A method and system for producing olefins

Abstract

The present disclosure relates to a method and system for producing olefins, water enters a new energy water electrolysis hydrogen production device to prepare hydrogen and oxygen, which provides the required oxygen for the gasification reaction in the coal gasification device and provides the required hydrogen for the methanol synthesis reaction in the synthesis gas methanol synthesis device; and the carbon dioxide generated by the gasification reaction in the coal gasification device is sent into a carbon dioxide electrolysis device to generate synthesis gas and oxygen, the synthesis gas is used as a raw material for preparing synthetic methanol, and through a methanol-to-olefin device, ethylene and propylene are produced, the water produced by the methanol-to-olefin device is further used as a raw material for electrolytic water hydrogen production, and the oxygen is used as a raw material for the gasification reaction again, thereby realizing the cyclic utilization of oxygen elements and near-zero emission of carbon dioxide.

Description

Technical Field

[0001] This disclosure relates to the field of coal chemical technology, and more specifically, to a method and system for producing olefins. Background Technology

[0002] Currently, the main route for producing low-carbon olefins from coal is coal-to-methanol (MMT) olefins, which includes steps such as air separation, coal gasification, shift conversion, methanol synthesis, and MMT olefins production. Oxygen is provided through air separation and fed into the coal gasification reactor along with coal-water slurry to produce crude syngas. Since the carbon monoxide to hydrogen ratio in the crude syngas is insufficient for subsequent methanol synthesis, it needs to enter a shift conversion unit to convert carbon monoxide into hydrogen and carbon dioxide. The converted syngas is then sent to a syngas-to-methanol unit to produce methanol, which is then used in the MMT olefins unit to synthesize ethylene, propylene, and other low-carbon products. It is evident that because coal is a carbon-rich resource with relatively low hydrogen and oxygen content, obtaining syngas with the required carbon-to-hydrogen ratio necessitates the emission of large amounts of carbon dioxide during the shift conversion process. In existing coal-to-methanol olefins routes, approximately 40% of the carbon in the raw coal is converted into low-carbon olefins, over 50% is converted into carbon dioxide for emission, and less than half of the carbon is converted into low-carbon olefins, with significant carbon dioxide emissions. Summary of the Invention

[0003] The purpose of this disclosure is to provide a method and system for producing olefins, which enables the recycling of oxygen, reduces carbon dioxide emissions during coal-to-olefin production, and achieves green electricity consumption and clean utilization of coal.

[0004] To achieve the above objectives, in one respect, this disclosure provides a method for producing olefins, the method comprising the following steps:

[0005] S1. Water is introduced into the new energy water electrolysis hydrogen production device to carry out the first electrolysis reaction, and hydrogen and oxygen are obtained.

[0006] S2. Coal raw material, water, and at least a portion of the oxygen obtained in step S1 are fed into a coal gasification unit for gasification reaction to obtain gasification products; the gasification products are separated to obtain coal gasification syngas and carbon dioxide;

[0007] S3. Water and carbon dioxide obtained in step S2 are fed into a carbon dioxide electrolysis device to carry out a second electrolysis reaction to obtain electrolytic syngas and oxygen.

[0008] S4. The coal gasification syngas, electrolysis syngas and hydrogen obtained in step S1 are fed into the syngas to methanol production unit to obtain synthetic methanol.

[0009] S5. The synthesized methanol is reacted with the methanol-to-olefins catalyst to obtain a reaction product containing olefins.

[0010] Optionally, the method further includes: introducing at least a portion of the oxygen obtained in step S3 into a coal gasification device and mixing it with the coal raw material, water, and at least a portion of the oxygen obtained in step S1 to carry out a gasification reaction.

[0011] Optionally, in step S2, the weight ratio of the coal raw material, water, and oxygen is 1:(0.05-0.8):(0.5-1), preferably 1:(0.1-0.7):(0.6-0.9);

[0012] The coal gasification syngas includes carbon monoxide and hydrogen, and the molar ratio of carbon monoxide to hydrogen is 1:(0.2-1.2), preferably 1:(0.3-0.9).

[0013] The reaction conditions for the gasification reaction include: a reaction temperature of not less than 1000℃ and a reaction pressure of 1-9MPa;

[0014] Preferably, the reaction temperature is 1100-1400℃ and the reaction pressure is 5-8MPa.

[0015] Optionally, the water in steps S1 and S3 is desalinated water with a conductivity of 0.1-10 μs / cm and a pH of 5-9 at 25°C, preferably 6-8.

