JP4397423B1 - Gasification method - Google Patents

Abstract

The present invention provides a method for efficiently and stably generating a gas that can be used effectively as waste and can be recovered as fuel.
The waste material A containing fine dust and papermaking sludge B are mixed, and the fine dust of the waste material A is adsorbed and flocked by the papermaking sludge B, and the flocked dust adheres to the waste material A. A gasification method characterized by pyrolyzing the raw material C in a non-oxidizing atmosphere and reacting the generated pyrolysis gas with steam.
[Selection figure] None

Description

  The present invention relates to a gasification method. More specifically, the present invention relates to a method for efficiently and stably generating a gas that can be effectively used as a waste resource and can be recovered as fuel.

  In recent years, methods to effectively use waste resources such as waste wood, thinned wood, driftwood, waste chopsticks, bark, etc., so-called "biomass", which have been disposed of by incineration in the past in order to prevent global warming and promote a recycling-oriented society Various studies have been made. As a method for treating such biomass, a direct combustion method and a gasification method are generally considered.

  The direct combustion method completely burns biomass, and for example, a combustion furnace such as a stoker furnace, a fluidized bed furnace, a fine powder combustion furnace, or a spouted bed furnace is used. Only the thermal energy can be recovered and utilized by the direct combustion method, and electricity is generated by generating hot water or steam by the thermal energy.

  In the gasification method, biomass is partially oxidized by oxygen or air, and gasification furnaces such as a fixed bed furnace, a fluidized bed furnace, a bubbling type fluidized bed furnace, a circulating fluidized bed furnace, and a circulating moving bed furnace are used. . In the gasification method, thermal energy and gas can be recovered and used, and hot water and electric power can be obtained using the thermal energy. Moreover, it is also possible to collect hot water and electric power using the gas as fuel, or to use it as a heat source as a combustion aid in a kiln furnace or the like.

  In addition, due to regulatory measures to reduce dioxins generated by waste incineration, simple incineration processing of industrial waste such as biomass is also regulated, and simple incineration processing is becoming impossible. On the other hand, the promotion of recycling of construction waste wood is included in the basic policy of the Construction Recycling Law, and the construction waste wood and the like have to be recycled.

  However, the total domestic emission of industrial waste and general waste is usually about 0.5 to 3 tons / day, and when it becomes the waste wood that is the main material of the biomass, it is only about 1 ton / day. Compared with the processing amount in the direct combustion method or gasification method, it is considerably small. In particular, waste wood has been used once as a construction material for houses and the like, and has become a material with an extremely low moisture content due to a decrease in moisture in the wood over time. In the gasification furnace, the moisture contained in the raw material increases the gas tightness in the gasification furnace, which contributes to the improvement of operational stability and gasification efficiency in the gasification furnace. It becomes necessary to supply moisture. However, even if moisture is supplied to the waste wood, it is difficult to increase the water content by impregnating the waste wood into the raw material (in the raw material). It evaporates immediately after being supplied to the gasifier and does not contribute to the gas tightness in the gasifier. Therefore, although treatment and effective utilization of biomass are required, development of a new technology for improving operation stability and gasification efficiency in a gasification furnace is desired at the same time.

  On the other hand, in paper mills, the yield of fine fibers is increased by the rapid and forced dehydration at the wire part due to the high blending of waste paper pulp containing many fine fibers in recent years, the paper weight reduction, and the speed of the paper machine. And the yield of ash is very low. As a result, papermaking sludge discharged in each papermaking process has been increasing year by year.

  In particular, a large amount of used paper pulp is required due to an increase in the production ratio of recycled paper using used paper pulp and a high blending of used paper pulp, and the amount of used paper is also increasing. Waste paper such as used newspapers and magazines contains a lot of inorganic substances derived from fillers used in uncoated paper and fillers and pigments used in coated paper. A large amount of deinking sludge separated from fibers and containing a large amount of inorganic substances such as fillers and pigments is generated.

  Conventionally, deinking sludge discharged from waste paper processing processes that contain a large amount of inorganic substances such as fillers and pigments, and paper sludges such as wastewater and dewatered sludge discharged from each papermaking process, are conventionally burned to reduce the volume. Many have been disposed of in landfills.

  However, in order to continuously produce recycled paper that can contribute to environmental protection, resource protection, dust reduction, etc., while maintaining or improving its quality, paper mills need to recycle such paper sludge. And effective use have become important issues.

