A low-nitrogen and high-carbon combustion process method and system
Through the low-nitrogen-rich carbon combustion process, the heat pump system and the carbon capture system are combined to improve the carbon dioxide enrichment and system energy efficiency, solve the high cost and high energy consumption problems of the post-combustion capture method, and achieve environmental protection and low cost Carbon recycling.
Patent Information
- Application Number
- CN202110785842.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-07-12
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2041-07-12
AI Technical Summary
In the existing carbon capture technology, the use of liquid solvent MEA after combustion capture method has high costs, large energy consumption and equipment corrosion, resulting in large investment in flue gas carbon capture implementation, unsatisfactory results and high operating costs.
Using low-nitrogen-concentrated carbon combustion process, the flue gas at the tail of the boiler is sent to the heat pump system for heat exchange. Then most of the low-temperature flue gas enters the carbon capture system to separate and extract carbon dioxide, and a small part of the low-temperature flue gas is mixed with oxygen and then re-entered into the boiler. , dilute nitrogen to reduce the formation of thermal nitrogen oxides.
It improves the enrichment of carbon dioxide in flue gas, reduces the system energy consumption and operating costs, achieves more efficient carbon recovery, is conducive to environmental protection, and uses the original equipment, with a low overall cost.
Smart Images
Figure CN113405279B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of flue gas treatment technology, and in particular to a low-nitrogen and high-carbon combustion process method and system. Background Art
[0002] Carbon capture technology is the basis and prerequisite for carbon emission reduction measures, and it is also the most costly and energy-intensive link in the entire carbon capture, utilization and storage system. According to my country's current energy structure, it is not difficult to find that the production and supply of electricity and heat account for the largest proportion of carbon emissions. Therefore, capturing carbon dioxide emissions from boiler systems is of great significance to reducing my country's total carbon dioxide emissions. At present, there are three main capture technology routes at home and abroad, namely pre-combustion capture, oxygen-enriched combustion and post-combustion capture. Post-combustion capture technology is considered to be the most feasible carbon capture method. Post-combustion capture is a system that separates CO2 from flue gases produced by the combustion of primary fuels in air. These systems usually use liquid solvents to capture a small amount of CO2 components (generally 3-15% by volume) from flue gases whose main component is nitrogen (from air). Among them, the chemical solvent MEA (ethanolamine) is the most commonly used as a liquid solvent absorption method. However, MEA solution itself has some inherent defects, among which the more prominent ones are the high price of MEA itself, the high regeneration temperature, the large energy consumption required, the high investment and operation costs, and the easy corrosion of equipment. Summary of the invention
[0003] The present invention provides a low-nitrogen and high-carbon combustion process method and system, which solves the above-mentioned technical problems of large investment, unsatisfactory effect and high operating cost in flue gas carbon capture.
[0004] The present invention provides a low-nitrogen and high-carbon combustion process to solve the above technical problems, comprising:
[0005] S1, the tail flue gas of the boiler is sent to the heat pump system as a high-temperature heat source for heat exchange;
[0006] S2, most of the low-temperature flue gas discharged from the heat pump system enters the carbon capture system for separation and extraction of carbon dioxide gas or liquid products;
[0007] A small amount of low-temperature flue gas discharged from the heat pump system is mixed with supplementary oxygen and then re-enters the boiler for recycling. This operation not only supplements the oxygen required for combustion, but also dilutes the nitrogen in the flue gas, reduces the formation of thermal nitrogen in the final flue gas, and controls the formation of thermal nitrogen oxides during the combustion process.
[0008] Optionally, the tail flue gas of the boiler first passes through a desulfurization and denitrification device for desulfurization and denitrification before entering the heat pump system.
[0009] Optionally, the heat pump system is provided with two exhaust ports, a large exhaust port for exhausting most of the low-temperature flue gas, and a small exhaust port for exhausting a small portion of the low-temperature flue gas.
[0010] Optionally, it is characterized in that a control valve is provided on the small discharge outlet, and the control valve is used to open or close the small discharge outlet to release carbon dioxide in a quantitative manner.
[0011] Optionally, S2 specifically includes: a small portion of low-temperature flue gas discharged from the heat pump system is mixed with supplementary oxygen in a mixing box, and then sent into the boiler through a fan for recycling.
[0012] Optionally, S2 specifically includes: the carbon capture system separates and extracts the gaseous or liquid product of carbon dioxide by a physical method, and the physical method is physical adsorption or membrane method.
