JPS59224694A - Saccharification of cellulosic substance and its device - Google Patents

Abstract

PURPOSE:To enable saccharification of cellulosic substance in a highly concentrated state, by blending a cellulosic substance with cellulase in the presence of water, feeding the blend to a saccharification tank of column type, retaining it for a given time, separating the reaction product into a solid and liquid materials. CONSTITUTION:A cellulosic substance such as straw, bagasse, small pieces of wood, etc. is fed from the hopper 3a to the blender 3, the aqueous solution 2 of an enzyme such as cellulase, hemicellulase, etc. is simultaneously added from the pump 3f to it, and, if necessary, an acid or alkali is added from the tank 3d, they are adjusted to a proper pH, and blended by the ribbon blade 3c in the blender 3. The blend is then fed to the packing tank 5 of column type by the screw feeder 4, retained for a given time and saccharified. Liquid(saccharide solution) in the reaction product of the blend is taken out from the filter 7, and the solid material is discharged by the extruder 6, and further separated into a liquid and solid materials by the centrifugal separator 8.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides a method for saccharifying cellulosic substances such as straw, bagasse, corn stover, and wood chips using fibrinolytic enzymes. This invention relates to an improved saccharification method and apparatus for performing saccharification continuously or semi-continuously.

[Background of the invention]

Conventionally, cellulosic materials require delignification and destruction of the cellulose crystal structure as pretreatment in order to be treated with fibrinolytic enzymes. However, in order to put this pretreatment method into practical use, it is necessary to (1) consume less energy for pretreatment and extraction, (2) have a high conversion rate from pretreated raw materials to sugar, and (3) saccharification. In the reaction, it is required to efficiently obtain a highly concentrated sugar solution with less energy consumption.

Among these, for (1) and (2), combinations of pretreatment methods, such as a combination of alkali treatment and pulverization or ozone treatment, are being considered.

On the other hand, in order to obtain the highly concentrated sugar solution (3), it is necessary to charge the pretreated raw materials at a high concentration. In that case, the fiber length of the raw material affects the saccharification reaction. The cutting length of the raw material,
If it is finely pulverized to about 10 to 30 microns, there will be no problem in stirring and mixing and continuous saccharification, but the energy consumption required for this pulverization is extremely large, so it is not practical. Therefore,
Conventionally, methods have been studied that allow pretreated raw materials that are not pulverized to be charged at high concentrations. However, the current situation is that no satisfactory method has been developed yet. For example, in a method in which raw materials are added sequentially and saccharification is performed in a slurry state, there is a problem that there is a limit to the amount of addition because as the amount of addition increases, residue accumulates and becomes sludge. As an alternative method, a saccharification method using a saccharification tank that can perform sludge kneading operations requires a large capacity saccharification tank and the installation of a large-capacity stirring motor, and the mixing within the tank is incomplete. However, there are problems in that a short pass of the raw material occurs and continuous saccharification is difficult.

Therefore, there is a need for the development of a saccharification method that can continuously saccharify pretreated raw materials that are not pulverized at a high concentration and at a high charging rate.

[Purpose of the invention]

The present invention has been made to solve the problems of the prior art described above, and its purpose is to provide a saccharification method in which pretreated raw materials that are not pulverized are charged at a high concentration and saccharified without stirring. Our goal is to provide that device.

[Summary of the invention]

To summarize the present invention, the first invention of the present invention relates to a method for saccharifying a morulose-based substance, and in the saccharification method for obtaining a sugar solution by decomposing a cellulose-based substance with a fibrinolytic enzyme, (1) a step of mixing a cellulosic substance and a fibrinolytic enzyme via water; (2) a step of supplying the mixture to a basic saccharification tank and, after residence for a predetermined period of time, drawing out the resulting mixture from the bottom of the tank; 3) It is characterized by including the steps of separating the product mixture into solid and liquid and recovering a sugar solution.

Further, the second invention of the present invention is an invention related to a saccharification device for cellulose-based materials, and in the saccharification device for obtaining a sugar solution by decomposing cellulose-based materials with a fibrinolytic enzyme, the saccharification device contains a cellulose-based material raw material and a processing agent. It is characterized by including a means for mixing with an aqueous solution, a means for charging the mixture into the saccharification tank, a jacketed tower type saccharification tank, a means for extracting the product mixture from the lower part of the saccharification tank, and a solid-liquid separation means.

