JP2012197976A - Fluid bed drying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve drying efficiency in a fluid bed drying device.SOLUTION: The fluid bed drying device includes a drying container 101 making a hollow shape, an original coal input port 102 for inputting original coal to one end of the drying container 101, a dried coal output port 103 for outputting a dried coal obtained by heating and drying the original coal from the other end of the drying container 101, a fluidized gas feed port 104 for feeding fluidized gas to the lower part of the drying container 101 to form a flow bed S with the original coal, a gas discharge port 105 for discharging the fluidized gas and generated steam from the upper part of the original coal input port 102 at one end of the drying container 101, and a heat transfer pipe 106 for heating the original coal of the fluid bed S. A control device 125 is configured to regulate the aperture of a flow regulating valve 114 of a gas discharge line 113 on the basis of the temperature of the fluid bed S detected by a first temperature sensor 121 and to change a pressure in the drying container 101 and to change a dew point temperature.

Description

  The present invention relates to a fluidized bed drying apparatus for drying a material to be dried by fluidizing gas.

  For example, a combined coal gasification power generation facility is a power generation facility that aims to further increase the efficiency and environmental performance compared to conventional coal-fired power generation by gasifying coal and combining it with combined cycle power generation. This coal gasification combined cycle power generation facility has a great merit that it can use coal with abundant resources, and it is known that the merit can be further increased by expanding the applicable coal types.

  Conventional coal gasification combined power generation facilities generally have a coal supply device, a drying device, a coal gasification furnace, a gas purification device, a gas turbine facility, a steam turbine facility, an exhaust heat recovery boiler, a gas purification device, and the like. ing. Therefore, the coal is dried and then pulverized, supplied to the coal gasifier as pulverized coal, and air is taken in. The coal gas is combusted and gasified in this coal gasifier, and the product gas (combustible) Gas) is produced. Then, the product gas is purified and then supplied to the gas turbine equipment to burn and generate high-temperature and high-pressure combustion gas to drive the turbine. The exhaust gas after driving the turbine recovers thermal energy by the exhaust heat recovery boiler, generates steam and supplies it to the steam turbine equipment, and drives the turbine. As a result, power generation is performed. On the other hand, the exhaust gas from which the thermal energy has been recovered is released into the atmosphere through a chimney after harmful substances are removed by the gas purification device.

  By the way, the coal used in such a coal gasification combined power generation facility is not only a high-grade coal (high-grade coal) having a high calorific value such as bituminous coal and anthracite, but also a comparison such as sub-bituminous coal and lignite. There is a low-grade coal (low-grade coal) with a low calorific value. This low-grade coal has a large amount of moisture to be brought in, and the power generation efficiency decreases due to this moisture. For this reason, in the case of low-grade coal, it is necessary to dry the coal with the above-described drying apparatus to remove moisture and then pulverize and supply the coal gasifier.

  As a drying apparatus for drying such coal, there is one described in Patent Document 1 below. The control method and apparatus for a fluidized bed dryer described in Patent Document 1 introduces exhaust gas, which is a heat source, into a fluidized bed dryer as a heat source / fluidized gas to dry the wet raw material, and is introduced into the lower part thereof. A part of the gas is bypassed and introduced in the vicinity of the exhaust gas outlet, the FBD introduction gas amount is set to a constant value for stabilizing the fluidized bed, the processing amount and the dryness are set, and the exhaust gas system In order to prevent dew condensation in the circulation system, the exhaust gas relative humidity at the FBD outlet is set, the exhaust gas temperature of the heat source is measured, and the FBD introduction gas temperature, bypass exhaust gas amount, circulating exhaust gas amount as control variables according to the fluctuations The exhaust gas amount of the heat source is calculated and controlled.

JP-A-10-253251

  In the control method and apparatus of the fluidized bed dryer of Patent Document 1 described above, the exhaust gas temperature as a heat source for introducing the fluidized gas into the fluidized bed dryer and drying the wet raw material is measured, and the fluidized bed is changed according to the variation. It controls the temperature at which the dryer is introduced, the amount of bypass exhaust gas, the amount of circulating exhaust gas, and the amount of exhaust gas from the heat source. However, the fluidized bed dryer has a long response time due to the large heat capacity of the wet raw material and the dryer body that are put inside, and the temperature inside the fluidized bed dryer can be adjusted early even if the temperature and amount of exhaust gas are adjusted. However, it is difficult to always maintain stable operation and maintain the target throughput and dryness.

  The present invention solves the above-described problems, and an object thereof is to provide a fluidized bed drying apparatus capable of improving the drying efficiency.

  In order to achieve the above object, the fluidized bed drying apparatus of the present invention includes a drying container having a hollow shape, a wet raw material charging unit for charging a wet raw material into one end of the drying container, and the other end of the drying container. A dry matter discharge unit that discharges a dry product obtained by heating and drying the wet raw material, a fluidized gas supply unit that forms a fluidized bed together with the wet raw material by supplying a fluidizing gas to a lower part of the drying container, and the dry container A gas discharge unit that discharges fluidized gas and generated steam from above the wet raw material input unit on one end side, a heating unit that heats the wet raw material of the fluidized bed, and a dew point that changes the dew point temperature in the drying container A temperature changing device, a fluidized bed temperature detection sensor for detecting the temperature of the fluidized bed, and a control device for controlling the dew point temperature changing device based on a detection result of the fluidized bed temperature detection sensor. To do It is.

  Therefore, when the wet raw material is charged into the drying container from the wet raw material charging part and the fluidizing gas is supplied to the lower part of the drying container from the fluidizing gas supply part, the wet raw material flows by the fluidizing gas. A fluidized bed is formed, and the wet raw material of the fluidized bed is heated by the heating unit to be dried to become a dry product. The dry product is discharged to the outside from the dry product discharge unit, while the fluidized gas and the wet raw material are discharged. Vapor generated by drying is discharged from the gas discharge portion to the outside. At this time, the fluidized bed temperature detection sensor detects the temperature of the fluidized bed, and when the temperature of the fluidized bed fluctuates, the control device controls the dew point temperature changing device to change the dew point temperature in the drying container. Then, the drying degree of the wet raw material in the drying container becomes constant, and it becomes possible to always perform a stable drying process of the wet raw material, and it is possible to improve the drying efficiency.

  In the fluidized bed drying apparatus of the present invention, the dew point temperature changing device is a pressure reducing device that changes the pressure in the drying container, and the control device controls the pressure reducing device based on the temperature of the fluidized bed. It is characterized by that.

