Project no. 127
Pre-heating Stage in Thermal Power Plant
A. Wijaya, G. Wibowo, D. Lin
BEng Electrical & Electronic Engineering, University of Nottingham Ningbo China
Over the centuries, major problems for renewable and sustainable energy sources are cost
and efficiency. Thermal power plant is the most widely used facility for electricity generation
until today benefit from its economic and robust operation. Fossil fuels is normally used as
energy source to heat up water into steam, which is then used to drive steam turbine and
generate electricity. Environmental problems associated with thermal power plant today is the
emission of pollutants (particulates, CO2, NOx, and SO2) originated from the combustion of
impurities in the fuel. To reduce the overall environmental impact of a thermal plant, solar
energy can be used to pre-heat the water as the initial stage of a thermal power plant. Fresnel
lens (compact convex lens) will be employed to concentrate the solar power to the pre-heating
chamber, where the temperature of water can be heated up prior to entering the boiler.
Thermal radiation from the sun could be used for heating purpose. If the sunlight is focused
by a lens to one point, energy contained in the thermal radiation could be harvested. When
light rays pass through a convex lens (a type of lens usually used for magnification), it will be
focused to one point. The lens used in this project is a slimmer and cheaper version of convex
lens called Fresnel lens. Fresnel lens divides the lens into a set of concentric annular sections
which has a ‘focal length’ and ‘light rays bending effect’ similar to conventional lens.
Water Tube / Container
(act as heat conductor)
Figure 1: Pre-Heating Tube with Fresnel Lens and Metal Pillars inside the Tube
Figure 1 shows the schematics of the proposed design that will supplement conventional
boiling process through harvesting solar energy. It works by raising the temperature of the
water up to 60.63℃ before it enters the main boiler and thus, reduce the overall coal
consumption up to 7.4% for electricity generation. Consequently, the overall environmental
impact of the plant operation can be mitigated with reduced amount of greenhouses gases
emission. There will also be metal pillars in the tube to help transferring the heat from the top
of the tube to the water inside the tube.
The container was made of cast iron. Cast iron is a good heat conductor and at the same
time, it has a higher melting point (1535 ℃). Next, the proposed pre-heat supplement is
preferred in warm areas such as tropical areas to maximize its benefit. However, this project
has a wide applicability whereas, if there is sunlight, this system will work.
Based on the calculation, this project cost no more than 20,000 USD. This means that it is
feasible and can also be made in a reasonable timeframe as all the technologies are ready.
In the future, solar pre-heating unit can also be employed in other power plants.