JP2005351554A - Drying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drying device for giving continuous drying treatment to industrial wastes containing water. <P>SOLUTION: The drying device comprises a furnace 10 having a burner 11 on the upper part and an exhaust port in the lower part and a plurality of cylinders (screw conveyors) 12 for carrying and moving workpieces into or out of the furnace 10. It also has a secondary combustion chamber 15 for heating exhaust gas from the furnace and a suction device 16 for sucking the exhaust gas. It measures pressure in the furnace 10 and controls the suction device so that the furnace has negative pressure to atmospheric pressure. With the burner placed thereon, combustion gas spreads over the upper part and moves down to the lower part to reduce temperature irregularity at positions in the furnace and allow uniform heating of the whole furnace. A residing time for the combustion gas in the furnace is controlled by the control of a suction amount, thus improving heat efficiency. With the burner placed thereon, the upper conveyor requiring a great quantity of heat is located closer to the burner, reducing a drying treatment time. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a drying apparatus, and more particularly to a drying apparatus that can continuously dry garbage, industrial waste containing moisture, and the like. In the present specification, drying includes carbonization.

Conventionally, various drying apparatuses have been proposed as drying apparatuses for garbage. For example, in Patent Document 1 below, a plurality of cylinders having screw conveyors are provided in the primary combustion chamber, and the primary combustion chamber is heated to allow garbage to pass through the cylinder. A drying apparatus is disclosed.
Japanese Patent Laid-Open No. 2001-4276

  In the conventional drying apparatus described above, the burner is arranged at the lower part of the furnace, and the combustion gas is discharged from the upper part, but in this case, the residence time of the combustion gas in the furnace is short and the thermal efficiency is poor. was there. In addition, there is a problem that a path through which combustion gas flows is created, and the temperature in the furnace is not uniform, and unevenness occurs depending on the location.

  In addition, when drying garbage etc., in order to connect a plurality of screw conveyors in series and pass the work to be dried, the conveyors are arranged vertically so that the axis of the screw conveyor is horizontal, A configuration in which a workpiece is introduced from the top, is sequentially transferred to a lower conveyor, and is dried. In this case, it is necessary to supply a large amount of heat because the upper conveyor has more moisture and the like.

  However, the combustion gas generated from the burner becomes higher as it gets closer to the burner. Accordingly, there is a problem that the temperature is too high in the lower part and the workpiece is carbonized or burned, the conveyor and the cylinder are damaged by heat, and the temperature inside the cylinder does not rise in the upper part.

  The present invention aims to solve the above-described problems. For this purpose, the drying apparatus of the present invention includes a furnace provided with heating means at the top and an exhaust port provided below the heating means, And a conveyor means for carrying in, moving and carrying out the workpiece. Further, the present invention is also characterized in that it includes a secondary combustion means for heating the furnace exhaust by the second heating means, and a suction means for sucking the exhaust from the secondary combustion means.

  Further, a pressure measuring means for measuring the pressure in the furnace, and a control means for controlling the suction means so that the inside of the furnace becomes a negative pressure with respect to the atmospheric pressure based on the measurement result of the pressure measuring means. There is also a feature in the point. Another feature is that air supply means for supplying air into the furnace is provided.

  Furthermore, the conveyor means is also characterized in that a plurality of conveyors including a cylinder having an exhaust port and a screw conveyor arranged inside the cylinder are connected in cascade. In addition, at least some of the plurality of conveyor cylinders have a cross-sectional shape in which a space is formed above the screw conveyor. Further, the present invention is also characterized in that a cylinder air supply means for supplying air to the space above the screw conveyor inside the cylinder is provided.

  In the drying apparatus of the present invention, the combustion gas spreads in the upper part and descends to the lower part by placing the burner on the top and sucking it with the exhaust port facing down. Therefore, the temperature unevenness due to the location in the furnace is reduced, and the entire furnace can be heated uniformly. Further, since the residence time of the combustion gas in the furnace can be controlled by controlling the suction amount of the combustion gas, there is an effect that the thermal efficiency is improved. Furthermore, by placing the burner on the top, the position of the upper conveyor and the burner, which require a large amount of heat, becomes close, and the drying process time is shortened.

  Therefore, according to the drying apparatus of the present invention, the drying time and operation cost are remarkably shorter or less than other systems, and the apparatus can be downsized. In particular, it can be used to dry or carbonize work pieces such as food waste and various industrial wastes (livestock excrement, vegetable scraps, wood chips, sludge), etc. Can be reduced. Furthermore, charcoal can be reused as a soil conditioner.

