WO2022011865A1 - Reaction system and method for preparing ethanol using syngas - Google Patents

Abstract

Provided are a reaction system and method for preparing ethanol using syngas. The reaction system comprises: a methanol preparation unit, a reaction unit for preparing dimethyl ether from methanol and a reaction unit for preparing ethanol from dimethyl ether that are connected in sequence. The methanol preparation unit comprises a microbubble generator and a synthesis column. An inert oil and a syngas are simultaneously introduced into the microbubble generator, mixed, dispersed and crushed, enter into the synthesis column, and yield crude methanol through synthesis reactions. The crude methanol is distilled successively in a first distillation column and a second distillation column to obtain refined methanol, which is conveyed to the reaction unit for preparing dimethyl ether from methanol. The reaction system provided reduces energy consumption, reduces reaction temperature, improves raw material utilization and effectively enhances productivity.

Description

A kind of reaction system and method for producing ethanol from synthesis gas technical field

The invention relates to the field of ethanol preparation, in particular, to a reaction system and method for producing ethanol from synthesis gas.

Background technique

Worldwide, the production routes of ethanol include grain fermentation routes, petrochemical routes and carbon-one chemical routes such as coal and natural gas. Grain fermentation routes are widely used internationally, and large-scale ethanol production enterprises mostly use grain fermentation processes. Affected by the "food crisis", China has stopped approving new corn fuel ethanol projects. The cellulosic fuel ethanol project fermented with cassava and corn stover has poor economic benefits due to its high production cost, excessive dependence on state subsidies, and imperfect production technology. The petrochemical route uses ethylene as raw material to produce fuel ethanol through ethylene hydration. my country relies heavily on imports of oil, and the price of ethylene is often higher than that of ethanol, which restricts the application and promotion of this method in my country.

Coal, natural gas and other carbon-to-chemical routes use coal or natural gas as raw materials to first obtain synthesis gas and methanol, and then obtain ethanol by dimethyl ether method or acetic acid method. This method uses coal as raw material, plus my country's coal resources It is rich, so it is the most widely used in my country now. However, this method has a series of problems such as high reaction pressure, high temperature, high energy consumption, low utilization rate of raw materials, and low production capacity.

In view of this, the present invention is proposed.

SUMMARY OF THE INVENTION

The first object of the present invention is to provide a reaction system for producing ethanol from synthesis gas. The reaction system reduces energy consumption and reaction temperature by combining the reaction system with a micro-interface generator and a micro-bubble generator. The reaction yield is improved, especially the utilization rate of the reaction gas phase is improved, and the production capacity is effectively improved, thereby improving the quality and yield of the product, and also plays a role in saving equipment cost and equipment floor space.

The second object of the present invention is to provide a reaction method for producing ethanol from synthesis gas by using the above reaction system, the reaction method fully disperses and crushes the reaction raw materials, improves the mass transfer efficiency of the reaction, and improves the conversion rate of the reaction raw materials, The yield of the product is also increased accordingly.

In order to realize the above-mentioned purpose of the present invention, the following technical solutions are specially adopted:

The invention provides a reaction system for producing ethanol from synthesis gas, comprising: a methanol preparation unit, a methanol-to-dimethyl ether reaction unit and a dimethyl ether-to-ethanol reaction unit connected in sequence;

The methanol preparation unit includes: a micro-bubble generator and a synthesis tower. The micro-bubble generator is simultaneously fed with inert oil and synthesis gas after mixing, dispersing and crushing, and then entering the synthesis tower to react and synthesize crude methanol. The rectified methanol obtained after the methanol is rectified in the primary distillation column and the secondary distillation column in turn goes to the methanol-to-dimethyl ether reaction unit;

The methanol-to-dimethyl ether reaction unit includes: a dimethyl ether reactor; the refined methanol is passed into the dimethyl ether reactor for gas-phase catalytic dehydration reaction, and the reacted product enters the first rectifying tower for 2 Methyl ether is purified and rectified, and part of the rectified gas phase is condensed and returned to the first rectifying tower, part of which is returned to the dimethyl ether reactor for re-reaction, and the dimethyl ether side line after the rectification is extracted and sent to the dimethyl ether system. Ethanol reaction unit;

The dimethyl ether-to-ethanol reaction unit includes: a carbonylation reactor, and a first micro-interface generator is arranged on the outside of the carbonylation reactor, and the first micro-interface generator is connected to the first micro-interface generator. The dimethyl ether separated by rectification in the distillation column, and carbon monoxide is introduced at the same time. After being dispersed and broken by the first micro-interface generator, it enters the carbonylation reactor for reaction, and the carbonylation reactor is connected to the second micro-interface. The generator is used to pass the carbonylation product into the second micro-interface generator, and the second micro-interface generator is fed with hydrogen at the same time, and enters the hydrogenation reaction after being dispersed and broken by the second micro-interface generator The reactor is used to carry out the hydrogenation reaction of methyl acetate, and the reaction product after the hydrogenation reaction is separated from methanol and ethanol through the second rectification column to obtain ethanol.

In the reaction system of the present invention, a micro-bubble generator is arranged before the synthesis tower, and a micro-interface generator is correspondingly arranged before the carbonylation reactor and the hydrogenation reactor, so as to disperse and break the incoming gas phase into micro-bubbles, In order to improve the mass transfer effect, the main function of introducing the liquid phase inside the micro-bubble generator and the micro-interface generator is to cooperate with the dispersion and crushing of the gas, which is equivalent to the role of the medium.

