JP2002066598A - Method and facility for heating object to be treated, which contains water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the heating technology of an object to be treated, which contains water, with inexpensive running cost. SOLUTION: A dielectric heating means 10 directly heats the object to be treated in a water removing device 1, heats it in a state where a container 11 is evacuated by an evacuation pump P and therefore the evaporation of water is advanced. Then, the bulk of the obtained object to be treated, which contains less water, is reduced by indirect heating in the bulk reducing device in a next process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a facility for heat treatment of an object to be treated having a high water content (eg, sludge). The present invention relates to a processing technique for performing volume reduction processing such as drying → carbonization.

[0002]

2. Description of the Related Art Objects to be treated having a high water content, for example, various types of sludge, have a water content of 70 to 80%. When this kind of sludge is subjected to heat treatment, first, water is removed by removing water. The rate is reduced so that processing (including transport) becomes easier. Various means have been tried as the water removing means.

[0003] For example, sludge is evaporated and dehydrated with electric power and microwave to a water content of about 60%, and at the same time, sterilization and fungicide are performed.
In addition, a method is used in which a sludge having a water content of 60% is reduced to a water content of 0% by microwave to obtain a hard lump and a roadbed material or a landfill material of a chip-like substance (Japanese Patent Laid-Open No. 7-68297).

[0004] Further, the object to be treated is heated by a heater and gradually dried while being transported inside the drying device, crushed and then introduced into a stirring chamber which is decompressed by a vacuum pump to remove moisture. There is known a method of promoting evaporation and further drying (Japanese Patent Application Laid-Open No. 10-170151).

[0005]

The above-described method of removing water by microwave heating and evacuation heating is a means capable of effectively removing moisture. However, this means is applied to the entire apparatus to perform processing. To do so requires a large input energy, which is not preferable in terms of running costs.

Accordingly, an object of the present invention is to provide a heat-treating technique for a water-containing workpiece which can reduce the overall running cost.

[0007]

According to the present invention, as a pretreatment step (apparatus), a certain amount of water removal, for example, 70%
The water-removing means for reducing the water content to 20% to 30% of the object to be treated having a water content of ~ 80% is taken, and in the next treatment step (apparatus), the object having a low water content obtained by the water-removing means is removed. It is conveyed continuously or to a remote place, and carbonized by indirect heating means to reduce the volume by carbonization and incineration.

On the other hand, the generated gas containing water vapor generated in the pretreatment step is subjected to a combustion treatment in a heat source (hot blast stove) for generating a hot gas of an indirect heating means so as to surely remove and sterilize odors. It is.

In other words, the heat treatment method is a heat treatment method for a moisture-containing object, wherein the water-removing step is a step of heating by a heating means to evaporate and remove moisture from the moisture-containing object.
A volume reduction step of reducing the water content by heating the object to be treated whose moisture content is reduced by the moisture removal step, wherein the heating means in the moisture removal step is a direct heating means by dielectric heating. The heating means in the volume reduction step is an indirect heating means.

The above-mentioned volume reduction step may be either a carbonization treatment or an ashing treatment, or both.

Further, it is desirable that the generated gas containing water vapor generated during the water removing step is suctioned to remove the water under reduced pressure, and the sucked generated gas is subjected to combustion treatment. In addition, sterilization is also performed reliably.

The supply of the object to the water removal step and the discharge of the low water content object after the treatment are performed in a state where the outside air is shut off by an intermittent moving means having an opening / closing means. It is preferable to perform the water removal step under reduced pressure by suctioning the water, and the removal of water is effectively promoted by heating under reduced pressure.

As a heat treatment facility for a moisture-containing treatment object, a moisture removing device for evaporating and removing moisture from the moisture-containing treatment object by heating, and a treatment object having a reduced moisture content to reduce the volume by heat decomposition. Volume reduction device, the water removal device includes a dielectric heating means for directly heating the object to be processed,
The volume reduction device is provided with an indirect heating means for indirectly heating an object to be processed.

The above-mentioned water removing device is composed of a horizontal cylindrical container, provided with a means for conveying and stirring the object to be processed at a lower portion thereof, a generated steam storage space at an upper portion thereof, and a dielectric heating device located at the space. Is desirably provided. The conveying and stirring means covers the outer surface with a dielectric material and performs dielectric heating itself.

