WO2012132700A1

WO2012132700A1 - Coal-fired power generation plant and coal-fired power generation method

Info

Publication number: WO2012132700A1
Application number: PCT/JP2012/054761
Authority: WO
Inventors: 敏之木村; 隆行野口; 片岡　正樹
Original assignee: 月島機械株式会社
Priority date: 2011-03-25
Filing date: 2012-02-27
Publication date: 2012-10-04
Also published as: TW201319474A; JP2012202607A; AU2012235025A1; US20140013746A1; KR20140002743A; TWI544183B; KR101879471B1; AU2012235025B2; JP5535112B2

Abstract

[Problem] To provide a coal-fired power generation plant that not only recovers latent heat condensation from dry exhaust gas generated by drying facilities that dry coal in advance, but also is configured so that the amount of steam that flows in the final stage of a steam turbine does not materially differ from design values. [Solution] A coal-fired power generation plant comprising an indirect heat dryer (1) that has a heat medium flow channel in a housing and that indirectly heats coal brought into the housing using steam fed to the heat medium flow channel, thus drying the coal; a coal-firing boiler (3) that burns coal to generate steam; and a steam turbine (6) that generates power using the steam from the boiler (3). The boiler feedwater for the coal-firing boiler (3) is waste-heated using the extracted steam extracted from the steam turbine (6). The coal-fired power generation plant is provided with a system for using a portion of the extracted steam as the heating steam of the indirect heat dryer (1); a condenser (5) of the steam turbine (6); a wet scrubber (11) provided with a dry exhaust gas path from the indirect heat dryer (1); and heat recovery and heat exchange devices (22) (24) that perform heat exchange between the circulation water of the wet scrubber (11) and the condensation water of the condenser (5), wherein the condensation water that recovered the heat from the dry exhaust gas through the heat recovery and heat exchange devices (22) (24) is used to waste-heat the boiler feedwater.

Description

Coal thermal power generation facility and coal thermal power generation method

The present invention relates to a coal-fired power generation facility and a coal-fired power generation method in which coal is pre-dried, partially crushed, sent to a coal-fired boiler, and a steam turbine is driven to generate power.
In particular, not only the latent heat of condensation is recovered from the dry exhaust gas from the drying equipment for pre-drying the coal, but the amount of steam flowing through the final stage of the steam turbine is not greatly changed from the design value.
More specifically, it is suitable for suppressing a decrease in power generation efficiency when burning using low-grade coal such as lignite and subbituminous coal.

In recent years, due to soaring coal prices, new coal-fired power generation facilities have been devised to use high-moisture coal containing high moisture as fuel.

Also, existing coal-fired power generation facilities tend to change the coal used to low-grade (high moisture) coal. However, when low-grade coal such as lignite and sub-bituminous coal is burned, part of the heat of the coal is used for evaporation of moisture contained in the coal, and the amount of steam generated by the boiler is reduced accordingly. As a result, the power generation efficiency (power generation / coal heat) deteriorates.

For this reason, it is known to add a drying facility to pre-dry coal. This is because when the amount of heat of the high-pressure and high-temperature steam generated in the boiler is recovered as power by the steam turbine, a part of the steam at medium or low pressure is extracted from the steam turbine, and the condensation latent heat of this extracted steam is extracted. As a heating source, coal is pre-dried by this drying facility, and the dried coal is burned in a boiler, thereby improving power generation efficiency.

However, the condensing latent heat of the extracted steam is transferred to the dry exhaust gas generated when the coal is dried with the drying equipment, and if it is released as it is, not only will there be a loss of effective heat, but steam that has become medium or low pressure. When a part of the steam is extracted from the steam turbine, the amount of steam flowing through the final stage of the steam turbine decreases, exhaust loss increases, and turbine efficiency decreases.

In particular, if the existing coal-fired power generation facility is replaced with a coal type, etc., and the drying facility is added to pre-dry the coal using the steam extracted from the steam turbine as a heating source, the amount of steam flowing through the final stage of the steam turbine There is a possibility of a significant drop from the design value. Thus, when the amount of steam is greatly reduced, the turbine efficiency is lowered, and it is not possible to expect a sufficient improvement in power generation efficiency due to the preliminary drying of coal.

Furthermore, power demand is reduced at night, etc., and it is necessary to operate the coal-fired power generation facility at a low load. In this case, the amount of steam flowing through the final stage of the steam turbine further decreases, resulting in vibrations and the like. There is also a drawback that the range of low-load operation is narrowed as compared with the prior art.