  Therefore, the temperature of the fluidized bed is determined by the dew point temperature that depends on the partial pressure of water vapor in the drying vessel. Therefore, by changing the pressure in the drying vessel based on the temperature of the fluidized bed, The deviation between the temperature and the dew point temperature in the drying container can be maintained at a predetermined value, so that a stable wet raw material drying process can always be performed.

  In the fluidized bed drying apparatus of the present invention, the control device controls the pressure reducing device to lower the pressure in the drying container when the temperature of the fluidized bed is lowered.

  Therefore, when the temperature of the fluidized bed decreases, the pressure in the drying container is decreased, whereby the deviation between the temperature of the fluidized bed and the dew point temperature in the drying container can be easily maintained at a predetermined value.

  In the fluidized bed drying apparatus of the present invention, the fluidized gas supply unit can supply water vapor and non-condensable gas as fluidized gas to the lower part of the drying container, and the dew point temperature changing device is fluidized. An apparatus for adjusting a water vapor concentration in the drying container by controlling a gas supply unit, wherein the control device controls the water vapor concentration adjusting device based on a temperature of the fluidized bed.

  Therefore, since the temperature of the fluidized bed is determined by the dew point temperature of the steam depending on the water vapor partial pressure in the drying container, by adjusting the water vapor concentration in the drying container based on the temperature of the fluidized bed, The deviation between the temperature of the fluidized bed and the dew point temperature in the drying container can be maintained at a predetermined value, and a stable wet raw material drying process can always be performed.

  The fluidized bed drying apparatus of the present invention is characterized in that the control device controls the water vapor concentration adjusting device to lower the water vapor concentration in the drying container when the temperature of the fluidized bed is lowered.

  Therefore, by reducing the water vapor concentration in the drying container when the temperature of the fluidized bed decreases, the deviation between the temperature of the fluidized bed and the dew point temperature in the drying container can be easily maintained at a predetermined value.

  In the fluidized bed drying apparatus of the present invention, the control device increases the supply amount of the non-condensable gas when the temperature of the fluidized bed decreases.

  Therefore, by increasing the supply amount of the non-condensable gas when the temperature of the fluidized bed decreases, the amount of fluidized gas in the drying container increases, and fluidization of the wet raw material can be promoted. It is possible to improve the drying efficiency.

  In the fluidized bed drying apparatus of the present invention, when the temperature of the fluidized bed is lowered, the control device decreases the supply amount of water vapor while increasing the supply amount of non-condensable gas, thereby fluidizing gas. It is characterized by maintaining a constant amount.

  Therefore, when the temperature of the fluidized bed is lowered, the amount of fluidized gas in the drying vessel is maintained at a constant amount by decreasing the amount of water vapor supplied while increasing the amount of non-condensable gas supplied. The pressure acting on the drying container does not become excessive, and safety can be improved.

  According to the fluidized bed drying apparatus of the present invention, the dew point temperature changing device that changes the dew point temperature in the drying container, the fluidized bed temperature detection sensor that detects the temperature of the fluidized bed, and the detection result of the fluidized bed temperature detection sensor. Since the control device for controlling the dew point temperature changing device is provided, the degree of drying of the wet raw material in the drying container is constant, and it becomes possible to always perform a stable drying process of the wet raw material, thereby improving the drying efficiency. be able to.

FIG. 1 is a schematic configuration diagram of a coal gasification combined power generation facility to which a fluidized bed drying apparatus according to Embodiment 1 of the present invention is applied. FIG. 2 is a schematic view of the fluidized bed drying apparatus of Example 1. FIG. 3 is a graph showing the dew point temperature with respect to the pressure in the container. FIG. 4 is a schematic diagram of a fluidized bed drying apparatus according to Embodiment 2 of the present invention. FIG. 5 is a graph showing the dew point temperature with respect to the water vapor concentration in the drying container. FIG. 6 is a schematic side view of a fluidized bed drying apparatus according to Example 3 of the present invention.

  Exemplary embodiments of a fluidized bed drying apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited by this Example, Moreover, when there exists multiple Example, what comprises combining each Example is also included.

  FIG. 1 is a schematic configuration diagram of a coal gasification combined power generation facility to which a fluidized bed drying apparatus according to a first embodiment of the present invention is applied, FIG. 2 is a schematic diagram of a fluidized bed drying apparatus of the first embodiment, and FIG. It is a graph showing dew point temperature with respect to the pressure in a container.

  The coal gasification combined power generation facility (IGCC: Integrated Coal Gasification Combined Cycle) of Example 1 adopts an air combustion method in which coal gas is generated in a gasification furnace using air as an oxidizer, and is purified by a gas purifier. Coal gas is supplied as fuel gas to gas turbine equipment to generate electricity. That is, the combined coal gasification combined power generation facility of this embodiment is a power generation facility of an air combustion system (air blowing). In this case, low-grade coal is used as the wet raw material supplied to the gasifier.

  In Example 1, as shown in FIG. 1, the coal gasification combined power generation facility 10 includes a coal supply device 11, a fluidized bed drying device 12, a pulverized coal machine (mill) 13, a coal gasification furnace 14, and a char recovery device 15. , A gas refining device 16, a gas turbine facility 17, a steam turbine facility 18, a generator 19, and a heat recovery steam generator (HRSG) 20.

  The coal feeder 11 includes a raw coal bunker 21, a coal feeder 22, and a crusher 23. The raw coal bunker 21 can store low-grade coal, and can drop a predetermined amount of low-grade coal into the coal feeder 22. The coal feeder 22 can transport the low-grade coal dropped from the raw coal bunker 21 by a conveyor or the like and drop it on the crusher 23. The crusher 23 can crush the dropped low-grade coal into a predetermined size.

  The fluidized bed drying device 12 supplies drying steam (superheated steam) to the low-grade coal introduced by the coal feeder 11 so as to heat and dry the low-grade coal while flowing. Moisture contained in the graded coal can be removed. The fluidized bed drying device 12 is provided with a cooler 31 for cooling the dried low-grade coal taken out from the lower portion, and the dried and cooled dried coal is stored in the dried coal bunker 32. Further, the fluidized bed drying apparatus 12 is provided with a dry coal cyclone 33 and a dry coal electrostatic precipitator 34 for separating dry coal particles from steam taken out from above, and the dry coal particles separated from the steam are dried coal bunker. 32 is stored. The steam from which the dry coal has been separated by the dry coal electrostatic precipitator 34 is compressed by the steam compressor 35 and then supplied to the fluidized bed drying device 12 as drying steam.

