JP2009202078A - Drying and granulation system of wet organic waste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system which can easily obtain a dried material excellent in handling at a low cost by efficiently drying and granulating the wet organic waste. <P>SOLUTION: The drying and granulation system 1 of the wet organic waste comprises a storage tank 2 storing the wet organic waste, a superheated steam generator 3 generating superheated steam, a crushing air flow dryer 4 crushing and drying the wet organic waste while bringing the wet organic waste W supplied from the storage tank into direct contact with the superheated steam S supplied from the superheated steam generator, and a granulator 9 granulating the organic waste crushed and dried by the crushing air flow dryer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a system for drying and granulating water-containing organic waste, particularly water-containing organic sludge such as sewage sludge, paper sludge, and food sludge.

  Conventionally, most of the water-containing organic sludge such as sewage sludge, papermaking sludge, food sludge, etc. has been landfilled as it is or after incineration. However, although landfill processing is simple, it is not preferable because it may lead to environmental destruction of the landfill, and the landfill is decreasing year by year. Therefore, attempts have been made to dry hydrous organic waste such as hydrous sludge and reuse it as fuel, and various systems have been proposed.

  For example, Patent Document 1 discloses a step of dropping a muddy object in a rotating tray in a space that is airtightly held against the outside air, and a muddy object accumulated in the receiving tray is rotated integrally with the receiver to surround the muddy object. A step of causing the muddy material to collide and adhere to the barrier surrounding the tray, and a step of blowing the mixed gas of superheated steam and combustion exhaust gas to the muddy material and the muddy material adhering to the barrier to expand and dry the muddy material. And drying the muddy material by scraping with a mortar-shaped scraper placed under the dish and receiving the dried material adhering to the barrier, and dropping the scraped dried material down from the hole provided at the bottom of the scraper. A system has been proposed.

  Further, in Patent Document 2, only superheated steam is used as a drying heat source, a plurality of drying floor surfaces are provided inside, a rotating rake is disposed on each drying floor surface, sludge supplied from an upper supply unit, etc. The superheated steam circulation type drying system that moves from the upper stage to the lower stage while being mixed and stirred by a rotating rake, dries in direct contact with the circulating superheated steam, and then discharges from the lower outlet. Proposed.

  Furthermore, in Patent Document 3, a water-containing organic sludge is dehydrated to obtain an organic dehydrated cake, which is mixed and granulated by a biaxial mixer, and then the granulated product is dried by a hot air co-current rotary drying drum. A system has been proposed.

JP 2005-114327 A JP 2006-308162 A Japanese Patent Laid-Open No. 11-217576

  However, first, in the method for drying a mud material proposed in Patent Document 1, since the mixed gas of superheated steam and combustion exhaust gas is used to dry the mud material, the mud material is dried. As the amount of the processing gas becomes large, the processing cost increases, and there is a concern that the drying apparatus and the like explode due to oxygen contained in the combustion exhaust gas. Moreover, the dried product was bulky and had problems in handling properties such as transportation and storage.

  In addition, in the technique proposed in Patent Document 2, since only superheated steam is used, the amount of processing gas after drying can be reduced, the cost required for gas processing can be reduced, and oxygen is contained in the drying hot gas. Since it is not included, there is no risk of explosion of the drying device or the like. However, in this technique, the material to be dried is mixed and stirred by a rotating rake placed on the dry floor surface while being dried. Since the floor surface is moved from the upper stage to the lower stage and dried, the contact area between the material to be dried and the superheated steam is relatively small, and it cannot be said that the drying efficiency is necessarily high, and the apparatus becomes large, There was a problem that the cost of the equipment and the operation cost were soaring. Moreover, since the dried product becomes bulky as in the technique of Patent Document 1, the handling property such as transportation and storage has a problem.

  In addition, in the system disclosed in Patent Document 3, since the material to be dried is granulated and dried, dust explosion during the drying hardly occurs, and the dried material is granulated. Therefore, it is a system that can obtain a product with good handling properties, but the drying of the granulated product is inefficient because the moisture is confined in the granulated product, and a large drying device is required. As a result, there has been a problem that the cost of the apparatus and the operating cost are soaring.

  The present invention has been made in view of the various problems of the background art described above, and its purpose is to efficiently dry and granulate water-containing organic waste, and to provide a dry-processed product with good handling properties. It is an object of the present invention to provide a water-containing organic waste drying and granulating system that can be easily obtained at low cost.

