JP4885254B2 - Biomass gasification system - Google Patents

Description

  The present invention relates to a biomass gasification system capable of efficiently using biomass and performing clean and highly efficient gasification.

  In general, biomass refers to organisms (such as agricultural products or by-products, wood, plants, etc.) that can be used as energy sources or industrial raw materials, and are produced by the action of solar energy, air, water, soil, etc. Is infinitely reproducible.

By using the biomass, fuel and methanol can be produced. Further, since biomass as waste can be treated, it is useful for environmental purification, and newly produced biomass is also grown by CO ₂ fixation by photosynthesis, so that it does not increase atmospheric CO ₂ .

  For example, fermentation methods and hydrothermal decomposition methods have been proposed as conventional methods for converting biomass to alcohol. However, the former fermentation method uses only sugar and starch as raw materials and takes a long time for fermentation. In addition, it is necessary to install a large-capacity fermentation tank, and the latter hydrothermal decomposition method has problems of high temperature, high pressure, and low yield. In addition, there is a problem that a large amount of biomass residues are supplied together and the utilization rate of biomass is low.

On the other hand, in the case of biomass gasification, for example, a gasification furnace such as a fixed bed or a fluidized bed was used, but only the surface of the biomass particles reacted and did not react uniformly to the inside, There is a problem that tar is generated and the generated gasification gas is not a raw material for efficient methanol synthesis because it has a small amount of H ₂ and CO.

  Further, there is a problem in that the generated tar adheres to the inside of the furnace and also adheres to equipment or the like installed on the downstream side, resulting in malfunctions.

  Therefore, in the past, it was decided to burn at a high temperature by supplying a large amount of oxygen, but in this case, a high temperature region partially exceeding 1200 ° C. was formed, and the biomass itself lacked oxygen without becoming a gas. There is a problem that it burns in a state and becomes sooted.

JP-A-5-287282 JP-A-6-0099967 Japanese Patent Laid-Open No. 7-041767

  In view of the above problems, an object of the present invention is to provide a biomass gasification system that can perform clean and highly efficient gasification and achieve complete gasification of biomass.

  A first invention for solving the above-described problem is a biomass gasification system including a biomass gasification system including a biomass gasification furnace that uses biomass as a raw material and obtains a product gas by gasification using oxygen and steam as a gasification agent. A dust removing means for removing dust in the produced gas produced by a furnace, and heating the produced gas by passing the produced gas disposed inside the biomass gasification furnace and removed by the dust removing means. It is a biomass gasification system characterized by having piping to perform.

According to a second invention, in the first invention, there is provided a steam reforming means interposed in a part of the pipe to reform hydrocarbons in the product gas into CO and H _2. This is a biomass gasification system.

  A third invention is the biomass gasification system according to the first or second invention, wherein water vapor is supplied to the product gas that is removed by the dust removing means and passes through the pipe.

A fourth invention, in any one invention of the first to third, and CO ₂ removal unit for removing CO ₂ in the product gas which has passed through the pipe, the CO ₂ is removed by the CO ₂ remover A biomass gasification system comprising a methanol synthesizer for synthesizing methanol from H ₂ and CO in the product gas.

  According to the biomass gasification system of the present invention, clean and highly efficient gasification can be performed and biomass can be completely gasified.

It is the schematic of the biomass gasification furnace concerning 1st Embodiment. It is the schematic of the other biomass gasification furnace of 1st Embodiment. It is the schematic of the other biomass gasification furnace of 1st Embodiment. It is the schematic of the biomass gasification furnace concerning 2nd Embodiment. It is a related figure of the amount of steam input using the biomass gasification furnace concerning 2nd Embodiment, the amount of hydrogen generation, and the amount of methane generation. It is the schematic of the methanol synthesis system using the biomass gasification furnace concerning 3rd Embodiment. It is the schematic of the biomass gasification furnace concerning 4th Embodiment. It is the schematic of the other biomass gasification furnace of 4th Embodiment. It is the schematic of the methanol synthesis | combination system using the biomass gasification furnace concerning 5th Embodiment. It is the schematic of the methanol synthesis system using the biomass gasification furnace concerning 6th Embodiment.

    Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

[First Embodiment]
A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic view of a biomass gasification furnace according to the present embodiment.

