JP2000035212A - Melt treatment device for waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recover carrying-out beat of molten slag and to heat ash to be molten by the heat with high efficiency by providing a heat-exchanger to exert the latent heat of molten ash (molten stag) discharged from a melt furnace on gas and a heater to heat ash to be molten by gas discharged therefrom. SOLUTION: High temperature slug from a slug box 19 is moved to a heat- exchanger 3. The heat-exchanger is provided at a bottom with a slug discharge apparatus 20 and an air feed pipe 21 and at an upper part with a high temperature slug introduction pipe and a high temperature air discharge pipe 23. The slug discharge apparatus 20 lowers and moves high temperature slug 22 in the heat-exchanger 3 and discharges particles in the heat-exchanger 3 to the outside of the apparatus and air is supplied through an air supply pipe 21 to the heat-exchanger 3. Air increased in temperature through heat-exchange is taken out from a high temperature air discharge pipe 23 and supplied to a heater 4. This constitution recovers the carry-out heat of molten slug and heats ash to be molten by the heat, whereby high-efficient melt treatment is practicable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for melting waste such as incineration ash.

[0002]

2. Description of the Related Art Most of sludge generated in sewage treatment and garbage discharged from households are treated by incineration, and incinerated ash generated by incineration is disposed of by landfill. However, there are limits to landfill sites and it is necessary to further reduce ash volume.

[0003] In order to reduce the volume of ash, a method is generally used in which heat is applied from the outside to melt the ash into slag, and various methods have been proposed. In each of these methods, the ash is melted in the melting furnace, the generated gas is discharged from the upper part of the furnace, and the molten ash (molten slag) is allowed to flow down from the bottom of the furnace to the water tank to cool the molten slag. Discharge as solid slag. In this method, most of the heat applied from the outside is transferred from the molten slag to the cooling water in the water tank and discarded. That is, it can be said that the thermal efficiency in the melting furnace is low.

It is important to recover the heat taken out in order to improve the efficiency of the ash melting furnace.
-298715. However, the patent discloses heat recovery from generated gas, and heat recovery from molten slag has not been achieved. Specifically, in a melting furnace, usually 20
Then, the ash is received and the ash is melted by heating to about 1200 ° C., which is the melting temperature of the ash. Approximately 5 to melt 1 kg of ash
Energy of about 30 kcal is required, of which 440 kc
al is used for heating and melting ash, and 90 kcal is used for evaporating water.

On the other hand, molten ash (molten slag) carries out 350 kcal of the heat output. Conventionally, molten slag of about 1200 ° C is dropped into a water tank of about 50 ° C, and the heat of the molten slag is only converted to hot water of about 50 ° C.
There is no effective heat recovery.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly efficient method of melting waste, which recovers the heat taken out of the molten slag and heats the ash to be melted with the recovered heat. .

[0007]

As means for attaining the above object, a slag granulator for producing solid high-temperature slag particles by bringing liquid molten slag discharged from an ash melting furnace into contact with a rotating body is provided. The solid slag produced by the slag granulator is charged from the upper part of the heat exchanger and discharged from the lower part, and air is introduced from the bottom part of the heat exchanger and taken out as high-temperature air from the upper part. The air is introduced into the heater, and the ash of coarse particles separated by sieving or the large particles obtained by granulating fine ash is fed into the heater from above and brought into contact with air to heat the ash to be melted. And then supply it to the ash melting furnace.

That is, the operation of the above means is as follows.

The molten slag flowing out of the ash melting furnace contains silica, alumina, magnesia, calcia, etc.
It is a liquid at about 1 ° C and becomes solid at about 1100 ° C.
In the slag granulator, the molten slag flowing down from the ash melting furnace in a liquid state is brought into contact with a rotating body whose surface is cooled, and 1100 ° C.
It is cooled to a certain degree and solidified, and the lump is granulated into particles of 10 mm or less by a rotating blade. Water on the surface of the rotating body is formed into a thin film, and when the molten slag comes into contact with the surface, it becomes water vapor and has an effect of preventing the molten slag from sticking to the rotating body surface. By rotating the rotor at several revolutions per minute,
It has the effect of granulating the molten slag flowing down on the rotor into particles. The slag, water and evaporated water vapor that have fallen from the rotor are separated by a screen at the bottom of the granulator.

