JP2011214559A - Low grade coal drying system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve power generation efficiency by effectively utilizing exhaust heat generated in drying low grade coal.SOLUTION: This low grade coal drying system includes: a low grade coal drying device 102 drying the low grade coal 101 indirectly with latent heat of superheated steam A; a binary cycle 120 generating power by operating a steam turbine 124 by a circulating low boiling point heat medium 121; a preheater 128 provided in a process of circulating the heat medium 121, and preheating the heat medium 121 by indirect heat exchange with generated steam 104 generated from the low grade coal 101 by drying; an evaporator 127 provided in the process of circulating the heat medium 121, and vaporizing the heat medium 121 that has passed through the preheater 128, by indirect heat exchange with the generated steam 104; and a superheater 129 provided in the process of circulating the heat medium 121, and superheating the heat medium 121 that has passed through the evaporator 127, by indirect heat exchange with condensed water B produced by condensation of the superheated steam A that has dried the low grade coal 101.

Description

  The present invention relates to a low-grade coal drying system that uses, as a heat source, steam generated when low-grade coal is dried by a low-grade coal drying apparatus.

  For example, the Integrated Coal Gasification Combined Cycle (IGCC) system gasifies coal and combines it with combined cycle power generation consisting of a gas turbine and a steam turbine to achieve higher efficiency than conventional coal-fired power generation. This is a power generation system that aims to make it more environmentally friendly. This coal gasification combined power generation system has a great merit that it can use coal with abundant resources, and it is known that the merit will be further increased by expanding the types of applied coal.

  However, low-grade coal such as lignite and sub-bituminous coal has a large amount of moisture that is brought in, and there is a problem that power generation efficiency decreases due to this moisture. For this reason, it is necessary to dry the low-grade coal to remove moisture.

  Conventionally, for example, a low-grade coal drying system (a power generation method using low-grade coal as a fuel) described in Patent Document 1 shows a dehydration reforming process for removing moisture from low-grade coal. In this dehydration reforming process, the evaporated and separated water is in the state of steam, and this steam is used for heating the condensate derived from the power generation process.

Japanese Patent No. 4153448

  As described in Patent Document 1, by using the steam generated in the dehydration reforming process for heating the condensate derived from the power generation process, the power generation efficiency can be improved. However, in recent years, further improvement in power generation efficiency is eagerly desired.

  In view of the above problems, an object of the present invention is to provide a low-grade coal drying system capable of improving power generation efficiency by effectively using exhaust heat when drying low-grade coal.

  In order to achieve the above-mentioned object, the low-grade coal drying system of the present invention includes a low-grade coal drying apparatus that indirectly dries low-grade coal with the latent heat of superheated steam, and a steam turbine that uses a circulating low-boiling-point heat medium. A binary cycle that is operated to generate electricity and a process in which the heating medium circulates, and the generated steam generated from the low-grade coal by drying or the condensed water condensed by the superheated steam that has dried the low-grade coal. A preheater that preheats the heat medium by indirect heat exchange with at least one, and a process in which the heat medium circulates, and the heat medium that is indirectly exchanged with at least the other of the generated steam or the condensed water. And an evaporator that vaporizes the heat medium that has passed through a preheater.

  According to this low-grade coal drying system, the heat generated from the low-grade coal by drying and the exhaust heat of the condensed water condensed by the superheated steam that dries the low-grade coal are preheated and evaporated in the binary cycle. It can be effectively used for power generation in the binary cycle and can improve power generation efficiency.

  Further, in the low-grade coal drying system of the present invention, the evaporator is provided by indirect heat exchange with the condensed water in which the superheated steam obtained by drying the low-grade coal is provided in the process of circulating the heat medium. The preheater preheats the heat medium by indirect heat exchange with the generated steam generated from the low-grade coal by drying, and the evaporator is dried. Thus, the heat medium having passed through the preheater is vaporized by indirect heat exchange with generated steam generated from the low-grade coal.

  According to this low-grade coal drying system, the generated heat generated from the low-grade coal by drying and the exhaust heat of the condensed water condensed by the superheated steam that dried the low-grade coal are preheated and evaporated in the binary cycle. By using it for overheating, it can be effectively used for power generation in the binary cycle, and the power generation efficiency can be improved.

