阅读说明：本技术 一种用于制备dmc的系统及制备方法 (System and method for preparing DMC ) 是由 张志炳 孟为民 周政 王宝荣 杨高东 罗华勋 张锋 李磊 杨国强 田洪舟 曹宇 于 2021-07-16 设计创作，主要内容包括：本发明提供了一种用于制备DMC的系统,包括：反应罐和精馏塔,所述反应罐设置在所述精馏塔内的中部,所述精馏塔侧壁上由上至下设置有甲醇管路和混合气管路；所述甲醇管路和所述混合气管路均穿透所述精馏塔侧壁进入所述反应罐中；甲醇和混合气在所述反应罐中反应,反应产物从所述反应罐顶部进入所述精馏塔中。本发明的系统能够显著降低所需反应温度和压力,且整体反应过程中副反应少、甲醇转化率高,值得广泛推广应用。(The present invention provides a system for preparing DMC, comprising: the device comprises a reaction tank and a rectifying tower, wherein the reaction tank is arranged in the middle of the rectifying tower, and a methanol pipeline and a mixed gas pipeline are arranged on the side wall of the rectifying tower from top to bottom; the methanol pipeline and the mixed gas pipeline penetrate through the side wall of the rectifying tower to enter the reaction tank; and the methanol and the mixed gas react in the reaction tank, and the reaction product enters the rectifying tower from the top of the reaction tank. The system can obviously reduce the required reaction temperature and pressure, has less side reaction and high methanol conversion rate in the whole reaction process, and is worthy of wide popularization and application.)

1. A system for preparing DMC, comprising: the device comprises a reaction tank and a rectifying tower, wherein the reaction tank is arranged in the middle of the rectifying tower, and a methanol pipeline and a mixed gas pipeline are arranged on the side wall of the rectifying tower from top to bottom; the methanol pipeline and the mixed gas pipeline penetrate through the side wall of the rectifying tower to enter the reaction tank; the methanol and the mixed gas react in the reaction tank, and a reaction product enters the rectifying tower from the top of the reaction tank;

two micro-interface generators are sequentially arranged in the reaction tank from top to bottom, and outlets of the two micro-interface generators are oppositely arranged; the micro-interface generator positioned above is connected with the methanol pipeline; the micro-interface generator positioned at the lower part is connected with the mixed gas pipeline; and after the methanol and the mixed gas are respectively dispersed and crushed into micro-bubbles at the micron level by the micro-interface generator, the micro-bubbles react in the reaction tank.

2. The system for preparing DMC according to claim 1, characterized in that the reactor vessel has a circulation line connected to its side wall, and a shower is provided on the top of the reactor vessel; the circulating pipeline is connected with the sprayer, and the liquid phase in the reaction tank enters the sprayer along the circulating pipeline and is sprayed back to the reaction tank through the sprayer.

3. The system for preparing DMC according to claim 2, wherein the height of the connection port of said circulation line to said reaction tank in the vertical direction is not lower than the micro-interface generator located above; and the circulating pipeline is provided with a circulating pump, a check valve and a flow valve.

4. The system for the production of DMC of claim 1, wherein both of said micro-interface generators are pneumatic micro-interface generators.

5. The system for preparing DMC according to claim 1, wherein a guide disk is disposed at the outlet of each of the two micro-interface generators, and a plurality of guide circular holes are uniformly disposed on the guide disk.

6. The system for preparing DMC according to claim 1, characterized in that the top of the rectification column is provided with a condenser, and the gas at the top of the rectification column is discharged after being condensed by the condenser.

7. The system for preparing DMC according to claim 1, characterized in that, the rectifying tower is provided with a side draw outlet at its upper part, and a side draw pump is connected to the side draw outlet and connected to the methanol pipeline.

8. The system for the preparation of DMC of claim 1, further comprising an adsorption tower; the bottom of the rectifying tower is provided with a product outlet which is connected with a reboiler, the product in the rectifying tower is divided into gas-liquid two-phase material flows through the reboiler, the gas-phase material flow enters the rectifying tower, and the liquid-phase material flow flows into the adsorption tower.

9. Method for the preparation of DMC using a system for the preparation of DMC according to any one of claims 1 to 8, characterized by the steps of:

respectively crushing methanol and synthesis gas through a micro interface, and mixing the methanol and the synthesis gas with a catalyst to perform carbonylation reaction to obtain a product DMC; the catalyst is cuprous chloride.

10. The process according to claim 9, wherein the carbonylation reaction temperature is 110 ℃ and 115 ℃ and the pressure is 1.5 to 2.0 MPa.

