Industry Market Trends

Reducing Manufacturing Waste, the Dupont Way

Dec 17, 2001

Process and utility waste can take huge bites out of a manufacturer´s profits, and traditional problem solving has failed to minimize the problem. A Dupont developed methodology claims to have a better way of identifying improvement areas.

When a process engineer enters the business world, a senior engineer usually shows him or her the ropes. In a few years, the young engineer absorbs the rules of the old guard and then continues to analyze problems in the same way as was done in the past. Unfortunately, the old ways of analyzing problems, particularly in regards to pinpointing and minimizing waste, are not always the best ways. To fill the vacuum left by outdated methods, Dupont has developed a methodology that systematically identifies opportunities to reduce the amount of waste that the manufacturer generates. It does this by examining the waste generation process in reverse, starting with the waste streams and working back to their source, asking essential questions at each step as to how the waste may be minimized or eliminated altogether. The methodology acts as a screening tool for potential waste reduction processes, determining which processes are best and where they should be applied.

Reducing waste should be on any manufacturer's list of priorities. There are three basic types of waste produced by the manufacturing process. The first type, process wastes, are those that result from transforming lower-value feed materials into higher-value products. The second type, utility wastes, are those that result from the utility systems that are needed to power the manufacturing process. A third type results from start-ups and shutdowns, maintenance and other offhand operations.

Process wastes are the most costly of the three types and therefore should be the first type that manufacturers attempt to reduce. By minimizing process wastes, manufacturers can lower the cost of making a certain product and also reduce their investment in treating the wastes that manufacturing the product creates. Furthermore, utility wastes, which can take the form of released steam, an inefficient boiler, or air and nitrogen leaks, has a direct correlation with how much process waste is produced.

The Dupont methodology analyzes each waste stream in four steps. The first step is to list all of the waste stream's components. Secondly, the components triggering the concern should be identified, including hazardous air pollutants and carcinogenic compounds. Third, the highest volume materials (which are often diluents such as air, water, a carrier gas or a solvent) must be identified. These materials often control the investment and operating costs associated with end-treatment of the waste streams. The source of these diluents within the process must be determined and then waste minimization options must be developed to reduce or eliminate them entirely. The fourth step is to identify the next set of components that has an impact on the investment and operating costs of the end-treatment.

The ultimate goal of the methodology is to guide the manufacturer to a state of efficiency in which all of the materials that are added to or removed from a process are valuable. In order to do this, the raw materials that the manufacturer uses, the intermediates, or the products themselves, must perform the functions previously performed by input streams such as air, water and other catalysts. To come closer to achieving this ideal, the manufacturer needs to undertake a process analysis. The first step in this process analysis is to list all salable products, all raw materials reacting to salable products and any intermediates. The second step of the process analysis is to enumerate all of the other materials created in the process, such as non-salable byproducts (waste), on a second list. Third, for each compound in the second list, the process engineer should ask, "how can we use a material from the first list to do the same function?" or "how can we modify the process to eliminate the need for this material?" Finally, in considering the materials in the second list that result from producing non-salable products, the process engineer should ask, "how can we modify the chemistry or process to minimize or eliminate these wastes?" This method of analysis, when correctly used in collaboration with the application of fundamental engineering and chemical practices, can help in developing a technology plan for achieving a manufacturing state that generates the minimum amount of waste.

The beauty of the Dupont methodology is that it uses a minimum amount of time and money to define process improvements and to conduct baseline analysis. In addition, it uses existing process information to define process improvement opportunities and process characteristics. And, last but not least, it has been proven to work.

Source: Process Analysis via Waste Minimization: Using Dupont's Methodology to Identify Process Improvement Opportunities
Environmental Progress, Nov. 30, 2001
http://www.aiche.org/envprogress/