So 2 absorption and desorption system and absorption and desorption method

Abstract

An SO2 absorption and desorption system and absorption and desorption method. The SO2 absorption and desorption system comprises a water washing tower (1), an absorption tower (2), a regeneration tower (3), a rich liquid pipeline (1003) and a lean liquid pipeline (1004); the water washing tower (1) comprises a first feeding port (101) and a first tower top outlet (102), and the first feeding port (101) is connected to a waste gas feeding pipeline (1001) and a supplementary water pipeline (1002) separately; the absorption tower (2) comprises a second feeding port (201), a first tower top inlet (202) and a second tower bottom outlet (203); the first tower top outlet (102) is connected to the second feeding port (201); the regeneration tower (3) comprises a third feeding port (301), a fourth feeding port (302), a second tower top inlet (303), a third tower bottom outlet (304) and a third tower top outlet (305); the third feeding port (301) is located above the fourth feeding port (302); and the third tower top outlet (305) is connected to the second tower top inlet (303) by means of a water cooler (306) to form a tower top circulation loop (1006). According to the system and the method, the content of sulfur dioxide in an outlet gas can be reduced, the desulfurization efficiency can be further improved, and sulfur dioxide can be further recycled, thereby satisfying the requirements of energy conservation and environmental protection, and improving the absorption effect.

Description

A SO2 absorption and desorption system and absorption and desorption method Technical Field

[0001] The present invention relates to an SO2 absorption and desorption system and an absorption and desorption method. Background Art

[0002] Industrial waste gas usually contains pollutants such as SO2, which will directly affect the ecological environment on which we depend for survival. Relevant measures to control SO2 emissions have limited effect.

[0003] SO2 is an acidic gas that not only damages ecosystems like land, forests, and rivers, but also causes irreparable harm to buildings, industrial facilities, and cultural relics. Furthermore, it has a significant impact on human health. Therefore, effectively controlling SO2 emissions is an urgent task. Currently, over 200 flue gas desulfurization technologies are being researched and developed worldwide, but very few have been commercially implemented.

[0004] Currently, the mainstream processes for treating this flue gas include ammonia absorption and limestone slurry absorption. The ammonia absorption method, also known as ammonia-based desulfurization, uses ammonia, a raw material used in fertilizers, which is valuable and expensive, resulting in certain production losses for synthetic ammonia companies. Furthermore, ammonia is volatile, easily causing white smoke to escape from the top of the flue gas and generating secondary aerosol pollution. The limestone slurry absorption method, also known as wet lime absorption, utilizes limestone for absorption, offering convenient access and low production costs. However, the resulting gypsum is a solid waste with low economic value, and the system consumes a large amount of water. Therefore, a green and recyclable flue gas desulfurization process is needed.

[0005] Ionic liquids (ILs) are substances composed entirely of ions that are liquid at room temperature or below. They are also known as room temperature ionic liquids, room temperature molten salts, or organic ionic liquids. Their greatest characteristic is their near-zero vapor pressure and excellent chemical and thermal stability. Furthermore, ILs exhibit excellent solubility for a wide variety of organic and inorganic gases, with significant variations in solubility. This suggests that ILs, as environmentally friendly, green solvents, hold great promise for gas separation applications. Using ionic liquids as absorbents for SO2 absorption has become a new research topic.

[0006] Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art, such as low desulfurization efficiency and high sulfur dioxide content in the outlet gas, by providing a SO2 absorption and desorption system and absorption and desorption method. The system and method of the present application not only reduce the sulfur dioxide content in the outlet gas and further improve the desulfurization efficiency, but also realize the recovery and utilization of sulfur dioxide, thereby meeting the requirements of energy conservation and environmental protection and improving the absorption effect.

