Zero-carbon-emission system for preparing methanol through hydrogenation of carbon dioxide

Abstract

The utility model relates to a zero-carbon-emission system for preparing methanol through hydrogenation of carbon dioxide. The system comprises a heating furnace system, a methanol synthesis system, a pre-rectifying tower system, a pressurized rectifying tower system, a normal-pressure rectifying tower system and a carbon recovery system, raw material gas is connected with the heating furnace system through the compressor, a flue gas side outlet of the heating furnace system is connected with the carbon recovery system, a process gas side outlet of the heating furnace is connected with the methanol synthesis system, and then the outlet end of the methanol synthesis system is sequentially connected with the pre-rectifying tower system, the pressurized rectifying tower system and the normal-pressure rectifying tower system. In the system, a heating furnace is introduced, purge gas, flash steam, non-condensable gas at the top of a pre-tower and the like are used as fuels, a high temperature required by inverse transformation is provided, waste heat is fully utilized, and a methanol synthesis heat insulation section mainly based on inverse transformation and a methanol synthesis isothermal section mainly based on methanol synthesis are compounded into a methanol synthesis tower; and the process and equipment occupied area are simplified.

Description

Technical Field

[0001] The utility model relates to the technical field of preparing methanol by hydrogenation of carbon dioxide, in particular to a zero-carbon emission carbon dioxide hydrogenation system for preparing methanol. Background Art

[0002] The raw materials for the carbon dioxide hydrogenation to methanol reaction are carbon dioxide and hydrogen. There is a reverse reaction of the conversion reaction during the reaction process. The reaction formula is as follows:

[0003] CO 2 +H 2 →CO+H 2 O△H=-41.2kJ / mol

[0004] The final reaction is CO and CO 2 The main reaction formula of the process of producing methanol under the action of catalyst is as follows:

[0005] CO+2H 2 →CH 3 OH△H=90.73kJ / mol

[0006] CO 2 +3H 2 →CH 3 OH+H 2 O△H=48.02kJ / mol

[0007] The reverse reaction of the shift reaction is an endothermic reaction, and high temperature is conducive to the reaction proceeding to the right. Methanol synthesis is an exothermic reaction, and low temperature is conducive to the reaction proceeding to the right. Therefore, methanol synthesis is generally carried out in the range of 200-260°C, and the reverse reaction of the shift reaction is not deep at this time; when the temperature is raised to above 300°C, or even above 350°C, the methanol synthesis reaction becomes less, and a large amount of carbon dioxide is converted into carbon monoxide through reverse transformation. The heat release of synthesizing methanol from the same mole of carbon monoxide and carbon dioxide is nearly doubled, and the reaction rate of synthesizing methanol from carbon monoxide is much faster. Synthesizing methanol from carbon monoxide is more conducive to the comprehensive utilization of reaction rate and heat.

[0008] Patent CN107285995A proposes a method for preparing methanol using carbon dioxide and hydrogen. Methanol is prepared indirectly by reverse water gas shift reaction + methanol synthesis reaction. A multi-stage adiabatic fixed bed reactor is used in the reverse water gas shift reaction unit to convert carbon dioxide into carbon monoxide at high temperature, thereby increasing the carbon monoxide content entering the methanol synthesis unit, and improving the carbon dioxide conversion rate and methanol yield. However, this method requires the introduction of external heat and the addition of multi-stage adiabatic reactors to achieve reverse conversion.

[0009] Patent CN101386564B proposes a process for synthesizing methanol from hydrogen and carbon dioxide. The method of synthesizing methanol by setting up a two-stage reactor can improve the methanol conversion rate. However, due to the reaction balance of carbon dioxide, the conversion rate and reaction speed are low, and the synthesis and distillation heat are difficult to couple.

[0010] Patents CN218452168U, CN216550214U and other patents all propose two or more stages of methanol synthesis reaction, which can achieve a higher conversion rate, but there are problems such as carbon emissions from the purge gas.

[0011] Based on existing patents and technologies, the current process of synthesizing methanol from carbon dioxide hydrogenation has the following problems:

[0012] (1) In the existing process, the purge gas, flash gas, and non-condensable gas at the top of the pre-tower are discharged to the flare system, which still generates carbon emissions.

