JP5999114B2 - Method and system for reducing the molecular weight of organic substances - Google Patents

Description

  The present invention relates to a method for modifying an organic substance to reduce the molecular weight in order to convert the organic substance such as plastic into a gaseous fuel and the like, and a low molecular weight system for use in the implementation of the method.

At present, most of waste plastic, oil-impregnated sludge, waste oil, etc. are incinerated. However, incineration treatment has a high environmental load such as CO ₂ generation, and there is a problem of thermal damage of the incinerator, and establishment of chemical recycling technology is required.
Among chemical recycling technologies, technologies for converting organic substances into gaseous fuels and liquid fuels have been variously studied mainly with respect to waste plastics. For example, the following proposals have been made.

In Patent Document 1, a coke oven gas (COG) having a hydrogen concentration of 60 vol% or more, preferably 80 vol% or more and a temperature of 600 ° C or more is reacted with an organic material such as waste plastic, thereby hydrogenating the organic material with high efficiency. A method for increasing the heat of COG by decomposition and gasification is disclosed.
Further, Patent Document 2 discloses a method in which petroleum fluid contact catalyst (FCC) is used as a heat medium / catalyst and waste plastic is decomposed at a temperature of 350 to 500 ° C. to be converted into liquid fuel.
Further, in Patent Document 3, when pyrolyzing RDF, wood, etc., the gas generated by pyrolysis is steam reformed, and the gas having a high hydrogen concentration by this steam reforming is circulated to the pyrolysis section to generate hydrogen. A method of performing pyrolysis in a gas atmosphere with a high concentration is disclosed.

In Patent Document 4, when waste is gasified, the waste is pyrolyzed in an indirect heating kiln furnace, and the gasification gas generated by the pyrolysis and the solid pyrolysis residue are fluidized bed gas. A system that is introduced into a gasification furnace and gasified with a gasifying agent (oxygen or water vapor) is disclosed.
In Patent Document 5, unburnt char generated in a fluidized bed gasification furnace that gasifies biomass, coal, and the like and a fluidized medium are guided to a circulating fluidized bed combustion furnace. A gasification system is disclosed in which a fluidized medium is heated by combustion and circulated through the fluidized bed gasification furnace.

JP 2007-224206 A JP 2010-013657 A JP 2001-131560 A JP 2004-75779 A JP 2005-41959 A International Publication No. 2012/029293

However, the above prior art has the following problems.
First, regarding Patent Document 1, since the hydrogen concentration in COG is 60 vol% or more is limited to the end of the dry distillation in the coal dry distillation process, in the method of Patent Document 1, the gas flow path is opened at the end of the dry distillation. It is necessary to switch and supply COG of 600 ° C. or more containing a large amount of dust to a waste plastic hydrocracking reactor. However, it is difficult to stably operate the flow path switching valve for a long time under such a severe condition, and in this sense, it can be said that the technique is poor in feasibility. Furthermore, for efficient gasification of waste plastic, it is necessary to continuously supply COG containing 60 vol% or more of hydrogen to the hydrocracking reactor. In addition, it is necessary to install a hydrogen concentration meter and a flow path switching valve, which increases the equipment cost.

Moreover, although the method of patent document 2 advances catalytic cracking and aromatization by FCC catalyst addition, since it reacts by an inert gas flow, 13 mass% of heavy oil components and coke are produced | generated in total ( Example 1) is not a satisfactory level as a light fuel production technology.
Further, the gas generated by the method of Patent Document 3 is mainly H ₂ , CO, and CO ₂ , and the combustion heat is about 1800 kcal / Nm ³ that is slightly lower than that of the exhaust gas generated from the metallurgical furnace. The value is limited.

The kiln furnace used in the system of Patent Document 4 is a pyrolysis furnace that indirectly heats waste with combustion exhaust gas generated from a power generation device, and is not a furnace for supplying a gasification heat source. Moreover, the combustion heat of the gas produced | generated by gasification is only about 2700 kcal / Nm < ³ >, and the value as a gaseous fuel becomes limited.

  Further, the system of Patent Document 5 heats a fluid medium using char generated as a by-product in a gasification furnace as a heat source, and uses the heated fluid medium as a heat source for the gasification furnace. However, (i) a circulating fluidized bed combustion furnace that burns char has a lower limit on the flow velocity of combustion air, so the residence time must be controlled by the height of the furnace. As a result, the height of the combustion furnace is increased, and large and expensive equipment is required. (Ii) In order to maintain stable combustion, generally, the flow of air from the lower part of the circulating fluidized bed combustion furnace is reduced. Since the particle density in the lower part of the bed is increased and the secondary air is blown from the middle part of the fluidized bed, there is a problem that the combustion heat lost as the sensible heat of the combustion exhaust gas increases and the thermal efficiency is lowered.

In order to solve such a problem, Patent Document 6 describes that an organic substance is efficiently reformed using a gas that can be stably supplied to reduce the molecular weight, and there is little heavy or carbonaceous matter. As a method of obtaining a high-calorie modified product containing a large amount, it was generated by a shift reaction by adding excess water vapor to an exhaust gas containing carbon monoxide generated in a metallurgical furnace to cause a shift reaction. A method is described in which a mixed gas containing hydrogen and carbon dioxide gas and water vapor that has not been consumed in the shift reaction is brought into contact with an organic substance, and the organic substance is reformed to reduce the molecular weight.
However, in the method of Patent Document 6, since a mixed gas is brought into contact with an organic substance in a reforming reactor such as a rotary kiln or a fixed bed reforming reactor, a solid organic substance such as plastic is brought into the reactor. There is a problem that easily causes troubles such as fusion. Patent Document 6 does not describe anything about the method for supplying the heat of reaction for reducing the molecular weight.

  Therefore, an object of the present invention is to add hydrogen and carbon dioxide gas generated in the shift reaction to the exhaust gas containing carbon monoxide generated in the metallurgical furnace and cause the shift reaction to be consumed in the shift reaction. In the method of making a mixed gas containing water vapor that has not been made, contacting this mixed gas with an organic substance, and modifying the organic substance to lower the molecular weight, problems such as fusion of the organic substance in the reactor occur. It is an object of the present invention to provide a method capable of efficiently reducing the molecular weight of an organic substance and supplying heat of reaction for reducing the molecular weight with optimum equipment and conditions, and a system used for the method. .

  As a result of repeated studies to solve the above problems, the present inventors have obtained the following knowledge. That is, by adding excess water vapor to the exhaust gas containing carbon monoxide generated in the metallurgical furnace and performing a shift reaction, hydrogen and carbon dioxide generated by the shift reaction, and water vapor not consumed in the shift reaction In a method of reducing the molecular weight by bringing the mixed gas into contact with an organic substance and modifying the organic substance, a fluidized bed depolymerization furnace using a granular material containing a specific metal as a fluid medium In this case, the organic material can be efficiently reduced in molecular weight without causing trouble such as fusion of the organic material. In addition, there are particularly suitable conditions for the powder particles used in the fluidized bed molecular weight reduction furnace. Furthermore, the char and fluid medium produced as a by-product in the molecular weight reduction reaction in the fluidized bed molecular weight reduction furnace are guided to the rotary kiln combustion furnace, and the fluid medium is heated by heating the char in the rotary kiln combustion furnace. By circulating the fluidized medium in a fluidized bed depolymerization furnace, it is possible to provide a thermally independent depolymerization system that supplies heat of depolymerization reaction using char generated as a by-product in the depolymerization reaction as a heat source. At the same time, a rotary kiln combustion furnace that burns char has no restriction on the flow rate of combustion air supplied to the furnace, and the residence time of the object to be treated can be controlled relatively freely. This is a small and inexpensive facility, and therefore, it is possible to supply heat of reaction for reducing the molecular weight with optimal facilities and conditions.

The present invention has been made on the basis of such findings and has the following gist.
[1] Addition of excess water vapor to the exhaust gas (g ₀ ) containing carbon monoxide generated in the metallurgical furnace to cause the shift reaction to consume the hydrogen and carbon dioxide generated by the shift reaction and the shift reaction In a method of reducing the molecular weight by modifying the organic substance by bringing the mixed gas (g) into contact with the organic substance and reforming the organic substance.
A fluidized bed having a true density of 4 to 8 g / cm ³ and having a granular material (f) containing at least one selected from Fe, Ni, and Cr as at least a part of the fluidized medium (m). In the molecularization furnace, the mixed gas (g) is brought into contact with an organic substance, and the organic substance is reformed to reduce the molecular weight, and the char and fluid medium (m) produced as a by-product in this molecular weight reduction reaction are converted into a rotary kiln combustion furnace. In this rotary kiln combustion furnace, the fluidized medium (m) is heated by air-burning the char and the heated fluidized medium (m) is circulated in the fluidized bed depolymerization furnace. A method for reducing the molecular weight of a substance.

[2] A method for reducing the molecular weight of an organic substance according to the method of [1], wherein at least a part of the granular material (f) is iron-containing dust generated in a steelmaking process.
[3] A method for reducing the molecular weight of an organic substance according to the method [2] above, wherein the powder (f) is iron-containing dust generated in a steelmaking process.
[4] In the method according to any one of [1] to [3] above, the organic substance to be modified is one or more selected from plastic, oil-containing sludge, waste oil, and biomass. A method for reducing the molecular weight of a substance.
[5] A method for reducing the molecular weight of an organic material according to the method of [4], wherein at least a part of the organic material to be modified is a mixed molded product of plastic and wood.

[6] The method for reducing the molecular weight of an organic substance according to the method of [5], wherein the wood is one or more selected from construction waste wood, packaging / transport waste wood, and thinned wood.
[7] In any one of the above methods [1] to [6], the gas (g _p ) discharged from the fluidized bed depolymerization furnace is passed through a dust collector, and the fluid medium (g _p ) contained in the gas (g _p ) m) is collected, and the collected fluid medium (m) is circulated through a fluidized bed depolymerization furnace.
[8] A method of operating a blast furnace, characterized in that a gas product generated by reducing the molecular weight of an organic substance by any one of the methods [1] to [7] is blown into a blast furnace.

[9] A reactor (1) for adding excess water vapor to an exhaust gas (g ₀ ) containing carbon monoxide generated in a metallurgical furnace to perform a shift reaction;
The reaction apparatus (1) is supplied with a mixed gas (g) containing hydrogen and carbon dioxide gas generated in the shift reaction and water vapor not consumed in the shift reaction, and an organic substance as a low molecular weight raw material is supplied. A low molecular weight furnace to be supplied, having a true density of 4 to 8 g / cm ³ and containing at least one powder (f) containing at least one selected from Fe, Ni, and Cr. (M) fluidized bed low molecular weight reactor (2),
Extracting means (3) for withdrawing the char generated as a by-product in the molecular weight reduction reaction of the organic substance in the fluidized bed molecular weight reduction furnace (2) and the fluidized medium (m) from the fluidized bed molecular weight reduction furnace (2) When,
A rotary kiln combustion furnace (4) for supplying the char and fluid medium (m) extracted by the extraction means (3) and heating the fluid medium (m) by burning the char in air;
An organic material molecular weight reduction system comprising a supply means (5) for supplying a fluidized medium (m) heated in the rotary kiln combustion furnace (4) to a fluidized bed molecular weight reduction furnace (2).

