JP2013061080A - Method and device for generating steam using solar heat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steam generation method for stably generating and supplying steam while reducing troubles due to a heat medium, in a system for generating steam using solar heat.SOLUTION: The method for generating steam using solar heat includes: a step (X) of circulating a heat medium gas g between a receiver 1, on which sunbeams are condensed by a light condensing device having a plurality of mirror bodies, and a regenerative furnace 2 including a breathable heat reservoir and, during the circulation, heating the heat medium gas g by sunbeams condensed to the receiver 1 while storing heat of the heat medium gas g in the regenerative furnace 2; and a step (Y) of circulating the heat medium gas g between the regenerative furnace 2 having passed the step (X) and a heat exchanger 3, and during the circulation, radiating heat stored in the regenerative furnace 2 to the heat medium gas g while exchanging heat between the heat medium gas g and water using the heat exchanger 3 to generate steam.

Description

  The present invention relates to a steam generation method using solar heat and a steam generation apparatus used for the implementation.

  Conventionally, what is shown by the nonpatent literature 1 is known as a solar thermal power generation plant. In this solar thermal power plant, as shown in FIG. 5, sunlight is collected by the parabolic trough 21 during the daytime, and the molten salt is circulated and heated to recover heat. A part of the heated molten salt is stored in the two heat storage tanks 22. The remaining molten salt exchanges heat with water in the heat exchanger 23 to generate steam to drive the steam turbine and the generator 24 to generate electricity. The steam that has passed through the steam turbine is condensed by the condenser 25 and circulated to the heat exchanger 23 again. On the other hand, at night, high-temperature molten salt stored in the heat storage tank 22 is circulated through the heat exchanger 23 to generate steam, and power is generated in the same manner as described above.

`` The parabolic trough power plants Andasol 1 to 3 '', Solar Millennium AG, 2008, p.12

  In the prior art as shown in Non-Patent Document 1, solar energy is recovered by a method in which molten salt is heated by solar heat and stored in a heat storage tank. This method has the advantage that steam can be generated even at night to generate electricity, but when the temperature of the molten salt decreases, the molten salt solidifies and clogs in the piping, making it impossible to operate. is there. For this reason, it is necessary to take measures such as keeping the entire pipe warmed with an electric heater, which increases equipment costs and operating costs.

  Therefore, the object of the present invention is to solve the above-described problems of the prior art, and in a system for generating steam using solar heat, troubles caused by the heat medium are unlikely to occur, and fluctuations in the amount of sunlight due to passage of clouds, etc. It is an object of the present invention to provide a steam generation method and apparatus capable of stably generating and supplying steam without being affected by the above.

The gist of the present invention for solving the above problems is as follows.
[1] Between a receiver (1) in which sunlight rays are condensed by a condensing device having a plurality of mirror bodies, and a heat storage furnace (2) having a breathable heat storage body inside. In the circulation, the heating medium gas g is heated with solar rays condensed on the receiver (1), and the heat of the heating medium gas g is stored in the regenerative furnace (2) (X) The heat medium gas g is circulated between the heat storage furnace (2) and the heat exchanger (3) having undergone the step (X), and the heat stored in the heat storage furnace (2) is circulated during the circulation. A method for generating steam using solar heat, comprising the step (Y) of generating heat by radiating heat to the gas g and causing the heat medium gas g to exchange heat with water in a heat exchanger (3).

[2] In the steam generation method according to [1] above, a plurality of regenerative furnaces (2) are used, and each of the regenerative furnaces (2) performs steps (X) and (Y) alternately, and a plurality of regenerators. A steam generation method using solar heat, wherein steam is continuously generated by sequentially performing the steps (Y) in the furnace (2).
[3] A steam generation method using solar heat, wherein the steam generated by the heat exchanger (3) is further heated by a heating device (7) in the steam generation method of [1] or [2].
[4] A solar thermal power generation method, wherein the steam turbine and the generator are driven by the steam generated by any one of the methods [1] to [3] to generate power.