[0016] The electricity used in the first and second electrolysis reactions comes from one or more of wind power, photovoltaic power, hydropower, nuclear power, and biomass power generation.

[0017] Optionally, in step S3, water and the carbon dioxide obtained in step S2 are fed into a carbon dioxide electrolysis device to contact the electrolysis catalyst for a second electrolysis reaction to obtain electrolytic syngas and oxygen.

[0018] The electrolytic catalyst includes a nickel-based catalyst.

[0019] Optionally, the method further includes feeding the gasification products into a purification device to separate carbon dioxide and remove impurities to obtain the coal gasification syngas; the impurities include at least one of ammonia, mercury, hydrogen sulfide, carbonyl sulfide, oxygen-containing compounds, and cyanide.

[0020] Optionally, the electrolytic synthesis gas includes carbon monoxide and hydrogen, and the molar ratio of carbon monoxide to hydrogen in the electrolytic synthesis gas is 1:(1-5), preferably 1:(1-3).

[0021] Optionally, in step S4, the coal gasification syngas and electrolysis syngas are mixed with the hydrogen obtained in step S1 so that the molar ratio of carbon monoxide to hydrogen in the syngas to methanol device is 1:(2-3), preferably 1:(2-2.7).

[0022] The reaction product obtained in step S5 also includes water. Optionally, the method further includes: purifying the water in the reaction product obtained in step S5 to remove impurities from the water, and then allowing the purified water to enter the new energy water electrolysis hydrogen production device for the first electrolysis reaction; the impurities include at least one of aldehyde compounds, ketone compounds and metal ions.

[0023] Optionally, the methanol-to-olefins catalyst includes a SAPO molecular sieve catalyst.

[0024] On the other hand, this disclosure provides a system for producing olefins, the system including a coal gasification unit, a syngas-to-methanol unit, a methanol-to-olefins unit, a new energy water electrolysis-to-hydrogen unit, and a carbon dioxide electrolysis unit;

[0025] The coal gasification unit includes a raw coal inlet, a water inlet, an oxygen inlet, and a gasification product outlet;

[0026] The syngas-to-methanol unit includes a syngas inlet, a hydrogen inlet, and a methanol outlet;

[0027] The methanol-to-olefins unit includes a methanol inlet, an olefins outlet, and a water outlet;

[0028] The new energy water electrolysis hydrogen production device includes a water inlet, an oxygen outlet, and a hydrogen outlet;

[0029] The carbon dioxide electrolysis device includes a carbon dioxide inlet, a water inlet, an electrolytic synthesis gas outlet, and an oxygen outlet;

[0030] The oxygen outlet of the new energy water electrolysis hydrogen production device is connected to the oxygen inlet of the coal gasification device, and the hydrogen outlet of the new energy water electrolysis hydrogen production device is connected to the hydrogen inlet of the syngas to methanol device.

[0031] The water inlet of the carbon dioxide electrolysis device is used to connect to a water source;

[0032] The gasification product outlet of the coal gasification unit and the electrolytic synthesis gas outlet of the carbon dioxide electrolysis unit are respectively connected to the synthesis gas inlet of the synthesis gas to methanol unit, and the methanol outlet of the synthesis gas to methanol unit is connected to the methanol inlet of the methanol to olefins unit.

[0033] Optionally, the system also includes a water purification device;

[0034] Optionally, the water outlet of the methanol-to-olefins unit is connected to the water inlet of the new energy water electrolysis hydrogen production unit via a first pipeline, and the water purification device is installed on the first pipeline.

[0035] Optionally, the system further includes a purification device, wherein the gasification product outlet of the coal gasification unit is connected to the syngas inlet of the syngas-to-methanol unit via a second pipeline, and the purification device is installed on the second pipeline;

[0036] The purification device includes a gasification product inlet, a carbon dioxide outlet, and a coal gasification syngas outlet.

[0037] The gasification product inlet of the purification device is connected to the gasification product outlet of the coal gasification device, the coal gasification syngas outlet of the purification device is connected to the syngas inlet of the syngas-to-methanol device, and the carbon dioxide outlet of the purification device is connected to the carbon dioxide inlet of the carbon dioxide electrolysis device.

