JP2012201610A - Method for producing alcohol and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and stably obtain a synthesis gas having a H/CO molar ratio suitable for the synthesis of methanol even when types or properties of a raw material are changed.SOLUTION: This method for producing alcohol includes steps of: obtaining a first gas containing Hand CO by pyrolytic gasification of a solid raw material such as biomass; obtaining a second gas containing Hand CO by steam gasification of a solid raw material also such as biomass; mixing the first gas and the second gas in proportions in accordance with the respective H/CO molar ratios to obtain a synthesis gas having a desired H/CO molar ratio; and synthesizing methanol as alcohol from the synthesis gas.

Description

  The present invention relates to an alcohol production method using biomass, waste plastics, and the like as raw materials and an apparatus therefor.

The process of gasifying biomass to obtain methanol has been extensively studied. For example, in Patent Document 1, a combustion oxidant made of oxygen or a mixture of oxygen and water vapor is introduced into a gasification furnace that thermally decomposes and gasifies biomass to promote a partial oxidation reaction of biomass (H ₂ It is described that the H ₂ / CO molar ratio of the product gas (molar ratio of H _{2 to} CO) approaches 2 by promoting the production of In order to synthesize methanol from a synthesis gas composed of CO and H ₂ , the molar ratio is brought close to the stoichiometric ratio.

In the same document, CO and H ₂ are generated by a steam reforming reaction from a hydrocarbon-based material such as methane which is a by-product in the gasification furnace, and this is used as a raw material gas for methanol synthesis. Is also described. It is also generally known to adjust the H ₂ / CO molar ratio of the product gas by placing a water gas shift reactor after the biomass pyrolysis gasification reactor.

JP 2001-240878 A

In the technique of promoting the partial oxidation reaction of biomass in the gasifier, it is not always easy to adjust the H ₂ / CO molar ratio to a desired value.

In other words, if the type of biomass as a raw material is limited and its quality is stable, it is possible to determine to some extent the optimum amount of combustion oxidant to obtain a desired H ₂ / CO molar ratio by experiment. It is believed that there is. However, for example, even when sawdust is used as a raw material, the water content usually varies depending on the type of sawdust (wood) and the climate. Therefore, the H ₂ / CO molar ratio of the resulting product gas tends to deviate from the desired value. In addition, when a mixture of biomass and waste plastic is used as a raw material, particularly when the mixing ratio changes from time to time, it is difficult to set the H ₂ / CO molar ratio of the product gas to a desired value.

The same problem applies to the method of adjusting the H ₂ / CO molar ratio by the water gas shift reaction. If the type or properties of the raw material changes, it is necessary to change the reaction conditions such as the addition amount of water vapor accordingly. It is difficult to control the reaction to obtain a H ₂ / CO molar ratio of In addition, the installation of the water gas shift reactor is disadvantageous in terms of cost, and furthermore, once generated CO is converted to CO ₂ , there arises a problem that CO required for synthesis is reduced.

Therefore, an object of the present invention is to easily and stably obtain a synthesis gas having a H ₂ / CO molar ratio suitable for alcohol synthesis even when the type or properties of the raw material changes.

In order to solve the above-mentioned problems, the present invention changes the idea from the concept of adjusting the H ₂ / CO molar ratio using a conventional chemical reaction, and uses two types of gases having different H ₂ / CO molar ratios. And a method of mixing the two gases at a ratio corresponding to each H ₂ / CO molar ratio.

That is, the alcohol production method disclosed herein includes a step of obtaining a first gas containing H ₂ and CO by pyrolysis gasification of a solid first raw material containing carbon element and hydrogen element in the molecule;
A step of obtaining a second gas containing H ₂ and CO by steam gasification of a second raw material that is the same as or different from the first raw material and contains carbon element and hydrogen element in the molecule;
Mixing the first gas and the second gas at a ratio corresponding to each H ₂ / CO molar ratio to obtain a synthesis gas for alcohol production;
And a step of synthesizing alcohol from the synthesis gas.

In addition, the alcohol production apparatus disclosed herein performs the pyrolysis gasification treatment on the solid first raw material containing carbon element and hydrogen element in the molecule for obtaining the first gas containing H ₂ and CO. One reactor,
A second reaction for obtaining a second gas containing H ₂ and CO by steam gasification of a second raw material which is the same as or different from the first raw material and contains carbon element and hydrogen element in the molecule And
A third reactor for alcohol synthesis;
Synthetic gas supply means for mixing the first gas and the second gas so as to become a synthesis gas for alcohol synthesis at a ratio corresponding to each H ₂ / CO molar ratio and supplying the mixed gas to the third reactor It is characterized by having.

