Instrumentation system cascade problem
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Gentlemen, I would like to ask: in the cascade control system of a heating furnace, where the secondary loop is controlled by gas pressure, should the primary loop be based on furnace temperature or on the temperature at the furnace outlet?
Haiyou, the outlet temperature of the heating furnace is the main circuit.
The outlet temperature is the adjustment target for the main circuit
Dear Haiyou, let me explain it in detail: First of all, any change in gas pressure is immediately reflected in the temperature of the heating furnace’s furnace chamber. In other words, if the pressure fluctuations are frequent but of small amplitude (i.e., the interference is minimal), the secondary circuit composed of gas pressure P and PRC2 can ensure that the furnace chamber temperature remains constant； If the interference is significant or for some other reason, the furnace temperature does not change immediately, but the outlet temperature does change; in such a case, the combination of the outlet temperature T and TRC1 forms the main control loop, which immediately provides a set value for the secondary loop so that it can adjust promptly and maintain stable outlet temperature ； If disturbances act on both circuits simultaneously, they will balance each other out, ensuring efficient regulation. So this is why the outlet temperature is chosen.
The book always mentions outlet temperature: hug::victory:
I’m foolish, am I not? In this cascade system, is the main loop the outlet temperature, and the secondary loop the gas system?