We Energies Coal Combustion Products ... - The White House

Chapter 2
CCPs and
Electric Power Generation
Coal is one of the most commonly used energy sources for the generation of
electricity. In the process of generating power from coal, large quantities of
CCPs are produced. CCPs are the solid residues that remain after the
combustion of coal within a furnace.
In the early years of power generation by a coal-fired generating plant, coal
was fired in a furnace with stoker grates. Today most coal-fueled power plants
are fired with pulverized coal.
Electric Power Generation
In the most simplified form, a coal-fired power plant process can be described
as follows. Coal is first passed through a pulverizer where it is milled to the
consistency of flour. The powdered coal is mixed with a steady supply of air
and is blown to the furnace where it burns like a gas flame. Pulverized coal
firing is more efficient than stoker firing. With stoker firing, there is always a
bed of coal on the grate, which contains a considerable amount of heat that is
lost when it is removed. With pulverized coal, the coal burns instantly, and in
this way the heat is released quickly and the efficiency of the process is
higher. If the coal supply is cut off, combustion ceases immediately (4).
The heat generated by burning pulverized coal in the furnace in the presence
of air is used to generate steam in a boiler. In its simplest form, the boiler
consists of steel tubes arranged in a furnace. The hot gases pass through the
banks of tubes, heating the tubes. The boiler is supplied with a steady flow of
water, which is turned to steam in the tubes. The steam is collected in the
upper drum of the boiler and is directed to pipes leading to a turbine (4).
The turbine can be compared to a windmill. The steam generated in the boiler
is directed to the fan blades in the turbine and causes the rotor assembly to
turn. The blades are arranged in groups or stages and the steam is forced to
flow through the different stages. In doing so, the steam loses some of its
energy at each stage, and the turbine utilizes the steam energy efficiently to
spin the rotor shaft.
9 We Energies
Coal Combustion Products
Utilization Handbook