JPH10253040A - Melting facility of waste disposal residue - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absorb and remove efficiently a poisonous substance in an exhaust gas emitted from an oxygen burner type melting furnace for waste disposal residue which melts a refuse incinerated residue or refuse heat decompsable residue or the like and purify the exhaust gas at low cost. SOLUTION: There are provided a gas refining device 6 which refines the air into a high oxygen gas whose oxygen concentration exceeds 90%, a melting furnace 1 which melts waste disposal residue such as a refuse incinerated residue or a refuse heat decomposable residue with an oxygen burner 2 which uses the high oxygen gas as a support combustion gas, a cooling device of the exhaust gas of the melting furnace 1, a bag filter type dust collector 14 which collects molten flying ashes separated out by gas cooling, a fume cleaning device which cleans the exhaust gas after dust is collected and neutralizes the acid gas in the exhaust gas with an alkali solution and an ozone generation device 15 which generates the ozone with the high oxygen gas. The ozone generated with the ozone generation device 15 is supplied into the exhaust gas in the upstream of the fume cleaning device 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a waste incineration residue generated when incinerators incinerate waste such as municipal solid waste, sewage sludge, and industrial waste, or to reduce such waste by a pyrolysis furnace. The present invention relates to a facility for melting a waste treatment residue such as a pyrolysis residue generated when pyrolysis is performed in an oxygen atmosphere by a melting furnace.

[0002]

2. Description of the Related Art When incinerating waste such as municipal solid waste, sewage sludge, and industrial waste, the incinerated ash is discharged from the bottom of the incinerator, and the incinerated fly ash is captured by a bag filter or the like in the exhaust gas treatment system. Is done. The incineration ash and fly ash generated in this way are melted in a melting furnace such as an arc furnace or resistance furnace to reduce and stabilize the volume, and then the molten slag is dropped into a water tank and quenched. Solidified and crushed.

[0003] By the way, incinerated fly ash is produced by an oxygen burner type melting furnace using oxygen as a combustion supporting gas as disclosed in Japanese Patent Application Laid-Open No. 8-313938 filed by the present applicant. Although melting is possible by using and forming a high-temperature flame, this melting furnace has a problem that a large amount of nitrogen monoxide (NO) is generated in exhaust gas due to high temperature. That is, nitric oxide is not easily dissolved or absorbed in water or an alkaline solution, and may cause air pollution if discharged directly into the atmosphere.To reduce high-concentration nitric oxide to nitrogen gas, Since a large-sized denitration apparatus is required and a large amount of ammonia is consumed, there is a problem that equipment and running costs are extremely high.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for melting waste treatment residues capable of efficiently absorbing and removing toxic substances in exhaust gas discharged from a melting furnace for waste treatment residues and purifying the exhaust gas at low cost. It is intended to provide facilities.

[0005]

For this purpose, a waste treatment residue melting facility according to the present invention comprises a gas purifying apparatus for purifying air into high oxygen gas having an oxygen concentration of 90% or more, and a gas purifying apparatus for converting the high oxygen gas into a supporting gas. Furnace that melts waste treatment residues such as waste incineration residue or waste pyrolysis residue using an oxygen burner, a cooling device for exhaust gas of the melting furnace, and a bag filter that collects molten fly ash precipitated by exhaust gas cooling Type dust collector,
The apparatus is provided with: a smoke washer that cleans the exhaust gas after dust collection with an aqueous alkaline solution to neutralize an acid gas in the exhaust gas; and an ozone generator that generates ozone using the high oxygen gas. The ozone is supplied to exhaust gas upstream of the smoke washer. Further, the present invention is characterized in that in the waste treatment residue melting facility, an exhaust gas reheating device and a catalytic denitration device for reacting ammonia are provided downstream of the smoke washing device.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an exhaust gas treatment system diagram of the waste treatment residue melting facility. In the figure, reference numeral 1 denotes an oxygen burner type fly ash melting furnace. In the melting furnace 1, an oxygen burner 2 is provided downward on the upper wall of the furnace body, and a molten slag 3 is stored at the bottom of the furnace. The oxygen burner 2 has a fuel supply nozzle, a supporting oxygen supply nozzle, and an incineration fly ash supply nozzle provided concentrically. The incineration fly ash stored in the hopper 4 is fed from a compressor 5 with a dryer. The gas is conveyed to the oxygen burner 2 by air.