The present invention was completed by analyzing the saccharification reaction of high-concentration raw materials as described below.

Alkali-treated or ozone-treated bagasse without pulverization (
average particle size 0.7, ) at a concentration of 10 to 15% by weight,
Horizontal tank with inner diameter of 20cm and length of 40cm (ribbon type)
Batch saccharification was carried out in Motsumono).

In addition, as the cellulase, commercially available Cellulase Onozuka R-10 (manufactured by Kinki Yakult Co., Ltd., optimal temperature 500% pH
4,8) was used. As a result, both the alkali-treated and ozone-treated bagasse were in a sludge state before saccharification, but with the saccharification reaction, the sludge volume decreased and free aqueous liquid increased, resulting in slurry. Then, the slurry state at this time was analyzed.

A reaction tube with an inner diameter of 4 cm and a height of 6 cm with a net installed at the bottom was prototyped, and free aqueous liquid was sampled over time to measure the amount of change. Figure 1 shows the measurement results. In other words, Figure 1 shows the relationship between time (hours) (horizontal axis) and the volume of the packed layer 4Jt (ml).
Hey! lucose, cellobiose concentration <9/l), as well as the flux rate of free aqueous fluid (rnlV/h) and hyglucose,
It is a graph showing the relationship with cellobiose concentration <y/l> (vertical axis).

As is clear from FIG. 1, a large amount of free water and sexual fluid is produced at the early stage of saccharification. The total amount was about 30% of the total water content. At this time, the volume of the raw material sludge decreased due to the saccharification reaction of the sludge state. The rate of decrease in this volume and bonds was approximately 30-40%. From this, we believe that if we use a saccharification tank with a structure similar to the reaction tube described above and perform the saccharification reaction using the sequential addition method, we can charge more raw material to compensate for the reduced volume of raw material sludge. Using a base-type saccharification tank with an internal diameter of 5 cm and a height of 20 cm, 100 g of the ozonated bagasse and cellulase aqueous solution (water content approximately 85% by weight) was added every 24 hours (filling height 7 cm).
m) The saccharification reaction was carried out by sequential addition. Figure 2 shows the results. In other words, Figure 2 shows the saccharification time (hours) (horizontal axis), the amount of produced free aqueous liquid extracted from the bottom of the saccharification tank (cumulative outflow amount) (k), and the glucose concentration (+++y/d).
(vertical axis).

As is clear from FIG. 2, the sugar concentration of the free aqueous liquid increased as the amount of addition increased successively, and became almost constant after the third or fourth addition. Each addition produced 50-60 grams of free aqueous liquid. The total raw material charging volume at this time is approximately 1/3 compared to a batch reaction system in which free aqueous liquid is not removed.
It became. However, the sugar concentration of the liquid separated from the total residual sludge in the saccharification tank was lower than that in the batch reaction system in which free aqueous liquid was not removed. This is because the saccharification reaction is distributed in the filling height direction. From this, it has been found that in the saccharification method of the above type, it is better to perform continuous or semi-continuous operation in which cis sludge is removed from the lower part of the saccharification tank in addition to sequential addition.

Therefore, the saccharification reaction rate is high at the beginning of the saccharification reaction, and the rate of increase gradually decreases and becomes constant. In this experiment, it became constant after 30 to 48 hours. Therefore, it is efficient to extract the sludge from the tank when the residence time of the raw material at the bottom of the saccharification tank reaches a time at which the saccharification rate becomes constant. Then, by separating the extracted raw material sludge and the liquid, a highly concentrated sugar solution can be obtained. However, there were concerns about dilution due to free water. Therefore, we investigated the flow of water within the sludge-filled layer. As a result, it was found that water is released from the filled layer only when the amount of water retained in the filled layer reaches 80% by weight or more, and the water flows downward due to the extrusion flow. Furthermore, in the experimental data, the maximum amount of free water produced per unit time after the sixth addition is as small as about 2.6% of the total amount of retained water. It takes about 50 minutes for the free water in the upper layer to reach the lower layer.
It takes more than 0 hours. Therefore, it was assumed that the free aqueous liquid obtained from the bottom of the saccharification tank was extruded from the sludge near the bottom of the tank. In fact, in the above experiment, the sugar concentration of the free aqueous liquid in the sixth experiment almost matched the concentration of the sugar solution contained in the sludge near the bottom of the tank. From this, it was determined that there was no dilution due to free water.

