Our North Valve Group Co., Ltd. is a manufacturer of research and development, production and sales of standard general industrial valves such as high-temperature and high-pressure valves, ball valves, gate valves, butterfly valves and globe valves, with diameters ranging from 10mm to 3000mm and nominal pressure PN ranging from 1Mpa to 80Mpa. At the same time, we can also customize non-standard valves for you. Welcome to call us.
The high-temperature and high-pressure valve manufacturer is arranged by the technical department of North Hi-Tech Group. The high-temperature and high-pressure valve is also known as the high-temperature and high-pressure regulating valve. In the field of industrial automation process control, it is the final control element that changes the process parameters such as medium flow, pressure, temperature and liquid level by means of power operation. Generally, it consists of actuator and valve. According to the stroke characteristics, high temperature and high pressure valves can be divided into straight stroke and angular stroke; According to the power used by the actuator, it can be divided into three types: pneumatic high temperature and high pressure valve, electric high temperature and high pressure valve and hydraulic high temperature and high pressure valve. According to its function and characteristics, it can be divided into linear characteristics, equal percentage characteristics and parabolic characteristics. High temperature and high pressure valves are suitable for air, water, steam, various corrosive media, mud, oil and other media.
So what measures should be taken when the high temperature and high pressure valve fails? Here are several protection schemes for high-temperature and high-pressure valve failures:
J61Y High Temperature and High Pressure Power Station Stop Valve
The function of high temperature and high pressure valve in process control is well known. In many control processes, it is required that the high temperature and high pressure valve be in a certain position when it fails to protect the process from accidents, which requires that the high temperature and high pressure valve be designed to realize the fault-safe three-break (gas cut-off, power cut-off and signal cut-off) protection measures. For electric high-temperature and high-pressure valves, it is relatively simple. When the signal is cut off, it can stay in any position of full opening, full closing and holding according to the setting of the control module, while when the power is cut off, it naturally stays in the fault position, or the electric actuator with reset device can also run the valve position to full opening or full closing.
For pneumatic high-temperature and high-pressure valves, the situation is more complicated, so we mainly discuss the three-break position keeping method of pneumatic high-temperature and high-pressure valves. Generally speaking, when we choose pneumatic thin-film high-temperature and high-pressure valves, we must first determine whether to open or close the gas, which is the protection position when the high-temperature and high-pressure valves are cut off. If the process requires that the valves be opened when the gas is cut off, we should choose the normally open (gas-closed) high-temperature and high-pressure valves, otherwise we should choose the normally closed (gas-opened) high-temperature and high-pressure valves. This is only a shallow scheme. If the process requires three-way protection of gas cut-off, power cut-off and signal cut-off, the high-temperature and high-pressure valves need to be equipped with some accessories to form a protection system to meet the control requirements. These accessories mainly include position retaining valves, high-temperature and high-pressure regulating valves and gas tanks. The following are two retention schemes for single-acting pneumatic membrane high-temperature and high-pressure valves and double-acting pneumatic high-temperature and high-pressure valves.
I. Scheme of pneumatic diaphragm high-temperature and high-pressure valve (high-temperature and high-pressure valve is equipped with electro-pneumatic valve positioner)
ZJSF(H) pneumatic diaphragm three-way flow dividing (closing) regulating valve
This scheme is mainly composed of pneumatic high-temperature and high-pressure valve, electro-pneumatic valve positioner, power loss (signal) comparator, single electronically controlled electromagnetic directional valve, pneumatic position retaining valve, valve position signal returner, etc. Its working principle is as follows:
1, cut off the gas source:
When the air source of the control system fails (loses air), the pneumatic retaining valve automatically closes to lock the output signal pressure of the positioner in the membrane chamber of the pneumatic high-temperature and high-pressure regulating valve, and the output signal pressure is balanced with the reaction force generated by the spring of the high-temperature and high-pressure regulating valve, so that the valve position of the pneumatic high-temperature and high-pressure regulating valve remains in the failed position. The retaining valve should be set to start when it is slightly lower than the smaller value of the air source.
