Regarding humidity controllers
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I am currently working on a flue gas desulfurization project. The simple process flow is as follows: the flue gas (which contains SO2, O2, and inert gases) has its humidity increased by injecting low-pressure steam, after which it enters the desulfurization tower where it reacts to form dilute sulfuric acid, thereby achieving flue gas desulfurization and resource recovery. Current process requirements specify that a humidity meter should be installed on the flue gas pipeline, with the humidity level to be no lower than 3%. I would like to ask experienced designers whether such a humidity level can meet these requirements
The humidity isn’t that high; since low-pressure steam is being introduced, the humidity should be at least 50%. In southern provinces such as Guangdong and Guangxi, the air humidity is generally around 50%, and in some high-pressure chambers where dehumidifiers are used, the air humidity is even 45%.
I also want to ask whether there is a control scheme that uses a humidity transmitter to regulate control valves, as I haven’t seen one before; commonly, temperature transmitters are used for such control. But the process only requires humidity and not temperature.
Of course, the humidity can be adjusted by regulating its steam output!
Any parameter that can be detected by instruments can be controlled (the process provides a way to modify these parameters)