JP4725294B2 - Fluidized bed furnace for medium circulation equipment - Google Patents

Description

  In the present invention, fuel such as general waste or waste solidified fuel (RDF, RPF) or coal is burned in a combustion furnace, and the generated high-temperature fluidized medium is externally circulated to an external fluidized bed furnace to flow. The present invention relates to a fluidized bed furnace of a medium circulation facility that can effectively use the heat of the medium.

  Conventionally, a circulating fluidized bed boiler has been proposed as a medium circulating facility for externally circulating a fluidized medium of a combustion furnace to an external fluidized bed furnace (see, for example, Patent Document 1). FIG. 8 shows the configuration of a circulating fluidized bed boiler disclosed in Patent Document 1. The combustion furnace 1 and particles contained in the exhaust gas by introducing exhaust gas generated by combustion in the combustion furnace 1 (fluid medium) ), A fluidized bed furnace 3 as a boiler device 3A for introducing and heat-exchanged particles collected by the medium separator 2, and a fluidized bed furnace 3 A steam heat transfer tube 4 that performs heat exchange with the fluidized medium therein and a duct 5 that returns the fluidized medium in the fluidized bed furnace 3 to the combustion furnace 1 are provided.

  The combustion furnace 1 is formed of a water-cooled furnace wall. At the bottom of the combustion furnace 1, fluid A is introduced into the furnace and fluidized together with a bed material made of sand, ash, limestone, or the like. The air dispersion nozzle 6 is provided, and the fuel 7 is burned by a fluidized bed formed on the air dispersion nozzle 6 for flow. The medium separator 2 is connected to the upper part of the combustion furnace 1, and the upper part of the medium separator 2 is connected to a rear heat transfer section 8 for leading the exhaust gas after separating the fluidized medium. A medium flow pipe 9 that guides the collected fluid medium to the fluidized bed furnace 3 is connected to the lower part of the medium separator 2. The rear heat transfer section 8 is provided with a heat transfer section for performing heat recovery of the exhaust gas.

  Formed at the bottom of the fluidized bed furnace 3 is a wind box 11 for introducing fluidized air A upward from the dispersion plate 10 to form a fluidized bed 21, and the medium flow down pipe of the fluidized bed furnace 3. A combustion chamber 12 that actively burns the unburned portion of the fluidized medium is formed by a partition plate 12a at a lower portion of 9 and a fluidized medium whose temperature is increased by combustion is introduced to the side of the combustion chamber 12 Thus, a heat exchange chamber 13 is formed in which heat recovery is performed by the steam heat transfer tube 4. The exhaust gas when the unburned portion in the fluid medium is burned in the combustion chamber 12 is guided to the combustion furnace 1 from the corrosive gas duct 14 provided at the top.

  In the circulating fluidized bed boiler of FIG. 8 described above, the air A and the fuel 7 are combusted in the combustion furnace 1 while being fluidized together with the bed material made of sand, ash, limestone, etc. Steam to be supplied to the illustrated steam turbine for power generation is generated. On the other hand, particles (fluid medium) blown up by the exhaust gas generated by the combustion in the combustion furnace 1 are collected by the medium separator 2 and introduced into the fluidized bed furnace 3 through the medium flow down pipe 9. The fluidized medium introduced into the fluidized bed furnace 3 is bubbled by the fluidizing air A, and is removed by heating the steam by heat exchange with the steam heat transfer tube 4 by the fluidized bed 21. And returned to the bottom of the combustion furnace 1 to circulate.

Further, in place of the fluidized bed furnace 3 including the boiler apparatus 3A having the steam heat transfer tube 4 as shown in FIG. 8, a gasifier having a raw material supply port 19 and a product gas outlet 20 as shown in FIG. A fluidized bed furnace 3 consisting of 3B has also been proposed. In the fluidized bed furnace 3, a raw material supply port 19 supplies a raw material such as coal and biomass into the gasifier 3 </ b> B, and a decomposition promoting gas such as steam B for promoting the decomposition of the raw material from the dispersion plate 10. To form a fluidized bed 21, gasify the raw material by contact with a high-temperature fluidized medium, lead the generated gasification gas to the outside from the product gas outlet 20, and various combustion fuels, It is used as a fuel for hydrogen fuel cell power generation, as a raw material gas for a gas synthesis system. In the case of the gasifier 3B of FIG. 13, the char generated during the gasification of the gasified fuel circulates in the combustion furnace 1 and burns to become a heat source. It is sufficient to supply only the fuel 7 '(city gas, kerosene, etc.).