  In the low-grade coal drying system of the present invention, a coal gasification furnace using the low-grade coal dried by the low-grade coal drying apparatus as a gasification gas, and a gasification gas supplied from the coal gasification furnace Power generation system comprising: a gas turbine that is operated by using gas as a fuel; a generator that generates electric power by operating the gas turbine; and a steam turbine that is operated by steam generated by exhaust heat of turbine exhaust gas discharged from the gas turbine The low-grade coal is dried by using steam extracted from the steam turbine as superheated steam.

  According to this low-grade coal drying system, the steam extracted from the steam turbine of the coal gasification combined power generation system can be used as superheated steam for drying the low-grade coal.

  Further, in the low-grade coal drying system of the present invention, the heating medium that reaches the preheater by indirect heat exchange with the turbine exhaust gas that is provided in the process of circulating the heating medium and exhausted from the gas turbine is preliminarily provided. A pre-heater for preheating is provided.

  According to this low-grade coal drying system, exhaust heat of the exhaust gas of the power generation system is used for pre-heating of the heat medium in the binary cycle, so that it can be effectively used for power generation in the binary cycle and power generation efficiency can be improved.

  According to the present invention, it is possible to improve the power generation efficiency by effectively utilizing the exhaust heat generated when the low-grade coal is dried.

FIG. 1 is a schematic diagram illustrating an example of a low-grade coal drying system. FIG. 2 is a schematic diagram showing an example of a combined coal gasification combined power generation system to which the low-grade coal drying system shown in FIG. 1 is applied. FIG. 3 is a schematic diagram of the low-grade coal drying system according to Embodiment 1 of the present invention. FIG. 4 is a temperature-entropy diagram illustrating the heat medium used in the binary cycle. FIG. 5 is a schematic diagram of another example of the low-grade coal drying system according to Embodiment 1 of the present invention. FIG. 6 is a schematic diagram of another example of the low-grade coal drying system according to Embodiment 1 of the present invention. FIG. 7 is a schematic diagram of another example of the low-grade coal drying system according to Embodiment 1 of the present invention. FIG. 8 is a schematic diagram of another example of the low-grade coal drying system according to Embodiment 1 of the present invention. FIG. 9 is a schematic diagram of another example of the low-grade coal drying system according to Embodiment 1 of the present invention. FIG. 10 is a schematic diagram of a low-grade coal drying system according to Embodiment 2 of the present invention.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  The present embodiment will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating an example of a low-grade coal drying system.

As shown in FIG. 1, a low-grade coal drying system 100 includes a low-grade coal drying device 102 that dries a low-grade coal 101 such as lignite having a high water content, and a low-grade coal drying device 102 that is tubular. A heat transfer member 103 that supplies superheated steam (for example, 150 ° C. steam) A inside to remove moisture in the low-grade coal 101, and generation that occurs when the low-grade coal 101 is dried by the heat transfer member 103 A generated steam line L ₁ that discharges the steam 104 to the outside of the low-grade coal drying device 102, a dust collector 105 that is interposed in the generated steam line L ₁ and removes dust in the generated steam 104, and the dust collection tap a portion of the steam generated 104 dust is removed from the apparatus 105, the branch line L ₂ to be supplied to the low-grade coal drying device 102 as a fluidizing steam 107, withdrawn from the low-grade coal drying device 102 The dried coal 108 is cooled is intended and a cooler 110 to a product coal 109.

  In the low-grade coal drying system 100, the low-grade coal 101 is introduced into the low-grade coal drying apparatus 102 by a supply means (not shown) and is fluidized by the fluidized steam 107 separately introduced into the low-grade coal drying apparatus 102. A fluidized bed 111 is formed. The heat transfer member 103 described above is disposed in the fluidized bed 111. The superheated steam A at 150 ° C. is supplied into the heat transfer member 103, and the low-grade coal 101 is dried indirectly using the latent heat of the high-temperature superheated steam A. The superheated steam A used for drying is discharged to the outside of the low-grade coal drying apparatus 102 as, for example, 150 ° C. condensed water B.

