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Introduction of three classifications of steam regulating valves
Oct 30, 2018

Steam regulating valve is called steam regulating valve because it uses steam as medium. It is divided into electric steam regulating valve, pneumatic steam regulating valve and self-operated steam regulating valve according to the choice of actuator. It is a single-seat steam regulating valve, a sleeve steam regulating valve, and a two-seat steam regulating valve.
The pneumatic steam regulating valve is composed of a pneumatic multi-spring diaphragm actuator and a low flow resistance single seat valve. The new actuator has low height, light weight and simple equipment. The new valve body has compact structure, smooth flow path and large flow coefficient. The pneumatic steam regulating valve is stable in operation, with reliable operating characteristics, small valve seat leakage, precise flow characteristics, and wide adjustable range.
Pneumatic steam control valves are sure to achieve high quality control results in a wide range of applications with unique advantages. Pneumatic steam regulating valves are available in standard, adjustable cut-off type, bellows seal type, and jacket insulation type. Pneumatic steam regulators are available in a variety of grades from 100°C to +560°C.
Pneumatic steam regulator valve features
Pneumatic steam regulating valve is suitable for applications where the leakage is strict, the differential pressure before and after the valve is low, and there is a certain viscosity and a small amount of fiber steam. The pneumatic flow regulating valve can be divided into two types: normally open air closed type and normally closed air open type according to different switching modes. The gas shutoff valve consists of a positive acting actuator and a valve. When the input signal pressure is changed from the lower limit value to the upper limit value, the valve is fully open to fully closed. The air-open valve consists of a reaction actuator and a valve. When the input signal pressure is changed from the lower limit value to the upper limit value, the valve is fully closed to fully open.

The electric steam regulating valve has compact structure, precise flow characteristics and small leakage of the seat. Electric steam regulating valves are widely used in petroleum, chemical, metallurgical, power station and other industrial sectors. The electric steam regulator uses the 3810L (PSL) series of electronic electric actuators. The integrated structure with built-in electronic controller module eliminates the hassle of using a servo amplifier. The adjustment mechanism uses a new low flow resistance single seat valve. The utility model has the advantages of compact structure, smooth flow path, precise flow characteristics, large adjustable range, and small leakage of the valve seat. Control gas, liquid, steam and other media, suitable for occasions where the leakage is strictly required.
Electric steam regulating valve product features
Electric steam regulating valve consists of PS series and 3610 series linear actuators and low flow resistance steam straight through single seat valves. (Can also be equipped with other brands of straight-line executives). The steam electric actuator is an electronic integrated structure with a servo amplifier. The input control signal (4-20mADC or 1-5VDC) and the power supply can control the valve opening to achieve the parameters such as pressure, flow, liquid level and temperature. Adjustment. It has the characteristics of sensitive action, simple connection, large flow, small size and high adjustment precision. Control accuracy and performance are significantly improved over the DKZ model.
The pre-valve pressure P1 of the working steam passes through the throttle after the valve core and the valve seat, and becomes the post-valve pressure P2. P2 is input into the lower chamber of the actuator through the control line and acts on the top plate. The generated force is balanced with the reaction force of the spring, which determines the relative position of the valve core and the valve seat, and controls the pressure behind the valve. When the post-valve pressure P2 increases, the force acting on the top plate of P2 also increases. At this time, the force of the top plate is greater than the reaction force of the spring, so that the valve core is closed to the position of the valve seat until the force of the top plate is balanced with the reaction force of the spring. At this time, the flow area of the valve body and the valve seat is reduced, and the flow resistance is increased, so that P2 is lowered to a set value. Similarly, when the post-valve pressure P2 is lowered, the action direction is opposite to the above, which is the working principle of the self-operated (post-valve) pressure regulating valve. This type of valve should generally be installed horizontally in the pipeline. When it is necessary to change the set value of the post-valve pressure P2, the adjusting nut can be adjusted.
Pre-valve pressure control

