System and method for using boiler hot flue gas to decompose hydrogen iodide

Abstract

Disclosed in the present invention are a system and method for using boiler hot flue gas to decompose hydrogen iodide. The system comprises a mixed liquid container, a mixed liquid pump, a pump outlet regulating valve, a boiler high-temperature flue gas zone and a temperature control valve, wherein an outlet of the mixed liquid container is connected to an inlet of the mixed liquid pump; an outlet of the mixed liquid pump is connected to an inlet of the pump outlet regulating valve; an outlet of the pump outlet regulating valve is connected to an inlet of the boiler high-temperature flue gas zone; and an outlet of the boiler high-temperature flue gas zone is connected to an inlet of the temperature control valve. In the present invention, heat is obtained from flue gas from a power station boiler; it is only necessary to place a hydrogen iodide heating device in a high-temperature zone of a furnace of the boiler, and two sides of the hydrogen iodide heating device are at low pressure, thereby greatly improving the safety; in addition, obtaining heat directly from the flue gas is more economical than obtaining heat via steam and electric energy.

Description

A system and method for decomposing hydrogen iodide using boiler hot flue gas Technical Field

[0001] This invention belongs to the field of hydrogen production technology, specifically relating to a system and method for decomposing hydrogen iodide using boiler hot flue gas. Background Technology

[0002] High-temperature hydrolysis for hydrogen production using a sulfur-iodine cycle requires pyrolysis of sulfuric acid to sulfur dioxide at temperatures above 850℃. Water, sulfur dioxide, and iodine then react at around 100℃ to produce hydrogen iodide, which decomposes into iodine and hydrogen gas at 500℃. Currently, the problems and difficulties in high-temperature hydrolysis for hydrogen production and the combustion of sulfur-containing coal are:

[0003] (1) The high temperature of 850℃ required to pyrolyze sulfuric acid into sulfur dioxide is difficult to meet.

[0004] (2) The economic efficiency of producing hydrogen from sulfuric acid by pyrolysis is poor.

[0005] Because coal combustion contains sulfur dioxide, and the flue gas from coal combustion also contains sulfur dioxide, sulfur dioxide emissions into the atmosphere cause air pollution, necessitating desulfurization measures. Obtaining sulfur dioxide from power plant boiler flue gas to form an open-loop sulfur-iodine cycle for hydrogen production is an environmentally friendly and economical method. In this method, iodine absorbs sulfur dioxide from the boiler flue gas to form a hydrogen iodide solution. The decomposition of hydrogen iodide requires heat of approximately 500°C, which is the most energy-intensive part of the cycle. While the decomposition of hydrogen iodide can be achieved through electric heating, more than 50% of the heat is lost during the conversion from thermal energy to electrical energy. The iodine absorption device for sulfur dioxide in the boiler flue gas is located near the power plant boiler. If the heat needed to decompose hydrogen iodide can be obtained from the boiler flue gas, completing the decomposition, it would undoubtedly be the most economical method. Summary of the Invention

[0006] The purpose of this invention is to provide a system and method for decomposing hydrogen iodide using boiler hot flue gas.

[0007] This invention is achieved using the following technical solution:

[0008] A system for producing hydrogen iodide using boiler hot flue gas includes a mixing container, a mixing pump, a pump outlet regulating valve, a boiler high-temperature flue gas zone, and a temperature control valve.

[0009] The outlet of the mixing container is connected to the inlet of the mixing pump, the outlet of the mixing pump is connected to the inlet of the pump outlet regulating valve, the outlet of the pump outlet regulating valve is connected to the inlet of the boiler high-temperature flue gas zone, and the outlet of the boiler high-temperature flue gas zone is connected to the inlet of the temperature control valve.

[0010] A further improvement of the present invention is that the solution inside the mixing container is a mixture of hydrogen iodide, iodine and water, the flue gas temperature in the high-temperature flue gas zone of the boiler is between 500°C and 700°C, and a heat exchanger is arranged in the high-temperature flue gas zone of the boiler.