Moreover, in the reaction system of the present invention, the reason why it is necessary to set the microbubble generator before the synthesis tower, and set the micro-interface generator before the carbonylation reactor and the hydrogenation reactor, is because whether it is the synthesis tower or the two reactions The reactions carried out in the device are all gas-liquid two-phase reactions. The micro-interface generator and micro-bubble generator set up can just play the role of dispersing and breaking the gas phase, and because of the micro-interface generator set up later, dimethyl ether does not mix. It does not need to be gasified first, and can be directly fed into the micro-interface generator to mix, disperse and crush with carbon monoxide, which simplifies the operation steps. It can be seen that although the structure of the micro-interface generator itself already belongs to the prior art, the setting position of the micro-interface generator It is obtained through practical design, and needs to be specially designed according to the different characteristics of different reactions.

Preferably, the number of micro-bubble generators, the first micro-interface generator or the second micro-interface generator is not unique. In order to increase the mass transfer effect, the number of settings can also be increased accordingly, and the setting method is the best. Arranged in order from top to bottom, each micro-interface generator is preferably in a parallel relationship.

The above-mentioned micro-bubble generator, the first micro-interface generator and the second micro-interface generator are all pneumatic, and the mass transfer is improved by passing the gas phase into the micro-interface generator and then directly contacting the liquid phase and then breaking into micro-bubbles. Effect.

Of course, in addition to arranging the micro-interface generator and the micro-bubble generator in the reactor, the micro-interface generator and the micro-bubble generator can also be correspondingly arranged inside the reactor, but the best way is to The micro-interface generator is set before the reactor, and the micro-interface generator must be set before the carbonylation reactor and the hydrogenation reactor, because this ensures that the pressure does not need to be too high during the reaction process, and the raw materials do not need gas. It is more conducive to centralized control and improves the safety of equipment operation. If one of the micro-interface generators is not installed, the controllability of the material pressure in the whole process will be reduced, and the pressure will vary, and the reduction will not be fully achieved. effect of energy consumption.

Those skilled in the art can understand that the micro-interface generator and micro-bubble generator used in the present invention have been embodied in the inventor's prior patents, such as application numbers CN201610641119.6, 201610641251.7, CN201710766435.0, CN106187660 , CN105903425A, CN109437390A, CN205833127U and CN207581700U patents. In the previous patent CN201610641119.6, the specific product structure and working principle of the micro-bubble generator (that is, the micro-interface generator) were introduced in detail. There is a cavity, the body is provided with an inlet communicating with the cavity, the opposite first and second ends of the cavity are open, wherein the cross-sectional area of the cavity is from the middle of the cavity to the first and second ends of the cavity. The second end is reduced; the secondary crushing piece is arranged at at least one of the first end and the second end of the cavity, a part of the secondary crushing piece is arranged in the cavity, and both ends of the secondary crushing piece and the cavity are open An annular channel is formed between the through holes of the micro-bubble generator. The micro-bubble generator also includes an air inlet pipe and a liquid inlet pipe." From the specific structure disclosed in the application document, we can know that its specific working principle is: the liquid enters the micron tangentially through the liquid inlet pipe. In the bubble generator, ultra-high-speed rotation and cutting of the gas make the gas bubbles break into micro-bubbles at the micron level, thereby increasing the mass transfer area between the liquid phase and the gas phase, and the micro-bubble generator in this patent belongs to the pneumatic micro-interface generation. device.

In addition, the previous patent 201610641251.7 records that the primary bubble breaker has a circulating liquid inlet, a circulating gas inlet and a gas-liquid mixture outlet, and the secondary bubble breaker communicates the feed port with the gas-liquid mixture outlet, indicating that the bubble breaker is both It needs to be mixed with gas and liquid. In addition, it can be seen from the following drawings that the primary bubble breaker mainly uses circulating liquid as power, so in fact, the primary bubble breaker belongs to the hydraulic micro-interface generator, and the secondary bubble breaker is a gas-liquid breaker. The mixture is simultaneously fed into the elliptical rotating ball for rotation, so that the bubbles are broken during the rotation, so the secondary bubble breaker is actually a gas-liquid linkage type micro-interface generator. In fact, both hydraulic micro-interface generators and gas-liquid linkage micro-interface generators belong to a specific form of micro-interface generators. However, the micro-interface generators used in the present invention are not limited to the above-mentioned forms. , 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 take. In addition, the previous patent 201710766435.0 recorded that "the principle of the bubble breaker is to achieve high-speed jets to achieve gas collision", and also stated that it can be used in micro-interface enhanced reactors to verify the relationship between the bubble breaker and the micro-interface generator. and the prior patent CN106187660 also has related records for the specific structure of the bubble breaker, see the specific description in paragraphs [0031]-[0041], and the accompanying drawings, which are related to the bubble breaker S-2 The specific working principle of the bubble breaker is explained in detail. The top of the bubble breaker is the liquid phase inlet, and the side is the gas phase inlet. The liquid phase entering from the top provides the entrainment power, so as to achieve the effect of crushing into ultra-fine bubbles, which can also be seen in the accompanying drawings. The bubble breaker has a conical structure, and the diameter of the upper part is larger than that of the lower part, so that the liquid phase can provide better entrainment power.

Since the micro-interface generator was just developed in the early stage of the previous patent application, it was named as micro-bubble generator (CN201610641119.6), bubble breaker (201710766435.0), etc., and later changed its name to micro-interface generator with continuous technological improvement. Now the micro-interface generator and micro-bubble generator in the present invention are equivalent to the previous micro-bubble generator, bubble breaker, etc., but the names are different.

