Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS FOR DRYING COAL USING REHEAT STEAM
TECHNICAL FIELD
The present invention relates to an apparatus for
drying a coal using a reheat steam, and more particularly,
to a coal drying apparatus equipped with a multistage dryer
that removes water contained in the coal used as a fuel for
thermal power plants by jetting the reheat steam.
BACKGROUND ART
In general, in a thermal power plant that generates
power using the coal as a fuel, coal of about 180 tons/hr
per 500 MW is combusted, and the coal equivalent to about 37
tons per differentiator is supplied to a boiler. In the
thermal power plant of 500 MW that uses the coal,
approximately six coal yards having capacity of
approximately 500 tons are installed, the normal supply of
coal is performed in five of them, and the remaining one is
operated as a coal yard that preliminarily stores the coal
capable of being used for a certain period of time.
Further, in the thermal power plant that generates
power using the coal as a fuel, a standard thermal power
design criterion of coal is designed to use a low moisture
bituminous coal of 6,080 Kcal/Kg and 10% or less. Imported
coal is used in some thermal power plants, and an average
moisture water content of some sub-bituminous coals of them
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may be equal to or higher than 17%, which lowers the
combustion efficiency of the boiler. When the
standard
thermal power combustion limit is 5,400 Kcal/Kg and a
heating value of the used coal is low, a decrease in the
power generation amount and an increase in the fuel
consumption are expected due to a decline in the combustion
efficiency. Furthermore, when using the sub-bituminous coal
that is a high-moisture and low-calorific coal, since the
moisture content is higher than the design criteria, a
conveyance system for transport the coal is not smooth, and
when grinding the coal using a differentiator, a decline in
the efficiency, a decline in the combustion efficiency due
to some incomplete combustion, a deviation of a heat
distribution generated in the boiler, and operation in an
abnormal state also occur. However, in order to reduce fuel
costs in the thermal power plant, the proportion of use of
the sub-bituminous coal has gradually increased to about
approximately 41 to 60%.
In addition, in the face of safety issues due to
expectation of global economic recovery, and destruction of
the nuclear power plant caused by Japanese huge earthquake,
the preference of the thermal power plant increases, and
demand and price of coal seems to consistently rise. Since
the environment of the global coal market changes from the
consumer to the provider, stable supply and demand of coal
are difficult, a production volume of the high calorific
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coal is expected to be maintained at current levels, and
thus, an imbalance of coal supply and demand is expected.
Although the low-calorific coal is about 47% among the
total deposits of the world's coal and its deposits are
much, since there are problems of a low calorific value, a
high moisture content and a combustion failure during
combustion, and the high moisture low calorific coal has a
difficulty in complete combustion, it is ignored in the
market. Until recent
years, worldwide, although there has
been a high tendency of relying on stable prices of
petroleum and low-production unit price of the nuclear power
generation, in recent years, due to a sharp rise in the
price of petroleum and a sense of insecurity to the nuclear
power generation, many constructions of the thermal power
generation that uses coal have been planned.
As conventional techniques (thermal drying) for drying
the coal, a rotary drying method for drying the internal
coal particles with high-temperature gas, while rotating a
cylindrical shell into which coal is charged, a flash
pneumatic drying method for raising and drying the high-
temperature dry gas from bottom to top, while supplying the
cola from top to bottom, and a fluid-bed drying method for
drying the coal, while the high-temperature dry gas being
raised upward along with fine particles have been mainly
used.
Coal is divided into a surface moisture adhered to a
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gap between the coal particles, and a coupling moisture
coupled to an internal pore of the coal. As the surface
moisture, moisture sprayed during a cleaning process in the
production area and at the time of transportation and
storage is most, and its amount is determined depending on a
surface area and absorbency. As the
particles are small,
the surface area becomes greater, capillary is formed
between the particles, and contains moisture, and a water
content increases. The coupling
moisture is formed at a
generation epoch of the coal, and is low in the order of
lignite, bituminous coal (bituminous coal and sub-bituminous
coal), and anthracite coal. When the coal
has much
moisture, the heating value decreases and the transportation
costs also increase. Thus, it is
necessary to control the
moisture in the process of mixing, pulverizing, and
separation of the coal.
