System and method for obtaining hydrogen iodide by using sulfur dioxide in boiler flue gas

Abstract

Disclosed in the present invention are a system and method for obtaining hydrogen iodide by using sulfur dioxide in boiler flue gas. The system comprises a scrubbing tower, an absorption tower, an iodine interception tower, and a flue gas test and discharge device; an outlet of a flue duct downstream of a boiler booster fan is connected to a flue gas inlet of the scrubbing tower, a flue gas outlet of the scrubbing tower is connected to a flue gas inlet of the absorption tower, a flue gas outlet of the absorption tower is connected to a flue gas inlet of the iodine interception tower, and a flue gas outlet of the iodine interception tower is connected to an inlet of the flue gas test and discharge device. The method comprises: using the scrubbing tower to remove most of dust and nitrogen oxides in flue gas, so as to reduce the impact of these impurities on the absorption of sulfur dioxide by iodine; using the iodine interception tower to reduce the probability of iodine escaping from the system; and using the absorption tower to collect a slurry formed after iodine interception, thereby reducing the use of clean water and the generation of wastewater. In the present invention, flue gas is subjected to three-stage purification by means of the scrubbing tower, the absorption tower and the iodine interception tower, and thus is cleaner and more environmentally friendly.

Description

A system and method for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas. Technical Field

[0001] This invention belongs to the field of comprehensive utilization of boiler flue gas and hydrogen preparation technology, specifically relating to a system and method for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas. Background Technology

[0002] Using iodine to absorb sulfur dioxide from flue gas to obtain hydrogen iodide, which is then used to produce hydrogen, achieves waste utilization, environmental protection, and the production of green hydrogen, with good social and economic benefits. However, this method currently has the following problems:

[0003] (1) The boiler flue gas has a complex composition and carries dust and nitrogen oxides. These impurities enter the Bunsen reaction of hydrogen production in the sulfur-iodine cycle, making it difficult to purify hydrogen iodide.

[0004] (2) Iodine is a relatively volatile substance. Iodine vapor will cause pollution. At the same time, iodine has a high value, and the release of iodine vapor will increase the cost of hydrogen production. Summary of the Invention

[0005] This invention addresses the problems existing in the current method of producing hydrogen from sulfur dioxide in boiler flue gas by sulfur absorption, and provides a system and method for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas.

[0006] This invention is achieved using the following technical solution:

[0007] The present invention provides a system for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas, comprising a scrubbing tower, an absorption tower, an iodine-blocking tower, and a flue gas detection and emission device; the outlet of the flue gas duct after the boiler booster fan is connected to the flue gas inlet of the scrubbing tower, the flue gas outlet of the scrubbing tower is connected to the flue gas inlet of the absorption tower, the flue gas outlet of the absorption tower is connected to the flue gas inlet of the iodine-blocking tower, and the flue gas outlet of the iodine-blocking tower is connected to the inlet of the flue gas detection and emission device.

[0008] A further improvement of the present invention is that it also includes a clean water tank, a waste liquid tank, and a washing tower circulation pump. The first outlet of the clean water tank is connected to the slurry replenishment port of the washing tower, the second outlet of the washing tower is connected to the inlet of the waste liquid tank, the slurry circulation outlet of the washing tower is connected to the inlet of the washing tower circulation pump, and the outlet of the washing tower circulation pump is connected to the slurry circulation inlet of the washing tower.

[0009] A further improvement of the present invention is that it also includes a separator, an absorption tower circulation pump, and an iodine filling device. The outlet of the iodine filling device is connected to the iodine inlet of the absorption tower, the concentrated slurry outlet of the absorption tower is connected to the inlet of the separator, the slurry circulation outlet of the absorption tower is connected to the inlet of the absorption tower circulation pump, and the outlet of the absorption tower circulation pump is connected to the slurry circulation inlet of the absorption tower.

