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通用设备阀门的发展与原理

2019-05-28  来自: 泰科菲阀门有限公司 浏览次数:121

阀门是用以控制流体流量、压力和流向的装置。被控制的流体可以是液体、气体、气液混合体或固液混合体。
  
  阀门通常由阀体、阀盖、阀座、启闭件、驱动机构、密封件和紧固件等组成。阀门的控制功能是依靠驱动机构或流体驱使启闭件升降、滑移、旋摆或回转运动以改变流道面积的大小来实现的。
  
  阀门的用途广,它与人们的日常生活有密切的关系,例如自来水管用的水龙头、液化石油气灶用的减压阀都是阀门。阀门也是各种机械设备如内燃机、蒸汽机、压缩机、泵、气压传动装置、液压传动装置、车辆、船舶和飞行器中不可缺少的部件。
  
  公元前两千年前,中国人就在输水管道上使用了竹管和木塞阀,以后又在灌溉渠道上使用水闸,在冶炼用的风箱上使用板式止回阀,在井盐开采方面使用竹管和板式止回阀提取盐水。
  
  随着冶炼技术和水力机械的发展,在欧洲出现了铜制和铅制旋塞阀。随着锅炉的使用,1681年又出现了杠杆重锤式安全阀。1769年瓦特蒸汽机出现以前,旋塞阀和止回阀一直是主要的阀门。
  
  蒸汽机的发明使阀门进入了机械工业领域。在瓦特的蒸汽机上除了使用旋塞阀、安全阀和止回阀外,还使用了蝶阀,用以调节流量。随着蒸汽流量和压力的增大,使用旋塞阀控制蒸汽机的进汽和排汽已不能满足需要,于是出现了滑阀。
  
  1840年前后,相继出现带螺纹阀杆的截止阀,和带梯形螺纹阀杆的楔式闸阀,这是阀门发展中的一次重大突破。这两类阀的出现,不仅满足了当时各种工业对压力、温度不断提高的要求,而且初步满足了对流量调节的要求。此后随着电力工业、石油工业、化学工业和造船工业的发展,各种高中压阀门得到迅速发展。
  
  第二次世界大战后,由于聚合材料、润滑材料、不锈钢和钴基硬质合金的发展,古老的旋塞阀和蝶阀获得了新的应用,球阀和隔膜阀得到迅速发展。截止阀、闸阀和其他阀门品种增加,质量提高。阀门制造业逐渐成为机械工业的一个重要部门。
  
  阀门按使用功能可分为截断阀、调节阀、止回阀、分流阀、安全阀、多用阀六类。
  
  截断阀主要用于截断流体通路,包括截止阀、闸阀、旋塞阀、球阀、蝶阀隔膜阀、夹管阀等;调节阀主要用于调节流体的压力、流量等,包括调节阀、节流阀、减压阀和浮球调节阀等;止回阀用于阻止流体的逆向流动;分流阀用于分配流体的通路去向,或将两相流体分离,包括滑阀、多通阀、疏水阀和排空气阀等;安全阀主要用于保护,防止锅炉、压力容器或管道因超压而破坏;多用阀是具有一种以上功能的阀门,如截止止回阀既能起断流作用又能起止回作用。
  
  工业管道阀门按公称压力又可分为真空阀、低压阀、中压阀、高压阀、超高压阀;阀门按工作温度又可分为常温阀、中温阀、高温阀、低温阀;阀门还可按驱动装置的类型、与管道的联接方式和阀体的使用材料等进行分类。阀门可按各种分类方法单独地或组合地命名,也可按启闭件的结构特征或具体用途命名。
  
  阀门的基本参数是工作压力、工作温度和口径。对于大量使用于工业管道的各种阀门,常用公称压力和公称通径作为基本参数。公称压力是指某种材料的阀门,在规定的温度下,允许承受的大工作压力。公称通径是指阀体与管子联接端部的名义内径。
  
  阀门根据其种类和用途有不同的要求,主要有密封、强度、调节、流通、启闭等性能。在设计和选用阀门时,除了要考虑基本参数和性能外,还要考虑流体的性能,包括流体的相态(气体、液体或含固体颗粒)、腐蚀性、粘度、毒性、易燃易爆性,贵重稀有程度和放射性等。
  