In addition, as the relevant prior art, there are a
drying apparatus of Korean Registered Patent Publication No.
10-0680905 (published Jan. 8, 2007), and a coal drying
apparatus that uses a superheated steam of Korean Registered
Patent Publication No. 10-1216827 (published Dec. 28, 2012).
DISCLOSURE
TECHNICAL PROBLEM
An object of the present invention is directed to
enhance a heating value of coal so that coal used as fuel in
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thermal power plant can keep proper moisture content of coal
by being dried using a dried reheated steam, thereby being
able to improve the combustion efficiency of the boiler and
reduce the use of fuel.
Also, another object of the present invention is to
provide a drying technique capable of preventing
environmental problems due to incomplete combustion of the
coal through the regulation of the moisture contained in the
coal, and a technique that can be applied to a thermal power
plant.
TECHNICAL SOLUTION
According to an aspect of the present invention, there
is provided an apparatus for drying coal using reheat steam,
the apparatus including a first coal dryer; a second coal
dryer; and a third dryer, a pair of first drive sprockets
and a pair of first driven sprockets are spaced apart from
each other at a constant distance and are fastened to each
other by first chains, a plurality of first LransporL plates
is hinged between the first chains, a pair of first guide
rails that horizontally supports the first transport plates
is installed below an upper first chain connected between
the first drive sprocket and the first driven sprocket, a
pair of second guide rails that horizontally supports the
first transport plates is installed below a lower first
chain connected between the first drive sprocket and the
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first driven sprocket, a first steam chamber that injects a
reheat steam supplied from a reheater is installed below the
upper first chain, a second steam chamber that injects the
reheat steam supplied from the reheater is installed below
the lower first chain, a first exhaust chamber that collects
an exhaust gas is installed above the upper first chain, and
a second exhaust chamber that collects the exhaust gas is
installed above the lower first chain; a pair of second
drive sprockets and a pair of second driven sprockets are
spaced apart from each other at a constant distance and are
fastened to each other by second chains, a plurality of
second transport plates are hinged between the second
chains, a pair of third guide rails that horizontally
supports the second transport plates is installed below an
upper second chain connected between the second drive
sprocket and the second driven sprocket, a pair of fourth
guide rails that horizontally supports the second Lransport
plates is installed below a lower second chain connected
between the second drive sprocket and the second driven
sprocket, a third steam chamber that injects a reheat steam
supplied from a reheater is installed below the upper second
chain, a fourth steam chamber that injects the reheat steam
supplied from the reheater is installed below the lower
second chain, a third exhaust chamber that collects an
exhaust gas is installed above the upper second chain, and a
fourth exhaust chamber that collects the exhaust gas is
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installed above-the lower chain; the third coal drier being
installed below the second coal dryer to naturally dry the
coal at room temperature, while transporting the coal dried
by the reheat steam, and the coal primarily dried in the
first coal dryer is charged to the second coal dryer to be
secondarily dried.
Further, in the present invention, a steam supply pipe
that supplies the reheat steam from the reheater may be
connected to each of the first steam chamber through the
fourth steam chamber, and a gas discharge pipe that
discharges the exhaust gas may be connected to each of the
first exhaust gas chamber through the fourth exhaust gas
chamber.
Further, in the present invention, the first steam
chamber through the fourth steam chamber and the first
exhaust gas chamber through Lhe fourth gas chamber may be
partitioned into plural numbers.
Further, in the present invention, the first transport
plate is hinged to the first chain by being deflected, the
second transport plate is hinged to the second chain by
being deflected, a plurality of through-holes are formed in
each of the first transport plate and the second transport
plate, and a punching ratio of each through-hole compared to
a total area of the first transport plate and the second
transport plate may be 10 to 15%.
