JP2002336641A - Method for refining gas generated from waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dust-containing gas refining method by which the materials contained in the dust in the gas discharged from a gasifier or incinerator of waste and the dust discharged when acidic gas is removed can be separated and recovered effectively without arranging complicated separation steps subsequently and the recovered dust can be recycled easily as resources. SOLUTION: The gas generated by treating waste at high temperature in the waste gasifier 1 for reducing the volume of the waste is introduced into a high-temperature dust removing facility 2 to remove dust, which is then introduced into a heat exchanger 3 to recover the heat of the gas. The gas whose heat is recovered is introduced into a middle-temperature dust removing facility 4 to remove dust, which is then introduced into an acidic gas treating step to remove the acidic gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to a facility for incinerating or gasifying waste such as municipal solid waste, sewage sludge, waste plastic, biomass waste, automobile waste, waste oil, etc. to reduce the volume. The present invention relates to a method for purifying high-temperature dust-containing gas.

[0002]

[Prior Art] Urban waste, sewage sludge, waste plastic,
Waste such as biomass waste, automobile waste, waste oil, etc. is reduced in volume by incineration using an incinerator or is landfilled untreated, and useful components such as metals in the waste The amount that is recycled is very small.

A stoker furnace or a fluidized bed furnace has been used as the incinerator, but the metals discharged from the furnace are not suitable for recycling because they are oxidized.

[0004] The gas generated in the waste volume reduction processing contains dust mainly composed of oxides that are ash. In addition, it contains a substance mainly composed of heavy metals and salts thereof that are volatilized and gaseous at a high temperature immediately after gas generation, but are gradually generated as dust when cooled.

[0005] The oxides contained in the dust in the generated gas are:
Silica, alumina, magnesia, calcia, iron oxide, etc., many of which are high boiling compounds, for example, 1000
It is almost solid at ° C. In addition, these oxides account for a large part of the dust contained in the generated gas,
Depending on the processing waste, it may account for 20% to 40%, and in some cases 50% to 60%. In a gasification melting furnace, most of the high-boiling oxides are contained in and discharged from the molten slag taken out from the bottom of the furnace.

In addition, when these oxide dusts are cooled without being removed from the gas, dioxins and heavy metals are adsorbed on the surface of the oxide, and these treatments become difficult.

Further, since the gas discharged from the incinerator contains harmful components such as hydrogen chloride, for example, an alkaline agent such as slaked lime is blown into a dust collector such as a bag filter to remove hydrogen chloride in the exhaust gas. And the chlorine is reacted with an alkaline agent to collect as dust. In the dust collector, heavy metals such as zinc and lead and oxides are also collected as dust. At this time, the heavy metal dust, the oxide dust, the chlorine reacting with the alkali and the alkaline agent are mixed and collected, so even if the waste metals are collected from the dust and used effectively, they are separated. Was difficult and could not be used effectively.

Therefore, two stages of bag filters are arranged in series, and the former stage is used for collecting dust discharged from the furnace, and the latter stage is used for removing an acidic gas such as hydrogen chloride using an alkaline agent. A method of separating and recovering dust and other dust that have reacted with hydrogen chloride has also been disclosed, but even in this case, dust of oxides such as silica and alumina and dust of useful heavy metals such as zinc and lead are still present. Since they are mixed and collected, it is difficult to separate useful heavy metal dusts, and they cannot be used effectively.

Further, as a method of reducing the volume of the waste, a method of recovering metals in a reduced state together with slag from the furnace bottom by a method of gasification in a reducing atmosphere and facilitating subsequent recycling is used. It has been disclosed. For example, in the Thermoselect method disclosed in Environmental Technology, vol. 28, No. 12, p. 891 (1999), from the bottom of a gasification and melting furnace,
It has been shown that slag and reduced metal can be recovered and used. However, in the Thermoselect method, the gas generated in the gasification and melting furnace is rapidly cooled by spraying a large amount of an aqueous solution of an acid or an alkali to react the acidic component such as hydrogen chloride contained in the gas with an alkali agent. Since dust of products, dust of heavy metals, and dust of oxides such as silica and alumina are mixed and contained in water, it has been difficult to separate and collect them for effective use.