[0013] Optionally, S2 specifically includes: the carbon capture system separates and extracts the gaseous or liquid product of carbon dioxide by a chemical method, and the chemical method is a chemical solvent absorption method or a thermal decomposition method.
[0014] Optionally, the heat pump system uses return water in the boiler water system as a cold source to reduce the temperature of the flue gas at the tail end of the boiler.
[0015] The present invention also provides a low nitrogen and high carbon combustion system for the low nitrogen and high carbon combustion process as described above, the low nitrogen and high carbon combustion system comprising: a boiler, a heat pump system, a carbon capture system and a mixing box;
[0016] The tail flue gas of the boiler is sent to the heat pump system as a high-temperature heat source for heat exchange. Most of the low-temperature flue gas discharged by the heat pump system enters the carbon capture system for separation and extraction of carbon dioxide gas or liquid products. A small amount of low-temperature flue gas discharged from the heat pump system is mixed with supplementary oxygen in a mixing box and then re-enters the boiler for recycling.
[0017] In an optional solution, the mixing box is an empty box, and a drainage device is provided at the bottom of the empty box.
[0018] The embodiment of the present invention also provides a system for a low-nitrogen and high-carbon combustion process method, the system comprising: a boiler, a heat pump system, a carbon capture system and a mixing box. The tail flue gas of the boiler is sent to the heat pump system as a high-temperature heat source for heat exchange, and most of the low-temperature flue gas discharged by the heat pump system enters the carbon capture system for separation and extraction of carbon dioxide gaseous or liquid products. A small amount of low-temperature flue gas discharged from the heat pump system is mixed with supplementary oxygen in the mixing box and then re-enters the boiler for recycling.
[0019] In a preferred solution, the mixing box is an empty box, and a drainage device is provided at the bottom of the empty box. The gas in the mixing box undergoes a heat exchange process, so water vapor is generated, and finally water is retained in the empty box. The drainage device of the empty box discharges the water to prevent the water from accumulating and overflowing, and also to prevent the heat absorption and heat release of the accumulated water from affecting the heat exchange efficiency of the gas in the mixing box.
[0020] Beneficial effects: The present invention provides a low-nitrogen and high-carbon combustion process method and system, including: S1, the tail flue gas of the boiler is sent to the heat pump system as a high-temperature heat source for heat exchange; S2, most of the low-temperature flue gas discharged from the heat pump system enters the carbon capture system for separation and extraction of carbon dioxide gas or liquid products; a small part of the low-temperature flue gas discharged from the heat pump system is mixed with supplementary oxygen and then re-enters the boiler for recycling. This scheme realizes the function of carbon concentration and capture of the tail flue gas discharged from the boiler system, improves the enrichment of carbon dioxide in the flue gas and realizes better carbon recovery; it not only supplements the oxygen required for combustion, but also dilutes the nitrogen in the flue gas, reduces the formation of thermal nitrogen in the final flue gas, and controls the formation of thermal nitrogen oxides during the combustion process. On the other hand, the recovery of low-grade heat sources improves the overall energy efficiency of the system, is beneficial to environmental protection, utilizes the original equipment of the boiler, and has a low overall cost.
[0021] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. The specific implementation of the present invention is given in detail by the following embodiments and their accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:
[0023] Figure 1 This is a functional principle diagram of the low-nitrogen and high-carbon combustion process method and system of the present invention.
[0024] Explanation of reference numerals: boiler 1 , heat pump system 2 , carbon capture system 3 , fan 4 , mixing box 5 . DETAILED DESCRIPTION
[0025] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention. The present invention is described in more detail by way of example with reference to the accompanying drawings in the following paragraphs. The advantages and features of the present invention will become clearer according to the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.
[0026] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a component centered. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a component centered. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a component centered. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.
[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.
[0028] like Figure 1 As shown, the present invention provides a low-nitrogen and high-carbon combustion process method, comprising: S1, the tail flue gas of the boiler 1 is sent to the heat pump system 2 as a high-temperature heat source for heat exchange; S2, most of the low-temperature flue gas discharged from the heat pump system 2 enters the carbon capture system 3 for separation and extraction of carbon dioxide gas or liquid products; a small part of the low-temperature flue gas discharged from the heat pump system 2 is mixed with supplementary oxygen and then re-enters the boiler 1 for recycling. This operation not only supplements the oxygen required for combustion, but also dilutes the nitrogen in the flue gas, reduces the formation of thermal nitrogen in the final flue gas, and controls the formation of thermal nitrogen oxides during the combustion process.
