CN118479957A - A methanol preparation process and preparation system - Google Patents

Abstract

The application provides a methanol preparation process and a methanol preparation system. The methanol preparation process comprises the steps of mixing a carbon oxide and hydrogen to form a mixed raw material gas, and inputting the mixed raw material gas into a methanol reactor for reaction to generate methanol; the carbon oxides include carbon monoxide and carbon dioxide; the content of carbon monoxide is less than the content of carbon dioxide; the hydrogen-carbon ratio of the mixed raw material gas is (3-5): 1. according to the methanol preparation process provided by the application, the carbon oxide is used as a carbon source, the content of carbon monoxide in the carbon source is smaller than that of the carbon dioxide, and a reasonable hydrogen-carbon ratio range is designed, so that the methanol preparation process can be more effectively carried out, and the conversion rate of mixed raw material gas to methanol and the yield of the methanol are improved.

Description

A methanol preparation process and preparation system

Technical Field

The present application relates to the technical field of methanol synthesis, and in particular to a methanol preparation process and preparation system.

Background Art

Methanol, as an important organic chemical raw material, is usually produced from coke oven gas produced in the coke industry. Coke oven gas contains a large amount of hydrogen and methane, as well as a small amount of carbon monoxide, carbon dioxide and nitrogen. Methanol can be produced by the reaction of carbon monoxide or carbon dioxide with hydrogen.

At present, methanol is used as an alternative fuel for vehicles, which has the advantages of low carbon and reduced pollutant emissions. As the application of methanol becomes more and more extensive, how to improve the methanol preparation process to increase the yield of methanol is an urgent problem to be solved at this stage.

Summary of the invention

The present application provides a methanol preparation process and a preparation system, which can improve the conversion rate of mixed raw gas to methanol and the yield of methanol.

Specifically, the present application is implemented through the following technical solutions:

On the one hand, the present application provides a methanol preparation process, comprising:

The mixed raw gas formed by mixing carbon oxides and hydrogen is input into a methanol reactor for reaction to generate methanol;

The carbon oxides include carbon monoxide and carbon dioxide; the content of carbon monoxide is less than the content of carbon dioxide; the hydrogen-to-carbon ratio of the mixed raw gas is (3-5):1.

Optionally, the volume ratio of carbon monoxide to carbon dioxide in the carbon oxides is (35%~49%): (51%~65%).

Optionally, the mixed raw gas includes an incompletely reacted circulating mixed gas obtained from the methanol reactor and a fresh mixed gas obtained after purification of exhaust gas; a mass ratio of the circulating mixed gas to the fresh mixed gas is (4-6):1.

Optionally, the fresh mixed gas includes hydrogen, carbon monoxide and carbon dioxide; the hydrogen-to-carbon ratio of the fresh mixed gas is (2.05-2.1):1.

Optionally, the volume ratio of hydrogen, carbon monoxide and carbon dioxide in the fresh mixed gas is: (65%~69%): (6~10%): (15~19%).

Optionally, in the process of inputting the mixed raw gas into the methanol reactor for reaction to generate methanol, the carbon dioxide content in the fresh mixed gas is adjusted so that the hydrogen-carbon ratio of the mixed raw gas satisfies (3-5):1.

Optionally, after obtaining the incompletely reacted circulating mixed gas from the methanol reactor, the method further comprises:

The circulating mixed gas is input into a methanol scrubber for scrubbing to remove acidic gas in the circulating mixed gas;

And/or, the circulating mixed gas is input into a hydrogen separator to separate the hydrogen in the circulating mixed gas.

Optionally, after the carbon oxides and hydrogen are mixed to form a mixed raw gas, the method further comprises:

The mixed raw gas is first input into a gas compression device for compression, and then the compressed mixed raw gas is input into the methanol reactor for reaction;

The pressure of the air inlet of the gas compression device is 1.9~2.0MPa; the pressure of the air outlet of the gas compression device is 8.0~9.0MPa;

And/or, after reacting in the methanol reactor to generate methanol, the method further includes inputting the methanol into a methanol distillation device for purification to obtain refined methanol.

