JP2001059607A - Method and system for heating matter to be treated - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep a positive pressure in a decomposition gas combustion furnace by making the pressure in a heating furnace negative with respect to the atmospheric pressure and keeping the pressure in a decomposition gas combustion furnace positive with respect to the atmospheric pressure thereby preventing leakage of decomposition gas from the heating furnace. SOLUTION: Pressure in a rotary heating furnace has a trend to become negative with respect to atmospheric pressure because the heating furnace is normally sucked by means of a blower 39 having a bug filter 38 but it has a trend to become positive upon generation of decomposition gas through heating operation. Decomposition gas in the rotary heating furnace is sucked by means of the blower 53 in a decomposition gas introducing means 50 and the pressure in the rotary heating furnace can be made negative with respect to the atmospheric pressure. The negative pressure can be regulated easily by controlling rotation of blower preferably in the range of -5 to -10 mmH2O. Pressure in a decomposition gas combustion furnace 34 is preferably kept positive (0 to +10 mmH2O) in view point of combustion conditions by introducing air and decomposition gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for heat-treating an object to be treated such as various kinds of wastes, and more particularly to a method for treating a decomposition gas generated during the heat treatment.

[0002]

2. Description of the Related Art Various wastes (industrial wastes, general wastes, etc.) to be treated contain organic substances such as halogen substances (chlorine, etc.), and various harmful substances (for example, It is known that hydrogen chloride and dioxins) are precipitated and generated and are contained in exhaust gas, and it is common practice to purify exhaust gas before it is released into the atmosphere (emission control). It has been done.

[0003] Generally, hydrogen chloride generated in a large amount by heat treatment is neutralized with caustic soda or the like and recovered with hydrochloric acid.

As a general exhaust gas purifying apparatus, there is a bag filter apparatus disclosed in Japanese Patent Application Laid-Open No. 8-108026. These apparatuses use slaked lime as a purifying agent for exhaust gas to remove hydrogen chloride and dioxins in the exhaust gas. In addition, in order to obtain the same effect, various purifying agents have recently been proposed.

[0005] However, chlorine-based gas components are also adhered and adsorbed to substances other than exhaust gas, such as slaked lime powder used in a bag filter for exhaust gas treatment, fly ash in the exhaust gas, and incineration residue (eg, incinerated ash). It is known to produce highly toxic dioxins.

On the other hand, the present inventors have proposed that organic chlorine compounds (hydrogen chloride), which is an organic substance (halogen substance such as chlorine), perform "suppression of generation" instead of conventional "suppression of emission". It has been proposed to suppress the generation of harmful substances such as hydrogen chloride, to make the exhaust gas harmless, to make the residue harmless, and to reduce the damage to the treatment equipment due to chlorine.

That is, an alkaline substance is added to and mixed with an object to be treated and heated at a predetermined temperature to decompose and precipitate hydrogen chloride, and at the same time, contact and react with the alkaline substance added and mixed to form harmless chloride. A technique for generating a replacement has been found and an application has been filed (for example, see JP-A-9-155326,
0-43713, JP-A-10-235186, JP-A-10-235187, etc.).

[0008] Further, a dechlorinating agent has been proposed in which the dechlorinating agent is made porous to increase the area for the contact reaction to enhance the reaction effect (Japanese Patent Application Laid-Open No. 10-193844).

Using these treating agents, the material to be treated is heat-treated to obtain a residue of carbide, which is used as a soil improver, a water purifier, a snow melting agent, and a heat insulator due to its porous nature. It can also be used as a recycled product in a wide range of fields, such as being used as fuel.

[0010]

When an object to be treated is heated by an external heating means in a heat treatment furnace and subjected to a thermal decomposition treatment such as a dry distillation treatment, a decomposition gas (a dry distillation gas) is generated. The regulations stipulate that the gas be burned at 850 ° C. for 2 seconds or more and discharged.

The generated gas is entirely attracted and sucked by a blower located at a later stage as an exhaust gas system, and the inside has a negative pressure tendency with respect to the atmospheric pressure. However, when a decomposition gas is generated during the heat treatment, the pressure tends to be positive with respect to the atmospheric pressure.

When a positive pressure is applied to the inside of the heat treatment furnace, a problem is a gas leak from a seal portion constituting the furnace. In particular, in the case of a rotary kiln (rotary type) provided with a rotary seal, the decomposition gas may leak from the seal portion. In this case, the condition is constantly monitored, and if the pressure becomes positive, the suction force of the blower may be increased, but the monitoring and control become complicated.