[5] A receiver (1) that heats the heat medium gas g with solar rays collected by a condensing device having a plurality of mirrors in a circulation channel (4) that circulates the heat medium gas g; And a heat exchanger (2) in which a heat storage gas (g) is stored and heat is radiated or dissipated by the passage of the heat medium gas g, and a heat exchanger that generates steam by heat exchange between the heat medium gas g and water ( 3) is arranged, and the circulation channel (4) is capable of switching between the heat storage process and the heat dissipation process for each heat storage furnace (2), and the heat storage furnace (2) and the receiver (1) during the heat storage process ) And a gas circulation system for circulating the heating medium gas g between the heat storage furnace (2) and the heat exchanger (3) during the heat radiation process are simultaneously formed. And a piping mechanism having a plurality of on-off valves (5) and a circulation fan (6). A steam generator using solar heat.
[6] The steam generating apparatus using solar heat according to [5], further comprising a heating device (7) for further heating the steam generated by the heat exchanger (3).

[7] In the steam generator of [5] or [6] above, the flow path (44) connected to one end of each regenerative furnace (2) has two branch flow paths (440) and (441). Of these, the branch channel (440) is connected to the channel (40) on the heat medium gas outlet side of the receiver (1), and the branch channel (441) is on the heat medium gas inlet side of the heat exchanger (3). The flow path (45) connected to the other flow path (41) and connected to the other end of each regenerative furnace (2) has two branch flow paths (450) and (451), of which the branch flow The channel (450) is connected to the flow channel (42) on the heating medium gas inlet side of the receiver (1), and the branch channel (451) is the flow channel (43) on the heating medium gas outlet side of the heat exchanger (3). A circulation fan (6) is provided in each of the flow path (42) or (40) and the flow path (43) or (41), and each branch flow path (440), (44 ), (450), (451 A), respectively off valve (5) steam generator using solar heat, characterized in that is provided.
[8] A solar thermal power generation apparatus comprising the steam generation apparatus according to any one of the above [5] to [7], a steam turbine driven by steam generated by the steam generation apparatus, and a generator.

  ADVANTAGE OF THE INVENTION According to this invention, a steam can be stably produced using a solar heat by utilizing the thermal storage furnace which stores and heat-radiates with heat-medium gas. In addition, since no molten salt is used for the heat medium, troubles such as solidification of the heat medium in the piping do not occur even when the operation is stopped or when it rains. And its operating cost is unnecessary, and can be implemented at low cost.

Overall flow diagram of one embodiment of a steam generator of the present invention Explanatory drawing which shows the implementation condition of the steam generation method of this invention using the apparatus of FIG. Explanatory drawing which shows the implementation condition of the steam generation method of this invention using the apparatus of FIG. Explanatory drawing showing an example of operation mode of the method of the present invention Explanatory drawing showing a conventional device

FIG. 1 is an overall flow diagram of an embodiment of the steam generating apparatus of the present invention.
The steam generating apparatus of the present invention includes a receiver 1 that heats the heat medium gas g with solar rays condensed by the light condensing device S in a circulation channel 4 that circulates the heat medium gas g (for example, air), and an internal Are provided with a breathable heat storage body, a plurality of heat storage furnaces 2 in which heat is stored or released by passage of the heat medium gas g, and a heat exchanger 3 that generates steam by heat exchange between the heat medium gas g and water are arranged. Is done.
The condensing device S includes a plurality of mirror bodies, and reflects sunlight rays on the mirror bodies to collect the light rays on the receiver 1, and in this embodiment, guides the mirror bodies and the sun rays in the receiver direction. It is composed of a heliostat combined with a mirror angle control device. Usually, hundreds to thousands of heliostats are installed, and the mirror angle is controlled so that the sunlight rays always gather at the receiver 1 even if the position of the sun changes. In addition to the heliostat, for example, a parabolic trough, a linear Fresnel, a parabolic dish, or the like may be used as the light collecting device S.

  The receiver 1 is attached to an upper portion of a tower (a tower composed of a steel frame or the like) (not shown). Although the height of a tower is arbitrary, it is about 50m-100m normally, and height is designed appropriately by the quantity of the light which each receiver 1 receives. Multiple towers may be installed. On the light receiving surface of the receiver 1, for example, heat transfer tubes such as boiler tubes are densely arranged and heated by receiving the concentrated sunlight. The heat transfer gas g flows in the heat transfer tube, and the heat transfer gas g is heated by heat transfer from the heat transfer tube. Although the size of the light receiving surface of one receiver 1 is arbitrary, the height and the width are usually several meters to ten meters, and the area is about several tens square meters to one hundred square meters.

