Reaction system and method for preparing methanol through hydrogenation of carbon dioxide

Abstract

The invention provides a reaction system and method for preparing methanol through hydrogenation of carbon dioxide, and the reaction system at least comprises a reactor, the reactor comprises a shell with a cavity, a plurality of reaction tubes which are arranged in the shell and are used for providing reaction cavities, and a plurality of baffle plates which are arranged in the shell and are used for increasing the contact area of hot air outside the reaction tubes; according to the reaction system for preparing methanol through hydrogenation of carbon dioxide, the feed gas is heated by utilizing product heat, heat is transferred by utilizing heat exchange between a tube pass and a shell pass, an external heat source and a cooling medium are not needed, energy is saved, the temperature in the reaction process is controllable, and the loss of reaction equipment caused by temperature fluctuation is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical equipment and process, and in particular relates to a reaction system and method for preparing methanol by hydrogenating carbon dioxide. Background Art

[0002] The production of methanol from CO2 plus H2 is an exothermic reaction process, and the thermal management of the reactor has a significant impact on the reaction results. On the one hand, a higher reaction temperature is conducive to the activation of CO2 to improve the reaction efficiency; on the other hand, since this reaction is a typical thermodynamic equilibrium-limited reaction, an increase in temperature not only leads to a decrease in the equilibrium conversion rate, but also increases the selectivity of the byproduct CO. A moderate reaction temperature should be selected after weighing the pros and cons.

[0003] The conventional method uses a tubular fixed bed reactor and removes the reaction heat by boiling water or a steam drum to keep the temperature uniform. Among them, the boiling water removes the reaction heat by using boiling water as a heat removal medium to remove the heat generated by the reaction. In this system, water is heated to boiling inside or outside the reactor, and then evaporates to take away the heat. This method has the problem of difficult temperature control, especially when the reaction exotherm is large, a temperature runaway phenomenon may occur, that is, the reaction temperature loses control, rises sharply, and exceeds the appropriate range. This method also requires the addition of a steam recovery system, which has the problem of large equipment investment. The steam drum removes the reaction heat by generating steam through the steam drum while removing the reaction heat. In this system, the heat generated by the reactor is used to heat the water in the steam drum to generate steam, and then the heat is removed by discharging the steam. The high-pressure steam generated by the reactor is directly reduced to produce medium-pressure steam. The intermediate energy loss is very large, and the energy cannot be maximized. There are problems of energy waste and low energy efficiency; in addition, the internal results of the reactor using the steam drum to remove heat are complicated and the operation process is complicated.

[0004] In view of the shortcomings of conventional methods, Poland disclosed an autothermal reactor filled with catalysts in both the tube side and the shell side as early as 1990 (patent number: B1 163570). This design uses countercurrent heat transfer between the tube side and the shell side to achieve autothermal balance. However, due to the countercurrent heat transfer, the heat transfer temperature difference between the tube and shell side is large, which is prone to local overheating or thermal failure. In addition, the catalyst filling in the tube and shell side increases the fluid resistance, resulting in an increase in pressure drop. In order to maintain the normal operation of the system, it is necessary to increase the flow rate of the feed gas. This method not only increases energy consumption, but also increases the difficulty of controlling the temperature distribution, thereby reducing the operability and operation stability of the reactor. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a reaction system and method for producing methanol by hydrogenation of carbon dioxide, so as to solve the problems of low energy efficiency, difficult temperature control, complex process flow and high equipment investment in the reaction system and method for producing methanol by hydrogenation of carbon dioxide in the prior art.

[0006] To achieve the above-mentioned object and other related objects, the present invention provides a reaction system and method for producing methanol by hydrogenating carbon dioxide.

[0007] The first aspect of the present invention provides a carbon dioxide hydrogenation methanol reaction system, the reaction system at least includes a reactor, the reactor includes a shell with a chamber, a plurality of reaction tubes arranged in the shell for providing a reaction chamber, and a plurality of baffles arranged in the shell for increasing the contact area of ​​the outside of the reaction tubes with the heating gas; the shell is provided with a raw gas inlet end and a product gas outlet end; a first partitioning inlet plate circumferentially fixed in the shell is provided near the raw gas inlet end; a second partitioning outlet plate circumferentially fixed in the shell is provided near the product gas outlet end; a plurality of spaced air flow holes are correspondingly formed on the first partitioning inlet plate and the second partitioning outlet plate, and the two ends of the plurality of reaction tubes are respectively connected to the air flow holes; one end of the plurality of baffles is fixed on the inner wall of the shell and is located between the first partitioning inlet plate and the second partitioning outlet plate; a heating gas inlet end and a heating gas outlet end are formed on the side wall of the shell, and the plurality of baffles are arranged between the heating gas inlet end and the heating gas outlet end.

[0008] Preferably, the reaction system further comprises a shell bypass pipe connected to the heating gas outlet and the raw gas inlet so as to allow the heating gas to enter the reaction chamber to participate in the reaction.

[0009] Preferably, each of the baffles extends radially inward from the inner wall of the shell to penetrate a portion of the reaction tubes so as to limit the flow direction of the heating gas.

[0010] Preferably, there are multiple baffles, which are arranged parallel to each other to form a continuous S-shaped airflow channel.

[0011] Preferably, the aspect ratio of the reactor is 4 to 5; for example, it may be 4 to 4.2, 4.2 to 4.4, 4.4 to 4.6, 4.6 to 4.8, or 4.8 to 5.0.

[0012] The aspect ratio of the reactor of the present invention is the ratio of the longitudinal direction to the transverse direction of the reactor.

[0013] Preferably, at least one temperature indicator is provided on the housing.

