阅读说明：本技术 一种气相催化水合法制备乙二醇的反应系统及方法 (Reaction system and method for preparing ethylene glycol by gas-phase catalytic hydration method ) 是由 张志炳 周政 李磊 张锋 孟为民 王宝荣 杨高东 罗华勋 田洪舟 杨国强 曹宇 于 2020-12-03 设计创作，主要内容包括：本发明提供了一种气相催化水合法制备乙二醇的反应系统,包括：水合反应精馏器和蒸发塔；所述水合反应精馏器侧面设置有微界面机组,所述微界面机组通过进料管道与所述水合反应精馏器相连,在相连的进料口处设置有用于使原料均匀分布的导向圆盘；所述微界面机组由若干个外置微界面发生器构成,所述微界面机组同时连接有气体输送管道以及水输送管道,以用于将环氧乙烷和水同时通入到微界面机组内部以用于破碎环氧乙烷气体为微米级别的微气泡。本发明的反应系统设备组件少、占地面积小、能耗低、成本低、安全性高、反应可控,原料转化率高,值得广泛推广应用。(The invention provides a reaction system for preparing ethylene glycol by a gas-phase catalytic hydration method, which comprises the following steps: a hydration reaction rectifier and an evaporation tower; a micro interface unit is arranged on the side surface of the hydration reaction rectifier, the micro interface unit is connected with the hydration reaction rectifier through a feed pipe, and a guide disc for uniformly distributing raw materials is arranged at a feed inlet connected with the micro interface unit; the micro-interface unit is composed of a plurality of external micro-interface generators, and is simultaneously connected with a gas conveying pipeline and a water conveying pipeline so as to simultaneously introduce ethylene oxide and water into the interior of the micro-interface unit and break the ethylene oxide gas into micro-bubbles at the micron level. The reaction system has the advantages of few equipment components, small occupied area, low energy consumption, low cost, high safety, controllable reaction and high raw material conversion rate, and is worthy of wide popularization and application.)

1. A reaction system for preparing ethylene glycol by a gas-phase catalytic hydration method is characterized by comprising: a hydration reaction rectifier and an evaporation tower;

a micro interface unit is arranged on the side surface of the hydration reaction rectifier, the micro interface unit is connected with the hydration reaction rectifier through a feed pipe, and a guide disc for uniformly distributing raw materials is arranged at a feed inlet connected with the micro interface unit; the micro-interface unit is composed of a plurality of external micro-interface generators, and is simultaneously connected with a gas conveying pipeline and a water conveying pipeline for simultaneously introducing ethylene oxide and water into the micro-interface unit for breaking the ethylene oxide gas into micro-bubbles at a micron level;

the bottom of the hydration reaction rectifier is provided with an ethylene glycol outlet for discharging ethylene glycol product, the ethylene glycol discharged from the ethylene glycol outlet is divided into two gas-liquid material flows through a first reboiler, the gas-phase material flow is circularly returned to the hydration reaction rectifier, and the liquid-phase material flow flows into the evaporation tower along a material-liquid channel for gas-liquid separation.

2. The reaction system for preparing ethylene glycol by the gas-phase catalytic hydration method according to claim 1, wherein the external micro-interface generators in the micro-interface unit are sequentially arranged from top to bottom.

3. The reaction system for preparing the ethylene glycol through the gas-phase catalytic hydration method according to claim 1, wherein a built-in micro-interface generator is arranged inside the hydration reaction rectifier, and the gas-phase material flow returned by the first reboiler enters the hydration reaction rectifier through the built-in micro-interface generator.

4. The reaction system for preparing ethylene glycol by the gas-phase catalytic hydration method according to claim 1, wherein the guide disc is tapered; a plurality of guide holes are uniformly distributed on the guide disc, and the diameters of the guide holes are sequentially increased along the direction away from the feed inlet.

5. The reaction system for preparing ethylene glycol by the gas phase catalytic hydration method according to claim 1, wherein the evaporation tower is connected with a dehydration tower, the material coming out from the bottom of the evaporation tower is divided into two gas-liquid streams by a second reboiler, the gas-phase stream is circulated back to the evaporation tower, and the liquid-phase stream enters the dehydration tower for further separation and purification.

