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WO2024048386A1 - Method for treating high-temperature gas - Google Patents

Method for treating high-temperature gas Download PDF

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Publication number
WO2024048386A1
WO2024048386A1 PCT/JP2023/030280 JP2023030280W WO2024048386A1 WO 2024048386 A1 WO2024048386 A1 WO 2024048386A1 JP 2023030280 W JP2023030280 W JP 2023030280W WO 2024048386 A1 WO2024048386 A1 WO 2024048386A1
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WIPO (PCT)
Prior art keywords
temperature gas
cement
gas
carbon dioxide
nitrous oxide
Prior art date
Application number
PCT/JP2023/030280
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French (fr)
Japanese (ja)
Inventor
弘輔 佐藤
芙子 小野
博幸 早野
敏嗣 田中
拓望 田口
あかね 武藤
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日本ヒューム株式会社
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Priority claimed from JP2023124315A external-priority patent/JP2024032662A/en
Application filed by 日本ヒューム株式会社 filed Critical 日本ヒューム株式会社
Publication of WO2024048386A1 publication Critical patent/WO2024048386A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/54—Nitrogen compounds
    • B01D53/56—Nitrogen oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/62—Carbon oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/81—Solid phase processes
    • B01D53/82—Solid phase processes with stationary reactants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes

Definitions

  • the present invention relates to a high-temperature gas processing method for suitably reducing greenhouse gases nitrous oxide and carbon dioxide in the same process.
  • nitrous oxide has about 300 times the greenhouse effect of carbon dioxide, and also decomposes in the stratosphere to produce nitric oxide, which affects the depletion of the ozone layer. Reduction of both levels of nitrous oxide is required from the perspective of global environmental conservation.
  • the coefficient for carbon dioxide is set to 1
  • the coefficient for nitrous oxide is set to 300, and each amount contained in the gas is multiplied by the coefficient, so that the total becomes smaller. Reducing emissions is an effective way to combat global warming.
  • a known method for treating nitrous oxide is to bring a catalyst such as limestone or slaked lime powder into contact with nitrous oxide and decompose the nitrous oxide into nitrogen, thereby removing it (for example, (See Patent Document 1).
  • the amount of concrete waste generated from demolition of buildings, etc. is approximately 35 million tons per year, and the amount of concrete that is returned to factories without being used at construction sites is approximately 1.6 million m 3 per year, i.e. the volume of ready-mixed concrete shipped.
  • Approximately 2% of approximately 80 million cubic meters of cement is generated, and these are treated as industrial waste, and the reuse of hardened cement, including such concrete waste, has become a social issue.
  • the present invention uses hardened cement to efficiently reduce nitrous oxide and carbon dioxide contained in high-temperature gas in the same process without using natural resources. This was developed for the purpose of providing a method for processing high-temperature gas.
  • the feature of the invention according to claim 1 for solving the above-mentioned conventional problems is that, in a method for treating high-temperature gas containing nitrous oxide and carbon dioxide, the high-temperature gas of 50 to 900 °C and cement to decompose the cement hydrate contained in the hardened cement body to produce calcium oxide, and also bring the calcium oxide into contact with the gas, and use the calcium oxide as a catalyst to generate calcium oxide.
  • the purpose is to decompose nitrogen oxide into nitrogen and oxygen, and to fix the carbon dioxide in the hardened cement body in the same process.
  • the high temperature gas contains 50 ppm or more of nitrous oxide, 5% or more of carbon dioxide, and 10% or more of water content per reference volume. There is a particular thing.
  • a feature of the invention according to claim 3, in addition to the configuration of claim 1 or 2, is that the high temperature gas is adjusted to 450°C to 700°C.
  • a feature of the invention as set forth in claim 4 is that, in addition to the structure of claim 1 or 2, the cement hardened body is made of waste cement material.
  • a feature of the invention set forth in claim 5 is that, in addition to the structure of claim 1 or 2, the cement hardened body is composed of a residue obtained by separating and removing aggregate from concrete material before solidification. be.
  • the invention according to claim 6 is characterized in that the hardened cement body in which the carbon dioxide is fixed is recovered and reused as a cement material.
  • a seventh aspect of the invention is characterized in that, in addition to the first or second aspect, the high-temperature gas is exhaust gas generated from a sewage sludge incinerator.
  • the method for treating high-temperature gas according to the present invention includes the configuration set forth in claim 1, thereby eliminating nitrous oxide and slaked lime from exhaust gas in the same process without using limestone or slaked lime powder, which are natural resources.
  • Nitrous oxide and carbon dioxide which are greenhouse gases in high-temperature gases containing carbon, can be decomposed and fixed.
  • concrete waste material whose annual amount is about 35 million tons or more, can be suitably reused.
  • the amount of nitrous oxide and carbon dioxide is increased, so greenhouse gases can be efficiently reduced, and waste can be reduced. It is possible to use more of a certain hardened cement. Further, it is possible to increase the amount of carbon dioxide fixed by the hardened cement body.
  • the hardened cement body can be reused as a cement-based material and can be effectively utilized as a measure against global warming.
  • nitrous oxide and carbon dioxide contained in exhaust gas generated from a sewage sludge incinerator can be decomposed and fixed.
  • 1 is a schematic cross-sectional view showing an example of a processing apparatus used in the high-temperature gas processing method according to the present invention.
  • 1 is a vertical cross-sectional view schematically showing an apparatus used in an effect confirmation test of a high-temperature gas processing method according to the present invention. It is a graph showing the relationship between the reduction rate of nitrous oxide and temperature in the same effect confirmation test as above. It is a graph which shows the relationship between the reduction rate of carbon dioxide and temperature same as the above. It is a graph showing the relationship between the overall reduction rate of greenhouse gases same as above and temperature. It is a graph which shows the relationship between the reduction rate of nitrous oxide and time at each temperature same as the above.
  • sewage sludge, etc. is incinerated in an incinerator 4 at a sewage sludge incinerator, etc., and high-temperature gas (high-temperature exhaust gas) discharged from the incinerator 4 is installed downstream of the incinerator 4.
  • high-temperature gas high-temperature exhaust gas
  • the processing apparatus 1 includes, for example, an inclined tubular processing furnace body 3 and a gas supplying gas (high-temperature exhaust gas) 5 discharged from an incinerator 4 into the processing furnace body 3. and a cement hardening body supply means 6 for supplying the cement hardening body 2 into the processing furnace body 3, and cement hardening with the high temperature gas 5 containing nitrous oxide and carbon dioxide in the treatment furnace body 3.
  • the treated gas is brought into contact with the body 2 and the treated gas is discharged from the exhaust pipe 7.
  • the treated gas discharged from the processing device 1 is discharged into the atmosphere from a chimney through a cooling tower, a dust collector, a flue gas treatment tower, etc. (not shown in the figure). It looks like this.
  • the processing furnace body 3 is formed in a closed cylindrical shape with a certain length, and the internal atmosphere can be adjusted to a predetermined temperature by a temperature control means 8 consisting of a heater etc. arranged on the outer periphery.
  • the high-temperature gas 5 may be used as it is, or may be controlled to a temperature that allows greenhouse gases to be more efficiently reduced depending on the situation.
  • the processing furnace body 3 may be configured to be rotatable in the circumferential direction around the tube axis by a rotating means.
  • the gas supply means includes a gas supply pipe 9 connected to the incinerator 4, and is configured to supply high-temperature gas 5 exhausted from the incinerator 4 into the processing furnace body 3 through this gas supply pipe 9. .
  • the treated gas discharged from the exhaust pipe 7 may be recovered and reheated by the reheating means 10, and then sent to the gas supply pipe 9 and supplied into the processing furnace body 3 again. .
  • the hardened cement supply means 6 includes a supply belt conveyor 11 that communicates with the inside of the processing furnace 3 on the upstream side, and a hopper or the like into which the hardened cement 2 prepared in a separate plant is fed onto the supply belt conveyor 11.
  • the hardened cement body 2 is fed into the processing furnace body 3 from the upstream side by the supply side belt conveyor 11, and passes through the treatment furnace body 3 along the slope at a predetermined speed. After that, it is discharged by a discharge side belt conveyor 13 that communicates with the inside of the processing furnace body 3 on the downstream side.