[0014] Preferably, at least one pressure indicator is provided on the housing.

[0015] Preferably, the reaction system also includes a heat exchanger for performing heat exchange on the raw gas to heat it, the heat exchanger includes a tube bundle for the raw gas to pass through, and a shell layer arranged outside the tube bundle, a heat source chamber for the heat source gas to pass through is formed between the shell layer and the tube bundle; the shell layer forms a heat source gas outlet end; the product gas outlet end is connected to the heat source chamber through a product heat recovery channel to utilize the heat of the product gas to heat the raw gas; the raw gas outlet end of the tube bundle is connected to the heating gas inlet end of the reactor through a heating gas feed channel.

[0016] Preferably, the baffle is a 20-25% area cut-off baffle.

[0017] The 20% to 25% area cut-off baffle mentioned in the present invention refers to the percentage of the cut-off area of ​​the baffle to the total baffle.

[0018] In some preferred embodiments of the present invention, the number of the baffles is 2, 3, 4 or 5.

[0019] The present invention can prolong the residence time of the raw gas in the shell by arranging the baffles, so that the raw gas is more evenly heated by the reaction heat generated in the reaction tubes, thereby ensuring that the temperature of the raw gas entering the reaction tubes is within a range suitable for the catalytic reaction.

[0020] Preferably, the reaction tubes may be arranged at multiple angles, for example, 30°, 60°, 45° or 90°.

[0021] The arrangement angle of the reaction tubes described in the present invention refers to the angle formed between the center line connecting adjacent tubes and the flow direction of the fluid in the shell in the geometric arrangement of the reaction tubes.

[0022] Preferably, a temperature indicator is provided on the shell bypass pipe.

[0023] Preferably, a pressure indicator is also provided on the shell bypass pipeline.

[0024] Preferably, the reaction system further comprises a raw gas mixing tank, and the gas outlet end of the raw gas mixing tank is connected to the raw gas inlet end of the tube bundle through a raw gas mixing channel.

[0025] Preferably, a pressure indicator is provided on the heating gas feed channel.

[0026] Preferably, a temperature indicator is provided on the heating gas feed channel.

[0027] Preferably, a switch valve is provided on the heating gas feed channel.

[0028] Preferably, a pressure indicator is provided on the product heat recovery channel.

[0029] Preferably, a temperature indicator is provided on the product heat recovery channel.

[0030] Preferably, a switch valve is provided on the product heat recovery channel.

[0031] Preferably, the reaction system further comprises a condenser for condensing the heat source gas and a product condensate collection channel, and the feed end of the condenser is connected to the heat source gas discharge end through the product condensate collection channel.

[0032] Preferably, the reaction system further comprises a raw material gas channel, one end of which is connected to the gas inlet end of the raw material mixing tank.

[0033] Preferably, a pressure gauge is provided on the raw mixed gas channel.

[0034] Preferably, a switch valve is provided on the raw mixed gas channel.

[0035] Preferably, a temperature indicator is provided on the raw mixed gas channel.

[0036] Preferably, a switch valve is provided on the product condensation collection channel.

[0037] Preferably, a gas compressor is provided on the raw gas channel.

[0038] Preferably, a switch valve is provided on the raw gas channel.

[0039] Preferably, a pressure gauge is provided on the raw gas channel.

[0040] Preferably, the air inlet ends of the raw gas channel are independently connected to a carbon dioxide air inlet system and a hydrogen air inlet system.

[0041] Preferably, the carbon dioxide intake system comprises a carbon dioxide gas source and a carbon dioxide intake section pipeline, the carbon dioxide intake section pipeline is used to connect the carbon dioxide gas source and the intake end of the raw gas channel; the carbon dioxide intake section pipeline is provided with one or more of a first filter, a first switch valve, a first pressure gauge, a first flow meter and a first check valve; the hydrogen intake system comprises a hydrogen gas source and a hydrogen intake end pipeline, the hydrogen intake section pipeline is used to connect the hydrogen gas source and the intake end of the raw gas channel; the hydrogen intake section pipeline is provided with one or more of a second filter, a second switch valve, a second pressure gauge, a second flow meter and a second check valve.

[0042] The carbon dioxide hydrogenation methanol reaction system of the present invention can monitor the pressure condition in the system in real time by means of a pressure gauge and a pressure indicator, and can monitor the temperature condition in the system in real time by means of a temperature indicator.

[0043] The second aspect of the present invention provides a method for producing methanol by hydrogenating carbon dioxide. The method is carried out by the carbon dioxide hydrogenation to methanol reaction system described in the first aspect of the present application. The method comprises: a mixture of carbon dioxide and hydrogen is preheated and then enters a reactor, reacts under the action of a catalyst, and obtains a reaction product.

[0044] Preferably, the molar ratio of the carbon dioxide to the hydrogen inlet gas is 1:(1-5).

[0045] More preferably, the molar ratio of carbon dioxide to hydrogen is 1:(2-5); for example, it can be 1:(2-3), 1:(3-4) and or 1:(4-5).

[0046] In some preferred embodiments of the present invention, the molar ratio of carbon dioxide to hydrogen is 1:3.

[0047] Preferably, the reaction pressure is 60-80 bar.

[0048] More preferably, the reaction pressure is 65-75 bar.

[0049] Preferably, the pressure drop in the reaction tubes is 0.6-0.7 bar.

[0050] Preferably, the reaction catalyst is a copper-based catalyst.

[0051] Further preferably, the reaction catalyst is selected from one or more of Cu-Zn-Al2O3, Cu-ZnO-Al2O3, and Cu-ZnO-ZrO2.

[0052] Preferably, the reaction temperature is 180-280°C.