JP-A-8-296835 JP-A-6-66107

The present invention has been made in view of the above background, not only recovering latent heat of condensation from the dry exhaust gas from the drying equipment for pre-drying the coal, but also the amount of steam flowing through the final stage of the steam turbine relative to the design value An object of the present invention is to provide a coal-fired power generation facility and a coal-fired power generation method capable of suppressing a decrease in power generation efficiency without greatly changing.

The invention according to claim 1, which has solved the above-mentioned problem,
An indirect heating dryer that has a heating medium passage in the casing and indirectly heats the coal charged in the casing with steam that feeds the heating medium passage to dry the coal;
A coal-fired boiler that generates steam by burning dry coal;
A steam turbine that generates power by steam from a boiler;
A coal-fired power generation facility that preheats boiler feed water to the coal-fired boiler with the extracted steam extracted from the steam turbine,
A system utilizing a part of the extracted steam as heating steam of the indirect heating dryer;
A condenser of the steam turbine;
Heat recovery means provided in the dry exhaust gas path from the indirect heating dryer;
The heat recovery means has heat recovery amount adjustment means for adjusting the heat recovery amount while transferring the heat of the dry exhaust gas to the condensate of the condenser,
A system that uses the condensate that has recovered the heat of the dry exhaust gas by the heat recovery means as the residual heat of the boiler feed water;
A coal-fired power generation facility characterized by comprising:

According to the coal-fired power generation facility according to claim 1, the drying facility pre-drys the coal using the steam extracted from the steam turbine as a heating source, and heat is recovered from the dried exhaust gas discharged from the drying facility by a heat recovery heat exchanger. Recover and reheat the boiler water supply to the boiler. At this time, by adjusting the heat recovery amount when recovering the heat from the dry exhaust gas, the amount of regeneration extracted steam from the low pressure (low temperature) portion of the steam turbine can be reduced or eliminated.

Although the amount of steam extracted for pre-drying varies depending on the moisture content and throughput of coal, the amount of steam extracted from the low-pressure steam turbine to heat the boiler feedwater can be adjusted by appropriately adjusting the amount of heat recovered from the dry exhaust gas. The amount can be adjusted. Therefore, by reducing or eliminating the amount of extracted steam extracted from the low-pressure steam turbine and reducing the variation in the amount of extracted steam, the amount of steam flowing through the final stage of the steam turbine greatly changes from the design value. Therefore, the displacement of the low-pressure steam turbine is within the allowable range.

As a result, according to the coal-fired power generation facility of the present invention, it is possible not only to recover the condensation latent heat from the dry exhaust gas discharged from the drying facility that pre-drys the coal using the condensation latent heat of the extracted steam of the steam turbine as a heating source, Since the amount of steam flowing through the final stage of the turbine does not change greatly with respect to the design value, it is possible to prevent the efficiency of the low-pressure steam turbine from being lowered.
When recovering the heat of the dry exhaust gas, if a wet scrubber is used, the sensible heat of the dry exhaust gas and the condensation latent heat of the vapor from which the moisture of the coal has evaporated can be transferred to the circulating water, and the heat recovery efficiency is high. In addition, by controlling the exhaust gas temperature at the outlet of the wet scrubber, it becomes easy to control the amount of extracted steam from the low pressure (low temperature) portion of the steam turbine.

According to a second aspect of the present invention, the heat recovery means exchanges heat between a wet scrubber provided in a dry exhaust gas path from the indirect heating dryer, circulating water of the wet scrubber, and condensate of the condenser. The coal thermal power generation facility according to claim 1, further comprising a heat recovery amount exchanger configured to adjust a heat recovery amount by controlling a circulating water amount of the wet scrubber.
When recovering the heat of dry exhaust gas, it is possible to use a dry exhaust gas-condensate gas-liquid shell and tube heat exchanger, but in comparison with this, the wet scrubber Becomes a circulating-condensate liquid-liquid heat exchanger, and the heat recovery efficiency is much higher. And since it is also easy to control the amount of circulating water, a heat recovery amount adjustment means can be comprised easily.