  Therefore, various treatment methods have been further studied in order to recycle and effectively use the biomass and paper sludge.

  For example, in Patent Document 1, blast furnaces and coke ovens, shaft furnaces, rotary kilns, cupolas, melting furnaces and waste gasification and melting equipment, and other processing equipment such as general garbage and waste food residues, waste paper and waste wood, livestock dung, A method for recovering hydrogen gas generated as reducing gas by introducing waste containing hydrocarbons such as activated sludge, paper sludge, shredder scrap, waste plastic, or waste containing water and unused resources has been proposed. ing.

  Further, for example, Patent Document 2 has a gasification furnace having a region for thermally decomposing organic waste and a region for reforming generated pyrolysis gas in one container, and heats the organic waste. There has been proposed a method of gasifying organic waste by pyrolysis and reforming using a gasification apparatus in which a solid heat medium having a predetermined constant pressure molar heat capacity is filled in a region to be decomposed.

By these methods, it is possible to use so-called biomass and papermaking sludge as raw materials to obtain thermal energy and gas as resources. However, in these methods, the water content of the raw material cannot be adjusted appropriately, and the gas tightness of the reaction system cannot be maintained especially when the raw material is volatilized or thermally decomposed. There is a problem that the performance is impaired.
JP 2001-311084 A JP 2005-146056 A

  The present invention has been made in view of the background art described above, and an object of the present invention is to provide a method for efficiently and stably generating a gas that can be recovered as a fuel by effectively using waste resources.

The present invention
Waste material A containing fine dust and papermaking sludge B are mixed, and fine dust of waste material A is adsorbed and flocked by the papermaking sludge B. The present invention relates to a gasification method characterized by pyrolyzing in a non-oxidizing atmosphere and reacting the generated pyrolysis gas with steam.

  The gasification method of the present invention is a resource circulation type method that effectively uses waste resources, and by the gasification method, a gas that can be recovered as fuel can be efficiently and stably generated together with the amount of heat. Moreover, it is possible to suppress the precipitation of the pitch due to operational fluctuations.

(Embodiment)
In the gasification method of the present invention, a main raw material C in which waste material A containing fine dust and papermaking sludge B are mixed as a raw material is used, and the main raw material C is thermally decomposed in a non-oxidizing atmosphere to generate heat. React the cracked gas with steam.

  First, the raw material used for the gasification method according to the present embodiment will be described.

  The waste material A, which is one of the main raw materials C used in the present embodiment, is a wood waste such as waste wood, thinned wood, driftwood, waste split chopsticks, bark, etc., and is usually a raw material having a low water content. .

The waste material A is not particularly limited as long as it can be processed in a gasification furnace in a gasification apparatus to be described later. For example, if the shape is a plate or sheet, the area is about 4 to ²⁰ cm ² , and the thickness is If the length is about 5 to 10 mm, the bottom area is about 0.5 to ² cm ² and the length is about 20 to 100 mm. The thing of about 0.5-2 cm can be used suitably.

  As described above, when using a coarse waste material A exceeding the suitable plate-like, sheet-like, granular, or powdery dimensions, due to a decrease in workability in the raw material supply to the gasification furnace, or variations in raw material dimensions, There is a fear that it is difficult to provide a method for efficiently and stably generating a gas that can be recovered as a fuel, which is an object of the present invention.

  The waste material A used in the present embodiment contains fine dust. The fine dust is generated when the raw wood waste is crushed into, for example, a desired shape and size that can be processed in a gasification furnace in a gasification apparatus described later. Means dust of 10 mm or less, mainly about 2 to 6 mm.

  Normally, when such fine dust is contained in the waste material, the air flow is hindered by the fine dust and the porosity decreases, and when the gas generated by the thermal decomposition of the waste material reacts with the steam, The flow is obstructed and the reaction does not proceed sufficiently. Therefore, although the fine dust can be effectively used as a part of the waste material, it must be removed in advance before the treatment in the gasification furnace, and the operation is complicated.

  However, in the present embodiment, not only the waste material A but also papermaking sludge B, which will be described later, is mixed as the main raw material C, so the fine dust of the waste material A is adsorbed by the papermaking sludge B to be flocked and flocked. The dust adheres to the waste material A, and the fine dust that obstructs the air flow during the thermal decomposition is remarkably reduced, and the steam flow is not hindered later. Therefore, it is not necessary to remove the fine dust in advance as in the prior art, and the waste material A containing the fine dust can be effectively used for all, and during the pyrolysis of the raw material and the reaction between the pyrolysis gas and steam. Operation is not complicated.

