Introduction to common gate valve gate and its application in the power plant thermal system

by:AIRWOLF     2020-05-15
There are a large number of thermal system in power plant piping, these pipes have different purposes, to each of the pipes and connections of equipment can meet the requirements of the operation of the thermal system, what the valve door requires scientific choice, according to the function of the system to choose the appropriate gate valve is connected to the pipe and equipment, so as to achieve the needs of the system function, according to many years of experience in here talk about gate valve gate a little common sense, and the thermal system in power plant which can be used in the system. 1, the classification of gate valve gate valve gate in accordance with the sealing surface configuration can be divided into wedge gate valve gate door and parallel sluice gate valve door, wedge gate valve gate door can be divided into: single gate type, double disc and flexible disc; Parallel slide gate valve door can be divided into single ram and double ram. According to the valve rod thread position, can be divided into rising stem gate valve gate and two non-rising stem gate door. Gate valve gate including gate valve gate valve body and disc, ram has two sealing surface, the two most commonly used mode gate valve sealing surface form a wedge, the wedge Angle vary with the valve door parameters, wedge gate valve gate door is the ram is wedge gate valve gate, single ram is a single ram, double ram type is two ram. Wedge gate valve gate of the door can be made into a whole, is called a rigid disc; Can also make it generates trace of deformation of ram, in order to improve the manufacturability, make up for the sealing surface Angle in the process of our processing deviation, this damper is called elastic brake. Parallel slide gate valve door means the gate door gate are parallel, the same gate is divided into single ram and double ram. Rising stem gate valve gate valve stem head in opening and closing the valve door when lifting, which is to see the valve rod movement ( Not rotating lifting only) , the so-called non-rising stem gate valve gate valve rod in the opening and closing valve door would only rotate without lifting. 2, working principle and characteristics of gate valve gate valve door is opening and closing of ram, the ram of the direction perpendicular to the direction of flow, gate door can only be fully open and close, not to adjust and throttling. Gate valve door seal has since sealing and forced sealing two kinds. Sealing surface can only rely on medium pressure to seal, that is, to rely on medium pressure to press the sealing face of gate to the other side of the valve seat to ensure sealing face seal, this is the seal. Forced sealing refers to the gate door is closed, to rely on outside force forced the ram pressure to the valve seat, to ensure the sealing surface sealing. Open the valve gate when the gate hoisting height is equal to the 1:1 times of valve gate size, fluid channels completely open, but at runtime, the position cannot be monitored. Actual use, based on the valve rod vertices as a sign, that is not moving, as its full open position. To consider locking phenomenon in a temperature change, usually in the open to the vertex positions, pour 1/2 - back 1 ring, as a fully open valve of the position of the door. Therefore, valve door fully open position, according to the location of the damper ( The trip) To determine. Gate valve gate has the following characteristics. Advantages are: 2. 1, small fluid resistance, sealing surface Chong brush and erosion by the medium. 2. 2, open and close more effort. 2. 3 the flow direction of medium, not restricted, disturbed flow, reduce the pressure. 2. 4, the structure of the form is simple, short length, good manufacturing technology, wide application scope. The disadvantages are: 2. 5, easy cause surface erosion and abrasion, maintenance is difficult. 2. 6, appearance size is larger, open needs certain space, open and close time is long. 2. 7 and complicated structure. 3, gate door installation and maintenance should pay attention to item 3. 1, hand wheel, lever and transmission mechanism are not allowed for lifting, and it is forbidden to collision. 3. 2, double gate valve should be installed vertically (door The valve stem in a vertical position, the handwheel at the top) 。 3. 3, the gate valve with a bypass valve gate in front of the opening should be open the bypass valve ( To balance the import and export of pressure difference and reduce the opening force) 。 3. 4, belt transmission mechanism of the gate door, according to the regulations of the product instruction manual installation. 3. 5, if the valve door switch is used, often lubrication at least once a month. 3. June, installation position and height must comply with the design requirements, the connection should be firmly connected. 3. 7, all kinds of manual valve door installed on the thermal insulation pipe, handle shall be down. 3. A visual inspection must be conducted before eight, gate door installation, the valve nameplate of the door should be consistent with existing national standards of the common valve door sign GB12220 rules.
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