JP2005207627A - Flying ash treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flying ash treatment deice less in energy consumption, free from overheat, superior in practical use and smaller for efficiently removing unburnt carbon from flying ashes in a relatively short time. <P>SOLUTION: The flying ash treatment device 1 comprises a rotary kiln 2 as a cylindrical rotary furnace, a screw conveyor 3 for loading the flying ashes FA1 containing the unburnt carbon into the rotary kiln 2, a supplementary firing burner 4, an air suction pipe 5 for supplying air into the rotary kiln 2, a shell furnace 6a and a burner 6b, a shell furnace 7a and a blower 7b, a cooling water nozzle 8a and a water sump 8b, a flying ash discharge port 9 for discharging the flying ashes FA2 after removing the unburnt carbon therefrom, and an exhaust pipe 10 for exhausting exhaust gas from the rotary kiln 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fly ash treatment apparatus having a function of removing carbon (unburned carbon) contained in fly ash.

  Various technologies for removing unburned carbon contained in fly ash recovered from exhaust gas discharged from pulverized coal combustion boilers installed in thermal power plants have been developed. However, as a technique related to the present application, there is a fly ash treatment apparatus using a rotary kiln (see Patent Documents 1 and 2).

  The fly ash treatment apparatus described in Patent Document 1 supplies fly ash from an upper end opening of an externally heated rotary kiln installed at an inclination, and by heating the fly ash to 500 ° C. to 1100 ° C. in the rotary kiln, It burns and removes unburned carbon in fly ash.

  The fly ash treatment apparatus described in Patent Document 2 supplies fly ash into an externally heated rotary kiln containing a stirring plate and a massive medium, and while mixing the fly ash and the massive medium, It burns and removes unburned carbon in fly ash.

Japanese Patent Laid-Open No. 06-134435 (page 2-4) Japanese Patent Laid-Open No. 07-19440 (page 2-4)

  In the case of the fly ash treatment apparatus described in Patent Document 1, the temperature in the rotary kiln becomes substantially uniform, and therefore the position where the self-combustion start temperature of the unburned carbon contained in the fly ash introduced into the kiln reaches 600 ° C. It is not fixed, it is difficult to control the temperature distribution in the axial direction of the kiln, the thermal efficiency tends to deteriorate, and the size in the axial direction tends to increase.

  Heating is required up to the fly ash self-combustion start temperature of 600 ° C., but if this temperature is exceeded, the unburned carbon will burn and become overheated, and it is predicted that it will exceed 950 ° C. However, since the fly ash treatment apparatus described in Patent Document 1 is not equipped with an overheat prevention means such as a cooling means, general stainless steel (such as SUS310S) cannot withstand high heat. For this reason, it is necessary to comprise a rotary kiln with special heat-resistant materials, such as ceramics, and lacks practicality.

  Also, in the fly ash treatment apparatus described in Patent Document 2, although the external heating means is provided but the cooling means is not provided, unburned carbon in the fly ash introduced into the rotary kiln is burned. It is expected that the temperature will rise above 950 ° C. when starting. For this reason, the same problem as the fly ash treatment apparatus described in Patent Document 1 described above may occur.

  The problem to be solved by the present invention is that unburned carbon contained in fly ash can be efficiently removed in a relatively short time, consumes little energy, does not cause overheating, has excellent practicality, and is an apparatus An object of the present invention is to provide a fly ash treatment apparatus that can be downsized.

  The fly ash treatment apparatus of the present invention includes a rotary kiln arranged so that the axis is downwardly inclined from the start end to the end, a fly ash charging means provided at the start end of the rotary kiln, an auxiliary heating means, Air blowing path, external heating type heating means, external cooling type air cooling means and external cooling type water cooling means arranged in series from the start end to the end of the rotary kiln, and fly ash provided at the end of the rotary kiln An exhaust port and an exhaust path are provided. Here, the rotary kiln refers to a cylindrical rotary furnace with a gradient in which a raw material is charged from one end and a workpiece can be continuously taken out from the other end.