  That is, on the inner surface of the heat transfer member 103 that is a heating means, the superheated steam A condenses into a liquid (moisture), so that the condensed latent heat radiated at this time is effectively used for heating the low-grade coal 101 for drying. ing. Any heating medium other than the high-temperature superheated steam A may be used as long as it is accompanied by a phase change. Examples thereof include Freon, pentane, and ammonia.

The generated steam 104 generated when the low-grade coal 101 is dried by the heat transfer member 103 is generated from the free board portion F formed in the upper space of the fluidized bed 111 in the low-grade coal drying apparatus 102. ₁ is discharged to the outside of the low-grade coal drying apparatus 102. Since the generated steam 104 includes a powder obtained by drying and pulverizing the low-grade coal 101, the generated steam 104 is collected by a dust collector 105 such as a cyclone or an electric dust collector and separated as a solid component 115. This solid component 115 is mixed with the dry coal 108 extracted from the low-grade coal drying apparatus 102 and cooled by the cooler 110 to obtain the product coal 109. This product charcoal 109 is used as a raw material for boilers, gasifiers, and the like.

On the other hand, the generated steam 104 after being collected by the dust collector 105 is discharged to the outside of the low-grade coal drying system 100 as steam at 105 to 110 ° C., for example. Part of the steam generated 104 after being dust collecting by a dust collector 105, is sent to the low-grade coal drying device 102 by the circulation fan 114 interposed in the branch line L _2, low-grade coal 101 Is used as fluidized steam 107 for fluidizing the fluidized bed 111. As a fluidizing medium for fluidizing the fluidized bed 111, a part of the generated steam 104 is reused. However, the fluidizing medium is not limited to this. For example, nitrogen, carbon dioxide, or a low oxygen concentration containing these gases is used. Air may be used.

  In addition, although the low grade coal 101 was illustrated as a to-be-dried material dried with the low-grade coal drying apparatus 102 mentioned above, as long as a moisture content is high, to-be-dried materials other than the low grade coal 101 may be made into drying object.

  An example applied to a coal gasification combined power generation (IGCC) system using the product coal 109 dried by the above-described low-grade coal drying apparatus 102 will be described. FIG. 2 is a schematic diagram showing an example of a combined coal gasification combined power generation system to which the low-grade coal drying system shown in FIG. 1 is applied.

  As shown in FIG. 2, the coal gasification combined power generation system 200 treats pulverized coal 201 a obtained by pulverizing coal (product charcoal 109 dried by the low-grade coal drying system 100) into a gasification gas 202. A coal gasification furnace 203 for conversion, a gas turbine (GT) 204 operated using the gasification gas 202 as a fuel, and a heat recovery steam generator (heat recovery steam generator) for introducing turbine exhaust gas 205 from the gas turbine 204 The steam turbine (ST) 208 operated by the steam 207 generated by the HRSG) 206, and the generator (G) 209 connected to the gas turbine 204 and / or the steam turbine 208 are provided.

The coal gasification combined power generation system 200 gasifies pulverized coal 201a pulverized by a mill 210 in a coal gasification furnace 203 to obtain a gasified gas 202 which is a generated gas. The gasified gas 202 is subjected to dust removal and gas purification by a cyclone 211 and a gas purification device 212, and then supplied to a combustor 213 of a gas turbine 204, which is a power generation means, where it is burned to produce a high-temperature and high-pressure combustion gas 214. Generate. The gas turbine 204 is driven by the combustion gas 214. The gas turbine 204 is connected to a generator 209, and the generator 209 generates electric power when the gas turbine 204 is driven. Since the turbine exhaust gas 205 after driving the gas turbine 204 still has a temperature of about 500 to 600 ° C., it is sent to an exhaust heat recovery boiler (HRSG) 206, where thermal energy is recovered. In the exhaust heat recovery boiler (HRSG) 206, steam 207 is generated by the thermal energy of the turbine exhaust gas 205, and the steam turbine 208 is driven by the steam 207. The exhaust gas 215 from which heat energy has been recovered by the exhaust heat recovery boiler (HRSG) 206 is released into the atmosphere via the chimney 217 after the NOx and SOx components in the exhaust gas 215 are removed by the gas purification device 216. . In the figure, reference numeral 218 denotes a condenser, 219 denotes air, 220 denotes a compressor, and 221 denotes an air separation device (ASU) that separates air into nitrogen (N ₂ ) and oxygen (O ₂ ). .

