Condensing economizers for efficiency improvement and emissions control in industrial boilers

Conference · Sat Jun 01 00:00:00 EDT 1996

OSTI ID:244535

Butcher, T A; Litzke, W L ^[1]; Schulze, K; Bailey, R ^[2]

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1. Brookhaven National Lab., Upton, NY (United States)
2. Babcock and Wilcox Co., Lynchburg, VA (United States). Research and Development Div.

Condensing economizers recover sensible and latent heat from boiler flue gas, leading to marked improvements in thermal efficiency. This paper summarizes the current commercial status and continuing development efforts with one type of condensing economizer. In this design Teflon{reg_sign} covered tubes and enclosure walls are used to handle the corrosive condensate. Flue gas flows around the tubes and feed water, being heated, flows through the inside. In addition to improving thermal efficiency, condensing economizers can also be used to reduce particulate emissions primarily by inertial impaction of particles on tube surfaces, water droplets, and added impactors. Collected particles are then removed with condensate. Water sprays directly on the tubes can be used to enhance particle capture. With coal-firing, tests have shown particle removal efficiencies as high as 98%. To enhance the emissions control potential of condensing economizer technology a two-stage economizer system concept has been developed. Two heat exchanger modules are used. The first is a downflow design and recovers primarily sensible heat from the flue gas. The second is upflow and recovers mostly latent heat. Condensate is collected in a transition plenum between the two stages. This configuration, termed the Integrated Flue Gas Treatment System, provides great flexibility for implementing emissions reduction strategies. Particulate emissions can be reduced without impacting sensible heat recovery by recirculating collected condensate to spray nozzles at the top of the second stage heat exchanger. In tests at BNL with heavy oil firing, particulate reductions over 90% and final emission rates on the order of.005 lb/MMBtu are achieved. Adding sorbents to the recirculated condensate reduces sulfur dioxide emissions and SO{sub 2} removal efficiencies over 95% are achieved. Also, condensing economizers show great potential for the removal of certain air toxics such as mercury and nickel.

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 244535
• Report Number(s): BNL-62939; CONF-9606183-1; ON: DE96009691; TRN: AHC29613%%10
• Resource Relation: Conference: Combustion Canada 1996, Ottawa (Canada), 5-7 Jun 1996; Other Information: PBD: [1996]
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
01 COAL, LIGNITE, AND PEAT
02 PETROLEUM
ECONOMIZERS
PERFORMANCE
DESIGN
BOILERS
THERMAL EFFICIENCY
FLY ASH
AIR POLLUTION CONTROL
LIGNITE
FUEL OILS
COMBUSTION
WASTE HEAT
HEAT RECOVERY
FLUE GAS
VAPOR CONDENSATION
SULFUR DIOXIDE
MERCURY
NICKEL
CHROMIUM
LEAD
CADMIUM
ZINC