[0013] (2) The direct hydrogenation of carbon dioxide to methanol has low heat of reaction, large circulation ratio, and is difficult to couple with distillation. Even if low-level heat is used for coupling, the area of ​​the reboiler needs to be designed to be very large.

[0014] (3) For methanol synthesis processes with two or more stages, the methanol tower occupies a relatively large area. Utility Model Content

[0015] The purpose of the utility model is to provide a zero-carbon emission carbon dioxide hydrogenation methanol system. This is a new system designed for the characteristics of carbon dioxide hydrogenation methanol device, such as low reaction heat, large circulation ratio, and difficulty in thermal coupling with distillation; carbon emission still exists in the purge gas, flash gas, and non-condensable gas at the top of the pre-tower; and the methanol tower of the two-stage and above methanol synthesis system occupies a relatively large area.

[0016] In this system, the high temperature required for reverse conversion is provided by introducing a heating furnace to use the purge gas, flash steam, and non-condensable gas at the top of the pre-tower as fuel. After the reverse conversion, the temperature of the methanol synthesis gas is still very high, which can meet the heat required by the reboiler of the pressurized distillation tower, and the temperature difference of the shell and tube is ≥20°C, which is a high-quality waste heat. By absorbing the carbon dioxide generated by the combustion of the purge gas, flash steam, and non-condensable gas at the top of the pre-tower, it is analyzed and pressurized and supplemented into the system as carbon dioxide to achieve zero carbon emission. The adiabatic section of methanol synthesis based on reverse conversion and the isothermal section of methanol synthesis based on methanol synthesis are combined into a methanol synthesis tower to simplify the process and equipment footprint.

[0017] The purpose of the utility model is achieved through the following technical solutions:

[0018] A zero-carbon emission carbon dioxide hydrogenation methanol system, the system comprising a heating furnace system, a methanol synthesis system, a pre-distillation tower system, a pressurized distillation tower system, an atmospheric distillation tower system and a carbon recovery system; wherein the feed gas is connected to the heating furnace system via a compressor, the flue gas side outlet of the heating furnace system is connected to the carbon recovery system, the process gas side outlet of the heating furnace is connected to the methanol synthesis system, and then the outlet end of the methanol synthesis system is sequentially connected to the pre-distillation tower system, the pressurized distillation tower system and the atmospheric distillation tower system.

[0019] Furthermore, the heating furnace system includes a raw gas compressor, an air-to-air heat exchanger and a heating furnace; the raw gas is connected to the heating furnace via the raw gas compressor and the air-to-air heat exchanger.

[0020] Furthermore, the methanol synthesis system includes a methanol synthesis tower, a pressure tower waste heat reboiler, a decomposition tower reboiler, a primary high-efficiency separator, an inlet heater, a carbon dioxide heater, a cooler, a secondary high-efficiency separator, a flash tank, a flue gas heat exchanger and a circulating gas compressor; wherein the gas-to-gas heat exchanger and the heating furnace are both connected to the methanol synthesis tower; the outlet end of the adiabatic section of the methanol synthesis tower is connected to the pressure tower waste heat reboiler, the decomposition tower reboiler and the primary high-efficiency separator in sequence; and the gas phase of the primary high-efficiency separator is connected to the isothermal section in the methanol synthesis tower through the inlet heater, and the liquid phase is connected to the flash tank; the outlet of the isothermal section of the methanol synthesis tower is then connected to the gas-to-gas heat exchanger, the carbon dioxide heater, the cooler and the secondary high-efficiency separator in sequence; the gas phase of the secondary high-efficiency separator is connected to the inlet of the circulating gas compressor and then enters the gas-to-gas heat exchanger, and the liquid phase is connected to the flash tank; the liquid outlet of the flash tank is connected to the flue gas heat exchanger.

[0021] Furthermore, the pre-distillation tower system includes a pre-distillation tower, a pre-distillation tower cooler and a pre-distillation tower reboiler; the flue gas heat exchanger is connected to the pre-distillation tower, and the pre-distillation tower is equipped with a pre-distillation tower cooler and a pre-distillation tower reboiler.

