CN111359539B - Gas-liquid reaction method and gas-liquid reaction device capable of entering reaction preparation state in advance - Google Patents

Gas-liquid reaction method and gas-liquid reaction device capable of entering reaction preparation state in advance Download PDF

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CN111359539B
CN111359539B CN202010096185.6A CN202010096185A CN111359539B CN 111359539 B CN111359539 B CN 111359539B CN 202010096185 A CN202010096185 A CN 202010096185A CN 111359539 B CN111359539 B CN 111359539B
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liquid
phase
reactor
reaction
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CN111359539A (en
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许萧
杨强
王磊
王俊杰
卢浩
代品一
钱运东
黄燎云
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Shanghai Misu Environmental Protection Technology Co ltd
East China University of Science and Technology
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East China University of Science and Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J4/00—Feed or outlet devices; Feed or outlet control devices
    • B01J4/001—Feed or outlet devices as such, e.g. feeding tubes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/0006—Controlling or regulating processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/24—Stationary reactors without moving elements inside
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J4/00—Feed or outlet devices; Feed or outlet control devices
    • B01J4/001—Feed or outlet devices as such, e.g. feeding tubes
    • B01J4/002—Nozzle-type elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J4/00—Feed or outlet devices; Feed or outlet control devices
    • B01J4/008—Feed or outlet control devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2204/00—Aspects relating to feed or outlet devices; Regulating devices for feed or outlet devices
    • B01J2204/002—Aspects relating to feed or outlet devices; Regulating devices for feed or outlet devices the feeding side being of particular interest

Abstract

The invention discloses a gas-liquid reaction method for entering a reaction preparation state in advance, wherein gas-phase feeding branches comprise partial gas-phase feeding and main process gas-phase feeding; the liquid phase feeding and the part of gas phase feeding are premixed through 4 steps before entering a reactor to obtain premixed materials; the lower part of the reactor is provided with a main process gas phase feed inlet and a premixed material feed inlet, and the reactor above the premixed material feed inlet is a reaction main control unit; the premixed material enters the reactor through the premixed material feed inlet, and the main process gas-phase feed enters the reactor through the main process gas-phase feed inlet and upwards reacts with the premixed material entering the reaction main control unit. A gas-liquid reaction device is also provided. The gas-liquid reaction method and the device can enable the premixed material to enter a reaction preparation state in advance before entering the reactor, and are beneficial to improving the conversion rate and the selectivity to be close to the reaction equilibrium conversion rate and the selectivity.

Description

Gas-liquid reaction method and gas-liquid reaction device capable of entering reaction preparation state in advance
Technical Field
The invention belongs to the technical field of gas-liquid reaction. In particular to a gas-liquid reaction method and a gas-liquid reaction device which enter a reaction preparation state in advance.
Background
In the middle-speed and slower gas-liquid reaction processes of oxidation, hydrogenation and the like, gas is firstly contacted with liquid, gas molecules are transferred to a liquid film at a gas-liquid interface and further diffused to the liquid phase, and the dissolving process is completed. Gas molecules dissolved in the liquid react with liquid molecules at the catalytic active sites to complete the reaction conversion process; in the absence of catalytically active sites, the gas dissolves while reacting with the liquid. Therefore, in the gas-liquid reaction, the speed and depth of the gas dissolved in the liquid are important factors affecting the reaction speed and depth of the reaction chain.
For example, in the liquid phase hydrogenation process, hydrogen and raw oil are premixed, so that hydrogen is dissolved in raw oil, and then the hydrogen enters a reactor for reaction, and most of hydrogen required in the reaction comes from dissolved hydrogen. The raw oil and hydrogen have low similarity and compatibility, so the process of dissolving hydrogen in the raw oil is a slower process, and longer premixing retention time is needed. In the existing process, in order to meet the amount of hydrogen required in the hydrogenation process, a large amount of circulating oil is required or a solvent is additionally added to dissolve the hydrogen, so that the hydrogenation efficiency is reduced and the production cost is high.
For example, in the process of synthesizing isophthalic acid by oxidation reaction, a metaxylene liquid raw material is mixed and contacted with oxygen in a reactor, and the reaction is carried out by adopting mixing means such as stirring, jet flow and the like. However, the dissolution rate and concentration of oxygen in meta-xylene are very low, and the meta-xylene liquid feedstock flowing through the feed line directly into the reactor usually needs to be precontacted with bubbling oxygen for a long time, resulting in low reaction efficiency at the bottom of the reactor, large volume of the reactor, and high production cost.
Patent CN 101993721a discloses a liquid phase circulation hydrotreating method and reaction system, which utilizes part of circulation of liquid phase product of hydrotreating to mix with fresh raw oil to form liquid phase material, and mixes hydrogen into the liquid phase material, thereby increasing the mixing amount of hydrogen and the saturated dissolved hydrogen amount. However, a large amount of hydrogen gas remains in the hydrogenation reactor, and a high recycle hydrogen compressor is required to recycle the hydrogen gas, so that the production cost is increased.
The problem that the dissolved gas in liquid is insufficient exists in the feeding position accessory of the existing gas-liquid reactor, so that the gas-liquid mixture at the position does not enter a reaction preparation state, and the problem of low reaction efficiency is caused. Therefore, there is a need to develop a novel gas-liquid reaction method and apparatus to solve the above technical defects in the prior art.
Disclosure of Invention
The first purpose of the invention is to provide a gas-liquid reaction method which enters a reaction preparation state in advance, so as to solve the technical defects of low gas content rate, low reaction conversion rate and selectivity and high production cost of the reactor in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
the gas-liquid reaction method comprises the steps of entering a reaction preparation state in advance, wherein gas-phase feeding branches comprise partial gas-phase feeding and main process gas-phase feeding, the lower part of a reactor is provided with a main process gas-phase feeding hole, a premixed material feeding hole is arranged above the main process gas-phase feeding hole, and the reactor above the premixed material feeding hole is a reaction main control unit; the method comprises the following steps:
(1) forming larger bubbles in the liquid-phase feeding material by the partial gas-phase feeding material to obtain mixed feeding material containing the larger bubbles;
(2) forming a relatively strong liquid phase turbulence on the mixed feed containing the larger bubbles so as to rapidly dissolve the larger bubbles in the mixed feed containing the larger bubbles into a liquid phase to obtain a mixed feed with a large gas dissolving amount;
(3) forming the undissolved large bubbles in the mixed feed with a large gas dissolving amount into micro bubbles under a high shearing condition to obtain the mixed feed containing the micro bubbles;
(4) forming a relatively weak liquid phase turbulence in the mixed feed containing the micro-bubbles so as to further dissolve the micro-bubbles into the liquid phase feed to obtain the premixed material;
(5) the premixed material enters the reactor through the premixed material feeding hole, the main process gas phase feeding enters the reactor through the main process gas phase feeding hole, and the premixed material and the main process gas phase feeding are upward fed into the reaction main control unit for reaction;
under the relatively strong liquid phase turbulence condition, the Reynolds number of the liquid is 2000-200000;
under the relatively weak liquid phase turbulence condition, the Reynolds number of the liquid is 0.1-2000;
the particle Reynolds number of the micro-bubbles is less than 1;
the amount of the partial gas phase feed is 1.01 to 2 times of the amount of the gas phase required for the liquid phase feed to reach the gas phase saturated dissolution concentration per unit time.
Under the conditions, the gas phase concentration in the premixed material can reach the saturated dissolved concentration.
It should be noted that the saturated dissolved concentration is not limited to the stoichiometrically exact saturated dissolved concentration under specific temperature and pressure conditions. Under certain temperature and pressure conditions, the saturated solution concentration in the flowing state will shift to some extent. Typically, the offset range is ± 15%. For example, the shift range is + -15% as shown in "shift of pressure of carbon dioxide-water phase equilibrium system under turbulent flow conditions", journal of Beijing university of chemical engineering (Nature science edition), 2013,40(3): 5-11.