[0010]

In each of the above-mentioned waste treatment methods, any of the above-mentioned waste treatment methods comprises a reaction product of an acidic gas component and an alkaline agent discharged together with a gas from an incinerator or a gasification furnace, or an oxide such as silica or alumina. And heavy metals such as zinc and lead are mixed and discharged out of the system, so that it has been difficult to separate them and use them effectively. For this reason, they could not be used effectively and were landfilled. In order to promote the effective use of resources obtained from waste, the oxides and heavy metals, and the dust consisting of the reaction product of the acidic gas and the alkaline agent are separated and collected in the waste treatment process. It is necessary.

The present invention solves the above-mentioned problems of the prior art, and solves the problems of the substances contained in the dust in the gas discharged from the gasifier and incinerator of waste and the dust discharged in the acid gas removal treatment. It is an object of the present invention to provide a method for purifying a dust-containing gas, which can be effectively separated and recovered without providing a complicated post-separation step, and which can easily recycle dust as a resource.

[0012]

In order to achieve the above-mentioned object, the present invention according to claim 1 is a method for purifying a gas generated in a high-temperature volume reduction process of a waste, wherein the gas is subjected to high-temperature dust removal. It is characterized in that dust is removed in a process, and subsequently in a medium-temperature dust removal process at a temperature lower than the processing temperature of the high-temperature dust removal process.

According to a second aspect of the present invention, in the first aspect of the present invention, the acidic gas is removed in an acidic gas treatment step subsequent to the medium temperature dust removal step. Purification method.

According to a third aspect of the present invention, in the second aspect, the condensate is recovered in a gas-liquid separation step following the acid gas treatment step.

According to a fourth aspect of the present invention, in the second or third aspect of the invention, the acidic gas treatment step includes blowing an alkaline agent into the gas to remove a reaction product of the alkaline agent and the acidic gas component. It is characterized in that it is a process of collecting by dust removal equipment.

According to a fifth aspect of the present invention, in the second or third aspect of the invention, the acid gas treatment step comprises adsorbing or combining an acid gas component in the gas with a renewable deacidifying gas agent. And removing the deacidified gas agent containing the acid gas component, regenerating it, and separating and recovering the acid gas component.

According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the collected matter collected in the high-temperature dust removing step is returned to the waste volume reducing step. It is characterized by volume reduction processing.

According to a seventh aspect of the present invention, in purifying a gas generated in the step of reducing the volume of waste at a high temperature, an alkaline agent is blown into the gas, and the gas is removed in a high-temperature dust removing step. Dust is removed at a temperature lower than the processing temperature of the high-temperature dust removal process in the medium-temperature dust removal process, the reaction product of the alkaline agent and the acidic gas component is extracted from the collected material in the high-temperature dust removal process, and the remaining collected material is discarded It is characterized in that the material is returned to the volume reduction process of the product and the volume is reduced.

An eighth aspect of the present invention is characterized in that, in the seventh aspect of the present invention, the condensate is recovered in a gas-liquid separation step following the medium-temperature dust removal step.

According to a ninth aspect of the present invention, in the third aspect of the present invention, the condensate recovered in the gas-liquid separation step is subjected to volume reduction of waste. It is characterized by being returned to the process.

According to a tenth aspect of the present invention, in the invention according to any one of the first to ninth aspects, the collected matter collected in the intermediate temperature dust removal step is used as a raw material for refining heavy metals. I have.

According to an eleventh aspect of the present invention, in purifying a gas generated in a high-temperature volume reduction treatment step of a waste, an alkaline agent is blown into the gas, and dust is removed in a high-temperature dust removal step. The condensate is collected in the gas-liquid separation step, the reaction product of the alkali agent and the acidic gas component is extracted from the collected matter collected in the high-temperature dust removal step, and the remaining collected matter is treated as a waste volume reduction step It is characterized by being returned to

According to a twelfth aspect of the present invention, in the invention of the eleventh aspect, after removing heavy metals from the condensate recovered in the gas-liquid separation step, the remaining liquid is subjected to the volume reduction processing step. It is characterized by being returned.

