JP2012083031A - Coal drying device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coal drying device capable of reducing consumption of coal and COemission per unit electricity generated.SOLUTION: A pulverizer 2 is disposed in a state that dried coal DC discharged from a steam tube dryer 1 can be charged thereto. A boiler 3 is mounted in a state that powdered coal pulverized by the pulverizer 2 can be charged thereto. The steam S1 generated in the boiler 3 and boiler combustion exhaust gas EG4 are distributed to a high-pressure steam turbine 7 through a first superheater 4. The exhaust steam S5 is discharged from a low-pressure steam turbine 8 connected to the high-pressure steam turbine 7, and the exhaust steam S5 is distributed to a steam condenser 9. The exhaust steam S5 is condensed by the condenser 9, the condensed water D1 is distributed to a heat exchanger 11 to exchange heat with dried exhaust gas DEG in the heat exchanger 11, and the heat is recovered from the dried exhaust gas DEG.

Description

The present invention relates to a coal drying apparatus and a coal drying method that can reduce the amount of coal used per unit power generation and CO ₂ emissions, and can be applied to coal-fired power generation facilities using coal as fuel.

In recent years, due to soaring coal prices, coal-fired power plants have come to use high moisture coal containing high moisture as fuel. However, when high moisture coal is used as a fuel, not only the power generation efficiency is reduced and the amount of coal used is increased, but also the amount of CO ₂ emitted is increased. Furthermore, as the amount of coal used increases, the power of the coal crusher of the coal-fired power plant and the exhaust gas blower of the boiler increase, which is not economical.

  In addition, coal is generally dried in a coal-fired power plant. This coal is dried by pulverizing the coal with a pulverizer such as a roller mill. By supplying, it is carried out with fine pulverization while preventing coal dust explosion. At this time, drying is adjusted at the temperature of the boiler combustion exhaust gas supplied to the pulverizer, and the high-temperature exhaust gas before heat recovery that recovers heat from the boiler combustion exhaust gas with an air heater or the like and the low-temperature exhaust gas after heat recovery are mixed as appropriate. To adjust the temperature.

  The amount of boiler combustion exhaust gas supplied to the fine pulverizer is related to the wind classifying ability of the fine pulverizer, etc., but it causes vibration and overload of the fine pulverizer, and therefore has an upper limit value and a lower limit value. Furthermore, the temperature of the boiler combustion exhaust gas supplied to the fine pulverizer has an upper limit value from the design temperature of the fine pulverizer. Therefore, conventionally, it has not been possible to cope with high moisture coal containing high moisture exceeding the specification range of the fine pulverizer.

In addition, the boiler combustion exhaust gas supplied to the fine pulverizer is supplied to the boiler as it is with the finely pulverized coal together with the water vapor generated by the drying of the coal. However, since there is no energy saving effect, it hardly contributes to improvement of power generation efficiency or CO ₂ reduction.

JP 7-279621 A JP-A-6-108058 JP 2005-172391 A

  On the other hand, a method has also been proposed in which steam is extracted from a steam turbine, air is heated using the extracted steam as a heating source, and the air is supplied to a pulverizer (Patent Document 1). However, as described above, this Patent Document 1 cannot be applied to high-moisture coal, and it has the disadvantage that it leads to an increase in the oxygen concentration in the pulverizer and increases the risk of a coal dust explosion.

  On the other hand, a method of extracting steam from a steam turbine and drying coal using the extracted steam as a heating source has already been proposed (Patent Document 2). However, the dry exhaust gas of coal is normally discharged to the atmosphere after being removed by a dust collector, and heat recovery (mainly latent heat of vaporization) cannot be economically performed by Patent Document 2.

  Here, considering the heat balance of the coal-fired power plant, the heat input and output heat are roughly as follows. The heat input is the amount of fuel, the amount of combustion air (atmosphere), the amount of pure water (room temperature), and the amount of heat output is the amount of heat dissipated in the condenser, the amount of heat emitted from the exhaust gas, the amount of heat released from the equipment, etc. The amount of power generation.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a coal drying device, and a coal drying method may reduce the coal consumption and CO ₂ emissions per unit of power generation.