[0013] When the air is strongly sucked by the blower, the pressure inside the cracked gas combustion furnace becomes negative, and the combustion state changes. That is, combustion at 850 ° C. for 2 seconds may be difficult. Therefore, (a) means for maintaining a negative pressure in the heat treatment furnace,
(B) How to prevent a change (decrease) in combustion conditions in a cracked gas combustion furnace is an important issue.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and prevents the decomposition gas from leaking from the heat treatment furnace, and maintains the internal pressure of the decomposition gas combustion furnace at a positive pressure to burn the decomposition gas. It aims to be effective.

[0015]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a decomposition gas (exhaust gas,
When the carbonization gas is introduced into the decomposition gas combustion furnace, the pressure in the heat treatment furnace is induced to be negative with respect to the atmospheric pressure to be introduced into the decomposition gas combustion furnace. By maintaining the pressure in the gas combustion furnace at a positive pressure with respect to the atmospheric pressure, it is possible to prevent the decomposition gas from leaking from the heat treatment furnace, and to set the combustion conditions in the decomposition gas combustion furnace at 850 ° C. for 2 seconds. It allows the combustion to be maintained.

The specific means is a method of heating the object to be treated, which is put into a heat treatment furnace for thermal decomposition treatment, and the generated decomposition gas is burned in a decomposition gas combustion furnace and then discharged. The pressure in the heat treatment furnace is negative with respect to the atmospheric pressure, and the pressure in the cracked gas combustion furnace is positive with respect to the atmospheric pressure.

[0017] The negative pressure relative to atmospheric pressure of the heat treatment furnace and -5 to-10 mm H ₂ O, positive pressure relative to atmospheric pressure of the decomposition gas combustion furnace, it is desirable to 0~ + 10mmH ₂ O.

The temperature inside the heat treatment furnace is 200 ° C.
As described above, the internal temperature of the cracked gas combustion furnace is desirably 800 ° C. or higher.

It is desirable to use LPG or LNG as fuel for the heat treatment furnace and the cracked gas combustion furnace.

In the apparatus for carrying out the above method, an object to be processed is charged into a heat treatment furnace to be thermally decomposed, and the generated decomposition gas is discharged after burning in a decomposition gas combustion furnace. In the heat treatment apparatus for the object to be processed, the decomposition gas introduction means for introducing the decomposition gas into the decomposition gas combustion furnace,
A configuration is adopted in which a pressurized driving gas is ejected from a nozzle, and a decomposition gas is introduced by suction / transport force of the jet.

The above-mentioned decomposition gas introducing means uses an air ejector, and adjusts the pressure in the heat treatment furnace to a negative pressure with respect to the atmospheric pressure and the pressure in the decomposition gas combustion furnace to the atmospheric pressure by adjusting the jet of the driving gas. It is desirable to maintain a positive pressure.

[0022]

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

FIG. 1 is a conceptual diagram of a heat treatment apparatus for an object to be treated according to the present invention. The two objects of the present invention are described below. The second rotary heating furnace is provided with a function of volume reduction by carbonization or incineration treatment (hereinafter, referred to as a volume reduction furnace). Is the case.

Reference numeral 1 denotes a desalination furnace. The desalination furnace 1 includes a rotatable rotary cylinder 2 and a gas duct formed on the outer periphery of the rotary cylinder 2 to introduce a hot gas to rotate the rotary cylinder 2. A heating jacket 3 as external heating means for externally heating
Support rollers 4, 4 'for rotatably supporting the rotating cylindrical body 2 at both ends, and rotation driving means 5, 5' for rotating the rotating cylindrical body 2 are provided. A supply port 6 for carrying the object to be processed, and a discharge port 7 for discharging the object to be processed at the other end, and a feed blade (not shown) that is inclined with respect to the axis of the rotating cylinder. Are provided in the radial direction and the axial direction, and by rotation of the rotating cylindrical body 2,
The workpiece is transferred from the supply port 6 side to the discharge port 7 while stirring.

As shown in FIG. 1, for example, the rotary driving means 5 and 5 'include driving motors 5a and 5'a and a driving gear 5
b, 5'b and driven gears 2a, 2'a provided on the outer periphery of the rotary cylinder 2, and the drive motors 5a, 5'a are controlled by a motor control device (not shown).

Although the rotary drive means has been described using a gear as a means for transmitting power from a drive motor, it is not always necessary to use a gear, but a sprocket for a roller chain is provided, and the rotation is transmitted by the roller chain. You may do so. Reference numeral 8 denotes a mechanical seal, which seals a contact portion with the heating jacket 3 which is in contact with the outer periphery of the cylindrical body 2.

