CO 2 Comprehensive energy system and co-generation method for co-electrolysis combined with oxygen-enriched combustion power generation

Abstract

The present invention provides a comprehensive energy system and a cogeneration method for CO2 co-electrolysis combined with oxygen-enriched combustion power generation, the system comprising a wind power or photovoltaic power generation system, a water electrolysis cell, an air separation device, an ammonia synthesis module, an oxygen-enriched combustion power generation module, and a CO2 and H2O co-electrolysis cell. The present invention utilizes wind power or solar power generation to drive air separation into nitrogen and oxygen, and drives water electrolysis into hydrogen and oxygen. Oxygen is used as a combustion aid for fossil fuel combustion. Fossil fuel fuel is used for power generation to output electricity. The generated high-temperature flue gas can be directly introduced into the water electrolysis cell for co-electrolysis to generate hydrocarbons. Hydrocarbons are liquid at room temperature, easy to store and transport, and are important chemical raw materials. The source of electricity is wind power or solar power generation, and CO2 emissions are reduced. Hydrogen and nitrogen synthesize ammonia. The co-production of electricity and hydrocarbons, ammonia, etc. is achieved, and CO2 is highly valued and resourced, thereby offsetting the cost of carbon emission reduction, which is conducive to low-carbon and efficient reform of fossil fuel power generation systems.

Description

Technical Field

[0001] The present invention belongs to the technical field of comprehensive energy application, and in particular relates to a comprehensive energy system and a co-production method for CO2 co-electrolysis combined with oxygen-enriched combustion power generation. Background Art

[0002] In order to mitigate the greenhouse effect, the energy system is undergoing a green and low-carbon transformation, and reducing carbon dioxide emissions from the energy system has become a consensus of human society. Carbon dioxide capture, utilization and storage technology (CCUS) plays an important role in the green and low-carbon reform of the energy system, especially for energy-intensive industries such as thermal power generation, cement, and steel. CCUS technology can be well combined with existing equipment to avoid large-scale reconstruction of infrastructure.

[0003] However, CCUS technology requires new investment and has high operating costs. For example, the current technology for reducing carbon emissions in thermal power generation mainly involves absorbing and separating carbon dioxide from flue gas after combustion through chemical absorption or physical adsorption methods. However, due to the low volume fraction of carbon dioxide in flue gas, this type of capture system is large and the energy consumption of separation and analysis is high (power supply efficiency is reduced by 10-15%). Therefore, the high cost of carbon emission reduction has brought great difficulties to the low-carbon and clean reform in areas such as thermal power generation.

[0004] CCUS technology can reduce the cost of carbon emission reduction by converting CO2 into high-value-added raw materials, making full use of the vast market of high-value-added raw materials in modern chemical industry. For example, formic acid and methanol are important chemical raw materials with high market value, but their sources are currently fossil fuels, which belong to high-carbon chemical processes. If new low-carbon production methods for formic acid and methanol can be explored, it can also play a certain role in carbon emission reduction in the chemical industry.

[0005] Overall, the current technology costs for capturing, utilizing and storing carbon dioxide are relatively high, which makes it difficult to reduce carbon emissions from thermal power generation. At the same time, the production process of modern chemical raw materials is highly dependent on fossil fuels. Summary of the invention

[0006] The purpose of the present invention is to provide an integrated energy system and co-production method for CO2 co-electrolysis combined with oxygen-enriched combustion power generation, aiming to solve the problem that the existing carbon dioxide capture, utilization and storage technologies are relatively expensive, which brings difficulties to carbon emission reduction in thermal power generation.

[0007] The present invention is achieved by a comprehensive energy system of CO2 co-electrolysis combined with oxygen-enriched combustion power generation, comprising a wind power or photovoltaic power generation system, a water electrolysis cell, an air separation device, an ammonia synthesis module, an oxygen-enriched combustion power generation module, and a CO2 and H2O co-electrolysis cell;

[0008] The electric energy output from the electric energy output port of the wind power or photovoltaic power generation system is divided into three branches, which are respectively connected to the electric energy input port of the water electrolysis cell, the electric energy input port of the air separation device, and the electric energy input port of the CO2 and H2O co-electrolysis cell;

[0009] The water input port of the water electrolysis cell is connected to an external water source, the hydrogen output port thereof is connected to the hydrogen input port of the ammonia synthesis module, and the oxygen output port thereof is connected to the oxygen input port of the oxygen-enriched combustion power generation module;