[0010] A further improvement of the present invention is that it also includes an iodine-blocking tower circulation pump, wherein the slurry circulation outlet of the iodine-blocking tower is connected to the inlet of the iodine-blocking tower circulation pump, and the outlet of the iodine-blocking tower circulation pump is divided into two streams, the first stream being connected to the slurry replenishment port of the iodine-blocking tower, and the second stream being connected to the slurry replenishment port of the absorption tower.

[0011] A further improvement of the present invention is that the upper part of the washing tower, the absorption tower and the iodine barrier tower are all equipped with two layers of packing material, which is a porous ball made of material that does not react with iodine, sulfur dioxide, hydrogen iodide and sulfuric acid, and the lower part is a circulating slurry pool.

[0012] A further improvement of the present invention is that, during operation, the lower circulating slurry tank maintains a liquid level that enables the circulating pumps of each tower to operate normally. The flue gas inlet and slurry replenishment port of the washing tower, absorption tower and iodine barrier tower are located between the liquid level and the lower packing. The slurry circulation port is arranged between two layers of packing and is connected to an atomizing nozzle, so that the slurry forms a mist-like droplet after passing through the atomizing nozzle and falls onto the packing layer.

[0013] A further improvement of the present invention is that the iodine inlet of the absorption tower is arranged between the liquid level of the absorption tower and the packing material at the bottom of the absorption tower.

[0014] This invention also provides a method for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas. This method is based on the aforementioned system for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas, and includes:

[0015] Before the system starts, clean water is injected into the washing tower through the clean water tank until the liquid level in the washing tower meets the level required for the normal operation of the washing tower circulation pump. Then, the washing tower circulation pump is started to establish the spray circulation of the washing tower.

[0016] Clean water is injected into the iodine-blocking tower through the clean water tank until the liquid level in the iodine-blocking tower meets the normal operating level of the iodine-blocking tower circulation pump. Then, the iodine-blocking tower circulation pump is started to establish the iodine-blocking tower spray circulation.

[0017] Clean water is injected into the absorption tower through the outlet pipe of the iodine-blocking tower circulation pump, and clean water is also injected into the iodine-blocking tower through the clean water tank. The liquid level in the iodine-blocking tower is kept at a level not lower than the normal operating level of the iodine-blocking tower circulation pump until the liquid level in the absorption tower meets the normal operating level of the absorption tower circulation pump. Then the absorption tower circulation pump is started to establish the spray circulation of the absorption tower.

[0018] Iodine is loaded into the absorption tower through an iodine filling device until the iodine dissolution reaches saturation, at which point undissolved iodine can be seen.

[0019] Flue gas is introduced into the scrubbing tower through the boiler booster fan. After passing through the spray area of ​​the scrubbing tower, a small amount of fly ash and nitrogen oxide impurities in the flue gas are washed with water and then collected in the slurry pool at the bottom of the scrubbing tower. Initially, sulfur dioxide in the flue gas also dissolves into the scrubbing liquid. As the sulfur dioxide in the scrubbing liquid reaches saturation, the sulfur dioxide content of the flue gas at the inlet and outlet of the scrubbing tower is the same. The clean flue gas containing sulfur dioxide enters the absorption tower.

[0020] In the absorption tower, sulfur dioxide in the flue gas reacts with iodine and water to produce sulfuric acid and hydrogen iodide. As the amount of hydrogen iodide dissolved in the slurry increases, the slurry's ability to dissolve iodine increases. At this time, iodine is replenished to the absorption tower in a timely manner through the iodine filling device.

[0021] The flue gas discharged from the absorption tower enters the iodine interception tower. The flue gas contains a small amount of iodine and its mixture. After these flue gas substances are sprayed and absorbed by the iodine interception tower, the iodine is intercepted, and the clean flue gas enters the flue gas detection and emission device.

[0022] When the slurry density in the absorption tower reaches the set value, the slurry in the absorption tower is discharged into the separator for the separation of sulfuric acid and hydrogen iodide. The slurry from the iodine barrier tower is then replenished to the absorption tower by the iodine barrier tower circulation pump. At the same time, clean water is added to the iodine barrier tower from the clean water tank until the normal liquid level of the iodine barrier tower is reached.

