In the production process automation regulation system, the control valve is an important, essential link, is called the production process automation "the hand and Foot", is one of automatic control system terminal Control components. The angle type adjusts the valve flow path is simple, the resistance is small, generally applies in the forward use (installs). However, in the case of high pressure drop to recommend the reverse use of angle control valve to improve the imbalance and reduce the damage to the spool, but also conducive to the flow of media, to avoid the adjustment valve coking and blockage. Angle control valve in reverse use, especially should avoid a long period open opening, in case of a strong oscillation and damage the spool.
Especially in the chemical plant trial production stage, because the trial production load is lower, the design process conditions may not quickly meet the requirements, the reverse use of angle control valve should be as far as possible to avoid a longer opening condition, to prevent the damage of the angle control valve. In the production process automation regulation system, the control valve is an important, essential link, is called the production process automation "the hand and Foot", is one of automatic control system terminal Control components. It is composed of actuator and valve two parts.
From the hydraulics point of view, the control valve is a local resistance can change the throttle element, the control valve is based on the input signal by changing the stroke to change the drag coefficient, so as to achieve the purpose of regulating flow.
Structure and application of angle-type regulating valve
1 structure of the angle-type regulating valve Angle Control Valve In addition to the valve body for the angle, the other structures are similar to the single seat valve, its characteristics determine its flow path is simple, small resistance, particularly conducive to high pressure drop, high viscosity, containing suspended solids and granular material fluid regulation.
It can avoid coking, bonding and clogging phenomena occur, but also easy to clean and self-cleaning.
2 angle type Control valve positive and reverse use comparison Under normal circumstances, the angle-type control valves are used forward installation, that is, the bottom into the side out. Only in high pressure and high viscosity, easy coking, including suspended particulate matter medium, only recommended reverse installation, that is, material side to bottom out.
The purpose of the angular control valve reversal is to improve the unbalance force and reduce the wear of the spool, and also to facilitate the flow of high viscosity, easy coking and medium with suspended particulate matter to avoid coking and blockage.
How to apply angular control valve in production
Analysis of reverse use of angular control valve Jilin Chemical Industry Co., Ltd. in the acetaldehyde device introduced from West Germany, the pv-23404 angle regulating valve is recommended for reverse use under the condition of high pressure drop. In the water linkage test, the angular control valve produces a strong oscillation, and a harsh noise, the test 4h after the spool is broken. At that time, foreign experts believed that the valve core manufacturing quality is not the result. I think it is not a quality problem, but because of unreasonable use.
The causes of fracture are analyzed below. We know that at present except the butterfly valve and diaphragm valve are completely symmetrical in structure, all the other structural control valves are asymmetrical. When the regulating valve changes the flow direction, the change of the flow path will cause the value change. The normal flow direction of all kinds of regulating valves is to make the valve core open (forward use), the production plant also only provides the flow capacity of normal flow, and flow characteristics. When the control valve is used in reverse, the flow capacity of the regulating valve will increase when the fluid flows along the direction of closing the spool. When the water linkage test, the simulated technological conditions may not soon reach the normal state, the regulating valve is used in the small opening condition for a long time, because of the unbalance force, it will appear serious instability. So the control valve will produce a strong vibration and make a harsh noise, resulting in the valve core quickly broken. In the normal process conditions, the opening of the control valve is moderate, even if the small opening is also short-lived, so the control valve can be used safely.