  When the amount of fine dust contained in the waste material A is too large, the amount of fine dust that is not sufficiently adsorbed by the papermaking sludge B and remains in the pyrolysis without being flocked increases. Since there exists a possibility, it is preferable that fine dust is contained in the waste material A in the quantity of 15 mass% or less, Furthermore, 10 mass% or less. Further, considering the work when crushing the raw wood waste into a desired shape and size that can be processed in a gasification furnace in a gasification apparatus to be described later, About 3% by mass or more is contained.

  In addition, when the fine dust contained in the waste material A exceeds 15% by mass, as described above, it is not sufficiently adsorbed by the papermaking sludge B and remains in the pyrolysis state without being flocked. For this reason, the blockage of the raw material is increased in the gasification furnace, and there is a possibility that the gas that can be recovered as fuel, which is the subject of the present invention, cannot be efficiently and stably generated.

  As described above, the waste material A is usually a raw material having a low moisture content, and the moisture content is preferably about 20% by mass or more and about 25% by mass or less, although it varies depending on the shape.

  In addition, in this specification, a moisture content means the value measured based on the method as described in JISZ7302-3 "Waste solidified fuel-Part 3: Water test method."

  In the present embodiment, as the waste material A, for example, a material having a low water content as described above is used, and, as will be described later, appropriate retained moisture is required for pyrolyzing the waste material A and the papermaking sludge B. Therefore, the waste material A may not be subjected to a drying process in advance.

  The papermaking sludge B, which is another main raw material C used in the present embodiment, is, for example, generated in a deinking treatment process for producing deinked wastepaper pulp from wastepaper, such as a wastepaper recycling process. Deinking sludge containing organic substances such as pulp fibers and inorganic substances such as porous fillers and pigments, so-called calcium carbonate, kaolin, talc, titanium dioxide, silica, alumina, etc. Waste from the papermaking process containing organic and inorganic substances, such as industrial wastewater sludge collected and treated with wastewater sludge, and surplus sludge sludge in microbial treatment in the papermaking process, and usually a raw material with a high water content.

  Waste from the papermaking process that contains organic and inorganic substances, such as industrial wastewater sludge with a high water content and surplus sludge sludge from microbial treatment in the papermaking process, can easily contain moisture even if it is supplied to the gasifier. Since it does not disperse, it becomes possible to appropriately adjust the moisture in the gasifier by combining with wood waste with low moisture content, and it becomes possible to increase the gas tightness in the gasifier, so gas The production efficiency and stability of can be improved.

  In the gasification method according to the present embodiment, together with the waste material A containing fine dust, it is one of the major features that papermaking sludge B is used as a raw material having a high moisture content and a high moisture retention capability. By using the waste material A containing fine dust and the papermaking sludge B in this way, when pyrolyzing in a non-oxidizing atmosphere, for example, when the waste material A is used alone as a raw material, moisture is contained in the system. Gasification can proceed efficiently and stably without replenishing. In addition, as described above, fine dust contained in the waste material A is adsorbed and flocked by the papermaking sludge B, and the flocked dust adheres to the waste material A, and the fine dust that inhibits the flow of air during thermal decomposition. Dust is significantly reduced and the steam flow is not hindered later. Therefore, it is not necessary to remove the fine dust in advance as in the prior art, and the waste material A containing the fine dust can be effectively used for all, and during the pyrolysis of the raw material and the reaction between the pyrolysis gas and steam. Operation is not complicated.

  As described above, the papermaking sludge B is a raw material that usually has a high water content, and varies slightly depending on the type, but the water content is preferably about 40% by mass or more and about 70% by mass or less, and 50% by mass. More preferably, it is about from about% to about 70% by mass.

  In order to make the water content of the papermaking sludge B exceed 70% by mass, further water must be added to the papermaking sludge B. If the water content is too high, the temperature in the gasification furnace decreases and the gasification furnace Water leakage occurs during transport, which may cause deterioration of workability. Further, when the water content of the papermaking sludge B is less than 40% by mass, the fine dust that is an obstacle to the efficient and stable generation of the recoverable gas, which is the subject of the present invention, is attached to the waste material A. May be difficult and may not solve the problem.