[0008] The present invention solves the above technical problems through the following technical solutions:

[0009] The present invention provides a SO2 absorption and desorption system, which includes a water washing tower, an absorption tower, a regeneration tower, a rich liquid pipeline and a lean liquid pipeline; wherein,

[0010] The water washing tower comprises a first feed inlet and a first tower top outlet, wherein the first feed inlet is connected to an exhaust gas feed pipeline and a supplementary water pipeline respectively;

[0011] The absorption tower comprises a second feed inlet, a first tower top inlet and a second tower bottom outlet; the first tower top outlet is connected to the second feed inlet;

[0012] The regeneration tower includes a third feed port, a fourth feed port, a second tower top inlet, a third tower bottom outlet, and a third tower top outlet; the third feed port is located above the fourth feed port; the rich liquid pipeline is connected to the third feed port after passing through the cold fluid channel of the heat exchanger from the second tower bottom outlet; the lean liquid pipeline is connected to the first tower top inlet and the fourth feed port after passing through the hot fluid channel of the heat exchanger and the lean liquid cooler from the third tower bottom outlet;

[0013] The third tower top outlet is connected to the second tower top inlet through a water cooler to form a tower top circulation loop.

[0014] In the present invention, preferably, an electric demisting device is provided in the top of the water washing tower for removing acid mist and fine particulate matter from the flue gas.

[0015] In the present invention, preferably, the water washing tower further includes a first tower kettle outlet and a water-cooling circulation pipeline, and the water-cooling circulation pipeline is connected to the make-up water pipeline and the top inlet of the water washing tower respectively after passing through a water-cooling tower circulation cooler from the first tower kettle outlet; more preferably, a water-cooling tower bottom circulation pump is provided on the water-cooling circulation pipeline; more preferably, an external liquid outlet is provided on the water-cooling circulation pipeline.

[0016] In the present invention, preferably, the water washing tower comprises a plate tower or a packed tower, more preferably a packed tower, and even more preferably a two-stage packed tower.

[0017] In the present invention, preferably, the first feed inlet is provided with a gas distributor for allowing the gas to enter the water-cooling tower evenly, so as to provide sufficient contact area for gas-liquid mass transfer.

[0018] In the present invention, preferably, the first feed inlet is provided at the lower portion of the water washing tower.

[0019] In the present invention, preferably, the absorption tower further includes a second top outlet, and the second top outlet is used to discharge tail gas.

[0020] In the present invention, preferably, the absorption tower is a packed tower, more preferably a two-stage packed tower.

[0021] In the present invention, preferably, the second feed port is provided at the lower portion of the absorption tower.

[0022] In the present invention, preferably, a rich liquid pump is provided on the pipeline between the second tower kettle outlet and the heat exchanger.

[0023] In the present invention, preferably, a lean liquid pump is provided on the pipeline between the heat exchanger and the lean liquid cooler.

[0024] In the present invention, preferably, a pre-filtration cooler and a filter are sequentially provided on the pipeline between the lean liquid cooler and the fourth feed port.

[0025] In the present invention, preferably, the regeneration tower is a packed tower, more preferably a three-stage packed tower.

[0026] In the present invention, preferably, the third feed port is arranged above the packing layer of the regeneration tower, and the third feed port is used to transport the rich liquid to the regeneration tower for regeneration; the fourth feed port is used to transport the lean liquid as the regenerated solvent to the bottom of the regeneration tower.

[0027] In the present invention, preferably, the fourth feed port is provided at the lower portion of the regeneration tower.

[0028] In the present invention, preferably, a regeneration tower top reflux pump is provided on the tower top circulation loop.

[0029] In the present invention, preferably, a regeneration tower top reflux tank is provided on the tower top circulation loop, the inlet of the regeneration tower top reflux tank is connected to the outlet of the water cooler, the liquid phase outlet of the regeneration tower top reflux tank is connected to the second tower top inlet, and the gas phase outlet of the regeneration tower top reflux tank is connected to the sulfur dioxide collection device.

[0030] In the present invention, preferably, the kettle of the regeneration tower is provided with a reboiler circuit, and the reboiler circuit is provided with a reboiler; the heat exchange medium of the reboiler is low-pressure steam, and the low-pressure steam forms steam condensate after heat exchange.