The regenerative furnace 2 (hot stove) includes a breathable heat accumulator in the inside, similar to a hot stove used for supplying high-temperature air to the blast furnace tuyere in the iron making process. This breathable heat storage body is configured by, for example, stacking refractories (bricks) in which a large number of gas vent holes are formed. When the high-temperature heat transfer gas g passes through the breathable heat storage body, the heat of the heat transfer medium gas g is stored in the breathable heat storage body (heat storage process), while the stored high-temperature breathable heat storage body is cooled to a low temperature. When the heat transfer medium gas g passes, the heat transfer medium gas g is heated by the heat of the breathable heat storage body (heat radiation step). Usually, the outer shell of the regenerative furnace 2 is a steel pressure vessel. In the present embodiment, two heat storage furnaces 2 (heat storage furnaces 2 _A and 2 _B ) are provided, but three or more heat storage furnaces may be provided. The size of each regenerative furnace 2 is arbitrary, but the diameter is usually about several meters to ten meters and the height is about several tens meters to hundred meters.

The heat exchanger 3 heat-exchanges the heat transfer medium gas g passing through the inside of the vessel and water to generate steam from the water. The heat exchanger 3 is connected to a water supply pipe from a water tank 8 by a pump 9. The required amount of water is supplied through 10.
The circulation channel 4 has a piping mechanism provided with an on-off valve and a circulation fan necessary for alternately performing a heat storage process and a heat dissipation process in the two heat storage furnaces 2. That is, this piping mechanism includes a plurality of on-off valves 5 and a circulation fan 6, and can switch between the heat storage process and the heat dissipation process for each heat storage furnace 2, and between the heat storage furnace 2 and the receiver 1 during the heat storage process. A piping mechanism capable of simultaneously forming a gas circulation system that circulates the heat medium gas g and a gas circulation system that circulates the heat medium gas g between the heat storage furnace 2 and the heat exchanger 3 during the heat radiation process. is there.

Specifically, the piping mechanism has the following configuration. That is, the flow paths 44 _A and 44 _B connected to one end side of each of the heat storage furnaces 2 _A and 2 _B have two branch flow paths 440 and 441, respectively, of which the branch flow path 440 is the heat of the receiver 1. The branch channel 441 is connected to the channel 41 on the heat medium gas inlet side of the heat exchanger 3. The flow paths 45 _A and 45 _B connected to the other ends of the regenerative furnaces 2 _A and 2 _B have two branch flow paths 450 and 451, respectively, of which the branch flow path 450 is the receiver 1. The branch channel 451 is connected to the channel 43 on the heat medium gas outlet side of the heat exchanger 3. Circulating fans 6a and 6b are provided in the channel 42 and the channel 43, respectively. Each branch channel 440 has on / off valves 5a and 5b, each branch channel 441 has on / off valves 5c and 5d, and each branch channel 450 has on / off valves 5e and 5f on each branch channel 451. Open / close valves 5g and 5h are respectively provided. In addition, the piping which comprises the above piping mechanism has a required heat retention structure.

The circulation fan 6 a circulates the heat medium gas g between the receiver 1 and the arbitrary heat storage furnace 2, and the circulation fan 6 b circulates the heat medium gas g between the arbitrary heat storage furnace 2 and the heat exchanger 3. Let The circulation fan 6a may be provided in the flow path 40 and the circulation fan 6b may be provided in the flow path 41, respectively.
The circulation fans 6a and 6b have heat resistance that can withstand temperatures of about 300 ° C., and the air flow rate can be adjusted by a control device (not shown).
In this embodiment, the heating apparatus 7 which can further heat the vapor | steam produced | generated with the heat exchanger 3 is provided. In this heating device 7, fuel is used as a heat source. After heating the steam as necessary, it is sent to the lower process.
When the lower process is a power generation process using a steam turbine and a generator, a solar thermal power generation apparatus is configured by the power generation steam turbine and power generator and the steam generation device described above.

