Wind and light hydrogen production system utilizing flue gas of coal-fired unit to lift water

Abstract

The invention discloses a wind and light hydrogen production system for lifting water by using flue gas of a coal-fired unit, which comprises a condensation water lifting tower, the upper part of the condensation water lifting tower is connected with a chimney through a smoke exhaust pipeline, and the lower part of the condensation water lifting tower is connected with the coal-fired unit through a flue gas input pipeline; a reservoir is arranged below the condensation water extraction tower and is connected with an electrolytic bath of the hydrogen production system through a water treatment pipeline, and a chemical water treatment device is arranged in the water treatment pipeline; and the electrolytic bath is connected with a wind power system and / or a photovoltaic system. According to the scheme, a flue gas cooling, condensing and water extracting method is adopted, a large amount of water in flue gas can be extracted, and the part of condensed water can be used as raw material water to be supplied to a wind-solar hydrogen production project after being treated and can also be partially recycled to a coal-fired unit, so that water saving and efficient utilization of water resources are realized.

Description

Technical Field

[0001] The present invention belongs to the field of renewable energy hydrogen production and coal-fired power generation, and specifically relates to a wind-solar hydrogen production system that utilizes flue gas from coal-fired units to extract water. Background Art

[0002] In recent years, hydrogen energy has become a consensus for the low-carbon and clean development of global energy. Based on abundant renewable energy, using electricity-generated green hydrogen as a medium, on the one hand, it can achieve large-scale consumption of renewable energy and improve the dispatchability of the power grid; on the other hand, replacing high-pollution and high-emission coal-to-hydrogen with clean and efficient green hydrogen can promote the green and low-carbon transformation of industries such as steel and chemical industry. my country will vigorously promote large-scale demonstration projects such as renewable energy hydrogen production, steelmaking, synthetic ammonia, and synthetic methanol, mainly based on wind, solar, and hydropower, with an estimated market size of more than 100 billion yuan. At the same time, hydrogen production from renewable energy water electrolysis is also an important peak-shaving energy storage method, which is of great significance for improving the utilization rate of renewable energy, improving the power grid's absorption capacity, increasing the stability of the power grid, and even building a new power system.

[0003] In recent years, my country's wind and solar hydrogen production industry has developed rapidly. Several wind and solar hydrogen production projects have been completed and put into operation, and multiple wind and solar hydrogen production demonstration projects are being planned and constructed. At present, my country's wind and solar hydrogen production projects are characterized by large scale of individual projects, and most projects have an annual hydrogen production capacity of 10,000 tons. However, since my country's wind and solar resource-rich areas are mainly concentrated in the three northern regions, and most of the three northern regions are relatively short of water, the water source required for water electrolysis to produce hydrogen is a key issue that most projects must solve. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a wind-solar hydrogen production system that utilizes the flue gas of coal-fired units to extract water, so as to solve the difficulties faced by the construction of wind-solar power generation and hydrogen production projects in areas with abundant wind and solar resources but insufficient water, and to utilize the water vapor in the flue gas of coal-fired units to provide raw water for electrolysis of water to produce hydrogen, thereby achieving water saving and efficient utilization.

[0005] According to the technical solution of the present invention, the present invention provides a wind-solar hydrogen production system that utilizes flue gas from coal-fired units to extract water, including a condensation water extraction tower, which is connected to the chimney through a smoke exhaust pipeline at the top, and is connected to the coal-fired unit through a flue gas input pipeline at the bottom; a water reservoir is provided below the condensation water extraction tower, which is connected to the electrolyzer of the hydrogen production system through a water treatment pipeline, and a chemical water treatment device is provided in the water treatment pipeline; the electrolyzer is connected to a wind power system and / or a photovoltaic system.

[0006] Furthermore, a turbulator, a spray layer and a tube bundle demister are arranged in sequence from bottom to top in the condensing water-lifting tower. The condensing water-lifting tower is connected to the chimney through a smoke exhaust pipeline above the tube bundle demister, and is connected to the coal-fired unit through a flue gas input pipeline below the turbulator.

