Typical examples of stepwise regulation
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That is a typical example of one with step adjustment. Those who find it convenient can share.
For the temperature control of the jacket water in PVC polymerization reactors, our factory uses two control valves with diameters of DN80 and DN200 to achieve stepwise regulation. At the initial stage of the reaction in the reactor, the DN80 control valve is used to regulate the temperature; after two hours, when the reaction intensifies, the DN80 valve is fully opened, while the DN200 valve opens in response to changes in the reactor temperature. This functionality is achieved through the positioners attached to the valves – for the DN80 valve, full closure is achieved at a signal range of 12–20 mA, and for the DN200 valve it is 4–12 mA; both valves are of the air-operated type.
It can be sealed with nitrogen or fuel gas, and controlled either by step control or by a self-acting control valve; it is equipped with a pressure relief valve and a make-up valve, one of which operates on an air-open principle and the other on an air-close principle