WO2019111540A1 - Method for producing reformed coal - Google Patents

Method for producing reformed coal Download PDF

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WO2019111540A1
WO2019111540A1 PCT/JP2018/038445 JP2018038445W WO2019111540A1 WO 2019111540 A1 WO2019111540 A1 WO 2019111540A1 JP 2018038445 W JP2018038445 W JP 2018038445W WO 2019111540 A1 WO2019111540 A1 WO 2019111540A1
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coal
dry
oxidation treatment
comparative example
distilled
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PCT/JP2018/038445
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French (fr)
Japanese (ja)
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彰伸 今村
小菅　克志
小水流　広行
亘 谷奥
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新日鉄住金エンジニアリング株式会社
新日鐵住金株式会社
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Priority to AU2018378746A priority Critical patent/AU2018378746B2/en
Priority to CN201880077972.7A priority patent/CN111433330A/en
Publication of WO2019111540A1 publication Critical patent/WO2019111540A1/en

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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L9/00—Treating solid fuels to improve their combustion
    • C10L9/02—Treating solid fuels to improve their combustion by chemical means
    • C10L9/06—Treating solid fuels to improve their combustion by chemical means by oxidation
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L9/00—Treating solid fuels to improve their combustion
    • C10L9/08—Treating solid fuels to improve their combustion by heat treatments, e.g. calcining

Definitions

  • the present disclosure relates to a method of producing modified coal.
  • an object of this invention is to provide the manufacturing method of the modification coal which can manufacture the modification coal in which the spontaneous ignition property was fully suppressed with high yield.
  • the present invention comprises a dry distillation step of dry-distilling coal at 300 to 650 ° C. to obtain dry-distilled carbon, and an oxidation treatment step of oxidizing dry-distilled carbon at a temperature range of over 200 ° C. and 240 ° C. or less for 10 to 60 minutes. Providing a method of producing modified coal.
  • oxidation treatment of raw material carbon is performed at a temperature range of over 200 ° C. and less than 240 ° C. for 10 to 60 minutes.
  • the oxidation treatment is performed under such conditions, the surface component of the raw material carbon is oxidized to stabilize the surface state, and hence it is considered that the self-heating property is reduced and the spontaneous ignition property is suppressed.
  • the loss due to self-combustion can be suppressed, and the yield can be increased.
  • the above-mentioned manufacturing method has a dry distillation step of dry-distilling coal to obtain dry-distilled carbon prior to the oxidation treatment step.
  • Dry distillation of coal is effective as a means of upgrading coal.
  • the yield at the dry distillation tends to be high while the spontaneous ignition tends to be high.
  • the self heating property can be reduced by the oxidation treatment step. For this reason, even if the dry distillation temperature in the dry distillation step is 650 ° C. or lower, the spontaneous ignition can be suppressed. Therefore, it is possible to produce a high grade, reformed coal with sufficiently suppressed spontaneous combustion property, with high yield.
  • the above manufacturing method may have a drying step of drying coal at 150 ° C. or less before the oxidation treatment step. Since the moisture of coal is reduced by this, a higher quality modified coal can be obtained by an oxidation treatment process or a dry distillation process and an oxidation treatment process.
  • the above-mentioned production method may have a combustion step of burning a gas containing volatile components generated by dry distillation of coal in a combustion furnace.
  • the dry-distilled coal be oxidized by the exhaust gas containing oxygen from the combustion furnace.
  • the present invention can provide a method for producing a modified coal capable of producing a modified coal with sufficiently suppressed spontaneous ignition property with high yield.
  • FIG. 1 is a flowchart showing an example of a method for producing modified coal.
  • FIG. 2 is a graph showing the results of the spontaneous ignition evaluation test of Examples 1 and 2 and Reference Examples 1 and 2 and Comparative Examples 1 to 4.
  • FIG. 3 is a graph showing the time-dependent change of the calorific value of dry-distilled carbon of Comparative Examples 5 to 8 having different dry distillation degrees.
  • FIG. 4 is a graph showing time-dependent changes in calorific value of the modified coals of Example 3 and Reference Example 4 and Comparative Examples 9 and 10 having different oxidation treatment temperatures and the dry-distilled carbon of Comparative Example 6.
  • FIG. 1 is a flowchart showing an example of a method for producing modified coal.
  • FIG. 2 is a graph showing the results of the spontaneous ignition evaluation test of Examples 1 and 2 and Reference Examples 1 and 2 and Comparative Examples 1 to 4.
  • FIG. 3 is a graph showing the time-dependent change of the calorific value of dry-distilled carbon of Comparative Examples 5 to 8 having different dry distillation degrees.
  • FIG. 5 is a graph showing the concentrations of carbon monoxide and carbon dioxide in the exhaust gas at the time of the oxidation treatment of Examples 5, 6 and Reference Example 7 and Comparative Examples 11-13.
  • FIG. 6 is a diagram showing the results of infrared spectroscopic analysis of Comparative Example 6, Comparative Example 14 and Comparative Example 15.
  • FIG. 7 is a graph showing the results of thermogravimetric analysis of Comparative Examples 16 to 19 and Examples 8, 9 and Reference Example 10 in which the oxidation treatment temperature is different.
  • FIG. 8 is a graph showing the results of differential thermal analysis of Comparative Examples 16 to 19, and Examples 8 and 9, and Reference Example 10 having different oxidation treatment temperatures.
  • FIG. 10 is a graph showing the results of the spontaneous firing evaluation test.
  • the method for producing modified coal according to the present embodiment includes a dry distillation step of dry-distilling coal at 300 to 650 ° C. to obtain dry-distilled carbon, and an oxidation treatment of oxidizing dry-distilled carbon at a temperature range of 200 ° C. to 240 ° C. It has a process.
  • dry-distilled coal tends to ignite spontaneously more than dry coal in coal.
  • by performing an oxidation treatment step under predetermined conditions on dry-distilled coal having a surface condition different from that of coal and its dry coal reformed coal in which spontaneous ignition is sufficiently suppressed is obtained from dry-distilled carbon. be able to.
  • the dry distillation step is a step of dry-distilling coal at 300 to 650 ° C. to obtain dry-distilled carbon.
  • the water content of the coal is reduced at the beginning of the dry distillation process.
  • the dry distillation step is preferably performed in a temperature range of 300 to 600.degree. This makes it possible to maintain a high yield while sufficiently promoting the carbonization of coal.
  • the dry distillation step can be performed using a conventional dry distillation furnace such as a vertical shaft furnace, a coke oven, or a tunnel kiln furnace.
  • the volatile matter (VM) of the dry-distilled carbon obtained in the dry distillation step is preferably 10 to 30% by mass.
  • Such dry-distilled carbon usually has high spontaneous ignition properties, but in the present embodiment, it is possible to suppress the spontaneous ignition properties by performing an oxidation treatment step after the dry distillation step. Therefore, high yield can be realized.
  • the coal may contain low grade coal or may contain high grade coal. When low grade coal is contained, it is preferable to perform the drying process mentioned later before an oxidation treatment process. However, it is not always essential to carry out the drying step.
  • the particle size of the raw material carbon may be, for example, 50 mm or less, 30 mm or less, or 10 mm or less.
  • the oxidation treatment step by setting the temperature (oxidation treatment temperature) at which oxidation treatment of dry-distilled carbon is carried out in a range exceeding 200 ° C., the surface of dry-distilled carbon is sufficiently reformed to sufficiently suppress spontaneous ignition. Can be obtained.
  • the oxidation treatment temperature By setting the oxidation treatment temperature to 240 ° C. or less, the reduction of the volatile component in the oxidation treatment process is suppressed, and the modified coal can be produced with a high yield.
  • the oxidation treatment temperature is preferably 210 to 240 ° C., more preferably 220 to 240 ° C., from the viewpoint of achieving both suppression of spontaneous ignition and improvement of yield at a higher level.
  • the oxidation treatment step may not be performed at a constant oxidation treatment temperature, and the oxidation treatment temperature may fluctuate within the above-mentioned range.
  • the time of the oxidation treatment step is 10 to 60 minutes from the viewpoint of producing the modified coal with high yield. From the viewpoint of sufficiently suppressing the spontaneous ignition, the time of the oxidation treatment step may be 15 to 60 minutes.
  • the atmosphere in the oxidation treatment step is not particularly limited as long as it is an atmosphere containing oxygen, and may be air or a mixed atmosphere of an inert gas such as nitrogen and oxygen. Moreover, it may be the exhaust gas of a combustion furnace.
  • the oxygen concentration may be, for example, 2 to 13% by volume or 3 to 10% by volume from the viewpoint of safety and the efficiency of the oxidation treatment. This "volume%" is a volume ratio in the conditions of a standard state (25 degreeC, 100 kPa).
  • the volatile content (VM) of the modified coal may be 5% by mass or more, or 10% by mass or more from the viewpoint of enhancing the usefulness as a fuel.
  • the volatile content (VM) of the modified coal may be 30% by mass or less or 25% by mass or less from the viewpoint of further reducing the spontaneous ignition property.
  • the volatile matter content in this specification is a value of the anhydrous basis measured based on the "square electric furnace method" of JISM 8812: 2006.
  • the manufacturing method of the present embodiment it is possible to manufacture the modified coal in which the spontaneous combustion property is sufficiently suppressed at a high yield.
  • Such reformed coal can also be used effectively as a fuel because it can contain a certain amount of volatile matter.
  • it is highly useful as a fuel, and it is possible to safely carry out storage of coal in a yard, and on-shore / sea transportation from a coal-producing area.
  • the method for producing modified coal according to another embodiment includes a drying step of drying coal at 150 ° C. or less before the above-mentioned dry distillation step.
  • a drying step of drying coal at 150 ° C. or less before the above-mentioned dry distillation step.
  • low-grade coal having a high water content for example, lignite and sub-bituminous coal having a water content of 50% by mass or more
  • the coal is dried by heating, for example, to a temperature range of 40 to 150.degree.
  • the drying step may be performed in air or in an inert gas atmosphere. Alternatively, it may be performed in the exhaust gas of a combustion furnace.
  • the water content of coal is reduced to, for example, 20% by mass or less.
  • the drying step may be performed using a common electric furnace or the like, or may be performed using an indirect heater or an air fluidized bed dryer.
  • the time of the drying step is not particularly limited, and can be adjusted depending on the moisture content of coal, the particle size of coal, and the like.
  • the particle size of the modified coal may be, for example, 50 mm or less, or 10 mm or less.
  • the modified coal obtained by the above-mentioned production method may be classified to be divided into particles (for example, particles with a particle diameter of 3 mm or more) and powders (for example, particles with a particle diameter of less than 3 mm).
  • the powdery modified carbon (powder) obtained by classification may be molded with or without a binder, and may be mixed with the particulate modified carbon (particles) obtained by classification as well.
