A series-parallel process system for CO2 hydrogenation to methanol

Abstract

The utility model relates to a kind of CO2 hydrogenation methanol's series-parallel process system, belong to chemical production field.It includes first reactor and second reactor, wherein, first reactor includes water-cooled reactor one and water-cooled reactor two, second reactor includes gas-cooled reactor, first reactor and second reactor are connected to form loop A, second reactor forms loop B, loop A and loop B are connected in parallel.The series connection of first reactor and second reactor, so that the balance of methanol synthesis reaction is further moved, higher single-pass conversion rate can be obtained;Synthesis gas is connected in parallel, reduce the operation load of first reactor, also improve the utilization of second reactor catalyst, so that the catalyst of first reactor and second reactor is synchronized aging;At the same time, this series-parallel operation can reduce circulation amount, so that the energy consumption of entire methanol preparation process is low and pipeline size is relatively reduced.

Description

Technical Field

[0001] This utility model relates to the field of chemical production, and in particular to a series-parallel process system for producing methanol by CO2 hydrogenation. Background Technology

[0002] Carbon dioxide is both a greenhouse gas and a cheap and abundant carbon resource. The production of methanol from carbon dioxide is gaining increasing attention as a large-scale utilization method for carbon dioxide. On the one hand, it can reduce greenhouse gas emissions and achieve carbon recycling; on the other hand, it can be combined with new energy sources such as hydrogen electrolysis to achieve hydrogen energy storage, providing a new approach for green methanol production and energy storage, with good economic and social benefits.

[0003] The production of green methanol by hydrogenating carbon dioxide can realize the resource utilization of carbon dioxide, reduce carbon emissions, and help solve or alleviate some contradictions and difficulties in the development of new energy sources. It is an ideal way to utilize liquid sunlight.

[0004] Characteristics of the CO2 hydrogenation to methanol reaction:

[0005] CO2 + 3H2 --- CH3OH + H2O ΔH= -49.51kJ / mol (1)

[0006] CO2 + H2 --- CO + H2O ΔH = 41.19kJ / mol (2)

[0007] CO + 2H2 --- CH3OH ΔH = -90.70kJ / mol (3)

[0008] Reaction (1) is the main reaction for the hydrogenation of CO2 to methanol. This reaction has two characteristics:

[0009] (A) CO2 has a stable structure and high activation energy, requiring high temperature conditions to activate and hydrogenate it to produce methanol;

[0010] (B) The thermodynamic equilibrium conversion rate of CO2 decreases rapidly with increasing temperature. The reaction temperature range with industrial application value is 200-300℃. Above 300℃, the thermodynamic equilibrium conversion rate of CO2 is too low and the cycle energy consumption is too high.

[0011] The typical process for producing methanol by direct hydrogenation of carbon dioxide has drawbacks such as high investment, low carbon dioxide conversion rate, and high power consumption. Therefore, providing a method for producing methanol by direct hydrogenation of carbon dioxide with high single-pass conversion rate, low circulation volume, and energy saving has become an urgent problem to be solved by those skilled in the art. Utility Model Content

[0012] To address the shortcomings of existing carbon dioxide hydrogenation to methanol technology, such as low single-pass conversion rate, large circulating gas volume, and high energy consumption, this invention provides a series-parallel process system for CO2 hydrogenation to methanol. By connecting the first-stage reactor and the second-stage reactor in series and parallel, a higher single-pass conversion rate is achieved, and the circulating gas volume is reduced, thereby achieving energy saving.

[0013] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0014] A series-parallel process system for CO2 hydrogenation to methanol includes a first-stage reactor and a second-stage reactor. The first-stage reactor includes a water-cooled reactor one and a water-cooled reactor two, and the second-stage reactor includes an air-cooled reactor. The first-stage reactor and the second-stage reactor are connected in series to form a loop A, and the second-stage reactor forms a loop B.

[0015] The circuit A further includes a gas compressor, a gas booster, a heat exchanger, a heat exchanger, a crude methanol separator tank 1, and a crude methanol separator tank 2. The outlet of the gas compressor is connected to the inlet of the gas booster, the outlet of the gas booster is connected to the tube-side inlet of the gas-cooled reactor, the tube-side outlet of the gas-cooled reactor is connected to the inlet of the first-stage reactor, the outlet of the first-stage reactor is connected to the tube-side inlet of the heat exchanger, the tube-side outlet of the heat exchanger is connected to the heat exchanger, the heat exchanger is connected to crude methanol separator tank 1, crude methanol separator tank 1 is connected to the shell-side inlet of the heat exchanger, the shell-side outlet of the heat exchanger is connected to the inlet of the inter-tube catalyst bed of the gas-cooled reactor, the outlet of the inter-tube catalyst bed of the gas-cooled reactor is connected to crude methanol separator tank 2, and the gas phase outlet of crude methanol separator tank 2 is connected to the gas booster and the venting gas outlet.

