AU2015351701B2

AU2015351701B2 - Drying system

Info

Publication number: AU2015351701B2
Application number: AU2015351701A
Authority: AU
Inventors: Toru Ishii
Original assignee: IHI Corp
Current assignee: IHI Corp
Priority date: 2014-11-26
Filing date: 2015-10-15
Publication date: 2018-08-02
Anticipated expiration: 2035-10-15
Also published as: JP6520076B2; AU2015351701A1; JP2016099099A; WO2016084509A1

Abstract

The present invention is provided with: a plurality of solar heat collectors (2) that heat a heat transfer medium (X) with solar heat; and a drying furnace (5) that dries an object to be dried (Y) by exchanging heat between the object to be dried (Y) and the heat transfer medium (X) that has been heated by the solar collectors (2).

Description

DRYING SYSTEM

[0001]

The present disclosure relates to a drying system.

Priority is claimed on Japanese Patent Application No. 2014-238922, filed November 26, 2014, the content of which is incorporated herein by reference.

[0002]

Because solid fuels containing large quantities of moisture, such as brown coal, biomass and palm, have poor ignitability or combustibility due to the influence of the moisture contained therein when used without treatment, such solid fuels are conventionally dried in the sunlight or the like. However, with the sunlight, there is a need for a wide space in which to store the fuel, and it is difficult to manage the temperature of the fuel during drying. Therefore, in addition to heating using solar radiation, when the solid fuel comes into contact with air, it is oxidized and changes in quality. Additionally, heat generated by the oxidation is added to heat of the solar radiation and the temperature abnormally rises, which may lead to spontaneous ignition.

[0003]

Meanwhile, it is conceivable to artificially create hot air and dry the fuel using the hot air. However, generation of such hot air necessarily consumes a great amount of fuel, and much carbon dioxide is discharged. Thus, for example, it is conceivable to perform drying without consuming the fuel by applying the gasifying facility disclosed in Patent Document 1, and by heating the fuel using heat obtained by condensing sunlight.

[0004]

Japanese Unexamined Patent Application, First Publication No. 2001-123183 [0005]

However, because the fuel is directly irradiated with the condensed sunlight in the gasifying facility disclosed in Patent Document 1, the fuel is heated to the vicinity of 1000 °C. Although such a temperature is not a problem when the gasifying facility performs the gasification of the fuel, the temperature is excessive in drying the fuel.

[0006]

Also, in the gasifying facility disclosed in Patent Document 1, in order to heat the fuel up to 1000 °C, sunlight condensed by a plurality of heliostats is condensed on the reflection mirror supported on the top by a large tower, and is further guided to the gasification furnace. For this reason, there is a need for a large number of heliostats, a large tower or the like, and the facility increases in size. Moreover, because the sunlight condensed from a large number of heliostats installed in a wide range is condensed within a limited range, there are problems of a need for a complicated control and an increase in facility cost. In the drying system that dries the fuel, because it is not necessary to raise the temperature of the fuel up to the vicinity of 1000 °C, it is not necessary to install a large facility such as that shown in Patent Document 1, and it is desirable to miniaturize the facility.

[0007]

Preferred embodiments of the invention have been made in view of the above-described problems, and suppress the consumption of fuel used for drying by utilizing solar heat and to suppress an increase in size of the facility in a drying system that dries a drying target, and to enable adjustment of the temperature of the drying target to a temperature suitable for drying.

[0008]

According to the present invention there is provided a drying system comprising: a plurality of solar collectors that are provided to heat a heat transfer medium with solar heat; a drying furnace that dries a drying target by exchanging heat between the heat transfer medium heated by the solar collector and the drying target; and a steam drum that is disposed between the solar collectors and the drying furnace to temporarily store the heat transfer medium which is vaporized by being heated by the solar collectors, wherein the steam drum has an upper portion connected to the drying furnace, and a bottom portion connected to a heat transfer medium-circulating unit.

[0009] [This paragraph has been intentionally left blank.] [0010]

According to the present disclosure, a configuration that includes a plurality of solar collectors configured to heat the heat transfer medium is adopted.

Therefore, by installing a number the solar collectors that is sufficient for collecting the energy required for drying the drying target, the drying target can be dried, and it is possible to perform the drying using the solar heat, without installing a huge tower or a reflection mirror. Further, compared to the quantity of heat required for gasifying the solid fuel such as coal, since the quantity of heat required for drying is small, according to the present disclosure, it is not necessary to install a large number of heliostats as in the aforementioned gasification facility, and there is no need for a complex control system that condenses light to a limited range from the heliostat installed over a wide range. Therefore, according to the present embodiment, it is possible to suppress an increase in size of the facility or complexity of the control system.

Furthermore, the present embodiment adopts a configuration which heats the heat transfer medium with the solar heat and heats the drying target with the heat transfer medium, rather than directly heating the drying target with the solar heat collected by the solar collector. Therefore, by adjusting the physical properties (e.g., saturated steam temperature) of the heat transfer medium or the flow velocity of the heat transfer medium at the time of heat exchange, it is possible to easily adjust the temperature of the drying target. Therefore, according to the present embodiment, it is possible to adjust the temperature of the drying target to a temperature that is suitable for drying.

[0011]

Embodiments of the present invention will now be described, by way of non-limiting example only, with reference to the accompany drawings.

Fig. 1 is a flow diagram showing a schematic configuration of a drying system in a first embodiment of the present disclosure.

Fig. 2 A is a schematic diagram showing a schematic configuration of a solar collector with which the drying system of the first embodiment of the present disclosure is equipped.

Fig. 2B is a schematic diagram showing a schematic configuration of a solar collector with which the drying system of the first embodiment of the present disclosure is equipped.

Fig. 3 is an explanatory diagram of a case of operating an auxiliary boiler only around (before and after) sunrise in the drying system of the first embodiment of the present disclosure.

Fig. 4 is an explanatory diagram of a case of operating the auxiliary boiler only around (before and after) sunset in the drying system of the first embodiment of the present disclosure.

Fig. 5 is an explanatory diagram of a case of operating the auxiliary boiler around (before and after) sunrise and around (before and after) sunset in the drying system of the first embodiment of the present disclosure.

Fig. 6 is a flow diagram showing a schematic configuration of a drying system of a second embodiment of the present disclosure.

