600MW机组凝结水含氧量超标的危害和预防,600MW units condensate oxygen content of the hazards of excessive and prevention,Condensate of dissolved oxygen is one of the main indicators of the chemical supervision ，600MW units condensate dissolved oxygen content higher dissolved oxygen ，because a lot of excessive or long - term failure, It will accelerate the condensate pipeline and equipment corrosion,and make condensat contains iron oxide ions , causing galvanic corrosion，Heat transfer deterioration , until the occurrence of boiler tube , and crew safety and economic operation of units.,凝结水溶解氧是化学监督的主要指标之一,特别是600M机组对凝结水溶解氧含量有更高的要求.因为溶解氧大幅度超标或长期不合格，会加速凝结水管道及设备的腐蚀，并使凝结水中含有氧化铁离子，引起电化腐蚀，使传热恶化，直至发生锅炉爆管，严重威胁机组安全、经济运行。,凝结水溶解氧存在的原因：,1.真空系统不严密，进入凝结器的漏量大；2.有溶解氧含量较高的补水或回收水大量进入凝结器；,Condensate of dissolved oxygen reasons for the existence :,1.vacuum system is not tight ,a lot of air to enter the condenser ; 2.higher levels of dissolved oxygen replenish water or recycled water enter the condenser,针对上述原因，从以下方面进行防范和处理：,For the above reasons , from the following aspects prevent and treatment :,运行中真空系统的查漏以氦介质检漏为主。方法是在运行真空泵出口布置氦介质检漏装置，利用专用的喷枪在所有负压系统的阀门、法兰、管道焊缝、排大气口等处喷氦气，然后观察1-2分钟，如果检测点有泄露，检漏装置就会发出报警，泄漏量越大，报警数值就越大，即使很微量的泄露，也能检测出来。并且这种方法灵活，不受时间限制，消除漏点后随时可以检测溶解氧的变化。缺点是工作量大，耗时长。,1.真空系统的查漏,1.vacuum system leak,running vacuum system leak is mainly helium medium Leak . running vacuum pump outlet layout the helium medium leak detection devices , with a dedicated gun spray helium to all negative pressure system valves, flanges , pipe welds and exclusive atmosphere mouth etc, then observed for 1-2 minutes , if it detects some leakage ,and the leak detection device will alarm , the greater the amount of leakage , the greater the alarm value , even a very small amount of leakage can be detected . the method is flexible , without time limit , after eliminate the leak ，at any time the change of dissolved oxygen can be detected . The drawback is the large amount of work , time-consuming long,灌水查漏。方法是：凝结器灌水至末级叶片下100mm高度，然后查漏处理。需要注意的是灌水过程中有专人监视水位，防止水位过高进入汽轮机。但这种方法必须停机后才能进行。,Condenser irrigation to the last stage blades under 100mm height , then leak to handle . Should be noted that there is someone to monitor the water level,in order to prevent the high water level enter the turbine in the irrigation process . However , this method must be shut down after .,The purpose of irrigation leak,2.凝结水泵系统的改造,Condensate pump seal water instead of two : closed water and condensate pump outlet self-sealing water,凝结水泵密封水水源改为两路：闭式水和凝结泵出口自密封水。凝结水泵进口滤网顶部增加排空气管路,2.Condensate pump system transformation,Increase exhaust air line at the top of condensate pump inlet filter,3.对加入凝结水的回收水进行处理,热力系统内漏进入凝结器内的非正常疏水。该疏水进入凝结器导致热负荷增加，汽阻增大，造成凝结器内空气分压的提高，从而凝结水的含氧量增加。因此查出阀门泄露并及时更换内泄阀门是一项长期的工作,低加等热力系统的正常疏水。方法是维持低加正常水位，防止无水位运行或常开危急疏水运行，另外加强对疏水系统阀门法兰的检漏，尽可能减少空气的漏人,3 . Join condensate recycled water treatment,normal drain low pressure heater of thermal system . the method is to maintain the the low pressure heater normal level , to prevent the no level or long-time open a critical drain valve running , in addition to strengthening the valve flange leak detection of drain system , in order to minimize air leakage .the abnormal drain leakage of thermal system leak into condenser . the drain entering condenser that heat load increases, and the steam resistance increases, resulte to raise the branch pressure of air in the condenser , and raise the water oxygen content of condenser, therefore detect valve leaks and timely replacement the leaking valve is a long-standing work .,4凝补水系统的改造,凝补水是除盐水。除盐水的含氧量很高，需要进行深度除氧。一般的说，凝补水直接补入热井，没有利用凝结器的真空除氧作用，除盐水补水口应接在6.9米的7、8号低加侧，经充分雾化后增大凝补水与排汽的接触面积，从而减少凝结水的含氧量。,4. Condensate replenishment system transformation,Condensate replenishment is demineralized water , the oxygen content of demineralizing water is very high , it need depth to remove oxygn . Condensate replenishment directly into the hot well , no make full use vacuum removalling oxygn role of condenser, replenishment point of demineralizing water should pick the 6.9 m 7,8 low pressure heater side , after fully atomized to increase contacting area of condensate replenishment with exhaust , thereby reduce the oxygen content of the condensate .,案例分析:,上海吴泾发电有限责任公司2*300MW机组运行中凝结水溶解氧时有超标(标准控制30ug/L),2010年12月份#1机组进行B级检修时发现:给水泵、省煤器腐蚀严重，同时发现锅炉内部也有一定结垢和腐蚀。经过排查发现:凝结泵自密封阀门开度小于10%时凝补水会进入凝结水中，导致凝结水含氧量升高。另外排查发现:真空系统漏点多集中在凝结器管阀和凝结水泵入口管阀等处，空气的漏入导致凝结水含氧量升高。上述问题解决后凝结水溶解氧合格率达到100%，平均化验值达到21ug/L.,Case Study:,Shanghai Wujing Power Company 2 * 300MW unit :during operation it often can be find excessive by dissolved oxygen of condensate ( standard control 30ug / L). when # 1 unit B type overhaul : severe corrosion for the feed water pumps and economizer , at the same time find some scale and corrosion inside the boiler .,After investigation found :the condensate replenishment enter condensate when graduation of condensate Pump self - sealing valve is less than 10%, result to increase oxygen content of condensate,