[0007] Furthermore, the water reservoir is connected to an indirect air cooling tower via a high-temperature circulating water pipeline, a circulating water pump is provided in the high-temperature circulating water pipeline, and the indirect air cooling tower is connected to the spray water input end of the spray layer via a low-temperature circulating water pipeline.

[0008] Furthermore, the high-temperature circulating water pipeline is also connected to a heat pump.

[0009] Furthermore, it also includes a hot water storage tank, and the heat pump, the hot water storage tank, and the electrolytic cell are connected in sequence through a hot water pipeline.

[0010] Furthermore, the water reservoir is also connected to the water system of the power plant through a recycling pipeline.

[0011] Compared with the prior art, the beneficial technical effects of the present invention are as follows: 1. There are abundant coal resources and many large-capacity coal-fired units in the three northern regions of my country. At present, the inlet of the desulfurization tower of large and medium-sized coal-fired units is mostly between 90℃ and 120℃. After entering the desulfurization tower, the flue gas temperature is reduced to about 55℃. At this time, the flue gas is saturated wet flue gas with a large amount of water vapor. Taking the 660MW coal-fired unit as an example, the water consumption of desulfurization of two units can reach more than 100t / h. If no measures are taken, this part of water will be discharged into the atmosphere with the flue gas, resulting in a large amount of water resources. This scheme adopts the flue gas cooling and condensation water extraction method to reduce the saturated wet flue gas temperature from 55℃ to about 50℃, which can extract a large amount of water from the flue gas. The typical flue gas water extraction of two 660MW coal-fired units exceeds 250t / h. It can be seen that in addition to covering the water carried away by the flue gas in the desulfurization tower, more than 100t / h of water can be extracted. After treatment, this part of condensed water can be used as raw water for wind and solar hydrogen production projects, or it can be partially reused for coal-fired units, thus achieving water conservation and efficient use of water resources. Taking the 700MW wind power hydrogen production project as an example, the annual hydrogen production is 30,000 tons, and the required raw water volume is about 300,000 tons / year; the flue gas water extraction of two 660MW coal-fired units is reused for the coal-fired units themselves, and the surplus water volume is about 300,000 tons / year, which can be used for the raw water required by the 700MW wind power hydrogen production project. Therefore, if the flue gas water extraction is used first for the coal-fired units themselves, about 300,000 tons of surplus water can be used for the 30,000 tons / year wind and solar hydrogen production project each year, thus solving the water shortage problem commonly faced by the construction of wind and solar hydrogen production projects in northern regions.

[0012] 2. At the same time, the temperature of flue gas condensate is generally around 50°C, which is significantly higher than the 30°C temperature of desalted water entering the electrolyzer. Therefore, entering the electrolyzer as raw water can reduce the energy consumption required to raise the temperature of conventional raw water from room temperature to around 90°C, which helps to reduce the electricity consumption of hydrogen production in the electrolyzer.

[0013] 3. In addition, the heat brought out by flue gas condensation is discharged into the atmosphere through an indirect air cooling tower, and part of the condensed water in the water storage tank is used for indirect air cooling before entering the condensation water tower to spray the flue gas for cooling. The heat of part of the condensed water can be extracted by a heat pump and stored in a hot water storage tank. When the wind and solar power generation is insufficient, some electrolyzers will be shut down. When this electrolyzer hot standby condition occurs, the hot water storage tank can be used to supply heat to the shut-down electrolyzers, thereby realizing their hot standby, thereby accelerating the startup speed of these electrolyzers, improving the flexibility of the electrolyzers and the utilization rate of green electricity. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the system structure provided by the present invention.