It is well known to those skilled in the art that gas dissolves slowly and insufficiently in a liquid. The limit of gas-liquid mass transfer is gas-liquid phase equilibrium at rest. However, in the actual production process, the gas-liquid equilibrium of the flowing gas-liquid phase is difficult to achieve, and one reason for the phenomenon is that the gas-liquid phase needs a long contact time to achieve the dissolution equilibrium, and the flowing materials in the industrial production cannot meet the long-time dissolution, so that the solvent equilibrium cannot be achieved. In engineering research, researchers realize that two flowing gas-liquid phases can hardly reach phase balance (see the theory of interface imbalance: majeu, von hui, xueshuan, et al. interface mass transfer mechanism of absorption process [ J ]. Chinese chemical engineering report (English edition), 2003,11(2):13-16. majeu, cong. gas-liquid interface mass transfer mechanism [ J ]. chemical report, 2005,56(4): 574) 578), and the state that the phase balance can not be reached but is in a relatively stable state is called a metastable thermodynamic equilibrium state.
Based on the dynamic gas-liquid mass transfer theory, the liquid flow can affect the gas-liquid mass transfer speed and the equilibrium concentration. The most common practice is to increase the mass transfer interfacial area and reduce the mass transfer resistance, and accelerate the dissolution of the gas. Such as increasing liquid phase turbulence to increase the mass transfer rate of dissolution absorption, enhancing gas absorption, such as stirring, vibration, jet flow, hypergravity, etc., but too strong liquid phase turbulence is not favorable for dissolution absorption mass transfer, for example, carbonated beverages can cause gas desorption and overflow, and some volatile liquids usually require careful attention to avoid component vaporization. Therefore, how to realize that the gas-liquid two phases under the dynamic condition reach the thermodynamic metastable equilibrium state under the condition of shorter contact time so as to improve the reaction efficiency of the subsequent reaction, improve the conversion rate and the selectivity and reduce the production cost is a problem which needs to be solved urgently by the technical personnel in the field.
By the method, the dissolution and absorption of the gas are enhanced through two steps of high-speed runner dissolution and low-speed runner dissolution, and the premixed material can reach the saturated dissolution concentration of the gas (namely, the thermodynamic metastable equilibrium state is reached) in advance before entering the reactor, namely, the premixed material enters the reaction preparation state in advance. The premixed material starts to react at the lower part of the reactor or is ready for reaction, so that the direct and rapid reaction of reactants is facilitated. The premixed material with a reaction preparation state enters the reaction main control unit and then further reacts, so that the reaction conversion rate and selectivity are obviously improved, and the volume of the reactor is favorably reduced. Therefore, the method just effectively solves the technical problem.
According to a preferred technical scheme of the invention, the main process gas-phase feeding material and the premixed material enter the reaction main control unit upwards in a plug flow mode to react.
The device is beneficial to the reaction efficiency, the reaction conversion rate and the selectivity of the gas-liquid phase reaction. For example: for exothermic reactions, back-mixing will result in an increase in the temperature of the reaction mass and a decrease in selectivity. The back mixing can be reduced as much as possible by adopting a plug flow mode.
In order to realize the above-mentioned plug flow manner, various structures in the prior art can be adopted. In the invention, the plug flow is effectively realized through a specially arranged structure.
Preferably, the reactor further comprises a gas distributor connected with the main flow gas phase feed port and a liquid velocity distribution unit connected with the premix material feed port; wherein:
the liquid velocity distribution unit comprises a unit body, a unit inlet and a plurality of liquid velocity distribution outlets are formed in the unit body, the unit inlet is connected with the premixed material feeding port, discharging pipes are arranged on the liquid velocity distribution outlets, and the liquid velocity distribution outlets and the discharging pipes are respectively distributed along the cross section of the reactor; the cross-sectional area of the tapping pipe is larger closer to the side wall of the reactor, and the cross-sectional area of the tapping pipe is smaller closer to the center of the reactor; and the shorter the length of the tapping pipe closer to the side wall of the reactor, the longer the length of the tapping pipe closer to the center of the reactor; so that the flow rate of the liquid in the middle of the reactor is relatively small and the amount of the liquid is relatively small; the flow rate of the liquid close to the side wall of the reactor is relatively large, and the amount of the liquid is relatively large;
and the premixed material and the gas-phase feeding of the main process realize upward horizontal pushing flow above the liquid velocity distribution unit and upwards enter the reaction main control unit.
In the present invention, after the main process gas-phase feed injected into the bottom of the reactor passes through the gas distributor, a bubble upflow flow regime is formed inside the reactor, which belongs to the flow regime characteristics of a conventional bubble reactor and presents a liquid velocity distribution with a sidewall liquid velocity downward and a central liquid velocity upward. This will result in some degree of back-mixing, thereby reducing reaction conversion and selectivity.
By the method, the premixed material enters the liquid velocity distribution unit, and the liquid velocity distribution unit enables the premixed material to flow upwards and presents initial liquid distribution with high side wall distribution flow velocity and low center distribution flow velocity. And after the liquid velocity distribution of the liquid velocity distribution unit below the liquid velocity distribution unit is superposed with the liquid velocity distribution of the liquid velocity distribution unit with the side wall downward and the central liquid velocity upward, the liquid can be horizontally pushed to flow upwards integrally. Is very favorable for improving the conversion rate and the selectivity of the reaction.
By the method, the premixed materials from the hydraulic premixer enter the liquid velocity distribution unit of the reactor, the liquid velocity distribution unit enables the premixed materials to flow upwards and present liquid initial distribution with high side wall distribution flow velocity and low center distribution flow velocity, and the liquid velocity distribution with downward side wall liquid velocity and upward center liquid velocity below the liquid velocity distribution unit is superposed, so that the liquid flows in a flat plug flow with integral flat plug upwards.
It should be noted that the reaction master control unit is usually in the form of a stirred reaction unit, a fixed bed, a fluidized bed, a packing unit, or the like. Or an empty reactor, the gas-liquid phase reacting in the process of going up the reactor.
It should be noted that the superficial gas velocity of the main process gas phase feed in the reactor affects the assurance of plug flow in the reactor. Therefore, under the process conditions of the present invention, depending on the superficial gas velocity of the gas phase feed of the main process, it is possible to ensure as much as possible a plug flow regime of the fluid in the reactor by adjusting the ratio of the maximum cross-sectional area to the minimum cross-sectional area of the tapping pipe.
Further preferably, when the superficial gas velocity of the main process gas phase feed in the reactor is less than 5mm/s, the ratio of the maximum cross-sectional area to the minimum cross-sectional area of the tapping pipe is not more than 1.5;
when the superficial gas velocity of the main process gas-phase feeding in the reactor is 5 mm/s-0.1 m/s, the ratio of the maximum cross-sectional area to the minimum cross-sectional area of the discharge pipe is 1.5-10;
when the superficial gas velocity of the main process gas-phase feed in the reactor is greater than 0.1m/s, the ratio of the maximum cross-sectional area to the minimum cross-sectional area of the tapping pipe is not less than 10.
