JP4138716B2 - Drying apparatus and drying method - Google Patents

Description

  The present invention relates to a drying apparatus and a drying method for drying an object to be dried such as a water-containing solid, and in particular, drying dehydrated cakes and the like discharged from water and sewage systems, rural village drainage treatment facilities, human waste treatment facilities, industrial drainage facilities, and the like. The present invention relates to a drying apparatus and a drying method suitable for the above.

Conventionally, various types of dryers have been proposed as drying devices for drying water-containing solids such as dehydrated cakes. Dryers are classified into heating methods, such as hot air heating dryers, steam indirect heating dryers, and so on. There are dryers. Here, the warm air heating type dryer is to dry the object to be dried by contacting the object to be dried with hot air (hot air), and the steam indirect heating type dryer passes the high temperature steam to the outside of the jacket through which the object to be dried passes. The object to be dried is heated indirectly to be dried. The rotary dryer dries while rotating the material to be dried in a cylinder or the like, and the agitation dryer dries the material to be dried mechanically or with hot air. Is to dry by bringing hot air or the like into contact with an object to be dried that is placed on a band such as a wire mesh having air permeability.
Chemical Engineering Handbook Revised 5th Edition Chemical Engineering Association Maruzen Co., Ltd. p. 663-692

  However, hot air heating type dryers and steam heating type dryers have a high thermal efficiency by exhausting wet high-temperature air in the dryer to the outside or draining steam pipe drain (condensate water) of 100 ° C or higher. There was a problem of causing a drop. In addition, the rotary dryer and the agitation dryer have problems that kneading occurs when a material to be dried having a high water content is added, and dust is generated from the material to be dried after drying. On the other hand, although the ventilation band type dryer has no kneading of the materials to be dried and generation of dust, the material to be dried was put on the band from a high position above the dryer and recovered from below. There is a problem that it is necessary to separately install a conveying means for charging / recovering the material to be dried, which requires large equipment and high operating costs.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a drying apparatus and a drying method capable of efficiently drying an object to be dried with a simple and small-scale configuration. .

The invention according to claim 1 for solving the above-mounting have a communication unit which returns from the upper end to the lower end of the spiral portion to move upward in a spiral shape on the upper end from the lower end and the spiral portion An endlessly configured net conveyor having a placement surface formed in a mesh shape, a drying chamber surrounding at least the spiral portion of the net conveyor, and dehumidified hot air supplied to the upper portion of the drying chamber downward A blower forcibly flowing down, a dried product supply unit for supplying a dried product to the net conveyor at the lower end of the spiral part of the net conveyor, and drying from above the net conveyor at the upper end of the spiral part The present invention is characterized in that a to-be-dried object collecting unit for collecting the to-be-dried object is provided.

  According to a second aspect of the present invention, in the drying apparatus according to the first aspect, the to-be-dried object supply unit is configured to continuously supply the to-be-dried object onto the net conveyor, and the to-be-dried object recovery unit is the drying It is characterized by being comprised so that the to-be-dried material may be continuously collect | recovered from a net conveyor.

The invention according to claim 3 is the drying apparatus according to claim 1 or 2, further comprising a heat pump, wherein the air discharged from the drying chamber is introduced into the heat exchange chamber of the heat pump to dehumidify the dehumidified air. Is configured to be supplied to the upper part of the drying chamber .

  According to a fourth aspect of the present invention, in the drying apparatus according to any one of the first to third aspects, at least the heat exchanger of the heat pump is disposed in the heat exchange chamber, and the drying chamber and the heat exchange chamber are air. It is characterized by communication through a circulation path.

  According to a fifth aspect of the present invention, in the drying apparatus according to the third or fourth aspect of the present invention, a moisture recovery mechanism that recovers moisture condensed from the air dehumidified by the heat pump is provided.

  According to a sixth aspect of the present invention, in the drying apparatus according to the fourth or fifth aspect, the drying chamber is provided with an air replacement mechanism that replaces part of the air in the drying chamber with the outside air.

