Normal Operating Configuration

Define the equipment configuration. What valves are open or closed What are the liquid levels Is this a normal operation state ... 

Equations (8.32) and (8.33) describe what we call the normal or no failure operation of the system of interest. The problem of failure detection is concerned with the detection of abrupt changes in a system, as modeled in Eqs. (8.32) and (8.33). Changes in (8.33) will be referred to as sensor failures. The main task of failure detection and compensation design is to modify the normal mode configuration to add the capability of detecting abrupt changes and compensating for them. In order to do that, we need to formulate what is called the failure model system ... 

A pair of scrubbers operated alternately. In the normal configuration the scrubbers are operated in series. As the caustic in the upstream scrubber becomes depleted it is taken off line and the remaining scrubber becomes the prime tower. The off-line scrubber has the hypochlorite-laden inventory discharged to be replaced with fresh caustic, and is then brought back online as the downstream tower. This will be referred to as batch operation. The minimum changeover frequency in normal operation is probably less than a day. 

Analysis of various tj s of industrial classifiers has led to the observation that the sharpness index is essentially constemt for a classifier (with a fixed geometrical configuration) over its normal operating range. Assuming that bypass is minimal, only two things affect the size distribution of the fine stream the size distribution of the feed and the cut size. Hence, if the size distribution of the feed is constant, only the cut size (c 5o) will affect the size distribution of the fines. Bypass can be minimized by proper design and operation of the classifier. 

These trickle bed reactors normally operate in the downflow configuration and have a number of operational problems, including poor distribution of liquid and pulsing operation at high liquid and gas loading. Scale-up of these liquid-gas-solid reactors is much more difficult than for a gas-solid or gas-liquid reactor. Nevertheless, the downflow system is convenient when the bed is filled with small catalyst particles. And, because the catalyst particles are free from diffu-sional limitations, these reactors are quite effective as filters of the incoming feed. Any suspended fine solids, such as fine clays from production operations, accumulate at the front end of the bed. Eventually, this will lead to high-pressure differentials between the inlet and outlet end of the reactor. 

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