  • FIG. 1 is a view showing an example of an apparatus configuration for performing a method of manufacturing modified coal according to an embodiment.
  • the drying process is performed in the drying apparatus 10
  • the dry distillation process is performed in the dry distillation apparatus 20
  • the oxidation treatment process is performed in the oxidation treatment apparatus 30.
  • the gas containing volatile components generated from the dry distillation apparatus 20 is consumed as a fuel gas in the combustion furnace 40 (combustion process).
  • the drying device 10 may be, for example, a conventional dryer.
  • Examples of the oxidation treatment apparatus 30 include a conventional electric furnace.
  • the exhaust gas generated by burning the fuel gas containing the volatile component in the combustion furnace 40 usually contains about 5 to 10% by volume of oxygen.
  • the exhaust gas generated in the combustion furnace 40 may be used as a heating gas in the drying apparatus 10.
  • Example 1 [Manufacturing of modified coal]
  • Commercially available coal for boilers, sub-bituminous coal (Adaro coal from Indonesia), was dried in the air using a drier to obtain dried coal (drying step).
  • the heating temperature in the drying step was 150 ° C., and the heating time was 30 minutes.
  • the volatile matter (VM) of the obtained dried coal was 50% by mass, and the water content was 10% by mass or less.
  • the obtained dried coal was subjected to dry distillation using a dry distillation furnace to obtain dry distilled carbon (dry distillation step).
  • the heating temperature in the dry distillation step was 430 ° C., and the heating time was 40 minutes.
  • the volatile matter (VM) of dry-distilled carbon was 25% by mass.
  • the dry-distilled carbon obtained was oxidized using an electric furnace to produce granular modified carbon (particle size: about 1 to 3 mm) (oxidation treatment step).
  • the conditions for the oxidation treatment were a mixed gas atmosphere of nitrogen gas and oxygen gas (oxygen concentration: 8% by volume), a heating temperature of 240 ° C., and a heating time of 40 minutes.
  • Example 2 Modified coal was produced in the same manner as in Example 1 except that the heating temperature in the oxidation treatment step was 210 ° C. Then, in the same manner as in Example 1, a spontaneous ignition evaluation test was conducted. The results were as shown in curve A2 of FIG.
  • Example 4 Dry carbon was obtained in the same manner as Example 1.
  • the volatile matter (VM) of the dried charcoal was 50% by mass, and the water content was 10% by mass or less.
  • the pyrophoricity evaluation test of the obtained dried coal was conducted. The results were as shown in curve D1 of FIG.
  • the dry-distilled carbon (curve E1) of Comparative Example 1 in which the oxidation treatment step was not performed generated heat to 250 ° C. or more in about one hour. That is, the modified coal was the highest in spontaneous ignition.
  • the dry charcoal (curve D1) of Comparative Example 4 was lower in pyrophoric property than the dry-distilled charcoal (curve E1) of Comparative Example 1.
  • the spontaneous ignition property of the modified coal of Example 2 was lower than that of the commercially available subbituminous coal, and the spontaneous ignition property of the modified coal of Example 1 was lower than that of the commercially available bituminous coal. Thus, it was confirmed that the pyrophoric properties of the modified coals of Example 1 and Example 2 were sufficiently suppressed despite being carbonized.
  • Differential scanning calorimetry (DSC measurement) of the prepared dried charcoal was performed using a commercially available measuring device. Specifically, in a nitrogen atmosphere, the dried charcoal and the reference substance were each heated by a heater and heated to 107 ° C. Thereafter, the nitrogen atmosphere was switched to air, and the calorific value when air oxidation was performed at a constant temperature (107 ° C.) was measured. The results are as shown in curve D2 of FIG.
  • the dried carbon (curve D2) of Comparative Example 5 has a lower calorific value than the dried carbon (E2) of Comparative Example 6. Also in FIG. 2, it is shown that dry charcoal (curve D1) is lower in self-ignitability than dry carbon (E1). From these tendencies, it can be said that, even when dry coal is subjected to oxidation treatment, it is possible to suppress spontaneous ignition as in dry-distilled coal. That is, the oxidation treatment is effective for dry coal as well as dry-distilled coal.
  • FIG. 4 also shows the result of Comparative Example 6 in order to facilitate the comparison.
  • the modified coals (curves A3 and A4) of Example 3 and Reference Example 4 were able to significantly reduce the calorific value compared to the dried carbon (curve E2) of Comparative Example 6.
  • the calorific value of the modified coals of Example 3 and Reference Example 4 was lower than the calorific value of the modified coals of Comparative Example 9 and Comparative Example 10. From this, it was confirmed that the modified coals of Example 3 and Reference Example 4 can reduce the self-heating property more than Comparative Examples 6, 9, 10.
  • Example 6 Modified coal was produced in the same manner as in Comparative Example 11 except that the oxidation treatment temperature in the oxidation treatment step was 240 ° C. The concentration of CO 2 and CO in the exhaust gas during the oxidation treatment step was analyzed in the same manner as in Comparative Example 11.
  • FIG. 5 is a graph in which the concentrations of CO 2 and CO in the exhaust gas determined in Examples 5 and 6 and Reference Example 7 and Comparative Examples 11 to 13 are plotted. As shown in FIG. 5, it was confirmed that when the oxidation treatment temperature exceeded 200 ° C., the generation amount of CO 2 and CO increased. From this, it can be said that the surface of the modified coal can be sufficiently reformed by setting the oxidation treatment temperature in a range exceeding 200 ° C.
  • FIG. 6 shows, on an enlarged scale, a portion at 2800 to 3000 cm -1 at which a peak derived from an aliphatic hydrocarbon group is observed in the measurement charts of infrared spectroscopic analysis of Comparative Example 14 and Comparative Example 15. Further, for comparison, FIG. 6 also shows the results of infrared spectroscopy of the dry-distilled carbon prepared in Comparative Example 6 (curve E2). As shown in FIG. 6, it was confirmed that the surface composition of dry-distilled carbon was changed by oxidizing dry-distilled carbon. In addition, it was confirmed that when the oxidation treatment temperature is changed within the temperature range of 200 to 300 ° C., the surface composition of the resulting modified coal changes significantly.
  • thermogravimetric / differential thermal analysis in the oxidation process (FIGS. 7 and 8)] (Comparative example 16)
  • the oxidation treatment process was performed using the dry-distilled carbon of Comparative Example 6.
  • the weight and differential heat at the time of the oxidation treatment step were measured using a commercially available thermogravimetric / differential thermal simultaneous analyzer. Specifically, dry-distilled coal was placed in an analyzer, and the temperature was raised to 140 ° C. at a rate of 10 ° C./minute in a nitrogen atmosphere. Thereafter, the atmosphere was switched to a mixed atmosphere of nitrogen and oxygen (oxygen concentration: 10% by volume) to start the oxidation treatment.
  • Thermogravimetric / differential thermal simultaneous analysis was performed based on this switching time.
  • the results of thermogravimetric analysis were as shown in curve B7 in FIG. 7, and the results of differential thermal analysis were as shown in curve B7 in FIG.
  • thermogravimetric / differential thermal simultaneous analysis was performed in the same manner as in Comparative Example 16 except that the oxidation treatment temperature (the temperature at which the mixed atmosphere was switched) in the oxidation treatment step was 220 ° C.
  • the results of thermogravimetric analysis were as shown in curve A5 in FIG. 7, and the results of differential thermal analysis were as shown in curve A5 in FIG.
  • Example 9 Thermal weight and differential thermal simultaneous analysis were performed in the same manner as in Comparative Example 16 except that the oxidation treatment temperature (the temperature at which the mixed atmosphere was switched) in the oxidation treatment step was 240 ° C.
  • the results of thermogravimetric analysis were as shown by curve A6 in FIG. 7, and the results of differential thermal analysis were as shown by curve A6 in FIG.
  • FIG. 9 is a graph showing the relationship between the height of the maximum peak (peak top) in the DTA analysis results (differential thermal analysis results) of each example and each comparative example shown in FIG. 8 and the oxidation treatment temperature.
  • the oxidation treatment temperature is 200 ° C. or lower (Comparative Examples 16, 17, 18)
  • the oxidation reaction does not progress so actively.
  • the oxidation treatment temperature exceeds 200 ° C., the oxidation reaction proceeds rapidly. Therefore, in order to advance the oxidation of the surface of the modified coal to a certain extent, it can be said that the oxidation treatment temperature needs to be in the range exceeding 200.degree.
  • the oxidation treatment of dry-distilled coal at 200 to 300 ° C. increased the oxygen concentration. That is, the oxidation treatment step has the function of oxidizing the functional group to increase the oxygen content. It is considered that the spontaneous firing property is suppressed by such an action.

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Abstract

Provided is a method for producing reformed coal, the method having a dry distillation step for dry-distilling coal at 300-650°C to obtain dry-distilled coal, and an oxidation treatment step in which the dry-distilled coal is subjected to oxidation treatment for 10-60 minutes in a temperature range from more than 200°C to no more than 240°C.

Description

改質炭の製造方法Method of producing modified coal
　本開示は、改質炭の製造方法に関する。 The present disclosure relates to a method of producing modified coal.
　褐炭又は亜瀝青炭等の低品位炭を改質するため、このような低品位炭を乾燥及び乾留させる技術が知られている。しかしながら、このような技術によって石炭を改質すると、表面が活性化され、空気中の酸素との反応熱で自然発火することが知られている。このような自然発火を防止する技術として、酸素を含有する処理ガスを用いて、石炭を４０～９５℃の温度範囲で不活性化処理する技術が提案されている（特許文献１参照）。 In order to reform low-grade coal such as lignite or sub-bituminous coal, techniques for drying and dry-distilling such low-grade coal are known. However, when coal is reformed by such a technique, it is known that the surface is activated and spontaneously ignited by the heat of reaction with oxygen in the air. As a technology for preventing such spontaneous ignition, a technology for deactivating coal in a temperature range of 40 to 95 ° C. using a processing gas containing oxygen has been proposed (see Patent Document 1).
特開２０１３－１３９５３７号公報JP, 2013-139537, A
　特許文献１に記載されているような従来の不活性化処理を行えば、乾留炭をある程度不活性化できるものと考えられる。しかしながら、本発明者らの検討によれば、このような従来の不活性化処理を行っても、自然発火性が十分に低減されないことが分かった。一方で、自然発火性を低減するために過剰に不活性化処理を行うと揮発成分が減少して、燃料として有効活用できなくなってしまう。そこで、本発明は、自然発火性が十分に抑制された改質炭を高い歩留まりで製造することが可能な改質炭の製造方法を提供することを目的とする。 It is considered that the dried carbon can be inactivated to some extent if the conventional inactivation treatment as described in Patent Document 1 is performed. However, according to the study of the present inventors, it was found that even if such conventional inactivation treatment was performed, the spontaneous firing property was not sufficiently reduced. On the other hand, if excessive inactivation treatment is performed to reduce the spontaneous ignition, the volatile components are reduced, and the fuel can not be effectively used. Then, an object of this invention is to provide the manufacturing method of the modification coal which can manufacture the modification coal in which the spontaneous ignition property was fully suppressed with high yield.
