JPH042302B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a stirred packed bed reactor.

(Prior art) In recent years, there has been much research and development regarding the establishment of production technology using immobilized biocatalysts, and the reactors used for this are packed bed type and fluidized bed type as seen in JP-A-59-162873. There are a wide variety of types, including the stirring tank type as seen in Japanese Patent Publication No. 28-974, and the membrane type.

(Problems to be solved by the invention) Conventionally, packed bed reactors do not have strong stirring;
Even fragile immobilized biocatalysts are not destroyed.

Furthermore, since there is little back-mixing of liquids, there is an advantage that even reactions where product inhibition occurs can be carried out with high efficiency.

There are upward and downward flow methods for passing liquid into the reactor, but downward flow is more effective in terms of preventing backflow and efficiently reacting with plug flow.

However, in the case of downward flow, if the substrate tends to adhere to the immobilized biocatalyst, or if such substances coexist in the solution containing the substrate, the pressure loss will increase economically.

In addition, although the pressure loss is small in the upward flow, a phenomenon in which the flow concentrates in the easily flowing portion of the packed bed, that is, channeling occurs, and the reaction efficiency decreases. In particular, this tendency becomes more pronounced as the diameter of the reactor increases.

(Means for Solving the Problems) Therefore, the technical problem of the present invention is to provide an upflow packed bed type immobilization system that can improve the contact between the immobilized biocatalyst and the substrate and increase the reaction efficiency. The purpose of the present invention is to provide a reactor for biocatalysts, and the technical means of the present invention to solve this technical problem is to provide a reactor for biocatalysts in the center and outer periphery of a packed bed in a vertical column packed with immobilized biocatalysts. A stirring blade that is driven independently at a low speed is installed in the vertical column, and a conical mesh is used as the packing bed supporting mesh for the vertical column, and a bubble removal device is installed at the tip of the conical mesh where air bubbles accumulated on the bottom surface of the mesh gather. Scraping blades that open the pipe and scrape off the immobilized biocatalyst floating with air bubbles on the bottom surface of the immobilized biocatalyst outflow prevention net installed above the packed bed in contact with the net surface and return it to the packed bed. is provided so that the substrate continuously supplied from the substrate inlet provided at the bottom of the vertical column and the loaded immobilized biocatalyst are brought into contact by the stirring action of the stirring blade to cause a reaction to occur. This is what I did.

(Effect of the invention) The present invention installs stirring blades in the packed bed part of the reactor,
This system uses a method of stirring the immobilized biocatalyst by rotating it at a low speed, and since the rotation speed is low, no axial flow occurs due to this stirring. Since the packed bed is always moving in the circumferential direction, channeling can be prevented and reaction efficiency can be improved.

However, by rotating the stirring blades in the center so that the circumferential speeds of the stirring blades on the outer periphery are equal, the diameter of the reactor can be increased, and the stirring speed between the center and the tip can be increased, as in a uniaxial stirring system. The stirring state is made uniform without a large difference in the reaction rate, channeling is prevented, and the reaction efficiency is improved.

Additionally, when the stirring blades in the center and the stirring blades in the outer periphery are rotated in opposite directions, the relative speed increases even at low speeds, so the external diffusion rate around the immobilized biocatalyst increases. have.

Furthermore, the filling material is not damaged because it rotates at a low speed, the power required for each motor is small because the stirring blades can be shortened, and the plug flow can be maintained because axial stirring does not occur. It has the characteristic of being able to react with high efficiency even with oxygen, which is susceptible to product inhibition.

In addition, at the same time as the stirring blades rotate, the scraping blades on the bottom surface of the column upper mesh are rotated, and this stirs the immobilized biocatalyst that has risen due to adhesion of bubbles, so the adhering bubbles are separated and the immobilized biocatalyst is packed. Fall to the layer. As a result, no pressure loss occurs due to the accumulation of the immobilized biocatalyst, and the
Since air bubbles generated in the conical network for supporting the immobilized biocatalyst at the bottom of the packed bed are easily discharged, the liquid is introduced into the packed bed without drifting.

(Example) The embodiments shown in the drawings will be described below.

The outer periphery of the vertical column body is a temperature-maintaining jacket 1
1a and 1b are the hot water inlet and outlet.

The inside of the main body constitutes an immobilized biocatalyst filling part 13, in which central stirring blades 2 and outer peripheral stirring blades 3 are formed in multiple stages, and the central stirring blades 2 are connected to the shaft 4.
The outer stirring blade 3 is attached to the frame 5.

The shaft 4 is directly driven by the motor 6 and the frame 5
is driven by a motor 7, which drives a pulley 9 via a belt from a pulley 8, drives a pipe 10 fitted onto the shaft 4 from the pulley 9, and drives the frame 5 with the pipe 10. There is.

The lower end of the illustrated shaft 4 is supported by a knife holder 11 provided at the center of the frame 5.
1 is supported by support needles 12 arranged at the bottom of the vertical column.

