JP3751307B2 - Sludge drying system - Google Patents

Description

  The present invention relates to a sludge drying system capable of reducing sludge generated in a large amount in a wastewater treatment facility and the like and achieving reduction in treatment costs.

  A large amount of sludge is generated in factories and sewage treatment plants. Since sludge has a high moisture content and a large volume as it is, it is generally reduced by dehydration. Thickeners, filters and the like can be combined depending on the properties of the sludge, for example, 1/10 by weight, and the moisture content can be reduced from about 98 to 99% to about 70 to 80%.

  However, since the amount of sludge generated is proportional to the amount of wastewater itself and the organic matter concentration in the wastewater, if the amount of wastewater is large and the organic matter concentration is high, the treatment amount is enormous even if these conventional dehydration treatments are performed. In order to further reduce the weight, it is necessary to perform a drying process. However, in general, drying treatment facilities require a large and vast space, and there are many cases that require odor treatment as they dry, so it is necessary to construct a new building and accommodate these facilities indoors, etc. There are various difficulties associated with installation.

  By the way, Patent Document 1 describes a tofu shell drying apparatus that dries tofu shell (okara) generated in the production of tofu with hot air. This will be described with reference to FIG.

  This figure is a cross-sectional view showing the internal structure of the tofu husk drying apparatus 11, which accommodates a large number of pellets P having a predetermined diameter mainly composed of ceramic and is installed in a horizontal direction, and the hollow chamber 111. A box-shaped upper hollow chamber 112 disposed above the hollow chamber 111 and having a lower end communicating with the hollow chamber 111, and a tip opened to the outer peripheral surface of the hollow chamber 111 in the vicinity of the bottom of the hollow chamber 111. The hot air supply path 113 for supplying hot air from a hot air generator (not shown) into the hollow chamber 111, and the tip between the upper hollow chamber 112 and the hot air supply path 113 are arranged in the tangential direction of Opened in the outer peripheral surface of the hollow chamber 111, and is arranged upright and tangentially to the hollow chamber 111, and the tofu shell supply path 114 for supplying the tofu shell into the hollow chamber 111, and the upper hollow chamber 112 It is provided near the upper end, and the contents in the upper hollow chamber 112 are discharged with hot air. Made from the discharge port 116. that. Reference numeral 115 denotes a rotary feeder provided in the tofu husk supply path 114.

  When hot air is sent from the hot air supply passage 113 while supplying the tofu shell into the hollow chamber 111 from the tofu shell supply passage 114, the pellets P in the hollow chamber 111 are blown up by the hot air, and the inner peripheral surface and the upper portion of the hollow chamber 111 are The tofu husks collide with the inner wall of the upper hollow chamber 112 and repeatedly collide with the supplied tofu husks, so the tofu husks are crushed to increase the surface area and dried by hot air, and the pellets P are also heated and stored by hot air The far-infrared rays are emitted to promote further drying, and the crushed, dried and lightened tofu husks soar in the air current. The upper hollow chamber 112 is a classification chamber and rises as it becomes lighter, and the dried product is discharged from the outlet 116 of the upper hollow chamber 112 together with hot air.

Further, Patent Document 2 uses the same device as in FIG. 3 and limits the pellet P accommodated therein to a ceramic mainly composed of a metal oxide having a high mechanical strength, and has a higher specific gravity than tofu shell. Although it is described that a substance (for example, porcelain clay) is dried, according to experiments, the sludge adheres to the inner peripheral surface of the hollow chamber 111 and the inner wall of the upper hollow chamber 112 due to the difference in specific gravity. There is a problem that it grows in a lump shape inside or cannot be dried sufficiently. Moreover, since the hot air is discharged at a high temperature, the thermal efficiency is also poor.
JP-A-6-105663 JP 2000-146433 A

  The present invention realizes a sludge drying system that can perform accurate drying in response to differences in various moisture contents and specific gravity of sludge, has high thermal efficiency, and has no problems such as secondary pollution to the environment. For the purpose.