On the other hand, the present application provides a methanol preparation system, which is used to perform any of the above-mentioned methanol preparation processes, comprising:

A first waste gas treatment system, a second waste gas treatment system, a methanol reactor and a mixed raw gas transmission pipeline;

The first exhaust gas treatment system is used to pre-treat the coke oven gas from the coke oven; the second exhaust gas treatment system is used to pre-treat the carbon dioxide in the exhaust gas;

The methanol reactor comprises a mixed raw gas inlet and a circulating mixed gas outlet; the first exhaust gas treatment system and the second exhaust gas treatment system are respectively connected to the mixed raw gas inlet through the mixed raw gas delivery pipeline, so as to supply fresh mixed gas to the methanol reactor;

The circulating mixed gas outlet is connected to the mixed raw gas inlet through a pipeline, and is used to supply the circulating mixed gas to the methanol reactor.

Optionally, the methanol preparation system further comprises a methanol distillator; the methanol distillator comprises a main feed cavity and a delivery pump arranged at the inlet of the main feed cavity;

The methanol reactor also includes a methanol outlet; the methanol inlet is connected to the inlet of the main feed cavity through a delivery pipeline and the delivery pump; the main feed cavity and the delivery pump are made of stainless steel.

The technical solution provided by this application can achieve the following beneficial effects:

The present application provides a methanol preparation process and a preparation system. The process uses carbon oxides as a carbon source, the carbon monoxide content in the carbon source is less than the carbon dioxide content, and a reasonable hydrogen-carbon ratio range is designed, which can be more conducive to the efficient implementation of the methanol preparation process and improve the conversion rate of the mixed raw gas to methanol and the yield of methanol.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of a methanol preparation system shown in an exemplary embodiment of the present application.

Figure numerals: 1, methanol reaction system; 1-1, methanol reactor; 1-2, methanol distillator; 1-3, mixed raw gas compression device; 1-4, hydrogen recovery device; 1-5, methanol storage tank; 2, first exhaust gas treatment system; 2-1, tar filter; 2-2, gas cabinet; 2-3, first compression equipment; 2-4, TSA pre-purifier; 2-5, second compression equipment; 2-6, fine desulfurization device; 2-7, MDEA decarbonization device; 2-8, drying and liquefaction device; 2-9, LNG storage tank; 3 , the second exhaust gas treatment system; 3-0, carbon dioxide separation equipment; 3-1, carbon supplement compression equipment section I-II; 3-2, carbon supplement compression equipment section III; a, coke oven gas; b, the first mixed gas; c, the second mixed gas; d, the third mixed gas; e, the fourth mixed gas; f, alkane liquefaction LNG; g, adsorbed carbon dioxide; h, carbon dioxide in the exhaust gas; i, carbon monoxide; j, a mixture of carbon dioxide and carbon monoxide; k, hydrogen; l, fresh mixed gas; m, circulating mixed gas; n, regenerated gas.

DETAILED DESCRIPTION

The technical solution of the present application will be described in detail below with reference to the accompanying drawings.

The endpoints and any values of the ranges disclosed in the embodiments of the present application are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article. If there are terms related to directional indications or positional relationships in the embodiments of the present application (such as up, down, left, right, front, back, inside, outside, top, bottom, center, vertical, horizontal, longitudinal, transverse, length, width, counterclockwise, clockwise, axial, radial, circumferential, etc.), such terms are only used to explain the relative positional relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings); if the specific posture changes, the directional indication or positional relationship also changes accordingly. In addition, the terms "first" and "second" in the embodiments of the present application are only used for the purpose of convenience of description, and cannot be understood as indicating or implying relative importance.