The coal drying apparatus according to claim 1 is an indirect heating type dryer that discharges dry exhaust gas as it indirectly heats the coal charged in the casing through the wall surface of the heating passage through which heating steam provided in the casing circulates. Machine,
A coal-fired boiler that uses dried coal as fuel,
A steam turbine driven by steam generated by the coal-fired boiler;
A steam turbine condenser,
By heating the condensate by contacting the dry exhaust gas from the indirect heating dryer with the condensate of the condenser, the heat of the dry exhaust gas is recovered, and this condensate is supplied to the coal combustion boiler. Heat recovery means to send,
It is characterized by providing.

The operation of the coal drying apparatus according to claim 1 will be described below.
According to the coal drying apparatus of this claim, the indirect heating type dryer discharges the coal dried by charging and heating the coal, the coal combustion boiler burns the dried coal, Generate heat medium. In addition, the steam turbine is driven by the heat medium generated in the coal combustion boiler and the temperature of the heat medium is lowered, but the heat recovery means recovers heat from the dry exhaust gas discharged from the indirect heating dryer, for example, condensate and The heating medium is reheated and then the heated condensate is sent to a coal fired boiler.

Therefore, according to the coal drying apparatus of this claim, the heat recovery means recovers heat from the dry exhaust gas and reheats the heat medium whose temperature has been lowered by driving the steam turbine, and is discarded without being used conventionally. The heat that had been used can now be used effectively. As a result, coal consumption per unit power generation and CO ₂ emissions can be reduced, so that more efficient power generation is possible in coal-fired power generation facilities such as coal-fired power plants. became. It can be applied to direct heating dryers such as kilns and fluidized bed dryers, but indirect heating dryers have a higher dew point in the dry exhaust gas, and latent heat recovery is easier and latent heat recovery is possible. The amount also increases. Along with this, there is an advantage that it is easier to improve the power generation efficiency.

  Here, in order to improve the power generation efficiency by increasing the power generation amount while keeping the heat input constant, it is effective to reduce the amount of heat dissipated from the condenser or the heat amount of the exhaust gas. Along with this, conventionally, steam is extracted from the middle of the steam turbine to heat the feed water to the boiler, or the high-pressure steam turbine exhaust steam is reheated by the boiler and supplied to the next steam turbine. The so-called resuperheating method has reduced the amount of heat dissipated from the condenser and improved the power generation efficiency.

On the other hand, in this claim, not only can the power generation efficiency be improved by adopting a regeneration system that uses the steam steam of the steam turbine to heat the feed water to the boiler, but also the heating source of the steam extracted from the steam turbine As described above, dry exhaust gas from a dryer for drying coal previously burned in a boiler is used. This improved power generation efficiency and reduced coal consumption and CO ₂ emissions per unit power generation.

The operation of the coal drying apparatus according to claim 2 will be described below.
The coal drying apparatus according to the present invention has the same effect as that of the first aspect. However, the present invention has a configuration in which the heat recovery means is an indirect heat exchanger that indirectly exchanges heat between the dry exhaust gas and the condensate.

  According to this claim, about 90% of the condensation latent heat of the dry exhaust gas can be recovered by a simple device called an indirect heat exchanger. That is, most of the amount of heat supplied to the dryer can be recovered by this, so that the required amount of steam generated in the boiler need not increase substantially.

The operation of the coal drying apparatus according to claim 3 will be described below.
The coal drying apparatus according to the present invention has the same effect as that of the first aspect. However, in the present invention, the heat recovery means includes a wet scrubber into which dry exhaust gas is sent, and an indirect heat exchanger that exchanges heat between the circulating liquid of the wet scrubber and the condensate. ing.

  According to the present claim, about 90% of the condensation latent heat of the dry exhaust gas can be recovered by a simple apparatus such as a wet gas scrubber and an indirect heat exchanger. That is, as in claim 2, since most of the amount of heat supplied to the dryer can be recovered, the required amount of steam generated in the boiler need not increase substantially.