  Embodiments will be described below with reference to the drawings.

  FIG. 1 is a front view showing a configuration of an embodiment of a drying apparatus of the present invention. Moreover, FIG. 2 is a side view which shows the structure of the Example of the drying apparatus of this invention. A solid line with an arrow indicates a movement path of the workpiece, and a dotted line with an arrow indicates a movement path of the combustion gas. The drying apparatus is roughly divided into a primary heating chamber 10 (hereinafter also referred to as a furnace 10) and a secondary heating chamber 15 (rear of the furnace 10 in FIG. 1). The furnace 10 is a metal rectangular parallelepiped furnace whose inner wall is covered with a heat-resistant material such as refractory bricks, and a primary burner 11 as a heating means is provided at the upper part of the side surface.

  Although details will be described later, a plurality of cylinders 12 are arranged in the vertical direction inside the furnace 10, and a screw conveyor driven by a motor 13 is built in each cylinder 12. When the workpiece is loaded from the furnace loading port 19 by the loading conveyor 18 and conveyed to the opposite side of the furnace 10 by the screw conveyor, it falls to the lower screw conveyor and is conveyed again into the furnace.

  The workpiece that has reached the lowermost conveyor 12F is discharged through a discharge conveyor 14 that also serves as a cooling device. Between the inlet of the inlet conveyor 18 and the outlet of the outlet conveyor 14 is sealed except for the water vapor and dry distillation gas outlet in the furnace. In particular, since a hot workpiece to be carried out of the furnace may be burned when exposed to air, the workpiece is cooled to a temperature at which it does not burn while passing through the airtight discharge conveyor 14.

  Further, in order to reduce the amount of air entering and exiting from the input port of the input conveyor 18 and the output port of the discharge conveyor 14 as much as possible, the workpieces of the input conveyor 18 and the discharge conveyor 14 are filled so that the workpiece is filled into the screw conveyor without gaps. The rotational speed is controlled to be slower than the rotational speed of the conveyor in the furnace.

  A connecting portion 21 with the secondary heating chamber 15 is provided in the lower part of the furnace 10, and the combustion gas moves to one end of the secondary heating chamber 15 through the connecting portion 21. The secondary heating chamber 15 is a metal cylinder whose inner wall is covered with a heat-resistant material such as refractory bricks, and a secondary burner 20 is provided in the vicinity of the connecting portion 21. The secondary heating chamber 15 is for completely combusting and decomposing dry distillation gas, dioxin and the like generated from the workpiece and discharged into the furnace at a high temperature.

  The other end of the secondary heating chamber 15 is connected to an exhaust cylinder 17 via a suction device 16. The suction device 16 is a cylindrical body having a constriction, and sucks the combustion gas in the secondary heating chamber 15 by blowing air pressurized from an external blower into the constricted portion and discharges it from the exhaust tube 17.

  FIG. 3 is a front view showing the configuration of the primary combustion chamber 10 of the drying apparatus of the present invention. A primary burner 11 serving as a heating means is provided at the upper part of the side surface of the furnace 10. As the burner 11, any known commercially available one can be used. In the furnace 10, in this embodiment, six cylinders containing screw conveyors are arranged vertically. The upper two pieces (12A and 12B) have a U-shaped cross section of the cylindrical body 12, and the lower four pieces (12C to 12F) have a circular cross section.

  FIG. 4 is a cross-sectional view and a plan view showing the configuration of the cylinder of the drying apparatus of the present invention. Fig.4 (a) is sectional drawing which shows the structural example of two cylinders (12A, 12B) of an upper part. The cylindrical body 40 is a metal member having a substantially U-shaped cross section, and a screw conveyor 41 is built in the cylindrical body 40. A lid body 42 is attached to the upper portion of the cylindrical body 40, and a plurality of exhaust ports 43 are provided in the lid body 42 at equal intervals. The lid body 42 is fixed to the cylinder body 40 with a bolt or the like (not shown). When drying, a large amount of water vapor is generated. Therefore, the upper multi-stage cylinder (in this embodiment, two stages) has a U-shaped cross section to make it easier for water vapor to escape.

  4C and 4D are plan views showing two configuration examples of the lid body 42. FIG. (C) is an example in which a relatively large exhaust port is provided, and (d) is an example in which an exhaust port smaller than (c) is provided. By replacing the lid 42 with an optimum one based on the type and state of the workpiece, the drying process can be performed in the optimum state.