The present application provides a methanol preparation process, comprising: feeding a mixed raw gas formed by mixing carbon oxides and hydrogen into a methanol reactor for reaction to produce methanol. The carbon oxides include carbon monoxide and carbon dioxide; the content of carbon monoxide is less than the content of carbon dioxide; and the hydrogen-carbon ratio of the mixed raw gas is (3-5):1.

The chemical reaction formula for the reaction of carbon oxides and hydrogen in the mixed raw gas to methanol is: CO+ _2H2 ＝ _CH3OH （1）， _CO2 + _3H2 ＝ _CH3OH + _H2O （2）. The above scheme uses carbon oxides as the carbon source, the carbon monoxide content in the carbon source is less than the carbon dioxide content, and a reasonable hydrogen-carbon ratio range is designed. This not only avoids the excessive hydrogen-carbon ratio of the mixed raw gas, which leads to a large amount of accumulation of hydrogen on the surface of the catalyst, such as but not limited to the copper-based catalyst, thereby reducing the activity of the catalyst and thus reducing the conversion rate of methanol, but also avoids the incomplete reaction of carbon oxides due to the low hydrogen-carbon ratio, thereby reducing the conversion rate of methanol. The above scheme can be more conducive to the efficient implementation of the methanol preparation process, and improves the conversion rate of the mixed raw gas to methanol and the yield of methanol.

It should be noted that the hydrogen-carbon ratio of the mixed raw gas is usually calculated using the volume of each gas component, that is, hydrogen-carbon ratio = ( _H2 - _CO2 )/(CO+ _CO2 ). In addition, the content of carbon monoxide and the content of carbon dioxide can be expressed by volume fraction. For example, in a unit volume of carbon oxides, the volume fraction of carbon monoxide is 35% and the volume fraction of carbon dioxide is 65%, which means that the content of carbon monoxide is less than the content of carbon dioxide.

In one embodiment, the volume ratio of carbon monoxide to carbon dioxide in the carbon oxides is (35%-49%): (51%-65%). By optimizing the volume ratio of carbon monoxide to carbon dioxide within the above range, the conversion rate of carbon monoxide to methanol and the conversion rate of carbon dioxide to methanol can be taken into account, and by consuming a larger volume of carbon dioxide, it can be more environmentally friendly.

In one embodiment, the mixed raw gas includes an incompletely reacted circulating mixed gas obtained from the methanol reactor and a fresh mixed gas obtained after purification of exhaust gas; the mass ratio of the circulating mixed gas to the fresh mixed gas is (4-6):1.

In one embodiment, the fresh mixed gas includes hydrogen, carbon monoxide and carbon dioxide; the hydrogen-carbon ratio of the fresh mixed gas is (2.05-2.1): 1. By optimizing the hydrogen-carbon ratio of the fresh mixed gas within the above range, sufficient carbon source can be provided and the occurrence of side reactions can be reduced.

In one embodiment, the volume ratio of hydrogen, carbon monoxide and carbon dioxide in the fresh mixed gas is: (65%-69%): (6-10%): (15-19%). Thus, the volume selection range of each gas component can be wider, expanding the application scope of the methanol preparation process.

In one embodiment, when the mixed raw gas is fed into the methanol reactor for reaction to generate methanol, the carbon dioxide content in the fresh mixed gas is adjusted so that the hydrogen-to-carbon ratio of the mixed raw gas satisfies (3-5): 1. Thus, the intake flow rate and intake components of the mixed raw gas can be ensured to be relatively stable.

In one embodiment, after obtaining the incompletely reacted circulating mixed gas from the methanol reactor, the circulating mixed gas is also input into a methanol scrubber for washing to remove acidic gas in the circulating mixed gas. The acidic gas includes but is not limited to hydrogen sulfide. In one embodiment, the circulating mixed gas is input into a hydrogen separator to separate hydrogen from the circulating mixed gas. Exemplarily, the hydrogen separation process can be performed after the washing process, but is not limited thereto.