According to a second aspect of the present invention, the heat recovery means exchanges heat between a wet scrubber provided in a dry exhaust gas path from the indirect heating dryer, circulating water of the wet scrubber, and condensate of the condenser. The coal-fired power generation facility according to claim 1, further comprising a heat recovery amount exchanger configured to adjust a heat recovery amount by controlling a circulating water amount of the wet scrubber.

The invention of claim 3 is the coal-fired power generation facility according to claim 1, wherein the heat recovery means includes heat pump means.

For example, when drying high-moisture coal such as lignite with a drying facility until the moisture content becomes low, the temperature of the dried exhaust gas is usually 100 ° C or less, so the temperature of the condensate can be recovered by heat recovery and heat exchange with the condensate. Cannot be heated above 100 ° C. Therefore, the heat amount of the dry exhaust gas cannot be sufficiently recovered. If low-temperature waste heat that cannot be sufficiently recovered is converted into a high-temperature heat source using heat pump means, heat can be further recovered to heat the boiler feed water.

According to a fourth aspect of the present invention, the wet scrubber is of a two-stage type, receives boiler feed water heated by a first heat recovery heat exchanger corresponding to the circulating water of the first stage scrubber, and circulates water of the second stage scrubber. 3. The coal-fired power generation facility according to claim 1, wherein a second heat recovery heat exchanger corresponding to 1 heats boiler feed water to a higher temperature, and the second heat recovery heat exchanger has a heat pump configuration.

For example, the temperature of the first stage scrubber outlet of the dried exhaust gas is cooled to about 65 ° C., and the sensible heat and condensation latent heat of the dried exhaust gas are transferred to the circulating water of the first stage scrubber to heat the circulating water and condensate of the first stage scrubber. Replace and heat the condensate. The temperature of the condensate at this point is below the temperature of the dry exhaust gas.
The dried exhaust gas at the outlet of the first stage scrubber is passed through the second stage scrubber, for example, the temperature of the outlet of the second stage scrubber of the dried exhaust gas is cooled to about 30 ° C., and the sensible heat and condensation latent heat of the dried exhaust gas are circulated through the second stage scrubber. Move to water. However, since the circulating water temperature of the second stage scrubber is 65 ° C. at maximum, the condensate cannot be heated as it is. Here, when a heat pump using the circulating water of the second-stage scrubber as a heating source is introduced, a high-temperature liquid (for example, 120 ° C.) is recovered, and the condensed water can be further heated.
As a result, most of the heat extracted for drying can be recovered and used for heating the condensate.

The invention according to claim 5 is the coal-fired power generation facility according to claim 1, configured to send boiler combustion exhaust gas as a carrier gas into the casing of the indirect heating dryer.

When boiler combustion exhaust gas is sent as a carrier gas into the casing of the indirect heating dryer, the sensible heat of the boiler exhaust gas and the condensation latent heat of water vapor contained in the boiler exhaust gas can also be recovered and extracted for drying. The amount of heat that is greater than the amount of heat is recovered and the condensate can be heated, which not only saves energy, but also reduces the amount of low-pressure (low-temperature) steam for regeneration that exceeds the amount of extracted steam for drying. There is an advantage to expand.

The invention according to claim 6 has an indirect heating dryer that has a heating medium passage in the casing and indirectly heats and drys the coal with steam that feeds the coal charged into the casing into the heating medium passage.
A coal-fired boiler that generates steam by burning dry coal;
A steam turbine that generates power by steam from a boiler,
In a coal-fired power generation facility that preheats boiler feed water to the coal-fired boiler with extracted steam extracted from the steam turbine,
Utilizing a part of the extracted steam as heating steam of the indirect heating dryer, condensing the exhaust of the steam turbine by a condenser,
A heat recovery means is provided in the dry exhaust gas path from the indirect heating dryer, and the heat recovery means transfers the heat of the dry exhaust gas to the condensate of the condenser and adjusts the heat recovery amount. It has a collection amount adjustment means,
The coal thermal power generation method is characterized in that the condensate in which the heat of the dry exhaust gas is recovered by the heat recovery means is used as the residual heat of the boiler feed water.

According to a seventh aspect of the present invention, the boiler combustion exhaust gas is fed into the casing of the indirect heating dryer as a carrier gas, and the dew point of the dry exhaust gas is in the range of 80 ° C to 95 ° C. This is a coal-fired power generation method.

According to the present invention, not only recovering latent heat of condensation from the dry exhaust gas from the drying equipment for pre-drying the coal, the amount of steam flowing through the final stage of the steam turbine does not change significantly with respect to the design value, and the power generation efficiency It is possible to suppress the decrease of the.

