JPS6349127B2 - - Google Patents

Description

Detailed Description of the Invention The present invention is designed to prevent heavy metals from flowing out when industrial waste such as sewage sludge, or intermediately processed products obtained by drying and incinerating or pulverizing them as necessary, are used in landfills. Regarding the method of incinerating or melting industrial waste or making it available for use as construction aggregate, etc., in detail, industrial waste or its intermediate processed materials are burned or melted in the upper part of a high-temperature hearth made of carbon-based combustible materials. In addition to incinerating and melting
The present invention relates to a waste melting method in which combustion exhaust gas is discharged into an ascending passage provided with an upwardly expanding portion.

The above method involves supplying a large amount of combustion oxygen-containing gas to carbon-based combustible materials in order to obtain the high temperature necessary for melting waste in the high-temperature hearth. Even if the combustion exhaust gas is ejected at high speed, the action of the upwardly expanding portion of the ascending channel reduces the upward flow velocity of the combustion exhaust gas in the ascending channel, resulting in dust entrainment in the combustion exhaust gas, resulting in exhaust dust pollution and blockages in the exhaust system. The aim is to prevent such troubles.

However, until now, no technology has been established regarding the level at which the industrial waste and intermediately treated products fed onto the high-temperature hearth should be filled in the furnace to achieve good melting processing.

As a result, the intended purpose of preventing dust entrainment into the combustion exhaust gas in the ascending flow path is not fully achieved, resulting in unexpected exhaust dust pollution and problems with the exhaust system, and sometimes industrial The supply of waste and intermediately processed materials was not carried out smoothly, which sometimes caused problems in the melting process.

The purpose of the present invention is to investigate the causes of the conventional troubles as described above, to reliably prevent dust from being entrained in the combustion exhaust gas in the ascending flow path, and to effectively transport industrial waste and intermediately processed materials to the high-temperature hearth. The aim is to ensure the supply of

The characteristic means of the present invention is to maintain a state in which the upwardly expanding portion formed in the ascending passage for flue gas above the high-temperature hearth is filled with industrial waste and intermediately treated materials up to almost the upper end thereof. The functions and effects are as follows.

In other words, after investigating the cause of the above-mentioned conventional trouble through various experiments, the following facts (a) and (b) were found.

(b) If the upper end of the in-furnace packed bed for industrial waste or intermediate treatment is lower than the upper end of the upper expanding part, the area of the top end of the packed bed will become smaller, and the gas ejection speed from the top of the packed bed will decrease. As the dust grows larger, it tends to be blown up from the packed bed, and once the dust is blown up into the upward flow path, even if the gas flow rate decreases, most of the blown up dust will not descend under its own weight. It will be entrained in the combustion exhaust gas.

(b) If the upper end of the in-furnace packed bed for industrial waste or intermediate treatment is made higher than the upper end of the upper expanding part, the flow resistance will increase around the packed bed, making it difficult for combustion exhaust gas to flow. The gas ejection velocity from the upper end of the central portion increases, and dust is entrained with the combustion exhaust gas for the reason explained in item (a) above. Furthermore, the packed bed becomes compacted at the lower end level of the upwardly expanding portion, causing a bridging phenomenon, which prevents industrial waste and intermediately processed materials from being smoothly supplied to the high-temperature hearth.

Therefore, based on the above-mentioned new knowledge, we maintained a state in which the top of the packed bed in the furnace for industrial waste and intermediate treatment materials almost coincided with the top of the upper expansion part, and the gas ejection speed from the top of the packed bed was sufficiently increased. We were able to confirm the fact that the dust can be stably maintained at a small size, reliably suppressing entrainment of dust into the combustion exhaust gas, and reliably facilitating the supply of industrial waste and intermediate treatment materials to the high-temperature hearth.

As a result, there is no exhaust dust pollution caused by dust entrained in the combustion exhaust gas, and no problems with the exhaust system.
In addition, it has become possible to reliably perform good waste melting processing while smoothly supplying industrial waste and intermediate treatment materials to the high-temperature hearth.

Next, examples will be shown with reference to drawings.