According to a thirteenth aspect of the present invention, in any one of the first to twelfth aspects, the temperature in the high-temperature dust removing step is from 600 ° C. to 1400 ° C.

According to a fourteenth aspect of the present invention, in any one of the first to tenth aspects, the temperature in the intermediate-temperature dust removing step is 300 ° C. to 600 ° C.

According to a fifteenth aspect of the present invention, in any one of the first to fourteenth aspects, a heat recovery step is provided after the high-temperature dust removal step.

According to a sixteenth aspect of the present invention, in the invention according to any one of the first to fifteenth aspects, the step of reducing the volume of the waste is a step of gasifying the waste, It is characterized in that it is a step of chemical melting.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION The waste volume reduction treatment in the present invention means that waste such as municipal garbage, sewage sludge, waste plastic, biomass waste, automobile waste, waste oil, etc. is treated in a stoker furnace, a fluidized bed furnace, or the like. This refers to the process of burning and burning in an incinerator or partial combustion and gasification in a gasifier to reduce the volume.

The high-temperature dust removal step in the present invention is performed at 600
This is a step of removing dust in the gas immediately after generation at a temperature of from 1 to 1400C, preferably from 800 to 1100C. In this temperature range, the oxide of the high-boiling compound is in a solid state,
Since other heavy metals and salts thereof are in a gaseous state, dust mainly composed of a high-boiling oxide is removed. For this reason,
In the high-temperature dust removal step, high-boiling-point oxides are collected by dust removal, and heavy metals and salts are not collected, so that separation and collection can be achieved. In this step, dust mainly composed of a high-boiling point oxide collected by dust removal is returned to a waste volume reduction processing step such as an incinerator or a gasification and melting furnace.

At the same time, in the high-temperature dust removal process, unburned organic substances discharged from the waste volume reduction process such as an incinerator and a gasification and melting furnace are captured as chars and returned to the volume reduction process. . By returning these chars to the waste processing step, the amount of dust to be removed in the subsequent step can be reduced, and the char can be reused as a heat source. Particularly in a gasifier that generates combustible gas, the calorie of the gas is also increased.

Examples of the method used in the high-temperature dust removal step of the present invention include dust removal using a particle layer filter having a packed layer of carbon particles such as coke, and dust removal using a ceramic filter.

The gas from which dust mainly composed of oxides has been removed in the high-temperature dust removal step contains heavy metals such as lead and zinc and chlorides of heavy metals, in addition to trace amounts of oxides having a relatively low boiling point. , These are gas cooled to 300 ° C to 6 ° C.
When the temperature reaches about 00 ° C., dust is generated in the gas.

FIG. 6 is a graph showing the distribution of lead and zinc in the gas phase in the gas. In FIG. 6, both lead and zinc are almost completely distributed to the gas phase at a high temperature of about 800 ° C., and when the temperature reaches about 500 ° C., most of them become solid or liquid phases which are collected by dust removal equipment. It is shown.
Not only zinc and lead but also many heavy metals contained in waste show the same tendency.

The medium-temperature dust removal step in the present invention is performed by
C. to 600.degree. C., preferably 400 to 500.degree. C., in which dust in the gas is removed. In this medium temperature removal step, heavy metals such as zinc and lead are chloride, sulfide,
Collected as dust in oxide or metal form.

The dust collected in the intermediate temperature dust removal step includes:
In addition to heavy metals, sodium and potassium oxides may be slightly contained. However, as described above, in the former high-temperature dust removal step, oxides such as silica and alumina that account for most of the dust contained in the gas immediately after the generation have been removed, and also, for neutralizing the acid gas. Since no alkaline agent is injected and no reaction products between the acidic gas and the alkaline agent are contained, the dust collected in the medium-temperature dust removal process contains heavy metals at a high concentration and contains heavy metals such as lead and zinc. It is useful as a raw material for refining.