1 is a partially broken perspective view of a steam tube dryer applied to a first embodiment of the present invention. It is the schematic which shows the coal-fired power generation facility of the regeneration system which concerns on the 1st Embodiment of this invention. It is the schematic which shows the coal-fired power generation facility of the regeneration system which concerns on the 2nd Embodiment of this invention. It is a principal part enlarged view of the 2nd Embodiment of this invention. It is a figure which shows the graph showing the relationship between the steam quantity of the last stage of a steam turbine, and exhaust loss. It is a figure which shows the graph showing the relationship between the dry exhaust gas temperature after heat recovery, and the ratio of the amount of steam which flows through the last paragraph of a turbine at the time of no prior drying equipment.

A first embodiment of a coal thermal power generation facility and a coal thermal power generation method according to the present invention will be described below with reference to the drawings. First, prior to explaining the present embodiment, an example of a steam tube dryer as an indirect heating rotary dryer that can be suitably used as a drying equipment applied to the embodiment of the present invention to deepen the understanding. 1 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. Extracted steam S7 sent from the outside through the attached heat medium inlet pipe 51 is supplied as heating steam to these heating pipes 31 and circulates through each of the heating pipes 31, and then this heat via the heat medium outlet pipe 52 The drain D of the heating 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 WC containing water or an organic substance, which is an object to be processed, which is input from one end side into the rotary cylinder 30 through the insertion port 53 of the charging device, is brought into contact with the heating tube 31 heated by heating steam. Become dry. 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 as dry exhaust gas DEG.

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 regeneration-type coal-fired power generation facility to which the present embodiment is applied.
As shown in FIG. 2, the dried dry coal DC discharged from the steam tube dryer 1 is fed into the pulverizer 2. The pulverized dry coal DC pulverized by the pulverizer 2 is put into the coal combustion boiler 3.

When low-grade (high moisture) coal WC is supplied to the steam tube dryer 1, steam extracted from the first steam turbine 6 described later is used as a heating source, and the coal WC is pre-dried in the steam tube dryer 1. , Obtained as dry charcoal DC.
With this drying operation, the dry exhaust gas DEG is discharged from the other end side of the steam tube dryer 1. The dry coal DC is finely pulverized while being dried by the fine pulverizer 2 as necessary, and then the exhaust gas EG2 is supplied from the fine pulverizer 2 to the boiler 3 along with the finely pulverized product and burned by a burner (not shown). The

The boiler 3 is provided with three heat exchangers from the first heat exchange unit 3A to the third heat exchange unit 3C. Steam, which is a heat medium generated from the boiler 3, is sent to the second heat exchanging unit 3 </ b> B and reheated, and the reheated superheated steam S <b> 1 is supplied to the high pressure steam turbine 7 of the first steam turbine 6. The high-pressure steam turbine 7 is supplied and driven. The high-pressure steam turbine 7 is not only connected to the low-pressure steam turbine 8 but also connected to the generator 6A, and the high-pressure steam turbine 7 and the low-pressure steam turbine 8 are driven and rotated in conjunction with each other, thereby recovering heat. Then, the generator 6A of the first steam turbine 6 generates electric power.

At this time, steam is extracted from the high-pressure steam turbine 7, and a part of this steam becomes extracted steam S2 and S3 to heat the boiler feed water D2 to the boiler 3 in the feed water line 12, but the remaining extracted steam S4 returns to the first heat exchanging section 3A of the boiler 3 and is reheated to become resuperheated steam S5, which is supplied to the low-pressure steam turbine 8 to be a driving force. In addition, a part of the extracted steam S6 extracted from the low-pressure steam turbine 8 heats the boiler feed water D2 in the feed water pipe 12 in the same manner.

On the other hand, the other extracted steam S7 extracted from the low-pressure steam turbine 8 of the first steam turbine 6 is used as a heating source for the steam tube dryer 1 and sent to the second steam turbine 9 which is a low-pressure steam turbine. Electric power is generated by a generator 9A attached to the second steam turbine 9. Thereafter, a part of the extracted steam S8, S9 from the second steam turbine 9 joins the drain D discharged from the steam tube dryer 1 and then is supplied to the water supply line 12, and also the water supply line 12 The boiler feed water D2 is also heated directly. The other extracted steam S10 from the second steam turbine 9 is sent to a condenser 5 that exchanges heat with seawater as cooling water, and the extracted steam S10 is condensed by the condenser 5. It becomes boiler feed water D1.