[0038] Through the above technical solution, this disclosure provides a method and system for olefin production, which allows water to enter a new energy water electrolysis hydrogen production device to produce hydrogen and oxygen, providing the required oxygen for the gasification reaction in the coal gasification device and the required hydrogen for adjusting the carbon-hydrogen ratio in the syngas-to-methanol device; and sending the carbon dioxide generated by the gasification reaction in the coal gasification device to a carbon dioxide electrolysis device to generate syngas and oxygen, using the syngas as a raw material for the production of synthetic methanol, and the water produced from the synthesis of olefins from methanol as a raw material for water electrolysis hydrogen production, and the oxygen as a raw material for the gasification reaction, thereby realizing the recycling of oxygen and near-zero carbon dioxide emissions, achieving green electricity consumption and clean utilization of coal; eliminating the conversion device in the conventional process, and significantly reducing the scale of the air separation unit used in the prior art.

[0039] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0040] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0041] Figure 1 This is a process flow diagram of coal-to-olefins production used in Embodiment 1 of this disclosure.

[0042] Figure 2 This is a process flow diagram of coal-to-olefins production used in Comparative Example 1 of this disclosure. Detailed Implementation

[0043] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0044] In this disclosure, directional terms such as "up" and "down" refer to the up and down in the normal operating state of the device, while "inside" and "outside" refer to the outline of the device itself.

[0045] In this disclosure, olefins refer to low-carbon olefins such as ethylene and propylene.

[0046] The first aspect of this disclosure provides a method for producing olefins, the method comprising the following steps:

[0047] S1. Water is introduced into the new energy water electrolysis hydrogen production device to carry out the first electrolysis reaction, and hydrogen and oxygen are obtained.

[0048] S2. Coal raw material, water, and at least a portion of the oxygen obtained in step S1 are fed into a coal gasification unit for gasification reaction to obtain gasification products; the gasification products are separated to obtain coal gasification syngas and carbon dioxide;

[0049] S3. Water and carbon dioxide obtained in step S2 are fed into a carbon dioxide electrolysis device to carry out a second electrolysis reaction to obtain electrolytic syngas and oxygen.

[0050] S4. The coal gasification syngas, electrolysis syngas and hydrogen obtained in step S1 are fed into the syngas to methanol production unit to obtain synthetic methanol.

[0051] S5. The synthesized methanol is reacted with the methanol-to-olefins catalyst to obtain a reaction product containing olefins.

[0052] In the method provided in this disclosure, water enters a new energy water electrolysis hydrogen production device to produce hydrogen and oxygen, providing the required oxygen for the gasification reaction in the coal gasification device and the required hydrogen for the methanol production reaction in the syngas to methanol device; and the carbon dioxide generated by the gasification reaction in the coal gasification device is sent to a carbon dioxide electrolysis device to generate syngas and oxygen, using the syngas as a raw material for the preparation of synthetic methanol, and the water produced from the preparation of olefins from the synthesis of methanol is further used as a raw material for water electrolysis hydrogen production, and the oxygen is again used as a raw material for the gasification reaction, thereby realizing the recycling of oxygen and near-zero carbon dioxide emissions.

[0053] In this disclosure, the reaction conditions for the first and second electrolysis reactions are not particularly limited and can be selected as needed.

[0054] According to one embodiment of this disclosure, the method further includes: introducing at least a portion of the oxygen obtained in step S3 into a coal gasification device and mixing it with the coal raw material, water, and at least a portion of the oxygen obtained in step S1 to carry out a gasification reaction;

[0055] Optionally, the gasification reaction can be either coal-water slurry gasification or pulverized dry coal gasification.

[0056] According to one embodiment of this disclosure, in step S2, the weight ratio of the coal raw material, water and oxygen is 1:(0.05-0.8):(0.5-1), preferably 1:(0.1-0.7):(0.6-0.9); the coal gasification syngas includes carbon monoxide and hydrogen, and optionally, the molar ratio of carbon monoxide to hydrogen is 1:(0.2-1.2), preferably 1:(0.3-0.9).

[0057] According to one embodiment of this disclosure, the water in steps S1 and S3 is desalinated water with a conductivity of 0.1-10 μs / cm and a pH value of 5-9 at 25°C, preferably 6-8.

[0058] The electricity used for the first electrolysis reaction and the second electrolysis reaction comes from one or more of wind power, photovoltaic power, hydropower, nuclear power and biomass power generation;

[0059] Optionally, in step S3, water and the carbon dioxide obtained in step S2 are fed into a carbon dioxide electrolysis device to contact the electrolysis catalyst for a second electrolysis reaction to obtain electrolytic syngas and oxygen.