As a method used in the medium temperature dust removal step of the present invention, dust removal by a ceramic filter using a porous ceramic or the like can be mentioned.

In the acid gas treatment step of the present invention, an alkali agent such as slaked lime is blown into the gas treated by the medium temperature dust removal, and the alkali agent reacts with the acid gas in the gas. To collect. In this case, most of the oxide dust and heavy metal dust contained in the gas have been removed during high-temperature and medium-temperature dust removal, so most of the dust collected here is the reaction product of an alkali agent and an acidic gas. is there.

Dust collected by a bag filter installed in a conventional refuse treatment facility has been disposed of by landfill under special management, and the social problem of shortage of landfill sites has occurred. According to this, since the amount of dust collected by the bag filter is greatly reduced, the above problem can be solved. In addition, landfill disposal under special management,
Although it is a disposal method selected to prevent the elution of heavy metals contained in the collected dust, according to the present invention, the dust collected by the bag filter hardly contains heavy metals, Since there is no need for management, it is possible to treat the dust by a simpler method than before. It is also possible to reuse salts in dust.

As another method of the acid gas treatment step of the present invention, an acid gas component in a gas is removed by adsorbing or combining with a renewable deacidifying gas agent such as metal oxide or activated carbon. It is also possible to apply a dry acid gas treatment method comprising removing a used deacidifying gas agent containing a gas component from a process, regenerating the gas agent, and simultaneously separating and recovering the acid gas component. According to this method, the amount of dust can be reduced as compared with the above-described alkali agent blowing method.

In the present invention, when a gasification facility such as a gasification melting furnace is applied to waste volume reduction processing, the generated gas is a gas containing flammable hydrogen or carbon monoxide as a main component. When this gas is used as energy, it is necessary to remove moisture. In this case, in order to remove moisture, the gas is cooled using a gas-liquid separator to separate it into condensate and gas. This condensate may contain a small amount of tar or a small amount of mercury in addition to water. In this case, after removing mercury from the condensate by chelation or the like, the remaining tar can be used as an auxiliary fuel, and water can be reused in the gasification melting furnace as water used for operation control. In this case, thermal energy corresponding to the tar content is saved, and a volume reduction process of clean waste that does not discharge wastewater out of the system and has a small load on the environment can be realized.

In the method for treating an acidic gas according to the present invention, there is a method in which a sodium-based or calcium-based deacidifying gas agent is introduced into a gas immediately after generation in a waste volume reduction treatment step. The deacidifying gas agent that has reacted with the acid gas component is collected in the high-temperature dust removal process, the reaction product of the acid gas component and the deacidifying gas agent is removed from the collected dust, and the remaining oxides such as silica and alumina are removed. And chars are returned to the waste volume reduction process. In this case, since the acidic gas is removed at the uppermost stream of the process, there is no need to use a highly acid-resistant material for the subsequent equipment, so that there is an advantage that the total equipment cost can be reduced.

FIG. 1 shows a first example of a process for carrying out the method for purifying generated gas from waste according to the present invention. In this embodiment, municipal waste, sewage sludge,
Wastes such as waste plastics, biomass wastes, automobile wastes, waste oils, etc. are put into the gasification and melting furnace 1 and the wastes are gasified. The temperature of the free board portion of the gasification and melting furnace 1 is operated at about 1000 ° C. The gas generated by the gasification is removed in the high-temperature dust removal equipment 2, and the collected oxides and chars are returned to the gasification and melting furnace 1 through the return line 6. The chars undergo a gasification process, and the oxides are separately collected as slags. High temperature dust removal equipment 2
The method is a particle layer filter filled with coke particles,
The operating temperature is about 900 ° C.