JP 2003-207115 A

  The circulating fluidized bed boiler shown in FIG. 8 supplies the fluidized medium separated by the medium separator 2 to one side in the longitudinal direction (right side in FIG. 8) of the fluidized bed furnace 3 which is the boiler device 3A through the medium flow down pipe 9. While the fluidized medium supplied to the fluidized bed furnace 3 is introduced into one duct 5 on the other side of the fluidized bed furnace 3 (left side in FIG. 8) while flowing by bubbling of the fluidized bed 21, steam in the heat exchange chamber 13 is introduced. The heat transfer pipe 4 has a configuration in which heat is recovered from the fluidized medium, and the fluidized medium supplied in the fluidized bed furnace 3 from the medium flow-down pipe 9 moves toward one duct 5 in the horizontal direction. There is a problem of creating a stagnant medium stagnation part.

  For example, in FIGS. 9 and 10, the medium flow down pipe 9 is arranged on one side in the longitudinal direction of the fluidized bed furnace 3 having a rectangular planar shape, and the side wall surface 3 a on the other side in the longitudinal direction of the fluidized bed furnace 3. Although the case where the duct 5 is arranged is shown, in this configuration, the fluid medium supplied from the medium flow down pipe 9 to the fluidized bed furnace 3 flows toward the duct 5 while flowing by the fluid air A. When moving, it shows a tendency to move linearly along the shortest distance connecting the medium flow down pipe 9 and the duct 5. For this reason, as shown in FIG. 10 with hatching, the portion of the fluidized bed furnace 3 opposite to the duct 5 with respect to the longitudinal direction of the fluidized bed furnace 3 in a plan view has a lateral direction (horizontal direction) of the fluidized medium. The medium stagnation part X that is in a state where the movement to the stagnation is delayed occurs.

  11 and 12, the medium flow pipe 9 is disposed on one side in the longitudinal direction of the fluidized bed furnace 3 having a rectangular planar shape, and the duct 5 is connected to the end wall surface 3 b on the other side in the longitudinal direction of the fluidized bed furnace 3. In this configuration, the fluidized medium supplied from the medium flow down pipe 9 to the fluidized bed furnace 3 moves toward the duct 5 while flowing with the fluidizing air A. In this case, there is a tendency to linearly move the center in the width direction of the fluidized bed furnace 3 which is the shortest distance connecting the medium flow down pipe 9 and the duct 5. For this reason, as shown in FIG. 12 with hatching, the medium stagnation portions X in which the movement of the fluidized medium in the horizontal direction is stagnated on both sides in the width direction of the fluidized bed furnace 3 when viewed in plan. Arise.

  The present inventors prepared sand mixed with colored sand for easy observation, and in the conventional apparatus shown in FIGS. 9 and 10 and the conventional apparatus shown in FIGS. The sand is supplied to the fluidized bed furnace 3, the fluidized bed 21 is formed and the sand is supplied to the duct 5, and the formation state of the fluidized bed 21 and the state of the sand flow to the duct 5 are observed. Experiments were performed. As a result, in the conventional apparatus, it was clearly observed that the medium stagnation part X where the horizontal movement of the sand was stagnated was generated as shown in FIGS.

  As described above, when the medium stagnation part X in which the movement of the fluid medium in the horizontal direction stagnates in the fluidized bed furnace 3, the fluid medium in the medium stagnation part X is flow air A ( Since the time of exposure to (see FIG. 8) becomes longer and cooling proceeds, a large temperature difference occurs in the fluidized medium in the fluidized bed furnace 3. Further, since the unburnt portion is also burned unevenly by the medium stagnation portion X, the combustion efficiency is also lowered. Accordingly, since the temperature of the fluidized bed 21 in the fluidized bed furnace 3 is unevenly and lowered, the heat exchange efficiency by the steam heat transfer tube 4 of the boiler device 3A is lowered, and therefore the steam extraction by the steam heat transfer tube 4 is reduced. There is a problem that the temperature decreases.

