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Show COMBUSTION SYSTEM REQUIREMENTS FOR ADVANCED GAS-FIRED PROCESSES David F. Knowles Gas Research Institute Chicago, Illinois, USA ABSTRACT Gas Research Institute is supporting the development of innovative advances in the state- of-the-art for natural gas fired industrial process equipment. The keys to maintaining and expanding the competitiveness of gas equipment are improved productivity and flexibility and higher temperature capability. The paper explains specific process developments and describes the advances required in combustion technology. INTRODUCTION INDUSTRIAL PROCESSES many years ago were much simpler than they are today. The technology of the day did not permit complicated production methods. The combustion systems were as simple and unsophisticated as the processes. The burners were often merely holes in the furnace wall with a gas pipe stuck through the back and the control systems were typically totally manual. The heat distribution within the furnace and the air/fuel ratio were often a matter of chance rather than careful design and maintenance. Today, no industry can afford to bank on chance. The demand for sophisticated products with high quality at low cost requires tight control of complicated processes. The combustion system is a key element in these processes, and is increasingly called upon to do more than just burn the fuel with air. The goal of Gas Research Institute is to make gas the least cost energy service option. GRI sponsors research and development projects aimed at upgrading the use of gas in traditional processes and projects which allow gas to enter new markets. The Industrial Utilization Research group of GRI has undertaken an ambitious plan directed at increasing gas use through innovative technologies. The strategy is to take advantage of the unique qualities of natural 323 gas. Natural gas is a premium fuel; it has a high calorific value, a consistent chemistry, is in a gaseous form, and is clean burning. These characteristics make it well suited to a wide scope of industrial applications, including melting, heating, drying and refining. FUTURE COMBUSTION SYSTEMS Combustion systems will be required to operate a higher temperatures and in hostile, corrosive environments. This means 16S00C (30020F) and above for direct fired systems and above 11000C (20120F) for indirect fired systems. The combustion systems must also be capable of utilizing preheated air at 11000C (20120F) or above delivered from a new breed of high temperature heat exchangers. These heat exchangers are essential towards assuring that the gas process maintains its competitive edge in energy costs over other energy options. The combustion systems for advanced processes will need high high fluxes and a wide turndown range. These two features, coupled together, with permit rapid heatup to process temperature and will also allow more compact equipment. In certain applications, such as heat treating, the combustion equipment may have to assist in cooling as well as heating. Equipment compactness generally leads to lower capital costs and will also facilitate its integration into in-line manufacturing. The state-of-the-art in control technology must continue to be advanced to improve accuracy and to provide flexibility. Although the environmental impact of natural gas. combustion is small in comparison to coal or oil, problems still do exist. While the primary pollutant associated with burning gas is nitrous oxide, other gaseous and solid species can evolve with the process itself. Steps must be taken to mitigate these |