2, power off:
When the power supply of the control system fails (loses power), the power loss (signal) comparator controls the output voltage of the single electric control electromagnetic directional valve to disappear, the single electric control electromagnetic directional valve loses power, the slide valve in the single electric control electromagnetic directional valve slides under the action of the return spring, the high-temperature and high-pressure regulating valve reverses direction, the pressure of the membrane chamber of the pneumatic position-keeping valve is evacuated, and the pneumatic position-keeping valve is closed, so that the output signal pressure of the positioner is locked in the membrane chamber of the pneumatic high-temperature and high-pressure regulating valve, and the output signal pressure is balanced with the reaction force generated by the spring of the high-temperature and high
3, broken signal:
When the signal of the control system fails (loses signal), the power-off (signal) comparator will cut off the voltage signal of the single electric control electromagnetic directional valve, and the single electric control electromagnetic directional valve will lose power. The slide valve in the single electric control electromagnetic directional valve will slide under the action of the return spring, and the high-temperature and high-pressure regulating valve will reverse, emptying the pressure of the membrane chamber of the pneumatic position-keeping valve, closing the pneumatic position-keeping valve, locking the output signal pressure of the positioner in the membrane chamber of the pneumatic high-temperature and high-pressure regulating valve, and outputting the signal pressure and the high-temperature and high-pressure regulating valve.
The position feedback signal is given by the valve position signal returner.
The advantages of this scheme are: when the "three-break" protection is started, the system responds quickly and acts quickly. The overall cost is relatively cheap.
Disadvantages of this scheme: the high-temperature and high-pressure regulating valve is charged for a long time, which affects the service life. With more accessories, the installation and debugging are more complicated, and the valve position feedback needs to be equipped with a valve position signal return device, which is more complicated in the case of using a handwheel.
Second, the double-acting pneumatic high-temperature and high-pressure valve scheme (high-temperature and high-pressure valve with electro-pneumatic valve positioner)
Pneumatic high temperature cut-off butterfly valve
1. This scheme is mainly composed of high-temperature and high-pressure regulating valve, pneumatic reversing valve, positioner, self-locking valve, one-way valve, pressure reducing valve and gas storage tank. Its working principle is as follows:
When the air source of the control system fails (loses air), the self-locking valve (which acts in the opposite way to the retaining valve) will automatically open, and the control air source of the pneumatic directional valve will be cancelled, and the slide valve of the pneumatic directional valve will be reset under the action of the spring. One of the two pneumatic directional valves exhausts, the other air inlet, and the one-way valve will be closed, and the air source will supply air to the valve from the air source stored in the air storage tank, thus realizing the full or full opening of the valve. The switch between full-closed and full-open can be realized by adjusting the connection mode of pneumatic reversing valve.
2. To realize valve retention, install pneumatic retention valve and change the pipeline connection, directly control the retention valve with self-locking valve, and cancel the pneumatic directional control valve, one-way valve and gas storage tank.
3. The following scheme can be adopted to ensure that the valve can act several times when the gas source is cut off.
This scheme consists of gas storage tank, one-way valve, blocking valve and stop valve. Its working principle is as follows:
When the air source fails (loses air), the one-way valve closes, and the blocking valve loses air. The slide valve of the blocking valve is reset under the action of the spring, and the air path is reversed. The air source pipeline of the system is disconnected, and the gas storage tank pipeline is connected, so that the gas storage tank can supply air to the valve, so as to ensure that the valve has several actions and realize the purpose of continuous control. Due to the limited capacity of the gas storage tank, and the pressure of the gas source in the gas storage tank is constantly decreasing with the action of the valve, it is not possible to use the gas storage tank to supply gas to the valve for a long time. The capacity of the gas storage tank used in this scheme should be larger than that of the general protection gas storage tank. In this scheme, when the gas source is cut off, the number of valve actions is related to the capacity of the gas storage tank.
4. There is also a reference for the positioning scheme of pneumatic diaphragm high-temperature and high-pressure valve: a positioning valve and a two-position three-way high-temperature and high-pressure regulating valve are connected in series between the positioner and the actuator, and the positioning is maintained by the positioning valve when the gas is cut off, and the positioning is maintained by the high-temperature and high-pressure regulating valve when the signal is cut off. However, the high-temperature and high-pressure regulating valve must be interlocked with the positioner (set in the control program), that is, the positioner has a signal, and the high-temperature and high-pressure regulating valve must be powered on. Once the positioner loses its signal, the high
After reading this article, I believe you have a certain understanding of high-temperature and high-pressure valves. Our North Valve Group Co., Ltd. is a manufacturer of high-temperature and high-pressure valves. For decades, the company has sold high-quality valve products, and the product technology and quality have been certified by national authorities, reaching national standards and deeply trusted by customers.
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Release time：2024-03-19