System and method for decomposing hydrogen iodide using hot exhaust gas from a boiler

Abstract

This invention discloses a system and method for decomposing hydrogen iodide using boiler heat exhaust gas. The system comprises a mixed liquid container, a mixed liquid pump, a pump outlet control valve, a boiler high-temperature exhaust gas area, and a temperature control valve. The outlet of the mixed liquid container is connected to the inlet of the mixed liquid pump, the outlet of the mixed liquid pump is connected to the inlet of the pump outlet control valve, the outlet of the pump outlet control valve is connected to the inlet of the boiler high-temperature exhaust gas area, and the outlet of the boiler high-temperature exhaust gas area is connected to the inlet of the temperature control valve. This invention obtains heat from the boiler exhaust gas of a power plant, and by simply installing a hydrogen iodide heating device in the high-temperature section of the boiler furnace, both sides of the hydrogen iodide heating device become low pressure, significantly improving safety. Furthermore, because heat is obtained directly from the exhaust gas, it is more economical than steam or electrical energy.

Description

Technical Field

[0001] The present invention relates to the field of hydrogen production technology, and more particularly to a system and method for realizing the decomposition of hydrogen iodide by the thermal exhaust gas of a boiler.

Background Art

[0002] To produce hydrogen by using high-temperature hydrolysis of the sulfur-iodine cycle, sulfuric acid is thermally decomposed into sulfur dioxide at a high temperature of 850 °C or higher, water, sulfur dioxide, and iodine produce hydrogen iodide at a temperature of about 100 °C, and hydrogen iodide decomposes into iodine and hydrogen at a temperature of 500 °C. Conventionally, the problems and difficulties in hydrogen production by high-temperature hydrolysis and sulfur-containing coal combustion are as follows.

[0003] (1) It is difficult to satisfy the high temperature of 850 °C required for thermally decomposing sulfuric acid into sulfur dioxide.

[0004] (2) The economic efficiency of hydrogen production by thermal decomposition of sulfuric acid is low.

[0005] Since coal contains sulfur dioxide and the exhaust gas after coal combustion contains sulfur dioxide, sulfur dioxide is discharged into the atmosphere and causes air pollution, so it is necessary to take desulfurization measures. Obtaining sulfur dioxide from the exhaust gas of a power plant boiler and forming an open sulfur-iodine cycle to produce hydrogen is an environmentally friendly and economical hydrogen production method. In such a method, iodine absorbs sulfur dioxide in the boiler exhaust gas to generate a hydrogen iodide solution, and about 500 °C of heat is required for the decomposition of hydrogen iodide, which is the most energy-consuming part of the cycle. The decomposition of hydrogen iodide can obtain heat by electric heating, but more than 50% of the heat is lost from thermal energy to electrical energy. The device for absorbing sulfur dioxide in the boiler exhaust gas with iodine is installed near the power plant boiler. If heat for decomposing hydrogen iodide can be obtained from the boiler exhaust gas and the decomposition of hydrogen iodide can be completed, it will be the most economical method.

Summary of the Invention

[0006] The object of the present invention is to provide a system and method for decomposing hydrogen iodide using hot exhaust gas from a boiler. [Means for solving the problem]

[0007] This invention is realized by the following technical solution.

[0008] The system for decomposing hydrogen iodide using hot exhaust gas from a boiler comprises a mixed liquid container, a mixed liquid pump, a pump outlet control valve, a boiler high-temperature exhaust gas area, and a temperature control valve.

[0009] The outlet of the mixed liquid container is connected to the inlet of the mixed liquid pump, the outlet of the mixed liquid pump is connected to the inlet of the pump outlet control valve, the outlet of the pump outlet control valve is connected to the inlet of the boiler high-temperature exhaust gas area, and the outlet of the boiler high-temperature exhaust gas area is connected to the inlet of the temperature control valve.

[0010] Further improvements to the present invention include the fact that the solution in the mixed liquid container is a mixed solution of hydrogen iodide, iodine, and water, the exhaust gas temperature in the boiler's high-temperature exhaust gas area is 500°C to 700°C, and a heat exchanger is provided in the boiler's high-temperature exhaust gas area.