Further, in the present invention, a guide bar may be
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installed below each of the first driven sprocket and the
second driven sprocket.
Further, in the present invention, each of the first
drive sprocket and second drive sprocket may be connected so
that rotational power generated from the drive motor is
transmitted through a reduction gear.
It should be understood that different embodiments of
the invention, including those described under different
aspects of the invention, are meant to be generally
applicable to all aspects of the invention. Any embodiment
may be combined with any other embodiment unless
inappropriate. All examples
are illustrative and non-
limiting.
ADVANTAGEOUS EFFECTS
According to the present invention, by removing the
moisture remaining on the inside and the outside of the coal
as the fuel used in the thermal power plant_ using the high-
temperature reheat steam in a multi-stage coal dryer to
prevent incomplete combustion, a calorific value of the coal
is improved, the discharge of the pollutants is minimized,
corrosion of the system is prevented, the durability is
improved, the natural ignition rate with a decrease in
moisture is reduced, the grinding efficiency of the coal
differentiator and the heat distribution of the power boiler
during combustion of coal are improved, it is possible to
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eliminate the clogging phenomenon of the path at the time of
transportation of coal, and it is possible to improve the
stability of the coal supply by enhancing the utilization
rate of the low-grade coal of the low-demand. Also, it is
possible to use a low calorific coal of a price cheaper than
a high-calorific coal, to reduce the fuel cost and the
original cost due to a decrease in amount of coal import,
and to relatively reduce the coal consumption, thereby being
able to achieve an effect of reducing the emissions of waste
and contaminating substances generated from the combustion
gas and reducing carbon dioxide, and it is possible to
expect a substitution effect of overseas techniques and an
effect such as an overseas export of equipment.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating a coal drying
apparatus using reheat steam as an embodiment according to
the present invention.
FIG. 2 is a block diagram illustrating the coal drying
apparatus using reheat steam according to the present
invention.
FIG. 3 is a side view illustrating the coal drying
apparatus using reheat steam of the present invention.
FIGS. 4 and 5 are perspective views illustrating main
parts of a driven sprocket of the coal drying apparatus
using reheat steam of the present invention.
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BEST MODE FOR THE INVENTION
Exemplary embodiments of the present invention will be
described below in more detail with reference to the
accompanying drawings. The present invention may, however,
be embodied in different forms and should not be construed
as limited to the embodiments set forth herein. Rather,
these embodiments are provided so that this disclosure will
be thorough and complete, and will fully convey the scope of
the present invention to those skilled in the art.
Throughout the disclosure, like reference numerals refer to
like parts throughout the various figures and embodiments of
the present invention.
An embodiment according to a coal drying apparatus
using reheat steam according to the present invention will
be described in detail referring to the accompanying
drawings.
In FIG. 1, a coal yard 10 is a place that keeps and
stores the coal for use as a boiler fuel of a thermal power
plant. Coal contains
surface moisture and internal
moisture. Further, by regularly spraying water to the coal
stored in the coal yard 10, the scattering of coal powder is
prevented. The coal stored in coal yard 10 is transported to
the coal drying apparatus through a transport means such as
a conveyor system. At this time, coal in the coal yard 10
from which moisture is not removed may be transferred to a
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drying coal supply tank 20 connected to the coal drying
apparatus and stored therein.
Further, coal stored in the coal supply tank 20 is
supplied to the coal drying apparatus 100 from a coal fixed
amount supplier 30 in a fixed amount.
The coal drying apparatus 100 includes two dries of a
first coal dryer 110 and a second coal dryer 140 installed
in a multi-layer manner, and a third coal dryer 170 for
naturally drying coal discharged from the second coal dryer
140. The first coal dryer 110 and the second coal dryer 140
have the same structure.
