LNG용 초저온 스윙체크밸브의 열유동해석

Abstract

As part to reduce environmental pollutants by recent fossil energy, use of natural gas is gradually increasing. LNG natural gas, since the pollution materials generated during combustion as compared to the fossil energy contains less worldwide consumption has been increasing rapidly, currently, even in Asian countries, due to the benefits of these natural gas, tend to have increased usage. 80% of these LNG transport, to one ship LNG carrier requires about 500 or more valves. However, cryogenic check valves to be used in the LNG carrier is dependent on imports for the total amount, it needs domestic production. Swing check valve is located in the flow of the linear fluid, is opened when the flow direction is forward, when the flow is reversed, the valve is automatically closed by back pressure. That is, to prevent backflow, it is one of the check valves most frequently used in industrial sites with a purpose of protecting the pipe system. Operation of the check valves influence on the speed of the general flow, the shape of the turbulent flow, the type of fluid and the like. Therefore, research on the flow inside the valve, is a step for unless always precede for accurate design of the valve. For the swing check valves that are used in general industrial field, but a number of studies relating to the shape and internal flow of the valve has been promoted, but the case for cryogenic temperature swing check valves, fluid engineering study of the internal flow field is almost nil. This can give rise to over-design and anxiety in performance and reliability of the valve. Therefore, in this paper, as a basic research for the domestic production of Cryogenic swing check valve, a study was conducted of the valve internal flow field. The working fluid used in the study, using liquefied methane -165 ℃ (CH4), was simulated by varying separately the opening divergence into four intervals from 0 to 100%. The pressure inside the pipe simulations are 10bar, the inflow velocity of the fluid is 4m/s. The approximate research results are as follows: fluid leaving the valve disk, regardless of the opening divergence, to form a large recirculation zone, to form a very fast flow rate from the edge of the disk. When the opening divergence is smaller, it appears high pressure on the upstream side, this value is relaxed when the opening divergence is large. Flow rate coefficient of the valve shows a larger value as the degree of opening becomes larger, confirming that the check valve used in the study is in the effective flow rate counting range. Pressure loss coefficient of the valve is confirmed to show a small value when opening divergence increases.