换向阀的平面阀板与密封端面通过直接接触实现密封。阀板闭合后，因加工、装配精度低导致密封不严，废气在压力作用下流动，在阀板处形成少许内漏，不通过蓄热体及炉膛焚烧直接排放。同时，阀杆在往复运动中对密封填料造成磨损，使废气通过填料直接泄漏到大气中，发生外漏。

The flat valve plate and sealing end face of the directional valve are sealed through direct contact. After the valve plate is closed, due to low processing and assembly accuracy, the sealing is not tight, and the exhaust gas flows under pressure, forming a small internal leakage at the valve plate. It is not directly discharged through the heat storage body and furnace incineration. At the same time, the valve stem causes wear on the sealing packing during reciprocating motion, causing exhaust gas to directly leak into the atmosphere through the packing, resulting in external leakage.

另外，换向阀内部存在高温烟气，经长期运行后，原阀杆与阀板均存在不同程度的腐蚀损坏。由于原换向阀设计存在上述问题，加之在排放指标、指标更为严格的情况下，即使少量的泄漏也会对排放指标产生很大的影响，因此需要通过改造提高阀门的密封性、耐蚀性和耐用度，使装置能够满足现有工况条件下长期稳定运行的要求。

In addition, there is high-temperature smoke inside the directional valve, and after long-term operation, the original valve stem and valve plate have varying degrees of corrosion damage. Due to the aforementioned issues in the original directional valve design, coupled with stricter emission and environmental indicators, even a small amount of leakage can have a significant impact on the emission indicators. Therefore, it is necessary to improve the sealing, corrosion resistance, and durability of the valve through renovation, so that the installation can meet the requirements of long-term stable operation under existing operating conditions, And ensure that the emitted exhaust gas meets the emission standards of GB31571-2015 Petrochemical Industry Pollutant Emission Standards.

根据长期运行后装置换向阀出现的泄露、损坏等问题，结合故障点的出现位置，可以从以下三个方面对换向阀的结构进行分析，并考虑改进办法：

Based on the leakage and damage of the directional valve after long-term operation, combined with the location of the fault point, the structure of the directional valve can be analyzed from the following three aspects and improvement methods can be considered:

1.阀杆材料及其连接结构换向阀的主要动件是阀杆和圆形阀板，因阀门动作频繁，密封结构及支撑结构负荷较大。加之炉中废气温度较高且有较强的腐蚀性，装置运行一段时间后，阀杆与阀板均发生了一定的磨损与破坏。

1. The main moving parts of the directional valve stem material and its connecting structure are the stem and circular valve plate. Due to frequent valve movements, the sealing structure and supporting structure are heavily loaded. In addition, the exhaust gas in the furnace has a high temperature and strong corrosiveness. After running the device for a period of time, both the valve stem and valve plate have undergone certain wear and damage.

经现场测量、检查发现，阀板与密封面之间存在一定程度的平行度偏差。因此，应对阀板与阀杆采取降低重量、更换材料、增加错动补偿机构等措施使动件拥有更长的使用寿命和更好的密封效果。

Through on-site measurement and inspection, it was found that there is a certain degree of parallelism deviation between the valve plate and the sealing surface. Therefore, measures such as reducing weight, replacing materials, and increasing displacement compensation mechanisms should be taken to ensure that the valve plate and stem have a longer service life and better sealing effect.

2.阀板密封结构原设计中，圆形阀板仅通过与密封面接触时自身发生形变来进行密封。

In the original design of the valve plate sealing structure, the circular valve plate was only sealed by deformation of itself when in contact with the sealing surface.

由于加工精度无法保证，以及长期运行带来的支撑结构磨损，圆形阀板与密封面无法在圆周上所有的位置都能紧密接触。因此，需要对阀板密封结构进行重新设计，来保证长期运行中阀板密封的可靠性。

Due to the inability to guarantee machining accuracy and the wear of the supporting structure caused by long-term operation, the circular valve plate and sealing surface cannot be tightly contacted at all positions on the circumference. Therefore, it is necessary to redesign the valve plate sealing structure to ensure the reliability of valve plate sealing during long-term operation.