6. The reaction system for preparing the ethylene glycol by the gas-phase catalytic hydration method according to claim 5, wherein a refining tower is connected with the dehydration tower, and is used for further refining and purifying materials discharged from the dehydration tower.

7. The reaction system for preparing the ethylene glycol by the gas-phase catalytic hydration method according to claim 6, wherein the refining tower is connected with a product storage tank, and the product flow refined by the refining tower is stored in the product storage tank.

8. The reaction system for preparing ethylene glycol by the gas-phase catalytic hydration method according to claim 6, wherein a second condenser is connected to the top of the refining tower, and the gas-phase component at the top of the refining tower is condensed by the second condenser and then refluxed to the top of the refining tower.

9. The reaction method of the reaction system for producing ethylene glycol by the gas-phase catalytic hydration method according to any one of claims 1 to 8, characterized by comprising the steps of:

mixing ethylene oxide and water, dispersing and crushing the mixture through a micro interface, carrying out catalytic hydration reaction, and then carrying out separation, purification and refining to obtain ethylene glycol; the temperature of the catalytic hydration reaction is 150 ℃ and 165 ℃, and the pressure is 0.5-0.8 MPa.

10. The reaction method of claim 9, wherein the catalyst for catalyzing the hydration reaction is any one or more of potassium carbonate, potassium bicarbonate, aluminum perchlorate and aluminum trifluoromethanesulfonate.

Technical Field

The invention relates to the field of ethylene glycol preparation, in particular to a reaction system and a method for preparing ethylene glycol by a gas-phase catalytic hydration method.

Background

Ethylene glycol is important aliphatic diol, has wide application, and is mainly used for producing polyester resin including fiber, film and engineering plastic. It can also be directly used as a cooling agent and an antifreezing agent, and is also an indispensable substance for producing products such as alkyd resin, plasticizer, paint, adhesive, surfactant, explosive, capacitor electrolyte and the like.

Ethylene oxide is used as a raw material to prepare ethylene glycol, and the method mainly comprises two methods, namely a direct hydration method, namely the ethylene oxide directly reacts with water under certain conditions to generate ethylene glycol, the reaction can be carried out without a catalyst, and the method comprises two methods, namely catalytic hydration and non-catalytic hydration; the other method is an ethylene carbonate method, namely ethylene oxide firstly reacts with CO2 to generate ethylene carbonate under the action of a catalyst, and then ethylene glycol is generated by hydrolysis.

At present, the non-catalytic hydration process of a direct hydration method, also called pressurized hydration, is adopted for industrially preparing the ethylene glycol, a catalyst is not used in the method, the molar ratio of reaction feed water to ethylene oxide (hereinafter referred to as water ratio) is 20-25: 1, the reaction temperature is 150-200 ℃, the reaction pressure is 0.8-2.0 MPa, the conversion rate of the ethylene oxide is close to 100%, and the selectivity of the ethylene glycol is about 90%. In the reaction, because the reactivity of ethylene glycol and ethylene oxide is higher than that of water and ethylene oxide, unconverted ethylene oxide continues to react with the product ethylene glycol to generate diethylene glycol, triethylene glycol and other byproducts, so that a method of large excess of water is often adopted in industry to improve the selectivity of ethylene glycol. The greatest disadvantage of this process is that a large amount of energy is used in the production to evaporate more than 85% of the water in the product. For example, in the purification step of ethylene glycol product, when the feed water ratio is 20, about 19 times of the useless water of ethylene glycol is removed by evaporation, and the required heat is 170 kilocalories per mole of ethylene glycol, which means that about 5.5 tons of steam is consumed for producing 1 ton of ethylene glycol, resulting in huge energy consumption and high production cost of the method. Therefore, in order to reduce the reaction water ratio and reduce the energy consumption, researchers at home and abroad compete to develop the research on various ethylene oxide catalytic hydration reaction technologies.

