JP2629117B2 - Waste melting furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermediate treatment obtained by using a massive carbon-based combustible material such as coke as a heat source, municipal waste, various industrial wastes, or dewatering, drying, incineration, crushing and the like thereof. The present invention relates to a melting furnace for heating and melting an object and recovering it as a civil engineering material, a concrete fine aggregate, and a slag material for a surface decorative aggregate.

[0002]

2. Description of the Related Art In order to melt such waste, coke-blended waste is charged from the top of a shaft furnace, and an oxygen-containing gas or an oxygen-enriched gas is blown into the furnace through tuyeres. The carbonaceous matter generated by the heat and pyrolysis is burned at a high temperature in a high-temperature hearth, and descends sequentially in a drying zone, a dry distillation gasification zone and a combustion melting zone in the furnace to form molten slag. The melting furnace itself in which the waste packed bed in the inside is raised as a countercurrent to recover as a combustible gas is disclosed in JP-B-52-24790, JP-B-55-21923, and JP-A-60-19723.
No. 23714.

[0003] The first public technology mentioned above is 40%
The above-described gas containing oxygen is injected to recover the gas, the molten slag, and the molten metal. Also,
The second is to replenish the lime source with the waste and adjust the slag composition.

[0004] Furthermore, the third method is to melt fine industrial waste and intermediate treatment products thereof, such as incineration ash of waste and dust collected from a melting furnace, by preventing troubles caused by scattering of dust. It is devised so that it can be done.

However, when the waste is melted in the melting furnace, the properties of the gas generated from the melting furnace fluctuate due to fluctuations in the properties of the waste and furnace conditions in the melting furnace. This causes problems such as inducing fluctuations in combustion of the fuel and causing fluctuations in the amount of recovered steam.

Further, fluctuations in the amount of flue gas and the temperature of flue gas in the secondary combustion furnace cause problems such as instability of exhaust gas treatment characteristics such as NOx removal and HCl removal in subsequent processes.

[0007] However, no method has been proposed to solve these problems by the conventional disclosed technology. That is, the first and second disclosed technologies describe the operating conditions of the melting furnace main body, and do not provide a technology relating to stabilization of fluctuations in the post-process.

On the other hand, as a result of investigations by the present inventors and the like, a part of combustibles in wastes is carbonized and discharged as gas, and a part of air and oxygen blown from tuyeres at a lower part of the furnace. However, it was found that most of the remaining combustibles were discharged as combustible dust from the top of the melting furnace. Furthermore, it became clear that the amount of flammable dust emitted from the top of the melting furnace fluctuates over time due to the nature of the waste and fluctuations in the furnace conditions of the melting furnace. However, it became clear that the calorific value of the gas generated from the melting furnace and the fluctuation of the generated amount were small.

Therefore, it is possible to stabilize the post-process after the secondary combustion furnace by suppressing the fluctuation by a method such as collecting combustible dust generated from the melting furnace.

[0010] The third disclosed technique provides a technique of collecting dust discharged from a melting furnace and blowing it into the melting furnace again to suppress the fluctuation of dust generated from the melting furnace. However, it does not provide a technique for stabilizing the secondary combustion.

Furthermore, when collecting combustible dust in the gas generated from the melting furnace, the generated gas contains low-boiling substances such as tar, so that it adheres to the flow path due to a decrease in gas temperature. In addition, the combustible dust has a very fine property and is difficult to collect.

[0012]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to collect flammable dust scattered from a melting furnace, thereby suppressing the fluctuation of the flammable dust and reducing the exhaust gas amount and temperature fluctuation of a secondary combustion furnace. An object of the present invention is to provide a melting furnace capable of suppressing energy consumption, stably recovering energy, and stabilizing an exhaust gas treatment process.

In collecting flammable dust,
It is an object of the present invention to provide a device for collecting fine combustible dust while avoiding a trouble of adhering a low-boiling substance such as tar contained in gas to a flow path or the like.

Further, when the collected dust is burned in a secondary combustion furnace, an apparatus for controlling the amount of cut-out dust and the like for stabilizing the amount of steam recovered from the exhaust gas is provided.