Fig. 7 is an explanatory diagram of a case of operating the auxiliary boiler only around (before and after) sunrise in the drying system of the second embodiment of the present disclosure.

Fig. 8 is an explanatory diagram of a case of operating the auxiliary boiler only around (before and after) sunset in the drying system of the second embodiment of the present disclosure.

Fig. 9 is an explanatory diagram of a case of operating the auxiliary boiler around (before and after) sunrise and around (before and after) sunset in the drying system of the second embodiment of the present disclosure.

Fig. 10 is a flow diagram showing a schematic configuration of a drying system according to a third embodiment of the present disclosure.

[0012]

Hereinafter, an embodiment of a drying system according to the present disclosure will be described with reference to the accompanying drawings. In the following drawings, in order to set each member to a recognizable size, the scale of each member is appropriately changed.

[0013] (First embodiment)

Fig. 1 is a flow diagram showing a schematic configuration of a drying system 1 of the present embodiment. As shown in Fig. 1, the drying system 1 of the present embodiment is equipped with a plurality of solar collectors 2, a steam drum 3, an auxiliary boiler 4, a drying furnace 5, a fluidizing gas supply device 6 (a fluidizing gas supply means, an inert gas supply unit), a heat transfer medium-circulating unit 7, and a control device 8.

[0014]

Figs. 2A and 2B are schematic diagrams showing a schematic configuration of a solar collector 2, Fig. 2A is a perspective view thereof, and Fig. 2B is a cross-sectional view thereof. As shown in Figs. 2A and 2B, the solar collector 2 is equipped with a first reflector 2a, a second reflector 2b, a heat transfer tube 2c, and a driving device 2d.

[0015]

The first reflector 2a is a substantially semi-cylindrical reflector having an inner surface serving as a reflecting surface directed toward the sky, and reflects the sunlight to condense the light on the second reflector 2b. The second reflector 2b is a substantially semi-cylindrical reflector that is supported by a supporting portion 2e fixed to the first reflector 2a, and has an inner surface serving as a reflecting surface directed toward the first reflector 2a. The heat transfer tube 2c is a straight pipe that is disposed in the light-condensing position of the second reflector 2b, and the heat transfer medium X flows therein. The heat transfer tube 2c is fixed by a support mechanism provided externally to pass through a through-hole provided in the supporting portion 2e. The driving device 2d movably supports the first reflector 2a and the second reflector 2b around the heat transfer tube 2c, and for example, moves the first reflector 2a and the second reflector 2b under the control of the control device 8 such that the reflecting surface of the first reflector 2a faces the sun. The second reflector 2b obtains the effects of improving the light collection efficiency, and improving the heat collection by heating a surface serving as a back side when viewed from the first reflector 2a, among the outer surfaces of the heat transfer tube 2c. The second reflector 2b can also be omitted.

[0016]

In the solar collector 2, the sunlight reflected by the first reflector 2a and the second reflector 2b is condensed in the heat transfer tube 2c, and the heat transfer medium X inside the heat transfer tube 2c is heated by solar heat obtained by the concentration. In the present embodiment, water is used as the heat transfer medium X, and the heated heat transfer medium X in the solar collector 2 is heated to the extent that it is partially or entirely vaporized. Further, as the heat transfer medium X, without being limited to water, it is also possible to use, for example, organic solvents, inorganic salts or metals. For example, when the organic solvents are used, it is possible to use alcohols or oils and fats that have relatively high boiling points and are liquid at room temperature. Further, when the inorganic salts and metals are used, a medium that becomes liquid at a relatively low temperature is selected to ensure fluidity.

[0017]

As shown in Fig. 1, a plurality of solar collectors 2 which heat the heat transfer medium X with the solar heat are provided, and each of the solar collectors 2 is connected to a steam drum 3 via a collector tube 2f. The number of the solar collectors 2 installed is determined based on the quantity of steam required for drying a drying target Y in the drying furnace 5. For example, the number of the solar collectors 2 installed is determined such that the quantity of steam generated by the solar collectors 2 during operation exceeds the quantity of steam required by the drying furnace 5 during the day in fair weather.

[0018]

The steam drum 3 is a container that temporarily stores the heat transfer medium X that is partially or entirely vaporized by being heated by the solar collectors 2, and is disposed between the solar collectors 2 and the drying furnace 5. Further, the steam drum 3 has an upper portion connected to the drying furnace 5, and a bottom portion connected to the heat transfer medium-circulating unit 7. When the heat transfer medium X is supplied to the steam drum 3, the heat transfer medium X in the steam state is accumulated in the upper portion of the steam drum 3 and is sent toward the drying furnace 5. Further, the heat transfer medium X of the liquid state is accumulated in the bottom portion of the steam drum 3, and is sent to the heat transfer medium-circulating unit 7.

[0019]

The auxiliary boiler 4, for example, is a general-purpose boiler that is easily started and stopped, and is connected to the steam drum 3. The auxiliary boiler 4 supplementarily heats the heat transfer medium X to generate steam, and supplies the steam to the steam drum 3 when the quantity of production of steam in the solar collectors 2 decreases near the time of sunrise, sunset or the like. In the present embodiment, the auxiliary boiler 4 is connected to the control device 8 to generate steam under the control of the control device 8.

[0020]

The drying furnace 5 is equipped with a chamber 5a, dividing walls 5b that divide the inside of the chamber 5a into a plurality of regions in a horizontal direction, and a heat transfer tube 5c that is inserted into the chamber 5a. The chamber 5a is a container in which the drying target Y is stored. In the chamber 5a, some of the drying target Y stored in advance by supplying the drying target Y from the outside is extruded and discharged. The plurality of dividing walls 5b are erected on the bottom portion of the chamber 5a, and are provided so that the wall surfaces thereof face each other. As the dividing walls 5b, a first dividing wall 5b 1 provided with an opening at a lower portion, and second dividing walls 5b2 with no openings and having lower heights than the first dividing wall 5b 1 are provided, and these dividing walls are alternately arranged in the chamber 5a. Since the inside of the chamber 5a is divided by the plurality of dividing walls 5b, as indicated by an arrow in Fig. 1, the drying target Y meanders up and down in the chamber 5a. The heat transfer tube 5 c has an inlet end connected to the steam drum 3, and an exit end connected to the heat transfer medium-circulating unit 7. The heat transfer medium X which exchanges heat with the drying target Y inside the chamber 5a flows through the heat transfer tube 5c.