In order to overcome the defects of the non-catalytic hydration process of the ethylene oxide, researchers at home and abroad compete to develop the research on preparing the ethylene glycol by catalytic hydration of the ethylene oxide, and the reduction of energy consumption and production cost are expected.

In the early method for producing ethylene glycol by catalytic hydration, inorganic acid or alkali catalyst is adopted, but the homogeneous hydration catalyst is difficult to separate because of introducing catalyst components influencing the product quality, and the catalyst has large dosage and corrodes equipment, so the acid-base catalytic hydration process in the traditional sense is eliminated and is not used any more.

RU2001901C1 adopts a series process of multiple displacement flow reactors, and uses quaternary ammonium polystyrene anion exchanger containing bicarbonate as catalyst, which can ensure the ethylene oxide conversion rate close to 100%, and the selectivity is improved compared with single displacement flow reactor, but the catalyst activity is low, the reactor volume is too large, the equipment investment is large, and the production cost is high.

US5488184 discloses an ethylene oxide hydrated anion exchange resin catalyst. The reaction is carried out at the temperature of 80-200 ℃, the pressure of 200-3000 KPa and the water ratio of 1-15: 1, the conversion rate of the ethylene oxide is close to 100%, and the selectivity of the ethylene glycol is 95%. However, the catalyst system has the obvious defects that the resin catalyst has poor heat resistance, and the expansion condition of the catalyst is severe within the hydration reaction temperature range, so that the pressure drop of a reactor bed layer is increased quickly, and the service life of the catalyst is short.

CN1237953A discloses a method for producing dihydric alcohol, which is to produce dihydric alcohol in at least two multi-effect evaporation tower reactors, wherein the towers are connected in series, and the process of evaporation, absorption and reaction is coordinated, and the method is particularly suitable for preparing ethylene glycol by the reaction of ethylene oxide and water, and the yield of the ethylene glycol is about 90 percent. The catalyst of the reaction zone is selected from the group consisting of aluminosilicate zeolites, amorphous aluminosilicates, and acidic ion exchange resins. Compared with a single-effect evaporation tower reactor, the multi-effect evaporation tower reactor system used in the method has the advantages that the energy efficiency is improved, but the catalyst is required to have longer service life, and the loading workload of the catalyst is large.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

The first purpose of the invention is to provide a reaction system for preparing ethylene glycol by a gas-phase catalytic hydration method, which is characterized in that a micro-interface unit is arranged outside a hydration reaction rectifier, so that ethylene oxide is crushed into micro-bubbles before the ethylene oxide and water carry out catalytic hydration reaction, the phase boundary mass transfer area between the ethylene oxide and the water is increased, the water required by the reaction is reduced, the reaction efficiency is increased, the addition amount of a catalyst is reduced, the energy consumption is low, and the production cost is low.

The second purpose of the invention is to provide a reaction method for preparing ethylene glycol by adopting the reaction system, the ethylene glycol obtained by the reaction has high purity and wide application, the application range of the ethylene glycol is improved, and the method is worthy of wide popularization and application.

In order to achieve the above purpose of the present invention, the following technical solutions are adopted:

the invention provides a reaction system for preparing ethylene glycol by a gas-phase catalytic hydration method, which comprises the following steps: a hydration reaction rectifier and an evaporation tower; a micro interface unit is arranged on the side surface of the hydration reaction rectifier, the micro interface unit is connected with the hydration reaction rectifier through a feed pipe, and a guide disc for uniformly distributing raw materials is arranged at a feed inlet connected with the micro interface unit; the micro-interface unit is composed of a plurality of external micro-interface generators, and is simultaneously connected with a gas conveying pipeline and a water conveying pipeline for simultaneously introducing ethylene oxide and water into the micro-interface unit for breaking the ethylene oxide gas into micro-bubbles at a micron level;

the bottom of the hydration reaction rectifier is provided with an ethylene glycol outlet for discharging ethylene glycol product, the ethylene glycol discharged from the ethylene glycol outlet is divided into two gas-liquid material flows through a first reboiler, the gas-phase material flow is circulated and returned to the hydration reaction rectifier, and the liquid-phase material flow flows into the evaporation tower along a material-liquid channel for gas-liquid separation.

