JP2001041435A - Ash melting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ash melting device in which dioxin in ashes can be removed with low energy consumption. SOLUTION: An ash melting device comprises an ash melting furnace 11 having an ignition burner 13 provided on a furnace top part or a furnace bottom part, a group of vapor jet nozzles 26 for jetting vapor including fuel to a furnace, an ash supply port 30 provided on a furnace wall and a melted ash take- out port 34 provided on the furnace bottom part 32, and a vapor generator 40 for supplying vapor including combustible components to the group of vapor jet nozzles 26. Thus, ashes including dioxin can be supplied to the ash melting furnace 11 so as to mix the vapor including the combustible components with air, burn the mixture at high temperature not lower than ash melting temperature and decompose the dioxin in the ashes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ash melting apparatus for melting residue ash and fly ash discharged from a solid incinerator to remove dioxin contained in the ash.

[0002]

2. Description of the Related Art Exhaust gas discharged from incinerators for municipal solid waste and industrial waste is subjected to dioxin emission control measures. Dioxin contained in fly ash and incineration residue ash generated in the combustion process and dust collection process must be melted at a high temperature and decomposed. Fly ash and incineration residue ash discharged from a stalker type or fluidized bed type incinerator are collected in a dust collector or a residue receptacle and are melted. In order to melt the combustion ash, a high temperature of about 1200 ° C. or more is required, and therefore various melting furnaces have been developed. For example, there are an electric arc type, an electric resistance type, a gasification melting furnace, a burner combustion type, etc., all of which consume a large amount of energy.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ash melting apparatus capable of removing dioxin in ash and having low energy consumption.

[0004]

An ash melting apparatus according to the present invention comprises: an ignition burner provided at a furnace top or a furnace bottom;
An ash melting furnace having a steam injection nozzle group provided on the furnace top and injecting steam containing fuel into the furnace, an ash inlet provided on the furnace wall, and a molten ash outlet provided on the furnace bottom, and A steam generator is provided for supplying steam containing a combustible component to the steam injection nozzle group.

In the above ash melting apparatus, fly ash and incineration residues containing dioxin discharged from a waste incinerator or the like are supplied into the ash melting furnace. The combustible component in the vapor is burned at a high temperature by mixing the vapor containing the combustible component with the combustion gas, and the inside of the furnace is maintained at the ash melting temperature or higher. Since the ash melting temperature is higher than the dioxin decomposition temperature, dioxin in the ash is decomposed. Combustion waste heat from ash melting furnaces and waste incinerators can be recovered by heating and generating steam from feedwater containing combustible components, and the steam is reused as auxiliary combustion steam.
It is possible to improve combustion efficiency and reduce energy consumption.

The steam generator is connected to the ash melting furnace through a combustion gas passage, and heat exchanger for heating water containing a combustible component; and a steam injection nozzle formed on an upper portion of the heat exchanger. It is good also as composition which has a steam part which leads to a group. In this configuration, high-temperature combustion waste heat from the ash melting furnace can be effectively used.

[0007] In a facility in which an ash melting device is provided in a waste incinerator, the steam generator heats water containing a combustible component using exhaust gas from the waste incinerator as a heat source and communicates with the steam injection nozzle group. It is good also as composition provided with a heat exchanger.
With this configuration, the combustion waste heat of the waste incinerator can be effectively used.

[0008]

FIG. 1 shows an embodiment of the present invention and is a configuration diagram of an ash melting device. The ash melting device 10 of the present invention mainly includes an ash melting furnace 11 and a steam generator 40.

The ash melting furnace 11 is a completely sealed vertical cylindrical furnace. An ignition burner 13 is provided at the center of the furnace top, and the ignition burner 13 is an air spray oil burner and has a double structure. That is, the central fuel injection nozzle 1
An annular combustion air injection nozzle 15 is formed at the tip of the nozzle 4. The fuel injection nozzle 14 has a fuel oil tank 16
Are connected via a fuel supply pipe 17. Fuel oil is
The fuel is supplied to the fuel injection nozzle 14 by the fuel pump 18. Fuel oil used is heavy oil, light oil, waste oil, or the like. A combustion air blower 20 is connected to the combustion air injection nozzle 15 via an air supply pipe 21. After ignition,
When the furnace temperature rises to a temperature at which the steam containing the combustible component can burn on its own, the fuel oil is stopped, and the furnace temperature naturally rises to the ash melting temperature.