Reference numeral 20 denotes a volume reduction furnace having a volume reduction processing function.
The volume reduction furnace 20 has the same configuration as the desalination furnace 1. Therefore, the same parts as in the desalination furnace 1 are given the same reference numerals as those of the desalination furnace 1 in the order of 20 and their detailed description is omitted.

The desalination furnace 1 and the volume reduction furnace 20 are vertically
In addition, the supply port 26 side of the volume reduction furnace 20 is arranged on the discharge port 7 side of the desalination furnace 1. A supply duct 1 for supplying the object to be processed into the rotary cylindrical body 2 is provided on the supply port 6 side of the desalination furnace 1.
0 is provided. Reference numeral 9 denotes a rotary valve provided in the supply duct 10. The discharge port 7 and the supply port 26 of the desalination furnace 1 and the supply port 26
A communication duct 11 is provided so as to cover the object, and an object to be treated (residue) heated in the desalination furnace 1 is introduced into the volume reduction furnace 20.
Reference numeral 12 denotes a rotary valve provided at an intermediate portion of the communication duct 11.

Reference numeral 30 denotes a hot gas generating means,
And supplies the fuel such as LNG or LPG, and burns the fuel to generate hot gas. The generated hot gas is supplied to the heating jacket 23 of the volume reduction furnace 20 to heat the rotating cylindrical body 22 of the volume reduction furnace 20, and then the desalination furnace 1 is connected via the connecting pipe 31.
Is supplied into the heating jacket 3. At this time, the temperature adjusting air 32 is sent in to adjust the temperature of the hot gas.

Reference numeral 33 denotes a hopper, which feeds the mixture of the object to be treated and the dechlorinating agent, or the mixture into the rotary cylindrical body 2 of the desalination furnace 1 via the supply duct 10 while mixing.

Although not shown, the contact portion between the supply duct 10, the communication duct 11 and the communication duct 11 and the discharge duct 13 which are in rotational contact with the rotary cylinder 2 and the rotary cylinder 22, respectively. Is provided with a mechanical seal for preventing gas leakage.

Reference numeral 34 denotes a cracked gas combustion furnace, which is a cracked gas (exhaust gas) generated during the heat treatment in the desalination furnace 1 and the volume reduction furnace 20.
Is introduced through gas conduits 35 and 36, and combustible components such as tar components and residual harmful substances are burned by a burner 34a.
After being cooled by the exhaust gas cooling means 37, it is purified by the bag filter 38 and discharged from the chimney 40. This exhaust gas cooling means 3
The cooling in 7 can be performed by spraying cooling air or a cooling liquid. 39 is a blower provided in the bag filter,
The gas generated in the heat treatment furnace is sucked.

Reference numeral 41 denotes a dissolving tank, which discharges the material to be treated reduced in the volume reducing furnace 20 and the chloride and the like generated by reacting with the dechlorinating agent in the desalination furnace 1 to the discharge side duct 13, After being discharged from the damper 14, it is washed with water to remove chlorides and the like, then dehydrated by the dehydrating means 42 and dried by the drying means 43 to take out carbides and the like.

Reference numeral 44 denotes wastewater treatment means for detoxifying water from the dissolving tank 41 and water generated during dehydration.
Drain.

Incidentally, the rotary valves 9 and 12 may be constituted by intermittent sending means for opening and closing and intermittently sending the object to be processed.

The drying means 43 includes a desalination furnace 1 as a heat source.
The hot gas after heating is introduced from the exhaust pipe 45 through the gas pipe 46 and heated.

FIG. 2 is an enlarged schematic view of the cracked gas combustion furnace 34 shown in FIG. 1. Numeral 50 indicates a cracked gas introducing means, which is constituted by an air ejector. The decomposed gas introducing means 50 includes an outer cylinder 51, a nozzle member 52 provided in the outer cylinder 51, and a blower 53 for sending a pressurized driving gas to the nozzle member 52. One end of the outer cylinder 51 is disassembled. It is opened in the gas combustion furnace 34, and the other end side is a gas introduction pipe 3
It communicates with 5,36. The tip end of the nozzle member 52 is narrowed narrowly and is opened at the opening of the outer cylinder 51, and the other end is connected to the blower 53. The air from the blower 53 is ejected from the tip of the nozzle member 52, and the decomposed gas is attracted into the decomposed gas combustion furnace 34 and burned by the suction / conveyance of the jet.