  The fly ash containing unburned carbon introduced from the fly ash charging means into the rotary kiln is heated by the auxiliary heating means and the external heating means while being supplied with air from the air blowing path, and thus proceeds in the rotary kiln. While being heated, the unburned carbon starts burning when the temperature reaches a self-combustion temperature of 600 ° C. Then, after the start of combustion, the inside of the rotary kiln moves toward the area where the external cooling type air cooling means is arranged while continuing to burn the unburned carbon by its own heat generation.

  The heating method of such a process is a parallel flow in which a heated gas and an object to be heated (fly ash) flow in parallel, and the temperature of fly ash containing unburned carbon that travels in the rotary kiln increases, The temperature of the heated gas gradually decreases. And since the fly ash temperature is the lowest in the rotary kiln start end part with the highest heating gas temperature, the temperature of the rotary kiln main body is substantially the average value of the heating gas temperature and the fly ash temperature, and does not become high. For this reason, a rotary kiln can be comprised with a general stainless steel material (SUS310S etc.), and sufficient durability is acquired.

  The fly ash that has reached the region where the external cooling type air cooling means is disposed is the heat generated by the combustion of unburned carbon and the cooling action by the external cooling type air cooling means, while maintaining the temperature in the rotary kiln while maintaining 600 to 900 ° C. Is moved toward the area where the external cooling type water cooling means is disposed. Therefore, in this process, the combustion of unburned carbon proceeds, and most of the combustion is removed. That is, in this process, the combustion of unburned carbon proceeds only by cooling without supplying heat from the outside. In this step, if natural cooling is left without providing a cooling means, the heat generated by the combustion of unburned carbon exceeds 950 ° C., so an external cooling type air cooling means is necessary.

  The fly ash that has reached the area where the external cooling type water cooling means is arranged is cooled to about 200 ° C. by the external cooling type water cooling means while moving in the rotary kiln toward the end part, and the fly ash provided at the end part of the rotary kiln is provided. It is discharged from the ash outlet. The unburned carbon remaining in the discharged fly ash is about 0.1% to 0.5%.

  On the other hand, the air supplied into the rotary kiln from the air blowing path and the gas generated in the rotary kiln due to the combustion reaction of unburned carbon, etc., move toward the end in the rotary kiln, and the exhaust path in the end Is discharged as exhaust gas. The discharged exhaust gas is detoxified through a powder recovery process using a cyclone, a combustion process of unburned components such as CO using a secondary combustion means, a cooling process using a cooling means, and a dust removal process using a bag filter, etc. It is released inside.

  Thus, the unburned carbon in the fly ash introduced into the rotary kiln starts self-combustion when it reaches 600 ° C. in the heating region by the auxiliary heating means and the external heating type heating means. By moving in the high temperature holding region due to the interaction between the carbon combustion heat and the external cooling type air cooling means, the combustion reaction proceeds without heating from the outside. That is, since the combustion of unburned carbon proceeds while moving the fly ash along the heat transfer direction, the unburned carbon contained in the fly ash can be efficiently removed in a relatively short time.

  In addition, since the heat generated by the self-combustion of unburned carbon is cooled by the external cooling type cooling means, there is no risk of overheating, and it is not necessary to supply heat from the outside after the unburned carbon starts self-combustion. Less energy is consumed. Further, since the cooling means is provided, there is no possibility of overheating to a high temperature region exceeding 950 ° C., so that the rotary kiln can be configured with a general material such as a stainless steel material, and the practicality is also excellent. Furthermore, by arranging the external cooling type water cooling means, it becomes possible to cool the fly ash after removing the unburned carbon in a short time, so that the axial length of the rotary kiln can be reduced in size. .