[0023] A further improvement of the present invention is that it also includes: during system operation, detecting the flue gas at the outlet of the scrubbing tower; if the nitrogen oxides and fly ash in the flue gas exceed the standards, discharging the slurry of the scrubbing tower into the waste liquid tank and replenishing the scrubbing tower with clean water.

[0024] A further improvement of the present invention is that the density of the slurry in the absorption tower is set to 2 kg / L.

[0025] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0026] This invention provides a system for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas, comprising a scrubbing tower, an absorption tower, an iodine-blocking tower, and a flue gas detection and emission device. This invention addresses the complex composition of boiler flue gas by incorporating a scrubbing tower to remove most dust and nitrogen oxides, reducing their impact on iodine absorption of sulfur dioxide. To minimize iodine escape, an iodine-blocking tower is included, reducing the likelihood of iodine escaping from the system. Simultaneously, the iodine-blocking slurry is added to the absorption tower, reducing the use of clean water and wastewater generation, thus being more environmentally friendly. Finally, the flue gas undergoes triple scrubbing through the scrubbing tower, absorption tower, and iodine-blocking tower, resulting in a cleaner and more environmentally friendly product.

[0027] Furthermore, the present invention provides a system for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas, which also includes a clean water tank, a waste liquid tank, and a washing tower circulation pump. The clean water tank can inject clean water into the washing tower and the iodine-blocking tower respectively. The waste liquid tank is used to collect the slurry discharged from the washing tower. The washing tower circulation pump can accelerate the circulation of the washing tower.

[0028] Furthermore, the present invention provides a system for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas, which also includes a separator, an absorption tower circulation pump, and an iodine filling device. The separator separates sulfuric acid and hydrogen iodide in the slurry in the absorption tower. The iodine-blocking tower circulation pump can replenish the slurry in the iodine-blocking tower to the absorption tower in a timely manner. The iodine filling device can replenish iodine to the absorption tower in a timely manner.

[0029] Furthermore, the present invention provides a system for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas, which also includes an iodine-blocking tower circulation pump. The iodine-blocking tower circulation pump can realize the spray circulation of the iodine-blocking tower on the one hand, and inject clean water into the absorption tower on the other hand.

[0030] This invention provides a method for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas. A scrubbing tower removes most dust and nitrogen oxides from the flue gas, reducing the impact of these impurities on iodine absorption of sulfur dioxide. To minimize iodine escape, an iodine-blocking tower reduces the likelihood of iodine escaping from the system. Simultaneously, the iodine-blocking slurry is added to the absorption tower, reducing the use of clean water and wastewater generation, making it more environmentally friendly. Finally, the flue gas undergoes triple scrubbing—through the scrubbing tower, absorption tower, and iodine-blocking tower—resulting in a cleaner and more environmentally friendly product. Attached Figure Description

[0031] Figure 1 is a structural block diagram of a system for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas according to the present invention.

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

[0033] 1. Boiler booster fan flue, 2. Scrubber, 3. Absorber, 4. Iodine barrier, 5. Flue gas detection and emission device, 6. Clean water tank, 7. Waste liquid tank, 8. Separator, 9. Scrubber circulation pump, 10. Absorber circulation pump, 11. Iodine barrier circulation pump, 12. Iodine filling 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] Example 1

[0036] As shown in Figure 1, the present invention provides a system for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas, comprising a boiler booster fan downstream flue 1, a scrubbing tower 2, an absorption tower 3, an iodine-blocking tower 4, and a flue gas detection and emission device 5. The outlet of the boiler booster fan downstream flue 1 is connected to the flue gas inlet of the scrubbing tower 2, the flue gas outlet of the scrubbing tower 2 is connected to the flue gas inlet of the absorption tower 3, the flue gas outlet of the absorption tower 3 is connected to the flue gas inlet of the iodine-blocking tower 4, and the flue gas outlet of the iodine-blocking tower 4 is connected to the inlet of the flue gas detection and emission device 5. The scrubbing tower 2 can wash away most of the dust and nitrogen oxides in the flue gas, reducing the impact of these impurities on the absorption of sulfur dioxide by iodine. The iodine-blocking tower 4 can reduce the probability of iodine escaping from the system. The absorption tower 3 can collect the iodine-blocking slurry, thereby reducing the use of clean water and the generation of wastewater.