The second purpose of the invention is to provide a gas-liquid reaction device, which comprises a hydraulic premixer and a reactor connected with the hydraulic premixer; the gas phase feeding branch is divided into partial gas phase feeding and main process gas phase feeding; in unit time, the amount of the partial gas phase feed is 1.01-2 times of the amount of the gas phase required for enabling the liquid phase feed to reach the gas phase saturated dissolution concentration; wherein:
the hydraulic premixer comprises a cylinder body, a liquid-phase feed inlet and a gas-phase feed inlet which are arranged at one end of the cylinder body, and a premixed material discharge outlet which is arranged at the other end of the cylinder body; the liquid phase feeding is connected with the liquid phase feeding hole, and the partial gas phase feeding is connected with the gas phase feeding hole; a large bubble generator, a plurality of high-speed flow channels, at least one micro-bubble generator and a plurality of low-speed flow channels are sequentially arranged in the cylinder body from the liquid-phase feed inlet and the gas-phase feed inlet to the premixed material discharge outlet; the micro-bubble generator is connected with the tail end of the high-speed flow channel;
the part of the gas-phase feed passes through the larger bubble generator and is distributed in the liquid-phase feed in the form of larger bubbles, so as to obtain a mixed feed containing the larger bubbles; then flows through the high-speed flow passage and passes through the micro-bubble generator to obtain mixed feeding containing micro-bubbles; finally, the mixture flows out of the premixed material discharge port after passing through the low-speed flow channel to obtain a premixed material;
the lower part of the reactor is provided with a main process gas-phase feed inlet, a premixed material feed inlet is arranged above the main process gas-phase feed inlet, the reactor above the premixed material feed inlet is a reaction main control unit, and a gas-phase reaction product outlet and a liquid-phase reaction product outlet are arranged on the reaction main control unit; the premixed material enters the reactor from the premixed material feed inlet, the main process gas-phase feed enters the reactor through the main process gas-phase feed inlet, and the premixed material and the main process gas-phase feed enter the reaction main control unit together;
the Reynolds number of the liquid in the high-speed flow channel is 2000-200000, so that a relatively strong liquid phase turbulent motion condition is formed; the Reynolds number of the liquid in the low-speed flow channel is 0.1-2000, so that a relatively weak liquid phase turbulent condition is formed; the ratio of the residence time of the gas in the high-speed flow channel to the residence time of the gas in the low-speed flow channel is 0.01-1; the particle Reynolds number of the fine bubbles is less than 1.
It should be noted that, as will be readily understood by those skilled in the art, the arrangement of the high-speed flow passage and the low-speed flow passage provides a relative concept that the flow velocity increases when the cross-sectional area of the flow passage becomes smaller, and the flow velocity decreases when the cross-sectional area of the flow passage becomes larger.
In the invention, the total cross-sectional area of the high-speed flow passage is smaller than that of the cylinder body at the inlet end, so that liquid-phase materials flowing at high speed are formed.
The total cross-sectional area of the low-speed flow passage is larger than that of the high-speed flow passage so as to form a low-speed flowing liquid-phase material with a lower speed relative to the speed of the high-speed fluid in the high-speed flow passage.
By the arrangement, the hydraulic premixer with the specific structure can effectively ensure that the gas phase in the premixed material entering the reactor reaches the saturation solubility, namely a thermodynamic metastable equilibrium state is reached, namely a reaction preparation state is entered in advance. Therefore, the initial reaction efficiency of the premixed material in the reaction main control unit is improved, the integral reaction conversion rate and selectivity are improved, and the volume of the reactor is obviously reduced.
In the present invention, the number of the micro-bubble generators is the flow rate of the liquid phase feed divided by the throughput of a single micro-bubble generator and rounded up. Usually, at least one micro-bubble generator is provided.
Preferably, the lower part of the reactor is sequentially provided with a gas distributor and a liquid velocity distribution unit from bottom to top, and the main process gas-phase feed enters the reactor from the main process gas-phase feed inlet and is distributed by the gas distributor; the premixed material enters the reactor from the premixed material feeding hole and is distributed by the liquid velocity distribution unit;
the liquid velocity distribution unit comprises a unit body, a unit inlet and a plurality of liquid velocity distribution outlets are formed in the unit body, the unit inlet is connected with the premixed material feeding port, discharging pipes are arranged on the liquid velocity distribution outlets, and the liquid velocity distribution outlets and the discharging pipes are respectively distributed along the cross section of the reactor; the cross-sectional area of the tapping pipe is larger closer to the side wall of the reactor, and the cross-sectional area of the tapping pipe is smaller closer to the center of the reactor; and the shorter the length of the tapping pipe closer to the side wall of the reactor, the longer the length of the tapping pipe closer to the center of the reactor; so that the flow rate of the liquid in the middle of the reactor is relatively small and the amount of the liquid is relatively small; the flow rate of the liquid close to the side wall of the reactor is relatively large, and the amount of the liquid is relatively large;
and the premixed material and the gas-phase feeding of the main process realize upward horizontal pushing flow above the liquid velocity distribution unit and upwards enter the reaction main control unit.
With the arrangement, the liquid velocity distribution unit with a specific structure can effectively ensure the plug flow state of the fluid in the reactor, thereby further improving the reaction conversion rate and the selectivity.
Preferably, the maximum cross-sectional area of the tapping pipe does not exceed 100 square centimeters; the minimum cross-sectional area of the tapping pipe is not less than 1 mm.
It is easily understood by those skilled in the art that the larger bubble generation method is an aeration or bubbling method based on the throttling principle. The micro-bubble generation method is a vortex, jet, venturi or impeller method based on the liquid shearing principle.
Preferably, the larger bubble generator is a gas distributor or a porous medium bubbler;
the micro-bubble generator is selected from one or more of a venturi tube, a jet pipe and a micropore aeration unit.
According to a preferred technical scheme of the invention, the micro-bubble generator comprises a cylindrical shell, one end of the shell is provided with a mixed material inlet, the other end of the shell is provided with a mixed material outlet, and a convergent nozzle, a throttling nozzle and a divergent nozzle are sequentially arranged between the mixed material inlet and the mixed material outlet; the convergent nozzle has an interior defining a convergent chamber, the throttle nozzle has an interior defining a throttle chamber, the divergent nozzle has an interior defining a divergent chamber and an exit chamber, and a back-mixing chamber is between the convergent nozzle and the throttle nozzle.
Preferably, the high-speed flow channels are uniformly distributed in the hydraulic premixer along the circumference of the cross section of the cylinder; the micro-bubble generators are uniformly distributed in the hydraulic premixer along the circumference of the cross section of the cylinder. The arrangement ensures that larger undissolved bubbles in the mixed material passing through the high-speed flow channel are uniformly dispersed into micro bubbles, which is beneficial to ensuring further dissolution of gas in the subsequent process and reaching or exceeding the saturated dissolution concentration.
Preferably, the gas-liquid reaction device further comprises a high-speed flow channel assembly and a low-speed flow channel assembly; the high-speed runner assembly comprises the high-speed runner and a high-speed runner limiting part, and the high-speed runner limiting part is fixedly connected with the barrel; the low-speed runner assembly comprises the low-speed runner and a low-speed runner limiting part, and the low-speed runner limiting part is fixedly connected with the barrel.
It should be noted that the amount of the portion of the gaseous material entering the hydraulic premixer should be slightly greater than the amount of material required for saturation and dissolution in the premixer liquid, and that the slight excess of gas should remain in the liquid phase in the form of fine bubbles.
Preferably, the amount of the partial gas phase feed per unit time is 1.01 to 1.3 times the amount of the gas phase required for the liquid phase feed to reach the gas phase saturation solubility concentration.
Compared with the prior art, the invention has the following beneficial technical effects:
(1) the gas-liquid reaction method which enters the reaction preparation state in advance can effectively realize the continuous feeding of the reactor, and gas-phase or liquid-phase materials do not need to be circulated, thereby reducing the circulation cost; by a specific method, part of gas phase feeding materials and liquid phase feeding materials are interacted in advance, and the kinetic energy of the liquid phase feeding materials is utilized to pre-mix the part of gas phase feeding materials and the liquid phase feeding materials before the gas phase feeding materials and the liquid phase feeding materials enter a reactor, so that gas with saturated dissolved concentration is dissolved in advance in liquid and enters a reaction preparation state in advance. When the reaction product enters the reactor, the reaction product can immediately participate in the reaction after reaching the required pressure and temperature so as to accelerate the reaction efficiency, thereby improving the gas content of the reactor, improving the conversion rate and selectivity of the reaction to be close to the equilibrium conversion rate and selectivity of the reaction, reducing the volume of the reactor, and being very suitable for medium-speed and slower gas-liquid reactions such as oxidation, hydrogenation, chlorination, alkylation and the like.