The pre-valve pressure P1 of the self-operated steam regulating valve is changed to the post-valve pressure P2 after the throttle after the valve core and the valve seat. At the same time, P1 is input into the upper chamber of the actuator through the control pipeline and acts on the top plate. The generated force is balanced with the reaction force of the spring, which determines the relative position of the valve core and the valve seat, and controls the pressure before the valve. As the pre-valve pressure P1 increases, the force acting on the top plate by P1 also increases. At this time, the force of the top plate is greater than the reaction force of the spring, so that the valve core moves away from the valve seat until the force of the top plate is balanced with the reaction force of the spring. At this time, the flow area of the valve body and the valve seat is increased, and the flow resistance is reduced, so that P1 is lowered to a set value. Similarly, when the pre-valve pressure P1 is lowered, the action direction is opposite to the above, which is the working principle of the self-operated (pre-valve) pressure regulating valve.
When it is necessary to change the set value of the pre-valve pressure P1, the adjusting nut can be adjusted.
Self-operated temperature control valve working principle (heating type)
The temperature regulating valve works according to the principle of incompressibility and thermal expansion and contraction of the liquid. The self-operated temperature regulating valve for heating, when the temperature of the controlled object is lower than the set temperature, the liquid in the temperature pack shrinks, the force acting on the actuator push rod is reduced, and the valve core member opens the valve under the action of the spring force. Increase the flow rate of heated steam such as steam and hot oil, so that the temperature of the controlled object rises until the temperature of the controlled object reaches the set value, the valve closes, and after the valve is closed, the temperature of the controlled object drops, the valve opens again, and the heated steam is again Entering the heat exchanger, the temperature is raised again, so that the temperature of the controlled object is constant. The valve opening degree is related to the difference between the actual temperature and the set temperature of the controlled object.
Self-operated temperature control valve working principle (cooling type)
The working principle of the self-operated temperature regulating valve for cooling can be referred to the self-operated temperature regulating valve for heating. However, when the valve core member is opened and closed under the action of the actuator and the spring force, the valve body passes through the cold steam, and is mainly used in the valve body. Temperature control in the cooling unit.
Working principle of self-operated flow regulating valve
After the steam input valve is controlled, the pre-valve pressure P1 is input to the lower diaphragm chamber through the control line, and the pressure Ps after the throttling of the throttle valve is input to the upper membrane chamber. The difference between P1 and Ps is ΔPs=P1-Ps, which is called effective pressure. . The thrust generated by P1 acting on the diaphragm and the thrust difference generated by Ps acting on the diaphragm are balanced with the spring reaction force to determine the relative position of the spool and the valve seat, thereby determining the flow rate through the valve. When the flow rate through the valve increases, that is, ΔPs increases, and as a result, P1 and Ps act on the lower and upper membrane chambers respectively, so that the valve core moves toward the valve seat, thereby changing the flow area between the valve core and the valve seat, so that The Ps increases, and the increased thrust of the Ps acting on the diaphragm plus the spring reaction force and the thrust of the P1 acting on the diaphragm balance the new position to achieve the purpose of controlling the flow. On the contrary, the same reason.
Self-operated regulating valves are used to regulate process parameters such as steam flow, pressure, temperature and liquid level in the field of industrial automation process control. The valve opening is automatically adjusted according to the control signals in the automation system to achieve steam flow, pressure, temperature and liquid level adjustment.
Features
Self-operated steam regulating valve features
1. The self-operated steam regulating valve does not need external energy, and can work in the situation of no electricity and no gas, which is convenient and saves energy.
2. The pressure segmentation range is fine and crosses each other, and the adjustment precision is high.
3. The pressure set value can be set continuously during operation.
4, the pressure adjustment after the valve, the ratio between the pressure before the valve and the pressure behind the valve is 10:1~10:8
5, rubber diaphragm type detection, the actuator has high detection accuracy and sensitive action.
6. The pressure balance mechanism is adopted to make the control valve sensitive and accurate.

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