  The first and second raw materials include woody biomass such as sawdust, thinned wood, and other biomass (paper, livestock dung, food waste, sewage sludge, raw garbage, rice straw, straw, rice husk, resource crops, Forage crops, waste plastics, and other organic wastes can be used as long as they are solid materials containing carbon and hydrogen elements in their molecules, and different materials can be used in combination. . The first raw material and the second raw material may be the same or different.

In the pyrolysis gasification treatment of the first raw material, in principle, heat treatment is performed without adding water vapor, whereby the H ₂ / CO molar ratio is smaller than 2, and further, the H ₂ / CO molar ratio is 1 The following first gas can be obtained. The general formula of the pyrolysis gasification reaction can be expressed as follows, and may be pyrolyzed and gasified in an oxygen-free atmosphere.
_{C n H m O p + aO} 2 → bCO + cCO 2 + dH 2 + C x H y ...... (1)

In the case of biomass, if this is expressed as CH ₂ O for simplicity, the pyrolysis gasification reaction can be expressed as follows.
CH ₂ O → CO + H ₂ (2)

However, although the molar ratio of CO and H ₂ produced differs depending on the type of the first raw material and the water content of the first raw material itself, it does not add water vapor, and by-products such as C _x H _y As a result, the H ₂ / CO molar ratio of the first gas is less than 2 and further 1 or less.

In the steam gasification treatment of the second raw material, gasification is performed by adding steam, so that a _second gas having an H ₂ / CO molar ratio larger than 2 and further 4 or more can be obtained. The steam gasification reaction can be represented by the following equation (3) in the case of biomass, and can be represented by the equation (4) in the case of waste plastic. Also in this case, the H ₂ / CO molar ratio of the obtained second gas varies depending on the type of the second raw material and the water content of the first raw material itself.
CH ₂ O + H ₂ O → CO ₂ + H ₂ (3)
C _n H _{2n + 1} + nH ₂ O → nCO + (2n + 1) H ₂ (4)

The first gas and the second gas are mixed at a ratio corresponding to the H ₂ / CO molar ratio of each of the two gases so that the H ₂ / CO molar ratio is suitable for the synthesis of the alcohol to be produced. In the case of the batch type, the H ₂ / CO molar ratio of each of the obtained first gas and second gas is obtained by analysis, and both gases are mixed to obtain a synthesis gas. In the case of the continuous type, a gas analyzer for analyzing the H ₂ / CO molar ratio of the gas may be provided in the middle of the supply pipe for supplying the first gas and the second gas to the alcohol synthesis reactor. That is, in accordance with H _{2 /} CO mole ratio of two gases each obtained by analysis, so that the H _{2 /} CO molar ratio suitable for the synthesis of alcohol, may be feedback controlled supply of both gas respectively.

When synthesizing methanol as the alcohol, the first gas and the second gas may be mixed so that, for example, a synthesis gas having a H ₂ / CO molar ratio of 1.3 to 3.5 can be obtained. Good.

Therefore, according to the present invention contains a first gas containing H ₂ and CO obtained by pyrolysis gasification process of the first source, H ₂ and CO obtained by steam gasification process of the second material Unlike the case where the pyrolysis gasification reaction or water gas shift reaction is controlled, the second gas is mixed at a ratio corresponding to each H ₂ / CO molar ratio and used for the production of alcohol. A synthesis gas having a H ₂ / CO molar ratio suitable for the synthesis of alcohol can be obtained easily and stably, and a special effect of being advantageous in terms of cost and energy efficiency can be obtained.

It is a figure which shows the polypropene manufacturing system to which this invention is applied. It is a graph which shows the density | concentration of the product gas by each pyrolysis gasification process and water vapor | steam gasification process. It is a graph which shows the time-dependent change of the temperature and pressure in methanol synthesis. It is a graph which shows the amount of component gas before and behind methanol synthesis reaction.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its application, or its use.

FIG. 1 shows a system for synthesizing methanol as alcohol from a solid first raw material and a second raw material at normal temperature and pressure, each containing carbon and hydrogen elements such as biomass and waste plastic in the molecule, and further producing polypropene. The overall configuration is shown. The alcohol production method and apparatus according to the present invention are used in this system. In the figure, 1 is for obtaining a first gas containing H ₂ and CO, the first reactor a first material handling pyrolysis gasification, 2 obtain a second gas containing H ₂ and CO Therefore, a second reactor for steam gasification of the second raw material, 3 is a third reactor for methanol synthesis supplied by mixing the first gas and the second gas, 4 is methanol to propene It is the 4th reactor which produces | generates.