[0053] More preferably, the reaction temperature may be 180-200°C, 200-220°C, 220-230°C, 230-240°C, 240-250°C, 250-260°C and 260-280°C.

[0054] Preferably, the raw gas is preheated in the heat exchanger for the first time and then enters the shell of the reactor through the heating gas feed channel, and then enters the reaction tubes through the shell bypass pipe to react and form product gas; the product gas is cooled after passing through the product heat recovery channel to the heat source chamber of the heat exchanger.

[0055] Preferably, the temperature of the mixed gas of carbon dioxide and hydrogen after passing through the heat exchanger is 180-190°C.

[0056] The present invention preheats the mixture of carbon dioxide and hydrogen by utilizing the heat of the product gas, so that the temperature of the mixture reaches 180-190°C, which not only realizes the heat recovery and utilization, but also enables the preliminary cooling of the mixture, making it easier to condense the mixture and collect methanol.

[0057] After the raw gas of the present invention is preheated for the first time by the heat exchanger and enters the shell of the reactor through the heating gas feed channel, it flows between the reaction tubes in the shell. Since the carbon dioxide and hydrogen in the reaction tubes undergo an exothermic reaction under the action of the catalyst, the temperature in the reaction tubes rises, and the gas in the tubes and the gas in the shell are heat-transferred and coupled while flowing in parallel, and the mixed gas is further preheated for the second time. After the second preheating, the temperature of the mixed gas of carbon dioxide and hydrogen is 180-220°C.

[0058] Preferably, the ratio of the diameter of the reaction tubes to the diameter of the catalyst particles is ≥10.

[0059] In the present application, the diameter of the reaction tubes can generally be selected from 1 to 10 cm, and the diameter of the reaction tubes includes but is not limited to 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, and 10 cm.

[0060] In the present invention, if the diameter of the catalyst particles is too large, the gaps between the larger particle sizes will be large, which will cause the gas to stay in the catalyst for too short a time and fail to fully react; if the diameter of the catalyst particles is too small, the gaps will be too small, thereby reducing the heat transfer efficiency and failing to transfer sufficient reaction heat to the gas in the shell.

[0061] More preferably, the ratio of the diameter of the reaction tube to the diameter of the catalyst particles is 10-50; for example, it can be 10-20, 20-30, 30-40, or 40-50.

[0062] Preferably, the ratio of the gaps between the catalyst particles to the total volume of the tube array is 0.4-0.5; for example, it can be 0.4-0.41, 0.41-0.42, 0.42-0.43, 0.43-0.44, 0.44-0.45, 0.45-0.46, 0.46-0.47, 0.47-0.48, 0.48-0.49 and 0.49-0.5.

[0063] Preferably, the carbon dioxide and hydrogen stay in the catalyst for 0.5 to 5 seconds.

[0064] More preferably, the reaction gas stays in the catalyst for 0.5 to 3 s; for example, it may be 0.5 to 1 s, 1 to 1.5 s, 1.5 to 2.0 s, 2.0 to 2.5 s, or 2.5 to 3 s.

[0065] In the present invention, when the reaction gas stays in the catalyst for too short a time, the reaction gas will not be able to fully react and the reaction efficiency will be low; when the reaction gas stays in the catalyst for too long, the local temperature in the reactor will be too high, resulting in thermal mismatch, affecting the stability of the catalyst or causing side reactions.

[0066] Preferably, the feed flow rate of the carbon dioxide is 1000-10000 kg / h.

[0067] Preferably, the feed rate of hydrogen is 100-1000 kg / h.

[0068] In the present invention, the flow ratio of carbon dioxide and hydrogen can be adjusted according to the output demand of the target product.

[0069] As described above, the reaction system and method for producing methanol by hydrogenating carbon dioxide of the present invention have the following beneficial effects:

[0070] 1. The carbon dioxide hydrogenation to methanol reaction system of the present application realizes heating of the feed stream by direct coupling of heat transfer and reaction in the reactor through the form of co-current flow of fluids in the shell and tube side and direct coupling of heat transfer and reaction, thereby effectively utilizing reaction heat, shortening the process and reducing investment costs.

[0071] 2. The carbon dioxide hydrogenation to methanol reaction system of the present application can effectively utilize the reaction heat and transfer the reaction heat generated by the catalytic reaction in the tube, thereby controlling the reaction temperature distribution in the tube to be within a range suitable for methanol production, thereby effectively avoiding the problem of local overheating caused by excessive heat transfer temperature difference, making the reactor heated evenly, reducing the risk of damage, and reducing the long-term operation and maintenance costs of the equipment.

[0072] 3. The carbon dioxide hydrogenation to methanol reaction system of the present application recycles heat through heat transfer, thus saving energy consumption;

[0073] The shell-side fluid is introduced into the tube-side through the transfer pipe for reaction, and the tube-side reaction heat is used to heat the shell-side fluid, realizing the in-situ utilization of the reaction heat. The reaction heat heats the intake air, thereby reducing the requirements for the feed gas temperature, eliminating the need for external cooling medium, and saving energy.

[0074] 4. The carbon dioxide hydrogenation to methanol reaction system of the present application is simple to operate, and the reaction equipment is not prone to thermal runaway problems, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 It shows a schematic diagram of the structure of the reactor in the reaction system for producing methanol by hydrogenation of carbon dioxide according to the present invention.

[0076] Figure 2Shown is a schematic structural diagram of a reaction system for producing methanol from carbon dioxide hydrogenation according to the present invention.

[0077] Figure 3 Shown is a schematic diagram of the structures of various parts in the reaction system for producing methanol from carbon dioxide hydrogenation according to the present invention.