  As shown in FIG. 1, a biomass gasification furnace 10 according to the present embodiment obtains a product gas 24 by a partial oxidation gasification reaction using biomass 13 as a raw material and oxygen and steam as gasification agents. The biomass supply means 14 for supplying biomass 13 pulverized to a predetermined particle size into the gasification furnace main body 11 and the oxygen or air 15 at the top 12 of the gasification furnace main body 11 made of a refractory material Are provided with combustion oxidant supply means 16 for supplying the steam and steam supply means 18 for supplying the steam 17 to the inside of the gasification furnace main body 11.

  In the present embodiment, the steam supply means 18 includes a first steam supply means 18A supplied from the top 12 of the gasifier main body 11 and a second steam supply means supplied from a substantially central portion of the gasifier main body 11. 18B, a high-temperature reaction field 19A by a combustion reaction at a location where the biomass 13 is supplied, and a gasification reaction field (or a thermal decomposition reaction field where the oxidant is consumed and the biomass 13 is decomposed by heat). The steam 17 is supplied separately to 19B.

  Further, an ash reservoir 22 for the ash 21 in the biomass 13 is formed at the lower part of the gasifier main body 11.

  In addition, a gas discharge part 23 is provided on the lower side of the side wall of the gasification furnace main body 11, and the produced gas 24 generated by gasification of the biomass 13 is sent out to the downstream side.

  Here, as the biomass 13 supplied into the gasification furnace main body 11, it is preferable to supply pulverized and dried biomass produced or discarded as necessary. Biomass in the present invention refers to biological resources that can be used as an energy source or industrial raw material (for example, agricultural products or by-products, wood, plants, etc.), and examples include sweet sorghum, napiergrass, spirulina, and the like. it can.

  In the present invention, the average particle diameter (D) of the pulverized product of biomass 13 is preferably 0.05 mm ≦ D ≦ 5 mm. This is because if the average particle size (D) is 0.05 mm or less, the pulverization efficiency of biomass deteriorates, which is not preferable. On the other hand, when the average particle size (D) exceeds 5 mm, the biomass is not combusted well, the reaction is not promoted, and high-efficiency gasification becomes difficult.

  Here, in the embodiment shown in FIG. 1, the combustion oxidant 15 is supplied from the top 12 of the gasification furnace body 11 through the combustion oxidant supply means 16 and the steam 17 is supplied to the first steam supply means at the same location. While supplying through 18A, the water vapor | steam 17 is also supplied through the 2nd water vapor | steam supply means 18B also from the side surface center vicinity side of the gasification furnace main body 11, and it is trying to improve gasification efficiency.

  The supply of the water vapor 17 is divided in this way because the temperature of the water vapor is about 400 to 600 ° C. even when it is normally heated. Therefore, when it is supplied to the high temperature reaction field 19A, it acts as a coolant. This is because the high temperature reaction field 19A is not sufficiently formed.

Therefore, when supplying the gasification reaction field 19B with a small amount of oxygen after the high temperature reaction field 19A is sufficiently formed, the water vapor 17 is exposed to the atmosphere and becomes a high temperature (about 900 to 1200 ° C.). The high-temperature steam 17 causes a CO shift reaction of CO + H ₂ O ← → CO ₂ + H ₂ to proceed to the right side, and the H ₂ concentration can be improved. CO / H ₂ suitable as a methanol production raw material to be described later A product gas 24 having a composition with a molar ratio of approximately ½ can be obtained.

  Moreover, in order to adjust the temperature in the gasifier main body 11 and the composition of the product gas 24, the supply ratio of the water vapor 17 in the first water vapor supply means 18A and the second water vapor supply means 18B can be adjusted.

  Furthermore, in the present invention, the steam 17 supplied to the biomass gasification furnace 10 is supplied in two stages, but the present invention is not limited to this, and as shown in FIG. You may make it supply supply of the water vapor | steam 17 supplied to the field (or also called thermal decomposition reaction field) 19B from several places using supply means, such as a some supply nozzle. Moreover, you may make it supply the water vapor | steam 17 from several places not only in a perpendicular direction but in the circumferential direction.

  Further, as shown in FIG. 3, the water vapor 17 is supplied from the top 12 of the gasification furnace main body 11 to the gasification reaction field 19 </ b> B of the gasification furnace main body 11 by the water vapor supply means 18 only. You may do it.

Here, the input ratio of the combustion oxidant 15 and the total amount of the water vapor 17 is such that the molar ratio of oxygen [O ₂ ] / carbon [C] is in the range of 0.1 ≦ O ₂ / C, preferably 0.1. ≦ O ₂ /C<1.0 (particularly preferably 0.2 ≦ O ₂ /C<0.5) and the molar ratio of water vapor [H ₂ O] / carbon [C] is 1 By making the range ≦ H ₂ O / C (particularly preferably, the range 2 ≦ H ₂ O / C ≦ 6), clean gasification with less generation of tar and soot can be achieved.

