換向閥的平面閥板與密封端面通過直接接觸實現(xiàn)密封。閥板閉合后，因加工、裝配精度低導致密封不嚴，廢氣在壓力作用下流動，在閥板處形成少許內(nèi)漏，不通過蓄熱體及爐膛焚燒直接排放。同時，閥桿在往復運動中對密封填料造成磨損，使廢氣通過填料直接泄漏到大氣中，發(fā)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，換向閥內(nèi)部存在高溫煙氣，經(jīng)長期運行后，原閥桿與閥板均存在不同程度的腐蝕損壞。由于原換向閥設計存在上述問題，加之在排放指標、指標更為嚴格的情況下，即使少量的泄漏也會對排放指標產(chǎn)生很大的影響，因此需要通過改造提高閥門的密封性、耐蝕性和耐用度，使裝置能夠滿足現(xiàn)有工況條件下長期穩(wěn)定運行的要求。

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.

根據(jù)長期運行后裝置換向閥出現(xiàn)的泄露、損壞等問題，結(jié)合故障點的出現(xiàn)位置，可以從以下三個方面對換向閥的結(jié)構進行分析，并考慮改進辦法：

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.閥桿材料及其連接結(jié)構換向閥的主要動件是閥桿和圓形閥板，因閥門動作頻繁，密封結(jié)構及支撐結(jié)構負荷較大。加之爐中廢氣溫度較高且有較強的腐蝕性，裝置運行一段時間后，閥桿與閥板均發(fā)生了一定的磨損與破壞。

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.

經(jīng)現(xiàn)場測量、檢查發(fā)現(xiàn)，閥板與密封面之間存在一定程度的平行度偏差。因此，應對閥板與閥桿采取降低重量、更換材料、增加錯動補償機構等措施使動件擁有更長的使用壽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.閥板密封結(jié)構原設計中，圓形閥板僅通過與密封面接觸時自身發(fā)生形變來進行密封。

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.

由于加工精度無法保證，以及長期運行帶來的支撐結(jié)構磨損，圓形閥板與密封面無法在圓周上所有的位置都能緊密接觸。因此，需要對閥板密封結(jié)構進行重新設計，來保證長期運行中閥板密封的可靠性。

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.閥桿密封結(jié)構及支撐結(jié)構原設計中，閥桿的密封組件采用的是填料式密封，由于換向閥的動作頻率非常高（每60-180s動作1次）使得此處密封填料的損耗非?？?。

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.

閥桿的支撐結(jié)構是在內(nèi)外兩側(cè)對稱布置的由三個橡膠輪組成的支撐軸承。

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

拆除支撐軸承后，發(fā)現(xiàn)滑輪表面包膠因長期使用表面已發(fā)生變形；滑輪的轉(zhuǎn)軸因長期與軸套干磨，已嚴重磨損；部分滑輪已無法正常轉(zhuǎn)動。

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，經(jīng)檢查發(fā)現(xiàn)，支撐軸承雖然有一定的調(diào)心功能，但當閥桿兩端同時采用此結(jié)構時，很難保證閥桿與密封函的同心度，從而加劇了填料的磨損。填料磨損后，廢氣在此處發(fā)生泄漏。因此，需要對閥桿的密封結(jié)構與支撐機構進行重新設計，以達到更好的閥桿密封效果與更長的使用壽命。

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、閥桿及其連接構件

1、 Valve stem and its connecting components

如某涂布行業(yè)企業(yè)，一臺55000Nm3/h處理量的RTO，在換向閥設計中的幾個取值，如閥桿為直徑60mm的實心桿，材質(zhì)為不銹鋼，閥板為直徑 1300mm，厚3-10mm 的圓形板，材質(zhì)同為不銹鋼。在運行一段時間后，閥桿與閥板表面均出現(xiàn)了嚴重的腐蝕與磨損。考慮到長期運行時的設備工況，需要同時滿足力學性能、表面硬度、耐腐蝕性三方面要求，因此理想的替代材料有調(diào)制鋼不銹鋼或其他合金鋼。

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.

根據(jù)現(xiàn)場的使用經(jīng)驗，選用直徑63mm，厚10mm的不銹鋼鋼管作為替代閥桿材料。閥板的材料也選用不銹鋼，直徑不變，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.

閥桿自身的磨損與閥桿支撐軸承的磨損均會導致活塞桿與閥桿的同心度偏差進一步加大。改進的辦法是在過渡頭與活塞桿之間增加一個浮動接頭。浮動接頭允許兩側(cè)連接桿發(fā)生偏心滑動和球面滑動，它能夠?qū)钊麠U與閥桿之間的偏心量進行補償，使得換向閥在長期使用過程中穩(wěn)定地運行，降低RTO換向閥運行隱患。

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、閥板密封構件

2、 Valve plate sealing components

1.改進后的閥板密封結(jié)構在密封面上加工兩道密封槽，選用適當?shù)膹椥泽w材料作為密封體；利用密封體的回彈性補償閥板與密封面之間的平行度偏差。同時，利用兩道密封體形成迷宮密封結(jié)構，阻止有機廢氣泄漏，提高RTO處理效率。換向閥高溫側(cè)的環(huán)境溫度可達到300℃甚更高（如部分行業(yè)需增加反燒工藝），因此要求密封體材料在高溫下具有良好的物理、化學特性穩(wěn)定性。膨脹石墨的耐溫性出色，同時兼具較好的回彈性，非常適用于目的工況。

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.改進后的閥板密封結(jié)構在密封面上增加集氣室，增加壓縮空氣接口，內(nèi)部通入正壓，以保證換向閥的零泄漏。

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、閥桿支撐構件

3、 Valve stem support components

1.將原結(jié)構中的橡膠輪改為40Cr材質(zhì)的鋼輪，提高滑輪在高溫煙氣條件下的耐用性和耐腐蝕性。

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.增加下部兩個滑輪的寬度，增大滑輪與閥桿的接觸面積，降低滑輪與閥桿之間接觸處的滑動摩擦阻力。

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.在每個滑輪內(nèi)部增加一對自潤滑軸承，使滑輪的滑動更加順滑，延長滑輪的使用壽命。

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

經(jīng)過我們的研究和探索，根據(jù)上述改進措施，換向閥能夠滿足RTO長期使用的穩(wěn)定性和重復性，使RTO設備做到滿足新標準中的排放要求，達到了預期的改進目的。具體效果總結(jié)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.更換后的不銹鋼閥桿與閥板能夠有效抵抗腐蝕并降低閥桿支撐負荷，減少磨損，具有更長的使用壽命。

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.作為閥板密封體材料，膨脹石墨在高溫下具有良好的熱穩(wěn)定性和良好的回彈率。

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

3.改進后的閥桿密封結(jié)構能夠有效阻隔灰塵；有效阻止RTO運行過程中的有機廢氣泄漏，并對閥桿提供穩(wěn)固支撐。改進后的閥桿支撐軸承運轉(zhuǎn)更加順滑，使用壽命大大增加。

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.改進提高了換向閥的密封性；提高了換向閥運行時的平順性與可靠性；延長了換向閥的使用壽命。

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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