  Here, as the air blowing path, it is desirable to provide an air blowing pipe capable of supplying air into the rotary kiln in the region where the external heating type heating means is arranged. By setting it as such a structure, it becomes possible to supply air to the position where the fly ash introduced into the area | region where the external heating type heating means is arrange | positioned reached self-combustion start temperature 600 degreeC. Therefore, it is not necessary to heat the air, and all of the heating amount by the auxiliary heating means and the external heating type heating means is used for raising the temperature of the fly ash. A combustion area of certain unburned carbon can be made long, and combustion of unburned carbon can be efficiently advanced.

  Here, it is desirable to provide a dam plate protruding in the axial direction on the inner peripheral surface of the rotary kiln, and to provide a through hole in contact with the inner peripheral surface of the rotary kiln in the dam plate. With such a configuration, since the moving speed of fly ash that moves in the rotary kiln toward the end portion is suppressed and the residence time can be increased, it is possible to achieve complete combustion of unburned carbon, and the rotary kiln The size can be reduced. Moreover, since the through-hole of the dam plate is in contact with the inner peripheral surface of the rotary kiln, fly ash that moves along the inner peripheral surface does not remain or accumulate in the dam plate portion.

  In addition, the position where such a dam plate with a through-hole is arranged is the rotary kiln inner peripheral surface at the boundary between the external heating type heating means and the external cooling type air cooling means, the external cooling type air cooling means and the external cooling type water cooling means. The inner peripheral surface of the rotary kiln at the boundary portion, the terminal end of the rotary kiln, and the like are suitable. By arranging the dam plate at such a position, it becomes possible to retain fly ash until the combustion start reaction, combustion reaction, and cooling in the region where each means is arranged is completed properly. Can be burned completely.

  On the other hand, if a shelf-like stirring member is provided on the inner peripheral surface of the rotary kiln, the stirring member rakes up fly ash by the rotation of the rotary kiln and stirs it to drop, so that sufficient oxygen is supplied into the fly ash. become. Therefore, it is possible to rapidly advance the combustion reaction of unburned carbon that is controlled by oxygen diffusion into fly ash, which is extremely effective for removing unburned carbon.

  The position where such a stirring member is provided is preferably the inner peripheral surface of the rotary kiln in the region where the unheated carbon burns, the region where the external heating type heating means is arranged, and the region where the external cooling type air cooling means is arranged. Thus, complete combustion of unburned carbon in fly ash can be achieved. In addition, it is not necessary to arrange | position the said stirring member in the area | region where the preheating area | region until a fly ash reaches 600 degreeC, and the external heating type water cooling means are arrange | positioned.

  In this case, it is desirable to provide a gap between the shelf-like stirring member and the inner peripheral surface of the rotary kiln. As a result, the fly ash scraped up by the stirring member can pass through the gap and drop, and the opportunity (number of times) the fly ash directly contacts the inner peripheral surface of the rotary kiln increases. The conduction efficiency increases, and the heating efficiency and cooling efficiency are improved. Further, it is possible to prevent fly ash from remaining or accumulating near the boundary between the stirring member and the inner peripheral surface of the rotary kiln, thereby reducing the stirring action.

  Moreover, it can also be set as the structure which supplies at least one part of the air heated with the heat which arises in an external heating type heating means and an external cooling type air cooling means to at least one of an air blowing path and an external heating type heating means. With such a configuration, it is possible to supply air at a higher temperature than the outside air to the air blowing path and the external heating type heating means, so that the consumption of heating energy can be reduced.

  Further, as an exhaust path, an exhaust pipe opened in the rotary kiln in the vicinity of the start end of the area where the external cooling type water cooling means is disposed from the terminal end portion of the rotary kiln can be provided. By providing such an exhaust pipe, it is possible to avoid the cooling action by the external cooling water cooling means from reaching the exhaust gas, and the exhaust gas can be discharged while maintaining a high temperature state (preferably about 700 ° C.). It becomes like this. For this reason, in addition to improving the combustion efficiency of CO remaining in the exhaust gas, the combustion removal of unburned carbon contained in the finely divided fly ash accompanying the exhaust gas is also achieved.