A steam injection nozzle box 2 is provided at the center of the top of the furnace.
5 are provided. The vapor injection nozzle box 25 is connected to an evaporator 50 of a vapor generator 40 described below via a vapor pipe 57. A plurality of steam injection nozzle groups 26
It is provided on the peripheral wall and bottom of the steam injection nozzle box 25. The steam injection nozzle group 26 opens diagonally downward and in a direction along the furnace inner wall. Therefore, the steam injected from the steam injection nozzle group 26 spirals downward in the furnace. In order to sufficiently decompose the dioxin in the ash, it is desirable that the combustion gas be retained in the furnace for 2 seconds or more. For this reason, the internal volume of the ash melting furnace 11, the air volume of the combustion air blower 20, and the like are designed so that a combustion gas residence time of 2 seconds or more can be obtained.

An incineration ash inlet 30 is provided at the center of the furnace side wall of the furnace body 12 on the side of the combustion gas outlet 28. The furnace bottom 32 is inclined toward the outlet 34, and the molten slag flows through the furnace bottom 32 and is discharged from the outlet 34.

The steam generator 40 comprises a heat exchanger 41 and an evaporator 50. The combustion gas outlet 28 provided near the furnace bottom is connected to the heat exchanger 4 via a combustion gas passage 36.
1 header 42. A large number of smoke tubes 44 are attached to the tube sheet 43. The combustion gas is discharged from the chimney 55 through the smoke pipe 44 to the atmosphere. A water supply tank 46 is connected to the heat exchanger 41 via a water supply pipe 47, and water containing oil is supplied by a water supply pump 48. The upper part of the heat exchanger 41 is an evaporator 50.
An oil drain port 51 is provided on a side wall of the evaporating section 50, and the concentrated oil floating on the liquid surface is discharged to the fuel tank 16 through an oil drain pipe 52 together with water. Heavy oil, light oil, waste oil and the like are used as the oil component.

The operation of the ash melting apparatus 10 configured as described above will be described. A water supply containing a small amount of oil (for example, 10 to 20% by weight) previously stored in the water supply tank 46 is supplied to the set water level of the evaporator 50. Next, after starting the combustion air blower 20, the fuel supply pump 18 is started, and the ignition burner 13 is ignited. The optimum combustion state is maintained while detecting the furnace temperature with a thermocouple (not shown). The temperature inside the furnace rises, and the feedwater containing oil is heated by the heat exchanger 41 to reach the evaporation temperature, and the feedwater starts to evaporate in the evaporator 50. The steam passes through the oil film layer on the water surface to become steam containing oil (partially in fine particles), and enters the steam injection nozzle box 25 via the steam pipe 57. The steam is heated by the combustion gas in the furnace in the steam injection nozzle box 25, becomes dry steam, and is injected into the furnace from the steam injection nozzle group 26. The vapor pressure is, for example, 1-2 kg / cm ² ab. The injected steam mixes with the combustion gas from the ignition burner 13 while descending spirally along the furnace wall.
By mixing with the combustion gas, the oil in the steam is completely burned. The combustion temperature of the fuel oil and the oil component in the steam is equal to or higher than the dioxin decomposition temperature (850 ° C.). The combustion gas from the ash melting furnace 11 is discharged from the chimney 55 into the atmosphere via the combustion gas path 36 and the smoke tube 44 of the heat exchanger 41.

The combustion temperature of the ash melting furnace 11 is gradually raised to about 1200 ° C. while adjusting the flow rate of the feed water containing the fuel oil and the oil component. When the combustion temperature is stabilized, the supply of the fuel oil to the ignition burner 13 is stopped. Burn only the oil in the water supply. As described above, a high-temperature reducing gas is generated by mixing the oil component with the steam and spray-combustion, thereby suppressing high-temperature corrosion of the heat exchanger 41 and preventing dust from sticking in the smoke tube 44.

The incineration ash discharged from a waste incinerator or the like is collected in an incineration ash reservoir. The collected incinerated ash is intermittently charged and melted from the incinerated ash input port 30 of the ash melting furnace 11 in a batch system. The inside of the furnace is maintained at a high temperature of about 1200 ° C. which is a dioxin decomposition temperature of 850 ° C. or more. Since the incinerated ash is melted and the dioxin in the ash is decomposed, clean exhaust gas is released from the chimney 55 into the atmosphere.