In the drying furnace 5, the drying target Y is dried by exchanging heat between the drying target Y flowing due to the fluidizing gas Z supplied from the fluidizing gas supply device 6 and the heat transfer medium X flowing through the heat transfer tube 5c.

[0021]

The drying target Y to be dried by such a drying furnace 5 is a solid fuel which is used as a fuel of a pulverized coal boiler or the like (not shown), and contains a large quantity of moisture (e.g., a moisture content is 20% or more). As such a drying target Y, for example, there is powdered brown coal or biomass. In order to enhance the fluidity in the chamber 5a, the fluidized medium such as sand may be stored inside the chamber 5a, in addition to the drying target Y. The fluidized medium is separated from the drying target Y after being discharged from the chamber 5 a, and is returned into the chamber 5 a again.

[0022]

The fluidizing gas supply device 6 is equipped with a circulation pipe 6a, an inert gas generator 6b, a blower 6c, a heat exchanger 6d and a cooler 6e. The circulation pipe 6a is a pipe that has a first end side branched into a large number of sections and connected to the bottom portion of the chamber 5a, and a second end side connected to the ceiling portion of the chamber 5a, and serves as a flow passage of the fluidizing gas Z. Further, the first end side of the circulation pipe 6a is connected to the bottom portion of the chamber 5a so that each of the branched ends is connected to each region of the chamber 5a divided by the dividing wall 5b. The inert gas generator 6b, for example, generates nitrogen gas (an inert gas) used as a fluidizing gas from the atmosphere, and is connected to the circulation pipe 6a. The blower 6c is provided in the intermediate portion of the circulation pipe 6a to pressure-feed the fluidizing gas Z. The blower 6c pressure-feeds the fluidizing gas Z toward the first end side (the side connected with the bottom portion of the chamber 5a) of the circulation pipe 6a so that the fluidizing gas Z is supplied upward from the bottom portion of the chamber 5 a.

Thus, the fluidizing gas Z is supplied into the chamber 5a from the first end side (the side connected to the bottom portion of the chamber 5a) of the circulation pipe 6a, and the fluidizing gas Z of the inside of the chamber 5a is recovered from the second end side (the side connected to the ceiling portion of the chamber 5a) of the circulation pipe 6a.

[0023]

The heat exchanger 6d is an intermediate portion of the circulation pipe 6a, and is disposed downstream from the blower 6c. The heat exchanger 6d exchanges heat between the heat transfer medium X flowing through a return flow pipe 7a to be described later provided in the heat transfer medium-circulating unit 7 and the fluidizing gas Z flowing through the circulation pipe 6a. In the heat exchanger 6d, by the heat-exchange between the heat transfer medium X and the fluidizing gas Z, the fluidizing gas Z is heated prior to being supplied to the drying furnace 5, and thus a decrease in the internal temperature of the chamber 5 a can be prevented by the fluidizing gas Z.

[0024]

The cooler 6e is an intermediate portion of the circulation pipe 6a and is disposed upstream from the blower 6c. The cooler 6e cools the fluidizing gas Z to condense and separate the moisture that is contained in the fluidizing gas Z heated by passing through the inside of the chamber 5a. Thus, the dried fluidizing gas Z is supplied to the blower 6c or the like, which makes it possible to prevent condensation from occurring in the blower 6c or the like.

[0025]

Because the fluidizing gas Z is supplied upward from the bottom portion of the chamber 5a by such a fluidizing gas supply device 6, the drying target Y stored in the chamber 5 a is caused to flow. Thus, the heat-exchange between the drying target Y and the heat transfer medium X is promoted, and it is possible to dry the drying target Y in a short amount of time.

[0026]

In the heat transfer medium-circulating unit 7, a return flow pipe 7a, a condenser 7b, a feed water pump 7c, a feed water preheater 7d, and a steam drum connection pipe 7e are provided. The return flow pipe 7a is a pipe that connects the drying furnace 5 and the solar collectors 2, and returns the heat transfer medium X discharged from the drying furnace 5 to the solar collectors 2 again. As shown in Fig. 1, the return flow pipe 7a passes through the heat exchanger 6d to exchange heat between the heat transfer medium X flowing through the return flow pipe 7a and the fluidizing gas Z flowing through the circulation pipe 6a, and the quantity of heat of the heat transfer medium X is transferred to the fluidizing gas Z.

[0027]

The condenser 7b is an intermediate portion of the return flow pipe 7a, is disposed downstream from the heat exchanger 6d, and cools and liquefies the heat transfer medium X in the steam state, for example, by heat exchange with the atmosphere. The feed water pump 7c is disposed further downstream from the condenser 7b, and feeds the heat transfer medium X liquefied by the condenser 7b toward the solar collectors 2. The feed water preheater 7d is disposed further downstream from the feed water pump 7c, and preheats the heat transfer medium X supplied to the solar collectors 2 by exchanging heat between the heat transfer medium X discharged from the feed water pump 7c and the heat transfer medium X upstream from the condenser 7b. A steam drum connection pipe 7e is a pipe that connects the bottom portion of the steam drum 3 and the return flow pipe 7a, and guides the heat transfer medium X in the liquid state accumulated in the bottom portion of the steam drum 3 to the upstream side of the condenser 7b, without passing through the drying furnace 5. Further, a port (not shown) which additionally supplies the heat transfer medium X to the return flow pipe 7a is provided upstream from the feed water pump 7c, and for example, the heat transfer medium X is additionally supplied to the return flow pipe 7a from the port, for example, depending on the need such as supplement of the decrement of the heat transfer medium X.

[0028]

The control device 8 performs overall control of the drying system 1 of the present embodiment, and for example, controls the auxiliary boiler 4, the inert gas generator 6b, the blower 6c and the feed water pump 7c. In the drying system 1 of the present embodiment, the operating period of the auxiliary boiler 4 is defined under the control of the control device 8. For example, under the control of the control device 8, the auxiliary boiler 4 is operated only around (before and after) sunrise or is operated only around (before and after) sunset, or the auxiliary boiler 4 is operated around (before and after) sunrise and around (before and after) sunset. Further, although it is omitted in Fig. 1, in the drying system 1 of the present embodiment, a valve is provided in an appropriate position. By adjusting the degree of opening of the valve by the control or the like of the control device 8, the flow rate of the heat transfer medium X or the fluidizing gas Z is adjusted.