In the prior art, the industrial catalytic hydration method for producing ethylene glycol uses inorganic acid or alkali as a catalyst, for example, sulfuric acid or phosphoric acid as the catalyst, ethylene oxide can be completely converted, the yield of ethylene glycol is about 90%, but the inorganic acid catalyst causes corrosion to equipment and pollutes the environment; when inorganic base is used as the catalyst, the generation of some high molecular weight by-products is easily promoted, and the product selectivity is reduced. Patent RU2001901C1 uses a series process of multiple displacement flow reactors, and uses quaternary ammonium polystyrene anion exchanger containing bicarbonate as catalyst to drive reaction, patent US5488184 discloses an ethylene oxide hydrated anion exchange resin catalyst, and uses resin catalyst to drive reaction, patent CN1237953A discloses a method for producing dihydric alcohol, and uses aluminosilicate zeolite, amorphous aluminosilicate and acidic ion exchange resin as catalyst to drive reaction. Therefore, in the prior art, a large amount of catalyst is needed to promote the reaction, the dependence on the catalyst is large, and the production cost is high.

According to the reaction system for preparing the ethylene glycol, the micro-interface unit is arranged in the hydration reaction rectifier, so that the ethylene oxide entering the hydration reaction rectifier is dispersed and crushed into micro bubbles, the mass transfer effect is improved, the mass transfer rate is greatly improved, the hydrogenation reaction temperature and pressure are reduced, and the dependence on a catalyst is reduced.

Preferably, the external micro-interface generators in the micro-interface unit are sequentially arranged from top to bottom. The number of the external micro-interface generators in the micro-interface unit is three. The arrangement of the external micro-interface generators can improve the dispersion and crushing efficiency of raw materials, and further improve the reaction rate.

Preferably, a built-in micro-interface generator is arranged in the hydration reaction rectifier, and the gas phase material flow returned by the first reboiler enters the hydration reaction rectifier through the built-in micro-interface generator. The gas phase material flows through the micro interface generator to be dispersed and broken into micro bubbles, and the unreacted light component returns to the hydration reaction rectifier to continue the reaction.

Preferably, the guide disc is conical; a plurality of guide holes are uniformly distributed on the guide disc, and the diameters of the guide holes are sequentially increased along the direction away from the feed inlet. Through setting up the direction disc, can make the microbubble that micro-interface unit produced distribute evenly.

Preferably, the guide curve of the guide disc is any one of a hyperbolic curve, a parabolic curve, a two-segment broken line and a logarithmic curve.

The micro-interface unit is arranged outside the hydration reaction rectifier, wherein the external micro-interface generator is arranged in a mode of being sequentially arranged from top to bottom, ethylene oxide enters the internal part of the external micro-interface generator through the gas conveying pipeline, meanwhile, water enters the external micro-interface generator through the water conveying pipeline, and the water is taken as a medium to be closely contacted with the entering ethylene oxide, so that the ethylene oxide can be fully dispersed and crushed before entering the hydration reaction rectifier, and the micro-interface unit is equivalent to form a one-time micro-interface system on the external micro-interface generator, so that the gas phase is fully dispersed and crushed inside the external micro-interface generator on the premise of taking the liquid phase as the medium, and therefore, three external micro-interface generators connected in parallel are adopted, and the dispersing and crushing efficiency is improved. The parallel connection mode can ensure that the gas phase and the liquid phase simultaneously and uniformly pass through the three micro-interface generators, thereby ensuring certain timeliness and improving the reaction efficiency.

The invention is also provided with a guide disc at the feed inlet, a plurality of guide holes are uniformly distributed on the guide disc, and the diameters of the guide holes are sequentially increased along the direction far away from the feed inlet. The guide disc can change the running direction of the micro bubbles to ensure that the bubbles are uniformly distributed; meanwhile, the guide holes in the guide disc can also play a role in redistribution of the microbubbles, so that the microbubbles are more uniformly distributed in the hydration reaction rectifier, and the reaction is favorably carried out. Therefore, the micro-interface generator set is combined with the guide disc to be applied, so that the application effect of the micro-interface generator is improved. When the microbubbles are dispersed from the micro-interface generator and then are in a disordered state, the microbubbles and other raw materials can be fully fused only by guiding the formed microbubbles through corresponding equipment to a certain degree, and therefore the reaction efficiency is improved.