The ignition burner is not limited to the air spray oil burner, but may be a hydraulic spray oil burner, a mixed gas burner or other burners. Fuel is heavy oil,
In addition to liquid fuel such as light oil, gaseous fuel such as LPG and city gas may be used. For gaseous fuel, fuel tank 1
Instead of the fuel pump 6 and the fuel pump 18, gas fuel is supplied to the gas burner from a city gas supply line or a gas fuel filling cylinder. If it is difficult to burn the oil contained in the feedwater, a heater may be provided in the feedwater tank 46.

FIG. 2 shows another embodiment of the present invention. Components similar to those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. As shown in the drawing, the burner 13 for ignition is provided at the furnace top in the ash melting apparatus 10 described above, but the difference is that the burner 62 for ignition is provided at the furnace bottom in the ash melting apparatus 60. . The operation of the ash melting device 60 is substantially the same as that of the ash melting device 10 described above.

FIG. 3 shows an example in which the ash melting apparatus of the present invention is installed in an incineration boiler power plant. The exhaust gas from the waste incinerator 65 is sucked by the exhaust blower 72,
The gas is discharged from the chimney 73 through the steam generator 67 and the dust collector 70. When the exhaust gas passes through the steam generator 67, it heats the feedwater containing oil from the feedwater tank 68. The steam generator 67 is provided with the steam injection nozzle group 2 of the ash melting device 10.
6 is supplied with steam. Steam from an incinerator boiler 75 installed in the waste incinerator 65 is supplied to a steam turbine 76, drives a generator 77, and is further supplied to a steam use facility 78 such as a product drying device. Drain from the steam-using equipment 78 is supplied to a drain tank 80 by a drain transfer pump 79, and is supplied to an incineration boiler 75 by a water supply pump 81.

[0019]

The ash melting apparatus of the present invention includes a gasification melting furnace for burning combustible components in low-pressure steam. Combustion waste heat from ash melting furnaces and waste incinerators can be recovered by heating and generating steam from feedwater containing combustible components, and the steam is reused as auxiliary combustion steam, improving combustion efficiency. Energy consumption can be reduced. The generation of NOx is also suppressed by the reducing gas using steam. The ash melting furnace can be used even for crude oil such as waste oil, and is suitable for small-scale equipment because of its simple structure and operation. Since the vapor pressure may be low, the surface temperature of the heat exchanger tubes of the heat exchanger does not rise, and high-temperature corrosion hardly occurs.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention and is a configuration diagram of an ash melting device.

FIG. 2, showing another embodiment of the present invention, is a configuration diagram of an ash melting device.

FIG. 3 is a plant system diagram showing an example in which the ash melting device of the present invention is installed in an incineration boiler power plant.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Ash melting device 50 Evaporating part 11 Ash melting furnace 55 Chimney 13 Ignition burner 57 Steam pipe 16 Fuel tank 60 Ash melting device 18 Fuel pump 62 Ignition burner 20 Combustion air blower 65 Waste incinerator 25 Steam injection nozzle box 67 Steam generator 26 Steam injection nozzle group 70 Dust collector 30 Incineration ash inlet 72 Exhaust blower 36 Combustion gas path 75 Incinerator boiler 40 Steam generator 76 Steam turbine 41 Heat exchanger 77 Generator 44 Smoke tube 78 Steam utilization facility 46 Water supply tank 81 Water supply pump 48 Water supply pump

Claims (3)

[Claims] 1. An ignition burner provided at a furnace top or a furnace bottom, a steam injection nozzle group provided at a furnace top and injecting steam containing a combustible component into a furnace, an ash inlet provided at a furnace wall And an ash melting furnace having a molten ash outlet provided at the furnace bottom, and a ash melting device comprising: a steam generator for supplying steam containing a combustible component to the steam injection nozzle group. . 2. A heat exchanger connected to the ash melting furnace through a combustion gas passage and heating water containing a combustible component, the steam generator being formed on an upper portion of the heat exchanger, The ash melting device according to claim 1, further comprising a steam portion communicating with the injection nozzle group. 3. The steam generator includes a heat exchanger that heats water containing a combustible component using exhaust gas from a waste incinerator as a heat source and communicates with the steam injection nozzle group.
The ash melting device as described.