  The present invention has the following effects.

(1) A rotary kiln arranged so that its axis is downwardly inclined from the start end to the end, a fly ash charging means, an auxiliary heating means and an air blowing path provided at the start end of the rotary kiln, and a rotary kiln An external heating type heating means, an external cooling type air cooling means and an external cooling type water cooling means arranged in series from the starting end part to the terminal end part, and a fly ash discharge port and an exhaust path provided at the terminal end part of the rotary kiln; The unburned carbon contained in fly ash can be efficiently removed in a relatively short time, with low energy consumption, no risk of overheating, excellent practicality, and downsizing of the device. Is also possible.

(2) By providing an air blowing pipe capable of supplying air into the rotary kiln in the region where the external heating type heating means is disposed as the air blowing path, the fly ash has air at a position where the self-combustion start temperature reaches 600 ° C. Therefore, it is not necessary to heat the air, it is possible to rapidly raise the temperature, and combustion of unburned carbon can be efficiently advanced.

(3) If a dam plate protruding in the axial direction is provided on the inner peripheral surface of the rotary kiln, and a through-hole in contact with the inner peripheral surface of the rotary kiln is provided in this dam plate, unburned fly ash can be avoided while avoiding accumulation and accumulation. Carbon can be burnt completely, and the rotary kiln can be downsized.

(4) If a shelf-shaped stirring member is provided on the inner peripheral surface of the rotary kiln, the stirring member rakes up fly ash by the rotation of the rotary kiln, and stirs it to drop, so that sufficient oxygen is supplied into the fly ash, It is possible to rapidly advance the combustion reaction of unburned carbon, which is extremely effective for removing unburned carbon.

(5) If a gap is provided between the shelf-shaped stirring member and the inner peripheral surface of the rotary kiln, the fly ash that has been scraped up can pass through the gap and drop, and the fly ash directly contacts the inner peripheral surface of the rotary kiln. This increases the chance (number of times) to be conducted and increases the efficiency of conduction between the inner peripheral surface and the heating and cooling efficiency. In addition, fly ash remains near the boundary between the stirring member and the inner peripheral surface of the rotary kiln. It is possible to prevent the stirring action from being reduced due to or accumulation.

(6) If at least a part of the air heated by the heat generated in the external heating type heating means and the external cooling type air cooling means is supplied to at least one of the air blowing path and the external heating type heating means, air having a temperature higher than the outside air is supplied. Since the air can be supplied to the air blowing path and the external heating type heating means, the consumption of heating energy can be reduced.

(7) As the exhaust path, by providing an exhaust pipe which is inserted in the axial direction from the terminal end of the rotary kiln and opened in the rotary kiln in the vicinity of the start end of the area where the external cooling water cooling means is disposed, Since the cooling action from the means to the exhaust gas is avoided and the exhaust gas can be discharged in a high temperature state, the combustion efficiency of CO remaining in the exhaust gas is improved, and it is included in the fine powder fly ash accompanying the exhaust gas Unburnt carbon can be removed by combustion.

  Hereinafter, a fly ash treatment apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a fly ash treatment apparatus according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram showing an exhaust treatment apparatus for treating exhaust gas discharged from the fly ash treatment apparatus shown in FIG. 3 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 4 is a cross-sectional view taken along line BB in FIG. 5 is a partial sectional view showing a dam plate constituting the fly ash treatment apparatus shown in FIG. 1, FIG. 6 is a partial sectional view showing a stirring member constituting the fly ash treatment apparatus shown in FIG. 1, and FIG. 6 is a partially enlarged view of FIG.