The gas removed in the high-temperature dust removal equipment 2 is introduced into the heat exchanger 3 to recover sensible heat, and high-temperature steam is generated in the heat exchanger 3. The obtained steam may be used as a heat source for power generation, or may be used as moisture for controlling the operation of the gasification and melting furnace 1. In the heat exchanger 3, from 900 ° C. to 5
Gas sensible heat up to 00 ° C is recovered. The gas exiting the heat exchanger 3 is introduced into a medium-temperature dust removing facility 4, where dust having a low oxide content and rich in heavy metals is collected. Since this dust has a high heavy metal content, it is useful as a raw material for metal refining.

The system of the medium-temperature dust removal equipment 4 is a ceramic filter system, and the operating temperature is 450 ° C. here. An alkaline agent such as slaked lime is injected into the gas leaving the intermediate temperature dust removal equipment 4, and an acidic gas such as hydrogen chloride or hydrogen sulfide in the gas reacts with the alkaline agent to become a reaction product dust. It is collected by the bag filter 5. The collected dust has a very low content of heavy metals, is mainly composed of easy-to-treat salts, and is capable of recycling sulfur and chlorine. The operating temperature of the bag filter 5 is about 200 ° C. here. The purified gas exiting the bag filter 5 is a purified gas mainly composed of clean hydrogen and carbon monoxide having a very low concentration of oxides, heavy metals, salts and acidic gas components, and is used for gas turbine power generation and other fuels. Can be used as.

FIG. 2 shows a second example of a process for carrying out the method for purifying generated gas from waste according to the present invention. In FIG. 2, the processes from the gasification and melting furnace 1 to the bag filter 5 are the same as those in FIG. In this embodiment, the gas that has exited the bag filter 5 contains moisture, but is introduced into the gas-liquid separation facility 7 where it is cooled and the condensate generated by gas-liquid separation at room temperature is removed. The separated condensate contains water as a main component, but may also contain agglomerated tar and a small amount of mercury. In this case, mercury is removed by chelation treatment, water is returned to the gasification and melting furnace 1 via the return line 8 as water for controlling the operation of the gasification and melting furnace 1, and tar is combustible as a combustible. Is done.

FIG. 3 shows a third example of a process for carrying out the method for purifying generated gas from waste according to the present invention. In FIG. 3, the gasification and melting furnace 1 to the medium-temperature dust removal equipment 4
Since the processes up to this point are the same as those in FIG. 1, the description of the same parts as in FIG. 1 is omitted.

In this embodiment, the gas leaving the intermediate-temperature dust removing equipment 4 is introduced into a dry deoxidizing gas equipment 9 which is an acidic gas processing equipment. In the dry deoxidizing gas equipment 9, the filled metal oxide as a deoxidizing gas agent reacts with hydrogen chloride and hydrogen sulfide as acid gas components to generate metal chloride and metal sulfide. These reaction products are withdrawn to the separator 10, where the reaction products are oxidized to separate and recover chlorine and sulfur. Simultaneously, the oxidized and regenerated metal oxide is also recovered and reused again as a deoxidizing gas agent in the dry deoxidizing gas facility 9. The gas leaving the dry deacidifying gas equipment 9 is introduced into the gas-liquid separation equipment 7. The condensate generated in the gas-liquid separation equipment 7 is treated in the same manner as in FIG. 2 and is returned to the gasification and melting furnace 1.

The dry deoxidizing gas equipment 9 is filled with an oxide such as manganese, cobalt or iron as a deoxidizing gas agent, and contains a gas containing the oxide and an acidic gas component such as hydrogen chloride or hydrogen sulfide. Are contacted and reacted to generate chlorides and sulfides such as manganese, cobalt, and iron, thereby removing acidic gas components such as hydrogen chloride and hydrogen sulfide. In addition, as a method of contacting the deacidifying gas agent with the gas, a method using a fixed bed or a moving bed is employed.

The separator 10 separates the chlorine and sulfur components by subjecting the metal chloride or metal sulfide, which is the reaction product of the deacidifying gas agent and the acid gas component, to a high temperature in the air. Since it has the property of returning to the oxide of the product, it heats the reaction product and regenerates it to the original metal oxide, and the equipment separates these metal oxides from chlorine and sulfur. is there.