[0078] Figure 4 Shown is a schematic diagram of a 25% baffle according to the present invention.

[0079] Figure 5 It shows different arrangement states between the reaction tubes of the present invention.

[0080] Figure 6 It is a schematic diagram of the structure of a boiling water heat removal reactor in the prior art.

[0081] Figure 1 The reference numerals in the accompanying drawings are explained as follows: 1 is a reactor, 11 is a reaction tube, 12 is a shell, 13 is a first baffle, 14 is a second baffle, 15 is a third baffle, 16 is a first partition air inlet plate, 17 is a second partition air outlet plate, a is a heating gas inlet inlet, b is a heating gas outlet, 18 is a raw gas inlet, 19 is a product gas outlet, 2 is a shell bypass pipeline, 21 is a third temperature indicator, 22 is a second pressure indicator, 3 is a heat exchanger, 4 is a raw material mixing tank, 5 is a raw material gas channel, 51 is a gas compressor, 52 is a third switch valve, 53 is a third pressure gauge, 6 is a raw material mixed gas channel, 61 is a fourth pressure gauge, 62 is a fourth switch valve, 63 is a first temperature indicator, 7 is a heating gas feed channel, 71 is a first pressure indicator, 72 is a second temperature indicator , 73 is the fifth switch valve, 8 is the product heat recovery channel, 81 is the fourth pressure indicator, 82 is the seventh temperature indicator, 83 is the sixth switch valve, 9 is the product outlet channel, 91 is the seventh switch valve, 10 is the carbon dioxide intake system, 101 is the carbon dioxide cylinder, 102 is the first filter, 103 is the first switch valve, 104 is the first pressure gauge, 105 is the first mass flow meter, 106 is the first check valve, 11 is the hydrogen intake system, 111 is the hydrogen cylinder, 112 is the second filter, 113 is the second switch valve, 114 is the second pressure gauge, 115 is the second mass flow meter, 116 is the second check valve, 121 is the fourth temperature indicator, 122 is the third pressure indicator, 123 is the fifth temperature indicator, and 124 is the sixth temperature indicator.

[0082] Figure 2 The reference numerals in the figures are explained as follows: C1 is the baffle reserved area, C2 is the baffle cut-off area, and C3 is the baffle through hole. DETAILED DESCRIPTION

[0083] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0084] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0085] In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in the present invention does not exclude the existence of other devices / apparatuses before or after the combination device / apparatus or the insertion of other devices / apparatuses between these explicitly mentioned two devices / apparatuses. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or the scope of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the present invention without substantially changing the technical content.

[0086] See also Figure 1 to Figure 3 . It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0087] like Figure 1 to Figure 3As shown, a specific reaction system for the hydrogenation of carbon dioxide to methanol reaction is provided, and the reaction system at least comprises: a reactor 1, wherein the reactor 1 comprises a shell 12 having a chamber, a plurality of reaction tubes 11 arranged in the shell 12 for providing a reaction chamber, and a plurality of baffles 13 arranged in the shell 12 for increasing the contact area of ​​the outside of the reaction tubes with the hot gas; a raw gas inlet end and a product gas outlet end are provided on the shell 12; a first partition inlet plate 16 circumferentially fixed in the shell 12 is provided near the raw gas inlet end; a circumferentially fixed first partition inlet plate 16 is provided near the product gas outlet ... To the second partition outlet plate 17 fixed in the shell 12; the first partition inlet plate 16 and the second partition outlet plate 17 are formed with a plurality of spaced air flow holes, and the two ends of the plurality of reaction tubes 11 are respectively connected to the air flow holes; one end of the plurality of baffles 13 is fixed on the inner wall of the shell 12 and is located between the first partition inlet plate 16 and the second partition outlet plate 17; a heating gas inlet end and a heating gas outlet end are formed on the side wall of the shell 12, and the plurality of baffles 13 are arranged between the heating gas inlet end and the heating gas outlet end. The baffles 13 are provided in the reaction system of the carbon dioxide hydrogenation to methanol reaction of the present application to increase the contact area of ​​the reaction tubes 11 with the external heating gas, so that the reaction heat in the reaction tubes 11 can fully heat the gas in the shell 12.

[0088] In a Figure 2 and Figure 3 In the specific embodiment shown, the reaction system further comprises a shell bypass pipe 2 connected to the heating gas outlet and the raw gas inlet so as to allow the heating gas to enter the reaction chamber to participate in the reaction.

[0089] In a Figure 1 In the specific embodiment shown, each of the baffles 13 extends radially inward from the inner wall of the shell to penetrate a portion of the reaction tubes so as to limit the flow direction of the heating gas.

[0090] In a Figure 1 In the specific embodiment shown, there are multiple baffles 11, which are arranged parallel to each other to form a continuous S-shaped airflow channel to extend the residence time of the gas in the shell 12 so that it can be fully heated by the reaction heat in the reaction tubes 11.

[0091] In a Figure 1 In the specific embodiment shown, the aspect ratio of the reactor 1 is 4 to 5, so as to prolong the heating time of the reaction gas and the contact time with the catalyst to allow the reaction to proceed fully.

[0092] In a Figure 2In the specific embodiment shown, at least one temperature indicator is disposed on the shell 12 to monitor the temperature of the gas in the shell 12 in real time.

[0093] In a Figure 2 In the specific embodiment shown, a fourth temperature indicator 121 , a fifth temperature indicator 123 and a sixth temperature indicator 124 are provided on the housing 12 .

[0094] In a Figure 2 In the specific embodiment shown, at least one pressure indicator is provided on the housing 12 to monitor the pressure inside the housing 12 in real time.