Each of the first and second reactors 1 and 2 is provided with a heater 11 and a temperature sensor 12. The first gas and the second gas generated in the reactors 1 and 2 are respectively stored in the first and second intermediate tanks 15 and 16 through the gas purifier 13, the heat exchanger 14 and the booster 22. The intermediate tanks 15 and 16 are mixed at a ratio corresponding to the H ₂ / CO molar ratio and supplied to the third reactor 3.

In the first reactor 1, a reaction temperature field of 400 ° C. to 1000 ° C. is formed by the combustion of the heater 11 and a part of the first raw material, and the pyrolysis gasification of the first raw material is advanced without adding water vapor. . _Thus, H 2 / CO of <2 (molar ratio), it is possible to obtain the first gas _H 2 / CO ≦ 1 (molar ratio).

In the second reactor 2, a reaction temperature field of 700 ° C. to 1100 ° C. is formed by the combustion of the heater 11 and a part of the second raw material, and the steaming of the second raw material proceeds. A water source 17 is connected to the second reactor 2 via a pump 18 for the addition of water vapor. By the addition of water vapor, the second reactor 2 can obtain a second gas with H ₂ / CO> 2 (molar ratio) and further with H ₂ / CO ≧ 4 (molar ratio). If necessary, dolomite effective for decomposition of tar as a by-product and other catalysts are added to the second reactor 2. For example, a Ni catalyst in which nickel oxide is supported on activated alumina can be used.

  The gas purifier 13 removes ash, undecomposed components, water-soluble components, surplus moisture, catalyst poisons, etc. in the product gas (first gas, second gas). In the heat exchanger 14, cooling and water vapor in the product gas are removed. The heat obtained by the heat exchange can be used for generation of water vapor added to the second reactor 2. The generated gases (first gas and second gas) that have passed through the heat exchanger 14 are respectively boosted by the booster 22 and stored in the first and second intermediate tanks 15 and 16. The pressure required for the methanol synthesis described later is obtained by this pressure increase.

The supply gas supply pipes extend from the first and second intermediate tanks 15 and 16 toward the third reactor 3, respectively, and both supply pipes are connected to the third reactor 3 as a single merge pipe. Has been. Each supply pipe is provided with a flow control valve 21, and the junction pipe is provided with an opening / closing valve 23. Thus, a gas analyzer 24 for analyzing the H ₂ / CO molar ratio of each product gas is provided in the supply pipes upstream of the intermediate tanks 15 and 16 or the flow control valve 21, and downstream of the on-off valve 23. A gas analyzer 25 for analyzing the H ₂ / CO molar ratio of the supply gas is provided in the side junction pipe.

The supply pipe, junction pipe, flow rate control valve 21 and gas analyzer 24 constitute a synthesis gas supply means for synthesizing methanol from the first gas and the second gas. That is, the H ₂ / CO molar ratio of the gas obtained in each of the first and second reactors 1 and 2 varies from time to time depending on the types and properties of the first raw material and the second raw material. On the other hand, the synthesis gas suitable for the synthesis of methanol is theoretically H ₂ / CO molar ratio = 2. Therefore, the H ₂ / CO molar ratio of each of the first gas and the second gas is analyzed by the gas analyzer 24, and the flow rate control valve 21 is feedback-controlled based on the analysis value, thereby the first gas and the second gas. Are mixed at a ratio corresponding to their H ₂ / CO molar ratio, for example, a synthesis gas having a target value of H ₂ / CO molar ratio = 1.3 to 3.5 is obtained.

The gas analyzer 25 on the downstream side of the on-off valve 23 is used for feedback correction of the opening degree of the flow control valve 21 based on the H ₂ / CO molar ratio of the synthesis gas so that the target H ₂ / CO molar ratio is obtained. Is.

  The third reactor 3 for alcohol synthesis is filled with a catalyst for methanol synthesis, and further provided with a heater 26 and a temperature sensor 27. A reaction temperature field of 180 ° C. to 300 ° C. is formed by the heater 26, and methanol is synthesized from the synthesis gas under a pressure of 3 MPa to 8 MPa. As the catalyst, a Cu catalyst (for example, a two-component CuO—ZnO catalyst) can be used.

  In the path from the third reactor 3 to the fourth reactor 4 for propene synthesis, a heat exchanger 28, an on-off valve 29, a distillation apparatus 31, and an intermediate tank 32 are provided. That is, the methanol synthesized in the third reactor 3 is cooled by the heat exchanger 28, separated from the exhaust gas by the distillation device 31, and sent to the intermediate tank 32. Then, it is supplied from the intermediate tank 32 to the fourth reactor 4.

