JPH0824624A - Method for controlling reaction in bubble tower-type loop reactor - Google Patents

Abstract

PURPOSE:To perform stationarily a reaction by a method wherein a liq. flow rate controlling valve is provided in a liq. circulation line and deviation between a set temp. and the reaction temp. is interlocked with the liq. flow rate controlling valve and the reaction temp. is controlled by controlling the liq. flow rate controlling valve in accordance with the reaction temp. CONSTITUTION:In the bubble tower-type loop reactor, a liq. flow rate controlling valve 10 is provided in a liq. circulation line and deviation between a set temp. and the reaction temp. is interlocked with the liq. flow rate controlling valve and the liq. flow rate controlling valve 10 is controlled in accordance with the reaction temp. and the reaction temp. is controlled by increasing and decreasing the amt. of liq. circulation and the amt. of gas-liq. mass transfer. Namely, when the amt. of liq. circulation is decreased by means of the liq. flow rate controlling valve 10, the reaction temp. is elevated by decreasing heat exchange efficiency and at the same time, as the amt. of gas-liq. mass transfer is increased and the amt. of reaction is increased, the reaction temp. is furthermore elevated. On the contrary, when the amt. of liq. circulation is increased, the reaction temp. is decreased by increasing the heat exchange efficiency and at the same time, as the amt. of gas-liq. mass transfer is decreased and the amt. of the reaction is decreased, the reaction temp. is furthermore lowered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reaction control method for a gas-liquid catalytic reaction using a bubble column loop reactor.

[0002]

2. Description of the Related Art A bubble column type loop reactor is attracting attention as a fermentation apparatus or a gas-liquid contact reaction apparatus because of its simple structure and high efficiency of mixing, heat transfer, mass transfer and the like. . This bubble column type loop reactor is provided with a draft tube having upper and lower ends opened in the container, and gas is continuously blown into the draft tube from a gas disperser provided at the bottom of the container below the draft tube so that the inside of the container is closed. An internal circulation type in which the reaction liquid of is circulated from the water pressure difference inside and outside the draft tube to make gas-liquid contact,
There is an external circulation type which is composed of an ascending pipe and a descending pipe, and in which gas is blown into the ascending pipe to perform liquid circulation due to a density difference.

When an exothermic reaction of a catalyst-containing gas-liquid system is carried out by using such a bubble column type loop reactor, the reaction is caused by disturbances such as instability of the raw material liquid supply amount and nonuniformity of catalyst activity. Because of fluctuations, there is a problem that the reaction temperature rises, particularly in a reaction involving a large amount of heat generation, and undesired by-products are generated or runaway occurs. Therefore, in order to carry out the reaction steadily, it is necessary to control the reaction temperature, and the bubble column type loop reactor is not currently used for the reaction involving a large amount of heat generation.

[0004]

The object of the present invention is to solve the above problems,
To provide a reaction control method of a bubble column loop reactor capable of controlling the reaction temperature by adjusting the liquid circulation amount according to the difference between the set temperature and the reaction temperature and performing the reaction steadily. is there.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a bubble column type loop reactor comprising a liquid upflow part, a gas-liquid separation part at the top of the column, a liquid downflow part and a column bottom part where the liquid flow is reversed. , With the liquid flow control valve in the liquid circulation line,
The present invention relates to a reaction control method characterized in that a reaction temperature is controlled by interlocking a deviation between a set temperature and a reaction temperature with a liquid flow rate control valve and adjusting the liquid flow rate control valve according to the reaction temperature.

The bubble column type loop reactor used in the present invention comprises a liquid ascending flow section, a gas-liquid separating section at the top of the tower, a liquid descending flow section, and a tower bottom section at which the liquid flow is reversed. There are internal circulation type and external circulation type. In particular, when used in a reaction that generates a large amount of heat, an external circulation type with high heat exchange efficiency is preferable. A feature of the present invention is that a liquid flow rate control valve is provided in the liquid circulation line of this bubble column loop reactor, and the deviation between the set temperature and the reaction temperature is linked with the liquid flow rate control valve to adjust the liquid flow rate according to the reaction temperature. It is to control the reaction temperature by adjusting the valve.

This will be described below with reference to FIG. FIG. 1 is a schematic view of a bubble column type loop reactor used in the present invention. In FIG. 1, the reaction gas is fed into the liquid ascending flow section 1 from the gas supply pipe 5. The liquid ascending flow section 1 passes through a column bottom section 2 and a gas-liquid separating section 3 and then a liquid descending flow section 4
Connected to. The gas dispersed as bubbles is separated in the gas-liquid separation unit 3 and is discharged from the gas discharge pipe 7. The liquid downflow section 4 is a multi-tube heat exchanger for taking out heat generated by the reaction. A liquid flow rate control valve 10 is provided on the tower bottom 2. The reaction temperature is set by the temperature indicator controller 12, and according to the difference between the set temperature and the actual reaction temperature, the liquid flow rate regulating valve 10 is adjusted by the flow rate indicator controller 11 which is interlocked with this to circulate the liquid. The amount can be increased or decreased.