　本発明は、石炭を３００～６５０℃で乾留して乾留炭を得る乾留工程と、乾留炭を、２００℃を超え且つ２４０℃以下の温度範囲で１０～６０分間酸化処理する酸化処理工程と、を有する、改質炭の製造方法を提供する。 The present invention comprises a dry distillation step of dry-distilling coal at 300 to 650 ° C. to obtain dry-distilled carbon, and an oxidation treatment step of oxidizing dry-distilled carbon at a temperature range of over 200 ° C. and 240 ° C. or less for 10 to 60 minutes. Providing a method of producing modified coal.
　この製造方法は、原料炭の酸化処理を、２００℃を超え且つ２４０℃未満の温度範囲で１０～６０分間行う。このような条件で酸化処理を行うと、原料炭の表面成分が酸化されて表面状態が安定化されるため、自己発熱性が低減されて自然発火性が抑制されるものと考えられる。また、自己燃焼による消失が抑制され、歩留まりを高くすることができる。 In this production method, oxidation treatment of raw material carbon is performed at a temperature range of over 200 ° C. and less than 240 ° C. for 10 to 60 minutes. When the oxidation treatment is performed under such conditions, the surface component of the raw material carbon is oxidized to stabilize the surface state, and hence it is considered that the self-heating property is reduced and the spontaneous ignition property is suppressed. In addition, the loss due to self-combustion can be suppressed, and the yield can be increased.
　上記製造方法は、酸化処理工程の前に、石炭を乾留して乾留炭を得る乾留工程を有する。石炭の乾留は石炭を高品位化する手段として有効である。ここで、石炭の乾留を６５０℃以下で行うと、乾留時の歩留まりが高くなる一方で、自然発火性が高くなる傾向にある。上記製造方法では、酸化処理工程によって、自己発熱性を低減することができる。このため、乾留工程における乾留温度を６５０℃以下にしても自然発火性を抑制することができる。したがって、高品位で自然発火性が十分に抑制された改質炭を、高い歩留まりで製造することができる。 The above-mentioned manufacturing method has a dry distillation step of dry-distilling coal to obtain dry-distilled carbon prior to the oxidation treatment step. Dry distillation of coal is effective as a means of upgrading coal. Here, when the dry distillation of coal is carried out at 650 ° C. or less, the yield at the dry distillation tends to be high while the spontaneous ignition tends to be high. In the above manufacturing method, the self heating property can be reduced by the oxidation treatment step. For this reason, even if the dry distillation temperature in the dry distillation step is 650 ° C. or lower, the spontaneous ignition can be suppressed. Therefore, it is possible to produce a high grade, reformed coal with sufficiently suppressed spontaneous combustion property, with high yield.
　上記製造方法は、酸化処理工程の前に、１５０℃以下で石炭を乾燥する乾燥工程を有していてもよい。これによって石炭の水分が低減されるため、酸化処理工程、又は乾留工程及び酸化処理工程によって、一層高品位な改質炭を得ることができる。 The above manufacturing method may have a drying step of drying coal at 150 ° C. or less before the oxidation treatment step. Since the moisture of coal is reduced by this, a higher quality modified coal can be obtained by an oxidation treatment process or a dry distillation process and an oxidation treatment process.
　上記製造方法は、石炭の乾留によって発生する揮発成分を含むガスを燃焼炉で燃焼する燃焼工程を有していてもよい。この場合、酸化処理工程では、燃焼炉からの酸素を含む排ガスによって乾留炭を酸化処理することが好ましい。これによって、改質炭の製造コストを低減しつつ、酸化処理の効率性と安全性を向上することができる。 The above-mentioned production method may have a combustion step of burning a gas containing volatile components generated by dry distillation of coal in a combustion furnace. In this case, in the oxidation treatment step, it is preferable that the dry-distilled coal be oxidized by the exhaust gas containing oxygen from the combustion furnace. As a result, the efficiency and safety of the oxidation treatment can be improved while reducing the manufacturing cost of the modified coal.
　本発明は、自然発火性が十分に抑制された改質炭を高い歩留まりで製造することが可能な改質炭の製造方法を提供することができる。 The present invention can provide a method for producing a modified coal capable of producing a modified coal with sufficiently suppressed spontaneous ignition property with high yield.
図１は、改質炭の製造方法の一例を示すフローチャートである。FIG. 1 is a flowchart showing an example of a method for producing modified coal. 図２は、実施例１，２、参考例１，２及び比較例１～４の自然発火性評価試験の結果を示すグラフである。FIG. 2 is a graph showing the results of the spontaneous ignition evaluation test of Examples 1 and 2 and Reference Examples 1 and 2 and Comparative Examples 1 to 4. 図３は、乾留度が異なる比較例５～８の乾留炭の発熱量の経時変化を示すグラフである。FIG. 3 is a graph showing the time-dependent change of the calorific value of dry-distilled carbon of Comparative Examples 5 to 8 having different dry distillation degrees. 図４は、酸化処理温度が異なる実施例３、参考例４及び比較例９，１０の改質炭、並びに、比較例６の乾留炭の発熱量の経時変化を示すグラフである。FIG. 4 is a graph showing time-dependent changes in calorific value of the modified coals of Example 3 and Reference Example 4 and Comparative Examples 9 and 10 having different oxidation treatment temperatures and the dry-distilled carbon of Comparative Example 6. 図５は、実施例５，６、参考例７及び比較例１１～１３の酸化処理時における排ガス中の一酸化炭素及び二酸化炭素の濃度を示すグラフである。FIG. 5 is a graph showing the concentrations of carbon monoxide and carbon dioxide in the exhaust gas at the time of the oxidation treatment of Examples 5, 6 and Reference Example 7 and Comparative Examples 11-13. 図６は、比較例６、比較例１４及び比較例１５の赤外線分光分析の結果を示す図である。FIG. 6 is a diagram showing the results of infrared spectroscopic analysis of Comparative Example 6, Comparative Example 14 and Comparative Example 15. 図７は、酸化処理温度が異なる比較例１６～１９、及び実施例８，９、参考例１０の熱重量分析の結果を示すグラフである。FIG. 7 is a graph showing the results of thermogravimetric analysis of Comparative Examples 16 to 19 and Examples 8, 9 and Reference Example 10 in which the oxidation treatment temperature is different. 図８は、酸化処理温度が異なる比較例１６～１９、及び実施例８，９、参考例１０の示差熱分析の結果を示すグラフである。FIG. 8 is a graph showing the results of differential thermal analysis of Comparative Examples 16 to 19, and Examples 8 and 9, and Reference Example 10 having different oxidation treatment temperatures. 図９は、酸化処理温度が異なる比較例１６～１９、及び実施例８，９、参考例１０の示差熱分析結果における最大ピークの高さと、酸化処理温度との関係を示すグラフである。FIG. 9 is a graph showing the relationship between the height of the maximum peak and the oxidation treatment temperature in the results of differential thermal analysis of Comparative Examples 16 to 19, and Examples 8 and 9, and Reference Example 10 having different oxidation treatment temperatures. 図１０は、自然発火性評価試験の結果を示すグラフである。FIG. 10 is a graph showing the results of the spontaneous firing evaluation test.
　以下、場合により図面を参照して、本発明の実施形態について説明する。ただし、以下の実施形態は、本発明を説明するための例示であり、本発明を以下の内容に限定する趣旨ではない。 Hereinafter, embodiments of the present invention will be described with reference to the drawings as needed. However, the following embodiments are exemplifications for describing the present invention, and the present invention is not intended to be limited to the following contents.
　本実施形態の改質炭の製造方法は、石炭を３００～６５０℃で乾留して乾留炭を得る乾留工程と、乾留炭を２００℃を超え且つ２４０℃以下の温度範囲で酸化処理する酸化処理工程を有する。通常、乾留炭の方が石炭の乾燥炭よりも自然発火し易い傾向にある。本実施形態では、石炭及びその乾燥炭とは表面状態が異なる乾留炭に、所定の条件の酸化処理工程を行うことによって、乾留炭から、自然発火性が十分に抑制された改質炭を得ることができる。 The method for producing modified coal according to the present embodiment includes a dry distillation step of dry-distilling coal at 300 to 650 ° C. to obtain dry-distilled carbon, and an oxidation treatment of oxidizing dry-distilled carbon at a temperature range of 200 ° C. to 240 ° C. It has a process. In general, dry-distilled coal tends to ignite spontaneously more than dry coal in coal. In the present embodiment, by performing an oxidation treatment step under predetermined conditions on dry-distilled coal having a surface condition different from that of coal and its dry coal, reformed coal in which spontaneous ignition is sufficiently suppressed is obtained from dry-distilled carbon. be able to.
　乾留工程は、石炭を３００～６５０℃で乾留して、乾留炭を得る工程である。なお、後述の乾燥工程を行わずに乾留工程から行ってもよい。この場合、乾留工程の初期において石炭の水分が低減される。乾留工程は、好ましくは３００～６００℃の温度範囲において行う。これによって、石炭の乾留を十分に進行させつつ歩留まりを高く維持することができる。乾留工程は、竪型シャフト炉、コークス炉、又はトンネルキルン炉などの通常の乾留炉を用いて行うことができる。 The dry distillation step is a step of dry-distilling coal at 300 to 650 ° C. to obtain dry-distilled carbon. In addition, you may carry out from a dry distillation process, without performing the below-mentioned drying process. In this case, the water content of the coal is reduced at the beginning of the dry distillation process. The dry distillation step is preferably performed in a temperature range of 300 to 600.degree. This makes it possible to maintain a high yield while sufficiently promoting the carbonization of coal. The dry distillation step can be performed using a conventional dry distillation furnace such as a vertical shaft furnace, a coke oven, or a tunnel kiln furnace.
　乾留工程で得られる乾留炭の揮発分（ＶＭ）は、好ましくは１０～３０質量％である。このような乾留炭は、通常高い自然発火性を有するが、本実施形態では乾留工程の後に酸化処理工程を行って自然発火性を抑制することができる。したがって、高い歩留まりを実現することができる。 The volatile matter (VM) of the dry-distilled carbon obtained in the dry distillation step is preferably 10 to 30% by mass. Such dry-distilled carbon usually has high spontaneous ignition properties, but in the present embodiment, it is possible to suppress the spontaneous ignition properties by performing an oxidation treatment step after the dry distillation step. Therefore, high yield can be realized.