Since the pressure in the rotary heating furnace is normally sucked by the blower 39 provided in the bag filter 38,
The pressure tends to be negative with respect to the atmospheric pressure, but tends to be positive when the decomposition gas is generated by the heat treatment. However, the decomposed gas in the rotary heating process is attracted by the air flow rate (flow rate) from the blower 53 of the decomposed gas introduction means 50, and can be made negative pressure with respect to the atmospheric pressure. This negative pressure value can be easily adjusted by controlling the rotation of the blower.
It is desirable to set it to 10 mmH ₂ O.

The pressure in the cracked gas combustion furnace 34 is desirably a positive pressure in view of combustion conditions, and is maintained at a positive pressure (0 to +10 mmH ₂ O) by introducing air and a cracked gas.

Next, a series of processing methods for the object to be processed will be described. First, the hot gas generating means 30 burns fuel such as LNG to generate a hot gas, and supplies the hot gas to the heating jacket 23 of the volume reduction furnace 20 to heat the rotary cylindrical body 22. It is fed into the heating jacket 3 of the salt furnace 1 to heat the rotating cylinder 2.

Next, a material containing a harmful component such as a halogen substance is crushed into fine pieces (or crushed while mixing) and a mixture of a dechlorinating agent or supplied from a hopper 33 while mixing. Desalting furnace 1 through side duct 10
Is supplied into the rotating cylindrical body 2.

In the heat treatment in the desalination furnace 1, the temperature and time at which the chlorine-based gas precipitates from the object to be treated are investigated in advance,
The properties of the object to be treated are grasped, and the treatment is performed at a temperature (for example, 200 ° C. to 350 ° C.) and time that can sufficiently cover the result of the investigation. This temperature adjustment is basically performed by the supply amount of the temperature adjustment air 32 supplied to the communication pipe 31.

The heating in the desalination furnace 1 is not burning and incineration but steaming and pyrolysis in a low oxygen atmosphere, and harmful components such as HCI gas deposited by the pyrolysis and the dechlorinating agent are not used. Is subjected to a contact reaction.

The dechlorinating agent to be mixed or added with the object to be treated is
An alkaline substance is used that at least reacts with HCI (hydrogen chloride) to form harmless chlorides. For example, Japanese Patent Application Laid-Open Nos. Hei 9-155326, Hei 10-43731 and Hei 10-235186 filed earlier by the applicant of the present application
JP-A-10-235187, JP-A-10-193
No. 844, an alkaline earth metal, an alkaline earth metal compound, an alkali metal, an alkali metal compound,
Specifically, calcium, lime, slaked lime, calcium carbonate, dolomite, silicate (such as calcium silicate), sodium hydrogen carbonate, sodium carbonate, sodium sesquicarbonate, natural soda, sodium hydroxide, potassium hydroxide,
One of potassium hydrogen carbonate and potassium carbonate is selected, or several types are mixed and used. As an amount to be used, 5 to 30% by weight based on the material to be treated is mixed or added.

For example, sodium bicarbonate (Na
When HCO ₃ ) is used, a decomposition gas of the HCl component is generated in the desalination furnace, which is the first heat treatment furnace, but immediately reacts with sodium hydrogen carbonate to produce (NaHCO ₃ ) +
(HCl) → (NaCl) + (H ₂ O) + (CO ₂ ), producing harmless sodium chloride (NaCl) and eliminating harmful HCl from the decomposition gas. This allows
The detoxification of the HCl component in the cracked gas and the detoxification of the residue are performed simultaneously.

The object (residue) after the harmful components are precipitated and detoxified is passed through a communication duct 11 and a rotary valve 12 to a rotary cylindrical body of a volume reduction furnace 20 as a second rotary heating furnace. The material is fed into the supply port 26 of 22 and is carbonized at a temperature at which the object is carbonized (paper begins to carbonize at about 350 ° C.).
The volume is reduced by heating to 00 ° C. or more by incineration.

The volume-reduced material to be treated and the sodium chloride after the reaction are discharged into the discharge duct 13 and the double damper 14.
Is discharged to the dissolving tank 41 through In this dissolving tank 41, the reduced volume of the object to be treated and the dechlorinating agent (sodium chloride) after the reaction are dissolved in water, and the sodium chloride dissolved in the water is discharged to a wastewater treatment means 44, and the remaining solids are discharged. The material is dehydrated by the dehydrating means 42 and dried by the drying means 43 to take out solid matter such as carbide. The solids taken out are separated according to their physical properties and are reused.

On the other hand, the decomposition gas (exhaust gas, dry distillation gas) generated during the heat treatment in the desalination furnace 1 and the volume reduction furnace 20 is supplied to the gas outlet pipes 35 and 36 by the decomposition gas introduction means 50.
From the furnace to the cracked gas combustion furnace 34, where it is burned.