[0011] A further improvement of the present invention is that the mixture in the mixture container is pressurized by a mixture pump, its flow rate is adjusted by a pump outlet adjustment valve, and then it enters the heat exchanger in the boiler's high-temperature exhaust gas area. The mixture absorbs heat in the heat exchanger in the boiler's high-temperature exhaust gas area, causing its temperature to rise, and then reaches the inlet of the temperature control valve.

[0012] A further improvement of the present invention further comprises a catalyst chamber, a hydrogen separation tower, a hydrogen tank, and an absorption tower, wherein the first outlet of a temperature control valve is connected to the first inlet of a 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 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 when the set temperature of the temperature control valve is T, if the temperature of the mixed liquid flowing out of the heat exchanger in the boiler's high-temperature exhaust gas area is T or less, the mixed liquid flows in from the first outlet of the temperature control valve, and if the temperature of the mixed liquid flowing out of the heat exchanger in the boiler's high-temperature exhaust gas area is higher than T, the mixed liquid flows in from 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 that decomposes hydrogen iodide, and the high-temperature hydrogen iodide solution is partially decomposed into iodine and hydrogen after passing through the catalyst in the catalyst chamber.

[0015] A further improvement of the present invention is that the hydrogen separation tower is equipped with a cooler, and the mixed medium from the catalyst chamber is cooled by the cooler in the hydrogen separation tower to a temperature of 100°C or lower, causing the water vapor, undecomposed hydrogen iodide, and iodine to condense into a liquid, which enters the absorption tower, and the hydrogen enters the hydrogen tank.

[0016] A further improvement of the present invention is that it comprises a material supply device, a hydrogen iodide separation tower, and a sulfuric acid tank, wherein the outlet of the material supply 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, and the hydrogen iodide separation tower has a first outlet connected to the inlet of the sulfuric acid tank and a second outlet connected to the second inlet of the mixed liquid container.

[0017] A further improvement of the present invention is that the material replenishment device replenishes sulfur dioxide, water, and iodine lost due to various factors during the system cycle, the mixture of sulfur dioxide, water, iodine from the material replenishment device and the mixture returned from the hydrogen separation tower undergoes a Bunsen reaction to produce hydrogen iodide and sulfuric acid, the solution of hydrogen iodide and sulfuric acid 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 tank.

[0018] The method for achieving the decomposition of hydrogen iodide using the hot exhaust gas of a boiler is a method carried out by the system for achieving the decomposition of hydrogen iodide using the hot exhaust gas of a boiler as described above. In an absorption tower, sulfur dioxide, water, and iodine react to produce hydrogen iodide and sulfuric acid, 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 then enters a mixed liquid container, and the sulfuric acid enters a sulfuric acid tank. The mixture in the mixture container is pressurized by the mixture pump, its flow rate is adjusted by the pump outlet control valve, and then it enters the heat exchanger in the boiler's high-temperature exhaust gas area. The mixture absorbs heat in the heat exchanger in the boiler's high-temperature exhaust gas area, causing its temperature to rise. When the temperature control valve is set to T, if the temperature of the mixed liquid flowing out of the heat exchanger in the boiler's high-temperature exhaust gas area is below T, the mixed liquid flows in from the first outlet, enters the mixed liquid container, and the next cycle begins. When the temperature of the mixed liquid flowing out of the heat exchanger in the boiler's high-temperature exhaust gas area is higher than T, the mixed liquid flows in from the second outlet and enters the catalyst chamber, where the hydrogen iodide is decomposed into hydrogen and iodine by the action of the catalyst. The mixed medium discharged from the catalyst chamber enters the hydrogen separation tower, where it is cooled to below 100°C. The water vapor, undecomposed hydrogen iodide, and iodine condense into a liquid, which then enters the absorption tower, while the hydrogen enters the hydrogen tank. The mixture entering the absorption tower receives sulfur dioxide, water, and iodine from the material replenishment unit, after which the next cycle begins. Includes.

[0019] The system and method for realizing the decomposition of hydrogen iodide by the thermal exhaust gas of a boiler according to the present invention have at least the following obvious advantages.

[0020] (1) The present invention proposes to obtain heat from boiler exhaust gas to decompose hydrogen iodide. The heat from boiler exhaust gas is the most basic heat and has the lowest heat cost, so it is the most economically efficient.