In FIG. 2, in the first coal dryer 110, a pair of first
drive sprockets 111, and a pair of first driven sprockets
112 installed to be spaced apart from the first drive
sprockets at a fixed distance are installed. In the first
drive sprockets 111 and the first driven sprockets 112,
sprockets are constituted on both sides of a drum with a
width of a certain size. Thus, the first
drive sprockets
111 and the first driven sprockets 112 are located at a
certain horizontal distance, and each of a pair of sprockets
is constituted before and after the first drive sprockets
111 and the first driven sprockets 112. The pair of
first
chains 113 is fastened between a pair of the first drive
sprockets 111 and a pair of first driven sprockets 112 to
transmit the rotational force.
In FIG. 3, the rotary power generated from the first
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drive motor 118 is transmitted to the first drive sprocket
111 via the first speed reducer 119.
In FIG 4, a plurality of first transport plates 114 are
hinged between the first chains 113. The first
transport
plates 114 are consecutively horizontally arranged in a flat
plate shape. The first
transport plates 114 are hinged
between the first chains 113 at regular intervals, the
hinges are located by being deflected to the first transport
plate 114, and are hinged to hinge holes formed in the chain
113. The first
transport plate 114 is formed with
vertically penetrated through-holes 114a, and the through-
holes 114a are formed at a penetration ratio of about 10 to
15% to the total area of the first transport plate 114. The
through-holes 114a are holes through which the reheat steam
injected from the bottom passes.
Thus, the coupling of the pair of first drive sprockets
111 and first driven sprockets 112, the first chains 113 and
the first transport plates 114 acts as a conveyor that
conveys coal.
In addition, a pair of first guide rails 115 which
horizontally supports each of a plurality of first transport
plates 114 is installed below the first upper chain 113a
located between the first drive sprocket 111 and the first
driven sprocket 112. Further, a pair of second guide rails
116 which horizontally supports each of a plurality of first
transport plates 114 is installed below the first lower
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chain 113b located between the first drive sprocket 111 and
the first driven sprocket 112. The first guide rail 115 and
the second guide rail 116 allow the first transport plate
114 hinged to the first chain 113 by being deflected to
convey the coal, while maintaining the horizontal state. At
this time, the transport plates are constituted by two
stages so that, while the first driven sprocket112 fastened
to the first chain 113 rotates by the rotational force of
the first drive sprocket 111, the coal can be transported by
the first transport plate 114 coupled to the upper first
chain 113a, and the coal can be transported by the first
transport plate 114 coupled to the lower first chain 113b.
A first steam chamber 120 formed with a constant space
portion is formed below the upper first chain 113a, and a
second steam chamber 123 formed with a constant space
portion is formed below the lower first chain 113b. The
first steam chambers 120 and the second steam chambers 123
may be divided into one or more sections and installed. The
reheat steam supplied from the reheater 40 through the steam
supply pipe 121 is supplied to the first steam chamber 120
and the second steam chamber 123.
Also, a first exhaust gas chamber 124 formed with a
constant space portion is formed over the upper first chain
113a, and a second exhaust gas chamber 126 formed with a
constant spaced portion is formed over the lower first chain
113b. The first
exhaust gas chamber 124 and the second
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exhaust gas chamber 126 may be divided into one or more
sections and installed. The first
exhaust gas chamber 124
and the second exhaust gas chamber 126 are configured to
collect the exhaust gas changed after being injected from
each of the first steam chamber 120 and the second steam
chamber 123, and thereafter, to discharge the exhaust gas to
the outside through the gas discharge pipe 125. A blower
for sucking the exhaust gas can be installed in the gas
discharge pipe 125. The exhaust gas discharged through the
gas discharge pipe 125 is put into the reheater 40, and the
reheat steam reheated at a constant temperature is supplied
to the first steam chamber 120 and the second steam chamber
123 of the first coal dryer 110 through the steam supply
pipe 121.
