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Show One of the greatest problems being experienced in our mills is lack of adequate preventive maintenance. Frequently maintenance is by disaster. Only when the equipment breaks down do we react and make adequate corrections. It is imperative that more attention be paid to proper servicing of control systems such as pressure and ratio control. On high temperature operations in the order of 2400F, relatively minor variations in fuel/air ratio can increase fuel consumption dramatically. Figure 18 illustrates the increase in fuel consumption that could be expected where ratio is permitted to deviate from set norms. Where fuel/air ratios are permitted to move into the substoichiometric area additional problems of tight scale or rolled in scale can be encountered with the potential of the product being scrapped or downgraded. Marking or gouging of slabs in pusher furnaces can, in large measure, be eliminated by use of the walking beam furnace but with the disadvantage of increasing the total area of water cooled members in the furnace to support the charge. BATCH TYPE FURNACES Batch furnaces are used for a variety of heat and heat treat operations within the steel industry. Past practice has frequently dictated that sections to be heated are charged directly to the hearth of such furnaces. In many cases large temperature differential in the pieces resulted, such that cracks occurred in the finished product or non-uniform metallurg:i.cal results. In most cases, particularly where metal sections of greater than four inches were involved, it is highly desirable to present heat to both sides of the piece to attain adequate temperature uniformity as illustrated in Figure 19. Specifications by both industry and governmental agencies on both forging and heat treat heating standards are becoming ever more demanding. Our operating practices of the past must be critically reviewed if we are to meet these requirements. To achieve product temperature uniformity it has been practice until recent times to use excess air firing in such furnaces. This practice is no longer acceptable based on the resultant high fuel consumption. Pulse firing of such furnaces was developed in Europe where good results were attained. The same good results were not as broadly attained in the United States, possibly due to lack of maintenance and care for the process on the same basis as would be standard practice there. In this procedure the burner systems were fired at near stoichiometric ratio at all times but only for that period of time in any minute required to hold temperatures to control level. By this means high recirculation rates were achieved in the combustion chamber to attain temperature uniformity at minimum fuel cost. For such furnaces today, the use of regenerative burners, developed with the assistance of G. R. I. can 16 achieve spectacular uniformity and at efficiency rates in many cases to levels of 70 to 80 percent. INDIRECT FIRED - BATCH AND CONTINUOUS FURNACES Great strides are being made again through the use of the regenerative burners on radiant tube applications for both batch and continuous furnaces. In these furnaces radiant tubes are utilized so that special atmospheres can be maintained in the furnace chambers to protect the products being processed or to, in some cases, change its chemistry or metallurgical properties. Reductions in fuel usage of 50 percent from standard operating conditions are frequently achieved. CONCLUSION Few new facilities or major furnace installations are likely to be built in the next few . years in the major integrated steel mills. Efforts will be made to improve operating efficiencies on existing equipment and to improve product quality. More obsolete equipment will be scrapped or replaced such that in the next very few years the industry will have achieved at least relative parity in operating efficiency with competitive foreign producers. In many installations in the industry today, we know the steps that must be taken to improve both the operating economics of heating processes but also to provide high quality heating of the product. In many cases the limitation is the availability of funds to carry out the project. The prime areas where mprovement in industrial furnace design and efficfency are required- include the following: 1. 2. 3. 4. 5. Furnace enclosures must be maintained as tight as possible to reduce infiltration or sting out to the maximum degrees. Proper pressure control is imperative to reduce furnace losses and to help control furnace atmosphere and, thus, in many cases its effect on product quality. Suitable ratio control equ:ipment is a must to gain control of the furnace atmosphere but also to optimize fuel consumption. It is not uncommon to see furnaces ~~re new, proper ratio equipment can reduce fuel consumption by values in excess of ten (10) percent. Flame quality can be a very important factor in optimization of furnace operation. The flame shape and quality as well as its color can make substantial differences in overall furnace operation fuel economics and product quality. ' The preheating of combustion air in the lower temperature rapges as has been |