12.4. Split-Range Control

A split-range strategy is often used in situations where one or more valves may be used, depending on the operating scenario. An example application is a batch reactor. Batch reactors must often be heated from ambient temperature to a desired operating temperature. Particularly if the reaction is exothermic, then cooling will be needed to maintain the desired reactor temperature. In the split-range control strategy shown in Figure 12-4, if the jacket temperature controller output is between 0 and 50%, the cold glycol valve is open; if the jacket temperature controller output is between 50 and 100%, the hot glycol valve is open. For safety reasons we wish the cold glycol valve to fail-open and the hot glycol valve to ...

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