Therefore, semi-continuous saccharification was performed using the saccharification tank described above. 1
After adding 100 g of the mixture of the pretreated bagasse and cellulase solution in 5 portions every 2 hours, saccharification was performed with a residence time of 60 hours. In addition, a net was installed between each sludge so that the raw material sludge in each category could be determined. As a result, the sugar concentration of the liquid separated from the extracted sludge and the free aqueous liquid was
The result was a glucose of 54 g/l), which was exactly the same as the value obtained in the batch-based saccharification reaction.

Next, conditions for effectively implementing the present invention, ie, conditions for increasing the volume reduction rate of the sludge-like raw material, were investigated. We focused on the retained moisture content of the sludge-like raw material and the fiber length of the cellulosic material as influencing factors.

First, saccharification raw materials with various mixing ratios of bagasse and cellulase aqueous solution were prepared, and this was charged into a saccharification tube with an inner diameter of 4 cm and a height of 6 m with a net installed at the bottom of the tank, and the volume reduction rate of the raw material, i.e. (Volume after saccharification/Volume before saccharification) X100 (%) was investigated. In addition, the average fiber length of bagasse was 0.7.

Measurement result f: Shown in FIG. In other words, Figure 3 shows the solid content concentration (wt%) (horizontal axis) and volume reduction rate (%) (vertical lll
1lI).

As is clear from Figure 3, at a solid content concentration of 5% by weight,
The above-mentioned preparation raw material is in the form of a slurry, and the liquid flows out through the mesh.
Bagasse remained in the form of sludge inside the saccharification tube. At this time, the retained moisture content of the residual bagasse, that is, [(retained water V (retained water amount type material)) X100 (%), was 80 to 90% by weight. Moreover, the saccharification reaction progressed in this residual bagasse, and the sludge volume decreased.

On the other hand, when the solid content concentration was 10 to 20% by weight, the raw material became sludge-like.

When the content exceeds 20% by weight, the raw material becomes lumpy. The volume of these sludge and nodular raw materials decreased due to the saccharification reaction. As a result, it was found that the volume reduction rate becomes large when the solid content concentration is 10 to 20% by weight, and becomes maximum when the solid content concentration is 15% by weight.

This value coincides with the limit value that the raw material bagasse can absorb water (approximately 85% by weight of the limit retained water).

These results were similar when rice straw was used as the sample.

Next, the influence of the fiber length (average diameter) on the volume reduction rate was investigated under the above-mentioned limit water retention conditions. The measurement results are shown in the fourth
As shown in the figure. In other words, Figure 4 shows the fiber length (horizontal axis)
It is a graph showing the relationship between and the volume reduction rate (%) (vertical axis).

As is clear from FIG. 4, fiber lengths of 0.1 m or more are effective. Note that when the fiber length is 2a or more, the volume reduction rate improves, but since the volume at the time of preparation increases,
That doesn't necessarily mean it's effective. Further, when the fiber length is 0.06 mm or less, there is almost no decrease in volume. This is because, although free water was formed, it was not eluted through the plugged mesh. Considering the above,
The fiber length is preferably about 0.1 mm to 2.0 van.

In the following discussion, in order to discuss free aqueous liquids,
We investigated the case where a screen was installed at the bottom of the saccharification tank, but in practice, as will be described later, we confirmed that the presence or absence of the screen does not affect the saccharification reaction itself.

As described above, according to the saccharification method of the present invention, continuous saccharification could be performed at a high concentration and at a high charging rate even with a cellulosic material that is not pulverized.