  • the hardened cement body 2 may be supplied either batchwise or continuously.
  • cement hardened body 2 discharged from the processing furnace body 3 may be recovered and put into the processing furnace body 3 again.
  • Cement, returned mortar, and returned concrete (hereinafter collectively referred to as hardened cement 2) are prepared in a separate plant, and the hardened cement supply means 6 starts supplying them into the processing furnace 3.
  • these hardened cement bodies 2 may be those mixed with cement, and the larger the amount of cement mixed in, the more preferable.
  • waste concrete material is crushed and aggregate is removed, and returned concrete material is composed of the residue after separating and removing aggregate before solidification, which reduces nitrous oxide and carbon dioxide. preferred.
  • exhaust gas generated at the sewage sludge incinerator that is, high-temperature gas containing nitrous oxide and carbon dioxide generated when sewage sludge and the like are incinerated in the incinerator 4 is transferred to the processing device 1 (processing furnace body 3).
  • Nitrous oxide and carbon dioxide in the high-temperature gas and the cement hardening body 2 are fed through the supply pipe 9 into the processing furnace body 3 adjusted to a predetermined temperature of 50° C. to 900° C., preferably 450° C. to 700° C. bring into contact.
  • the high temperature gas 5 contains 50 ppm or more of nitrous oxide, 5% or more of carbon dioxide, and 10% or more of moisture per standard volume, and is adjusted by adding moisture as necessary.
  • calcium hydroxide in the hardened cement body 2 is decomposed into calcium oxide and water at 450 to 600°C (Ca(OH) 2 ⁇ CaO+H 2 O). , new calcium oxide is produced. This generated calcium oxide comes into contact with nitrous oxide in the gas, thereby promoting the decomposition of nitrous oxide. Further, carbon dioxide also reacts with newly generated calcium oxide and is fixed to the hardened cement body 2.
  • Nitrous oxide in the gas is decomposed into oxygen and nitrogen when it comes into contact with calcium oxide at a temperature of 200°C or higher, further decomposed at 350°C or higher, and the decomposition is accelerated as the temperature increases.
  • the amount of substances produced by chemical reactions at each of these temperatures varies depending on the chemical composition of the hardened cement body 2.
  • the high-temperature gas comes into contact with the hardened cement body 2, it is also possible to recover it and return it to the processing device 1 again. Similarly, after contacting the cement hardened body 2 with the gas, it can be returned to the treatment device 1 again and the same treatment can be repeated multiple times.
  • the hardened cement body 2 in which carbon dioxide is fixed by contact with the gas can be reused as a new cement material such as a cement raw material or a concrete material.
  • the hardened cement body 2 is produced not only when the hardened cement body 2 is crushed and aggregate is removed at the stage before the main treatment (before fixation of carbon dioxide), but also when carbon dioxide is fixed in the hardened cement body 2. After that, it is pulverized and the aggregate is removed. In either case, it can be reused as a new cement raw material or cement material such as concrete material, and by fixing carbon dioxide, carbon dioxide emissions are reduced. can be effectively used as a countermeasure against global warming.
  • the cement paste attached to its surroundings fixes carbon dioxide, so by reusing it as recycled aggregate in concrete materials (cement-based materials), it can be used effectively to counter global warming. can do.
  • the waste heat of the treated exhaust gas, in which nitrous oxide has been decomposed into nitrogen and oxygen, is recovered by a heat exchanger and released into the atmosphere from a chimney or the like through a pipe.
  • nitrous oxide is decomposed into nitrogen and oxygen by contacting with the hardened cement 2, without using limestone or slaked lime powder, which are natural resources.
  • nitrous oxide is decomposed into nitrogen and oxygen.
  • Carbon can be fixed in the hardened cement body 2, and emissions of nitrous oxide and carbon dioxide can be totally suppressed as greenhouse gases.
  • the discarded cement hardened body 2 can be suitably reused.
  • nitrous oxide is appropriately expressed as N 2 O
  • carbon dioxide is expressed as CO 2 using chemical formulas.
  • Example 2 Using ordinary cement, mix cement paste with a W/C of 0.6 in a Hobart mixer to make a total of 30L of cement paste, put it into multiple polyethylene bags (diameter 50mm, length 500mm), and mix the cement paste with a W/C of 0.6 using a Hobart mixer. After 3 weeks of age, sealed curing was performed in air at 20°C to prepare a hardened cement body 2. After that, the polyethylene bag was removed and the hardened cement body 2 was crushed to a particle size of 5 mm or less with a jaw crusher to obtain a hardened cement body. Take the sample No. 2 and put it in a polyethylene bag and seal it.
  • a mixed gas containing 10% CO 2 , 1000 ppm N 2 O, and the rest atmospheric gas flows into the kiln at 1 L/min for 30 minutes. 4.
  • the CO 2 concentration is monitored, and 18 L of gas is collected using a sampling bag (the remaining 12 L is branched for monitoring), and the gas concentrations of N 2 O and CO 2 are analyzed using a gas chromatograph.
  • the total greenhouse gas concentration was calculated by multiplying the N 2 O concentration by 300 times and the CO 2 concentration by 1 time.
  • the greenhouse gas reduction rate is calculated using the following formula for the inflow greenhouse gas concentration of 0.4 (N 2 O: 1000 ppm x 300, CO 2 : 10% x 1). We calculated the rate at which we were able to reduce this. (1-Greenhouse gas concentration/0.4) x 100 (%)
  • Example 1 The above steps 1 to 4 were carried out at different temperatures from 50° C. to 850° C., and the gas concentrations of N 2 O and CO 2 at each temperature were analyzed. The results are shown in Table 1 and Figures 3 to 5.
  • nitrous oxide and carbon dioxide are suitably removed in the temperature range of 450°C to 700°C, and that the greenhouse gases nitrous oxide and carbon dioxide can be efficiently reduced in total in the same process. Ta.
  • Example 2 In this example, 20% of the sample was atomized with water in advance to make it hydrated, and the above steps 1 to 4 were carried out at a temperature of 600°C to remove N 2 O and CO 2 . The gas concentration was analyzed. The results are shown in Table 2.
  • Example 3 In this example, the inflow gas (inflow rate 2 L/min) was adjusted by adding 10% CO 2 , 500 ppm N 2 O, and 40 vol% steam, and the above steps 1 to 4 were performed in a kiln. The analysis was carried out at different internal temperatures of 400° C. to 850° C., and the temperature at which the gas concentration of both N 2 O and CO 2 at each temperature had the highest reduction rate was analyzed.
  • hardened cement 2 In addition to hardened cement 2, two types of hardened cement 2' were used as samples, which were carbonated in a tank at room temperature for 4 days to simulate fine cement powder from waste concrete.
  • the hardened cement body 2 is assumed to be sludge such as returned concrete, and the hardened cement body 2' is assumed to be fine powder of waste concrete obtained by crushing concrete that has been used for many years and has become carbonated (hereinafter referred to as The hardened cement body 2 is referred to as an uncarbonated product, and the carbonated hardened cement body 2' is referred to as a carbonated product).
  • Example 4 a dehydrated sludge product (hereinafter referred to as sludge), which is an actual waste concrete material, was used as a sample, and as in Example 3, CO 2 was added to the inflow gas (inflow rate 2 L/min). After adjusting by adding 10% of N 2 O, 500 ppm of N 2 O, and 40 vol% of water vapor, the above steps 1 to 4 were carried out at a kiln internal temperature of 600° C. in the same manner as in Example 3, and N 2 O and CO The reduction rate of gas concentration in both cases was verified.
  • This sample was made by solidifying the sludge generated during the manufacture of ready-made piles outdoors and crushing it into particles with a particle size of 5 mm or less using a jaw crusher. The experiment was conducted by placing 100 g of each sample on four stainless steel buds, and placing a total of 400 g into the kiln.