[0029] This solution realizes the function of carbon concentration and capture of the tail flue gas discharged from the boiler 1 system, improves the enrichment degree of carbon dioxide in the flue gas and realizes better carbon recovery; on the other hand, it recovers low-grade heat sources, improves the overall energy efficiency of the system, is beneficial to environmental protection, utilizes the original equipment of boiler 1, has a low overall cost, and is easy to implement and promote.
[0030] The tail flue gas outlet of the boiler 1 is sealed and connected to the air inlet of the heat pump system 2 through a pipe. The heat pump system 2 has at least one low-temperature flue gas outlet. The high-temperature flue gas from the boiler 1 is subjected to heat exchange in the heat pump system 2 and then discharged to the carbon capture system 3 through the low-temperature flue gas outlet. The other part of the low-temperature flue gas returns to the boiler 1 through the pipe.
[0031] As an optional solution, the tail flue gas of the boiler 1 first passes through a desulfurization and denitrification device for desulfurization and denitrification before entering the heat pump system 2. For a coal-fired boiler 1, a desulfurization and denitrification device required for environmental protection will be installed at the outlet of the boiler 1, and the tail flue gas will first pass through the environmental protection device before entering the heat pump system 2.
[0032] As an optional solution, the heat pump system 2 is provided with two exhaust ports, one large exhaust port is used to exhaust most of the low-temperature flue gas, and the other small exhaust port is used to exhaust a small portion of the low-temperature flue gas. The small portion of the low-temperature flue gas discharged from the heat pump system 2 is mixed with the supplementary oxygen in the mixing box 5, and then sent to the boiler 1 through the fan 4 for recycling. For the gas boiler 1, the flue gas cooled by the heat pump system 2 is taken as the flue gas circulating in the flue gas recirculation, and then mixed evenly with the supplementary oxygen in the mixing box 5. The mixed gas is sent into the furnace through the fan 4 to reduce the combustion temperature of the furnace, thereby reducing the generation of nitrogen oxides. For the coal-fired boiler 1, part of the low-temperature flue gas cooled by the heat pump system 2 is taken and mixed evenly with the supplementary oxygen in the mixing box 5, and the mixed gas is sent into the furnace as secondary air through the fan 4 to assist combustion. After the above steps are circulated, the enrichment of carbon dioxide in the flue gas is completed.
[0033] In an optional solution, a control valve is provided on the small discharge port, and the control valve is used to open or close the small discharge port to quantitatively release carbon dioxide. The control valve can be an electronic valve, and the opening and closing of the valve can be remotely controlled. When the electronic valve is remotely opened, part of the low-temperature flue gas in the heat pump system 2 flows into the mixing box 5 along the connecting pipe, and then reaches the boiler 1 again through the exhaust hole of the peripheral pipeline. The amount of low-temperature flue gas is controlled by the combustion condition of the boiler 1.
[0034] As an optional solution, the temperature of most of the low-temperature flue gas discharged from the heat pump system 2 is no higher than 15°C. The tail flue gas of the boiler 1 is sent to the heat pump system 2 as a high-temperature heat source for heat exchange, outputs low-temperature flue gas (ideally around 10°C), and discharges condensed water after the flue gas is condensed. For the gas boiler 1, the amount of this part of condensed water is huge, and the volume of the output low-temperature flue gas is sharply reduced;
[0035] An optional solution, S2 specifically includes: the carbon capture system 3 separates and extracts the gaseous or liquid product of carbon dioxide by a physical method, and the physical method is physical adsorption or membrane method. The carbon capture system 3 is located at the very end of the flue gas treatment system. The low-temperature flue gas output by the heat pump system 2 contains a high concentration of carbon dioxide. After entering the carbon capture system 3, the carbon dioxide gaseous or liquid product is separated and extracted by physical or chemical methods and used or sold as an industrial gas. Among them, the physical methods are mainly physical adsorption (activated carbon) and membrane method; the chemical methods are mainly chemical solvent absorption method and thermal decomposition method.
