Recipe stage, chemical process

In general, hazard identification criterion represents the deviation of one or more measured variables from specified values. This is the basis upon which a significant percentage of risk analyses are done. For a chemical process, a number of measurable variables, physical properties, and states or positions of various parts of the overall equipment, e.g., pumps, valves, and motors, can be specified for every time or phase of the process. Certain deviations from the "standard" recipe or settings can then be defined in advance as hazardous, and thus can be used for initiation of an alarm at the early stage of a runaway or upset condition. 

The example is taken from a polymerization batch process and has also been referred to previously by Dahl et al. [1999] and Kosanovich et al. [1996], The dataset consists of 50 batches from which eight process variables are measured over approximately 120 time intervals. From this set of batches, two quality variables on the final product were also available. Both process and quality variables are listed in Table 10.7. The reactor in this chemical process (see Figure 10.26) converts the aqueous effluent from an upstream evaporator into a polymer product. The reactor consists of an autoclave and a cooling/heating system. It also has a vent to control the vapor pressure in the autoclave. The recipe specifies reactor and heat source pressure trajectories through five stages. 

In order to illustrate the approach, a case study is considered. The case study is a multi-stage multiproduct chemical batch plant demonstrator with a plant topology similar to flexible flow shops. Two recipes to produce the end-products are given. The end-products blue (B) and green (G) are produced from three raw materials, yellow (Y), red (R) and white (W). Each batch of the product results from two batches of the raw materials. The production process considered is two batches of material Y and W reacts to produce one batch of B similarly two batches of R and... 

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