  FIG. 4B is a modified example of FIG. 4A, which is obtained by adding air supply means to the inside of the cylindrical body in the configuration of FIG. In (b), the piping 44 provided with the some hole is provided in the inside of the cylinder 40, and the heated air is supplied to the inside of the cylinder 40 from the external blower through the piping 45 in the furnace. With such a configuration, the workpiece is dried more quickly.

  4E and 4F are cross-sectional views showing a configuration example of the lower four (12C to 12F) cylinders. The lower the cylinder is, the smaller the amount of water vapor or gas generated from the workpiece, and the more easily the carbonization or combustion occurs when it is dried. In the upper structure (a), the area of the exhaust port can be adjusted by replacing the lid 42. However, in the case of the lower part, a pipe provided with a hole is used as a cylindrical body, but it is difficult to make a configuration in which the pipe itself is replaced.

  Therefore, a plurality of exhaust holes 51 are provided in the cylinder 50, and an adjustment plate 52 having a hole 53 overlapping the hole 51 is overlapped with the cylinder 50 and is slidably held. Then, the opening area is adjusted and fixed with screws (not shown). The shape of the hole may be an ellipse or an ellipse. Further, a planar plate having the same function as the adjustment plate 52 may be provided on the upper lid 42. Furthermore, if the position of the adjusting plate can be adjusted from the outside of the furnace, the opening area of the exhaust port can be changed during operation of the furnace.

  FIG. 5 is a front view showing the internal configuration of the cylinder of the drying apparatus of the present invention. A screw conveyor is built in each of the cylinders 12A to 12F and is driven by a motor-13. When the workpiece is loaded from the furnace loading port 19 by the loading conveyor and conveyed to the opposite side of the furnace 10 by the screw conveyor, it falls to the lower screw conveyor and is conveyed again into the furnace.

  In particular, in the case of sludge containing a flocculant, it becomes a dumpling-like lump during conveyance on the screw conveyor, and heat does not easily pass to the inside, and drying takes time. Therefore, in order to break up the lump, as shown in the cross section at the bottom of FIG. 5, a grid is formed along the lower surface of the upper screw conveyor between the upper screw conveyor and the lower screw conveyor at the turn point of the conveyor. A net 60 (or punching plate) is provided. Then, the lump is pressed against the net 60 by the scraper 61 attached to the shaft of the screw conveyor, and is crushed and dropped. The shaving plate may be a flat plate or a curved plate, or may be a columnar member whose cross section is an ellipse, an ellipse, or an eccentric circular shape.

  FIG. 6 is a front view showing the configuration of the secondary combustion chamber of the drying apparatus of the present invention. The secondary heating chamber 15 is a metal cylinder whose inner wall is covered with a heat-resistant material such as refractory bricks, and a secondary burner 20 is provided in the vicinity of the connecting portion 21. The secondary heating chamber 15 is for completely combusting and decomposing a dry distillation gas, a harmful gas such as dioxin, an off-flavor component, and the like generated from the workpiece and discharged into the furnace at a high temperature.

  The other end of the secondary heating chamber 15 is connected to an exhaust cylinder 17 via a suction device 16. The suction device 16 is a cylindrical body having a constriction, and sucks combustion gas from the secondary heating chamber 15 by blowing air pressurized from an external blower 70 into the center of the constricted portion. The sucked gas is discharged from the exhaust cylinder 17.

  FIG. 7 is a block diagram for explaining the control function of the drying apparatus of the present invention. The control device 80 is a known control device that performs control by a program and manual operation. A temperature sensor 81 for measuring the temperature in the furnace 10 and a pressure sensor 82 for measuring the pressure in the furnace 10 (differential pressure from the atmospheric pressure) are connected to the control device 80. Further, the two burners 11 and 20 in the apparatus, the blower 70 of the suction device, the blower 83 for supplying air into the furnace 10, and the cylinder 40 shown in FIG. 4B are provided. A blower 84 and the like for supplying heated air to the pipe 44 are inverter-controlled.

  Although the blower 83 for supplying air into the furnace 10 is not an essential device, combustible dry distillation gas is generated together with water vapor depending on the type of workpiece. Thus, by supplying air into the furnace 10 by the blower 83, fuel can be expected by burning the dry distillation gas in the primary combustion chamber 10, and the furnace is adjusted by adjusting the amount of air supplied. The internal temperature can be controlled.