  As shown in FIG. 1, the fly ash treatment apparatus 1 of the present embodiment includes a rotary kiln 2 that is a cylindrical rotary furnace arranged such that an axis 2c is inclined downward from a start end 2a toward a end 2b. I have. As shown in FIG. 3, the rotary kiln 2 includes a screw conveyor 3 that is a charging unit for fly ash FA 1 containing unburned carbon, an auxiliary combustion burner 4 that is an auxiliary heating unit, and a rotary kiln 2. An air blowing pipe 5 that is an air blowing path is arranged.

  The air blowing pipe 5 is inserted from the starting end 2a of the rotary kiln 2 along the axial center 2c thereof at a position above the axial center 2c, and is opened toward the inner peripheral surface of the rotary kiln 2 at a portion near the tip. The air blowing hole 5a is provided, and the tip of the air blowing pipe 5 is closed with a partition wall 5b. A blower 16 for sending air into the air blowing pipe 5 is disposed on the proximal end side of the air blowing pipe 5.

  Further, from the start end portion 2a of the rotary kiln 2 toward the end portion 2b, the outer shell furnace 6a and the burner 6b which are external heating type heating means, the outer shell furnace 7a and the blower 7b which are external cooling type air cooling means, and external cooling The cooling water nozzle 8a and the water receiver 8b which are a type | formula water cooling means are arrange | positioned in series. A fly ash discharge port 9 for discharging the fly ash FA2 after the completion of processing and an exhaust pipe 10 serving as an exhaust path are disposed at the end portion 2b of the rotary kiln 2.

  When the fly ash FA1 containing unburned carbon is introduced into the hopper 3a of the screw conveyor 3, the fly ash FA1 is introduced into the rotary kiln 2 by the screw conveyor 3, and in the rotary kiln 2 in the region where the outer shell furnace 6a is disposed, The air is heated by the auxiliary burner 4 and the burner 6b while being supplied with air from the air blowing pipe 5. In this case, as shown in FIG. 4, the high-temperature gas flow generated from the burner 6b is heated while swirling between the outer peripheral surface of the rotary kiln 2 and the outer shell furnace 6a, so that the fly ash FA1 in the rotary kiln 2 is efficiently produced. Can be heated uniformly.

  When the temperature of the fly ash FA1 reaches 600 ° C. which is the self-combustion start temperature by such a heating process, the unburned carbon in the fly ash FA1 starts burning at that point, and thereafter, the unburned carbon is burned by its own combustion heat. While continuing and expanding the combustion of carbon, the rotary kiln 2 moves toward the area where the outer shell furnace 7a and the blower 7b are arranged. In the fly ash treatment apparatus 1 of the present embodiment, the air blowing hole 5a of the air blowing pipe 5 is at a position where air can be blown when the temperature of the fly ash FA1 introduced into the rotary kiln 2 reaches 600 ° C. Is provided.

  The fly ash FA1 that has reached the region where the outer shell furnace 7a and the blower 7b are arranged is controlled by the heat generated by the combustion of unburned carbon and the cooling action by the air flow supplied from the blower 7b in the rotary kiln 2 in this region. Then, while maintaining a high temperature state of about 600 ° C. to 900 ° C. (preferably about 700 ° C. to 800 ° C.), the rotary kiln 2 moves toward the end portion 2b. In this process, the combustion of unburned carbon further proceeds, most of which is burned and removed, and becomes fly ash FA2 after the processing is completed. Moreover, since the rotary kiln 2 in this process is cooled by the air flow supplied from the blower 7b, there is no fear of overheating.

  In the region where the cooling water nozzle 8a and the water receiver 8b are disposed, the rotary kiln 2 is cooled by blowing cooling water from the cooling water nozzle 8a to the outer peripheral surface of the rotary kiln 2. Accordingly, the fly ash FA2 that has reached this region is cooled to about 200 ° C. while moving in the rotary kiln 2 toward the end portion, and then from the fly ash discharge port 9 provided at the end portion 2b of the rotary kiln 2. It is discharged and collected via the hopper 11.