  密封性能和强度性能是一切阀门基本、重要的性能。阀门的密封分内密封和外密封两部分。内密封是阀瓣与阀座之间的密封;外密封是阀杆运动部位与阀盖之间、阀体与阀盖之间和阀体与管道联接部位之间的密封。阀门在使用时不仅要求密封性能好,而且必须保证安全。
  
  如果因密封不好而发生泄漏或因强度不够而使零件破坏,将会造成不同程度的经济损失,如输送有毒、易燃易爆或有强腐蚀性流体,还可能导致严重的安全事故。为了保证阀门的密封和强度,除了必须遵守有关标准规定合理地进行结构设计、确保工艺质量外,还必须正确地选用材料。
  
  通常,低压非腐蚀性流体用的阀门使用铸铁或铸铜;高、中压阀用铸钢或锻钢;高温或高压阀使用合金钢;用于腐蚀性流体的阀门用不锈钢、塑料,耐蚀合金(如铜镍钼合金、钛合金和铅合金等)或用铸铁、铸钢内衬耐蚀材料制造。
  
  通常,低压阀的密封面大多使用黄铜或青铜,高、中压阀大多使用不锈钢,要求较高的高、中压阀或高温阀等使用钴基硬质合金。聚合材料在阀门中已获得应用,如球阀的阀座主要采用聚四氟乙烯塑料,蝶阀的密封圈和隔膜阀的隔膜采用各种橡胶材料。这些材料在可以使用的温度范围内具有比金属的密封性。
  
  随着现代核工业、石油化学工业、电子工业和航天工业的发展,以及流程工艺自动控制和远距离流体输送的发展,促进了现代低温阀、真空阀、核工业用阀和各种调节阀的发展。用于远距离控制和程序控制的阀门驱动装置的应用越来越多。
  
  未来阀门的发展将向扩大产品参数,发展节能、省力和自控阀门,改进结构、采用新材料和新工艺,提高阀门的使用寿命,以及发展专用阀门系列等发面发展,如用于液氧、液氢和液化天然气等的低温阀、真空阀、核工业用阀、安全阀、调节阀、疏水阀和阀门驱动装置等。

    A valve is a device for controlling the flow, pressure, and direction of fluid. The controlled fluid may be a mixture of liquid, gas, liquid or solid.


The valve usually consists of body, cover, seat, opening and closing piece, drive mechanism, seal and fastener, etc. The control function of the valve depends on the drive mechanism or fluid drive the lifting, sliding, swinging or turning motion to change the size of the flow area.


Valve has a wide range of USES. It is closely related to People's Daily life, for example, the faucet of tap water pipe and the pressure reducing valve for LPG stove are all valves. Valve is also an indispensable part of various mechanical equipment such as internal combustion engine, steam engine, compressor, pump, pneumatic drive, hydraulic drive, vehicle, ship and aircraft.


Before 2000 BC, the Chinese people used bamboo tube and plug valve in the water supply pipeline, and later used sluice in the irrigation channel, plate check valve on the air box for smelting, and bamboo tube and plate check valve to extract salt water in well salt mining.


With the development of smelting technology and hydraulic machinery copper and lead plug valves have appeared in Europe. With the use of boilers, a lever and hammer safety valve appeared in 1681. Before the invention of the watt steam engine in 1769, stopcock and check valves were the main valves.


The invention of the steam engine brought the valve into the mechanical industry. In addition to cock, relief and check valves, butterfly valves are used in watt's steam engine to regulate flow. With the increase of steam flow and pressure, the intake and exhaust steam of the steam engine controlled by the cock valve can no longer meet the requirements.


Around 1840, globe valves with threaded stems and wedge-type gate valves with trapezoid threaded stems successively appeared, which was a major breakthrough in valve development. The appearance of these two types of valves not only meets the requirements of continuous improvement of pressure and temperature in various industries at that time, but also initially meets the requirements of flow regulation. Since then, with the development of power industry, petroleum industry, chemical industry and shipbuilding industry, various high pressure valves have been rapidly developed.


After world war ii, as a result of the development of polymeric materials, lubricants, stainless steel and cobalt-based cemented carbides, the old cock and butterfly valves gained new applications, and ball and diaphragm valves developed rapidly. Globe, gate and other valve varieties increased, quality improved. Valve manufacturing has become an important part of the machinery industry.