[0011] A further improvement of the present invention is that the mixed solution in the mixing container is pressurized by the mixing pump, and after the flow rate is adjusted by the pump outlet regulating valve, it enters the heat exchanger in the high-temperature flue gas zone of the boiler. After absorbing heat in the heat exchanger in the high-temperature flue gas zone of the boiler, the temperature of the mixed solution rises and reaches the inlet of the temperature control valve.

[0012] A further improvement of the present invention is that it also includes a catalyst chamber, a hydrogen separation tower, a hydrogen storage tank, and an absorption tower; the first outlet of the temperature control valve is connected to the first inlet of the mixed liquid container, the second outlet of the temperature control valve is connected to the inlet of the catalyst chamber, the outlet of the catalyst chamber is connected to the inlet of the hydrogen separation tower, the first outlet of the hydrogen separation tower is connected to the inlet of the hydrogen storage tank, and the second outlet of the hydrogen separation tower is connected to the first inlet of the absorption tower.

[0013] A further improvement of the present invention is that the set temperature of the temperature control valve is T. When the temperature of the mixed liquid flowing out of the heat exchanger in the high-temperature flue gas zone of the boiler is less than or equal to T, the mixed liquid enters the first outlet of the temperature control valve. When the temperature of the mixed liquid flowing out of the heat exchanger in the high-temperature flue gas zone of the boiler is greater than T, the mixed liquid enters the second outlet of the temperature control valve.

[0014] A further improvement of the present invention is that the catalyst chamber is filled with a catalyst for the decomposition of hydrogen iodide, and the high-temperature hydrogen iodide solution is partially decomposed into iodine and hydrogen gas after passing through the catalyst in the catalyst chamber.

[0015] A further improvement of the present invention is that a cooler is arranged inside the hydrogen separation tower. After the mixed medium from the catalyst chamber is cooled by the cooler inside the hydrogen separation tower, the temperature drops to below 100°C. Water vapor, undecomposed hydrogen iodide, and iodine condense into liquid and enter the absorption tower, while hydrogen enters the hydrogen storage tank.

[0016] A further improvement of the present invention is that it also includes a material replenishment device, a hydrogen iodide separation tower, and a sulfuric acid storage tank; the outlet of the material replenishment device is connected to the second inlet of the absorption tower, the outlet of the absorption tower is connected to the inlet of the hydrogen iodide separation tower, the first outlet of the hydrogen iodide separation tower is connected to the inlet of the sulfuric acid storage tank, and the second outlet is connected to the second inlet of the mixed liquid container.

[0017] A further improvement of the present invention is that the sulfur dioxide, water, and iodine lost due to various factors during the replenishment process of the material replenishment device replenishment system undergo a Bunsen reaction with the sulfur dioxide, water, iodine from the material replenishment device and the mixture returned from the hydrogen separation tower to generate hydrogen iodide and sulfuric acid. The hydrogen iodide and sulfuric acid solution discharged from the absorption tower enters the hydrogen iodide separation tower, where hydrogen iodide and sulfuric acid are separated. The hydrogen iodide enters the mixed liquid container, and the sulfuric acid enters the sulfuric acid storage tank.

[0018] A method for decomposing hydrogen iodide using boiler hot flue gas, the method being based on the aforementioned system for decomposing hydrogen iodide using boiler hot flue gas, comprising:

[0019] Sulfur dioxide, water, and iodine react inside the absorption tower to produce hydrogen iodide and sulfuric acid.

[0020] The hydrogen iodide and sulfuric acid solution discharged from the absorption tower enters the hydrogen iodide separation tower, where the hydrogen iodide and sulfuric acid are separated. The hydrogen iodide enters the mixed liquid container, and the sulfuric acid enters the sulfuric acid storage tank.