Technical Field

The invention relates to the field of methanol carbonylation reaction preparation, in particular to a system and a method for preparing DMC.

Background

A liquid-phase methanol oxidizing and carbonylating method based on CH₃OH、O₂And a method for synthesizing DMC by CO under the action of catalyst.

The existing production process flow is generally carried out in two sets of reaction devices. Each set of reaction device consists of two parallel reactors and a gas-liquid separation tank. The reaction temperature is 115 ℃ and 120 ℃, and the reaction pressure is 2.2-2.5 MPaG. The normal operation liquid level of the gas-liquid separation tank is about 50 percent. The catalyst is cuprous chloride catalyst, the particle size of the catalyst particles is 200 meshes (74 mu m), the catalyst particles are in a pseudo-homogeneous state in the slurry, and the content is 1.5-3% (wt).

The liquid phase feeding of the reactor is fresh methanol and methanol circulated by the system, and the fresh methanol and the methanol are mixed and then enter a downcomer at the bottom of the gas-liquid separation tank to flow into the bottom of the reactor respectively. Fresh O in gas phase feed₂And CO and circulating gas (mainly CO) are mixed and then respectively enter the two reactors in a bubbling mode through a distributor at the bottom of the two reactors. To ensure O₂Fully reacting, and controlling O in the exhaust gas₂The content is below the explosive limit and the oxygen concentration in the feed is < 5%. In two reactors, O₂And generating DMC and water by the CO and the methanol under the action of a catalyst. The top of the two reactors is connected with a gas-liquid separating tank through a pipeline, and the gas-liquid mixture on the upper part of the reactors enters the gas-liquid separating tank for separation. The separated gas phase mixture is sent to a downstream device, and the main components are CO, DMC, methanol and CO₂And water. The liquid phase at the bottom of the separation tank is mixed with the raw material methanol from the downcomer and then circulated back toThe bottoms of the two reactors.

The methanol oxidative carbonylation reaction is exothermic, the heat of reaction generated by 1mol of DMC is about 310kJ, the reaction material is discharged in a gas phase, and the latent heat of vaporization is 31 kJ/mol. Because the conversion per pass of the raw materials is low, the total exothermic amount of the reaction is relatively small, and the constant reaction temperature needs to be regulated by supplementing heat through a U-shaped heat exchanger inside the reactor. 4 heat exchangers are arranged in each reactor, and the steam consumption is about 0-10 t/h.

The main problems of the existing DMC production process are as follows:

(1) the raw material gas mixture is initially distributed at the bottom of the reactor through a distributor and then is bubbled into a liquid phase. Because the opening of the distributor is in millimeter level (phi 5mm), the diameter of the generated bubbles is larger (8-15 mm), the gas-liquid interface area is smaller, the initially distributed bubbles are easy to coalesce in the rising process, the bubbles in the reactor are distributed unevenly, and in addition, the liquid circulation adopts a density difference circulation mode, the flow rate is slower (less than 0.1m/s), so that the gas-liquid mass transfer rate is lower, and the macroscopic reaction rate is seriously lower than the design expected value;

(2)O₂the consumption is high, but the actual effective utilization rate is low;

(3) the single-pass conversion rate of CO is about 2-8%, and the feeding amount of CO is more, so that the power consumption of a fresh CO compressor and a circulating CO compressor is larger;

(4) because the product DMC stays in the system for too long time and undergoes hydrolysis reaction with water, CO is generated₂With CO and O₂Side reactions are easy to occur, and the factors greatly reduce the conversion rate of raw materials.

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

Disclosure of Invention

The first purpose of the invention is to provide a system for preparing DMC, the system improves the utilization rate of temperature and reduces the energy consumption by arranging a reaction tank in a rectifying tower and heating the reaction tank by using the temperature in the rectifying tower; the reactor is internally provided with the micro-interface generator to disperse and crush the methanol and the synthesis gas respectively and then carry out carbonylation reaction, so that the gas-liquid mass transfer area of the methanol and the synthesis gas is increased, the reaction rate is increased, and the reaction energy consumption is reduced.

The second purpose of the invention is to provide a preparation method for preparing DMC by using the system, which has simple operation, can obviously reduce energy consumption and improve DMC yield and methanol conversion rate.

