KR20140002743A - Coal-fired power generation plant and coal-fired power generation method - Google Patents

Abstract

[PROBLEMS] In addition to recovering latent heat of condensation and the like from a dry exhaust gas in a drying facility for pre-drying coal, a coal-fired power generation facility in which the amount of steam flowing through the final short circuit of a steam turbine does not change significantly with respect to a design value is provided. [Solution] An indirect heating dryer 1 having a heating medium passage in a casing and indirectly heating the steam by feeding coal charged into the casing into the heating medium passage to dry coal, and burns coal to vaporize the steam. A coal-fired boiler (3) for generating steam, a steam turbine (6) for generating power by steam in the boiler (3), and a coal-fired boiler (3) with additional steam extracted from the steam turbine (6). A coal-fired power plant that heats boiler feed water to a furnace, the system using a portion of the additional steam as the heating steam of the indirect heating dryer (1), the condenser (5) of the steam turbine (6), and the indirect heating dryer (1). A wet scrubber 11 provided with a dry exhaust gas path of heat exchanger, heat recovery heat exchangers 22 and 24 for heat-exchanging a plurality of the circulating water of the wet scrubber 11 and the condenser 5, and the heat recovery heat exchanger 22 Gun by, 24) A plurality of recovered heat in the exhaust gas has a configuration using as the residual heat of the boiler feed water.

Description

Coal-fired Power Plants and Coal-fired Power Plants {COAL-FIRED POWER GENERATION PLANT AND COAL-FIRED POWER GENERATION METHOD}

The present invention relates to a coal-fired power generation facility and a coal-fired power generation method for generating coal by pre-drying, pulverizing, feeding into a coal-fired boiler and driving a steam turbine.

In particular, not only the latent heat of condensation and the like are recovered from the dry exhaust gas in the drying equipment for pre-drying coal, but also the amount of steam flowing through the final short circuit of the steam turbine is not significantly changed with respect to the design value.

In more detail, it is preferable to suppress the fall of the power generation efficiency at the time of burning using low quality coal, such as lignite and sub-bituminous coal.

In recent years, with the rise of coal prices, it is being studied to use high moisture coal containing high moisture as a fuel in a new coal-fired power plant.

Moreover, also in the coal-fired power generation facility already installed, there exists a tendency to change the coal to be used to lower grade (high moisture) coal than before. However, when low-grade coal such as lignite or sub-bituminous coal is combusted, part of the heat of coal is used for evaporation of water contained in coal, and as a result, the amount of steam generated by the boiler decreases, resulting in generation efficiency (power generation / coal). Calories) deteriorates.

Therefore, it is known to add a drying facility to pre-dry coal. When the heat quantity of the high pressure and high temperature steam which generate | occur | produced in a boiler is collect | recovered as a power by a steam turbine, a part of steam which became medium pressure or low pressure is extracted from a steam turbine, and a drying installation is made into the heat source as the latent heat of condensation of this additional steam. The coal is pre-dried and the dried coal is burned in a boiler to improve the power generation efficiency.

However, the latent condensation of additional steam is transferred to the dry exhaust gas generated when the coal is dried by the drying equipment, and when discharged as it is, not only effective heat is lost, but also a portion of the medium or low pressure steam is removed from the steam turbine. In the case of additionally recording, the amount of steam flowing through the final short circuit of the steam turbine is lowered, the exhaust loss is increased, and the turbine efficiency is lowered.

In particular, when a drying facility is added to pre-dry coal by using additional steam from the steam turbine as a heating source due to a change in coal type in an already installed coal-fired power plant, the amount of steam flowing through the final short circuit of the steam turbine It may fall considerably with respect to a design value. When the amount of steam is greatly reduced in this manner, the turbine efficiency is lowered, and a sufficient improvement in power generation efficiency due to predrying of coal cannot be expected.

In addition, the power demand is lowered at night and the coal-fired power generation equipment needs to be operated under a low load. However, at this time, the amount of steam flowing through the final short circuit of the steam turbine is further reduced, resulting in vibration and the like. There is also a problem that the range of operation is narrowed.

Patent Document 1: Japanese Patent Application Laid-Open No. 8-296835 Patent Document 2: Japanese Patent Laid-Open No. 6-66107

The present invention has been made to solve the above problems, and not only recovers latent heat of condensation from the dry exhaust gas in a drying facility for pre-drying coal, but also the amount of steam flowing through the final short circuit of the steam turbine does not change significantly with respect to the design value. Therefore, it aims at providing the coal-fired power plant and the coal-fired power generation method which can suppress the fall of power generation efficiency.