[0022] Furthermore, the pressurized distillation tower system is a pressurized distillation tower, and the liquid outlet of the kettle of the pre-distillation tower is connected to the pressurized distillation tower.

[0023] Furthermore, the atmospheric distillation tower system includes an atmospheric distillation tower reboiler, an atmospheric distillation tower, an atmospheric distillation tower cooler and a wastewater pump; wherein, the top gas phase of the pressurized distillation tower is connected to the atmospheric distillation tower reboiler, and the liquid outlet of the pressurized distillation tower kettle is connected to the atmospheric distillation tower; the atmospheric distillation tower cooler is arranged at the upper end of the atmospheric distillation tower, and the atmospheric distillation tower reboiler and the wastewater pump are respectively arranged at the lower end.

[0024] Furthermore, the carbon recovery system includes an absorption tower, a decomposition tower, a decomposition tower steam reboiler and a carbon dioxide compressor; wherein the flue gas heat exchanger is connected to the absorption tower, and the absorption tower is connected to the decomposition tower; the decomposition tower is provided with a decomposition tower steam reboiler; the top gas phase port of the decomposition tower is connected to the inlet of the carbon dioxide compressor, and the outlet of the carbon dioxide compressor is connected to the carbon dioxide heater, and then enters the raw material compressor outlet pipeline.

[0025] Furthermore, the compressor outlet gas, the circulating gas compressor outlet gas and the carbon dioxide compressor outlet gas heated by the carbon dioxide heater are mixed; and the outlet end of the mixed gas is connected to the gas-to-gas heat exchanger.

[0026] Furthermore, the gas phase outlet ends of the secondary high-efficiency separator, flash tank and pre-distillation tower cooler are all connected to the combustion side of the heating furnace; the combustion flue gas outlet end of the heating furnace is connected to the flue gas heat exchanger and the absorption tower in turn.

[0027] Furthermore, the heat source of the atmospheric distillation tower comes from the steam at the top of the pressurized distillation tower, and the waste heat at the outlet of the adiabatic section of the methanol synthesis tower provides heat sources for the pressurized tower and the decomposition tower respectively; the heat source of the pre-distillation tower comes from the condensed water of the system steam.

[0028] Preferably, the outlet temperature of the carbon dioxide and hydrogen mixed gas of the heating furnace (3) is ≥321°C.

[0029] Preferably, the outlet temperature of the adiabatic section of the methanol synthesis tower (4) is ≥290°C.

[0030] Compared with the prior art, the utility model has the following beneficial effects:

[0031] (i) A heating furnace is introduced into the system, which can use the purge gas, flash gas, non-condensable gas at the top of the pre-tower, etc. as fuel to provide the high temperature required for the reverse conversion.

[0032] (ii) After the reverse transformation, the temperature of the methanol synthesis gas is still very high, which can meet the heat required by the reboiler of the pressurized distillation tower, and the temperature difference between the shell and tube is ≥20℃, which is a high-quality waste heat. The waste heat is used for recycling treatment, making full use of the heat.

[0033] (III) The carbon dioxide produced by the combustion of purge gas, flash gas, non-condensable gas at the top of the pre-tower, etc. is absorbed by the absorption tower, and after analysis and pressurization, it is added to the system as carbon dioxide to achieve zero carbon emission.

[0034] (iv) The adiabatic section of methanol synthesis mainly based on reverse transformation and the isothermal section of methanol synthesis mainly based on methanol synthesis are combined into a methanol synthesis tower to simplify the process and equipment footprint. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1This is a schematic diagram of the connection relationship of a zero-carbon emission carbon dioxide hydrogenation to methanol process described in Example 1 of the utility model.