[0029]

Next, the operation of the drying system 1 having the configuration of the present embodiment will be described. Further, in the following description of the operation, the drying target Y is continuously supplied to the chamber 5 a of the drying furnace 5 at a constant quantity.

[0030]

When the sunlight is condensed by the first reflector 2a and the second reflector 2b of the solar collectors 2, and the heat transfer medium X flowing through the heat transfer tube 5 c is heated by solar heat, some of the heat transfer medium X is vaporized to generate the heat transfer medium X in the gas-liquid mixed state. The heat transfer medium X generated by the plurality of solar collectors 2 is collected by the collector tube 2f and is supplied to the steam drum 3. The heat transfer medium X is separated into gas and liquid in the steam drum 3, and the heat transfer medium X in the steam state is supplied to the heat transfer tube 5c of the drying furnace 5. Meanwhile, the heat transfer medium X in the liquid state is supplied to the heat transfer medium-circulating unit 7 from the steam drum connection pipe 7e and is supplied to the solar collectors 2 again.

[0031]

Further, in the fluidizing gas supply device 6, the fluidizing gas Z (inert gas) is supplied to the circulation pipe 6a from the inert gas generator 6b, and the fluidizing gas Z of the circulation pipe 6a is pressure-fed toward the drying furnace 5 by driving the blower 6c. After the fluidizing gas Z supplied to the drying furnace 5 is warmed in the heat exchanger 6d in advance, the fluidizing gas Z is supplied into the chamber 5a from the bottom portion of the chamber 5a. By supplying the fluidizing gas Z from the bottom of the chamber 5a, the drying target Y in the chamber 5a is fluidized. Further, the fluidizing gas Z in the chamber 5a is recovered to the circulation pipe 6a from the top portion of the chamber 5a, and after the moisture in the cooler 6e is removed, the fluidizing gas Z is pressure-fed again by the blower 6c.

[0032]

When the heat transfer medium X supplied to the heat transfer tube 5c inserted into the chamber 5a is supplied as described above, by the heat-exchange between the heat transfer medium X of the inside of the heat transfer tube 5 c and the drying target Y of the outside of the heat transfer tube 5c, the drying target Y is heated. As a result, moisture contained in the drying target Y is evaporated, and the drying target Y is dried. The drying target Y is discharged to the outside of the chamber 5a by being pushed by the new drying target Y that is continuously supplied to the chamber 5a. The moisture evaporated from the drying target Y and the fluidizing gas Z is recovered to the circulation pipe 6a.

[0033]

The heat transfer medium X discharged to the outside of the chamber 5a through the heat transfer tube 5c flows into the return flow pipe 7a of the heat transfer medium-circulating unit 7. The heat transfer medium X flowing into the return flow pipe 7a is returned to the liquid state by passing through the heat exchanger 6d and the feed water preheater 7d, and by being cooled in the condenser 7b. The heat transfer medium X returned to the liquid state is pressure-fed toward the solar collectors 2 by the feed water pump 7c. The heat transfer medium X pressure-fed by the feed water pump 7c is supplied to the solar collectors 2 again, after being preheated in the feed water preheater 7d.

[0034]

Further, the auxiliary boiler 4 is operated only around (before and after) sunrise, only around (before and after) sunset or around (before and after) sunrise and around (before and after) sunset. When the auxiliary boiler 4 is operated, steam (the heat transfer medium X) is generated and is supplied to the steam drum 3. The steam supplied to the steam drum 3 from the auxiliary boiler 4 is used after being mixed with steam (the heat transfer medium X) supplied to the steam drum 3 from the solar collectors 2.

[0035]

Next, an example of an operation pattern in which the auxiliary boiler 4 of the drying system 1 of the present embodiment is used will be described with reference to Figs. 3 to 5.

[0036]

Fig. 3 is an explanatory diagram of a case of driving the auxiliary boiler 4 in the drying system 1 of the present embodiment only around (before and after) sunrise. Further, Fig. 4 is an explanatory diagram of a case of driving the auxiliary boiler 4 in the drying system 1 of the present embodiment only around (before and after) sunset. Fig. 5 is an explanatory diagram of a case of driving the auxiliary boiler 4 in the drying system 1 of the present embodiment around (before and after) sunrise and around (before and after) sunset. Although Figs. 3 to 5 show the graphs showing the relationship between the time and the temperature of the heat transfer medium X in the steam drum 3 in the upper portion, the graphs also show superimposed graphs showing the relationship between the time and the energy obtained from the sun as a reference.

[0037]

As shown in Fig. 3, when the auxiliary boiler 4 is driven around (before and after) sunrise, the operation of the auxiliary boiler 4 is started before sunrise. Because it is not possible to heat the heat transfer medium X with the solar collectors 2 before sunrise, even when the steam is supplementarily supplied to the steam drum 3 from the auxiliary boiler 4, the temperature of the heat transfer medium X supplied to the steam drum 3 from the solar collector 2 side via the collector tube 2f is low, and the temperature of the heat transfer medium X in the entire steam drum 3 does not reach the boiling point.

[0038]

Further, the drying system 1 of the present embodiment performs the preheating operation until the temperature of the heat transfer medium X in the steam drum 3 reaches the boiling point. The preheating operation is an operation that is performed in a state in which the drying target Y is not supplied to the drying furnace 5, and is an operation of grad ually raising the temperature of the heat transfer medium X toward the boiling point. Further, the preheating operation is performed in one of a state in which the drying target Y is not stored in the drying furnace 5 and a state in which the drying target Y that was not completely dried on the previous day is stored in the drying furnace 5. In such a preheating operation, the temperature of the heat transfer medium X gradually rises due to the operation of the auxiliary boiler 4 (including heating with the solar collectors 2 after sunrise). Further, in the preheating operation, the fluidizing gas Z is supplied to the drying furnace 5 by the fluidizing gas supply device 6. Thus, the temperature of the fluidizing gas Z also rises with an increase in temperature of the heat transfer medium X, and thus it is possible to prevent the drying target Y from being cooled by the fluidizing gas Z after the drying operation starts.