Embodiments of the apparatus of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 5 is a partially cross-sectional schematic diagram showing an example of the device of the present invention. In Fig. 5, numeral 1 is a cellulose-based material, 2 is an enzyme aqueous solution, 3 is a mixing tank, 3a is a hopper, 3b is a stirring motor, 3c is a ribbon g, 3ct is an alkali or acid aqueous solution, 3e is a pump, 3f is a pump , 4 is a screw feeder, 4a is a screw blade, 5 is a saccharification tank, 5a
is a hot water jacket, 6 is an Ffluder, 6a is a screw blade, 6b is a discharge port, 7 is a net, 7a is a free aqueous liquid,
8 is a centrifugal separator, 8a is a residual cellulosic material, and 8b is a separated liquid.

The device shown in Figure 5 has four functions: mixing, transportation, saccharification, and solid-liquid separation.
It consists of processes.

(1) Mixing process Cellulose-based material 1, which is a raw material, is supplied to the mixing tank 3 through the hopper 33. Then, an aqueous enzyme solution 2 such as cycellulase or hemicellulase is supplied by the pump 3f. The mixture is then mixed by the rotation of the ribbon blade 3c installed on the rotating shaft of the stirring motor 3b. The amount of water at this time is set to the above-mentioned limit retention amount of water, and this value may be determined in advance and the calculated amount may be added.

The pH of the mixture is adjusted by supplying an aqueous alkali or acid solution 3d via a pump 3e. The amount added at this time is
Measure in advance. The structure of the above mixing tank is as follows:
Not particularly limited.

(2) Transportation process The screw feeder 4 was used to transport the mixture to the saccharification tank 5. The supply amount of the mixture is controlled by the screw blade 4.
The test was conducted based on the rotation speed and operating time of a.

(3) Saccharification process The saccharification tank 5 is a tower-shaped packed tank with a hot water jacket 5 on the tank wall.
A is installed. The bottom of the tank is connected to the cross-feeding Ffluder 6. A net 7 is installed below the FFS Fluder 6 on the downward extension of the saccharification tank 5. The diameter of the mesh 70 may be any diameter as long as it can hold the cellulosic material 1. The mixture supplied from the screw feeder 4 forms a packed layer in the saccharification tank 5. Then, the warm water (5a) is heated to the optimum temperature for the fibrinolytic enzyme. When the saccharification tank is enlarged, heat transfer tubes may be installed in the packed layer so as not to interfere with the descent of the mixture. The free aqueous liquid produced by the saccharification reaction is
The mixture was taken out through a net 7, and the cellulose material 1 near the bottom of the tank was taken out through an Ffluder 6. The amount to be extracted at this time was controlled by the rotational speed and operating time of the screw blade 6a of the Ffluder 6.

The operations of screw feeder 4 and FFS Fluder 6 are related, and after FFS Fluder 6 finishes its operation,
The screw feeder 4 starts operating. The operating time for each can be determined based on the transport capacity of each by checking in advance the volume reduction of the mixture during the set residence time in the saccharification tank. That is, the operating times of the screw feeder 4 and the Ffluder 6 are calculated using the following formulas: Δt 6 = Vy / Qr −-(1
)Δt? =VIX/QEX--”
・(2) V m x / V v = α
・・・・・・・・・(3)α=f(T)
・・・・・・・・・(4) [In each of the above formulas, Δt6: Operating time of the Niscrew feeder (minutes), Δt7: Operating time of the Ffluder (minutes)
, Qy Transport speed of Niskrieu feeder) Corpse (m3/
minutes), Q3x: Excluder I transfer speed (m3/
min), VF: Volume of feed mixture (m3), v, x:
Volume of extracted material (m3), α: Reduction rate of mixture volume due to saccharification, T: Residence time of mixture (hours)] (4) Solid-liquid separation process Mixture extracted in Ffluder-6 (residual cellulose substance 8a and sugar) and an aqueous solution containing the enzyme) are subjected to solid-liquid separation using a centrifuge 8. Separated liquid 8b and free aqueous liquid 7
Combine with a to make a sugar solution.

Note that the solid-liquid separation method is not particularly limited to the above centrifugation method.

Next, FIG. 6 is a partially cross-sectional schematic diagram showing another example of the apparatus of the present invention. Each symbol in FIG. 6 has the same meaning as in FIG. 5, and the difference from FIG. 5 is that the net 7 is not installed at the bottom of the saccharification tank 5.

The process in the apparatus shown in Figure 6 is the same as in Figure 5.
The mixing process and the transportation process are the same as in the case of FIG. The steps after the saccharification step are performed as follows.

