A system and method for obtaining hydrogen iodide using sulfur dioxide from boiler flue gas

Abstract

The invention discloses a system and method for obtaining hydrogen iodide by using sulfur dioxide in boiler flue gas, the system comprising a scrubbing tower, an absorption tower, an iodine intercepting tower and a flue gas detection and emission device; the outlet of the flue 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 intercepting tower, and the flue gas outlet of the iodine intercepting tower is connected to the inlet of the flue gas detection and emission device; the method comprises: most dust and nitrogen oxides in the flue gas can be washed by the scrubbing tower, reducing the influence of these impurities on the absorption of sulfur dioxide by iodine, the iodine intercepting tower can reduce the probability of iodine escaping out of the system; the absorption tower can collect the iodine intercepting slurry, thereby reducing the use of clean water and the generation of waste water. In the present invention, the flue gas is triple-washed by the scrubbing tower, the absorption tower and the iodine intercepting tower, which is cleaner and more environmentally friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive utilization of boiler flue gas and hydrogen preparation, and specifically relates to a system and method for obtaining hydrogen iodide by utilizing sulfur dioxide in boiler flue gas. Background Art

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

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

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

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

[0006] The present invention is achieved by adopting the following technical solutions:

[0007] The present invention provides a system for obtaining hydrogen iodide by utilizing sulfur dioxide in boiler flue gas, comprising a scrubbing tower, an absorption tower, an iodine intercepting tower and a flue gas detection and emission device; the outlet of the flue 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 intercepting tower, and the flue gas outlet of the iodine intercepting 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 stratifier, an absorption tower circulation pump and an iodine filling device, the outlet of the iodine filling device is connected to the iodine addition port of the absorption tower, the concentrated slurry discharge port of the absorption tower is connected to the inlet of the stratifier, 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 intercepting tower circulation pump, the slurry circulation outlet of the iodine intercepting tower is connected to the inlet of the iodine intercepting tower circulation pump, and the outlet of the iodine intercepting tower circulation pump is divided into two streams, the first stream is connected to the slurry replenishment port of the iodine intercepting tower, and the second stream is connected to the slurry replenishment port of the absorption tower.

[0011] A further improvement of the present invention is that the upper parts of the washing tower, the absorption tower and the iodine intercepting tower are all equipped with two layers of fillers, which are porous balls made of materials that do 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 pool maintains a liquid level that enables the circulation pumps of each tower to operate normally, the flue gas inlet and slurry replenishment port of the washing tower, absorption tower and iodine interception tower are between the liquid level and the lower filler, the slurry circulation port is arranged between two layers of filler, and the slurry circulation port is connected to an atomizing nozzle so that the slurry forms mist droplets on the filler layer after passing through the atomizing nozzle.

[0013] A further improvement of the present invention is that the iodine addition port of the absorption tower is arranged above the liquid level of the absorption tower and between the lower filler of the absorption tower.

[0014] The present invention also provides a method for obtaining hydrogen iodide by using sulfur dioxide in boiler flue gas. The method is based on the system for obtaining hydrogen iodide by using sulfur dioxide in boiler flue gas, and comprises:

[0015] Before starting the system, inject clean water into the scrubber through the clean water tank until the liquid level in the scrubber meets the normal operating level of the scrubber circulation pump, start the scrubber circulation pump, and establish the scrubber spray cycle;

[0016] Inject clean water into the iodine intercepting tower through the clean water tank until the liquid level of the iodine intercepting tower meets the normal operating liquid level of the iodine intercepting tower circulation pump, start the iodine intercepting tower circulation pump, and establish the iodine intercepting tower spraying cycle;

[0017] Inject clean water into the absorption tower through the outlet pipe of the iodine intercepting tower circulation pump, and inject clean water into the iodine intercepting tower through the clean water tank at the same time, and keep the liquid level of the iodine intercepting tower not lower than the normal operating liquid level of the iodine intercepting tower circulation pump, until the liquid level of the absorption tower meets the normal operation of the absorption tower circulation pump, start the absorption tower circulation pump, and establish the spray circulation of the absorption tower;