[0039]

At sunrise, although the energy obtained from the sun is lower than around (before and after) noon, the heat transfer medium X is heated by the solar collectors 2, and the temperature of the heat transfer medium X in the steam drum 3 rapidly increases up to the boiling point. When the temperature of the heat transfer medium X in the steam drum 3 reaches the boiling point, the auxiliary boiler 4 stops, the drying target Y is charged into the drying furnace 5, and a drying operation of drying the drying target Y is performed. Further, when sunset approaches and the energy obtained from the sun decreases, because the temperature of the heat transfer medium X is lower than the boiling point, the supply of the drying target Y to the drying furnace is stopped at this time, and the drying operation is stopped.

[0040]

Thereafter, the cooling operation is performed until sunset. In the cooling operation, for example, by directing the solar collectors 2 in a direction different from the sun, a state in which the heat transfer medium X is not heated by the solar collectors 2 is set, and the fluidization gas Z is continuously supplied to the drying furnace 5 by the fluidizing gas supply device 6. Thus, the drying target Y is stirred without being heated, and the internal temperature of the drying furnace 5 is rapidly lowered. After the internal temperature of the drying furnace 5 is cooled to a temperature at which there is no risk of spontaneous ignition or the like, the cooling operation is completed, and the drying system 1 of the present embodiment is stopped until the operation restarts on the next day.

[0041]

Further, when the auxiliary boiler 4 is not driven around (before and after) sunrise, since the heat transfer medium X is heated by the solar collectors 2 after sunrise, as indicated by a chain line in Fig. 3, the time at which the heat transfer medium X reaches the boiling point in the steam drum 3 is delayed. Thus, by driving the auxiliary boiler 4 around (before and after) sunrise, it is possible to quicken the start timing of the drying operable period, and it is possible to dry the drying target Y for a longer period of time.

[0042]

Further, as shown in Fig. 4, when the auxiliary boiler 4 is driven around (before and after) sunset, the operation of the auxiliary boiler 4 is started before sunset. When sunset approaches, since the energy obtained from the sun decreases, energy which heats the heat transfer medium X in the solar collectors 2 decreases, and it is not possible to maintain the temperature of the heat transfer medium X at the boiling point with only the solar collectors 2. However, the temperature of the heat transfer medium X gradually decreases, rather than immediately decreasing to room temperature even when sunset approaches or passes (see Fig. 3). Here, as shown in Fig. 4, when the auxiliary boiler 4 is operated around (before and after) sunset, by supplying the new steam to the steam drum 3 from the auxiliary boiler 4, it is possible to suppress a decrease in the temperature of the heat transfer medium X around (before and after) sunset. Thus, even when sunset passes, the temperature of the heat transfer medium X can be maintained at the boiling point for a while, and it is possible to continue the drying of the drying target Y. In this way, by operating the auxiliary boiler 4 around (before and after) sunset, it is possible to extend the drying operable period as shown in Fig. 4 up to the time after sunset, and the drying target Y can be dried for a longer period of time.

[0043]

Further, as described above, although it is not possible to maintain the temperature of the heat transfer medium X at the boiling point with only the solar collectors 2 around (before and after) sunset, the heat transfer medium X is warmed by the operation in the daytime. Thus, the input energy that maintains the temperature of the heat transfer medium X at the boiling point using the auxiliary boiler 4 becomes smaller than when the auxiliary boiler 4 is driven around (before and after) sunrise.

Therefore, when the auxiliary boiler 4 is driven around (before and after) sunset, it is possible to extend the drying operable period with less fuel than when the auxiliary boiler 4 is operated around (before and after) sunrise.

[0044]

Further, as shown in Fig. 5, when the auxiliary boiler 4 is driven around (before and after) sunset and around (before and after) sunrise, it is possible to quicken the start timing of the drying operable period, and it is possible to extend the drying operable period beyond sunset. In such a case, although a larger quantity of fuel is required than when the auxiliary boiler 4 is driven only around (before and after) sunrise and when the auxiliary boiler 4 is driven only around (before and after) sunset, it is possible to ensure the longest drying operable period. For this reason, for example, this is an operation pattern that is useful when the operating time of the plant in which the drying system 1 of the present embodiment is installed increases, and the drying system 1 is attempted to be operated for a long time in accordance with the operation time.

[0045]

According to the drying system 1 of the present embodiment as described above, the configuration which includes a plurality of solar collectors 2 for heating the heat transfer medium X is adopted. Therefore, by installing the solar collectors of the number that is sufficient for collecting the energy required for drying the drying target Y, the drying target Y can be dried, and it is possible to perform the drying using the solar heat, without installing a huge tower or a reflection mirror. Further, compared to the quantity of heat required for gasifying the solid fuel such as coal, since the quantity of heat required for drying is small, in the drying system 1 of the present embodiment, it is not necessary to install a large number of heliostats as in the aforementioned gasification facility, and there is no need for a complex control system that condenses light to a limited range from the heliostats installed over a wide range. Therefore, according to the drying system 1 of the present embodiment, it is possible to limit an increase in the size of the facility or the complexity of the control system.

[0046]

Furthermore, the drying system 1 of the present embodiment adopts a configuration which heats the heat transfer medium X with the solar heat and heats the drying target Y with the heat transfer medium X, rather than directly heating the drying target Y with the solar heat collected by the solar collectors 2. Therefore, by adjusting the physical properties (e.g., saturated steam temperature) of the heat transfer medium X or the flow velocity of the heat transfer medium X at the time of heat exchange, it is possible to easily adjust the temperature of the drying target Y. For example, in the drying system 1 of the present embodiment, since water is used as the heat transfer medium X, it is possible to prevent the temperature of the drying target Y from becoming equal to or higher than the saturation temperature of water. Further, a pipe or the like through which the heat transfer medium X flows is a closed space, and due to vaporization of the heat transfer medium X, the internal pressure of the space rises. Therefore, in the drying system 1 of the present embodiment, the saturation temperature of the heat transfer medium X, for example, becomes approximately 160 °C to 170 °C.

[0047]

Therefore, according to the drying system 1 of the present embodiment described above, it is possible to suppress the consumption of fuel used for drying by utilizing the solar heat. Further, it is possible to limit an increase in the size of the facility. Furthermore, it is possible to adjust the temperature of the drying target Y to a temperature that is suitable for drying.

