Waste Minimization

Figure 3.11.10 summarizes a suggested approach for applying pinch technology to environmental problems (Spriggs, Smith, and Petela 1990). Waste minimization is clearly the place to start. Solving environmental problems at the source is not always the simplest solution, but it is usually the most satisfactory solution in the long term. Reducing the problem at the source by modifications to the process reaction and separation technology has the dual benefit of reducing raw material and effluent treatment costs.

Once the design engineer has exhausted the possibilities for waste minimization by process modifications, the

FIG. 3.11.8 Example process.

orator which operates at 2 bars. The 2-bar steam produced in the evaporator can then be used to heat the reactor. Thus, the company could use the evaporator to increase product recovery and eliminate the effluent without any increase in energy costs.

Of course, to make this design work in a batch plant the operations must be sequenced in such a way that the evaporator is running at the same time that the reactor is being heated. In practice, this sequencing is easily achieved. The resulting process modification is a more cost-effective means of waste minimization than those developed without pinch technology and has the added benefit of enhanced product recovery.

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