[0018] Iodine is added to the absorption tower through an iodine filling device until the iodine dissolution reaches saturation, i.e., undissolved iodine can be seen;

[0019] The flue gas is introduced into the scrubber through the flue after the boiler booster fan. After the flue gas passes through the spray area of ​​the scrubber, a small amount of fly ash and nitrogen oxide impurities in the flue gas are washed with water and gathered in the slurry pool at the bottom of the scrubber. The sulfur dioxide in the flue gas is also dissolved in the scrubbing liquid. As the sulfur dioxide in the scrubbing liquid reaches saturation, the sulfur dioxide content of the inlet and outlet flue gas of the scrubber is the same, and 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 generate 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 promptly added to the absorption tower 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 the flue gas is 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 density of the slurry in the absorption tower reaches above the set value, the slurry in the absorption tower is discharged into the classifier to separate the sulfuric acid and hydrogen iodide. The slurry in the iodine interception tower is replenished into the absorption tower through the iodine interception tower circulation pump. At the same time, clean water is replenished from the clean water tank to the iodine interception tower to the normal liquid level of the iodine interception tower.

[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 washing tower, if the nitrogen oxides and fly ash in the flue gas exceed the standard, discharging the slurry of the washing tower into the waste liquid tank, and replenishing clean water to the washing tower.

[0024] A further improvement of the present invention is that the slurry density 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] The present invention provides a system for obtaining hydrogen iodide by utilizing sulfur dioxide in boiler flue gas, comprising a washing tower, an absorption tower, an iodine intercepting tower and a flue gas detection and emission device. The present invention aims at the complex composition of boiler flue gas. By setting a washing tower, most dust and nitrogen oxides in the flue gas can be washed, and the influence of these impurities on the absorption of sulfur dioxide by iodine can be reduced. In order to reduce iodine escape, the present invention sets an iodine intercepting tower, which reduces the probability of iodine escaping out of the system. At the same time, the iodine intercepting slurry is supplemented into the absorption tower, which reduces the use of clean water and the generation of wastewater, and is more environmentally friendly. Finally, the flue gas is triple washed by the washing tower, the absorption tower and the iodine intercepting tower, and is cleaner and more environmentally friendly.

[0027] Furthermore, the present invention provides a system for obtaining hydrogen iodide by utilizing sulfur dioxide in boiler flue gas, which also includes a clean water tank, a waste liquid tank and a washing tower circulation pump. Clean water can be respectively injected into the washing tower and the iodine intercepting tower through the clean water tank. The waste liquid tank is used to collect 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 by utilizing sulfur dioxide in boiler flue gas, which also includes a stratifier, an absorption tower circulation pump and an iodine filling device. The stratifier is used to separate sulfuric acid and hydrogen iodide from the slurry in the absorption tower. The iodine interception tower circulation pump can replenish the slurry in the iodine interception tower to the absorption tower in time, and the iodine filling device can replenish iodine to the absorption tower in time.

[0029] Furthermore, the system for obtaining hydrogen iodide by utilizing sulfur dioxide in boiler flue gas provided by the present invention also includes an iodine intercepting tower circulation pump, through which the iodine intercepting tower can be sprayed and circulated on the one hand, and clean water can be injected into the absorption tower on the other hand.

[0030] The present invention provides a method for obtaining hydrogen iodide by utilizing sulfur dioxide in boiler flue gas. Most dust and nitrogen oxides in the flue gas can be washed by a washing tower, thereby reducing the influence of these impurities on the absorption of sulfur dioxide by iodine. In order to reduce iodine escape, the present invention reduces the probability of iodine escaping out of the system by an iodine intercepting tower. At the same time, the iodine intercepting slurry is supplemented into the absorption tower, thereby reducing the use of clean water and the generation of wastewater, and being more environmentally friendly. Finally, the flue gas is triple-washed by the washing tower, the absorption tower and the iodine intercepting tower, thereby being cleaner and more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a structural block diagram of a system for obtaining hydrogen iodide by utilizing sulfur dioxide in boiler flue gas.