[0021] The mixed solution in the mixing container is pressurized by the mixing pump, and after the flow rate is adjusted by the pump outlet regulating valve, it enters the heat exchanger in the high-temperature flue gas zone of the boiler. The temperature of the mixed solution rises after absorbing heat in the heat exchanger in the high-temperature flue gas zone of the boiler.

[0022] The temperature control valve is set to T. When the temperature of the mixed liquid flowing out of the heat exchanger in the high-temperature flue gas zone of the boiler is less than or equal to T, the mixed liquid enters the first outlet and enters the mixed liquid container to start the next cycle.

[0023] When the temperature of the mixed liquid flowing out of the heat exchanger in the high-temperature flue gas zone of the boiler is greater than T, the mixed liquid enters the second outlet and enters the catalyst chamber. In the catalyst chamber, under the action of the catalyst, hydrogen iodide decomposes into hydrogen and iodine.

[0024] The mixed medium discharged from the catalyst chamber enters the hydrogen separation tower and is cooled down to below 100°C. Water vapor, undecomposed hydrogen iodide, and iodine condense into liquid and enter the absorption tower, while hydrogen enters the hydrogen storage tank.

[0025] The mixture entering the absorption tower, after receiving sulfur dioxide, water, and iodine from the material replenishment device, begins the next cycle.

[0026] The system and method for decomposing hydrogen iodide using boiler hot flue gas provided by this invention have at least the following significant advantages:

[0027] (1) This invention proposes to obtain heat from boiler flue gas to achieve the decomposition of hydrogen iodide. The heat from boiler flue gas is the most basic heat and has the lowest heat cost, so it is the most economical.

[0028] (2) The decomposition of hydrogen iodide can be heated by electric heating, but more than 50% of the heat is lost when converting thermal energy to electrical energy, so its economic efficiency is worse than that of obtaining heat from flue gas.

[0029] (3) The decomposition of hydrogen iodide can also be achieved by heating with steam, but the pressure of steam is generally high. Using steam heating would require making the decomposer of hydrogen iodide a high-pressure device, which is less economical and safer than obtaining heat from flue gas.

[0030] (4) The method of obtaining heat from the flue gas of power plant boiler proposed in this invention is simple to implement and has high safety. Attached Figure Description

[0031] Figure 1 is a structural block diagram of a system for decomposing hydrogen iodide using boiler hot flue gas according to the present invention.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. Temperature control valve; 2. High-temperature flue gas zone of boiler; 3. Pump outlet regulating valve; 4. Mixed liquid pump; 5. Mixed liquid container; 6. Catalyst chamber; 7. Hydrogen separation tower; 8. Absorption tower; 9. Hydrogen iodide separation tower; 10. Sulfuric acid storage tank; 11. Hydrogen storage tank; 12. Material replenishment device. Detailed Implementation

[0034] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0035] As shown in Figure 1, the present invention provides a system for decomposing hydrogen iodide using boiler hot flue gas, comprising a mixed liquid container 5, a mixed liquid pump 4, a pump outlet regulating valve 3, a boiler high-temperature flue gas zone 2, a temperature control valve 1, a catalyst chamber 6, a hydrogen separation tower 7, a hydrogen storage tank 11, an absorption tower 8, a material replenishment device 12, a hydrogen iodide separation tower 9, and a sulfuric acid storage tank 10.

