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A choke valve is a valve that controls the flow of fluid by changing the throttling section or the throttling length. Everyone may see it very little in life, and is also not very clear about the working principle of the choke valve.
The choke valve is very similar to the globe valve in terms of shape and structure, and the only difference is the shape and working stroke of the valve disc. Therefore, the components of the choke valve and the globe valve are highly interchangeable.
All kinds of shut-off valves can change the cross-sectional area of the medium channel, so they can also play a regulating role to a certain extent, but their regulating performance is not good.
This is because their opening and closing parts and the valve stem are movably connected, and there is a gap at the connection, which is inconvenient to adjust; the lifting and lowering of the opening and closing parts is not proportional to the change of the channel area, so it is difficult to achieve accurate and continuous adjustment.
When the channel area is small and the medium flow rate is large, it will cause serious erosion of the sealing surface and cause the vibration of the valve disc. Therefore, the choke valve with special structure and the shape of the opening and closing parts is usually used for adjustment.
The choke valve is mainly used to adjust the flow and pressure. When we are selecting the valve, the flow control range, pressure drop and its load must be considered to avoid premature failure and ensure safe use. Valves used for high differential pressure throttling require specially designed valve sealing elements.
In general, the maximum differential pressure across the valve disc of choke valve must not exceed 20% of the maximum upstream pressure or 200 psi (1380 kPa), whichever is less. Valves with special sealing elements can be used beyond this differential pressure limit.
The choke valve can play the role of controlling the fluid flow. Generally speaking, when the pressure difference of the choke valve is constant, the size of the opening affects the change of the liquid flow. In a nutshell, the choke valve has three main functions:
(1) The role of throttling and speed regulation
The choke valve changes the flow by controlling the throttle section or length, which is the main role of the choke valve and its main function.
(2) The role of load resistance
The choke valve can also play a load role to a certain extent, which is only a part of the function of the choke valve. The main function of the choke valve is still throttling and speed regulation.
(3) The role of pressure buffer
The choke valve can play a pressure buffering effect on the fluid. When the fluid flows in through the choke valve, the choke valve can hinder the passage of the fluid to a certain extent and reduce the impact force.
According to the channel mode, the choke valve can be divided into two types: straight-through type and horizontal type; according to the shape of the opening and closing parts, there are three types: needle-shaped, groove-shaped and circular types.
Adjustable choke valve: the valve needle and valve element are made of hard alloy. The product is designed according to the API6A standard and has properties of wear resistance and erosion resistance. It is mainly used for wellhead oil (gas) tree equipment.
Sliding type choke valve: the valve element of choke valve adopts a low-noise balanced structure, which is easy to open. The product is designed according to the API6A standard, and the surface of the valve element is covered with tungsten carbide.
It is suitable for occasions with harsh conditions such as flash evaporation, high pressure difference, high pressure, cavitation, etc., with long service life and greatly improved flow adjustment accuracy. It is suitable for petroleum, natural gas, chemical, oil refining, hydropower and other industries.