[0032] Description of reference numerals:

[0033] 1. Flue duct after boiler booster fan, 2. Scrubber, 3. Absorption tower, 4. Iodine intercepting tower, 5. Flue gas detection and emission device, 6. Clean water tank, 7. Waste liquid tank, 8. Stratifier, 9. Scrubber circulating pump, 10. Absorption tower circulating pump, 11. Iodine intercepting tower circulating pump, 12. Iodine filling device. DETAILED DESCRIPTION

[0034] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to be able to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] Example 1

[0036] like Figure 1 As shown, the system for obtaining hydrogen iodide by using sulfur dioxide in boiler flue gas provided by the present invention comprises a flue duct 1 after a boiler booster fan, a washing tower 2, an absorption tower 3, an iodine intercepting tower 4 and a flue gas detection and emission device 5; the outlet of the flue duct 1 after the boiler booster fan is connected to the flue gas inlet of the washing tower 2, the flue gas outlet of the washing 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 intercepting tower 4, and the flue gas outlet of the iodine intercepting tower 4 is connected to the inlet of the flue gas detection and emission device 5. The washing tower 2 can wash most of the dust and nitrogen oxides in the flue gas, reducing the influence of these impurities on the absorption of sulfur dioxide by iodine, and the iodine intercepting tower 4 can reduce the probability of iodine escaping from the system; the absorption tower 3 can collect the iodine intercepting slurry, thereby reducing the use of clean water and the generation of wastewater.

[0037] Example 2

[0038] like Figure 1 As shown, a system for obtaining hydrogen iodide by utilizing sulfur dioxide in boiler flue gas provided by the present invention comprises a flue 1 after a boiler booster fan, a washing tower 2, an absorption tower 3, an iodine intercepting tower 4, a flue gas detection and emission device 5, a clean water tank 6, a waste liquid tank 7 and a washing tower circulation pump 9; the outlet of the flue 1 after the boiler booster fan is connected to the flue gas inlet of the washing tower 2, the flue gas outlet of the washing 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 intercepting tower 4, and the flue gas outlet of the iodine intercepting 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 clean water tank can inject clean water into the washing tower 2 and the iodine intercepting 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] like Figure 1As shown, the present invention provides a system for obtaining hydrogen iodide by utilizing sulfur dioxide in boiler flue gas, comprising a flue duct 1 after a boiler booster fan, a washing tower 2, an absorption tower 3, an iodine intercepting tower 4, a flue gas detection and emission device 5, a clean water tank 6, a waste liquid tank 7, a washing tower circulation pump 9, a stratifier 8, an absorption tower circulation pump 10 and an iodine filling device 12; the outlet of the flue duct 1 after the boiler booster fan is connected to the flue gas inlet of the washing tower 2, the flue gas outlet of the washing 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 intercepting tower 4, the flue gas outlet of the iodine intercepting tower 4 is connected to the flue gas detection and emission device 5, the clean water tank 6, the waste liquid tank 7, the washing tower circulation pump 9, the stratifier 8, the absorption tower circulation pump 10 and the ... 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 addition port of the absorption tower 3, the concentrated slurry discharge port of the absorption tower 3 is connected to the inlet of the stratifier 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 stratifier 8 can realize the separation of sulfuric acid and hydrogen iodide in the slurry in the absorption tower 3, the iodine intercepting tower circulation pump 11 can timely replenish the slurry of the iodine intercepting tower 4 into the absorption tower 3, and the iodine filling device 12 can timely replenish iodine into the absorption tower 3.