  The fourth reactor 4 is filled with a zeolite catalyst (for example, ZSM-5 catalyst), and further, a heater 33 and a temperature sensor 34 are provided. A reaction temperature field of 450 ° C. to 500 ° C. is formed by the heater 33, and propene is synthesized from methanol under normal pressure. The obtained propene is purified and polymerized in the presence of Ziegler-Natta catalyst in the polymerization apparatus 35 to obtain polypropene.

<Example>
Sawdust was used as the first raw material and the second raw material, and the composition of the gas obtained in the first reactor 1 and the second reactor 2 was examined experimentally. That is, 4.0 g of sawdust was pyrolyzed and gasified at temperatures of 600 ° C., 700 ° C. and 800 ° C. (no addition of steam and dolomite, no catalyst), and the composition of the obtained first gas was examined. Further, 0.5 g of sawdust was gasified with steam at a temperature of 800 ° C. (water vapor addition amount: 0.1 g / min, dolomite addition amount 24.2 g, no catalyst), and the composition of the obtained second gas was examined. . The experimental conditions are shown in Table 1, and the results are shown in FIG.

According to FIG. 2, in both pyrolysis gasification and steam gasification, by-products such as CO ₂ and CH ₄ are seen in addition to H ₂ and CO, but the first gas by pyrolysis gasification It can be seen that H ₂ / CO ≦ 1 (molar ratio), and the second gas by steam gasification is H ₂ / CO ≧ 4 (molar ratio).

Based on the above analysis results, the first gas and the second gas were mixed to prepare a synthesis gas having an H ₂ / CO molar ratio of about 1.4. Specifically, the first gas and the second gas were generated and mixed under the conditions shown in Table 2 to obtain a synthesis gas having a total gas amount of 2200 cm ³ . This synthesis gas was reacted in the third reactor 3 using a CuO—ZnO catalyst under the conditions of a temperature of 220 ° C. and a pressure of 3 MPa. FIG. 3 shows changes in temperature and pressure in this reaction, and FIG. 4 shows component gas amounts before and after the reaction.

According to FIG. 3, the pressure increases with increasing reaction temperature, and then the pressure is reduced. Therefore, it can be seen that methanol synthesis reaction occurs. Then, according to FIG. 4, after the reaction as compared with that before the reaction, only the H ₂ content and CO content is reduced significantly. From this, it is recognized that a methanol synthesis reaction occurs.

<Other embodiments>
Although the said embodiment is a case which obtains a polypropene continuously from a raw material, it can also be made into a batch type. That is, the configuration is as follows. A first tank and a second tank for storing the first gas and the second gas generated in the reactors 1 and 2 shown in FIG. 1 are provided, and each tank analyzes the H ₂ / CO molar ratio of the generated gas. An analyzer is provided. By mixing the two tanks of the gas at a rate corresponding to the _H 2 / CO molar ratio which is analyzed by the gas _analyzer, synthesis H 2 / CO mole ratio = 1.3 to 3.5 as the target value Get gas. This synthesis gas is supplied to a reactor for methanol synthesis to synthesize methanol. Other configurations are the same as those in FIG.

1 First reactor (for first gas generation)
2 Second reactor (for second gas generation)
3 Third reactor (for methanol synthesis)
4 Fourth reactor (for propene synthesis)
24 gas analyzer

Claims (4)

Obtaining a first gas containing H ₂ and CO by pyrolysis gasification of a solid first raw material containing carbon element and hydrogen element in the molecule;
A step of obtaining a second gas containing H ₂ and CO by steam gasification of a second raw material that is the same as or different from the first raw material and contains carbon element and hydrogen element in the molecule;
Mixing the first gas and the second gas at a ratio corresponding to each H ₂ / CO molar ratio to obtain a synthesis gas for alcohol production;
A process for synthesizing alcohol from the synthesis gas. In claim 1,
In order to synthesize methanol as the alcohol, the first gas and the second gas are mixed to obtain a synthesis gas having a H ₂ / CO molar ratio of 1.3 to 3.5. Production method. A first reactor for pyrolyzing and gasifying a solid first raw material containing carbon element and hydrogen element in the molecule for obtaining a first gas containing H ₂ and CO;
A second reaction for obtaining a second gas containing H ₂ and CO by steam gasification of a second raw material which is the same as or different from the first raw material and contains carbon element and hydrogen element in the molecule And
A third reactor for alcohol synthesis;
Synthetic gas supply means for mixing the first gas and the second gas so as to become a synthesis gas for alcohol synthesis at a ratio corresponding to each H ₂ / CO molar ratio and supplying the mixed gas to the third reactor And an alcohol production apparatus. In claim 3,
In order to synthesize methanol, the first gas and the second gas are mixed so as to be a synthesis gas having a H ₂ / CO molar ratio of 1.3 or more and 3.5 or less and supplied to the third reactor. An alcohol production apparatus.

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