  The pulverized coal machine 13 is a coal pulverizer, and pulverizes the low-grade coal (dried coal) dried by the fluidized bed dryer 12 into fine particles to produce pulverized coal. That is, in the pulverized coal machine 13, the dry coal stored in the dry coal bunker 32 is dropped by the coal feeder 36, and this dry coal) is converted into low-grade coal having a predetermined particle size or less, that is, pulverized coal. . The pulverized coal after being pulverized by the pulverized coal machine 13 is separated from the conveying gas by the pulverized coal bag filters 37a and 37b and stored in the pulverized coal supply hoppers 38a and 38b.

  The coal gasification furnace 14 can supply pulverized coal processed by the pulverized coal machine 13 and can be recycled by returning the char (unburned coal) recovered by the char recovery device 15. .

  That is, the coal gasification furnace 14 is connected to the compressed air supply line 41 from the gas turbine equipment 17 (compressor 61), and can supply compressed air compressed by the gas turbine equipment 17. The air separation device 42 separates and generates nitrogen and oxygen from air in the atmosphere. A first nitrogen supply line 43 is connected to the coal gasifier 14, and a pulverized coal supply hopper is connected to the first nitrogen supply line 43. Charging lines 44a and 44b from 38a and 38b are connected. The second nitrogen supply line 45 is also connected to the coal gasification furnace 14, and the char return line 46 from the char recovery device 15 is connected to the second nitrogen supply line 45. Further, the oxygen supply line 47 is connected to the compressed air supply line 41. In this case, nitrogen is used as a carrier gas for coal and char, and oxygen is used as an oxidant.

  The coal gasification furnace 14 is, for example, a spouted bed type gasification furnace, which combusts and gasifies coal, char, air (oxygen) supplied therein or water vapor as a gasifying agent, and produces carbon dioxide. A combustible gas (product gas, coal gas) containing carbon as a main component is generated, and a gasification reaction takes place using this combustible gas as a gasifying agent. The coal gasification furnace 14 is provided with a foreign matter removing device 48 that removes foreign matter mixed with pulverized coal. In this case, the coal gasification furnace 14 is not limited to the spouted bed gasification furnace, and may be a fluidized bed gasification furnace or a fixed bed gasification furnace. The coal gasification furnace 14 is provided with a gas generation line 49 for combustible gas toward the char recovery device 15, and can discharge combustible gas containing char. In this case, by providing a gas cooler in the gas generation line 49, the combustible gas may be cooled to a predetermined temperature and then supplied to the char recovery device 15.

  The char recovery device 15 includes a dust collector 51 and a supply hopper 52. In this case, the dust collector 51 is constituted by one or a plurality of bag filters or cyclones, and can separate char contained in the combustible gas generated in the coal gasification furnace 14. The combustible gas from which the char has been separated is sent to the gas purification device 16 through the gas discharge line 53. The hopper 52 stores the char separated from the combustible gas by the dust collector 51. A bin may be disposed between the dust collector 51 and the supply hopper 52, and a plurality of supply hoppers 52 may be connected to the bin. A char return line 46 from the supply hopper 52 is connected to the second nitrogen supply line 45.

The gas purification device 16 performs gas purification by removing impurities such as sulfur compounds and nitrogen compounds from the combustible gas from which the char has been separated by the char recovery device 15. The gas purifier 16 purifies the combustible gas to produce fuel gas and supplies it to the gas turbine equipment 17. In the gas purifier 16, since the combustible gas from which the char is separated still contains sulfur (H ₂ S), the sulfur is finally removed by removing it with the amine absorbent. Is recovered as gypsum and used effectively.

  The gas turbine equipment 17 includes a compressor 61, a combustor 62, and a turbine 63, and the compressor 61 and the turbine 63 are connected by a rotating shaft 64. The combustor 62 has a compressed air supply line 65 connected to the compressor 61, a fuel gas supply line 66 connected to the gas purifier 16, and a combustion gas supply line 67 connected to the turbine 63. Further, the gas turbine equipment 17 is provided with a compressed air supply line 41 extending from the compressor 61 to the coal gasification furnace 14, and a booster 68 is provided in the middle. Therefore, in the combustor 62, the compressed air supplied from the compressor 61 and the fuel gas supplied from the gas purifier 16 are mixed and burned, and the rotating shaft 64 is rotated by the generated combustion gas in the turbine 63. By doing so, the generator 19 can be driven.

  The steam turbine facility 18 includes a turbine 69 that is coupled to the rotating shaft 64 in the gas turbine facility 17, and the generator 19 is coupled to the base end portion of the rotating shaft 64. The exhaust heat recovery boiler 20 is provided in the exhaust gas line 70 from the gas turbine equipment 17 (the turbine 63), and generates steam by exchanging heat between the air and the high temperature exhaust gas. Therefore, the exhaust heat recovery boiler 20 is provided with the steam supply line 71 between the steam turbine equipment 18 and the turbine 69 of the steam turbine equipment 18, the steam recovery line 72 is provided, and the steam recovery line 72 is provided with the condenser 73. Yes. Therefore, in the steam turbine facility 18, the turbine 69 is driven by the steam supplied from the exhaust heat recovery boiler 20, and the generator 19 can be driven by rotating the rotating shaft 64.

  The exhaust gas from which heat has been recovered by the exhaust heat recovery boiler 20 is freed of harmful substances by the gas purification device 74, and the purified exhaust gas is discharged from the chimney 75 to the atmosphere.

  Here, the action | operation of the coal gasification combined cycle power generation equipment 10 of Example 1 is demonstrated.

  In the coal gasification combined power generation facility 10 of the first embodiment, raw coal (low-grade coal) is stored in the raw coal bunker 21 by the coal feeder 11, and the low-grade coal of the raw coal bunker 21 is supplied to the coal. The machine 22 drops the crusher 23 where it is crushed to a predetermined size. The crushed low-grade coal is heated and dried by the fluidized bed drying device 12, cooled by the cooler 31, and stored in the dry coal bunker 32. Further, the steam taken out from the upper part of the fluidized bed drying device 12 is separated into dry coal particles by the dry coal cyclone 33 and the dry coal electrostatic precipitator 34 and compressed by the steam compressor 35 before being supplied to the fluidized bed drying device 12. Returned as drying steam. On the other hand, the dry coal particles separated from the steam are stored in the dry coal bunker 32.