[0037] Example 2

[0038] As shown in Figure 1, the present invention provides a system for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas, comprising a boiler booster fan downstream flue 1, a scrubbing tower 2, an absorption tower 3, an iodine-blocking tower 4, a flue gas detection and emission device 5, a clean water tank 6, a waste liquid tank 7, and a scrubbing tower circulation pump 9; the outlet of the boiler booster fan downstream flue 1 is connected to the flue gas inlet of the scrubbing tower 2, the flue gas outlet of the scrubbing tower 2 is connected to the flue gas inlet of the absorption tower 3, the flue gas outlet of the absorption tower 3 is connected to the flue gas inlet of the iodine-blocking tower 4, and the flue gas outlet of the iodine-blocking tower 4 is connected to the inlet of the flue gas detection and emission device 5; the first outlet of the clean water tank 6 is connected to the slurry replenishment port of the scrubbing tower 2, the second outlet of the scrubbing tower 2 is connected to the inlet of the waste liquid tank 7, the slurry circulation outlet of the scrubbing tower 2 is connected to the inlet of the scrubbing tower circulation pump 9, and the outlet of the scrubbing tower circulation pump 9 is connected to the slurry circulation inlet of the scrubbing tower 2. The clean water tank can inject clean water into the washing tower 2 and the iodine barrier tower 4 respectively, the waste liquid tank can collect the slurry discharged from the washing tower 2, and the washing tower circulation pump can accelerate the circulation of the washing tower 2.

[0039] Example 3

[0040] As shown in Figure 1, the present invention provides a system for obtaining hydrogen iodide from boiler flue gas sulfur dioxide, comprising a boiler booster fan downstream flue 1, a scrubbing tower 2, an absorption tower 3, an iodine-blocking tower 4, a flue gas detection and emission device 5, a clean water tank 6, a waste liquid tank 7, a scrubbing tower circulation pump 9, a separator 8, an absorption tower circulation pump 10, and an iodine filling device 12; the outlet of the boiler booster fan downstream flue 1 is connected to the flue gas inlet of the scrubbing tower 2, the flue gas outlet of the scrubbing tower 2 is connected to the flue gas inlet of the absorption tower 3, the flue gas outlet of the absorption tower 3 is connected to the flue gas inlet of the iodine-blocking tower 4, and the flue gas outlet of the iodine-blocking tower 4 is connected to the inlet of the flue gas detection and emission device 5; the clean water tank 6... The first outlet of the iodine filling device 12 is connected to the slurry replenishment port of the washing tower 2, the second outlet of the washing tower 2 is connected to the inlet of the waste liquid tank 7, the slurry circulation outlet of the washing tower 2 is connected to the inlet of the washing tower circulation pump 9, and the outlet of the washing tower circulation pump 9 is connected to the slurry circulation inlet of the washing tower 2. The outlet of the iodine filling device 12 is connected to the iodine addition port of the absorption tower 3, the concentrated slurry discharge outlet of the absorption tower 3 is connected to the inlet of the separator 8, the slurry circulation outlet of the absorption tower 3 is connected to the inlet of the absorption tower circulation pump 10, and the outlet of the absorption tower circulation pump 10 is connected to the slurry circulation inlet of the absorption tower 3. The separator 8 can separate sulfuric acid and hydrogen iodide from the slurry in the absorption tower 3, the iodine barrier circulation pump 11 can replenish the slurry from the iodine barrier tower 4 to the absorption tower 3 in a timely manner, and the iodine filling device 12 can replenish iodine to the absorption tower 3 in a timely manner.