A jacket 15 is also formed in the lower conical part 14 of the vertical column, and 15a and 15b are hot water inlets and outlets.

Further, 16 is a substrate inlet formed with a conical portion 14.

Furthermore, a bubble removal pipe 17 is formed in the conical portion 14, and this is connected to a bubble discharge pipe 19, so that bubbles can be discharged by opening the cutout 18.

The support needle 12 described above stands upright in the center of the bubble removal pipe 17.

At the boundary between the immobilized biocatalyst filling part 13 and the conical part 14, there is a conical structure 20 for supporting the immobilized biocatalyst packed layer.
There is.

In the illustrated example, the tip of the support needle 12 is supported by the center of the net 20.

An immobilized biocatalyst outflow prevention net 21 is stretched over the upper cylinder 24 of the vertical column body, and there are bubble separation scraping blades 22 that rotate along the net and are attached to the drive pipe 10 of the frame 5. ing.

23 is a product outlet in a hemispherical part 25 formed following the cylindrical part 24.

This reactor has the immobilized biocatalyst filling section 1 as described above.
3. Conical network 20 for supporting immobilized biocatalyst packed layer;
A central stirring blade 2 installed in multiple stages to stir the packed bed in the center, an outer peripheral stirring blade 3 installed in multiple stages to stir the outer periphery, a discharge pipe 19 for air bubbles accumulated on the lower surface of the net 20, and a temperature-maintaining pipe 19. It consists of a jacket 1, motors 6 and 7 for rotating each stirring blade, a net 21 for preventing outflow of the immobilized biocatalyst, and a scraping blade 22 for separating air bubbles adhering to the immobilized biocatalyst floating and depositing on its lower surface. ing.

Next, to explain the action according to the flow of the substrate, the substrate heated to the reaction temperature releases dissolved gas, which becomes bubbles and collects at the top of the packed bed support net 20 at the bottom of the reactor.

The air bubbles pass through the pipe 17 and the discharge pipe 19
It is discharged from there by a metering pump (not shown).

The substrate from which air bubbles have been removed reaches the immobilized biocatalyst filling part 13 from the filling support net 20, and is reacted by the immobilized biocatalyst a.

Here, the immobilized biocatalyst is stirred by blades 2, 3 rotating at low speed.

Note that these blades 2 and 3 attached to the center and the outer periphery are usually adjusted and rotated so that the speeds of their tips are the same.

In this way, by stirring the packed bed with a stirring blade, channeling does not occur even in a reactor with a large diameter, and the immobilized biocatalyst and substrate come into contact with each other efficiently, improving reaction efficiency.

The reactants generated by passing through the packed bed pass through a net for preventing outflow of the immobilized biocatalyst and reach the next step.

Then, the immobilized biocatalyst that has floated up with fine bubbles together with the reactants reaches the bottom surface of the immobilized biocatalyst outflow prevention net 21 and is deposited thereon. By stirring this deposited layer at low speed with the scraping blade 22, fine air bubbles are separated from the immobilized biocatalyst and are discharged from the outlet 23 through the immobilized biocatalyst outflow prevention net 21.

The immobilized biocatalyst separated from the bubbles is smoothly returned to the immobilized biocatalyst packed bed section 13 by propeller-shaped scraping blades 22 that generate a flow in the opposite direction to the flow direction of the reaction liquid.

According to the embodiment, the air bubbles accumulated on the lower surface of the packed bed support net 20 can be continuously or intermittently discharged by the bubble removal pipe 17 attached at a position close to the lower surface. It is possible to prevent drifting and improve reaction efficiency.

Furthermore, in a practical scale reactor, problems such as large pressure drop and crushing of the immobilized biocatalyst in the lower part of the reactor will occur unless the diameter of the reactor is increased.

Therefore, the diameter of the reactor must necessarily be increased.

When a packed bed is stirred by a single uniaxial stirrer in such a large-diameter reactor, the stirring speed differs greatly between the center and the tip of the stirring blade.
However, as in the embodiment, a plurality of independent stirrers may be installed and each stirrer may be rotated differently so that the peripheral speeds thereof are equal.

This method ensures uniform stirring and prevents channeling even in large-diameter reactors.
Reaction efficiency is improved.

In addition, each stirrer may be installed so that it can rotate in forward and reverse directions.

In this case, when it is rotated in the opposite direction, the relative speed increases even at a low speed, so the effect is that the external diffusion rate at the outer periphery of the immobilized biocatalyst increases.

Further, when the gas dissolved in the substrate solution kept at a low temperature is raised to the reaction temperature, it becomes bubbles and stays on the lower surface of the filling support net 20. Therefore, the flow in that part is blocked and a drift occurs before reaching the filling layer 13, which may cause channeling within the filling layer.

Therefore, the packed bed supporting net 20 is formed into a conical shape, and air bubbles are collected at the top thereof and can be discharged out of the system via the pipe 17 by a metering pump.