[0036] Reference numerals:

[0037] 1- Raw gas compressor, 2- Gas-to-gas heat exchanger, 3- Heating furnace, 4- Methanol synthesis tower,

[0038] 5-pressure tower waste heat reboiler, 6-analysis tower reboiler, 7-first-stage high-efficiency separator,

[0039] 8- inlet heater, 9- carbon dioxide heater, 10- cooler,

[0040] 11-secondary high-efficiency separator, 12-flash tank, 13-flue gas heat exchanger, 14-circulation compressor,

[0041] 15-pre-distillation tower, 16-pre-distillation tower cooler, 17-pre-distillation tower reboiler,

[0042] 18-pressure distillation tower, 19-atmospheric distillation tower reboiler, 20-atmospheric distillation tower,

[0043] 21- atmospheric distillation tower cooler, 22- wastewater pump, 23- absorption tower,

[0044] 24-analysis tower, 25-analysis tower steam reboiler, 26-carbon dioxide compressor. DETAILED DESCRIPTION

[0045] A zero-carbon emission carbon dioxide hydrogenation methanol system, the system comprising a heating furnace system (raw gas compressor 1, gas-to-gas heat exchanger 2, heating furnace 3), a methanol synthesis system (methanol synthesis tower 4, pressure tower waste heat reboiler 5, analysis tower reboiler 6, primary high-efficiency separator 7, inlet heater 8, carbon dioxide heater 9, cooler 10, secondary high-efficiency separator 11, flash tank 12, flue gas heat exchanger 13, circulation compressor 14), a pre-distillation tower system (pre-distillation tower 15, pre-distillation tower cooler 16, pre-distillation tower reboiler 17), a pressurized distillation tower system (pressurized distillation tower 18), an atmospheric distillation tower system (atmospheric distillation tower reboiler 19, atmospheric distillation tower 20, atmospheric distillation tower cooler 21, wastewater pump 22), and a carbon recovery system (absorption tower 23, analysis tower 24, analysis tower steam reboiler 25, carbon dioxide compressor 26).

[0046] The raw gas inlet device is connected to the heating furnace system, and the flue gas side outlet of the heating furnace system is connected to the carbon recovery system, the process gas side outlet of the heating furnace is connected to the methanol synthesis system, and then the outlet end of the methanol synthesis system is connected to the pre-distillation tower system, the pressure distillation tower system, and the atmospheric distillation tower system in sequence.

[0047] The raw mixed gas of carbon dioxide and hydrogen is compressed by the raw gas compressor 1 and then mixed with the outlet gas of the circulating gas compressor 14 and the outlet gas of the carbon dioxide compressor 26. The outlet end of the mixed gas is connected to the gas-to-gas heat exchanger 2, the heating furnace 3 and the methanol synthesis tower 4 in sequence.

[0048] The outlet end of the adiabatic section of the methanol synthesis tower 4 is connected to the pressure tower waste heat reboiler 5, the analytical tower reboiler 6, and the primary high-efficiency separator 7 in sequence, and the gas phase of the primary high-efficiency separator 7 is connected to the isothermal section of the methanol synthesis tower 4, and the liquid phase is connected to the flash tank 12. Then the outlet of the isothermal section of the methanol synthesis tower 4 is connected to the gas-to-gas heat exchanger 2, the carbon dioxide heater 9, the cooler 10, and the secondary high-efficiency separator 11 in sequence. After that, the gas phase of the secondary high-efficiency separator 11 is connected to the inlet of the circulating gas compressor 14, and the liquid phase is connected to the flash tank 12. Finally, the liquid outlet of the flash tank 12 is connected to the flue gas heat exchanger 13 and the pre-distillation tower 15 in sequence.

[0049] The pre-distillation tower 15 is adapted to be equipped with a pre-distillation tower cooler 16 and a pre-distillation tower reboiler 17, and the liquid outlet of the tower bottom of the pre-distillation tower 15 is connected to the pressure distillation tower 18. The pressure distillation tower 18 is adapted to be equipped with a pressure tower waste heat reboiler 5, the top gas phase of the pressure distillation tower 18 is connected to the atmospheric distillation tower reboiler 19, and the liquid outlet of the tower bottom of the pressure distillation tower is connected to the atmospheric distillation tower 20. The atmospheric distillation tower 20 is adapted to be equipped with an atmospheric distillation tower cooler 21, an atmospheric distillation tower reboiler 19, and a wastewater pump 22.

