JP2006207911A - Operation method of waste melting furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operation method of a waste melting furnace capable of surely reducing usage of cokes by securing combustion before tuyere even when the quantity of combustible dust is changed or shorted. <P>SOLUTION: In this operation method of the waste melting furnace for catching the combustible dust scattered from the waste melting furnace where a plurality of tuyeres No.1-No.6 are arranged at an outer periphery of a furnace bottom portion at intervals, and supplying the same into the waste melting furnace from the tuyere, the combustible material excluding the combustible dust are also supplied with the combustible dust. A mole ratio of the quantity of oxygen supplied from a lower tuyere and the quantity of oxygen necessary for burning the cokes, the combustible dust and the combustible material excluding the combustible dust is 0.5-1.0. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of operating a waste melting furnace capable of reducing the amount of coke used by blowing other combustible materials into the waste melting furnace from the tuyere together with combustible dust scattered from the waste melting furnace.

  As a processing method for waste such as general waste and industrial waste, waste melting processing is used in which it is dried, pyrolyzed, burned and melted in a waste melting furnace to form slag and metal. In the waste melting treatment, waste is thrown into the waste melting furnace together with coke and limestone, which are auxiliary materials, and oxygen-enriched air is blown from a plurality of tuyere arranged at intervals around the lower part of the furnace. The slag and metal are discharged from the tap through the process of drying, pyrolysis, combustion and melting.

  The combustible matter in the waste is pyrolyzed and discharged as a pyrolysis gas from the duct at the top of the waste melting furnace, and the combustible dust in the pyrolysis gas is collected by a dust remover such as a cyclone. As a method for reducing the amount of coke used in a waste melting furnace, there is a tuyere blowing technique for combustible dust. This technology collects combustible dust scattered from a waste melting furnace, blows the collected combustible dust from the tuyere, and burns the combustible dust in front of the tuyere. Since it becomes a heat source for drying and raising the temperature of the product, it is possible to reduce coke which has been a heat source for drying, raising the temperature and melting the charged material (see Patent Document 1).

  The blowing from the tuyere of combustible dust scattered in a waste melting furnace is disclosed in Patent Documents 2 to 4.

  FIG. 8 is a schematic view showing an outline of a conventional waste melting furnace described in Patent Document 2, and FIG. 9 is a schematic view showing a conventional tuyere blowing example.

  8 and 9, a plurality of tuyere 13 are arranged at intervals on the outer periphery of the bottom of the waste melting furnace 1, and waste, coke, and limestone are charged into the waste melting furnace 1, Oxygen-enriched air is blown from the tuyere 13, and the waste is discharged, slag and metal are discharged from the outlet 14 through the processes of drying, pyrolysis, combustion, and melting.

  The combustible dust scattered from the waste melting furnace 1 is collected by the dust remover 2 and stored in the combustible dust hopper 3. When a predetermined amount of combustible dust is stored in the combustible dust hopper 3, the damper is opened, and the combustible dust falls to the intermediate hopper 7 through the screw conveyor 4, the water-cooled screw conveyor 5, and the sieve device 6. In the intermediate hopper 7, the upper damper 8 and the lower damper 9 are alternately opened and closed to drop the combustible dust into the combustible dust blowing device 10. All the combustible dust in the combustible dust blowing device 10 is adjusted through the piping 14 by the blower 11 by adjusting the rotational speed of the circle feeder 12 by the motor M and adjusting the blow amount of the combustible dust (FIG. 9). In No. 1-6), blowing is performed.

The amount of coke used is determined by the amount of flammable dust collected, but the amount of flammable dust collected varies depending on the composition of the waste to be treated. The necessary and sufficient amount may not be obtained. As a result, the fluidity of the melt is deteriorated due to a temporary shortage of coke, and the amount of reduction in the amount of coke used is limited.
JP 2001-21123 A JP 2001-108209 A JP 2002-267130 A JP 2002-267121 A

  In that case, it can be considered that solid fuel such as coke powder or biomass is blown together with combustible dust as external fuel. However, if the appropriate amount is blown, the amount of coke used can be reduced. On the contrary, when the amount is small, there is a problem that the effect of blowing does not appear.

  Therefore, the present invention provides a method for operating a waste melting furnace that can ensure the amount of combustion before the tuyere and reliably reduce the amount of coke used even when the amount of combustible dust varies or is insufficient. It is.

  The operation method of the waste melting furnace of the present invention is to collect combustible dust scattered from a waste melting furnace in which a plurality of tuyere are arranged at intervals on the outer periphery of the bottom of the furnace, and in the waste melting furnace In the method of blowing from the tuyere, a combustible material other than the combustible dust is blown together with the combustible dust.

