Sheet 4343-9 page 2
cycle fired with LNI gas (gas injectors). Whether a TB-II fires with burner gas or injector gas (LNI mode) is controlled by the gas path select valves. The injector gas select valve can only be open if the chamber temperature is above 1450 F and the TB-II is in cycle fire mode. Air/fuel ratio is a flow metered control system that is required because system flow resistance changes as the regenerator temperature changes. Electronic air/fuel ratio control is shown but regulator control may be used. Depending on the system design, each TB-II may have its own ratio control system or a system may be shared as depicted.
The simplified piping schematic shows the basic operation of a pair of TwinBed II regenerative burners. Each TB-II has cycling valves that control flow of gas, air, and exhaust. In the illustration the firing burner (A) has a closed exhaust cycling valve and open gas and air cycling valves for supply of fuel and air. The exhausting TB-II (B) has closed fuel and air cycling valves and an open exhaust cycling valve for removal of furnace gases. During the second half of the regenerative cycle, the firing and exhausting of TB-II's A and B are switched by changing all valve positions. The pneumatic control system shown in the schematic permits cycle firing the pair or direct firing of either or both TB-II's. In the schematic TB-II "A" is firing in burner gas mode but may be
WARNING: Situations dangerous to personnel and property may exist with the operation and maintenance of any combustion equipment. The presence of fuels, oxidants, hot and cold combustion products, hot surfaces, electrical power in control and ignition circuits, etc., are inherent with any combustion application. Components in combustion systems may exceed 160°F (71°C) surface temperatures and present hot surface contact hazard. Fives North American Combustion, Inc. suggests the use of combustion systems that are in compliance with all Safety Codes, Standards, Regulations and Directives; and care in operation.
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Fives North American Combustion, Inc. 4455 East 71st Street - Cleveland, OH 44105 - USA www.fivesgroup.com
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