(2) The gas-liquid reaction device comprises a hydraulic premixer and a reactor. Through the hydraulic premixer comprising the large bubble generator, the high-speed flow channel, the micro-bubble generator and the low-speed flow channel, the retention time required by dissolved gas is greatly shortened, the dissolved concentration of the gas is high, the gas phase in the premixed material can reach the saturated dissolved concentration, namely, the gas phase enters the reaction preparation stage in advance, the reaction efficiency is facilitated, the gas content of the reactor can be improved, the conversion rate and the selectivity of the reaction are improved to be close to the reaction balance conversion rate and the selectivity, and the volume of the reactor can be reduced.
Drawings
FIG. 1 is a flow chart of a gas-liquid reaction apparatus in example 1.
FIG. 2 is a schematic longitudinal sectional view of a hydraulic premixer.
FIG. 3 is a schematic diagram of a hydraulic premixer in longitudinal section (high-speed flow passage assembly is in a tubular structure).
FIG. 4 is a schematic longitudinal sectional view of a fine bubble generator.
FIG. 5 is a flow chart of a gas-liquid reaction apparatus according to example 2.
Fig. 6 is a flow chart of a conventional bubble reactor apparatus.
Detailed Description
The present invention will be further described with reference to the following examples. It should be understood that the following examples are illustrative only and are not intended to limit the scope of the present invention.
Example 1A gas-liquid reaction apparatus
As shown in fig. 1 to 4, the present embodiment provides a gas-liquid reaction apparatus, comprising a hydraulic premixer 10, and a reactor 20 connected to the hydraulic premixer 10; the gas-phase feed branch V is a partial gas-phase feed V1 and a main process gas-phase feed V2; the amount of the partial gas phase feed V1 per unit time is 1.01 to 2 times the amount of the gas phase required to bring the liquid phase feed L to the gas phase saturation solubility concentration. Wherein:
the hydraulic premixer 10 comprises a cylinder 11, a liquid-phase feed inlet 12 and a gas-phase feed inlet 13 which are arranged at one end of the cylinder 11, and a premixed material discharge outlet 14 which is arranged at the other end of the cylinder 11; the liquid phase feed L is connected with the liquid phase feed inlet 12, and the partial gas phase feed V1 is connected with the gas phase feed inlet 13; a large bubble generator 15, a plurality of high-speed runners 16, a plurality of micro-bubble generators 17 and a plurality of low-speed runners 18 are sequentially arranged in the barrel 11 from the liquid-phase feed port 12 and the gas-phase feed port 13 to the premix material discharge port 14; the micro-bubble generators 17 are connected to the ends of the high-speed flow channels 16, and one micro-bubble generator 17 is connected to each end of the high-speed flow channel 16.
Said partial vapor phase feed V1 passes through said larger bubble generator 15 and is distributed as larger bubbles in said liquid phase feed L, resulting in a mixed feed containing larger bubbles; then flows through the high-speed flow passage 16 and passes through the micro-bubble generator 17 to obtain a mixed feed containing micro-bubbles; and finally, the mixture flows out of the premixed material discharge port 14 after passing through the low-speed flow passage 17 to obtain the premixed material.
A main process gas phase feed inlet 21 is formed in the lower portion of the reactor 20, a premixed material feed inlet 22 is formed above the main process gas phase feed inlet 21, the reactor 20 above the premixed material feed inlet 22 is a reaction main control unit 23, and a gas phase reaction product outlet 24 and a liquid phase reaction product outlet 27 are formed in the reaction main control unit 23; the premixed material enters the reactor 20 from the premixed material feed inlet 22, and the main process gas-phase feed V2 enters the reactor 20 through the main process gas-phase feed inlet 21 and enters the reaction main control unit 23 together with the premixed material.
The Reynolds number of the liquid in the high-speed flow channel 16 is 2000-200000, so as to form a relatively strong liquid phase turbulent motion condition; the Reynolds number of the liquid in the low-speed flow channel 18 is 0.1-2000, so that a relatively weak liquid phase turbulence condition is formed; the ratio of the residence time of the gas in the high-speed flow passage 16 to the residence time of the gas in the low-speed flow passage is 0.01 to 1.
In the present embodiment, the residence time of the gas in the high-speed flow channel 16 is 1 to 3 seconds.
In fact, the physical properties of gas and liquid under actual working conditions are greatly different from those of a daily air-water system, and larger bubbles and micro-bubbles are only different in relative size. Preferably, in the present invention, the Reynolds number of the particles
Figure BDA0002385359440000101
Bubbles smaller than 1 are considered to be micro-bubbles, i.e. the particle reynolds number of the micro-bubbles is smaller than 1. The particle reynolds number for larger bubbles is greater than or equal to 1.
In the conditions of the present invention, since most of the gas in the high-speed flow path is large bubbles and almost all of the gas in the low-speed flow path is fine bubbles, the residence time of the large bubbles corresponds to the residence time of the gas in the high-speed flow path, and the residence time of the fine bubbles corresponds to the residence time of the gas in the low-speed flow path. Namely, the ratio of the residence time of the large bubbles in the high-speed flow channel to the residence time of the fine bubbles in the low-speed flow channel is 0.01 to 1.
It should be noted that the portion of the hydraulic premixer 10 before the high-speed flow passage 16 includes a liquid inlet section in which the large bubble generator is disposed. The portion following the low-velocity flow path 18 includes a liquid outlet section. The lengths of the liquid inlet section and the liquid outlet section can be set according to actual needs as long as the residence time of the gas in the high-speed flow passage and the low-speed flow passage satisfies the above range. Thus, as will be readily understood by those skilled in the art, the total gas residence time within the hydraulic premixer 10 will vary with the length of the liquid inlet and outlet sections and the length of the micro-bubble generator.
Typically, the liquid inlet section and the liquid outlet section are short in length relative to the length of the high velocity flow channels 16 and the low velocity flow channels 18. On the premise that the gas phase concentration in the premix material can reach the saturated dissolved concentration, the liquid inlet section and the liquid outlet section are usually shortened as much as possible to reduce the cost.
The gas-liquid reaction device of the present example was used as follows:
(1) the liquid phase feed L enters the hydraulic premixer 10 through the liquid phase feed inlet 12, the partial gas phase feed V1 enters the hydraulic premixer 10 through the partial gas phase feed inlet 13, and a mixed feed containing larger gas bubbles is formed in the hydraulic premixer 10 through the larger gas bubble generator 15;
(2) then, enabling the mixed feed containing the larger bubbles to pass through a plurality of high-speed flow channels 16 which are horizontally arranged, so that the larger bubbles in the mixed feed containing the larger bubbles are quickly dissolved into a liquid phase, and obtaining the mixed feed with a large gas dissolving amount;
(3) then making the mixed feed with a large dissolved amount of gas flow into the micro-bubble generator 17 to form a mixed feed containing micro-bubbles under the action of high shear;
(4) and then enabling the mixed feed containing the micro-bubbles to pass through a plurality of horizontally arranged low-speed flow passages 18, well dissolving the mixed feed in the low-speed flow passages 18 to reach a saturated dissolving concentration, and completing premixing to obtain a premixed material.
(5) Then the premixed material comes out from the premixed material outlet 14 of the hydraulic premixer 10, then enters the reactor 20 through a feed pipe and a premixed material inlet 22 connected with the tail end of the feed pipe, the main process gas-phase feed V2 enters the bottom of the reactor 20 through the main process gas-phase feed inlet 21 and upwards enters the reaction main control unit 23 with the premixed material, and after catalytic reaction, the obtained gas-phase and liquid-phase reaction products flow out from the gas-phase reaction product outlet 24 and the liquid-phase reaction product outlet 27.
Through detection, the concentration of the gas phase in the premixed material can reach the saturated dissolved concentration.
It should be noted that, as will be readily understood by those skilled in the art, the arrangement of the high-speed flow passage 16 and the low-speed flow passage 18 is a relative concept, and when the cross-sectional area of the flow passage becomes smaller, the flow velocity increases, and when the cross-sectional area of the flow passage becomes larger, the flow velocity decreases.