To sum up, 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 belong to the type of hydraulic bubble breakers, and some belong to the type of gas bubble breakers. The type of liquid-linked bubble breaker, but the difference between the types is mainly selected according to the specific working conditions. In addition, the connection between the micro-interface generator and the reactor and other equipment, including the connection structure and connection position, depends on the micro-interface generator. It depends on the structure of the interface generator, which is not limited.

The reaction system of the present invention includes three units: a methanol preparation unit, a methanol-to-dimethyl ether reaction unit, and a dimethyl ether-to-ethanol reaction unit.

Among them, the methanol preparation unit mainly includes the following equipment: micro-bubble generator, synthesis tower, gasification tower, primary rectification tower, and secondary rectification tower.

Inert oil and synthesis gas are simultaneously introduced into the microbubble generator, mixed, dispersed and broken, and then entered into the synthesis tower for synthesis reaction to synthesize crude methanol. The refined methanol goes to the methanol-to-dimethyl ether reaction unit for subsequent reactions.

The synthesis gas is mainly transformed through natural gas, petroleum, coal and other raw materials, and after the transformation, _{synthetic raw material gas of CO, CO 2} and H ₂ is formed, and then the raw material gas is purified to adjust the hydrogen-carbon ratio, and finally the subsequent compression process is carried out to achieve The pressure required to synthesize methanol to form syngas.

Syngas often requires high temperature and high pressure conditions for methanol synthesis, but methanol synthesis itself is a relatively strong exothermic reaction. From a thermodynamic point of view, lowering the temperature is conducive to the reaction moving in the direction of methanol generation. In this way, the operation temperature and pressure can be significantly reduced by adopting the liquid phase synthesis method. The synthesis gas is passed through the micro-bubble generator in advance, and dissolved in the inert oil medium from large bubbles to small bubbles, so that the subsequent transport into the synthesis tower , the synthesis gas with inert oil as the medium is also easier to reach the surface of the catalyst. Because the inert oil is used as the medium, the specific surface area of the catalyst dispersed in the medium is relatively large, which accelerates the reaction process, and the reaction temperature and pressure will drop a lot, and Because the micro-bubble generator is set before the synthesis tower, the reaction temperature and pressure are significantly reduced, and the reaction energy consumption is fully reduced.

The synthesis gas is compressed by the compressor, and then transferred to the micro-bubble generator after exchanging heat with the product from the synthesis tower in the heat exchanger.

The synthesis tower is a fixed bed reactor, and a solid catalyst is placed on the fixed bed, and the type of the solid catalyst can be a copper-based catalyst or a zinc-chromium catalyst.

Preferably, a gasification tower is provided between the synthesis tower and the primary rectification tower for removing dimethyl ether, methyl formate and other low-boiling substances in the crude methanol, and the primary rectification tower The side wall of the distillation column is connected with the bottom of the gasification column through a pipeline, so that the crude methanol after removing impurities enters the primary rectification column for rectification.

The function of setting the gasification tower is to remove dimethyl ether, methyl formate and other low-boiling substances in crude methanol. These substances are returned to the top of the gasification tower for re-reaction, and the crude methanol is removed from the bottom of the gasification tower. Go to the primary rectification tower for rectification, generally from between the two tower sections of the primary rectification tower.

Preferably, the side of the primary rectification tower is provided with a first material circulation line for condensing the gas phase from the top of the primary rectification tower and then returning to the primary rectification tower. A first condenser, a first condensing tank and a first circulating pump are arranged in sequence along the top direction of the material flowing out of the primary rectifying tower on the line, and the side wall of the first condensing tank is connected to the secondary The top of the distillation column is connected.

Preferably, the side of the secondary rectification tower is provided with a second material circulation line for partially condensing the refined methanol extracted from the side line of the secondary rectification tower and returning it to the secondary rectification tower. A second condenser, a second condensing tank, and a second circulating pump are sequentially arranged on the second material circulation line along the top direction of the material returning to the secondary rectification tower.

The material from the top of the primary rectification tower contains 50% methanol, which is recycled to a part of the primary rectification tower through the first material circulation line after coming out from the top of the tower, and the other part is condensed by the first condenser and then goes to the secondary rectification tower. The top of the distillation column is re-rectified.

Preferably, a side-line extraction line is arranged at the upper position of the side wall of the secondary rectification tower, the end of the side-line extraction line is connected with a refined methanol storage tank, and a third condenser is arranged on the side-line extraction line, so the The second material circulation line is connected with the side branch of the side line draw line between the secondary rectification tower and the third condenser.

The methanol channel containing heavy components from the bottom of the primary rectification tower is rectified in the secondary rectification tower, the methanol from the secondary rectification tower is condensed by the third condenser to obtain refined methanol and stored in the refined methanol storage tank , for the subsequent methanol to dimethyl ether reaction unit. Of course, a part of methanol from the secondary rectification column is returned to the secondary rectification column through the second material circulation line for re-rectification.

The equipment mainly included in the methanol-to-dimethyl ether reaction unit of the present invention includes: a dimethyl ether reactor and a first rectifying tower.