[10] The system according to [9], further comprising a separating means (6) for separating the fluid medium (m) discharged from the combustion exhaust gas after being heated in the rotary kiln combustion furnace (4), and supplying means ( 5) An organic material molecular weight reduction system characterized in that the fluidized medium (m) separated from the combustion exhaust gas by the separation means (6) is supplied to the fluidized bed molecular weight reduction furnace (2).
[11] In the system according to [9] or [10], the rotary kiln combustion furnace (4) is installed at a higher position than the fluidized bed depolymerization furnace (2). system.

According to the method for lowering the molecular weight of an organic substance and the system for lowering the molecular weight according to the present invention, when the molecular weight of a high molecular weight organic substance such as plastic is reduced, a gas that can be stably supplied is used. The organic material is efficiently modified to reduce the molecular weight without causing problems such as fusion of the organic material, resulting in a gas-modified product that contains a small amount of heavy and carbon, and a large amount of light. be able to. Furthermore, a thermal self-sustaining depolymerization system that supplies heat of depolymerization reaction using char generated as a by-product in the depolymerization reaction as a heat source, and a rotary kiln combustion furnace that burns char is Since there is no restriction on the flow velocity of the combustion air to be supplied and the residence time of the object to be treated can be controlled relatively freely, the degree of freedom of the combustion conditions is high, and the equipment is small and inexpensive. Low molecular weight reaction heat can be supplied with equipment and conditions.
In addition, since CO ₂ produced by the shift reaction changes to CO during the reforming of the organic material, it is possible to carry out chemical recycling of the organic material without increasing the amount of CO ₂ generated. It becomes.
Moreover, according to the operating method of the blast furnace which concerns on this invention, the usage-amount of coke which is a reducing material can be reduced, and a carbon dioxide discharge reduction and the reduction of steelmaking cost can be aimed at.

In the shift reaction performed by adding water vapor to the converter gas, a graph showing the relationship between the amount of water vapor added and the composition of the gas after the shift reaction (calculated equilibrium composition at a temperature of 430 ° C.) Explanatory drawing which shows one Embodiment of the molecular weight reduction system of the organic substance which concerns on this invention, and the molecular weight reduction method using the same Explanatory drawing which shows other embodiment of the molecular weight reduction system of the organic substance which concerns on this invention, and the molecular weight reduction method using the same Ring die type compression molding granulator to obtain a mixed molded product of plastic and wood, and an explanatory diagram schematically showing the implementation status of compression molding granulation using this

In the method of the present invention, an excess water vapor is added to an exhaust gas (g ₀ ) containing carbon monoxide generated in a metallurgical furnace (hereinafter sometimes referred to as “metallurgical furnace generated exhaust gas”) to cause a shift reaction. A mixed gas (g) containing hydrogen and carbon dioxide gas generated in the shift reaction and water vapor not consumed in the shift reaction, and this mixed gas (g) (hereinafter sometimes referred to as “shift reaction product gas”). In the method of contacting the organic material with the organic material and modifying the organic material to reduce the molecular weight, the true density is 4 to 8 g / cm ³ and contains at least one selected from Fe, Ni, and Cr. In a fluidized bed depolymerization furnace in which the powder (f) is at least part of the fluidized medium (m), the mixed gas (g) is brought into contact with an organic substance, and the organic substance is modified to reduce the molecular weight. . Furthermore, the char and fluid medium (m) by-produced in the above-mentioned molecular weight reduction reaction are introduced into a rotary kiln combustion furnace, and the fluid medium (m) is heated by air-burning char (carbon) in this rotary kiln combustion furnace. The heated fluid medium (m) is circulated to the fluidized bed low molecular weight furnace. The fluidized medium (m) that has been heated and exited from the rotary kiln combustion furnace is separated from the combustion exhaust gas by a gas separation means, if necessary, and then circulated in a fluidized bed low molecular weight furnace.
In the method of the present invention, adding excess water vapor to the exhaust gas (g ₀ ) means adding water vapor so that excess water vapor that is not consumed in the shift reaction remains in the mixed gas (g).

In such a method of the present invention, the reduction of the molecular weight of the organic substance is efficiently promoted even at a relatively low reaction temperature, the hydrogen consumption is small, and the generation of heavy components and carbonaceous matter is hardly observed.
In general, it is known that a high molecular weight organic substance such as plastic begins to thermally decompose when heated at a temperature of 300 to 400 ° C. or higher, but at this time, it becomes lighter and heavier. Coexistence of hydrogen during thermal decomposition is effective in suppressing heavy formation and reducing the molecular weight because hydrogen addition reaction and hydrocracking reaction to hydrocarbon species proceed. However, the high temperature is required for hydrocracking, and the hydrogen consumption is a problem.

On the other hand, steam reforming and carbon dioxide reforming can be regarded as oxidation of hydrocarbons by oxygen in H ₂ O and CO ₂ molecules, achieving low molecular weight and suppressing carbonaceous production with a small amount of hydrogen addition. it can. Furthermore, steam reforming and carbon dioxide reforming are characterized in that the reaction temperature decreases as the carbon chain of the organic molecule to be modified becomes longer. In the method of the present invention, the low molecular weight of an organic substance is efficiently promoted even at a relatively low reaction temperature, the amount of hydrogen consumption is small, and the generation of heavy components and carbonaceous matter is hardly recognized. It is considered that the four reactions of hydrogenation, hydrocracking, steam reforming, and carbon dioxide reforming proceed simultaneously by reforming (reducing molecular weight) the organic substance using (g).

For example, the exhaust gas generated from a metallurgical furnace such as a converter usually contains about 25 to 80 vol% of CO. Therefore, when water vapor is added thereto, H ₂ and CO ₂ are generated by the following shift reaction (1).
CO + H ₂ O → H ₂ + CO ₂ (1)
In the method of the present invention, since excess water vapor is added to the exhaust gas (g ₀ ), the mixed gas (g) after the shift reaction includes H ₂ , CO ₂ generated by the shift reaction, and H ₂ O of excess addition. Will be included. In the reforming of organic substances (lower molecular weight) by this shift reaction product gas (g), four reactions of hydrogenation, hydrocracking, steam reforming, and carbon dioxide reforming by each gas component proceed simultaneously. it is conceivable that.

In the present invention, the concentration of water vapor, hydrogen, and carbon dioxide in the gas is controlled by appropriately controlling the excess ratio of water vapor added excessively to the exhaust gas (g ₀ ) and the reaction rate of the shift reaction. A mixed gas (g) for material modification can be obtained. However, the general composition of the metallurgical furnace generated exhaust gas stored in the gas holder (for example, a general gas holder used in a steelworks) is CO: 50 to 70 vol%, CO2: 10 to ₂₀ vol%, N _{2: 10~20vol%,} H _2: because of the order 0~5vol% (including other saturated steam) generally is not necessary to carry out until the reaction rate control of the shift reaction, only by adjusting the excess percentage of water vapor Thus, each concentration of water vapor, hydrogen and carbon dioxide in the mixed gas (g) can be controlled to a desired level.
The reaction rate of the shift reaction can be controlled by adjusting the residence time in the shift reactor. For example, in order to shorten the residence time, a method in which the shift reactor length is reduced or the catalyst charge amount is reduced is generally used. In this case, the shift reactor length and the catalyst charge amount are almost until equilibrium. What is necessary is just to set it as about 1 / 2-1 / 4 in the case of advancing reaction.

As an example, converter gas of 100 kmol / h (= 2240 Nm ³ / h) having a composition of CO: 65 vol%, CO ₂ : 15 vol%, N ₂ : 18 vol%, H ₂ : 1 vol%, H ₂ O: 1 vol% In the case of performing the shift reaction by changing the amount of water vapor added from 60 kmol / h (= 1340 Nm ³ / h) to 540 kmol / h (= 1100 Nm ³ / h), the amount of water vapor added and the composition of the gas after the shift reaction ( The calculated equilibrium composition at a temperature of 430 ° C. is shown in FIG. According to this, it can be seen that the concentration of water vapor, hydrogen, and carbon dioxide in the mixed gas (g) can be controlled only by adjusting the amount of water vapor added, and a preferable gas composition as described later can be obtained. In addition, it is well known that the shift reaction usually proceeds to almost equilibrium.

Furthermore, in the present invention, by reducing the molecular weight of the organic substance using a fluidized bed (fluidized bed molecular weight reduction furnace) having a large heat transfer rate, it is possible to control the supply of reaction heat necessary for the reduction of the molecular weight. It is possible to prevent troubles such as high molecular weight organic substances such as plastics fused and clogged in the reactor. Moreover, as the fluidized medium (m) of the fluidized bed, a powder (f) having a true density of 4 to 8 g / cm ³ and containing at least one selected from Fe, Ni, and Cr is used. Thus, since the powder (f) also functions as the fluid catalyst (m), the organic substance can be efficiently modified to obtain a low molecular weight product.

In addition, in the gas discharged from the fluidized bed depolymerization furnace, a part of the granular material (f), which is the fluidized medium (m), and the ash of organic substances such as plastics are scattered. It is collected by a dust collector installed on the downstream side of the molecular furnace, and the powder (f) is usually circulated (returned) to the fluidized bed low molecular furnace. As a granular material (f) that is a fluidized medium (m) of a fluidized bed and functions as a catalyst, a granular material having a true density larger than that of a general fluidized bed fluidized medium and having a true density of 4 g / cm ³ or more. By using the dust collector, the particulate matter (f) is collected separately from the ash content of the organic substance (that is, the particulate matter (f) and the ash content of the organic substance are collected separately) It becomes easy to selectively circulate (return) the granular material (f), and it is possible to prevent the granular material (f) from being diluted with ash that is inert to the low molecular weight reaction. However, the powder (f) having a true density exceeding 8 g / cm ³ has low fluidity.

  In addition, the char (carbon) and fluid medium (m) produced as a by-product in the molecular weight reduction reaction in the fluidized bed low molecular reactor are extracted and led to the rotary kiln combustion furnace, and the char is air-combusted in this rotary kiln combustion furnace. (M) is heated, and this heated fluid medium (m) is circulated to the fluidized bed depolymerization furnace, so that the heat generated by the depolymerization reaction is generated by supplying the heat of the depolymerization reaction. It can be a thermally self-supporting low molecularization system that supplies heat of low molecularization reaction as a heat source. In addition, a rotary kiln combustion furnace that burns char has no restriction on the flow rate of combustion air supplied to the furnace, and the residence time of the object to be processed can be controlled relatively freely. This is a small and inexpensive facility, and therefore, it is possible to supply heat of reaction for reducing the molecular weight with optimal facilities and conditions.