Moreover, after air is sent from the outside to the third heat exchanging section 3C of the boiler 3 and heated, it is sent into the boiler 3 to help the combustion of the dry coal DC. The exhaust gas discharged from the boiler 3 is A part of the gas is used as the carrier gas CG of the steam tube dryer 1 and the boiler combustion exhaust gas EG2 is sent to the pulverizer 2, and the remaining exhaust gas EG1 is discharged to the outside. In the present embodiment, the exhaust gas discharged from the boiler 3 is supplied as the carrier gas CG of the steam tube dryer 1 so that the dew point of the dry exhaust gas DEG is in the range of 80 ° C to 95 ° C. An inert gas such as air or nitrogen may be used so that the dew point of the exhaust gas DEG falls within this temperature range.

On the other hand, the condenser 5 is connected to a heat recovery means, and in particular, as shown in FIGS. 3 and 4, is connected to a wet scrubber 11 as a heat recovery means. As the moisture of the coal WC evaporates in the steam tube dryer 1, the exhaust gas DEG discharged is passed through the scrubber 11. In this scrubber 11, the sensible heat of the dry exhaust gas DEG and the condensing latent heat of the vapor from which the water content of the coal WC has evaporated are temporarily transferred to the circulating water, and then transferred to the circulating water. The amount of heat exchanges heat with the boiler feed water D1 that is condensed by the condenser 5 and sent to the scrubber 11, and this boiler feed water D1 becomes the boiler feed water D2. In this way, the scrubber 11 is heat-exchanged with the dry exhaust gas DEG from the steam tube dryer 1 to recover the heat that the dry exhaust gas DEG has.
When the wet scrubber 11 is used as the heat recovery means, as can be seen from FIG. 4, the heat recovery amount adjustment means can be assigned mainly to a circulation pump that adjusts the amount of circulating water.
The heat recovery means is not limited to the wet scrubber 11, and for example, as described above, a shell and tube heat exchanger or the like can be used.

Further, the scrubber 11 is connected to the boiler 3 through the water supply pipe 12, and the boiler feed water D2 is fed into the boiler 3, and is deaerated by the deaeration device 10 in the middle. At this time, extracted steam S2, S3, S6, S8, and S9, which are a part of the steam discharged from the

steam turbines

7, 8, and 9, are introduced in the middle of the water supply pipe 12 to supply the boiler feed water D2. Heat. That is, steam is extracted from each place of the

steam turbines

7, 8, and 9, and the boiler feed water D <b> 2 is heated to a predetermined temperature.

Next, the operation of the coal thermal power generation facility and the coal thermal power generation method according to the present embodiment will be described below.
According to the coal-fired power generation facility of the present embodiment, a regeneration method is employed in which the boiler feed water D2 to the boiler 3 is heated using the steam extracted from the

steam turbines

6 and 9. However, in the present embodiment, the steam tube dryer 1 pre-drys the coal WC using the extracted steam S7 extracted from the steam turbine 6 as a heating source, and then heats from the dry exhaust gas DEG discharged from the steam tube dryer 1. The scrubber 11, which is an exchanger, recovers heat and heats the boiler feed water D <b> 1 to the boiler 3.

At this time, the scrubber 11 adjusts the amount of heat recovered when recovering heat from the dry exhaust gas DEG, so that the extracted steam S6, S8 from the low-pressure steam turbines 8, 9 that are the low-pressure and low-temperature parts of the

steam turbines

6, 9 is obtained. , S9 is reduced.

Although the amount of steam extracted for pre-drying varies depending on the amount of water and the processing amount of coal WC, the boiler feed water D1 is heated by appropriately adjusting and changing the amount of heat recovered by the scrubber 11 from the dry exhaust gas DEG. Therefore, the temperature of the steam extracted from the low pressure steam turbines 8 and 9 can be adjusted. As a result, by reducing or eliminating the amount of extracted steam extracted from the low-pressure steam turbines 8 and 9 and reducing the variation in the amount of extracted steam, the amount of steam flowing through the final stage of the steam turbine is less than the design value. There is no significant change, and the displacement of the low-pressure steam turbines 8 and 9 is within the allowable range.

