Detailed discussion on three impulse control
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In the three-input control for boiler level, the flow rate of medium-pressure steam generated in the boiler is used as a feedforward control mechanism to convert the volumetric flow rate into a mass flow rate, expressed in tons per hour. The inflow water flow rate is also expressed in tons per hour. In theory, this setup should allow for automatic control. Do experienced users know of any other potential issues? I hope we can have a thorough discussion on the three impulses.
Boiler three-variable control is a control system in which the liquid level serves as the primary control parameter, with the feedback feedwater flow signal and the feedforward steam flow signal acting as secondary control elements; it is a cascade control system...
First and foremost, it should be clear that not all drum level controls require three impulses; the decision needs to be based on specific circumstances. For example, with small steam drums, since their capacity is low, there is no need for 3 impulse systems, and even if such systems are installed, they cannot be used in automatic mode – this is something I have experienced firsthand. Generally speaking, large-capacity drum boilers are suitable for three-pulse control. In addition, there are those with 2 impulses, and it is determined based on specific circumstances. The essence of 3 impulses is feedforward (steam volume) – cascade (level and feedwater volume) control.
Right. Those that require three impulse adjustments – I’m not sure if they are all in use properly.