[0021] (2) Although heat can be obtained for the decomposition of hydrogen iodide by electric heating, more than 50% of the heat is lost from thermal energy to electrical energy, so the economic efficiency is poor compared with obtaining heat from exhaust gas.

[0022] (3) Although heat can also be obtained for the decomposition of hydrogen iodide by steam heating, the steam pressure generally becomes high. When using steam heating, it is necessary to make the hydrogen iodide decomposer a high-pressure device, and the economic efficiency and safety are lower compared with obtaining heat from exhaust gas.

[0023] (4) The method of obtaining heat from the boiler exhaust gas of the power plant according to the present invention is simple to implement and has high safety.

Brief Description of the Drawings

[0024] [Figure 1] FIG. 1 is a configuration block diagram of a system for realizing the decomposition of hydrogen iodide by the thermal exhaust gas of a boiler according to the present invention.

Embodiments for Carrying Out the Invention

[0025] Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. While the drawings illustrate exemplary embodiments of the present disclosure, it should be understood that the present disclosure can be implemented in various forms and should not be limited to the embodiments described herein. Rather, these embodiments are provided to allow for a deeper understanding of the present disclosure and to fully convey its scope to those skilled in the art. It should also be noted that, where no conflict arises, embodiments and features of the present invention can be combined with each other. Hereinafter, the present invention will be described in detail in combination with the embodiments, with reference to the accompanying drawings. [Examples]

[0026] As shown in Figure 1, the system for realizing the decomposition of hydrogen iodide by boiler exhaust gas according to the present invention comprises a mixed liquid container 5, a mixed liquid pump 4, a pump outlet adjustment valve 3, a boiler high-temperature exhaust gas area 2, a temperature control valve 1, a catalyst chamber 6, a hydrogen separation tower 7, a hydrogen tank 11, an absorption tower 8, a material supply device 12, a hydrogen iodide separation tower 9, and a sulfuric acid tank 10.

[0027] The outlet of the mixed liquid container 5 is connected to the inlet of the mixed liquid pump 4, the outlet of the mixed liquid pump 4 is connected to the inlet of the pump outlet control valve 3, the outlet of the pump outlet control valve 3 is connected to the inlet of the boiler high-temperature exhaust gas area 2, and the outlet of the boiler high-temperature exhaust gas area 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 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 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 hydrogen iodide separation tower 9 has its first outlet connected to the inlet of the sulfuric acid tank 10, and its second outlet is connected to the second inlet of the mixed liquid container 5.

[0028] The solution in the mixed liquid container 5 is a mixture of hydrogen iodide, iodine, and water. The exhaust gas temperature in the boiler's high-temperature exhaust gas area 2 is 500°C to 700°C, and a heat exchanger is provided in the boiler's high-temperature exhaust gas area 2. The mixed liquid in the mixed liquid container 5 is pressurized by the mixed liquid pump 4, and after the flow rate is adjusted by the pump outlet adjustment valve 3, it enters the heat exchanger in the boiler's high-temperature exhaust gas area 2. The mixed liquid absorbs heat in the heat exchanger in the boiler's high-temperature exhaust gas area 2, causing its temperature to rise, and then reaches the inlet of the temperature control valve 1.

[0029] The catalyst chamber 6 is filled with a catalyst that decomposes hydrogen iodide. After the high-temperature hydrogen iodide solution passes through the catalyst in the catalyst chamber, it is partially decomposed into iodine and hydrogen.

[0030] The hydrogen separation tower 7 is equipped with a cooler, and the mixed medium from the catalyst chamber 6 is cooled by the cooler in the hydrogen separation tower 7 until it reaches below 100°C. The water vapor, undecomposed hydrogen iodide, and iodine then condense into a liquid which enters the absorption tower 8, and the hydrogen enters the hydrogen tank 11.

[0031] The material replenishment device 12 replenishes sulfur dioxide, water, and iodine lost during the system cycle due to various factors. The mixture of sulfur dioxide, water, iodine from the material replenishment device 12 and the mixture returned from the hydrogen separation tower 7 undergoes a Bunsen reaction to produce hydrogen iodide and sulfuric acid. The solution of hydrogen iodide and sulfuric acid 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 tank 10.