[0095] In a Figure 2 In the specific embodiment shown, a third pressure indicator 122 is provided on the housing 12 .

[0096] In a Figure 2 and Figure 3 In the specific embodiment shown, the reaction system further includes a heat exchanger 3 for performing heat exchange on the raw gas to heat the raw gas, the heat exchanger 3 includes a tube bundle for the raw gas to pass through, a shell layer arranged outside the tube bundle, a heat source chamber for the heat source gas to pass through is formed between the shell layer and the tube bundle; the shell layer forms a heat source gas outlet; the product gas outlet is connected to the heat source chamber through a product heat recovery channel 8 to heat the raw gas using the heat of the product gas; the raw gas outlet of the tube bundle is connected to the heating gas inlet of the reactor through a heating gas feed channel 7. By setting the heat exchanger 3, the raw gas flowing through the heat exchanger 3 is heated to a suitable temperature by the heat source to participate in the subsequent reaction.

[0097] In a Figure 1 In the specific embodiment shown, the baffle 13 is a baffle with a 20-25% area cutoff, so as to maintain the gas in the shell within a suitable residence time so that it is heated to a suitable temperature.

[0098] In a Figure 2 In the specific embodiment shown, a third temperature indicator 21 is provided on the shell bypass pipeline 2 to monitor the temperature of the gas in the shell bypass pipeline 2 .

[0099] In a Figure 2 In the specific embodiment shown, a second pressure indicator 22 is provided on the shell bypass pipeline 2 to monitor the pressure in the shell bypass pipeline 2 .

[0100] In a Figure 2 and Figure 3In the specific embodiment shown, the reaction system also includes a raw gas mixing tank 4, the gas outlet end of the raw gas mixing tank 4 is connected to the raw gas inlet end of the tube bundle through a raw mixed gas channel 6 to transport the raw mixed gas to the tube bundle of the heat exchanger 3.

[0101] In a Figure 2 In the specific embodiment shown, a first pressure indicator 71 is provided on the heating gas feed passage 7 to monitor the pressure in the heating gas feed passage 7 .

[0102] In a Figure 2 In the specific embodiment shown, a second temperature indicator 72 is provided on the heating gas feed channel 7 to monitor the gas temperature in the heating gas feed channel 7 .

[0103] In a Figure 2 In the specific embodiment shown, a fifth switch valve 73 is provided on the heating gas feed channel 7 to control the amount of gas passing through in real time by adjusting the opening and closing degree of the switch valve.

[0104] In a Figure 2 In the specific embodiment shown, a fourth pressure indicator 81 is provided on the product heat recovery channel 8 to monitor the pressure in the product heat recovery channel 8 .

[0105] In a Figure 2 In the specific embodiment shown, a seventh temperature indicator 82 is provided on the product heat recovery channel 8 to monitor the temperature of the gas in the product heat recovery channel 8 .

[0106] In a Figure 2 In the specific embodiment shown, a sixth switch valve 83 is provided on the product heat recovery channel 8 to control the amount of gas passing through in real time by adjusting the opening and closing degree of the switch valve.

[0107] In a Figure 2 and Figure 3 In the specific embodiment shown, the reaction system further includes a condenser (not shown in the figure) for condensing the heat source gas and a product condensation collection channel 9, and the feed end of the condenser is connected to the heat source gas discharge end through the product condensation collection channel 9. The product gas is condensed by the condenser to collect methanol.

[0108] In a Figure 2 and Figure 3 In the specific embodiment shown, the reaction system further includes a raw gas channel 5, one end of which is connected to the gas inlet end of the raw material mixing tank 4 so as to pass the raw gas into the raw material mixing tank 4 for mixing.

[0109] In a Figure 2In the specific embodiment shown, a fourth pressure gauge 61 is provided on the raw mixed gas channel 6 to monitor the pressure in the raw mixed gas channel 6 .

[0110] In a Figure 2 In the specific embodiment shown, a fourth switch valve 62 is provided on the raw mixed gas channel 6 to control the amount of gas passing through in real time by adjusting the opening and closing degree of the switch valve.

[0111] In a Figure 2 In the specific embodiment shown, a first temperature indicator 63 is provided on the raw mixed gas channel 6 to monitor the temperature of the gas in the raw mixed gas channel 6 .

[0112] In a Figure 2 In the specific embodiment shown, a seventh switch valve 91 is provided on the product condensation collection channel 9 to control the amount of gas passing through in real time by adjusting the opening and closing degree of the switch valve.

[0113] In a Figure 2 In the specific embodiment shown, a gas compressor 51 is provided on the raw gas channel 5 to compress the raw gas to a specific pressure value.

[0114] In a Figure 2 In the specific embodiment shown, a third switch valve 52 is provided on the raw gas channel 5 to control the amount of gas passing through in real time by adjusting the opening and closing degree of the switch valve.

[0115] In a Figure 2 In the specific embodiment shown, a third pressure gauge 53 is provided on the raw gas channel 5 to monitor the pressure in the raw gas channel 5 .

[0116] In a Figure 2 and Figure 3 In the specific embodiment shown, the air inlet ends of the raw gas channel 5 are independently connected to a carbon dioxide air inlet system 10 and a hydrogen air inlet system 11 , so as to transport carbon dioxide and hydrogen to the raw gas channel 5 .

[0117] In a Figure 2 and Figure 3 In the specific embodiment shown, the carbon dioxide intake system 10 includes a carbon dioxide gas source and a carbon dioxide intake section pipeline, and the carbon dioxide intake section pipeline is used to connect the carbon dioxide gas source and the intake end of the raw gas channel 5 to transport carbon dioxide to the raw gas channel 5.