3.阀杆密封结构及支撑结构原设计中，阀杆的密封组件采用的是填料式密封，由于换向阀的动作频率非常高（每60-180s动作1次）使得此处密封填料的损耗非常快。

In the original design of the valve stem sealing structure and support structure, the sealing component of the valve stem used a packing type seal. Due to the high frequency of action of the directional valve (once every 60-180 seconds), the loss of the sealing packing here is very fast.

阀杆的支撑结构是在内外两侧对称布置的由三个橡胶轮组成的支撑轴承。

The supporting structure of the valve stem is a supporting bearing composed of three rubber wheels symmetrically arranged on both inner and outer sides.

拆除支撑轴承后，发现滑轮表面包胶因长期使用表面已发生变形；滑轮的转轴因长期与轴套干磨，已严重磨损；部分滑轮已无法正常转动。

After removing the supporting bearings, it was found that the surface of the pulley surface had undergone permanent deformation due to long-term use; The shaft of the pulley has been severely worn due to long-term dry wear with the shaft sleeve; Some pulleys are unable to rotate properly.

此外，经检查发现，支撑轴承虽然有一定的调心功能，但当阀杆两端同时采用此结构时，很难保证阀杆与密封函的同心度，从而加剧了填料的磨损。填料磨损后，废气在此处发生泄漏。因此，需要对阀杆的密封结构与支撑机构进行重新设计，以达到更好的阀杆密封效果与更长的使用寿命。

In addition, upon inspection, it was found that although the supporting bearing has a certain centering function, it is difficult to ensure the concentricity between the valve stem and the sealing box when this structure is used at both ends of the valve stem, which exacerbates the wear of the packing. After the packing is worn out, exhaust gas leaks here. Therefore, it is necessary to redesign the sealing structure and support mechanism of the valve stem to achieve better valve stem sealing effect and longer service life.

一、阀杆及其连接构件

1、 Valve stem and its connecting components

如某涂布行业企业，一台55000Nm3/h处理量的RTO，在换向阀设计中的几个取值，如阀杆为直径60mm的实心杆，材质为不锈钢，阀板为直径 1300mm，厚3-10mm 的圆形板，材质同为不锈钢。在运行一段时间后，阀杆与阀板表面均出现了严重的腐蚀与磨损。考虑到长期运行时的设备工况，需要同时满足力学性能、表面硬度、耐腐蚀性三方面要求，因此理想的替代材料有调制钢不锈钢或其他合金钢。

For example, in the design of a directional valve for a coating industry enterprise with a processing capacity of 55000Nm3/h RTO, several values are taken. For example, the valve stem is a solid rod with a diameter of 60mm, made of stainless steel, and the valve plate is a circular plate with a diameter of 1300mm and a thickness of 3-10mm, all made of stainless steel. After running for a period of time, both the valve stem and valve plate surfaces showed severe corrosion and wear. Considering the long-term operating conditions of the equipment, it is necessary to meet the requirements of mechanical properties, surface hardness, and corrosion resistance simultaneously. Therefore, ideal alternative materials include modulated steel, stainless steel, or other alloy steels.

根据现场的使用经验，选用直径63mm，厚10mm的不锈钢钢管作为替代阀杆材料。阀板的材料也选用不锈钢，直径不变，厚度增加。

Based on on-site usage experience, stainless steel pipes with a diameter of 63mm and a thickness of 10mm are selected as alternative valve stem materials. The material of the valve plate is also stainless steel, with the diameter unchanged and the thickness increased.

阀杆自身的磨损与阀杆支撑轴承的磨损均会导致活塞杆与阀杆的同心度偏差进一步加大。改进的办法是在过渡头与活塞杆之间增加一个浮动接头。浮动接头允许两侧连接杆发生偏心滑动和球面滑动，它能够对活塞杆与阀杆之间的偏心量进行补偿，使得换向阀在长期使用过程中稳定地运行，降低RTO换向阀运行隐患。

The wear of the valve stem itself and the wear of the valve stem support bearings will further increase the concentricity deviation between the piston rod and the valve stem. The improvement method is to add a floating joint between the transition head and the piston rod. The floating joint allows for eccentric and spherical sliding of the connecting rods on both sides. It can compensate for the eccentricity between the piston rod and the valve stem, allowing the directional valve to operate stably and efficiently during long-term use, reducing the safety hazards of RTO directional valve operation.

