Classification & Working Principle of Throttling Valve
Common throttle valves are classified by function into throttling type and throttling-stop type. Throttling-stop type valves can both throttle and cut off flow. Structurally, they can be divided into needle valves, cylindrical valves, orifice plate valves, and wedge valves. Needle valves and orifice plate valves belong to the throttling-stop type, while the other two are throttling type.
The working principle of a throttle valve is to use a handwheel or other drive mechanism to adjust the position of the valve core and valve seat, changing the flow clearance or even completely cutting it off.
The valve core of a needle valve is needle-shaped or conical, and both the valve core and valve seat are conical with the same taper. When fully closed, it forms a metal-metal seal, when completely closed, it cuts off the flow. It has a longer throttling stroke, a more uniform flow area, and better throttling characteristics.
Cylinder valves are made entirely of hard alloy, and their valve seats are usually designed with a flip-up structure, allowing them to be turned around for use after one side wears out. They have a shorter adjustment stroke, a less uniform throttling area, and generally lower throttling characteristics.
Orifice plate throttle valves consist of a fixed and rotating disc. The valve core structure includes semi-circular and double-orifice types. Throttling is achieved by rotating a handwheel or gear, which changes the overlap area of the orifices on the rotating and fixed discs, thus achieving throttling. The flow area changes uniformly, resulting in good throttling characteristics. When closed, the pressure difference across the orifice place causes the fixed and rotating discs to adhere tightly, completely stopping the flow.
Wedge-shaped throttle valves have a wedge-shaped valve core and paired with an erosion-resistant valve seat, providing strong erosion resistance and a long service life. Their unique crescent-shaped throttling orifice causes the throttling area to change in a“slow-fast-slow”rhythm, effectively meeting the fine-tuning needs of the entire well control process.
As a crucial component of the well control manifold, the throttle valve is key to implementing circulating sewage discharge or throttling well control.