[0016] The circuit B also includes a gas compressor, a second crude methanol separator, and a gas booster. The gas compressor is connected to the inlet of the inter-tube catalyst bed of the gas-cooled reactor, the outlet of the inter-tube catalyst bed of the gas-cooled reactor is connected to the second crude methanol separator, and the gas phase outlet of the second crude methanol separator is connected to the gas booster and the venting gas outlet.

[0017] Furthermore, the first-stage reactor and the second-stage reactor are either axial reactors or radial reactors.

[0018] Furthermore, the first-stage reactor and the second-stage reactor are adiabatic reactors.

[0019] Furthermore, the adiabatic reactor is an adiabatic quench reactor.

[0020] Furthermore, the liquid phase outlets of the crude methanol separator one and crude methanol separator two are connected to the methanol refining unit.

[0021] Furthermore, the heat exchanger is an air cooler and / or a circulating water cooler.

[0022] The beneficial effects of this invention are as follows: The system features interstage condensation and separation of methanol between the two reactor stages, resulting in a reasonable combination, high single-pass conversion rate, low recycle rate, and good reaction performance. Syngas simultaneously enters both the first and second-stage reactors, which facilitates adjustment of the reactor loads and allows for synchronized catalyst aging. Furthermore, this series-parallel operation reduces the recycle volume, leading to lower energy consumption and relatively smaller pipeline dimensions in the overall methanol production process. This process system offers advantages such as high single-pass conversion rate, low gas recycle volume, reduced energy consumption, and good reaction performance. Attached Figure Description

[0023] Figure 1 This is a flow chart of a series-parallel process for producing methanol from CO2 via hydrogenation.

[0024] In the diagram: C-2001, gas compressor; C-2002, gas booster; R-2002, gas-cooled reactor; R-2001A, water-cooled reactor one; R-2001B, water-cooled reactor two; E-2007, heat exchanger; E-2008, heat exchanger; D-2003, crude methanol separator one; D-2002, crude methanol separator two. Detailed Implementation

[0025] A series-parallel process system for CO2 hydrogenation to methanol includes a first-stage reactor and a second-stage reactor. The first-stage reactor includes a water-cooled reactor R-2001A and a water-cooled reactor R-2001B. The second-stage reactor includes an air-cooled reactor R-2002. The first-stage reactor and the second-stage reactor are connected in series to form loop A, and the second-stage reactor forms loop B.

[0026] The circuit A also includes a gas compressor C-2001, a gas booster C-2002, a heat exchanger E-2007, a heat exchanger E-2008, a crude methanol separator D-2003 (first stage), and a crude methanol separator D-2002 (second stage). The outlet of the gas compressor C-2001 is connected to the inlet of the gas booster C-2002. The outlet of the gas booster C-2002 is connected to the tube-side inlet of the gas-cooled reactor R-2002. The tube-side outlet of the gas-cooled reactor R-2002 is connected to the inlet of the first-stage reactor. The outlet of the first-stage reactor is connected to the tube-side inlet of the heat exchanger E-2007. The tube-side outlet of heat exchanger E-2007 is connected to heat exchanger E-2008. Heat exchanger E-2008 is connected to crude methanol separator D-2003. Crude methanol separator D-2003 is connected to the shell-side inlet of heat exchanger E-2007. The shell-side outlet of heat exchanger E-2007 is connected to the inlet of the intertube catalyst bed of gas-cooled reactor R-2002. The outlet of the intertube catalyst bed of gas-cooled reactor R-2002 is connected to crude methanol separator D-2002. The gas phase outlet of crude methanol separator D-2002 is connected to gas booster C-2002 and venting gas outlet.

[0027] The circuit B also includes a gas compressor C-2001, a crude methanol separator D-2002, and a gas booster C-2002. The gas compressor C-2001 is connected to the inlet of the inter-tube catalyst bed of the gas-cooled reactor R-2002. The outlet of the inter-tube catalyst bed of the gas-cooled reactor R-2002 is connected to the crude methanol separator D-2002. The gas phase outlet of the crude methanol separator D-2002 is connected to the gas booster C-2002 and the venting gas outlet.

[0028] The first-stage reactor can be an axial reactor, a radial reactor, or an adiabatic or adiabatic quench reactor, and one or more reactors can be connected in parallel; the second-stage reactor can be an axial reactor, a radial reactor, or an adiabatic quench reactor, and one or more reactors can be connected in parallel.