[0041] Example 4

[0042] like Figure 1 As shown, the present invention provides a system for obtaining hydrogen iodide by utilizing sulfur dioxide in boiler flue gas, comprising a flue duct 1 after a boiler booster fan, a washing tower 2, an absorption tower 3, an iodine intercepting tower 4, a flue gas detection and emission device 5, a clean water tank 6, a waste liquid tank 7, a washing tower circulation pump 9, a stratifier 8, an absorption tower circulation pump 10, an iodine intercepting tower circulation pump 11 and an iodine filling device 12; the outlet of the flue duct 1 after the boiler booster fan is connected to the flue gas inlet of the washing tower 2, the flue gas outlet of the washing 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 intercepting tower 4, and the flue gas outlet of the iodine intercepting 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 replenishing 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 port of the absorption tower 3 is connected to the inlet of the stratifier 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 intercepting tower 4 is connected to the inlet of the iodine intercepting tower circulation pump 11, and the outlet of the iodine intercepting tower circulation pump 11 is divided into two branches, the first branch is connected to the slurry replenishment port of the iodine intercepting tower 4, and the second branch is connected to the slurry replenishment port of the absorption tower 3.

[0043] In this embodiment, the upper part of the washing tower 2, the absorption tower 3 and the iodine intercepting tower 4 are equipped with two layers of fillers, the fillers are porous balls made of materials that do not react with iodine, sulfur dioxide, hydrogen iodide and sulfuric acid, and the lower part is a circulating slurry pool. During operation, the lower circulating slurry pool maintains a liquid level that enables the normal operation of the circulating pumps of each tower, the flue gas inlet and the slurry replenishment port of the washing tower 2, the absorption tower 3 and the iodine intercepting tower 4 are between the liquid level and the lower filler, the slurry circulation port is arranged between the two layers of fillers, and the slurry circulation port is connected to the atomizing nozzle, so that the slurry forms a mist drop on the filler layer after passing through the atomizing nozzle. 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 filler of the absorption tower 3.

[0044] Example 5

[0045] The present invention provides a method for obtaining hydrogen iodide by using sulfur dioxide in boiler flue gas. The method is based on the system for obtaining hydrogen iodide by using sulfur dioxide in boiler flue gas. Figure 1 As shown, the system comprises a flue 1 after a boiler booster fan, a washing tower 2, an absorption tower 3, an iodine intercepting tower 4, a smoke detection and emission device 5, a clean water tank 6, a waste liquid tank 7, a washing tower circulation pump 9, a stratifier 8, an absorption tower circulation pump 10, an iodine intercepting tower circulation pump 11 and an iodine filling device 12; the outlet of the flue 1 after the boiler booster fan is connected to the smoke inlet of the washing tower 2, the smoke outlet of the washing tower 2 is connected to the smoke inlet of the absorption tower 3, the smoke outlet of the absorption tower 3 is connected to the smoke inlet of the iodine intercepting tower 4, and the smoke outlet of the iodine intercepting tower 4 is connected to the inlet of the smoke detection and emission device 5; the first outlet of the clean water tank 6 is connected to the slurry replenishing port of the washing tower 2, and the second outlet of the washing tower 2 is connected to the waste liquid tank 7; The inlet of the liquid tank 7 and the slurry circulation outlet of the washing tower 2 are 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 port of the absorption tower 3 is connected to the inlet of the classifier 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 intercepting tower 4 is connected to the inlet of the iodine intercepting tower circulation pump 11, and the outlet of the iodine intercepting tower circulation pump 11 is divided into two branches, the first branch is connected to the slurry replenishment port of the iodine intercepting tower 4, and the second branch 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 liquid level of the normal operation of the washing tower circulation pump 9, and the washing tower circulation pump 9 is started to establish the spray circulation of the washing tower 2;

[0048] Inject clean water into the iodine intercepting tower 4 through the clean water tank 6 until the liquid level of the iodine intercepting tower 4 meets the normal operating liquid level of the iodine intercepting tower circulation pump 11, start the iodine intercepting tower circulation pump 11, and establish the iodine intercepting tower 4 spray cycle;

[0049] Clean water is injected into the absorption tower 3 through the outlet pipe of the iodine intercepting tower circulation pump 11, and clean water is injected into the iodine intercepting tower 4 through the clean water tank 6, and the liquid level of the iodine intercepting tower 4 is kept not lower than the normal operating liquid level of the iodine intercepting tower circulation pump 11, until the liquid level of the absorption tower 3 meets the normal operation of the absorption tower circulation pump 10, the absorption tower circulation pump 10 is started, and the spray circulation of the absorption tower 3 is established;

[0050] Iodine is charged into the absorption tower 3 through the iodine filling device 12 until the iodine dissolution reaches saturation, that is, undissolved iodine can be seen;

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

[0052] 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 amount of hydrogen iodide dissolved in the slurry increases, the iodine dissolving capacity of the slurry increases. 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 intercepting tower 4. The flue gas contains a small amount of iodine and its mixture. After the flue gas is sprayed and absorbed by the iodine intercepting tower 4, the iodine is intercepted and the clean flue gas enters the flue gas detection and emission device 5.