[0032] The method for achieving the decomposition of hydrogen iodide by the thermal exhaust gas of a boiler according to the present invention is: In absorption tower 8, sulfur dioxide, water, and iodine react to produce 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 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 tank 10. The mixed liquid in the mixed liquid container 5 is pressurized by the mixed liquid pump 4, and after the flow rate is adjusted by the pump outlet adjustment valve 3, it enters the heat exchanger in the boiler's high-temperature exhaust gas area 2. The mixed liquid absorbs heat in the heat exchanger in the boiler's high-temperature exhaust gas area 2, causing its temperature to rise. When the set temperature of the temperature control valve 1 is T, if the temperature of the mixed liquid flowing out of the heat exchanger in the boiler's high-temperature exhaust gas area 2 is less than or equal to T, the mixed liquid flows in from the first outlet, enters the mixed liquid container 5, and the next cycle begins. When the temperature of the mixed liquid flowing out of the heat exchanger in the boiler's high-temperature exhaust gas area 2 is higher than T, the mixed liquid flows in from the second outlet and enters the catalyst chamber 6, where the hydrogen iodide is decomposed into hydrogen and iodine by the action of the catalyst in the catalyst chamber 6. The mixed medium discharged from the catalyst chamber 6 enters the hydrogen separation tower 7, where it is cooled to below 100°C. The water vapor, undecomposed hydrogen iodide, and iodine condense into a liquid, which enters the absorption tower 8, and the hydrogen enters the hydrogen tank 11. The mixture entering the absorption tower 8 receives sulfur dioxide, water, and iodine from the material replenishment unit 12, after which the next cycle begins. Includes.

[0033] For example, in the case of a 350MW unit, the sulfur content in the exhaust gas is 5g / m³. 3 The total exhaust gas volume is 1.3 million m³ 3 In the case of / h, theoretically it is 100,000 moles / h, 2240 m 3 It is possible to produce hydrogen at a rate of / h, and the hydrogen is 1m 3 If calculated at 10 yuan per unit, the cost is 22,000 yuan. Furthermore, it is possible to produce 100,000 moles / h and 9.8 t / h of sulfuric acid, which, if calculated at 500 yuan per ton, would cost 4,900 yuan. The decomposition of hydrogen iodide requires 17,002.6 mJ / h of heat, but this is less than 1% of the heat output of the boiler exhaust gas, resulting in a good economic effect.

[0034] Although the present invention has been described in detail above by the general description and embodiments for carrying out the invention, it will be obvious to those skilled in the art that various modifications and improvements are possible based on the present invention. Therefore, all such modifications and improvements made without departing from the spirit of the present invention are within the scope of protection of the present invention. [Explanation of symbols]

[0035] 1: Temperature control valve, 2: Boiler high-temperature exhaust gas area, 3: Pump outlet control valve, 4: Mixture pump, 5: Mixture container, 6: Catalyst chamber, 7: Hydrogen separation tower, 8: Absorption tower, 9: Hydrogen iodide separation tower, 10: Sulfuric acid tank, 11: Hydrogen tank, 12: Material replenishment device

Claims

1. A system that enables the decomposition of hydrogen iodide using the hot exhaust gas of a boiler, The system comprises a mixed liquid container (5), a mixed liquid pump (4), a pump outlet control valve (3), a boiler high-temperature exhaust gas area (2), a temperature control valve (1), a catalyst chamber (6), a hydrogen separation tower (7), a hydrogen tank (11), an absorption tower (8), a material replenishment device (12), a hydrogen iodide separation tower (9), and a sulfuric acid tank (10). The outlet of the mixed liquid container (5) is connected to the inlet of the mixed liquid pump (4), the outlet of the mixed liquid pump (4) is connected to the inlet of the pump outlet control valve (3), the outlet of the pump outlet control valve (3) is connected to the inlet of the boiler high-temperature exhaust gas area (2), and the outlet of the boiler high-temperature exhaust gas area (2) is connected to the inlet of the temperature control valve (1). The solution in the mixed liquid container (5) is a mixed solution of hydrogen iodide, iodine, and water, the exhaust gas temperature in the boiler high-temperature exhaust gas area (2) is 500°C to 700°C, and a heat exchanger is provided in the boiler high-temperature exhaust gas area (2). 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 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 supply 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), and the hydrogen iodide separation tower (9) has its first outlet connected to the inlet of the sulfuric acid tank (10) and its second outlet connected to the second inlet of the mixed liquid container (5), in a system that realizes the decomposition of hydrogen iodide by the hot exhaust gas of a boiler.