This is because when the amount falls within the above range, the pyrolysis gasification is improved by supplying water vapor and oxygen, and the amount of H ₂ and CO in the product gas 24 can be improved.

  In order to gasify the biomass 13, it is preferable to set the internal temperature of the gasification furnace body 11 to gasification conditions of 700 to 1200 ° C. This is because if the internal temperature of the gasification furnace main body 11 is less than 700 ° C., the thermal decomposition of the biomass 13 is not good and is not preferable, while if it exceeds 1200 ° C., soot is generated by the combustion of the biomass 13 itself. It is generated and is not preferable.

  Moreover, it is preferable that the internal pressure of the gasification furnace main body 11 shall be 1-30 atmospheres. This is because when it is directly linked to the synthesis of methanol (or dimethyl ether), the vicinity of 80 atm is preferable, but the gasification furnace main body 11 needs to have a pressure-resistant structure, which is not preferable because of high manufacturing costs. In addition, about 30 atmospheres, a superficial velocity becomes low and an apparatus can be made compact, and it is preferable.

  The superficial velocity inside the gasification furnace main body 11 is preferably set to gasification conditions of 0.1 to 5 m / s. If the superficial velocity is 0.1 m / s or less, the residence time inside the gasification furnace main body 11 is long and excessive combustion is not preferable. On the other hand, if it exceeds 5 m / s, combustion / pyrolysis is completely completed. This is because good gasification cannot be achieved.

According to the biomass gasification furnace 10 of the present invention, the biomass 13 is efficiently gasified by partial oxidation, the CO shift reaction proceeds to the H ₂ production side, and the produced gas contains a large amount of H ₂ necessary for methanol synthesis described later. 24 can be obtained.

  The obtained product gas 24 can be directly used as a fuel gas for a gas turbine after being purified by a gas purification means.

Further, by adjusting the composition of H ₂ and CO gas in the product gas 24, it can be used as a gas for producing methanol (or dimethyl ether).

[Second Embodiment]
FIG. 4 is a schematic view of a gasification furnace according to the second embodiment of the present invention.
In the present embodiment, the first water vapor supply means 18A for supplying the water vapor 17 is provided on the top portion 12 of the gasification furnace main body 11, and the second water vapor supply means 18B is provided on the side surface of the gasification furnace main body 11. Is. The steam 17 from the first steam supply means 18A is supplied into the high temperature reaction field 19A, and the steam 17 from the second steam supply means 18B is supplied into the gasification reaction field 19B.

Here, in the case of H ₂ O / C = 2.5, the ratio of the input amount of the steam 17 from the first steam supply unit 18A and the input amount of the steam 17 from the second steam supply unit 18B is the first steam. When the input amount of the water vapor 17 from the supply unit 18A is 10 to 90%, the ratio of the input amount of the water vapor 17 from the second water vapor supply unit 18B may be 90 to 10%. In particular, when the ratio of the amount of water vapor 17 supplied from the second water vapor supply means 18B is in the range of 20 to 60%, particularly preferably in the range of 40 to 60%, as shown in FIG. ₂ ) It is preferable because the amount of methane (CH ₄ ) generated decreases as the amount generated increases. In addition, when the ratio of the input amount of the water vapor 17 from the second water vapor supply means 18B exceeds 70%, the temperature of the high temperature reaction field 19A increases (about 1400 ° C. or more), and heat loss increases. The furnace manufacturing cost is undesirably high.

As described above, in order to synthesize methanol from CO and H ₂ , it is necessary to improve the hydrogen concentration, but this can be achieved by setting the input amount of the water vapor 17 from the second water vapor supply means 18B to a predetermined ratio. Can be achieved.

  In the present embodiment, the introduction of the water vapor 17 from the second water vapor supply means 18B causes the water vapor 17 to flow in the tangential direction from four locations in the circumferential direction so as to improve the mixing efficiency. Further, the blowing of the water vapor 17 from the second water vapor supply means 18B into the gasifier main body 11 is supplied so as to blow up the water vapor 17 from the lower side to the upper side of the vertical axis. The mixing ratio may be improved.

[Third Embodiment]
Hereinafter, a system 100 that uses the obtained product gas 24 for methanol synthesis will be described with reference to FIG.

