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Presentation: Dr. Lian Zhanghua

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1 Presentation: Dr. Lian Zhanghua
FLUID FIELD ANALYSIS OF HIGH PRESSURE THROTTLE VALVEAND IT’S STRUCTURE IMPROVEMENT Presentation: Dr. Lian Zhanghua Southwest Petroleum Institute Chengdu, Sichuan Province P.R. of China P.O. Box

2 Contents Introduction Theoretical analysis of throttle valves
Geometry model of the cone valve CFD analysis of a wedge valve Discussions of structure improvement Conclusions

3 Introduction Fig.1 shows the valve rod fracture accident that occurred at Dongqiu well No.8 in Tarim Oil Field in May of Fig.2 shows the valve body and the double flange spools washout in the kill-job at Wushen well No.1 in Tarim Oil Field. The early pressure-control techniques and the throttle system could no longer meet the demand in production, gathering and transporting. Fig.1 Valve rod fatigue fracture Fig.2 Valve body washout

4 Fig.3 Relation between flow coefficient and opening of the cone valve
Theoretical analysis of throttle valves 1. The flow coefficient 2. The flow resistance coefficient Fig.3 Relation between flow coefficient and opening of the cone valve

5 Geometry model of the cone valve
the CAD model of every valve was built with Pro/E software, and the geometry data have been saved as STL format files, and then imported into PHOENICS software for the CFD modeling. Fig.4 The structure section CAD model of the cone valve Fig.5 Geometry structure section of the cone valve

6 Analysis of the CFD results of the cone valve
1. Computation and solution Fig.6 Pressure contours Fig.7 Velocity vectors

7 Analysis of the CFD results of the cone valve
2. Results analysis Fig.8 Streamline pattern

8 CFD analysis of a wedge valve
1. Geometry a. one slope surface b. an arc surface c. two slope surface Fig.9 Schematic diagram of structure of wedge valve Fig.10 Structure CAD model of wedge valve

9 CFD analysis of a wedge valve
2. Result analysis Fig.11 Relation of pressure vs. stroke

10 CFD analysis of a wedge valve
3. Analysis of flow field pattern Fig.12 Velocity vector patterns Fig.13 Velocity contour

11 Stroke of the valve core flow resistance coefficient 
CFD analysis of a wedge valve Table 1 Pressure drop, flow resistance coefficient of the wedge valve at different opening Stroke of the valve core (mm) flowing area (mm2) wetted perimeter equivalent diameter pressure drop(MPa) flow resistance coefficient  3 92.86 60.26 6.16 26.438 4 134.19 68.01 7.89 24.674 5 176.61 74.39 9.50 22.789 6 219.28 79.85 10.98 20.278 7 261.64 84.55 12.38 17.462 8 303.35 88.68 13.68 14.347 864.16 9 344.15 92.37 14.90 11.011 663.22 10 383.89 95.68 16.05 8.300 499.93 11 422.44 98.64 17.13 5.058 304.66 12 459.74 101.35 18.14 4.096 246.71 13 495.74 103.81 19.10 3.249 195.70 14 530.44 106.07 20.00 2.919 175.82 15 563.84 108.14 20.86 2.829 170.40

12 Discussions of structure improvement
In order to get a better distribution of the fluid field, the paper presented a wedge surface that consists of two slopes, shown as in Fig.9c. From the figure, we could see that the valve core of the wedge valve consists of two slopes, and the bottom slope is parallel to the central axial line, and parallel to the surface of the shell body. It is to avoid the direct impact of the fluid on the wall. Through plentiful fluid field analysis, this structure (shown as Fig.9c) has been the optimum, the production has been applied in the oil field, its life is 5~7 times that of the cone valve.

13 Conclusions The flow resistance is greater when the fluid flows into the region that abruptly changes its shape than the region that gradually changes its shape. In the design and installation of the throttle valve, the flow passage, that abruptly changed, should be used. With enough flow passage area, the bigger flow resistance is better. 2. The erosion to the valve parts such as valve cavity, valve core, mainly comes from the mud impacting on the valve parts at a high velocity as the mud medium directly rushes to the shell body. The tangent direction of the end section of the valve core should be parallel with the central axial line of the shell body, namely a plane, at the end section of the valve core, parallel with the central axial line of the shell body. 3. The cone valve is equivalent to a cantilever beam; this type of valve easily produces vibration and fatigue damage. The wedge valve is better in the fluid field and the structure. For the high pressure throttle valve, the wedge valve is recommended.

14 Conclusions 4. The shell body of the bottom valve cavity washout occurred in the use of the slope wedge valve. 5. Changing to an arc surface wedge valve, the erosion damage reduces, but the linear adjusting is poor. 6. After changing the wedge surface of the valve core to two slopes, the lack of the plane wedge valve and the arc surface wedge valve is make up better. 7. For the wedge valve that consists of two slopes, converse angle or circular arc should be adopted at the interface of the two slopes in order to reduce erosion to the slope that parallel with the central axial line of the shell body.

15 Thanks


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