  According to this coal gasification combined cycle power generation system 200, even when gasifying using low-grade coal 101 having high moisture, the low-grade coal 101 is dried by the efficient low-grade coal drying device 102. Gasification efficiency is improved and power generation can be performed stably over a long period of time.

Moreover, in the coal gasification combined cycle power generation system 200, the efficiency of the coal-fired power plant, which has been about 40% in the past, can be improved to about 46% by combining the gas turbine and the steam turbine. By improving the plant efficiency, CO ₂ emissions can be reduced by about 13% compared to conventional coal fired boilers.

  Note that the power generation system using the product coal 109 dried by the low-grade coal drying system 100 according to the present embodiment is not limited to the coal gasification combined power generation system 200 described above. For example, although not clearly shown in the figure, the charcoal 109 dried by the low-grade coal drying system 100 is supplied to a boiler furnace, the steam turbine is driven by steam generated in the boiler furnace, and the output is generated by a generator. A power generation system using a boiler may be used.

[Embodiment 1]
FIG. 3 is a schematic diagram of a low-grade coal drying system according to the present embodiment. As shown in FIG. 3, the low-grade coal drying system 100 of the present embodiment uses the generated steam 104 at about 105 to 110 ° C. after being collected by the dust collector 105 in the binary cycle 120. .

  In the binary cycle 120, a circulation pump 123, a steam turbine 124 and a condenser 125 are provided in a heat medium circulation line 122 for circulating the heat medium 121. The steam turbine 124 is connected to a generator (G) 126. The heat medium 121 circulated through the heat medium circulation line 122 is a low boiling point heat medium that does not enter the wet region during the turbine expansion process, that is, as shown in the temperature-entropy diagram illustrating the heat medium in FIG. The slope of the saturation curve on the evaporation side during the turbine expansion process is preferably positive, and for example, isobutane or isopentane is applied.

  In the binary cycle 120, an evaporator 127, a preheater 128, and a superheater 129 are provided in the heat medium circulation line 122. The binary cycle 120 is arranged in the order of the circulation of the heat medium in the heat medium circulation line 122 in the order of the circulation pump 123, the preheater 128, the evaporator 127, the superheater 129, the steam turbine 124, and the condenser 125. Yes.

Evaporator 127, in a casing 127a for passing the heating medium 121, the heat transfer member 127b of the tubular which leads to generating steam line _{L 1} is provided. Furthermore, the preheater 128, in a casing 128a for passing the heating medium 121, the heat transfer member 128b of the tubular which leads to generating steam line _{L 1} is provided. Then, the generated steam 104 discharged from the low-grade coal drying apparatus 102 to the generated steam line L ₁ passes through the evaporator 127 and the preheater 128 in the order of the evaporator 127 and the preheater 128. That is, the generated steam 104 generated by drying the low-grade coal 101 in the low-grade coal drying apparatus 102 vaporizes the heat medium 121 by indirect heat exchange in the evaporator 127. Thereafter, the generated steam 104 preheats the heat medium 121 by indirect heat exchange in the preheater 128.

  In the superheater 129, a tubular heat transfer member 129 b connected to the line on the side where the condensed water B of the heat transfer member 103 in the low-grade coal drying apparatus 102 is discharged is provided in the casing 129 a through which the heat medium 121 passes. . That is, the condensed water B in which the superheated steam A obtained by drying the low-grade coal 101 is condensed passes through the superheater 129 and heats the heat medium 121 by indirect heat exchange.

  The binary cycle 120 is a process in which the heat medium 121 circulates in the heat medium circulation line 122 by the circulation pump 123, the heat medium 121 is preheated by the preheater 128, and then the heat medium 121 is vaporized by the evaporator 127. Subsequently, the heating medium 121 is heated by the superheater 129 and supplied to the steam turbine 124. Then, the steam turbine 124 is operated by the vaporized and superheated heat medium 121, and the generator 126 generates electric power.