The present invention accommodates a large number of pellets having a predetermined diameter mainly composed of a metal or a metal compound, and is disposed in a horizontal direction in a cylindrical hollow chamber and above the hollow chamber, and the lower end is located in the hollow chamber. A box-shaped upper hollow chamber that communicates, and a hot air for supplying hot air into the hollow chamber, the tip opening at the outer peripheral surface of the hollow chamber in the vicinity of the bottom of the hollow chamber, arranged in the tangential direction of the hollow chamber A tip is opened in the outer peripheral surface of the hollow chamber between the supply passage, the upper hollow chamber, and the hot air supply passage, and is arranged upright and tangentially to the hollow chamber to supply sludge into the hollow chamber. The hot air is supplied to the hot air supply path to a sludge drying apparatus body which is provided near the upper end of the upper hollow chamber and a discharge port through which the contents in the upper hollow chamber are discharged together with the hot air. A hot air generator is attached. And mud drying device,
A screen that captures pellets discharged from the discharge port and returns them to the upper hollow chamber, a dust collector that separates dry sludge from hot air discharged from the discharge port, and a dry sludge separated by the dust collector A sludge drying system comprising a dry sludge storage means for storing and a gas cleaning device for purifying hot air from which dry sludge has been separated by the dust collector, and preferably the diameter of the pellets is The sludge drying system in the range of 6.0 to 10.0 mm, the sludge drying system in which the surface of the pellet is a non-adhesive material, and the inner wall surfaces of the hollow chamber and the upper hollow chamber It is the said sludge drying system which used non-adhesive material.

  In addition, whether the air volume from the hot air generating device can be changed, or whether there is a hot air return path for returning the hot air separated dry sludge by the dust collector to the hot air supply path, A deodorizing device is provided between the hot air return path and the hot air supply path, or a dry sludge return path for returning the dried sludge stored in the dry sludge storage means to the sludge supply path. Or dewatering means for dewatering sludge upstream of the sludge supply path, dewatered sludge storage means for storing the dewatered sludge, and transfer means for transferring the stored sludge toward the sludge supply path. The sludge drying system provided with the sludge pretreatment device comprising: and the sludge drying system further comprising a crushing means for crushing the sludge dehydrated by the dewatering means in the sludge pretreatment device. .

  According to the present invention, it is possible to perform accurate drying in response to various differences in moisture content, specific gravity, etc. of sludge, and heat efficiency is improved by circulating hot air, and thorough dust collection and deodorization are performed. A sludge drying system without problems such as secondary pollution to the environment will be realized, and the amount of sludge that must be transported for final disposal such as incineration and landfill will be greatly reduced, and industrial waste disposal costs will be reduced. Excellent effect. For example, if the sludge having a moisture content of 85% has been transported to the landfill site with six trucks, according to the present invention, the moisture content is 10% or less and only one truck is required. In addition, since the moisture content is reduced, the rot is prevented, the sludge can be stored for a long time, and the generation of bad odor is also effective.

  An embodiment of the present invention will be described with reference to FIG. This figure is a block diagram of the sludge drying system of the embodiment. 1 is a sludge drying device that dries sludge with hot air, 11 is a sludge drying device body, and its structure is basically different from the tofu shell drying device shown in FIG. There is no. 12 is a hot air generating device, 13 is a hot air deodorizing device, 2 is provided on the outlet side of the sludge drying device main body, that is, downstream of the discharge port 116, passes hot air and dry sludge, and captures the pellets P to be ejected. 3 is a dust collector such as a cyclone that separates hot air and dry sludge, 4 is a dry sludge storage means such as a storage tank, and 5 is a gas purifier such as a venturi scrubber, where sludge is removed. In addition, exhaust gas that has been deodorized and cooled and rendered harmless is dissipated into the atmosphere. You may use dust collection means, such as an electric dust collector, as needed.

  Since the exhaust from the dust collector 3 is still at a high temperature close to 90 ° C., it is preferable from the viewpoint of thermal efficiency that it is returned to the outlet of the hot air generator 12 as much as possible and recycled as hot air. For this reason, a hot air return path 31 for mixing the hot exhaust gas from the dust collector 3 into the hot air is provided, connected to the outlet of the hot air generator 12, and connected to the hot air supply path 113 via the deodorizing device 13. This is because the exhaust from the dust collector 3 contains odor due to sludge, and it is desirable to use a catalyst such as platinum at a high temperature. Therefore, if this hot air return path 31 is not provided, the deodorizing device 13 is also unnecessary.