As shown in FIG. 6, a biomass methanol synthesis system 100 that synthesizes methanol using a product gas 24 produced by the biomass gasification furnace 10 generates dust in the product gas 24 generated in the biomass gasification furnace 10. The dust collector 101 to be removed, the purification device 102 for purifying the product gas 24 after dust collection, the CO shift reaction device 104 for adjusting the composition of H ₂ and CO gas in the product gas 24, and the pressure of the product gas 24 Booster device 105 for improving the efficiency, methanol production device 106 for producing methanol (CH ₃ OH) from H ₂ and CO in product gas 24, and gas-liquid separation device 109 for separating exhaust gas 107 and methanol 108 It has.

Biomass 13 supplied into the gasification furnace main body 11 of the biomass gasification furnace 10 is partially burned by the combustion oxidant 15 and is preferably produced as a raw material for producing the methanol 108 by setting the above-described predetermined furnace conditions. A gas 24 is obtained. The generated gas 24 generated here is then dust-removed by the dust collector 101, then the H ₂ amount is increased by the CO shift device 104, and the pressure is increased to the synthesis pressure of the methanol 108 by the booster device 105. 106, where methanol 108 is produced. Thereafter, the methanol 108 and the exhaust gas 107 are separated.

Here, since CH ₄ which is a combustible gas remains in the exhaust gas 107, it is supplied again to the gasification furnace main body 11 or reused as a heat source (fuel) for preheating the water vapor 17. It may be.

In order to improve the recovery rate of methanol 108, excess CO ₂ is removed by a CO ₂ removal device (decarbonation device) 110 that removes CO ₂ such as an amine-based wet CO ₂ removal device at the final stage of the system. It may be provided upstream of the booster device 105 to remove excess CO ₂ .

As a result, the production gas 24 of the raw material of the methanol 108 supplied to the methanol synthesizer 106 can be made to have a molar ratio composition of [CO] / [H ₂ ] = _1/2 by removing excess CO _2. The synthesis of methanol 108 proceeds efficiently, and the supplied biomass 13 can be efficiently synthesized into methanol 108.

[Fourth Embodiment]
A fourth embodiment of the present invention will be described with reference to FIG. In addition, about the same member as the gasification furnace shown in FIG. 1, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  The biomass gasification furnace 30 according to the present embodiment has a constricted part 32 formed in the central part of the gasification furnace main body 31, and the interior is divided into a first chamber 31A and a second chamber 31B in the vertical axis direction. A biomass supply means 14 for supplying biomass 13 to the lower side, a combustion oxidant supply means 16 for supplying oxidant 15, and a steam supply means 18 for supplying water vapor 17 are provided. Also in the present embodiment, the water vapor 17 is supplied not only from the first chamber 31A but also from the second water vapor supply means 18B to the second chamber 31B.

The supply of the water vapor 17 is divided in this way because the temperature of the water vapor is about 400 to 600 ° C. even when it is normally heated. Therefore, when it is supplied to the high temperature reaction field 19A, it acts as a coolant. This is due to insufficient oxidation and thermal decomposition reactions. Therefore, when supplying the gasification reaction field (thermal decomposition reaction field) 19B with a small amount of oxygen after the high-temperature reaction field 19A is sufficiently formed, the water vapor 17 is exposed to the atmosphere and is heated to a high temperature (about 900 to CO shift reaction of CO + H ₂ O ← → CO ₂ + H ₂ proceeds to the right side, the H ₂ concentration can be improved, and a CO / H ₂ molar ratio suitable as a raw material for producing methanol 108 Can be obtained.

  The supply method of the biomass 13 is not limited to what is supplied from the lower side like this Embodiment. In addition, by making the flow of the product gas 24 upward as in the present embodiment, the high-temperature gas flows upward, so that the gas flow in the gasification furnace main body 11 becomes uniform, and the gasification reaction proceeds efficiently. Therefore, it is preferable.

  Moreover, also in the biomass gasification furnace 10 that supplies the biomass 13 according to the first embodiment shown in FIGS. 1 to 3 from above, a constricted portion is formed in the gasification furnace main body 11 as in this embodiment. In this way, the high temperature reaction field 19A and the gasification reaction field 19B may be clarified.

  Further, as shown in FIG. 8, the steam 17 is not supplied to the first chamber 31A of the gasification furnace main body 31 having the constricted portion 32, but only to the gasification reaction field 19B in the second chamber 31B. The water vapor 17 may be supplied from the means 18.