  As described above, the low-grade coal drying system 100 according to the present embodiment uses the low-grade coal drying apparatus 102 that indirectly dries the low-grade coal 101 with the latent heat of the superheated steam A and the circulating low-boiling-point heat medium 121 to generate steam. The heat medium is obtained by indirect heat exchange between the binary cycle 120 that generates power by operating the turbine 124 and the generated steam 104 that is provided in the heat medium circulation line 122 through which the heat medium 121 circulates and is generated from the low-grade coal 101 by drying. A preheater 128 that preheats 121, an evaporator 127 that is provided in the heat medium circulation line 122 and vaporizes the heat medium 121 that has passed through the preheater 128 by indirect heat exchange with the generated steam 104, and the heat medium circulation line 122. The heating medium 121 that has passed through the evaporator 127 is heated by indirect heat exchange with the condensed water B condensed with the superheated steam A that has been dried on the low-grade coal 101. And a vessel 129.

  According to the low-grade coal drying system 100, the generated steam 104 generated from the low-grade coal 101 by drying and the exhaust heat of the condensed water B condensed by the superheated steam A drying the low-grade coal 101 are converted into a binary cycle 120. By using it for preheating, evaporation, and overheating of the heat medium 121, it is possible to effectively use it for power generation in the binary cycle 120 and improve power generation efficiency.

  By the way, the low-grade coal drying system 100 described above uses the condensed water B condensed with the superheated steam A obtained by drying the low-grade coal 101 for overheating the heating medium 121 in the superheater 129 of the binary cycle 120. But this is not the case. 5 to 9 are schematic views of other examples of the low-grade coal drying system according to the present embodiment.

  In the low-grade coal drying system 100 shown in FIG. 5, the condensed water B of the heat transfer member 103 in the low-grade coal drying device 102 is placed in the casing 127 a of the evaporator 127 instead of having the superheater 129 of FIG. 3. A tubular heat transfer member 127c connected to the line on the discharge side is provided. That is, the condensed water B in which the superheated steam A obtained by drying the low-grade coal 101 is condensed passes through the evaporator 127 and vaporizes the heat medium 121 through indirect heat exchange.

  In the low-grade coal drying system 100 shown in FIG. 6, the condensed water B of the heat transfer member 103 in the low-grade coal drying device 102 is placed in the casing 128 a of the preheater 128 instead of having the superheater 129 of FIG. 3. A tubular heat transfer member 128c connected to the line on the discharge side is provided. That is, the condensed water B condensed with the superheated steam A obtained by drying the low-grade coal 101 preheats the heat medium 121 through indirect heat exchange via the preheater 128.

  In the low-grade coal drying system 100 shown in FIG. 7, a heat transfer member 127c is provided together with the heat transfer member 127b in the casing 127a of the evaporator 127 instead of having the superheater 129 of FIG. Further, a heat transfer member 128c is provided in the casing 128a of the preheater 128 together with the heat transfer member 128b. That is, the condensed water B condensed with the superheated steam A obtained by drying the low-grade coal 101 passes through the evaporator 127 together with the generated steam 104 and vaporizes the heat medium 121 by indirect heat exchange. The condensed water B condensed with the superheated steam A obtained by drying the low-grade coal 101 passes through the preheater 128 together with the generated steam 104 and preheats the heat medium 121 by indirect heat exchange.

  In the low-grade coal drying system 100 shown in FIG. 8, a heat transfer member 127c is provided together with the heat transfer member 127b in the casing 127a of the evaporator 127 instead of having the superheater 129 of FIG. That is, the condensed water B condensed with the superheated steam A obtained by drying the low-grade coal 101 passes through the evaporator 127 together with the generated steam 104 and vaporizes the heat medium 121 by indirect heat exchange.

  In the low-grade coal drying system 100 shown in FIG. 9, the heat transfer member 128 c is provided together with the heat transfer member 128 b in the casing 128 a of the preheater 128 instead of having the superheater 129 of FIG. 3. That is, the condensed water B condensed with the superheated steam A obtained by drying the low-grade coal 101 passes through the preheater 128 together with the generated steam 104 and preheats the heat medium 121 by indirect heat exchange.