In order to achieve the above-described object, the present invention is a water-containing organic waste drying and granulating system described in [1] to [4] below.
[1] A storage tank for storing water-containing organic waste, a superheated steam generator for generating superheated steam, a water-containing organic waste supplied from the storage tank, and superheated steam supplied from the superheated steam generator. A hydrous organic waste comprising: a pulverized air flow dryer for crushing and drying hydrous organic waste while being in direct contact; and a granulator for granulating the organic waste crushed and dried by the crushed air flow dryer. Product drying and granulation system.
[2] The water-containing organic waste drying and granulating system according to [1], wherein the water-containing organic waste is water-containing significant sludge such as sewage sludge, papermaking sludge, and food sludge.
[3] The water-containing organic waste according to [1] or [2], wherein the crushing air dryer is a crushing air dryer of a striking type such as a chain hitting type or a rod hitting type. Drying and granulating system.
[4] The water-containing organic waste drying and granulating system according to any one of [1] to [3], wherein the granulator is a stirring granulation type twin screw mixer.

  According to the present invention described above, the water-containing organic waste is directly brought into contact with the superheated steam having a large amount of heat per unit volume by the crushing airflow dryer, and the water-containing organic waste is dried while being crushed. Water-containing organic waste can be efficiently dried while greatly increasing the contact area between the water and superheated steam, and the organic waste after crushing and drying is granulated by a granulator, so that it has good handling properties. Organic waste can be obtained.

  Here, in the drying and granulation system for hydrous organic waste according to the present invention, the superheated steam discharged from the crushing air dryer is returned to the crushing air dryer by providing a circulation route. Is preferable because a system with high heat efficiency can be constructed with little loss of heat. Moreover, if the exhaust route for discharging excess water vapor is provided in the circulation route, and a condenser or a combustion furnace for treating the water vapor discharged from the exhaust portion is provided, the amount of water vapor circulating is kept constant. In addition, it is possible to prevent diffusion of volatile components, odorous components and the like generated from water-containing organic waste into the atmosphere.

  According to the above-described present invention, the water-containing organic waste can be efficiently dried and granulated, and the organic waste having good handling properties can be obtained at low cost and easily.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a water-containing organic waste drying and granulating system according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a flow diagram illustrating an embodiment of a drying and granulation system for hydrous organic waste according to the present invention. This drying and granulation system 1 is a storage tank for storing hydrous organic waste. 2, a superheated steam generator 3 for generating superheated steam, a pulverized air flow dryer 4 for crushing and drying the hydrated organic waste W while directly contacting the hydrated organic waste W and the superheated steam S, and a hydrated organic A supply device 5 for supplying the waste W to the crushing air dryer 4, a blower 6 for supplying superheated steam S to the crushing air dryer 4, and a cyclone 7 for separating the exhaust from the crushing air dryer 4 into a solid gas A bag filter 8 that collects dust contained in superheated steam S ′ discharged from the cyclone 7, a granulator 9 that granulates the dry organic waste W ′ collected from the cyclone 7 and the bag filter 8, and a granulator Grain size A storage tank 10 for storing the dry granulation organic waste W "was and is mainly composed of a circulation blower 11 for circulating the superheated steam S '.

  The water-containing organic waste storage tank 2 is provided for storing the received water-containing organic waste W. As the water-containing organic waste W, for example, water-containing organic sludge such as highly water-containing sewage sludge, papermaking sludge, food sludge and the like containing water of 40% by mass or more is targeted. The storage tank 2 is provided with a supply device 5 such as a screw feeder for supplying the hydrated organic waste W to the crushing air flow dryer 4 at the bottom.

The superheated steam generating apparatus 3, in this embodiment, the heat exchanger 3b for heating the boiler 3a for generating superheated steam So in the early stage of operation, the superheated steam S ₀ and circulating superheated steam S 'to the desired temperature It consists of and. As the boiler 3a, for example, a waste heat boiler that generates superheated steam So using waste heat from a cement firing facility can be used. In addition, as the heat exchanger 3b, a plate heat exchanger using waste heat from the cement firing facility can be preferably used. The blower 6 is provided on the steam discharge side of the superheated steam generator 3 and supplies the superheated steam S to the crushed airflow dryer 4. If the superheated steam S is not circulated, the superheated steam generator 3 may be only the boiler 3a.

  The crushing air dryer 4 is provided to dry the hydrated organic waste W supplied from the storage tank 2 with the superheated steam S supplied from the superheated steam generator 3 while crushing. As this crushing air dryer 4, for example, a chain blow type crushing air dryer is used. The chain blow type crushing air dryer 4 includes a supply port 4a for the water-containing organic waste W in the upper part and a supply port 4b for the superheated steam S from the superheated steam generator 3 in the lower part. The superheated steam S is brought into direct contact with the countercurrent. In addition, a rotating shaft 4c and a plurality of striking chains 4d that are fixed to the rotating shaft 4c and extend horizontally by centrifugal force along with the rotation of the rotating shaft 4c to crush the water-containing organic waste W are provided. Is provided. There is also a rod hitting type crushing air dryer in which a round bar or the like is mounted horizontally on a rotating shaft instead of a chain (striking chain).

