Research & Development: Small Boiler Simulator

In 2009, B&W commissioned its 6 million Btu/hr Small Boiler Simulator-II (SBS-II) pilot-scale combustion and emissions control test facility in Barberton, Ohio, replacing the original SBS unit that had operated for over two decades at a former site.

Many practical features were implemented in the design and construction of the SBS-II. For example, the furnace and convection tube bank were built with water-cooled jackets and refractory lining to represent the time-temperature profile of a utility boiler.

For added flexibility, the unit was designed to be configurable in the wall-fired and cyclone-fired modes and maintain the ability to burn a wide range of conventional and alternative fuels. One of the facilities unique attributes is the ability to burn fuel with air or oxygen; also referred to as oxy-firing.

Regardless of the firing mode, the combustion products exit the furnace and enter a convection pass where cooling water circulates to the tube banks and walls. After leaving the convection bank, the flue gas is further cooled as it passes through an air heater.

Depending on specific applications, the emissions control equipment can be arranged to mimic the flue gas pathway in different commercial operations. Those components include a selective catalytic reduction (SCR) system, a moving bed SCR system, a wet flue gas desulfurization (WFGD) unit, a condensing heat exchanger, a spray dryer absorber (SDA), and baghouse modules with fabric filters for particulate capture.

If desired, the flue gas can also be diverted to an adjacent post-combustion CO₂ capture pilot plant. Multiple access ports are located throughout the facility for visual observations, in-furnace and in-situ measurements, and extractive sampling. Other major capabilities include:

Pulverizer - A fuel handling system including a dryer, a crusher, weigh feeders, and an MPS-32 mill with a stationary or rotating classifier prepares coals and other solid fuels for combustion. Supportive laboratory measurements are also provided to characterize the fuel composition, grindability, and particle size distribution.

Combustion - Several geometrically scaled-down commercial burners are available for firing natural gas, fuel oils and slurries, biomass, and pulverized coals ranging from bituminous to lignite. A slagging Cyclone™ combustor can also be installed for efficient burning of diverse coals, pulp and paper mill sludge, tires, and municipal solid waste. For staged combustion, the combustion zone is operated sub-stoichiometrically to minimize NO_x formation. Staging oxidant flows into the furnace through two elevations above the combustion zone, each equipped with 2 over-fire air (OFA) ports. For O₂ enrichment of air or recycled flue gas during oxy-combustion, liquid oxygen from a 9,000-gallon storage tank is first vaporized in an ambient vaporizer. Gaseous oxygen is then regulated to appropriate pressures and delivered to the test area.

Selective Catalytic Reduction (SCR) - A conventional SCR unit including an ammonia injection system is located downstream of the economizer to investigate the effects flue gas temperature, composition, space velocity, catalyst formulation, and catalyst geometry on NO_x reduction and elemental mercury oxidation. A low-temperature moving bed SCR reactor is also positioned nearby, downstream of the particulate control device.

Flue Gas Desulfurization (WFGD and SDA) - Wet and dry scrubbing are highly efficient and proven technologies for SO₂ emissions control in coal-burning units. Both wet and dry scrubbing processes use aqueous sorbent slurries which react with SO₂ in the flue gas stream inside a reactor vessel, producing wet and dry byproducts, respectively. Our full-flow WFGD and SDA systems have been utilized to provide valuable performance data not only for SO₂ control but also for simultaneous removal of other pollutants including NO_x, PM, SO₃, HCl, and air toxics (e.g., Hg, Se, As, and Cd) in various applications.

Sorbent Injection - Direct injection of sorbents into the flue gas stream offers an alternative approach for reducing the emissions of NO_x, SO₂, SO₃, and Hg. Candidate sorbents or reagents can be metered and delivered pneumatically to selected injection points along the flue gas pathway for emissions control studies.

Instruments - Measurements of the fuel and oxidant flow rates, reagent feed rates, flue gas composition, etc., rely on calibrated instrumentation. Rockwell Automation system is used for overall facility operation control and data acquisition. Chemical analyses of collected samples are carried out in the analytical chemistry lab. Below is a short list of other instrumentation and measurement capabilities.

• Flue gas analyzers (NO_x, SO₂, CO, CO₂, and O₂)
• In-situ O₂ and H₂O probes
• Multi-gas Fourier Transfer Infrared (FTIR) analyzer
• Flameview™ camera for live flame imaging and temperature mapping
• High-velocity thermocouple probes
• Particulate samplers
• EPA flue gas sampling methods

Past Experience - Over the years, the original SBS and SBS-II facilities have been used successfully in company and government-sponsored projects to develop commercial technologies including:

For more information, please contact us.