From Basics of Boiler and HRSG Design

Although the technologies listed in this chapter might sound new, most have been around for a long time. What's driving them are environmental and efficiency issues. As they have become increasingly critical factors, these technologies have taken on much more importance. The natural gas-fired combined-cycle process is both efficient and environmentally friendly, while fluidized-bed combustion provides pollution control directly in the boiler and offers another option for continued use of coal, as does integrated coal gasification. Alternative fuel (refuse, biomass) boilers are often stoker fired, which has kept this venerable technology alive.

FLUIDIZED BED COMBUSTION

As chapter 1 indicated, many of the most modern coal-fired units have been based around pulverized coal technologies. However, environmental regulations regarding nitrogen oxide (NO x) and sulfur dioxide (SO 2) emissions require pollution control techniques. They can include burner modifications, overfire air, selective-catalytic-reduction (SCR), or selective non-catalytic reduction (SNCR) for NO x control, and fuel switching, wet scrubbing, or dry scrubbing for SO 2 removal. These pollution control methods add a great deal of complexity and cost to a steam-generating unit.

Fluidized-bed combustion incorporates NO x and SO 2 control directly into the furnace design and operation. The term "fluidized bed" refers to the process in which an upward flow of air keeps fuel and ash particles in a suspended state within the boiler. The airflow required to initially transform a fixed bed of material into a fluidized bed is known as the minimum fluidization velocity. This velocity...

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Products & Services
Boilers (industrial)
Industrial boilers are closed vessels that use a fuel source or electricity to heat water or generate steam for industrial heating and humidification applications.
Selective Catalytic Reduction (SCR) Systems
Selective catalytic reduction (SCR) systems inject ammonia into boiler flue gas and pass it through a catalyst bed where the nitrogen oxide gas (NOx) and ammonia react to form nitrogen and water vapor.
Adsorption Equipment
Adsorption equipment is used to bind molecules or particles to a surface. This process is used for the reclamation or remediation of process effluents including wastewater, liquid, gas, vapor, air, and contaminated soil.
Combined Heat and Power (CHP) Modules
Cogeneration equipment produces power and thermal energy from a common fuel source, generally one that is considered to be a waste product from another process.
Air Scrubbers, Wet Scrubbers, and Gas Scrubbers
Air scrubbers, wet scrubbers, and gas scrubbers are air pollution control devices that use a high-energy liquid spray to remove aerosol and gaseous pollutants from an air stream. The gases are removed either by absorption or chemical reaction.

Topics of Interest

Bruce G. Miller Associate Director, Energy Institute The Pennsylvania State University Sharon Falcone Miller Research Associate, Energy Institute The Pennsylvania State University 8.1 Introduction...

8.2 Fluidized-Bed Combustion Systems In a typical FBC system, the fuel (or fuels), an inert material such as sand or ash (referred to as bed material), and limestone (when added for sulfur control)...

OVERVIEW Control of air pollution it's an issue of tremendous importance to power plant owners past, present, and future. While the industry focus for years has been on nitrogen oxides (NO x), sulfur...

8.6 Pollutant Formation and Control Fluidized-bed coal combustors have been called the "commercial success story of the last decade in the power generation business" and are perhaps the most...

Fluidized bed choices include bubbling fluidized bed (BFB), circulating fluidized bed (CFB), and pressurized circulating fluidized bed (PCFB). Bubbling fluidized-bed units are particularly efficient...