  In the gasification method according to the present embodiment, first, a waste material A containing fine dust and a papermaking sludge B are mixed and mixed so that the mass ratio of both is included in a specific range (main raw material) C), and the main raw material C is pyrolyzed in a non-oxidizing atmosphere in a gasification furnace in the gasifier.

  There are no particular limitations on the specifications of the gasifier and the gasifier provided therein, for example, the main raw material C can be pyrolyzed, and the pyrolysis gas generated by the pyrolysis can be reacted with steam If it is.

  Examples of the gasification furnace include an updraft gasification furnace. The updraft gasification furnace forms approximately four reaction layers of an ashing layer, a char layer, a volatilization / pyrolysis layer, and an unreacted raw material layer from the lower layer to the upper layer. It consists of a kind of reaction tower which gasifies the raw material with the superheated steam. In such an updraft gasification furnace, a combustion reaction occurs in the lower part of the char layer due to the superheated steam supplied from the lower layer of the furnace, thereby causing an endothermic reaction such as a water gasification reaction and a generating furnace gasification reaction in the upper part of the char layer. Progresses. Therefore, the volatilization / pyrolysis layer needs to exhibit a layer structure in which the gas flow from the lower part maintains an appropriate hermeticity in order to maintain the reaction of generating CO or H2 as fuel gas. . In order to appropriately maintain the airtightness in the volatile / thermal decomposition layer, the reaction system may be adjusted so as to have appropriate retained moisture. If the retained moisture is insufficient or conversely excessive, the gas generation efficiency and generation stability are impaired.

  In the gasification method according to the present embodiment, as described above, not only the waste material A having a relatively low water content, which is conventionally used as a raw material for gasification, but also porous fillers and pigments in its constituent components. Since a papermaking sludge B having a relatively high water content is used in combination, an appropriate retained moisture is imparted to the reaction system by the moisture retained in the porous filler or pigment that does not volatilize easily. Therefore, when pyrolyzing in a non-oxidizing atmosphere, for example, when the waste material A is used alone as a raw material, it is possible to maintain airtightness in the volatile / pyrolytic layer without separately supplying water to the system. The gas generation efficiency and generation stability are remarkably improved.

  When mixing the waste material A containing fine dust and the papermaking sludge B, if the papermaking sludge B is too much relative to the waste material A, the moisture of the main raw material C may be excessive and the gas temperature may decrease. The content ratio of the papermaking sludge B in the main raw material C is preferably adjusted so that the solid content is 30% by mass or less, and further 25% by mass or less. On the contrary, if the papermaking sludge B is too small relative to the waste material A, the water content of the main raw material C becomes too low and the gas temperature may rise. Therefore, the content ratio of the papermaking sludge B in the main raw material C is solid. It is preferable to adjust so that it may become 5 mass% or more in a minute, and also 10 mass% or more. Thus, it is preferable to appropriately adjust the mass ratio between the two so that the water content of the main raw material C becomes an appropriate amount.

  If the content of the papermaking sludge B in the main raw material C exceeds 30% by mass, the gasification reaction is likely to be hindered due to the influence of the papermaking sludge B originally containing a large amount of ash (inorganic fine particles). When the content ratio of the papermaking sludge B in the main raw material C is less than 5% by mass, a problem that the water retention due to the high water content and the function of fixing the fine dust to the waste material A, which the papermaking sludge B has, is likely to occur. Therefore, there is a risk that it is difficult to efficiently and stably generate a gas that can be effectively used as a problem and is recovered as fuel, which is a problem of the present invention.

  Further, as described above, for example, the water content of the waste material A containing fine dust is about 20 to 25% by mass, and the water content of the papermaking sludge B is about 40 to 70% by mass. The moisture content of C is about 45% by mass or more and about 55% by mass or less in order to keep gas tightness in the volatile / thermal decomposition layer moderately and to improve gas generation efficiency and generation stability. It is preferable to adjust so that.

  If the water content of the main raw material C is less than 45% by mass, insufficient supply of moisture in the gasification furnace tends to occur, and conversely, if it exceeds 55% by mass, the problem of reduced workability tends to occur. There is a possibility that it is difficult to efficiently and stably generate a gas that can be recovered as a fuel by effectively using waste resources, which is a problem.