　石炭は、低品位炭を含んでいてもよいし、高品位炭を含んでいてもよい。低品位炭を含む場合、酸化処理工程の前に、後述する乾燥工程を行うことが好ましい。ただし、乾燥工程を行うことは必ずしも必須ではない。原料炭の粒径は、例えば５０ｍｍ以下であってもよく、３０ｍｍ以下であってもよく、１０ｍｍ以下であってもよい。 The coal may contain low grade coal or may contain high grade coal. When low grade coal is contained, it is preferable to perform the drying process mentioned later before an oxidation treatment process. However, it is not always essential to carry out the drying step. The particle size of the raw material carbon may be, for example, 50 mm or less, 30 mm or less, or 10 mm or less.
　酸化処理工程では、乾留炭の酸化処理を行う温度（酸化処理温度）を、２００℃を超える範囲にすることによって、乾留炭の表面を十分に改質して、自然発火性が十分に抑制された改質炭を得ることができる。酸化処理温度を、２４０℃以下にすることによって、酸化処理工程における揮発分の減少が抑制され、高い歩留まりで改質炭を製造することができる。 In the oxidation treatment step, by setting the temperature (oxidation treatment temperature) at which oxidation treatment of dry-distilled carbon is carried out in a range exceeding 200 ° C., the surface of dry-distilled carbon is sufficiently reformed to sufficiently suppress spontaneous ignition. Can be obtained. By setting the oxidation treatment temperature to 240 ° C. or less, the reduction of the volatile component in the oxidation treatment process is suppressed, and the modified coal can be produced with a high yield.
　酸化処理温度は、自然発火性の抑制と歩留まりの向上を一層高水準で両立する観点から、好ましくは２１０～２４０℃であり、より好ましくは２２０～２４０℃である。酸化処理工程は、一定の酸化処理温度で行わなくてもよく、上述の範囲内で酸化処理温度は変動してもよい。酸化処理工程の時間は、高い歩留まりで改質炭を製造する観点から、１０～６０分間である。自然発火性を十分に抑制する観点から、酸化処理工程の時間は、１５～６０分間としてもよい。 The oxidation treatment temperature is preferably 210 to 240 ° C., more preferably 220 to 240 ° C., from the viewpoint of achieving both suppression of spontaneous ignition and improvement of yield at a higher level. The oxidation treatment step may not be performed at a constant oxidation treatment temperature, and the oxidation treatment temperature may fluctuate within the above-mentioned range. The time of the oxidation treatment step is 10 to 60 minutes from the viewpoint of producing the modified coal with high yield. From the viewpoint of sufficiently suppressing the spontaneous ignition, the time of the oxidation treatment step may be 15 to 60 minutes.
　酸化処理工程の雰囲気は、酸素を含有する雰囲気であれば特に制限はなく、空気であってもよいし、窒素等の不活性ガスと酸素との混合雰囲気であってもよい。また、燃焼炉の排ガスであってもよい。酸素濃度は、安全性と酸化処理の効率性の観点から、例えば２～１３体積％であってもよく、３～１０体積％であってもよい。この「体積％」は、標準状態（２５℃、１００ｋＰａ）の条件における体積比率である。 The atmosphere in the oxidation treatment step is not particularly limited as long as it is an atmosphere containing oxygen, and may be air or a mixed atmosphere of an inert gas such as nitrogen and oxygen. Moreover, it may be the exhaust gas of a combustion furnace. The oxygen concentration may be, for example, 2 to 13% by volume or 3 to 10% by volume from the viewpoint of safety and the efficiency of the oxidation treatment. This "volume%" is a volume ratio in the conditions of a standard state (25 degreeC, 100 kPa).
　酸化処理工程では、原料炭の表面における官能基が酸化される。これによって、酸化による自己発熱性が低減され、自然発火性が十分に抑制された改質炭を製造することができる。改質炭の揮発分（ＶＭ）は、燃料としての有用性を高くする観点から、５質量％以上であってもよく、１０質量％以上であってもよい。一方、改質炭の揮発分（ＶＭ）は、自然発火性を一層低減する観点から、３０質量％以下であってもよく、２５質量％以下であってもよい。なお、本明細書における揮発分は、ＪＩＳ　Ｍ　８８１２：２００６の「角形電気炉法」に準拠して測定される無水ベースの値である。 In the oxidation treatment step, functional groups on the surface of the raw material carbon are oxidized. By this, the self-heating property by oxidation is reduced, and the reformed coal in which the spontaneous ignition property is sufficiently suppressed can be manufactured. The volatile content (VM) of the modified coal may be 5% by mass or more, or 10% by mass or more from the viewpoint of enhancing the usefulness as a fuel. On the other hand, the volatile content (VM) of the modified coal may be 30% by mass or less or 25% by mass or less from the viewpoint of further reducing the spontaneous ignition property. In addition, the volatile matter content in this specification is a value of the anhydrous basis measured based on the "square electric furnace method" of JISM 8812: 2006.
　本実施形態の製造方法によれば、自然発火性が十分に抑制された改質炭を高い歩留まりで製造することができる。このような改質炭は、ある程度の揮発分を含むことも可能であることから、燃料として有効活用することができる。このように燃料として有用性も高いうえにヤードにおける貯炭、及び、産炭地からの陸上・海上輸送等を安全に行なうことができる。 According to the manufacturing method of the present embodiment, it is possible to manufacture the modified coal in which the spontaneous combustion property is sufficiently suppressed at a high yield. Such reformed coal can also be used effectively as a fuel because it can contain a certain amount of volatile matter. As described above, it is highly useful as a fuel, and it is possible to safely carry out storage of coal in a yard, and on-shore / sea transportation from a coal-producing area.
　別の実施形態に係る改質炭の製造方法は、上述の乾留工程の前に、１５０℃以下で石炭を乾燥する乾燥工程を有する。水分含有量が多い低品位炭（例えば、水分が５０質量％以上である褐炭及び亜瀝青炭等）を用いる場合は、本実施形態のように乾燥工程を有することが好ましい。 The method for producing modified coal according to another embodiment includes a drying step of drying coal at 150 ° C. or less before the above-mentioned dry distillation step. In the case of using low-grade coal having a high water content (for example, lignite and sub-bituminous coal having a water content of 50% by mass or more), it is preferable to have a drying step as in this embodiment.
　乾燥工程では、石炭を、例えば４０～１５０℃の温度範囲に加熱して乾燥させる。乾燥工程は、空気中で行ってもよいし、不活性ガス雰囲気中で行ってもよい。また、燃焼炉の排ガス中で行ってもよい。乾燥工程では、石炭の水分量を例えば２０質量％以下に低減する。このような乾燥工程を行うことによって、乾留又は酸化処理による改質効果を十分に得ることができる。 In the drying step, the coal is dried by heating, for example, to a temperature range of 40 to 150.degree. The drying step may be performed in air or in an inert gas atmosphere. Alternatively, it may be performed in the exhaust gas of a combustion furnace. In the drying step, the water content of coal is reduced to, for example, 20% by mass or less. By performing such a drying step, the reforming effect by dry distillation or oxidation treatment can be sufficiently obtained.
　乾燥工程は、通常の電気炉等を用いて行ってもよいし、間接加熱器又は空気流動層乾燥器を用いて行ってもよい。乾燥工程の時間は特に制限はなく、石炭の水分量及び石炭の粒径等によって調整することができる。 The drying step may be performed using a common electric furnace or the like, or may be performed using an indirect heater or an air fluidized bed dryer. The time of the drying step is not particularly limited, and can be adjusted depending on the moisture content of coal, the particle size of coal, and the like.
　本実施形態の製造方法によれば、低品位炭を用いた場合であっても、自然発火性が十分に抑制された改質炭を高い歩留まりで製造することができる。改質炭の粒径は、例えば５０ｍｍ以下であってもよく、１０ｍｍ以下であってもよい。 According to the manufacturing method of the present embodiment, even when low-grade coal is used, it is possible to manufacture modified coal with sufficiently suppressed spontaneous ignition property with high yield. The particle size of the modified coal may be, for example, 50 mm or less, or 10 mm or less.
　上述の製造方法で得られた改質炭を分級して、粒状（例えば粒径３ｍｍ以上の粒）のものと、粉状（例えば粒径３ｍｍ未満の粉）ものとに分けてもよい。分級によって得られた粉状の改質炭（粉）はバインダーを用いて、またはバインダーを用いずに成型し、同じく分級によって得られた粒状の改質炭（粒）と混合してもよい。このようにして改質炭の平均粒径を大きくすれば、輸送及び貯炭時の粉塵発生が一層低減され、改質炭のハンドリング性をさらに向上することができる。 The modified coal obtained by the above-mentioned production method may be classified to be divided into particles (for example, particles with a particle diameter of 3 mm or more) and powders (for example, particles with a particle diameter of less than 3 mm). The powdery modified carbon (powder) obtained by classification may be molded with or without a binder, and may be mixed with the particulate modified carbon (particles) obtained by classification as well. By thus increasing the average particle size of the modified coal, the generation of dust during transportation and storage can be further reduced, and the handling of the modified coal can be further improved.
　図１は、一実施形態の改質炭の製造方法を行うための装置構成の一例を示す図である。図１の例では、乾燥装置１０において乾燥工程を、乾留装置２０では乾留工程を、酸化処理装置３０では酸化処理工程を行う。乾留装置２０から発生する揮発成分を含むガスは、燃焼炉４０にて燃料ガスとして消費される（燃焼工程）。乾燥装置１０としては例えば通常の乾燥器が挙げられる。酸化処理装置３０としては例えば通常の電気炉が挙げられる。 FIG. 1 is a view showing an example of an apparatus configuration for performing a method of manufacturing modified coal according to an embodiment. In the example of FIG. 1, the drying process is performed in the drying apparatus 10, the dry distillation process is performed in the dry distillation apparatus 20, and the oxidation treatment process is performed in the oxidation treatment apparatus 30. The gas containing volatile components generated from the dry distillation apparatus 20 is consumed as a fuel gas in the combustion furnace 40 (combustion process). The drying device 10 may be, for example, a conventional dryer. Examples of the oxidation treatment apparatus 30 include a conventional electric furnace.
　燃焼炉４０において揮発成分を含む燃料ガスを燃焼して発生した排ガスは、通常５～１０体積％程度の酸素を含む。このような排ガスを酸化処理装置３０で利用することによって、酸化処理工程における酸化処理の効率性と安全性を十分に高くすることができる。また、排ガスの温度を有効に活用できるため、エネルギーの削減も図ることができる。燃焼炉４０において発生した排ガスは、乾燥装置１０において加熱用のガスとして用いてもよい。このように乾留工程で生じる熱を有効利用することによって、改質炭の製造コストを低減することができる。 The exhaust gas generated by burning the fuel gas containing the volatile component in the combustion furnace 40 usually contains about 5 to 10% by volume of oxygen. By using such exhaust gas in the oxidation treatment device 30, the efficiency and safety of the oxidation treatment in the oxidation treatment step can be sufficiently enhanced. In addition, since the temperature of the exhaust gas can be effectively used, energy can be reduced. The exhaust gas generated in the combustion furnace 40 may be used as a heating gas in the drying apparatus 10. By effectively utilizing the heat generated in the dry distillation step as described above, the manufacturing cost of the modified coal can be reduced.