Next, the steam generation method of the present invention will be described.
The steam generation method of the present invention includes a receiver 1 in which sunlight rays are collected by a condensing device having a plurality of mirror bodies, and a heat storage furnace 2 having a breathable heat storage body therein. In the circulation, the heating medium gas g is heated with solar rays condensed on the receiver 1, and the heat X of the heating medium gas g is stored in the heat storage furnace 2 (heat storage process); The heat medium gas g is circulated between the heat storage furnace 2 and the heat exchanger 3 that have undergone the process X, and during this circulation, the heat stored in the heat storage furnace 2 is radiated to the heat medium gas g, and the heat It has process Y (heat dissipation process) which carries out heat exchange of medium gas g with water with heat exchanger 3, and generates steam. In this steam generation method, a plurality of regenerative furnaces 2 are used, and the process X and the process Y are alternately performed in each regenerative furnace 2, and the process Y is sequentially performed in the plurality of regenerative furnaces 2 to continuously steam. It is preferable to generate them automatically. Further, the steam generated by the heat exchanger 3 can be further heated by the heating device 7.
The type of the heat transfer gas g is arbitrary, but usually air is used.

Hereinafter, an embodiment of the steam generation method of the present invention will be described based on FIGS. 2 and 3 by taking the case of using the apparatus of the embodiment shown in FIG. 1 as an example. In this embodiment, air is used as the heating medium gas g. The open / close valves 5a to 5h shown in FIGS. 2 and 3 indicate that the white ones are in an open state and the ones that are blacked out are in a closed state.
Here, the heat storage process in regenerative furnace 2 _A If the regenerative furnace 2 _B in the heat radiation step is respectively carried out (first step), as shown in FIG. 2, the on-off valve 5b, 5c, 5f, and 5g closed state, (including branched flow path 440) opening and closing valve 5a, 5d, 5e, 5h was opened and air receiver 1 and regenerative furnace ₂ stream is circulated between _a path 42 → the passage 40 → the passage 44 _a → flow path 45 a gas circulation system consisting of _(including branch channel 450) (hereinafter, "the gas circulation system (i)") and, flow causes air to circulate between the regenerative furnace 2 _B and the heat exchanger 3 channel 43 → Flow path 45 _B (including branch flow path 451) → Flow path 44 _B (including branch flow path 441) → A gas circulation system including the flow path 41 (hereinafter referred to as “gas circulation system (ii)”) Form each one.

The gas circulation system in (i), the circulation fan 6a air is circulated between the heat storage furnace 2 _A and receiver 1, the process previously described X (heat storage process) is performed. The sunlight is condensed on the light receiving surface of the receiver 1 by the light collecting device S, and the air passing through the receiver 1 (heat transfer tube on the light receiving surface) is heated. At this time, the condensing magnification (total heliostat mirror area / receiver light receiving area) on the receiver light receiving surface is about 500 to 1000 times. Moreover, the outer surface temperature of the heat exchanger tube in a light-receiving surface is about 600-900 degreeC, and the temperature of the air in a receiver exit is 500-700 degreeC. At this time, the receiver is designed so that the ratio of the energy obtained by heating the air to the energy of the sunlight reaching the receiver light-receiving surface is 75% or more. 500 to 700 ° C. hot air exiting from the receiver 1, regenerative furnace 2 to heat the furnace interior breathable regenerator while passing through the _A and stored heat in the heat storage furnace 2 _A heat storage at 300 ° C. below the temperature exiting the furnace _{2 a.} In this manner, the energy of the sunlight stored in the heat storage furnace 2 _A. At this time, the temperature distribution inside the heat storage furnace _{2 A,} a gas inlet side (the flow path 44 _A side) 500 to 700 ° C., the gas outlet side (the flow path 45 _A side) is about 300 ° C..

Meanwhile, the In the gas circulation system (ii), the circulation fan 6b air is circulated between the heat storage furnace 2 _B and the heat exchanger 3, the steps previously described Y (radiating step) is performed. Water is supplied from the water tank 8 to the heat exchanger 3 by a pump 9. Regenerative furnace 2 _B of the process Y is performed in a state already been heated in the previous step (step X). Air after being heated to approximately four hundred and eighty to six hundred eighty ° C. The breathable regenerator furnace interior in the process of passing through the regenerative furnace 2 _B, it enters the heat exchanger 3. In the heat exchanger 3, heat is exchanged between air and water to generate steam (saturated steam or superheated steam). The air leaves the heat exchanger 3 at a temperature below 200 ° C.
When the steam generated by the heat exchanger 3 does not satisfy the requirements of the lower process, the steam is heated by the heating device 7 using the fuel as a heat source and then sent to the lower process. Since such heating is possible, even when the temperature condition of the steam required in the lower process is changed to a high temperature side, it can be easily handled.