[0118] In a Figure 2In the specific embodiment shown, one or more of a first filter 102 , a first switch valve 103 , a first pressure gauge 104 , a first flow meter 105 and a first check valve 106 are provided on the carbon dioxide intake pipeline.

[0119] In a Figure 2 In the specific embodiment shown, the hydrogen intake system 11 includes a hydrogen gas source and a hydrogen gas intake end pipeline, and the hydrogen gas intake section pipeline is used to connect the hydrogen gas source and the intake end of the raw gas channel 5 to transport hydrogen to the raw gas channel 5.

[0120] In a Figure 2 In the specific embodiment shown, one or more of a second filter 112 , a second switch valve 113 , a second pressure gauge 114 , a second flow meter 115 and a second check valve 116 are provided on the hydrogen intake pipeline.

[0121] In the present invention, the filters on the carbon dioxide inlet section pipeline and the hydrogen inlet end pipeline are used to filter the raw gas to remove impurities, the switch valve and the flow meter are used to regulate and monitor the amount of gas introduced, the pressure gauge is used to monitor the pressure in the pipeline, and the check valve is used to prevent gas backflow.

[0122] The working principle of preparing methanol using the carbon dioxide hydrogenation to methanol reaction system of the present invention is: carbon dioxide and hydrogen enter the reactor after being pressurized and heated, and methanol is synthesized under the action of the catalyst, and the reaction equation is: CO2+3H2→CH3OH+H2O.

[0123] The specific reaction system used in the following examples of this application is as follows Figure 2 As shown, the process of producing methanol by hydrogenation of carbon dioxide based on this specific reaction system is described as follows:

[0124] When in use, first, carbon dioxide and hydrogen are transported to the raw gas channel 5 through the carbon dioxide intake system 10 and the hydrogen intake system 11, and the carbon dioxide and hydrogen are pressurized and compressed by the gas compressor 51 on the raw gas channel 5. After the pressure is pressurized to 60-80 bar, the carbon dioxide and hydrogen enter the raw material mixing tank 4 to be fully mixed; the mixed carbon dioxide and hydrogen are transported to the pipe layer of the heat exchanger 3 through the raw mixed gas channel 6, and the mixed gas of carbon dioxide and hydrogen is preheated with the product gas to 180-190°C. The preheated carbon dioxide and hydrogen mixture is transported to the shell 12 of the reactor through the heating gas feed channel 7; the carbon dioxide and hydrogen mixture is further heated to 180-220° C. by the reaction heat generated in the reaction tubes 11 in the shell side, and then enters the reaction tubes 11 through the shell bypass pipeline 2 for reaction; the product after the reaction enters the shell layer of the heat exchanger 3 through the product heat recovery channel 8 to heat the carbon dioxide and hydrogen mixture in the tube layer of the heat exchanger 3, and the product after heat recovery is subsequently condensed and collected through the product outlet channel 9 to obtain methanol.

[0125] The present application preheats the mixture of carbon dioxide and hydrogen in the heat exchanger 3 for the first time by using the product gas flow, thereby increasing the temperature of the reaction raw gas and lowering the temperature of the product itself, reducing energy loss and reducing costs.

[0126] The present application performs a second preheating of the mixture of carbon dioxide and hydrogen entering the shell 12 by utilizing the heat released by the catalytic reaction in the reaction tubes 11, thereby further increasing the temperature of the reaction raw gas to a suitable temperature for the catalytic reaction; in addition, the heat generated in the reaction tubes 11 can be effectively removed through the second preheating, thereby avoiding the occurrence of side reactions due to excessively high reaction temperatures, and maintaining the temperature in the reaction tubes 11 within a suitable range.

[0127] The carbon dioxide hydrogenation to methanol reaction system of the present application requires an external heat source to heat the heat exchanger 3 at the initial stage of the reaction. The heat source can be removed after the reaction is stabilized, and the raw gas can be heated by the heat released by the product and the reaction without the need for an external heat source. In addition, the reaction heat can be effectively removed by heating the gas in the shell 12 using the reaction heat continuously generated in the reaction tubes 11, so no external heat removal device is required. Compared with the prior art, it can effectively reduce energy consumption, ensure that the reaction temperature is within an appropriate range, improve the conversion rate of carbon dioxide and the yield of methanol, and save equipment loss.

[0128] The reaction system and method for producing methanol by hydrogenation of carbon dioxide of the present invention are illustrated below by specific examples and comparative examples. The catalysts used in the following examples and comparative examples are all Cu-Zn-Al2O3, and the calculation formula of methanol yield in the following examples and comparative examples is: The calculation formula for carbon dioxide conversion rate is:

[0129]

[0130] Example 1

[0131] With an annual production of 1,000 tons of methanol as the goal, the carbon dioxide hydrogenation methanol production reaction system and method of the present invention are used to synthesize methanol from carbon dioxide hydrogenation, and tail gas recycling is not considered for the time being. The feed amount and reaction conditions of this embodiment 1 are shown in Table 1.

[0132] The specific structure and parameters of the specific carbon dioxide hydrogenation to methanol reaction system are as follows: the number of shell-side tubes in the reactor is 121, the shell-side diameter is 0.5m, the tube length is 2m, the tube diameter is 2cm, the catalyst particles are evenly distributed in the tube, the catalyst particles have a diameter of 2mm, a height of 4mm, a mass of 44.5kg, and a porosity of 0.41; according to the above-mentioned shell-side structure, a subroutine is established to calculate the shell-side heat transfer coefficient. The specific calculation of the heat transfer coefficient can refer to reference 1 (Iordanidis AA. Mathematical Modeling of Catalytic Fixed Bed Reactors. Ph.D. thesis, University of Twente, Enschede, The Netherlands. 2002.5) and reference 2 (McAdams WH. Heat Transmission. New York: McGraw-Hill, 3rd ed. 1954.).