The bottom of the hydration reaction rectifier is also provided with a built-in micro-interface generator, gas phase material flow returned by the first reboiler can be fully dispersed and crushed in the built-in micro-interface generator, and residual water in the hydration reaction rectifier is a medium. The reason why the built-in micro-interface generator is arranged at the bottom is that the reaction of raw materials is faster, the residual medium water at the bottom of the hydration reaction rectifier is less, and the dispersion crushing condition of the built-in micro-interface generator can be met only by arranging the built-in micro-interface generator at the bottom. The outlet of the built-in micro-interface reactor is also provided with a guide disc for the uniform distribution of the generated micro-bubbles in the bottom medium of the hydration reaction rectifier, which is beneficial to improving the reaction rate.

It will be appreciated by those skilled in the art that the micro-interface generator used in the present invention is described in the prior patents of the present inventor, such as the patents of application nos. CN201610641119.6, 201610641251.7, CN201710766435.0, CN106187660, CN105903425A, CN109437390A, CN205833127U and CN 207581700U. The detailed structure and operation principle of the micro bubble generator (i.e. micro interface generator) is described in detail in the prior patent CN201610641119.6, which describes that "the micro bubble generator comprises a body and a secondary crushing member, wherein the body is provided with a cavity, the body is provided with an inlet communicated with the cavity, the opposite first end and second end of the cavity are both open, and the cross-sectional area of the cavity decreases from the middle of the cavity to the first end and second end of the cavity; the secondary crushing member is disposed at least one of the first end and the second end of the cavity, a portion of the secondary crushing member is disposed within the cavity, and an annular passage is formed between the secondary crushing member and the through holes open at both ends of the cavity. The micron bubble generator also comprises an air inlet pipe and a liquid inlet pipe. "the specific working principle of the structure disclosed in the application document is as follows: liquid enters the micro-bubble generator tangentially through the liquid inlet pipe, and gas is rotated at a super high speed and cut to break gas bubbles into micro-bubbles at a micron level, so that the mass transfer area between a liquid phase and a gas phase is increased, and the micro-bubble generator in the patent belongs to a pneumatic micro-interface generator.

In addition, the first patent 201610641251.7 describes that the primary bubble breaker has a circulation liquid inlet, a circulation gas inlet and a gas-liquid mixture outlet, and the secondary bubble breaker communicates the feed inlet with the gas-liquid mixture outlet, which indicates that the bubble breakers all need to be mixed with gas and liquid, and in addition, as can be seen from the following drawings, the primary bubble breaker mainly uses the circulation liquid as power, so that the primary bubble breaker belongs to a hydraulic micro-interface generator, and the secondary bubble breaker simultaneously introduces the gas-liquid mixture into an elliptical rotating ball for rotation, thereby realizing bubble breaking in the rotating process, so that the secondary bubble breaker actually belongs to a gas-liquid linkage micro-interface generator. In fact, the micro-interface generator is a specific form of the micro-interface generator, whether it is a hydraulic micro-interface generator or a gas-liquid linkage micro-interface generator, however, the micro-interface generator adopted in the present invention is not limited to the above forms, and the specific structure of the bubble breaker described in the prior patent is only one of the forms that the micro-interface generator of the present invention can adopt.