[0031] The present invention also provides a SO2 absorption and desorption method, which uses the SO2 absorption and desorption system described above and includes the following steps:

[0032] S1, the flue gas is passed from the exhaust gas feed pipeline into the water washing tower for water washing, and the washed flue gas is obtained at the top of the water washing tower, and the liquid-gas ratio of the water washing is 5-10L / Nm 3 The temperature of the flue gas after water washing is 30-45°C;

[0033] S2, passing the washed flue gas into the absorption tower containing SO2 absorbent to absorb SO2, and obtaining SO2 rich liquid in the bottom of the absorption tower;

[0034] S3. The SO2 rich liquid is passed from the rich liquid pipeline through the heat exchanger to the regeneration tower for SO2 desorption, and a mixed gas and a SO2 lean liquid are obtained at the top and bottom of the regeneration tower respectively; the mixed gas is passed through the top circulation loop to obtain SO2 gas; the SO2 lean liquid is passed through the lean liquid pipeline through the heat exchanger and then passed into the absorption tower and the regeneration tower from the first tower top inlet and the fourth feed port respectively.

[0035] In the present invention, the Nm 3 It is the unit of standard gas cubic meter commonly used in this field.

[0036] In step S1, those skilled in the art should know that the purpose of the water washing is to cool the flue gas and remove dust.

[0037] In step S1, the content of SO2 in the flue gas is not particularly limited, but is preferably 5000-12000 mg / Nm 3 , for example 10000mg / Nm 3 .

[0038] In step S1, preferably, the flue gas is subjected to a pressure-boosting treatment before entering the water scrubber; the pressure-boosting treatment is achieved by a booster fan.

[0039] In step S1, preferably, the water washing tower is a two-stage packed tower, and the two-stage packed tower is divided into a first packing section and a second packing section from bottom to top; more preferably, the gas temperature in the first packing section is 35-45°C, and the gas temperature in the second packing section is 30-40°C; further preferably, the temperature of the gas in the second packing section changes from bottom to top from 40°C to 30°C.

[0040] In step S1, preferably, the washing water flowing out from the first kettle outlet of the water washing tower is refluxed to the top inlet of the water washing tower through the water-cooling circulation pipeline of the water washing tower for recycling and reuse. More preferably, the washing water is pressurized by the water-cooling tower bottom circulation pump on the water-cooling circulation pipeline.

[0041] Preferably, the washing water contacts the flue gas in countercurrent and is used again to wash and cool the flue gas.

[0042] In step S1, preferably, the gas velocity of the water scrubber is 1-2 m / s.

[0043] In step S1, preferably, the liquid-gas ratio of the water washing refers to the volume ratio of water to flue gas.

[0044] In step S2, preferably, the temperature of the SO2 absorption is 10-100°C, more preferably 40-90°C.

[0045] In step S2, preferably, the pressure of the SO2 absorption is 0.01-0.2 MPa, more preferably 0.05-0.2 MPa.

[0046] In step S2, preferably, the liquid-gas ratio of the SO2 absorption is 0.1-3 L / Nm 3 , more preferably 0.35-1.3L / Nm 3 ; Those skilled in the art should know that the liquid-to-gas ratio of the SO2 absorption refers to the volume ratio of the SO2 absorbent to the flue gas after water washing.

[0047] In step S2, preferably, the gas velocity of the absorption tower is 0.5-5 m / s, more preferably 1.5-2.5 m / s.

[0048] In step S2, preferably, the absorption tower is a two-stage packed tower, and the liquid holding capacity of the packing layer of the two-stage packed tower is 3-10m 3 Liquid / m 3 Filler, preferably 4-8m 3 Liquid / m 3 Packing to provide sufficient contact area for gas-liquid mass transfer.

[0049] In step S2, preferably, the SO2 absorbent includes: 30wt%-70wt% ionic liquid, 0.1wt%-4.0wt% activator, 0.1wt%-0.5wt% antioxidant, 0.1wt%-0.5wt% corrosion inhibitor, and water; wt% refers to the ratio of the mass of the above component to the total mass of the SO2 absorbent.

[0050] Wherein, in the SO2 absorbent, the water content is preferably 35wt%-65wt%.

[0051] Wherein, in the SO2 absorbent, the content of the ionic liquid is preferably 35wt%-55wt%.