[0048]

Further, the drying system 1 of the present embodiment is equipped with a steam drum 3 that is disposed between the solar collectors 2 and the drying furnace 5 to temporarily store the heat transfer medium X that is vaporized by being heated by the solar collectors 2. Thus, for example, even when there is a variation in heating performance of each solar collector 2 due to the arrangement and the individual differences and there is a difference in the production ability of steam, since all of the steam is collected once in the steam drum 3 and is supplied to the drying furnace 5 from the steam drum 3, it is always possible to stably supply the heat transfer medium X to the drying furnace 5. Further, since a certain quantity of steam is accumulated inside the steam drum 3, for example, even if the sun is temporarily hidden by clouds and steam cannot be sufficiently produced in the solar collectors 2, it is possible to continuously supply the steam to the drying furnace 5.

[0049]

Further, in the drying system 1 of the present embodiment, since the fluidizing gas Z is supplied into the chamber 5a from the fluidizing gas supply device 6, the drying target Y flows inside the chamber 5 a. Therefore, the heat-exchange between the drying target Y and the heat transfer medium X is promoted, and it is possible to dry the drying target Y in a shorter amount of time. Also, the fluidizing gas supply device 6 supplies the inert gas as the fluidizing gas Z to the drying furnace 5. Therefore, oxygen does not enter the chamber 5a of the drying furnace 5, and thus it possible to prevent the drying target Y from having any chance of being combusted in the drying furnace 5.

[0050]

Further, the drying system 1 of the present embodiment is equipped with an auxiliary boiler 4 that heats the heat transfer medium X separately from the solar collectors 2. Therefore, when the steam required for the drying furnace 5 cannot be generated in the solar collectors 2, by generating the steam using the auxiliary boiler 4, the drying target Y can be dried. For example, by operating the auxiliary boiler 4 around (before and after) sunset and around (before and after) sunrise, it is possible to extend the drying operable period (a period of time at which the drying target Y can be dried) as described above.

[0051]

Further, in the drying system 1 of the present embodiment, the control device 8 operates the auxiliary boiler 4 in accordance with at least one of sunrise and sunset. Therefore, as explained above with reference to Figs. 4 to 6, it is possible to ensure the longer drying operable period than when the auxiliary boiler 4 is not used.

[0052] (Second embodiment)

Next, a second embodiment of the present disclosure will be described with reference to Figs. 6 to 9. In the description of the present embodiment, the description of the parts similar to those of the first embodiment will be omitted or simplified.

[0053]

Fig. 6 is a flow diagram showing a schematic configuration of a drying system 1A of the present embodiment. As shown in Fig. 6, the drying system 1A of the present embodiment has a configuration that includes a solar superheater 10 (superheater), and a fluidizing steam supply unit 11 (a fluidizing gas supply means, a superheated steam supplying unit), in addition to the drying system 1 of the first embodiment.

[0054]

The solar superheater 10 is disposed between the steam drum 3 and the drying furnace 5. The solar superheater 10 has a configuration similar to that of the solar collectors 2, and raises the temperature of the heat transfer medium X to be supplied to the heat transfer tube 5c of the drying furnace 5 from the steam drum 3 to the saturation temperature or higher (e.g., about 200 °C) with the solar heat. Further, although the drying system lAof the present embodiment adopts a configuration in which only one solar superheater 10 is provided, it is also possible to further adopt a configuration that includes a plurality of solar superheaters 10.

[0055]

The fluidizing steam supply unit 11 is equipped with a superheated steam supply pipe 11a and a switching valve lib. The superheated steam supply pipe 11 a is a pipe that connects the solar superheater 10 and the bottom portion of the chamber 5a, and supplies the heat transfer medium X superheated by the solar superheater 10 as the fluidizing gas into the chamber 5a. The switching valve lib is disposed in the intermediate portion of the superheated steam supply pipe 1 la to open and close the flow passage formed by the superheated steam supply pipe 11a. The switching valve 1 lb is, for example, controlled by the control device 8.

[0056]

In the drying system lAof the present embodiment having such a configuration, after the heat transfer medium X of steam discharged from the steam drum 3 is superheated to a temperature equal to or higher than the saturation temperature by the solar superheater 10, the heat transfer medium X is supplied to the heat transfer pipe 5c of the drying furnace 5. Therefore, the heat transfer medium X of temperature higher than the drying system 1 of the first embodiment is supplied to the heat transfer tube 5 c of the drying furnace 5. Therefore, it is possible to further raise the drying temperature in the drying furnace 5, and it is possible to dry the drying target Y in a short amount of time.

[0057]

Further, the control device 8 in the drying system lAof the present embodiment opens the switching valve lib as needed during the period of time in which the heat transfer medium X is superheated by the solar superheater 10. When the switching valve 11b is opened in this way, the heat transfer medium X is supplied as a fluidizing gas into the chamber 5a through the superheated steam supply pipe 11a. Further, for example, if the heat transfer medium X is directly brought into contact with the drying target Y when the temperature in the chamber 5a is low such as at the beginning of the operation of the drying system 1A or the like, the heat transfer medium X is condensed, and the surface of the drying target Y is wetted to inhibit the flow of the drying target Y. Therefore, when the internal temperature of the chamber 5a is low, similarly to the drying system 1 of the first embodiment, the fluidizing gas Z containing the inert gas is supplied to the chamber 5a by the fluidizing gas supply device 6.

[0058]

Next, an example of an operation pattern in the drying system 1A of the present embodiment will be described with reference to Figs. 7 to 9.

[0059]

Fig. 7 is an explanatory diagram of a case of operating the auxiliary boiler 4 only around (before and after) sunrise in the drying system 1A of the present embodiment. Fig. 8 is an explanatory diagram of a case of operating the auxiliary boiler 4 only around (before and after) sunset in the drying system lAof the present embodiment. Fig. 9 is an explanatory diagram of a case of operating the auxiliary boiler 4 around (before and after) sunrise and around (before and after) sunset in the drying system 1A of the present embodiment.