  As described above, another example of the low-grade coal drying system 100 according to the present embodiment includes a low-grade coal drying apparatus 102 that indirectly dries the low-grade coal 101 with the latent heat of the superheated steam A, and a circulating low boiling point heat. The generated steam 104 generated from the low-grade coal 101 or the low-grade coal 101 provided in the binary cycle 120 in which the steam turbine 124 is operated by the medium 121 to generate electric power and the heat-medium circulation line 122 through which the heat medium 121 circulates is generated. A preheater 128 that preheats the heat medium 121 by indirect heat exchange with at least one of the condensed water B condensed with the superheated steam A dried, and a heat medium circulation line 122 through which the heat medium 121 circulates. An evaporator 127 that vaporizes the heat medium 121 that has passed through the preheater by indirect heat exchange with at least the other of the generated steam 104 or the condensed water B.

  According to the low-grade coal drying system 100, the generated steam 104 generated from the low-grade coal 101 by drying and the exhaust heat of the condensed water B condensed by the superheated steam A drying the low-grade coal 101 are converted into a binary cycle 120. By using it for preheating and evaporation of the heat medium 121 in the above, it is possible to effectively use it for power generation in the binary cycle 120 and improve power generation efficiency.

[Embodiment 2]
FIG. 10 is a schematic diagram of a low-grade coal drying system according to the present embodiment. As shown in FIG. 10, in the low-grade coal drying system 100 of the present embodiment, the binary cycle 120 is added to the above-described low-grade coal drying system 100 of the first embodiment shown in FIG. The pre-heater 130 is provided between the circulation pump 123 and the pre-heater 128 and the heat medium 121 before reaching the pre-heater 128.

  The pre-heater 130 is provided with a tubular heat transfer member 130b to which the turbine exhaust gas 205 is supplied in a casing 130a through which the heat medium 121 passes. The turbine exhaust gas 205 is discharged from the gas turbine 204 in the above-described coal gasification combined power generation system 200 to which the low-grade coal 101 (product coal 109) dried by the low-grade coal drying apparatus 102 is applied. That is, the pre-heater 130 pre-heats the heat medium 121 reaching the pre-heater 128 in advance by indirect heat exchange with the turbine exhaust gas 205 discharged from the gas turbine 204.

  Thus, the low-grade coal drying system 100 of the present embodiment is a low-grade coal dried by the low-grade coal drying apparatus 102 in addition to the low-grade coal drying system 100 of the first embodiment shown in FIG. 3 described above. 101 (product charcoal 109) as a gasification gas 202, a gas gasification furnace 203, a gas turbine (GT) 204 operated using the gasification gas 202 supplied from the coal gasification furnace 203 as a fuel, and a gas turbine 204 And a generator (G) 209 that generates electricity by the operation of the above, and is indirectly provided with a turbine exhaust gas 205 provided in a heat medium circulation line 122 through which the heat medium 121 circulates and discharged from the gas turbine 204. A pre-heater 130 that pre-heats the heat medium 121 that reaches the pre-heater 128 by heat exchange is provided.

  According to the low-grade coal drying system 100, the exhaust heat of the exhaust gas from the power generation system is used for pre-heating of the heat medium 121 in the binary cycle 120, so that it can be effectively used for power generation in the binary cycle 120 to improve power generation efficiency. It becomes possible.

  By the way, the pre-heater 130 mentioned above can also be added to the low-grade coal drying system 100 of Embodiment 1 shown in FIGS. 5-9 mentioned above. Also in this low-grade coal drying system 100, exhaust heat of the exhaust gas from the power generation system is used for pre-heating of the heat medium 121 in the binary cycle 120 so that it can be effectively used for power generation in the binary cycle 120 to improve power generation efficiency. Is possible.

  In the low-grade coal drying system 100 according to Embodiment 1 and Embodiment 2 described above, the above-described coal gasification combined power generation system 200 is used as the superheated steam A supplied to the heat transfer member 103 of the low-grade coal drying apparatus 102. The steam extracted from the steam turbine 208 may be used.