Reference numeral 6 denotes a gas purifying apparatus for purifying a high oxygen gas having an oxygen concentration of 90% or more by repeatedly compressing and expanding air using zeolite as an adsorbent (molecular sieve). Then, the high oxygen gas is supplied to the oxygen burner 2 as a supporting gas, and fuel such as kerosene is burned by the oxygen burner 2 and the high temperature (2000)
℃). The incineration fly ash is blown into the flame to melt it, and the molten slag 3 is stored in the bottom of the furnace. The slag is dropped into a water tank from a flow-out port 7 provided on one side wall to be rapidly cooled and solidified. And crushed into granules to stabilize and reduce the volume. Reference numeral 8 denotes an arc discharge heating electrode provided to maintain the fluidity of the slag at the outlet.

In the upper part of the side wall of the melting furnace 1, an exhaust gas outlet 10 connected to the duct 9 is formed. Reference numeral 11 denotes an exhaust gas cooling device. The cooling device 11 sprays cooling water from a nozzle 13 into the air (atmosphere) sent from a blower 12 in a mist state, and cools the cooling air containing a large amount of the mist-like water into a duct 9. The molten exhaust gas is rapidly cooled to a temperature lower than the heat-resistant temperature of the bag filter type dust collector 14 (for example, the exhaust gas at 1500 ° C. is cooled to 150 ° C.), whereby molten fly ash is precipitated from the exhaust gas. Then, the molten fly ash is collected by the bag filter type dust collector 14.
The rapid cooling can also prevent the regeneration of harmful substances such as dioxin.

An ozone generator 15 charges oxygen in the air by a high-pressure charging method called an ozonizer discharge to generate ozone (O ₃ ). The ozone generator 15 is purified by the gas purifier 6 in the ozone generator 15. Ozone generation efficiency and power consumption efficiency are improved by using high oxygen gas. The ozone produced in this way is used as a bag filter type dust collector 1
4 and is oxidized by its strong oxidizing power to convert most of the nitric oxide in the exhaust gas to nitrogen dioxide (NO ₂ ). NO + O ₃ → NO ₂ + O ₂

[0010] 16 the exhaust gas after the dust collection washed by dispersing the alkali aqueous solution such as N _a OH, in the exhaust gas HCl and SO
_2, in Araikemuri device to neutralize the acid gas SO _3, etc., this in Araikemuri device 16 the nitrogen dioxide is changed to sodium nitrate (N _a NO ₃₎ by the following reaction. _{2NO 2 + 2N a OH → N} a NO 3 + downstream of the exhaust gas temperature of the _{N a NO 2 + O 2 N} a NO 2 + O 3 → N a NO 3 + O 2 It should be noted that the wash smoke device 16 drops to about 80 ° C..

Reference numeral 17 denotes a steam heating type exhaust gas reheating device provided to promote the reaction downstream of the smoke washing device 16, and the exhaust gas passes through the reheating device 17 so that the exhaust gas is reduced to about 220 ° C. Reheated. Then, ammonia (NH ₃ ) is supplied into the exhaust gas, and titanium oxide,
Ammonia reacts with NO and NO ₂ in the exhaust gas to reduce it to nitrogen in a catalytic denitration device 18 using an active metal catalyst made of vanadium oxide and tungsten oxide in a honeycomb form, and the purified exhaust gas is passed through a chimney 19. Release to atmosphere. 4NO + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O 2NO ₂ + 4NH ₃ + O ₂ → 3N ₂ + 6H ₂ O