Meanwhile, the second coal dryer 140 is installed at
the lower end of the first coal dryer 110 to secondarily dry
the coal first dried in the first coal dryer 110 by the
reheat steam, and the second coal dryer 140 has
substantially the same configuration as the first coal dryer
110.
That is, a pair of second drive sprockets 141, and a
pair of second driven sprockets 142 installed to be spaced
apart from the second drive sprockets at a fixed distance
are installed in the second coal dryer 140. Sprockets are
constituted on both sides of a drum haying a width of a
certain size in the second drive sprocket 141 and the second
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driven sprockets 142. Thus, the
second drive sprocket 141
and the second driven sprocket 142 are located at a
horizontally certain distance, and are configured so that a
pair of sprockets is located before and after each of the
second drive sprocket 141 and the second driven sprocket
142.
Then, a pair of second chains 143 is fastened for
transmitting the rotational force between a pair of the
second drive sprockets 141 and the pair of second driven
sprockets 142. A plurality of
second transport plates 144
is hinged between the second chains 143. The second
transport plates 144 are consecutively and horizontally
arranged in a flat plate shape. The second transport plates
144 are hinged at regular intervals between the second
chains 143, the hinges are located by being deflected to the
second transport plate 144, and are hinged to hinge holes
formed in the second chain 143. The second transport plate
144 is formed with vertically penetrated through-holes 144a,
and the through-holes 144a are formed at a penetration ratio
of about 10 to 15% to the total area ratio of the second
transport plate 144. The through-
holes 144a are holes
through which the reheat steam injected from the bottom
passes.
Thus, the coupling of the pair of second drive
sprockets 141 and the second driven sprockets 142, the
second chain 143 and the second transport plate 144 acts as
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a conveyor that conveys coal.
Further, a pair of third guide rails 145 that
horizontally supports each of a plurality of second
transport plates 144 is installed below the upper second
chain 143a located between the second drive sprocket 141 and
the second driven sprocket 142. Moreover, a pair of fourth
guide rails 146 that horizontally supports each of a
plurality of second transport plates 144 is installed below
the second lower chain 143b located between the second drive
sprocket 141 and the second driven sprocket 142. The third
guide rail 145 and the fourth guide rail 146 allow the
second transport plate 144 hinged by being deflected to the
second chain 143 to convey the coal, while maintaining the
horizontal state. At this time, the transport plates are
constituted by two stages so that, while the second driven
sprocket142 fastened to the second chain 143 rotates by the
rotational force of the second drive sprocket 141, the coal
can be transported by the second transport plate 144 coupled
to the second upper chain 143a, and the coal can be
transported by the second transport plate 144 coupled to the
lower second chain 143h.
A third steam chamber 150 formed with a constant space
portion is formed below the upper second chain 143a, and a
fourth steam chamber 153 formed with a constant space
portion is formed below the lower second chain 143b. The
third steam chambers 150 and the fourth steam chambers 153
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may be divided into one or more sections and installed. The
reheat steam supplied from the reheater 40 through the steam
supply pipe 121 is supplied to the third steam chamber 150
and the fourth steam chamber 153.
Also, a third exhaust gas chamber 154 formed with a
constant space portion is formed over the upper second chain
143a, and a fourth exhaust gas chamber 156 formed with a
constant space portion is formed over the lower second chain
143b. The third
exhaust gas chamber 154 and the fourth
exhaust gas chamber 156 may be divided into one or more
sections and installed. The third
exhaust gas chamber 154
and the fourth exhaust gas chamber 156 are configured to
collect the exhaust gas changed after being injected from
each of the third steam chamber 150 and the fourth steam
chamber 153, and thereafter, to discharge the exhaust gas to
the outside through the discharge pipe 125. A blower for
sucking the exhaust gas can be installed in the gas
discharge pipe 125. The exhaust gas discharged through the
gas discharge pipe 125 is put into the reheater 40, and the
reheat steam reheated at a constant temperature is supplied
to the third steam chamber 150 and the fourth steam chamber
153 of the second coal dryer 140 via the steam supply pipe
121.