In this decomposed gas, harmful components such as hydrogen chloride are basically removed by the reaction treatment in the desalination furnace 1, but they cannot be completely reacted for some reason and may remain in the exhaust gas. There is also. In addition, since combustible components such as tar are also contained, the gas is burned by the gas combustion means 34, then cooled by the exhaust gas cooling means 37 to a temperature lower than the allowable temperature limit of the bag filter 38, and cleaned by the bag filter 38 to form a chimney It is discharged from 40.

[0050]

As described in detail above, the present invention decomposes and deposits harmful components such as chlorine-based gas from waste materials to be treated, and contacts the deposited harmful components with a dechlorinating agent for alkaline substances. Reacts to form harmless chlorides.Effectively combines each step in the series of processes from release of generated decomposition gas to the atmosphere and volume reduction of residues, and to use heat sources effectively. As a result, a high-efficiency and safe facility can be obtained as a whole of the processing apparatus for the object to be processed, and a cracking gas introducing means is provided in the cracking gas combustion furnace, and the pressure in the rotary heating furnace is reduced to a negative pressure with respect to the atmospheric pressure. Since the pressure in the cracked gas combustion furnace is maintained at a positive pressure with respect to the atmospheric pressure, gas leakage does not occur from the mechanical seal portion at the contact portion between the rotating cylinder and each duct in the heat treatment furnace. In addition, since the amount of induced air is very small, a stable decomposition and reaction environment can be secured and maintained.

The pressure in the cracked gas combustion furnace can be maintained at a positive pressure (0 to +10 mmH ₂ O) with respect to the atmospheric pressure, and the specified combustion at 850 ° C. for 2 seconds can be maintained. To play.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an embodiment of the present invention.

FIG. 2 is an explanatory view of a cracked gas combustion furnace of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Demineralization furnace 20 ... Volume reduction furnace 2, 22 ... Rotating cylindrical body 3, 23 ... Heating jacket 4, 24 ... Support roller 5, 25 ... Rotation drive means 6, 26 ... Supply port 7, 27 ... Discharge port 8 ... Mechanical seal 9 Rotary valve 10 Supply duct 11 Communication duct 12 Rotary valve 13 Discharge duct 14 Double damper 29 Fuel tank 30 Hot gas generating means 31 Communication pipe 32 Temperature controlled air 33 Hopper 34 Gas combustion furnace 35 36 Gas introduction pipe 37 Exhaust gas cooling means 38 Bag filter 39 Blower 40 Chimney 41 Melting tank 42 Dewatering means 43 Drying means 44 Wastewater treatment means 45 Exhaust pipe 46 ... gas pipe 50 ... decomposition gas introduction means 51 ... outer cylinder 52 ... nozzle member 53 ... blower

Claims (6)

[Claims] 1. A heat treatment method for an object to be treated, wherein the object to be treated is charged into a heat treatment furnace for thermal decomposition treatment, and the generated decomposition gas is burned in a decomposition gas combustion furnace and then discharged. A method for heat treating an object to be processed, wherein the pressure in the heat treatment furnace is set to a negative pressure with respect to the atmospheric pressure, and the pressure in the cracked gas combustion furnace is set to a positive pressure with respect to the atmospheric pressure. 2. The negative pressure with respect to the atmospheric pressure in the heat treatment furnace is:
And -5 to-10 mm H ₂ O, positive pressure relative to atmospheric pressure of the decomposition gas combustion furnace, the heat treatment method according to claim 1 the processed material, wherein it has a 0~ + 10mmH ₂ O. 3. The furnace temperature of the heat treatment furnace is 200 ° C. or more,
3. The method according to claim 1, wherein the furnace temperature of the cracked gas combustion furnace is 800 ° C. or higher. 4. The heat treatment method for an object according to claim 1, wherein LPG or LNG is used as a fuel for the heat treatment furnace and the cracked gas combustion furnace. 5. A heat treatment apparatus for an object to be processed, wherein the object to be processed is charged into a heat treatment furnace to be thermally decomposed, and the generated decomposition gas is discharged after being burned in a decomposition gas combustion furnace. The cracked gas introducing means for introducing the cracked gas into the cracked gas combustion furnace ejects a pressurized driving gas from a nozzle, and introduces the cracked gas by suction / transport force of the jet. Heat treatment equipment for processed materials. 6. The decomposition gas introduction means uses an air ejector, and adjusts the pressure in the heat treatment furnace to a negative pressure with respect to the atmospheric pressure and the pressure in the decomposition gas combustion furnace to the atmospheric pressure by adjusting the jet of the driving gas. 7. The apparatus according to claim 6, wherein the apparatus is maintained at a positive pressure.