2. The system for realizing the decomposition of hydrogen iodide by the hot exhaust gas of a boiler as described in claim 1, wherein the mixed liquid in the mixed liquid container (5) is pressurized by the mixed liquid pump (4), the flow rate is adjusted by the pump outlet adjustment valve (3), and then enters the heat exchanger in the boiler's high-temperature exhaust gas area (2), where the mixed liquid absorbs heat in the heat exchanger in the boiler's high-temperature exhaust gas area (2), causing its temperature to rise, and then reaches the inlet of the temperature control valve (1).

3. A system for realizing the decomposition of hydrogen iodide by the hot exhaust gas of a boiler as described in claim 1, wherein when the set temperature of the temperature control valve (1) is T, if the temperature of the mixed liquid flowing out from the heat exchanger in the boiler's high-temperature exhaust gas area (2) is T or less, the mixed liquid flows in from the first outlet of the temperature control valve (1), and if the temperature of the mixed liquid flowing out from the heat exchanger in the boiler's high-temperature exhaust gas area (2) is higher than T, the mixed liquid flows in from the second outlet of the temperature control valve (1).

4. A system for decomposing hydrogen iodide using the hot exhaust gas of a boiler as described in claim 1, wherein a catalyst chamber (6) is filled with a catalyst for decomposing hydrogen iodide, and a high-temperature hydrogen iodide solution is partially decomposed into iodine and hydrogen after passing through the catalyst in the catalyst chamber.

5. The hydrogen separation tower (7) is equipped with a cooler. A system for decomposing hydrogen iodide using the heat exhaust gas of a boiler as described in claim 1, wherein the mixed medium from the catalyst chamber (6) is cooled by a cooler in the hydrogen separation tower (7) to a temperature of 100°C or lower, and the water vapor, undecomposed hydrogen iodide, and iodine condense into a liquid which enters the absorption tower (8), and the hydrogen enters the hydrogen tank (11).

6. A material supply device (12) replenishes sulfur dioxide, water, and iodine lost due to various factors during the system cycle; the mixture of sulfur dioxide, water, iodine from the material supply device (12) and the mixture returned from the hydrogen separation tower (7) undergoes a Bunsen reaction to produce hydrogen iodide and sulfuric acid; the solution of hydrogen iodide and sulfuric acid 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 tank (10); a system for realizing the decomposition of hydrogen iodide by the hot exhaust gas of a boiler as described in claim 1.

7. A method for achieving the decomposition of hydrogen iodide using the hot exhaust gas of a boiler, In the absorption tower (8), sulfur dioxide, water, and iodine react to produce 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 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 tank (10). The mixed liquid in the mixed liquid container (5) is pressurized by the mixed liquid pump (4), and after the flow rate is adjusted by the pump outlet adjustment valve (3), it enters the heat exchanger in the boiler's high-temperature exhaust gas area (2). The mixed liquid absorbs heat in the heat exchanger in the boiler's high-temperature exhaust gas area (2), causing its temperature to rise. When the temperature control valve (1) is set to T, if the temperature of the mixed liquid flowing out of the heat exchanger in the boiler's high-temperature exhaust gas area (2) is below T, the mixed liquid flows in from the first outlet, enters the mixed liquid container (5), and the next cycle begins. When the temperature of the mixed liquid flowing out of the heat exchanger in the boiler's high-temperature exhaust gas area (2) is higher than T, the mixed liquid flows in from the second outlet and enters the catalyst chamber (6), where the hydrogen iodide is decomposed into hydrogen and iodine by the action of the catalyst in the catalyst chamber (6). The mixed medium discharged from the catalyst chamber (6) enters the hydrogen separation tower (7), where it is cooled to below 100°C. The water vapor, undecomposed hydrogen iodide, and iodine condense into a liquid and enter the absorption tower (8), while the hydrogen enters the hydrogen tank (11). The mixture entering the absorption tower (8) receives sulfur dioxide, water, and iodine from the material replenishment unit (12), after which the next cycle begins. A method for decomposing hydrogen iodide using the hot exhaust gas of a boiler, including [the specified component].

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