The invention according to claim 1 which solves the above problems,

An indirect heating dryer having a heating medium passage in the casing and indirectly heating the steam by feeding the coal charged into the casing into the heating medium passage to dry the coal;

A coal-fired boiler that generates steam by burning dry coal,

A steam turbine generating power by steam in a boiler,

A coal-fired power generation facility that heats boiler feed water to the coal-fired boiler by additional steam added from the steam turbine,

A system using a part of the additional steam as heating steam of the indirect heating dryer,

A condenser of the steam turbine,

Heat recovery means provided in a dry exhaust gas path from the indirect heat dryer;

The heat recovery means includes: heat recovery means having heat recovery amount adjusting means for transferring heat of the dry exhaust gas to a plurality of the plurality of condensers and adjusting the amount of heat recovery;

The system which uses the plurality which collect | recovered the heat which dry exhaust gas has by the said heat recovery means as a heat supply of the said boiler feed water,

It is a coal-fired power plant characterized in that it comprises.

According to the coal-fired power plant according to claim 1, the drying equipment pre-drys the coal using steam extracted from the steam turbine as a heating source, but heat is recovered by a heat recovery heat exchanger from the dry exhaust gas discharged from the drying equipment to generate a boiler. Heat the boiler feedwater to the furnace. At this time, by adjusting the heat recovery amount in the heat recovery from the dry exhaust gas, it is possible to reduce or eliminate the amount of additional steam for regeneration from the low pressure (low temperature) portion in the steam turbine.

The amount of steam to be added for predrying varies depending on the moisture and throughput of coal, but by appropriately adjusting the amount of heat recovery from the dry exhaust gas, the amount of steam extracted from the low pressure steam turbine can be adjusted to heat the boiler feed water. . Therefore, by reducing or eliminating the amount of additional steam to be extracted from the low pressure steam turbine and reducing the variation in the amount of additional steam, it is possible to prevent the amount of steam flowing through the final stage of the steam turbine from being greatly changed with respect to the design value. The displacement is within the allowable range.

As a result, according to the coal-fired power plant of the present invention, not only the latent heat of condensation and the like can be recovered from the dry exhaust gas discharged from the drying facility where the coal is pre-dried using the latent heat of condensation steam of the steam turbine as a heating source. Since the amount of steam flowing through the final short circuit of the turbine does not significantly change with respect to the design value, the efficiency of the low pressure steam turbine can be prevented from being lowered.

In the recovery of the heat of the dry exhaust gas, the use of a wet scrubber makes it possible to transfer the latent heat of the dry exhaust gas and the latent heat of condensation of the vapor from which the moisture of the coal has evaporated to the circulating water, so that the heat recovery efficiency is high. . Further, by controlling the outlet exhaust gas temperature of the wet scrubber, it becomes easy to control in the direction of suppressing the amount of additional vapor from the low pressure (low temperature) portion of the steam turbine.

The invention according to claim 2, wherein the heat recovery means includes a wet scrubber provided in a dry exhaust gas path from the indirect heat dryer, a heat recovery heat exchanger for heat-exchanging a plurality of the plurality of condensers with the circulating water of the wet scrubber. It is the coal-fired power plant of Claim 1 in which the heat recovery amount adjustment means which adjusts the heat recovery amount by controlling the circulation water volume of a wet scrubber is comprised.

When the heat which dry exhaust gas has is collect | recovered, it is also possible to use dry exhaust gas-multiple gas-liquid shell-and-tube type heat exchanger, etc., but in comparison with this, it is a wet type. Since the scrubber becomes a circulating water-plural liquid-liquid heat exchanger, the heat recovery efficiency is significantly higher. In addition, since it is also easy to control the amount of circulation water, the heat recovery amount adjusting means can be easily configured.

The invention according to claim 2, wherein the heat recovery means includes a wet scrubber provided in a dry exhaust gas path from the indirect heat dryer, a heat recovery heat exchanger for heat-exchanging a plurality of the plurality of condensers with the circulating water of the wet scrubber. It is the coal-fired power plant of Claim 1 in which the heat recovery amount adjustment means which adjusts the heat recovery amount by controlling the circulation water volume of a wet scrubber is comprised.