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  • Chemical & Material Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
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Abstract

[Problem] To provide a method for treating a high-temperature gas, whereby nitrous oxide and carbon dioxide contained in the high-temperature gas can be efficiently reduced in the same step using a cured cement object without using natural resources. [Solution] This method for treating a high-temperature gas comprises: bringing a high-temperature gas 5 having a temperature of 50-900°C into contact with a cured cement object 2 to decompose a cement hydrate contained in the cured cement object 2 to yield calcium oxide; bringing the calcium oxide into contact with the gas to decompose the nitrous oxide into nitrogen and oxygen with the calcium oxide as a catalyst; and fixing the carbon dioxide to the cured cement object 2 in the same step.

Description

高温ガスの処理方法How to treat high temperature gas
本発明は、温室効果ガスである亜酸化窒素と二酸化炭素とを同じ工程で好適に削減するための高温ガスの処理方法に関する。 The present invention relates to a high-temperature gas processing method for suitably reducing greenhouse gases nitrous oxide and carbon dioxide in the same process.
ボイラーや各種プラントの炉から排出される排ガスには、化学的に安定した亜酸化窒素（Ｎ２Ｏ）や二酸化炭素（ＣＯ２）が含有されていることが知られている。　 It is known that exhaust gas discharged from boilers and furnaces of various plants contains chemically stable nitrous oxide (N 2 O) and carbon dioxide (CO 2 ).
特に亜酸化窒素は、二酸化炭素の約３００倍の温室効果があり、また、成層圏で分解して一酸化窒素を生成しオゾン層の破壊に影響を与えることから、二酸化炭素だけでなく二酸化炭素と亜酸化窒素の両方の削減が地球環境保全の観点から求められている。　 In particular, nitrous oxide has about 300 times the greenhouse effect of carbon dioxide, and also decomposes in the stratosphere to produce nitric oxide, which affects the depletion of the ozone layer. Reduction of both levels of nitrous oxide is required from the perspective of global environmental conservation.　
２種類の温室効果については、二酸化炭素の係数を１、亜酸化窒素の係数を３００とし、ガス中に含まれるそれぞれの量に対してそれぞれ係数を乗じて、その合計が小さくなるよう効率的に削減することが地球温暖化対策において有効である。　 Regarding the two types of greenhouse effects, the coefficient for carbon dioxide is set to 1, and the coefficient for nitrous oxide is set to 300, and each amount contained in the gas is multiplied by the coefficient, so that the total becomes smaller. Reducing emissions is an effective way to combat global warming.　
従来、亜酸化窒素を処理する方法としては、石灰石や消石灰粉粒体等の触媒を亜酸化窒素と接触させ、亜酸化窒素を窒素に分解することによって除去する方法が知られている（例えば、特許文献１を参照）。 Conventionally, a known method for treating nitrous oxide is to bring a catalyst such as limestone or slaked lime powder into contact with nitrous oxide and decompose the nitrous oxide into nitrogen, thereby removing it (for example, (See Patent Document 1).
特開平７－１７１３４６号公報Japanese Patent Application Publication No. 7-171346
しかしながら、上述の如き従来の技術では、石灰石や消石灰粉粒体が有限な天然資源であることから、亜酸化窒素の処理に潤沢に使用すると資源枯渇につながるおそれがあった。　 However, in the conventional techniques as described above, since limestone and slaked lime powder are finite natural resources, there is a risk that if they are used in abundance for the treatment of nitrous oxide, it will lead to resource depletion.　
一方、現在では、建造物の解体等によって生じたコンクリート廃材は年間約３５００万ｔ、工事現場で使われずに工場に戻されたりしたコンクリートは年間で約１６０万ｍ３、即ち、生コンクリート出荷量約８０００万ｍ３の２％程度発生し、これらが産業廃棄物として処理されており、このようなコンクリート廃材等を含むセメント硬化体の再利用が社会的課題となっている。　 On the other hand, currently, the amount of concrete waste generated from demolition of buildings, etc. is approximately 35 million tons per year, and the amount of concrete that is returned to factories without being used at construction sites is approximately 1.6 million m 3 per year, i.e. the volume of ready-mixed concrete shipped. Approximately 2% of approximately 80 million cubic meters of cement is generated, and these are treated as industrial waste, and the reuse of hardened cement, including such concrete waste, has become a social issue.
そこで、本発明は、このような従来の問題に鑑み、セメント硬化体を使用し、天然資源を用いずに高温ガス中に含まれる亜酸化窒素と二酸化炭素とを同工程で効率的に削減できる高温ガスの処理方法の提供を目的としてなされたものである。 In view of these conventional problems, the present invention uses hardened cement to efficiently reduce nitrous oxide and carbon dioxide contained in high-temperature gas in the same process without using natural resources. This was developed for the purpose of providing a method for processing high-temperature gas.
上述の如き従来の問題を解決するための請求項１に記載の発明の特徴は、亜酸化窒素及び二酸化炭素を含有する高温ガスの処理方法において、５０℃～９００℃の前記高温ガスと、セメントを含むセメント硬化体とを接触させ、前記セメント硬化体に含まれるセメント水和物を分解して酸化カルシウムを生成するとともに、該酸化カルシウムを前記ガスと接触させ、前記酸化カルシウムを触媒として前記亜酸化窒素を窒素と酸素に分解し、且つ、同工程で前記二酸化炭素を前記セメント硬化体に固定化することにある。　 The feature of the invention according to claim 1 for solving the above-mentioned conventional problems is that, in a method for treating high-temperature gas containing nitrous oxide and carbon dioxide, the high-temperature gas of 50 to 900 °C and cement to decompose the cement hydrate contained in the hardened cement body to produce calcium oxide, and also bring the calcium oxide into contact with the gas, and use the calcium oxide as a catalyst to generate calcium oxide. The purpose is to decompose nitrogen oxide into nitrogen and oxygen, and to fix the carbon dioxide in the hardened cement body in the same process.　
請求項２の記載の発明の特徴は、請求項１の構成に加え、前記高温ガスは、基準容積当りに亜酸化窒素を５０ｐｐｍ以上、二酸化炭素を５％以上、水分量を１０％以上含有することにある。　 The feature of the invention described in claim 2 is that in addition to the configuration of claim 1, the high temperature gas contains 50 ppm or more of nitrous oxide, 5% or more of carbon dioxide, and 10% or more of water content per reference volume. There is a particular thing.　
請求項３に記載の発明の特徴は、請求項１又は２の構成に加え、前記高温ガスを４５０℃～７００℃に調整することにある。　 A feature of the invention according to claim 3, in addition to the configuration of claim 1 or 2, is that the high temperature gas is adjusted to 450°C to 700°C.　
請求項４に記載の発明の特徴は、請求項１又は２の構成に加え、前記セメント硬化体は、廃セメント材によって構成されていることにある。　 A feature of the invention as set forth in claim 4 is that, in addition to the structure of claim 1 or 2, the cement hardened body is made of waste cement material.　
請求項５に記載の発明の特徴は、請求項１又は２の構成に加え、前記セメント硬化体は、コンクリート材から固化前に骨材を分離して除去した残分により構成されていることにある。　 A feature of the invention set forth in claim 5 is that, in addition to the structure of claim 1 or 2, the cement hardened body is composed of a residue obtained by separating and removing aggregate from concrete material before solidification. be.　
請求項６に記載の発明の特徴は、請求項１又は２の構成に加え、前記二酸化炭素を固定したセメント硬化体を回収してセメント系材料として再利用することにある。　 In addition to the structure of claim 1 or 2, the invention according to claim 6 is characterized in that the hardened cement body in which the carbon dioxide is fixed is recovered and reused as a cement material.　
請求項７に記載の発明の特徴は、請求項１又は２の構成に加え、前記高温ガスは、下水汚泥焼却場から発生する排ガスであることにある。 A seventh aspect of the invention is characterized in that, in addition to the first or second aspect, the high-temperature gas is exhaust gas generated from a sewage sludge incinerator.