Hereinafter, details and preferable conditions of the present invention will be described.
In the present invention, the reason why the metallurgical furnace generated exhaust gas is used as the exhaust gas (g ₀ ) for the shift reaction is that the metallurgical furnace generated exhaust gas contains carbon monoxide at a relatively high concentration and the concentration of unnecessary nitrogen is low. . As the metallurgical furnace-generated exhaust gas (g ₀ ) containing carbon monoxide, any one can be used. The most representative is the converter gas generated from the converter where the decarburization process of the steel manufacturing process is performed, but other than that, for example, it is generated from a hot metal pretreatment furnace, a smelting reduction furnace, a shaft furnace, etc. Exhaust gas to be used can be exemplified, and one kind or a mixture of two or more kinds thereof can be used.

The secondary combustion rate (CO ₂ / (CO + CO ₂ ) × 100), which is the rate at which carbon monoxide produced in the metallurgical process is further oxidized to produce carbon dioxide, is generally only about 10 to 50%. Also, in the exhaust gas (g ₀₎ are also included hydrogen and nitrogen, H ₂ concentration varies depending on the metallurgical process, it is about 0~20vol%. Nitrogen is supplied for in-furnace agitation and flue safety, and the concentration in the exhaust gas (g ₀ ) is about 10 to 30 vol%.
From the above points, the composition of general metallurgical furnace-generated exhaust gas (g ₀ ) is generally in the following range.
CO: 80-25 vol% (equivalent to 10-50% secondary combustion rate)
CO _2: 10~25vol% (corresponding to the secondary combustion rate 10-50%)
N _2: 10~30vol%
H2: 0 to ₂₀ vol%

Although carbon monoxide is required for the shift reaction, there is no particular problem with the composition of the exhaust gas (g ₀ ) as long as the gas composition is in the above range. Here, nitrogen does not contribute at all to the chemical reaction (shift reaction, hydrogenation, hydrocracking, steam reforming, carbon dioxide reforming) occurring in the present invention, while diluting the gaseous fuel produced, Low combustion heat (hereinafter referred to as “LHV”) is reduced. In particular, when the nitrogen concentration exceeds 50 vol%, the LHV of the gaseous fuel is significantly reduced and the shift reaction rate tends to be reduced. Therefore, the nitrogen concentration is preferably within the above composition range.

As mentioned earlier, gas holder (e.g., typical gas holder used in steelworks) General composition of metallurgical furnace generation exhaust gas to be stored in the, CO: 50~70vol%, CO 2 : 10 ˜20 vol%, N ₂ : 10 to ₂₀ vol%, H ₂ : 0 to 5 vol% (including saturated steam in addition), and this composition is high in the composition of the above general metallurgical furnace generated exhaust gas. It corresponds to the CO concentration composition. Since the gas stored in the gas holder is used as fuel gas at each factory in the steelworks, it is necessary to prevent a decrease in combustion efficiency at the use destination. Therefore, setting the lower limit value of the CO concentration in the gas as a storage condition in the gas holder is the reason why the composition has a high CO concentration.
In the present invention, the composition of the exhaust gas generated in the general metallurgical furnace as described above is used even if the exhaust gas has a relatively high CO concentration as stored in a general gas holder used in a steelworks. However, it can be used as exhaust gas (g ₀ ).

Incidentally, some metallurgical furnace-generated exhaust gas (g ₀ ) has a relatively low carbon monoxide concentration and a high nitrogen concentration, such as blast furnace gas. Such metallurgical furnace-generated exhaust gas (g ₀ ) Alternatively, at least a part of the nitrogen contained may be separated (removed) to increase the carbon monoxide concentration, and then an excessive water vapor may be added to cause the shift reaction. Although it cannot be uniformly determined because of the required specification of the combustion heat of the gaseous fuel generated by lowering the molecular weight of the organic substance, if the nitrogen concentration in the exhaust gas exceeds 30 vol%, a nitrogen separation step is provided and the exhaust gas ( It is preferable to separate (remove) at least part of the nitrogen from g ₀ ).
As typical exhaust gas that is preferably subjected to nitrogen separation, blast furnace gas can be mentioned, but in addition to this, exhaust gas generated from an electric furnace or a shaft furnace operating under a condition where the nitrogen concentration becomes high can be mentioned. it can. In addition, the nitrogen gas is separated from an exhaust gas containing a relatively high concentration of carbon monoxide such as a converter gas, and the shift reaction can be performed after further increasing the carbon monoxide concentration.

There is no particular restriction on the method for separating nitrogen from exhaust gas, and any method such as adsorption separation method or distillation separation method can be applied. However, since the boiling point difference between nitrogen and carbon monoxide is small, the adsorption separation method is Particularly preferred. For example, since activated carbon supporting Cu ⁺ , which is known as a CO adsorbent, also adsorbs CO ₂ , blast furnace gas (general composition: N ₂ : 50 vol%, CO ₂ ) is obtained by PSA method using Cu ⁺ supported activated carbon as an adsorbent. : _25vol%, CO 2: approximate composition as desorbed gas from 25 vol%) is _{N 2: 15vol%, CO:} 45vol%, CO 2: it is possible to obtain a 40 vol% of the gas, which separates the nitrogen in the blast furnace gas Thus, the carbon monoxide is concentrated.

The shift reaction in the method of the present invention may be carried out by a known method and is not particularly limited. Generally, water vapor is added to the metallurgical furnace-generated exhaust gas (g ₀ ) in advance, and this is introduced into a fixed bed reactor filled with a catalyst to perform a shift reaction. Alternatively, the water vapor to be added in advance may be partially used, the catalyst may be packed in multiple stages in the reactor, and the remaining water vapor may be added between the catalyst layer and the catalyst layer.
If water vapor, hydrogen, and carbon dioxide are added to the metallurgical furnace-generated exhaust gas (g ₀ ) without performing the shift reaction as in the present invention, the mixture for organic substance modification obtained by the shift reaction in the present invention is used. Although a gas having a composition equivalent to that of the gas (g) can be obtained, in such a method, in addition to water vapor, expensive hydrogen gas and carbon dioxide gas must be added, resulting in an increase in cost.

In the present invention, the mixed gas (g) for reforming the organic substance obtained by the shift reaction contains water vapor, hydrogen and carbon dioxide gas, and there is no particular limitation on the concentration thereof. Therefore, the water vapor concentration is preferably 5 to 70 vol%. In other words, when the water vapor concentration is low, the decomposition rate of organic substances such as plastics is low. However, by setting the water vapor concentration to 5 vol% or more, a certain level of organic material decomposition rate can be secured, and the production rate of gaseous fuel (gas Conversion rate) can be maintained at a constant level, and the amount of heavy components produced can be reduced. On the other hand, when the water vapor concentration is high, CO ₂ tends to remain in the reformed product gas of organic substances (gas generated by the reforming of organic substances, hereinafter the same), and the LHV of the gaseous fuel decreases. However, if the water vapor concentration is 70 vol% or less, it is possible to suppress the residual CO _{2 in} the reforming reaction product gas, and it is also possible to suppress the decrease in the LHV of the gaseous fuel / liquid fuel.
Further, from the viewpoint of ensuring the decomposition rate of the organic substance, both the hydrogen concentration and the carbon dioxide concentration of the mixed gas (g) are preferably 5 vol% or more.

Moreover, for the following reasons, the more preferable composition of the mixed gas (g) for organic substance reforming is: water vapor concentration: 20 to 70 vol%, hydrogen concentration: 10 to 40 vol%, carbon dioxide concentration: 10 to 40 vol%. It is. In addition, it does not prevent that other gas components (for example, nitrogen etc.) are contained in this mixed gas (g). By setting the water vapor concentration to 20 vol% or more, the decomposition rate of the organic substance can be sufficiently increased, and the LHV of the gaseous fuel can be increased. The reason for setting the water vapor concentration to 70 vol% or less is as described above. By setting the hydrogen concentration to 10 vol% or more (more preferably 12 vol% or more), it is possible to suppress the CO ₂ from remaining in the gaseous fuel even when the organic substance is reformed at a relatively low temperature. Can do. By setting the carbon dioxide gas concentration to 10 vol% or more (more preferably 13 vol% or more), H ₂ which is a low-calorie gas component is less likely to remain in the gaseous fuel as compared to hydrocarbons and CO. Moreover, the decomposition rate of organic substances, such as a plastic, can be made into a preferable level by making hydrogen concentration and carbon dioxide gas concentration into 40 vol% or less. Moreover, from the above viewpoints, a more preferable gas composition of the mixed gas (g) is a water vapor concentration: 25 to 65 vol%, a hydrogen concentration: 15 to 35 vol%, and a carbon dioxide concentration: 15 to 35 vol%. In addition, it does not prevent that other gas components (for example, nitrogen etc.) are contained in this mixed gas (g).

Next, conditions for modifying (lowering the molecular weight) of an organic substance with the mixed gas (g) obtained by the shift reaction will be described.
In the present invention, there is no particular limitation on the organic material to be reduced in molecular weight by modification, but a high molecular weight organic material is suitable, for example, plastic (usually waste plastic), oil-containing sludge, waste oil, biomass. One or more of these can be targeted.

Although there is no special restriction | limiting in the kind of target plastic, For example, an industrial waste type | system | group, a target plastic of the container packaging recycling law etc. can be mentioned. More specifically, polyolefins such as PE and PP, thermoplastic polyesters such as PA and PET, elastomers such as PS, thermosetting resins, synthetic rubbers, foamed polystyrene and the like can be mentioned. In addition, inorganic substances such as fillers are added to many plastics. However, in the present invention, such inorganic substances are not involved in the reaction, and therefore, as a solid residue, a reforming reactor (fluidized bed low molecular weight furnace. The same applies hereinafter). In addition, the plastic is pre-cut into an appropriate size as required, and then charged into the reforming reactor.
Further, if the plastic contains a chlorine-containing resin such as polyvinyl chloride, chlorine is generated in the reforming reactor, and this chlorine may be contained in the product. Therefore, when the plastic may contain a chlorine-containing resin, it is preferable to introduce a chlorine absorbent such as CaO into the reforming reactor so that the chlorine content is not contained in the gas product. .

  Oil-containing sludge is a sludge-like mixture generated in an oil-containing waste liquid treatment step, and generally contains about 30 to 70% by mass of water. Examples of the oil in the sludge include, but are not limited to, various mineral oils, natural and / or synthetic oils and fats, and various fatty acid esters. In addition, in order to improve handling property, such as when supplying oil-impregnated sludge to the reforming reactor, moisture in the sludge may be reduced to about 30 to 50% by mass by a method such as centrifugation.

Examples of the waste oil include, but are not limited to, various used mineral oils, natural and / or synthetic fats and oils, and various fatty acid esters. Moreover, the mixture of these 2 or more types of waste oil may be sufficient. In addition, in the case of waste oil generated in the steel mill rolling process, it generally contains a large amount of water (usually more than about 80% by mass), but this water is also reduced in advance by a method such as specific gravity separation. It is advantageous in terms of handleability.
When the organic substance contains water, water vapor is generated in the reforming reactor. Therefore, the excess ratio of water vapor added in the shift reaction is determined in consideration of the amount.