The transport speed of the chains of the first coal
dryer 110 and the second coal dryer 140 and the second
transport plate are about 4m per minute, and the coal of
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about 33 tons per hour may be transported.
The third coal dryer 170 is installed below the second
coal dryer 140 and naturally dries the coal dried and
discharged by the reheated steam at room temperature, while
transporting the coal.
The third coal dryer 170 is made up of a flat belt
conveyor or a U-shaped conveyor belt.
The coal naturally dried while passing through the
third coal dryer 170 is stored in a dry coal storage tank
50, and then is supplied as fuel for boilers of thermal
power plants.
The operation of the coal drying apparatus using a
reheat steam of the present invention configured in this way
will be described.
First, the drying coal transported to the drying coal
supply tank 20 from the coal yard 10 is charged into the
coal drying apparatus 100 from the coal fixed amount
supplier 30. The drying coal
charged at a fixed amount
through a first charge port 130 of the first coal dryer 110
of the coal drying apparatus 100 is transported by being
loaded on the first transport plate 114 coupled to the upper
first chain 113a between a pair of first drive sprockets 111
and a pair of first driven sprockets 112. At this time, the
high-temperature reheat steam is supplied to the first steam
chamber 120 installed below the upper first chain 113a from
the reheater 40 through the first steam supply pipe 121, and
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the reheat steam supplied to the first steam chamber 120 is
injected into a through-hole 114a formed in the first
transport plate 114. When reheat steam is injected through
the through-hole 114a, the coal being transported on the
first transport plate 114 is dried by being heated.
Further, the reheat steam having passed through the through-
hole 114a of the first transport plate 114 is collected in
the upper first exhaust gas chamber 124 provided above the
upper first chain 113a in the form of discharge gas, and
then is discharged through the gas discharge pipe 125.
Further, the discharge of the exhaust gas to the gas exhaust
pipe 125 is accelerated by the blower that sucks exhaust
gases. After the
exhaust gas discharged through the gas
discharge pipe 125 is put into the reheater 40 and is re-
heated at a constant temperature, the exhaust gas is
supplied to the first steam chamber 120 of the first coal
dryer 110 in the state of reheat steam via the steam supply
pipe 121.
Further, one or more first steam chambers 120 are
continuously installed below the upper first chain 113a, and
in the course of coal being transported to the first
transport plate 114, the coal is subjected to several drying
processes.
In FIG. 3, the first transport plate 114 hinged to the
upper first chain 113a by being deflected maintains the
horizontal state, while going along the first guide rail
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115, and when reaching a disconnected point of the first
guide rail 115, the first transport plate 114 enters a
vertical state, by being rotated by its own weight by the
deflected hinge coupling. At this time,
the coal on the
first transport plate 114 falls and is loaded on the first
transport plate 114 hinged to the lower first chain 113b.
Further, the first transport plate 114 hinged to the
first chain 113 to be transported to the first driven
sprocket 112 maintains the vertical state, and then is
transported in a horizontal state again, by the first guide
bar 117 installed in an arc shape at the bottom of the first
driven sprocket 112. As illustrated
in FIG. 5, the first
transport plate 114 transported by the first guide bar 117
fixed on the second guide rail 116 at its one side is
changed from the vertical state to a horizontal state.
Also, the coal dropped from the first transport plate
114 of the upper first chain 113a and loaded onto the lower
first chain 113b is heated by the reheat steam supplied to
one or more second steam chambers 123 consecutively
installed at the bottom of the first lower chain 113b, and
thus, the coal is subjected to the continuous drying
process. The exhaust gas collected after the coal drying in
the second exhaust gas chamber 126 provided at the top of
the lower first chain 113b is discharged through the gas
discharge pipe 125.