本発明に係る高温ガスの処理方法は、請求項１に記載の構成を具備することによって、天然資源である石灰石や消石灰粉粒体を用いずに、同一工程で排ガス等の亜酸化窒素及び二酸化炭素を含有する高温ガス中の温室効果ガスである亜酸化窒素及び二酸化炭素を分解し、固定することができる。また、年間排出量が約３５００万トン以上にも及ぶコンクリート廃材を好適に再利用することができる。　 The method for treating high-temperature gas according to the present invention includes the configuration set forth in claim 1, thereby eliminating nitrous oxide and slaked lime from exhaust gas in the same process without using limestone or slaked lime powder, which are natural resources. Nitrous oxide and carbon dioxide, which are greenhouse gases in high-temperature gases containing carbon, can be decomposed and fixed. In addition, concrete waste material, whose annual amount is about 35 million tons or more, can be suitably reused.　
また、本発明において、請求項２に記載の構成を具備することによって、亜酸化窒素や二酸化炭素の量が多くなるので、温室効果ガスを効率的に削減することができ、且つ、廃棄物であるセメント硬化体をより多く使用することができる。また、セメント硬化体による二酸化炭素の固定量の増加を図ることができる。　 Further, in the present invention, by providing the structure according to claim 2, the amount of nitrous oxide and carbon dioxide is increased, so greenhouse gases can be efficiently reduced, and waste can be reduced. It is possible to use more of a certain hardened cement. Further, it is possible to increase the amount of carbon dioxide fixed by the hardened cement body.　
また、本発明において、請求項３に記載の構成を具備することによって、亜酸化窒素の分解及びセメント硬化体への二酸化炭素の固定を促進することができる。　 Further, in the present invention, by providing the structure according to claim 3, decomposition of nitrous oxide and fixation of carbon dioxide to the hardened cement body can be promoted.　
また、本発明において、請求項４乃至５に記載の構成を具備することによって、不要となったコンクリート廃材や戻りコンクリート等を効率的に再利用することができる。　 Further, in the present invention, by providing the configurations according to claims 4 and 5, it is possible to efficiently reuse unnecessary concrete waste materials, returned concrete, and the like.　
また、本発明において、請求項６に記載の構成を具備することによって、セメント硬化体をセメント系材料として再利用することができるとともに、地球温暖化対策として有効活用することができる。　 Moreover, in the present invention, by providing the structure according to claim 6, the hardened cement body can be reused as a cement-based material and can be effectively utilized as a measure against global warming.　
さらに、本発明において、請求項７に記載の構成を具備することによって、下水汚泥焼却場から発生する排ガスに含有される亜酸化窒素及び二酸化炭素を分解し、固定することができる。 Furthermore, in the present invention, by providing the configuration according to claim 7, nitrous oxide and carbon dioxide contained in exhaust gas generated from a sewage sludge incinerator can be decomposed and fixed.
本発明に係る高温ガスの処理方法に使用する処理装置の一例を示す概略断面図である。1 is a schematic cross-sectional view showing an example of a processing apparatus used in the high-temperature gas processing method according to the present invention. 本発明に係る高温ガスの処理方法の効果確認試験に使用した装置の概略を示す縦断面図である。1 is a vertical cross-sectional view schematically showing an apparatus used in an effect confirmation test of a high-temperature gas processing method according to the present invention. 同上の効果確認試験における亜酸化窒素の削減率と温度との関係を示すグラフである。It is a graph showing the relationship between the reduction rate of nitrous oxide and temperature in the same effect confirmation test as above. 同上の二酸化炭素の削減率と温度との関係を示すグラフである。It is a graph which shows the relationship between the reduction rate of carbon dioxide and temperature same as the above. 同上の温室効果ガス全体の削減率と温度との関係を示すグラフである。It is a graph showing the relationship between the overall reduction rate of greenhouse gases same as above and temperature. 同上の各温度における亜酸化窒素の削減率と時間との関係を示すグラフである。It is a graph which shows the relationship between the reduction rate of nitrous oxide and time at each temperature same as the above. 同上の各温度における二酸化炭素の削減率と時間との関係を示すグラフである。It is a graph which shows the relationship between the reduction rate of carbon dioxide and time at each temperature same as the above. 同上の温室効果ガス全体の削減率と時間との関係を示すグラフである。It is a graph showing the relationship between the overall reduction rate of greenhouse gases same as above and time. 同上のセメント硬化体としてスラッジを使用した際の温度６００℃における亜酸化窒素の削減率と時間との関係を示すグラフである。It is a graph showing the relationship between the reduction rate of nitrous oxide and time at a temperature of 600° C. when sludge is used as the cement hardening body same as above. 同上の温度６００℃における二酸化炭素の削減率と時間との関係を示すグラフである。It is a graph which shows the relationship between the reduction rate of carbon dioxide and time at the temperature of 600 degreeC same as the above. 同上の温室効果ガス全体の削減率と時間との関係を示すグラフである。It is a graph showing the relationship between the overall reduction rate of greenhouse gases same as above and time.
次に、本発明に係る高温ガスの処理方法の実施態様を図１に示した実施例に基づいて説明する。　 Next, an embodiment of the high temperature gas processing method according to the present invention will be described based on the embodiment shown in FIG.　
本実施例では、特に図示しないが、下水汚泥焼却場等において下水汚泥等が焼却炉４で焼却され、焼却炉４より排出された高温ガス（高温排ガス）が焼却炉４の下流側に設置された処理装置１に送られ、処理装置１において亜酸化窒素を分解、二酸化炭素をセメント硬化体２に固定して処理するようになっている。　 In this embodiment, although not particularly shown, sewage sludge, etc. is incinerated in an incinerator 4 at a sewage sludge incinerator, etc., and high-temperature gas (high-temperature exhaust gas) discharged from the incinerator 4 is installed downstream of the incinerator 4. In the processing device 1, the nitrous oxide is decomposed and the carbon dioxide is fixed in the hardened cement body 2 for processing.　
処理装置１は、例えば、図１に示すように、傾斜した管状の処理用炉体３と、処理用炉体３内に焼却炉４から排出された高温ガス（高温排ガス）５を供給するガス供給手段と、処理用炉体３内にセメント硬化体２を供給するセメント硬化体供給手段６とを備え、処理用炉体３内で亜酸化窒素及び二酸化炭素を含有する高温ガス５とセメント硬化体２とを接触させ、処理済みガスを排気管７から排出するようになっている。　 As shown in FIG. 1, the processing apparatus 1 includes, for example, an inclined tubular processing furnace body 3 and a gas supplying gas (high-temperature exhaust gas) 5 discharged from an incinerator 4 into the processing furnace body 3. and a cement hardening body supply means 6 for supplying the cement hardening body 2 into the processing furnace body 3, and cement hardening with the high temperature gas 5 containing nitrous oxide and carbon dioxide in the treatment furnace body 3. The treated gas is brought into contact with the body 2 and the treated gas is discharged from the exhaust pipe 7.　
尚、処理装置１から排出された処理済みガスは、亜酸化窒素及び二酸化炭素の濃度を計測した後、特に図示しないが、冷却塔、集塵機、排煙処理塔等を経て煙突より大気に排出するようになっている。　 After measuring the concentration of nitrous oxide and carbon dioxide, the treated gas discharged from the processing device 1 is discharged into the atmosphere from a chimney through a cooling tower, a dust collector, a flue gas treatment tower, etc. (not shown in the figure). It looks like this.　
処理用炉体３は、一定の長さを有する閉鎖された円筒形状に形成され、外周部に配置されたヒーター等からなる温度調節手段８により内部雰囲気を所定の温度に調節でき、供給された高温ガス５をそのままの温度で利用してもよく、状況に応じて温室効果ガスをより効率よく削減できる温度に制御してもよい。　 The processing furnace body 3 is formed in a closed cylindrical shape with a certain length, and the internal atmosphere can be adjusted to a predetermined temperature by a temperature control means 8 consisting of a heater etc. arranged on the outer periphery. The high-temperature gas 5 may be used as it is, or may be controlled to a temperature that allows greenhouse gases to be more efficiently reduced depending on the situation.　
また、処理用炉体３は、特に図示しないが、回転手段によって管軸を中心に円周方向に回転できるようにしてもよい。　 Further, although not particularly shown, the processing furnace body 3 may be configured to be rotatable in the circumferential direction around the tube axis by a rotating means.　