[0060]

As shown in Fig. 7, when the auxiliary boiler 4 is driven around (before and after) sunrise, the operation of the auxiliary boiler 4 is started before sunrise. At the time of start of the operation, the preheating operation is performed in the same manner as in the drying system 1 of the first embodiment. However, at this time, since the temperature of the heat transfer medium X does not reach the boiling point, and the superheated heat transfer medium X (superheated steam) is generated in the solar superheater 10, the fluidization gas Z containing the inert gas is supplied to the chamber 5 a by the fluidizing gas supply device 6 to allow the drying target Y remaining in the chamber 5 a from the operation of the previous day to flow.

[0061]

When sunrise passes and the temperature of the heat transfer medium X reaches the boiling point, a new drying target Y is supplied to the chamber 5a and the drying operation is started. Further, when the heat transfer medium X superheated by the solar superheater 10 is generated, the supply of the inert gas to the chamber 5a using the fluidizing gas supply device 6 is stopped, and the heat transfer medium X superheated by the solar superheater 10 is supplied as the fluidizing gas to the chamber 5a. Since a certain quantity of an inert gas leaks even when it is circulating and is required to be replenished, by stopping the supply of the inert gas and supplying the superheated heat transfer medium X as the fluidizing gas, it is possible to reduce the quantity of the active gas, and the operating costs are reduced.

[0062]

When sunset approaches and the superheating energy due to the solar superheater 10 is not obtained, the supply of the heat transfer medium X from the fluidizing steam supply unit 11 to the chamber 5 a is stopped, and the supply of the inert gas from the fluidizing gas supply device 6 to the chamber 5a is resumed. Further, when sunset approaches and the temperature of the heat transfer medium X becomes lower than the saturation temperature, the operation is switched to the cooling operation, and the subsequent operations are stopped.

[0063]

By operating the auxiliary boiler 4 around (before and after) sunrise in this way, it is possible to quicken the start timing of the drying operable period, and it is possible to dry the drying target Y for a longer period of time.

[0064]

As shown in Fig. 8, when the auxiliary boiler 4 is driven around (before and after) sunset, the operation of the auxiliary boiler 4 is started before sunset. This makes it possible to suppress a decrease in the temperature of the heat transfer medium X around (before and after) sunset. Thus, even when sunset passes, the temperature of the heat transfer medium X can be maintained at the boiling point for a while, and it is possible to continuously dry the drying target Y. However, since the time of operating the auxiliary boiler 4 is a time period in which the energy obtained from the sun is low, it is not possible to superheat the heat transfer medium X with the solar superheater 10. Therefore, at this time, the supply of the heat transfer medium X from the fluidizing steam supply unit 11 to the chamber 5a is stopped, and the fluidizing gas Z containing the inert gas is supplied from the fluidizing gas supply device 6 to the chamber 5 a. In this way, by operating the auxiliary boiler 4 around (before and after) sunset, it is possible to extend the drying operable period beyond sunset as shown in Fig. 8, and it is possible to dry the drying target Y for a longer period of time.

[0065]

Further, as shown in Fig. 9, when the auxiliary boiler 4 is driven around (before and after) sunrise and around (before and after) sunset, it is possible to quicken the start timing of the drying operable period, and it is possible to further extend the drying operable period time beyond sunset.

[0066]

The drying system 1A of the aforementioned present embodiment is equipped with the solar superheater 10 that further raises the temperature of the heat transfer medium X heated by the solar collectors 2. Therefore, it is possible to further raise the drying temperature in the drying furnace 5, and it is possible to dry the drying target Y in a short amount of time. Furthermore, according to the heat transfer medium X which is heated to the saturation temperature or higher, since the temperature is high enough, the heat transfer medium X does not agglomerate even when it comes into contact with the drying target Y during drying. Therefore, it is possible to use the heat transfer medium X as the fluidizing gas, and it is possible to reduce the usage of inert gas.

[0067] (Third embodiment)

Next, a third embodiment of the present disclosure will be described with reference to Fig. 10. In the description of the present embodiment, the parts similar to the above-mentioned first embodiment and second embodiment will be omitted or simplified.

[0068]

Fig. 10 is a flow diagram showing a schematic configuration of a drying system IB of the present embodiment. As shown in Fig. 10, the drying system IB of the present embodiment is provided along with a boiler power generation system 100 that uses the drying target Y (brown coal) dried in the drying system 1B of the present embodiment as a fuel, and adopts a configuration which includes an intermediate-pressure turbine extraction unit 12, a drying steam superheater 13 (superheater) and a low-pressure turbine extraction unit 14, in addition to the drying system lAof the second embodiment.

[0069]

Although the configuration of the boiler power generation system 100 is not particularly limited, the boiler power generation system 100 is equipped with a boiler 101 that generates steam by combusting the drying target Y, and a turbine 102 that generates rotational power using the steam obtained by the boiler 101. Further, although it is omitted in Fig. 10, the boiler power generation system 100 is equipped with a generator or the like that performs the power generation using the rotational power generated by the turbine 102. In the present embodiment, the turbine 102 is a three-stage type turbine that is equipped with a high-pressure turbine 102a, an intermediate-pressure turbine 102b and a low-pressure turbine 102c.

Further, the boiler 101 is equipped with a reheater 101a that reheats the steam discharged from the high-pressure turbine 102a and supplies the steam to the intermediate-pressure turbine 102b.

[0070]

The intermediate-pressure turbine extraction unit 12 is equipped with an extraction pipe 12a and a switching valve 12b. The extraction pipe 12a is a pipe that connects the intermediate-pressure turbine 102b and the low-pressure turbine 102c via the drying steam superheater 13. The switching valve 12b is disposed in the intermediate portion of the extraction pipe 12a, and opens and closes the flow passage formed by the extraction pipe 12a. The switching valve 12b is controlled by, for example, the control device 8. The intermediate-pressure turbine extraction unit 12 extracts the steam from the intermediate-pressure turbine 102b, guides the extracted steam to pass through the drying steam superheater 13, and supplies the extracted steam to the low-pressure turbine 102c.

[0071]

The drying steam superheater 13 is provided between the steam drum 3 and the drying furnace 5 in parallel with the solar superheater 10. The drying steam superheater 13 further raises the temperature of the heat transfer medium X by exchanging the heat between the steam extracted from the intermediate-pressure turbine 102b by the intermediate-pressure turbine extraction unit 12 and the heat transfer medium X disposed in the steam drum 3.