[0050] The heat source of the atmospheric distillation tower 20 comes from the top steam of the pressure distillation tower 18, and the waste heat at the outlet of the adiabatic section of the methanol synthesis tower 4 provides heat sources for the pressure tower 18 and the decomposition tower 24 in turn; the heat source of the pre-distillation tower 15 comes from the system steam condensate.

[0051] The gas phase outlet ends of the pre-distillation tower 15, the flash tank 12, and the secondary high-efficiency separator 11 are connected to the combustion side of the heating furnace 3, and the combustion flue gas outlet end is connected to the flue gas heat exchanger 13, the absorption tower 23, and the decomposition tower 24 in sequence. The decomposition tower 24 is equipped with a decomposition tower reboiler 6 and a decomposition tower steam reboiler 25. The gas phase port at the top of the decomposition tower 24 is connected to the inlet of the carbon dioxide compressor 26, and the outlet of the carbon dioxide compressor 26 is connected to the carbon dioxide heater 9, and then enters the outlet pipeline of the raw material compressor 1.

[0052] The outlet temperature of the carbon dioxide and hydrogen mixed gas of the heating furnace 3 is ≥321°C.

[0053] The outlet temperature of the adiabatic section of the methanol synthesis tower 4 is ≥290°C.

[0054] In order to make the invention purpose, technical solution and advantages of the utility model clearer, the technical solution in the embodiment of the present application will be clearly and completely described below in conjunction with the accompanying drawings. The orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the application product is usually placed when in use, or is the orientation or position relationship commonly understood by those skilled in the art. The terms "set", "open", "installed", "connected" and "connected" should be understood in a broad sense.

[0055] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In addition, the embodiments and features in the embodiments of this application can be combined with each other without conflict.

[0056] Example 1

[0057] A zero-carbon emission carbon dioxide hydrogenation methanol system, the system comprising a heating furnace system, a methanol synthesis system, a pre-distillation tower system, a pressurized distillation tower system, an atmospheric distillation tower system and a carbon recovery system; wherein the feed gas is connected to the heating furnace system via a compressor, the flue gas side outlet of the heating furnace system is connected to the carbon recovery system, the process gas side outlet of the heating furnace is connected to the methanol synthesis system, and then the outlet end of the methanol synthesis system is sequentially connected to the pre-distillation tower system, the pressurized distillation tower system and the atmospheric distillation tower system.

[0058] The heating furnace system comprises a raw gas compressor 1 , an air-to-air heat exchanger 2 and a heating furnace 3 ; the raw gas is connected to the heating furnace 3 via the raw gas compressor 1 and the air-to-air heat exchanger 2 .

[0059] The methanol synthesis system comprises a methanol synthesis tower 4, a pressurizing tower waste heat reboiler 5, a decomposing tower reboiler 6, a primary high-efficiency separator 7, an inlet heater 8, a carbon dioxide heater 9, a cooler 10, a pre-distillation tower 11, a vacuum distillation tower 12, a flue gas heat exchanger 13 and a circulating gas compressor 14; wherein the gas-to-gas heat exchanger 2 and the heating furnace 3 are both connected to the methanol synthesis tower 4; the outlet end of the adiabatic section of the methanol synthesis tower 4 is connected to the pressurizing tower waste heat reboiler 5, the decomposing tower reboiler 6, the primary high-efficiency separator 7 in sequence connected; the gas phase of the primary high-efficiency separator 7 is connected to the isothermal section in the methanol synthesis tower 4 through the inlet heater 8, and the liquid phase is connected to the flash tank 12; the outlet of the isothermal section of the methanol synthesis tower 4 is then connected to the gas-to-gas heat exchanger 2, the carbon dioxide heater 9, the secondary cooler 10, and the secondary high-efficiency separator 11 in sequence; the gas phase of the secondary high-efficiency separator 11 is connected to the inlet of the circulating gas compressor 14 and then enters the gas-to-gas heat exchanger 2, and the liquid phase is connected to the flash tank 12; the liquid outlet of the flash tank 12 is connected to the flue gas heat exchanger 13.

