Structural Performance Analysis And Optimization Of Needle Throttle Valve In High Pressure Gas Well

Needle throttle valve is installed on the wellhead device tree of high pressure gas well which is used to adjust the action of natural gas output pressure and flow rate. It is mainly consists of valve body, valve core, valve stem and other parts, the shape of the valve core just like a needle, when it is working, in order to realize the purpose of controlling gas flow rate and pressure, we can transfer the position of the valve stem to change the Circulation area of throttle valve.Especially for high pressure gas well, the performance of throttle valve will directly determines the safety of construction process when we are drilling, during the process of gas exploitation, the working conditions of throttle valve is very bad, such as: large flow, high pressure, and there is many hard solid particle in the fluid medium, etc. The main problems of needle valve includes presently:Frictional resistance of the valve stem is very big, The valve body is easy to erosion, the valve core is easy to fall off, the volume is too large.Aimed mainly at the two problems:Frictional resistance of the valve stem is very big and the valve body is easy to erosion,this paper do some research as the following work:(1) This paper do some research on the working principle of needle valve, the main reason for the failure of seal ring, the reason for the erosion wear failure of valve body, summarized the main reason of Frictional resistance of the valve stem is very big is mainly because of high Frictional resistance between seal ring and metal surface, and the main factors affecting the body erosion wear including erosion velocity of solid particle, impact angle and particle nature of itself.(2) Using finite element analysis method, the sealing performance of the original seal ring structure is analyzed, the evaluation method of seal performance is determined in the end.(3) In order to develop the sealing performance of the seal ring structure, three new structure are designed, the new seal rings in plan1and2are optimized based on structure change, The new seal ring in plan3is designed integrating structure and material, the optimal sealing ring structure is chosen after analyzing.(4) The change rules of gas flow velocity、solid particle velocity, pressure drop, the erosion rate of the body wall, etc. are analyzed. The most serious erosion field of the valve body and the solid particle accumulation area heavily are founded in the internal valve body.(5) According to the flow velocity of the solid particles inside the valve body, particle concentration distribution and the body of erosion wear, this paper designs a new valve body structure. The new structure has a throttle opening with taper and its entrance was design with bend structure, the structure could significantly reduces the solid particle erosion of the valve body, and it also could prevent solid particles inside the body from accumulating in the body.By analyzing the performance of the needle valve, the evaluation method of seal performance and body resistance to erosion are determined, the optimal sealing structure and body structure are obtained in the end. The evaluation method in this paper has certain reference significance for designing of a high performance needle valve.