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Full Suite of Air Pollution Control Devices

The Energy & Environmental Research Center (EERC) is leading a series of programs that together provide the technical basis for a near-zero-emission facility. Such a facility would run more efficiently and exceed current air emission regulations.

The design consists of an entire family of technologies that, when working together, will offer greatly enhanced efficiency and reduced emissions and contribute to a cleaner, healthier environment. Key components of the system include advanced coal utilization technologies to improve energy efficiency and reduce fuel use and advanced emission control devices to capture hazardous trace metals such as mercury; dramatically reduce particulate, sulfur oxide (SOx), sulfur trioxide (SO3), and nitrogen oxide (NOx); and capture carbon dioxide (CO2).

Key air pollution control devices include the following.

Mercury Control Technology

Through the EERC's Centers for Air Toxic Metals® program, the EERC has been proven to be the premier group in the world for developing mercury control technologies. The EERC has developed state-of-the-art, cost-effective mercury control technologies with its partners and is leading the drive to commercialize these mercury control solutions. Effective technologies now exist to remove all forms of mercury from flue gas, and the technologies can be scaled for use in virtually any site facility.

Particulate Control Systems

Retrofitting power plants with the EERC's Advanced HybridTM filter technology removes more than 99.99% of fine particles from exhaust gases of coal-fired power plants, incinerators, and mineral-processing facilities as well as recaptures valuable product from process gases in the pharmaceutical and chemical industries. Particulate Test Combustor

Wet Flue Gas Desulfurization System

The EERC's pilot-scale wet flue gas desulfurization system for sulfur control is 7 inches in diameter, with a height of approximately 20 ft. The scrubber is equipped with packing to ensure the scrubber solutions do not run down the walls of the scrubber. The column is made of plastic material, while the spray nozzles are made of stainless steel.

Spray Dryer

The EERC’s spray dryer is a Niro Inc. Production MinorTM spray dryer designed to operate in conjunction with the combustion test facility (CTF). The drying chamber is 3.9 ft in diameter, with a 2.5-ft cylindrical height and a 60° conical bottom. The inner shell is constructed of 2-mm stainless steel, Type AISI 316, with a 220-grit finish. A Niro Inc. Type FS-1 rotary atomizer, capable of speeds ranging from 10,500 to 30,000 rpm, is used for atomizing lime slurry. An air disperser, supplied with the rotary atomizer, is used to introduce the properly heated (300°F [149°C]) air flow pattern throughout the chamber. The lime slurry flow rate is nominally 0.17 lb/min.

Electrostatic Precipitator (ESP)

A single-wire, tubular ESP, shown schematically in the figure below, provides a specific collection area of 125 at 300°F. Gas velocity through the ESP is 5 ft/min. Plate spacing for the unit is 11 in. The ESP has an electrically isolated plate that is grounded through an ammeter, allowing continuous monitoring of the actual plate current to ensure consistent operation of the ESP. The tubular plate is suspended by a load cell and is used to monitor rapping efficiency. In addition, sight ports are located at the top of the ESP to enable online inspection of electrode alignment, sparking, rapping, and dust buildup on the plate. The ESP was designed to facilitate thorough cleaning between tests so that all tests begin on the same basis.

Pulse-Jet Baghouse

The baghouse vessel is a 20-in.-inside diameter chamber that is heat-traced and insulated, with the flue gas introduced near the bottom. Three 13-ft by 5-in. bags provide an air-to-cloth ratio of 4 ft/sec. The air-to-cloth ratio can be increased by removing or adding shorter bags. A variety of bags can and have been used for tests, including 100% GORE-TEX® with a GORE-TEX membrane. These bags provide a particulate collection efficiency that is exceedingly high, >99.995%. Each bag is cleaned separately with its own diaphragm pulse valve.

Selective Catalytic Reduction (SCR) System

In order to control NOx emissions from the CTF, a SCR reactor was installed ahead of the ESP. The reactor contains three catalyst layers and utilizes anhydrous ammonia as the reductant. The system is designed for a face velocity of 5 m/s and an operating temperature of 600° to 800°F, which can be controlled. Sampling ports are available at the inlet, outlet, and between the catalyst layers to facilitate gas sampling. Catalyst can be easily removed and installed to allow the use of any catalyst desired. The reactor can be quickly bypassed to accommodate specific testing needs. This reactor can also be easily moved and installed on the particulate test combustor as well.

CO2 Capture

Another major focus of the EERC's program is the development of technologies to reduce CO2 emissions into the atmosphere. The EERC's Partnership for CO2 Capture is identifying and commercializing a range of CO2 capture technology systems that can be implemented into the electric utility fleet to meet environmental emission constraints and the requirements of CO2 sequestration. The technologies tested in the pilot-scale systems at the EERC included solvent scrubbing, solid sorbents, and oxygen-fired combustion.

Useful Links

Centers for Air Toxic Metals®

Mercury Control

Advanced HybridTM Filter

Particulate Test Combustor

Combustion Test Facility