Choke valve is a valve that controls the flow of a fluid by changing a throttle section or a throttle length. The choke valve and the check valve are connected in parallel to form a one-way choke valve. The choke valve and the one-way choke valve are simple flow control valves. In the hydraulic system of the fixed pump, the choke valve and the relief valve cooperate to form three throttling speed control systems, that is, the throttle speed regulation System, return oil throttle control system and bypass throttle speed control system. The choke valve has no negative flow feedback function and cannot compensate for the instability caused by the load change. It is generally only used in applications where the load does not change much or the speed stability is not high.
The choke valve can be divided into straight-through type and angle type according to the channel mode; according to the shape of the opening and closing member, there are three types of needle shape, groove shape and window shape.
Adjustable throttle: The valve needle and spool are made of hard alloy. The product is designed according to API6A standard and has wear resistance and erosion resistance. Mainly used in wellhead oil (gas) tree equipment.
Sleeve type choke valve: The valve core adopts low noise balance structure, which is light and easy to open. The product is designed according to API6A standard. The surface of the valve core is covered with tungsten carbide. It is suitable for flashing, high pressure difference, high pressure, cavitation and other harsh conditions. Occasionally, the service life is long and the flow adjustment accuracy is greatly improved. Suitable for oil, natural gas, chemical, oil refining, hydropower and other industries.
Since the flow rate of the choke valve depends not only on the area of the orifice, but also on the pressure difference before and after the orifice, the rigidity of the valve is small, so it is only suitable for the actuator load change and the speed stability is not high. occasion.
For the throttle control system with large load variation of the actuator and high speed stability requirements, the choke valve must be pressure compensated to keep the differential pressure before and after the choke valve constant, so as to achieve flow stability.