The operation of the coal drying apparatus according to claim 4 will be described below.
The coal drying apparatus according to the present invention has the same effect as that of the first aspect. However, in the present invention, the carrier gas fed into the indirect heating dryer and the drain of the heating steam are heat-exchanged to heat the carrier gas, and then the coal-fired boiler together with the heated condensate. It has the composition of sending to.
That is, the temperature of the condensate sent to the coal combustion boiler is thereby increased, resulting in a more efficient coal drying apparatus.

The operation of the coal drying apparatus according to claim 5 will be described below.
The coal drying apparatus according to the present invention has the same effect as that of the first aspect. However, the present invention has a configuration in which the exhaust gas of the coal combustion boiler is used as a carrier gas blown into the indirect heating dryer.
That is, the efficiency can be further improved by using the exhaust gas of the coal combustion boiler as the carrier gas.

In the method for drying coal according to claim 6, the coal is charged and heated with an indirect heating dryer, thereby discharging the dried coal and discharging the dried exhaust gas.
Next, the dried coal is burned in a coal-fired boiler to generate steam,
After this, the steam turbine is driven by this steam,
The heat recovery means recovers the heat from the dry exhaust gas discharged from the indirect heating dryer, drives the steam turbine to lower the temperature, and reheats the condensate that has become condensate in the condenser. Sending heated condensate to a coal fired boiler,
Including that.

The coal drying method according to the sixth aspect can improve the power generation efficiency and reduce the coal consumption per unit power generation amount and CO ₂ emission, similarly to the coal drying apparatus according to the first aspect.

The operation of the coal drying method according to claim 7 will be described below.
The coal drying method according to the present invention has the same effect as that of the sixth aspect. However, in this claim, when the coal is charged and heated by the indirect heating dryer, the drain is discharged from the indirect heating dryer, and the carrier gas fed into the indirect heating dryer is heated by this drain. After
The condensate after heat recovery from the dry exhaust gas and this drain are mixed.
That is, the power generation efficiency can be further improved by heating the carrier gas with the drain discharged from the indirect heating dryer.

The operation of the coal drying method according to claim 8 will be described below.
The coal drying method according to the present invention has the same effect as that of the sixth aspect. However, in this claim, flue gas is discharged when coal is burned in a boiler,
A part of the combustion exhaust gas is used as a carrier gas fed into an indirect heating dryer.
That is, if a part of the combustion exhaust gas from the boiler that is diffused into the atmosphere is used as the carrier gas of the indirect heating dryer, sensible heat can be recovered up to about 40 ° C., and the power generation efficiency can be further improved.

As described above, according to the present invention, it is possible to provide a coal drying apparatus and a coal drying method that can reduce coal consumption per unit power generation amount and CO ₂ emission.
That is, according to the present invention, a combination of simple equipment such as a device for recovering latent heat from dry exhaust gas and a device for supplying exhaust gas as a carrier gas, coal consumption per unit power generation and CO ₂ emissions It will also be possible to provide coal-fired power generation facilities capable of reducing the amount.

1 is a partially broken perspective view of a steam tube dryer applied to a first embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows the coal-fired power generation facility of the reheating and regeneration system to which the 1st Embodiment of this invention is applied, Comprising: The case where the carrier gas of a steam tube dryer is heated with a STD carrier gas heater is shown . It is the schematic which shows the coal-fired power generation facility of the reheating and regeneration system to which the 2nd Embodiment of this invention is applied, Comprising: The case where the carrier gas of a steam tube dryer is made into boiler exhaust gas is shown. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows the reheat-and-regeneration-type coal thermal power generation equipment to which the 1st Embodiment of this invention is applied, Comprising: The case where a dry exhaust gas scrubber and an indirect type heat exchanger are employ | adopted is shown.

  A first embodiment of a coal drying apparatus and a coal drying method according to the present invention will be described below with reference to the drawings. First, prior to describing the present embodiment, an example of a steam tube dryer (hereinafter referred to as STD as appropriate) that is an indirect heating rotary dryer applied to the embodiment of the present invention to deepen understanding will be described with reference to FIG. Will be described in advance.