[0036] The outlet of the mixing container 5 is connected to the inlet of the mixing pump 4. The outlet of the mixing pump 4 is connected to the inlet of the pump outlet regulating valve 3. The outlet of the pump outlet regulating valve 3 is connected to the inlet of the boiler high-temperature flue gas zone 2. The outlet of the boiler high-temperature flue gas zone 2 is connected to the inlet of the temperature control valve 1. The first outlet of the temperature control valve 1 is connected to the first inlet of the mixing container 5. The second outlet of the temperature control valve 1 is connected to the inlet of the catalyst chamber 6. The outlet of the catalyst chamber 6 is connected to the inlet of the hydrogen separation tower 7. The first outlet of the hydrogen separation tower 7 is connected to the inlet of the hydrogen storage tank 11. The second outlet of the hydrogen separation tower 7 is connected to the first inlet of the absorption tower 8. The outlet of the material replenishment device 12 is connected to the second inlet of the absorption tower 8. The outlet of the absorption tower 8 is connected to the inlet of the hydrogen iodide separation tower 9. The first outlet of the hydrogen iodide separation tower 9 is connected to the inlet of the sulfuric acid storage tank 10. The second outlet of the hydrogen iodide separation tower 9 is connected to the second inlet of the mixing container 5.

[0037] The solution inside the mixing container 5 is a mixture of hydrogen iodide, iodine, and water. The flue gas temperature in the high-temperature flue gas zone 2 of the boiler is between 500℃ and 700℃. A heat exchanger is arranged in the high-temperature flue gas zone 2. The mixed solution in the mixing container 5 is pressurized by the mixing pump 4, and after the flow rate is regulated by the pump outlet regulating valve 3, it enters the heat exchanger in the high-temperature flue gas zone 2 of the boiler. After absorbing heat in the heat exchanger in the high-temperature flue gas zone 2 of the boiler, the temperature of the mixed solution rises and reaches the inlet of the temperature control valve 1.

[0038] The catalyst chamber 6 is filled with a catalyst for the decomposition of hydrogen iodide. After passing through the catalyst in the catalyst chamber, the high-temperature hydrogen iodide solution is partially decomposed into iodine and hydrogen gas.

[0039] A cooler is installed inside the hydrogen separation tower 7. After the mixed medium from the catalyst chamber 6 is cooled by the cooler inside the hydrogen separation tower 7, the temperature drops to below 100°C. Water vapor, undecomposed hydrogen iodide, and iodine condense into liquid and enter the absorption tower 8, while hydrogen enters the hydrogen storage tank 11.

[0040] Material replenishment device 12 replenishes the sulfur dioxide, water, and iodine lost due to various factors during the system circulation process. The sulfur dioxide, water, and iodine from material replenishment device 12, along with the mixture returned from hydrogen separation tower 7, undergo a Bunsen reaction to produce hydrogen iodide and sulfuric acid. The hydrogen iodide and sulfuric acid solution discharged from absorption tower 8 enters hydrogen iodide separation tower 9, where hydrogen iodide and sulfuric acid are separated. Hydrogen iodide enters mixed liquid container 5, and sulfuric acid enters sulfuric acid storage tank 10.

[0041] This invention provides a method for decomposing hydrogen iodide using boiler hot flue gas, comprising:

[0042] Sulfur dioxide, water, and iodine react in absorption tower 8 to produce hydrogen iodide and sulfuric acid.

[0043] The hydrogen iodide and sulfuric acid solution discharged from the absorption tower 8 enters the hydrogen iodide separation tower 9, where the hydrogen iodide and sulfuric acid are separated. The hydrogen iodide enters the mixed liquid container 5, and the sulfuric acid enters the sulfuric acid storage tank 10.

[0044] The mixed solution in the mixing container 5 is pressurized by the mixing pump 4, and after the flow rate is adjusted by the pump outlet regulating valve 3, it enters the heat exchanger in the high temperature flue gas zone 2 of the boiler. The temperature of the mixed solution rises after absorbing heat in the heat exchanger in the high temperature flue gas zone 2 of the boiler.

[0045] The temperature control valve 1 is set to T. When the temperature of the mixed liquid flowing out of the heat exchanger in the high-temperature flue gas zone 2 of the boiler is less than or equal to T, the mixed liquid enters the first outlet and enters the mixed liquid container 5 to start the next cycle.