Next, data of the exhaust gas obtained by the experimental enzyme burner type melting furnace manufactured by the present inventors will be shown. That is,
Kerosene 15 to melt 50 kg / h of refuse incineration fly ash
33 m ₃ N / h with oxygen / kg / h and oxygen concentration 99.9%
And fly ash transport air of 40 m ₃ N / h. The melting furnace exhaust gas was introduced at 1500 ° C. at the furnace outlet, and water sprayed air was introduced to cool it to 200 ° C. The exhaust gas amount after cooling was 800 m ₃ / h, the NO concentration was 190 ppm,
The O ₂ concentration was 20.2% and the NO ₂ concentration was 0 ppm.
In addition, since the exhaust gas from refuse incineration facilities is generally regulated by NO _x value converted to 12% O ₂ concentration, when converted into data based on that, it becomes 2140 ppm, which is 150 ppm for general area and 60 ppm for urban area. for more than much, ozone is added to 0.32kg / h N _a OH
It was washed and absorbed with an aqueous solution to obtain 100 ppm (converted to an O ₂ concentration of 12%). Further, even in an area where regulation is severe, it can be easily dealt with by reducing NO to N ₂ using a catalytic denitration device. Note that the denitration rate of the catalytic denitration apparatus is set to about 90% under the best conditions. Therefore, at a high concentration of 2140 ppm, it drops to only about 210 ppm. The invention eliminates that need.

Further, in the present invention, a high oxygen gas is purified from air by a gas purifier using the PSA or a cryogenic separation method for separating oxygen by cooling the air to minus 160 to 170 ° C. The gas is used not only as a supporting gas for the oxygen burner but also for generating ozone in the ozone generator 16. By purifying the air by such a method, a high oxygen gas having an oxygen concentration of 90% or more and containing almost no water can be obtained. This gas is suitable for ozonation, and the ozone can be efficiently used with a small power consumption. It can be generated well. By the way, when this high enzyme gas is used, the power consumption is reduced to about one third compared with the case where ozone is generated from air.

It should be noted that the present invention is not limited to the incineration fly ash or the incineration residue of an incinerator or the like shown in this embodiment. The present invention can also be applied to a facility for melting what has been decomposed into (pyrolysis residue).

[0015]

As described above, according to the present invention, a high oxygen gas having an oxygen concentration of 90% or more used as a supporting gas in an oxygen burner type melting furnace purified by a gas purifying apparatus is used as the supporting gas. In addition to using it, ozone is generated through an ozone generator, nitric oxide in the exhaust gas of the melting furnace is oxidized by the ozone, and the exhaust gas is washed with an alkaline aqueous solution. There is a beneficial effect that the emission of nitric oxide can be suppressed at low cost without the need for ammonia or a large-sized denitration device.

[Brief description of the drawings]

FIG. 1 is an exhaust gas treatment system diagram showing an embodiment of a waste treatment residue melting facility according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Melting furnace 2 Oxygen burner 3 Molten slag 6 Gas purification device 11 Cooling device 14 Bag filter type dust collector 15 Ozone generator 16 Smoke washing device 17 Exhaust gas reheating device 18 Catalyst denitration device

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F23J 15/06 F23J 15/00 E 15/08 K F23L 7/00 HLZ

Claims (2)

[Claims] 1. A gas purifying apparatus for purifying air into a high oxygen gas having an oxygen concentration of 90% or more, and a waste treatment such as a refuse incineration residue or a refuse pyrolysis residue using an oxygen burner using the high oxygen gas as a supporting gas. A melting furnace for melting the residue, a cooling device for the exhaust gas of the melting furnace, a bag filter type dust collector for collecting molten fly ash precipitated by cooling the exhaust gas, and washing the exhaust gas after dust collection with an alkaline aqueous solution to remove the exhaust gas from the exhaust gas A smoke washer that neutralizes acidic gas, and an ozone generator that generates ozone using the high oxygen gas, wherein the ozone generated by the ozone generator is included in exhaust gas upstream of the smoke washer. Melting facility for waste treatment residues characterized by supplying. 2. The waste treatment residue melting facility according to claim 1, further comprising a flue gas reheating device and a catalytic denitration device for reacting ammonia downstream of the smoke washing device.