[0060] The electrolytic catalyst includes a nickel-based catalyst.

[0061] In step S2, the reaction conditions for the gasification reaction include: a reaction temperature of not less than 1000℃ and a reaction pressure of 1-9MPa;

[0062] Preferably, the reaction temperature is 1100-1400℃ and the reaction pressure is 5-8MPa.

[0063] According to one embodiment of this disclosure, the method further includes: sending the gasification product into a purification device to separate carbon dioxide and remove impurities to obtain the coal gasification syngas; the impurities include at least one of ammonia, mercury, hydrogen sulfide, carbonyl sulfide, oxygen-containing compounds, and cyanide.

[0064] The electrolytic synthesis gas includes carbon monoxide and hydrogen; optionally, the molar ratio of carbon monoxide to hydrogen in the electrolytic synthesis gas is 1:(1-5), preferably 1:(1-3).

[0065] According to one embodiment of this disclosure, in step S4, the coal gasification syngas and electrolysis syngas are mixed with the hydrogen obtained in step S1, so that the molar ratio of carbon monoxide to hydrogen in the syngas-to-methanol device is 1:(2-3), preferably 1:(2-2.7).

[0066] The reaction product obtained in step S5 also includes water. Optionally, the method further includes: purifying the water in the reaction product obtained in step S5 to remove impurities from the water, and then allowing the purified water to enter the new energy water electrolysis hydrogen production device for the first electrolysis reaction; the aldehyde compounds, ketone compounds and metal ions;

[0067] The methanol-to-olefins catalyst includes a SAPO molecular sieve catalyst.

[0068] The second aspect of this disclosure provides a system for producing olefins, the system comprising a coal gasification unit, a methanol-to-olefins unit, a new energy water electrolysis hydrogen production unit, and a carbon dioxide electrolysis unit;

[0069] The coal gasification unit includes a raw coal inlet, a water inlet, an oxygen inlet, and a gasification product outlet;

[0070] The syngas-to-methanol unit includes a syngas inlet, a hydrogen inlet, and a methanol outlet;

[0071] The methanol-to-olefins unit includes a methanol inlet, an olefins outlet, and a water outlet;

[0072] The new energy water electrolysis hydrogen production device includes a water inlet, an oxygen outlet, and a hydrogen outlet;

[0073] The carbon dioxide electrolysis device includes a carbon dioxide inlet, a water inlet, an electrolytic synthesis gas outlet, and an oxygen outlet;

[0074] The oxygen outlet of the new energy water electrolysis hydrogen production device is connected to the oxygen inlet of the coal gasification device, and the hydrogen outlet of the new energy water electrolysis hydrogen production device is connected to the hydrogen inlet of the syngas to methanol device.

[0075] The water inlet of the carbon dioxide electrolysis device is used to connect to a water source;

[0076] The gasification product outlet of the coal gasification unit and the electrolytic synthesis gas outlet of the carbon dioxide electrolysis unit are respectively connected to the synthesis gas inlet of the synthesis gas to methanol unit, and the methanol outlet of the synthesis gas to methanol unit is connected to the methanol inlet of the methanol to olefins unit.

[0077] According to one embodiment of this disclosure, the system further includes a water purification device;

[0078] Optionally, the water outlet of the methanol-to-olefins unit is connected to the water inlet of the water electrolysis-to-hydrogen unit via a first pipeline, and the water purification device is installed on the first pipeline.

[0079] According to this disclosure, the system further includes a purification device. Optionally, the gasification product outlet of the coal gasification device is connected to the syngas inlet of the syngas-to-methanol device via a second pipeline, and the purification device is installed on the second pipeline.

[0080] The purification device includes a gasification product inlet, a carbon dioxide outlet, and a coal gasification syngas outlet.

[0081] The gasification product outlet of the coal gasification unit is connected to the gasification product inlet of the purification unit, the coal gasification syngas outlet of the purification unit is connected to the syngas inlet of the syngas-to-methanol unit, and the carbon dioxide outlet of the purification unit is connected to the carbon dioxide inlet of the carbon dioxide electrolysis unit.