[0010] The nitrogen output port of the air separation unit is connected to the nitrogen input port of the ammonia synthesis module, and the oxygen output port thereof is connected to the oxygen input port of the oxygen-enriched combustion power generation module;

[0011] The ammonia synthesis module is used to synthesize ammonia from the input nitrogen and hydrogen, and output it as one of the system products;

[0012] The fuel input port of the oxygen-enriched combustion power generation module is used to input fossil fuels. The fossil fuels are burned with oxygen, and chemical energy is converted into mechanical energy and then into electrical energy, which is output as the second system product. The high-temperature CO2 and H2O gases output from the tail gas output port of the oxygen-enriched combustion power generation module are divided into two streams, one of which flows into the heat source input port of the water electrolysis cell, and the other flows into the raw material input port of the CO2 and H2O co-electrolysis cell after merging with the tail gas after heat exchange from the water electrolysis cell.

[0013] The water input port of the CO2 and H2O co-electrolysis cell is connected to an external water source, and CO2 and H2O are co-electrolyzed to produce hydrocarbons, which are output as the third product of the system.

[0014] To achieve the above object, the present invention also provides a method for co-generating CO2 electrolysis combined with oxygen-enriched combustion power generation, comprising the following steps:

[0015] The electric energy generated by the wind power or photovoltaic power generation system is connected to the water electrolysis cell and the air separation device respectively; water undergoes an electrochemical reaction in the water electrolysis cell to produce hydrogen and oxygen, and air is separated in the air separation device to produce nitrogen and oxygen; the generated oxygen is all fed into the oxygen-enriched combustion power generation module as a combustion aid;

[0016] The hydrogen and nitrogen are introduced into the ammonia synthesis module to synthesize ammonia, which is output as one of the products;

[0017] In the oxygen-enriched combustion power generation module, oxygen and fossil fuels are subjected to oxygen-enriched combustion, chemical energy is converted into mechanical energy and then into electrical energy output, which is output as the second product; at the same time, high-temperature flue gas is generated, and the components of the high-temperature flue gas include carbon dioxide and water vapor;

[0018] The high-temperature flue gas is divided into two streams, one of which provides heat for the water electrolysis cell and then merges with the other stream to form a converged flue gas, which is passed into the CO2 and H2O co-electrolysis cell for co-electrolysis. The electric energy comes from the power generation of wind power or photovoltaic power generation system;

[0019] In the CO2 and H2O co-electrolysis cell, carbon dioxide and water vapor are converted into hydrocarbons and output as the third product. By connecting an external water source to the CO2 and H2O co-electrolysis cell, the ratio of H2O to CO2 can be adjusted to control the hydrocarbon generation process.

[0020] Furthermore, the chemical reaction in the ammonia synthesis module is:

[0021]

[0022] In the CO2 and H2O co-electrolysis cell, when tin oxide is used as a catalyst, the chemical reaction is:

[0023] CO2+H2O+2e - →HCOO - +OH -

[0024] When cobalt phthalocyanine is used as a catalyst, the chemical reaction is:

[0025] CO2+5H2O+6e - →CH3OH+6OH - .

[0026] Furthermore, the air separation device adopts low-temperature air separation technology.

[0027] Furthermore, the water electrolysis cell adopts alkaline water electrolysis, proton exchange membrane water electrolysis or high-temperature solid oxide water electrolysis technology.

[0028] Furthermore, by adjusting the amount of H2O introduced into the CO2 and H2O co-electrolysis cell, the ratio of CO2 and H2O in the co-electrolysis reaction can be regulated, thereby controlling the generation of the target product.

[0029] Furthermore, the hydrocarbon produced by the co-electrolysis of CO2 and H2O is methanol or formic acid.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention utilizes wind energy or solar energy to generate electricity to drive the separation of air into nitrogen and oxygen, and to drive the electrolysis of water into hydrogen and oxygen. The generated oxygen is used as a combustion aid for the combustion of fossil fuels. When fossil fuels such as natural gas and coal are burned, the chemical energy is converted into mechanical energy and then into electrical energy output. At the same time, high-temperature flue gas is generated. The high-temperature flue gas contains only water vapor and CO2, which can be directly introduced into a solid oxide electrolysis cell for co-electrolysis to generate hydrocarbons such as methanol and formic acid.