Furthermore, the prior patent 201710766435.0 states that the principle of the bubble breaker is that high-speed jet flows are used to achieve mutual collision of gases, and also states that the bubble breaker can be used in a micro-interface strengthening reactor to verify the correlation between the bubble breaker and the micro-interface generator; moreover, in the prior patent CN106187660, there is a related description on the specific structure of the bubble breaker, see paragraphs [0031] to [0041] in the specification, and the accompanying drawings, which illustrate the specific working principle of the bubble breaker S-2 in detail, the top of the bubble breaker is a liquid phase inlet, and the side of the bubble breaker is a gas phase inlet, and the liquid phase coming from the top provides the entrainment power, so as to achieve the effect of breaking into ultra-fine bubbles, and in the accompanying drawings, the bubble breaker is also seen to be of a tapered structure, and the diameter of the upper part is larger than that of the lower part, and also for better providing the entrainment power for the liquid phase. Since the micro-interface generator was just developed in the early stage of the prior patent application, the micro-interface generator was named as a micro-bubble generator (CN201610641119.6), a bubble breaker (201710766435.0) and the like in the early stage, and is named as a micro-interface generator in the later stage along with the continuous technical improvement, and the micro-interface generator in the present invention is equivalent to the micro-bubble generator, the bubble breaker and the like in the prior art, and has different names.

In summary, the micro-interface generator of the present invention belongs to the prior art, although some bubble breakers belong to the type of pneumatic bubble breakers, some bubble breakers belong to the type of hydraulic bubble breakers, and some bubble breakers belong to the type of gas-liquid linkage bubble breakers, the difference between the types is mainly selected according to the different specific working conditions, and in addition, the connection between the micro-interface generator and the reactor and other equipment, including the connection structure and the connection position, is determined according to the structure of the micro-interface generator, which is not limited.

Preferably, the evaporation tower is connected with a dehydration tower, the material from the bottom of the evaporation tower is divided into a gas-liquid two-stream by a second reboiler, the gas-phase stream is circulated and returned to the evaporation tower, and the liquid-phase stream enters the dehydration tower for further separation and purification. The evaporation tower and the dehydration tower can dehydrate the product, and the product purity is improved.

Preferably, the dehydration tower is connected with a refining tower for further refining and purifying the material discharged from the dehydration tower. Furthermore, the refining tower is connected with a product storage tank, and the product flow refined by the refining tower is stored in the product storage tank. The refining tower is used for refining and purifying the ethylene glycol, and the ethylene glycol is output to a product storage tank for storage after the purification is finished.

Preferably, a third reboiler is arranged between the dehydration tower and the refining tower; and a fourth reboiler is arranged in the refining tower and the product storage tank. The third reboiler and the fourth reboiler gasify part of the material passing through, the liquid phase is continuously output, and the gas phase flows back, so that the material can be further purified.

Preferably, the top of the hydration reaction rectifier is connected with a second reboiler, the top of the evaporation tower is connected with a third reboiler, and the top of the dehydration tower is connected with a fourth reboiler, so that the steam of the previous stage can be used as the heat source of the reboiler of the next stage, and the utilization efficiency of energy is improved.

Preferably, the top of the refining tower is connected with a second condenser, and the gas-phase components at the top of the refining tower are condensed by the second condenser and then refluxed to the top of the refining tower. The top of the refining tower is totally refluxed, and the gaseous glycol is condensed into a liquid phase by a condenser and returns to the refining tower through a reflux pipeline.

Preferably, the top of the hydration reaction rectifier is provided with an additive channel for adding catalyst. By adding an appropriate amount of catalyst, the reaction rate can be further increased.

Preferably, the top of the hydration reaction rectifier is connected with a first condenser, unreacted water and ethylene oxide are condensed by the first condenser and then flow back to the hydration reaction rectifier for continuous reaction, and the utilization efficiency of raw materials is improved.

The invention also provides a reaction method of the reaction system for preparing the ethylene glycol by applying the gas-phase catalytic hydration method, which comprises the following steps:

mixing ethylene oxide and water, dispersing and crushing the mixture through a micro interface, carrying out catalytic hydration reaction, and then carrying out separation, purification and refining to obtain ethylene glycol; the temperature of the catalytic hydration reaction is 150 ℃ and 165 ℃, and the pressure is 0.5-0.8 MPa.

Preferably, the catalyst for catalyzing the hydration reaction is any one or a mixture of more of potassium carbonate, potassium bicarbonate, aluminum perchlorate and aluminum trifluoromethanesulfonate.