A melting furnace for incinerating and melting industrial waste, such as dried sewage sludge, includes a combustion part 2 for forming a high-temperature hearth 1 with a carbon-based combustible material, such as coke, and a reflective type or other type. A melt extraction furnace body 3 is provided on a pedestal 4 in communication with the combustion section 2 near the bottom, and a bottom portion 2a of the combustion section 2 is provided.
It is configured to be openable and closable so that coke combustion slag can be taken out, and a flow path 5 for combustion exhaust gas is provided.
In order to form a portion 5a that expands upward immediately above the high temperature hearth 1 on the starting end side thereof, and to connect it above the high temperature hearth 1, and to form the high temperature hearth 1. A dual-purpose flow passage 6 for supplying coke and dry sludge to the upper surface of the high-temperature hearth 1 is positioned with its flow opening near the top of the high-temperature hearth 1, and its flow extension line is connected to the high-temperature furnace 1. It is connected to the ascending flow path 5 for exhaust gas in a downwardly inclined manner so as to face near the center of the upper surface of the bed 1, so that the dried sludge is evenly supplied to the upper surface of the high temperature hearth 1, and the combustion A combustion device 7 for igniting the coke supplied to the combustion section 2 and a tuyere 9 for supplying oxygen-containing gas for combustion from a heat exchanger (not shown) for utilizing waste gas waste heat are connected to the combustion section 2, respectively. An oxygen-containing gas supply pipe 10 is provided in the furnace body 3, and the supply amount of oxygen-containing gas for combustion from the tuyere 9 that supplies the high-temperature hearth 1 is controlled so that a relatively large amount of impurity is present in the combustion gas. In order to incinerate the dried sludge in a state containing completely combustible components, the supply amount is set to be small, and a state is maintained in which the dry sludge is filled almost to the upper end of the upper expanding portion 5a of the upper surface of the high temperature hearth 1. In this way, dry sludge is evenly supplied to the upper surface of the high-temperature hearth 1, and it is incinerated and melted in the upper part of the high-temperature hearth 1 in a state of insufficient oxygen gas.
The molten material is taken out from the lower side of the high-temperature hearth 1 to the furnace body 3, and by reducing the amount of oxygen-containing gas supplied for combustion to reduce the amount of combustion exhaust gas generated, the molten material is transferred to the upper surface of the sludge combustion layer. The blowing velocity of the combustion exhaust gas is reduced to suppress dust scattering, and the cross-sectional diameter of the ascending passage 5 is increased to reduce the ascending flow velocity of the exhaust gas, and the height of the passage is increased to straighten the exhaust gas. By doing so, the separation performance due to the drop of the dust's own weight is improved, and the synergistic effect of these factors allows the dust to be effectively separated and removed, and the combustion exhaust gas is made to flow out from the upper part of the ascending passage 5. .

The molten material taken out into the furnace body 3 is transferred to the first and second
The high-temperature exhaust gas from the furnace body 3 is appropriately collected from the slag outlets 11 and 12, and a part of it is passed through the flow path 1.
3 to the rising flow path 5, and the remainder to the flow path 1.
6 from the ascending channel 5 to the descending inclined channel 1
In the downstream flow path 17 of the cyclone 15 connected to 4,
The heat exchanger is provided in the flow path 17, and an air supply pipe 18 is connected near the connecting portion of the flow paths 16 and 17 to post-combust the incompletely combusted exhaust gas.

Supply path 1 for high temperature exhaust gas to the ascending flow path 5
3 is provided with a flow rate control valve V, and an exhaust gas temperature detection device 19 is provided on the starting end side of the downwardly inclined flow path 14 for exhaust gas, and the amount of exhaust gas supplied by the control valve V is determined based on information from this temperature detection device 19. A control mechanism 20 for automatic adjustment is provided to prevent moisture in the exhaust gas from condensing on the flow paths 5, 14, 16 and the inner wall surface of the cyclone 15, or to facilitate post-combustion of the exhaust gas. The exhaust gas temperature detected by the temperature detection device 19 is maintained within a set range.

In addition, various carbon-based combustible materials such as graphite electrode scraps can be used to form the high-temperature hearth 1, and the above-mentioned melting furnace can also be used in addition to sewage sludge, such as tire scraps,
Various industrial wastes such as municipal waste incineration ash and waste catalysts, as well as their intermediate products, can be treated.

[Brief explanation of drawings]

The drawing is an overall vertical sectional side view showing an embodiment of a melting furnace used in the waste melting method according to the present invention. 1... High-temperature hearth, 5... Exhaust gas ascending channel, 5a
...The upper expanding part.

Claims (1)

[Claims] 1 High-temperature hearth made of carbon-based combustible material 1
A waste melting method in which industrial waste or its intermediate treatment is incinerated and melted in the upper part of the industrial waste or its intermediate treatment, and the combustion exhaust gas is discharged into an ascending passage 5 provided with an upper expanding portion 5a. A waste melting method characterized by maintaining a state in which the material is filled to almost the upper end of the upper expanding portion 5a.