In the present invention, the total cross-sectional area of the high velocity flow channels 16 is less than the cross-sectional area of the barrel at the inlet end to create relatively strong liquid phase turbulence conditions. The total cross-sectional area of the low velocity flow channels 18 is greater than the total cross-sectional area of the high velocity flow channels to create relatively weak liquid phase turbulence conditions and thereby create a low velocity flow of mixed material relative to the velocity of the high velocity fluid in the high velocity flow channels.
By the arrangement, the hydraulic premixer with the specific structure can effectively ensure that the gas phase in the premixed material entering the reactor reaches the saturated dissolved concentration, namely a thermodynamic metastable equilibrium state is reached, namely the premixed material enters a reaction preparation state in advance.
Of course, one skilled in the art can also provide other configurations of hydraulic premixers, as long as the gas phase in the premix entering the reactor is ensured to reach the saturated solution concentration.
According to some preferred embodiments of the invention, the apparatus further comprises a high-speed flow channel assembly and a low-speed flow channel assembly; the high-speed runner assembly comprises the high-speed runner 16 and a high-speed runner limiting part 161, and the high-speed runner limiting part 161 is fixedly connected with the cylinder 11; the low-speed flow passage assembly includes the low-speed flow passage 18, and a low-speed flow passage defining member 181, which is fixedly connected to the cylinder 11.
The high speed flow path defining member may take many forms known in the art. One particular form may be: including installing cylindrical component in the barrel, cylindrical component's outer wall with the inner wall clearance fit of barrel is fixed, cylindrical component's inside distribution has the through-hole of a plurality of level setting. Since the liquid-phase feed on the inlet-end side of the cylindrical member is forced to flow toward the outlet-end side of the cylindrical member along the through-hole having a smaller cross section, the flow rate of the liquid-phase feed in the through-hole is significantly increased, thereby forming a high-speed flow passage.
Of course, it is easily understood by those skilled in the art that the high-speed flow passage may be formed by other components in the prior art, as shown in fig. 3, for example, the high-speed flow passage includes a left baffle 162 and a right baffle 163 which are circular, outer walls of the left baffle 162 and the right baffle 163 are fixedly connected to an inner wall of the cylinder, a plurality of openings are correspondingly formed in the left baffle 162 and the right baffle 163, the openings are respectively connected by a tube array 164, and the high-speed flow passage 16 is formed inside the tube array 164.
The low-speed flow path defining member 181 may take various forms as in the prior art. One particular form may be: the high-speed flow passage comprises cylindrical structures which are annularly distributed along the inner wall of the barrel body 11, the outer wall of each cylindrical structure is fixedly connected with the inner wall of the barrel body 11, a Venturi tube-shaped passage is arranged inside each cylindrical structure, and the cross sectional area of a throat of each passage is larger than the total cross sectional area of the high-speed flow passage. Whereby the flow velocity of the fluid in the venturi-type passage is smaller than the flow velocity of the fluid in the high-velocity flow passage, thereby forming the low-velocity flow passage. The number of the low-speed flow passages may be one or more.
Of course, it will be readily understood by those skilled in the art that the low speed flow path may be formed by other types of components known in the art.
It is to be noted that, as shown in fig. 3, a fine bubble generator mounting plate 1712 may be provided at the end of the high-speed flow path 16, and the outer periphery of the fine bubble generator mounting plate 1712 may be fixedly connected to the inner wall of the cylinder and sealed to form a channel. The mixed material flowing out of the high-speed flow passage 16 enters a cavity between the end of the high-speed flow passage and the fine bubble generator mounting plate 1712. The micro-bubble generator mounting plate 1712 is provided with a plurality of openings, and the micro-bubble generator 17 is correspondingly mounted on the openings. The number of micro-bubble generators 17 is the flow rate of the liquid phase feed divided by the throughput of a single micro-bubble generator and rounded up. Usually, at least one micro-bubble generator is provided.
It is easily understood by those skilled in the art that the larger bubble generation method is an aeration or bubbling method based on the throttling principle. The micro-bubble generation method is a vortex, jet, venturi or impeller method based on the liquid shearing principle.
Preferably, the larger bubble generator is a gas distributor or a porous media bubbler. According to some preferred embodiments of the present invention, the larger bubble generator 15 is a tubular pipe having a plurality of openings, the diameter of the openings in the tubular pipe is 1-5 mm, and the bending radius R of the tubular pipe is about 1/4 of the inner diameter D of the hydraulic premixer.
The micro-bubble generator is selected from one or more of a venturi tube, a jet pipe and a micropore aeration unit.
As shown in fig. 4, the micro-bubble generator 17 of the present embodiment 1 includes a cylindrical housing 171, one end of the housing 171 has a mixture inlet 172, and the other end has a mixture outlet 173, and a convergent nozzle 174, a throttle nozzle 175 and a divergent nozzle 176 are sequentially disposed between the mixture inlet 172 and the mixture outlet 173; the convergent nozzle 174 defines a convergent cavity 177 in its interior, the convergent nozzle 175 defines a throttle cavity 178 in its interior, the divergent nozzle 176 defines a divergent cavity 179 and an exit cavity 1710 in its interior, and a back-mixing cavity 1711 is provided between the convergent nozzle 174 and the convergent nozzle 175.
Because the micro-bubble generator has a special structure of convergent-divergent-convergent-divergent, the high-flow-rate mixed material flowing out of the high-speed flow channel enters the micro-bubble generator from the mixed material inlet, then passes through the convergent nozzle, the highly turbulent liquid phase provides energy for bubble breaking, and gas-liquid circulation stirring is further performed in the back-mixing cavity, so that the bubbles are broken into a plurality of micro-bubbles in the back-mixing cavity, are uniformly dispersed in the liquid phase in the divergent cavity and the outlet cavity of the divergent nozzle, and finally flow out of the mixed material outlet to form the mixed material containing the micro-bubbles.
The relative dimensions of the micro-bubble generator are shown in table 1.
TABLE 1 micro-bubble Generator correlation dimensions
Size of Name of dimension Design scope
d0 Diameter of mixed material inlet 4～40mm
d1 Convergent nozzle exit diameter (0.4～0.7)d0
d2 Throttle bore diameter of throttle nozzle (0.3～0.5)d1
d3 Of divergent nozzlesDiameter of outlet cavity (0.8～1.2)d0
L1 Total length of the housing 200～800mm
L2 Length of the throttle chamber min(20mm,3×d2)
Preferably, the back mixing chamber 1711 is symmetrically located between the outer wall of the convergent nozzle 174 and the housing 171 to provide better back mixing effect to facilitate the formation of micro-fine bubbles.
According to some preferred embodiments of the present invention, the high velocity flow channels 16 are distributed in a circumferential array along the cross-section of the bowl 11 within the hydrodynamic premixer 10. The micro-bubble generators 17 are distributed in the hydraulic premixer 10 in a circumferential array along the cross-section of the barrel 11.
The arrangement enables larger undissolved bubbles in the mixed material passing through the high-speed flow channel 16 to be uniformly dispersed into micro-bubbles, which is beneficial to ensuring further dissolution of gas in the subsequent process and reaching or exceeding the saturation concentration.
It should be noted that the amount of a portion of the gaseous material entering the hydraulic premixer 10 should be greater than the amount of material required for saturation and dissolution in the premixer liquid, and that a slight excess of gas remains in the liquid phase in the form of fine bubbles.
It is further preferred that the amount of the portion of the gaseous material entering the hydraulic premixer 10 be slightly greater than the amount of material required for saturation and dissolution in the premixer liquid. The amount of the partial gas phase feed per unit time is 1.01 to 1.3 times the amount of the gas phase required for the liquid phase feed to reach the gas phase saturation dissolution concentration.