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

the present invention provides a system for preparing DMC, comprising: the device comprises a reaction tank and a rectifying tower, wherein the reaction tank is arranged in the middle of the rectifying tower, and a methanol pipeline and a mixed gas pipeline are arranged on the side wall of the rectifying tower from top to bottom; the methanol pipeline and the mixed gas pipeline penetrate through the side wall of the rectifying tower to enter the reaction tank; the methanol and the mixed gas react in the reaction tank, and a reaction product enters the rectifying tower from the top of the reaction tank;

two micro-interface generators are sequentially arranged in the reaction tank from top to bottom, and outlets of the two micro-interface generators are oppositely arranged; the micro-interface generator positioned above is connected with the methanol pipeline; the micro-interface generator positioned at the lower part is connected with the mixed gas pipeline; and after the methanol and the mixed gas are respectively dispersed and crushed into micro-bubbles at the micron level by the micro-interface generator, the micro-bubbles react in the reaction tank.

In the prior art, the DMC production process has the main problems that: the raw material gas mixture is initially distributed at the bottom of the reactor through a distributor and then is bubbled into a liquid phase. Because the opening of the distributor is in millimeter level (phi 5mm), the diameter of the generated bubbles is larger (8-15 mm), the gas-liquid interface area is smaller, the initially distributed bubbles are easy to coalesce in the rising process, the bubbles in the reactor are distributed unevenly, and in addition, the liquid circulation adopts a density difference circulation mode, the flow rate is slower (less than 0.1m/s), so that the gas-liquid mass transfer rate is lower, and the macroscopic reaction rate is seriously lower than the design expected value; and the conversion rate of methanol is low, the raw material waste is serious, and the DMC yield is severely limited.

In order to solve the technical problems, the invention provides a system for preparing DMC, which uses a micro-interface generator to respectively crush methanol and mixed gas into micro-bubbles at micron level, thereby increasing the mass transfer area between the methanol and the mixed gas, improving the mass transfer effect, greatly improving the mass transfer rate and reducing the temperature and pressure required by the reaction; the outlets of the two micro-interface generators are oppositely arranged, so that the uniform distribution of micro-bubbles in the reaction tank is promoted; the reaction tank and the rectifying tower are combined in the tower kettle, and the temperature in the rectifying tower is utilized to heat the reaction tank, so that the temperature utilization rate is improved, and the energy consumption is reduced.

Preferably, the side wall of the reaction tank is connected with a circulating pipeline, and the top of the reaction tank is provided with a sprayer; the circulating pipeline is connected with the sprayer, and the liquid phase in the reaction tank enters the sprayer along the circulating pipeline and is sprayed back to the reaction tank through the sprayer. By spraying the liquid phase from the top of the reaction tank, it is possible to react with unreacted gas, promote the conversion of CO and the like, and improve the yield of DMC.

Preferably, the height of a connecting port of the circulating pipeline and the reaction tank along the vertical direction is not lower than that of the micro-interface generator positioned above the connecting port; and the circulating pipeline is provided with a circulating pump, a check valve and a flow valve. During reaction, a high-pressure area for reaction is arranged from the upper micro-interface generator to the bottom of the reaction tank, the reaction is violent, and the reaction is complete mixed flow; the top is a low pressure area, which is plug flow. The liquid phase in the low-pressure area is basically free of mixed gas, mainly contains a large amount of unreacted methanol, and the methanol is sprayed and dropped in a spraying mode, so that the unreacted gas can be neutralized and continuously reacted, and the conversion rate of raw materials is improved.

Preferably, both of the micro-interface generators are pneumatic micro-interface generators.

Preferably, the outlets of the two micro-interface generators are both provided with a guide disc, and a plurality of guide circular holes are uniformly formed in the guide disc. Through setting up the direction disc, make the microbubble distribute more evenly to be favorable to going on of reaction.

Two micro-interface generators are arranged in a reaction tank to disperse and crush methanol and mixed gas respectively, and during reaction, the methanol and the mixed gas are dispersed and crushed into micro bubbles at the micron level by the micro-interface generators respectively and then subjected to carbonylation reaction, so that the phase boundary mass transfer area of the methanol and the mixed gas is increased; the outlets of the two micro-interface generators are opposite, so that the opposite impact effect can be achieved, and the uniform distribution of micro-bubbles can be realized. The distributor is arranged at the outlet of the micro-interface generator, also to promote the uniform distribution of the micro-bubbles.

It should be noted that when the micro-interface generator is arranged, the micro-interface generator positioned at the upper part is connected with a methanol pipeline, the micro-interface generator positioned at the lower part is connected with a synthesis gas pipeline, the synthesis gas is relatively synthesized in advance by a gas source, and is combustible with CO and O in the synthesis gas raw material₂The reaction is easy to explode, so in order to improve the safety of the reaction, the air inlet is arranged at a lower position as much as possible, and meanwhile, the micro-interface generator for crushing methanol is arranged at the upper part and the micro-interface generator for crushing synthesis gas is arranged at the lower part in view of the fact that the micro-interface generator flows towards the top of the reactor more easily after entering the reactor.