Further, the water removing device is composed of a horizontal cylindrical container, and an intermittent moving means is provided at a supply port and a discharge port thereof so that the inside of the cylindrical container is cut off from the outside air, and a reduced pressure state is obtained by suction of water vapor. It is desirable to secure it.

Further, it is desirable that the above-mentioned dielectric heating means is constituted by a plurality of beam irradiation units.

As described above, by combining the advantages of the respective means organically by adopting the hybrid structure, a facility capable of effectively treating the water-containing workpiece at low cost is provided.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram of a moisture removing apparatus 1 according to the present invention. The moisture removing apparatus comprises a dielectric heating means, and 10 denotes the dielectric heating means. Reference numeral 11 denotes a cylindrical container. The cylindrical container 11 has a predetermined length and a semicircular bottom (see FIG. 2), and both ends are sealed by side walls 11a.

Reference numeral 12 denotes a screw conveyor serving as a conveying and stirring means, which is provided at a lower position inside the cylindrical container 11, and conveys the object to be processed while stirring. The screw conveyor 12 includes a rotating shaft 12a, a screw (screw blade) 12b spirally attached to the rotating shaft 12a, and a stirring blade 1 provided at a predetermined interval between the screws 12b.
2c, and both ends of the rotating shaft 12a are
The bearing 13 is rotatably supported by a bearing 13 provided in a penetrating portion through the side wall 11a of the first member, and the bearing 13 is sealed (sealed). It is not always necessary to support both ends as the support means of the rotating shaft 12a, and may be a cantilever (the right side in the drawing is free).

Reference numeral 14 denotes a plurality of beam irradiators provided in the cylindrical container 11 and located in the generated vapor storage space formed in the upper part of the cylindrical container 11, and 15 denotes a diffusion provided in the beam irradiator 14. A fan disturbs radio waves to help uniform heating.

A microwave power supply 16 applies microwaves between the beam irradiation unit 14 and the cylindrical container 11.

Reference numeral 17 denotes a rotation driving means for rotating the rotation shaft 12a of the screw conveyor 12. The rotation driving means 17 includes a motor 17a and an inverter power supply 12b capable of controlling the motor 17a to rotate forward / reversely and at a variable speed.

Reference numeral 18 denotes an intermittent supply means (also referred to as a fixed-rate supply means) provided at an upper supply port of the cylindrical container 11, and a storage part 18a, and opening / closing dampers 18b provided above and below the storage part 18a. 18c, and a lower opening / closing damper 18c
The upper opening / closing damper 18b is opened in a state of closing to store the object to be treated having high water content (sludge, etc.) in the storage portion 18a once, and when a predetermined amount is reached, the upper opening / closing damper 18b is closed and the lower opening / closing is opened. The damper 18c is opened to supply the processing object into the cylindrical container 11. After supplying the entire processing object in the storage section 18a, the lower opening / closing damper 18c is closed, the upper opening / closing damper 18b is opened, and the processing object is again charged into the storage section 18a. A predetermined amount of the object to be processed is intermittently moved and supplied in a state in which is cut off.

Reference numeral 19 denotes an intermittent discharge means provided at a lower discharge port of the cylindrical container 11 and has the same configuration as the intermittent supply means 18. That is, the storage unit 19a and the opening and closing dampers 19b and 19c above and below the storage unit 19a are operated. It moves intermittently to a carbonizing furnace or a dry carbonizing furnace, etc. and sends it out.

P is a vacuum pump, which forcibly sucks the vapor or generated gas generated in the cylindrical container 11 and
The internal pressure is reduced, and the suctioned gas and the like are sent to the hot blast stove 27 shown in FIG. 3 and the dry distillation gas combustion furnace 63 shown in FIG.

FIG. 2A is a sectional view taken along the line AA of FIG.
As shown in FIG. 2 (B), a dielectric material is formed on the inner surface of the bottom circular portion of the cylindrical container 11, the surface of the screw 12b of the screw conveyor 12, the surface of the stirring blade 12c, and the surface of each substrate of the rotating shaft 12a. It has been given. That is, for example, it is covered with a dielectric (insulator) D such as ceramic or glass, and is itself a heating element.