Methanol is first subjected to gas-phase catalytic dehydration reaction in a dimethyl ether reactor to generate dimethyl ether. The reaction temperature is 250 to 270 ° C and the pressure is 1.2 MPa. The catalyst is generally selected from molecular sieve, such as ZSM molecular sieve, aluminum phosphate or γ- Al ₂ O ₃ . The dehydration of methanol to form dimethyl ether is an exothermic reaction, and the temperature of the product gas at the outlet of the reactor is 320°C to 330°C. The main reaction products are dimethyl ether and water, and the side reaction products are carbon oxides, methane and hydrocarbons.

Preferably, the methanol-to-dimethyl ether reaction unit includes a heat exchanger, and the heat exchanger is used for heat exchange between the raw methanol and the gas-phase catalytic dehydration reaction product.

Preferably, the heat exchanger is arranged between the dimethyl ether reactor and the first rectification column, and a preheater is also arranged between the heat exchanger and the dimethyl ether reactor . It is precisely because methanol dehydration to prepare dimethyl ether is an exothermic reaction, so a preheater and a heat exchanger are set up accordingly.

After heat exchange, the reaction product enters the first rectifying tower for purification and rectification, and then a relatively pure dimethyl ether product can be formed, which can be used for the subsequent synthesis of ethanol.

The main function of the first rectifying tower is to purify the dimethyl ether product. After the gas phase methanol recovered at the top of the first rectifying tower is liquefied by the condenser at the top of the tower, part of it is returned to the first rectifying tower, and the other part is returned to the dimethyl ether reaction. The device is reused as the reaction raw material. Most of the materials coming out from the bottom of the first rectifying tower are dimethyl ether and a small amount of methanol, which can also be directly extracted for simple separation, and the separated methanol can be directly used as the reaction raw material of the dimethyl ether reactor.

Preferably, a extraction mechanism for side-line extraction of dimethyl ether is provided on the first rectifying tower, and the extraction mechanism is connected with the first micro-interface generator. The main product of the first rectifying tower is extracted by the side-line extraction mechanism. After the side-line extraction, the dimethyl ether product is transported to the first micro-interface generator for the subsequent ethanol synthesis process.

The equipment mainly included in the dimethyl ether-to-ethanol reaction unit of the present invention is a carbonylation reactor, a separation column, a hydrogenation reactor and a second rectification column.

The type of the carbonylation reactor for carrying out the carbonylation reaction is preferably a fixed bed reactor, and three layers of fixed trays are arranged inside, and a carbonylation reaction catalyst is arranged on each layer of the fixed tray, and the carbonylation reactor is provided with a carbonylation reaction catalyst. Several reaction mixture inlets are respectively arranged at the top of the carbonylation reactor and between adjacent fixed trays.

The dimethyl ether product from the methanol-to-dimethyl ether reaction unit does not need to be gasified, and is directly fed into the first micro-interface generator. At the same time, carbon monoxide is also fed into the first micro-interface generator. Carbon monoxide is in the liquid phase. After being crushed into microbubbles under the action of dimethyl ether, it enters the carbonylation reactor for carbonylation reaction. In order to improve the reaction effect, the mixture inlets on the carbonylation reactor are respectively arranged between the adjacent fixed beds on the side walls. room and top.

Preferably, a separation column is arranged between the carbonylation reactor and the second micro-interface generator for removing gas-phase impurities in the carbonylation product.

Preferably, the top of the separation tower is provided with a separation tank, and the gas phase after the separation of the separation tank goes to the first micro-interface generator, and the liquid phase returns to the separation tower to be stripped and separated again.

Carbon monoxide and dimethyl ether undergo a carbonylation reaction under the action of a catalyst to obtain a carbonylation product. The main component of the carbonylation product is methyl acetate and some unreacted dimethyl ether. After stripping through a separation tower, the separation The top of the tower is mainly unreacted dimethyl ether, which can be directly returned to the first micro-interface generator as the reaction feed for carbonylation through the separation tank set at the top of the separation tower, and the liquid phase from the bottom of the separation tank is directly returned to the separation tank. In the column, stripping separation and purification are carried out again.

Preferably, a methyl acetate outlet is provided at the bottom of the separation tower, and the methyl acetate outlet is connected with the second micro-interface generator through a pipeline.

The material coming out from the bottom of the separation tower is mainly methyl acetate, which is transported into the second micro-interface generator through a pump. In order to improve the effect of the second micro-interface generator, methyl acetate is preheated by a preheater before into the second micro-interface generator. Hydrogen is simultaneously introduced into the second micro-interface generator, and the hydrogen is pulverized into micro-bubbles under the action of liquid methyl acetate, and then enters the hydrogenation reactor for hydrogenation reaction.

Preferably, the type of the hydrogenation reactor for the hydrogenation reaction is a fixed bed reactor, the catalyst in the fixed bed reactor is fixed on the bed layer, and the catalyst for the hydrogenation reaction is generally a nickel-based catalyst, preferably the catalyst can be a supported catalyst Nickel-based catalysts of type 1, or nickel-based catalysts modified with alkaline earth metal oxides or rare earth metal oxides are more preferable.

Methyl acetate generates methanol and ethanol after hydrogenation reaction, and then enters into the second rectifying tower for ethanol refining. The operating pressure at the top of the second rectifying tower is about 0.03 MPa, and the vapor at the top of the tower is condensed to 61.7 ° C, and the condensation Part of the liquid phase (methanol) after coming down is returned to the second rectifying tower, and part is sent to the methanol-to-dimethyl ether reaction unit, which is used as a reaction raw material to prepare dimethyl ether.