[0041] Example 4

[0042] As shown in Figure 1, the present invention provides a system for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas, comprising a boiler booster fan downstream flue 1, a scrubbing tower 2, an absorption tower 3, an iodine-blocking tower 4, a flue gas detection and emission device 5, a clean water tank 6, a waste liquid tank 7, a scrubbing tower circulation pump 9, a separator 8, an absorption tower circulation pump 10, an iodine-blocking tower circulation pump 11, and an iodine filling device 12; the outlet of the boiler booster fan downstream flue 1 is connected to the flue gas inlet of the scrubbing tower 2, the flue gas outlet of the scrubbing tower 2 is connected to the flue gas inlet of the absorption tower 3, the flue gas outlet of the absorption tower 3 is connected to the flue gas inlet of the iodine-blocking tower 4, and the flue gas outlet of the iodine-blocking tower 4 is connected to the inlet of the flue gas detection and emission device 5; the first outlet of the clean water tank 6 is connected to the slurry replenishment port of the scrubbing tower 2, and the second outlet of the scrubbing tower 2 is connected to the waste liquid tank 7. The inlet of the slurry circulation outlet of the washing tower 2 is connected to the inlet of the washing tower circulation pump 9, and the outlet of the washing tower circulation pump 9 is connected to the slurry circulation inlet of the washing tower 2; the outlet of the iodine filling device 12 is connected to the iodine addition port of the absorption tower 3, the concentrated slurry discharge outlet of the absorption tower 3 is connected to the inlet of the separator 8, the slurry circulation outlet of the absorption tower 3 is connected to the inlet of the absorption tower circulation pump 10, and the outlet of the absorption tower circulation pump 10 is connected to the slurry circulation inlet of the absorption tower 3; the slurry circulation outlet of the iodine barrier tower 4 is connected to the inlet of the iodine barrier tower circulation pump 11, and the outlet of the iodine barrier tower circulation pump 11 is divided into two streams, the first stream is connected to the slurry replenishment port of the iodine barrier tower 4, and the second stream is connected to the slurry replenishment port of the absorption tower 3.

[0043] In this embodiment, the upper parts of the scrubbing tower 2, absorption tower 3, and iodine-blocking tower 4 are all equipped with two layers of packing material. The packing material is porous microspheres made of materials that do not react with iodine, sulfur dioxide, hydrogen iodide, or sulfuric acid. The lower part is a circulating slurry pool. During operation, the lower circulating slurry pool maintains a liquid level sufficient to ensure the normal operation of the circulating pumps in each tower. The flue gas inlet and slurry replenishment port of the scrubbing tower 2, absorption tower 3, and iodine-blocking tower 4 are located between the liquid level and the lower packing material. The slurry circulation port is arranged between the two layers of packing material and is connected to an atomizing nozzle, so that the slurry forms a mist-like droplet after passing through the atomizing nozzle and falls onto the packing layer. In addition, the iodine addition port of the absorption tower 3 is arranged between the liquid level of the absorption tower 3 and the lower packing material of the absorption tower 3.

[0044] Example 5

[0045] This invention provides a method for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas. This method is based on a system for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas, as shown in Figure 1. The system includes a boiler booster fan downstream flue 1, a scrubbing tower 2, an absorption tower 3, an iodine-blocking tower 4, a flue gas detection and emission device 5, a clean water tank 6, a waste liquid tank 7, a scrubbing tower circulation pump 9, a separator 8, an absorption tower circulation pump 10, an iodine-blocking tower circulation pump 11, and an iodine filling device 12. The outlet of the boiler booster fan downstream flue 1 is connected to the flue gas inlet of the scrubbing tower 2, the flue gas outlet of the scrubbing tower 2 is connected to the flue gas inlet of the absorption tower 3, the flue gas outlet of the absorption tower 3 is connected to the flue gas inlet of the iodine-blocking tower 4, and the flue gas outlet of the iodine-blocking tower 4 is connected to the inlet of the flue gas detection and emission device 5. The clean water tank 6... The first outlet of the iodine-filling device 12 is connected to the iodine-adding port of the absorption tower 3. The concentrated slurry discharge port of the absorption tower 3 is connected to the inlet of the separator 8. The slurry circulation outlet of the absorption tower 3 is connected to the inlet of the absorption tower circulation pump 10. The outlet of the absorption tower circulation pump 10 is connected to the slurry circulation inlet of the absorption tower 3. The slurry circulation outlet of the iodine-blocking tower 4 is connected to the inlet of the iodine-blocking tower circulation pump 11. The outlet of the iodine-blocking tower circulation pump 11 is divided into two streams. The first stream is connected to the slurry replenishment port of the iodine-blocking tower 4, and the second stream is connected to the slurry replenishment port of the absorption tower 3.