In the process of removing water from the object, a constant amount of the water-containing object is charged into the cylindrical container 11 from the intermittent supply means 18 on the inlet side. Before the charging, the inside of the cylindrical container 11 is depressurized by operating the evacuation pump P in advance, and a microwave is applied to the beam irradiation unit 14 by the microwave power source 6 to perform dielectric heating.

The dielectric heating is classified into two types, high-frequency heating (4 MHz to 80 MHz) and microwave heating (mainly 2450 MHz), depending on the frequency, and either of them may be used.

The workpiece to be processed is conveyed by the screw conveyor 12 heated by dielectric heating while being stirred by the rotation of the screw conveyor 12 to the discharge side (right side in the figure).

After a predetermined amount of the object to be processed is charged and conveyed, the screw conveyor 12 is rotated forward and reverse to heat it until the water content falls below a predetermined set value (for example, 20 to 30%).

At this time, the object to be processed is directly heated by the heat generated by the dielectric material D covering the base material, and is further heated in a state where the pressure is reduced by the operation of the vacuum pump P and the boiling point of water is lowered. In addition, the evaporation of water is promoted, and the water content is effectively reduced.

The object whose water content has been reduced is taken out by the intermittent discharge means 19. Then, it is continuously conveyed to the carbonization furnace of the next step, or put in a container or the like and conveyed to the processing facility of the next step.

The heating time in the cylindrical container 11 was measured in advance by examining the relationship with the water content in consideration of conditions such as the configuration of the dielectric heating means and the frequency to be applied. It is desirable to set the heating time based on the following. Alternatively, the set water content may be determined by means such as the amount of water vapor and the load of the driving source, and the heating may be terminated.

FIG. 3 is a conceptual diagram of a heat treatment facility for a water-containing treatment object. The treatment object having a low water content by the moisture removing apparatus 1 of FIG. 1 is dried and carbonized by a single indirect heating furnace. Is the case of incineration). The same or corresponding parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted.

In FIG. 3, reference numeral 20 denotes an indirect heating furnace by indirect heating means. The indirect heating furnace 20 has a rotatable cylindrical body 2 having blades for moving an object to be processed while stirring the object.
1, a heating duct 22 for forming a gas duct on the outer periphery of the cylindrical body 21 and introducing a hot gas to heat the cylindrical body 21; and a heating cylinder 22 provided at one end of the cylindrical body 21, 21
And a discharge port 24 provided at the other end of the cylindrical body 21. The cylindrical body 21 is rotationally driven by a rotation driving means (not shown). The rotation driving means includes a driving motor, a driving gear, a driven gear provided on the cylindrical body 21, and the like.

Reference numeral 25 denotes a supply duct surrounding the supply port 23 side, and reference numeral 26 denotes a discharge duct surrounding the discharge port 24 side.

Note that a mechanical seal is applied to a rotating contact portion between the cylindrical body 21 and the heating cylinder 23, and the inside of the cylindrical body 21 is kept in a low oxygen atmosphere. That is, the indirect heating furnace 20
Are a series of heat treatments, such as steaming by indirect heating in a low oxygen atmosphere and thermal decomposition treatments.

Reference numeral 27 denotes a hot blast stove as a heating source.
Burning fuel such as LPG or petroleum to generate hot gas,
The cylindrical body 21 is heated by being supplied into a heating cylinder 22 provided on the outer periphery of the cylindrical body 21. The heated hot gas is sucked by the circulation blower 28, a part of which is returned to the hot blast stove 27, and the other part is heated by a heat exchanger 29 comprising a hot water utilization facility 29 a and a circulation pump 29 b to utilize the exhaust heat to generate a bug. After the filter 30 has been cooled down to an appropriate temperature for use, it is cleaned with the bag filter 30 and the blower 3
1, exhausted through the silencer 32.

The carbides and the like obtained by the heat treatment in the indirect heating furnace 20 are conveyed (discharged) through the discharge duct 26, the intermittent discharge means 33, and the pipe conveyor 34.

