Design and Analysis of Feed Check Valve Using CFD Software
Design and Analysis of Feed Check Valve Using CFD Software – Mechanical Project
The Feed check valve is fitted to the boiler, slightly below the working level in the boiler. It is used to supply high pressure feed water to boiler and also to prevent the returning of feed water from the boiler if feed pump fails to work. With rapid advancement in the area of flow simulation, CFD and Numerical technique, the flow characteristics of the feed check valve can be studied effectively. In this paper modeling and 3-dimensional flow simulation of a feed check valve is carried out using SOLIDWORKS™ FLOW SIMULATION software to understand the inside flow characteristics and to determine prominent factors such as Pressure drop, Valve co-efficient. In the final phase, the discharge of the valve for a constant pressure drop of 1 bar is determined and flow patterns are visualized.
A control valve is a mechanical device that controls the flow of fluid and pressure within a system or process. A control valve controls system or process fluid flow and pressure by performing different functions like stopping and starting fluid flow, varying (throttling) the amount of fluid flow, controlling the direction of fluid flow, regulating downstream system or process pressure, relieving component or piping over pressure .There are many valve designs and types that satisfy one or more of the functions identified above. A multitude of valve types and designs safely accommodate a wide variety of industrial applications.
The construction of a feed check valve is shown in the Figure . The feed-water pipe carrying water from the feed pump usually enters the boiler in the water space of the boiler. A valve is placed in the feed pipe to control or regulate the flow of water into the boiler. The valve is attached directly to the boiler front. It is a non-return valve which permits flow of water in one direction only and automatically prevents the back flow of water from the boiler when the feed water pump is not working. The amount of water entering the boiler can be adjusted by controlling the lift of the valve. This valve is known as feed check valve or boiler feed valve.
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The next step after the modeling is to subject the developed model to Computational Fluid Dynamics (CFD) analysis to understand the flow
characteristics inside the valve.
The CFD analysis is carried out in 3 steps-
Obtaining pressure drop curves for volume flow rates 5 m3/hr and 10 m3/hr by varying valve lift from 3mm to 16mm.
From the obtained pressure drop values the valve Flow Co-efficient (Cv) is calculated for different valve lifts from 3mm to 16mm using
conventional valve sizing calculation formula.
In this step, for a constant pressure drop of 1 bar between inlet and outlet, the outlet velocity (V) of flow is measured to calculate the volume
flow rate (Q) which is given by,
Volume flow rate = outlet velocity x area
Q= V x A…………….. (1)
A graph of discharge vs. valve lift characteristic curve for the valve is plotted.
1) The modeling of the feed check valve is done and a method of performing CFD analysis using flow simulation software is shown.
2) The pressure drop curve is obtained for flow rates of 5 m3/hr and 10 m3/hr. The results show that the pressure drop is more for higher flow rates and lower valve lifts.
3) The obtained pressure drop values is used to calculate the flow co-efficient (Cv) for flow rates 5 m3/hr and 10 m3/hr using traditional valve sizing formula for different valve lifts i.e., from 3mm to 16mm. The results show that flow co-efficient increases in a linear fashion with the valve lift.
4) Result of flow simulation is visualized to observe the flow patterns inside the valve. The flow patterns show a rapid increase in the velocity at the valve-valve seat clearance.