Valves can be divided into six categories according to the functions of stop valve, regulating valve, check valve, flow valve, safety valve and multi-purpose valve.


Intercepting valve is mainly used to block the flow passage, including globe valve, gate valve, plug valve, ball valve, butterfly valve diaphragm valve, clamping valve, etc. The regulating valve is mainly used to regulate the pressure and flow of the fluid, including regulating valve, throttling valve, reducing valve and floating ball regulating valve. Check valves are used to prevent reverse flow of fluid; The shunt valve is used for distributing the flow passage or separating the two-phase flow, including the slide valve, multi-pass valve, steam trap and air drain valve. The safety valve is mainly used for safety protection to prevent the boiler, pressure vessel or pipeline from being damaged due to overpressure. Multi-purpose valve is a valve with more than one function, such as stop-check valve can both cut off and start the role of check.


The valve of industrial pipeline can be divided into vacuum valve, low-pressure valve, medium-pressure valve, high-pressure valve and ultra-high pressure valve according to the nominal pressure. Valve can be divided into normal temperature valve, medium temperature valve, high temperature valve and low temperature valve. Valves can also be classified according to the type of actuator, connection to the pipe and material used in the body. Valves may be individually or in combination according to various classification methods, or in accordance with the structural features or specific purposes of the closures.


The basic parameters of the valve are working pressure, working temperature and diameter. Nominal pressure and nominal size are used as basic parameters for a wide range of valves used in industrial piping. Nominal pressure is the maximum allowable working pressure of a valve of a certain material at a specified temperature. Nominal diameter refers to the nominal diameter of the valve body and the end of the pipe connection.


Valves have different requirements according to their types and USES, mainly including sealing, strength, regulation, circulation, opening and closing performance. In the design and selection of the valve, in addition to the basic parameters and performance, consideration should be given to the performance of the fluid, including the phase state of the fluid (gas, liquid or solid particles), corrosivity, viscosity, toxicity, flammability and explosibility, degree of precious and rare, radioactivity, etc.


Sealing performance and strength performance are the most basic and important performance of all valves. The sealing of the valve consists of two parts: inner sealing and outer sealing. The inner seal is the seal between the disc and the seat. The outer seal is a seal between the stem movement and the cover, between the body and the cover, and between the body and the pipe connection. The valve should not only be well sealed, but also be safe when used.


Leakage due to poor sealing or damage to parts due to insufficient strength will result in economic losses of varying degrees, such as the delivery of toxic, flammable, explosive or highly corrosive fluids, and may lead to serious safety accidents. In order to ensure the sealing and strength of the valve, in addition to following the relevant standards, the proper design of the structure and the quality of the process must also be properly selected.


Generally, valves for low pressure noncorrosive fluids use cast iron or cast copper; Cast or forged steel for high and medium pressure valves; High temperature or high pressure valve USES alloy steel; Valves used in corrosive fluids are manufactured from stainless steel, plastics, corrosion resistant alloys (such as cupr-ni-mo, titanium and lead alloys) or with cast iron and cast steel lined with corrosion resistant materials.


Generally, the sealing face of low pressure valve USES brass or bronze mostly, high, medium pressure valve USES stainless steel mostly, the demand is higher high, medium pressure valve or high temperature valve USES cobalt base hard alloy. Polymeric materials have been widely used in the valve, such as ball valve seats are mainly made of teflon plastics, butterfly valve sealing ring and diaphragm valve diaphragm are made of various rubber materials. These materials have better tightness than metals in the range of temperatures available.


With the development of modern nuclear industry, petrochemical industry, electronic industry and aerospace industry, as well as the development of automatic control of process technology and long-distance fluid transportation, the development of modern low-temperature valve, vacuum valve, valves for nuclear industry and various regulating valves has been promoted. Applications of valve actuators for remote control and program control are increasing.


Future valve parameters to expand the development of products, development of energy saving, energy saving and automatic control valve, to improve structure, using new materials and new technology, improve the service life of the valve, and the development of special valve series against the development, such as used in the low temperature of liquid oxygen and liquid hydrogen and liquefied natural gas valve, vacuum valve, the nuclear industry with valve, relief valve, regulating valve, drain valve and valve actuator, etc.

关键词: 泰科菲阀门   阀门厂家   进口阀门   阀门  

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