On the other hand, the carbonized gas generated during the heating is led out from the discharge duct 26 and sent to the hot blast stove 27 for combustion treatment.

The generated gas containing water vapor generated by the moisture removing means 1 is also introduced into the hot blast stove 27 and burned.

Reference numeral 1 'denotes a second moisture removing device, and it is preferable to operate a plurality of moisture removing devices in parallel in order to facilitate the processing. In this case, the low water content workpiece is supplied to the indirect heating furnace 20 in parallel.

In the figure, reference numeral 35 denotes a hopper for storing the water-containing processing object and supplying it to the water removing device 1 via the intermittent supply means 18 of the water removing device 1 by a pipe conveyor 36.

The material to be treated having a low water content generated by the water removing device 1 is put into the indirect heating furnace 20 and heated at, for example, 600 ° C. and carbonized (800 ° C. or more in the case of incineration). In this case, the heat treatment is effectively performed in a short time by firmly reducing the water content by the water removing device 1.

On the other hand, the gas containing water vapor generated by the moisture removing device 1 and the gas (dry distillation gas) generated during the heat treatment of the indirect heating furnace 20 are introduced into the hot blast furnace 27 at 850 ° C.
Burns harmful substances by burning for more than a second.

FIG. 4 is a conceptual diagram showing an embodiment in which the steps after moisture removal by the moisture removal apparatus 1 and the drying step and the carbonization step are performed in separate indirect heating furnaces, and the moisture removal apparatus is omitted. is there.

The same or corresponding parts as in FIG. 3 are denoted by the same reference numerals, and detailed description is omitted.

In FIG. 4, reference numeral 40 denotes a drying furnace, and reference numeral 50 denotes a carbonizing furnace. The configurations of the drying furnace 40 and the carbonizing furnace 50 are the same as those of the indirect heating furnace 20 of FIG. Therefore, in the same or corresponding parts, one digit of 40 and 50 is set to the same number, and the description is omitted.

In the series of heat treatments of the object to be treated, the carbonizing furnace 50,
The heating operation of the drying furnace 40 is started. That is, the fuel such as LNG is burned in the hot blast stove 27 and supplied to the heating tube 52 of the carbonization furnace 50 to heat the cylindrical body 51. Heat 41. At this time, cooling air 57a is introduced into the connecting pipe 57 to adjust the temperature of the hot gas.

The heating temperature of the carbonization furnace 50 is set at a temperature (200 ° C. to 600 ° C.) at which the workpiece is carbonized.

Next, an object to be treated, which has been treated to a low moisture content by the moisture removing device 1 of FIG. 1, is supplied from the supply side duct 45 of the drying furnace 40, where the moisture is further evaporated to dry and dried. The object to be processed is sent into the carbonization furnace 50 via the discharge side duct 46, where the carbonization treatment by dry distillation is performed at 200 ° C to 600 ° C.

The carbonized material heated in the carbonizing furnace 50 is discharged to the discharge duct 56, the intermittent discharge means 60, and the pipe conveyor 6.
1 and an intermittent supply means 62 through a dry distillation gas combustion furnace 63
At 850 ° C for 2 seconds or more. The ash burned and incinerated in the carbonization gas combustion furnace 63 is taken out from the treated ash take-out part 64.

On the other hand, the hot gas after heating the carbonizing furnace 50 and the drying furnace 40 is sucked by the circulation blower 48, and a part (or all) of the hot gas is returned to the hot blast furnace 27 for reuse and another part is used. Is exhausted through a heat exchanger 29, a bag filter 30, a blower 31, and a silencer 32.

The steam and the carbonization gas generated during the heat treatment in the drying furnace 40 and the carbonization furnace 50, and the gas including the steam generated in the moisture removing device 1 are burned in the carbonization gas combustion furnace 63, and then subjected to the cyclone. It is sent to the heat exchanger 29 through 65, and after using exhaust heat, it is cleaned and exhausted.

This embodiment is effective when the decrease in water content is moderated by heating by the dielectric heating means.

