Conceptual design of multistep reaction processes.

摘要

Many of the chemical routes that are proposed for making commodity and specialty chemicals are characterized by a large number of reaction steps with separations required between these steps. A hierarchical decision procedure has been developed for the conceptual design of multiple reaction step processes from the petrochemical, specialty chemical, and agrichemical industries.; The major interactions among the individual plants within a process are identified at the higher abstraction levels of the procedure. Each plant in the process can have more than one supplier plant and can supply more than one plant. Alternative chemistry routes for the production of the desired product of the process or any of the plant intermediates can be integrated and compared within the same process. Balanced processes characterized by very tight interactions among the plants have also been examined. The procedure draws upon an extended set of heuristics that guide the decision-making. A new approach has been used for the calculation of the material balances for the overall process in terms of the dominant design variables, which are determined automatically. The raw material and waste treatment costs, the profits from valuable byproducts, and the costs of the reactor systems and gas compressors are incorporated in the economic evaluation of each process. The sensitivity of the economic potential on the design variables is investigated and the significant economic trade-offs are identified.; Object-oriented and rule-based programming techniques have been used for the implementation of the procedure in PIP II, a computer program that allows a design engineer to rapidly generate potentially profitable process alternatives and estimate the optimum design conditions for each flowsheet. The hierarchical decomposition of the design problem and the systematic nature of the procedure considerably limit the number of alternatives that need to be examined and facilitate their screening.; The procedure and PIP II have been successfully tested on the design of fifteen processes. Examples are: the production of vinyl chloride mononer via chlorination and oxychlorination of ethylene; the production of adipic acid from butadiene and methanol (BASF process); the production of adiponitrile by butadiene hydrocyanation (DuPont process) as well as via adipic acid.