  This steam tube dryer 1 shown in FIG. 1 has a plurality of heating pipes 31 arranged between both end plates in parallel with the axis in a rotary cylinder 30 that is rotatable around the axis. The STD heating steam S11 fed from the outside is supplied as heating steam to these heating pipes 31 through the attached heat medium inlet pipe 51 and circulates through the respective heating pipes 31, and then passes through the heat medium outlet pipe 52. The drain of the heated steam is discharged.

  The steam tube dryer 1 is provided with a charging device (not shown) having a screw or the like for charging the workpiece into the rotary cylinder 30. For example, coal or organic matter containing moisture, which is an object to be processed that has been thrown into the rotary cylinder 30 from the insertion port 53 of this charging device, is brought into contact with the heating pipe 31 heated by heating steam and dried. To become. At the same time, since the rotating cylinder 30 is installed with a downward slope, it is moved smoothly in the direction of the discharge port 54 so that the workpiece is continuously discharged from the other end side of the rotating cylinder 30. Yes.

  As shown in FIG. 1, the rotary cylinder 30 is installed on a base 36, and two sets of support rollers 35, 35 arranged parallel to the axis of the rotary cylinder 30 and spaced apart from each other, 34 is supported. The width between the two sets of support rollers 35 and 35 and the inclination angle in the longitudinal direction thereof are selected in accordance with the downward gradient and diameter of the rotating cylinder 30.

  On the other hand, in order to rotate the rotating cylinder 30, a driven gear 40 is provided around the rotating cylinder 30, and the drive gear 43 meshes with the driven gear 40, and the rotational force of the prime mover 41 is transmitted via the speed reducer 42. Thus, it rotates around the axis of the rotating cylinder 30. Further, a carrier gas CG is introduced into the inside of the rotary cylinder 30 from a carrier gas inlet 61, and the carrier gas CG is accompanied by a vapor obtained by evaporating moisture contained in coal or organic matter to be processed. It is discharged from the discharge port 62.

  In addition, the whole structure of the said steam tube dryer 1 is an example, and this invention is not limited by the said structure.

FIG. 2 is a schematic view showing a reheat / regeneration type coal-fired power generation facility to which the present embodiment is applied.
As shown in FIG. 2, a fine pulverizer 2 is arranged so that the dried dry coal DC discharged from the steam tube dryer 1 can be charged, and the fine pulverizer 2 is pulverized by the fine pulverizer 2. A boiler 3 is attached so that dry coal DC in powder form can be input. The steam S1 generated in the boiler 3 and the boiler combustion exhaust gas EG4 are sent to the first superheater 4, and the superheated steam S2 passing through the first superheater 4 is sent to the high-pressure steam turbine 7, This high-pressure steam turbine 7 is driven.

  The high-pressure steam turbine 7 is not only connected to the low-pressure steam turbine 8, but also connected to a generator (not shown), and the high-pressure steam turbine 7 and the low-pressure steam turbine 8 rotate in conjunction with each other. It is designed to generate power. In addition, the boiler combustion exhaust gas EG4 passes through the first superheater 4 and passes through the resuperheater 5 as boiler combustion exhaust gas EG5, and thereafter, is introduced into the air heater 6 as boiler combustion exhaust gas EG6. Eventually, the boiler combustion exhaust gas EG1 is used as exhaust gas, and the boiler combustion exhaust gas EG2 is supplied to the pulverizer 2.

  On the other hand, the exhaust steam S3 is discharged from the high-pressure steam turbine 7 to which the superheated steam S2 is input, and is input to the resuperheater 5, and is resuperheated by the resuperheater 5 to become the resuperheated steam S4. 8 is supplied. Accordingly, the exhaust steam S5 is discharged from the low-pressure steam turbine 8. The exhaust steam S5 is sent to the condenser 9, and the exhaust steam S5 is condensed into the condensate. This becomes the drain D1. The condenser 9 is connected to a heat exchanger 11, and the drain D1 is fed into the heat exchanger 11. The heat exchanger 11 exchanges heat with the dry exhaust gas DEG and recovers heat from the dry exhaust gas DEG.