[0054] The density of the slurry in the absorption tower 3 reaches more than 2Kg / L, and the slurry in the absorption tower 3 is discharged into the classifier 8 to separate the sulfuric acid and hydrogen iodide. The slurry in the iodine interception tower 4 is supplemented into the absorption tower 3 through the iodine interception tower circulation pump 11, and at the same time, clean water is supplemented from the clean water tank 6 to the iodine interception tower 4 to the normal liquid level of the iodine interception tower 4.

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

[0056] Embodiment 6:

[0057] In this example, a 350MW thermal power unit contains 5g of sulfur dioxide and 30mg of dust per cubic meter of flue gas, and the total amount of flue gas is 1.3 million m 3 / h.

[0058] After the flue gas passes through the scrubber 2, sulfur dioxide and dust in the flue gas are absorbed by the scrubbing water. After the water in the scrubber 2 reaches saturation with sulfur dioxide, sulfur dioxide enters the absorption tower 3. When the slurry in the scrubber 2 is viscous and affects the scrubbing effect on the dust or the normal operation of the scrubber circulating pump 9, the slurry in the scrubber 2 is replaced.

[0059] In the absorption tower 3, sulfur dioxide reacts with iodine and water to generate hydrogen iodide. Then hydrogen is produced from hydrogen iodide. Theoretically, for a 350MW thermal power unit, at full load, sulfur dioxide in the flue gas can produce 100,000 mol hydrogen / h and 2240m 3 Hydrogen / h, 1m 3 Hydrogen is worth 22,000 yuan at 10 yuan per tonne. It can be used to produce 100,000 mol / h and 9.8 t / h of sulfuric acid. One ton of sulfuric acid is worth 4,900 yuan at 500 yuan per tonne. The heat required to decompose hydrogen iodide is 17002.6 mj / h, which accounts for less than 1% of the heat of boiler flue gas and has good economic benefits.

[0060] The flue gas coming out of the absorption tower 3 enters the iodine intercepting tower 4, and the trace iodine, hydrogen iodide and sulfuric acid carried by the flue gas are absorbed by the liquid in the iodine intercepting tower 4, and the flue gas discharged from the iodine intercepting tower 4 is clean flue gas.

[0061] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A system for obtaining hydrogen iodide using sulfur dioxide from boiler flue gas, characterized in that: It comprises a washing tower (2), an absorption tower (3), an iodine intercepting tower (4), a smoke detection and emission device (5), a clean water tank (6), a waste liquid tank (7), a washing tower circulation pump (9), a stratifier (8), an absorption tower circulation pump (10), an iodine filling device (12) and an iodine intercepting tower circulation pump (11); The outlet of the flue (1) after the boiler booster fan is connected to the flue gas inlet of the washing tower (2), the flue gas outlet of the washing 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 intercepting tower (4), and the flue gas outlet of the iodine intercepting 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 replenishing 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 adding port of the absorption tower (3), the concentrated slurry discharge port of the absorption tower (3) is connected to the inlet of the classifier (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 intercepting tower (4) is connected to the inlet of the iodine intercepting tower circulation pump (11), and the outlet of the iodine intercepting tower circulation pump (11) is divided into two streams, the first stream is connected to the slurry replenishing port of the iodine intercepting tower (4), and the second stream is connected to the slurry replenishing port of the absorption tower (3).

