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Show INSENSITIVITY In addition to the major advantage of higher fuel savings, the basic design and operati'ng characteristics of the Regenerative Burner provide lack of sensitivity to its operating env ironment. There are no boundaries between air and waste gas streams to be maintained against leakage and the materials have been chosen to withstand the corrosive effects of exhaust gas borne volciti les. reGen has proven capabi I ity of operation with dirty gas streams. Regenerator packing can be easily cleaned of any dirt or condensed fouling - it can be dropped out of the base of the regenerator of an exhausting burner, c leaned and replaced through the top. The first commercial application of the Regenerative Burner, made in February of 1983, demonstrates this property exceptionally well. The furnace is a small glass tank which operates at 1400°C (2550°F). The exhaust gas is heavily contami.nated with corrosive volatiles and batch car ry·.-0ver. Desp i te these contam i nants, the reGer.l has proven to be an extremely efficient firing system. The regenerators are kept at their peak of performance by a monthly cleaning, taking about 50 minutes, without shutting down the system. The reGen has been in operation in secondary aluminum melting since January 1985, with six furnaces retrofitted to date where solid flux is used for skimming, cleaning, and demagging. Cleaning the regenerators of the fouling of condensed flux volatiles involves removing the packing and either water washing or tumbling and screening, the choice of method being largely dependent on site facilities for treating con tam i nated water. In most cases a set of clean packing is available before commencing draining a dirty regenerator, such that the burners need only be shut down for a short period. The highest cleaning frequency needed so far is once each week, on a well charged furnace melting dirty scrap. By comparison, a Regenerative Burner on a furnace in a permanent mold operation where flux is used for c leaning and skimming once per shift is cleaned once every three months. THE "EASY CLEAN - A 1 STYLE" reGen To facilitate the frequent cleaning and provide corrosion resistance, several enhancements were made to the original design to produce a specific unit for aluminum melting furnaces. The burner body and internals were redesigned such that removal ·of a large backplate will allow the ceramic internals to be inspected, removed and cleaned as necessary. The regenerator bodies have large packing drain and recharge doors. The regenerator bases are internally vitreous enamelled and the reversing valve nickel plated to prov ide corrosion resistance. 80 OTHER REGENERATIVE BURNER CHARACTERISTICS The burner is available in high, medium, and low velocity versions for gas, oil or dual fuel operation (including heavy oils and coal tar fue I). The reGen has been proven to give improvements in other aspects of furnace performance such as temperature uniformity, where the "moving heat source" provided by the alternating firing of the burners in a pai r enhances the temperature uniformity and gives improved heat transfer to the charge. The Regenerative Burner uses any standard temperature and fuel/air ratio control system. These are appl ied to the cold side of the system - no hot valving or temperature corrected fJJel/air ratio equipment is required. Furnace pressure is controlled, and the exhaust fan protected, by an automatic valve in the exhaust systan. The Regenerative Burner is a simple system for retrof i t appl icat ions. As each un i t, consisting of a pair of burners and regenerators, can reverse independent of other furnace controls or other pai rs, there is no compl icated piping arrangement requ ired. The Regenerative Burner's exhaust system for clean exhaust gas appl ication is constructed from mi Id steel pipe. The exhaust gas is so cool by the time it has reached the base of the regenerator that standard pipe and fittings are quite adequate to handle it. No special flue ports or refractory lined chimneys are required. Conventional cold combustion air fans are used to provide the exhaust suction. Exhaust system design for aluminum melting has addressed the question of corrosion in a number of different ways - most have had dilution of the exhaust gases prior to the exhaust fan, but on the "dirtier" furnaces the use of an exhauster to take the fu II 260 -315 ° C (500-600° F) Regenerative Burner exhaust is considered beneficial to prevent the possibility of the dilution level allowing the temperature of the gases to fall below the dew pOint with subsequent aqueous corrosion potential. Exhaust piping used for aluminum melting has varied from internally vitreous enamelled carbon steel pipe, fabricated alloy steel ducting and plain carbon steel pipe. Each has its inherent advantages and disadvantages - vitreous enamelling carbon steel pipe negates the possibility of site fabrication - alloy steel choice may be difficult to make if exhaust gas constituents are not qualified and may be subject to change with modified cleaning and degassing practice - plain carbon steel pipe will eventually corrode, but is site fabricable, easily site repairable and cheap to replace. |