[0060] The pre-distillation tower system comprises a pre-distillation tower 15, a pre-distillation tower cooler 16 and a pre-distillation tower reboiler 17; the flue gas heat exchanger 13 is connected to the pre-distillation tower 15, and the pre-distillation tower 15 is adapted to be provided with the pre-distillation tower cooler 16 and the pre-distillation tower reboiler 17.

[0061] The pressurized distillation tower system is a pressurized distillation tower 18 , and the liquid outlet of the kettle of the pre-distillation tower 15 is connected to the pressurized distillation tower 18 .

[0062] The atmospheric distillation tower system includes an atmospheric distillation tower reboiler 19, an atmospheric distillation tower 20, an atmospheric distillation tower cooler 21 and a wastewater pump 22; wherein, the top gas phase of the pressurized distillation tower 18 is connected to the atmospheric distillation tower reboiler 19, and the liquid outlet of the bottom of the pressurized distillation tower 18 is connected to the atmospheric distillation tower 20; an atmospheric distillation tower cooler 21 is arranged at the upper end of the atmospheric distillation tower 20, and an atmospheric distillation tower reboiler 19 and a wastewater pump 22 are respectively arranged at the lower end.

[0063] The carbon recovery system includes an absorption tower 23, a decomposition tower 24, a decomposition tower steam reboiler 25 and a carbon dioxide compressor 26; wherein the flue gas heat exchanger 13 is connected to the absorption tower 23, and the absorption tower 23 is connected to the decomposition tower 24; a decomposition tower steam reboiler 25 is arranged on the decomposition tower 24; the top gas phase port of the decomposition tower 24 is connected to the inlet of the carbon dioxide compressor 26, and the outlet of the carbon dioxide compressor 26 is connected to the carbon dioxide heater 9, and then enters the outlet pipeline of the raw material compressor 1.

[0064] The outlet gas of the compressor 1 , the outlet gas of the circulating gas compressor 14 and the outlet gas of the carbon dioxide compressor 26 are mixed after being heated by the carbon dioxide heater 9 ; the outlet end of the mixed gas is connected to the gas-to-gas heat exchanger 2 .

[0065] The gas phase outlet ends of the secondary high-efficiency separator 11, the flash tank 12 and the pre-distillation tower cooler 16 are all connected to the combustion side of the heating furnace 3; the combustion flue gas outlet end of the heating furnace 3 is connected to the flue gas heat exchanger 13 and the absorption tower 23 in turn.

[0066] The heat source of the atmospheric distillation tower 20 comes from the top steam of the pressure distillation tower 18, and the waste heat at the outlet of the adiabatic section of the methanol synthesis tower 4 provides heat sources for the pressure tower 18 and the decomposition tower 24 respectively; the heat source of the pre-distillation tower 15 comes from the condensed water of the system steam.

[0067] The carbon dioxide hydrogenation to methanol process is carried out using the zero-carbon emission carbon dioxide hydrogenation to methanol system described above. Taking 100,000 tons / year of methanol production as an example, the parameters are as follows:

[0068] 1) Carbon dioxide 18225.8 kg / h, temperature 40°C, pressure 0.15 MPa, mass composition: 99% carbon dioxide, 1% nitrogen; raw hydrogen 2679.9 kg / h, temperature 40°C, pressure 0.15 MPa, mass composition: 92.6% hydrogen, 7.4% methane.

[0069] 2) The final amount of refined alcohol is 12543.05 kg / h, and the mass composition is: 99.99% methanol, 0.01% water.

[0070] 3) The inlet of the adiabatic section of the methanol synthesis tower is 335°C, and the outlet of the adiabatic section is 298°C.

[0071] 4) The operating parameters of the distillation tower are as follows:

[0072] parameter Pre-distillation tower Pressurized distillation tower Atmospheric distillation tower Tower top temperature ℃ 45 104 90 Tower temperature ℃ 80 118 127 Operating pressure MPaG 0.03 0.3 0.1

[0073] 5) The condenser of the pressure distillation tower can provide 9.2715Gcal of heat, and the reboiler of the atmospheric distillation tower requires 8.8132Gcal of heat, which can form heat coupling.

