Bulletin 4343 Page 3
CONSTRUCTION FEATURES TwinBed II has enhanced rugged construction. Burner and regenerator are separate modules. Angled transitions are available to change burner firing angles relative to regenerator. Burner and regenerator can be rotated for ease of installation. Other improvements include nozzle-mix pilot with flanged mounting. TwinBed II is insensitive to furnace operating environments that can quickly destroy recuperators. There are no boundaries between air and waste gas streams to be maintained against leakage. Materials of construction have been chosen to withstand the corrosive effects of exhaust gas borne volatiles. Regenerators can be easily cleaned of dirt or condensed fouling by dropping the bed support plate and removing bed material through the rear hatch. Clean heat transfer material can be replaced through the top hatch. A regenerator can be cleaned while the other burner in the pair fires direct (a non-reversing mode) to maintain furnace operation.
CONTROLS TwinBed II operates with the same controls (air/fuel ratio, furnace pressure, and flame detection) used with conventional burners. Air/fuel ratio is typically controlled with differential pressures from an orifice plate in the combustion air line and a flow-based fuel rate control system--either regulator or electronic. Typically, about 80% of the furnace gases are exhausted through the regenerators. The remaining 20% passes through a pressure controlled furnace flue. Exhaust flow through the regenerators is controlled by the temperature of the exhaust gases leaving the regenerator. If temperature is too low, the exhaust flow through the regenerator is increased. Furnace pressure is controlled with the flue damper. Logic links from the furnace pressure control to the burner exhaust system prevent excessive pull through the burners which would result in negative furnace pressure. Each burner's flame supervision uses ultraviolet flame detectors on both the pilot and main flames connected to a single flame relay. By switching detector signals when burners alternate firing, the flame relays monitor the main flame of the firing burner and the pilot flame of the exhausting burner.
NATURAL GAS
Basic piping arrangement of two burner TwinBed II system.
PATH SELECT VALVES
GAS CYCLE VALVE
INJECTOR GAS
TwinBed II
BURNER
AIR CYCLE VALVE
REGENERATOR
COMBUSTION AIR FAN
EXHAUST CYCLE VALVE
EXHAUST FAN
COMBUSTION AIR FLOW CONTROL VALVE
EXHAUST TEMP CONTROL VALVE
EXHAUST
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.
CONTACT fna.sales@fivesgroup.com T +1 800 626 3477 - F +1 216 373 4237
Fives North American Combustion, Inc. 4455 East 71st Street - Cleveland, OH 44105 - USA www.fivesgroup.com
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