  6 is a sludge pretreatment device that pretreats the sludge to be introduced into the sludge drying device 1 as necessary, and the contents will be described later. 31 is the hot air return path, and 41 is a dried sludge return path for mixing a part of the dried sludge stored in the dried sludge storage means 4 into the sludge supplied to the sludge drying apparatus 1.

  Sludge having a high water content received from a water treatment plant or the like is supplied to the sludge drying device 1 directly or via the sludge pretreatment device 6 as necessary. Needless to say, the sludge supply path 114 shown in FIG. One hot air is supplied into the hollow chamber 111 from a hot air generator composed of a gas burner, a fan or the like via the hot air supply path 113 shown in FIG. Depending on the type of sludge, the hot air temperature is set to 350 ° C., for example. The temperature can be arbitrarily adjusted according to the combustion amount of the gas burner and the air volume of the fan.

  Although the sludge dried with hot air is discharged from the discharge port 116 of the sludge drying apparatus body 11, a part of the pellet P may be ejected. Therefore, a screen 2 is provided downstream of the discharge port 116 to allow the hot air and dried sludge to pass through and capture the pellets P that are about to jump out.

  The hollow chamber 111 accommodates a large number of pellets P having a predetermined diameter mainly composed of metal or a metal compound (so-called fine ceramics) such as silicon oxide, silicon nitride, aluminum oxide (alumina), or zirconia. The diameter of the pellet P is in the range of 6.0 to 10.0 mm. Since the bulk specific gravity of the fine ceramics is about 3.2 to 6.0, when the diameter of the pellet P is 6.0 mm or less, the pellet P is likely to jump out on the air current. On the other hand, if it is 10.0 mm or more, it will not fly up with hot air inside, so it will not easily collide with sludge and will not be effective for drying. The input amount of the pellets P is arbitrary depending on the operation state, but is approximately 3 to 5% of the internal volume of the hollow chamber 111 as a guide.

Depending on the type of sludge, the adhesiveness is high and may adhere to the surface of the pellet P, the inner peripheral surface of the hollow chamber 111, and the inner wall of the upper hollow chamber 112. If sludge adheres to the surface of the pellet P, the pulverization effect due to the collision is reduced, and if the sludge attached to the inner wall grows, the inside becomes clogged and the efficiency of the drying process is reduced. In order to prevent adhesion of the pellet P to the surface, it is effective to make the material of the pellet P difficult to adhere. Since the surface that is smoother is less adhered than the surface that is rough, the zircon (ZiO ₂ —SiO ₂ ) system is better than the alumina system in this respect. In order to prevent adhesion to the inner wall, it is effective to line with a material having a low friction coefficient, such as a fluororesin.

  The processing amount in the sludge drying apparatus 1 is determined approximately by its internal volume. In order to cope with a change in the processing amount in an already manufactured apparatus, the amount of hot air may be changed. Therefore, it is preferable to provide a damper in the hot air supply path of the hot air generator so that the air volume of the blower can be controlled. By adjusting the hot air, it is possible to prevent adhesion of sludge as well as adhesion.

  Next, an embodiment of the sludge pretreatment device 6 in FIG. 1 will be described with reference to FIG. 61 is a dewatering means such as a dehydrator, 62 is a dewatered sludge storage means for storing the dewatered sludge, 63 is a conveyor for cutting out the stored dewatered sludge and transferring it to the sludge drying apparatus 1, and a transport means such as pneumatic transportation It is. Further, depending on the type of dehydrator, the dehydrated cake may solidify and become a lump, which may hinder subsequent processing. In such a case, it is necessary to provide a crushing means 64 for crushing the dewatered sludge.

  The sludge with a moisture content of 98% received from a wastewater treatment plant is dehydrated to about 85% by the dehydration means 61. The volume is reduced to about 10 at this stage if the receiving sludge is 100. By further drying this sludge with a sludge dryer, the water content can be reduced to about 2% by volume.

  In order to perform a stable drying treatment, it is preferable that the moisture content of the sludge to be introduced into the sludge drying device 1 is in the range of 80 to 90%. If the moisture content is higher than this range, the sludge pretreatment device 6 is used. If it is not necessary, pass it directly. Alternatively, the moisture content can be adjusted by receiving the dried sludge stored in the dried sludge storage means 4 and mixing it into the sludge using the dried sludge return path 41 shown in FIG.