  The cooling water sprayed from the cooling water nozzle 8a onto the outer peripheral surface of the rotary kiln 2 cools the rotary kiln 2 while flowing down along the outer peripheral surface, and then drops and collects in the water receiver 8b. Then, the water is again supplied to the cooling water nozzle 8a and reused as cooling water.

  On the other hand, the air supplied from the air blowing pipe 5 into the rotary kiln 2 and the gas generated in the rotary kiln 2 due to the combustion reaction of unburned carbon move in the rotary kiln 2 from the start end 2a toward the end end 2b. The exhaust gas is exhausted from the exhaust pipe 10 disposed near the end portion 2b.

  The exhaust gas discharged from the exhaust pipe 10 passes through the powder recovery process by the cyclone 13 shown in FIG. 1, and then, as shown in FIG. 2, a secondary combustion tower 14 incorporating a catalytic combustion layer 14a as secondary combustion means. By passing through, unburned components such as CO are burned, and unburned carbon contained in the fine powder fly ash accompanying the exhaust gas is also burned and removed. The exhaust gas that has passed through the secondary combustion tower 14 passes through the gas cooling tower 15 that is a cooling means, is cooled to a predetermined temperature, is further detoxified through a dust removing process by the bag filter 22, and is then released into the atmosphere. Is done.

  In this way, the unburned carbon in the fly ash introduced into the rotary kiln 2 is rapidly heated to 600 ° C. in the heating region by the auxiliary burner 4 and the burner 6 b, and the air blown in when the temperature reaches 600 ° C. After starting combustion, the combustion reaction further proceeds by moving through the high temperature holding region controlled by the interaction between the combustion heat of the unburned carbon and the cooling by the blower 7b.

  That is, since the combustion of the unburned carbon proceeds while moving the fly ash FA1 along the heat moving direction, the unburned carbon contained in the fly ash FA1 can be efficiently removed in a relatively short time. The fly ash FA2 after the unburned carbon is burned and removed in the high temperature holding region is rapidly cooled by passing through the cooling region where the cooling water nozzle 8a is disposed, and then discharged from the fly ash discharge port 9. The

  In the present embodiment, as shown in FIG. 1, the inner peripheral surface of the rotary kiln 2 projects in the direction of the axis 2c at the boundary portion between the outer shell furnaces 6a and 7a and the boundary portion between the outer shell furnace 7a and the cooling water nozzle 8a. The dam plate 17 is provided. As shown in FIG. 5, the dam plate 17 has a donut shape, and the dam plate 17 has a plurality of through holes 17a (rat holes) contacting the inner peripheral surface 2d of the rotary kiln 2 at equal intervals along the circumferential direction. Is provided.

  By providing such a dam plate 17 with a through-hole 17a on the inner peripheral surface 2d of the rotary kiln 2, the moving speed of the fly ash FA1 moving toward the terminal end in the rotary kiln 2 is suppressed, and the residence time is lengthened. Therefore, complete combustion of unburned carbon can be achieved, and the axial direction of the rotary kiln 2 can be reduced. Further, since the through-hole 17a of the dam plate 17 is in contact with the inner peripheral surface 2d of the rotary kiln 2, the fly ash FA1 moving along the inner peripheral surface 2d remains or accumulates in the dam plate 17 portion. I don't have to.

  These dam plates 17 are disposed on the inner peripheral surface 2d of the rotary kiln 2 at the boundary between the outer shell furnaces 6a and 7a and at the boundary between the outer shell furnace 7a and the cooling water nozzle 8a. It is possible to retain the fly ash FA1 until the combustion start reaction in the arranged region and the combustion reaction in the region in which the outer shell furnace 7a is arranged are completed. For this reason, even if it is the rotary kiln 2 whose axial direction is comparatively short, complete combustion of unburned carbon can be aimed at.

