Improved Efficiency of Steam Power Plant
by Concentrating Solar Power
Dheeman Paul, M. S. Muhit & Marzana Khatun
Department of EEE, American International University-Bangladesh, Dhaka, Bangladesh.
E-mail : dheeman@ymail.com, muhitkth@gmail.com, marzana.eva@gmail.com
Abstract – This paper establishes that the efficiency of a
steam power plant can be enhanced by incorporating
concentrated solar energy using ball lens to increase the
temperature of the feed water entering the boiler ; the
proposed deign is 35 percent more energy efficient in
comparison to available concentrating solar power
technologies. The proposed design of the solar chamber is
adaptive with the technology discussed. Index.
concept of Concentrated Solar Power (CSP) comes into
focus. The available solar energy can be concentrated
using an arrangement of lenses, mirrors and tracking
devices resulting into focused beam of sunlight with
high density. Wide range of existing technologies in this
arena exists; ranging from parabolic trough, solar power
tower, solar chimney, dish stirling, fresnel reflectors [2]
are frequently used based on required specifications of
projects. Glass ball lens [3] can also be used to
concentrate the solar energy in a more efficient way.
The lenses being spherical in appearance, concentrates
available solar energy around itself in an improved
efficiency order. Figure 1 depicts the typical
arrangement of lens arrangement.
Keywords – Ball lens, Concentrated solar power.
I.
INTRODUCTION
Electricity, one of the most important factors in
economic development of every country is under crisis.
The availability of fossil fuels such as coal, oil and
natural gas is decreasing everyday and electric power
generation is also decreasing. At present with less
availability, the inflation of fossil fuel immensely affects
generation. Renewable energy sources come into the
scenario with great promising prospects. Energy sources
such as solar, wind, biomass, and hydro are plenty.
Hence, in recent days, the trend is more towards
utilizing the renewable energy sources in a more
efficient way regardless their commonly conventional
installations. Among all the other resources, solar
thermal power is considered to be of utmost prospects
[1]. In this paper, proposal has been given on increasing
efficiency of existing power stations incorporated with
solar energy utilization using glass ball lens setup.
II. INCORPORATING SOLAR ENERGY
The available solar energy obtained from the sun may be
sufficient enough to generate electricity from
photovoltaic cells. In contrary, for the purpose of
efficient thermodynamic cycle with reduced fuel cost,
water must be heated up till a certain temperature before
it enters the feed water in steam power plant. Then, the
Fig. 1 : Typical arrangement of glass ball lens for
concentrating solar power
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ITSI Transactions on Electrical and Electronics Engineering (ITSI-TEEE)
Few of the major advantages with ball lenses are: i)
Ball lens do not need mirror to focus the light, ii) being
spherical in shape, the lens can concentrate sun light
irrespective of the position of the sun. iii) no need of sun
tracking, iv) the lenses can even work at night or
diffused light.
The condenser absorbs steam and transformed into
water which is passed to the feed water heater to
economizer for preparing water for reuse and sent to the
boiler for cycle continuation. Generally thermal power
plant works on principle of Rankine Cycle as shown in
Figure. 3. The cycle consists of four processes: (1-2)
Isentropic compression in pump; Constant pressure heat
addition in a boiler; (3-4) Isentropic expansion in a
turbine; (4-1) Constant pressure heat rejection in a
condenser. To improve this cycle some factors can be
considered such as, lowering the condenser pressure,
superheating the steam to high temperatures, increasing
the boiler pressure, reheating Rankine cycle or by using
regenerative Rankine cycle where feed water is heated
by extracted steam from turbine.
The use of mirrors and tracking devices can be
eliminated in the arrangement as shown in figure 2.
IV. FEED WATER HEATING BY CSP
Before entering the Boiler, the proposed design will
have a solar chamber through feed water pipe. The solar
chamber consists of glass ball lens over its surface,
superconducting plate and conducting rod for effective
transfer of heat energy. The purpose of the glass ball
lens is to concentrate the sunlight in the focal plane. The
superconducting plate on the surface of solar chamber
absorbs the heat concentrated by the lens. Conducting
rods connected underneath the surface transfers the heat
to the water. The rod has fin type arrangement with
adaptive surface for faster heat transfer to the working
fluid, water. As the water takes away more and more
heat from the radiator it enters the boiler. The detailed
diagram is shown in figure 4.