  The heating temperature when pyrolyzing the main raw material C in which the waste material A containing fine dust and the papermaking sludge B are mixed is almost complete, and a sufficient amount of pyrolytic gas is generated. For example, the temperature is preferably 1000 ° C. or higher, and more preferably about 1200 ° C. If the heating temperature is lower than 1000 ° C., the main raw material C may not be sufficiently thermally decomposed. On the other hand, if the heating temperature exceeds 1200 ° C., the pyrolysis gas itself may be burned by itself, which is not preferable.

  As the heating means at the time of the pyrolysis, a gas such as propane gas is used at the time of ignition.

  The pressure at which the main raw material C is pyrolyzed may be any pressure as long as the pyrolysis reaction of the main raw material C is almost completed and a sufficient amount of pyrolysis gas can be generated. Is not to be done.

  The main raw material C is thermally decomposed in a non-oxidizing atmosphere. Examples of the non-oxidizing atmosphere include a mixed gas of water vapor and air, and an atmosphere of an inert gas such as nitrogen gas or helium gas. Further, the time for subjecting the main raw material C to pyrolysis is not particularly limited as long as the pyrolysis reaction is almost completed and a sufficient amount of pyrolysis gas can be generated.

Next, the pyrolysis gas generated by pyrolysis as described above can be reacted with steam to recover, for example, a fuel gas containing a large amount of CO, H _{2 and the} like.

  When the pyrolysis gas and steam are reacted, for example, a mixed gas in which air and water vapor are mixed may be supplied by blowing from the lower part of the gasification furnace. When the pyrolysis gas is generated, by adjusting the water content of the main raw material C in which the waste material A containing fine dust and the papermaking sludge B are mixed, for example, within the above range, It is also possible to use water as steam.

  The amount of steam supplied to the pyrolysis gas varies depending on, for example, the types of the waste material A and paper sludge B, which are raw materials, the properties of the target fuel gas, etc., and cannot be determined unconditionally. The fuel gas may be adjusted so that it proceeds and a fuel gas having a sufficient amount and a desired component is obtained.

  The reaction temperature at the time of reacting the pyrolysis gas and steam is not particularly limited as long as the reaction of both ends and a fuel gas having a sufficient amount and a desired component can be obtained. is not.

  Further, the pressure and time for reacting the pyrolysis gas and steam may be any pressure at which the reaction between the two ends and a fuel gas having a sufficient amount and a desired component can be obtained. It is not particularly limited.

The fuel gas thus obtained contains a large amount of, for example, CO, H _{2 and the} like, and can be appropriately recovered by purification, concentration, etc., respectively, by a usual method.

As described above, according to the gasification method of the present invention, it is possible to efficiently and stably recover the fuel gas such as CO and H ₂ together with the amount of heat by effectively circulating and utilizing the waste resources, and further operating. It is also possible to suppress the precipitation of the pitch due to the fluctuation.

  In the preferred gasification method of the present invention, the waste material is crushed into a predetermined shape, and the waste A raw material containing fine dust generated by the smashing is transported to a gasifier raw material pit by a truck. It is adjusted by stirring and water application so that the moisture in the raw material pit is constant. The main raw material C is constituted by further adding a papermaking sludge B having a predetermined moisture content to the waste A raw material in the raw material pit, and then it is put into the gasification furnace by a conveying means such as a screw conveyor. The screw conveyor is easy to apply moisture in the middle, and is a useful means for maintaining the main ingredient C having a dry taste at a constant moisture.

  The fuel gas generated in the gasifier contains a large amount of tar and moisture. When supplying fuel gas to facilities that are useful as fuel gas equipment, such as kilns, the temperature is lowered during the supply. The tar content is deposited on the pipe, which may cause problems such as dirt and clogging of the piping and energy loss due to moisture contained therein. Therefore, the fuel gas generated in the gasification furnace is preliminarily about 30 ° C. in the cooler. It is preferable to cool to the vicinity and separate the tar content and moisture.

  The fuel gas obtained by separating the tar content and the moisture as described above can be used effectively in a combustion facility such as a kiln, for example, in a mixed combustion burner of heavy oil and gas, etc. It can also be used as a power source.

  Next, the gasification method of the present invention will be described in more detail based on the following examples, but the present invention is not limited to these examples.