Example 2A gas-liquid reaction apparatus
As shown in fig. 5, the basic structure of the present embodiment is the same as that of embodiment 1, except that:
the lower part of the reactor 20 is sequentially provided with a gas distributor 25 and a liquid velocity distribution unit 26 from bottom to top, and the main process gas phase feed V2 enters the reactor 20 from the main process gas phase feed inlet 21 and is distributed by the gas distributor 25; the premix material enters the reactor 20 through the premix material feed inlet 22 and is distributed through the liquid velocity distribution unit 26.
The liquid velocity distribution unit 26 comprises a unit body 262, a unit inlet and a plurality of liquid velocity distribution outlets are arranged on the unit body 262, the unit inlet is connected with the premixed material feeding hole 22, a discharge pipe 261 is arranged on the liquid velocity distribution outlets, and the liquid velocity distribution outlets and the discharge pipe 261 are respectively distributed along the cross section of the reactor; the outlet pipe closer to the side wall of the reactor 20 has a larger cross-sectional area, and the outlet pipe closer to the center of the reactor 20 has a smaller cross-sectional area; and the shorter the length of the outlet pipe closer to the side wall of the reactor 20, the longer the length of the outlet pipe 261 closer to the center of the reactor 20; so that the flow rate of the liquid in the middle of the reactor 20 is relatively small and the amount of the liquid is relatively small; the flow rate of the liquid close to the side wall of the reactor 20 is relatively large, and the amount of the liquid is relatively large;
the maximum cross-sectional area of the tapping pipe 261 does not exceed 100 cm; the minimum cross-sectional area of the discharge pipe 261 is not less than 1 mm;
the premixed material and main process gas phase feed V1 realize an upward type horizontal pushing flow above the liquid velocity distribution unit 26 and upward into the reaction main control unit 23.
The gas-liquid reaction device of the present example was used as follows:
(1) the liquid phase feed L enters the hydraulic premixer 10 through the liquid phase feed inlet 12, the partial gas phase feed V1 enters the hydraulic premixer 10 through the partial gas phase feed inlet 13, and a mixed feed containing larger gas bubbles is formed in the hydraulic premixer 10 through the larger gas bubble generator 15;
(2) then, enabling the mixed feed containing the larger bubbles to pass through a plurality of high-speed flow channels 16 which are horizontally arranged, so that the larger bubbles in the mixed feed containing the larger bubbles are quickly dissolved into a liquid phase, and obtaining the mixed feed with a large gas dissolving amount;
(3) then making the mixed feed with a large dissolved amount of gas flow into the micro-bubble generator 17 to form a mixed feed containing micro-bubbles under the action of high shear;
(4) and then enabling the mixed feed containing the micro-bubbles to pass through a plurality of horizontally arranged low-speed flow passages 18, well dissolving the mixed feed in the low-speed flow passages 18 to reach a saturated dissolving concentration, and completing premixing to obtain a premixed material.
(5) The premix then exits the premix outlet 14 of the hydraulic premixer 10, then enters the reactor 20 through a feed line and from a premix inlet 22 connected to the end of the feed line, and is distributed through the liquid velocity distribution unit 26; the main process gas-phase feed V2 enters the gas distributor 25 at the bottom of the reactor 20 through the main process gas-phase feed inlet 21, and flows with the premixed material in an upward horizontal pushing manner above the liquid velocity distribution unit 26, and enters the reaction main control unit 23, and after the catalytic reaction, the obtained gas-liquid phase reaction product flows out from the gas-phase reaction product outlet 24 and the liquid-phase reaction product outlet 27.
Through detection, the concentration of the gas phase in the premixed material can reach the saturated dissolved concentration.
It should be noted that, a person skilled in the art can easily understand the specific structure of the liquid velocity distribution unit 26, for example, the liquid velocity distribution unit 26 may be a liquid distributor, and may be a serpentine concentric ring pipe, wherein a plurality of liquid velocity distribution outlets with different cross-sectional areas are formed on the serpentine concentric ring pipe, and the discharge pipes 261 with different cross-sectional areas are inserted on the liquid velocity distribution outlets.
Example 3 Effect detection
Comparative tests were conducted using the apparatus of example 1 and example 2 and a conventional bubble reactor apparatus, respectively. The reaction scheme of a conventional bubble reactor is shown in FIG. 6.
And (I) carrying out autocatalytic oxidation reaction, namely oxidizing the cumene into the cumene hydroperoxide. The process and parameters are as follows:
the cumene oxidation to cumene hydroperoxide reaction conditions: the reaction temperature is 110 ℃, the reaction pressure is 0.6MPa, and the gas-liquid ratio is 9: 1.
The test was carried out using a plexiglas cylinder with an internal diameter of 180mm and a height of 2000mm as the reactor. The reaction main control unit 23 is an empty cylinder, and is not provided with a filler or a catalyst layer.
The inner diameter D of the cylinder body of the hydraulic premixer 10 is 50mm, the total length is 2000mm, 10 high-speed flow channels are provided, and the inner diameter of each high-speed flow channel is 6 mm.
In the fine bubble generator 17, the diameter d of the mixed material inlet05mm, convergent nozzle outlet diameter d1Is 2.5mm, the diameter d of the throttling cavity of the throttling nozzle21.2mm, the diameter d of the outlet cavity of the divergent nozzle3Is 6 mm. Total length L of the housing1Is 400mm, the length L of the throttling cavity2Is 3.6 mm.
The amount of the partial gas phase feed per unit time was 1.2 times the amount of the gas phase required to bring the liquid phase feed to the gas phase saturation solubility concentration.
Under the conditions of three experimental devices, the gas flow and the liquid flow entering the reactor are kept the same, and the liquid retention time in the reactor is ensured to be 5 hours.
In embodiment 2, 4 liquid outlet pipes 261 are uniformly distributed in an inner ring of the liquid velocity distribution unit 26, 8 liquid outlet pipes 261 are uniformly distributed in an outer ring, the cross-sectional area of the liquid outlet pipe 261 in the outer ring is 0.5 square centimeter, and the cross-sectional area of the liquid outlet pipe 261 in the inner ring is 0.083 square centimeter. The ratio of the cross-sectional area of the outlet pipe 261 of the outer ring to the cross-sectional area of the outlet pipe 261 of the inner ring is 6.
The Reynolds number of the liquid in the high-speed flow passage 16 in the hydraulic premixer 10 is 4000, the Reynolds number of the liquid in the low-speed flow passage 18 is 1000, and the ratio of the residence time of the gas in the high-speed flow passage 16 to the residence time of the gas in the low-speed flow passage 18 is 0.1; the particle reynolds number of the fine bubbles was 0.2. The gas residence time in the high velocity flow channel 16 was 1.5 seconds.
In the examples 1 and 2, the superficial gas velocity of the main process gas-phase feed V2 in the reactor 20 was controlled to be 0.05 m/s. In the bubble reactor apparatus, the superficial gas velocity of the gas-phase feed in the reactor 20 was controlled to be 0.05 m/s. And detecting that the concentration of the gas phase in the premixed material reaches the saturated dissolved concentration.
The results are shown in Table 2.
TABLE 2 comparison of values of parameters of a reaction Master Unit in the Oxidation of cumene to cumene hydroperoxide
Figure BDA0002385359440000171
In this example, the gas void fraction is defined as follows: the gas phase in the reactor is a percentage of the total volume of the reactor. Total gas phase intake: total amount of gas phase entering the reactor.
As can be seen from the data in table 2, the selectivities of example 1 and example 2 were increased by 7.5% and 15%, respectively, with respect to the conversion of the bubble reactor apparatus, by 3.3% and 6.5%, respectively, and the gas contents were increased by 200% and 300%, respectively.
(II) changing relevant parameters to detect effects
(1) And the other conditions are the same as those of the (I), and the difference is that:
the amount of the partial gas phase feed per unit time was 1.01 times the amount of the gas phase required to bring the liquid phase feed to the gas phase saturation solubility concentration.
Controlling the Reynolds number of the liquid in the high-speed flow passage 16 of the hydraulic premixer 10 to be 2000, the Reynolds number of the liquid in the low-speed flow passage 18 to be 0.1, the ratio of the residence time of the gas in the high-speed flow passage 16 to the residence time of the gas in the low-speed flow passage 18 to be 0.01, and the Reynolds number of the particles of the fine bubbles to be 0.15. The gas residence time in the high velocity flow channel 16 was 1.5 seconds.