2. A system for obtaining hydrogen iodide by utilizing sulfur dioxide from boiler flue gas according to claim 1, characterized in that: The washing tower (2), the absorption tower (3) and the iodine intercepting tower (4) are all equipped with two layers of fillers on the top, wherein the fillers are porous balls made of materials that do not react with iodine, sulfur dioxide, hydrogen iodide and sulfuric acid, and the bottom is a circulating slurry pool.

3. A system for obtaining hydrogen iodide by utilizing sulfur dioxide from 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), the absorption tower (3) and the iodine interception tower (4) are located between the liquid level and the lower filler. The slurry circulation port is arranged between two layers of filler. The slurry circulation port is connected to an atomizing nozzle so that the slurry forms mist droplets on the filler layer after passing through the atomizing nozzle.

4. A system for obtaining hydrogen iodide by utilizing sulfur dioxide from boiler flue gas according to claim 2, characterized in that: The iodine addition port of the absorption tower (3) is arranged above the liquid level of the absorption tower (3) and between the lower fillers of the absorption tower (3).

5. A method for obtaining hydrogen iodide using sulfur dioxide from boiler flue gas, characterized in that: The method is based on the system for obtaining hydrogen iodide by utilizing 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 of the normal operation of the washing tower circulation pump (9), and the washing tower circulation pump (9) is started to establish the spray circulation of the washing tower (2); Inject clean water into the iodine intercepting tower (4) through the clean water tank (6) until the liquid level of the iodine intercepting tower (4) meets the normal operating liquid level of the iodine intercepting tower circulation pump (11), start the iodine intercepting tower circulation pump (11), and establish the iodine intercepting tower (4) spraying cycle; Clean water is injected into the absorption tower (3) through the outlet pipe of the iodine intercepting tower circulation pump (11), and clean water is injected into the iodine intercepting tower (4) through the clean water tank (6), and the liquid level of the iodine intercepting tower (4) is maintained not lower than the normal operating liquid level of the iodine intercepting tower circulation pump (11), until the liquid level of the absorption tower (3) satisfies the normal operation of the absorption tower circulation pump (10), the absorption tower circulation pump (10) is started, and the spray circulation of the absorption tower (3) is established; Iodine is charged into the absorption tower (3) through the iodine filling device (12) until the iodine dissolution reaches saturation, that is, undissolved iodine can be seen; Flue gas is introduced into the scrubbing tower (2) through the flue duct (1) after the boiler booster fan. After the flue gas passes through the spraying area of ​​the scrubbing tower (2), a small amount of fly ash and nitrogen oxide impurities in the flue gas are washed with water and then gathered in the slurry pool at the bottom of the scrubbing tower (2). The sulfur dioxide in the flue gas is also initially dissolved in 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 (2) becomes the same, and the clean flue gas containing sulfur dioxide enters the absorption tower (3); In the absorption tower (3), sulfur dioxide in the flue gas reacts with iodine and water to generate sulfuric acid and hydrogen iodide. As the amount of hydrogen iodide dissolved in the slurry increases, the iodine dissolving capacity of the slurry increases. At this time, iodine is promptly added to the absorption tower (3) through the iodine filling device (12); The flue gas discharged from the absorption tower (3) enters the iodine intercepting tower (4). The flue gas contains a small amount of iodine and its mixture. After the flue gas is sprayed and absorbed by the iodine intercepting tower (4), the iodine is intercepted and the clean flue gas enters the flue gas detection and emission device (5). When the density of the slurry in the absorption tower (3) reaches a set value or above, the slurry in the absorption tower (3) is discharged into the classifier (8) to separate the sulfuric acid and hydrogen iodide, and the slurry in the iodine interception tower (4) is replenished into the absorption tower (3) through the iodine interception tower circulation pump (11), and at the same time, clean water is replenished from the clean water tank (6) to the iodine interception tower (4) to the normal liquid level of the iodine interception tower (4).

6. The method for obtaining hydrogen iodide by utilizing sulfur dioxide from boiler flue gas according to claim 5, characterized in that: Also includes: During the operation of the system, the flue gas at the outlet of the washing tower (2) is detected. If the nitrogen oxides and fly ash in 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 added to the washing tower (2).

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

Images