Performing operation for a predetermined time as described above, heat in the heat storage furnace 2 _A (solar energy) is sufficiently accumulated, the temperature of the air flowing through the flow path 45 _A, 42 of the outgoing side of the heat storage furnace 2 _A rises Then, it approaches the heat resistant use temperature of the circulation fan 6a. On the other hand, regenerative furnace 2 _B in the heat (solar energy) is the consumption, of the air flowing through the flow path 44 _B, 41 of the outlet side of the heat storage furnace 2 _B temperature decreases, the steam produced in the heat exchanger 3 The temperature drops.
In such a time, the heat storage furnace 2 _B step X (heat storage process) is switched to the step Y operation of (radiating step) are carried out respectively in regenerative furnace 2 _A (second step). That is, as shown in FIG. 3, the on-off valve 5a, 5d, 5e, 5h the closed state, the on-off valve 5b, 5c, 5f, and 5g to the open state, flow circulating air between the receiver 1 and the regenerative furnace 2 _B A gas circulation system including a channel 42 → a channel 40 → a channel 44 _B (including a branch channel 440) → a channel 45 _B (including a branch channel 450), and air to the heat exchanger 3 and the regenerative furnace 2 _{A A} gas circulation system consisting of a flow path 43 to be circulated, a flow path 45 _A (including a branch flow path 451), a flow path 44 _A (including a branch flow path 441), and a flow path 41 is formed. Then, although the heat storage process and the heat radiation process in both gas circulation system is conducted, the details of which regenerative furnace 2 _B and regenerative furnace 2 _A is only reversed, the same as described for FIG.

Performs operations such as predetermined time or more, the heat in the heat storage furnace 2 _B (solar energy) is sufficiently accumulated, the temperature of the air flowing through the flow path 45 _B, 42 of the outlet side of the heat storage furnace 2 _B rises circulates approaches the heat operating temperature of the fan 6a, whereas, is consumed heat of the heat storage furnace 2 _a (solar energy), the temperature of the air flowing through the flow path 44 _a, 41 of the outgoing side of the heat storage furnace 2 _a is reduced, heat When the temperature of the vapor produced in the exchanger 3 is lowered again operation of FIG. 2, i.e., the heat storage furnace 2 _a process X (heat storage step) is, the step Y (the heat radiation step) in regenerative furnace 2b Switch to operations where
By repeating the above steps, as long as the sunbeam reaches the receiver 1, it is possible to recover the energy of the sunbeam and continue to produce steam.

Figure 4 (a), (b) shows an operational embodiment of the present invention method, the horizontal axis represents time and the vertical axis represents regenerative furnace 2 _B heat storage and regenerative furnace 2 _A, the heat radiation, which states the heat-retaining Is shown.
Figure In operation the form of 4 (A), only the times can be received from the sun, alternately performs heat radiation and the heat storage in the heat storage furnace 2 _B and regenerative furnace 2 _A, and steam continuously generate. Meanwhile, during a time period that can not be received from the sun, it is both heat retaining state regenerative furnace 2 _B and regenerative furnace 2 _A, air circulation is not performed, the steam is not generated.

On the other hand, the operation mode of FIG. 4 (a) is performed as follows. In regenerative furnace 2 _A, do the coercive heat from nighttime A to the initial daytime A, in the daytime A, in the morning, the day is rising, the amount of light received by the receiver 1 starts the heat storage from equal to or greater than a certain degree, afternoon, When the sun goes down and the amount of light received by the receiver 1 falls below a certain level, the heat storage is stopped and the heat is kept. In the heat retaining state, air is not circulated and no steam is generated. On the other hand, the heat radiation from the heat storage furnace 2 _B at night A, carried out 24 hours continuously throughout the day A. In this case, the circulation fan 6b is operated with a reduced air flow so that heat can be continuously dissipated for 24 hours. The next day, regenerative furnace 2 heat dissipation from _A nighttime B, Day 24 hour continuous conducted through B, whereas, in the regenerative furnace 2 _B, performs heat retaining from night B to the initial day B, during the day B, AM Heat storage starts after the sun rises and the amount of light received by the receiver 1 exceeds a certain level. After the afternoon and day, when the amount of light received by the receiver 1 falls below a certain level, the heat storage stops and the heat is retained. State. In operation according to FIG. 4 (b), may be a regenerative furnace 2 _A by performing alternately on a daily basis the radiator and the heat storage in the heat storage furnace 2 _B, keeps continuously produced steam day and night.