ガス供給手段は、焼却炉４に接続されたガス供給管９を備え、このガス供給管９を通して焼却炉４より排気された高温ガス５を処理用炉体３内に供給するようになっている。　 The gas supply means includes a gas supply pipe 9 connected to the incinerator 4, and is configured to supply high-temperature gas 5 exhausted from the incinerator 4 into the processing furnace body 3 through this gas supply pipe 9. .　
尚、排気管７から排出された処理済みガスは、回収して再加熱手段１０によって再加熱した後、ガス供給管９に送込み、再度処理用炉体３内に供給するようにしてもよい。　 Note that the treated gas discharged from the exhaust pipe 7 may be recovered and reheated by the reheating means 10, and then sent to the gas supply pipe 9 and supplied into the processing furnace body 3 again. .　
セメント硬化体供給手段６は、処理用炉体３内と上流側で連通する供給側ベルトコンベア１１と、供給側ベルトコンベア１１上に別プラントで調整されたセメント硬化体２を投入するホッパ等のセメント硬化体供給源１２とを備え、供給側ベルトコンベア１１によりセメント硬化体２が上流側から処理用炉体３内に送り込まれ、処理用炉体３内を傾斜に沿って所定の速度で通過した後、処理用炉体３内と下流側で連通する排出側ベルトコンベア１３によって排出されるようになっている。　 The hardened cement supply means 6 includes a supply belt conveyor 11 that communicates with the inside of the processing furnace 3 on the upstream side, and a hopper or the like into which the hardened cement 2 prepared in a separate plant is fed onto the supply belt conveyor 11. The hardened cement body 2 is fed into the processing furnace body 3 from the upstream side by the supply side belt conveyor 11, and passes through the treatment furnace body 3 along the slope at a predetermined speed. After that, it is discharged by a discharge side belt conveyor 13 that communicates with the inside of the processing furnace body 3 on the downstream side.　
尚、セメント硬化体２の供給は、バッチ式であってもよく、連続的に投入されるようにしてもよい。　 The hardened cement body 2 may be supplied either batchwise or continuously.　
また、処理用炉体３から排出されたセメント硬化体２は、回収され、再度処理用炉体３内に投入されるようにしてもよい。　 Moreover, the cement hardened body 2 discharged from the processing furnace body 3 may be recovered and put into the processing furnace body 3 again.　
次に、上述の処理装置１を使用した高温ガスの処理方法の具体的手順を示す。　 Next, a specific procedure of a high temperature gas processing method using the above-mentioned processing apparatus 1 will be described.　
先ず、建造物の解体等に生じたセメント廃材、モルタル廃材、コンクリート廃材や、工事現場において使用されず残存した残セメント、残モルタル、残コンクリートや、工事現場において使用されず工場に戻された戻りセメント、戻りモルタル、戻りコンクリート（以下、総称してセメント硬化体２という）を別プラントにおいて調整し、セメント硬化体供給手段６により処理用炉体３内への供給を開始する。　 First, waste cement, mortar, and concrete generated during the demolition of buildings, residual cement, mortar, and concrete left unused at the construction site, and waste returned to the factory without being used at the construction site. Cement, returned mortar, and returned concrete (hereinafter collectively referred to as hardened cement 2) are prepared in a separate plant, and the hardened cement supply means 6 starts supplying them into the processing furnace 3.　
尚、これらのセメント硬化体２については、セメントが混入したものであればよく、セメント混入量が多いほど好ましい。また、廃コンクリート材については、粉砕し、骨材を除去し、戻りコンクリート材については、固化前に骨材を分離して除去した残分により構成することが、亜酸化窒素及び二酸化炭素の削減には好ましい。　 It should be noted that these hardened cement bodies 2 may be those mixed with cement, and the larger the amount of cement mixed in, the more preferable. In addition, waste concrete material is crushed and aggregate is removed, and returned concrete material is composed of the residue after separating and removing aggregate before solidification, which reduces nitrous oxide and carbon dioxide. preferred.　
一方、下水汚泥焼却場で発生した排ガス、即ち、下水汚泥等を焼却炉４で焼却した際に生じた亜酸化窒素及び二酸化炭素を含む高温ガスを処理装置１（処理用炉体３）にガス供給管９を通して送り込み、５０℃～９００℃、好ましくは４５０℃～７００℃の所定の温度に調整した処理用炉体３内において高温ガス中の亜酸化窒素及び二酸化炭素とセメント硬化体２とを接触させる。　 On the other hand, exhaust gas generated at the sewage sludge incinerator, that is, high-temperature gas containing nitrous oxide and carbon dioxide generated when sewage sludge and the like are incinerated in the incinerator 4, is transferred to the processing device 1 (processing furnace body 3). Nitrous oxide and carbon dioxide in the high-temperature gas and the cement hardening body 2 are fed through the supply pipe 9 into the processing furnace body 3 adjusted to a predetermined temperature of 50° C. to 900° C., preferably 450° C. to 700° C. bring into contact.　
高温ガス５は、基準容積当りに亜酸化窒素を５０ｐｐｍ以上、二酸化炭素を５％以上、水分量を１０％以上含有するものとし、必要に応じて水分を追加して調整する。　 The high temperature gas 5 contains 50 ppm or more of nitrous oxide, 5% or more of carbon dioxide, and 10% or more of moisture per standard volume, and is adjusted by adding moisture as necessary.　
高温ガス中の二酸化炭素は、以下の式（１）（２）に示すように、セメント硬化体２中に含まれる酸化カルシウム、水酸化カルシウムと反応し、常温でも炭酸カルシウムを生成し、高温ほど反応が促進され、効率よくセメント硬化体２に固定される。　ＣａＯ＋ＣＯ２→ＣａＣＯ３　　　　　　　　…（１）　Ｃａ（ＯＨ）２＋ＣＯ２→ＣａＣＯ３＋Ｈ２Ｏ　…（２）尚、（１）式の反応では、水が無いと反応し難いため、高温ガス５中に水分が多いことが好ましい。　 As shown in equations (1) and (2) below, carbon dioxide in the high-temperature gas reacts with calcium oxide and calcium hydroxide contained in the hardened cement 2, producing calcium carbonate even at room temperature, and as the temperature increases The reaction is promoted and the cement is efficiently fixed to the hardened cement body 2. CaO+CO 2 →CaCO 3 …(1) Ca(OH) 2 +CO 2 →CaCO 3 +H 2 O …(2) In addition, in the reaction of formula (1), it is difficult to react without water, so in the high temperature gas 5 Preferably, the water content is high.
一方、セメント硬化体２中の水酸化カルシウムは、４５０～６００℃で酸化カルシウムと水に分解され（Ｃａ（ＯＨ）２→ＣａＯ＋Ｈ２Ｏ）
、新たに酸化カルシウムが生成される。この生成された酸化カルシウムは、ガス中の亜酸化窒素と接触することで、亜酸化窒素の分解を促進する。また、二酸化炭素が新たに生成された酸化カルシウムとも反応し、セメント硬化体２に固定される。　 On the other hand, calcium hydroxide in the hardened cement body 2 is decomposed into calcium oxide and water at 450 to 600°C (Ca(OH) 2 →CaO+H 2 O).
, new calcium oxide is produced. This generated calcium oxide comes into contact with nitrous oxide in the gas, thereby promoting the decomposition of nitrous oxide. Further, carbon dioxide also reacts with newly generated calcium oxide and is fixed to the hardened cement body 2.
ガス中の亜酸化窒素は、２００℃以上の温度で酸化カルシウムと接触すると酸素と窒素に分解され、３５０℃以上では更に分解が進み、高温になるほど分解が促進される。　 Nitrous oxide in the gas is decomposed into oxygen and nitrogen when it comes into contact with calcium oxide at a temperature of 200°C or higher, further decomposed at 350°C or higher, and the decomposition is accelerated as the temperature increases.　
特に、４５０～７００℃の温度域では、セメント硬化体２から新たに酸化カルシウムが生成されるとともに雰囲気が高温になるので、亜酸化窒素の分解がより促進される。　 In particular, in the temperature range of 450 to 700° C., calcium oxide is newly generated from the hardened cement body 2 and the atmosphere becomes high temperature, so that the decomposition of nitrous oxide is further promoted.　