In one embodiment, after the carbon oxides and hydrogen are mixed to form a mixed raw gas, the mixed raw gas is first input into a gas compression device for compression, and then the compressed mixed raw gas is input into the methanol reactor for reaction. The pressure of the gas inlet of the gas compression device is 1.9-2.0 MPa; the pressure of the gas outlet of the gas compression device is 8.0-9.0 MPa.

In one embodiment, after reacting in a methanol reactor to generate methanol, the process further includes inputting the methanol into a methanol distillation device for purification to obtain refined methanol. It should be noted that the yield of methanol refers to the percentage of the amount of refined methanol purified during the distillation process to the amount of original methanol input into the methanol distillation device per unit time, i.e., the yield of methanol.

Please refer to Figure 1. The present application also provides a methanol preparation system for executing any of the above-mentioned methanol preparation processes, including a first exhaust gas treatment system 2, a second exhaust gas treatment system 3, a methanol reactor 1-1 and a mixed raw gas transmission pipeline.

The first waste gas treatment system 2 is used to pre-treat the coke oven gas a from the coke oven; the second waste gas treatment system 3 is used to pre-treat the carbon dioxide in the waste gas. Exemplarily, the waste gas can be industrial waste gas, such as but not limited to waste gas containing carbon dioxide generated in a lime kiln of a steel industry furnace charge plant. Of course, the waste gas source can also be other waste gas containing carbon dioxide in the environmental waste gas.

The methanol reactor 1-1 includes a mixed raw gas inlet and a circulating mixed gas outlet; the first exhaust gas treatment system 2 and the second exhaust gas treatment system 3 are respectively connected to the mixed raw gas inlet through the mixed raw gas conveying pipeline, so as to supply fresh mixed gas to the methanol reactor 1-1.

The circulating mixed gas outlet is connected to the mixed raw gas inlet through a pipeline, and is used to supply the circulating mixed gas to the methanol reactor 1-1.

In one embodiment, the methanol preparation system further includes a methanol distillation device 1 - 2 ; the methanol distillation device 1 - 2 includes a main feed cavity and a delivery pump disposed at the inlet of the main feed cavity.

The methanol reactor 1-1 also includes a methanol outlet; the methanol inlet is connected to the inlet of the main feed cavity through a delivery pipeline and the delivery pump; the main feed cavity and the delivery pump are made of stainless steel.

In one embodiment, the methanol preparation system further comprises a methanol scrubber. The inlet of the methanol scrubber is connected to the circulating mixed gas outlet of the methanol reactor 1-1. The washing pump in the methanol washing tower comprises a high-pressure plunger pump.

As shown in FIG1 , the specific process of a methanol preparation process performed by the methanol preparation system in this application is as follows:

The first waste gas treatment system 2 includes a tar filter 2-1, a gas cabinet 2-2, a first compression device 2-3, a TSA pre-purifier 2-4, a second compression device 2-5, a fine desulfurization device 2-6, an MDEA decarbonization device 2-7, a drying and liquefaction device 2-8 and an LNG storage tank 2-9, which are sequentially connected according to the flow direction of the gas. The second waste gas treatment system 3 includes a carbon dioxide separation device 3-0, a waste gas carbon supplementation compression device I-II section 3-1 and a carbon supplementation compression device III section 3-2, which are sequentially connected according to the flow direction of the gas. The methanol reaction system 1 includes a methanol reactor 1-1, a methanol distillator 1-2, a mixed raw gas compression device 1-3, a hydrogen recovery device 1-4 and a methanol storage tank 1-5.