[0074] 6) The outlet temperature of the combustion furnace is 345°C, and the outlet temperature of the adiabatic section of the methanol synthesis tower is 302°C. Therefore, the high-temperature waste heat of the methanol synthesis tower is 9.9115 Gcal, and the heat required by the pressurized distillation tower is 9.8884 Gcal, which can meet the required heat.

[0075] Comparative Example 1:

[0076] The same process parameters as in Example 1 are used to compare the conventional two-tower methanol synthesis in patent CN 101386564 A with the carbon dioxide hydrogenation to methanol synthesis system of the utility model. The conversion rate and carbon emission results are shown in the following table:

[0077] The utility model Traditional two towers Carbon dioxide one-way conversion rate 0.8578 0.8033 Total CO2 conversion 0.9945 0.9933 Remove flare exhaust 192.135 kmol 192.135 kmol Carbon emissions in tail gas 0 58.4969 kmol

[0078] It can be seen from the above table that the utility model can increase the carbon dioxide one-way conversion rate by 6.3% and reduce carbon emissions by 4.7%.

[0079] The utility model introduces a heating furnace and uses the purge gas, flash steam, non-condensable gas at the top of the pre-tower as fuel to provide the high temperature required for the reverse conversion. After the reverse conversion, the temperature of the methanol synthesis gas is still very high, which can meet the heat required by the reboiler of the pressurized distillation tower, and the temperature difference of the shell and tube is ≥20°C, which is a high-quality waste heat. The carbon dioxide generated by the combustion of the purge gas, flash steam, non-condensable gas at the top of the pre-tower is absorbed and pressurized, and then added to the system as carbon dioxide to achieve zero carbon emission. The adiabatic section of methanol synthesis based on reverse conversion and the isothermal section of methanol synthesis based on methanol synthesis are combined into a methanol synthesis tower to simplify the process and equipment space. The internal heat balance is achieved, the carbon emission is reduced by 5%, and the methanol conversion rate is increased by more than 5%.

[0080] The above is only a preferred embodiment of the utility model and does not impose any form of limitation on the utility model. According to the technical essence of the utility model, within the spirit and principles of the utility model, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the utility model technical solution.

Claims

1. A zero-carbon emission carbon dioxide hydrogenation to methanol system, characterized in that: The system includes a heating furnace system, a methanol synthesis system, a pre-distillation tower system, a pressurized distillation tower system, an atmospheric distillation tower system and a carbon recovery system; wherein the raw gas is connected to the heating furnace system through a compressor, and the flue gas side outlet of the heating furnace system is connected to the carbon recovery system, the process gas side outlet of the heating furnace is connected to the methanol synthesis system, and then the outlet end of the methanol synthesis system is connected to the pre-distillation tower system, the pressurized distillation tower system and the atmospheric distillation tower system in sequence.

2. A zero-carbon emission carbon dioxide hydrogenation to methanol system as claimed in claim 1, characterized in that: The heating furnace system comprises a raw gas compressor (1), an air-to-air heat exchanger (2) and a heating furnace (3); the raw gas is connected to the heating furnace (3) via the raw gas compressor (1) and the air-to-air heat exchanger (2).

3. A zero-carbon emission carbon dioxide hydrogenation to methanol system according to claim 2, characterized in that: The methanol synthesis system comprises a methanol synthesis tower (4), a pressure tower waste heat reboiler (5), a decomposition tower reboiler (6), a primary high-efficiency separator (7), an inlet heater (8), a carbon dioxide heater (9), a cooler (10), a secondary high-efficiency separator (11), a flash tank (12), a flue gas heat exchanger (13) and a circulating gas compressor (14); wherein the gas-to-gas heat exchanger (2) and the heating furnace (3) are both connected to the methanol synthesis tower (4); the outlet end of the adiabatic section of the methanol synthesis tower (4) is connected in sequence to the pressure tower waste heat reboiler (5), the decomposition tower reboiler (6), the primary high-efficiency separator (7), the inlet heater (8), the carbon dioxide heater (9), the cooler (10), the secondary high-efficiency separator (11), the flash tank (12), the flue gas heat exchanger (13) and the circulating gas compressor (14); The gas phase of the primary high-efficiency separator (7) is connected to the isothermal section of the methanol synthesis tower (4) through the inlet heater (8), and the liquid phase is connected to the flash tank (12); the outlet of the isothermal section of the methanol synthesis tower (4) is then connected to the gas-to-gas heat exchanger (2), the carbon dioxide heater (9), the cooler (10), and the secondary high-efficiency separator (11) in sequence; the gas phase of the secondary high-efficiency separator (11) is connected to the inlet of the circulating gas compressor (14) and then enters the gas-to-gas heat exchanger (2), and the liquid phase is connected to the flash tank (12); the liquid outlet of the flash tank (12) is connected to the flue gas heat exchanger (13).