The results are shown in Table 3.
TABLE 3 comparison of values of parameters of a reaction Master Unit in the Oxidation of cumene to cumene hydroperoxide
Figure BDA0002385359440000172
As can be seen from the data in table 3, the selectivities of example 1 and example 2 were increased by 7.7% and 12.8%, respectively, relative to the conversion of the bubble reactor apparatus, by 3.2% and 4.3%, respectively, and the gas contents were increased by 205% and 281%, respectively.
(2) And the other conditions are the same as those of the (I), and the difference is that:
the amount of the partial gas phase feed per unit time was 2 times the amount of the gas phase required to bring the liquid phase feed to the gas phase saturation solubility concentration.
The liquid Reynolds number in the high-velocity flow path 16 of the hydraulic premixer 10 is controlled to 200000, the liquid Reynolds number in the low-velocity flow path 18 is controlled to 2000, the ratio of the gas residence time in the high-velocity flow path 16 to the gas residence time in the low-velocity flow path 18 is controlled to 1, and the particle Reynolds number of the fine bubbles is controlled to 0.8. The gas residence time in the high velocity flow channel 16 was 1.5 seconds.
The results are shown in Table 4.
TABLE 4 comparison of values of parameters of a reaction Master Unit in the Oxidation of cumene to cumene hydroperoxide
Figure BDA0002385359440000181
As can be seen from the data in table 4, the selectivities of example 1 and example 2 were increased by 15% and 25%, respectively, with respect to the conversion of the bubble reactor unit, by 3.3% and 5.5%, respectively, and the gas contents were increased by 183% and 275%, respectively.
As can be seen from the data in tables 2 to 4, the gas void fraction of the apparatus of examples 1 and 2 was increased by 183% to 300% based on the bubble reactor apparatus, as compared with the conventional bubble reactor apparatus, under the condition that the total gas phase intake amount was equivalent. It can be seen that the gas content in the reactor is greatly increased under the conditions of the apparatus of examples 1 and 2 and the reaction parameters of the present invention. Therefore, on the premise of achieving the same gas content, the flow of the main process gas can be greatly reduced, so that the gas-liquid ratio is reduced, and the energy consumption of a gas compressor required for conveying the gas can be reduced. According to theoretical calculation, the gas-liquid ratio can be reduced to (3-4): 1.
as is well known to those skilled in the art, in the oxidation of cumene to cumene hydroperoxide, the upper limit of the conversion rate is about 25% and the upper limit of the selectivity is about 98-99% as calculated by the conversion equilibrium. And the closer to the upper limit, the more difficult it is to improve. Compared with the conventional bubble reactor device, the conversion rate of the devices of the embodiment 1 and the embodiment 2 is improved by 7.5 to 25 percent, and the selectivity is improved by 3.2 to 6.5 percent. By adopting the device and the method, the conversion rate can be further improved to 21-25% on the basis of the traditional bubbling reactor device, and the conversion rate is already close to the upper limit of the conversion rate; the selectivity is further improved to 94-98%, and the upper limit of the conversion rate is also very close. The reactor volume can be effectively reduced if the apparatus and process of the present invention are employed under conditions that achieve the same conversion and selectivity. Therefore, the device and the method can effectively improve the conversion rate and the selectivity, and have very important significance for improving the purity of the product and the utilization rate of raw materials.
In summary, the beneficial effects of the present invention can be achieved within the scope of the apparatus and the reaction parameters of the present invention. The gas-liquid reaction method and the corresponding device can effectively realize that the gas phase in the premixed material reaches the saturated dissolved concentration, namely, the gas phase enters the reaction preparation stage in advance, and are beneficial to the reaction efficiency, so that the gas content of the reactor, the conversion rate and the selectivity of the reaction can be improved, and the volume of the reactor can be reduced.
(III) superficial gas velocity of gas-phase feeding of main process in reactor
In addition to example 2 above, in order to achieve the plug flow effect in the reactor as much as possible, the apparent gas velocity of the main process gas phase feed in the reactor was changed, and the range of the ratio of the maximum cross-sectional area to the minimum cross-sectional area of the discharge pipe of the liquid velocity distribution unit under the conditions of the experimental apparatus was found as follows:
when the superficial gas velocity of the main process gas phase feed in the reactor is less than 5mm/s, it is preferable that the ratio of the maximum cross-sectional area to the minimum cross-sectional area of the discharge pipe of the liquid velocity distribution unit is not more than 1.5. At this time, the apparent gas velocity was low, and the bubbling state was quiet.
When the superficial gas velocity of the main process gas phase feeding in the reactor is 5mm/s to 0.1m/s, the ratio of the maximum cross-sectional area to the minimum cross-sectional area of the discharge pipe 261 of the liquid velocity distribution unit is preferably 1.5 to 10. At this time, the apparent gas velocity was moderate, and a favorable plug flow state was obtained.
When the superficial gas velocity of the main process gas phase feed in the reactor is more than 0.1m/s, it is preferable that the ratio of the maximum cross-sectional area to the minimum cross-sectional area of the discharge pipe of the liquid velocity distribution unit is not less than 10. At this time, the apparent gas velocity is large, the turbulence is large, and the state is approximate to a horizontal thrust state.
Compared with the detection data of the example 2 in the table 2, under the above conditions, good gas content can be realized, the conversion rate can reach 21-25%, and the selectivity can reach 94-98%.
In summary, in the present invention, the gas-liquid premixing is performed by using the hydraulic premixer, which requires two steps. First, larger bubbles of uniform larger size are generated and stronger liquid phase turbulence is provided, which is utilized for rapid dissolution prior to moving away from the metastable equilibrium state. Then, when the metastable equilibrium state is approached, fine bubbles with uniform micro-scale are generated, a weaker liquid phase turbulence is provided, the metastable equilibrium state in the flowing process is finally reached, and the obtained premixed material reaches or exceeds the saturation concentration of a gas phase and enters a reaction preparation state in advance.
The embodiments of the present invention have been described in detail, but the embodiments are merely examples, and the present invention is not limited to the embodiments described above. Any equivalent modifications or alterations to this practice will occur to those skilled in the art and are intended to be within the scope of this invention. Accordingly, equivalent changes and modifications made without departing from the spirit and scope of the present invention should be covered by the present invention.

Claims (11)

1. The gas-liquid reaction method for entering a reaction preparation state in advance is characterized in that gas-phase feeding branches are partial gas-phase feeding and main process gas-phase feeding, a main process gas-phase feeding hole is formed in the lower portion of a reactor, a premixed material feeding hole is formed above the main process gas-phase feeding hole, and the reactor above the premixed material feeding hole is a reaction main control unit; the method comprises the following steps:
(1) forming larger bubbles in the liquid-phase feeding material by the partial gas-phase feeding material to obtain mixed feeding material containing the larger bubbles;
(2) forming a relatively strong liquid phase turbulence on the mixed feed containing the larger bubbles so as to rapidly dissolve the larger bubbles in the mixed feed containing the larger bubbles into a liquid phase to obtain a mixed feed with a large gas dissolving amount;
(3) forming the undissolved large bubbles in the mixed feed with a large gas dissolving amount into micro bubbles under a high shearing condition to obtain the mixed feed containing the micro bubbles;
(4) forming a relatively weak liquid phase turbulence in the mixed feed containing the micro-bubbles so as to further dissolve the micro-bubbles into the liquid phase feed to obtain the premix material;
(5) enabling the premixed material to enter the reactor through the premixed material feeding hole, enabling the main process gas phase feeding to enter the reactor through the main process gas phase feeding hole, and enabling the premixed material and the premixed material to enter the reaction main control unit to react upwards;
under the relatively strong liquid phase turbulence condition, the Reynolds number of the liquid is 2000-200000;
under the relatively weak liquid phase turbulence condition, the Reynolds number of the liquid is 0.1-2000;
the particle Reynolds number of the micro-bubbles is less than 1;
the amount of the partial gas phase feed is 1.01 to 2 times of the amount of the gas phase required for the liquid phase feed to reach the gas phase saturated dissolution concentration per unit time.