  Furthermore, as shown in FIG. 6, a plurality of shelf-shaped stirring members 18 are arranged at equal intervals along the circumferential direction on the inner peripheral surface 2d of the rotary kiln 2 in the region where the outer shell furnace 7a is arranged. Yes. As shown in FIG. 7, these agitating members 18 have a shape similar to the seating surface of the bench, and a rotary kiln 2 is formed by a fixing member 19 formed by bending a round bar (or tubular material) into a U-shape. Is attached to the inner peripheral surface 2d.

  These agitating members 18 are also rotated by the rotation of the rotary kiln 2, and the fly ash FA1 is stirred up and dropped so that the fly ash FA1 is stirred, so that sufficient oxygen is supplied into the fly ash FA1. Therefore, the combustion reaction of the unburned carbon that is controlled by oxygen diffusion into the fly ash FA1 can be rapidly advanced, and complete combustion of the unburned carbon in the fly ash FA1 can be achieved.

  Further, as shown in FIG. 7, a gap 20 through which the fly ash FA <b> 1 can pass is provided between each stirring member 18 and the inner peripheral surface 2 d of the rotary kiln 2. The fly ash FA1 can fall through the gap 20. Accordingly, the opportunity (number of times) that the fly ash FA1 directly contacts the inner peripheral surface 2d of the rotary kiln 2 is increased, and the conduction efficiency with the inner peripheral surface 2d is increased. improves. Further, by providing the gap 20, the fly ash FA1 moving along the inner peripheral surface 2d of the rotary kiln 2 remains or accumulates near the boundary between the inner peripheral surface 2d and the stirring member 18. Can also be prevented.

  Furthermore, in this embodiment, by mixing outside air into the high-temperature gas generated from the outer shell furnace 6a and feeding it to the heat exchanger 21, heat exchange is performed between the air introduced into the heat exchanger 21 from the atmosphere. The hot air HA1 whose temperature has been raised is supplied to the burner 6b. In addition, a part of the high-temperature air HA2 that has been heated in the outer shell furnace 7a is supplied from the blower 16 through the air blowing pipe 5 into the rotary kiln 2. By setting it as such a structure, since the air which is in a high temperature state from external air can be supplied to the air blowing pipe | tube 5 and the burner 6b, the consumption of the energy for heating can be reduced.

  As described above, in the fly ash treatment apparatus 1, as the air blowing path into the rotary kiln 2, it is inserted from the starting end 2a of the rotary kiln 2 in the axial center 2c direction, and the burner 6b and outer shell which are external heating type heating means An air blowing pipe 5 having an air blowing hole 5a is provided in the rotary kiln 2 in the region where the furnace 6a is disposed.

  Therefore, air can be supplied from the air outlet 5a when the fly ash FA1 introduced into the region where the burner 6b and the like are disposed reaches the self-combustion start temperature 600 ° C. For this reason, as a result of all of the heating amount by the auxiliary burner 4 and the burner 6b being used to raise the temperature of the fly ash FA1, a rapid temperature rise is possible, and the unburned carbon combustion region, which is a subsequent process, is lengthened. And the combustion of unburned carbon can proceed efficiently. In addition, after starting combustion of unburned carbon, it is not necessary to heat from the outside, so that less energy is consumed.

  The heating method of such a process is a parallel flow in which the heating gas and the fly ash FA1 flow in parallel, and the temperature of the fly ash FA1 containing unburned carbon that travels in the rotary kiln 2 increases while the heating gas The temperature gradually decreases. Since the temperature of the fly ash FA1 is the lowest at the start end 2a of the rotary kiln 2 having the highest heating gas temperature, the temperature of the rotary kiln 2 body is approximately an average value (600 ° C.) of the heating gas temperature and the temperature of the fly ash FA1. ˜900 ° C.) and does not reach a high temperature. For this reason, it is possible to use a general stainless steel material (SUS310S etc.) as a constituent material of the rotary kiln 2, and it is excellent in practicality.