一方、７００℃程度より上の温度では、ＣａＣＯ３→ＣａＯ＋ＣＯ２の脱炭酸反応によりＣＯ２が新たに発生する。　 On the other hand, at temperatures above about 700° C., CO 2 is newly generated due to the decarboxylation reaction of CaCO 3 →CaO+CO 2 .
これら各温度における化学反応で生成される物質の量は、セメント硬化体２の化学成分で変わる。　 The amount of substances produced by chemical reactions at each of these temperatures varies depending on the chemical composition of the hardened cement body 2.　
尚、処理用炉体３を回転させて内部のセメント硬化体２を攪拌しながら排ガスと接触させることで、効率よくガス中の亜酸化窒素及び二酸化炭素を削減することができる。　 Note that by rotating the processing furnace body 3 and bringing the hardened cement body 2 inside into contact with the exhaust gas while stirring, it is possible to efficiently reduce nitrous oxide and carbon dioxide in the gas.　
高温ガスは、セメント硬化体２と接触した後、回収して、再度処理装置１に戻すことも可能である。セメント硬化体２も同様に、ガスと接触後、再度処理装置１に戻して同じ処理を複数繰り返すこともできる。　 After the high-temperature gas comes into contact with the hardened cement body 2, it is also possible to recover it and return it to the processing device 1 again. Similarly, after contacting the cement hardened body 2 with the gas, it can be returned to the treatment device 1 again and the same treatment can be repeated multiple times.　
一方、ガスと接触して二酸化炭素が固定されたセメント硬化体２は、新たにセメント原料やコンクリート材料等のセメント系材として再利用することができる。　 On the other hand, the hardened cement body 2 in which carbon dioxide is fixed by contact with the gas can be reused as a new cement material such as a cement raw material or a concrete material.　
尚、セメント硬化体２は、本処理前（二酸化炭素の固定前）の段階でセメント硬化体２を粉砕し、骨材を除去している場合のみならず、セメント硬化体２に二酸化炭素を固定した後、粉砕し、骨材を除去した場合のいずれの場合であっても新たにセメント原料やコンクリート材料等のセメント系材として再利用することができ、二酸化炭素を固定したことで二酸化炭素排出を抑制し、地球温暖化対策として有効に活用することができる。また、骨材については、周囲に付着しているセメントペースト分が二酸化炭素を固定するため、再生骨材としてコンクリート材料（セメント系材）に再利用することで、地球温暖化対策に有効に活用することができる。　 In addition, the hardened cement body 2 is produced not only when the hardened cement body 2 is crushed and aggregate is removed at the stage before the main treatment (before fixation of carbon dioxide), but also when carbon dioxide is fixed in the hardened cement body 2. After that, it is pulverized and the aggregate is removed. In either case, it can be reused as a new cement raw material or cement material such as concrete material, and by fixing carbon dioxide, carbon dioxide emissions are reduced. can be effectively used as a countermeasure against global warming. In addition, as for aggregate, the cement paste attached to its surroundings fixes carbon dioxide, so by reusing it as recycled aggregate in concrete materials (cement-based materials), it can be used effectively to counter global warming. can do.　
亜酸化窒素が窒素と酸素に分解された処理済み排ガスは、熱交換器によって廃熱が回収され、管路を経て煙突等から大気中に放出される。　 The waste heat of the treated exhaust gas, in which nitrous oxide has been decomposed into nitrogen and oxygen, is recovered by a heat exchanger and released into the atmosphere from a chimney or the like through a pipe.　
このように構成された処理方法では、天然資源である石灰石や消石灰粉粒体を用いずに、セメント硬化体２と接触させて亜酸化窒素を窒素と酸素とに分解するとともに、同じ工程において二酸化炭素をセメント硬化体２に固定することができ、亜酸化窒素及び二酸化炭素の排出を温室効果ガスとしてトータル的に抑制することができる。さらに廃棄されているセメント硬化体２を好適に再利用することができる。　 In the treatment method configured in this way, nitrous oxide is decomposed into nitrogen and oxygen by contacting with the hardened cement 2, without using limestone or slaked lime powder, which are natural resources.In the same process, nitrous oxide is decomposed into nitrogen and oxygen. Carbon can be fixed in the hardened cement body 2, and emissions of nitrous oxide and carbon dioxide can be totally suppressed as greenhouse gases. Furthermore, the discarded cement hardened body 2 can be suitably reused.　
次に、本発明に係る高温ガスの処理方法の効果を確認した実験結果について説明する。尚、以下においては、亜酸化窒素をＮ２Ｏと、二酸化炭素をＣＯ２とそれぞれ化学式で適宜表記する。　 Next, experimental results confirming the effects of the high-temperature gas processing method according to the present invention will be explained. In the following, nitrous oxide is appropriately expressed as N 2 O, and carbon dioxide is expressed as CO 2 using chemical formulas.
（試料）　普通セメントを用い、Ｗ／Ｃ０．６のセメントペーストをホバートミキサで練り混ぜ、計３０Ｌのセメントペーストを作製し、それを複数のポリエチレン袋（直径５０ｍｍ、長さ５００ｍｍ）に入れ、材齢３週間、２０℃の気中で封緘養生を行ってセメント硬化体２を作製し、その後、ポリエチレン袋を除去し、セメント硬化体２をジョークラッシャーで粒径５ｍｍ以下に粉砕してセメント硬化体２の試料とし、ポリエチレン袋に入れて密閉する。　そして、試験の前日にセメント硬化体２を１０５℃で５時間乾燥し、試験に供した。（実験方法）　１．図２に示すように、処理用炉体３として外熱キルン（内径１５ｃｍ、長さ７０ｃｍ）を使用し、外熱キルンの内部の雰囲気温度が設定温度になるまでヒーターで加熱し、温度を安定させる。　２．次に、ステンレスバット（１２６×１５５×２７ｍｍ）にセメント硬化体２の試料１００ｇを入れたものを４つ準備し、素早く外熱キルン内に入れる。　３．試料投入後、速やかにＣＯ２を１０％、Ｎ２Ｏを１０００ｐｐｍ、それ以外を大気ガスとした混合ガスを１Ｌ/ｍｉｎでキルン内に３０分間流入する。　４．キルンの排出側ではＣＯ２濃度をモニタリングするとともに、サンプリングバッグでガスを１８Ｌ（残りの１２Ｌはモニタリング用に分岐）採取し、Ｎ２ＯおよびＣＯ２のガス濃度をガスクロマトグラフで分析する。　尚、温室効果ガス濃度については、Ｎ２Ｏ濃度を３００倍、ＣＯ２濃度を1倍として合計の温室効果ガス濃度を算出した。また、温室効果ガス削減率は、流入した温室効果ガス濃度０．４（Ｎ２Ｏ:１０００ｐｐｍ×３００、ＣＯ２:１０％×１）に対して、以下の計算式により本処理によって温室効果ガスを削減できた割合を算出した。（１－温室効果ガス濃度／０．４）×１００（％）　 (Sample) Using ordinary cement, mix cement paste with a W/C of 0.6 in a Hobart mixer to make a total of 30L of cement paste, put it into multiple polyethylene bags (diameter 50mm, length 500mm), and mix the cement paste with a W/C of 0.6 using a Hobart mixer. After 3 weeks of age, sealed curing was performed in air at 20°C to prepare a hardened cement body 2. After that, the polyethylene bag was removed and the hardened cement body 2 was crushed to a particle size of 5 mm or less with a jaw crusher to obtain a hardened cement body. Take the sample No. 2 and put it in a polyethylene bag and seal it. Then, on the day before the test, the hardened cement body 2 was dried at 105° C. for 5 hours and used for the test. (Experimental method) 1. As shown in Figure 2, an external heat kiln (inner diameter 15 cm, length 70 cm) is used as the processing furnace body 3, and the temperature is stabilized by heating with a heater until the ambient temperature inside the external heat kiln reaches the set temperature. let 2. Next, prepare four stainless steel vats (126 x 155 x 27 mm) containing 100 g of samples of hardened cement 2, and quickly put them into an external heating kiln. 3. Immediately after the sample is introduced, a mixed gas containing 10% CO 2 , 1000 ppm N 2 O, and the rest atmospheric gas flows into the kiln at 1 L/min for 30 minutes. 4. On the discharge side of the kiln, the CO 2 concentration is monitored, and 18 L of gas is collected using a sampling bag (the remaining 12 L is branched for monitoring), and the gas concentrations of N 2 O and CO 2 are analyzed using a gas chromatograph. Regarding the greenhouse gas concentration, the total greenhouse gas concentration was calculated by multiplying the N 2 O concentration by 300 times and the CO 2 concentration by 1 time. In addition, the greenhouse gas reduction rate is calculated using the following formula for the inflow greenhouse gas concentration of 0.4 (N 2 O: 1000 ppm x 300, CO 2 : 10% x 1). We calculated the rate at which we were able to reduce this. (1-Greenhouse gas concentration/0.4) x 100 (%)
（実施例１）　上記１～４の工程を５０℃～８５０℃の異なる温度において実施し、各温度におけるＮ２ＯおよびＣＯ２のガス濃度について分析した。その結果を表1及び図３～図５に示す。　　
Figure JPOXMLDOC01-appb-T000001
 (Example 1) The above steps 1 to 4 were carried out at different temperatures from 50° C. to 850° C., and the gas concentrations of N 2 O and CO 2 at each temperature were analyzed. The results are shown in Table 1 and Figures 3 to 5.