[0015] Description of reference numerals in the accompanying drawings: 1. Electrolyzer; 2. Wind power system; 3. Photovoltaic system; 4. Condensation water tower; 5. Tube bundle demister; 6. Spray layer; 7. Turbulator; 8. Reservoir; 9. Circulating water pump; 10. Indirect air cooling tower; 11. Heat pump; 12. Chemical water treatment device; 13. Chimney; 14. Hot water storage tank; 15. Flue gas input pipeline; 16. Water treatment pipeline; 17. High-temperature circulating water pipeline; 18. Low-temperature circulating water pipeline; 19. Power plant water system. DETAILED DESCRIPTION

[0016] The present invention provides a wind-solar hydrogen production system that utilizes flue gas from coal-fired units to extract water, and more specifically, a system that utilizes flue gas from coal-fired generator sets to extract water and waste heat to supply water and heat for wind-solar hydrogen production projects, thereby solving the problem faced by wind-solar power generation and hydrogen production projects in areas with abundant wind and solar resources and water shortages, and utilizing water vapor in the flue gas from coal-fired units to provide raw water for electrolysis of water to produce hydrogen, thereby achieving water saving and efficient utilization.

[0017] See also Figure 1 The present invention provides a wind-solar hydrogen production system using flue gas from a coal-fired unit to extract water, including a condensing water extraction tower 4, in which a condensing heat exchange system is provided. The condensing water extraction tower 4 is connected to a chimney 13 through a smoke exhaust pipeline at the top, and is connected to a flue gas output end of the coal-fired unit after desulfurization through a flue gas input pipeline 15 at the bottom. A water reservoir 8 is provided below the condensing water extraction tower 4, and the water reservoir 8 is connected to an electrolyzer 1 of a hydrogen production system through a water treatment pipeline 16, and a chemical water treatment device 12 is provided in the water treatment pipeline 16. The electrolyzer 1 is connected to a wind power system 2 (wind power generation system) and / or a photovoltaic system 3 (photovoltaic power generation system). Thus, after the flue gas from the desulfurization tower of the coal-fired unit enters the condensation and water extraction tower 4 and is sprayed for cooling, a large amount of water vapor originally in the flue gas condenses and falls into the water reservoir 8, and the condensed water is finely treated by the chemical water treatment device 12 and then supplied to the electrolyzer 1 as raw water for hydrogen production. The cooled flue gas enters the chimney 13 and is discharged into the atmosphere.

[0018] In a specific embodiment, the condensation heat exchange system of the condensation water extraction tower 4 adopts a direct condensation heat exchange system, in other words, a hybrid condensation water extraction method, which includes arranging a turbulator 7, a spray layer 6 and a tube bundle demister 5 in sequence from bottom to top in the condensation water extraction tower 4. The condensation water extraction tower 4 is connected to the chimney 13 through a smoke exhaust pipeline above the tube bundle demister 5, and the condensation water extraction tower 4 is connected to the coal-fired unit through a smoke input pipeline 15 below the turbulator 7.

[0019] The input flue gas first flows through the turbulator 7, which can mix and distribute the flue gas evenly. The turbulator 7 increases the contact area and uniformity between the subsequent flue gas and the spray water through turbulence, which can improve the spray cooling and demisting effect. The spray layer 6 is mainly a spray device, which can spray water evenly through, for example, a nozzle structure, so that the water with a lower temperature directly contacts and mixes with the flue gas, reduces the flue gas temperature, and condenses a large amount of saturated water vapor in the flue gas into the water reservoir 8. The cooled flue gas continues to pass upward through the tube bundle demister 5 to remove the droplets and dust in the flue gas and reduce the droplet carryover, and finally enters the chimney 13 and is discharged into the atmosphere.

[0020] Furthermore, the water storage tank 8 is also connected to the indirect air cooling tower 10 through the high-temperature circulating water pipeline 17, and the high-temperature circulating water pipeline 17 is provided with a circulating water pump 9, and the indirect air cooling tower 10 is connected to the spray water input end of the spray layer 6 through the low-temperature circulating water pipeline 18. Thus, part of the condensed water in the water storage tank 8 (still at a relatively high temperature) is pressurized by the circulating water pump 9 and enters the indirect air cooling tower 10 for cooling to form low-temperature circulating water, and then enters the spray layer 6 of the condensation water tower 4 as spray water to spray the flue gas to achieve cooling.