The coke oven gas a from the coke oven is transported to the tar filter 2-1 at a flow rate of 45000±1490 Nm ³ /h for tar filtration, and then the remaining gas after filtration, i.e., the first mixed gas b, is stored in the gas cabinet 2-2. The first mixed gas b in the gas cabinet 2-2 is then transported to the first compression device 2-3 for compression, so that the gas pressure of the first mixed gas b reaches 0.7 MPa, and then it is purified by the TSA pre-purifier 2-4 to remove hydrocarbons such as benzene and naphthalene in the first mixed gas b to obtain the purified gas, i.e., the second mixed gas c, and then a part of the second mixed gas c is transported to the second compression device 2-5 for compression, so that the pressure of the second mixed gas c reaches 2.8 MPa, and then it is removed by the fine desulfurization device 2-6 to obtain the third mixed gas d. Then the third mixed gas d passes through the MDEA decarbonization device 2-7 to adsorb carbon dioxide, and the adsorbed carbon dioxide g is input into the carbon replenishment compression equipment I-II section 3-1 and compressed twice to a pressure of 0.6MPa. Then the third mixed gas d is stripped of carbon dioxide and the remaining gas, i.e., the fourth mixed gas e, is transported to the drying and liquefaction device 2-8 for liquefaction of alkane gas to generate alkane liquefied LNG f and stored in the LNG storage tank 2-9 for standby use.

The drying and liquefaction device 2-8 also includes a gas separation device for separating hydrogen k and carbon monoxide i from the gas remaining after removing carbon dioxide, i.e., the fourth mixed gas e. The separated carbon monoxide i (flow rate of about 1111 Nm ³ /h) is mixed with carbon dioxide g after secondary compression by the carbon supplementation compression device I-II section 3-1 to obtain a mixed gas j of carbon dioxide and carbon monoxide. The mixed gas j and carbon dioxide h (flow rate of about 5560 Nm ³ /h) from the exhaust gas enter the carbon supplementation compression device III section 3-2 together for further compression to 2.0MPa, and then mixed with hydrogen k (flow rate of about 25691 Nm ³ /h) separated by the gas separation device to form a fresh mixed gas l, which is then compressed to 8.0-9.0MPa by the mixed raw gas compression device 1-3 and then sent to the methanol reactor 1-1 for reaction. Crude methanol is obtained. The volume fraction of hydrogen in the fresh mixed gas 1 is about 67.35%, and the flow rate is about 25943Nm ³ /h; the volume fraction of carbon monoxide is about 10.19%, and the flow rate is about 3924Nm ³ /h; the volume fraction of carbon dioxide is about 17.77%, and the flow rate is about 6843Nm ³ /h; the remainder is nitrogen and methane.

The crude methanol is transported to the methanol distillation device 1-2 to remove higher alcohols, ethers, ketones and other components in the crude methanol, and obtain refined methanol by distillation, which is then stored in the methanol storage tank 1-5 for standby use.

In addition, the mixed raw gas that has not been completely reacted in the methanol reactor 1-1 is used as a circulating mixed gas m, a part of which is returned to the mixed raw gas compression device 1-3 for repeated compression to 8.0MPa-9.0MPa, and then mixed with the fresh mixed gas l at a mass ratio of 5:1 to form a mixed raw gas and returned to the methanol reactor 1-1 for re-reaction; the other part is used for hydrogen recovery, and the recovered hydrogen is stored in the hydrogen recovery device 1-4, and mixed with another part of the second mixed gas c purified by the TSA pre-purifier 2-4 as regeneration gas n, which is transported to the coke oven for reaction. Among them, the volume fraction of hydrogen in the mixed raw gas is about 64%, and the flow rate is about 107500Nm ³ /h; the volume fraction of carbon monoxide is about 3%, and the flow rate is about 6850 Nm ³ /h; the volume fraction of carbon dioxide is about 10%, and the flow rate is about 18800Nm ³ /h; the rest is nitrogen and methane.

The methanol preparation process provided in this application is compared with the technology (Emissions-To-Liguids, ETL, hereinafter referred to as the carbon-to-methanol process) developed by Iceland's Carbon Recycling International (CRI) that uses only carbon dioxide as a carbon source to synthesize methanol through hydrogenation. The methanol production process can increase the methanol yield to nearly 22%, greatly increasing the annual output of methanol.