Preferably, a methanol outlet is provided at the top of the second rectification column, and the methanol outlet is returned to the dimethyl ether reactor through a pipeline to be used as methanol raw material, and a product recovery device is arranged at the bottom of the second rectification column. Exported for extraction of product ethanol.

After the material from the methanol outlet is condensed by the overhead condenser, a part is returned to the second rectification tower, and the other part is communicated with the dimethyl ether reactor through a pipeline to reuse methanol as a raw material.

The product extraction port set at the bottom of the second rectifying tower is used to extract refined ethanol, the temperature is about 101 ℃, the refined ethanol of the extraction port is cooled to 40 ℃ in an ethanol cooler, and then pumped to ethanol through an ethanol buffer tank In the product tank area, the ethanol substandard product tank is set up in the intermediate tank area, which is used for start-up or abnormal production. During the process of ethanol refining in the second rectification tower, a small amount of rectification waste liquid will be produced at the bottom of the tower, the main component of which is acetic acid, which will be sent to the heavy component tank for storage after cooling to room temperature.

The present invention also provides a micro-interface reaction method for producing ethanol from synthesis gas, comprising:

Mixing, dispersing and crushing fresh synthesis gas and inert oil, catalyzing synthesis of crude methanol, the crude methanol is rectified to obtain refined methanol;

The refined methanol is subjected to gas-phase catalytic dehydration and rectification to obtain dimethyl ether;

After the dimethyl ether and carbon monoxide are mixed, dispersed and crushed, carbonylation reaction is carried out to obtain a carbonylation reaction product;

After the carbonylation reaction product is mixed, dispersed and crushed with hydrogen, and subjected to hydrogenation reaction, ethanol is obtained by rectification.

Preferably, the pressure of the synthesis gas catalytic synthesis of crude methanol is 2.5-4.0 MPa, and the temperature is 180-200 °C.

Preferably, the pressure of the carbonylation reaction is 2.5-3.0 MPa, and the temperature is 200-230 °C.

Preferably, the pressure of the hydrogenation reaction is 2.5-3.0MPa, and the temperature is 200-210°C.

In the prior art, the temperature of the dimethyl ether carbonylation reaction is selected at 240-260 ° C, the pressure is selected as 5.0 MPa, the temperature of the hydrogenation reaction is selected at 230-260 ° C, and the pressure is selected at 5.0 MPa, although increasing the temperature can significantly increase the temperature. The reaction activity of the catalyst and the selectivity of the product, but the reaction temperature is too high will accelerate the deactivation of the catalyst; the higher reaction pressure is conducive to the carbonylation reaction and promote the conversion of dimethyl ether, but the reaction pressure is too high will lead to raw materials or products. Therefore, by adopting the reaction method of the present invention, not only the reaction temperature and the reaction pressure are appropriately reduced to ensure the activity of the catalyst, but also the energy consumption is reduced, and the reaction effect, the yield and the conversion of the raw materials are also guaranteed. rate remains high.

The ethanol obtained by adopting the reaction method for producing ethanol from synthesis gas in the present invention has high yield and high purity, and the purity can reach 99.9%.

The reaction method of the present invention has low reaction temperature, greatly reduced pressure and high liquid hourly space velocity, which is equivalent to increasing the production capacity and improving the product yield.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The reaction system of the present invention reduces the energy consumption, reduces the reaction temperature, improves the reaction yield, and improves the utilization rate of the raw materials by combining the carbonylation reactor, the hydrogenation reactor and the micro-interface generator. ;

(2) The reaction system of the present invention is most advantageous for simplifying the operation steps and reducing the energy consumption of the entire process by arranging the micro-interface generator and the micro-bubble generator at a specific position;

(3) The reaction method of the present invention has low reaction temperature, greatly reduced pressure and high liquid hourly space velocity, which is equivalent to improving the production capacity, and the ethanol obtained by the reaction has high yield and high purity, and the product purity can reach 99.9%.

Description of 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 for the purpose of illustrating preferred embodiments only and are not to be considered limiting of the invention. Also, the same components are denoted by the same reference numerals throughout the drawings. In the attached image:

FIG. 1 is a schematic structural diagram of a reaction system for producing ethanol from synthesis gas according to an embodiment of the present invention.

Description of drawings:

10-dimethyl ether reactor; 20-preheater;

30-heat exchanger; 40-first distillation column;

401- tower top condenser; 402- tower kettle reboiler;

50-the first micro-interface generator; 60-CO storage tank;

70-carbonylation reactor; 80-separation tower;

90-second micro-interface generator; 100-hydrogen storage tank;

110-hydrogenation reactor; 120-second distillation column;

1201-Methanol export; 1202-Product extraction and export;

701-fixed tray; 702-mixture import;

801-Separation tank; 802-Methyl acetate outlet;

130-microbubble generator; 140-synthesis tower;

150-gasification tower; 160-first distillation tower;

170-The first material circulation line; 1701-The first condenser;

1702-The first condensing tank; 1703-The first circulating pump;

180-Secondary distillation column; 190-Second material circulation line;

1901-Second condenser; 1902-Second condensation tank;

1903-Second circulating pump; 200-Side line extraction line;

210 - Refined methanol storage tank; 220 - The third condenser.

detailed description

The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments, but those skilled in the art will understand that the embodiments described below are part of the embodiments of the present invention, rather than all of the embodiments, It is only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. If the specific conditions are not indicated in the examples, it is carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used without the manufacturer's indication are conventional products that can be purchased from the market.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation or a specific orientation. construction and operation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first", "second", and "third" are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

In the description of the present invention, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense, unless otherwise expressly specified and limited, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

In order to illustrate the technical solutions of the present invention more clearly, the following descriptions are given in the form of specific embodiments.