[0021] The high-temperature circulating water pipeline 17 is also connected to a heat pump 11, which can extract part of the heat of the circulating water for use. For example, it also includes a hot water storage tank 14, and the heat pump 11, the hot water storage tank 14, and the electrolytic cell 1 are connected in sequence through a hot water pipeline. Therefore, the heat extracted by the heat pump 11 can be sent to and stored in the hot water storage tank 14, and supplied to the electrolytic cell 1 for hot standby when needed. The heat pump 11 can use the unit steam or directly use electricity as a high-level energy source, thereby raising the waste heat temperature of the condensed water to a temperature suitable for the hot standby of the electrolytic cell. More specifically, the heat pump inlet is connected to the high-temperature circulating water pipeline, and the outlet is connected to the hot water storage tank; a part of the high-temperature circulating water enters the heat pump, and the heat pump uses external steam, electricity, etc. as input energy to further increase the temperature of the high-temperature circulating water and convert it into hot water and send it to the hot water storage tank. The heat in the hot water storage tank provides a heat source for the hot standby of the electrolytic cell. Most of the high-temperature circulating water from the water reservoir 8 enters the indirect air-cooling tower 10, and the rest enters the heat pump 11 for heating when needed and then enters the hot water storage tank 14; when the hot water storage tank 14 is full of water, all the high-temperature circulating water enters the indirect air-cooling tower 10.

[0022] The water reservoir 8 is also connected to the power plant water system 19 through a recycling pipeline, so that the condensed water in the water reservoir 8 can be directly recycled to the desulfurization system of the coal-fired unit, or used for other water facilities in the power plant such as boiler water replenishment and dry ash humidification after treatment.

[0023] It can be understood that in this scheme, the condensation water extraction tower 4 is used to reduce the temperature of the saturated net flue gas after desulfurization, so as to condense and extract a large amount of water vapor therein as condensed water. In addition to the aforementioned mixed condensation water extraction method, the condensation heat exchange system in the condensation water extraction tower 4 can also adopt an indirect condensation water extraction method, such as setting a shell and tube heat exchanger structure, the flue gas is transported through the shell side of the heat exchanger, and the coolant (such as water) is transported through the tube side. The flue gas and the coolant are not in direct contact, but indirectly exchange heat. In addition, the connection of the pipelines in this system and the setting of the corresponding valves and pumps can be adjusted according to needs, and the specific structure of the hydrogen production system can use the existing technology or other feasible solutions, which is not the focus of improvement of this scheme; these specific contents are easy to implement based on the existing technology and will not be repeated here.