  According to this low-grade coal drying system 100, steam extracted from the steam turbine 208 of the coal gasification combined power generation system 200 is used as superheated steam A for drying the low-grade coal 101, so that steam obtained by the steam turbine 208 is obtained. Can be used effectively.

  In the low-grade coal drying system 100 according to Embodiment 1 and Embodiment 2 described above, the low-grade coal drying device 102 has been described as a tubular heat transfer member 103, but superheated steam A is supplied to the inside. For example, a plate shape may be used.

  Further, in the low-grade coal drying system 100 according to the first and second embodiments described above, the low-grade coal drying apparatus 102 includes the low-grade coal 101 in which the fluidized steam 107 is introduced into the low-grade coal drying apparatus 102. Although the so-called fluidized bed drying apparatus in the form of fluidizing has been described as an example, it is not limited thereto. For example, the low grade coal 101 may be fluidized by conveying the low grade coal 101 while stirring it using a screw feeder.

  As described above, the low-grade coal drying system according to the present invention is suitable for improving the power generation efficiency by effectively utilizing the exhaust heat when the low-grade coal is dried.

DESCRIPTION OF SYMBOLS 100 Low grade coal drying system 101 Low grade coal 102 Low grade coal drying apparatus 103 Heat transfer member 104 Generated steam 105 Dust collector 107 Fluidized steam 108 Dry coal 109 Product coal 110 Cooler 111 Fluidized bed 114 Circulation fan 115 Solid component 120 Binary cycle 121 Low boiling point heat medium 122 Heat medium circulation line 123 Circulation pump 124 Steam turbine 125 Condenser 126 Generator 127 Evaporator 127a Casing 127b Heat transfer member 127c Heat transfer member 128 Preheater 128a Casing 128b Heat transfer member 128c Heat transfer Member 129 Superheater 129a Casing 129b Heat transfer member 130 Pre-heater 130a Casing 130b Heat transfer member 200 Coal gasification combined cycle system 201 Coal 202 Gasification gas 203 Coal gasification furnace 204 Gas turbine 205 Turbine exhaust gas 208 Steam turbine A Superheated steam B Condensate F Free board section L ₁ Generation steam line L ₂ Branch line

Claims (4)

A low-grade coal drying device that indirectly dries low-grade coal with the latent heat of superheated steam;
A binary cycle in which a steam turbine is operated by a circulating low boiling point heat medium to generate electricity;
Indirect heat exchange with at least one of the generated steam generated from the low-grade coal by drying or the condensed water condensed by the superheated steam drying the low-grade coal provided in the process of circulating the heat medium A preheater for preheating the heat medium,
An evaporator that is provided in a process in which the heat medium circulates and vaporizes the heat medium that has passed through the preheater by indirect heat exchange with at least the other of the generated steam or the condensed water;
A low-grade coal drying system characterized by comprising Provided in a process in which the heat medium circulates, comprising a superheater that superheats the heat medium that has passed through the evaporator by indirect heat exchange with condensed water in which the superheated steam that has dried the low-grade coal is condensed. ,
The preheater preheats the heating medium by indirect heat exchange with the generated steam generated from the low-grade coal by drying, and the evaporator is indirectly connected with the generated steam generated from the low-grade coal by drying. 2. The low-grade coal drying system according to claim 1, wherein the heat medium that has passed through the preheater is vaporized by natural heat exchange. A coal gasification furnace using the low-grade coal dried by the low-grade coal drying apparatus as a gasification gas, a gas turbine operated using the gasification gas supplied from the coal gasification furnace as fuel, and the gas Applied to a power generation system having a generator that generates electricity by operating a turbine, and a steam turbine that is operated by steam generated by exhaust heat of turbine exhaust gas discharged from the gas turbine;
The low-grade coal drying system according to claim 1 or 2, wherein the steam extracted from the steam turbine is used as superheated steam to dry the low-grade coal.   A pre-heater is provided in the process of circulating the heat medium to pre-heat the heat medium reaching the pre-heater in advance by indirect heat exchange with the turbine exhaust gas discharged from the gas turbine. The low-grade coal drying system according to claim 3.

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