The invention according to claim 7, the upper end portion spirally upward movement to spiral portion and said spiral portion communicating portion have a mounting surface reticulated to return to the lower portion from the upper end from the lower end portion supplying material to be dried in the lower end of the spiral portion of the net conveyor constructed in the formed endless on the net conveyor, the material to be dried to rise moving the spiral portion dehumidified by the heat pump spiral It is dried by contact with the air supplied to the upper part of the section and forced to flow downward by a blower , and the dried material is collected from the net conveyor at the upper end of the spiral section and contributes to the drying. the moist air dehumidified back to the heat pump, and wherein the Rukoto into contact with air again the material to be dried which dampening該除.

The invention described in claim 8 is characterized in that, in the drying method according to claim 7, supply of the material to be dried onto the net conveyor and recovery of the material to be dried from the net conveyor are continuously performed. .

According to the first aspect of the present invention, the dehumidified hot air supplied to the upper part of the drying chamber is forced to flow downward by a blower, and the drying target is moved up and down the spiral portion of the net conveyor. Since the material to be dried is brought into contact with an object and dried, the material to be dried can be efficiently dried. In addition, the dried product supply unit that supplies the dried product to the net conveyor at the lower end of the spiral portion of the net conveyor, and the dried product that is dried from the net conveyor at the upper end of the spiral portion is collected. Since the to-be-dried object recovery unit is provided, the to-be-dried part can be introduced from a low position of the spiral portion and recovered from a high position, so that a mechanism for transporting the to-be-dried object to a high position in advance becomes unnecessary. The structure is simple and compact. In addition, the energy required to transport the object to be dried can be kept low.

  According to the second aspect of the present invention, the to-be-dried object supply unit is configured to continuously supply the to-be-dried object onto the net conveyor, and the to-be-dried object collecting unit supplies the dried object to be dried on the net conveyor. Therefore, it is possible to efficiently dry the object to be dried and uniformly dry the object to be dried.

According to the third aspect of the present invention, a heat pump is provided, and the air discharged from the drying chamber is introduced into the heat exchange chamber of the heat pump for dehumidification, and the dehumidified air is supplied to the upper portion of the drying chamber. since it is configured, without discharging the moist hot air evaporated water to the outside, it can be reused heat the hot air has. Thereby, a to-be-dried object can be dried efficiently and the fall of the thermal efficiency of a drying apparatus can be prevented.

  According to the fourth aspect of the present invention, at least the heat exchanger of the heat pump is disposed in the heat exchange chamber, and the drying chamber and the heat exchange chamber are communicated with each other through the air circulation path. It can prevent that the heat which air has is discharged | emitted outside. Therefore, the material to be dried can be efficiently dried, and a decrease in the thermal efficiency of the drying device can be prevented.

  According to the fifth aspect of the present invention, since the moisture collecting mechanism for collecting the moisture condensed from the air dehumidified by the heat pump is provided, the heat of the moisture can be collected without being discharged to the outside. Therefore, the material to be dried can be efficiently dried, and a decrease in the thermal efficiency of the drying device can be prevented.

  According to the invention described in claim 6, since the air exchange mechanism for exchanging a part of the air in the drying chamber with the outside air is provided in the drying chamber, the odor generated during the drying is discharged to the outside of the drying chamber. It is possible to prevent corrosion in the apparatus.

According to the seventh aspect of the present invention, the object to be dried that moves up and down the spiral part is dehumidified by the heat pump, supplied to the upper part of the spiral part, and forced to flow downward by the blower and dried. Therefore, the material to be dried can be efficiently dried. Further, the material to be dried is supplied to the net conveyor at the lower end of the spiral portion of the net conveyor , and the material to be dried is recovered from the net conveyor at the upper end of the spiral portion. because with a part, to put the drying section from a low position of the helical portion, it is possible to recover in high position, that Do unnecessary power for conveying the pre-high position material to be dried. In addition, since the humid air that contributed to drying is returned to the heat pump and the dehumidified air is brought into contact with the object to be dried again, the hot air moistened with evaporated water is not discharged to the outside, and the hot air is discharged. Can be reused and drying can be performed efficiently.

  According to the invention described in claim 8, since the supply of the material to be dried on the net conveyor and the recovery of the material to be dried from the net conveyor are continuously performed, the drying process of the material to be dried is efficiently performed. It becomes possible to uniformly dry the object to be dried.

  Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a drying apparatus according to an embodiment of the present invention. Moreover, FIG. 2 is a figure which shows the structure of the net conveyor which a drying apparatus comprises, the figure (a) is a schematic side view of the net conveyor 10, and the figure (b) is the schematic plan view. As shown in FIG. 2, the net conveyor 10 is configured by forming a circulation path with an endless net belt 11 having a mounting surface 11a formed of a net-like net or the like. The circulation path of the net belt 11 includes a spiral portion 13 disposed around the rotating shaft 12 standing in the vertical direction and spirally wound with the placement surface 11a of the net belt 11 facing upward. The upper and lower portions 14 and 15 of the spiral portion 13 communicate with each other, and a communication portion 16 is provided. The communication part 16 extends in the horizontal direction from the upper part 14 of the spiral part 13, is folded back by the roll member 17, and is turned upside down so that the placement surface 11 a faces downward, and further, the roll member 18 on the front side faces vertically downward. The mounting surface 11a is bent sideways and is bent in a substantially horizontal direction by the lower roll member 19 and connected to the roll member 20 at the lower portion 15 of the spiral portion 13.

  In the net conveyor 10, the net belt 11 moves the spiral portion 13 from the lower portion 15 toward the upper portion 14 by driving the rotary shaft 12 and the roll members 17 to 20, and from the upper portion 14 to the lower portion 15 of the spiral portion 13. It goes around by returning through the communication part 16. The configuration of the net conveyor 10 is not limited to the configuration shown in the drawing as long as it can perform the operation of moving the net belt 11. For example, the net conveyor 10 includes a plurality of spiral portions 13 instead of one. The detailed configuration is not limited to the illustrated one.

  In addition, as shown in FIG. 2A, the drying device includes a supply unit 21 that supplies an object to be dried such as a dehydrated cake on the net belt 11 in the lower part 15 of the spiral part 13, and an upper part of the spiral part 13. 14 includes a transporting mechanism having a recovery unit 22 for recovering the material to be dried placed on the 14 net belts 11. The supply unit 21 is, for example, a screw-type supply device that supplies an object to be dried toward the placement surface 11a of the net belt 11, and the collection unit 22 is below the roll member 17 where the net belt 11 is folded, This is a collection port that opens to a drop position where an object to be dried placed on the net belt 11 falls. The transport mechanism can continuously supply the material to be dried onto the net belt 11 by the supply unit 21, and can continuously collect the material to be dried on the net belt 11 through the recovery port 22. In addition to this configuration, the supply unit 21 and the recovery unit 22 have a mechanism that can continuously supply an object to be dried to the lower part 15 of the spiral part 13 and collect an object to be dried from the upper part 14 of the spiral part 13. Anything provided is acceptable. The supply unit 21 is preferably configured to be able to uniformly supply the material to be dried onto the net belt 11. For example, the supply amount of the material to be dried is constant, and the material to be dried supplied onto the net belt 11. As long as the screw-type supply device 21 has a shape and a configuration in which are uniformly arranged. As this supply part 21, supply apparatuses, such as a table type, a bucket conveyor type, a rotary drum type, and a vibration type, other than said screw type supply apparatus can be used. Further, if necessary, a molding device may be installed, and the material to be dried may be molded by the molding device and then supplied onto the net belt 11.

  Next, the overall configuration of the drying apparatus will be described with reference to FIG. 1. In the drying apparatus, at least the spiral portion 13 of the net conveyor 10 is housed and arranged in a drying chamber 30 formed in a box shape. As long as the drying chamber 30 can accommodate the spiral portion 13 of the net conveyor 10, the material and structure thereof are not limited. Also, the drying chamber 30 is provided with an outside air introduction duct 31 that exhausts the internal air to the outside and introduces outside air to ventilate the drying chamber. The drying chamber 30 preferably has a heat insulating property.

  On the other hand, a box-shaped heat exchange chamber 40 is installed next to the drying chamber 30, and heat composed of a heat absorption part (evaporator) 51 and a heat radiation part (condenser) 52 of the heat pump 50 is placed in the heat exchange room 40. An exchanger is arranged and configured to dehumidify the air introduced into the heat exchange chamber 40. The drying chamber 30 and the heat exchange chamber 40 are communicated with each other by two air circulation ducts 32 and 33. The air circulation ducts 32 and 33 are preferably heat-insulating and air-tight and communicate with the inside of the drying chamber 30 and the heat exchange chamber 40, and other materials and shapes are not limited.