  As the crushing air dryer, there are a crushing air dryer of a cage mill type or a swirling type in addition to the crushing air dryer of the hitting system such as the chain hitting type and the bar hitting type. The cage mill type crushing air dryer is a dryer provided with crushing cages that are reversed to each other, and the swirling type crushing air dryer is a crushing air dryer using a circulating air current. However, in comparison with these types of crushing air dryers, the above-mentioned crushing air dryers such as the chain hitting type and the bar hitting type can dry while effectively crushing the water-containing organic waste W. Therefore, it can be used particularly preferably in the present invention.

  The cyclone 7 is provided for recovering the dried organic waste W ′ obtained by the crushing drying in the crushing air dryer 4, and the bag filter 8 is provided for recovering the dust in the exhaust gas of the cyclone 7. It is done. The cyclone 7 is not limited to a single stage as shown in the figure, and can be multistage. In that case, in order to collect finer dust in the subsequent stage, the cyclone diameter is increased as much as the subsequent cyclone. It is normal to make it smaller. However, in such a configuration, there is a possibility that a sufficient air volume may not be ensured, so a multi-cyclone can be employed. Further, the bag filter 8 can be omitted if the dust concentration at the outlet of the cyclone 7 does not adversely affect the dust filter, but even in that case, if the excess water vapor S ″ is discharged, A bag filter is required on the downstream side of the surplus steam discharge unit 13 described later.

  The granulator 9 is provided for granulating the dry organic waste W ′ collected from the cyclone 7 and the bag filter 8 to a particle size with good handling properties. As the granulator 9, for example, a stirring granulation type twin screw mixer is used. The stirring granulation type twin-screw mixer includes a processing tank 9a to which raw materials are supplied, two rotating shafts 9b that are arranged in parallel to each other in the processing tank 9a and rotate in opposite directions, and the rotation of these rotating shafts 9b. And a plurality of paddles 9c each fixed to the shaft 9b. And the raw material supplied in the processing tank is kneaded uniformly and uniformly by the action of the paddles 9c provided on the two rotating shafts rotating in the opposite directions, gradually granulated, and a predetermined time elapses. It is discharged from the outlet at the bottom as a granulated product.

  In addition to the agitation granulator described above, the granulator includes a rolling granulation type, a compression granulation type, a fluidized bed granulation type, and the like. In the rolling granulation method, a binder liquid is sprayed while rolling raw material powder in a rotating container such as a rotating drum, and agglomeration proceeds and granulates in a snowman manner. In the compression granulation method, the raw material powder is compressed and molded between two rotating rolls. In the fluidized bed granulation method, a binder is sprayed and granulated while the powder is suspended and suspended in a fluid blown from below. Among the various granulation methods known as described above, the stirring granulation type twin screw mixer used in the present embodiment has a simple structure and a large throughput, and the dry organic waste W ′. In particular, it is suitably used in the present invention.

  The dry granulated organic waste storage tank 10 is provided to store the dry granulated organic waste W ″ granulated by the granulator 9. The circulation blower 11 and the circulation duct 12 are crushed. The superheated steam S ′ discharged from the air dryer 4 and separated from the dried organic waste W ′ by the cyclone 7 and the bag filter 8 is again crushed through the heat exchanger 3 b of the superheated steam generator 3. It is provided to return to

  The surplus steam discharge unit 13 is provided in the circulation duct 12 constituting the closed circuit, and is provided for discharging surplus steam S ″. The surplus steam discharge unit 13 is discharged from the surplus steam discharge unit 13 at the subsequent stage. In order to process volatile components, odor components, etc. in the surplus steam S ″, a condenser (not shown) for condensing the steam and returning it to a liquid is arranged.

  Next, the operation of the drying and granulation system according to the present invention having the above configuration will be described with reference to FIG.

  First, the received water-containing organic waste W is temporarily stored in the storage tank 2, and the superheated steam So is generated by the boiler 3a that is operated by using waste heat of the cement baking equipment. Heat to a desired temperature by the heat exchanger 3b. That is, the superheated steam S is generated by the superheated steam generator 3.