  On the other hand, in the fly ash treatment apparatus 1, the exhaust path is inserted from the end portion 2b of the rotary kiln 2 along the axis 2c direction, and is opened in the rotary kiln 2 near the start end of the region where the water rejection nozzle 8a and the like are disposed. The exhaust pipe 10 is provided. Therefore, it is avoided that the cooling action by the cooling water sprayed from the cooling water nozzle 8a reaches the exhaust gas, and the exhaust gas can pass through the exhaust pipe 10 and be discharged in a high temperature state. For this reason, in addition to improving the combustion efficiency of CO remaining in the exhaust gas, combustion removal of unburned carbon contained in the finely divided fly ash accompanying the exhaust gas is also achieved.

  The fly ash treatment apparatus according to the present invention is an industry that needs to remove unburned carbon contained in fly ash recovered from exhaust gas discharged from a pulverized coal combustion boiler installed in a thermal power plant or the like. Can be widely used in the field.

It is a schematic block diagram which shows the fly ash processing apparatus which is embodiment of this invention. It is a schematic block diagram which shows the exhaust-gas treatment apparatus which processes the waste gas discharged | emitted from the fly ash processing apparatus shown in FIG. It is the sectional view on the AA line in FIG. It is the BB sectional view taken on the line in FIG. It is a fragmentary sectional view which shows the dam plate which comprises the fly ash processing apparatus shown in FIG. It is a fragmentary sectional view which shows the stirring member which comprises the fly ash processing apparatus shown in FIG. FIG. 7 is a partially enlarged view of FIG. 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fly ash processing apparatus 2 Rotary kiln 2a Start end part 2b End part 2c Axle center 2d Inner peripheral surface 3 Screw conveyor 3a, 11 Hopper 4 Auxiliary burner 5 Air blowing pipe 5a Air blowing hole 5b Bulkhead 6a, 7a Outer furnace 6b Burner 7b, 16 Blower 8a Cooling water nozzle 8b Water receiver 9 Fly ash discharge port 10 Exhaust pipe 12 Cooling tower 13 Cyclone 14 Secondary combustion tower 14a Catalyst combustion layer 15 Gas cooling tower 17 Dam plate 17a Through hole 18 Stirring member 19 Fixed member 20 Crevice 21 Heat Exchanger 22 Bag filter FA1 Fly ash containing unburned carbon FA2 Fly ash after processing HA1, HA2 Hot air

Claims (7)

A rotary kiln arranged so that the axis forms a downward slope from the start end to the end,
Fly ash charging means, auxiliary heating means and air blowing path provided at the starting end of the rotary kiln;
An external heating type heating means, an external cooling type air cooling means and an external cooling type water cooling means arranged in series from the starting end to the end of the rotary kiln;
A fly ash discharge port and an exhaust path provided at a terminal portion of the rotary kiln;
A fly ash processing apparatus comprising:   The fly ash treatment apparatus according to claim 1, wherein an air blowing pipe capable of supplying air into the rotary kiln in a region where the external heating type heating unit is disposed is provided as the air blowing path.   The fly ash treatment apparatus according to claim 1, wherein a dam plate protruding in an axial direction is provided on the inner peripheral surface of the rotary kiln, and a through-hole contacting the inner peripheral surface of the rotary kiln is provided in the dam plate.   The fly ash processing apparatus in any one of Claims 1-3 which provided the shelf-shaped stirring member in the said rotary kiln inner peripheral surface.   The fly ash processing apparatus in any one of Claims 1-4 which provided the clearance gap between the said stirring member and the said rotary kiln inner peripheral surface.   The at least one part of the air heated with the heat which generate | occur | produced in the said external heating type heating means and the said external cooling type air cooling means is supplied to at least one of the said air blowing path and the said external heating type heating means. The fly ash processing apparatus in any one.   7. The exhaust pipe according to claim 1, wherein an exhaust pipe is provided in the rotary kiln that is inserted in the axial direction from the end portion of the rotary kiln and is opened in the vicinity of the start end of the area where the external cooling type water cooling means is disposed as the exhaust path. The fly ash processing apparatus of crab.

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