二、阀板密封构件

2、 Valve plate sealing components

1.改进后的阀板密封结构在密封面上加工两道密封槽，选用适当的弹性体材料作为密封体；利用密封体的回弹性补偿阀板与密封面之间的平行度偏差。同时，利用两道密封体形成迷宫密封结构，阻止有机废气泄漏，提高RTO处理效率。换向阀高温侧的环境温度可达到300℃甚更高（如部分行业需增加反烧工艺），因此要求密封体材料在高温下具有良好的物理、化学特性稳定性。膨胀石墨的耐温性出色，同时兼具较好的回弹性，非常适用于目的工况。

1. The improved valve plate sealing structure has two sealing grooves machined on the sealing surface, and appropriate elastic material is selected as the sealing body; Utilize the resilience of the sealing body to compensate for the parallelism deviation between the valve plate and the sealing surface. At the same time, two sealing bodies are used to form a labyrinth sealing structure, preventing organic waste gas leakage and improving RTO treatment efficiency. The ambient temperature on the high-temperature side of the directional valve can reach 300 ℃ or even higher (if some industries require the addition of reverse burning technology), so it is required that the sealing material has good physical and chemical stability at high temperatures. Expanded graphite has excellent temperature resistance and good resilience, making it very suitable for target working conditions.

2.改进后的阀板密封结构在密封面上增加集气室，增加压缩空气接口，内部通入正压，以保证换向阀的零泄漏。

2. The improved valve plate sealing structure adds a gas collection chamber on the sealing surface, a compressed air interface, and positive pressure is introduced inside to ensure zero leakage of the directional valve.

三、阀杆支撑构件

3、 Valve stem support components

1.将原结构中的橡胶轮改为40Cr材质的钢轮，提高滑轮在高温烟气条件下的耐用性和耐腐蚀性。

1. Replace the rubber wheels in the original structure with steel wheels made of 40Cr material to improve the durability and corrosion resistance of the pulleys under high temperature flue gas conditions.

2.增加下部两个滑轮的宽度，增大滑轮与阀杆的接触面积，降低滑轮与阀杆之间接触处的滑动摩擦阻力。

2. Increase the width of the lower two pulleys, increase the contact area between the pulleys and the valve stem, and reduce the sliding friction resistance at the contact point between the pulleys and the valve stem.

3.在每个滑轮内部增加一对自润滑轴承，使滑轮的滑动更加顺滑，延长滑轮的使用寿命。

3. Add a pair of self-lubricating bearings inside each pulley to make the sliding of the pulley smoother and extend its service life.

经过我们的研究和探索，根据上述改进措施，换向阀能够满足RTO长期使用的稳定性和重复性，使RTO设备做到满足新标准中的排放要求，达到了预期的改进目的。具体效果总结如下：

After our research and exploration, based on the above improvement measures, the directional valve can meet the stability and repeatability of long-term use of RTO, enabling RTO equipment to meet the emission requirements of the new standards and achieve the expected improvement goals. The specific effects are summarized as follows:

1.更换后的不锈钢阀杆与阀板能够有效抵抗腐蚀并降低阀杆支撑负荷，减少磨损，具有更长的使用寿命。

1. The replaced stainless steel valve stem and valve plate can effectively resist corrosion and reduce the support load of the valve stem, reduce wear, and have a longer service life.

2.作为阀板密封体材料，膨胀石墨在高温下具有良好的热稳定性和良好的回弹率。

As a sealing material for valve plates, expanded graphite has good thermal stability and good rebound rate at high temperatures.

3.改进后的阀杆密封结构能够有效阻隔灰尘；有效阻止RTO运行过程中的有机废气泄漏，并对阀杆提供稳固支撑。改进后的阀杆支撑轴承运转更加顺滑，使用寿命大大增加。

3. The improved valve stem sealing structure can effectively block dust; Effectively prevent organic waste gas leakage during RTO operation and provide stable support for the valve stem. The improved valve stem support bearing operates more smoothly and has a significantly longer service life.

4.改进提高了换向阀的密封性；提高了换向阀运行时的平顺性与可靠性；延长了换向阀的使用寿命。

4. Improved the sealing of the directional valve; Improved the smoothness and reliability of the directional valve during operation; Extending the service life of the directional valve.

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