[0082] like Figure 1 As shown, in one exemplary embodiment of the coal-to-olefins system provided in this disclosure, the system includes:

[0083] Coal gasification units, syngas-to-methanol units, methanol-to-olefins units, new energy water electrolysis-to-hydrogen units, and carbon dioxide electrolysis units;

[0084] The coal gasification unit includes a raw coal inlet, a water inlet, an oxygen inlet, and a gasification product outlet; the syngas-to-methanol unit includes a syngas inlet, a hydrogen inlet, and a methanol outlet; the methanol-to-olefins unit includes a methanol inlet, an olefin outlet, and a water outlet; the new energy water electrolysis hydrogen production unit includes a water inlet, an oxygen outlet, and a hydrogen outlet; the carbon dioxide electrolysis unit includes a carbon dioxide inlet, a water inlet, an electrolytic syngas outlet, and an oxygen outlet; the oxygen outlet of the new energy water electrolysis hydrogen production unit is connected to the oxygen inlet of the coal gasification unit, and the hydrogen outlet of the new energy water electrolysis hydrogen production unit is connected to the hydrogen inlet of the syngas-to-methanol unit; the water inlet of the carbon dioxide electrolysis unit is used to connect to a water source; the electrolytic syngas outlet of the carbon dioxide electrolysis unit... The system includes a purification device. The gasification product outlet of the coal gasification unit is connected to the syngas inlet of the syngas-to-methanol unit, and the methanol outlet of the syngas-to-methanol unit is connected to the methanol inlet of the methanol-to-olefins unit. The purification device is installed on the second pipeline. The purification device includes a gasification product inlet, a carbon dioxide outlet, and a coal gasification syngas outlet. The gasification product inlet of the purification device is connected to the gasification product outlet of the coal gasification unit, the coal gasification syngas outlet of the purification device is connected to the syngas inlet of the syngas-to-methanol unit, and the carbon dioxide outlet of the purification device is connected to the carbon dioxide inlet of the carbon dioxide electrolysis unit.

[0085] The system also includes a water purification device; the water outlet of the methanol-to-olefins unit is connected to the water inlet of the new energy water electrolysis hydrogen production unit via a first pipeline, and the water purification device is installed on the first pipeline.

[0086] use Figure 1 The system shown is a method for producing olefins from coal, and the specific process includes:

[0087] S1. After desalination, water enters the new energy electrolysis water hydrogen production device to carry out the first electrolysis reaction, and hydrogen and oxygen are obtained.

[0088] S2. Coal raw material, water and at least a portion of the oxygen obtained in step S1 are fed into a coal gasification device to carry out a gasification reaction to obtain gasification products; the gasification products are sent to a purification device for separation to obtain coal gasification syngas and carbon dioxide, and to remove ammonia, mercury, hydrogen sulfide, carbonyl sulfide, oxygen-containing compounds and cyanide impurities from the gasification products.

[0089] S3. The desalinated water and the carbon dioxide obtained in step S2 are fed into a carbon dioxide electrolysis device to contact the electrolysis catalyst and carry out a second electrolysis reaction to obtain electrolytic syngas and oxygen; the electrolytic syngas includes carbon monoxide and hydrogen.

[0090] At least a portion of the oxygen obtained from the second electrolysis reaction is introduced into a coal gasification unit and mixed with the coal raw material, water, and at least a portion of the oxygen obtained in step S1 to carry out a gasification reaction;

[0091] S4. The coal gasification syngas, electrolysis syngas and hydrogen obtained in step S1 are fed into the syngas to methanol unit to obtain synthetic methanol.

[0092] S5. The synthesized methanol is reacted with the methanol-to-olefins catalyst to obtain a reaction product containing olefins and water. The obtained water is purified to remove aldehydes, ketones and metal ions. The purified water is then used as a water source to enter the new energy water electrolysis hydrogen production unit for the first electrolysis reaction.

[0093] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0094] Example 1

[0095] The process described in this embodiment is as follows: Figure 1 The new energy water electrolysis hydrogen production unit and carbon dioxide electrocatalytic unit are driven by wind power and photovoltaic power; the coal raw material is bituminous coal from a certain region, with a coal raw material consumption of 1.23 million tons / year, and its composition is detailed in Table 1.

[0096] use Figure 1 The experimental process for using the system shown to produce olefins from coal is as follows:

[0097] S1. The desalinated water is fed into the new energy electrolysis water hydrogen production device for the first electrolysis reaction to obtain hydrogen and oxygen; the conductivity of the desalinated water is 9 μs / cm and the pH value is 7 at 25℃.

[0098] S2. Coal raw material, water and at least a portion of the oxygen obtained in step S1 are fed into a coal gasification unit to carry out a coal-water slurry gasification reaction to obtain gasification products; the weight ratio of coal raw material, water and oxygen is 1:0.33:0.75; the gasification temperature is 1300℃ and the gasification pressure is 6.5MPa.