  The dry coal stored in the dry coal bunker 32 is fed into the pulverized coal machine 13 by the coal feeder 36, where it is pulverized into fine particles to produce pulverized coal, and through the pulverized coal bag filters 37a and 37b. And stored in the pulverized coal supply hoppers 38a and 38b. The pulverized coal stored in the pulverized coal supply hoppers 38 a and 38 b is supplied to the coal gasification furnace 14 through the first nitrogen supply line 43 by nitrogen supplied from the air separation device 42. Further, the char recovered by the char recovery device 15 described later is supplied to the coal gasifier 14 through the second nitrogen supply line 45 by nitrogen supplied from the air separation device 42. Further, the compressed air extracted from the gas turbine equipment 17 to be described later is boosted by the booster 68 and then supplied to the coal gasification furnace 14 through the compressed air supply line 41 together with oxygen supplied from the air separation device 42.

  In the coal gasification furnace 14, the supplied pulverized coal and char are combusted by compressed air (oxygen), and the pulverized coal and char are gasified to generate combustible gas (coal gas) mainly composed of carbon dioxide. Can be generated. The combustible gas is discharged from the coal gasifier 14 through the gas generation line 49 and sent to the char recovery device 15.

  In the char recovery device 15, the combustible gas is first supplied to the dust collector 51, whereby the char contained in the gas is separated from the combustible gas. The combustible gas from which the char has been separated is sent to the gas purification device 16 through the gas discharge line 53. On the other hand, the fine char separated from the combustible gas is deposited on the hopper 52, returned to the coal gasifier 14 through the char return line 46, and recycled.

  The combustible gas from which the char has been separated by the char recovery device 15 is subjected to gas purification by removing impurities such as sulfur compounds and nitrogen compounds in the gas purification device 16 to produce fuel gas. In the gas turbine facility 17, when the compressor 61 generates compressed air and supplies the compressed air to the combustor 62, the combustor 62 is supplied from the compressed air supplied from the compressor 61 and the gas purification device 16. Combustion gas is generated by mixing with fuel gas and combusting, and the turbine 63 is driven by this combustion gas, so that the generator 19 can be driven via the rotating shaft 64 to generate power.

  The exhaust gas discharged from the turbine 63 in the gas turbine equipment 17 generates steam by exchanging heat with air in the exhaust heat recovery boiler 20, and supplies the generated steam to the steam turbine equipment 18. . In the steam turbine facility 18, the generator 69 can be driven through the rotating shaft 64 to generate electric power by driving the turbine 69 with the steam supplied from the exhaust heat recovery boiler 20.

  Thereafter, in the gas purification device 74, harmful substances in the exhaust gas discharged from the exhaust heat recovery boiler 20 are removed, and the purified exhaust gas is discharged from the chimney 75 to the atmosphere.

  Hereinafter, the fluidized bed drying apparatus 12 in the coal gasification combined power generation facility 10 described above will be described in detail.

  As shown in FIG. 2, the fluidized bed drying apparatus 12 includes a drying container 101, a raw coal charging port (wet raw material charging unit) 102, a dry coal discharging port (dry matter discharging unit) 103, and a fluidizing gas supply port. (Fluidized gas supply unit) 104, gas discharge port (gas discharge unit) 105, and heat transfer tube (heating unit) 106.

  The drying container 101 has a hollow box shape, and is formed with a raw coal charging port 102 for charging raw coal on one end side, and on the other end side, dried charcoal for discharging a dried product obtained by heating and drying raw coal. A discharge port 103 is formed. In addition, the drying container 101 is provided with a dispersion plate 107 having a plurality of openings at a predetermined distance from the bottom plate at the bottom, and fluidization that supplies fluidized gas (superheated steam) into the drying container 101 on the bottom plate. A gas supply port 104 is formed. In this case, a plurality of fluidizing gas supply ports 104 are provided in the longitudinal direction of the drying container 101, but one may be used. Further, the drying container 101 has a gas discharge port 105 for discharging the fluidized gas and the generated steam at the upper part on the dry coal discharge port 103 side.

  The drying container 101 is supplied with raw coal from the raw coal inlet 102 and supplied with fluidizing gas from the fluidizing gas supply port 104 through the dispersion plate 107, so that a predetermined thickness is provided above the dispersion plate 107. A fluidized bed S is formed, and a free board portion F is formed above the fluidized bed S. A heat transfer pipe 106 that circulates in the fluidized bed S from the outside through the drying container 101 is disposed, and the raw coal can be heated and dried by the superheated steam flowing in the heat transfer pipe 106.

  In the drying container 101, a fluidizing gas supply line 111 is provided for each fluidizing gas supply port 104, and a flow rate adjusting valve 112 is attached to the fluidizing gas supply line 111. Further, the drying container 101 is provided with a gas discharge line 113 for the gas discharge port 105, and a flow rate adjusting valve 114 and a fan 115 are attached to the gas discharge line 113. Further, in the drying container 101, the heat transfer pipe 106 is disposed in the fluidized bed S, and a flow rate adjustment valve 116 is attached to the superheated steam supply side of the heat transfer pipe 106.

  In addition, the drying container 101 is provided with a first temperature sensor (fluidized bed temperature detection sensor) 121 for detecting the temperature of the fluidized bed S and a second temperature sensor 122 for detecting the temperature of the free board portion F. Yes. Further, the drying container 101 is provided with a pressure sensor 123 that detects the pressure of the drying container 101.

  The control device 125 includes a temperature T1 of the fluidized bed S detected by the first temperature sensor 121, a temperature T2 of the free board portion F detected by the second temperature sensor 122, and a pressure P of the drying container 101 detected by the pressure sensor 123. Is entered. Further, the control device 125 adjusts the fluidizing gas supply amount supplied from the fluidizing gas supply ports 104 into the drying container 101 through the fluidizing gas supply line 111 by adjusting the opening degree of the flow rate adjusting valve 112. can do. In addition, the control device 125 is discharged from the drying container 101 to the gas discharge line 113 through the gas discharge port 105 by adjusting the opening degree of the flow rate adjusting valve 114 or adjusting the rotation speed of the fan 115. The amount of steam (fluidized gas amount + generated steam amount) can be adjusted. Furthermore, the control device 125 can adjust the heating amount of the fluidized bed S by adjusting the amount of superheated steam flowing through the heat transfer pipe 106 by adjusting the opening degree of the flow rate adjusting valve 116.

  And in a present Example, the dew point temperature in this drying container 101 is changed by adjusting the pressure in the drying container 101 according to the fluctuation | variation of the temperature in the fluidized bed S. FIG. In this case, a pressure reducing device is used as a dew point temperature changing device for changing the dew point temperature in the drying container 101, and specifically, a flow rate adjusting valve 114 provided in the gas discharge line 113 is applied. That is, by setting the flow rate adjusting valve 112 to a predetermined opening, a predetermined amount of fluidizing gas is supplied through the fluidizing gas supply line 111, while the fan 115 is rotated at a predetermined number of revolutions, and the flow rate adjusting valve 114 is By setting to a predetermined opening, when a predetermined amount of steam in the drying container 101 is discharged, the pressure (total pressure) in the drying container 101 is maintained at a predetermined pressure.