[Fifth Embodiment]
A fifth embodiment of the present invention will be described with reference to FIG. The same members as those in the gasification furnace shown in FIG. 1 and the gasification system shown in FIG.

The biomass gasification system 120 according to the present embodiment includes a biomass gasification furnace 10 that gasifies biomass 13 and dust collection such as a scrubber that removes soot and the like in the generated gas 24 generated in the gasification furnace 10. A device 103, a pipe 121 for allowing the product gas 24 after dust collection to pass through the gasification furnace 10 again and heating the product gas 24 again, and a booster device 105 for increasing the pressure of the product gas 24 after heating, For example, a CO ₂ removal device 110 that removes CO ₂ such as an amine-based wet CO ₂ removal device, and a methanol production device 106 that produces methanol (CH ₃ OH) 108 from H ₂ and CO in the product gas 24 And a gas-liquid separation device 109 that separates the exhaust gas 107 into methanol 108.

According to the present embodiment, after dust is removed from the generated gas 24 by the dust removing device 103, the water vapor 17 is supplied to pass through the pipe 121 disposed in the gasification furnace 10. The gas 24 is heated again, and the CO shift reaction of CO + H ₂ O ← → CO ₂ + H ₂ proceeds to the right side, and the H ₂ concentration can be improved.

[Sixth Embodiment]
A sixth embodiment will be described with reference to FIG. The same members as those in the gasification system shown in FIG.

The biomass gasification system 130 according to the present embodiment is configured such that a catalyst device 131 that is a steam reforming means is interposed in a pipe 121 disposed in the gasification furnace main body. The catalyst device 131 is formed by, for example, filling a reforming catalyst 132 such as a Ni-based catalyst, etc., and by the reforming effect of the catalyst 132, a hydrocarbon-based material such as CH ₄ in the product gas 24, By steam reforming in the presence of the water vapor 17 and the nickel catalyst, CO and H ₂ can be obtained at a high temperature (preferably 900 ° C. ± 100 ° C.). As described above, H ₂ and CO generated by the steam reforming are raw materials for synthesizing the methanol 108.

As a result, product gas 24 of the raw material of methanol 108 to be supplied to the methanol synthesis unit 106, the molar ratio of H ₂ rich CO / H ₂ with excess CO ₂ is removed and the gas composition of 1/2 Therefore, the synthesis efficiency of methanol 108 is improved, and the supplied biomass 13 can be efficiently synthesized into methanol 108.

  In the fifth and sixth embodiments, the gasification furnace that introduces the water vapor 17 in multiple stages is not used. However, even if the gasification furnace shown in FIGS. It goes without saying that 108 can be synthesized.

10 Biomass gasifier 11 Gasifier body (furnace body)
12 Top 13 Biomass 14 Biomass supply means 15 Combustion oxidant 16 Combustion oxidant supply means 17 Steam 18 Steam supply means 18A First steam supply means 18B Second steam supply means 19A High temperature reaction field 19B Gasification reaction field (thermal decomposition) Reaction field)
21 Ash 22 Ash Reservoir 24 Generated Gas 100 Biomass Gasification System 101 Dust Collector 102 Purifier 103 Scrubber 104 CO Shift Reactor 105 Booster Device 106 Methanol Production Device 107 Exhaust Gas 108 Methanol 109 Gas-Liquid Separator 110 Decarbonizer 120 Biomass Gasification system 121 Piping 131 Catalytic device 132 Catalyst

Claims (4)

In a biomass gasification system equipped with a biomass gasification furnace that uses biomass as a raw material and obtains product gas by gasification using oxygen and steam as gasification agents,
Dust removing means for removing dust in the produced gas produced by the biomass gasification furnace;
A biomass gasification system comprising: a pipe that is disposed inside the biomass gasification furnace and that passes through the generated gas that has been removed by the dust removing means and heats the generated gas. In claim 1,
A biomass gasification system comprising steam reforming means interposed in a part of the pipe to reform hydrocarbons in the product gas into CO and H ₂ . In claim 1 or 2,
A biomass gasification system characterized in that water vapor is supplied to the product gas that is removed by the dust removing means and passes through the pipe. In any one of Claims 1 thru | or 3,
A CO ₂ removal device that removes CO ₂ in the product gas that has passed through the pipe;
A biomass gasification system comprising: a methanol synthesizer that synthesizes methanol from H ₂ and CO in the product gas from which CO ₂ has been removed by the CO ₂ removal device.

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