[0099] The gasification products are sent to a purification device to remove impurities such as ammonia, mercury, hydrogen sulfide, carbonyl sulfide, oxygen-containing compounds, and cyanide. After separation, coal gasification syngas and carbon dioxide are obtained. The molar ratio of hydrogen to carbon monoxide in the coal gasification syngas is 0.83:1.

[0100] S3. The desalinated water and the carbon dioxide obtained in step S2 are fed into a carbon dioxide electrolysis device to contact the electrolysis catalyst for a second electrolysis reaction, yielding electrolytic syngas and oxygen. The electrolytic syngas includes carbon monoxide and hydrogen. The desalinated water has a conductivity of 9 μS / cm and a pH of 7 at 25°C. The reaction temperature of the second electrolysis reaction is 60°C, the reaction pressure is atmospheric pressure, and the molar ratio of hydrogen to carbon monoxide in the electrolytic syngas is 2:1. The electrolysis catalyst is a nickel-based catalyst.

[0101] At least a portion of the oxygen obtained from the second electrolysis reaction is introduced into a coal gasification device and mixed with the coal raw material, water, and at least a portion of the oxygen obtained in step S1 to carry out a gasification reaction under the same conditions as the gasification reaction in step S2.

[0102] S4. The coal gasification syngas, electrolysis syngas and hydrogen obtained in step S1 are fed into the syngas to methanol unit to obtain synthetic methanol and water; the obtained water is purified to remove aldehydes, ketones and metal ions.

[0103] The electrolytic syngas and coal gasification syngas are mixed with the hydrogen obtained in step S1 to make the molar ratio of carbon monoxide to hydrogen 1:2.2.

[0104] S5. The synthesized methanol is introduced into the methanol-to-olefins unit and reacted with the methanol-to-olefins catalyst to obtain ethylene, propylene, and water; the water is desalinated and then sent to the new energy water electrolysis hydrogen production unit for recycling in the system; the methanol-to-olefins catalyst is a SAPO molecular sieve catalyst.

[0105] The products and their indicators obtained in this embodiment are shown in Table 2.

[0106] Table 1. Composition Analysis of Raw Coal

[0107]

[0108] Comparative Example 1

[0109] The process flow for producing olefins from coal in this comparative example is as follows: Figure 2 As shown, an air separation unit and a conversion unit are set in the system. The coal raw material consumption is 3 million tons / year. The composition of the raw coal is the same as in Example 1, as shown in Table 1.

[0110] Air is sent to an air separation unit to separate oxygen and nitrogen. The coal feedstock and the oxygen separated from the air separation unit are then sent to a coal gasification unit. Coal gasification uses a coal-water slurry gasification method, with an oxygen-to-coal mass ratio of 0.75:1, a gasification temperature of 1300℃, and a gasification pressure of 6.5 MPa. Gasification products include carbon monoxide, hydrogen, and carbon dioxide. A portion of the carbon monoxide from the gasification products is sent to a shift converter for carbon monoxide conversion, transforming water and carbon monoxide into carbon dioxide and hydrogen. The converted products are mixed with the non-shifted gases to achieve a hydrogen-to-carbon monoxide molar ratio of 2.2:1. The mixed gas then passes through a purification unit to separate carbon dioxide and syngas.

[0111] Syngas is sent to a syngas-to-methanol unit to synthesize methanol. The resulting methanol is then sent to a methanol-to-olefins unit where it is catalytically reacted with a fluidized bed catalyst to produce water, ethylene, and propylene.

[0112] The products and their indicators obtained in Comparative Example 1 are shown in Table 2.

[0113] Table 2. Products and their properties prepared in Example 1 and Comparative Example 1.

[0114] 1 Total raw coal volume, 10,000 tons / year 123 300 2 Ethylene products, 10,000 tons / year 35.4 35.4 3 Propylene products, 10,000 tons / year 28.8 28.8 4 Total carbon emissions, 10,000 tons / year 258 683 Process carbon emissions, 10,000 tons / year 21 402

[0115] Example 2

[0116] The raw coal used in this embodiment is gas coal from a certain region, and its composition is shown in Table 3. The process flow is the same as in Embodiment 1, except that the coal gasification device uses a dry coal powder gasification method.

