Questions about steam throttle orifice plates
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As shown in the figure below, this is a steam heat exchanger, whose function is to heat a medium. The main issue is related to the steam inlet: as shown in the diagram, the steam inlet passes through a pneumatic ball valve. Its function is to allow steam to flow into the heat exchanger and exchange heat with the medium when the heat exchanger is in operation ； When the heat exchanger is not in operation, the ball valve closes to cut off the steam. The client has requested that a throttle orifice plate be added next to the device, so that a small amount of steam can flow in when the heat exchanger is not in use, thereby helping to balance the steam pressure. We are asked to design this throttle orifice plate. May I ask if there is any method for calculating the diameter of such orifice plates, as well as any specific requirements? Thank you!
In my opinion, the reason why manufacturers require bypass flow control is not necessarily to stabilize the steam pressure; this cannot be achieved using flow-limiting orifice plates, unless the total amount of steam used is very small, or the orifice plates are large enough, without considering costs. It is believed that the purpose of installing flow-limiting orifice plates is twofold: 1. To maintain a certain excess amount of steam when the heat exchanger is not in use, thereby preventing the formation of condensation water inside the heat exchanger, which could cause water hammer when it is put back into operation. 2. When the heat exchanger is not in use, maintain a certain excess of steam to keep it at a specific temperature, thereby preventing leaks due to alternating temperatures after it is taken out of service. If this is the reason, the size of the orifice plate should be such that, after the heat exchanger is taken out of service and a small amount of steam passes through it, the temperature of the drainage water is comparable to the temperature when the heat exchanger is in normal operation.