Generally, in a bubble column type loop reactor, for example, mixed-phase flow 5 volume 4 (1991) p. 307 Fi
g. As described in 6, the liquid circulation rate U _L gas-liquid mass transfer amount k _L a in the relation shown in FIG. That is, the gas-liquid mass transfer amount k _L a to decrease the liquid circulation rate U _L increases, the reverse to the liquid circulation rate U _L is small gas-liquid mass transfer amount k _L a in a relationship increases. On the other hand, gas-liquid mass transfer amount k _L
When a decreases, the reaction amount decreases, so the reaction temperature decreases, and conversely, when the gas-liquid mass transfer amount k _L a increases, the reaction amount increases and the reaction temperature increases. Further, since the liquid circulation rate U _L is the efficiency of heat exchange decreases small reaction temperature increased, the reaction temperature because efficiency is improved heat exchange Conversely, when the liquid circulation velocity U _L increases decreases.

Therefore, a liquid flow rate adjusting valve is provided in the liquid circulation line, and the deviation between the set temperature and the reaction temperature is linked with the liquid flow rate adjusting valve, and the liquid flow rate adjusting valve is adjusted according to the reaction temperature to perform the liquid circulation. The reaction temperature can be controlled by increasing or decreasing the amount and the gas-liquid mass transfer amount. That is, when the liquid circulation amount is reduced by the liquid flow rate control valve, the reaction temperature rises due to a decrease in heat exchange efficiency, and at the same time, the gas-liquid mass transfer amount also increases and the reaction amount increases from the relationship of FIG. This further raises the reaction temperature. On the contrary, if the liquid circulation amount is increased by the liquid flow control valve, the reaction temperature decreases due to the increase in heat exchange efficiency, and at the same time, the gas-liquid mass transfer amount also decreases and the reaction amount decreases from the relationship of FIG. This further lowers the reaction temperature. Therefore,
The reaction temperature can be kept constant by linking the deviation between the set temperature and the reaction temperature with the liquid flow rate control valve.

For example, CDT obtained by trimerizing butadiene
(Cyclododecatriene), then CDT is hydrogenated to CDAN (cyclododecan), and CDAN is oxidized in the step of producing CDON / OL (cyclododecanone / cyclododecanol).
Since the step of hydrogenating T to produce CDAN is a gas-liquid solid catalytic reaction and an exothermic reaction, transfer of hydrogen into the reaction solution and removal of a large amount of reaction heat can be efficiently performed. It is necessary, and a bubble column loop reactor is suitable as a reactor therefor. In the above reaction, the control of the reaction temperature is important because the hydrogenolysis and isomerization of CDT occur especially at high temperatures. Therefore, by applying the reaction control method of the present invention to the above reaction, the reaction temperature can be kept constant, so that the production of by-products can be prevented and CDAN can be produced safely and economically. Become.

[0011]

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[0012]

EXAMPLES Examples will be shown below. Example 1 A hydrogenation reaction in which CDT was hydrogenated to synthesize CDAN was carried out using the bubble column loop reactor shown in FIG. In FIG. 1, the liquid upflow portion 1 reacts with CDT and H _{2 to} cause CD
The reaction section serving as AN and the liquid downflow section 4 are multitubular heat exchanger sections for taking out heat generated by the reaction.
Then, the reaction temperature is set by the temperature indicating controller 12, and according to the difference between the set temperature and the actual reaction temperature, the liquid flow adjusting valve 10 is operated by the flow rate indicating controller 11 which is interlocked with this.
The reaction temperature can be controlled by increasing or decreasing the liquid circulation amount by adjusting. To a loop reactor with a reaction volume of 0.84 l, CDAN
On the other hand, a hydrogenation catalyst (Ni 66% supported SiO ₂ —Al ₂ O
₍₃ catalyst) 0.3 wt% added slurry solution,
H ₂ gas was introduced at 56.5 Nl / hr and 4 kg / cm ² G through the gas supply pipe 5 to form a liquid circulation between the reaction section and the heat exchanger section. Next, from the raw material supply port 6, 0.547 k of a slurry solution in which 0.3 wt% of a catalyst is added to CDT
The reaction liquid was supplied by g / hr to start the reaction, and the reaction liquid was discharged from the reaction liquid discharge pipe 8 by overflow. Table 1 shows the deviation of the internal temperature of the reactor from the set temperature, the outlet reaction rate, and the liquid circulation amount when the temperature is set to each temperature by the temperature indicating controller 12 and the steady state is reached. The transition to each set temperature could be performed smoothly.

[0013]

[Table 1]

[Brief description of drawings]

FIG. 1 is a schematic view of a bubble column type loop reactor used in the present invention.

FIG. 2 is a diagram showing a relationship between a liquid circulation speed U _L and a gas-liquid mass transfer amount k _L a in an example of the present invention.

[Explanation of symbols]

 1 Liquid Upflow Part 2 Tower Bottom 3 Gas-Liquid Separation Part 4 Liquid Downflow Part 5 Gas Supply Pipe 6 Raw Material Supply Port 7 Gas Discharge Pipe 8 Reactant Discharge Pipe 9 Gas Dispersion Plate 10 Liquid Flow Control Valve 11 Flow Indicator 12 Temperature indicator controller 13 Coolant outlet 14 Coolant inlet

Claims (1)

[Claims] 1. A bubble column type loop reactor comprising a liquid ascending flow section, a gas-liquid separating section at the top of the tower, a liquid descending flow section, and a tower bottom at which the liquid flow is reversed, and a liquid flow control valve in a liquid circulation line. And the reaction temperature is controlled by interlocking the deviation between the set temperature and the reaction temperature with the liquid flow rate control valve and adjusting the liquid flow rate control valve according to the reaction temperature.