[0072]

The low-pressure turbine extraction unit 14 is provided with an extraction pipe 14a and a switching valve 12b. The extraction pipe 12a is connected to the low-pressure turbine 102c, and guides the steam extracted from the low-pressure turbine 102c toward the heat transfer tube 5c of the drying furnace 5. The switching valve 14b is disposed in the intermediate portion of the extraction pipe 14a, and opens and closes the flow passage formed by the extraction pipe 14a. The switching valve 14b is controlled by, for example, the control device 8. Such a low-pressure turbine extraction unit 14 extracts the steam from the low-pressure turbine 102c, and supplies the steam to the heat transfer tubes 5c of the drying furnace 5.

[0073]

The drying system 1B of the present embodiment is equipped with the drying steam superheater 13 that further raises the temperature of the heat transfer medium X heated by the solar collectors 2. Therefore, it is possible to further raise the drying temperature of the drying furnace 5, and it is possible to dry the drying target Y in a short amount of time. Furthermore, according to the heat transfer medium X which is heated to the saturation temperature or higher, since the temperature is high enough, the heat transfer medium does not agglomerate even when it comes into contact with the drying target Y during drying. Therefore, it is possible to use the heat transfer medium X as the fluidizing gas, and it is possible to reduce the usage of an inert gas.

[0074]

Further, in the drying system IB of the present embodiment, it is possible to supply some of the steam extracted from the low-pressure turbine 102c to the heat transfer tube 5c of the drying furnace 5. Therefore, when the flow rate of the heat transfer medium X discharged from the steam drum 3 is low, the flow rate can be compensated for by the steam from the low-pressure turbine 102c. Therefore, it is possible to extend the drying operable period, and it is also possible to operate the drying system IB, for example, for 24 hours.

[0075]

While preferred embodiments of the present disclosure have been described with reference to the accompanying drawings, the present disclosure is not limited to the aforementioned embodiments. Various shapes, combinations and the like of respective constituent members shown in the aforementioned embodiments are examples, and various modifications can be made based on design requirements and the like within the scope that does not depart from the scope of the present disclosure.

[0076]

For example, in the aforementioned embodiments, a configuration using a so-called fluidized bed type drying furnace for performing drying while fluidizing the drying target Y has been described as the drying furnace 5. However, the present disclosure is not limited thereto, and it is also possible to use other drying furnaces. For example, it is also possible to adopt a configuration using a moving bed type drying furnace that supplies the drying target Y to the inclined surface, and performs drying, while moving the drying target Y by weight. However, the fluidized bed type drying furnace 5 described in the aforementioned embodiment is advantageous in that it is possible to easily change the movement distance of the drying target Y by the arrangement interval or the like of the dividing wall 5b, and it is possible to optionally adjust the drying time of the drying target Y.

[0077]

Further, the configuration that drives the auxiliary boiler 4 at one or both of sunrise and sunset has been described in the aforementioned embodiments. However, the present disclosure is not limited thereto, and the auxiliary boiler 4 may be operated during cloudy or rainy weather. In such a case, for example, the control device 8 determines whether to operate the auxiliary boiler 4 on the basis of weather information that is input from the outside or a sensor that determines the weather conditions.

[0078]

According to the present disclosure, in the drying system for drying the fuel or the like containing a large quantity of moisture, it is possible to limit the consumption of fuel used for drying by utilizing the solar heat to limit an increase in the size of the facility, and to adjust the temperature of the drying target to the temperature that is suitable for drying.

[0078a]

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments.

[0078b]

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0078c]

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0079] 1 Drying system 1A Drying system IB Drying system 2 Solar collector 2a First reflector 2b Second reflector 2c Heat transfer tube 2d Driving device 2e Supporting portion 2f Collector tube 3 Steam drum 4 Auxiliary boiler 5 Drying furnace 5 a Chamber 5b Dividing wall 5b 1 First dividing wall 5b2 Second dividing wall 5 c Heat transfer tube 6 Fluidizing gas supply device (fluidizing gas supply means, inert gas supply unit) 6a Circulation pipe 6b Inert gas generator 6c Blower 6d Heat exchanger 6e Cooler 7 Heat transfer medium-circulating unit 7a Return flow pipe 7b Condenser 7c Feed water pump 7d Feed water preheater 7e Steam drum connection pipe 8 Control device 10 Solar superheater 11 Fluidizing steam supply unit (fluidizing gas supply means, superheated steam supply unit) 11a Superheated steam supply pipe lib Switching valve 12 Medium-pressure turbine extraction unit 12a Extraction pipe 12b Switching valve 13 Drying steam superheater (superheater) 14 Low-pressure turbine extraction unit 14a Extraction pipe 14b Switching valve 100 Boiler power generation system 101 Boiler 101a Reheater 102 Turbine 102a High-pressure turbine 102b Intermediate-pressure turbine 102c Low-pressure turbine X Heat transfer medium Y Drying target Z Fluidizing gas

Claims

The claims defining the invention are as follows:

1. A drying system comprising: a plurality of solar collectors that are provided to heat a heat transfer medium with solar heat; 5 a drying furnace that dries a drying target by exchanging heat between the heat transfer medium heated by the solar collector and the drying target; and a steam drum that is disposed between the solar collectors and the drying furnace to temporarily store the heat transfer medium which is vaporized by being heated by the solar collectors, 10 wherein the steam drum has an upper portion connected to the drying furnace, and a bottom portion connected to a heat transfer medium-circulating unit.
2. The drying system according to claim 1, further comprising: a superheater that further raises the temperature of the heat transfer medium heated by the solar collectors.
3. The drying system according to claim 1 or 2, further comprising: a fluidizing gas supply means that fluidizes the drying target in the drying furnace by supplying the fluidizing gas into the drying furnace.
4. The drying system according to claim 3, wherein a superheated steam supply unit configured to supply the superheated steam as the fluidizing gas to the drying furnace is 20 included as the fluidizing gas supply means.
5. The drying system according to claim 3 or 4, wherein an inert gas supply unit configured to supply an inert gas as the fluidizing gas to the drying furnace is included as the fluidizing gas supply means.
6. The drying system according to any one of claims 1 to 5, further comprising: an auxiliary boiler configured to heat the heat transfer medium separately from the solar collector.
7. The drying system according to claim 6, further comprising: a control device that operates the auxiliary boiler in accordance with at least one of sunrise and sunset.