  Further, as shown in FIG. 13, a raw material supply port 19 and a generated gas outlet 20 for supplying a raw material to be gasified are provided, and a fluidized bed 21 is formed by supplying steam B or the like from the dispersion plate 10. Also in the fluidized bed furnace 3 by the gasification apparatus 3B adapted to gasify the raw material, the medium stagnation part where the movement of the fluidized medium in the horizontal direction is stagnant as in FIGS. 10 and 12. The problem of X occurs, and the gas stagnation part X causes the gasification reaction in the gasifier 3B to become non-uniform, resulting in a problem of deterioration in gasification efficiency.

  The present invention has been made to solve the above-described conventional problems, and is a medium circulation facility that prevents the stagnation of the flow of the fluid medium in the fluidized bed furnace and makes the temperature inside the fluidized bed furnace uniform. An object is to provide a fluidized bed furnace.

  According to the first aspect of the present invention, the exhaust gas from the combustion furnace is guided to the medium separator to separate the fluidized medium, and the separated fluidized medium is supplied to one side of the fluidized bed furnace by the medium flow down pipe. The fluidized bed furnace of the medium circulation facility is configured to return the fluidized medium in the fluidized bed furnace to the combustion furnace by a duct provided on the other side of the fluidized bed furnace. One end on the side close to the medium flow down pipe and the other end on the far side are in the medium stagnation part where the horizontal movement of the flowing medium is stagnant in the middle of the flow medium supplied to one side of the fluidized bed furnace by the flow down pipe toward the other duct And a fluidized bed furnace of a medium circulation facility, characterized in that a medium guiding path that covers the bottom of the fluidized bed furnace in a tunnel shape is formed by a partition plate.

  The fluidized bed furnace according to claim 1, wherein the fluidized bed furnace is a boiler device that heats a steam heat transfer tube with a fluidized medium.

  2. The fluidized bed furnace for a medium circulation facility according to claim 1, wherein the fluidized bed furnace is a gasification apparatus having a raw material supply port and a product gas outlet and performing gasification of the raw material with a fluidized medium. , Related to

  The partition plate forming the medium guiding path is characterized in that the upper plate has a height at the other end farther from a height at one end closer to the medium flow down pipe. The fluidized bed furnace of the medium circulation facility according to any one of 1 to 3.

  Further, the partition plate forming the medium guiding path is an inclined plate in which the upper plate is formed in a descending gradient with one side in the width direction facing the inside of the fluidized bed furnace. This relates to the fluidized bed furnace of the medium circulation facility described in one.

  According to the above means, the following operation can be obtained.

  As described above, in the medium stagnation part where the fluid medium supplied from one side of the medium flow pipe to one side in the fluidized bed furnace goes to the duct on the other side, the horizontal movement of the fluid medium is stagnated. Since a medium guide path is formed by a partition plate that opens at the one end on the near side and the other end on the far side and covers the bottom of the fluidized bed furnace in a tunnel shape, the inside of the medium guide path is flown by the flow air. The flow of the medium is promoted, so that the flow medium supplied from the medium flow down pipe is actively sent from the opening on one end side of the medium guiding path toward the opening on the other end side. The problem that the medium stagnation part of the horizontal movement of the fluidized medium in the bed furnace can be solved.

  According to the fluidized bed furnace of the medium circulation facility of the present invention, the medium guide path is formed by the partition plate in the medium stagnation part where the horizontal movement of the fluidized medium generated in the fluidized bed furnace is stagnated to promote the flow of the fluidized medium. Since it did in this way, the problem that the medium stagnation part of the horizontal movement of a fluidized medium arises in a fluidized bed furnace is prevented, and it has the effect that the temperature of the fluidized bed in a fluidized bed furnace can be kept substantially uniform.

  Therefore, in the case where the fluidized bed furnace is a boiler apparatus equipped with a steam heat transfer tube, the fluidized medium can be made to flow substantially uniformly inside the fluidized bed furnace to burn the unburned portion. There is an effect that the temperature of taking out the steam by the steam heat transfer tube can be effectively increased while being kept at a uniform and high temperature.