Examples 1-5 and Comparative Examples 1-2
Waste materials A and papermaking sludge B containing fine dust shown below were mixed in the combinations shown in Table 1 below to prepare a mixed raw material (main raw material C). The main raw material C is an updraft gasification furnace in a gasifier (reaction of four layers consisting of an ashing layer, a char layer, a volatilization / thermal decomposition layer, and an unreacted raw material layer from the lower layer to the upper layer) Gasification furnace equipped with a layer) and pyrolyzed in a mixed gas atmosphere of water vapor and air to generate pyrolysis gas. In this thermal decomposition, propane gas was used at the time of ignition, and after that, the waste material A self-combusted and the thermal decomposition proceeded.

(Waste material A)
A-1: Plate-shaped / rod-shaped waste wood mixed material (mixed material in which the following A-2 and A-3 are mixed in substantially the same amount, moisture content: about 22% by mass,
Fine powder dust (particle size: about 4 mm) content: about 7% by mass)
A-2: Plate-like waste wood (area: about 10 cm ² , thickness: about 5 mm, moisture content: about 20% by mass,
Fine powder dust (particle size: about 2 mm) content: about 7% by mass)
A-3: Rod-like waste wood (bottom area: about 1 cm ² , length: about 50 mm, moisture content: about 25% by mass,
Fine powder dust (particle size: about 6 mm) content: about 7% by mass)

(Paper sludge B)
B-1: Deinking / drainage sludge mixed material (mixed material in which the following B-2 and B-3 are mixed in substantially the same amount, water content: about 65% by mass)
B-2: Deinking sludge (In the flotation process of the deinking process to manufacture deinked wastepaper pulp from wastepaper
Generated, moisture content: about 60% by mass)
B-3: Wastewater sludge (A collection of various wastewater sludge from the papermaking process,
(Moisture content: about 70% by mass)

(Combination of main raw materials C)

  Next, mixed air in which air and water vapor were mixed was blown from the lower part of the gasification furnace, and the generated pyrolysis gas and steam were reacted to perform gasification.

  As a result, in Examples 1 to 5, it was possible to obtain a fuel mixed gas in an efficient and stable operation state. However, in Comparative Example 1, not only the gasification reaction in the gasification furnace does not proceed, but also the fuel mixture gas cannot be used due to unstable operation. In Comparative Example 2, the gasification reaction in the gasification furnace hardly progressed.

  In each of the examples and comparative examples, a series of operations in which one set from the preparation of the raw material to obtaining the fuel mixed gas was performed was performed in three sets.

  Stable operation refers to an operation state in which clogging of raw materials and temperature change in the gasification furnace are small and a fuel mixed gas having a high calorific value can be generated. On the other hand, unstable operation refers to an operation state in which there are large fluctuations in the clogging of raw materials, temperature changes in the gasification furnace, and the heat generation amount of the fuel gas mixture, resulting in operation instability in the combustion facility that effectively uses the fuel gas mixture Say.

  When the heavy oil burner of the calcification combustion kiln was replaced with a heavy oil / gas mixed burner using the obtained fuel mixed gas, the reduction rate of heavy oil usage on a calorific basis was calculated and shown in Table 1. Thus, in the fuel mixed gas of Examples 1-5, the amount of heavy oil used could be reduced by 2-3%. On the other hand, gasification was impossible under the conditions of Comparative Examples 1 and 2.

  The gasification method of the present invention is a resource circulation method that effectively uses waste resources, and can be widely used in fields such as the construction industry, environmental business, and fuel supply development business.

Claims (5)

Waste material A containing fine dust and papermaking sludge B are mixed, and fine dust of waste material A is adsorbed and flocked by the papermaking sludge B. A gasification method characterized by pyrolyzing in a non-oxidizing atmosphere and reacting the generated pyrolysis gas with steam.   The gasification method according to claim 1, wherein 3 to 15 mass% of fine dust is contained in the waste material A.   The gasification method of Claim 1 or 2 adjusted so that the moisture content of the main raw material C may be 45-55 mass%.   The gasification method according to any one of claims 1 to 3, wherein a waste material A having a moisture content of 20 to 25% by mass and a papermaking sludge B having a moisture content of 40 to 70% by mass are mixed.   The gasification method as described in any one of Claims 1-4 adjusted so that the content rate of the papermaking sludge B in the main raw material C may be 5-30 mass% by solid content.