[0052] Preferably, the ionic liquid comprises a cation and an anion; the cation comprises a nitrogen-containing organic substance, and the anion comprises an organic acid. Further preferably, the cation of the ionic liquid is selected from one or more of guanidine salts, alcoholamines, imidazoles, pyridines, tetrazoles, quaternary ammonium salts, thiazoles, and dicyandiamide; and the anion is selected from one or more of lactic acid, tartaric acid, citric acid, methanesulfonic acid, malic acid, oxalic acid, and acetic acid. This ionic liquid can absorb SO2 with high selectivity, while absorbing almost no other acidic gases, such as CO2.

[0053] Among them, preferably, in the SO2 absorbent, the activator includes an organic alcohol substance; preferably, the activator includes one or two of n-butanol, n-hexanol and n-octanol.

[0054] Among them, preferably, in the SO2 absorbent, the antioxidant includes phenolic or quinone substances with weak reducing properties; preferably, the antioxidant includes one or more of hydroquinone, dibutylhydroxytoluene, tert-butylhydroquinone, naphthoquinone, anthraquinone and their derivatives.

[0055] Among them, preferably, in the SO2 absorbent, the corrosion inhibitor includes an inorganic salt substance; preferably, the corrosion inhibitor is selected from one or more of basic copper carbonate, potassium metavanadate, arsenic trioxide and antimony trichloride.

[0056] As a preferred embodiment, the composition of the SO2 absorbent is: 45 wt% of tetramethylguanidine tartrate, 0.3 wt% of n-butanol, 0.15 wt% of hydroquinone, 0.2 wt% of basic copper carbonate, and the rest is water.

[0057] As a preferred embodiment, the composition of the SO2 absorbent is: 30 wt% of metformin lactate, 0.3 wt% of n-butanol, 0.15 wt% of hydroquinone, 0.2 wt% of basic copper carbonate, and the rest is water.

[0058] As a preferred embodiment, the composition of the SO2 absorbent is: 70wt% of ethanolamine tartrate, 0.3wt% of n-butanol, 0.15wt% of hydroquinone, 0.2wt% of basic copper carbonate, and the rest is water.

[0059] In step S2, preferably, after the SO2 absorption is completed, tail gas is obtained at the top of the absorption tower, and the tail gas is discharged from the second top outlet of the absorption tower.

[0060] In step S3, preferably, the temperature of SO2 desorption is 100-150°C, more preferably 110-140°C.

[0061] In step S3, preferably, the pressure of the SO2 desorption is 0.01-0.2 MPa, more preferably 0.05-0.2 MPa.

[0062] In step S3, preferably, the gas velocity of the regeneration tower is 0.2-1.5 m / s, more preferably 0.6-0.8 m / s.

[0063] In step S3, preferably, the regeneration tower is a three-stage packed tower, and the liquid holding capacity of the packing layer of the three-stage packed tower is 1-8m 3 Liquid / m 3 Filler, preferably 1.5-5m 3 Liquid / m 3 Packing to provide sufficient contact area for gas-liquid mass transfer.

[0064] In step S3, the SO2 gas can be fed into the next process section to synthesize H2SO4.

[0065] In the present invention, the SO2 concentration in the SO2 gas can reach above 95%, where the SO2 concentration refers to the volume percentage of SO2 in the SO2 gas. If the SO2 is mixed with water vapor, it can be directly introduced into the next process stage to synthesize a high-concentration H2SO4 byproduct.

[0066] In the present invention, when the SO2 content in the flue gas reaches 10000 mg / Nm 3 When the SO2 content in the SO2 outlet gas is less than or equal to 70 mg / Nm 3 , desulfurization efficiency is as high as 99.3% and above.

[0067] In the present invention, the process of selectively absorbing SO2 based on an absorbent mainly composed of ionic liquids is described in more detail:

[0068] The ionic liquid-based absorbent provided by the present invention has good absorption and desorption capabilities for SO2 gas. The desulfurization mechanism is shown in formulas (1) and (2):

[0069] Overall reaction formula:

[0070] In the above formula, R represents the absorbent, and the overall reaction is reversible. At low temperatures, the reaction proceeds from left to right; at high temperatures, it proceeds from right to left. This process utilizes this principle, absorbing sulfur dioxide at low temperatures and desorbing it from the absorbent at high temperatures, thereby achieving the goal of removing and recovering sulfur dioxide from flue gas.

