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M9.2 Process Model

The relationship between feed-water flow rate and drum level for the process studied in this module is

Equation M9.1

graphics/m09equ01.gif


Assume that the valve transfer function is

Equation M9.2

graphics/m09equ02.gif


the unit of time is minutes, and the input and output have been scaled so that the full range is –1 to 1, with a nominal value of 0. The constraints on the inputs and outputs are then -1 and 1.

Now consider process disturbances. The primary disturbance (header pressure) affects the drum level in the following fashion

Equation M9.3

graphics/m09equ03.gif


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