Specifically, the preparation method comprises the steps of arranging the micro-interface unit connected with the gas conveying pipeline and the water conveying pipeline outside the hydration reaction rectifier, enabling the micro-interface unit to crush the ethylene oxide into micro-bubbles with the diameter of more than or equal to 1 mu m and less than 1mm before the ethylene oxide and raw material water are subjected to hydration reaction, enabling the ethylene oxide to be in contact with the water in the micro-bubbles state, increasing the phase boundary mass transfer area between the ethylene oxide and the water in the hydration reaction process, fully mixing the ethylene oxide and the water, and then performing the hydration reaction, so that the amount of water and a catalyst required by the reaction is reduced, and the reaction efficiency is improved.

The ethylene glycol product obtained by the reaction method has good quality and high yield. And the preparation method has the advantages of low reaction temperature, greatly reduced pressure and remarkably reduced cost.

Compared with the prior art, the invention has the beneficial effects that:

(1) according to the reaction system, the micro-interface unit connected with the gas conveying pipeline and the water conveying pipeline is arranged on the outer side of the hydration reaction rectifier, so that before the ethylene oxide and raw material water are subjected to hydration reaction, the micro-interface unit breaks the ethylene oxide into micro-bubbles with the diameter of more than or equal to 1 mu m and less than 1mm, the ethylene oxide is contacted with the water in the micro-bubbles state, the phase boundary mass transfer area between the ethylene oxide and the water in the hydration reaction process is increased, the ethylene oxide and the water are fully mixed and then subjected to the hydration reaction, the amount of water and a catalyst required by the reaction is reduced, and the reaction efficiency is improved.

(2) The reaction method is simple and convenient to operate, the ethylene glycol obtained by the reaction has high purity and wide application, the application range of the ethylene glycol is improved, and the method is worthy of wide popularization and application.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

fig. 1 is a schematic structural diagram of a reaction system for preparing ethylene glycol by a vapor-phase catalytic hydration method according to an embodiment of the present invention.

Wherein:

10-a hydration reaction rectifier; 101-a dosing channel;

102-a first condenser; 103-a guiding disc;

104-a built-in micro-interface generator; 105-a glycol outlet;

106 — a first reboiler; 107-feed inlet;

108-a feed conduit; 20-an evaporation tower;

201-material liquid channel; 202-a second reboiler;

30-a dehydration column; 301-a third reboiler;

40-a refining tower; 401-a fourth reboiler;

402-a second condenser; 50-product storage tank;

a 60-ethylene oxide storage tank; 70-a water storage tank;

80-a delivery pump; 90-micro interface unit.

Detailed Description

The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and the detailed description, but those skilled in the art will understand that the following described embodiments are some, not all, of the embodiments of the present invention, and are only used for illustrating the present invention, and should not be construed as limiting the scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In order to more clearly illustrate the technical solution of the present invention, the following description is made in the form of specific embodiments.

Examples

Referring to fig. 1, this embodiment provides a reaction system for preparing ethylene glycol by a gas-phase catalytic hydration method, including: a hydration reaction rectifier 10, an evaporation tower 20, a dehydration tower 30, a refining tower 40, an ethylene oxide storage tank 50 and a water storage tank 60; a micro interface unit 90 is arranged on the side surface of the hydration reaction rectifier 10, the micro interface unit 90 is connected with the hydration reaction rectifier 10 through a feeding pipeline 108, and a guide disc 103 for uniformly distributing raw materials is arranged at a feeding hole 107 connected with the micro interface unit; the micro interface unit 90 is composed of a plurality of external micro interface generators, and the micro interface unit is simultaneously connected with a gas delivery pipeline and a water delivery pipeline for introducing ethylene oxide and water into the micro interface unit 90 simultaneously for breaking the ethylene oxide gas into micro bubbles at a micron level. The gas delivery line is connected to the ethylene oxide storage tank 50, the water delivery line is connected to the water storage tank 60, and a delivery pump 80 is provided between the water delivery line and the water storage tank 60.

The guide disc 103 is conical; a plurality of guide holes are uniformly distributed on the guide disc 103, and the diameters of the guide holes are sequentially increased along the direction away from the feed port 107. The guide curve of the guide disk 103 is any one of a hyperbolic curve, a parabolic curve, a two-segment broken line and a logarithmic curve.