[0015]

In order to solve the above-mentioned problems, the present invention is characterized in that a charging port is installed at an upper part, a tuyere is installed at a lower part, and an exhaust gas discharge pipe is installed at a furnace top part. The exhaust gas discharge pipe is connected to a secondary combustion furnace in a shaft furnace type waste melting furnace having a discharge hole provided at a lower part, and a dust collecting device is installed in the middle of the pipe, A dust storage tank is installed below, and a powder cutting device is installed below the storage tank, and connected from the cutting device to the secondary combustion furnace via a dust supply pipe, and dust is conveyed along the dust supply pipe. The equipment was installed.

[0016]

According to the present invention, a dust collecting device, a storage tank for the collected dust, and a powder cutting device for cutting the dust out of the pipe for introducing the secondary combustion furnace and discharging the gas generated from the melting furnace are provided. By installing a dust supply pipe that blows the dust into the secondary combustion furnace, dust generated from the melting furnace is collected by a dust collection device, temporarily stored in a storage tank, and a powder cutting device is used from the storage tank. By cutting out the dust in a fixed amount and blowing the cut out dust into the secondary combustion furnace to burn it, it is possible to suppress the fluctuation of the combustible dust scattered from the melting furnace. Therefore, by stabilizing the amount of combustible dust burned in the secondary combustion furnace, it becomes possible to stabilize the recovered steam from the combustion exhaust gas. Further, by stabilizing the amount and temperature of the exhaust gas, it is possible to stabilize the exhaust gas treatment process.

[0017]

FIG. 1 shows an embodiment of the present invention using coke as a massive carbon-based combustible material.

In FIG. 1, waste, coke and lime are charged into the melting furnace 1 from a charging device 4 provided at the upper part of the melting furnace 1. Air supply pipe 3a and oxygen supply pipe 3 connected to tuyeres 2 provided around the lower part of melting furnace 1.
Air and oxygen are respectively supplied through b. The supply amounts of the air and oxygen are controlled by an air flow control valve 21a and an oxygen flow control valve 21b, respectively.

In the melting furnace 1, a part of the combustible portion of coke and waste is burned, and the ash and non-combustible materials are heated to a high temperature to be in a molten state and discharged from the slag discharge hole 5 to the outside of the furnace. . Gas and dust generated in the melting furnace are discharged from a gas discharge pipe 6 provided at the furnace top of the melting furnace 1.

The gas discharge pipe 6 is provided with a dust collecting device 7 for collecting dust in the gas. The collected dust is temporarily stored in a storage tank 8 and then cut out from a cutting device 9. The secondary combustion furnace 1 is discharged and passes through a dust supply pipe 10.
3. Further, a gas for conveying dust is supplied from the carrier gas supply pipe 11. In this embodiment, the dust is transported by the transport gas, but a mechanical transport device such as a screw conveyor can also be employed.

On the other hand, the gas that has passed through the dust collector 7 is supplied to the secondary combustion furnace 13 through the gas pipe 12.

Combustion air is supplied to the secondary combustion furnace 13 from an air supply pipe 14, mixed with gas and combustible dust, and burned in the furnace.

The combustion exhaust gas passes through an exhaust gas pipe 15 and is introduced into a boiler 16 where the exhaust heat is recovered. After the dust and pollutants are removed by a dust collector 17 and a smoke cleaning device 18, the combustion exhaust gas passes through a blower 19. Are discharged from the chimney 20. The amount of steam generated by the boiler 16 is measured by a steam flow meter 25.

Table 1 shows the properties of combustible dust generated from the melting furnace.

[0025]

[Table 1] As is evident from Table 1, the average particle size of combustible dust (the weight on the sieve is 50%) is 30 to 60 μm, and the dust collecting device 7 is capable of collecting such small-sized dust. A collector was used. In the embodiment in which the cyclone is installed, it is possible to collect 70 to 90% of combustible dust by the cyclone collecting device.

Table 1 shows an example of municipal waste as waste, but the particle diameter of dust was almost the same for other industrial waste.