  Further, the heat exchanger 11 is connected to the boiler 3, and the drain D <b> 1 passes through the heat exchanger 11 to become boiler feed water D <b> 2 and is fed into the boiler 3. At this time, extracted steam S9 and S10, which are part of the steam discharged from the middle of the low-pressure steam turbine 8, and extracted steam S7, S8 which are part of the steam discharged from the middle of the high-pressure steam turbine 7, In this way, the boiler feed water D2 is heated.

  On the other hand, the drain D3 discharged from the steam tube dryer 1 heats the outside air A3 with the STD carrier gas heater 10 to become the carrier gas CG, and becomes the drain D4 and is mixed with the boiler feed water D2. Yes.

Next, the procedure in the coal-fired power generation facility to which this embodiment is applied will be described.
As shown in FIG. 2, when the coal C is supplied to the steam tube dryer 1, it is dried to become dry coal DC, and the dried dry coal DC is discharged and the dry exhaust gas DEG is discharged. The dry coal DC is finely pulverized. It is pulverized by the machine 2. On the other hand, the outlet combustion exhaust gas EG6 and the outlet combustion exhaust gas EG1 having different temperatures before and after the air heater 6 are mixed to obtain an exhaust gas EG2 whose temperature is adjusted, and this exhaust gas EG2 is supplied to the pulverizer 2, The pulverizer 2 pulverizes the coal while drying it. Then, the exhaust gas EG2 is supplied to the boiler 3 accompanied by finely pulverized material, and burned by a burner (not shown) in the boiler 3.

  Steam S1, which is a heat medium generated in the boiler 3, is heated by the boiler combustion exhaust gas EG4 in the first superheater 4 to become superheated steam S2, and is supplied to the high-pressure steam turbine 7 to drive the high-pressure steam turbine 7. Part of the steam is extracted from the middle of the high-pressure steam turbine 7 to become extracted steam S7 and S8, and the boiler feed water D2 is heated. Most of the remaining steam is discharged from the high-pressure steam turbine 7 as exhaust steam S3, is re-superheated by the boiler combustion exhaust gas EG5 in the re-superheater 5, becomes re-superheated steam S4, and is supplied to the low-pressure steam turbine 8.

  Part of the steam is discharged from the middle of the low-pressure steam turbine 8 as extracted steam S9, S10, and similarly heats the boiler feed water D2. Further, STD heating steam S <b> 11 is extracted from one place in the middle of the low-pressure steam turbine 8 and supplied to the steam tube dryer 1. The pressure of the STD heating steam S11 at this time is 3 MPa or less, preferably O.D. The range is 3 MPa to 1.5 MPa. The STD heating steam S11 is heated by the steam tube dryer 1 to dry the coal C, condensed, and discharged as a drain D3. The drain D3 is heated to the air A3 taken from the outside in the STD carrier gas heater 10 to become the carrier gas CG, and then becomes the drain D4 and is used for heating the boiler feed water D2.

  The exhaust steam S5 of the low-pressure steam turbine 8 is condensed by the condenser 9, then recovered from the dried exhaust gas DEG by the heat exchanger 11 and reheated, and then mixed with the drain D4 to increase the temperature. As described above, the steam is heated by the extracted steam S7 to S10 of the high-pressure steam turbine 7 and the low-pressure steam turbine 8, and becomes boiler feed water D2 to supply water to the boiler 3.

  On the other hand, after the boiler combustion air A1 is heated by the air heater 6, the outlet combustion exhaust gas EG6 discharged from the resuperheater 5 becomes the combustion exhaust gas EG1, and most of it is processed by an exhaust gas treatment facility (not shown). And then released. In addition, it can also be set as the economizer which heats boiler feed water instead of the air heater 6. FIG.

