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Spring loaded PSV model A spring loaded pressure safety valve is a conventional pressure relief valve which is designed to open at a predetermined pressure and protect a vessel or system from excess pressure by removing or relieving fluid from that vessel or system. Figure 1 shows the half 3-D model of the spring loaded PSV studied in this research. It mainly consists of six parts: valve body, bonnet, nozzle, adjusting ring, movable valve disc and compressible spring. The operation of this spring loaded PSV is based on a force balance. When the pressure at inlet is below the set pressure, the resultant force on disc is downwards and the disc remains seated on the nozzle in the closed position. As the system pressure increases to the set pressure, the resultant force decreases to zero gradually. When the inlet static pressure rises above the set pressure of this PSV, the resultant force increases reversely, and the disc begins to lift off its seat. However, as soon as the spring starts to compress, the spring force increases, this means that the system pressure 

Spring loaded PSV model A spring loaded pressure safety valve is a conventional pressure relief valve which is designed to open at a predetermined pressure and protect a vessel or system from excess pressure by removing or relieving fluid from that vessel or system. Figure 1 shows the half 3-D model of the spring loaded PSV studied in this research. It mainly consists of six parts: valve body, bonnet, nozzle, adjusting ring, movable valve disc and compressible spring. The operation of this spring loaded PSV is based on a force balance. When the pressure at inlet is below the set pressure, the resultant force on disc is downwards and the disc remains seated on the nozzle in the closed position. As the system pressure increases to the set pressure, the resultant force decreases to zero gradually. When the inlet static pressure rises above the set pressure of this PSV, the resultant force increases reversely, and the disc begins to lift off its seat. However, as soon as the spring starts to compress, the spring force increases, this means that the system pressure 

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Conference Paper
Full-text available
We describe the dynamic analysis of a spring-loaded pressure safety valve (PSV) using a moving mesh technique and transient analysis in computational fluid dynamics (CFD). Multiple domains containing pure structural meshes are generated to ensure that the correlative mesh could change properly without negative volumes. With a geometrically accurate...