  In the case where the fluidized bed furnace is a gasification apparatus provided with a raw material supply port and a product gas outlet, the temperature of the fluidized bed in the fluidized bed furnace is maintained substantially uniform, thereby gasifying the raw material. The reaction is promoted and the gasification efficiency is improved.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIGS. 1 to 3 show an embodiment of the present invention applied to the fluidized bed furnace 3 as the boiler apparatus 3A of FIGS. 8 to 10, and are the same as FIGS. 8 to 10 in the figure. Are denoted by the same reference numerals, description thereof is omitted, and only the features of the present invention will be described in detail.

  In FIG. 1 to FIG. 3, as shown in FIG. 10, the fluid medium supplied to one side in the fluidized bed furnace 3 by the medium flow pipe 9 is in the horizontal direction of the fluid medium on the way to the duct 5 on the other side. The medium stagnation part X where the movement is stagnated has an opening 15 at one end close to the medium flow-down pipe 9 and an opening 16 at the other end far from the medium so as to cover the bottom of the fluidized bed furnace 3 in a tunnel shape. The medium guide path 17 is formed by the partition plate 18 including the upper plate 18a and the side plate 18b.

  In FIG. 2, the medium guiding path 17 has a rectangular cross section, and the height of the medium guiding path 17 is set at a predetermined distance from the bottom of the fluidized bed furnace 3. It is formed lower than the lower end position.

  The steam heat transfer tubes 4 are arranged so as to extend over substantially the entire plane of the fluidized bed furnace 3. In FIG. 2, only one stage of the steam heat transfer tubes 4 is provided, but any number of stages can be provided.

  The upper plate 18a of the partition plate 18 is an inclined plate 18a 'formed by inclining one side in the width direction toward the inside of the fluidized bed furnace 3 as shown by a two-dot chain line in FIG. In addition, according to the configuration of the inclined plate 18 a ′, the fluid medium can be prevented from being stored (deposited) on the partition plate 18.

  In addition, as shown in FIG. 4, the partition plate 18 forming the medium guiding path 17 has the other end on the side far from the height of one end (opening 15 side) on the side where the upper plate 18a is close to the medium flow down pipe 9. It can be formed by the upper plate 18a ″ inclined in the longitudinal direction so that the height of the (opening 16 side) is increased.

  Next, the operation of the embodiment shown in FIGS.

  As shown in FIG. 10, the fluidized medium moves in the horizontal direction while the fluidized medium supplied by the medium flow pipe 9 provided on one side in the fluidized bed furnace 3 flows toward the duct 5 provided on the other side. As shown in FIGS. 1 to 3, the fluid stagnation section X in the state where the stagnation is in the state is such that one end on the side close to the medium flow-down pipe 9 and the other end on the far side open 15 and 16. 3 is formed by the partition plate 18 so as to cover the bottom of the medium 3 in a tunnel shape, the flow of the fluid medium by the flow air A from the wind box 11 is more inside the medium guide path 17 than outside the medium guide path 17. Will be promoted. Further, the flowing medium is pushed out from the medium flow down pipe 9 one after another, and thus the flowing medium acts to be pushed into the medium guiding path 17 from the opening 15 on one end side of the medium guiding path 17. Since the flow is promoted inside 17 and the flow medium is easy to move, the flow medium is easily moved toward the opening 16 on the other end side. Therefore, this eliminates the problem that the medium stagnation part X of the horizontal movement of the fluidized medium occurs in the fluidized bed furnace 3, and the fluidized medium flows substantially uniformly in the fluidized bed furnace 3.

  Experiments in which the present inventors observe the formation state of the fluidized bed and the state of the sand flow to the duct 5 in the apparatus shown in FIGS. As a result, the sand effectively flows through the inside of the medium guiding path 17, thereby effectively preventing the problem that the medium stagnation part X of the horizontal movement of the fluidized medium occurs in the fluidized bed furnace 3. I was able to resolve it.

  At this time, as shown in FIG. 4, the upper plate 18 a of the partition plate 18 forming the medium guiding path 17 is disposed on the side far from the height of the opening 15 at one end close to the medium flow down pipe 9. If the upper plate 18a "is inclined in the longitudinal direction so that the height of the opening 16 at the other end is increased, the moving medium flows from the opening 15 at one end toward the opening 16 at the other end. It can be further enhanced.

  Further, when the upper plate 18a of the partition plate 18 is an inclined plate 18a 'formed so that one side in the width direction becomes a downward gradient toward the inside of the fluidized bed furnace 3, as shown by a two-dot chain line in FIG. The problem that the fluid medium is stored (deposited) on the partition plate 18 can be prevented.