　以上、本発明の幾つかの実施形態について説明したが、本発明は上記実施形態に何ら限定されるものではない。 As mentioned above, although some embodiment of this invention was described, this invention is not limited at all to the said embodiment.
　実施例及び比較例を参照して本発明の内容をより詳細に説明するが、本発明は下記の実施例に限定されるものではない。 Although the contents of the present invention will be described in more detail with reference to Examples and Comparative Examples, the present invention is not limited to the following Examples.
（実施例１）
［改質炭の製造］
　市販のボイラ用の石炭である亜瀝青炭（インドネシア産のアダロ炭）を、乾燥器を用いて空気中で乾燥して乾燥炭を得た（乾燥工程）。乾燥工程における加熱温度は１５０℃、加熱時間は３０分間とした。得られた乾燥炭の揮発分（ＶＭ）は５０質量％であり、水分量は１０質量％以下であった。得られた乾燥炭を、乾留炉を用いて乾留して乾留炭を得た（乾留工程）。乾留工程における加熱温度は４３０℃、加熱時間は４０分間とした。乾留炭の揮発分（ＶＭ）は２５質量％であった。 Example 1
[Manufacturing of modified coal]
Commercially available coal for boilers, sub-bituminous coal (Adaro coal from Indonesia), was dried in the air using a drier to obtain dried coal (drying step). The heating temperature in the drying step was 150 ° C., and the heating time was 30 minutes. The volatile matter (VM) of the obtained dried coal was 50% by mass, and the water content was 10% by mass or less. The obtained dried coal was subjected to dry distillation using a dry distillation furnace to obtain dry distilled carbon (dry distillation step). The heating temperature in the dry distillation step was 430 ° C., and the heating time was 40 minutes. The volatile matter (VM) of dry-distilled carbon was 25% by mass.
　続いて、電気炉を用いて得られた乾留炭の酸化処理を行って粒状の改質炭（粒径：約１～３ｍｍ）を製造した（酸化処理工程）。酸化処理の条件は、窒素ガスと酸素ガスの混合ガス雰囲気中（酸素濃度：８体積％）、加熱温度２４０℃、加熱時間４０分間とした。 Subsequently, the dry-distilled carbon obtained was oxidized using an electric furnace to produce granular modified carbon (particle size: about 1 to 3 mm) (oxidation treatment step). The conditions for the oxidation treatment were a mixed gas atmosphere of nitrogen gas and oxygen gas (oxygen concentration: 8% by volume), a heating temperature of 240 ° C., and a heating time of 40 minutes.
［自然発火性の評価（図２）］
　国際連合危険物輸送勧告試験［クラス４、区分４．２（自然発火性物質・自己発熱性物質）］に準じた手法によって、得られた改質炭の自然発火性評価試験を行った。具体的には、金網で形成された、一辺が１０ｃｍの立方体形状を有する容器の中に改質炭を入れ、１４０℃の空気中に保管して発熱温度の経時変化を調べた。結果は、図２の曲線Ａ１（改質炭）に示すとおりであった。 [Evaluation of spontaneous ignition (Fig. 2)]
The pyrophoricity evaluation test of the obtained modified coal was conducted by the method according to the United Nations Recommendations on the Transport of Hazardous Substances [Class 4, Category 4.2 (pyrophoric substances / self-heating substances)]. Specifically, the modified carbon was placed in a container having a cubic shape with a side of 10 cm, which was formed of a wire mesh, and stored in air at 140 ° C., and the heat generation temperature change was examined. The results are as shown in the curve A1 (modified coal) of FIG.
（実施例２）
　酸化処理工程における加熱温度を２１０℃にしたこと以外は、実施例１と同様にして改質炭を製造した。そして、実施例１と同様にして自然発火性評価試験を行った。結果は、図２の曲線Ａ２に示すとおりであった。 (Example 2)
Modified coal was produced in the same manner as in Example 1 except that the heating temperature in the oxidation treatment step was 210 ° C. Then, in the same manner as in Example 1, a spontaneous ignition evaluation test was conducted. The results were as shown in curve A2 of FIG.
（参考例１）
　実施例１で用いた亜瀝青炭（インドネシア産のアダロ炭）の自然発火性評価試験を実施例１と同様にして行った。結果は、図２の曲線Ｃ１に示すとおりであった。 (Reference Example 1)
The spontaneous ignition evaluation test of the sub bituminous coal (Adaro coal from Indonesia) used in Example 1 was conducted in the same manner as in Example 1. The results were as shown in curve C1 of FIG.
（参考例２）
　市販のボイラ用の石炭である瀝青炭（オーストラリア産のマウントアーサ炭）の自然発火性評価試験を実施例１と同様にして行った。結果は、図２の曲線Ｃ２に示すとおりであった。 (Reference Example 2)
The pyrophoricity evaluation test of bituminous coal (mount isa charcoal of Australian origin) which is coal for commercial boilers was conducted in the same manner as in Example 1. The results are as shown in curve C2 of FIG.
（比較例１）
　酸化処理工程を行わなかったこと以外は、実施例１と同様とした。すなわち、乾留工程で得られた乾留炭の自然発火性評価試験を行った。結果は、図２の曲線Ｅ１に示すとおりであった。 (Comparative example 1)
The process was the same as Example 1 except that the oxidation treatment step was not performed. That is, the pyrophoricity evaluation test of the dry-distilled carbon obtained in the dry distillation process was conducted. The results were as shown in curve E1 of FIG.
（比較例２）
　酸化処理工程における加熱温度を２００℃にしたこと以外は、実施例１と同様にして改質炭を製造した。そして、実施例１と同様にして自然発火性評価試験を行った。結果は、図２の曲線Ｂ１に示すとおりであった。 (Comparative example 2)
Modified coal was manufactured in the same manner as in Example 1 except that the heating temperature in the oxidation treatment step was set to 200 ° C. Then, in the same manner as in Example 1, a spontaneous ignition evaluation test was conducted. The results were as shown in curve B1 of FIG.
（比較例３）
　酸化処理工程における加熱温度を２９０℃にしたこと以外は、実施例１と同様にして改質炭を製造した。そして、実施例１と同様にして自然発火性評価試験を行った。結果は、図２の曲線Ｂ２に示すとおりであった。 (Comparative example 3)
Modified coal was produced in the same manner as in Example 1 except that the heating temperature in the oxidation treatment step was set to 290 ° C. Then, in the same manner as in Example 1, a spontaneous ignition evaluation test was conducted. The results are as shown in curve B2 of FIG.
（比較例４）
　実施例１と同様にして乾燥炭を得た。乾燥炭の揮発分（ＶＭ）は５０質量％、水分量は１０質量％以下であった。得られた乾燥炭の自然発火性評価試験を行った。結果は、図２の曲線Ｄ１に示すとおりであった。 (Comparative example 4)
Dry carbon was obtained in the same manner as Example 1. The volatile matter (VM) of the dried charcoal was 50% by mass, and the water content was 10% by mass or less. The pyrophoricity evaluation test of the obtained dried coal was conducted. The results were as shown in curve D1 of FIG.
　図２に示すとおり、酸化処理工程を行っていない比較例１の乾留炭（曲線Ｅ１）は、約1時間で２５０℃以上に発熱した。すなわち、改質炭は自然発火性が最も高かった。一方、比較例４の乾燥炭（曲線Ｄ１）は、比較例１の乾留炭（曲線Ｅ１）よりも自然発火性が低かった。 As shown in FIG. 2, the dry-distilled carbon (curve E1) of Comparative Example 1 in which the oxidation treatment step was not performed generated heat to 250 ° C. or more in about one hour. That is, the modified coal was the highest in spontaneous ignition. On the other hand, the dry charcoal (curve D1) of Comparative Example 4 was lower in pyrophoric property than the dry-distilled charcoal (curve E1) of Comparative Example 1.
　２００℃及び２９０℃の温度で酸化処理をそれぞれ行った比較例２の改質炭（曲線Ｂ１）及び比較例３の改質炭（曲線Ｂ２）は、比較例１よりも自然発火性が低くなっていた。そして、２１０℃及び２４０℃の温度で酸化処理をそれぞれ行った実施例２の改質炭（曲線Ａ２）及び実施例１の改質炭（曲線Ａ１）は、比較例２及び比較例３よりも自然発火性がさらに低くなっていた。 The modified coal (curve B1) of Comparative Example 2 and the modified coal (curve B2) of Comparative Example 3 in which the oxidation treatment was performed at temperatures of 200 ° C. and 290 ° C., respectively, have lower spontaneous ignition than in Comparative Example 1. It was Then, the modified coal (curve A2) of Example 2 and the modified coal (curve A1) of Example 1 in which the oxidation treatment was performed at temperatures of 210 ° C. and 240 ° C., respectively, were higher than those of Comparative Example 2 and Comparative Example 3. Spontaneous ignition was even lower.
　実施例２の改質炭の自然発火性は市販の亜瀝青炭よりも低く、実施例１の改質炭の自然発火性は市販の瀝青炭よりも低かった。このように、実施例１及び実施例２の改質炭の自然発火性は、乾留されているにもかかわらず十分に抑制されていることが確認された。 The spontaneous ignition property of the modified coal of Example 2 was lower than that of the commercially available subbituminous coal, and the spontaneous ignition property of the modified coal of Example 1 was lower than that of the commercially available bituminous coal. Thus, it was confirmed that the pyrophoric properties of the modified coals of Example 1 and Example 2 were sufficiently suppressed despite being carbonized.
［乾留度による発熱量への影響（図３）］
（比較例５）
　市販のボイラ用の石炭である亜瀝青炭（インドネシア産のアダロ炭）を、乾燥器を用いて空気中で乾燥して粒状の乾燥炭（粒径：０．５ｍｍ以下）を得た（乾燥工程）。乾燥工程における加熱温度は１５０℃、加熱時間は３０分間とした。乾燥炭の揮発分（ＶＭ）は５０質量％、水分量は１０質量％以下であった。 [Influence of calorific value on calorific value (Fig. 3)]
(Comparative example 5)
Commercially available coal for boilers, sub-bituminous coal (Adaro coal from Indonesia), was dried in the air using a drier to obtain granular dry coal (particle size: 0.5 mm or less) (drying step) . The heating temperature in the drying step was 150 ° C., and the heating time was 30 minutes. The volatile matter (VM) of the dried charcoal was 50% by mass, and the water content was 10% by mass or less.
