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...


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.
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.
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.
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.
Evaporators
Evaporators are systems consisting of a heat exchanger or bath, valves, manifolds and temperature controls for conversion of a product (e.g., liquefied gas) from a liquid to a gaseous state.

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...

5.4 Pulverized Coal Coal is an abundant and low-cost fuel for boilers. It can be burned in a number of ways depending on the characteristics of the coal and the particular boiler application. Various...

Overview Donald Kawecki Vice President Engineering Foster Wheeler North America Power The process of designing and operating a fuel preparation system for a power or steam generation station requires...