red world of
edited by
W. C. FERNELUS Kent State University Kern. OH 44242
HAROLD WITTCOFF Koor Chemicals Ltd. Beer-Sheva, Israel P.O.B. 60
Chemical Processing-Batch or Continuous? Part II S. M. Englund 800 Building, Dow Chemical, Michigan Division, Midland, MI 48640
Part I of this article discussed the relative merits and problems of continuous processes and conventional batch processes. Part I1 reports recent developments in batch processing technology that make it attractive for many applications even when continuous processing would be feasihle.
High temperohm initiators
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Longer total hot spct time due m mixsd initiotors
Improved Batch Technology
Several developments have improved the economics of batch processing considerably in recent years. Basically the improvements have increased productivity and safety through automation and process modifications. Automation The redesign of batch processes using computen has revolutionized batch processing. I t has become possible, by use of computers and suitable field equipment, to change batch processing from "person limited" to "equipment limited". "Dead time," the time lost in repeated starting and stopping of batch Drocesses, has been minimized. Short hatch turnaround times (or cycle times)' are now practical since the computer will supervise and actuallv direct all aspects of a batch process, including 1. Preparation of feed materials for loading 2. Loading resetors 3. Carrying out reactions 4. Temperature control 5. Transferring final product to next process stage
6. Cleaning 7. Safety and quality checks
The operator's jobs have not been eliminated; in fact they are higher quality jobs than before. Instead of turning valves and adding chemicals manually, the operator checks to see that the computer programs are doing the job properly and that the process equipment is functioning as it should. Also, the operator now has time to take part in scheduling and planning. Temperature control of hatrh processes has traditionully been difficult because of the unsteady state nature of st~ch processes. With modern control technology, excellent trmperature control ran he achieved. Process Modifications Improved "Conventional Batch Processing" Several methods have been developed to improve productivitv of conventional batch nolvmerization nrocesses. One of t