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

For example, in the case of drying the high moisture coal such as lignite by a drying facility until it becomes low moisture, the temperature of the dry exhaust gas is usually 100 ° C. or lower, so even if heat is recovered and heat exchanged with the plurality, the plurality of temperatures are 100 ° C. or higher. It cannot be heated by This results in a failure to recover the heat of the dry exhaust gas sufficiently. When the low-temperature waste heat that cannot be sufficiently recovered is converted to a high-temperature heat source by using a heat pump means, heat recovery can be performed again to heat the boiler feed water.

The invention according to claim 4, wherein the wet scrubber is a two-stage type, receives a boiler feed water heated by a first heat recovery heat exchanger corresponding to the circulating water of the first stage scrubber, and corresponds to a circulating water of the second stage scrubber. The 2 heat recovery heat exchanger heats boiler feed water further high temperature, The said 2nd heat recovery heat exchanger is a coal-fired power plant of Claim 1 or 2 which is a structure of a heat pump.

For example, the temperature of the first stage scrubber outlet of the dry exhaust gas is cooled to about 65 ° C., the sensible heat and the latent heat of condensation of the dry exhaust gas are transferred to the circulating water of the first stage scrubber, and the circulating water and the plurality of the first stage scrubber are exchanged. To heat the plurality. The plurality of temperatures at this point are equal to or less than the temperature of the dry exhaust gas.

The dry exhaust gas of the first stage scrubber outlet is cooled through the second stage scrubber, for example, the temperature of the second stage scrubber outlet of the dry exhaust gas is cooled to about 30 ° C., and the sensible heat and the latent heat of condensation of the dry exhaust gas are reduced to the second stage scrubber. To circulating water. However, since the circulating water temperature of the second stage scrubber is at most 65 ° C, a plurality of heatings cannot be performed 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 (eg, 120 ° C.) is recovered, so that the plurality can be further heated.

Thereby, most of the heat amount extracted for drying can be collect | recovered and can be used for several heating.

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

When the boiler combustion exhaust gas is supplied as a carrier gas into the casing of the indirect heating dryer, the sensible heat of the exhaust gas of the boiler and the latent heat of condensation of the water vapor contained in the boiler exhaust gas can also be recovered, so that the amount of heat equal to or greater than the amount of heat added for drying. Since the collected and heated plurality can be heated, not only energy can be saved, but also the reduction of the low-pressure (low temperature) steam amount for regeneration more than the amount of additional scavenging steam for drying can be reduced, and the operation range of low load operation can be extended.

Invention of Claim 6 has an indirect heat dryer which has a heating medium channel | path in a casing, and indirectly heats and dries coal by the steam which supplies the coal charged in the casing to a heating medium channel | path, and

A coal-fired boiler that generates steam by burning dry coal,

And a steam turbine generating power by steam in the boiler,

A coal-fired power generation facility that heats boiler feed water to the coal-fired boiler by extracting steam extracted from the steam turbine,

A part of the additional steam is used as heating steam of the indirect heating dryer, and the exhaust of the steam turbine is plural by a condenser,

Heat recovery means is provided in a dry exhaust gas path from the indirect heating dryer, and the heat recovery means transfers the heat of the dry exhaust gas to a plurality of the plurality of condensers and adjusts the amount of heat recovery. Equipped with a recovery amount adjusting means,

It is a coal-fired power generation method characterized by using the plurality which recovered the heat which dry exhaust gas has by the said heat recovery means as a residual heat of the boiler feed water.

The invention according to claim 7, 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. to be.

According to the present invention, not only the latent heat of condensation and the like are recovered from the dry exhaust gas in the drying equipment for pre-drying coal, but also the amount of steam flowing through the final short circuit of the steam turbine does not change significantly with respect to the design value, thereby reducing the power generation efficiency. It becomes suppressable.

1 is a partially broken perspective view of a steam tube dryer applied to the first embodiment of the present invention.
2 is a schematic view showing a coal-fired power plant of a regeneration system according to a first embodiment of the present invention.
It is a schematic diagram which shows the coal-fired power plant of the regeneration system which concerns on 2nd Embodiment of this invention.
It is an enlarged view of the principal part of 2nd Embodiment of this invention.
5 is a graph showing a relationship between the amount of steam at the final stage of the steam turbine and the exhaust loss.
FIG. 6 is a graph showing a relationship between the ratio of the dry exhaust gas temperature after heat recovery to the case where there is no predrying facility for the amount of steam flowing through the final short circuit of the turbine.