  Examples of biomass include sewage sludge, paper, wood (for example, construction waste wood, packaging / transport waste wood, thinned wood, etc.), and processed biomass such as solid waste fuel (RDF). However, it is not limited to these. Since biomass usually contains a large amount of water, it is preferable to dry it beforehand in view of energy efficiency. In addition, in the case of biomass containing relatively high concentrations of alkali metals such as sodium and potassium, alkali metals may be deposited in the reforming reactor. It is preferable to keep it. Large biomass such as construction waste wood and packaging / transport waste wood is cut in advance and put into the reforming reactor.

  Moreover, as an organic substance used as object, the mixed molded product of plastic (usually waste plastic) and wood (molded product of the mixture of plastic and wood) is preferable. This mixed molding is a compression molding of a mixture of plastic and wood (both small-sized materials such as small blocks, granules or small pieces), and frictional heat generated during the molding process and / or external heating applied during the molding process. Thus, the plastic is at least partially melted or softened, and the melted or softened plastic is solidified as a binder. In this case, only the plastic on the surface of the mixed molded product may be melted or softened, and the melted or softened plastic may be used as a binder to form a solidified outer shell. The wood is preferably one or more of construction waste wood, packaging / transport waste wood, and thinned wood from the viewpoint of effective use of resources, but is not limited thereto. Note that the packaging / transportation waste wood specifically means wood that is no longer necessary after packing or transporting work such as waste wooden boxes or waste pallets.

  The reason why the above-mentioned mixed molded article is preferable as the organic substance to be used in the present invention is that (a) the chlorine contained in the plastic is not a chlorine-containing wood (construction waste wood, packaging / transport waste wood) , Thinned wood, etc.), (b) the ash contained in the plastic is diluted with low ash wood, (c) at least partly due to frictional heat in the molding process as described above Plastics that have been melted or softened as a binder can improve the formability of wood, improve handling, and (d) low molecular weight organic substances due to oxygen atoms usually contained in wood at relatively high concentrations And the like are promoted.

Therefore, it is preferable that at least a part of the organic material to be modified is a mixed molded product of plastic and wood (for example, one or more of construction waste wood, packaging / transport waste wood, and thinned wood).
The ratio of wood in the mixed molded product is preferably about 10 to 70% by mass, and more preferably about 20 to 60% by mass. When the ratio of the wood is less than 10% by mass, the effects (a), (b), and (d) described above are hardly exhibited. On the other hand, when the ratio of the wood exceeds 70% by mass, the binder effect due to the molten or softened plastic of the above (c) is reduced. Moreover, when the ratio of wood exceeds 70 mass%, the combustion heat of the gaseous product produced | generated by a low molecular-ized reaction falls, and it is unpreferable.

  There is no restriction | limiting in particular in the manufacturing method of the mixed molding of a plastic and wood. Usually, plastic and wood (for example, one or more of construction waste wood, packaging / transport waste wood, and thinned wood) are preliminarily crushed so that they have a small diameter, granular, or small piece of material. It becomes. The size of the plastic or wood after the crushing process, that is, the screen of the crusher is determined according to the size of the target mixed molded product, for example, the outer diameter using a compression molding granulation method with a ring die described later. Is about 6 to 30 mm, the screen opening of the crusher is suitably about 10 to 30 mm. In addition, in order to protect the crusher and the forming granulator, it is common to remove metal foreign matters in advance by wind separation or magnetic separation.

  Plastic and wood are mixed in advance or in the molding process and compression molded to a predetermined size. There is no special restriction | limiting in this shaping | molding method, For example, well-known methods, such as the compression molding granulation method by a ring die, can be applied. The plastic is at least partially melted or softened by frictional heat generated in the molding process of the plastic and wood mixture or external heating applied in the molding process, and the molded product is solidified by using the molten or softened plastic as a binder.

  FIG. 4 schematically shows a ring die type compression molding granulator and an implementation status of compression molding granulation using the same. This compression molding granulator has a die ring 16 in which a large number of die holes 160 (round holes) are provided in the entire periphery, and is rotatable inside the die ring 16 so as to be in contact with the inner peripheral surface of the die ring. A plurality of (usually 2 to 3) rolling rollers 17 disposed on the die ring and a cutting blade 18 for cutting the mixed molded product extruded from the die hole 160 and scraping it off from the outer peripheral surface of the die ring. ing. The die ring 16 and the rolling roller 17 are both rotatably supported by an apparatus main body (not shown). The die ring 16 is driven to rotate by a driving device, whereas the rolling roller 17 is a non-driven free drive. The roller body rotates with the rotation of the die ring 16 due to friction with the inner peripheral surface of the die ring. Moreover, although the hole diameter of the die hole 160 is decided according to the magnitude | size (diameter) of the mixture which should be granulated, it is about 3-20 mm normally.

  In this ring die type compression molding granulator, the die ring 16 is rotationally driven in the direction of the arrow in the figure, and the rolling roller 17 is also rotated in the direction of the arrow. In this state, plastic and wood that have been crushed to an appropriate size in accordance with the size of the die hole diameter are put into the die ring 16 from a not-shown slot, and the thrown material is a rolling roller. 17 is pressed into the die hole 160 of the die ring 16 while being crushed and compressed between the inner peripheral surface of the die ring (there is also a crushing action by crushing). The material (mixture) pushed into the die hole 160 is compressed in the process of passing through the die hole 160, and the surface (surface in contact with the inner peripheral surface of the die hole) by frictional heat with the inner peripheral surface of the die hole. The plastic is melted or softened. The material (mixture) that has passed through the die hole 160 is sequentially extruded in the form of a column to the outer peripheral surface side of the die ring 16, and at this time, the plastic on the surface that has been melted or softened is solidified. An outer shell is formed using the solidified plastic as a binder. Then, when the cylindrical molded product pushed out to the outer peripheral surface of the die ring reaches the position of the cutting blade 18 by the rotation of the die ring 16, it is scraped off from the outer peripheral surface of the die ring 16 by the cutting blade 18, thereby A mixed molded product is obtained.

  The reaction temperature during organic substance modification is preferably as follows according to the type of organic substance. In the case of plastic or biomass, the reaction temperature is suitably about 400 to 900 ° C. When the reaction temperature is less than 400 ° C., the decomposition rate of plastic and biomass is low. On the other hand, when the reaction temperature exceeds 900 ° C., the production of carbonaceous matter increases. In the case of oil-containing sludge or waste oil, the reaction temperature is suitably about 300 to 800 ° C. When the reaction temperature is less than 300 ° C., the decomposition rate of oil-containing sludge and waste oil becomes low. On the other hand, even if the reaction temperature exceeds 800 ° C., there is no effect on the reforming (lower molecular weight) characteristics of the oil-containing sludge or waste oil, but it is not economical because the temperature is higher than necessary.

Moreover, when the mixture which consists of a plastic and / or biomass and oil-containing sludge and / or waste oil is made into object, about 400-800 degreeC is suitable for reaction temperature from the point mentioned above. Since almost no influence of pressure is observed, it is economical to operate the reforming reactor at normal pressure or slightly pressurized of about several kg / cm ² .
In addition, when a mixture molded product of plastic and wood (for example, at least one of construction waste wood, packaging / transport waste wood, and thinned wood) is used, a reaction temperature of about 400 to 900 ° C. is appropriate. .

  In addition, since the wood with a soft tree structure such as paulownia has a relatively high reactivity, the reaction temperature is set to 20 when compared with the case of plastic alone when a mixture molded product of such wood and plastic is targeted. It can be lowered by -30 ° C. However, the density and specific gravity of the timber vary greatly depending on the position of a single tree as well as the type and location of the tree. Furthermore, since waste wood becomes a mixture of various woods, it is not always possible to lower the reaction temperature. From such a point of view, an appropriate reaction temperature range is 400 to 900 ° C. even for a plastic-wood mixed molding.

In the present invention, a fluidized bed low molecular weight furnace is used as the reforming reactor. That is, the mixed gas (g) is brought into contact with an organic substance in a fluidized bed molecular weight reduction furnace, and the organic substance is modified to reduce the molecular weight. As already described, in the present invention, the four reactions of hydrogenation, hydrocracking, steam reforming, and carbon dioxide reforming proceed simultaneously, so that organic substances such as plastics can be made low molecular weight with high efficiency. In fact, it is clear that in addition to these, a pyrolysis reaction also proceeds. Of these, hydrocracking, steam reforming, carbon dioxide reforming, and thermal cracking are endothermic reactions, and the exothermic reaction is only hydrogenation. Therefore, this reaction is generally endothermic, and it is necessary to supply reaction heat.
This is not a big problem when reducing the molecular weight of plastics batchwise, but the problem when conducting reactions in a flow-type fixed bed reactor is that the rate of supply of reaction heat becomes rate limiting, and plastics are not contained in the reactor. For example, the heat efficiency is deteriorated by fusing or supplying heat higher than necessary to prevent fusing, and the plastic is carbonized by the high-temperature supply heat. It is done.

On the other hand, the fluidized bed depolymerization furnace is characterized by the fact that the temperature in the fluidized bed is almost uniform and the heat transfer is very fast, so that the problems that occur in the fixed bed reactor described above are avoided. be able to. Further, in the present invention, the true density is 4 to 8 g / cm ³ as at least a part of the fluidized medium (m) of the fluidized bed (preferably the main component of the fluidized medium (m)), and Fe, Ni, Cr The granular material (f) containing at least 1 sort (s) chosen from the inside is used. Fe, Ni, and Cr are all active in this reaction, and the low molecular weight reaction proceeds with high efficiency by the powder (f) functioning also as a catalyst. On the other hand, in the waste plastic gasification technology by the conventional fluidized bed, sand is often used as a fluidized medium. However, sand not only has no catalytic activity, but also has a slightly larger particle size as a fluid medium, and the conditions under which a stable fluidized bed can be formed are limited, making it difficult to deal with various raw materials. In addition, the presence form of Fe, Ni, Cr contained in a granular material (f) does not ask | require a distinction, such as a metal and an oxide. The reason why the true density of the powder (f) is 4 to 8 g / cm ³ will be described later.

  The total content of Fe, Ni and Cr in the powder (f) is preferably about 20 to 90% by mass, and more preferably about 30 to 80% by mass. When the content is less than 20% by weight, the true density of the granular material (f) becomes small, so that the granular material (f) scattered in the gas discharged from the fluidized bed depolymerization furnace and the ash content of the organic substance The segregated collection (collected in a state where both are separated) tends to be insufficient. On the other hand, if the content exceeds 90% by mass, the true density becomes excessive and the fluidity is lowered.

  As already described, the organic molecule reduction reaction in the present invention is generally endothermic, and it is necessary to supply reaction heat. In a circulating fluidized bed combustion furnace as shown in Patent Document 5, since the lower limit is imposed on the flow velocity of combustion air, the residence time must be controlled by the height of the furnace. As a result, the height of the combustion furnace is increased, and a large and expensive facility is required. In order to maintain stable combustion, generally, the amount of air blown from the lower part of the circulating fluidized bed combustion furnace is decreased to increase the particle density of the lower part of the fluidized bed, and the secondary air is blown from the middle part of the fluidized bed. Another disadvantage is that more combustion heat is lost as sensible heat of the combustion exhaust gas, resulting in a decrease in thermal efficiency.