[0029] Figure 1In loop A: Syngas enters gas compressor C-2001 for compression, and recirculated gas enters gas booster C-2002 for pressurization. The two gas streams of syngas and recirculated gas merge, and after heat exchange in the tubes of gas-cooled reactor R-2002, they enter the catalyst beds in parallel water-cooled reactors R-2001A and R-2001B for reaction. After the reaction, the gas flows sequentially from the outlet of the water-cooled reactor into heat exchanger E-2007 for tube-side heat exchange and heat exchanger E-2008 for cooling (or air). The methanol is separated in a crude methanol separator (D-2003) and heated in the shell side of a heat exchanger (E-2007). The methanol then enters the catalyst bed in the tube-cooled reactor (R-2002) for reaction. The reaction gas exiting the gas-cooled reactor (R-2002) then enters the crude methanol separator (D-2002) after being cooled by one or more methods. Part of the gas phase from the crude methanol separator (D-2002) enters the gas booster (C-2002), while the other part is discharged as purge gas.

[0030] Figure 1 In loop B: After the synthesis gas is compressed by the gas compressor C-2001, a portion of it bypasses the water-cooled reactors R-2001A and R-2001B and is directly fed into the inter-tube catalyst bed of the gas-cooled reactor R-2002 for reaction. After one or more cooling methods, it enters the crude methanol separator D-2002. A portion of the gas phase in the crude methanol separator D-2002 enters the gas booster C-2002, and the other portion is discharged as purge gas.

[0031] The crude methanol from crude methanol separator 1 (D-2003) and crude methanol from crude methanol separator 2 (D-2002) are combined and sent to the methanol refining unit.

Claims

1. A series-parallel process system for CO2 hydrogenation to methanol, characterized in that: It includes a first-stage reactor and a second-stage reactor. The first-stage reactor includes a water-cooled reactor one (R-2001A) and a water-cooled reactor two (R-2001B). The second-stage reactor includes an air-cooled reactor (R-2002). The first-stage reactor and the second-stage reactor are connected in series to form loop A, and the second-stage reactor forms loop B. Circuit A further includes a gas compressor (C-2001), a gas booster (C-2002), a heat exchanger (E-2007), a heat exchanger (E-2008), a crude methanol separator (D-2003), and a crude methanol separator (D-2002). The outlet of the gas compressor (C-2001) is connected to the inlet of the gas booster (C-2002). The outlet of the gas booster (C-2002) is connected to the tube-side inlet of the gas-cooled reactor (R-2002). The tube-side outlet of the gas-cooled reactor (R-2002) is connected to the inlet of the first-stage reactor. The outlet of the first-stage reactor is connected to the tube-side inlet of the heat exchanger (E-2007). The tube-side outlet of heat exchanger (E-2007) is connected to heat exchanger (E-2008), heat exchanger (E-2008) is connected to crude methanol separator one (D-2003), crude methanol separator one (D-2003) is connected to the shell-side inlet of heat exchanger (E-2007), the shell-side outlet of heat exchanger (E-2007) is connected to the inlet of the intertube catalyst bed of gas-cooled reactor (R-2002), the outlet of the intertube catalyst bed of gas-cooled reactor (R-2002) is connected to crude methanol separator two (D-2002), and the gas phase outlet of crude methanol separator two (D-2002) is connected to gas booster (C-2002) and venting gas outlet; The circuit B also includes a gas compressor (C-2001), a second crude methanol separator (D-2002), and a gas booster (C-2002). The gas compressor (C-2001) is connected to the inlet of the inter-tube catalyst bed of the gas-cooled reactor (R-2002). The outlet of the inter-tube catalyst bed of the gas-cooled reactor (R-2002) is connected to the second crude methanol separator (D-2002). The gas phase outlet of the second crude methanol separator (D-2002) is connected to the gas booster (C-2002) and the venting gas outlet.

2. The system according to claim 1, characterized in that: The first-stage reactor and the second-stage reactor are either axial reactors or radial reactors.

3. The system according to claim 1, characterized in that: The first-stage reactor and the second-stage reactor are adiabatic reactors.

4. The system according to claim 3, characterized in that: The adiabatic reactor is an adiabatic quench reactor.

5. The system according to claim 1, characterized in that: The liquid phase outlets of crude methanol separator one (D-2003) and crude methanol separator two (D-2002) are connected to the methanol refining unit.

6. The system according to claim 1, characterized in that: The heat exchanger (E-2008) is an air cooler and / or a circulating water cooler.

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