The operation of the screw feeder 4 and the Ffluder 6 is adjusted so that the mixture of the cellulosic material 1 and the fibrinolytic enzyme aqueous solution supplied from the screw feeder 4 forms a packed layer in the saccharification tank 5. An aqueous solution containing sugar is formed from this packed layer through a saccharification reaction. This aqueous solution descends within the agar tank and reaches the bottom of the tank. Then, it passes through the Ffluder 6 and is extracted out of the tank system from its outlet 6b. This aqueous solution and the cellulose material 1 extracted by the Ffus Fluder 6 are centrifuged (8 times) to separate the residual cellulose material 8a and the separated liquid 8b containing sugar.

At this time, depending on the fiber length of the cellulose-based material 1, the aqueous solution produced by the saccharification reaction may not descend within the filled layer and may remain in the upper part. If a new raw material is supplied and saccharification is performed in this state, the amount of aqueous solution will increase, so it is sufficient to provide an outlet in the upper part of the saccharification tank 5 and draw out the aqueous solution to keep the liquid level constant.

Note that since the extracted liquid contains sugar, it is collected together with the above-mentioned separated liquid 8b.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 Using ozone-treated bagasse as a raw material, continuous saccharification was performed using the apparatus shown in FIG. Note that the ozone treatment method was the method described in Japanese Patent Application Laid-Open No. 57-29293.

The saccharification tank has an inner diameter of 20 cm and a height of 65 cm.

Ozonated bagasse (average fiber length 0.7 tra, cellulose content 140%) and Cellulase Onozuka R,-1
The retained water content of the mixture with the 0-containing aqueous solution was 85% by weight. This mixture was fed at a rate of IKg/hour, the residence time of this mixture section in the tank was about 24 hours, and the temperature in the tank was 50C.
was controlled.

As a result, after 48 hours from the start of the reaction, the glucose concentration in the free aqueous liquid and the aqueous solution contained in the extracted bagasse was 44 Fl/l, and the combined amount of sugar solution was 0.65 Fl/l per unit time. It was t.

Comparative Example 1 Using the same bagasse as in Example 1, a continuous saccharification reaction was carried out in a mechanical stirring tank (with ribbon type blades) having an internal volume of 50 tons. A mixture of ozonated bagasse and cellulase aqueous solution whose pH had been adjusted to 4.8 in advance was supplied to the mechanical stirring tank at IK7/hour, and the residence time was set to 48 hours. The temperature inside the tank was 50711'.

As a result, the glucose concentration in the effluent was approximately 42 g/
It was l. Furthermore, when the residence time was 24 hours, the sugar concentration of the effluent was approximately 24 y/l. Therefore, in order to obtain a sugar solution with a glucose concentration of about 42 g/hr at a feed rate of IKg/hour of the mixture, a residence time of 48 hours and a sugar volume of about 5° were required. .

As is clear from the above Comparative Example 1°, it was found that according to the present invention, a tank volume of 2158° was sufficient compared to the conventional method.

Example 2 An experiment similar to Example 1 was conducted using alkali-treated bagasse. Alkali-treated bagasse was prepared as follows.

A 0.5% by weight aqueous solution of caustic soda and bagasse (average fiber length 0.7 than) were mixed at a mixing ratio of 20:1 and heated at 1ooc for 30 minutes. After collecting the bagasse, it was washed and dried. This alkali-treated bagasse and an aqueous cellulase solution were mixed. The mixing ratio is 3:
It was set at 17. Other saccharification conditions were the same as in Example 1.

After stabilization of the reaction, the glucose concentration of the free aqueous liquid and the aqueous solution contained in the withdrawal mixture was approximately 68 g/l. Note that the sugar concentration is higher here than in Example 1 because the alkali-treated bagasse has a higher cellulose content.

On the other hand, as in Comparative Example 1, a saccharification experiment was conducted in a mechanical stirring tank (with ribbon-shaped wings).

As a result, in order to obtain a sugar solution having the sugar concentration described in Example 2, the tank volume was required to be about 50, as in Example 1.

As is clear from this, it has been found that the tank volume can be reduced by the present invention even when alkali-treated bagasse is used.