  In contrast, in the present invention, char, which is a by-product of the molecular weight reduction reaction, is burned in a rotary kiln combustion furnace, the fluid medium (m) is heated with the combustion heat, and the heated fluid medium (m) is fluidized. Low molecular weight reaction heat is supplied by circulating in a low molecular weight reactor. In rotary kiln combustion furnaces, there is no restriction on the flow rate of combustion air supplied to the furnace, and the residence time of the workpiece is controlled relatively freely by three factors: furnace length, furnace rotation speed, and furnace tilt angle. Therefore, there is a feature that the degree of freedom of the combustion conditions is high, and the combustion furnace can be configured in a small size and at low cost. Also, secondary air blowing is not necessary, and as a result, a system with high thermal efficiency can be obtained.

Next, the low molecular weight system (equipment) of the present invention will be described. For convenience of explanation, the apparatus configuration of the low molecular weight system will be described with reference numerals corresponding to the embodiments of FIGS.
The system of the present invention includes a reaction apparatus 1 (shift reactor) for adding excess water vapor to a metallurgical furnace exhaust gas (g ₀ ) to perform a shift reaction, and a mixed gas (g) (shift reaction generation from the reaction apparatus 1). Gas) and a low molecular weight furnace to which an organic substance as a low molecular weight raw material is supplied, having a true density of 4 to 8 g / cm ³ and selected from Fe, Ni, and Cr In the fluidized bed depolymerization furnace 2 (reforming reactor) having at least a part of the granular material (f) containing at least one kind of the fluidized medium (m), and the fluidized bed depolymerization furnace 2 Char generated as a by-product of the organic molecule depolymerization reaction, the extraction medium 3 for extracting the fluid medium (m) from the fluidized bed depolymerization furnace 2, and the char and the fluid medium extracted by the extraction means 3 (M) is supplied, and the fluid medium (m) is heated by burning the char in the air. A re-kiln combustion furnace 4 and supply means 5 for supplying the fluidized medium (m) heated in the rotary kiln combustion furnace 4 to the fluidized bed low-molecularization furnace 2 are provided.
Further, if necessary, a separation means 6 for separating the fluid medium (m) discharged from the combustion exhaust gas after being heated in the rotary kiln combustion furnace 4 is provided, and the supply means 5 is separated from the combustion exhaust gas by the separation means 6. The separated fluid medium (m) is supplied to the fluidized bed depolymerization furnace 2.

The configuration of the reaction apparatus 1 (shift reactor) is arbitrary and is not particularly limited. For example, a known apparatus such as a fixed bed reactor filled with a catalyst can be applied.
The configuration of the fluidized bed low molecular weight reactor 2 is as described above.
The structure of the extraction means 3 is arbitrary and is not particularly limited. For example, it may be a mechanical extraction means such as a suction pump, but is connected to an intermediate portion of the fluidized bed low molecular weight reactor 2 and overflows. The extraction tube for extracting the char and the fluid medium (m) is most convenient.
The configuration of the separation means 6 (gas-solid separation device) is arbitrary and is not particularly limited, but a hot cyclone installed at a position higher than the fluidized bed depolymerization furnace 2 is the simplest.

  The structure of the supply means 5 is arbitrary, and is not particularly limited. However, one end of the supply means 5 is connected to the upper part of the fluidized bed low molecular weight furnace 2 and discharged from the rotary kiln combustion furnace 4 or discharged from the separation means 6 ( m) In the case where the supply pipe for supplying the fluidized bed depolymerization furnace 2 is the simplest and the separation means 6 is a hot cyclone installed higher than the fluidized bed depolymerization furnace 2, its dipleg Can be configured.

  When the rotary kiln combustion furnace 4 is installed at a position lower than the fluidized bed depolymerization furnace 2 (an embodiment as shown in FIG. 2 described later), the fluid medium (m) extracted from the fluidized bed depolymerization furnace 2 is The rotary kiln combustion furnace 4 can be charged as it is through the extraction means 3 such as an extraction rod. On the other hand, the fluidized medium (m) that has been heated and exits the rotary kiln combustion furnace 4 is preferably transported by gas to the upper part of the furnace in order to be supplied to the fluidized bed low molecular weight furnace 2. For example, when the separation means 6 is constituted by a hot cyclone installed at a position higher than the fluidized bed depolymerization furnace 2 and the supply means 5 is constituted by a dipleg of the hot cyclone, the rotary kiln combustion furnace 4 is The flowing fluid medium (m) is guided to the hot cyclone by gas transport, and the fluid medium (m) separated by the hot cyclone is supplied to the fluidized bed low molecular weight reactor 2 by natural fall through the hot cyclone dipleg (circulation). It is the simplest to do. In this case, since the temperature of the fluid medium (m) is lowered while the fluid medium (m) is guided to the hot cyclone by gas transportation, it is preferable to set the combustion temperature in the rotary kiln combustion furnace 4 to be relatively high.

  On the other hand, when the rotary kiln combustion furnace 4 is installed at a position higher than the fluidized bed depolymerization furnace 2 (an embodiment as shown in FIG. 3 described later), the fluid medium extracted from the fluidized bed depolymerization furnace 2 (m ) Is preferably gas transported to the rotary kiln combustion furnace 4, but the fluid medium (m) exiting the rotary kiln combustion furnace 4 does not require gas transport. Therefore, the fluid medium (m) exiting the rotary kiln combustion furnace 4 is directly supplied to the fluidized bed low molecular weight reactor 2 through a supply pipe or the like, or the separation means 6 is positioned higher than the fluidized bed low molecular weight reactor 2. When the hot cyclone is installed and the supply means 5 is a dipleg of the hot cyclone, the fluid medium (m) exiting the rotary kiln combustion furnace 4 is naturally dropped to the hot cyclone and this hot cyclone is introduced. It is most convenient to supply (circulate) the fluidized medium (m) separated by the cyclone to the fluidized bed depolymerization furnace 2 by natural fall through a hot cyclone dipleg.

  In this case, the temperature reduction of the fluidized medium (m) is slight because the gas transport of the fluidized medium (m) leaving the rotary kiln combustion furnace 4 is unnecessary. There is a merit that the thermal efficiency is higher than the case where it is installed at a lower position. However, since the rotary kiln combustion furnace 4 is generally operated at a negative pressure and the fluidized bed depolymerization furnace 2 is operated at a positive pressure, a sufficient static pressure in the dipleg can be taken by a material seal or the like to prevent backflow. is necessary. The configuration of the material seal is arbitrary and is not particularly limited. For example, a loop seal, an L valve type seal, and the like are appropriate.

In general, the fluidized bed depolymerization furnace 2 is operated at a slight positive pressure, and the rotary kiln combustion furnace 4 is operated at a slight negative pressure. Therefore, the rotary kiln combustion furnace 4 is lower than the fluidized bed depolymerization furnace 2. In the case where it is installed at the position, a backflow prevention measure is not necessary for the supply pipe from the fluidized bed depolymerization furnace 2 to the rotary kiln combustion furnace 4.
In the rotary kiln combustion furnace 4, a liquid component by-produced in the fluidized bed depolymerization furnace 2 or a gas introduced from the outside may be used as a part of the fuel. In the case where the liquid component by-produced in the fluidized bed depolymerization furnace 2 or the gas introduced from the outside is used as a part of the fuel, it may be burned by a general combustion nozzle, and there is no limitation. In addition, when the organic substance supplied to the fluidized bed depolymerization furnace 2 is an organic substance having a high oxygen content and a small amount of fixed carbon, such as PMMA resin, the char production rate is low, and is obtained in the rotary kiln combustion furnace 4. The combustion heat generated may be reduced, and the supply of heat for reducing the molecular weight may be insufficient. In such a case, it is economical and preferable to introduce and burn a liquid component by-produced in the fluidized bed depolymerization furnace 2. In addition, when the low molecular weight system is started up, neither char nor by-product liquid is present, so it is necessary to combust gas fuel such as natural gas or liquid fuel such as light oil introduced from the outside in the rotary kiln combustion furnace 4. Become.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 2 shows an embodiment of a low molecular weight system for organic substances and a low molecular weight method using the same according to the present invention. In the figure, 1 is a reaction apparatus (shift reactor) for performing a shift reaction of metallurgical furnace exhaust gas (g ₀ ), 2 is a fluidized bed depolymerization furnace (reforming reactor) for reducing the molecular weight of organic substances, Extraction means for extracting char and fluid medium (m) produced as a by-product of organic molecule depolymerization reaction from fluidized bed depolymerization furnace 2, 4 is a rotary kiln that heats the fluid medium (m) by air-burning char Combustion furnace, 6 is a separation means (gas-solid separation device) for separating the fluid medium (m) heated in the rotary kiln combustion furnace 4 from the combustion exhaust gas, and 5 is a fluidized medium (m) supplied to the fluidized bed depolymerization furnace 2. 14 is a supply means for supplying the mixed gas (g) from the reaction apparatus 1 to the fluidized bed depolymerization furnace 2. 8 is a discharge pipe for discharging gas from the fluidized bed depolymerization furnace 2, 9a is a primary dust collector (upstream first stage dust collector) provided in the discharge pipe 8, and 9b is a secondary dust collector (second downstream side dust collector). Stage dust collector).

The structures of the reactor 1 and the fluidized bed molecular weight reduction furnace 2 are as described above.
The rotary kiln combustion furnace 4 is installed at a position lower than the fluidized bed depolymerization furnace 2. The extraction means 3 is connected to the middle part of the fluidized bed depolymerization furnace 2 and is composed of an extraction pipe 30 for extracting char and fluid medium (m) by overflow, and the separation means 6 is a hot cyclone 60. The supply means 5 is constituted by a dipleg 50 of the hot cyclone 60. The supply means 14 is constituted by a supply pipe 140.
The fluidized bed depolymerization furnace 2 and the hot cyclone 60 are connected by a transport pipe 7, and air is supplied to the transport pipe 7 through a loop seal such as an L-valve seal, thereby fluidized bed low molecular weight. The fluid medium (m) that has exited the conversion furnace 2 can be transported to the hot cyclone 60.

Generally, the primary dust collector 9a is a cyclone, but the type of the secondary dust collector 9b is arbitrary, and may be a dry dust collector or a wet dust collector. When the secondary dust collector 9b is a dry dust collector, the exhaust gas is not cooled to the condensation temperature of the liquid product, so that the product passing through the secondary dust collector 9b remains in a gaseous state. A cooler, an oil / water separator, etc. are installed on the downstream side, and separated into gas products, liquid products, and waste water. On the other hand, when the secondary dust collector 9b is a wet dust collector, the exhaust gas is cooled and the liquid product is condensed. Therefore, the product passing through the secondary dust collector 9b is a gas product and is captured by the secondary dust collector 9b. The collected material will be a mixture of ash, wastewater, and liquid product. Therefore, an oil / water separator is installed in the mixture discharge system to separate the liquid product.
In FIG. 2, the primary dust collector 9 a is installed outside the fluidized bed depolymerization furnace 2, but may be installed inside the fluidized bed depolymerization furnace 2.

