In our daily life and production, valves are used more and more widely. In the automatic control system, the control valve is one of the important and indispensable components, and it is one of the terminal control components of the automatic control system.
The angle control valve has a simple flow path and low resistance, and is generally suitable for forward use (installation). However, in the case of high pressure drop, it is recommended to use the angle-type control valve in reverse to improve the unbalanced force and reduce the damage to the valve core, and at the same time, it is also beneficial to the flow of the medium and avoids coking and clogging of the control valve. When the angle control valve is used in reverse, it should be avoided to open with a small opening for a long time, so as to prevent strong oscillation and damage to the valve core. Especially in the trial production stage of chemical plants, due to the low load during trial production, and the design process conditions cannot meet the requirements quickly, the angle control valve used in the reverse direction should avoid the opening of a small opening for a long time as much as possible to prevent The angle control valve is damaged.
Key words: angle control valve; reverse use (installation); small opening; easy to damage
In the production process automation adjustment system, the control valve is an important and indispensable link, which is called the “hands and feet” of the production process automation, and is one of the terminal control components of the automatic control system. It is composed of actuator and valve. From a hydraulic point of view, the regulating valve is a throttling element whose local resistance can be changed. The regulating valve changes the resistance coefficient by changing the stroke according to the input signal, so as to achieve the purpose of regulating the flow.
The structure and use of angle control valve
The structure of the 1-angle control valve
Except that the valve body is an angle type, the other structure of the angle control valve is similar to that of the single seat valve. Its characteristics determine that its flow path is simple and the resistance is small, which is especially beneficial for high pressure drop, high viscosity, containing suspended solids and particulate matter. Fluid regulation. It can avoid the occurrence of coking, sticking and clogging, and is also easy to clean and self-clean.
Comparison of forward and reverse use of 2-angle control valve
Under normal circumstances, angle control valves are installed in the forward direction, that is, the bottom enters and the side exits. Only in the case of high pressure difference and high viscosity, easy coking, medium containing suspended particles, it is recommended to install in reverse, that is, the material side enters and the bottom exits. The purpose of the reverse use of the angle control valve is to improve the unbalanced force and reduce the wear on the valve core, and it is also conducive to the flow of high-viscosity, coking-prone and suspended particulate-containing media to avoid coking and clogging.
In general,At present, except for butterfly valves and diaphragm valves, which are completely symmetrical in structure, all other structures of regulating valves are asymmetrical. When the regulating valve changes the flow direction, the value of ) changes due to the change of the flow path. The normal flow direction of all kinds of regulating valves is the direction in which the spool is opened (forward use), and the manufacturer only provides the flow capacity in the normal flow direction) and flow characteristics. When the regulating valve is used in reverse, that is, when the fluid flows in the direction of closing the spool, the flow capacity of the regulating valve will increase. During the water linkage test run, the simulated process conditions cannot quickly reach the normal state, and the regulating valve is used in a small opening state for a long time, which will cause serious instability due to the effect of unbalanced force. Therefore, the regulating valve will generate strong vibration and make a harsh noise, which will cause the valve core to break quickly. Under normal process conditions, the opening of the regulating valve is moderate, and even a small opening is short-lived, so the regulating valve can be used normally and safely.
From the above analysis of the angle control valve, we draw the following conclusions:Angle type control valves are not recommended to be used in reverse, only in the case of high pressure difference, high viscosity, easy coking and medium containing suspended particles. When using it in reverse, it should be avoided to run with a small opening for a long time, especially during the test run.