EMBODIMENT OF THE INVENTION Hereinafter, 1st Embodiment of the coal-fired power plant and the coal-fired power plant method which concerns on this invention is described, referring drawings. First of all, an example of a steam tube dryer as an indirect heating rotary dryer that can be preferably used as a drying apparatus applied to an embodiment of the present invention will be described in advance with reference to FIG. 1 before explaining the present embodiment. .

In this steam tube dryer 1 shown in FIG. 1, in the rotary cylinder 30 which became rotatable about an axial center, the some heating pipe 31 was piped in parallel with an axial center between both end plates, and a rotary joint The supplemental steam S7 transferred from the outside through the heat medium inlet pipe 51 mounted on the 50 is supplied to these heating pipes 31 as heating steam, circulated to each heating pipe 31, and then the heat medium outlet. The drain D of this heating steam is discharged | emitted through the pipe | tube 52.

And the steam tube dryer 1 is equipped with the charging apparatus which is not shown in figure which has a screw etc. in order to charge the to-be-processed object in the rotating cylinder 30. As shown in FIG. Coal WC, organic matter, or the like, which is an object to be processed, which is injected from one end side into the rotary cylinder 30 from the insertion port 53 of the charging device, is brought into contact with the heating tube 31 heated by heating steam to be dried. It was made. At the same time, since the rotary cylinder 30 is provided with a downward gradient, the object can be continuously discharged smoothly from the other end side of the rotary cylinder 30 by moving smoothly sequentially in the direction of the discharge port 54.

As shown in FIG. 1, the rotating cylinder 30 is installed on the base 36, and is provided with two sets of support rollers 35 and 35 spaced apart from each other in parallel with the axis of the rotating cylinder 30. As shown in FIG. Is supported through the tire 34. The width between these two sets of support rollers 35 and 35 and their longitudinal inclination angles are selected in accordance with the downward gradient and the diameter of the rotary cylinder 30.

On the other hand, in order to rotate the rotating cylinder 30, the driven gear 40 is provided in the circumference | surroundings of the rotating cylinder 30, the drive gear 43 meshes with each other, and the rotational force of the prime mover 41 is reduced by the reducer ( And is rotated about the axis of the rotating cylinder 30. In addition, the carrier gas CG is introduced into the rotary cylinder 30 from the carrier gas inlet 61, and the carrier gas CG is accompanied by a vapor from which moisture contained in coal or an organic substance evaporated, and the carrier gas outlet ( From 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.

2 is a schematic view showing a coal-fired power plant of a regeneration system to which the present embodiment is applied.

As shown in FIG. 2, the dried dry carbon DC discharged | emitted from the steam tube dryer 1 is made to input into the pulverizer 2. As shown in FIG. The pulverized dry coal DC pulverized and pulverized by the pulverizer 2 is put into the coal combustion boiler 3.

When coal WC of low quality (high moisture) is supplied to the steam tube dryer 1, the additional steam of the 1st steam turbine 6 mentioned later becomes a heating source, and preliminary drying of coal WC in the steam tube dryer 1 is carried out. Is carried out and obtained as dry coal DC.

According to this drying operation, dry exhaust gas DEG is discharged | emitted from the other end side of the steam tube dryer 1. The dry coal DC is pulverized while being dried by the pulverizer 2 as necessary, and then, the exhaust gas EG2 is supplied from the pulverizer 2 to the boiler 3 together with the pulverized material, to a burner not shown. Is burned.

The boiler 3 is equipped with three heat exchangers from the 3rd heat exchange part 3A to the 3rd heat exchange part 3C. Among these, steam which is a heat medium generated from the boiler 3 is transferred to the 2nd heat exchange part 3B, and is reheated, and the reheated superheated steam S1 is supplied to the high pressure steam turbine 7 of the 1st steam turbine 6. Thus, the 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 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 to generate heat. This is recovered and the generator 6A of the first steam turbine 6 generates electric power.