DESCRIPTION OF SYMBOLS 1 Receiver 2, 2 _A , 2 _B Regenerative furnace 3 Heat exchanger 4 Circulation flow path 5, 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h On-off valve 6, 6a, 6b Circulation fan 7 Heating device 8 Water tank 9 pump 10 water supply pipe _{40,41,42,43,44 A, 44 B, 45 A} , 45 B passage 440,441,450,451 branch channel S light collector

Claims (8)

The heat medium gas g is circulated between a receiver (1) where sunlight rays are collected by a light collecting device including a plurality of mirrors and a heat storage furnace (2) provided with a breathable heat storage body inside. In the circulation, the heating medium gas g is heated with solar rays condensed on the receiver (1), and the heat of the heating medium gas g is stored in the heat storage furnace (2) (X),
The heat transfer gas g is circulated between the heat storage furnace (2) and the heat exchanger (3) that have undergone the step (X), and during this circulation, the heat stored in the heat storage furnace (2) is transferred to the heat transfer gas. A method for generating steam using solar heat, comprising the step (Y) of generating heat by radiating heat to g and heat-exchanging the heat medium gas g with water in a heat exchanger (3).   Using a plurality of regenerative furnaces (2), the steps (X) and (Y) are alternately performed in each regenerative furnace (2), and the steps (Y) are sequentially performed in the plurality of regenerative furnaces (2). The steam generation method using solar heat according to claim 1, wherein the steam is continuously generated.   The steam generated by the heat exchanger (3) is further heated by a heating device (7), and the steam generating method using solar heat according to claim 1 or 2.   A solar thermal power generation method, wherein a steam turbine and a generator are driven by steam generated by the method according to claim 1 to generate power. A receiver (1) for heating the heat medium gas g with solar rays collected by a condensing device having a plurality of mirror bodies in the circulation channel (4) for circulating the heat medium gas g, and a breathability inside. A plurality of heat storage furnaces (2) that include a heat storage body and store or release heat by passage of the heat medium gas g, and a heat exchanger (3) that generates steam by heat exchange between the heat medium gas g and water. And placed
The circulation channel (4) is capable of switching between the heat storage process and the heat dissipation process for each heat storage furnace (2), and between the heat storage furnace (2) and the receiver (1) during the heat storage process. a gas circulation system that circulates g, and a gas circulation system that circulates the heating medium gas g between the heat storage furnace (2) and the heat exchanger (3) during the heat radiation step can be simultaneously formed. A steam generator using solar heat, comprising a piping mechanism comprising an on-off valve (5) and a circulation fan (6).   The steam generator using solar heat according to claim 5, further comprising a heating device (7) for further heating the steam generated by the heat exchanger (3). The flow path (44) connected to one end of each regenerative furnace (2) has two branch flow paths (440) and (441), of which the branch flow path (440) is the heat of the receiver (1). Connected to the flow path (40) on the medium gas outlet side, the branch flow path (441) is connected to the flow path (41) on the heat medium gas input side of the heat exchanger (3),
The flow path (45) connected to the other end of each regenerative furnace (2) has two branch flow paths (450) and (451), of which the branch flow path (450) is the receiver (1). Connected to the flow path (42) on the heat medium gas inlet side, the branch flow path (451) is connected to the flow path (43) on the heat medium gas outlet side of the heat exchanger (3),
A circulation fan (6) is provided in each of the flow path (42) or (40) and the flow path (43) or (41),
Steam generation using solar heat according to claim 5 or 6, characterized in that each branch channel (440), (441), (450), (451) is provided with an on-off valve (5), respectively. apparatus.   A solar thermal power generation apparatus comprising: the steam generation apparatus according to claim 5; a steam turbine driven by steam generated by the steam generation apparatus; and a generator.

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