Example

Referring to FIG. 1, it is a schematic structural diagram of a reaction system for preparing ethanol from synthesis gas according to an embodiment of the present invention. The reaction system includes a methanol preparation unit, a methanol-to-dimethyl ether reaction unit, and a dimethyl ether-to-ethanol reaction unit. three units.

The methanol preparation unit includes: a micro-bubble generator 130, a synthesis tower 140, a gasification tower 150, a primary rectification tower 160, a secondary rectification tower 180, and the inert oil and synthesis gas are introduced into the micro-bubble generator 130 for mixing and dispersion After crushing, it enters the synthesis tower 140 to carry out the reaction of synthesizing methanol to synthesize crude methanol, and then the crude methanol passes through the subsequent gasification tower 150, the primary rectification tower 160, and the secondary rectification tower 180 to purify and rectify the purified methanol. Methanol goes to methanol to dimethyl ether reaction unit for subsequent reaction. The synthesis gas is pre-compressed by a compressor, and then transferred to the micro-bubble generator after exchanging heat with the product from the synthesis tower in a heat exchanger.

The crude methanol from the bottom of the synthesis tower is cooled by the heat exchanger and then sent to the gasification tower 150 to remove dimethyl ether, methyl formate and other low-boiling substances in the crude methanol. After the low-boiling substances are removed by gasification The methanol goes from the bottom of the gasification tower 150 to the primary rectification tower 160 through a pipeline for rectification.

The side of the primary rectification column 160 is provided with a first material circulation line 170 for condensing the gas phase from the top of the primary rectification column 160 and returning to the primary rectification column. The first material circulation line flows out of the primary rectification line along the material A first condenser 1701, a first condensing tank 1702, and a first circulating pump 1703 are sequentially arranged in the direction of the top of the tower. The side of the secondary rectification column 180 is provided with a second material circulation line 190 for partially condensing the refined methanol extracted from the side line of the secondary rectification column 180 and returning it to the secondary rectification column 180. A second condenser 1901, a second condensing tank 1902, and a second circulating pump 1903 are sequentially arranged along the top direction of the material returning to the secondary rectification tower 180.

A side draw line 200 is provided at the upper position of the side wall of the secondary rectification tower 180, the end of the side draw line 200 is connected with a refined methanol storage tank 210, and a third condenser is provided on the side draw line 220, the secondary rectifying tower 180 and the third condenser 220 are connected with the second material circulation line 190 by the side branch of the side line extraction line, and the methanol containing heavy components from the bottom of the primary rectifying tower 160 is passed to the secondary rectifying tower. Rectification is performed in the distillation column 180, and the methanol from the secondary rectification column 180 is condensed by the third condenser 220 to obtain refined methanol, which is stored in the refined methanol storage tank 210 for use in the subsequent methanol-to-dimethyl ether reaction unit. Of course, a part of methanol from the secondary rectification column 180 is returned to the secondary rectification column 180 through the second material circulation line 190 for re-rectification.

The dimethyl ether reaction unit includes: a dimethyl ether reactor 10, a first rectification tower 40, and the refined methanol stored in the refined methanol storage tank is sent to the dimethyl ether reactor 10, and after the gas-phase catalytic dehydration reaction is performed, the reaction product enters into the dimethyl ether reactor 10. The first rectifying tower 40 carries out dimethyl ether purification, and part of the top gas phase (mainly a small amount of gas-phase dimethyl ether and methanol, etc.) after the rectification is condensed and returned to the first rectifying tower, and partly returned to the dimethyl ether reactor 10 Re-react, and the rectified dimethyl ether is directly drawn from the side line and sent to the dimethyl ether-to-ethanol reaction unit.

The top of the first rectifying column 40 is provided with a column top condenser 401. After the gas phase at the top of the column passes through the column top condenser 401, a part returns to the first rectifying column 40, and the other part goes out from the column top condenser 401 to the washing column. 140. The tower bottom of the first rectifying tower 40 is provided with a tower kettle reboiler 402, and under the action of the tower kettle reboiler 402, the product (mainly liquid-phase dimethyl ether) flowing out of the tower kettle carries out a simple subsequent purification operation It can also be returned to the dimethyl ether reactor 10 as a reaction raw material.

Each of the first rectifying towers 40 is provided with a side-line extraction mechanism for extracting the product dimethyl ether, and the extraction mechanism is connected with the first micro-interface generator for subsequent reaction synthesis of ethanol.

Between the dimethyl ether reactor 10 and the first rectification tower 40, a heat exchanger 30 for exchanging heat between the raw methanol and the gas-phase catalytic dehydration reaction product is provided, and at the same time, the heat exchanger 30 and the dimethyl ether reactor 10 are provided with a heat exchanger 30. A preheater 20 is also arranged therebetween for preheating the raw materials entering the dimethyl ether reactor 10 , so as to improve the reaction efficiency of the dimethyl ether reactor 10 .

The dimethyl ether-to-ethanol reaction unit includes: a carbonylation reactor 70 , a first micro-interface generator 50 , a separation column 80 , a second micro-interface generator 90 , a hydrogenation reactor 110 , and a second rectification column 120 .