Example 3 An experiment similar to Example 1 was conducted using rice straw, corn cob, and wood chips as cellulose-based materials. The pretreatment method was alkaline treatment, and the treatment conditions were the same as in Example 2. In addition, each fiber length was in the order of 0.8 on average. The results are shown in Table 1 below.

Table 1 In Table 1 above, the reason why the glucose concentration in the obtained sugar solution differs is because the delignification rate due to alkali treatment differs depending on the type of cellulose material, and the reason why the glucose concentration in the obtained sugar solution differs is because the cellulose content of the alkali-treated raw material differs. This is because it is possible.

Example 4 Using ozone-treated bagasse as in Example 1 as a raw material,
A saccharification experiment was conducted using the apparatus shown in FIG.

The saccharification tank has a diameter of 2ot-nl and a height of 90cm (7).
Mo(7) '1J11 The retained water percentage of the mixture of ozonated bagasse (average fiber length 0.7 mm) and aqueous solution of cellulase aqueous solution CA R-10 was reduced to 85% by weight. This mixture was fed at IKg/hour, the residence time was about 24 hours, and the temperature inside the tank was controlled at 50C.

As a result, after 48 hours, the glucose concentration was approximately 42
(1/!) of the aqueous solution could be recovered at 0.52 t/hour.

Example 5 A saccharification experiment was conducted using alkali-treated bagasse as a raw material. The alkali-treated bagasse was prepared in the same manner as in Example 2, and the saccharification conditions were the same as in Example 4.

As a result, a sugar solution with a glucose concentration of about 629/l could be obtained.

〔Effect of the invention〕

As described above in detail, according to the present invention, saccharification can be performed without pulverization, and therefore energy consumption during pretreatment can be significantly reduced. In addition, the process requires continuous saccharification, which is practical and necessary, and the saccharification tank can be 1/3 to 215 of the capacity of a conventional mechanical stirring tank, and the stirring power is zero because stirring is performed without stirring. A remarkable effect was achieved.

[Brief explanation of drawings]

FIGS. 1 to 4 are graphs showing the results of various experiments conducted to determine the operating conditions of the present invention, and FIGS. 5 and 6 are partial sections showing an example of the apparatus of the present invention.] ■It is a schematic diagram. 1... Cellulose-based material, 2... Enzyme aqueous solution, 3.
...Mixing tank, 4...Screw feeder, 5...
Saccharification tank, 6...Ffluder, 7...Net, 8.
...Centrifugal separator Figure 3 0 / θ 2030 Solid content concentration (market amount phantom Figure 4 θ 0 / θ, / / i θ latitude: Korenagi (Rebellion Figure 1-51

Claims (1)

[Scope of Claims] 1. A saccharification method for obtaining a sugar solution by decomposing a cellulosic substance with a fibrinolytic enzyme, which comprises: (1) mixing a cellulosic substance and a fibrinolytic enzyme via water; 2) supplying the mixture to the basic saccharification tank and extracting the product mixture from the bottom of the tank after residence for a predetermined time; and (3) separating the product mixture into solid and liquid and recovering the sugar solution. 1. A method for saccharification of cellulosic substances, comprising the steps of: 2. The method for saccharifying a cellulosic material according to claim 1, wherein the water content in the mixture containing the cellulosic material, fibrinolytic enzyme, and water is the maximum amount of water that can retain the cellulosic material. 3. The method for saccharifying a cellulosic material according to claim 1, wherein the mixture containing the cellulosic material, fibrinolytic enzyme, and water has a water content of 80 to 90% by weight. 4. In a saccharification device that obtains a sugar solution by decomposing a cellulosic material with a fibrinolytic enzyme, a means for mixing the cellulosic material raw material and an aqueous solution containing a processing agent, a means for charging the mixture into a saccharification tank, and a jacketed column are provided. 1. An apparatus for saccharification of cellulosic substances, comprising a type saccharification tank, means for extracting a product mixture at the lower part of the saccharification tank, and solid-liquid separation means. 5. A patent claim in which the solid-liquid separation means comprises means for separating free aqueous liquid from the product mixture, means for separating solid-liquid from the residue, and means for mixing the separated liquid and the free aqueous liquid and recovering it as a sugar solution. The apparatus for saccharification of cellulosic substances according to item 4.