The molar ratio between the amount of oxygen blown from the lower tuyere and the amount of oxygen necessary for combustion of combustibles other than coke, combustible dust, and combustible dust is set to 0.5 to 1.0. Here, the molar ratio of the oxygen amount is
Molar ratio = Theoretical combustion oxygen amount calculated from the carbon amount of (flammable dust and combustible materials other than combustible dust) / total oxygen amount blown from the lower tuyere (air blown air and air blown oxygen)
It is.

  Blow flammable dust and combustible materials other than flammable dust through separate tuyere. At that time, the blown oxygen amount of each tuyere is set to 0.5 to 1.0 as the molar ratio of the oxygen amount necessary for combustion of combustibles other than coke, combustible dust, and combustible dust.

  Combustion in front of the tuyere even when the amount of combustible dust varies or is insufficient by blowing combustible dust and other combustible materials (hereinafter referred to as “other combustible materials”) into the furnace. By ensuring this, the amount of coke used can be reliably reduced.

  Other combustible materials are combustible materials such as solid fuels such as coke powder, powdered biomass, and waste plastics, and can be used regardless of carbides or non-carbonized materials.

  By setting the molar ratio of the blown oxygen amount at the tuyere to 0.5 to 1.0, the combustible material blown in reliably can be burned to prevent re-scattering and to reduce coke. If the molar ratio of oxygen is less than 0.5, the oxygen supplied from the tuyere starts to react with coke after burning the combustible dust, the height of the coke bed becomes lower, and the coke bed at the bottom of the furnace Becomes uneven, the melt temperature decreases, and stable operation becomes difficult. On the contrary, when the molar ratio of the oxygen amount exceeds 1.0, the combustible dust is not completely combusted before the tuyere, and the remaining combustible dust rides on the air current and is scattered again from the melting furnace. As a result, not only does the amount of flammable dust collected increase, but the amount of flammable dust that passes through the dust remover also increases, so the amount of dust collected in the downstream combustion chamber, boiler, and dust collector Will increase.

  The present invention ensures the amount of combustion before the tuyere even when the amount of combustible dust fluctuates or is insufficient by blowing in combustible materials such as coke powder and combustible materials such as powdered biomass from the tuyere. By doing so, the amount of coke used can be surely reduced.

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

  FIG. 1 is a schematic view showing an outline of a waste melting furnace for carrying out the present invention, and FIG. 2 is a schematic view showing an example of blowing the tuyere.

  As in the conventional example shown in FIGS. 8 and 9, a plurality of tuyere 13 are arranged at intervals on the outer periphery of the bottom of the waste melting furnace 1, and the waste melting furnace 1 is provided with waste and coke. Limestone is introduced, oxygen-enriched air is blown from the tuyere 13, and the waste is discharged, slag and metal are discharged from the outlet 14 through processes of drying, thermal decomposition, combustion, and melting.

  The combustible dust generated and scattered in the waste melting furnace 1 is collected by a dust remover 2 such as a cyclone, and the collected combustible dust is temporarily stored in the combustible dust hopper 3. When a predetermined amount of combustible dust is stored in the combustible dust hopper 3, the damper is opened, and the combustible dust is sent to the intermediate hopper 7 through the screw conveyor 4, the water-cooled screw conveyor 5, and the sieve device 6. In the intermediate hopper 7, the upper damper 8 and the lower damper 9 are alternately opened and closed to send the combustible dust to the combustible dust blowing device 10.

  In the combustible dust blowing device 10, for example, a circle feeder 12 is provided as a distributor for blowing combustible dust into the tuyere 13 by the blower 11. The combustible dust in the combustible dust blowing device is blown from the tuyere by the blower 11 by adjusting the rotation speed of the circle feeder 12 by the motor M, adjusting the blowing amount of each tuyere.

  This embodiment is an example in which a combustible material is supplied to the combustible dust blowing device 10 and blown from the tuyere together with the combustible dust.

  The graphs shown in FIGS. 5 to 7 are obtained from data obtained by a 20 t / D test machine, FIG. 5 is a graph showing the amount of combustible dust generated when coke consumption is 30 kg / t-trash, and FIG. 5 is a graph obtained by calculating the theoretical combustion oxygen amount of the total carbon amount from the carbon amount of the generated combustible dust and the carbon amount in the coke, FIG. 7 is a calculation of the molar ratio of the oxygen amount from FIG. 5 and FIG. And graphed.