  In this operating state, if the opening degree of the flow rate adjustment valve 114 is increased, the amount of steam discharged from the inside of the drying container 101 increases, so that the pressure in the drying container 101 can be reduced. On the other hand, when the opening degree of the flow rate adjustment valve 114 is reduced in the above-described operation state, the amount of steam discharged from the inside of the drying container 101 decreases, so that the pressure in the drying container 101 can be increased. Here, the pressure in the drying container 101 is adjusted by adjusting the opening degree of the flow rate adjustment valve 114. However, the opening degree of the flow rate adjustment valve 114 is made constant or eliminated, and the rotation speed of the fan 115 is adjusted. By adjusting the pressure, the pressure in the drying container 101 may be adjusted.

  And if the pressure in the drying container 101 is increased / decreased, the dew point temperature in this drying container 101 can be raised / lowered. In this case, since the temperature of the fluidized bed S is determined by the dew point temperature of the water vapor that depends on the water vapor partial pressure in the drying vessel 101, the pressure in the drying vessel 101 is changed based on the temperature of the fluidized bed S. By doing so, it becomes possible to maintain the deviation between the temperature of the fluidized bed S and the dew point temperature in the drying container at a predetermined value, and it is possible to always give a certain degree of heating to the raw coal of the fluidized bed S. It becomes.

  Specifically, the control device 125 adjusts the pressure in the drying container 101 by adjusting the opening of the flow rate adjustment valve 114 based on the detection result of the first temperature detection sensor 121, and adjusts the pressure in the drying container 101. Change the dew point temperature. That is, when the temperature of the fluidized bed S decreases, the control device 125 increases the opening degree of the flow rate adjustment valve 114 and decreases the pressure in the drying container 101.

  Here, the operation of the fluidized bed drying apparatus 12 of Example 1 will be described.

  In the fluidized bed drying device 12, the raw coal is supplied from the raw coal inlet 102 to the drying container 101 and the fluidized gas is supplied from the fluidized gas supply port 104 through the dispersion plate 107. A fluidized bed S having a predetermined thickness is formed above the dispersion plate 107. The raw coal moves through the fluidized bed S to the dry coal discharge port 103 side by the fluidizing gas, and is heated and dried by receiving heat from the heat transfer tube 106 at this time. In this case, the raw coal is heated and dried by the heat from the heat transfer tube 106 while moving from the raw coal inlet 102 to the dry coal outlet 103. Specifically, the raw coal is in a preheated state immediately after being fed from the raw coal inlet 102, and the water hardly evaporates. When the raw coal enters the drying region beyond the preheating region, the water evaporation starts and gradually increases. Then, the amount of evaporation becomes maximum, and decreases as the dry coal discharge port 103 is approached.

  Then, the dry coal from which the raw coal has been dried is discharged to the outside through the dry coal discharge port 103, and the steam generated when the raw coal is heated and dried in the fluidized bed S rises together with the fluidized gas and is discharged into the gas. The gas is discharged from the outlet 105 to the outside.

  At this time, as shown in FIGS. 2 and 3, the control device 125 supplies a predetermined amount of fluidizing gas through the fluidizing gas supply line 111 by setting the flow rate adjustment valve 112 to a predetermined opening degree. On the other hand, the control device 125 rotates the fan 115 at a predetermined rotational speed and sets the flow rate adjustment valve 114 to a predetermined opening, thereby discharging a predetermined amount of steam in the drying container 101. In such an operation state of the fluidized bed drying apparatus 12, the temperature T1 of the fluidized bed S in the drying vessel 101 is maintained at 110 ° C., and the pressure (total pressure) is maintained at 100 kPa. In this case, the pressure P in the drying container 101 and the temperature T1 of the fluidized bed S are set such that a deviation Ta between the temperature T1 of the fluidized bed S in the drying container 101 and the dew point temperature in the drying container 101 is set. By determining the intersection point A, a sufficient amount of heat drying in the raw coal is ensured.

  If the supply amount of the raw coal increases or the water content of the raw coal increases in the operating state of the fluidized bed drying device 12, the temperature T1 of the fluidized bed S decreases. At this time, for example, when the control device 125 detects that the temperature T1 of the fluidized bed S has decreased from 110 ° C. to 105 ° C., the control device 125 increases the opening of the flow regulating valve 114. Then, since the amount of steam discharged from the drying container 101 increases, the pressure in the drying container 101 is reduced, and the dew point temperature in the drying container 101 decreases. In this case, even if the temperature T1 of the fluidized bed S is lowered, the deviation between the temperature T1 of the fluidized bed S in the drying container 101 and the dew point temperature in the drying container 101 similar to the deviation Ta in the operation state described above. By determining the intersection B between the pressure P in the drying vessel 101 and the temperature T1 of the fluidized bed S so that Tb is set, a sufficient amount of heat and dryness in the raw coal is ensured.

  That is, the control device 125 sets the pressure P in the drying container 101 such that the deviation Ta = Tb, and adjusts the opening degree of the flow control valve 114 so as to be the pressure P in the drying container 101. . The relationship among the temperature T1, the dew point temperature, and the pressure P of the fluidized bed S is preferably mapped in advance according to the form of the fluidized bed drying device 12.

  When the heating and drying of the raw coal in the fluidized bed S progresses and the temperature T1 of the fluidized bed S increases, the control device 125 decreases the opening of the flow rate adjustment valve 114, and reverses the drying. A predetermined deviation between the temperature T1 in the container 101 and the dew point temperature is secured.

  Thus, in the fluidized bed drying apparatus of Example 1, the drying container 101 having a hollow box shape, the raw coal charging port 102 for charging the raw coal to one end of the drying container 101, and the drying container 101 A dry coal discharge port 103 for discharging dry coal obtained by heating and drying the raw coal from the other end side, and a fluidized gas supply port for forming a fluidized bed S together with the raw coal by supplying a fluidizing gas to the lower part of the drying vessel 101. 104, a gas discharge port 105 for discharging fluidized gas and generated steam from above the raw coal input port 102 on one end side of the drying vessel 101, and a heat transfer tube 106 for heating the raw coal of the fluidized bed S are provided and controlled. The device 125 changes the pressure P in the drying container 101 by adjusting the opening degree of the flow rate adjustment valve 114 of the gas discharge line 113 based on the temperature T1 of the fluidized bed S detected by the first temperature sensor 121. Change dew point temperature To have.