  In the heat pump 50, the refrigerant is circulated in the interior by being vaporized by the expansion valve 53, vaporized by the heat absorbing unit 51, compressed by the compressor 54, and led to the heat radiating unit 52 to condense. The refrigerant exchanges heat with the air in the heat exchange chamber 40. That is, moisture contained in the air in the heat exchange chamber 40 is condensed by the heat absorption part 51, and further, the air in the heat exchange chamber 40 is heated by the heat dissipation part 52. Thereby, dehumidification of the air in the heat exchange chamber 40 is performed. It is preferable to select a heat pump 50 having an appropriate configuration and output from the effective area of the net conveyor 10, that is, the amount of the object to be dried and the drying speed of the object to be dried.

  The air circulation ducts 32 and 33 are provided with a circulation fan 34 for sending the internal air in a certain direction (direction indicated by an arrow in the figure). Thereby, air is introduced from the drying chamber 30 through the air circulation duct 33 to the heat exchange chamber 40, and an air circulation path is formed through which the air is returned to the drying chamber 30 through the air circulation duct 32. It is desirable that the flow velocity of the air flowing through the air circulation ducts 32 and 33 is, for example, 15 m / sec or less. The circulation blower 34 can also be installed in the heat exchange chamber 40 and the drying chamber 30 as needed to send air into the air circulation ducts 32 and 33, and further promote air circulation. . FIG. 1 shows a state where it is also installed in the drying chamber 30.

  In the drying chamber 30, a blower 35 that blows the dried air introduced from the heat exchange chamber 40 onto the object to be dried on the net belt 11 is provided. The blower 35 is provided to effectively bring the dried air into contact with the object to be dried. However, if the air volume is reduced too much, the drying air cannot sufficiently contact the object to be dried and the drying speed decreases. On the other hand, if the air volume is increased too much, there is a problem that the power required for the blower 35 increases and the material to be dried moves by the wind. Therefore, the thing which can be drive | operated by the air quantity of the grade in which the wind speed in the drying chamber 30 is maintained at 0.1 m / sec-15 m / sec, More preferably, 0.3 m / sec-10 m / sec is good.

  A procedure for drying an object to be dried by the drying apparatus having the above configuration will be described. With the net conveyor 10 moved, the material to be dried is supplied from the supply unit 21 onto the net belt 11 at the lower part 15 of the spiral portion 13. The object to be dried moves upward while turning the spiral portion 13 by the movement of the net belt 11.

  On the other hand, the air dehumidified by the heat pump 50 in the heat exchange chamber 40 is sent into the drying chamber 30 through the air circulation duct 32 by the circulation fan 34. The dehumidified air sent into the drying chamber 30 is blown by the blower 35 onto the material to be dried that moves up the spiral portion 13 of the net conveyor 10. Thereby, the water | moisture content of to-be-dried material evaporates and dries. The evaporated moisture diffuses into the air around the object to be dried, and the air in the drying chamber 30 becomes moist air. The moist air is sent to the air circulation duct 33 by the circulation fan 34 installed in the drying chamber 30 and returned to the heat exchange chamber 40. The moist air is dehumidified by the heat pump 50 in the heat exchange chamber 40 and sent again from the air circulation duct 32 to the drying chamber 30. Condensed water generated when air is dehumidified by the heat pump 50 is collected by a condensed water discharge valve 41 provided at the bottom of the heat exchange chamber 40. By condensing moisture in the air, latent heat of vaporization is also recovered.

  It is desirable that the air flow rate of the circulation blower 34 is 10 times / h to 150 times / h, preferably 20 times / h to 100 times / h, depending on the ventilation frequency of the drying chamber 30. If the air flow rate of the circulation fan 34 is too small, the relative humidity in the drying chamber 30 increases and the drying speed of the object to be dried decreases. On the other hand, if the air flow rate is excessive, the dehumidification efficiency of the heat pump 50 decreases and the necessary power Will increase. Therefore, it is preferable to set the ventilation frequency so as to be an optimum value in accordance with the drying speed of the object to be dried.