[0117] Table 3. Composition Analysis of Raw Coal

[0118]

[0119] In this embodiment, the mass ratio of raw coal, water, and oxygen in the feed of the coal gasification unit is 1:0.1:0.78, the gasification temperature is 1400℃, the gasification pressure is 4.0MPa, and the molar ratio of hydrogen to carbon monoxide in the generated coal gasification syngas is 0.35.

[0120] The products and their indicators obtained in this embodiment are shown in Table 4.

[0121] Comparative Example 2

[0122] The composition of the raw coal in this comparative example is the same as that in Example 2, as shown in Table 3. The process flow is the same as that in Comparative Example 1, except that the coal gasification unit uses a dry coal powder gasification method, and the coal raw material consumption is 2.61 million tons / year.

[0123] The products and their indicators obtained in this comparative study are shown in Table 4.

[0124] Table 4. Products and their indicators prepared in Example 2 and Comparative Example 2.

[0125] 1 Total raw coal volume, 10,000 tons / year 105 261 2 Ethylene products, 10,000 tons / year 35.4 35.4 3 Propylene products, 10,000 tons / year 28.8 28.8 4 Total carbon emissions 245 652 Process carbon emissions 20 385

[0126] As can be seen from Tables 2 and 4, under the condition of the same ethylene and propylene production, the raw coal consumption of Example 1 is 1.23 million tons / year, the raw coal consumption of Example 2 is 1.05 million tons / year, the raw coal consumption of Comparative Example 1 is 3 million tons / year, and the raw coal consumption of Comparative Example 2 is 2.61 million tons / year. It can be seen that, under the condition of the same olefin production, the raw coal consumption of Examples 1 and 2 is significantly reduced compared with Comparative Examples 1 and 2. Furthermore, the total carbon emissions of Example 1 are reduced by 4.25 million tons / year compared with Comparative Example 1, and the total carbon emissions of Example 2 are reduced by 4.07 million tons / year compared with Comparative Example 2.

[0127] As can be seen, in the process flow disclosed herein, the water electrolysis and carbon dioxide electrocatalytic devices use green electricity resources such as wind power and hydropower, and all the oxygen in the coal gasification device is green oxygen, which greatly reduces the scale of the air separation device. Furthermore, the water generated in the carbon dioxide and methanol-to-olefins process is recycled and reused through the above devices, which further realizes the recycling of oxygen and reduces the carbon emissions of the entire production process.

[0128] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0129] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0130] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for producing olefins, characterized in that, The method includes the following steps: S1. Water is introduced into the new energy water electrolysis hydrogen production device to carry out the first electrolysis reaction, and hydrogen and oxygen are obtained. S2. Coal raw material, water, and at least a portion of the oxygen obtained in step S1 are fed into a coal gasification unit for gasification reaction to obtain gasification products; the gasification products are separated to obtain coal gasification syngas and carbon dioxide; S3. Water and carbon dioxide obtained in step S2 are fed into a carbon dioxide electrolysis device to carry out a second electrolysis reaction to obtain electrolytic syngas and oxygen. S4. The coal gasification syngas, electrolysis syngas and hydrogen obtained in step S1 are fed into the syngas to methanol production unit to obtain synthetic methanol. S5. The synthesized methanol is reacted with the methanol-to-olefins catalyst to obtain a reaction product containing olefins. The method further includes: introducing at least a portion of the oxygen obtained in step S3 into a coal gasification device and mixing it with the coal raw material, water, and at least a portion of the oxygen obtained in step S1 to carry out a gasification reaction.

2. The method according to claim 1, wherein, In step S2, the weight ratio of the coal raw material, water, and oxygen is 1:(0.05-0.8):(0.5-1). The coal gasification syngas includes carbon monoxide and hydrogen, and the molar ratio of carbon monoxide to hydrogen is 1:(0.2-1.2).

3. The method according to claim 2, wherein, In step S2, the weight ratio of the coal raw material, water, and oxygen is 1:(0.1-0.7):(0.6-0.9). The molar ratio of carbon monoxide to hydrogen is 1:(0.3-0.9).

4. The method according to claim 1, wherein, The water used in steps S1 and S3 has been desalinated and has a conductivity of 0.1-10 μs / cm and a pH of 5-9 at 25°C. The electricity used for the first electrolysis reaction and the second electrolysis reaction comes from one or more of wind power, photovoltaic power, hydropower, nuclear power and biomass power generation; In step S3, water and carbon dioxide obtained in step S2 are fed into a carbon dioxide electrolysis device to contact the electrolysis catalyst for a second electrolysis reaction, yielding electrolytic syngas and oxygen. The electrolytic catalyst includes a nickel-based catalyst.