Figure JPOXMLDOC01-appb-T000001
以上の結果から、５０℃～９００℃の温度域で温室効果ガスである亜酸化窒素及び二酸化炭素の削減が確認された。一方、亜酸化窒素は、セメント硬化体２から酸化カルシウムが生成される温度４５０℃以上の温度域で大幅に窒素と酸素への分解が促進され、二酸化炭素は、常温（５０℃）～７００℃当りまでの温度域で最も効率よく削減されることが確認された。　 From the above results, it was confirmed that greenhouse gases nitrous oxide and carbon dioxide were reduced in the temperature range of 50°C to 900°C. On the other hand, the decomposition of nitrous oxide into nitrogen and oxygen is greatly accelerated in the temperature range of 450°C or higher, the temperature at which calcium oxide is generated from the hardened cement body 2, and the decomposition of carbon dioxide is accelerated at temperatures between room temperature (50°C) and 700°C. It was confirmed that the most efficient reduction occurred in the temperature range up to　
即ち、４５０℃～７００℃の温度域において、亜酸化窒素と二酸化炭素とがそれぞれ好適に削除され、温室ガスである亜酸化窒素と二酸化炭素とを同一工程においてトータルで効率よく削減できることが確認された。　 In other words, it has been confirmed that nitrous oxide and carbon dioxide are suitably removed in the temperature range of 450°C to 700°C, and that the greenhouse gases nitrous oxide and carbon dioxide can be efficiently reduced in total in the same process. Ta.　
（実施例２）　本実施例では、事前に試料の２０％となる水を霧状に噴霧して含水させ、上記１～４の工程を温度６００℃において実施し、Ｎ２ＯおよびＣＯ２のガス濃度について分析した。その結果を表２に示す。　　
Figure JPOXMLDOC01-appb-T000002
 (Example 2) In this example, 20% of the sample was atomized with water in advance to make it hydrated, and the above steps 1 to 4 were carried out at a temperature of 600°C to remove N 2 O and CO 2 . The gas concentration was analyzed. The results are shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
以上の結果から、高温ガス５中に水分量が多く含まれることにより、効率よく温室効果ガスである亜酸化窒素及び二酸化炭素が削減されることが確認された。　 From the above results, it was confirmed that by containing a large amount of water in the high temperature gas 5, greenhouse gases such as nitrous oxide and carbon dioxide can be efficiently reduced.　
（実施例３）　本実施例では、流入ガス（流入量２Ｌ／ｍｉｎ）にＣＯ２を１０％、Ｎ２Ｏを５００ｐｐｍ、４０ｖｏｌ％の水蒸気を加えて調整し、上記１～４の工程をキルン内温度４００℃～８５０℃の異なる温度において実施し、各温度におけるＮ２ＯおよびＣＯ２の両者のガス濃度が最も削減率の高い温度について分析した。　 (Example 3) In this example, the inflow gas (inflow rate 2 L/min) was adjusted by adding 10% CO 2 , 500 ppm N 2 O, and 40 vol% steam, and the above steps 1 to 4 were performed in a kiln. The analysis was carried out at different internal temperatures of 400° C. to 850° C., and the temperature at which the gas concentration of both N 2 O and CO 2 at each temperature had the highest reduction rate was analyzed.
また、試料には、セメント硬化体２に加え、さらに槽内において４日間常温で炭酸化させ、廃コンクリートのセメント微粉末を模擬したセメント硬化体２′の２種類を使用した。　 In addition to hardened cement 2, two types of hardened cement 2' were used as samples, which were carbonated in a tank at room temperature for 4 days to simulate fine cement powder from waste concrete.　
尚、セメント硬化体２は、戻りコンクリートなどのスラッジを想定したもので、セメント硬化体２′は、長年供用され炭酸化したコンクリートを破砕した廃コンクリートの微粉末を想定したものである（以後、セメント硬化体２を未炭酸化品、炭酸化させたセメント硬化体２´を炭酸化品と称する）。　 The hardened cement body 2 is assumed to be sludge such as returned concrete, and the hardened cement body 2' is assumed to be fine powder of waste concrete obtained by crushing concrete that has been used for many years and has become carbonated (hereinafter referred to as The hardened cement body 2 is referred to as an uncarbonated product, and the carbonated hardened cement body 2' is referred to as a carbonated product).　
以下に、未炭酸化品と炭酸化品の示差熱分析結果を示す。　　
Figure JPOXMLDOC01-appb-T000003
 The results of differential thermal analysis of the uncarbonated product and the carbonated product are shown below.
Figure JPOXMLDOC01-appb-T000003
さらに、本実施例では、未炭酸化品または炭酸化品を４つのステンレスバッドに１００ｇずつ置き、計４００ｇをキルンに入れる場合に加え、セメント硬化体２０００ｇを回転するキルン内に直接入れる場合とを実施し、両場合の反応を比較した。尚、セメント硬化体をキルンに直接投入する場合のガスのモニタリング方法は、キルンから流出させたガスをガス分析計に直接接続し、常時計測とした。　 Furthermore, in this example, in addition to the case where 100 g of uncarbonated or carbonated product is placed on each of four stainless steel buds and a total of 400 g is put into the kiln, there is also a case where 2000 g of hardened cement is directly put into the rotating kiln. The reactions in both cases were compared. In addition, when the cement hardened body was directly put into the kiln, the gas was monitored by connecting the gas flowing out from the kiln directly to a gas analyzer and constantly measuring it.　
結果を図６～図８に示す。なお、キルン炉内のガスの入れ替わりに時間を要するとともに、初期の反応で生じる脱水が多い場合に分析計を一時的に外している時間があることから、その時間を考慮して実験開始から５～１０分以降の傾向に着目した。　 The results are shown in FIGS. 6 to 8. It should be noted that it takes time for the gas in the kiln to be replaced, and there is also a time when the analyzer is temporarily removed when there is a lot of dehydration caused by the initial reaction. We focused on trends after ~10 minutes.　
以上の結果から、４００℃～７００℃の各温度において、温室効果ガスである亜酸化窒素及び二酸化炭素の削減効果が確認された。特に、６００℃において温室効果ガスである亜酸化窒素および二酸化炭素の削減率が最も高いことが確認された。また、６００℃では炭酸化の影響をうけた炭酸化品の場合であっても最も安定して温室効果ガスの削減率が高いことが確認された。　 From the above results, the effect of reducing greenhouse gases nitrous oxide and carbon dioxide was confirmed at each temperature from 400°C to 700°C. In particular, it was confirmed that the reduction rate of greenhouse gases nitrous oxide and carbon dioxide was highest at 600°C. Furthermore, it was confirmed that at 600°C, the greenhouse gas reduction rate was the most stable and the highest even in the case of carbonated products that were affected by carbonation.　