Fig. 2 : Concentrated solar power
III. STEAM POWER PLANT
Steam power plant, a plant designed to convert the
heat from the combustion of a fuel into mechanical
energy by means of steam. Steam Power Plant consist of
several components, mainly boiler, low and high
pressure turbine, re-heater, super heater, condenser, feed
water pump, feed water heater, economizer etc. Air from
the atmosphere is heated in preheater by flue gas to
increase the thermal efficiency of the process. The steam
is then passed to high pressure steam turbine for
reheating. Furthermore, reheated air passed to the low
pressure turbine where it is connected with alternator for
generating electricity.
Fig. 4 : Feed water heating process
V. SOLAR CHAMBER DESIGN
In this paper, design of a solar chamber has been
proposed. An arrangement of ball lenses will be surface
mounted as shown in figure 5. The ball lens is round in
shape so the ball can concentrated the sunlight at any
time. The ball lenses are also capable to produce in the
Fig. 3 : Rankine Cycle
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night with the help of the moonlight. Next, the ball lens
concentrates the sun light in such a way that the super
conducting metal (Usually the super conducting metal is
Aluminum, Copper etc.) can easily heat up in the focal
plane as in figure 6. The focal plane is shown in the
figure as black line. Then the metal conducting rod in
figure 7, transfers the heat energy to the flowing water
through the heat sink. The heated feed water then enters
the boiler.
VI. COST ANALYSIS FOR SOLAR INTEGRATED STEAM
POWER PLANT
Before entering the boiler we assume that the Glass
lens will be used to heat up the feed water to increase
the temperature up to 350 degree Celsius to analyze the
cost. The steam temperature will increase to almost 500
degrees Celsius if high temperature feed water enters
into the boiler. So to reach its temperature (500 degree
Celsius) the boiler will need less fuel for combustion. In
between economizer and boiler several Glass ball lens
of radius 10 centimeter and 30 centimeter of focal length
will be added.
So, the power of the lens is:
.
The heat energy supplied by sunlight,
Where,
Fig. 5 : Top view of Solar chamber with ball lens arrangement
T1= temp. of feed water (assuming 60 degree Celsius)
T2= temp. given by Ball lens (assuming 300 degree
Celsius)
S= 4.2 KJ/Kg K (water specific heat)
M= 1 Kg (weight of feed water)
t= 1 sec
Now,
H= 1*4.2*(573K-333K) = 1008J
Supplied heat by the Fresnel per unit time,
Q=H/t= 1008 watts
Assume the area of the solar chamber is 2.6 square
meter. So, the side of the solar chamber is 1.61
meter=161 centimeter. Number of ball lens required to
cover the chamber is 161/20 (diameter of the ball lens)
=8.05. So, 8 ball lens are required to cover one line.
Fig. 6 : Super conducting plate (Concentrated area)
So, total number of ball lens required is 8*8-=64
ball lens. The price of 10 centimeter Glass ball lens
costs around $50. So, total cost is $50*64=$3200
(approximately).
We know that installing a power plant costs huge.
So, spending 3200 dollar or double of it would not be
much for a power plant. Thus, this will result in
decrease of fuel consumption and increase efficiency of
a plant.
Fig. 7 : Conducting rod for thermal energy transfer
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ITSI Transactions on Electrical and Electronics Engineering (ITSI-TEEE)
VII. CONCLUSIONS
VIII. REFERENCES
Electrical power generation is a big issue all over
the world and with increasing demand of power
generation, only depending on fossil fuels and nuclear
power plant would not be a wise idea. We have to take
advantage of every possible resource that is available to
us. The proposal we have given here is for long term
basis and we believe though the initial cost of building
the whole system will be expensive but in future the
profit gained from the increased efficiency and reduced
environmental pollution will be much higher than the
present high cost.
[1]
R. Ahmed, M. Billah, Md. M. Hossain
“Increasing the Efficiency of Steam Power Plant
with the Help of Solar Energy”, ICDRET
conference, 2012.
[2]
D. R. Mills and G. L. Morrison, “Compact linear
Fresnel reflector solar thermal power plants,”
Solar energy, vol. 68, no. 3, pp. 263-283, 2000.
[3]
http://www.greenoptimistic.com/2012/08/29/
broessel-spherical-lenses-concentrated-solarpower/#.UQTQgyKXDIU
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