[0010] Hundreds of degrees of slag produced in the granulator is led to a heat exchanger. The heat exchanger is a moving bed type, and cools the high temperature slag received from the top while moving it downward.
On the other hand, air is supplied from the bottom of the heat exchanger to give the heat of the high-temperature slag to the air. That is, the heat exchanger has an effect of giving the heat of the high-temperature slag to the air to produce high-temperature air. In this patent, high-temperature slag and air are brought into direct contact to recover heat, but heat exchange may be an indirect method. For example, it is also possible to install a heat transfer tube in a heat exchanger, flow water in the heat transfer tube to generate pressurized steam, and flow air in the tube to generate pressurized air.

Further, heat recovery may be achieved by using a heat exchanger as a fluidized bed. In any case, any form can be used as long as the heat of the molten slag can be transferred to another substance and the energy of the substance can be effectively used. The high-temperature slag is discharged by a discharger installed at the bottom of the heat exchanger. The discharge amount is the temperature of the particles and air in the heat exchanger, the amount of high-temperature slag received by the heat exchanger, and the amount of air supply. And the like, and control is performed based on these values. Further, the temperature of the slag discharged from the heat exchanger is cooled to 40 ° C or lower, preferably 30 ° C or lower with air.

[0012] Air heated to several hundred degrees in the heat exchanger is introduced from the bottom of the heater. In the heater, the air gives heat to the ash to be melted while rising. The heater is a moving bed type, and the ash received from the top moves downward, is discharged from the bottom and is supplied to the melting furnace. In general, since ash has a small particle diameter, if it is directly introduced into a heater, it is scattered from inside the heater. Therefore, the ash is separated by a sieve, and ash having a size of several mm or more is introduced into the heater. In the case of fine ash, it is made into coarse particles by a granulator and supplied to a heater. By coarsening the ash supplied to the heater,
The amount of fly ash entrained by the heated air can be reduced. The air discharged from the heater is dedusted by a bag filter, and then guided to a refuse incinerator in a refuse treatment plant and to a gas treatment device in a melting plant.

These slag granulators for converting liquid molten slag to solid high-temperature slag, heat exchangers for recovering heat from the high-temperature slag, and heaters for heating the ash to be melted with the recovered heat are ash-melted. By incorporating into the furnace, the heat of the molten slag can be used effectively, reducing the energy required for melting the ash,
In other words, the efficiency of the melting furnace can be improved.

[0014]

(Embodiment 1) An embodiment of the present invention will be described below with reference to FIG.

The overall system is composed of an ash melting furnace 1, a slag granulator 2, a heat exchanger 3, a heater 4, a granulator 5, a gas processor 6, and a pipe connecting them.

An electromagnetic induction coil 7 is wound around the ash melting furnace 1, a slag outlet 8 for slag at the bottom, an ash supply port 9 at the top, and an exhaust gas outlet 10 at the upper part. You. The melting furnace is filled with graphite 11 as a heating element. By passing a current through the electromagnetic induction coil, an eddy current flows through the graphite and generates Joule heat, causing the graphite surface temperature to rise to 1400
About ℃. The ash 12 to be melted is supplied into the ash melting furnace 1 by a quantitative feeder 13 installed at the bottom of the heater 4.

The ash is melted in the ash melting furnace and becomes molten slag 14 which flows down into the slag granulator 2 from the outlet.
In the slag granulator 2, a water-cooled rotary blade 15 and a screen 16 are installed. The rotary wing 15 is connected to the motor 17 via a speed reducer and rotates at several revolutions per minute. In addition, rotor 1
5 is supplied with water from a water pump 18 and water is taken out from a hole opened on the surface of the rotor to form a thin water film on the surface.