The side-line extraction mechanism set on the first rectifying tower 40 for the extraction of dimethyl ether products goes to the first micro-interface generator 50, and also passes into the first micro-interface generator 50, and CO is also introduced into the first micro-interface generator 50, and carbon monoxide is obtained from The carbon monoxide transported from the CO storage tank 60 is mixed with dimethyl ether in the first micro-interface generator 50 and then dispersed and crushed, and then enters the carbonylation reactor 70 for carbonylation reaction. The main components of the carbonylation reaction product are: Methyl acetate, and some unreacted dimethyl ether, go to the separation tower 80 from the bottom of the carbonylation reactor 70. The type of the carbonylation reactor 70 is a fixed bed reactor, and the interior is provided with three layers of fixed trays 701, Each fixed column plate 701 is provided with a carbonylation reaction catalyst, and the carbonylation reactor 70 is also provided with a number of mixture inlets 702. The mixture inlets 702 are respectively arranged at the top of the carbonylation reactor 70 and between the adjacent fixed column plates 701. between.

After stripping through the separation column 80, the top of the separation column 80 is mainly unreacted dimethyl ether, which can be directly returned to the first micro-interface generator 50 through the separation tank 801 arranged at the top of the separation column 80 as the reaction feed of the carbonylation. The liquid phase from the bottom of the separation tank 801 is directly returned to the separation tower 80 for stripping separation and purification again.

The bottom of the separation tower is provided with a methyl acetate outlet 802, and the material going out from the methyl acetate outlet 802 at the bottom of the separation tower 80 is mainly methyl acetate, and is transported into the second micro-interface generator 90 by a pump, in order to improve the second The effect of the micro-interface generator 90 is that methyl acetate is preheated by the preheater 20 and then fed into the second micro-interface generator 90, and at the same time, hydrogen is fed into the second micro-interface generator 90 at the same time, The hydrogen is transported through the hydrogen storage tank 100. The hydrogen is fully mixed with the liquid methyl acetate in the second micro-interface generator 90 and pulverized into microbubbles, and then enters the hydrogenation reactor 110 for hydrogenation reaction.

The methyl acetate is subjected to hydrogenation to generate methanol and ethanol, which are transported to the second rectifying tower 120 for ethanol purification. The top of the second rectifying tower 120 is provided with a methanol outlet 1201, and the methanol outlet 1201 is returned to dimethyl ether through a pipeline. The reactor 10 is used as a methanol raw material, and a product extraction port 1202 is provided at the bottom of the second rectifying tower 120 for extraction of product ethanol. The tower top of the second rectifying tower 120 is provided with a tower top condenser, and the tower kettle is provided with a tower kettle reboiler. After the material from the methanol outlet 1201 is condensed by the tower top condenser, a part returns to the second rectification tower 120, and a part returns to the second rectification tower 120. It is discharged, and the discharged part can be directly returned to the dimethyl ether reactor 10 for use as a reaction raw material.

The micro-interface reaction system of this embodiment is provided with a micro-interface generator at a specific position, so as to improve the mass transfer effect of the entire reaction, reduce energy consumption, and at the same time improve the utilization rate of raw materials.

In the above-mentioned embodiment, it is not limited to setting a single micro-interface generator. In order to increase the effect of dispersion and mass transfer, additional micro-interface generators can also be added. The installation position is actually not limited, and it can be external or external. Built-in, when built-in, it can also be installed on the side wall of the kettle, so as to realize the hedge of the micro-bubbles from the outlet of the micro-interface generator. Interface generator way.

In the above embodiment, there is no specific requirement for the number of pump bodies, which can be set at corresponding positions as required.

The working process and principle of the coal-to-ethanol micro-interface reaction system of the present invention are briefly described below:

Nitrogen purges each device in the micro-interface reaction system, and then starts to operate, and the syngas and inert oil are passed into the micro-bubble generator 130 to disperse and break the syngas into small bubbles, and then enter the synthesis tower 140 for methanol. In the synthesis reaction, the obtained crude methanol is successively rectified and purified by the gasification tower 150, the primary rectification tower 160, and the secondary rectification tower 180, and then stored in the refined methanol storage tank 210. The refined methanol from the refined methanol storage tank 210 First, the gas-phase catalytic dehydration reaction is carried out in the dimethyl ether reactor 10, and then it goes to the first rectifying tower 40 for rectification, and the dimethyl ether extracted from the side-drawing mechanism of the first rectifying tower 40 goes to the first rectifying tower 40. The micro-interface generator 50 is mixed with CO for dispersion and crushing. The dispersed and crushed mixture enters the carbonylation reactor 70 for carbonylation reaction. After the bottom of the tower comes out, it goes to the second micro-interface generator 90 to mix, disperse and crush with hydrogen, and then go to the hydrogenation reactor 110 for hydrogenation reaction, and finally the hydrogenation reaction product goes to the second rectification tower 120 for rectification to obtain the final product. The product is refined ethanol.

Wherein, the pressure of the synthesis gas catalytic synthesis of crude methanol is 2.5-4.0MPa, and the temperature is 180-200°C.

The pressure of the carbonylation reaction is 2.5-3.0MPa, and the temperature of the carbonylation reaction is 200-230°C.

The pressure of the hydrogenation reaction is 2.5-3.0MPa, and the temperature of the hydrogenation reaction is 200-210°C.

The above process steps are cycled back and forth to make the entire synthesis system run smoothly.

In a word, compared with the reaction system of the prior art, the reaction system of the present invention has fewer equipment components, small footprint, low energy consumption, low cost, high safety, controllable reaction, and high conversion rate of raw materials, which is equivalent to synthetic The field of gas-to-ethanol provides a more operable reaction system, which is worthy of widespread application.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. Scope.