  The sludge drying system of the present invention can efficiently dry without causing internal adhesion or scorching. Therefore, in addition to sludge, various types of food residues such as tofu husks, foods and alcoholic beverages, and cooking residue Can be dried.

It is a block diagram of the sludge drying system of the Example of this invention. FIG. 2 is a configuration diagram of an embodiment of the sludge pretreatment device in FIG. It is sectional drawing of the tofu shell drying apparatus in a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sludge drying apparatus 2 Screen 3 Dust collector 4 Dried sludge storage means 5 Gas cleaning apparatus 6 Sludge pretreatment apparatus
11 Sludge dryer body (tofu shell dryer)
12 Hot air generator
13 Deodorizer
31 Hot air return path
41 Dry sludge return route
61 Dehydration means
62 Dewatered sludge storage means
63 Transportation means
64 Crushing means
111 Hollow chamber
112 Upper hollow chamber
113 Hot air supply path
114 Sludge supply channel (tofu shell supply channel)
115 feeder
116 Discharge port P Pellet

Claims (10)

A cylindrical hollow chamber (111) containing a large number of pellets (P) having a predetermined diameter mainly composed of a metal or a metal compound and disposed horizontally, and disposed above the hollow chamber (111), has a lower end. Has a box-shaped upper hollow chamber (112) that communicates with the hollow chamber (111), and a tip that opens to the outer peripheral surface of the hollow chamber (111) in the vicinity of the bottom of the hollow chamber (111). 111) is arranged in the tangential direction of the hot air supply passage (113) for supplying hot air into the hollow chamber (111), and between the upper hollow chamber (112) and the hot air supply passage (113). A sludge supply path (114) for opening the tip to the outer peripheral surface of the hollow chamber (111), standing upright and being arranged in the tangential direction of the hollow chamber (111), and supplying sludge into the hollow chamber (111) ) And the upper hollow chamber (112) near the upper end, and the contents in the upper hollow chamber (112) are discharged together with hot air. The sludge drying apparatus body consisting outlet and (116) (11) which, sludge drying device formed by attaching a hot-air generator (12) for supplying hot air to the hot air supply path (113) and (1),
The dried sludge is separated from the screen (2) that captures the pellet (P) discharged from the discharge port (116) and returns it to the upper hollow chamber (112), and the hot air discharged from the discharge port (116). Clean the dust collector (3), the dry sludge storage means (4) for storing the dried sludge separated by the dust collector (3), and the hot air from which the dried sludge is separated by the dust collector (3) The sludge drying system characterized by comprising with the gas purifier (5) which changes.   The sludge drying system according to claim 1, wherein the diameter of the pellet (P) is in the range of 6.0 to 10.0 mm.   The sludge drying system according to claim 1 or 2, wherein the surface of the pellet (P) is a non-adhesive material.   The sludge drying system according to any one of claims 1 to 3, wherein the inner wall surfaces of the hollow chamber (111) and the upper hollow chamber (112) are made of a non-adhesive material.   The sludge drying system according to any one of claims 1 to 4, wherein the amount of air from the hot air generator (12) is changeable.   The sludge drying system according to any one of claims 1 to 5, further comprising a hot air return path (31) for returning the hot air separated from the dried sludge by the dust collector (3) to the hot air supply path (113). .   The sludge drying system according to claim 6, further comprising a deodorizing device (13) between the hot air return path (31) and the hot air supply path (113).   The sludge drying system according to any one of claims 1 to 7, further comprising a dried sludge return path (41) for returning the dried sludge stored in the dried sludge storage means (4) to the sludge supply path (114). .   Upstream of the sludge supply path (114), a dewatering means (61) for dewatering sludge, a dewatered sludge storage means (62) for storing the dewatered sludge, and the stored sludge to the sludge supply path (114). The sludge drying system according to any one of claims 1 to 8, further comprising a sludge pretreatment device (6) comprising a transfer means (63) for transferring the sludge.   The sludge drying system according to claim 9, further comprising a crushing means (64) for crushing the sludge dehydrated by the dewatering means (61) in the sludge pretreatment device (6).

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