FIG. 4 shows a fourth example of the process for carrying out the method for purifying generated gas from waste according to the present invention. Waste such as municipal garbage, sewage sludge, waste plastic, biomass waste, automobile waste, waste oil and the like are charged into the gasification and melting furnace 1, and the waste is gasified. The temperature of the freeboard portion of the gasification and melting furnace 1 is operated at about 1000 ° C. Also, a deacidifying gas agent, which is a sodium-based alkali agent, is introduced into the free board portion. The gas generated by the gasification of the waste is removed in the high-temperature dust removal equipment 2 to collect oxides such as silica and alumina, chars, and the reaction products of the acidic gas of hydrogen chloride or hydrogen sulfide with the alkaline agent. You. The collected dust is introduced into the separator 11, and after the reaction product of the acidic gas and the alkali agent is removed, the remaining oxides and chars such as silica and alumina are removed from the gasification and melting furnace by the return line 6. Returned to 1. The chars undergo gasification again, and the oxides are separately recovered as slags.

The separator 11 is a facility for separating a reaction product of an oxide or char collected in the high-temperature dust removal facility 2 and an alkali agent such as sodium and an acid gas such as hydrogen chloride. As the separation method, for example, oxide, char,
A mixture of a reaction product of hydrogen chloride and an alkali agent is separated by a wet method, and water is added to the mixture to form a reaction product of a water-soluble acid gas and an alkali agent, and an oxide that does not dissolve in water. It is a facility that separates it into char and char.

The method of the high-temperature dust removal equipment 2 is a particle bed filter filled with coke particles, and the operating temperature is about 900 ° C. The gas removed by the high-temperature dust removal equipment 2 is supplied to the heat exchanger 3
And sensible heat is recovered. In the heat exchanger 3, high-temperature steam is generated. The obtained steam may be provided to a heat source for power generation, or may be used as moisture for controlling the operation of the gasification and melting furnace 1. In the heat exchanger 3, 900 ° C to 5
Gas sensible heat up to 00 ° C is recovered. The gas exiting the heat exchanger 3 is introduced into a medium-temperature dust removing facility 4 where dust containing a small amount of oxide and rich in heavy metals is collected. Since this dust has a high heavy metal content, it is useful as a raw material for metal refining.

The system of the medium-temperature dust removal equipment 4 is a ceramic filter system, and the operating temperature is 450 ° C. here. The gas leaving the medium-temperature dust removal equipment 4 contains moisture, but is introduced into the gas-liquid separation equipment 7 where it is cooled and the condensate generated by gas-liquid separation at room temperature is removed. The separated condensate contains water as a main component, but may also contain agglomerated tar and a small amount of mercury. In this case, mercury is removed by chelation treatment, water is returned to the gasification and melting furnace 1 via the return line 8 as water for controlling the operation of the gasification and melting furnace 1, and tar is combustible as a combustible. Is done.

FIG. 5 shows a fifth example of a process for carrying out the method for purifying generated gas from waste according to the present invention. In FIG. 5, a high-temperature dust removal facility 2
Since the processes up to and the processes of the separator 11 and the return line 6 are the same as those in FIG. 4, the description of the same parts as in FIG. 4 will be omitted.

In this embodiment, the gas removed by the high-temperature dust removal equipment 2 is guided to the gas cooling tower 13 and cooled by the circulating water. The condensate generated by this gas cooling is removed by gas-liquid separation to obtain a purified gas. On the other hand, since tars and heavy metals are mixed in the condensate side, the condensate is introduced into the heavy metal separation equipment 12 to remove heavy metals. The remaining condensate containing water as a main component and containing tar is returned to the gasification and melting furnace 1 via the return line 8, and is reused.

The heavy metal separation equipment 12 is equipment for separating heavy metals from the condensate containing heavy metals and tar collected in the gas cooling tower 13. In the heavy metal separation equipment 12, an alkali hydroxide is added to the condensed liquid to make the heavy metal dissolved in the form of a salt insoluble and precipitate, and a process of separating the precipitate of the heavy metal is performed.