[0133] Comparative Example 1

[0134] With an annual production of 1,000 tons of methanol as the goal, this comparative example 1 uses a traditional boiling water heat removal reactor. Figure 4 As shown, a water vapor treatment device needs to be provided outside the boiling water heat removal reactor. Figure 4 When the reactor shown is in use, water needs to be added to the steam treatment device. The water in the steam treatment device enters the shell of the reactor, and the reaction heat generated by the catalytic reaction in the reaction tubes is taken away by water evaporation. After the water vapor is discharged, it passes through the steam treatment device again to preheat the reaction gas. The preheated water vapor becomes water and enters the steam treatment device again, thereby performing a heating and heat transfer cycle.

[0135] The feed amount and reaction conditions of this comparative example 1 are specifically shown in Table 1.

[0136] Example 2

[0137] With an annual output of 5,000 tons of methanol as the goal, the carbon dioxide hydrogenation to methanol reaction system and method of the present invention are used to synthesize methanol by carbon dioxide hydrogenation, and the tail gas circulation is not considered for the time being. The feed amount and reaction conditions of this embodiment 2 are shown in Table 2. The specific structure and parameters of the specific carbon dioxide hydrogenation to methanol reaction system are the same as those of embodiment 1.

[0138] Comparative Example 2

[0139] With an annual production of 5,000 tons of methanol as the target, this comparative example adopts Figure 4 The boiling water deheating reactor shown, the feed amount and reaction conditions of this comparative example 2 are shown in Table 2.

[0140] All the above embodiments and comparative examples were simulated using Aspen Plus software to perform material and energy balance calculations for the entire process. The reactor module operating conditions and material balance tables are shown in Tables 1 and 2.

[0141] Table 1 Operating conditions and material balance table of the embodiments and comparative examples for an annual methanol production of 1000 tons

[0142]

[0143]

[0144] It can be seen from the data of Example 1 and Comparative Example 1 that under the same conditions of feed amount and reaction conditions, when the annual output of at least 1000 tons of methanol is the production target, the boiling water heat removal reactor requires a feed temperature of 220°C, while the feed temperature of the reaction system of the present invention can be reduced to 180°C. The boiling water heat removal reactor transfers heat through boiling water, resulting in large temperature changes in the tube side and shell side, which is not conducive to the stable progress of the reaction and easily leads to the occurrence of side reactions. The shell side of the reactor of the reaction system of the present invention does not need to transfer heat through boiling water, but controls the temperature distribution of the tube side by transferring heat in situ by reaction heat, so the temperature fluctuation amplitude in the tube side is small, which is more conducive to the progress of the reaction, so the yield of methanol is higher. The boiling water heat removal reactor has a large degree of heat transfer in the shell side, and it is difficult to control the uniform distribution of the tube side temperature, resulting in the conversion of CO2 into CO, so the proportion of CO converted into methanol increases, thereby affecting the conversion rate of CO2, resulting in a decrease in yield.

[0145] Table 2 Operating conditions and material balance table of the embodiment and comparative example with an annual methanol production of 5000 tons

[0146]

[0147]

[0148] It can be seen from the data of Example 2 and Comparative Example 2 that when the annual output of methanol is increased from 1,000 tons to 5,000 tons, under the condition of increased feed amount, the conventional reactor requires a feed temperature of 226°C, while the feed temperature of the reaction system of the present invention can be 180°C; and the temperature distribution of the tube side and shell side of the reactor in the reaction system of the present invention is relatively uniform, which reduces the occurrence of the side reaction of CO2 to CO conversion, and the conversion rate of carbon dioxide is higher, so the yield of methanol is higher.

[0149] In summary, compared with the traditional boiling water heat removal reactor, the temperature distribution in the reactor tube of the present invention is more uniform, which reduces the loss of equipment due to overheating on the one hand, and reduces the occurrence of side reactions on the other hand, thereby improving the conversion rate of carbon dioxide and the yield of methanol. In addition, the carbon dioxide hydrogenation to methanol reaction system of the present invention does not require an external heat source, and eliminates the need for an additional heat transfer medium. The temperature distribution of the tube is controlled by in-situ heat transfer of the reaction heat, which promotes the sustainable use of energy, reduces the economic cost of equipment and process operation, and has huge economic benefits.

[0150] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the method of the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and evolutions of the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A carbon dioxide hydrogenation to methanol reaction system, characterized in that: The reaction system comprises at least a reactor (1), wherein the reactor (1) comprises a shell (12) having a chamber, a plurality of reaction tubes (11) arranged in the shell (12) for providing a reaction chamber, and a plurality of baffles (13) arranged in the shell (12) for increasing the contact area of ​​the reaction tubes with the heated gas outside. The shell (12) is provided with a raw gas inlet end and a product gas outlet end. A first partitioning inlet plate (16) circumferentially fixed in the shell (12) is provided near the raw gas inlet end. A second partitioning inlet plate (16) circumferentially fixed in the shell (12) is provided near the product gas outlet end. A partitioning gas outlet plate (17); a plurality of spaced gas flow holes are formed on the first partitioning gas inlet plate (16) and the second partitioning gas outlet plate (17), and the two ends of the plurality of reaction tubes (11) are respectively connected to the gas flow holes; one end of the plurality of baffles (13) is fixed to the inner wall of the shell (12) and is located between the first partitioning gas inlet plate (16) and the second partitioning gas outlet plate (17); a heating gas inlet end and a heating gas outlet end are formed on the side wall of the shell (12), and the plurality of baffles (13) are arranged between the heating gas inlet end and the heating gas outlet end.