[0046] The method includes:

[0047] Before the system is started, clean water is injected into the washing tower 2 through the clean water tank 6 until the liquid level of the washing tower 2 meets the normal operating level of the washing tower circulation pump 9. Then the washing tower circulation pump 9 is started to establish the spray circulation of the washing tower 2.

[0048] Clean water is injected into the iodine-blocking tower 4 through the clean water tank 6 until the liquid level of the iodine-blocking tower 4 meets the normal operating level of the iodine-blocking tower circulation pump 11. Then, the iodine-blocking tower circulation pump 11 is started to establish the spray circulation of the iodine-blocking tower 4.

[0049] Clean water is injected into the absorption tower 3 through the outlet pipe of the iodine-blocking tower circulation pump 11, and clean water is injected into the iodine-blocking tower 4 through the clean water tank 6. The liquid level of the iodine-blocking tower 4 is kept at a level not lower than the normal operating level of the iodine-blocking tower circulation pump 11 until the liquid level of the absorption tower 3 meets the normal operating level of the absorption tower circulation pump 10. Then the absorption tower circulation pump 10 is started to establish the spray circulation of the absorption tower 3.

[0050] Iodine is loaded into the absorption tower 3 through the iodine filling device 12 until the iodine dissolution reaches saturation, at which point undissolved iodine can be seen.

[0051] Flue gas is introduced into scrubbing tower 2 through flue 1 after the boiler booster fan. After passing through the spray area of ​​scrubbing tower 2, a small amount of fly ash and nitrogen oxide impurities in the flue gas are washed with water and then collected in the slurry pool at the bottom of scrubbing tower 2. Initially, sulfur dioxide in the flue gas also dissolves into the scrubbing liquid. As the sulfur dioxide in the scrubbing liquid reaches saturation, the sulfur dioxide content of the flue gas at the inlet and outlet of scrubbing tower 2 is the same. The clean flue gas containing sulfur dioxide enters the absorption tower 3.

[0052] In the absorption tower 3, sulfur dioxide in the flue gas reacts with iodine and water to produce sulfuric acid and hydrogen iodide. As the amount of hydrogen iodide dissolved in the slurry increases, the slurry’s ability to dissolve iodine is enhanced. At this time, iodine is promptly added to the absorption tower 3 through the iodine filling device 12.

[0053] The flue gas discharged from the absorption tower 3 enters the iodine-blocking tower 4. The flue gas contains a small amount of iodine and its mixture. After these flue gas substances are sprayed and absorbed by the iodine-blocking tower 4, the iodine is blocked, and the clean flue gas enters the flue gas detection and emission device 5.

[0054] When the slurry density in the absorption tower 3 reaches 2 kg / L or higher, the slurry in the absorption tower 3 is discharged into the separator 8 for the separation of sulfuric acid and hydrogen iodide. The slurry in the iodine barrier tower 4 is then replenished to the absorption tower 3 by the iodine barrier tower circulation pump 11. At the same time, clean water is added to the iodine barrier tower 4 from the clean water tank 6 until the normal liquid level of the iodine barrier tower 4 is reached.

[0055] In this embodiment, the system also includes: during system operation, detecting the flue gas at the outlet of the scrubbing tower 2; if the nitrogen oxides and fly ash in the flue gas exceed the standards, discharging the slurry of the scrubbing tower 2 into the waste liquid tank 7 and replenishing the scrubbing tower 2 with clean water.

[0056] Example 6

[0057] In this embodiment, a 350MW thermal power unit contains 5g of sulfur dioxide and 30mg of dust per cubic meter of flue gas, with a total flue gas volume of 1.3 million cubic meters. 3 / h.