  The object to be dried is dried while moving through the spiral part 13, and the object to be dried that has reached the upper part 14 of the spiral part 13 falls from the net belt 11 when the net belt 11 is folded back by the roll member 17. And it collect | recovers by the collection | recovery part 22 opened below it.

  In this drying apparatus, the object to be dried is supplied from the lower position (lower part 15) of the spiral portion 13 and recovered at the higher position (upper part 14). Is eliminated, and the structure of the transport mechanism is simple and compact. In addition, the energy required to transport the object to be dried can be kept low.

  In the above drying step, the outside air introduction duct 31 of the drying chamber 30 is opened, so that a part of the air in the drying chamber 30 can be replaced with the outside air for ventilation. Thereby, the odor etc. which generate | occur | produced from the to-be-dried object can be exhausted out of the drying chamber 30. If the ventilation rate is too small, the concentration of the corrosive gas generated from the object to be dried in the drying chamber 30 increases, and the inner wall surface of the drying chamber 30 and the net conveyor 10 are corroded. The heat dissipation increases and the thermal efficiency decreases. Therefore, the ventilation rate is preferably 0.1 times / h to 3 times / h, preferably 0.2 times / h to 1 time / h in terms of the number of ventilations. In addition, when the drying process is performed in a so-called continuous manner in which the material to be dried is continuously supplied, the outside air is introduced by opening the drying chamber 30 along with the supply and recovery of the material to be dried. It does not have to be installed and ventilated.

  In this drying apparatus, the air dehumidified by the heat pump 50 is brought into contact with the object to be dried to evaporate the moisture from the object to be dried, and the air moistened with the evaporated water is collected and introduced into the heat pump 50 for dehumidification, Since the dehumidified air is brought into contact with the object to be dried again, the heat of the high-temperature air can be recovered by the heat pump 50 without discharging the high-temperature air wet with the evaporated water to the outside. Thereby, the fall of the thermal efficiency of a drying apparatus can be prevented, and to-be-dried material can be dried efficiently.

  Further, since the air is circulated inside the drying chamber 30 and the heat exchange chamber 40 and the air circulation ducts 32 and 33, it is possible to prevent the heat of the circulating air from being discharged outside the apparatus. Accordingly, it is possible to prevent a decrease in the thermal efficiency of the drying apparatus, and to efficiently dry the object to be dried. Furthermore, since the condensed water generated when the air is dehumidified by the heat pump 50 is recovered by the condensed water discharge valve 41 provided at the bottom of the heat exchange chamber 40, the heat of the condensed water is not discharged to the outside. It can be recovered.

  In addition, since the object to be dried is placed on the net belt 11 and air dried by the blower 35 is blown and dried, not only can the object to be dried be efficiently dried, Drying can be performed so that generation of dust does not occur.

The result of having performed the drying process with the drying apparatus having the above configuration will be described. FIG. 3 is a diagram illustrating an example of a result of performing a drying process. Here, the net conveyor 10 of the drying device has an effective area of 8.0 m ² , the drying chamber 30 has an effective volume of 12.0 m ³ , the number of ventilations: 52 times / h, and the wind speed of the drying chamber: 1.2 m / sec. The heat pump 50 has a compressor nominal output of 2.2 kW. The dehydrated cake as the material to be dried was inorganic and used by pulverizing an ignition loss of 18% -DS and silica: 32% to a size of about 5 mm.

  As a result of continuous drying experiments under the conditions of dehydrated cake supply rate: 15 kg / h, drying time: 3.0 h, the drying chamber average temperature was 53 ° C., the drying chamber average humidity was 55%, and the moisture content of the dehydrated cake was 65. It was possible to dry from 3% to 34.3%. The power consumption of the compressor 54 was 6.6 kWh in 3 hours. The amount of evaporated water was 21.2 kg. When the latent heat of evaporation was 0.66 kWh, the amount of evaporated water was 14 kWh, which was a calculation equivalent to 2.1 times the power consumption. Moreover, the dried cake after the drying step maintained the same shape as the dehydrated cake, and no dust was generated.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Is possible. Note that any shape or material not directly described in the specification and drawings is within the scope of the technical idea of the present invention as long as the effects and advantages of the present invention are achieved.