At this time, steam is additionally extracted from the high pressure steam turbine 7, and a part of the steam is additionally steamed S2 and S3 to heat the boiler feed water D2 to the boiler 3 in the water supply line 12. The remaining additional steam S4 returns to the first heat exchanger 3A of the boiler 3, is reheated to become the superheated steam S5, and is supplied to the low pressure steam turbine 8 to be a driving force. In addition, a part of the additionally added steam S6 extracted from the low pressure steam turbine 8 heats the boiler feed water D2 in the same manner by the water supply pipe 12.

On the other hand, the second additional steam S7 extracted from the low pressure steam turbine 8 of the first steam turbine 6 becomes the heating source of the steam tube dryer 1 and is the second steam turbine 9 which is a low pressure steam turbine 9. ) Is generated to generate power to the generator 9A attached to the second steam turbine 9. Thereafter, some of the additional steam S8 and S9 from the second steam turbine 9 joins the drain D discharged from the steam tube dryer 1 and is then supplied to the water supply line 12 and at the same time the water supply line 12 ) Is directly supplied to heat the boiler feed water (D2) equally. The other scavenging steam S10 from the second steam turbine 9 is transferred to the condenser 5 for exchanging seawater as cooling water. The condenser 5 receives plural scavenging steam S10 and supplies boiler water D1. )

In addition, after the air is transferred to the third heat exchange part 3C of the boiler 3 from outside and heated, it is transferred into the boiler 3 to assist the combustion of the dry coal DC, but the exhaust gas discharged from the boiler 3 is discharged. A part becomes carrier gas CG of the steam tube dryer 1, becomes boiler combustion exhaust gas EG2, and is conveyed to the pulverizer 2, and the other waste gas EG1 is discharged | emitted outside. And in this embodiment, although the exhaust gas discharged | emitted from the boiler 3 is supplied as carrier gas CG of the steam tube dryer 1 so that the dew point of dry exhaust gas DEG may be in the range of 80 to 95 degreeC, it dry You may use inert gas, such as air and nitrogen, which made the dew point of exhaust gas DEG into 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 discharged dry exhaust gas DEG passes through the scrubber 11. In the scrubber 11, the circulating water is cooled to a predetermined temperature. On the contrary, the latent heat of condensation of steam in which the sensible heat of the dry exhaust gas DEG and the water of the coal WC have evaporated is once transferred to the circulating water, and the amount of heat transferred thereafter. Is heat-exchanged with the boiler feed water D1 which is plural by the condenser 5 and transferred to the scrubber 11, and the boiler feed water D1 becomes the boiler feed water D2. In this manner, the scrubber 11 exchanges heat with the dry exhaust gas DEG from the steam tube dryer 1 to recover the heat possessed by the dry exhaust gas DEG.

In the case where the wet scrubber 11 is used as the heat recovery means, as can be seen from FIG. 4, the heat recovery amount adjusting means can be primarily responsible for the circulation pump that regulates the amount of circulation water.

The heat recovery means is not limited to the wet scrubber 11, and as described above, for example, a shell and tube type heat exchanger may be used.

Moreover, this scrubber 11 is connected to the boiler 3 via the water supply line 12, and boiler water D2 is conveyed to the boiler 3, and is degassed by the degassing apparatus 10 in the middle. do. At this time, additional steam S2, S3, S6, S8, and S9 serving as part of the steam discharged from the steam turbines 7, 8, and 9 is introduced in the middle of the water supply line 12 to heat the boiler feed water D2. That is, steam is additionally added from each of the steam turbines 7, 8, and 9 so that the boiler feed water D2 is heated to a predetermined temperature.

Hereinafter, the operation of the coal-fired power generation facility and the coal-fired power generation method according to the present embodiment will be described.

According to the coal-fired power plant of the present embodiment, a regeneration system for heating the boiler feed water D2 to the boiler 3 using steam extracted from the steam turbines 6 and 9 is employed. In the present embodiment, however, the steam tube dryer 1 pre-drys the coal WC by using the additional steam S7 extracted from the steam turbine 6 as a heating source, and then discharged from the steam tube dryer 1. The scrubber 11 which is a heat exchanger heat-recovers from the dry exhaust gas DEG used, and heats boiler feed water D1 to the boiler 3.

At this time, the scrubber 11 adjusts the heat recovery amount in the heat recovery from the dry exhaust gas DEG, so that the scavenging steam S6 from the low pressure steam turbines 8 and 9 which are the low pressure and low temperature portions in the steam turbines 6 and 9. , S8 and S9) are reduced.