[0058] After the flue gas passes through scrubbing tower 2, the sulfur dioxide and dust in the flue gas are absorbed by the scrubbing water. Once the water in scrubbing tower 2 reaches saturation with sulfur dioxide, the sulfur dioxide enters absorption tower 3. If the slurry in scrubbing tower 2 becomes viscous, affecting the dust washing effect or the normal operation of the scrubbing tower circulation pump 9, the slurry in scrubbing tower 2 will be replaced.

[0059] In absorption tower 3, sulfur dioxide reacts with iodine and water to produce hydrogen iodide. Hydrogen is then produced from the hydrogen iodide. Theoretically, a 350MW thermal power unit at full load can produce 100,000 mol / h of hydrogen and 2240 m³ of hydrogen from sulfur dioxide in its flue gas. 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.

[0060] The flue gas exiting the absorption tower 3 enters the iodine-blocking tower 4, where the trace amounts of iodine, hydrogen iodide, and sulfuric acid it carries are absorbed by the liquid in the iodine-blocking tower 4, and the flue gas discharged from the iodine-blocking tower 4 is clean flue gas.

[0061] 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 obtaining hydrogen iodide using boiler flue gas sulfur dioxide, characterized by, It includes a scrubbing tower (2), an absorption tower (3), an iodine-blocking tower (4), a flue gas detection and emission device (5), a clean water tank (6), a waste liquid tank (7), a scrubbing tower circulation pump (9), a stratifier (8), an absorption tower circulation pump (10), an iodine filling device (12), and an iodine-blocking tower circulation pump (11). The outlet of the flue (1) after the boiler booster fan is connected to the flue gas inlet of the scrubbing tower (2), the flue gas outlet of the scrubbing tower (2) is connected to the flue gas inlet of the absorption tower (3), the flue gas outlet of the absorption tower (3) is connected to the flue gas inlet of the iodine barrier tower (4), and the flue gas outlet of the iodine barrier tower (4) is connected to the inlet of the flue gas detection and emission device (5). The first outlet of the clean water tank (6) is connected to the slurry replenishment port of the washing tower (2), the second outlet of the washing tower (2) is connected to the inlet of the waste liquid tank (7), the slurry circulation outlet of the washing tower (2) is connected to the inlet of the washing tower circulation pump (9), and the outlet of the washing tower circulation pump (9) is connected to the slurry circulation inlet of the washing tower (2). The outlet of the iodine filling device (12) is connected to the iodine inlet of the absorption tower (3), the slurry outlet of the absorption tower (3) is connected to the inlet of the separator (8), the slurry circulation outlet of the absorption tower (3) is connected to the inlet of the absorption tower circulation pump (10), and the outlet of the absorption tower circulation pump (10) is connected to the slurry circulation inlet of the absorption tower (3). The slurry circulation outlet of the iodine barrier tower (4) is connected to the inlet of the iodine barrier tower circulation pump (11). The outlet of the iodine barrier tower circulation pump (11) is divided into two streams. The first stream is connected to the slurry replenishment port of the iodine barrier tower (4), and the second stream is connected to the slurry replenishment port of the absorption tower (3).

2. A system for obtaining hydrogen iodide from sulfur dioxide of boiler flue gas according to claim 1, characterized in that, The upper part of the washing tower (2), the absorption tower (3) and the iodine barrier tower (4) are all filled with two layers of packing. The packing is made of porous small balls that do not react with iodine, sulfur dioxide, hydrogen iodide and sulfuric acid. The lower part is a circulating slurry pool.

3. A system for obtaining hydrogen iodide from sulfur dioxide of boiler flue gas according to claim 2, characterized in that, During operation, the lower circulating slurry pool maintains a liquid level that enables the circulating pumps of each tower to operate normally. The flue gas inlet and slurry replenishment port of the washing tower (2), absorption tower (3) and iodine barrier tower (4) are located between the liquid level and the lower packing. The slurry circulation port is arranged between the two layers of packing. The slurry circulation port is connected to an atomizing nozzle, so that the slurry forms a mist-like droplet after passing through the atomizing nozzle and falls onto the packing layer.