Hereinafter, the molecular weight reduction of the organic substance performed using the molecular weight reduction system of FIG. 2 will be described.
In the reactor 1, hydrogen gas and carbon dioxide gas generated by the shift reaction and the shift reaction are performed by adding excess water vapor to the exhaust gas (g ₀ ) containing carbon monoxide generated in the metallurgical furnace to perform the shift reaction. A mixed gas (g) containing water vapor that was not consumed is obtained. This mixed gas (g) is supplied to the fluidized bed molecular weight reduction furnace 2 through the supply pipe 140 (supply means 14).

In the fluidized bed depolymerization furnace 2, the mixed gas (g) is introduced into the wind box portion 13 on the lower side of the dispersion plate 12, and the mixed gas (g) blows out from the dispersion plate 12, thereby The fluidized bed 10 is formed by the fluidized medium (m). An organic substance such as plastic is supplied to the fluidized bed 10 from the upper part of the fluidized bed depolymerization furnace 2 and is reduced in molecular weight by reacting with the mixed gas (g) in the fluidized bed 10 to become a gas product. The gas (g _p ) containing the gaseous product is discharged through the discharge pipe 8, and then the fluid medium (m) and organic substances scattered in the gas (g _p ) by the primary dust collector 9a and the secondary dust collector 9b. Ash is collected, but the fluidized medium (m) and the organic ash are collected as separated as possible. In other words, the primary dust collector 9a mainly collects the fluid medium (m) and prevents the ash from being collected as much as possible, and the secondary dust collector 9b mainly collects the ash of organic substances. For this purpose, as will be described later, it is important to optimize the true density of the granular material (f) that is the fluid medium (m). The collected matter mainly composed of the fluidized medium (m) collected by the primary dust collector 9 a is circulated to the fluidized bed low molecular weight reactor 2 through the return pipe 11. In addition, you may arrange | position the primary dust collector 9a and the return pipe | tube 11 in the free board part of the upper part in the fluidized bed molecular weight reduction furnace 2. FIG. The gas (g _p ) that has passed through the secondary dust collector 9b is recovered, but the gas product contained in this gas (g _p ) is partially gas fuel and the other part is condensed. Each can be used as a liquid fuel.
As described above, in the present invention, the gas (g _p ) discharged from the fluidized bed is passed through the dust collector, the fluid medium (m) contained in the gas (g _p ) is collected, and the collected flow It is preferable to circulate the medium (m) in the fluidized bed.

The powder particles (f) constituting the fluid medium (m) have a true density of 4 to 8 g / cm ³ , more preferably 4 to 7.5 g / cm ³ . As described above, the granular material (f), which is a fluidized medium, and the ash content of the organic substance are scattered in the gas (g _p ) discharged from the fluidized bed depolymerization furnace 2, so that these are gas (g _p ), and among these, the granular material (f) is circulated in the fluidized bed low molecular weight reactor 2. When the true density of the granular material (f) is less than 4 g / cm ³ , since the density difference from the ash content of the organic substance is small, it becomes difficult to separate and collect from the organic ash content. Separation of ash tends to be insufficient. Specifically, in FIG. 2, it becomes difficult to mainly collect only the granular material (f) in the primary dust collector 9a, and a considerable amount of organic ash is also collected. As a result, the granular material (f) separated from the gas (g _p ) and circulated to the fluidized bed depolymerization furnace 2 is diluted with ash that is inactive to the depolymerization reaction. The catalytic activity of this continuously decreases. On the other hand, when the true density of the granular material (f) exceeds 8 g / cm ³ , the fluidity as the fluid medium (m) decreases. Here, a true density means the density measured using a pycnometer based on JIS-K-0061.

Even when the fluid medium (m) collected and separated by the primary dust collector 9a is not circulated through the fluidized bed depolymerization furnace 2, if the true density of the powder (f) is less than 4 g / cm ³ , It is difficult to collect the body (f) and ash separately, and the powder (f) is still diluted by the ash. When steelmaking dust as described later is used as the granular material (f), since this steelmaking dust is very inexpensive, the steelmaking dust collected by the dust collector is circulated to the fluidized bed low molecular weight furnace 2 and reused. However, the steelmaking dust is usually returned to the iron making process to recover the iron content, and if this contains a considerable amount of ash, the amount of slag generated in the iron making process increases due to this ash. Therefore, in any case, in order to prevent the granular material (f) collected from the gas (g _p ) from being diluted with ash, the true density of the granular material (f) must be 4 g / cm ³ or more. I must.

As the granular material (f) which is a fluid medium and functions as a catalyst, a known Ni-based reforming catalyst or Ni-based hydrogenation catalyst can be used, but (i) it has a high catalytic activity because it contains a large amount of iron. Steelmaking for reasons such as being high, (ii) having a true density in the range of 4-8 g / cm ³ and being fine particles and therefore suitable as a fluid medium, (iii) being available in large quantities and being inexpensive. It is particularly preferable to use iron-containing dust generated in the process (hereinafter referred to as “steel-making dust” for convenience of explanation). Steelmaking dust generally contains 30% by mass or more of iron. Since this steelmaking dust is generally collected by a wet process, a drying process is necessary, but a classification process or the like is not necessary.

Steelmaking dust is iron-containing dust generated mainly in a steelmaking process performed using a converter, and examples of the steelmaking process include a dephosphorization process, a decarburization process, and a stainless steel refining process. It is not limited to these. In the present invention, one or more of these steelmaking dusts can be used.
Although the rate of steelmaking dust varies from steelworks to steelworks, the amount generated is proportional to the amount of crude steel produced, so it is available in large quantities. Moreover, since the value of steelmaking dust is equivalent to that of crude steel, it is very inexpensive at around tens of thousands of yen per ton. On the other hand, a commercially available catalyst costs several million yen per ton, and it is very advantageous in terms of cost to use steelmaking dust as the granular material (f).

Steelmaking dust generally has a particle size distribution with a particle size lower limit of about 0.1 μm and an upper limit of about 200 μm, a median diameter (d50) of about 5 to 30 μm, and a specific surface area of 10 to 20 m ² / g. A coarse particle having a particle size distribution in which the lower limit of particle size is about 1 μm, the upper limit is about 2000 μm, the median diameter (d50) is about 30 to 200 μm, and the specific surface area is 1 m ² / g or less. There is grain dust. In general, exhaust gas discharged mainly from converters in the steelmaking process is collected in a wet form, but the amount that can be separated from water without adding a flocculant is coarse dust, and the addition of a flocculant is necessary for separation. Minutes are fine dust.

  In the present invention, either fine dust or coarse dust may be used. However, when fine dust and coarse dust are compared, fine dust has a higher specific surface area than coarse dust and therefore has higher catalytic activity, while the stability in fluidized state is better than coarse dust than fine dust. Is excellent. Further, since the iron content on the surface of the steelmaking dust particles is oxidized, the proportion of the oxidized iron content is increased in the fine dust having a larger specific surface area. For this reason, since the true density is larger in the coarse dust than in the fine dust, the blowing power of the mixed gas (g) which is a fluidized gas is larger in the case where the coarse dust is used. From the above points, by mixing and using fine dust and coarse dust, it is possible to form a fluidized bed in which high catalytic activity, stability in a fluidized state, and suppression of blowing power are ensured in a well-balanced manner. .

  A suitable mixing ratio of the fine dust and the coarse dust is not limited because it depends on the ratio [Lf / D] of the fluidized bed height Lf and the low molecular weight reactor inner diameter D, but generally the fine dust and the coarse dust are not limited. The mixing ratio [fine dust: coarse dust] (mass ratio) is suitably about 1:10 to 1: 5 when Lf / D is about 0.1 to 0.5, and Lf / D is In the case of over 0.5 to about 2, a ratio of about 1: 5 to 1: 1 is appropriate, and in the case of Lf / D of over 2 to about 10, a ratio of about 1: 1 to 5: 1 is appropriate.

Moreover, as a granular material (f), what carried out the classification process to about several dozen-several hundred micrometers after drying a mill scale etc. besides the steelmaking dust mentioned above can also be used. Such a classified product such as mill scale contains a large amount of iron as well as steelmaking dust, so it can be used alone as a granular material (f), but both catalytic activity and flow characteristics are better than steelmaking dust. Since it is low, it is preferable to use it mixed with steelmaking dust.
In addition, reduced iron powder produced by reducing the mill scale and atomized iron powder produced from molten steel by the water atomization method can be used alone as a powder (f). Since it is large, it is better to mix it with steelmaking dust and use it with good fluidity.
Therefore, the powder (f) is at least partly made of steelmaking dust, preferably mainly made of steelmaking dust (that is, containing 50% by mass or more of steelmaking dust), more preferably steelmaking dust. It is desirable to consist of.

  The fluid medium (m) is mainly composed of the powder (f) (that is, containing 50% by mass or more of the powder (f)), but other powders may be added. For example, by mixing one or more inorganic powders such as alumina powder and silica sand, the fluidity can be further improved and the increase in the blowing power of the mixed gas (g) can be suppressed. When the inorganic powder is mixed, the mixing ratio is set to less than 50% by mass so as not to cause a significant decrease in the catalytic activity of the granular material (f).

As shown in FIG. 2, a mixed gas (g), which is a fluidized gas of the fluidized medium (m), is supplied from the lower part of the fluidized bed depolymerization furnace and blown upward from the gas dispersion plate 12 to form the fluidized bed 10. To do. The flow rate of the mixed gas (g) blown out from the gas dispersion plate 12 is only required to maintain a good dispersion state, and usually about 0.05 to 2 m / sec is appropriate. If it is less than 0.05 m / sec, the fluidity decreases. On the other hand, if the flow velocity exceeds 2 m / sec, there is no problem in fluidity, but the flow velocity of the gas (g _p ) discharged from the fluidized bed depolymerization furnace 2 increases, and the amount of scattered fluid increases and the cyclone increases. As described later, it is necessary to increase the particle size of the solid organic material when the solid organic material is supplied from the upper part of the fluidized bed depolymerization furnace. Decreases.

  As for the method of supplying the organic substance into the fluidized bed depolymerization furnace 2, the liquid organic substance such as oil-containing sludge or waste oil may be sprayed by a spray nozzle or the like, and the supply position is the same as that of the fluidized bed depolymerization furnace 2. Any position such as the upper part or the upper part of the gas dispersion plate 12 may be used. On the other hand, in the case of a solid organic material such as plastic or biomass, it is common to supply from the upper part of the fluidized bed low molecular weight reactor 2, but a part of the mixed gas (g) is branched and mixed gas ( It can also be supplied to the upper part of the gas dispersion plate 12 by pneumatic transportation according to g). In addition, when supplying a solid organic substance from the upper part of the fluidized bed molecular weight reduction furnace 2, it is easier to drop by gravity rather than supplying by pneumatic transportation. However, in that case, it is preferable to mold the supplied solid organic material so that the particle size and density do not scatter, and to select a particle size that does not reduce the reaction efficiency.