  Therefore, when raw coal is introduced into the drying container 101 from the raw coal inlet 102 and fluidized gas is supplied from the lower part of the drying container 101 through the dispersion plate 107 from the fluidized gas supply port 104, the raw coal is supplied. When fluidized gas flows, a fluidized bed S is formed. When the raw coal of the fluidized bed S moves by fluidized gas, it is heated by the heat transfer tube 106 to be dried to become dry coal. Is discharged to the outside from the dry coal discharge port 103, while steam generated by drying the fluidized gas and raw coal is discharged to the outside from the gas discharge port 105. At this time, when the temperature T1 of the fluidized bed S varies, the control device 125 adjusts the opening degree of the flow rate adjustment valve 114 and adjusts the pressure P in the drying container 101 to change the dew point temperature. Then, the degree of drying of the raw coal in the drying container 101 becomes constant, and it becomes possible to always perform a stable raw coal drying process, and it is possible to improve the drying efficiency.

  In this case, the control device 125 changes the dew point temperature by adjusting the pressure P in the drying container 101 by adjusting the opening degree of the flow rate adjustment valve 114 based on the temperature T1 of the fluidized bed S. Specifically, the control device 125 decreases the pressure P in the drying container 101 by increasing the opening degree of the flow rate adjustment valve 114 when the temperature T1 of the fluidized bed S decreases.

  Therefore, since the temperature of the fluidized bed S is determined by the dew point temperature that depends on the water vapor partial pressure in the drying vessel 101, the pressure P in the drying vessel 101 is changed based on the temperature T1 of the fluidized bed S. Thus, the deviation between the temperature T1 of the fluidized bed S and the dew point temperature in the drying vessel 101 can be maintained at a predetermined value, and a stable raw coal drying process can always be performed.

  FIG. 4 is a schematic diagram of a fluidized bed drying apparatus according to Example 2 of the present invention, and FIG. 5 is a graph showing the dew point temperature with respect to the water vapor concentration in the drying container. In addition, the same code | symbol is attached | subjected to the member which has the function similar to the Example mentioned above, and detailed description is abbreviate | omitted.

  In Example 2, as shown in FIG. 4, the fluidized bed drying apparatus 12 includes a drying container 101, a raw coal inlet 102, a dry coal outlet 103, a fluidized gas supply port 104, and a gas outlet 105. And a heat transfer tube 106.

  This drying container 101 is provided with a fluidizing gas supply line 111 for each fluidizing gas supply port 104. A water vapor supply line 131 is provided and a flow rate adjustment valve 132 is attached, a non-condensable gas supply line 133 is provided and a flow rate adjustment valve 134 is attached, and the two lines 131 and 133 are merged. Thus, the fluidizing gas supply line 111 is formed. Further, the water vapor supply line 131 and the non-condensable gas supply line 133 are positioned upstream of the flow rate adjusting valves 132 and 134, and flow meters 135 and 136 for measuring the water vapor supply amount and the non-condensable gas supply amount are provided. It is installed. Here, the non-condensable gas is, for example, combustion exhaust gas, argon gas, nitrogen gas, or the like.

  Further, the drying container 101 is provided with a gas discharge line 113 with respect to the gas discharge port 105, and a flow meter 137 is attached. Further, a flow rate adjusting valve 116 is mounted on the superheated steam supply side of the heat transfer tube 106. In addition, the drying container 101 is provided with a first temperature sensor 121 that detects the temperature of the fluidized bed S and a second temperature sensor 122 that detects the temperature of the free board portion F.

  The control device 125 receives the temperature T1 of the fluidized bed S detected by the first temperature sensor 121 and the temperature T2 of the free board part F detected by the second temperature sensor 122. In addition, the control device 125 adjusts the opening degree of the flow rate adjustment valve 132 so that the superheated steam supplied from the fluidized gas supply ports 104 into the drying container 101 through the steam supply line 131 and the fluidized gas supply line 111. The supply amount can be adjusted. Further, the control device 125 adjusts the opening degree of the flow rate adjustment valve 134 so that the control device 125 is supplied into the drying container 101 from each fluidized gas supply port 104 through the non-condensable gas supply line 133 and the fluidized gas supply line 111. The amount of non-condensable gas supplied can be adjusted.

  And in a present Example, the dew point temperature in this drying container 101 is changed by adjusting the water vapor | steam density | concentration in the drying container 101 according to the fluctuation | variation of the temperature in the fluidized bed S. In this case, a water vapor concentration adjusting device is used as a dew point temperature changing device for changing the dew point temperature in the drying container 101. Specifically, a flow rate adjusting valve 134 provided in the non-condensable gas supply line 133 is applied. ing. That is, a predetermined amount of superheated steam is supplied through the fluidized gas supply line 111 while the flow rate adjustment valve 132 provided in the steam supply line 131 is set to a predetermined opening degree, while the non-condensable gas supply line 133 is provided. By closing the flow rate adjusting valve 134, the water vapor concentration in the drying container 101 is maintained at 100%.

  When the flow rate adjustment valve 134 is opened by a predetermined opening degree in this operation state, the noncondensable gas is supplied into the drying container 101, so that the water vapor concentration in the drying container 101 can be reduced. Since steam is generated by drying raw coal in the drying container 101, it is desirable to adjust the amount of non-condensable gas into the drying container 101 in consideration of the amount of generated steam. That is, the dew point temperature in the drying container 101 may be changed by adjusting the water vapor concentration discharged from the drying container 101 in accordance with the temperature fluctuation in the fluidized bed S.

  Further, here, the water vapor concentration is adjusted by supplying the non-condensable gas into the drying container 101 by adjusting the opening degree of the flow rate adjusting valve 134. It is preferable to reduce the amount of superheated steam by reducing the opening of the flow rate adjusting valve 132. That is, it is preferable that the amount of fluidized gas supplied into the drying vessel 101 be kept constant by making the increase amount of the non-condensable gas the same as the decrease amount of the superheated steam. Further, when the raw coal in the drying vessel 101 is insufficiently fluidized, when the supply amount of the non-condensable gas from the non-condensable gas supply line 133 is increased, the amount of superheated steam from the steam supply line 131 is increased. Without reducing the amount of heat, or the amount of decrease in superheated steam may be less than the amount of increase in non-condensable gas to increase the total amount of fluidized gas.

  And if the water vapor | steam density | concentration in the drying container 101 is increased / decreased, the dew point temperature in this drying container 101 can be raised / lowered. In this case, since the temperature of the fluidized bed S is determined by the dew point temperature of the water vapor that depends on the partial pressure of water vapor in the drying vessel 101, the water vapor concentration in the drying vessel 101 is determined based on the temperature of the fluidized bed S. By changing, it becomes possible to maintain the deviation between the temperature of the fluidized bed S and the dew point temperature in the drying vessel 101 at a predetermined value, and always give a certain degree of heating to the raw coal of the fluidized bed S. Is possible.