[0032] Since the electricity comes from wind or solar power generation, carbon dioxide emissions are reduced. Hydrogen and nitrogen can be synthesized into ammonia, which is exported as a system product to generate economic value. Hydrocarbons (such as methanol, formic acid, etc.) are liquid at room temperature, which is easy to store and transport, and are important intermediate raw materials in the modern chemical industry system. They not only transform the production process of hydrocarbons from a high-carbon process to a low-carbon process, but also realize the high-value resource utilization of carbon dioxide, thereby offsetting the high cost of carbon emission reduction, which is conducive to the low-carbon and efficient reform of fossil fuel power generation systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural block diagram of a comprehensive energy system for CO2 co-electrolysis combined with oxygen-enriched combustion power generation provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention; the terms "first", "second", and "third" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance; in addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be a connection between the two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] Please see Figure 1, showing a comprehensive energy system of CO2 co-electrolysis combined with oxygen-enriched combustion power generation provided by this embodiment, including a wind power or photovoltaic power generation system 1, a water electrolysis cell 2, an air separation device 3, an ammonia synthesis module 4, an oxygen-enriched combustion power generation module 5 and a CO2 and H2O co-electrolysis cell 6.

[0037] The electric energy output from the electric energy output port of the wind power or photovoltaic power generation system 1 is divided into three branches, which are respectively connected to the electric energy input port of the water electrolysis cell 2, the electric energy input port of the air separation device 3 and the electric energy input port of the CO2 and H2O co-electrolysis cell 6, thereby providing electric energy for water electrolysis, air separation and co-electrolysis.

[0038] The water input port of the water electrolysis cell 2 is connected to an external water source, the hydrogen output port thereof is connected to the hydrogen input port of the ammonia synthesis module 4 , and the oxygen output port thereof is connected to the oxygen input port of the oxygen-enriched combustion power generation module 5 .

[0039] The nitrogen output port of the air separation device 3 is connected to the nitrogen input port of the ammonia synthesis module 4 , and the oxygen output port thereof is connected to the oxygen input port of the oxygen-enriched combustion power generation module 5 .

[0040] The ammonia synthesis module 4 is used to synthesize ammonia from the input nitrogen and hydrogen, and output it as one of the system products.

[0041] The fuel input port of the oxygen-enriched combustion power generation module 5 is used to input fossil fuels. The fossil fuels are burned in oxygen, and the chemical energy is converted into mechanical energy and then into electrical energy, which is output as the second system product. The high-temperature CO2 and H2O gases output from the exhaust gas output port of the oxygen-enriched combustion power generation module 5 are divided into two streams, one of which flows into the heat source input port of the water electrolysis cell 2, and the other flows into the raw material input port of the CO2 and H2O co-electrolysis cell 6 after merging with the exhaust gas after heat exchange from the water electrolysis cell 2.

[0042] The water input port of the CO2 and H2O co-electrolysis cell 6 is connected to an external water source, and CO2 and H2O are co-electrolyzed to produce hydrocarbons (such as methanol or formic acid), which are output as the third product of the system.

[0043] The operation flow of realizing cogeneration by using the comprehensive energy system of this embodiment is as follows:

[0044] The electric energy generated by S1, wind power or photovoltaic power generation system 1 enters water electrolysis cell 2 and air separation device 3 respectively. Water undergoes electrochemical reaction in water electrolysis cell 2 to produce hydrogen and oxygen, and air produces nitrogen and oxygen in air separation device 3. The generated oxygen flows into oxygen-enriched combustion power generation module 5 as a combustion aid.

[0045] S2. Hydrogen and nitrogen flow into the ammonia synthesis module 4 to synthesize ammonia, which is output as one of the system's multiple products.

[0046] S3, in the oxygen-enriched combustion power generation module 5, oxygen and fossil fuels such as natural gas or coal are subjected to oxygen-enriched combustion, and chemical energy is converted into mechanical energy and then into electrical energy, which is output as the second multi-product of the system; at the same time, high-temperature flue gas is generated; the main components of the high-temperature flue gas are carbon dioxide and water vapor.

[0047] S4. The high-temperature flue gas is divided into two streams, one of which provides heat for the water electrolysis cell and then merges with the other to become a merged flue gas. The merged flue gas is introduced into the CO2 and H2O co-electrolysis cell 6 for co-electrolysis, and the electric energy comes from the power generation of the wind power or photovoltaic power generation system 1; in the CO2 and H2O co-electrolysis cell 6, carbon dioxide and water vapor are converted into hydrocarbons and output as the third multi-product of the system.