In addition, the present invention is also provided with a circulation line and a shower, and the liquid phase is sprayed from the top of the reaction tank to react with unreacted gas, thereby promoting the conversion of CO and the like and improving the yield of DMC. Therefore, the invention improves the application effect of the micro-interface generator by combining the distributor, the micro-interface generator and the sprayer.

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 numbers CN201610641119.6, CN201610641251.7, 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.

Preferably, a condenser is arranged at the top of the rectifying tower, and gas at the top of the rectifying tower is discharged after being condensed by the condenser.

Preferably, a side draw outlet is arranged at the upper part of the rectifying tower, and is connected with a side draw pump, and the side draw pump is connected with the methanol pipeline.

Preferably, the device also comprises an adsorption tower; the bottom of the rectifying tower is provided with a product outlet which is connected with a reboiler, the product in the rectifying tower is divided into gas-liquid two-phase material flows through the reboiler, the gas-phase material flow enters the rectifying tower, and the liquid-phase material flow flows into the adsorption tower.

Preferably, the number of the adsorption towers is two, and the two adsorption towers are arranged in parallel. When the device is used, the device can be used simultaneously, only one of the device can be used, and when one of the device needs to be overhauled, the other device can be directly used, so that uninterrupted production can be guaranteed.

Preferably, an evaporator is arranged on the methanol pipeline; the reaction tank and the rectifying tower are arranged concentrically.

The invention also provides a preparation method of the system for preparing DMC, which comprises the following steps:

respectively crushing methanol and synthesis gas through a micro interface, and mixing the methanol and the synthesis gas with a catalyst to perform carbonylation reaction to obtain a product DMC; the catalyst is cuprous chloride.

Preferably, the carbonylation reaction temperature is 110-115 ℃ and the pressure is 1.5-2.0 MPa.

The DMC product obtained by the reaction method of the invention 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 system for preparing DMC, the micro-interface generator is used for respectively crushing the methanol and the mixed gas into micro-bubbles at the micron level, so that the mass transfer area between the methanol and the mixed gas is increased, the mass transfer effect is improved, the mass transfer rate is greatly improved, and the temperature and the pressure required by the reaction are reduced;

(2) the outlets of the two micro-interface generators are oppositely arranged, so that the uniform distribution of micro-bubbles in the reaction tank is promoted;

(3) the reaction tank and the rectifying tower are combined in the tower kettle, and the temperature in the rectifying tower is utilized to heat the reaction tank, so that the temperature utilization rate is improved, and the energy consumption is reduced.

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 system for preparing DMC provided by the embodiment of the present invention.

Description of the drawings:

10-a rectification column; 20-a reaction tank;

30-a mixed gas line; a 40-methanol line;

50-an evaporator; 60-a condenser;

70-a sprayer; 80-flow valve;

90-circulating pump; 100-check valve;

110-a micro-interface generator; 120-a guide disc;

130-side draw pump; 140-a reboiler;

150-adsorption tower.

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, the present embodiment provides a system for preparing DMC, comprising: the device comprises a reaction tank 20 and a rectifying tower 10, wherein the reaction tank 20 is arranged in the middle of the rectifying tower 10, and a methanol pipeline 40 and a mixed gas pipeline 30 are arranged on the side wall of the rectifying tower 10 from top to bottom; the methanol pipeline 40 and the mixed gas pipeline 30 both penetrate through the side wall of the rectifying tower 10 and enter the reaction tank 20; the methanol and the mixed gas react in the reaction tank 20, and the reaction product enters the rectifying tower 10 from the top of the reaction tank 20; the methanol pipeline 40 is provided with an evaporator 50; the reaction tank 20 is disposed concentrically with the rectifying tower 10.

Wherein, two micro-interface generators 110 are sequentially arranged in the reaction tank 20 from top to bottom, and outlets of the two micro-interface generators 110 are oppositely arranged; the micro-interface generator 110 located above is connected with the methanol pipeline 40; the lower micro-interface generator 110 is connected to the mixing gas line 30; the methanol and the mixed gas are dispersed and broken into micro-bubbles of micron level by the micro-interface generator 110, and then reacted in the reaction tank 20. Both micro-interface generators 110 are pneumatic micro-interface generators 110.