2. The reaction system according to claim 1, characterized in that: The reaction system further comprises a shell bypass pipe (2) connected to the heating gas outlet and the raw gas inlet so as to allow the heating gas to enter the reaction chamber to participate in the reaction; and / or, each of the baffles (13) extends radially inward from the inner wall of the shell to a portion of the reaction tubes penetrating therethrough to limit the flow direction of the heating gas; and / or, the baffles (13) are multiple and are arranged parallel to each other to form a continuous S-shaped airflow channel; and / or, the length-to-diameter ratio of the reactor (1) is 4-5; and / or, at least one temperature indicator is provided on the housing (12); and / or, at least one pressure indicator is provided on the housing (12); And / or, the reaction system further comprises a heat exchanger (3) for performing heat exchange on the raw gas to heat the raw gas, the heat exchanger (3) comprising a tube bundle for the raw gas to pass through, a shell layer arranged outside the tube bundle, a heat source chamber for the heat source gas to pass through is formed between the shell layer and the tube bundle; the shell layer forms a heat source gas outlet end; the product gas outlet end is connected to the heat source chamber through a product heat recovery channel (8) to utilize the heat of the product gas to heat the raw gas; the raw gas outlet end of the tube bundle is connected to the heating gas inlet end of the reactor through a heating gas feed channel (7).

3. The reaction system according to claim 2, characterized in that: The baffle (13) is a 20-25% area truncated baffle; and / or, a temperature indicator is provided on the shell bypass pipeline (2); and / or, a pressure indicator is provided on the shell bypass pipeline (2); and / or, the reaction system further comprises a raw gas mixing tank (4), the gas outlet end of the raw gas mixing tank (4) is connected to the raw gas inlet end of the tube bundle through a raw mixed gas channel (6); and / or, a pressure indicator is provided on the heating gas feed channel (7); and / or, a pressure indicator is provided on the heating gas feed channel (7); A temperature indicator is provided; and / or, a switch valve is provided on the heating gas feed channel (7); and / or, a pressure indicator is provided on the product heat recovery channel (8); and / or, a temperature indicator is provided on the product heat recovery channel (8); and / or, a switch valve is provided on the product heat recovery channel (8); and / or, the reaction system also includes a condenser for condensing the heat source gas and a product condensate collection channel (9), and the feed end of the condenser and the heat source gas discharge end are connected through the product condensate collection channel (9).

4. The reaction system according to claim 3, characterized in that: The reaction system further comprises a raw gas channel (5), one end of which is connected to the gas inlet end of the raw material mixing tank (4); and / or, a pressure gauge is provided on the raw mixed gas channel (6); and / or, a switch valve is provided on the raw mixed gas channel (6); and / or, a temperature indicator is provided on the raw mixed gas channel (6); and / or, a switch valve is provided on the product condensate collection channel (9).

5. The reaction system according to claim 4, characterized in that: The raw gas channel (5) is provided with a gas compressor; And / or, a switch valve is provided on the raw gas channel (5); and / or, a pressure gauge is provided on the raw gas channel (5); and / or, the air inlet end of the raw gas channel (5) is independently connected to a carbon dioxide air inlet system (10) and a hydrogen air inlet system (11).

6. The reaction system according to claim 5, characterized in that: The carbon dioxide intake system (10) comprises a carbon dioxide gas source and a carbon dioxide intake section pipeline, wherein the carbon dioxide intake section pipeline is used to connect the carbon dioxide gas source and the intake end of the raw gas channel (5); the carbon dioxide intake section pipeline is provided with one or more of a first filter, a first switch valve, a first pressure gauge, a first flow meter and a first check valve; the hydrogen intake system (11) comprises a hydrogen gas source and a hydrogen intake end pipeline, wherein the hydrogen intake section pipeline is used to connect the hydrogen gas source and the intake end of the raw gas channel (5); the hydrogen intake section pipeline is provided with one or more of a second filter, a second switch valve, a second pressure gauge, a second flow meter and a second check valve.

7. A method for preparing methanol by hydrogenating carbon dioxide, characterized in that: The method is carried out by the reaction system for producing methanol by hydrogenation of carbon dioxide according to any one of claims 1 to 6, and comprises: a mixed gas of carbon dioxide and hydrogen is preheated and then enters a reactor, reacts under the action of a catalyst, and obtains a reaction product.

8. The method according to claim 7, characterized in that The molar ratio of the carbon dioxide to hydrogen inlet is 1: (1-5); and / or, the reaction pressure is 60-80 bar; and / or, the pressure drop in the reaction tube is 0.6-0.7 bar; And / or, the catalyst is a copper-based catalyst; and / or, the reaction temperature is 180-280°C.

9. The method according to claim 7, characterized in that: After the first preheating in the heat exchanger, the raw gas enters the shell of the reactor through the heating gas feed channel (7), and then enters the reaction tube (11) through the shell bypass pipeline (2) to react and form product gas; the product gas passes through the product heat recovery channel (8) to the heat source chamber of the heat exchanger (3) and then cools; the temperature of the mixed gas of carbon dioxide and hydrogen after passing through the heat exchanger (3) is 180-190°C; and / or the catalyst is selected from one or more of Cu-Zn-Al2O3, Cu-ZnO-Al2O3, Cu-ZnO-ZrO2.

10. The method according to claim 7, characterized in that The residence time of the carbon dioxide and hydrogen in the catalyst is 0.5 to 5 s; and / or, the feed flow rate of the carbon dioxide is 1000 to 10000 kg / h; and / or, the feed flow rate of the hydrogen is 100 to 1000 kg / h.

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