  For example, in the said embodiment, the drying chamber 30 which accommodates the helical part 13 of the net conveyor 10, the heat absorption part 51 of the heat pump 50, and the heat exchange chamber 40 which accommodates the heat dissipation part 52 are installed separately, and these are circulated by air. Although the configuration in which the ducts 32 and 33 communicate with each other is shown, when the drying chamber 30 and the heat exchange chamber 40 are installed adjacent to each other, or when the heat exchange chamber 40 is installed in the drying chamber 30, an air circulation duct is used. It is also possible to form an air circulation path without providing 32 and 33.

It is a figure which shows schematic structure of the drying apparatus concerning one Embodiment of this invention. It is a figure which shows the structure of the net conveyor which a drying apparatus comprises, the figure (a) is a schematic side view of a net conveyor, and the figure (b) is the schematic plan view. It is a figure which shows an example of the result of having performed the drying process with the drying apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Net conveyor 11 Net belt 11a Mounting surface 12 Rotating shaft 13 Spiral part 14 Upper part 15 Lower part 16 Communication part 17 Roll member 18 Roll member 19 Roll member 20 Roll member 21 Screw type supply apparatus (supply part)
22 Collection port (collection unit)
DESCRIPTION OF SYMBOLS 30 Drying chamber 31 Outside air introduction duct 32 Air circulation duct 33 Air circulation duct 34 Circulation fan 35 Blower 40 Heat exchange chamber 41 Condensate drain valve 50 Heat pump 51 Heat absorption part (evaporator)
52 Heat dissipation part (condenser)
53 Expansion valve 54 Compressor

Claims (8)

It has a spiral part that moves up and down spirally from the lower end part to the upper end part, and a communicating part that returns from the upper end part of the spiral part to the lower end part, and the mounting surface is formed in an endless shape. A net conveyor, a drying chamber that surrounds at least the spiral portion of the net conveyor, a blower that forcibly flows down the dehumidified warm air supplied to the upper portion of the drying chamber, and a spiral portion of the net conveyor A to-be-dried object supply unit for supplying an object to be dried to the net conveyor at a lower end of the object, and a to-be-dried object recovery unit for recovering an object to be dried from the net conveyor at the upper end of the spiral part. A drying apparatus characterized by that. The drying apparatus according to claim 1, wherein
The to-be-dried material supply unit is configured to continuously supply the to-be-dried material on the net conveyor, and the to-be-dried material collecting unit is configured to continuously collect the dried to-be-dried material from the net conveyor. The drying apparatus characterized by the above-mentioned. The drying apparatus according to claim 1 or 2,
A drying apparatus comprising a heat pump, wherein the air discharged from the drying chamber is introduced into the heat exchange chamber of the heat pump to dehumidify, and the dehumidified air is supplied to an upper portion of the drying chamber. . The drying apparatus according to any one of claims 1 to 3,
At least a heat exchanger of the heat pump is disposed in a heat exchange chamber, and the drying chamber and the heat exchange chamber communicate with each other through an air circulation path. The drying apparatus according to claim 3 or 4,
A drying apparatus comprising a moisture recovery mechanism for recovering moisture condensed from air dehumidified by the heat pump. In the drying apparatus according to claim 4 or 5,
The drying apparatus, wherein the drying chamber is provided with an air exchange mechanism for exchanging a part of the air in the drying chamber with outside air. Yes to mounting surface communicating portion which returns from the upper end to the lower end of the spiral portion to move upward in a spiral shape and the helical portion is constituted in an endless shape which is formed in a mesh shape in the upper portion from the lower end The material to be dried is supplied onto the net conveyor at the lower end of the spiral portion of the net conveyor, and the material to be dried moving up the spiral portion is dehumidified by a heat pump and supplied to the upper portion of the spiral portion and forced by a blower. The dried material is brought into contact with the air flowing down downward , and the dried material is recovered from the net conveyor at the upper end of the spiral portion, and the moist air contributing to the drying is returned to the heat pump. dehumidified Te, drying and wherein the Rukoto contacting again the material to be dried the該除dampening air. The drying method according to claim 7,
A drying method comprising continuously supplying a material to be dried onto the net conveyor and collecting the material to be dried from the net conveyor.

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