Claims (10)

1. A reaction system for producing ethanol from synthesis gas, comprising: a methanol preparation unit, a methanol-to-dimethyl ether reaction unit, and a dimethyl ether-to-ethanol reaction unit connected in sequence;

   The methanol preparation unit includes: a micro-bubble generator and a synthesis tower. The micro-bubble generator is simultaneously fed with inert oil and synthesis gas after mixing, dispersing and crushing, and then entering the synthesis tower to react and synthesize crude methanol. The rectified methanol obtained after the methanol is rectified in the primary distillation column and the secondary distillation column in turn goes to the methanol-to-dimethyl ether reaction unit;

   The methanol-to-dimethyl ether reaction unit includes: a dimethyl ether reactor; the refined methanol is passed into the dimethyl ether reactor for gas-phase catalytic dehydration reaction, and the reacted product enters the first rectifying tower for 2 Methyl ether is purified and rectified, and part of the rectified gas phase is condensed and returned to the first rectifying tower, part of which is returned to the dimethyl ether reactor for re-reaction, and the dimethyl ether side line after the rectification is extracted and sent to the dimethyl ether system. Ethanol reaction unit;

   The dimethyl ether-to-ethanol reaction unit includes: a carbonylation reactor, and a first micro-interface generator is arranged on the outside of the carbonylation reactor, and the first micro-interface generator is connected to the first micro-interface generator. The dimethyl ether separated by rectification in the distillation column, and carbon monoxide is introduced at the same time. After being dispersed and broken by the first micro-interface generator, it enters the carbonylation reactor for reaction, and the carbonylation reactor is connected to the second micro-interface. The generator is used to pass the carbonylation product into the second micro-interface generator, and the second micro-interface generator is fed with hydrogen at the same time, and enters the hydrogenation reaction after being dispersed and broken by the second micro-interface generator The reactor is used to carry out the hydrogenation reaction of methyl acetate, and the reaction product after the hydrogenation reaction is separated from methanol and ethanol through the second rectification column to obtain ethanol.
2. The reaction system according to claim 1, wherein a gasification tower is provided between the synthesis tower and the primary rectification tower for converting dimethyl ether and methyl formate in the crude methanol and other low-boiling substances are removed, the side wall of the primary rectification column is connected with the bottom of the gasification column through a pipeline, so that the crude methanol after removing impurities enters the primary rectification column for rectification.
3. The reaction system according to claim 2, wherein the side of the primary rectifying tower is provided with a second rectifying tower for condensing the gas phase from the top of the primary rectifying tower and returning to the primary rectifying tower. A material circulation line, the first material circulation line is provided with a first condenser, a first condensation tank, and a first circulation pump in sequence along the top direction of the material flowing out of the primary rectification tower, and the first condenser The side wall of the tank is connected with the top of the secondary rectification column through a pipeline.
4. The reaction system according to claim 3, characterized in that, a side of the secondary rectification tower is provided for partially condensing the refined methanol extracted from the side line of the secondary rectification tower and then returned to the secondary rectification tower. The second material circulation line of the distillation column is provided with a second condenser, a second condensation tank and a second circulation pump in sequence along the direction of the top of the column where the material returns to the secondary rectification column.
5. The reaction system according to claim 4, characterized in that, a side line extraction line is provided at the upper position of the side wall of the secondary rectification tower, and the end of the side line extraction line is connected with a refined methanol storage tank, so A third condenser is arranged on the side draw line, and the second material circulation line is connected to a side branch of the side draw line between the secondary rectification tower and the third condenser.
6. The reaction system according to claim 1, wherein the carbonylation reactor is a fixed-bed reactor, and three layers of fixed trays are arranged inside, and a carbonylation reaction catalyst is arranged on each layer of the fixed trays. The carbonylation reactor is provided with several reaction mixture inlets, and the reaction mixture inlets are respectively arranged at the top of the carbonylation reactor and between adjacent fixed trays.
7. The reaction system according to claim 1, wherein a separation column is arranged between the carbonylation reactor and the second micro-interface generator for removing gas-phase impurities in the carbonylation product.
8. The reaction system according to claim 7, wherein a separation tank is provided at the top of the separation tower, the gas phase separated by the separation tank goes to the first micro-interface generator, and the liquid phase returns to the The separation column is re-stripped for separation.
9. Adopt the reaction method of the reaction system that adopts synthesis gas to make ethanol described in any one of claim 1-8, it is characterized in that, comprising:

   Mixing, dispersing and crushing fresh synthesis gas and inert oil, catalyzing synthesis of crude methanol, the crude methanol is rectified to obtain refined methanol;

   The refined methanol is subjected to gas-phase catalytic dehydration and rectification to obtain dimethyl ether;

   After the dimethyl ether and carbon monoxide are mixed, dispersed and crushed, carbonylation reaction is carried out to obtain a carbonylation reaction product;

   After the carbonylation reaction product is mixed, dispersed and crushed with hydrogen, and subjected to hydrogenation reaction, ethanol is obtained by rectification.
10. The reaction method according to claim 9, wherein the pressure of the synthesis gas catalytic synthesis of crude methanol is 2.5-4.0MPa, and the temperature is 180-200°C;

    Preferably, the pressure of the carbonylation reaction is 2.5-3.0MPa, and the temperature is 200-230°C;

    Preferably, the pressure of the hydrogenation reaction is 2.5-3.0MPa, and the temperature is 200-210°C.

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