In order to heat the boiler feed water D1, the amount of steam to be added for pre-drying is varied by the amount of water and the amount of processing of the coal WC, by appropriately adjusting and changing the amount of heat recovered by the scrubber 11 from the dry exhaust gas DEG. The temperature of steam extracted from the low pressure steam turbines 8 and 9 can be adjusted. As a result, the amount of steam flowing through the final short circuit of the steam turbine does not change significantly with respect to the design value by reducing or reducing the amount of additional steam to be extracted from the low pressure steam turbines 8 and 9 so as to reduce the variation of the additional steam. The displacement of (8, 9) falls within the allowable range.

As mentioned above, according to the coal-fired power plant of this embodiment, although the steam tube dryer 1 pre-drys coal WC using the latent heat of condensation of additional steam S7 of the steam turbine 6 as a heating source, a steam tube dryer The latent heat of condensation and the like can be recovered from the dry exhaust gas DEG discharged from (1). As a result, it is possible to reduce coal consumption and CO ₂ emissions per unit power generation, so that more efficient power generation can be achieved in a coal-fired power plant such as a coal-fired power plant. Further, not only the latent heat of condensation and the like can be recovered from the dry exhaust gas DEG, but also the amount of steam flowing through the final short circuit of the steam turbine does not change significantly with respect to the design value, so that the efficiency of the low pressure steam turbines 8 and 9 is not lowered.

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

Here, as the dew point of the dry exhaust gas DEG of the steam tube dryer 1 increases, the amount of dry exhaust gas decreases, the dry exhaust gas processing equipment becomes compact, and the amount of heat that can be recovered from the dry exhaust gas DEG also increases. The temperature difference between the coal temperature in the steam tube dryer 1 and the steam temperature for heating becomes small, so that the drying capacity of the steam tube dryer 1 decreases. Therefore, although it depends also on the moisture and the quantity of coal WC to dry from the relationship between these collect | recovery calories and drying capacity, 80 degreeC-95 degreeC of the dew point of dry exhaust gas DEG is preferable.

In addition, when 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 water vapor contained in the boiler exhaust gas can be recovered, thereby saving energy. In addition, it is possible to reduce the amount of regeneration low pressure (low temperature) steam more than the amount of additional drying steam for drying, and to expand the operating range of low load operation.

Next, a second embodiment of the coal-fired power generation facility and the coal-fired 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 duplication description is abbreviate | omitted.

In the first embodiment, the scrubber 11 is a heat exchanger. However, in the present embodiment, as shown in FIGS. 3 and 4, a two-stage scrubber 21 is used as the heat exchanger. Among these, the indirect heat exchanger 22 is arrange | positioned in 21 A of 1st stage scrubbers, and the indirect heat exchanger 22 supplies boiler feed water D1 between the circulating water W of the 1st stage scrubber 21A. ) Is heated.

In addition, as shown in FIG. 4, the heat pump unit 27 which is a heat pump means which consists of the evaporator 24, the compressor 25, the condenser 26, etc. is arrange | positioned in the 2nd stage scrubber 21B, The boiler feed water D1 delivered from the indirect heat exchanger 22 of the first stage scrubber 21A is heated again between the circulating water W and finally turns into the boiler feed water D2.

Thus, by having the structure which heats boiler feed water D2 in two stages, according to this embodiment, not only heat recovery from dry exhaust gas DEG can be efficiently carried out, but also boiler water feed D2 can be optimally heated, and the scrubber 11 The amount of heat recovery at the time of heat recovery can be easily adjusted, and the amount of additional steam from the low pressure steam turbines 8 and 9 is reduced. At this time, after heating up the heat collect | recovered from the 2nd stage scrubber circulating liquid using the heat pump unit 27, heating of boiler feed water D2 can heat-recover heat quantity more effectively.

Next, the relationship between the steam amount and the exhaust loss of the last stage of a steam turbine is demonstrated based on FIG.

The exhaust loss is small in the vicinity of the design point P. However, even if the amount of vapor increases or decreases from the design point P, the exhaust loss increases, so that the turbine efficiency is lowered and the power generation efficiency is lowered. As a result, it can be understood that the efficiency of the steam turbine becomes good if the variation in the amount of additional steam from the steam turbine is made small so that the amount of steam flowing through the final short circuit of the steam turbine is not significantly changed with respect to 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 short circuit of the steam turbine in the above embodiment when there is no predrying facility will be described with reference to FIG. 6.

