editorial
Chemical technology without pollution
Design of an efficient chemical process should proceed on the basis that by-products are not necessarily wastes
L
egal restrictions on air and water pollution in recent years have produced a chorus of objections from some sectors of the chemical industry. The main point made in these objections has been that adding equipment to a plant to stop noxious waste products from getting into the air and natural waters just increases the already considerable manufacturing expense without adding one cent to the market value of the particular chemical product being made. We are faced with a situation in which most currently operating plants have no integral barriers to pollution; these barriers have to be added on, at which time we often launch into interminable arguments over who will pay for them. But it is only fair that customers should pay at least part of the price, for they, as well as manufacturers, must share responsibility for the long-standing practice (or more accurately, perhaps, the habit) of considering potential pollution problemsif at all-only after a process has been designed and not before. Most chemical processes consist of several steps: most also produce products other than the ones specifically desired-often certain unwanted, dispensable wastes. Therefore, it seems propitious to look at a number of alternative processes with a view to finding one which produces finished products, all of which can be sold or used, but does not produce waste products. either finally or at intermediate stages. Unfortunately. conventional economics have not encouraged this latter approach. It is only recently, for instance, that the
manufacture of sulfuric acid from certain stack gases relatively lean in sulfur dioxide or hydrogen sulfide has been considered economically feasible. Growth of such activity is an encouraging sign and is appearing none too soon; a sobering thought, however, is that it has taken legal duress to produce even this advance. Efficient use of the raw materials and products of a chemical process not only is necessary to avoid filling the environment with wastes, it is a good opportunity for engineering to show its most creative face. What is needed in the chemical industry is a commitment on the part of the process designer (backed by the consumer) to consider all the implications of a particular process, and not just to focus on making so many pounds per hour of the desired chemical. Since pollution will be tolerated less and less as t i r e goes on, now is the best time to start with a new philosophy. After all, it wasn’t long ago that designers designed their plants to run only at steady-state conditions. The birth of modern, sophisticated process control systems soon made the designer aware of the need to plan for changing plant conditions and, therefore, to know intimately the dynamic characteristics of his plant. Now, such considerations are among the first a designer r u s t study. Why couldn’t it be the same with respect to efficient utilization cf all participating chemicals in a commercial process? We can have profitable chemical technology without pollution, especially if we, as customers, demand it.
Volume 3, Number 6, June 1969
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