Does the water-side system of the heat exchanger require a control valve on each side, upstream and downstream of the heat exchanger?

Thread Content

This post was last edited by FionaGEJU on 2017-11-15 at 22:52. In a gas turbine (with natural gas as the primary fuel) combined cycle power plant, there is a heat exchanger in the natural gas system; the heat source is hot water from the medium-pressure stage of the waste heat boiler, and the return water goes to the condenser. The process flow of the hot water system for this heat exchanger is shown in the figure below. In the system, a control valve is installed upstream and downstream of the heat exchanger (indicated by circles in the diagram). According to the plant’s specialists, the downstream control valve is used to regulate flow, while the upstream control valve serves to stabilize pressure. Both valves are actually globe valves. My question is, why is it necessary to have a control valve at both the upstream and downstream sides? Is it possible to have one only on the downstream side or one only on the upstream side? I would appreciate some guidance from the experts here. PS: This heat exchanger is a shell-and-tube type heat exchanger. The feed water for the medium-pressure stage of the waste heat boiler has a pressure of approximately 4.5 MPa and a temperature of 150 degrees Celsius, with a hot water flow rate of around 80 t/h. Uh. . Why can’t I upload pictures today? . Well, the image can be found at the link below: https://pan.baidu.com/s/1geHWxqF