The molten slag 14 flows down on the water film of the rotor 15. The molten slag at about 1200 ° C. that has reached the water film is rapidly cooled and solidified from the surface, and moves to the outside of the rotary blade, falls, and reaches the screen. On the screen, only the water that has fallen with the slag is dropped below the screen, and the slag on the screen is moved to the slag box 19. The water under the screen is circulated and used by the water pump 18, but is cooled by a cooling tower outside the system because the water temperature rises with the operation. In addition, since the amount of water in the slag granulator 2 decreases due to evaporation, the slag granulator 2 is replenished to a constant level.

The high-temperature slag in the slag box 19 is supplied to the heat exchanger 3
Move in. Slag discharger 2 at the bottom of the heat exchanger
0, an air supply pipe 21 and a high-temperature slag introduction pipe and a high-temperature air discharge pipe are installed at the upper part. The slag discharger 20 moves down the high-temperature slag 22 in the heat exchanger 3, discharges particles in the heat exchanger outside the device, and supplies air to the heat exchanger 3 from the air supply pipe 21. The high-temperature air is taken out of the high-temperature air discharge pipe 23 and sent to the heater 4. The bottom of the heater 4 is connected to one end of a fixed-quantity feeder 13 for discharging ash in a fixed amount and one end of a high-temperature air discharge pipe 23. In the upper part, a granulated ash supply pipe 2 from the granulator 5 is provided.
4. The air discharge pipe 25 is connected by opening.

The ash granulated to several millimeters moves from top to bottom in the heater 4, and hot air flows upward from below, where the granulated ash is heated. After the heated air gives heat to the ash side, the entrained solids are separated in a gas treatment unit and reach the subsequent equipment. The separated solid is returned to the granulator 5 by the return pipe 26 and granulated.

In this system, the heat of the molten slag is
About kcal can be recovered. That is, the amount of heat 53 required for melting the ash
This means that 37.7% was recovered for 0 kcal.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to FIG.

Generally, refuse incineration ash contains about 25 to 30% of water and is dried before melting. Example 2 is a system for drying ash with heat recovered from molten slag.

The overall system is an ash melting furnace 1, a heat exchanger 3,
It comprises a heater 4, a granulating device 5, a gas processing device 6, a dryer 7 and a pipe connecting them. An electromagnetic induction coil 7 is wound around the ash melting furnace 1, a slag outlet 8 for molten slag is provided at a bottom, an ash supply port 9 is provided at an upper part, and an exhaust gas outlet 10 is provided at an upper part.

The melting furnace is filled with graphite 11 as a heating element. By passing a current through the electromagnetic induction coil, an eddy current flows through the graphite to generate Joule heat, and the graphite surface temperature becomes about 1400 ° C. The dry ash 28 to be melted is supplied to the ash melting furnace 1 by the quantitative feeder 13 installed at the bottom of the ash hopper 29.
Supply within. The ash is melted in the ash melting furnace and becomes molten slag 14 and flows down into the slag granulator 2 from the port.

In the slag granulator 2, a water-cooled rotor 1
5, a screen 16 is provided. The rotary wing 15 is connected to the motor 17 via a speed reducer and rotates at several revolutions per minute.
Further, water is supplied to the rotor 15 from a water pump 18, and water is discharged from a hole opened on the surface of the rotor to form a thin water film on the surface.

The molten slag 14 flows down on the water film of the rotor 15. The molten slag of about 1200 ° C. that has reached the water film is rapidly cooled and solidified from the surface, moves to the outside of the rotary wings, falls and reaches the screen. On the screen, together with the slag, only the dropped water is dropped below the screen, and the slag on the screen is moved to the slag box 19.
The water under the screen is circulated and used by the water pump 18, but as the water temperature rises with the operation, it is cooled by a cooling tower outside the system. In addition, since the amount of water in the slag granulator 2 decreases due to evaporation, the slag granulator 2 is replenished to a constant level.