[0057]

As described above, the present invention has the following advantages.

In purifying the gas generated in the waste volume reduction processing step, first, the high-temperature gas generated in the volume reduction processing step is introduced into the high-temperature dust removal step for dust removal processing. Mainly collects oxides and chars such as silica and alumina, and does not collect heavy metals such as zinc and lead. For this reason, the gas subjected to the dust removal process in the high-temperature dust removal process is further dust-treated in the medium-temperature dust removal process to separate heavy metals, or the gas subjected to the dust removal process in the high-temperature dust removal process is cooled to generate condensate, and condensate is formed. By separating the heavy metals dissolved in the wastewater, the heavy metals can be separated and collected, and the dust in the generated gas from the waste can be easily and effectively used as a resource without performing a complicated separation process. it can.

By providing the acid gas treatment step after the intermediate temperature dust removal step, it is possible to collect the reaction product of the alkali agent and the acid gas component or the reaction product of the deacidification gas agent and the acid gas component. it can. For this reason, since heavy metals can be separated and collected, dust having a high content of heavy metals can be obtained, and resources can be effectively recycled.

In addition, an alkaline agent is blown in the waste volume reduction treatment step to perform an acid gas removal treatment,
Since the reaction product of the alkali agent and the acidic gas component is collected in the high-temperature dust removal step, dust having a high content of heavy metals is obtained in the subsequent step, and the resources can be effectively recycled.

Also, by returning the dust collected in the high-temperature dust removal step to the volume reduction processing step, the amount of dust discharged outside the system is significantly reduced, and the char contained in the dust is used as fuel. Reused.

Further, the gas subjected to the dust removal treatment and the acid gas removal treatment is cooled to generate a condensate, and the condensate is returned to the waste volume reduction treatment step, thereby allowing drainage to the outside of the system. Emissions can be significantly reduced.

Further, by performing heat recovery of the gas that has been subjected to the dust removal processing in the high-temperature dust removal step, the energy of the gas generated in the waste volume reduction processing step can be used to the maximum.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first example of a process for implementing a method for purifying generated gas from waste according to the present invention.

FIG. 2 is a diagram showing a second example of a process for performing the method for purifying generated gas from waste according to the present invention.

FIG. 3 is a diagram showing a third example of a process for carrying out the method for purifying generated gas from waste according to the present invention.

FIG. 4 is a diagram showing a fourth example of a process for performing the method for purifying generated gas from waste according to the present invention.

FIG. 5 is a diagram showing a fifth example of a process for performing the method for purifying generated gas from waste according to the present invention.

FIG. 6 is a diagram showing a distribution ratio of lead and zinc in a gas phase in a gasification gas.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gasification melting furnace 2 High temperature dust removal equipment 3 Heat exchanger 4 Medium temperature dust removal equipment 5 Bag filter 6 Return line 7 Gas-liquid separation equipment 8 Return line 9 Dry deacidification gas equipment 10 Separator 11 Separator 12 Separator 13 Gas cooling tower

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C02F 11/10 C22B 19/00 4D059 F23G 5/027 Z 4K001 C10J 3/00 F27D 17/00 104G 4K056 C22B 13/00 105Z 19/00 B01D 53/34 118Z F23G 5/027 B09B 3/00 ZAB F23J 15/00 303M F27D 17/00 104 F23J 15/00 J 105 Z C22B 13/04 (72) Inventor Hiroshi Yamaguchi Marunouchi, Chiyoda-ku, Tokyo 1-2-2, Nihon Kokan Co., Ltd. (72) Inventor Kuniichi Okuyama 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. F-term (reference) 3K061 AA24 AB03 AC01 AC02 AC06 AC06 AC13 AC17 AC20 BA01 FA10 FA26 3K070 DA01 DA12 DA16 DA24 DA27 DA48 4D002 AA03 AA19 AB01 BA03 BA04 BA13 BA14 CA01 CA07 CA08 CA11 DA05 DA11 DA12 DA21 DA22 DA24 DA41 EA08 4D004 AA02 AA07 AA26 AA46 AB03 AB06 AC05 BA31 CA05 CA27 CA31 CC06 CC11 CC12 DA03 DA06 4D020 AA10 BA02 BA03 BA04 BA06 BA08 BB01 BC01 CA05 CA08 CD02 DA03 DB02 4D059 AA03 BB03 BB04 BB11 CA14 CA30 CC03 CC07 4K001 AA20 AA30 BA14 BA24 DB08 4K056 AA05 DB01 DB07 DB11 DB13