　市販の測定装置を用いて、調製した乾燥炭の示差走査熱量測定（ＤＳＣ測定）を行った。具体的には、窒素雰囲気中、乾燥炭と基準物質をそれぞれヒーターで加熱し１０７℃に昇温した。その後、窒素雰囲気から空気に切り替えて、一定の温度（１０７℃）下において空気酸化を行った時の発熱量を測定した。結果は、図３の曲線Ｄ２に示すとおりであった。 Differential scanning calorimetry (DSC measurement) of the prepared dried charcoal was performed using a commercially available measuring device. Specifically, in a nitrogen atmosphere, the dried charcoal and the reference substance were each heated by a heater and heated to 107 ° C. Thereafter, the nitrogen atmosphere was switched to air, and the calorific value when air oxidation was performed at a constant temperature (107 ° C.) was measured. The results are as shown in curve D2 of FIG.
（比較例６）
　比較例５の乾燥炭を用いて乾留工程を行い、乾留炭を調製した。乾留工程における加熱温度は４３０℃、加熱時間は４０分間とした。乾留炭の揮発分（ＶＭ）は２５質量％であった。この乾留炭のＤＳＣ測定を比較例５と同様にして行った。結果は、図３の曲線Ｅ２に示すとおりであった。 (Comparative example 6)
A dry distillation step was carried out using the dried charcoal of Comparative Example 5 to prepare dry distilled charcoal. The heating temperature in the dry distillation step was 430 ° C., and the heating time was 40 minutes. The volatile matter (VM) of dry-distilled carbon was 25% by mass. The DSC measurement of this dry-distilled coal was performed in the same manner as in Comparative Example 5. The results are as shown in curve E2 of FIG.
（比較例７）
　乾留工程における加熱温度を５５０℃としたこと以外は、比較例６と同様にして乾留炭を調製した。乾留炭の揮発分（ＶＭ）は１２質量％であった。この乾留炭のＤＳＣ測定を比較例５と同様にして行った。結果は、図３の曲線Ｅ３に示すとおりであった。 (Comparative example 7)
Dry-distilled carbon was prepared in the same manner as in Comparative Example 6 except that the heating temperature in the dry distillation step was 550 ° C. The volatile matter (VM) of dry-distilled carbon was 12% by mass. The DSC measurement of this dry-distilled coal was performed in the same manner as in Comparative Example 5. The results are as shown in curve E3 of FIG.
（比較例８）
　乾留工程における加熱温度を１０００℃としたこと以外は、比較例６と同様にして乾留炭を調製した。乾留炭の揮発分（ＶＭ）は０質量％であった。この乾留炭のＤＳＣ測定を比較例５と同様にして行った。結果は、図３の曲線Ｅ４に示すとおりであった。 (Comparative example 8)
Dry-distilled carbon was prepared in the same manner as in Comparative Example 6 except that the heating temperature in the dry distillation step was set to 1000 ° C. The volatile matter (VM) of dry-distilled carbon was 0% by mass. The DSC measurement of this dry-distilled coal was performed in the same manner as in Comparative Example 5. The results are as shown in curve E4 of FIG.
　比較例６～８の結果から、乾留温度（乾留度）が低い方が、乾留炭に残存する揮発分が多くなるため歩留まりが高かった。しかしながら、図３に示されるように、乾留温度を低くすると酸化による発熱量が大きくなることが確認された。これは、乾留温度が低くなると揮発分の残存量が多くなり、その結果、乾留炭の表面において活性の高いラジカルの生成量が増えることによるものと考えられる。乾留温度が４３０℃である比較例６の乾留炭の発熱量（曲線Ｅ２）は、比較例５の乾燥炭の発熱量（曲線Ｄ２）よりも大幅に高かった。この結果から、乾留炭の歩留まりと自己発熱性は互いにトレードオフの関係にあり、乾留炭のままでは高い歩留まりと自然発火性の抑制とを両立することは困難であることが確認された。 From the results of Comparative Examples 6 to 8, as the dry distillation temperature (degree of dry distillation) is lower, the amount of volatile matter remaining in dry dry carbon increases, so the yield is high. However, as shown in FIG. 3, it was confirmed that the calorific value due to oxidation is increased when the distillation temperature is lowered. This is considered to be due to the fact that the residual amount of volatile matter increases as the dry distillation temperature decreases, and as a result, the amount of highly active radicals generated on the surface of the dry-distilled carbon increases. The calorific value (curve E2) of the dry-distilled carbon of Comparative Example 6 having a dry-distillation temperature of 430 ° C. was significantly higher than the calorific value (curve D2) of the dry carbon of Comparative Example 5. From these results, it was confirmed that the yield of dry-distilled coal and the self-heating property are in a trade-off relationship with each other, and it is difficult to achieve both high yield and suppression of spontaneous ignition property with dry-distilled carbon as it is.
　図３に示されるように、比較例５の乾燥炭（曲線Ｄ２）は、比較例６の乾留炭（Ｅ２）よりも発熱量が低かった。図２においても、乾燥炭（曲線Ｄ１）の方が乾留炭（Ｅ１）よりも自己発火性が低いことが示されている。これらの傾向から、乾燥炭に対して酸化処理を行った場合も、乾留炭と同様に自然発火性を抑制できるといえる。すなわち、乾燥炭に対しても、乾留炭と同様に酸化処理は有効である。 As shown in FIG. 3, the dried carbon (curve D2) of Comparative Example 5 has a lower calorific value than the dried carbon (E2) of Comparative Example 6. Also in FIG. 2, it is shown that dry charcoal (curve D1) is lower in self-ignitability than dry carbon (E1). From these tendencies, it can be said that, even when dry coal is subjected to oxidation treatment, it is possible to suppress spontaneous ignition as in dry-distilled coal. That is, the oxidation treatment is effective for dry coal as well as dry-distilled coal.
［酸化処理温度の影響（図４）］
（実施例３）
　比較例６の乾留炭を用いて酸化処理工程を行い、改質炭を製造した。酸化処理の条件は、窒素ガスと酸素ガスの混合ガス雰囲気中（酸素濃度：１０体積％）、加熱温度２４０℃、加熱時間４０分間とした。製造した改質炭のＤＳＣ測定を比較例５と同様にして行った。結果は、図４の曲線Ａ３に示すとおりであった。 [Influence of oxidation treatment temperature (Figure 4)]
(Example 3)
An oxidation treatment step was performed using the dry-distilled carbon of Comparative Example 6, to produce a modified coal. The conditions for the oxidation treatment were a mixed gas atmosphere of nitrogen gas and oxygen gas (oxygen concentration: 10% by volume), a heating temperature of 240 ° C., and a heating time of 40 minutes. DSC measurement of the produced modified coal was performed in the same manner as Comparative Example 5. The results were as shown in curve A3 of FIG.
（参考例４）
　比較例６の乾留炭を用いて酸化処理工程を行い、改質炭を製造した。酸化処理の条件は、窒素ガスと酸素ガスの混合ガス雰囲気中（酸素濃度：１０体積％）、加熱温度２６０℃、加熱時間４０分間とした。製造した改質炭のＤＳＣ測定を比較例５と同様にして行った。結果は、図４の曲線Ａ４に示すとおりであった。 (Reference Example 4)
An oxidation treatment step was performed using the dry-distilled carbon of Comparative Example 6, to produce a modified coal. The conditions for the oxidation treatment were a mixed gas atmosphere of nitrogen gas and oxygen gas (oxygen concentration: 10% by volume), a heating temperature of 260 ° C., and a heating time of 40 minutes. DSC measurement of the produced modified coal was performed in the same manner as Comparative Example 5. The results were as shown in curve A4 of FIG.
（比較例９）
　比較例６の乾留炭を用いて酸化処理工程を行い、改質炭を製造した。酸化処理の条件は、窒素ガスと酸素ガスの混合ガス雰囲気中（酸素濃度：１０体積％）、加熱温度２００℃、加熱時間４０分間とした。製造した改質炭のＤＳＣ測定を比較例５と同様にして行った。結果は、図４の曲線Ｂ３に示すとおりであった。 (Comparative example 9)
An oxidation treatment step was performed using the dry-distilled carbon of Comparative Example 6, to produce a modified coal. The conditions for the oxidation treatment were a mixed gas atmosphere of nitrogen gas and oxygen gas (oxygen concentration: 10% by volume), a heating temperature of 200 ° C., and a heating time of 40 minutes. DSC measurement of the produced modified coal was performed in the same manner as Comparative Example 5. The results are as shown in curve B3 of FIG.
（比較例１０）
　比較例６の乾留炭を用いて酸化処理工程を行い、改質炭を製造した。酸化処理の条件は、窒素ガスと酸素ガスの混合ガス雰囲気中（酸素濃度：１０体積％）、加熱温度３００℃、加熱時間４０分間とした。製造した改質炭のＤＳＣ測定を比較例５と同様にして行った。結果は、図４の曲線Ｂ４に示すとおりであった。 (Comparative example 10)
An oxidation treatment step was performed using the dry-distilled carbon of Comparative Example 6, to produce a modified coal. The conditions for the oxidation treatment were a mixed gas atmosphere of nitrogen gas and oxygen gas (oxygen concentration: 10% by volume), a heating temperature of 300 ° C., and a heating time of 40 minutes. DSC measurement of the produced modified coal was performed in the same manner as Comparative Example 5. The results were as shown in curve B4 of FIG.
　図４には、比較を容易にするため、比較例６の結果も併せて示した。実施例３及び参考例４の改質炭（曲線Ａ３及びＡ４）は、比較例６の乾留炭（曲線Ｅ２）に比べて発熱量を大幅に低減することができた。実施例３及び参考例４の改質炭の発熱量は、比較例９及び比較例１０の改質炭の発熱量よりも低かった。このことから、実施例３及び参考例４の改質炭は、比較例６，９，１０よりも、自己発熱性を低減できることが確認された。 FIG. 4 also shows the result of Comparative Example 6 in order to facilitate the comparison. The modified coals (curves A3 and A4) of Example 3 and Reference Example 4 were able to significantly reduce the calorific value compared to the dried carbon (curve E2) of Comparative Example 6. The calorific value of the modified coals of Example 3 and Reference Example 4 was lower than the calorific value of the modified coals of Comparative Example 9 and Comparative Example 10. From this, it was confirmed that the modified coals of Example 3 and Reference Example 4 can reduce the self-heating property more than Comparative Examples 6, 9, 10.
