What does the ZT equation on the DCS screen in an ethylene plant mean?
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What does “ZT 26%” mean next to the valve in the DCS display? Is it the valve opening degree? On the mechanical display of the compressor, there are instrument readings marked with JI and *. What do these mean? What are their functions?
26 should be the valve opening degree, while JI is the turbine power calculated based on the amount of steam entering the turbine and its rotational speed. Some turbines these days will shut down via interlock when the HP opening is greater than 30%, but the actual power is lower than the specified value. *Should it be V* and VYI: vibration. There should also be ZI, axis displacement.