Contexts in source publication

Context 1
... to open at a predetermined pressure and protect a vessel or system from excess pressure by removing or relieving fluid from that vessel or system. Figure 1 shows the half 3-D model of the spring loaded PSV studied in this research. It mainly consists of six parts: valve body, bonnet, nozzle, adjusting ring, movable valve disc and compressible spring. ...
Context 2
... is observed clearly, this is possibly due to the vortex shedding, which is closer proximity to the bottom of disc during this period, but far from it when the disc is at a bigger lift. The results show a well-proportioned drop in the flow rate and pressures except that during the open and closure stage, which is agreement with the real situation. Fig. 11 indicates the pressure change as a function of time. Red line and black line represent the absolute pressure at monitor point and the average absolute pressure in the vessel, respectively. It shows that there is a noticeable difference between the average pressure in vessel and pressure at the monitor point when the valve opens a big ...
Context 3
... pressure. When the valve opens a big lift, the velocity passing though the monitor point is very noticeable, but very little when the valve is re-closed. In addition, the fluctuation of the pressure at monitor point during the re-closure is possibly due to the surge or hammer phenomenon when the valve disc alters the motion direction suddenly. Fig. 12 shows the relation between flow rate and pressure drop. By plotting flow rate as a function of pressure drop, the flow coefficient, i.e., the relation between the flow rate and upstream pressure can be calculated and understood clearly. Since the vibration during open and closure process is very strong, calculating the flow coefficient ...
Context 4
... small gap/lift of 0.4mm like the initial lift of 0.6mm is left to ensure the flow field continuous. From about 2.1s on, the valve disc remains at this lowest lift, because the resultant force is never bigger than zero. A notable intense oscillation of the force induced by the air flowing is observed clearly, this is possibly due to the vortex shedding, which is closer proximity to the bottom of disc during this period, but far from it when the disc is at a bigger lift. The results show a well-proportioned drop in the flow rate and pressures except that during the open and closure stage, which is agreement with the real situation. Fig. 11 indicates the pressure change as a function of time. Red line and black line represent the absolute pressure at monitor point and the average absolute pressure in the vessel, respectively. It shows that there is a noticeable difference between the average pressure in vessel and pressure at the monitor point when the valve opens a big lift, but no after re- closure. This is because that, the pressure calculated is the static pressure but not the total pressure. When the valve opens a big lift, the velocity passing though the monitor point is very noticeable, but very little when the valve is re-closed. In addition, the fluctuation of the pressure at monitor point during the re-closure is possibly due to the surge or hammer phenomenon when the valve disc alters the motion direction suddenly. Fig. 12 shows the relation between flow rate and pressure drop. By plotting flow rate as a function of pressure drop, the flow coefficient, i.e., the relation between the flow rate and upstream pressure can be calculated and understood clearly. Since the vibration during open and closure process is very strong, calculating the flow coefficient during the two stages is meaningless. Hence, only flow coefficient for the maximum lift is calculated as ...
Context 5
... small gap/lift of 0.4mm like the initial lift of 0.6mm is left to ensure the flow field continuous. From about 2.1s on, the valve disc remains at this lowest lift, because the resultant force is never bigger than zero. A notable intense oscillation of the force induced by the air flowing is observed clearly, this is possibly due to the vortex shedding, which is closer proximity to the bottom of disc during this period, but far from it when the disc is at a bigger lift. The results show a well-proportioned drop in the flow rate and pressures except that during the open and closure stage, which is agreement with the real situation. Fig. 11 indicates the pressure change as a function of time. Red line and black line represent the absolute pressure at monitor point and the average absolute pressure in the vessel, respectively. It shows that there is a noticeable difference between the average pressure in vessel and pressure at the monitor point when the valve opens a big lift, but no after re- closure. This is because that, the pressure calculated is the static pressure but not the total pressure. When the valve opens a big lift, the velocity passing though the monitor point is very noticeable, but very little when the valve is re-closed. In addition, the fluctuation of the pressure at monitor point during the re-closure is possibly due to the surge or hammer phenomenon when the valve disc alters the motion direction suddenly. Fig. 12 shows the relation between flow rate and pressure drop. By plotting flow rate as a function of pressure drop, the flow coefficient, i.e., the relation between the flow rate and upstream pressure can be calculated and understood clearly. Since the vibration during open and closure process is very strong, calculating the flow coefficient during the two stages is meaningless. Hence, only flow coefficient for the maximum lift is calculated as ...
Context 6
... this paper, the dynamic analysis of an individual spring load PSV is extended, the similar approaches involving DDM, domain interface, moving grid and CEL used previously [19] are utilized again. Differently and importantly, instead of giving a static pressure condition at the inlet of the valve, a high- pressure vessel is added to provide a comparatively real inlet condition, which means that this paper presents a study of a simple system including a high-pressure vessel and a spring loaded PSV rather than a PSV itself. In addition, a variable time step setting is adopted to ensure the convergence as well as save computational time. With such treatments, the whole exhausting process from the valve opening to valve re-closure is monitored, and several important parameters such as displacement and velocity of valve disc, flow mass through the valve, blowdown of the valve are obtained. Especially, a strong oscillation phenomenon is first observed during the re-closure of this valve by using CFD method. Compared with the research of individual spring loaded PSV, this work gives a deeper insight on the fluid flow behavior and performance of the type PSV mounted on a high-pressure vessel. designed to open at a predetermined pressure and protect a vessel or system from excess pressure by removing or relieving fluid from that vessel or system. Figure 1 shows the half 3-D model of the spring loaded PSV studied in this research. It mainly consists of six parts: valve body, bonnet, nozzle, adjusting ring, movable valve disc and compressible spring. The operation of this spring loaded PSV is based on a force balance. When the pressure at inlet is below the set pressure, the resultant force on disc is downwards and the disc remains seated on the nozzle in the closed position. As the system pressure increases to the set pressure, the resultant force decreases to zero gradually. When the inlet static pressure rises above the set pressure of this PSV, the resultant force increases reversely, and the disc begins to lift off its seat. However, as soon as the spring starts to compress, the spring force increases, this means that the system pressure has to continue to rise before any further lift can occur, and for there to be any significant flow through the valve. The additional pressure above the set pressure is called the overpressure. The allowable overpressure depends on the standards being followed and the particular application. For compressible fluids, this is normally between 3% and 10%. After opening, the valve will close when the system pressure drops sufficiently below the set pressure to allow the spring force to overcome the summation of fluid forces surrounding the disc. The pressure at which the valve re-seats is the closing pressure, and the difference between the set pressure and the closing pressure is blowdown. Commonly, the blowdown should be below 10% for compressible fluid. Figure 2 shows the typical disc travel from the set pressure to the maximum relieving pressure during the overpressure incident, then to the closing pressure during the blowdown. ...

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... In this paper, a relatively mature standard model is used for numerical simulation [1][2]. In standard turbulence k-ε model, turbulent kinetic energy k and turbulent kinetic energy dissipation rate transport equation ε can be expressed as,  Continuity equation ...
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