An electric heating type heating device 24 was installed on the outer wall of the dust collecting device, and was controlled by a temperature control device 23 so that the temperature measured by the thermometer 22 became 200 ° C. or more. It is possible to prevent such a problem that the tar component in the gas is condensed by the heating device and adheres to the inner wall of the flow path. In another embodiment, the temperature of the dust collecting device is 1
At 80 ° C., tar was condensed, dust adhered and grew, and operation was impossible.

The capacity of the storage tank 8 is set to a capacity for 2 to 4 hours as a capacity required for absorbing fluctuations from the cycle of the fluctuation in the amount of combustible dust collected. The time for drying and carbonizing the waste charged in the melting furnace is 2 to 4 hours, and therefore, it is considered that the fluctuation in the amount of combustible dust collected also fluctuates at substantially the same cycle.

When combustible dust is cut out from the storage tank, the amount of combustible dust generated is measured by the weighing device 26, and
The cut-out amount is controlled by the control device 27 so as to have an average value of 4 hours.

[0030]

According to the present invention, the following effects can be realized.

(1) In the present invention, dust is collected by a dust collecting device installed in the middle of a pipe for introducing gas generated from a melting furnace into a secondary combustion furnace, and the collected dust is temporarily stored in a storage tank. Then, the dust is quantitatively cut out from the storage tank by the powder cutting device and blown into the secondary combustion furnace for combustion, whereby fluctuations of combustible dust scattered from the melting furnace can be suppressed. By suppressing the variation in the amount of scattered combustible dust, the amount of exhaust gas and the temperature of the secondary combustion furnace are stabilized, and the amount of steam collected by the boiler is stabilized. The amount of power generation is stabilized by stabilizing the amount of steam.

(2) Particle size is 30 to 30 depending on the dust collecting device
60 μm combustible dust can be collected,
It is possible to collect most of the combustible dust in the gas generated from the melting furnace. Therefore, it is possible to suppress the fluctuation of the scattered amount of combustible dust from the melting furnace.

(3) The pipe wall of the flow path of the generated gas is removed by a heat retaining device or a heating device installed in the dust collecting device.
By maintaining the temperature at 00 ° C. or higher, it is possible to prevent the tar contained in the gas generated from the melting furnace from condensing and preventing dust from adhering to the dust collecting device and the flow path.

(4) The time average value of the fluctuation cycle of the trapped amount of combustible dust is obtained, and the amount of air blown into the secondary combustion furnace is suppressed by the average value to stabilize the combustion amount of the secondary combustion furnace. And the recovered steam from the exhaust gas can be stabilized.

(5) By suppressing fluctuations in the amount of dust generated in the melting furnace, the amount and temperature of exhaust gas from the secondary combustion furnace can be stabilized, and the properties of exhaust gas at the outlet of the smoke washing device can be stabilized. It becomes possible to make it.

[Brief description of the drawings]

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

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Melting furnace 2 Tuyere 3a Air supply pipe 3b Oxygen supply pipe 4 Charging device 5 Slag discharge hole 6 Gas discharge pipe 7 Dust collection device 8 Storage tank 9 Cut-out device 10 Dust supply pipe 11 Carrier gas supply pipe 12 Gas pipe 13 Secondary combustion furnace 14 Air supply pipe 15 Exhaust gas pipe 16 Boiler 17 Dust collector 18 Smoke washing device 19 Blower 20 Chimney 21a Air flow control valve 21b Oxygen flow control valve 22 Thermometer 23 Temperature control device 24 Heating device 25 Steam flow meter 26 Weighing Device 27 Control device

Claims (1)

(57) [Claims] 1. A shaft furnace type waste melting furnace in which a charging inlet is installed at an upper part, a tuyere is installed at a lower part, an exhaust gas discharge pipe is installed at a furnace top part, and an exhaust hole is installed at a lower part. The exhaust gas discharge pipe is connected to a secondary combustion furnace, a dust collecting device is provided in the middle of the pipe, a dust storage tank is provided below the collecting device, and a powder cutting device is provided below the storage tank. A waste melting furnace, wherein a dust supply pipe is installed from the cut-out device to the secondary combustion furnace via a dust supply pipe, and a dust transfer device is installed in the dust supply pipe.