, which reduce
34、d the rate of 3.12% compared with the de-sign value. In PT-02 the condenser cleanliness coeffi-cient was dropped to 0.77, which reduced the rate of 10.23% compared with the design value4. The Condenser Correction Pressure We can get the following conclusions according to the condenser heat transfer
35、equation in HEI standard 4. The higher the cooling temperature, the higher the heat trans-fer coefficient; larger the cycle water volume flow, the higher the heat transfer coefficient. In the same, the cleaner the cooling water pipes, the higher the heat transfer coefficient, and vice versa. The coo
36、ling water temperature was not likely to be exactly the design value (eg. 20) when the condenser performance test carried on. Neither was the cooling wa-ter volume flow. The heat transfer coefficient correction equation was as follows:Kc=KtFvFtFc （13）Fv= （14）TDV参数 单位 设计值 PT-01 PT-02管径 mm 25.4 25.4 2
37、5.4壁厚 mm 0.65 0.65 0.65海水流速 m/s 1.97 2.02 1.98冷却水进口温度 18.8 18.8 14.9冷却水出口温度 27.8 27.5 23.8清洁程度 0.85 0.82 0.77传热程度 kW/(m2) 2880 2825 2总的传热程度变化 kW/(m2) -54.7 -396.6流速影响 kW/(m2 34.7 8.2)壁厚影响 kW/(m2) 0 0水温影响 kW/(m2) -1.2 -150.8污染程度影响 kW/(m2) -89.5 -252.9测试的清洁程度和设计值的比例 % 3.1 10.2（15）tDF1（16）fTcCIn the ab
38、ove equations, Kc was the corrected heat transfer coefficient, Fc was flow rate corrected factor，Ft was water temperature corrected factor, and Fc was cor-rected factor of cleanliness coefficient. The corrected condenser pressure of TQNPC was cal-culated though the above equations. The results were
39、shown in Table 2. It can be seen that the corrected pres-sure was 4.91kPa, which was larger than the design value 4.90 kPa. It indicated than the condenser performance was worse than the design value. 5. Condenser Thermal Performance Analyses of Variable Conditions The steam condensation temperature
40、 ts were decided by equation 17 in operating condition. The saturation pres-sure corresponding to the steam condensation tempera-ture was condenser pressure. （17）tt1sThe condenser pressure curve under different sea wa-ter temperature can be obtained using the above equation 1,2,3,4, 17 and through i
41、terative calculation, as shown in Figure 1. It can be seen than at the same condenser heat transfer area, structure form, heat load, cooling water volume flow, vacuum tightness and cooling pipe cleanliness co-efficient, the cooling water inlet temperature rise, then the condenser pressure increases.
42、 As the temperature increases continually, the condenser pressure increases faster and faster. According to the operating parameters of seawater temperature, seawater volume flow and condenser design data, we can also get the relation curve of condenserpressure and unit output with the cooling pipes
43、 plugging rate using the above equations. The results were shown in Figures 2 and 3.Figure 1. Condenser pressure curve under different seawater temperatureFigure 2. The condenser pressure under different pipe plugging rate.Figure 3. The unit output under different pipe plugging rate. From the Figure
44、s 2 and 3, it can be seen that the cor-rected condenser pressure was 4.93 kPa when the pipe plugging rate was 2%. It can be concluded that there was no obvious impact on the unit output when the pipe plugging rate was low. The seawater volume flow at test conditions was larger than design values. So
45、 the impact of seawater volume flow on unit power was also analyzed. The calculation results were shown in Figure 4. The seawater mass flow was 39441.2 kg/s, which was 6.5% larger than the design value 36833.5 kg/s. Ac cord-ing to the slight increase of output method 6,7, if the seawater mass flow d
46、ecrease to design value, the unit output decrease 1.7 MW. If the seawater flow increase 10%, and the unit output can improved 1.9 MW.Based on the seawater pump curve and the pump power, it calculated that the pump power could save 380.7 kW, but the unit output decrease 1.7 MW, so the unit economic e
47、fficiency at test condition was better than the design volume flow.6. Conclusions Condenser is one of the important auxiliary equipments in nuclear power plants. The thermal efficiency of the entire unit was mostly depended on the condenser performance. Cleanliness factor and condenser corrected pre
48、ssure are the two most important evaluation indexes. The definition and derivation of these two evaluation indexes were elaborated and clarified in this paper. And the condenser performance at variable conditions was analyzed. The seawater temperature, pipe plugging rate and seawater volume rate effect on unit output were calculated. The calculation method was simple, which could provide reference guidance for similar power plantREFERENCES8 The Peoples Republic of China National Development and Reform Commission. “DL/T1078-2007 Performance Test Code