In the present invention, the organic substance such as plastic is reduced in molecular weight and the number of molecules is increased about twice, so the flow rate of the product gas in the fluidized bed low molecularization furnace is about twice that of the mixed gas (g). It is necessary to note that. For example, if the flow rate of the mixed gas (g) is 0.05 m / sec, the flow rate of the product gas is about 0.1 m / sec. Therefore, the true density of the solid organic substance is preferably 1 g / cm ^3. The particle size is about 2 to 6 mm. Moreover, if the flow rate of the mixed gas (g) is 2 m / sec, the flow rate of the product gas is about 4 m / sec. Therefore, when the true density of the organic substance is 1 g / cm ³ , the preferred particle size is 15 to It is about 20 mm.

In the fluidized bed depolymerization furnace 2, char is produced as a by-product due to the depolymerization reaction of the organic substance. This char and the fluid medium (m) are extracted from the extraction tube 30 (extraction means 3) due to overflow. The extraction pipe 30 is naturally dropped and supplied (introduced) to the rotary kiln combustion furnace 4. In the rotary kiln combustion furnace 4, the fluid medium (m) is heated by air burning the char. At this time, the combustion conditions are controlled by the flow rate of combustion air supplied to the furnace, the rotational speed of the furnace, and the like.
The fluid medium (m) heated in the rotary kiln combustion furnace 4 is air-fed to the hot cyclone 60 (separation means 6) through the transport pipe 7. In the hot cyclone 60, the fluidized medium (m) is separated from the combustion exhaust gas, and the separated fluidized medium (m) is naturally dropped through the dipleg 50 (supplying means 5) of the hot cyclone 60 by a fluidized bed low molecular weight reactor. 2 (circulation).

  As described above, in this embodiment, the temperature of the fluid medium (m) decreases while the fluid medium (m) exiting the rotary kiln combustion furnace 4 is guided to the hot cyclone 60 (separation means 6) by gas transport. Therefore, it is preferable to set the combustion temperature in the rotary kiln combustion furnace 4 relatively high. In general, the fluidized bed depolymerization furnace 2 is operated at a slight positive pressure, and the rotary kiln combustion furnace 4 is operated at a slightly negative pressure. When installed at a position lower than the molecularization furnace 2, a backflow prevention measure is not necessary for the supply piping from the fluidized bed low molecularization furnace 2 to the rotary kiln combustion furnace 4.

FIG. 3 is another embodiment of the organic material molecular weight reduction system and the molecular weight reduction method using the same according to the present invention. The rotary kiln combustion furnace 4 is installed at a position higher than the fluidized bed low molecular weight furnace 2. Embodiments are shown.
As in the embodiment of FIG. 2, the extraction means 3 is connected to an intermediate part of the fluidized bed molecular weight reduction furnace 2 and is composed of an extraction pipe 30 for extracting char and fluid medium (m) by overflow. In this embodiment, the extraction pipe 30 and the rotary kiln combustion furnace 4 are connected by a transport pipe 7a. By flowing air for nitrogen through a loop seal such as an L-valve seal to the transport pipe 7a, The fluidized medium (m) extracted from the bed molecular weight reduction furnace 2 can be transported to the rotary kiln combustion furnace 4. Here, the reason why nitrogen is used as the gas for air feeding is that when air is used for air, char is burned in the transport pipe 7a and becomes a high temperature, so that the transport pipe 7a needs to be an expensive heat-resistant material. is there. In addition, since nitrogen is used for the gas for air transportation, in order to prevent the oxygen concentration in the rotary kiln combustion furnace 4 from being lowered, the fluid medium (m) is separated from the air for air feeding to the inlet side of the rotary kiln combustion furnace 4. The separating means 15 is provided. The configuration of the separating unit 15 is arbitrary and is not particularly limited. In the present embodiment, the separating unit 15 is configured by a hot cyclone 150.
Since the other configuration is the same as that of the embodiment shown in FIG. 2, the same reference numerals are given and the detailed description is omitted.

In this embodiment, after the char and fluid medium (m) in the fluidized bed depolymerization furnace 2 are extracted from the extraction pipe 30 (extraction means 3) due to overflow, the transport pipe 7a leads to the rotary kiln combustion furnace 4. Be informed. At this time, the fluid medium (m) is separated from the air-feeding nitrogen in the cyclone 150 (separating means 15), and the separated fluid medium (m) is introduced into the rotary kiln combustion furnace 4 as it is to burn the char by air. To heat the fluid medium (m).
Since the rotary kiln combustion furnace 4 is installed at a higher position than the fluidized bed depolymerization furnace 2, the fluid medium (m) exiting the rotary kiln combustion furnace 4 is spontaneously dropped and introduced into the hot cyclone 60 (separation means 6). The fluid medium (m) separated from the combustion exhaust gas by the hot cyclone 60 is supplied (circulated) to the fluidized bed depolymerization furnace 2 by natural fall through the dipleg 50 (supply means 5) of the hot cyclone 60.

  As described above, in this embodiment, since the gas transport of the fluid medium (m) exiting the rotary kiln combustion furnace 4 is unnecessary, the temperature drop of the fluid medium (m) is slight, as shown in FIG. In addition, the thermal efficiency is higher than in the case where the rotary kiln combustion furnace 4 is installed at a position lower than the fluidized bed depolymerization furnace 2. On the other hand, generally, the fluidized bed depolymerization furnace 2 is operated at a slight positive pressure, and the rotary kiln combustion furnace 4 is operated at a slightly negative pressure. When installed at a position higher than the molecularization furnace 2, in order to prevent the backflow of the fluid medium (m) from the fluidized bed low molecularization furnace 2 to the rotary kiln combustion furnace 4, a material seal (for example, It is necessary to take measures to prevent backflow such as loop seals and L-valve seals).

The gasified product (gas product) of the organic substance obtained by the method of the present invention is usually light hydrocarbons of CO and C1 to C4, and is suitable as a gaseous fuel. Moreover, a part can be condensed and it can also be set as a liquid fuel.
The LHV in the gaseous fuel is about 6 to 10 Mcal / Nm ^3, which is the same as natural gas. Nevertheless, since the carbon monoxide concentration is high, it is characterized by higher combustibility than natural gas. Because of its high carbon monoxide concentration and high combustibility, it is safer to use it as a city gas alternative fuel in factories with metallurgical furnaces such as steelworks than to supply it as household city gas. preferable.

  Further, the gas product obtained by the method of the present invention can be used not as a fuel but as a reducing material such as a blast furnace. As mentioned above, this gas product mainly consists of light hydrocarbons and carbon monoxide, which are natural gas components, but both natural gas and carbon monoxide are effective as reducing materials for iron ore, so in blast furnace operation, By blowing the gas product obtained by the method of the present invention from the tuyere of a blast furnace, the amount of coke used as a reducing material can be reduced, which is effective in reducing carbon dioxide emissions and iron manufacturing costs.

[Example 1]
A branch pipe for a laboratory test is provided in the gas discharge pipe of the gas holder for temporarily storing the converter gas, and a small flow rate of the converter gas can be extracted through the branch pipe. On the downstream side of this branch pipe, there are a flow control valve, a steam mixer, a preheater (for converter gas and steam mixed gas), a fixed bed shift reactor (inner diameter 30 mm), an external heating fluidized bed reactor (fluidized bed). The low molecular weight furnace, inner diameter 44 mm) was arranged in this order. Piping is connected so that the total amount of shift reaction product gas can be supplied from the bottom of the fluidized bed reactor, and a circle feeder type quantitative charging device is provided so that waste plastic can be dropped into the reactor from the top of the fluidized bed reactor. Was installed. From the upper part of the fluidized bed reactor, a product sampling port was connected via a cyclone as a first stage dust collector, a gas filter as a second stage dust collector, and a gas cooler. Since the cyclone dipleg is not inserted into the fluidized bed reactor, the fluid medium (catalyst) is not circulated in this embodiment.

The average composition of the converter gas in the gas _{holder, H 2: 12vol%, CO} : 54vol%, CO 2: 17vol%, H 2 O: 1vol%, N 2: was 16 vol%. The steam mixer was supplied with 74 NL / h of the converter gas and 100 NL / h of steam at a pressure of 10 kg / cm ² G as steam, and the temperature was raised to 320 ° C. with a preheater, and then the shift reactor (Fe-Cr system) High temperature shift catalyst filling). Due to the shift reaction in the shift reactor, gas having a gas composition of H ₂ : 26 vol%, CO: ₂ vol%, CO ₂ : 28 vol%, H ₂ O: 37 vol%, N ₂ : 7 vol% (shift reaction product gas) Obtained. This shift reaction product gas had a flow rate of 172 NL / h (170 g / h in mass flow rate) and a reactor outlet gas temperature of 430 ° C.

A gas dispersion plate is provided in the lower part of the externally heated fluidized bed reactor, which is a reforming reactor for reducing the molecular weight of organic substances. Generated converter dust coarse particles (T-Fe: 80% by mass, average particle size: 80 μm, true density: 5.9 g / cm ³ , bulk density 2.9 g / cm ³ , Al ₂ O ₃ content 0.38 After charging 1 kg of (mass%), nitrogen gas was supplied at 50 NL / h to fluidize the converter dust. The fluidized bed height was about 280 mm (Lf / D = 6.4).

Next, after heating the fluidized bed reactor at a set temperature of 650 ° C., the fluidizing gas was switched from nitrogen to the shift reaction product gas (flow rate: 172 NL / h, flow rate at 650 ° C .: 0.1 m / sec). Next, a model waste plastic obtained by mixing 3.3% by mass of Al ₂ O ₃ (ash model material) with polyethylene into a particle size of 4 mm and a bulk density of 0.4 g / cm ³ is 910 g / h (880 g as polyethylene content) / H, Al ₂ O ₃ minutes at 30 g / h), and after continuing the low molecular weight reaction of the waste plastic for 1 hour, the gaseous fuel is calculated from the gas analysis results after cooling by the gas cooler. The amount was determined from the analysis results of the liquid products collected in the liquid fuel collector installed at the lower part of the gas cooler, and the production amount, composition, and LHV (low combustion heat) were obtained. The results are shown in Table 1.

  Since the total amount of shift reaction product gas and polyethylene supplied as raw materials is 1050 g / h, the production rate with respect to the total amount of feed materials is 36% for gaseous fuel (defined as products from H2 to C4), and liquid fuel (C5 The definition of the above product) was 58%. Since it is difficult to directly measure the amount of unreacted polyethylene, the total yield of gaseous fuel (380 g / h) and liquid fuel (610 g / h) relative to the total amount of shift reaction product gas and polyethylene (1050 g / h) supplied. Is defined as the polyethylene degradation rate, the polyethylene degradation rate was calculated to be 94% in this invention example.