Molar ratio = (combustible dust and combustible materials other than combustible dust) Calculated from the amount of carbon, combustion oxygen amount / total oxygen amount blown from lower tuyere (air blown air and blown oxygen)
In FIG. 7, when (c) the coke ratio is 30 kg / t-dust, (a) increases the coke ratio by 10 kg / t-trash, (b) decreases the coke ratio by 10 kg / t-trash. Indicates the case.

In (a), the molar ratio of the amount of oxygen does not fall below 0.5, but the period in which the molar ratio exceeds 1.0 increases and the inflammable dust is scattered.

In (b), the molar ratio of the amount of oxygen does not exceed 1.0, but the period when the molar ratio falls below 0.5 increases, and the slag temperature decreases.

  In this way, when the coke ratio is lowered, for example, powdered carbide other than combustible dust generated from the melting furnace when the molar ratio of the oxygen amount falls below 0.5, the molar ratio is 0.5 to 1. If the blowing amount is adjusted so as to be in the range of 0.0, the coke can be greatly reduced as compared with the conventional case. This blowing may be carried out intermittently or continuously so that the molar ratio is in the range of 0.5 to 1.0.

Table 1 shows the results when carbonized wood powder is added as another combustible material.

  Three conditions were carried out for 3 days each. The amount of combustible dust generated was blown. When the coke ratio was 10 kg / t-trash and other combustibles were not blown, the molar ratio was temporarily less than 0.5, and the slag temperature was greatly reduced.

  By blowing carbonized wood powder when the oxygen molar ratio is lowered, even when the coke ratio is 10 kg / t-dust, the same as when no other combustible material is blown when the coke ratio is 30 kg / t-dust Slag temperature is maintained. In addition, when [other combustibles were not blown and the coke ratio was 10 kg / t-trash], the slag temperature was significantly lowered and slag fluidity was deteriorated.

  FIG. 3 is a schematic view showing an outline of another embodiment of the present invention, and FIG. 4 is a schematic view showing an example of blowing the tuyere.

  In the present embodiment, the combustible dust blowing device 10 is connected by the pipe 14 only to the tuyere (No. 1, 3, 5 tuyere in FIG. 4) through which the combustible dust is blown.

  Other combustible materials are blown by the combustible material blowing device 16 from the remaining tuyere (No. 2, 4, 6) other than the tuyere (No. 1, 3, 5) into which the combustible dust is blown.

It is the schematic which shows the outline of the waste melting furnace for implementing this invention. It is the schematic which shows the example of blowing of a tuyere for implementing this invention. It is the schematic which shows the outline of another Example of this invention. It is the schematic which shows the example of blowing of the tuyere of another Example of this invention. It is a graph which shows the generation amount of combustible dust at the time of 30 kg / t-dust of coke usage. It is the graph which calculated | required the theoretical combustion oxygen amount of the total carbon amount from the carbon amount of the generated combustible dust shown in FIG. 5, and the carbon amount in coke. Graph FIG. 7 is a graph obtained by calculating the molar ratio of the oxygen amount from FIGS. 5 and 6. It is the schematic which shows the outline of the conventional waste melting furnace. It is the schematic which shows the example of blowing of a conventional tuyere.

Explanation of symbols

1: waste melting furnace 2: dust remover 3: combustible dust hopper 4: screw conveyor 5: water-cooled screw conveyor 6: sieve device 7: intermediate hopper 8: upper damper 9: lower damper 10: combustible dust blowing Device 11: Blower 12: Circle feeder 13: Tuyere 14: Piping 15: Outlet 16: Other combustible material blowing device

Claims (5)

In a method in which a plurality of tuyere collects combustible dust scattered from a waste melting furnace arranged at an interval on the outer periphery of the bottom of the furnace and blows it into the waste melting furnace from the tuyere,
A method for operating a waste melting furnace, characterized by injecting combustible materials other than combustible dust together with combustible dust.   The molar ratio between the amount of oxygen blown from the lower tuyere and the amount of oxygen necessary for combustion of combustibles other than coke, combustible dust, and combustible dust is set to 0.5 to 1.0. The operation method of the waste melting furnace described.   The method for operating a waste melting furnace according to claim 1 or 2, wherein combustible dust and combustible materials other than combustible dust are blown from separate tuyere.   The blown oxygen amount of each tuyere is characterized in that the molar ratio of the amount of oxygen necessary for combustion of combustibles other than coke, combustible dust and combustible dust is 0.5 to 1.0. 3. A method for operating a waste melting furnace according to 3.   The method for operating a waste melting furnace according to any one of claims 1 to 4, wherein combustible materials other than combustible dust are intermittently blown in accordance with the amount of combustible dust generated.

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