[0046] When the temperature of the mixed liquid flowing out of the heat exchanger in the high-temperature flue gas zone 2 of the boiler is greater than T, the mixed liquid enters the second outlet and enters the catalyst chamber 6. Under the action of the catalyst in the catalyst chamber 6, hydrogen iodide decomposes into hydrogen and iodine.

[0047] The mixed medium discharged from the catalyst chamber 6 enters the hydrogen separation tower 7 and is cooled down to below 100°C. Water vapor, undecomposed hydrogen iodide, and iodine condense into liquid and enter the absorption tower 8, while hydrogen enters the hydrogen storage tank 11.

[0048] The mixture entering the absorption tower 8, after receiving sulfur dioxide, water, and iodine from the material replenishment device 12, begins the next cycle.

[0049] Example:

[0050] For a 350MW unit, if the sulfur content in the flue gas is 5g / m³ 3 Total flue gas volume: 1.3 million cubic meters 3 Theoretically, it can produce 100,000 mol of hydrogen / h and 2240m 3 Hydrogen / h, 1m 3 Hydrogen, valued at 10 yuan, is worth 22,000 yuan; it can produce 100,000 mol / h or 9.8 t / h of sulfuric acid, and 1 ton of sulfuric acid, valued at 500 yuan, is worth 4,900 yuan; the decomposition of hydrogen iodide requires 17,002.6 mJ / h of heat, which accounts for less than 1% of the heat of boiler flue gas, thus having good economic benefits.

[0051] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A system for producing hydrogen iodide using boiler flue gas, characterized in that, It includes a mixing container (5), a mixing pump (4), a pump outlet regulating valve (3), a boiler high-temperature flue gas zone (2), a temperature control valve (1), a catalyst chamber (6), a hydrogen separation tower (7), a hydrogen storage tank (11), an absorption tower (8), a material replenishment device (12), a hydrogen iodide separation tower (9), and a sulfuric acid storage tank (10). The outlet of the mixing container (5) is connected to the inlet of the mixing pump (4), the outlet of the mixing pump (4) is connected to the inlet of the pump outlet regulating valve (3), the outlet of the pump outlet regulating valve (3) is connected to the inlet of the boiler high temperature flue gas zone (2), and the outlet of the boiler high temperature flue gas zone (2) is connected to the inlet of the temperature control valve (1). The solution inside the mixing container (5) is a mixture of hydrogen iodide, iodine and water. The flue gas temperature in the high-temperature flue gas zone (2) of the boiler is between 500°C and 700°C. A heat exchanger is arranged in the high-temperature flue gas zone (2) of the boiler. The first outlet of the temperature control valve (1) is connected to the first inlet of the mixed liquid container (5), the second outlet of the temperature control valve (1) is connected to the inlet of the catalyst chamber (6), the outlet of the catalyst chamber (6) is connected to the inlet of the hydrogen separation tower (7), the first outlet of the hydrogen separation tower (7) is connected to the inlet of the hydrogen storage tank (11), and the second outlet of the hydrogen separation tower (7) is connected to the first inlet of the absorption tower (8). The outlet of the material replenishment device (12) is connected to the second inlet of the absorption tower (8), the outlet of the absorption tower (8) is connected to the inlet of the hydrogen iodide separation tower (9), the first outlet of the hydrogen iodide separation tower (9) is connected to the inlet of the sulfuric acid storage tank (10), and the second outlet is connected to the second inlet of the mixed liquid container (5).

2. The system for realizing hydrogen iodide using boiler hot flue gas according to claim 1, characterized in that, The mixed solution in the mixed solution container (5) is pressurized by the mixed solution pump (4), and after the flow rate is adjusted by the pump outlet regulating valve (3), it enters the heat exchanger in the high temperature flue gas zone (2) of the boiler. After absorbing heat in the heat exchanger in the high temperature flue gas zone (2) of the boiler, the temperature of the mixed solution rises and reaches the inlet of the temperature control valve (1).