次に、実施例３で温室効果ガスに透過させた後の未炭酸化品および炭酸化品について、モルタルに再利用した際の各種物性について実験した結果について説明する。　 Next, the results of experiments on various physical properties when reusing the uncarbonated product and the carbonated product after being permeated with greenhouse gas in Example 3 as mortar will be explained.　
（実験方法）　実験は、ＪＩＳ　Ｒ　５２０１：セメントの物理試験に準拠し、配合、フロー試験、曲げ試験および圧縮試験を実施した。　 (Experimental Method) The experiment was carried out in accordance with JIS R 5201: Physical Test of Cement, including blending, flow test, bending test, and compression test.　
温室効果ガスの削減率が最も高く安定していた６００℃に使用した未炭酸化品および炭酸化品を、標準砂に置換率５％または１０％で絶乾状態のまま使用し、水中養生の後に材齢２８日強度を確認した。ブランクとして、試料を置換しない条件も作成した。実験結果を表４に示す。　　
Figure JPOXMLDOC01-appb-T000004
 The uncarbonated and carbonated products used at 600℃, which had the highest and most stable greenhouse gas reduction rate, were used in an absolutely dry state at a replacement rate of 5% or 10% with standard sand, and were cured in water. Afterwards, the strength was confirmed after 28 days of age. As a blank, conditions were also created in which the sample was not replaced. The experimental results are shown in Table 4.
Figure JPOXMLDOC01-appb-T000004
以上の結果から、温室効果ガスに透過させた後の未炭酸化品および炭酸化品を、モルタルの細骨材に５～１０％置換した場合の強度は、ブランクの場合と概ね同等でありセメント系材料として利用できることが確認された。　 From the above results, the strength when replacing 5 to 10% of the uncarbonated and carbonated products after permeation with greenhouse gases with fine aggregate in mortar is approximately the same as that of blank, and the strength of cement It was confirmed that it can be used as a system material.　
（実施例４）　本実施例では、実際の廃コンクリート材であるスラッジ脱水品（以下、スラッジという）を試料に使用し、実施例３と同様に流入ガス（流入量２Ｌ／ｍｉｎ）にＣＯ２を１０％、Ｎ２Ｏを５００ｐｐｍ、４０ｖｏｌ％の水蒸気を加えて調整したうえで、実施例３と同様に上記１～４工程をキルン内温度６００℃の温度において実施し、Ｎ２Ｏ及びＣＯ２の両者のガス濃度の削減率について検証した。　 (Example 4) In this example, a dehydrated sludge product (hereinafter referred to as sludge), which is an actual waste concrete material, was used as a sample, and as in Example 3, CO 2 was added to the inflow gas (inflow rate 2 L/min). After adjusting by adding 10% of N 2 O, 500 ppm of N 2 O, and 40 vol% of water vapor, the above steps 1 to 4 were carried out at a kiln internal temperature of 600° C. in the same manner as in Example 3, and N 2 O and CO The reduction rate of gas concentration in both cases was verified.
この試料は、既製杭の製造時に発生するスラッジを屋外にて固化させ、ジョーククラッシャーで粒径５ｍｍ以下に破砕したものである。試料は、４つのステンレスバッドに１００ｇずつ置き、計４００ｇをキルンに入れて実験を行った。　 This sample was made by solidifying the sludge generated during the manufacture of ready-made piles outdoors and crushing it into particles with a particle size of 5 mm or less using a jaw crusher. The experiment was conducted by placing 100 g of each sample on four stainless steel buds, and placing a total of 400 g into the kiln.　
以下にスラッジの示差熱分析結果を表に示す。　　
Figure JPOXMLDOC01-appb-T000005
 The table below shows the results of differential thermal analysis of sludge.
Figure JPOXMLDOC01-appb-T000005
結果を図９～図１１に示す。尚、キルン炉内のガスの入
れ替わりに時間を要するため、その時間を考慮して実験開始から５～１０分以降の傾向に着目した。　 The results are shown in FIGS. 9 to 11. Note that it takes time for the gas in the kiln to be replaced, so we took this time into consideration and focused on trends after 5 to 10 minutes from the start of the experiment.
以上の結果から、６００℃においてスラッジを用いたとき、亜酸化窒素および二酸化炭素の高い削減効果が確認され、セメント硬化体２としてのスラッジの有用性を確認した。 From the above results, when the sludge was used at 600° C., a high reduction effect on nitrous oxide and carbon dioxide was confirmed, and the usefulness of the sludge as the hardened cement body 2 was confirmed.
１　処理装置　２　セメント硬化体　３　処理用炉体　４　焼却炉　５　高温ガス　６　セメント硬化体供給手段　７　排気管　８　温度調節手段　９　ガス供給管１０　再加熱手段１１　供給側ベルトコンベア１２　セメント硬化体供給源１３　排出側ベルトコンベア 1. Processing equipment 2. Hardened cement 3. Furnace for processing 4. Incinerator 5. High temperature gas 6. Hardened cement supply means 7. Exhaust pipe 8. Temperature adjustment means 9. Gas supply pipe 10. Reheating means 11. Supply side belt conveyor 12. Hardened cement supply source 13 Discharge side belt conveyor

Claims (7)

  1. 亜酸化窒素及び二酸化炭素を含有する高温ガスの処理方法において、　５０℃～９００℃の前記高温ガスと、セメントを含むセメント硬化体とを接触させ、前記セメント硬化体に含まれるセメント水和物を分解して酸化カルシウムを生成するとともに、該酸化カルシウムを前記ガスと接触させ、前記酸化カルシウムを触媒として前記亜酸化窒素を窒素と酸素に分解し、且つ、同工程で前記二酸化炭素を前記セメント硬化体に固定化することを特徴とする高温ガスの処理方法。 In a method for treating high-temperature gas containing nitrous oxide and carbon dioxide, the high-temperature gas at 50°C to 900°C is brought into contact with a hardened cement body containing cement, and the cement hydrate contained in the hardened cement body is removed. Decomposing the nitrous oxide to produce calcium oxide, contacting the calcium oxide with the gas, using the calcium oxide as a catalyst to decompose the nitrous oxide into nitrogen and oxygen, and in the same step, converting the carbon dioxide into hardening the cement. A method for processing high-temperature gas characterized by immobilization in the body.
  2. 前記高温ガスは、基準容積当りに亜酸化窒素を５０ｐｐｍ以上、二酸化炭素を５％以上、水分量を１０％以上含有する請求項１に記載の高温ガスの処理方法。 2. The method for treating high-temperature gas according to claim 1, wherein the high-temperature gas contains 50 ppm or more of nitrous oxide, 5% or more of carbon dioxide, and 10% or more of water per reference volume.
  3. 前記高温ガスを４５０℃～７００℃に調整する請求項１又は２に記載の高温ガスの処理方法。 The method for treating high temperature gas according to claim 1 or 2, wherein the high temperature gas is adjusted to a temperature of 450°C to 700°C.
  4. 前記セメント硬化体は、廃セメント材によって構成されている請求項１又は２に記載の高温ガスの処理方法。 3. The method for treating high-temperature gas according to claim 1, wherein the hardened cement body is made of waste cement material.
  5. 前記セメント硬化体は、コンクリート材から固化前に骨材を分離して除去した残分により構成されている請求項１又は２に記載の高温ガスの処理方法。 3. The method for treating high-temperature gas according to claim 1, wherein the hardened cement is composed of a residue obtained by separating and removing aggregate from concrete material before solidification.
  6. 前記二酸化炭素を固定したセメント硬化体を回収してセメント系材料として再利用する請求項１又は２に記載の高温ガスの処理方法。 3. The high-temperature gas processing method according to claim 1, wherein the hardened cement body in which the carbon dioxide is fixed is recovered and reused as a cement material.
  7. 前記高温ガスは、下水汚泥焼却場から発生する排ガスである請求項１又は２に記載の高温ガスの処理方法。   The high temperature gas processing method according to claim 1 or 2, wherein the high temperature gas is exhaust gas generated from a sewage sludge incinerator.​
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