原文：
火电厂锅炉给水泵最小流量再循环调节阀，简称再循环阀或最小流量阀，安装在给水泵出口管道的支管上，接入除氧器。给水泵的作用是将除氧器中的水送往锅炉，运行中为防止其产生过热和汽蚀，要求在任何情况下都必须有一个最基本的流量，也就是给水泵的最小流量。当锅炉给水需要量很小或不需要流量时，就会打开再循环阀，使一部分高压给水再回流到除氧器，以保证给水泵的安全运行。 给水泵再循环阀前后的压差，近似于给水泵的进出口压差，该压差为全厂{zd0}，致使该阀阀内极易产生空化汽蚀，工作环境极为恶劣。大型机组例如超临界机组，采用的是直流锅炉，要求再循环阀做到大小可以调节，而不是开-关两位式调节阀。所以，大型机组给水泵再循环阀是火电厂{zg}端的流体控制组元， 对其设计、加工和选材等，都有着极高的要求。我们国家新近建设的大型火电机组，尤其是超临界和超超临界机组，给水泵的再循环阀几乎全部采用进口产品。 国外产品中美国Copes-Vulcan公司的给水泵再循环阀，简称CV阀、C/V阀或C-V阀，以较高的质量和新颖的软密封阀座等赢得了用户的青睐，近些年来在国内不少电厂获得了应用。但长时间运行后，CV阀的检修和维护，也就成了电厂普遍关心的问题了。 2.问题、原因 大唐三门峡华阳电厂600MW超临界机组使用的便是CV阀，在高压差运行环境下，其阀座、阀芯以及节流套等，被冲刷汽蚀得十分严重，不但起不到关断的效果，而且已经xx失去了流量调节的功能。他们解体了一个阀门，分析认为阀门失效的原因为： （1）阀内出现了空化汽蚀； （2）冲刷严重。一是国内水处理技术要求不严，难以保证给水品质，水中存在悬浮颗粒；二是管阀安装检修以及与阀门连接的设备在检修过程中，为了赶工期等原因，检验程序和施工工艺相对简单，很难做到无杂物颗粒，常见的如细小焊渣、毛线、金属颗粒等，这些对软密封阀座、阀芯和阀套等有极大的损害。 3.处理方案 面对煤价上涨造成的效益下滑，CV阀的这些问题，确实使电厂感到xx。考虑到费用和供货周期，电厂更趋向于维修而不是更换。电厂的要求主要是：(1)能解决问题；(2)检修停机有期限，解决问题的周期要短；(3)费用不能太高。2009年初，根据三门峡华阳电厂的要求，我西安秦申公司提出了如下解决方案： （1）对CV阀进行技术改造，即不再购置新阀； （2）改造后的新阀仍使用原来的执行机构，以节省费用； （3）改造后的新阀仍使用原来的阀体，这是基于原阀体损坏不严重的事实，节省费用，也便于安装。 （4）仅更换阀内组件。这是由于原阀的阀内组件损坏严重，已无法修复。 （5）采购原品备件，价格昂贵且供货周期不能满足要求；国内也无法采购到CV阀座使用的软密封材料，故采用我公司专利技术和设计思想，对阀内组件重新设计和制造，新阀内组件与原阀体配套，符合原安装要求。 （6）不降低原调节阀的性能参数、调节的灵活性等，关断严密。 4.实施方案 （1）工艺技术措施： a.使用秦申公司的专利技术——加工新式迷宫型节流套； b.加工新多级迷宫式平衡阀芯； c.新制严密关断的硬密封阀座； d.结构上保留原阀门的选择——低进高出，以方便工程实施。 （2）解决“关断严密”的方法： a.锥型硬密封，确保关断比压，实现V级泄漏标准； b.选材充分考虑耐冲刷要求，选用440B高级进口材料阀内组件； c.阀内组件的热处理工艺，确保在高硬度（HRC70左右）的同时，又具有较好的韧性； d.采用组合密封技术，使关断“线”不直接受冲刷； e.多级迷宫型节流，避免阀内空化汽蚀的发生。 （3）解决“调节灵活”的方法： a.采用平衡型结构，阀芯不受阀门前后高压差的影响，xx了不平衡力； b.调整阀杆直径，减小低进高出时的不平衡力； c.采用新型柔性石墨加镍丝填料，减小摩擦。 改造后的给水泵再循环阀，2009年3月投入运行，结果表明此次改造非常成功，得到了三门峡华阳电厂的强烈认可。 5结束语 在CV阀基础上改造的给水泵再循环阀，在三门峡华阳电厂投入运行半年后，该厂又委托我公司改造了同样的两套CV阀，运行结果依然非常成功。随后，我公司针对这项改造技术进行了进一步的完善，形成了第二代更加成熟的改造技术，并在陕西华电蒲城电厂等多家电厂的CV阀改造项目中获得了验证。在以后的发展过程中，我们将努力使我们西安秦申的这项技术能为更多的电厂排忧解难。

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译文：
Boiler feed pump minimum flow recirculation control valve, referred to as the minimum flow recirculation valve or valves, pumps installed in the export pipeline to the branch, the access deaerator. The role is to pump the water sent to the deaerator boiler operation to prevent overheating and cavitation of their produce, required in any case must have a minimum flow, that is, the minimum flow to the pump. When the boiler feed water flow rate requirement is small or do not, they will open the recirculation valve, so that part of the high-pressure water return flow to the deaerator to ensure the safe operation of a pump. Before and after the recirculation valve to the pump pressure, similar to the pump the pressure difference, the maximum pressure for the whole plant, causing the valve cavitation within the cavitation easily, extremely poor working conditions. Large units such as supercritical unit, using the boiler to require recirculation valve size can be adjusted, not - off the two-type regulating valve. Therefore, the large unit to pump recirculation valve is the most high-end power plant fluid control element, its design, processing and selection of materials, etc., all have very high requirements. New construction in our country large thermal power units, in particular, super-critical and ultra supercritical unit, to pump recirculation valve is almost all imported products. Foreign products in the United States Copes-Vulcan Inc. to pump recirculation valve, referred to as CV valve, C / V valve or valve CV to high quality and innovative soft-sealing valve seat and so won the favor of users, in recent years in Many domestic plants received application. But after a long run, CV valve repair and maintenance plant will become a question of general interest. 2. The problem, because Datang Sanmenxia Huayang 600MW supercritical power plant is the CV valve unit used in the pressure differential operating environment, its seat, spool and cutting sets, etc., are very serious cavitation erosion, not only will not achieve the relevant off effects, and has completely lost the flow control function. They disintegration of a valve, valve failure analysis because: (1) valve cavitation cavitation occurred; (2) severe erosion. First, strict technical requirements of domestic water treatment, is difficult to guarantee water quality, presence of suspended particles in water; second control valve connected with the valve installation and maintenance of equipment in the repair process, in order to catch up schedule and other factors, testing procedures and the relative construction technology Simple, it is difficult to achieve without debris particle, such as the small common welding slag, wool, metal particles, these soft sealing seat, spool and valve cover and other great damage. 