3. The system for realizing hydrogen iodide using boiler hot flue gas according to claim 1, characterized in that, The set temperature of the temperature control valve (1) is T. When the temperature of the mixed liquid flowing out from the heat exchanger of the high-temperature flue gas zone (2) of the boiler is less than or equal to T, the mixed liquid enters the first outlet of the temperature control valve (1). When the temperature of the mixed liquid flowing out from the heat exchanger of the high-temperature flue gas zone (2) of the boiler is greater than T, the mixed liquid enters the second outlet of the temperature control valve (1).

4. A system for realizing hydrogen iodide using boiler hot flue gas according to claim 1, characterized in that, The catalyst chamber (6) is filled with a catalyst for the decomposition of hydrogen iodide. The high-temperature hydrogen iodide solution is partially decomposed into iodine and hydrogen gas after passing through the catalyst in the catalyst chamber.

5. A system for realizing hydrogen iodide using boiler hot flue gas according to claim 1, characterized in that, A cooler is arranged inside the hydrogen separation tower (7). After the mixed medium from the catalyst chamber (6) is cooled by the cooler inside the hydrogen separation tower (7), the temperature drops to below 100°C. Water vapor, undecomposed hydrogen iodide, and iodine condense into liquid and enter the absorption tower (8), while hydrogen enters the hydrogen storage tank (11).

6. A system for realizing hydrogen iodide using boiler hot flue gas according to claim 1, characterized in that, The material replenishment device (12) replenishes the sulfur dioxide, water and iodine lost due to various factors during the system circulation process. The sulfur dioxide, water and iodine from the material replenishment device (12) and the mixture returned from the hydrogen separation tower (7) undergo Bunsen reaction to generate hydrogen iodide and sulfuric acid. The hydrogen iodide and sulfuric acid solution discharged from the absorption tower (8) enters the hydrogen iodide separation tower (9), where hydrogen iodide and sulfuric acid are separated. The hydrogen iodide enters the mixed liquid container (5), and the sulfuric acid enters the sulfuric acid storage tank (10).

7. A method for decomposing hydrogen iodide using boiler hot flue gas, characterized in that, This method is based on a system for realizing hydrogen iodide using boiler hot flue gas as described in claim 1, comprising: Sulfur dioxide, water, and iodine react in the absorption tower (8) to produce hydrogen iodide and sulfuric acid; The hydrogen iodide and sulfuric acid solution discharged from the absorption tower (8) enter the hydrogen iodide separation tower (9), where the hydrogen iodide and sulfuric acid are separated. The hydrogen iodide enters the mixed liquid container (5), and the sulfuric acid enters the sulfuric acid storage tank (10). The mixed solution in the mixed solution container (5) is pressurized by the mixed solution pump (4), and after the flow rate is adjusted by the pump outlet regulating valve (3), it enters the heat exchanger in the high temperature flue gas zone (2) of the boiler. The temperature of the mixed solution rises after absorbing heat in the heat exchanger in the high temperature flue gas zone (2) of the boiler. The temperature control valve (1) is set to T. When the temperature of the mixed liquid flowing out of the heat exchanger in the high-temperature flue gas zone (2) of the boiler is less than or equal to T, the mixed liquid enters the first outlet and enters the mixed liquid container (5) to start the next cycle. When the temperature of the mixed liquid flowing out of the heat exchanger in the high-temperature flue gas zone (2) of the boiler is greater than T, the mixed liquid enters the second outlet and enters the catalyst chamber (6). In the catalyst chamber (6), under the action of the catalyst, hydrogen iodide decomposes into hydrogen and iodine. The mixed medium discharged from the catalyst chamber (6) enters the hydrogen separation tower (7) and is cooled down to below 100°C. Water vapor, undecomposed hydrogen iodide, and iodine condense into liquid and enter the absorption tower (8), while hydrogen enters the hydrogen storage tank (11). The mixture entering the absorption tower (8) begins the next cycle after receiving sulfur dioxide, water, and iodine from the material replenishment device (12).

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