Also, the first transport plate 114 hinged to the lower
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first chain 113b by being deflected maintains a horizontal
state while going along the second guide rail 116, and then,
when reaching a disconnected point of the second guide rail
116, the first transport plate 114 enters a vertical state,
while being rotated by its own weight due to the deflection
hinge coupling. At this time, the coal on the first
transport plate 114 is charged into the first charge port
130 of the second coal dryer 140 through the first discharge
port 131. The first transport plate 114 hinged to the first
chain 113 transported to the first drive sprocket 111
maintains the vertical state, and then becomes a horizontal
state again, while being transported along the rotation of
the first drive sprocket 111.
Thus, the moisture of surface and inside of the coal
transported by being loaded on the first transport plate 114
by the conveyance of the first chain 113 fastened between
the first drive sprocket 111 and the first driven sprocket
112 of the first coal dryer 110 is removed by continuous
drying of high-temperature reheat steam in each of the upper
first chain 113a and the lower first chain 113b.
Meanwhile, when the coal subjected to the drying
process in the first coal dryer 110 is discharged through
the first discharge port 131, the coal is charged into the
second charge port 160 of the second coal dryer 140 which is
placed below the first coal dryer 110.
The first dried coal charged through the second charge
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port 160 of the second coal dryer 140 of the coal drying
apparatus 100 is transported by being loaded on the second
transport plate 144 coupled to the upper side of the second
chain 143a between a pair of second drive sprockets 141 and
a pair of second driven sprockets 142. At this time,
the
high-temperature reheat steam is supplied to the third steam
chamber 150 provided below the upper second chain 143a from
the reheater 40 through the second steam supply pipe 151,
and the reheat steam supplied to the third steam chamber 150
is injected into a through-hole 144a formed in the second
transport plate 144. When the reheat
steam is injected
through the through-hole 144a, the coal being transported on
the second transport plate 144 is dried by being heated.
Further, the reheat steam having passed through the through-
hole 144a of the second transport plate 144 is collected by
the third exhaust gas chamber 154 installed above the upper
second chain 143a in the form of exhaust gases, and
thereafter, the reheat steam is discharged through the gas
discharge pipe 125. Further,
discharge of the exhaust gas
is accelerated by the blower that sucks exhaust gases in the
gas discharge pipe 125. Further, the exhaust gas discharged
through the gas exhaust pipe 125 is charged into the
reheater 40 and re-heated at a constant temperature, and
thereafter, the exhaust gas is supplied to the third steam
chamber 150 of the second coal dryer 140 via the steam
supply pipe 121 in the reheat steam state.
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Also, one or more third steam chambers150 are
continuously installed below the upper second chain 143a,
and the coal is subjected to the plurality of drying
processes in the process of being transported to the second
transport plate 144.
Further, the second transport plate 144 hinged to the
upper second chain 143a by being deflected maintains the
horizontal state, while going along the third guide rail
145, and thereafter, when reaching a disconnected point of
the third guide rail 145, the second transport plate 144
enters a vertical state, while being rotated by its own
weight due to the deflected hinge coupling. At this time,
the coal on the second transport plate 144 drops and is
loaded onto the second transport plate 144 hinged to the
lower second chain 143b.
Further, the second transport plate 144 hinged to the
second chain 143 transported to the second driven sprocket
142 maintains the vertical state, and thereafter is
transported in a horizontal position again by a second guide
bar 157 installed in an arcuate shape below the second
driven sprocket 142. The second
transport plate 144
transported by the second guide bar 157 with one side fixed
on the fourth guide rail 146 is changed from the vertical
state to the horizontal state.
Furthermore, the coal dropped from the second transport
plate 144 of the upper second chain 143a and transported by
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being loaded onto the lower second chain 143b is heated by
the reheat steam supplied to the one or more fourth steam
chambers 153 consecutively installed below the lower second
chain 143b and is subjected to the continuous drying
process. Further, the
exhaust gas collected after the coal
drying in the fourth exhaust gas chamber 156 installed above
the lower second chain 143b is discharged through the gas
discharge pipe 125.