  As described above, the medium guiding path 17 is provided inside the fluidized bed furnace 3 to prevent the problem that the medium stagnation part X of the fluidized medium moves horizontally in the fluidized bed furnace 3. Since the inside of the furnace 3 flows substantially uniformly, the temperature of the fluidized bed in the fluidized bed furnace is kept substantially uniform and the unburned portion is combusted uniformly. In the fluidized bed furnace 3, the heat exchange efficiency by the steam heat transfer tube 4 can be improved, and the temperature for taking out the steam by the steam heat transfer tube 4 can be effectively increased.

  FIG. 5 shows another embodiment of the present invention applied to the fluidized bed furnace 3 shown in FIGS. 11 and 12. In FIG. 5, the same components as those shown in FIGS. Therefore, only the features of the present invention will be described in detail.

  In the form of FIG. 5, as shown in FIG. 12, the fluid medium supplied to one side in the fluidized bed furnace 3 by the medium flow down pipe 9 moves in the horizontal direction on the way to the duct 5 on the other side. The fluidized bed has an opening 15 at one end close to the medium flow down pipe 9 and an opening 16 at the other end far from the medium stagnation part X on both sides in the width direction of the fluidized bed furnace 3 where the fluidized bed furnace 3 is stagnant A medium guide path 17 that covers the bottom of the furnace 3 in a tunnel shape is formed by a partition plate 18.

  Also in the form of FIG. 5, the upper plate 18 a of the partition plate 18 is an inclined plate 18 a ′ formed in a downward gradient with one side in the width direction facing the inside of the fluidized bed furnace 3 as shown by a two-dot chain line in FIG. 2. Further, the upper plate 18a of the partition plate 18 forming the medium guiding path 17 is, as shown in FIG. 4, a side far from the height of the opening 15 at one end close to the medium flow down pipe 9. The upper plate 18a "may be inclined in the longitudinal direction so that the height of the opening 16 at the other end is increased.

  According to the form of FIG. 5, as in the case of the form of FIGS. 1 to 3, the medium stagnant portion X (FIG. 12) can be effectively solved.

  The present inventors conducted an experiment to observe the state of fluidized bed formation and the state of sand flow into the duct 5 in the apparatus of FIG. 5 using sand mixed with colored sand as in the conventional apparatus. The sand can effectively flow through the inside of the medium guide passages 17 on both sides, thereby preventing the problem that the medium stagnation part X of the horizontal movement of the fluidized medium occurs in the fluidized bed furnace 3. did it.

  As described above, also in the embodiment of FIG. 5, the fluidized medium flows substantially uniformly inside the fluidized bed furnace 3, and the heat exchange efficiency by the steam heat transfer tube 4 can be improved. The extraction temperature of the steam in the steam heat transfer tube 4 can be effectively increased.

  6 and 7 show another embodiment of the present invention applied to the fluidized bed furnace 3 by the gasifier 3B shown in FIG. The fluidized bed furnace 3 by the gasifier 3B of FIGS. 6 and 7 takes out the raw material supply pipe 19 provided on the side close to the medium flow pipe 9 for supplying raw materials such as coal and biomass, and takes out the gasification gas. And a gas extraction pipe 20 provided on the side close to the duct 5, and a decomposition promoting gas such as steam B for accelerating the decomposition of the raw material is supplied from the dispersion plate 10 below the gasifier 3B. The fluidized bed 21 is formed.

  In the form of FIGS. 6 and 7, as shown in FIG. 10, the fluid medium supplied to one side in the fluidized bed furnace 3 by the medium flow down tube 9 is moved to the duct 5 on the other side. The medium stagnation part X on both sides in the width direction of the fluidized bed furnace 3 where the horizontal movement is stagnant has an opening 15 at one end near the medium flow down tube 9 and an opening 16 at the other end far from the medium flow section. A medium guide path 17 that covers the bottom of the layer furnace 3 in a tunnel shape is formed by a partition plate 18.

  At this time, as shown in FIG. 12, when the medium stagnation part X occurs on both sides in the width direction due to the configuration of the fluidized bed furnace 3, the medium stagnation part X on both sides in the width direction is similar to FIG. Thus, the medium guide path 17 can be formed by the partition plate 18.

