Adjustment accuracy
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This post was last edited by yiyuguchen on 2019-8-28 at 17:14. The shell side of the heat exchanger is heated with steam; in order to control the temperature of the material exiting the exchanger, the amount of steam used is regulated. Parallel control valve assemblies are installed in the steam pipeline to achieve high-precision control. Is this a viable approach?
Automatic control can be achieved by regulating the steam flow rate
Parallel control valves installed on the steam pipeline? How to connect in parallel? Is the steam inlet connected in parallel with the condensation outlet?
It is connected in parallel on the steam inlet pipeline
This control scheme actually adjusts the steam inlet flow rate on the shell side of the heat exchanger to control the outlet temperature of the material. This solution is often used when it is not feasible to directly throttle the steam pipeline. It should be noted that when the steam inlet flow rate is low, the control is quite sensitive; however, when the steam inlet flow rate is high, the control sensitivity decreases, and the control becomes less sensitive. If the control valve is installed on the parallel bypass pipe of the steam pipeline, reducing the opening of the control valve increases the steam flow rate entering the heat exchanger. If the opening degree of the control valve is already very small, the control becomes highly insensitive at this point.
It is possible to design proportional control for the large and small valves; this type of application is quite common.