Next, the operation of the coal drying apparatus and the coal drying method according to the present embodiment will be described below.
According to the present embodiment, the steam tube dryer 1 discharges the dry coal DC that has been dried by charging and heating the coal C, and the boiler 3 burns the dry coal DC that has been dried to form steam. Generate heat medium. Further, the steam turbines 7 and 8 are driven by the steam generated in the boiler 3 to lower the steam temperature and become condensate, but the heat exchanger 11 is a heat recovery means from the dry exhaust gas DEG discharged from the steam tube dryer 1. Recovers heat and reheats this heat medium, which is condensate.

Therefore, according to the present embodiment, the heat exchanger 11 recovers heat from the dry exhaust gas DEG and reheats the condensate whose temperature has been lowered by driving the steam turbines 7 and 8 and is discarded without being used conventionally. The heat that had been used can now be used effectively. As a result, coal consumption per unit power generation and CO ₂ emissions can be reduced, so that more efficient power generation is possible in coal-fired power generation facilities such as coal-fired power plants. became.

Furthermore, the dew point of the dry exhaust gas DEG discharged from the steam tube dryer 1 is normally 80 ° C. (0.546 kg-H ₂ O / kg-air) to 95 ° C., whereas the dew point in the condenser 9 is The temperature of water is usually 30 ° C to 35 ° C. For this reason, the dry exhaust gas DEG of the steam tube dryer 1 can recover the condensation latent heat by condensate until the dew point is about 40 ° C. (0.04884 kg-H ₂ O / kg-air).

  That is, the heat exchanger 11 is an indirect heat exchanger that exchanges heat between the dry exhaust gas DEG discharged from the steam tube dryer 1 and the condensate, and heat is exchanged between the dry exhaust gas DEG and the condensate. About 90% of the condensation latent heat of this dry exhaust gas DEG can be recovered with a simple device.

  As described above, since most of the heat supplied to the steam tube dryer 1 can be recovered by the above method, the required amount of steam generated in the boiler 3 does not need to be increased. Furthermore, if a part of the boiler combustion exhaust gas (usually 120 ° C. to 200 ° C.) diffused into the atmosphere is used as the carrier gas CG of the steam tube dryer 1, sensible heat can be recovered up to about 40 ° C.

Next, a second embodiment of the coal drying apparatus and the coal drying method according to the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the member demonstrated in 1st Embodiment, and the overlapping description is abbreviate | omitted.
In the first embodiment, the air A3 is heated by the STD carrier gas heater 10, but in this embodiment, the exhaust gas EG7 that is a part of the boiler combustion exhaust gas EG1 is used as the carrier gas CG. This also makes it possible to effectively use the exhaust gas, and to reduce the coal consumption and CO ₂ emission amount per unit power generation amount.

Next, a third embodiment of the coal drying apparatus and the coal drying method according to the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the member demonstrated in 1st Embodiment, and the overlapping description is abbreviate | omitted.
In the first embodiment, the drain D1 is sent to the heat exchanger 11 and is heat-exchanged with the dry exhaust gas DEG by the heat exchanger 11, and heat is recovered from the dry exhaust gas DEG. In the embodiment, the dry exhaust gas DEG discharged from the steam tube dryer 1 is input to the dry exhaust gas scrubber 12.

  An indirect heat exchanger 13 that exchanges heat between the circulating fluid of the dry exhaust gas scrubber 12 and the condensate is disposed adjacent to the dry exhaust gas scrubber 12. Therefore, according to this embodiment, the heat exchanger can recover about 90% of the condensation latent heat of the dry exhaust gas DEG by a simple heat exchanger such as the dry exhaust gas scrubber 12 and the indirect heat exchanger 13.

Next, an example of the effect by embodiment which concerns on this invention is demonstrated below.
Table 1 below shows the values of the power generation efficiency when the moisture of the coal is dried to 25%, 15%, 10%, and 5% for each condition. The main steam conditions at this time were 10 MPa and 540 ° C., and the reheating / regeneration system was adopted.