[0071] The positive progress effect of the present invention is:

[0072] The system and method of the present application have the following advantages: stable performance, extremely low vapor pressure, strong absorption capacity for sulfur dioxide, low energy consumption, high desulfurization efficiency, and easy desorption and regeneration; the present application can not only reduce the content of sulfur dioxide in the exhaust gas and further improve the desulfurization efficiency, but also realize the recycling and utilization of sulfur dioxide, thereby meeting the requirements of energy conservation and environmental protection and improving the absorption effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] FIG1 is a schematic structural diagram of a SO2 absorption and desorption system according to Example 1 of the present invention.

[0074] Description of the accompanying drawings: Water washing tower 1 First feed inlet 101 First tower top outlet 102 Electrostatic demister 103 First tower bottom outlet 104 Water-cooled tower circulating cooler 105 Water-cooled tower bottom circulating pump 106 External liquid outlet 107 Absorption tower 2 Second feed inlet 201 First tower top inlet 202 Second tower bottom outlet 203 Second tower top outlet 204 Regeneration tower 3 Third feed inlet 301 Fourth feed inlet 302 Second tower top inlet 303 Third tower bottom outlet 304 Third tower top outlet 305 Water cooler 306 Regeneration tower top reflux tank 307 Reboiler 308 Low-pressure steam 309 Steam condensate 310 Regeneration tower top reflux pump 311 Heat exchanger 401 Rich liquid pump 402 Lean liquid pump 403 Lean liquid cooler 404 Pre-filtration cooler 405 Filter 406 Sulfur dioxide collection device 5 Waste gas feed pipeline 1001, make-up water pipeline 1002, rich liquid pipeline 1003, lean liquid pipeline 1004, water cooling circulation pipeline 1005, tower top circulation loop 1006, reboiler loop 1007. DETAILED DESCRIPTION

[0075] The technical solution of the present invention is described in detail below with reference to the embodiments.

[0076] Example 1

[0077] The system includes a water washing tower 1, an absorption tower 2, a regeneration tower 3, a rich liquid pipeline 1003 and a lean liquid pipeline 1004; wherein the water washing tower 1 includes a first feed port 101 and a first tower top outlet 102, the first feed port 101 is connected to an exhaust gas feed pipeline 1001 and a make-up water pipeline 1002 respectively; the absorption tower 2 includes a second feed port 201, a first tower top inlet 202 and a second tower bottom outlet 203; the first tower top outlet 102 is connected to the second feed port 201; the regeneration tower 3 includes a third feed port 301, a fourth feed port 302, a second tower top inlet 303, a third tower bottom outlet The third tower top outlet 301 is located above the fourth tower top outlet 302; the rich liquid pipeline 1003 is connected to the third tower top outlet 301 after passing through the cold fluid channel of the heat exchanger 401 from the second tower bottom outlet 203; the lean liquid pipeline 1004 is connected to the first tower top inlet 202 and the fourth tower top outlet 302 after passing through the hot fluid channel of the heat exchanger 401 and the lean liquid cooler 404 from the third tower bottom outlet 304; the third tower top outlet 305 is connected to the second tower top inlet 303 through the water cooler 306, forming a tower top circulation loop 1006.

[0078] An electric demisting device 103 is provided at the top of the water washing tower 1;

[0079] The water washing tower 1 also includes a first tower kettle outlet 104 and a water-cooling circulation pipeline 1005. The water-cooling circulation pipeline 1005 is connected to the make-up water pipeline 1002 and the top inlet of the water washing tower 1 respectively after passing through the water-cooling tower circulation cooler 105 from the first tower kettle outlet 104; a water-cooling tower bottom circulation pump 106 is provided on the water-cooling circulation pipeline 1005; and an external liquid outlet 107 is provided on the water-cooling circulation pipeline 1005.

[0080] The water scrubber 1 is a two-stage packed tower; the first feed inlet 101 is provided with a gas distributor; the first feed inlet 101 is provided at the lower part of the water scrubber 1 .