  In the primary combustion chamber 10, the burner 11 and the blower 83 are controlled so that the temperature becomes a desired set value, and the blower 70 of the suction device is controlled so that the pressure in the furnace becomes a negative pressure rather than the atmospheric pressure. Is done.

  The workpiece is conveyed into the furnace by a screw conveyor, and the cylinder 12 is provided with an exhaust port as described above. Moreover, although it can seal to some extent by making the speed of the input conveyor 18 and the discharge conveyor 14 slow and filling a workpiece into a conveyor, it cannot be made completely airtight. Therefore, if the pressure in the furnace is higher than atmospheric pressure, the combustion gas may flow into the cylindrical body 12 from the exhaust port and the workpiece may be burned.

  Therefore, by keeping the inside of the furnace at a negative pressure, combustion of the workpiece is prevented and drying is promoted. If the negative pressure is too large, air may flow from the discharge conveyor 14 and the workpiece in a high temperature state may burn, so the magnitude of the negative pressure is controlled to the minimum necessary value.

  Although the embodiments have been described above, the following modifications may be considered for the drying apparatus of the present invention. In the embodiment, a configuration using a well-known screw conveyor has been disclosed. However, a scraper may be attached to the blades of the screw conveyor to convey the workpiece while stirring. For example, the scraper plate is attached perpendicularly to the blades of the screw conveyor at a position where rotation is not hindered. In this way, it can be dried more quickly.

  In the embodiment, the configuration in which the conveyors are arranged in a line in the vertical direction is disclosed. However, for example, the conveyors may be arranged in a zigzag manner or arranged in an oblique direction. Two or more rows may be arranged vertically. The numbers of the U-shaped cross-sections and the circular cross-section cylinders are also arbitrary, and all may be U-shaped in cross section, or all may be circular in cross section. In addition, although an embodiment in which a part of the cylinder has a U-shaped cross section has been disclosed, the cross-sectional shape of the cylinder may be any shape as long as there is a space above the screw conveyor, such as a 0-shaped cross section. It can be adopted.

  In the embodiment, an example in which a screw conveyor is used has been disclosed. However, the present invention can be carried out by a conveying means other than the screw conveyor as a means for conveying a workpiece.

It is a front view which shows the structure of the Example of the drying apparatus of this invention. It is a side view which shows the structure of the Example of the drying apparatus of this invention. It is a front view which shows the structure of the primary combustion chamber of the drying apparatus of this invention. It is sectional drawing and a top view which show the structure of the cylinder of the drying apparatus of this invention. It is a front view which shows the structure inside the cylinder of the drying apparatus of this invention. It is a front view which shows the structure of the secondary combustion chamber of the drying apparatus of this invention. It is a block diagram for demonstrating the control function of the drying apparatus of this invention.

Explanation of symbols

10 ... Primary heating chamber (furnace)
11 ... Primary burner 12 ... Cylinder (screw conveyor)
DESCRIPTION OF SYMBOLS 13 ... Motor 14 ... Discharge conveyor 15 ... Secondary heating chamber 16 ... Suction device 17 ... Exhaust pipe 18 ... Input conveyor

Claims (7)

A furnace provided with heating means at the top and an exhaust port provided below the heating means;
A drying apparatus comprising conveyor means for loading, moving, and unloading a workpiece into a furnace. A secondary combustion means for heating the exhaust of the furnace by a second heating means;
The drying apparatus according to claim 1, further comprising suction means for sucking exhaust gas from the secondary combustion means. A pressure measuring means for measuring the pressure in the furnace;
The drying apparatus according to claim 2, further comprising a control unit that controls the suction unit based on a measurement result of the pressure measurement unit so that the inside of the furnace becomes a negative pressure with respect to an atmospheric pressure.   The drying apparatus according to claim 2, further comprising air supply means for supplying air into the furnace.   2. The drying according to claim 1, wherein the conveyor means is formed by cascading a plurality of conveyors each including a cylinder having an exhaust port and a screw conveyor disposed inside the cylinder. apparatus.   The drying apparatus according to claim 1, wherein at least some of the plurality of conveyor cylinders have a cross-sectional shape in which a space is formed above the screw conveyor. The drying apparatus according to claim 6, further comprising a cylinder air supply means for supplying air to a space above the screw conveyor inside the cylinder.

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