[0036] As an optional solution, the heat pump system 2 uses the return water in the water system of the boiler 1 as a cold source to reduce the temperature of the flue gas at the tail of the boiler 1, thereby saving energy and improving the thermal energy utilization rate of the boiler 1 system.
[0037] In an optional solution, the mixing box 5 is an empty box, and a drainage device is provided at the bottom of the empty box. The water generated during the cooling process is discharged in time through the drainage device.
[0038] Beneficial effects:
[0039] (1) The enrichment of carbon dioxide in the flue gas is increased. A small amount of low-temperature flue gas discharged from the heat pump system is mixed with supplementary oxygen and then re-enters the boiler for recycling. This not only supplements the oxygen required for combustion, but also dilutes the nitrogen in the flue gas, reduces the formation of thermal nitrogen in the final flue gas, and controls the formation of thermal nitrogen oxides during the combustion process.
[0040] (2) Recover low-grade heat sources and improve the overall energy efficiency of the system.
[0041] (3) It is beneficial to the environment.
[0042] (4) The existing boiler equipment is used, and the overall cost is low.
[0043] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in the industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with the profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.
Claims
1. A low nitrogen and high carbon combustion process, characterized in that: include: S1, the tail flue gas of the boiler is sent to the heat pump system as a high-temperature heat source for heat exchange; S2, most of the low-temperature flue gas discharged from the heat pump system enters the carbon capture system for separation and extraction of carbon dioxide gas or liquid products; A small amount of low-temperature flue gas discharged from the heat pump system is mixed with supplementary oxygen and then re-enters the boiler for recycling; The heat pump system is provided with two exhaust ports, a large exhaust port for exhausting most of the low-temperature flue gas, and a small exhaust port for exhausting a small part of the low-temperature flue gas; Wherein, the S2 specifically includes: a small portion of low-temperature flue gas discharged from the heat pump system is mixed with supplementary oxygen in a mixing box and then sent into the boiler through a fan for recycling; The heat pump system uses the return water in the boiler water system as a cold source to reduce the temperature of the flue gas at the tail end of the boiler; Wherein, the mixing box is an empty box, and a drainage device is provided at the bottom of the empty box; The tail flue gas of the boiler first passes through a desulfurization and denitrification device for desulfurization and denitrification before entering the heat pump system; Wherein, a control valve is provided on the small discharge outlet, and the control valve is used to open or close the small discharge outlet to quantitatively release carbon dioxide; Among them, S2 specifically includes: the carbon capture system separates and extracts carbon dioxide gas or liquid products through a physical method, and the physical method is physical adsorption or membrane method.
2. The low nitrogen and high carbon combustion process according to claim 1, characterized in that: The S2 specifically includes: the carbon capture system separates and extracts the gaseous or liquid product of carbon dioxide through a chemical method, and the chemical method is a chemical solvent absorption method or a thermal decomposition method.
3. A low nitrogen and high carbon combustion system for the low nitrogen and high carbon combustion process according to any one of claims 1 to 2, characterized in that: The system includes: a boiler, a heat pump system, a carbon capture system and a mixing box; The tail flue gas of the boiler is sent to the heat pump system as a high-temperature heat source for heat exchange. Most of the low-temperature flue gas discharged by the heat pump system enters the carbon capture system for separation and extraction of carbon dioxide gaseous or liquid products. A small amount of low-temperature flue gas discharged from the heat pump system is mixed with supplementary oxygen in a mixing box and then re-enters the boiler for recycling. The heat pump system is provided with two exhaust ports, a large exhaust port for exhausting most of the low-temperature flue gas, and a small exhaust port for exhausting a small part of the low-temperature flue gas; Wherein, the S2 specifically includes: a small portion of low-temperature flue gas discharged from the heat pump system is mixed with supplementary oxygen in a mixing box and then sent into the boiler through a fan for recycling; The heat pump system uses the return water in the boiler water system as a cold source to reduce the temperature of the flue gas at the tail end of the boiler; Wherein, the mixing box is an empty box, and a drainage device is provided at the bottom of the empty box; The tail flue gas of the boiler first passes through a desulfurization and denitrification device for desulfurization and denitrification before entering the heat pump system; Wherein, a control valve is provided on the small discharge outlet, and the control valve is used to open or close the small discharge outlet to quantitatively release carbon dioxide; Among them, S2 specifically includes: the carbon capture system separates and extracts carbon dioxide gas or liquid products through a physical method, and the physical method is physical adsorption or membrane method.