4. A zero-carbon emission carbon dioxide hydrogenation to methanol system as claimed in claim 1 or 3, characterized in that: The pre-distillation tower system comprises a pre-distillation tower (15), a pre-distillation tower cooler (16) and a pre-distillation tower reboiler (17); the flue gas heat exchanger (13) is connected to the pre-distillation tower (15), and the pre-distillation tower cooler (16) and the pre-distillation tower reboiler (17) are adapted to be provided on the pre-distillation tower (15).

5. A zero-carbon emission carbon dioxide hydrogenation to methanol system as claimed in claim 4, characterized in that: The pressurized distillation tower system is a pressurized distillation tower (18), and the liquid outlet of the bottom of the pre-distillation tower (15) is connected to the pressurized distillation tower (18).

6. A zero-carbon emission carbon dioxide hydrogenation to methanol system as claimed in claim 1 or 5, characterized in that: The atmospheric distillation tower system comprises an atmospheric distillation tower reboiler (19), an atmospheric distillation tower (20), an atmospheric distillation tower cooler (21) and a wastewater pump (22); wherein the top gas phase of the pressurized distillation tower (18) is connected to the atmospheric distillation tower reboiler (19), and the bottom liquid outlet of the pressurized distillation tower (18) is connected to the atmospheric distillation tower (20); the atmospheric distillation tower cooler (21) is arranged at the upper end of the atmospheric distillation tower (20), and the atmospheric distillation tower reboiler (19) and the wastewater pump (22) are respectively arranged at the lower end.

7. A zero-carbon emission carbon dioxide hydrogenation to methanol system as claimed in claim 6, characterized in that: The carbon recovery system comprises an absorption tower (23), a desorption tower (24), a desorption tower steam reboiler (25) and a carbon dioxide compressor (26); wherein the flue gas heat exchanger (13) is connected to the absorption tower (23), and the absorption tower (23) is connected to the desorption tower (24); the desorption tower (24) is provided with a desorption tower steam reboiler (25); the top gas phase port of the desorption tower (24) is connected to the inlet of the carbon dioxide compressor (26), and the outlet of the carbon dioxide compressor (26) is connected to the carbon dioxide heater (9), and then enters the outlet pipeline of the raw gas compressor (1).

8. A zero-carbon emission carbon dioxide hydrogenation to methanol system as claimed in claim 7, characterized in that: The outlet gas of the compressor (1), the outlet gas of the circulating gas compressor (14) and the outlet gas of the carbon dioxide compressor (26) are mixed after being heated by the carbon dioxide heater (9); and the outlet end of the mixed gas is connected to the gas-to-gas heat exchanger (2).

9. A zero-carbon emission carbon dioxide hydrogenation to methanol system as claimed in claim 8, characterized in that: The gas phase outlet ends of the secondary high-efficiency separator (11), the flash tank (12) and the pre-distillation tower cooler (16) are all connected to the combustion side of the heating furnace (3); the combustion flue gas outlet end of the heating furnace (3) is connected to the flue gas heat exchanger (13) and the absorption tower (23) in sequence.

10. A zero-carbon emission carbon dioxide hydrogenation to methanol system as claimed in claim 9, characterized in that: The heat source of the atmospheric distillation tower (20) comes from the top steam of the pressure distillation tower (18), and the waste heat at the outlet of the adiabatic section of the methanol synthesis tower (4) provides heat sources for the pressure distillation tower (18) and the desorption tower (24) in turn; the heat source of the pre-distillation tower (15) comes from the condensed water of the system steam.

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