［酸化処理温度によるガス発生量の変化（図５）］
（比較例１１）
　比較例６の乾留炭を、電気炉を用いて、窒素ガス雰囲気中、１４０℃に昇温した。昇温後、酸化処理工程を行って改質炭を製造した。酸化処理条件は、窒素ガスと酸素ガスの混合ガス雰囲気中（酸素濃度：１０体積％）、酸化処理温度１４０℃、酸化処理時間２０分間とした。酸化処理工程時の排ガスを全てサンプリングして平均化し、平均化したガス中のＣＯ２及びＣＯの濃度を、ガスクロマトグラフ法を用いて測定した。 [Change of gas generation amount by oxidation treatment temperature (Fig. 5)]
(Comparative example 11)
The dry-distilled coal of Comparative Example 6 was heated to 140 ° C. in a nitrogen gas atmosphere using an electric furnace. After the temperature rise, an oxidation treatment step was carried out to produce modified coal. The oxidation treatment conditions were a mixed gas atmosphere of nitrogen gas and oxygen gas (oxygen concentration: 10% by volume), an oxidation treatment temperature of 140 ° C., and an oxidation treatment time of 20 minutes. All exhaust gases from the oxidation treatment step were sampled and averaged, and the concentration of CO 2 and CO in the averaged gas was measured using a gas chromatography method.
（比較例１２）
　酸化処理工程における酸化処理温度を２００℃にしたこと以外は、比較例１１と同様にして改質炭を製造した。比較例１１と同様にして酸化処理工程時の排ガス中のＣＯ２及びＣＯの濃度を分析した。 (Comparative example 12)
Modified coal was produced in the same manner as in Comparative Example 11 except that the oxidation treatment temperature in the oxidation treatment step was set to 200 ° C. The concentration of CO 2 and CO in the exhaust gas during the oxidation treatment step was analyzed in the same manner as in Comparative Example 11.
（実施例５）
　酸化処理工程における酸化処理温度を２２０℃にしたこと以外は、比較例１１と同様にして改質炭を製造した。比較例１１と同様にして酸化処理工程時の排ガス中のＣＯ２及びＣＯの濃度を分析した。 (Example 5)
Modified coal was produced in the same manner as in Comparative Example 11 except that the oxidation treatment temperature in the oxidation treatment step was set to 220 ° C. The concentration of CO 2 and CO in the exhaust gas during the oxidation treatment step was analyzed in the same manner as in Comparative Example 11.
（実施例６）
　酸化処理工程における酸化処理温度を２４０℃にしたこと以外は、比較例１１と同様にして改質炭を製造した。比較例１１と同様にして酸化処理工程時の排ガス中のＣＯ２及びＣＯの濃度を分析した。 (Example 6)
Modified coal was produced in the same manner as in Comparative Example 11 except that the oxidation treatment temperature in the oxidation treatment step was 240 ° C. The concentration of CO 2 and CO in the exhaust gas during the oxidation treatment step was analyzed in the same manner as in Comparative Example 11.
（参考例７）
　酸化処理工程における酸化処理温度を２６０℃にしたこと以外は、比較例１１と同様にして改質炭を製造した。比較例１１と同様にして酸化処理工程時の排ガス中のＣＯ２及びＣＯの濃度を分析した。 (Reference Example 7)
Modified coal was produced in the same manner as in Comparative Example 11 except that the oxidation treatment temperature in the oxidation treatment step was 260 ° C. The concentration of CO 2 and CO in the exhaust gas during the oxidation treatment step was analyzed in the same manner as in Comparative Example 11.
（比較例１３）
　酸化処理工程における酸化処理温度を３００℃にしたこと以外は、比較例１１と同様にして改質炭を製造した。比較例１１と同様にして酸化処理工程時の排ガス中のＣＯ２及びＣＯの濃度を分析した。 (Comparative example 13)
Modified coal was produced in the same manner as in Comparative Example 11 except that the oxidation treatment temperature in the oxidation treatment step was set to 300 ° C. The concentration of CO 2 and CO in the exhaust gas during the oxidation treatment step was analyzed in the same manner as in Comparative Example 11.
　図５は、実施例５，６、参考例７及び比較例１１～１３において求めた排ガス中のＣＯ２及びＣＯの濃度をプロットしたグラフである。図５に示されるように、酸化処理温度が２００℃を超えるとＣＯ２及びＣＯの発生量が増加することが確認された。このことから、酸化処理温度を、２００℃を超える範囲内にすることによって改質炭の表面を十分に改質することができるといえる。 FIG. 5 is a graph in which the concentrations of CO 2 and CO in the exhaust gas determined in Examples 5 and 6 and Reference Example 7 and Comparative Examples 11 to 13 are plotted. As shown in FIG. 5, it was confirmed that when the oxidation treatment temperature exceeded 200 ° C., the generation amount of CO 2 and CO increased. From this, it can be said that the surface of the modified coal can be sufficiently reformed by setting the oxidation treatment temperature in a range exceeding 200 ° C.
［乾留炭及び改質炭の表面状態の分析（図６）］
（比較例１４）
　酸化処理工程における混合ガス雰囲気の酸素濃度を８体積％にしたこと以外は、比較例１２と同様にして改質炭（酸化処理温度：２００℃）を製造した。市販の赤外線分光分析計を用いて、製造した改質炭の赤外線分光分析（ＩＲ分析）を行った。分析結果は、図６の曲線Ｂ５に示すとおりであった。 [Analysis of surface condition of dry-distilled coal and modified coal (Fig. 6)]
(Comparative example 14)
Modified coal (oxidation treatment temperature: 200 ° C.) was produced in the same manner as in Comparative Example 12 except that the oxygen concentration in the mixed gas atmosphere in the oxidation treatment step was changed to 8% by volume. Infrared spectroscopy (IR analysis) of the produced modified coal was performed using a commercially available infrared spectrometer. The analysis results were as shown in curve B5 of FIG.
（比較例１５）
　酸化処理工程における混合ガス雰囲気の酸素濃度を８体積％にしたこと以外は、比較例１３と同様にして改質炭（酸化処理温度：３００℃）を製造した。そして、比較例１４と同様にして製造した改質炭の赤外線分光分析を行った。分析結果は、図６の曲線Ｂ６に示すとおりであった。 (Comparative example 15)
Modified coal (oxidation treatment temperature: 300 ° C.) was produced in the same manner as in Comparative Example 13 except that the oxygen concentration in the mixed gas atmosphere in the oxidation treatment step was changed to 8% by volume. Then, infrared spectroscopy analysis of the modified coal produced in the same manner as Comparative Example 14 was performed. The analysis results were as shown in curve B6 of FIG.
　図６には、比較例１４及び比較例１５の赤外線分光分析の測定チャートのうち、脂肪族炭化水素基に由来するピークが観測される２８００～３０００ｃｍ－１の部分を拡大して示した。また、比較のため、図６には、比較例６で調製した乾留炭の赤外線分光分析の結果も併せて示した（曲線Ｅ２）。図６に示されるように、乾留炭を酸化処理することによって、乾留炭の表面組成が変化することが確認された。また、酸化処理温度を２００～３００℃の温度範囲内で変更すると、得られる改質炭の表面組成が大きく変化することが確認された。 FIG. 6 shows, on an enlarged scale, a portion at 2800 to 3000 cm -1 at which a peak derived from an aliphatic hydrocarbon group is observed in the measurement charts of infrared spectroscopic analysis of Comparative Example 14 and Comparative Example 15. Further, for comparison, FIG. 6 also shows the results of infrared spectroscopy of the dry-distilled carbon prepared in Comparative Example 6 (curve E2). As shown in FIG. 6, it was confirmed that the surface composition of dry-distilled carbon was changed by oxidizing dry-distilled carbon. In addition, it was confirmed that when the oxidation treatment temperature is changed within the temperature range of 200 to 300 ° C., the surface composition of the resulting modified coal changes significantly.
［酸化処理工程における熱重量・示差熱分析（図７及び図８）］
（比較例１６）
　比較例６の乾留炭を用いて酸化処理工程を行った。市販の熱重量・示差熱同時分析装置を用いて、酸化処理工程時における重量及び示差熱を測定した。具体的には、乾留炭を分析装置の中に設置して、窒素雰囲気中、１４０℃まで１０℃／分の速度で昇温した。その後、雰囲気を窒素と酸素の混合雰囲気（酸素濃度：１０体積％）に切り替えて、酸化処理を開始した。この切り替え時を基準として、熱重量・示差熱同時分析を行った。熱重量分析の結果は図７の曲線Ｂ７に、示差熱分析の結果は図８の曲線Ｂ７に示すとおりであった。 [Thermogravimetric / differential thermal analysis in the oxidation process (FIGS. 7 and 8)]
(Comparative example 16)
The oxidation treatment process was performed using the dry-distilled carbon of Comparative Example 6. The weight and differential heat at the time of the oxidation treatment step were measured using a commercially available thermogravimetric / differential thermal simultaneous analyzer. Specifically, dry-distilled coal was placed in an analyzer, and the temperature was raised to 140 ° C. at a rate of 10 ° C./minute in a nitrogen atmosphere. Thereafter, the atmosphere was switched to a mixed atmosphere of nitrogen and oxygen (oxygen concentration: 10% by volume) to start the oxidation treatment. Thermogravimetric / differential thermal simultaneous analysis was performed based on this switching time. The results of thermogravimetric analysis were as shown in curve B7 in FIG. 7, and the results of differential thermal analysis were as shown in curve B7 in FIG.
（比較例１７）
　酸化処理工程における酸化処理温度（混合雰囲気への切り替え温度）を１８０℃にしたこと以外は、比較例１６と同様にして熱重量・示差熱同時分析を行った。熱重量分析の結果は図７の曲線Ｂ８に、示差熱分析の結果は図８の曲線Ｂ８に示すとおりであった。 (Comparative example 17)
Simultaneous thermal weight and differential thermal analysis were performed in the same manner as in Comparative Example 16 except that the oxidation treatment temperature (the temperature at which the mixed atmosphere was switched) in the oxidation treatment step was set to 180 ° C. The results of thermogravimetric analysis were as shown by curve B8 in FIG. 7, and the results of differential thermal analysis were as shown by curve B8 in FIG.
（比較例１８）
　酸化処理工程における酸化処理温度（混合雰囲気への切り替え温度）を２００℃にしたこと以外は、比較例１６と同様にして熱重量・示差熱同時分析を行った。熱重量分析の結果は図７の曲線Ｂ９に、示差熱分析の結果は図８の曲線Ｂ９に示すとおりであった。 (Comparative example 18)
Simultaneous thermal weight and differential thermal analysis were performed in the same manner as in Comparative Example 16 except that the oxidation treatment temperature (the switching temperature to the mixed atmosphere) in the oxidation treatment step was set to 200 ° C. The results of thermogravimetric analysis were as shown by curve B9 in FIG. 7, and the results of differential thermal analysis were as shown by curve B9 in FIG.