The outlets of the two micro-interface generators 110 are both provided with a guide disc 120, and a plurality of guide circular holes are uniformly arranged on the guide disc 120. By arranging the guiding disc 120, the micro-bubbles are distributed more uniformly, thereby facilitating the reaction.

Continuing to refer to fig. 1, the side wall of the reaction tank 20 is connected with a circulation pipeline, and the top of the reaction tank 20 is provided with a sprayer 70; the circulation line is connected to a shower 70, and the liquid phase in the reaction tank 20 enters the shower 70 along the circulation line and is sprayed back into the reaction tank 20 through the shower 70. By spraying the liquid phase from the top of the reaction tank 20, the reaction with the unreacted gas can be promoted, and the conversion of CO and the like can be promoted, thereby improving the yield of DMC.

Wherein, the height of the connecting port of the circulating pipeline and the reaction tank 20 along the vertical direction is not lower than that of the micro-interface generator 110 positioned above; a circulation pump 90, a check valve 100 and a flow valve 80 are provided on the circulation line. During reaction, a high-pressure region for reaction is formed from the upper micro-interface generator 110 to the bottom of the reaction tank 20, the reaction is violent, and the reaction is a complete mixed flow; the top is a low pressure area, which is plug flow. The liquid phase in the low-pressure area is basically free of mixed gas, mainly contains a large amount of unreacted methanol, and the methanol is sprayed and dropped in a spraying mode, so that the unreacted gas can be neutralized and continuously reacted, and the conversion rate of raw materials is improved.

In this embodiment, a condenser 60 is disposed at the top of the rectifying tower 10, and the gas at the top of the rectifying tower 10 is condensed by the condenser 60 and then discharged. The upper part of the rectifying tower 10 is provided with a side draw outlet, the side draw outlet is connected with a side draw pump 130, and the side draw pump 130 is connected with the methanol pipeline 40.

The system of this embodiment further includes an adsorption column 150; the bottom of the rectifying tower 10 is provided with a product outlet, the product outlet is connected with a reboiler 140, the product in the rectifying tower 10 is divided into gas-liquid two-phase material flow through the reboiler 140, the gas-phase material flow enters the rectifying tower 10, and the liquid-phase material flow enters the adsorption tower 150.

Wherein, the number of the adsorption towers 150 is two, and the two adsorption towers 150 are arranged in parallel. When the device is used, the device can be used simultaneously, only one of the device can be used, and when one of the device needs to be overhauled, the other device can be directly used, so that uninterrupted production can be guaranteed.

During the reaction, methanol and mixed gas are simultaneously introduced into the reaction tank 20, and are respectively dispersed into micro bubbles by the two micro interface generators 110, then the reaction is carried out under the participation of the catalyst, the reaction product flows into the rectifying tower 10 for refining, and then the water in the product is removed by the adsorption tower 150, thus obtaining the product DMC.

Wherein, the specific process parameters of the reaction are as follows:

methanol conversion-mol of methanol converted/mol of methanol fed,

DMC yield is the molar flow rate of DMC produced per molar amount of methanol fed.

As can be seen from the above table, the conversion per pass of methanol reached 20.35% (typical prior art processes are 13%) and the DMC yield reached 17.04% (typical prior art processes are 8-12%). The reaction temperature is 112 ℃, the pressure is 1.7MPa, while the existing reaction temperature is generally 120-125 ℃ and the pressure is 2.2-2.5MPa, thus the system of the embodiment has obviously reduced temperature and pressure compared with the existing process.

Example 2

This example is different from example 1 only in terms of process parameters, and the specific process parameters are as follows:

wherein the reaction temperature is 110 ℃ and the pressure is 1.5 MPa.

Through calculation, the single-pass conversion rate of the methanol reaches 20.11 percent, and the yield of the DMC reaches 17.40 percent. It can be seen that the system of the present embodiment has a significant reduction in temperature and pressure relative to existing processes.

Example 3

This example is different from example 1 only in terms of process parameters, and the specific process parameters are as follows:

wherein the reaction temperature is 115 ℃ and the pressure is 2 MPa.

Through calculation, the single-pass conversion rate of the methanol reaches 20.18 percent, and the yield of the DMC reaches 17.06 percent. It can be seen that the system of the present embodiment has a significant reduction in temperature and pressure relative to existing processes.

In conclusion, compared with the DMC preparation system in the prior art, the system provided by the invention can obviously reduce the required reaction temperature and pressure, has few side reactions and high methanol conversion rate in the whole reaction process, 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.