As described above, according to the coal thermal power generation facility of the present embodiment, the steam tube dryer 1 pre-drys the coal WC using the condensation latent heat of the extracted steam S7 of the steam turbine 6 as a heating source, but the steam tube dryer 1 discharges the coal WC. The condensed latent heat or the like can be recovered from the dried exhaust gas DEG. 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. Become. Furthermore, not only can the latent heat of condensation be recovered from the dry exhaust gas DEG, but the efficiency of the low-pressure steam turbines 8 and 9 is not reduced because the amount of steam flowing through the final stage of the steam turbine does not change significantly with respect to the design value. .

On the other hand, in the present embodiment, a boiler combustion exhaust gas selected from an inert gas such as air and nitrogen or a boiler combustion exhaust gas is supplied to the steam tube dryer 1 as the carrier gas CG, and the dew point of the dry exhaust gas DEG is set to 80. The range is from 0C to 95C.

Here, the higher the dew point of the dry exhaust gas DEG of the steam tube dryer 1, the lower the amount of dry exhaust gas, the more compact the dry exhaust gas treatment facility and the greater the amount of heat that can be recovered from the dry exhaust gas DEG. The temperature difference between the coal temperature and the heating steam temperature is reduced, and the drying capacity of the steam tube dryer 1 is reduced. For this reason, the dew point of the dry exhaust gas DEG is preferably 80 ° C. to 95 ° C., depending on the relationship between the amount of recovered heat and the drying capacity, depending on the moisture and amount of the coal WC to be dried.

Further, if the boiler exhaust gas is used as the carrier gas CG of the steam tube dryer 1 as in the present embodiment, the sensible heat of the boiler exhaust gas and the latent heat of condensation of the water vapor contained in the boiler exhaust gas can be recovered, saving energy. In addition, it is possible to reduce the amount of low pressure (low temperature) steam for regeneration that exceeds the amount of extracted steam for drying, and the operating range for low load operation can be expanded.

Next, a second embodiment of the coal thermal power generation facility and the coal thermal power generation method according to the present invention will be described with reference to FIGS. 3 and 4. 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 scrubber 11 is a heat exchanger, but in this embodiment, a two-stage scrubber 21 is used as a heat exchanger as shown in FIGS. 3 and 4. . The indirect heat exchanger 22 is disposed in the first stage scrubber 21A, and the indirect heat exchanger 22 heats the boiler feed water D1 with the circulating water W of the first stage scrubber 21A. It has become.

As shown in FIG. 4, the second stage scrubber 21B is provided with a heat pump unit 27, which is a heat pump means including an evaporator 24, a compressor 25, a condenser 26, and the like, and is indirectly connected to the first stage scrubber 21A. The boiler feed water D1 sent from the mold heat exchanger 22 is further heated between the circulating water W and finally becomes boiler feed water D2.

Thus, by having the structure which heats boiler feed water D2 in two steps, according to this Embodiment, not only can heat recovery from dry exhaust gas DEG efficiently, but boiler feed water D2 can be heated optimally, and scrubber 11 is heated. The amount of heat recovered during recovery can be easily adjusted, and the amount of extracted steam from the low-pressure steam turbines 8 and 9 is reduced. At this time, since the heat supplied from the second-stage scrubber circulating liquid is heated using the heat pump unit 27 and the boiler feed water D2 is heated, the amount of heat can be recovered more effectively.

Next, the relationship between the amount of steam at the final stage of the steam turbine and the exhaust loss will be described with reference to FIG.
Although the exhaust loss is small in the vicinity of the design point P, the exhaust loss increases, the turbine efficiency decreases, and the power generation efficiency decreases even when the steam amount increases or decreases from the design point P. As a result, it can be understood that the efficiency of the steam turbine is improved unless the fluctuation of the amount of extracted steam from the steam turbine is reduced and the amount of steam flowing through the final stage of the steam turbine is not largely changed from the design value.

Next, the relationship between the dry exhaust gas temperature after heat recovery and the ratio of the amount of steam flowing through the final stage of the steam turbine in the above embodiment without the pre-drying facility will be described with reference to FIG.
When the power generation amount is constant and the moisture of 65% coal is dried to 10% using the steam extracted from the steam turbine as the heating source, the temperature of the dry exhaust gas after heat recovery rises from the graph shown in this figure. This ratio is reduced to about 100% or less at about 70 ° C.