[0057]

According to the present invention, since the moisture-containing workpiece is directly heated by dielectric heating as described above, the following effects are obtained. (1) Since the pressure is reduced by vacuum suction in the dielectric heating means, moisture and organic substances contained in the object to be processed are effectively separated and removed. (2) An object to be treated having a high water content can be obtained by heating the object to be treated with the dielectric heating means in the pretreatment step, so that an object to be treated having a low moisture content can be effectively treated in the subsequent step such as carbonization by heating. I can do it. (3) Since the generated gas containing water vapor generated by the dielectric heating means is burned in a combustion furnace (a combustion furnace which is a heat source of the indirect heating means, a carbonization gas combustion furnace), odor removal and sterilization can be surely performed. (4) The local running cost can be reduced by locally adopting the dielectric heating unit having a large input energy.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a water removing device of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

FIG. 3 is a conceptual diagram of an object heat treatment facility having a low water content.

FIG. 4 is a conceptual diagram of another embodiment of the heat treatment facility for the object to be treated having a low water content.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Water removal apparatus 10 ... Dielectric heating means 11 ... Cylindrical container 12 ... Screw conveyor 13 ... Bearing 14 ... Beam irradiation part 15 ... Diffusion fan 16 ... Microwave power supply 17 ... Rotation drive means 18 ... Intermittent supply means 19 ... Intermittent discharge Means 20: Indirect heating furnace 21, 41, 51 ... Cylindrical body 22, 42, 52 ... Heating cylinder 23, 43, 53 ... Supply port 24, 44, 54 ... Discharge port 25, 45 ... Supply side duct 26, 46, 56 ... Discharge side duct 27 ... Hot stove 28,48 ... Circulation blower 29 ... Heat exchanger 30 ... Bag filter 31 ... Blower 32 ... Silencer 33 ... Intermittent discharge means 34,36,61 ... Pipe conveyor 35 ... Hopper 40 ... Drying furnace 50 ... carbonization furnace 60 ... intermittent discharge means 63 ... carbonization gas combustion furnace 64 ... treated ash extraction part 65 ... cyclone

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Claims (9)

[Claims] 1. A method for heat-treating a water-containing object, comprising: a water removing step of heating and evaporating and removing water from the water-containing object by heating by a heating means; and a water content reduced by the water removing step. A volume reduction step of reducing the volume of the processed product by heating with a heating means, wherein the heating means in the water removing step is a direct heating means by dielectric heating, and the heating means in the volume reduction step is indirect heating. A method for heat-treating a water-containing object to be treated, wherein 2. The method according to claim 1, wherein the volume reducing step is one or both of carbonization and incineration.
A method for heat-treating a moisture-containing workpiece as described in the above. 3. The moisture-containing coating according to claim 1, wherein a generated gas containing water vapor generated during the water removing step is suctioned to remove the water under reduced pressure, and the sucked generated gas is burned. Heat treatment method for the processed material. 4. The supply of the object to be treated to the water removing step and the discharge of the object to be treated having a low water content after the treatment are performed in a state where the outside air is shut off by an intermittent moving means having an opening / closing means. The method for heat-treating a moisture-containing workpiece according to claim 1 or 3, wherein the moisture removal step is performed under reduced pressure by vacuum suction. 5. A heat treatment facility for a moisture-containing treatment object, the heat treatment facility comprising: a moisture removal device for evaporating and removing moisture from the moisture-containing treatment object by heating; A water reducing device for directly heating the object to be processed, and the indirect heating means for indirectly heating the object to be processed. A heat treatment facility for a water-containing treatment object, comprising: 6. The water removing device is composed of a horizontal cylindrical container, provided with means for conveying and stirring the object to be processed at a lower part thereof, and a generated steam storage space at an upper part thereof, and a dielectric heating means located in the space. The heat treatment facility for treating a water-containing treatment object according to claim 5, further comprising: 7. The apparatus for heat-treating a moisture-containing object according to claim 6, wherein an outer surface of the conveying and stirring means is covered with a dielectric. 8. The moisture-containing device according to claim 5, wherein the moisture removing device comprises a horizontal cylindrical container and has an intermittent moving means at a supply port and a discharge port thereof. Heat treatment equipment for processing objects. 9. The apparatus according to claim 5, wherein the dielectric heating means comprises a plurality of beam irradiation units.