（実施例８）
　酸化処理工程における酸化処理温度（混合雰囲気への切り替え温度）を２２０℃にしたこと以外は、比較例１６と同様にして熱重量・示差熱同時分析を行った。熱重量分析の結果は図７の曲線Ａ５に、示差熱分析の結果は図８の曲線Ａ５に示すとおりであった。 (Example 8)
The thermogravimetric / differential thermal simultaneous analysis was performed in the same manner as in Comparative Example 16 except that the oxidation treatment temperature (the temperature at which the mixed atmosphere was switched) in the oxidation treatment step was 220 ° C. The results of thermogravimetric analysis were as shown in curve A5 in FIG. 7, and the results of differential thermal analysis were as shown in curve A5 in FIG.
（実施例９）
　酸化処理工程における酸化処理温度（混合雰囲気への切り替え温度）を２４０℃にしたこと以外は、比較例１６と同様にして熱重量・示差熱同時分析を行った。熱重量分析の結果は図７の曲線Ａ６に、示差熱分析の結果は図８の曲線Ａ６に示すとおりであった。 (Example 9)
Thermal weight and differential thermal simultaneous analysis were performed in the same manner as in Comparative Example 16 except that the oxidation treatment temperature (the temperature at which the mixed atmosphere was switched) in the oxidation treatment step was 240 ° C. The results of thermogravimetric analysis were as shown by curve A6 in FIG. 7, and the results of differential thermal analysis were as shown by curve A6 in FIG.
（参考例１０）
　酸化処理工程における酸化処理温度（混合雰囲気への切り替え温度）を２６０℃にしたこと以外は、比較例１６と同様にして熱重量・示差熱同時分析を行った。熱重量分析の結果は図７の曲線Ａ７に、示差熱分析の結果は図８の曲線Ａ７に示すとおりであった。 (Reference Example 10)
Simultaneous thermal weight and differential thermal analysis were performed in the same manner as in Comparative Example 16 except that the oxidation treatment temperature (the temperature at which the mixed atmosphere was switched) in the oxidation treatment step was 260 ° C. The results of thermogravimetric analysis were as shown in curve A7 in FIG. 7, and the results of differential thermal analysis were as shown in curve A7 in FIG.
（比較例１９）
　酸化処理工程における酸化処理温度（混合雰囲気への切り替え温度）を３００℃にしたこと以外は、比較例１６と同様にして熱重量・示差熱同時分析を行った。熱重量分析の結果は図７の曲線Ｂ１０に、示差熱分析の結果は図８の曲線Ｂ１０に示すとおりであった。 (Comparative example 19)
Thermal weight and differential thermal simultaneous analysis were performed in the same manner as in Comparative Example 16 except that the oxidation treatment temperature (the temperature at which the mixed atmosphere was switched) in the oxidation treatment step was set to 300 ° C. The results of thermogravimetric analysis were as shown in curve B10 of FIG. 7 and the results of differential thermal analysis were as shown in curve B10 of FIG.
　図９は、図８に示す各実施例及び各比較例のＤＴＡ分析結果（示差熱分析結果）における最大ピーク（ピークトップ）の高さと、酸化処理温度との関係を示すグラフである。図９に示すとおり、酸化処理温度が２００℃以下の場合（比較例１６，１７，１８）では、酸化反応（発熱反応）があまり活発に進行していない。一方、酸化処理温度が２００℃を超えると酸化反応が急激に進行している。したがって、改質炭の表面の酸化をある程度進行させるためには、酸化処理温度を、２００℃を超える範囲にする必要があるといえる。 FIG. 9 is a graph showing the relationship between the height of the maximum peak (peak top) in the DTA analysis results (differential thermal analysis results) of each example and each comparative example shown in FIG. 8 and the oxidation treatment temperature. As shown in FIG. 9, when the oxidation treatment temperature is 200 ° C. or lower (Comparative Examples 16, 17, 18), the oxidation reaction (exothermic reaction) does not progress so actively. On the other hand, when the oxidation treatment temperature exceeds 200 ° C., the oxidation reaction proceeds rapidly. Therefore, in order to advance the oxidation of the surface of the modified coal to a certain extent, it can be said that the oxidation treatment temperature needs to be in the range exceeding 200.degree.
　ただし、図７～図９に示すとおり、熱処理温度が２４０℃を超えると、発熱反応が活発となり重量減少が大きくなる傾向にある。そして、熱処理温度が３００℃の場合には、熱処理を開始してから３～４時間程度で改質炭は自然発火により消失した。このことから、酸化処理工程における改質炭の歩留まりを高くするためには、熱処理温度を２４０℃以下にする必要があるといえる。 However, as shown in FIGS. 7 to 9, when the heat treatment temperature exceeds 240 ° C., the exothermic reaction tends to be active and the weight loss tends to be large. Then, when the heat treatment temperature is 300 ° C., the modified coal disappears by spontaneous ignition within about 3 to 4 hours after the start of the heat treatment. From this, it can be said that the heat treatment temperature needs to be 240 ° C. or lower in order to increase the yield of the modified coal in the oxidation treatment process.
＜自然発火性抑制のメカニズム＞
　上述の比較例６の乾留炭と、比較例９、実施例３及び比較例１０の改質炭の元素分析を行った。その結果を表１に示す。 <Mechanism to suppress spontaneous firing property>
The elemental analysis of the dry-distilled carbon of the above-mentioned comparative example 6 and the modified coal of comparative example 9, example 3 and comparative example 10 was conducted. The results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　上記表１に示されるとおり、乾留炭を２００～３００℃で酸化処理することによって、酸素濃度が高くなることが確認された。すなわち、酸化処理工程は、官能基を酸化して酸素含有量を増やす作用を有している。このような作用によって、自然発火性が抑制されていると考えられる。 As shown in Table 1 above, it was confirmed that the oxidation treatment of dry-distilled coal at 200 to 300 ° C. increased the oxygen concentration. That is, the oxidation treatment step has the function of oxidizing the functional group to increase the oxygen content. It is considered that the spontaneous firing property is suppressed by such an action.
＜自然発火性の比較＞
　実施例１の乾燥工程を行って得られた乾燥炭を、６６０℃で４０分間加熱して乾留炭を調製した。実施例１と同じ自然発火性評価試験を行って、調整した乾留炭の自然発火性の評価を行った。その結果を図１０の曲線Ｆ１に示す。また、図１０には、図２に示されている曲線Ｅ１（乾留炭、乾留温度：４３０℃）も比較のため示す。 <Comparison of spontaneous firing ability>
The dried charcoal obtained by performing the drying step of Example 1 was heated at 660 ° C. for 40 minutes to prepare dry distilled charcoal. The same pyrophoricity evaluation test as in Example 1 was carried out to evaluate the pyrophoric nature of the adjusted dried carbon. The result is shown by curve F1 in FIG. Further, FIG. 10 also shows a curve E1 (dry carbon, dry distillation temperature: 430 ° C.) shown in FIG. 2 for comparison.
　図１０に示すとおり、乾留温度が６５０℃を超えると、自然発火性は大幅に低くなる。しかしながら、乾留温度を６５０℃を超える範囲にすると、酸化処理工程を経て得られる改質炭の歩留まりが低下する。そこで、石炭を３００～６５０℃で乾留して得られる乾留炭の酸化処理を、２００℃を超え２４０℃以下の温度範囲で行うことによって、高品位且つ自然発火性が十分に低減された改質炭を、高い歩留まりで製造することができる。 As shown in FIG. 10, when the distillation temperature exceeds 650 ° C., the spontaneous ignition becomes significantly lower. However, if the dry distillation temperature is in the range exceeding 650 ° C., the yield of the modified coal obtained through the oxidation treatment step is reduced. Therefore, by performing oxidation treatment of dry-distilled coal obtained by dry-distilling coal at 300 to 650 ° C. in a temperature range of more than 200 ° C. and 240 ° C. or less, reforming with high grade and sufficiently reduced spontaneous ignition property Charcoal can be produced with high yield.
　本開示によれば、自然発火性が十分に抑制された改質炭を高い歩留まりで製造することが可能な改質炭の製造方法が提供される。 According to the present disclosure, it is possible to provide a method for producing a modified coal which is capable of producing a modified coal with a sufficiently suppressed spontaneous ignition property at a high yield.
　１０…乾燥装置、２０…乾留装置、３０…酸化処理装置、４０…燃焼炉。 10 ... drying apparatus, 20 ... dry distillation apparatus, 30 ... oxidation treatment apparatus, 40 ... combustion furnace.

Claims (6)

  1. 　石炭を３００～６５０℃で乾留して乾留炭を得る乾留工程と、
    　前記乾留炭を、２００℃を超え且つ２４０℃以下の温度範囲で１０～６０分間酸化処理する酸化処理工程と、を有する、改質炭の製造方法。     Dry distillation at 300 to 650 ° C. to obtain dry carbon;
    And oxidizing the dried carbon in a temperature range of more than 200 ° C. and not more than 240 ° C. for 10 to 60 minutes.
  2. 　前記乾留工程の前に、１５０℃以下で石炭を乾燥する乾燥工程を有し、
    　前記乾留工程では、前記乾燥工程で乾燥された石炭を乾留する、請求項１に記載の改質炭の製造方法。     Before the said dry distillation process, it has a drying process which dries coal below 150 ° C,
    The method for producing modified coal according to claim 1, wherein in the dry distillation step, the coal dried in the drying step is dry distilled.
  3. 　前記石炭は水分が５０質量％以上である、請求項１又は２に記載の改質炭の製造方法。 The method for producing modified coal according to claim 1, wherein the coal has a water content of 50% by mass or more.
  4. 　前記乾留工程で得られる前記乾留炭の揮発分は１０～３０質量％である、請求項１～３のいずれか一項に記載の改質炭の製造方法。 The method for producing modified coal according to any one of claims 1 to 3, wherein the volatile matter content of the dry distilled carbon obtained in the dry distillation step is 10 to 30% by mass.
  5. 　前記酸化処理工程で得られる改質炭の揮発分は５～３０質量％である、請求項１～４のいずれか一項に記載の改質炭の製造方法。 The method for producing modified coal according to any one of claims 1 to 4, wherein the volatile content of the modified coal obtained in the oxidation treatment step is 5 to 30% by mass.
  6. 　前記石炭の乾留によって発生する揮発成分を含むガスを燃焼炉で燃焼する燃焼工程を有し、
    　前記酸化処理工程では、前記燃焼炉からの酸素を含む排ガスによって前記乾留炭を酸化処理する、請求項１～５のいずれか一項に記載の改質炭の製造方法。     The combustion step of burning the gas containing the volatile component generated by the carbonization of the coal in the combustion furnace,
    The method for producing reformed coal according to any one of claims 1 to 5, wherein in the oxidation treatment step, the dry-distilled coal is oxidized by an exhaust gas containing oxygen from the combustion furnace.
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