The extraction steam amount of the low-pressure steam turbine may be measured by installing a flow meter in the exhaust line from which the extraction steam is exhausted, and measuring with this flow meter or the amount of water condensed by the condenser 5. . The method for adjusting the heat recovery amount from the dry exhaust gas DEG is not particularly limited. For example, as in the above embodiment, the dry exhaust gas DEG is passed through the

scrubbers

11 and 21, and the circulating water is circulated to sensible heat of the dry exhaust gas DEG. It is preferable to transfer the condensation latent heat of the dry steam to the circulating water. When the circulating water and the boiler feed water D1 are indirectly heat exchanged, the amount of the boiler feed water D1 to be passed through the indirect heat exchanger 22 There is a method of controlling the exhaust gas temperature at the outlet.
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.

The present invention can be applied to a coal-fired power generation facility.

1 Steam tube dryer (indirect heating dryer)
3 Boiler 5 Condenser 6 First Steam Turbine 7 High Pressure Steam Turbine 8 Low Pressure Steam Turbine 9 Second Steam Turbine (Low Pressure Steam Turbine)
11 Scrubber (heat exchanger)
12 Water supply line 21 Scrubber (heat exchanger)
22 Indirect heat exchanger 27 Heat pump unit (heat pump means)

Claims

An indirect heating dryer that has a heating medium passage in the casing and indirectly heats the coal charged in the casing with steam that feeds the heating medium passage to dry the coal;
A coal-fired boiler that generates steam by burning dry coal;
A steam turbine that generates power by steam from a boiler;
A coal-fired power generation facility that preheats boiler feed water to the coal-fired boiler with the extracted steam extracted from the steam turbine,
A system utilizing a part of the extracted steam as heating steam of the indirect heating dryer;
A condenser of the steam turbine;
Heat recovery means provided in the dry exhaust gas path from the indirect heating dryer;
The heat recovery means has heat recovery amount adjustment means for adjusting the heat recovery amount while transferring the heat of the dry exhaust gas to the condensate of the condenser,
A system that uses the condensate that has recovered the heat of the dry exhaust gas by the heat recovery means as the residual heat of the boiler feed water;
A coal-fired power generation facility characterized by comprising:
The heat recovery means includes a wet scrubber provided in a dry exhaust gas path from the indirect heating dryer, and a heat recovery heat exchanger for exchanging heat between circulating water of the wet scrubber and condensate of the condenser. The coal-fired power generation facility according to claim 1, further comprising a heat recovery amount adjusting means for adjusting a heat recovery amount by controlling a circulating water amount of the wet scrubber.
The coal-fired power generation facility according to claim 1, wherein the heat recovery means includes a heat pump means.
The wet scrubber is a two-stage type,
Upon receiving the boiler feed water heated by the first heat recovery heat exchanger corresponding to the circulating water of the first stage scrubber, the second heat recovery heat exchanger corresponding to the circulating water of the second stage scrubber raises the boiler feed water to a higher temperature. The coal-fired power generation facility according to any one of claims 1 to 3, wherein the second heat recovery heat exchanger is heated and has a heat pump configuration.
The coal-fired power generation facility according to claim 1, configured to send boiler combustion exhaust gas as a carrier gas into a casing of the indirect heating dryer.
An indirect heating dryer having a heating medium passage in the casing and indirectly drying the coal with steam that feeds the coal charged into the casing into the heating medium passage;
A coal-fired boiler that generates steam by burning dry coal;
A steam turbine that generates power by steam from a boiler,
In a coal-fired power generation facility that preheats boiler feed water to the coal-fired boiler with extracted steam extracted from the steam turbine,
Utilizing a part of the extracted steam as heating steam of the indirect heating dryer, condensing the exhaust of the steam turbine by a condenser,
A heat recovery means is provided in the dry exhaust gas path from the indirect heating dryer, and the heat recovery means transfers the heat of the dry exhaust gas to the condensate of the condenser and adjusts the heat recovery amount. It has a collection amount adjustment means,
A coal-fired power generation method characterized in that condensate obtained by recovering the heat of dry exhaust gas by the heat recovery means is used as residual heat of the boiler feed water.
The coal-fired power generation method according to claim 6, wherein the boiler combustion exhaust gas is fed into the casing of the indirect heating dryer as a carrier gas, and the dew point of the dry exhaust gas is in the range of 80 ° C to 95 ° C.