  According to the form of FIG. 6 and FIG. 7, since the fluid medium flows substantially uniformly inside the fluidized bed furnace 3 by the medium guiding path 17, it is supplied from the raw material supply port 19 to the inside of the gasifier 3 </ b> B. Raw materials such as coal and biomass are decomposed by being uniformly heated in the fluidized bed 21 together with a decomposition promoting gas such as steam B, and the generated gasification gas is led out from the generated gas outlet 20 to the outside. Supplied to the intended use location. At this time, since the temperature of the fluidized bed 21 in the gasifier 3B is maintained substantially uniform by the installation of the medium guiding path 17, the gasification reaction of the raw material can be promoted to improve the gasification efficiency.

  In addition, the fluidized bed furnace of the medium circulation facility of the present invention is not limited to the above illustrated example, and the medium guiding path is for a medium stagnation part that may occur inside the fluidized bed furnace. It is only necessary to provide an opening at one end close to the medium flow down pipe and an opening at the other end far from the medium flow pipe so as to be provided along the direction in which the flow medium is desired to move. Of course, the present invention is not limited, and various modifications can be made without departing from the scope of the present invention.

It is a cutting top view of a fluidized bed furnace as a boiler apparatus which is an example of an embodiment which carries out the present invention. It is the II-II direction sectional drawing of FIG. It is the III-III direction sectional drawing of FIG. It is sectional drawing which shows the other example of the partition plate of FIG. It is a cutting | disconnection top view of the fluidized-bed furnace which is another form example which implements this invention. It is a cutting top view of a fluidized bed furnace as a gasifier which is an example of an embodiment which carries out the present invention. It is a VII-VII direction sectional view of Drawing 6. 1 is an overall schematic side view of a conventional circulating fluidized bed boiler. It is a perspective view which shows an example of the conventional fluidized bed furnace. FIG. 8 is a cut plan view of the fluidized bed furnace of FIG. 7. It is a perspective view which shows the other example of the conventional fluidized bed furnace. FIG. 10 is a cut plan view of the fluidized bed furnace of FIG. 9. It is a perspective view in the case of the gasifier which shows the other example of the conventional fluidized bed furnace, and has a raw material supply port and a production | generation gas outlet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Combustion furnace 2 Medium separation apparatus 3 Fluidized bed furnace 3A Boiler apparatus 3B Gasification apparatus 4 Steam heat transfer pipe 5 Duct 9 Medium flow-down pipe 15,16 Opening 17 Medium induction path 18 Partition plate 18a 'Upper plate 18a "Upper plate 19 Raw material supply Port 20 Generated gas outlet X Medium stagnant part

Claims (5)

  The flue gas from the combustion furnace is guided to a medium separator to separate the fluidized medium, and the separated fluidized medium is supplied to one side of the fluidized bed furnace through a medium flow pipe to form a fluidized bed by the fluidized medium. The fluidized bed furnace of a medium circulation facility in which the fluidized medium is returned to the combustion furnace by a duct provided on the other side of the fluidized bed furnace, and is supplied to one side of the fluidized bed furnace by the medium flow pipe. One end on the side close to the medium flow pipe and the other end on the far side open in the medium stagnation part where the horizontal movement of the fluid medium stagnate on the way to the duct on the other side, and tunnels the bottom of the fluidized bed furnace. A fluidized bed furnace for a medium circulation facility, characterized in that a medium guiding path covering the shape is formed by a partition plate.   The fluidized bed furnace for a medium circulation facility according to claim 1, wherein the fluidized bed furnace is a boiler device that heats a steam heat transfer tube with a fluidized medium.   The fluidized bed furnace for a medium circulation facility according to claim 1, wherein the fluidized bed furnace is a gasification apparatus that includes a raw material supply port and a product gas outlet and performs gasification of the raw material with a fluid medium.   The partition plate forming the medium guiding path is characterized in that the upper plate has a height at the other end far from the height at one end near the medium flow down pipe. The fluidized bed furnace of the medium circulation facility according to any one of 3. The partition plate that forms the medium guiding path is an inclined plate in which an upper plate is formed in a descending gradient with one side in the width direction facing the inside of the fluidized bed furnace. A fluidized bed furnace of the medium circulation facility described in 1.

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