  Specifically, the control device 125 adjusts the water vapor concentration in the drying container 101 by adjusting the opening degree of the flow rate adjustment valves 132 and 134 based on the detection result of the first temperature detection sensor 121, and this drying container The dew point temperature in 101 is changed. That is, when the temperature of the fluidized bed S decreases, the control device 125 increases the opening degree of the flow rate adjustment valve 134 and supplies the noncondensable gas into the drying container 101 to decrease the water vapor concentration.

  Here, the operation of the fluidized bed drying apparatus 12 of Example 2 will be described.

  In the fluidized bed drying device 12, the raw coal is supplied from the raw coal inlet 102 to the drying container 101 and the fluidized gas is supplied from the fluidized gas supply port 104 through the dispersion plate 107. A fluidized bed S having a predetermined thickness is formed above the dispersion plate 107. The raw coal moves through the fluidized bed S to the dry coal discharge port 103 side by the fluidizing gas, and is heated and dried by receiving heat from the heat transfer tube 106 at this time. In this case, the raw coal is heated and dried by the heat from the heat transfer tube 106 while moving from the raw coal inlet 102 to the dry coal outlet 103. Specifically, the raw coal is in a preheated state immediately after being fed from the raw coal inlet 102, and the water hardly evaporates. When the raw coal enters the drying region beyond the preheating region, the water evaporation starts and gradually increases. Then, the amount of evaporation becomes maximum, and decreases as the dry coal discharge port 103 is approached.

  Then, the dry coal from which the raw coal has been dried is discharged to the outside through the dry coal discharge port 103, and the steam generated when the raw coal is heated and dried in the fluidized bed S rises together with the fluidized gas and is discharged into the gas. The gas is discharged from the outlet 105 to the outside.

  At this time, as shown in FIGS. 4 and 5, the control device 125 sets the flow rate adjustment valve 132 to a predetermined opening, thereby allowing a predetermined amount of superheated steam (from the steam supply line 131 to flow through the fluidizing gas supply line 111). When fluidizing gas) is supplied, a predetermined amount of steam is pushed out from the gas discharge line 113 and discharged. In such an operation state of the fluidized bed drying apparatus 12, the temperature T1 of the fluidized bed S in the drying vessel 101 is maintained at 110 ° C., and the pressure (total pressure) is maintained at 100 kPa. In this case, the water vapor concentration C in the drying container 101 and the temperature of the fluidized bed S are set such that a deviation Tc between the dew point temperature in the drying container 101 and the temperature T1 of the fluidized bed S in the drying container 101 is set. By determining the intersection C with T1, a sufficient amount of heat drying in the raw coal is ensured.

  If the supply amount of the raw coal increases or the water content of the raw coal increases in the operating state of the fluidized bed drying device 12, the temperature T1 of the fluidized bed S decreases. At this time, for example, when the control device 125 detects that the temperature T1 of the fluidized bed S has decreased from 110 ° C. to 105 ° C., the control device 125 increases the opening degree of the flow rate adjustment valve 134 and increases the opening degree of the flow rate adjustment valve 132. Make it smaller. Then, while the amount of non-condensable gas into the drying container 101 increases, the amount of superheated steam decreases, the water vapor concentration in the drying container 101 decreases, and the dew point temperature in the drying container 101 decreases. In this case, even if the temperature T1 of the fluidized bed S is decreased, the deviation Tc of the fluidized bed S in the drying container 101 from the dew point temperature in the drying container 101 similar to the deviation Tc in the operation state described above. By determining the intersection D between the water vapor concentration C in the drying container 101 (exit) and the temperature T1 of the fluidized bed S so that Td is set, a sufficient amount of heat and dryness in the raw coal is ensured.

  That is, the control device 125 sets the water vapor concentration C in the drying container 101 (exit) so that the deviation Tc = Td, and the flow rate control valve 132, so that the water vapor concentration C in the drying container 101 is set. The opening degree of 134 is adjusted. The relationship between the temperature T1, the dew point temperature, and the water vapor concentration C of the fluidized bed S is preferably mapped in advance according to the form of the fluidized bed drying device 12. Further, the amount of steam generated in the drying container 101 is calculated based on the measurement results of the flow meters 135, 136, and 137, and the water vapor concentration in the drying container 101, that is, the gas discharge line 113 is obtained. The feedback control may be performed based on the water vapor concentration.

  When the heating and drying of the raw coal in the fluidized bed S progresses and the temperature T1 of the fluidized bed S rises, the control device 125 increases the opening of the flow rate adjustment valve 132, while adjusting the flow rate. The opening degree of the valve 134 is decreased, and a predetermined deviation between the temperature T1 and the dew point temperature in the drying container 101 is ensured.

  As described above, in the fluidized bed drying apparatus according to the second embodiment, the water vapor supply line 131 is provided at the lower portion of the drying container 101 and the flow rate adjustment valve 132 is mounted, and the non-condensable gas supply line 133 is provided and the flow rate is adjusted. The valve 134 is mounted, and the control device 125 adjusts the opening degree of the flow rate adjusting valves 132 and 134 based on the temperature of the fluidized bed S detected by the first temperature sensor 121, so that the water vapor concentration C in the drying container 101 is adjusted. To change the dew point temperature.

  Therefore, when the temperature T1 of the fluidized bed S fluctuates, the control device 125 adjusts the opening degree of the flow rate adjusting valves 132 and 134, adjusts the water vapor concentration C in the drying container 101, and changes the dew point temperature. Then, the degree of drying of the raw coal in the drying container 101 becomes constant, and it becomes possible to always perform a stable raw coal drying process, and it is possible to improve the drying efficiency.

  In this case, the controller 125 changes the dew point temperature by adjusting the water vapor concentration C in the drying container 101 by adjusting the opening degree of the flow rate adjusting valves 132 and 134 based on the temperature T1 of the fluidized bed S. Yes. Specifically, the control device 125 decreases the water vapor concentration C in the drying container 101 by increasing the opening degree of the flow rate adjustment valve 134 when the temperature T1 of the fluidized bed S decreases.

  Therefore, since the temperature of the fluidized bed S is determined by the dew point temperature of the water vapor that depends on the partial pressure of water vapor in the drying vessel 101, the water vapor concentration in the drying vessel 101 is adjusted based on the temperature of the fluidized bed S. By doing so, it becomes possible to maintain the deviation between the temperature T1 of the fluidized bed S and the dew point temperature in the drying vessel 101 at a predetermined value, and a stable raw coal drying process can always be performed.