5. The method according to claim 4, wherein, The water in steps S1 and S3 has a pH value of 6-8 after desalination treatment.

6. The method according to claim 1, wherein, In step S2, the reaction conditions for the gasification reaction include: a reaction temperature of not less than 1000℃ and a reaction pressure of 1-9MPa.

7. The method according to claim 6, wherein, The reaction conditions for the gasification reaction include: a reaction temperature of 1100-1400℃ and a reaction pressure of 5-8MPa.

8. The method according to claim 1, wherein, The method further includes: sending the gasification products into a purification device to separate carbon dioxide and remove impurities to obtain the coal gasification syngas; the impurities include at least one of ammonia, mercury, hydrogen sulfide, carbonyl sulfide, oxygen-containing compounds, and cyanide; The electrolytic synthesis gas includes carbon monoxide and hydrogen. The molar ratio of carbon monoxide to hydrogen in the electrolytic synthesis gas is 1:(1-5).

9. The method according to claim 8, wherein, The molar ratio of carbon monoxide to hydrogen in the electrolytic synthesis gas is 1:(1-3).

10. The method according to claim 1, wherein, In step S4, the coal gasification syngas and electrolysis syngas are mixed with the hydrogen obtained in step S1 so that the molar ratio of carbon monoxide to hydrogen in the syngas to methanol device is 1:(2-3). The reaction product obtained in step S5 also includes water. Optionally, the method further includes: purifying the water obtained in step S5 to remove impurities from the water, and then allowing the purified water to enter the new energy water electrolysis hydrogen production device for the first electrolysis reaction; the impurities include at least one of ketone compounds, aldehyde compounds and metal ions. The methanol-to-olefins catalyst includes a SAPO molecular sieve catalyst.

11. The method according to claim 10, wherein, The molar ratio of carbon monoxide to hydrogen in the syngas-to-methanol unit is 1:(2-2.7).

12. A system for producing olefins, characterized in that, The system includes a coal gasification unit, a syngas-to-methanol unit, a methanol-to-olefins unit, a new energy water electrolysis-to-hydrogen unit, and a carbon dioxide electrolysis unit. The coal gasification unit includes a raw coal inlet, a water inlet, an oxygen inlet, and a gasification product outlet; The syngas-to-methanol unit includes a syngas inlet, a hydrogen inlet, and a methanol outlet; The methanol-to-olefins unit includes a methanol inlet, an olefins outlet, and a water outlet; The new energy water electrolysis hydrogen production device includes a water inlet, an oxygen outlet, and a hydrogen outlet; The carbon dioxide electrolysis device includes a carbon dioxide inlet, a water inlet, an electrolytic synthesis gas outlet, and an oxygen outlet; The oxygen outlet of the new energy water electrolysis hydrogen production device is connected to the oxygen inlet of the coal gasification device, and the hydrogen outlet of the new energy water electrolysis hydrogen production device is connected to the hydrogen inlet of the syngas to methanol device. The water inlet of the carbon dioxide electrolysis device is used to connect to a water source; The gasification product outlet of the coal gasification unit and the electrolytic synthesis gas outlet of the carbon dioxide electrolysis unit are respectively connected to the synthesis gas inlet of the synthesis gas to methanol unit, and the methanol outlet of the synthesis gas to methanol unit is connected to the methanol inlet of the methanol to olefins unit. The oxygen outlet of the carbon dioxide electrolysis unit is connected to the oxygen inlet of the coal gasification unit.

13. The system according to claim 12, wherein, The system also includes a water purification device; The water outlet of the methanol-to-olefins unit is connected to the water inlet of the new energy water electrolysis hydrogen production unit via a first pipeline, and the water purification device is installed on the first pipeline.

14. The system according to claim 12, wherein, The system also includes a purification device. Optionally, the gasification product outlet of the coal gasification device is connected to the syngas inlet of the syngas-to-methanol device via a second pipeline, and the purification device is installed on the second pipeline. The purification device includes a gasification product inlet, a carbon dioxide outlet, and a coal gasification syngas outlet. The gasification product outlet of the coal gasification unit is connected to the gasification product inlet of the purification unit, the coal gasification syngas outlet of the purification unit is connected to the syngas inlet of the syngas-to-methanol unit, and the carbon dioxide outlet of the purification unit is connected to the carbon dioxide inlet of the carbon dioxide electrolysis unit.

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