[0024] In summary, the temperature of the inlet of the desulfurization tower of large and medium-sized coal-fired units is mostly between 90℃ and 120℃. After entering the desulfurization tower for desulfurization, the flue gas temperature is reduced to about 55℃. At this time, the flue gas is saturated wet flue gas with a large amount of water vapor. Taking the 660MW coal-fired unit as an example, the water consumption of desulfurization of two units can reach more than 100t / h. If no measures are taken, this part of water will be discharged into the atmosphere with the flue gas, resulting in a large amount of water resource waste. This scheme adopts the flue gas cooling and condensation water extraction method to reduce the temperature of saturated wet flue gas from 55℃ to about 50℃, which can extract a large amount of water from the flue gas. The typical flue gas water extraction of two 660MW coal-fired units exceeds 250t / h. It can be seen that in addition to covering the water carried away by the flue gas in the desulfurization tower, more than 100t / h of water can be extracted. This part of condensed water can be used as raw water for wind and solar hydrogen production projects after treatment, and can also be partially reused for coal-fired units, thereby achieving water saving and efficient use of water resources. Taking the 700MW wind power hydrogen production project as an example, the annual hydrogen production capacity is 30,000 tons, and the required raw water volume is about 300,000 tons / year; the flue gas water extraction of two 660MW coal-fired units, in addition to being reused in the coal-fired units themselves, has a surplus water volume of about 300,000 tons / year, which can be used for the raw water required by the 700MW wind power hydrogen production project. Therefore, if the flue gas water extraction is used first for the coal-fired units themselves, there will be about 300,000 tons of surplus water available each year for the 30,000 tons / year wind and solar hydrogen production project, thus solving the water shortage problem commonly faced by the construction of wind and solar hydrogen production projects in the northern region. At the same time, the temperature of flue gas condensate is generally around 50°C, which is significantly higher than the conventional desalted water temperature of 30°C entering the electrolyzer. Therefore, entering the electrolyzer as raw water can reduce the energy consumption required to raise the conventional raw water from room temperature to about 90°C, which helps to reduce the electricity consumption of electrolyzer hydrogen production. In addition, the heat brought out by flue gas condensation is discharged into the atmosphere through an indirect air cooling tower, and part of the condensed water in the water storage tank is used for indirect air cooling before entering the condensation water tower to spray the flue gas for cooling. In addition, a heat pump can be used to extract the heat of part of the condensed water and store it in a hot water storage tank. When the wind and solar power generation is insufficient, some electrolyzers will be shut down. When this electrolyzer hot standby condition occurs, the hot water storage tank can be used to supply heat to the shut-down electrolyzers, thereby realizing their hot standby, thereby accelerating the startup speed of these electrolyzers, improving the flexibility of the electrolyzers and the utilization rate of green electricity.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention; for ease of description, only the parts related to the relevant inventions are shown in the accompanying drawings. In the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other; modifying the technical solutions recorded in the aforementioned embodiments, or replacing some of the technical features therein by equivalents, does not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wind-solar hydrogen production system using flue gas from coal-fired units to extract water, characterized in that: The invention comprises a condensation water extraction tower (4), wherein the condensation water extraction tower (4) is connected to a chimney (13) at the top through a smoke exhaust pipeline, and is connected to a coal-fired unit at the bottom through a smoke input pipeline (15); a water reservoir (8) is provided below the condensation water extraction tower (4), and the water reservoir (8) is connected to an electrolyzer (1) of a hydrogen production system through a water treatment pipeline (16), and a chemical water treatment device (12) is provided in the water treatment pipeline (16); and the electrolyzer (1) is connected to a wind power system (2) and / or a photovoltaic system (3).

2. The wind-solar hydrogen production system using flue gas from coal-fired units to extract water according to claim 1 is characterized in that: A turbulator (7), a spray layer (6) and a tube bundle demister (5) are arranged in sequence from bottom to top in the condensing water extraction tower (4); the condensing water extraction tower (4) is connected to the chimney (13) above the tube bundle demister (5) through a smoke exhaust pipeline; and the condensing water extraction tower (4) is connected to the coal-fired unit through a smoke input pipeline (15) below the turbulator (7).

3. The wind-solar hydrogen production system using flue gas from coal-fired units to extract water according to claim 2 is characterized in that: The water storage tank (8) is also connected to an indirect air cooling tower (10) via a high-temperature circulating water pipeline (17), a circulating water pump (9) is provided in the high-temperature circulating water pipeline (17), and the indirect air cooling tower (10) is connected to a spray water input end of the spray layer (6) via a low-temperature circulating water pipeline (18).

4. The wind-solar hydrogen production system using flue gas from coal-fired units to extract water according to claim 3 is characterized in that: The high-temperature circulating water pipeline (17) is also connected to a heat pump (11).

5. The wind-solar hydrogen production system using coal-fired unit flue gas to extract water according to claim 4 is characterized in that: It also includes a hot water storage tank (14), and the heat pump (11), the hot water storage tank (14), and the electrolytic cell (1) are connected in sequence via a hot water pipeline.

6. The wind-solar hydrogen production system using flue gas from coal-fired units to extract water according to any one of claims 1 to 5, characterized in that: The water storage tank (8) is also connected to the power plant water system (19) via a recycling pipeline.

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