In addition, the second transport plate 144 hinged to
the lower second chain 143b by being deflected maintains the
horizontal state, while going along fourth guide rail 146,
and thereafter, when reaching a disconnected point of the
fourth guide rail 146, the second transport plate 144 enters
a vertical state while being rotated by its own weight due
to the deflected hinge coupling. At this time, the coal on
the second transport plate 144 is discharged to the third
coal dryer 170 through the second discharge port 161.
Further, the second transport plate 144 hinged to the second
chain 143 transported to the second drive sprocket 141
maintains the vertical state, and thereafter, enters a
horizontal state again, while being transported along the
rotation of the second drive sprocket 141.
Thus, the moisture of surface and inside of the coal
transported by being loaded on the second transport plate
144 by the conveyance of the second chain 143 fastened
between the second drive sprocket 141 and the second driven
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sprocket 142 of the second coal dryer 140 is secondarily
removed by continuous drying of high-temperature reheat
steam in each of the upper second chain 143a and the lower
second chain 143b.
The second coal dryer 140 dries the coal by the same
configuration and structure as the first coal dryer 110 in
the same drying process. Thus, the
drying coal is first
dried in the first coal dryer 110, and thereafter is
secondarily dried in the second coal dryer 140.
The coal having passed through the secondary drying
process in the second coal dryer 140 is discharged through
the second discharge port 161 and is discharged to the third
coal dryer 170. The third coal
dryer 170 naturally dries
and cools the coal heated at a constant temperature to room
temperature, while transporting the coal charged from the
second coal dryer 140 by the belt conveyor. The coal
transported to the third coal dryer 170 is transported to
the thermal power plant 60 after being charged and stored to
a dry coal storage tank 50.
The temperature of the coal subjected to the drying
process in the first coal dryer 110 and the second coal
dryer 140 may be raised to about 90 to 110 C. Although a
spontaneous ignition temperature of coal is about 93 to 95 C,
since the temperature of the reheat steam is about 400 to
600 C, oxygen is dilute, coal is not ignited, and there is
CA 02928103 2016-04-19
no danger of fire.
In addition, the reheat steam generated by the reheater
40 is a transparent gas that is obtained by mixing of a
latent heat of vaporization as vaporization heat, a
condensation transfer heat creased by the heating sensible
heat and radiation conductive heat. The reheat
steam is
generated by heating the saturated steam generated in the
boiler using reheater. The steam
generated in the boiler
for the power development has high pressure and high
temperature, but the reheat steam generated in the reheater
has low pressure and high temperature. Since the
reheat
sLeam is generated by heating water of the room temperature,
if residual oxygen in the water is few ppm and there is no
air mixture, it is possible to perform heat treatment in an
oxygen-free state, and the holding calorific value is high,
and force of transmitting heat and the drying capacity are
very strong. The reheat steam is superior about ten times
to the heat treatment capacity of the hot air, that is,
high-temperature air. Therefore, the
reheat steam is
effective in depriving the coal of the latent heat.
While particular embodiments of the present invention
have been illustrated and described in the above
description, it will be apparent to those skilled in the art
that various changes and modifications may be made without
departing from the spirit and scope of the invention as
defined in the following claims.
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The 'apparatus for drying coal using reheat steam
according to the present invention improves coal calorific
value, minimizes emissions of pollutants, protects the
corrosion of the system, improves its durability, reduces
the natural ignition rate along with a decrease in moisture,
improves the grinding efficiency of the coal differentiator
and thermal distribution of power boilers during the
combustion of coal, may eliminate the path clogging
phenomenon at the time of coal conveyance, and may enhance
usage of a low-grade coal of lower demand to improve the
stability of the coal feed, and thus, there is industrial
applicability.
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