SIMULATION OF WASTE GENERATION DURING START-UP OF AN INTERCONNECTED PROCESS NETWORK

B.B. Patel, S.T. Chou and L.T. Fan

ABSTRACT

During start-up, an interconnected process network, e.g., a network of chemical reactors, often generates an appreciable amount of product or products that do not meet the specifications and thus should be regarded as waste to be treated or reprocessed. Moreover, if a hazardous or toxic component is contained in the product, its accumulation may be such that it poses a high environmental or health risk. Naturally, it is desirable that this accumulation be minimized. To devise an optimal start-up strategy for the process requires an understanding of its transient behavior for various modes of start-up.

For illustration, the start-up characteristics of a system comprising three continuous stirred tank reactors (CSTR's) connected in series are examined in this work through computer simulation. Specifically, the transient characteristics of a numerical example are considered under three modes of the start-up, i.e., series, batch and parallel; in addition, the rates at which the waste or off-spec product accumulated and the total amount of this waste are evaluated. The example involves the simultaneous and sequential reactions of the 1.5th and 2nd orders under isothermal conditions.

KEY WORDS

start-up, process network, hazardous waste

This paper is from the Proceedings of the 10th Annual Conference on Hazardous Waste Research 1995, published in hard copy and on the Web by the Great Plains/Rocky Mountain Hazardous Substance Research Center.