2. The gas-liquid reaction method for entering the reaction preparation state in advance as recited in claim 1, wherein the main process gas phase feed and the premixed material enter the reaction main control unit together in a plug flow manner to react.
3. The gas-liquid reaction method of entering into the reaction preparation state in advance as set forth in claim 2, wherein the reactor further comprises a gas distributor connected to the main process gas phase feed port, and a liquid velocity distribution unit connected to the premix feed port; wherein:
the liquid velocity distribution unit comprises a unit body, a unit inlet and a plurality of liquid velocity distribution outlets are formed in the unit body, the unit inlet is connected with the premixed material feeding port, discharging pipes are arranged on the liquid velocity distribution outlets, and the liquid velocity distribution outlets and the discharging pipes are respectively distributed along the cross section of the reactor; the cross-sectional area of the tapping pipe is larger closer to the side wall of the reactor, and the cross-sectional area of the tapping pipe is smaller closer to the center of the reactor; and the shorter the length of the tapping pipe closer to the side wall of the reactor, the longer the length of the tapping pipe closer to the center of the reactor; so that the flow rate of the liquid in the middle of the reactor is relatively small and the amount of the liquid is relatively small; the flow rate of the liquid close to the side wall of the reactor is relatively large, and the amount of the liquid is relatively large;
and the premixed material and the gas-phase feeding of the main process realize upward horizontal pushing flow above the liquid velocity distribution unit and upwards enter the reaction main control unit.
4. The gas-liquid reaction method of bringing into reaction readiness in advance as set forth in claim 3, wherein when the superficial gas velocity of the main process gas phase feed in the reactor is less than 5mm/s, the ratio of the maximum cross-sectional area to the minimum cross-sectional area of the tapping pipe is not more than 1.5;
when the superficial gas velocity of the main process gas phase feeding in the reactor is 5 mm/s-0.1 m/s, the ratio of the maximum cross-sectional area to the minimum cross-sectional area of the discharge pipe is 1.5-10;
when the superficial gas velocity of the main process gas-phase feed in the reactor is greater than 0.1m/s, the ratio of the maximum cross-sectional area to the minimum cross-sectional area of the tapping pipe is not less than 10.
5. The gas-liquid reaction device is characterized by comprising a hydraulic premixer and a reactor connected with the hydraulic premixer; the gas phase feeding branch is divided into partial gas phase feeding and main process gas phase feeding; wherein:
the hydraulic premixer comprises a cylinder body, a liquid-phase feed inlet and a gas-phase feed inlet which are arranged at one end of the cylinder body, and a premixed material discharge outlet which is arranged at the other end of the cylinder body; the liquid phase feeding is connected with the liquid phase feeding hole, and the partial gas phase feeding is connected with the gas phase feeding hole; a large bubble generator, a plurality of high-speed flow channels, at least one micro-bubble generator and a plurality of low-speed flow channels are sequentially arranged in the cylinder body from the liquid-phase feed inlet and the gas-phase feed inlet to the premixed material discharge outlet;
the part of the gas-phase feed passes through the larger bubble generator and is distributed in the liquid-phase feed in the form of larger bubbles, so as to obtain a mixed feed containing the larger bubbles; then flows through the high-speed flow passage and passes through the micro-bubble generator to obtain mixed feeding containing micro-bubbles; finally, the mixture flows out of the premixed material discharge port after passing through the low-speed flow channel to obtain a premixed material;
the lower part of the reactor is provided with a main process gas-phase feed inlet, a premixed material feed inlet is arranged above the main process gas-phase feed inlet, the reactor above the premixed material feed inlet is a reaction main control unit, and a gas-phase reaction product outlet and a liquid-phase reaction product outlet are arranged on the reaction main control unit; the premixed material enters the reactor from the premixed material feed inlet, the main process gas-phase feed enters the reactor through the main process gas-phase feed inlet, and the premixed material and the main process gas-phase feed enter the reaction main control unit together;
the Reynolds number of the liquid in the high-speed flow channel is 2000-200000, so that a relatively strong liquid phase turbulent motion condition is formed; the Reynolds number of the liquid in the low-speed flow channel is 0.1-2000, so that a relatively weak liquid phase turbulent condition is formed; the ratio of the residence time of the gas in the high-speed flow channel to the residence time of the gas in the low-speed flow channel is 0.01-1; the particle Reynolds number of the micro-bubbles is less than 1;
the amount of the partial gas phase feed is 1.01 to 2 times of the amount of the gas phase required for the liquid phase feed to reach the gas phase saturated dissolution concentration per unit time.
6. The gas-liquid reaction device according to claim 5, wherein a gas distributor and a liquid velocity distribution unit are sequentially arranged at the lower part of the reactor from bottom to top, and the main process gas phase feed enters the reactor from the main process gas phase feed inlet and is distributed by the gas distributor; the premixed material enters the reactor from the premixed material feeding hole and is distributed by the liquid velocity distribution unit;
the liquid velocity distribution unit comprises a unit body, a unit inlet and a plurality of liquid velocity distribution outlets are formed in the unit body, the unit inlet is connected with the premixed material feeding port, discharging pipes are arranged on the liquid velocity distribution outlets, and the liquid velocity distribution outlets and the discharging pipes are respectively distributed along the cross section of the reactor; the cross-sectional area of the tapping pipe is larger closer to the side wall of the reactor, and the cross-sectional area of the tapping pipe is smaller closer to the center of the reactor; and the shorter the length of the tapping pipe closer to the side wall of the reactor, the longer the length of the tapping pipe closer to the center of the reactor; so that the flow rate of the liquid in the middle of the reactor is relatively small and the amount of the liquid is relatively small; the flow rate of the liquid close to the side wall of the reactor is relatively large, and the amount of the liquid is relatively large;
and the premixed material and the gas-phase feeding of the main process realize upward horizontal pushing flow above the liquid velocity distribution unit and upwards enter the reaction main control unit.
7. The gas-liquid reaction device as recited in claim 5, wherein the larger bubble generator is a gas distributor or a porous medium bubbler; the micro-bubble generator is selected from one or more of a venturi tube, a jet pipe and a micropore aeration unit.
8. The gas-liquid reaction device according to claim 7, wherein the micro-bubble generator comprises a cylindrical housing, one end of the housing is provided with a mixed material inlet, the other end of the housing is provided with a mixed material outlet, and a convergent nozzle, a throttle nozzle and a divergent nozzle are sequentially arranged between the mixed material inlet and the mixed material outlet; the convergent nozzle has an interior defining a convergent chamber, the throttle nozzle has an interior defining a throttle chamber, the divergent nozzle has an interior defining a divergent chamber and an exit chamber, and a back-mixing chamber is between the convergent nozzle and the throttle nozzle.
9. The gas-liquid reaction device according to claim 5, wherein the high-speed flow passages are circumferentially and uniformly distributed along a cross section of the cylinder in the hydraulic premixer; the micro-bubble generators are uniformly distributed in the hydraulic premixer along the circumference of the cross section of the cylinder.
10. The gas-liquid reaction device according to claim 5, further comprising a high-speed flow passage assembly and a low-speed flow passage assembly; the high-speed runner assembly comprises the high-speed runner and a high-speed runner limiting part, and the high-speed runner limiting part is fixedly connected with the barrel; the low-speed runner assembly comprises the low-speed runner and a low-speed runner limiting part, and the low-speed runner limiting part is fixedly connected with the barrel.
11. The gas-liquid reaction device according to claim 5, wherein the amount of the partial gas-phase feed per unit time is 1.01 to 1.3 times the amount of the gas-phase feed required for the liquid-phase feed to reach the gas-phase saturated dissolved concentration.
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