  Then, while supplying the water-containing organic waste W from the said storage tank 2 from the upper supply port 4a of the crushing airflow dryer 4 via the supply apparatus 5, from the lower supply port 4b of the crushing airflow dryer 4, the above-mentioned Superheated steam S from the superheated steam generator 3 is introduced through the blower 6. Since the temperature of the superheated steam S is about 200 ° C. to 500 ° C., the retained heat amount per unit volume is large, and the heat amount sufficient to dry the water-containing organic waste W is obtained. Further, in the crushing air dryer 4, the water-containing organic waste W and the superheated steam S are in direct contact with each other, and the water-containing organic waste W is removed by the striking chain 4 d provided in the crushing air dryer 4. In order to dry while crushing, the water-containing organic waste W is dried from the surface while increasing its specific surface area. Therefore, in addition to improving the drying efficiency by increasing the specific surface area, the crushing efficiency is also improved by the surface drying of the water-containing organic waste W, and the overall drying efficiency is dramatically improved as compared with the conventional case. Moreover, since the superheated steam S not containing oxygen is used, there is no risk of explosion of the crushed air dryer 4 or the like.

  Next, the dried organic waste W ′ crushed and dried by the crushing air dryer 4 is collected by the cyclone 7 and the bag filter 8, and the collected dried organic waste W ′ is put into the granulator 9 for granulation. To do. In the granulator 9, the dry organic waste W ′ is uniformly and reliably kneaded by the action of the paddles 9 c provided on the two rotating shafts 9 b that rotate in opposite directions, and gradually granulated. Then, after a predetermined time has passed, it is discharged from the bottom outlet as a granulated product. The particle size of the granulated product can be set to various particle sizes depending on the purpose of use. In this case, an appropriate amount of a liquid binder may be added to the granulator 9, and if necessary, It is good also as a structure in which the water-containing organic waste W used as a nucleus is thrown into the granulator 9 partially directly from the storage tank 2. FIG.

  The dry granulated organic waste W ″ granulated by the granulator 9 is temporarily stored in the storage tank 10 and then transported, and can be used, for example, as a fuel for cement burning equipment. In use, it can be blown in place of pulverized coal or mixed with pulverized coal from the main burner of the cement kiln. The dry granulated organic waste W ″ in this case is granulated to 2 mm to 15 mm. If it is, it will become favorable in handling property and blowing property. Further, it may be put into the cement kiln from a place other than the main burner, or the granulated product may be crushed again and then put.

  On the other hand, the superheated steam S ′ separated from the dry organic waste W ′ by the cyclone 7 and the bag filter 8 is returned to the heat exchanger 3 b of the superheated steam generator 3 by the circulation blower 11 and the circulation duct 12. After being heated to the desired high temperature superheated steam S, it is returned to the crushing air dryer 4 again. Thus, the superheated steam S is circulated to secure the amount of superheated steam flowing in the crushed airflow dryer 4, and the heat loss is suppressed, thereby constructing a system with high thermal efficiency.

  Further, the surplus steam S ″ staying in the circulation duct 12 is circulated by adopting a configuration in which the surplus steam S ″ is appropriately discharged to the outside via the surplus steam discharge section 13 and returned to the liquid by a condenser (not shown) and recovered. The amount of water vapor can be kept constant, and the diffusion of volatile components, odorous components, etc., generated from the water-containing organic waste W into the atmosphere can be prevented. Thus, deodorizing treatment can be performed.

  As mentioned above, although the embodiment of the drying and granulation system of the water-containing organic waste according to the present invention has been described, the present invention is not limited to the embodiment described above, and the present invention described in the claims. It goes without saying that various modifications and changes are possible within the scope of the technical idea.

It is the flowchart which showed one Embodiment of the drying and granulation system of the water-containing organic waste concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drying and granulation system 2 Storage tank of hydrous organic waste 3 Superheated steam generator 3a Boiler 3b Heat exchanger 4 Crushing air dryer 5 Feeding device 6 Blower 7 Cyclone 8 Bag filter 9 Granulator 10 Dry granulation organic waste Waste storage tank 11 Circulating blower 12 Circulating duct 13 Excess steam discharge section S Superheated steam W Water-containing organic waste

Claims (4)

  A storage tank for storing water-containing organic waste, a superheated steam generator for generating superheated steam, a water-containing organic waste supplied from the storage tank and a superheated steam supplied from the superheated steam generator are brought into direct contact with each other. A hydrated organic waste drying comprising: a crushing air dryer for crushing and drying hydrous organic waste while a granulator for granulating the organic waste crushed and dried by the crushing air dryer And granulation system.   The water-containing organic waste drying and granulating system according to claim 1, wherein the water-containing organic waste is water-containing organic sludge such as sewage sludge, papermaking sludge, and food sludge.   3. The water-containing organic waste drying and granulating system according to claim 1, wherein the crushing air dryer is a crushing air dryer of a striking type such as a chain hitting type or a bar hitting type.   The drying and granulation system for hydrous organic waste according to any one of claims 1 to 3, wherein the granulator is a stirring granulation type twin screw mixer.

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