3. Treatment options Benefits resulting from the face of rising coal price drop, CV valve of these issues, do so plant a headache. Taking into account the costs and supply cycle power plant also tends to replace rather than repair. Power requirements are: (1) to solve the problem; (2) maintenance of a period of downtime, problem-solving cycle is shorter; (3) costs can not be too high. Early 2009, according to Sanmenxia Huayang Power's request, I propose the following West An Qinshen Company solution: (1) transformation of the CV valve, that is no longer purchase a new valve; (2) After transformation, the new valve is still using the original implementation of the agency to save costs; (3) After transformation, the new valve body is still using the original, this is based on the original valve damage was not serious in fact, cost savings, but also easy to install. (4) only to replace the valve components. This is because the original valve of the valve components seriously damaged, beyond repair. (5) raw materials procurement of spare parts, delivery time is expensive and can not meet the requirements; the country will also be unable to purchase the software using the CV valve seat seal material, so using our patented technology and design, redesign of the valve components and manufacturing, the new valve components and the original body matching, consistent with the original installation requirements. (6) does not reduce the original control valve performance parameters, adjusting the flexibility, close off. 4. Implementation Plan (1) technical measures: a. Secretary of the patented technology used Qin Shengong - processing new labyrinth throttle sets; b. processing New multi labyrinth balance spool; c. the new system off the hard tight seal seat; d. the structure of the valve to retain the original choice - low prices, to facilitate the implementation of the project. (2) resolving the "close off" approach: a. cone seal, to ensure than the pressure off, to achieve V-level leakage standards; b. Selection of erosion-resistant requirements fully into account, use 440B valve components advanced imported materials; c. valve components of the heat treatment process to ensure high hardness (HRC70 or so) at the same time, but also has good toughness; d. use of combined sealing technology to turn off "line" not directly affected by erosion; e. multi-level maze-type throttle, to avoid cavitation valve cavitation occurrence. (3) resolving the "accommodative" approach: a. to balance the structure, before and after the pressure differential valve spool from the impact, eliminating the unbalanced force; b. adjust the valve stem diameter, low prices and decreased when the unbalanced force; c. Add new type of flexible graphite packing nickel wire, reducing the friction. After transformation to pump recirculation valve, put into operation in March 2009, the results show that this transformation is successful, the plant has been strongly endorsed Sanmenxia Huayang. 5 Conclusion On the basis of the CV valve to the pump recirculation valve reconstruction in the Sanmenxia Huayang six months after the power plant put into operation, the plant commissioned the transformation of the same company two CV valve, the results are still very successful. Subsequently, the transformation of our technology for further improvement of the formation of a second generation of the transformation of more mature technology, and in Shaanxi, Huadian Power and a number of power plants Pucheng CV valve reconstruction projects were validated. Development process in the future, we will strive to make our West An Qinshen of this technology can solve problems for more power plants.