The high-temperature slag in the slag box 19 is supplied to the heat exchanger 3
Move in. Slag discharger 2 at the bottom of the heat exchanger
0, an air supply pipe 21 and a high-temperature slag introduction pipe and a high-temperature air discharge pipe are installed at the upper part. The slag discharger 20 moves down the high-temperature slag 22 in the heat exchanger 3, discharges particles in the heat exchanger outside the heat exchanger, and supplies air to the heat exchanger 3 from the air supply pipe 21. The high temperature air is taken out from the high temperature air discharge pipe 23 by the heat exchange, and the ash dryer 27 is used.
Send to The dried ash 28 dried in the dryer 27 is sent to an ash hopper 29.

In this system, ash containing 30% moisture can be dried to 5% moisture, and the heat of evaporation of moisture in the melting furnace can be reduced.

[0030]

According to the present invention, the heat taken out of the molten slag can be recovered, and the ash to be melted can be heated by the recovered heat, so that the waste can be efficiently melted.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system of a waste melting method according to an embodiment of the present invention.

FIG. 2 is a diagram showing a system of a waste melting method including a dryer according to an embodiment of the present invention.

[Explanation of symbols]

1: Ash melting furnace, 2: Slag granulator, 3: Heat exchanger, 4:
Heater, 5: Granulation device, 6: Gas treatment device, 7: Electromagnetic induction coil, 8: Izumiguchi, 9: Ash supply port, 10: Exhaust gas outlet, 11: Graphite, 12: Ash, 13: Quantitative feeder , 14
... molten slag, 15 ... rotor, 16 ... screen, 17
... Motor, 18 ... Water pump, 19 ... Slag box, 20 ... Slag discharger, 21 ... Air supply pipe, 22 ... High temperature slag, 2
3 ... high-temperature air discharge pipe, 24 ... granulated ash supply pipe, 25 ... air discharge pipe, 26 ... return pipe, 27 ... dryer, 28 ... dry ash,
29 ... Ash hopper.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Koji Sato, Inventor 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Hisayuki Orita 7-1 Omikacho, Hitachi City, Ibaraki Prefecture No. 1 Hitachi, Ltd., Hitachi Research Laboratory (72) Inventor Osamu Ito 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor Koichi Tatemura Hitachi, Ibaraki Prefecture 3-1-1 Sachimachi F-term in Hitachi Works, Ltd. Hitachi Plant (Reference) 3K023 QA06 QB09 QC05 3K061 NB09 NB10 NB13 NB15 NB16 NB18 ND02 ND12

Claims (5)

[Claims] An apparatus for melting waste such as refuse incineration ash, sludge incineration ash and the like, wherein the latent heat of the molten ash (molten slag) discharged from the melting furnace is supplied to the gas and the heat exchanger is discharged from the heat exchanger. A waste melting treatment apparatus comprising a heater for heating ash to be melted by gas. 2. A slag granulator for producing solid slag particles by contacting liquid molten slag discharged from a melting furnace with a rotating body in a melting treatment apparatus for waste such as refuse incineration ash and sludge incineration ash. A waste melting treatment device provided. 3. The heat exchanger according to claim 1, wherein the solid slag produced by the slag granulator is introduced into the heat exchanger from the upper part, and the solid slag is moved downward in the heat exchanger and discharged from the lower part. A waste melting treatment device characterized in that air is introduced from inside and discharged from the upper part as high-temperature air. 4. A heater according to claim 1, wherein coarse particles of ash separated by sieving or large particles obtained by granulating fine ash are fed into the heater from above, and the coarse particles and large particles are passed downward in the heater. A waste melting treatment apparatus characterized in that the waste water is supplied to a melting furnace from a lower portion, while high-temperature air from a heat exchanger is introduced from a bottom portion and discharged from an upper portion. 5. The method according to claim 2, wherein the surface of the rotating body in contact with the molten slag has a structure in which a water film is formed, and water and solid slag dropped from the surface of the rotating body are separated by a lower screen. Characteristic waste melting equipment.