Further, fine air bubbles may reach the inside of the packed bed and adhere to the immobilized biocatalyst.

In this way, the immobilized biocatalyst with bubbles increases its buoyancy and floats up to the immobilized biocatalyst outflow prevention net 21.

For this purpose, the immobilized biocatalyst is deposited on the bottom surface of the screen, and a rotating stirring blade 22 is installed in contact with the bottom surface of the screen, and by rotating this blade at a low speed, air bubbles and the immobilized biocatalyst are separated. can be separated, and the separated immobilized biocatalyst sinks.

This is because the stirring blade 22 is rotated in the direction of downward flow as described above.

Since there is no accumulation of immobilized biocatalyst on the bottom surface of the screen, no increase in pressure loss occurs within the reactor.

A specific experimental example will be described below.

<Experiment 1> The immobilized protease was covalently immobilized on alumina (density 3.5 g/cm ³ ) with a diameter of 0.7 mmφ and placed in a stirred packed bed reactor (160 mmφ), and a 10% casein solution was added from the bottom. (50°C) at SV:10 to react. Here, SV is Space
Velocity (spatial velocity). in this case,
The rotational speed of the stirrer that stirs the packed bed part was 30 rpm for the center (blade diameter 70 mm) and 14 rpm for the outer periphery (blade diameter 150 mm), so that the circumferential speeds were almost the same. .

In addition, the gas dissolved in the 10% casein solution became bubbles and remained at the top of the lower surface of the packed bed support network, so these were removed via a pipe with a metering pump. In this way, by stirring the packed bed at low speed using a dual-type stirrer while removing air bubbles that remain at the top of the bottom surface of the packed bed support network, channeling does not occur, and no backflow occurs due to stirring. I was able to react.

The decomposition rate in this case was about 93 to 97%, assuming that the decomposition rate in the downward flow method, which has the highest reaction efficiency, was 100%.

In addition, it was 70 to 85% in an upflow type packed bed reactor in which the packed bed was not stirred.

Alumina is heavy with a density of 3.5 g/cm ³ , so fine bubbles were attached to it, and no bubbles were observed floating up to the bottom surface of the immobilized biocatalyst outflow prevention net. Therefore, in this case, it was found that there is no need to install a scraping blade.

<Experiment Example 2> β-galactosidase originating from Aspergillus oryzae immobilized on phenol-formalin resin was placed in the stirred packed bed reactor shown in Experiment Example 1, and 12% reduced skim milk (45 ℃）SV=14
The liquid was passed through. The rotation speed of the stirrer is the one in the center.
Set it to 10rpm, and set the outer part to 4.6rpm,
The peripheral speeds were made to be approximately the same. As in Experimental Example 1, since it was prepared by reduction, it contained a large amount of air bubbles, which gathered and remained at the top of the lower surface of the packed bed support network. Therefore, it was removed almost continuously using a metering pump through a pipe.

Further, this resin has a light density of 1.1 g/cm ³ , and therefore the immobilized β-galactosidase with fine bubbles attached floated to the bottom surface of the immobilized biocatalyst outflow prevention mesh. When these immobilized β-galactosidase were stirred by a scraping blade for separating bubbles, the bubbles were separated, and these immobilized oxygen were absorbed into the packed bed by the downward flow generated by the blade and by its own weight. It sank to .

When the reaction was carried out under the above conditions, the decomposition rate was 1.1 times that of the case without stirring, which was close to the decomposition rate when the liquid was passed in a downward flow.

In any case, the present invention improves the upward flow phenomenon in conventional packed bed reactors,
The packed bed is stirred by stirring blades rotating at low speed to improve reaction efficiency.

[Brief explanation of drawings]

The drawing is a sectional view showing the reactor of the present invention. 1... Jacket, 2, 3... Stirring blade, 13...
... Immobilized biocatalyst filling part, 16 ... Substrate inlet, 1
7...Bubble removal pipe, 20...Conical net for supporting the packed bed of immobilized biocatalyst, 21...Net for preventing outflow of the immobilized biocatalyst, 22...Scraping blade for air bubble separation, 2
3...Product outlet.

Claims (1)

[Claims] 1. Stirring blades that are independently driven at low speed are installed in the center and outer periphery of the packed bed in a vertical column filled with an immobilized biocatalyst, and the packed bed supporting net of the vertical column is replaced with a conical mesh. Then, a bubble removal pipe is opened at the tip of the conical net where the air bubbles accumulated on the bottom surface of the net gather, and the air bubbles float to the bottom surface of the net for preventing outflow of the immobilized biocatalyst installed above the packed bed. A scraping blade is provided that scrapes the immobilized biocatalyst and returns it to the packed bed in contact with the mesh surface, and the substrate provided at the bottom of the vertical column and the packed immobilized biocatalyst are removed by the stirring blade. A stirred packed bed reactor characterized by bringing the reaction into contact with the stirring action.