  In the fluidized bed drying apparatus of Example 2, when the temperature of the fluidized bed S decreases, the control device 125 increases the supply amount of the non-condensable gas by increasing the opening of the flow rate adjustment valve 134. Yes. Accordingly, the amount of fluidized gas in the drying container 101 is increased, fluidization of raw coal can be promoted, and drying efficiency can be improved.

  Moreover, in the fluidized bed drying apparatus of Example 2, when the temperature of the fluidized bed S decreases, the control device 125 decreases the opening amount of the flow rate adjustment valve 132 to reduce the supply amount of superheated steam. By increasing the opening degree of the regulating valve 134 and increasing the supply amount of the non-condensable gas, the fluidized gas amount is kept constant. Therefore, the amount of fluidized gas in the drying container 101 is maintained at a constant amount, the pressure acting on the drying container 101 is not excessive, and safety can be improved.

  FIG. 6 is a schematic side view of a fluidized bed drying apparatus according to Example 3 of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the function similar to the Example mentioned above, and detailed description is abbreviate | omitted.

  Example 3 is an example in which Example 1 and Example 2 are combined. As shown in FIG. 6, the drying container 101 is provided with a fluidizing gas supply line 111 with respect to the fluidizing gas supply port 104. The fluidized gas supply line 111 is connected to the water vapor supply line 131 and the flow rate adjustment valve 132 is attached, and the non-condensable gas supply line 133 is connected and the flow rate adjustment valve 134 is attached. In addition, the drying container 101 is provided with a gas discharge line 113 with respect to the gas discharge port 105 and is equipped with a flow rate adjustment valve 114 and a fan 115.

  And the control apparatus 125 adjusts the pressure in the drying container 101 by adjusting the opening degree of the flow volume adjustment valve 114 based on the detection result of the 1st temperature detection sensor 121, and the dew point temperature in this drying container 101 To change. That is, when the temperature of the fluidized bed S decreases, the control device 125 increases the opening degree of the flow rate adjustment valve 114 and decreases the pressure in the drying container 101. Further, the control device 125 adjusts the water vapor concentration in the drying container 101 by adjusting the opening degree of the flow rate adjusting valves 132 and 134 based on the detection result of the first temperature detection sensor 121, and the inside of the drying container 101 is adjusted. Change the dew point temperature. That is, when the temperature of the fluidized bed S decreases, the control device 125 increases the opening degree of the flow rate adjustment valve 134 to supply the non-condensable gas, while reducing the opening degree of the flow rate adjustment valve 132 and performs drying. The water vapor concentration in the container 101 is reduced.

  In this case, the control device 125 may change the dew point temperature by adjusting the pressure in the drying container 101 based on the temperature of the fluidized bed S, or adjust the water vapor concentration in the drying container 101 to adjust the dew point temperature. May be changed or performed simultaneously.

  In each of the above-described examples, low-grade coal was used as a wet raw material, but even high-grade coal can be applied, and is not limited to coal, but can be used as a renewable biological organic resource. For example, it is also possible to use thinned wood, waste wood, driftwood, grass, waste, sludge, tires, and recycled fuel (pellets and chips) made from these raw materials. .

DESCRIPTION OF SYMBOLS 11 Coal feeder 12 Fluidized bed dryer 13 Pulverized coal machine 14 Coal gasifier 15 Char recovery device 16 Gas refiner 17 Gas turbine equipment 18 Steam turbine equipment 19 Generator 20 Waste heat recovery boiler 101 Drying vessel 102 Raw coal input (Moist raw material input part)
103 Dry coal discharge port (dry matter discharge part)
104 Fluidization gas supply port (fluidization gas supply section)
105 Gas outlet (gas outlet)
106 Heat transfer tube (heating unit)
111 Fluidizing gas supply line 112 Flow rate adjusting valve 113 Gas exhaust line 114 Flow rate adjusting valve (dew point temperature changing device, pressure reducing device)
115 Fan 121 First temperature sensor (fluidized bed temperature detection sensor)
122 Second temperature sensor 123 Pressure sensor 125 Control device 131 Water vapor supply line 132 Flow rate adjusting valve (dew point temperature changing device, water vapor concentration adjusting device)
133 Non-condensable gas supply line 134 Flow rate adjusting valve (dew point temperature changing device, water vapor concentration adjusting device)

Claims (7)

A drying container having a hollow shape;
A wet raw material charging unit for charging the wet raw material to one end of the drying container;
A dried product discharger for discharging a dried product obtained by heating and drying the wet raw material from the other end of the drying container;
A fluidizing gas supply unit that forms a fluidized bed with a wet raw material by supplying a fluidizing gas to a lower portion of the drying container;
A gas discharge part for discharging fluidized gas and generated steam from above the wet raw material input part on one end side of the drying container;
A heating section for heating the wet raw material of the fluidized bed;
A dew point temperature changing device for changing the dew point temperature in the drying container;
A fluidized bed temperature detection sensor for detecting the temperature of the fluidized bed;
A control device for controlling the dew point temperature changing device based on the detection result of the fluidized bed temperature detection sensor;
A fluidized bed drying apparatus comprising:   The dew point temperature changing device is a pressure reducing device that changes a pressure in the drying container, and the control device controls the pressure reducing device based on a temperature of the fluidized bed. The fluidized bed drying apparatus as described.   The fluidized bed drying apparatus according to claim 2, wherein the control device controls the pressure reducing device to reduce the pressure in the drying container when the temperature of the fluidized bed is lowered.   The fluidized gas supply unit can supply water vapor and non-condensable gas as fluidized gas to the lower part of the drying container, and the dew point temperature changing device controls the fluidized gas supply unit to perform the drying. The fluidized bed drying apparatus according to claim 1, wherein the apparatus is a device for adjusting a water vapor concentration in a container, and the control device controls the water vapor concentration adjusting device based on a temperature of the fluidized bed.   The fluidized bed drying apparatus according to claim 4, wherein when the temperature of the fluidized bed is lowered, the control device controls the water vapor concentration adjusting device to lower the water vapor concentration in the drying container. .   The fluidized bed drying apparatus according to claim 5, wherein the control device increases the supply amount of the non-condensable gas when the temperature of the fluidized bed decreases.   The control device maintains the fluidized gas amount constant by decreasing the supply amount of water vapor while increasing the supply amount of non-condensable gas when the temperature of the fluidized bed decreases. The fluidized bed drying apparatus according to claim 5.

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