(Table 1)
Moisture content 25% 15% 10% 5%
STD 35.9% 36.2% 36.3% 36.4%
Latent heat recovery 36.3% 36.8% 37.0% 37.2%
Latent heat recovery + exhaust gas 36.4% 37.0% 37.2% 37.3%

Here, the contents of each condition will be described below.
“STD” is a case where the coal is dried using STD as a heat source from the extracted steam of the turbine.
“Latent heat recovery” refers to the case where heat is recovered from STD dry exhaust gas DEG (latent heat recovery) and the condensed water is heated using this as a heat source.
“Latent heat recovery + exhaust gas” means not only the above-described latent heat recovery but also the use of boiler exhaust gas before being released into the atmosphere as STD carrier gas CG.

  As described above, the power generation end efficiency is improved by pre-drying the coal, so that the power generation end efficiency is about O under the conditions of “latent heat recovery” and “latent heat recovery + exhaust gas” compared to “STD”. . It was confirmed that the improvement was about 5% to 1.0%.

  The embodiment according to the present invention has been described above, but the present invention is not limited to the embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the carrier gas of the dryer can be selected from not only a part of air and boiler combustion exhaust gas, but also any one of inert gases such as nitrogen gas, or a mixed gas thereof.

  The present invention can be applied not only to drying resins, foods, organic substances, etc., but also to drying for the purpose of drying woody biomass, organic waste, etc., and can also be applied to other industrial machines.

1 Steam tube dryer (indirect heating dryer)
2 Fine grinding machine (fine grinding means)
3 Boiler (Coal fired boiler)
7 High-pressure steam turbine 8 Low-pressure steam turbine 9 Condenser 11 Heat exchanger (heat recovery means)
12 Dry exhaust gas scrubber (heat recovery means, wet scrubber)
13 Indirect heat exchanger (heat recovery means)
30 Rotating cylinder (casing)
31 Heating tube (heating path)

Claims (8)

An indirect heating type dryer that discharges dry exhaust gas as it indirectly heats the coal charged in the casing through the wall surface of the heating path for circulating the heating steam provided in the casing;
A coal-fired boiler that uses dried coal as fuel,
A steam turbine driven by steam generated by the coal-fired boiler;
A steam turbine condenser,
By heating the condensate by contacting the dry exhaust gas from the indirect heating dryer with the condensate of the condenser, the heat of the dry exhaust gas is recovered, and this condensate is supplied to the coal combustion boiler. Heat recovery means to send,
A coal drying apparatus comprising:   The coal drying apparatus according to claim 1, wherein the heat recovery means is an indirect heat exchanger for indirectly exchanging heat between the dry exhaust gas and the condensate.   The coal drying apparatus according to claim 1, wherein the heat recovery means includes a wet scrubber into which dry exhaust gas is fed, and an indirect heat exchanger that exchanges heat between a circulating liquid of the wet scrubber and condensate.   The carrier gas sent into the indirectly heated dryer and the drain of the heating steam are heat-exchanged to heat the carrier gas, and then the drain is sent to the coal combustion boiler together with the heated condensate. The coal drying apparatus according to 1.   The coal drying apparatus according to claim 1, wherein the exhaust gas of the coal combustion boiler is used as a carrier gas blown into the indirect heating dryer. By charging coal and heating it with an indirect heating dryer, it discharges dry coal and exhausts dry exhaust gas,
Next, the dried coal is burned in a coal-fired boiler to generate steam,
After this, the steam turbine is driven by this steam,
The heat recovery means recovers the heat from the dry exhaust gas discharged from the indirect heating dryer, drives the steam turbine to lower the temperature, and reheats the condensate that has become condensate in the condenser. Sending heated condensate to a coal fired boiler,
Coal drying method including that. When the coal is charged and heated with the indirect heating dryer, the drain is discharged from the indirect heating dryer, and by this drain, the carrier gas sent to the indirect heating dryer is heated,
The coal drying method according to claim 6, wherein the condensate after heat recovery from the dried exhaust gas and the drain are mixed. Combustion exhaust gas is discharged when coal is burned in a boiler,
The coal drying method according to claim 6, wherein a part of the combustion exhaust gas is used as a carrier gas fed into an indirect heating type dryer.

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