Claims (16)

[Claims] In purifying gas generated in a volume reduction process of waste at a high temperature, the gas is removed in a high-temperature dust removal process, and then a temperature lower than a processing temperature in the high-temperature dust removal process in a medium-temperature dust removal process. A gas purification method characterized by removing dust with a gas. 2. The method for purifying a gas according to claim 1, wherein the acid gas is removed in an acid gas treatment step following the medium temperature dust removal step. 3. The method for purifying gas according to claim 2, wherein the condensate is recovered in a gas-liquid separation step following the acid gas treatment step. 4. The acid gas treatment step is a step in which an alkali agent is blown into the gas and a reaction product of the alkali agent and the acid gas component is collected by a dust removing facility. Item 3. The gas purification method according to Item 3. 5. An acid gas treatment step, wherein the acid gas component in the gas is removed by adsorbing or combining with the renewable deacidifying gas agent, and the deacidifying gas agent containing the acid gas component is taken out. The method for purifying a gas according to claim 2 or 3, wherein the step is a step of regenerating and separating and recovering an acidic gas component. 6. The method according to claim 1, wherein the collected matter collected in the high-temperature dust removing step is returned to the waste volume reducing step to reduce the volume. Gas purification method. 7. In purifying a gas generated in a waste volume reduction process at a high temperature, an alkaline agent is blown into the gas, the dust is removed in a high-temperature dust removal process, and then a high-temperature dust removal is performed in a medium-temperature dust removal process. Remove dust at a temperature lower than the processing temperature of the process,
The reaction product of the alkaline agent and the acidic gas component is extracted from the collected matter collected in the high-temperature dust removal step, and the remaining collected matter is returned to the waste volume reduction processing step to reduce the volume. Gas purification method. 8. The method for purifying gas according to claim 7, wherein the condensate is recovered in a gas-liquid separation step following the medium-temperature dust removal step. 9. The method according to claim 3, wherein the condensate collected in the gas-liquid separation step is returned to a waste volume reduction processing step.
The method for purifying a gas according to any one of claims 1 to 6, and claim 8. 10. The method according to claim 1, wherein the collected matter collected in the medium-temperature dust removal step is used as a raw material for refining heavy metals.
The method for purifying a gas according to claim 9. 11. Purification of gas generated in a waste volume reduction process at a high temperature by blowing an alkaline agent into the gas, removing the dust in a high-temperature dust removal process, and subsequently condensing in a gas-liquid separation process. Collecting the liquid, extracting the reaction product of the alkali agent and the acidic gas component from the collected matter collected in the high-temperature dust removal process, and returning the remaining collected material to the waste volume reduction process Gas purification method. 12. The gas purification according to claim 11, wherein after removing heavy metals from the condensate recovered in the gas-liquid separation step, the remaining liquid is returned to the volume reduction processing step. Method. 13. The temperature in the high-temperature dust removal step is 600 ° C.
The gas purification method according to any one of claims 1 to 12, wherein the temperature is from 1 to 1400 ° C. 14. The temperature in the medium temperature dust removal step is 300 ° C.
2. The temperature is from 600 to 600 [deg.] C.
0. A method for purifying a gas according to any one of the above items. 15. The gas purification method according to claim 1, wherein a heat recovery step is provided after the high-temperature dust removal step. 16. The gas purification method according to claim 1, wherein the waste volume reduction step is a step of gasifying or gasifying and melting the waste. Method.