4. A system for obtaining hydrogen iodide from sulfur dioxide of boiler flue gas according to claim 2, characterized in that, The iodine inlet of the absorption tower (3) is located between the liquid level of the absorption tower (3) and the packing material at the bottom of the absorption tower (3).

5. A method for obtaining hydrogen iodide using boiler flue gas sulfur dioxide, characterized by, This method is based on the system for obtaining hydrogen iodide from sulfur dioxide in boiler flue gas as described in claim 1, comprising: Before the system is started, clean water is injected into the washing tower (2) through the clean water tank (6) until the liquid level of the washing tower (2) meets the liquid level required for the normal operation of the washing tower circulation pump (9). Then the washing tower circulation pump (9) is started to establish the spray circulation of the washing tower (2). Water is injected into the iodine barrier tower (4) through the water tank (6) until the liquid level of the iodine barrier tower (4) meets the normal operating liquid level of the iodine barrier tower circulation pump (11). The iodine barrier tower circulation pump (11) is started to establish the spray circulation of the iodine barrier tower (4). Through the iodine tower circulating pump (11) outlet pipeline to the injection of clean water to the absorption tower (3), while through the clean water tank (6) to the injection of clean water to the iodine tower (4), and keep the liquid level of the iodine tower (4) is not lower than the normal operation of the iodine tower circulating pump (11) liquid level, until the absorption tower (3) liquid level meets the normal operation of the absorption tower circulating pump (10), start the absorption tower circulating pump (10), establish the spray circulation of the absorption tower (3); Through the iodine filling device (12) to the absorption tower (3) loaded with iodine, until the dissolution of iodine reaches saturation, that is, there is no dissolved iodine; Through the boiler booster fan after flue (1) to the washing tower (2) into the flue gas, after the flue gas through the spray area of the washing tower (2), a small amount of fly ash, nitrogen oxides impurities in the flue gas are washed by water and gathered in the slurry pool at the lower part of the washing tower (2), the initial sulfur dioxide in the flue gas also dissolves into the washing liquid, as the sulfur dioxide in the washing liquid reaches saturation, the sulfur dioxide content of the flue gas at the inlet and outlet of the washing tower (2) is the same, the clean flue gas containing sulfur dioxide enters the absorption tower (3); In the absorption tower (3), the sulfur dioxide in the flue gas reacts with iodine and water to generate sulfuric acid and hydrogen iodide, as the dissolved hydrogen iodide in the slurry increases, the ability of the slurry to dissolve iodine increases, at this time, iodine is supplemented to the absorption tower (3) through the iodine filling device (12) in time; The flue gas discharged from the absorption tower (3) enters the iodine blocking tower (4), the flue gas contains a small amount of iodine and its mixture, after the flue gas carrying is absorbed by the spray of the iodine blocking tower (4), the iodine is intercepted, and the clean flue gas enters the flue gas detection and discharge device (5); The slurry density in the absorption tower (3) reaches the set value, the slurry in the absorption tower (3) is discharged into the layering device (8) for separation of sulfuric acid and hydrogen iodide, the slurry in the iodine blocking tower (4) is supplemented to the absorption tower (3) through the iodine blocking tower circulating pump (11), and clean water is supplemented from the clean water tank (6) to the iodine blocking tower (4) to the normal liquid level of the iodine blocking tower (4).

6. A method of obtaining hydrogen iodide from the sulfur dioxide of boiler flue gas according to claim 5, characterized in that, Also includes: During system operation, the outlet flue gas of the washing tower (2) is detected, if the nitrogen oxides and fly ash of the flue gas exceed the standard, the slurry of the washing tower (2) is discharged into the waste liquid tank (7), and clean water is supplemented to the washing tower (2).

7. A method of obtaining hydrogen iodide from sulfur dioxide of boiler flue gas according to claim 5, characterized in that, The set value of the slurry density in the absorption tower (3) is 2Kg / L.

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