While the reaction was continued, the temperature in the reactor, which was the fluidized bed portion, was about 649 ° C., which was about 1 ° C. lower than the set temperature, but there were no troubles such as fusion or blockage of polyethylene. After the experiment was completed, the reactor was disassembled and the inside was observed, but formation of carbides such as fused organic substances was not observed, and it was confirmed that stable fluidization reaction could be performed by the fluidized bed. About 20 g of solid was recovered from the cyclone dipleg at the end of the experiment. When the recovered solid was analyzed, the Al ₂ O ₃ content was 0.42 wt% (0.084 g as the amount of Al ₂ O ₃ ). On the other hand, the solid collected by the gas filter which is a 2nd stage dust collector was about 26g. When the collected solid was analyzed, the Al ₂ O ₃ content was 99.6% by weight (25.9 g as the amount of Al ₂ O ₃ ), and the Fe content was below the detection limit. Considering experimental errors, it is considered that Al ₂ O ₃ which is a model ash and fluid medium (coarse dust) are almost completely separated.

  When the fluid medium (coarse dust) extracted from the fluidized bed reactor was subjected to elemental analysis, it contained 4% by mass of carbon (char). Furthermore, as a result of observing the state of carbon with a scanning electron microscope and X-ray diffraction, carbon is adhered in the form of fine particles on the surface of coarse dust (converter dust coarse particles), which is a fluid medium, and iron carbide (cementite) Production of was not observed.

  500 g of this coarse particle dust containing 4% by mass of carbon was taken and filled in an external heating (electric furnace) batch type rotary kiln, and air was supplied at 100 NL / min. Next, the rotary kiln was heated with an electric furnace at a heating rate of 5 ° C./min. In the rotary kiln, a thermocouple was installed in the vicinity of the coarse dust so that the temperature rise of the coarse dust due to the combustion of carbon could be confirmed. It was found that the temperature suddenly increased from the time when the temperature near the coarse dust reached about 400 ° C., and the combustion of carbon started. The maximum temperature in the vicinity of coarse dust was about 850 ° C. After the kiln combustion experiment, coarse dust was taken out and subjected to elemental analysis. As a result, the carbon content was 0.1% by mass or less. From the above points, it was found that the carbon particles adhering to the coarse dust surface can be burned quantitatively.

  From the heat balance calculation, it is possible to maintain the temperature of the fluidized bed reactor at 650 ° C. by circulating coarse dust having a temperature of 800 ° C. or higher to the fluidized bed reactor. Although the kiln combustion experiment is a batch type experiment, it is clear that the coarse dust can be heated to 800 ° C. or more by combustion of char (carbon) attached to the coarse dust even in a continuous rotary kiln.

[Example 2]
Industrial waste plastic and construction waste wood from which foreign materials such as metal have been removed are crushed by a crusher equipped with a screen with a mesh opening of 10 mm, and the crushed waste plastic and construction waste wood are The mixture was put into a ring die type compression molding granulator at a ratio of 7 parts by mass of waste plastic and 3 parts by mass of construction waste wood to obtain a mixed molded product. The compression molding granulator is equipped with a die ring having a plurality of die holes (φ6 mm) penetrating the entire circumference, and a mixture of waste plastic and construction waste wood is compressed and extruded from the die hole of the die ring. Is obtained.
The low molecular weight reduction reaction test of the mixed molded product of waste plastic and waste wood was conducted in the same manner as in Example 1 except that the mixed molded product was supplied to the fluidized bed reactor and the set temperature of the fluidized bed reactor was set to 600 ° C. went.

Analysis of the low molecular weight reaction product, the gaseous fuel generation rate 38%, the composition of the gaseous _{fuel, CO: 65vol%, N 2} : 5vol%, C1~C2: 9vol%, C3~C4: 21vol% ( H ₂ , CO ₂ , and H ₂ O were all 0 vol%), LHV was 8.5 Mcal / Nm ³ , and the liquid fuel production rate was 60%. During the reaction, there was no trouble such as plastic fusing or clogging in the fluidized bed reactor, and the low molecular weight reaction could be performed stably. Furthermore, the ash content in the mixed molded product was collected almost quantitatively by the gas filter which is the second stage dust collector, and there was no problem in separating the actual ash content and the fluid medium (coarse dust).
About the fluid medium (coarse dust) extracted from the fluidized bed reactor, the same kiln combustion experiment and heat balance calculation as in Example 1 were performed. As a result, carbon particles (char) adhering to the surface of the coarse dust were quantitatively determined. It was confirmed that the coarse dust could be heated to 800 ° C. or higher by burning the char (carbon).

[Comparative Example 1]
The low molecular weight reaction test of polyethylene was conducted in the same manner as in Example 1 except that the reactor was filled with a catalyst in which converter dust coarse particles were molded to a particle size of 4 mm. In this test, as a result of setting the catalyst particle size to 4 mm, the catalyst was not fluidized, and therefore the reaction was carried out in a flow-through fixed bed reactor.
The reaction was stopped because the temperature in the reactor gradually decreased from the start of the polyethylene supply, and the reactor pressure increased, making it difficult to supply the shift reaction product gas.
When the reactor was disassembled and the inside was observed, the catalyst layer was clogged with a substance that was considered to be a polyethylene fusion product, and unlike a fluidized bed, a flow-through fixed bed reactor could stably perform a low molecular weight reaction. It was confirmed that it was very difficult to do.
In this comparative example, the char combustion experiment could not be performed because the catalyst layer was clogged with the fusion material.

[Comparative Example 2]
Example 1 except that blast furnace dust (T-Fe: 45% by mass, Al ₂ O ₃ content: 2% by mass, true density: 3 g / cm ³ , average particle size: 400 μm) was used as a fluid medium (catalyst). Similarly, a molecular weight reduction reaction test of Al ₂ O ₃ -containing polyethylene was performed.
As a result of the low molecular weight reaction test, there was no problem with the fluidized state, polyethylene fusion and clogging as in Example 1, but the solid density recovered from the cyclone was very small because the true density of the fluidized medium was low. Most solids (Al ₂ O ₃ which is blast furnace dust and model ash) were collected by a gas filter, and model ash and blast furnace dust could hardly be separated.
Since most of the blast furnace dust was collected by the gas filter, there was no necessity of conducting a char combustion experiment.

DESCRIPTION OF SYMBOLS 1 Reactor 2 Fluidized bed molecular weight reduction furnace 3 Extraction means 4 Rotary kiln combustion furnace 5 Supply means 6 Separation means 7, 7a Transport pipe 8 Discharge pipe 9a Primary dust collector 9b Secondary dust collector 10 Fluidized bed 11 Return pipe 12 Dispersion plate 13 Wind box section 14 Supply means 15 Separation means 16 Die ring 17 Rolling roller 18 Cutting blade 30 Extraction rod 50 Dipreg 60 Hot cyclone 140 Supply pipe 150 Hot cyclone 160 Die hole

Claims (11)

By adding excess water vapor to the exhaust gas (g ₀ ) containing carbon monoxide generated in the metallurgical furnace to cause the shift reaction, hydrogen and carbon dioxide generated by the shift reaction were not consumed in the shift reaction. In a method of making a mixed gas (g) containing water vapor and bringing the mixed gas (g) into contact with an organic substance and modifying the organic substance to reduce the molecular weight,
A fluidized bed having a true density of 4 to 8 g / cm ³ and having a granular material (f) containing at least one selected from Fe, Ni, and Cr as at least a part of the fluidized medium (m). In the molecularization furnace, the mixed gas (g) is brought into contact with an organic substance, and the organic substance is reformed to reduce the molecular weight, and the char and fluid medium (m) produced as a by-product in this molecular weight reduction reaction are converted into a rotary kiln combustion furnace. In this rotary kiln combustion furnace, the fluidized medium (m) is heated by air-burning the char and the heated fluidized medium (m) is circulated in the fluidized bed depolymerization furnace. A method for reducing the molecular weight of a substance.   The method for reducing the molecular weight of an organic substance according to claim 1, wherein at least a part of the powder (f) is iron-containing dust generated in a steelmaking process.   The method for reducing the molecular weight of an organic substance according to claim 2, wherein the powder (f) is iron-containing dust generated in a steelmaking process.   The method for reducing the molecular weight of an organic substance according to any one of claims 1 to 3, wherein the organic substance to be modified is at least one selected from plastic, oil-containing sludge, waste oil, and biomass.   The method for reducing the molecular weight of an organic substance according to claim 4, wherein at least a part of the organic substance to be modified is a mixed molded product of plastic and wood.   6. The method for reducing the molecular weight of an organic substance according to claim 5, wherein the timber is at least one selected from construction timber, packaging / transport timber, and thinned wood. The gas (g _p ) discharged from the fluidized bed low molecular weight furnace is passed through a dust collector, the fluid medium (m) contained in the gas (g _p ) is collected, and the collected fluid medium (m) is collected. The method for reducing the molecular weight of an organic substance according to any one of claims 1 to 6, wherein the method is circulated in a fluidized bed molecular weight reduction furnace.   A method for operating a blast furnace, wherein a gas product generated by reducing the molecular weight of an organic substance by the method according to claim 1 is blown into the blast furnace. A reactor (1) for adding an excess water vapor to an exhaust gas (g ₀ ) containing carbon monoxide generated in a metallurgical furnace to perform a shift reaction;
The reaction apparatus (1) is supplied with a mixed gas (g) containing hydrogen and carbon dioxide gas generated in the shift reaction and water vapor not consumed in the shift reaction, and an organic substance as a low molecular weight raw material is supplied. A low molecular weight furnace to be supplied, having a true density of 4 to 8 g / cm ³ and containing at least one powder (f) containing at least one selected from Fe, Ni, and Cr. (M) fluidized bed low molecular weight reactor (2),
Extracting means (3) for withdrawing the char generated as a by-product in the molecular weight reduction reaction of the organic substance in the fluidized bed molecular weight reduction furnace (2) and the fluidized medium (m) from the fluidized bed molecular weight reduction furnace (2) When,
A rotary kiln combustion furnace (4) for supplying the char and fluid medium (m) extracted by the extraction means (3) and heating the fluid medium (m) by burning the char in air;
An organic material molecular weight reduction system comprising a supply means (5) for supplying a fluidized medium (m) heated in the rotary kiln combustion furnace (4) to a fluidized bed molecular weight reduction furnace (2).   Furthermore, it comprises a separating means (6) for separating the fluid medium (m) discharged from the combustion exhaust gas after being heated in the rotary kiln combustion furnace (4), and the supplying means (5) is combusted by the separating means (6). The system for lowering the molecular weight of an organic substance according to claim 9, wherein the fluidized medium (m) separated from the exhaust gas is supplied to a fluidized bed lowering furnace (2).   The system for reducing the molecular weight of an organic substance according to claim 9 or 10, characterized in that the rotary kiln combustion furnace (4) is installed at a higher position than the fluidized bed depolymerization furnace (2).

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