If the amount of power generated is constant and the coal with the moisture content of 65% is dried up to 10% with additional steam from the steam turbine as a heating source, the ratio is increased as the temperature of the dry exhaust gas after heat recovery increases from the graph shown in this figure. It falls and becomes 100% or less about 70 degreeC boundary.

In addition, the measurement of the amount of bleeding steam of the low pressure steam turbine may be performed by providing a flowmeter in the exhaust line through which bleeding steam is exhausted, and measuring the flow rate by the flow meter 5 or the quantity of water plurally obtained by the condenser 5. The method for adjusting the heat recovery amount from the dry exhaust gas DEG is not particularly limited, but the dry exhaust gas DEG is circulated by circulating the circulating water so that the dry exhaust gas DEG passes through the scrubbers 11 and 21 as in the above-described embodiment, for example. It is preferable to transfer the sensible heat and the condensation latent heat of the dry steam to circulating water, and when indirect heat exchange between the circulating water and the boiler feed water D1, the boiler feed water D1 passing through the indirect heat exchanger 22 And a method of controlling the outlet exhaust gas temperature of the scrubber 21 by the amount.

As mentioned above, although embodiment which concerns on this invention was described, this invention is not limited to this embodiment, It can variously deform and implement in the range which does not deviate from the meaning of this invention.

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

1: Steam tube dryer (indirect heated dryer)
3: boiler
5: avengers
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 (7)

An indirect heating dryer having a heating medium passage in the casing and indirectly heating the steam by feeding the coal charged into the casing into the heating medium passage to dry the coal;
A coal-fired boiler that generates steam by burning dry coal,
A steam turbine generating power by steam in the coal-fired boiler,
A coal-fired power generation facility that heats boiler feed water to the coal-fired boiler by bleed steam extracted from the steam turbine,
A system using a part of the additional steam as heating steam of the indirect heating dryer,
A condenser of the steam turbine,
Heat recovery means provided in a dry exhaust gas path from the indirect heat dryer;
The heat recovery means has heat recovery amount adjusting means for transferring the heat contained in the dry exhaust gas to a plurality of the plurality of condensers and adjusting the amount of heat recovery.
The system which uses the plurality which collect | recovered the heat which dry exhaust gas has by the said heat recovery means as a heat supply of the said boiler feed water,
Coal-fired power generation equipment comprising a. The method of claim 1,
The heat recovery means has a wet scrubber provided in a dry exhaust gas path from the indirect heat dryer, a heat recovery heat exchanger for exchanging the circulating water of the wet scrubber and the plurality of the plurality of condensers, and controlling the amount of circulating water of the wet scrubber by controlling Coal-fired power generation equipment comprising a heat recovery amount adjusting means for adjusting the heat recovery amount. The method of claim 1,
Coal-fired power generation equipment, wherein the heat recovery means comprises a heat pump means. 4. The method according to any one of claims 1 to 3,
The wet scrubber is made of two stages,
The boiler feed water heated by the first heat recovery heat exchanger corresponding to the circulating water of the first stage scrubber is received, and the second heat recovery heat exchanger corresponding to the circulating water of the second stage scrubber heats the boiler feed water to a higher temperature. A coal fired power plant, wherein the second heat recovery heat exchanger is a configuration of a heat pump. The method of claim 1,
A coal fired power generation system, configured to feed 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 heating and drying the coal by steam for feeding coal charged into the casing into the heating medium passage;
A coal-fired boiler that generates steam by burning dry coal,
A steam turbine for generating power by steam in the coal-fired boiler,
A coal-fired power generation facility that heats boiler feed water to the coal-fired boiler by extracting steam extracted from the steam turbine,
A part of the additional steam is used as heating steam of the indirect heating dryer, and the exhaust of the steam turbine is plural by a condenser,
Heat recovery means is provided in a dry exhaust gas path from the indirect heating dryer, and the heat recovery means transfers the heat of the dry exhaust gas to a plurality of the plurality of condensers and adjusts the heat recovery amount. Have quantity adjusting means,
The coal-fired power generation method using the plurality which collect | recovered the heat which dry exhaust gas has by the said heat recovery means as a residual heat of the boiler feed water. The method according to claim 6,
A coal-fired power generation method, wherein a boiler combustion exhaust gas is fed into a 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.

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