In this embodiment, the top of the hydration reactor rectifier 10 is provided with an additive channel 101 for adding catalyst. The top of the hydration reaction rectifier 10 is connected with a first condenser 102, and unreacted water and ethylene oxide are condensed by the first condenser 102 and then flow back to the hydration reaction rectifier 10 for continuous reaction. The bottom of the hydration reaction rectifier 10 is provided with an ethylene glycol outlet 105 for discharging the product ethylene glycol, the ethylene glycol discharged from the ethylene glycol outlet 105 is divided into two gas-liquid streams by a first reboiler 106, the gas-phase stream is circulated back to the hydration reaction rectifier 10, and the liquid-phase stream flows into the evaporation tower 20 along the material-liquid channel 201 for gas-liquid separation.

Wherein, the external micro-interface generators in the micro-interface unit 90 are sequentially arranged from top to bottom. In this embodiment, the number of external micro-interface generators in the micro-interface unit 90 is three. The three external micro-interface generators are arranged in parallel.

In addition, a built-in micro-interface generator 104 is further provided inside the hydration reaction rectifier 10, and the gas phase stream returned through the first reboiler 106 enters the hydration reaction rectifier 10 through the built-in micro-interface generator 104. The gas phase material flows through the built-in micro-interface generator 104 to be dispersed and broken into micro-bubbles, and the unreacted light component returns to the hydration reaction rectifier 10 along with the gas phase gas flow to continue the reaction.

The evaporation tower 20 is connected with a dehydration tower 30, the material from the bottom of the evaporation tower 20 is divided into a gas-liquid two-stream by a second reboiler 202, the gas-phase stream is circulated and returned to the evaporation tower 20, and the liquid-phase stream enters the dehydration tower 30 for further separation and purification. The dehydrating tower 30 is connected with a refining tower 40 for further refining and purifying the material discharged from the dehydrating tower 30. The refining tower 40 is connected with a product storage tank 50, and the product flow refined by the refining tower 40 is sent to the product storage tank 50 to be stored. The ethylene glycol is refined and purified in the refining tower 40, and is output to the product storage tank 50 for storage after purification is completed. The top of the refining tower 40 is connected with a second condenser 402, and the gas phase components at the top of the refining tower 40 are condensed by the second condenser 402 and then flow back to the top of the refining tower 40. The top of the refining tower 40 is totally refluxed, and the gaseous ethylene glycol is condensed into a liquid phase by the second condenser 402 and returns to the refining tower 40 through a reflux line.

Wherein a third reboiler 301 is arranged between the dehydrating tower 30 and the refining tower 40; a fourth reboiler 401 is provided in the polishing column 40 and the product storage tank 50. The third reboiler 301 and the fourth reboiler 401 partially vaporize the material passing therethrough, continuously output the liquid phase, and reflux the gas phase, thereby further purifying the material.

In addition, the top of the hydration reaction rectifier 10 is connected with the second reboiler 202, the top of the evaporation tower 20 is connected with the third reboiler 301, and the top of the dehydration tower 30 is connected with the fourth reboiler 401, so that the steam of the previous stage can be used as the heat source of the reboiler of the next stage, and the utilization efficiency of energy is improved.

In the specific reaction process, 10g of catalyst, 100g of ethylene oxide and 300g of water are introduced into a hydration reaction rectifier 10, the hydration reaction rectifier 10 is heated to 150 ℃, and the pressure in the hydration reaction rectifier 10 is set to be 0.8 MPa. Ethylene oxide reacts with water in the hydration reaction rectifier 10 to produce ethylene glycol; the produced ethylene glycol is dehydrated in the evaporation tower 20 and the dehydration tower 30, and then purified in the purification tower 40, and the purified ethylene glycol is outputted to the product storage tank 50.

In a word, compared with the reaction system for preparing the ethylene glycol by the gas-phase catalytic hydration method in the prior art, the reaction system disclosed by the invention has the advantages of fewer equipment components, small occupied area, low energy consumption, low cost, high safety, controllable reaction and high raw material conversion rate, and is worthy of wide popularization and application.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.