[0048] The chemical reaction in the ammonia synthesis module 4 is:

[0049]

[0050] In the above CO2 and H2O co-electrolysis cell 6, when tin oxide is used as a catalyst, the chemical reaction is:

[0051] CO2+H2O+2e - →HCOO - +OH -

[0052] When cobalt phthalocyanine is used as a catalyst, the chemical reaction is:

[0053] CO2+5H2O+6e - →CH3OH+6OH - .

[0054] In practical applications, the air separation device 3 may adopt low-temperature air separation technology, and the water electrolysis cell 2 may adopt alkaline water electrolysis, proton exchange membrane water electrolysis or high-temperature solid oxide water electrolysis technology.

[0055] In addition, the ratio of CO2 and H2O in the co-electrolysis reaction can be controlled by adjusting the amount of H2O introduced into the CO2 and H2O co-electrolysis cell 6, thereby controlling the generation of the target product.

[0056] In summary, this embodiment uses wind energy or solar energy to generate electricity to drive the separation of air into nitrogen and oxygen, and to drive the electrolysis of water into hydrogen and oxygen. The generated oxygen is used as a combustion aid for the combustion of fossil fuels. When fossil fuels such as natural gas and coal are burned, chemical energy is converted into mechanical energy and then into electrical energy output. At the same time, high-temperature flue gas is generated. The high-temperature flue gas contains only water vapor and CO2, which can be directly introduced into a solid oxide electrolysis cell for co-electrolysis to generate hydrocarbons such as methanol and formic acid.

[0057] Since the electricity comes from wind or solar power generation, carbon dioxide emissions are reduced. Hydrogen and nitrogen can be synthesized into ammonia, which is exported as a system product to generate economic value. Methanol, formic acid and other hydrocarbons are liquid at room temperature, which is convenient for storage and transportation. They are also important intermediate raw materials in the modern chemical industry system. They not only transform the production process of hydrocarbons from a high-carbon process to a low-carbon process, but also realize the high-value resource utilization of carbon dioxide, thereby offsetting the high cost of carbon emission reduction and facilitating the low-carbon and high-efficiency reform of fossil fuel power generation systems.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for co-generation of CO2 co-electrolysis combined with oxygen-enriched combustion power generation, characterized in that: The following steps are involved: The electric energy generated by the wind power or photovoltaic power generation system is connected to the water electrolysis cell and the air separation device respectively; water undergoes an electrochemical reaction in the water electrolysis cell to produce hydrogen and oxygen, and air is separated in the air separation device to produce nitrogen and oxygen; the generated oxygen is all fed into the oxygen-enriched combustion power generation module as a combustion aid; The hydrogen and nitrogen are introduced into the ammonia synthesis module to synthesize ammonia, which is output as one of the products; In the oxygen-enriched combustion power generation module, oxygen and fossil fuels are subjected to oxygen-enriched combustion, chemical energy is converted into mechanical energy and then into electrical energy output, which is output as the second product; at the same time, high-temperature flue gas is generated, and the components of the high-temperature flue gas include carbon dioxide and water vapor; The high-temperature flue gas is divided into two streams, one of which provides heat for the water electrolysis cell and then merges with the other stream to form a converged flue gas, which is passed into the CO2 and H2O co-electrolysis cell for co-electrolysis. The electric energy comes from the power generation of wind power or photovoltaic power generation system; In the CO2 and H2O co-electrolysis cell, carbon dioxide and water vapor are converted into hydrocarbons and output as the third product; an external water source is connected to the CO2 and H2O co-electrolysis cell to adjust the ratio of H2O and CO2 to control the hydrocarbon generation process.

2. The co-production method according to claim 1, characterized in that: The chemical reaction in the ammonia synthesis module is: In the CO2 and H2O co-electrolysis cell, when tin oxide is used as a catalyst, the chemical reaction is: CO2+H2O+2e - →HCOO - +OH - When cobalt phthalocyanine is used as a catalyst, the chemical reaction is: CO2+5H2O+6e - →CH3OH+6OH - 。 3. The co-production method according to claim 1, characterized in that: The air separation device adopts low-temperature air separation technology.

4. The co-production method according to claim 1, characterized in that: The water electrolysis cell adopts alkaline water electrolysis, proton exchange membrane water electrolysis or high-temperature solid oxide water electrolysis technology.

5. The co-production method according to claim 1, characterized in that: By adjusting the amount of H2O introduced into the CO2 and H2O co-electrolysis cell, the ratio of CO2 to H2O in the co-electrolysis reaction can be regulated, thereby controlling the generation of the target product.

6. The co-production method according to claim 5, characterized in that: The hydrocarbon produced by the co-electrolysis of CO2 and H2O is methanol or formic acid.

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