It should be noted that the technical solutions or technical features described in the above embodiments can be combined or supplemented with each other without causing conflicts. The scope of protection of this application is not limited to the precise structures described in the above embodiments and shown in the drawings; all modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this application.

Claims (10)

1. A methanol preparation process, characterized in that it comprises: The mixed raw gas formed by mixing carbon oxides and hydrogen is input into a methanol reactor for reaction to generate methanol; The carbon oxides include carbon monoxide and carbon dioxide; the content of carbon monoxide is less than the content of carbon dioxide; the hydrogen-to-carbon ratio of the mixed raw gas is (3-5):1. 2. The methanol preparation process according to claim 1, characterized in that the volume ratio of carbon monoxide to carbon dioxide in the carbon oxides is (35%~49%): (51%~65%). 3. The methanol preparation process according to claim 1 is characterized in that the mixed raw gas includes a circulating mixed gas that has not been completely reacted obtained from the methanol reactor and a fresh mixed gas obtained after purification from the exhaust gas; the mass ratio of the circulating mixed gas to the fresh mixed gas is (4~6):1. 4. The methanol preparation process according to claim 3 is characterized in that the fresh mixed gas comprises hydrogen, carbon monoxide and carbon dioxide; and the hydrogen-to-carbon ratio of the fresh mixed gas is (2.05-2.1):1. 5. The methanol preparation process according to claim 4, characterized in that the volume ratio of hydrogen, carbon monoxide and carbon dioxide in the fresh mixed gas is: (65%~69%): (6~10%): (15~19%). 6. The methanol preparation process according to claim 4 is characterized in that, in the process of inputting the mixed raw gas into the methanol reactor for reaction to generate methanol, the content of carbon dioxide in the fresh mixed gas is adjusted so that the hydrogen-carbon ratio of the mixed raw gas satisfies (3~5):1. 7. The methanol preparation process according to claim 3, characterized in that after obtaining the unreacted circulating mixed gas from the methanol reactor, it also includes: The circulating mixed gas is input into a methanol scrubber for scrubbing to remove acidic gas in the circulating mixed gas; And/or, the circulating mixed gas is input into a hydrogen separator to separate the hydrogen in the circulating mixed gas. 8. The methanol production process according to claim 1, characterized in that after the carbon oxides and hydrogen are mixed to form a mixed raw gas, it also comprises: The mixed raw gas is first input into a gas compression device for compression, and then the compressed mixed raw gas is input into the methanol reactor for reaction; The pressure of the air inlet of the gas compression device is 1.9~2.0MPa; the pressure of the air outlet of the gas compression device is 8.0~9.0MPa; And/or, after reacting in the methanol reactor to generate methanol, the method further includes inputting the methanol into a methanol distillation device for purification to obtain refined methanol. 9. A methanol preparation system, used to perform the methanol preparation process according to any one of claims 3 to 8, characterized in that it comprises: A first waste gas treatment system, a second waste gas treatment system, a methanol reactor and a mixed raw gas transmission pipeline; The first exhaust gas treatment system is used to pre-treat the coke oven gas from the coke oven; the second exhaust gas treatment system is used to pre-treat the carbon dioxide in the exhaust gas; The methanol reactor comprises a mixed raw gas inlet and a circulating mixed gas outlet; the first exhaust gas treatment system and the second exhaust gas treatment system are respectively connected to the mixed raw gas inlet through the mixed raw gas delivery pipeline, so as to supply fresh mixed gas to the methanol reactor; The circulating mixed gas outlet is connected to the mixed raw gas inlet through a pipeline, and is used to supply the circulating mixed gas to the methanol reactor. 10. The methanol preparation system according to claim 9, characterized in that the methanol preparation system further comprises a methanol distillation device; the methanol distillation device comprises a main feed cavity and a delivery pump arranged at the inlet of the main feed cavity; The methanol reactor also includes a methanol outlet; the methanol inlet is connected to the inlet of the main feed cavity through a delivery pipeline and the delivery pump; the main feed cavity and the delivery pump are made of stainless steel.