[0081] The absorption tower 2 further includes a second top outlet 204; the absorption tower 2 is a two-stage packed tower; the second feed inlet 201 is provided at the lower portion of the absorption tower 2; a rich liquid pump 402 is provided on the pipeline between the second bottom outlet 203 and the heat exchanger 401;

[0082] A lean liquid pump 403 is provided on the pipeline between the heat exchanger 401 and the lean liquid cooler 404 ; a pre-filtration cooler 405 and a filter 406 are provided in sequence on the pipeline between the lean liquid cooler 404 and the fourth feed inlet 302 .

[0083] The regeneration tower 3 is a three-stage packed tower; the fourth feed port 302 is provided at the lower part of the regeneration tower 3; a regeneration tower top reflux pump 311 is provided on the top circulation loop 1006; a regeneration tower top reflux tank 307 is provided on the top circulation loop 1006, the inlet of the regeneration tower top reflux tank 307 is connected to the outlet of the water cooler 306, the liquid phase outlet of the regeneration tower top reflux tank 307 is connected to the second tower top inlet 303, and the gas phase outlet of the regeneration tower top reflux tank 307 is connected to the sulfur dioxide collection device 5.

[0084] The kettle of the regeneration tower 3 is provided with a reboiler circuit, and a reboiler 308 is provided on the reboiler circuit; the heat exchange medium of the reboiler 308 is low-pressure steam 309, and the low-pressure steam 309 forms steam condensate 310 after heat exchange.

[0085] Example 2

[0086] S1, the temperature is 140 ℃, containing 10000mg / Nm 3 The SO2 flue gas is passed from the waste gas feed pipe 1001 into the water washing tower 1 for water washing. The washed flue gas is obtained at the top of the water washing tower 1. The liquid-gas ratio of the water washing is 5L / Nm 3 The temperature of the flue gas after water washing is 40°C; wherein the gas velocity of the water washing tower 1 is 1.5m / s;

[0087] Before entering the water scrubber 1, the flue gas is also subjected to a pressure-boosting treatment; the pressure-boosting treatment is achieved by a booster fan;

[0088] The water washing tower 1 is a two-stage packed tower, which is divided into a first packed section and a second packed section from bottom to top; the gas temperature in the first packed section is 35-45°C, and the gas temperature in the second packed section is 40-30°C;

[0089] The washing water flowing out from the first kettle outlet 104 of the water washing tower 1 is refluxed to the top inlet of the water washing tower 1 through the water cooling circulation pipeline 1005 of the water washing tower 1 for recycling and countercurrent contact with the flue gas; the washing water is pressurized by the water cooling tower bottom circulation pump 106 on the water cooling circulation pipeline 1005;

[0090] S2, passing the washed flue gas into the absorption tower 2 containing SO2 absorbent to absorb SO2, achieving gas-liquid countercurrent contact, and obtaining SO2 rich liquid in the bottom of the absorption tower 2; wherein,

[0091] The temperature of SO2 absorption is 60-70℃; the pressure of SO2 absorption is 0.1MPa; the liquid-gas ratio of SO2 absorption is 0.7L / Nm 3 ; The gas velocity of absorption tower 2 is 2m / s;

[0092] Absorption tower 2 is a two-stage packed tower with a liquid holding capacity of 7m 3Liquid / m 3 filler;

[0093] The SO2 absorbent comprises: 45% methylguanidine tartrate, 0.3% n-butanol, 0.15% hydroquinone, 0.2% basic copper carbonate, and the remainder is water;

[0094] After the SO2 absorption is completed, tail gas is obtained at the top of the absorption tower 2, and the tail gas is discharged from the second top outlet 204 of the absorption tower 2.

[0095] S3, the SO2 rich liquid is passed from the rich liquid pipeline 1003 through the heat exchanger 401 to the regeneration tower 3 for SO2 desorption, and a mixed gas and a SO2 lean liquid are obtained at the top and bottom of the regeneration tower 3 respectively; the mixed gas passes through the top circulation loop 1006 to obtain SO2 gas; the SO2 lean liquid passes through the lean liquid pipeline 1004 through the heat exchanger 401 and is passed into the absorption tower 2 and the regeneration tower 3 respectively from the first tower top inlet 202 and the fourth feed port 302; wherein,

[0096] The temperature for SO2 desorption is 120°C; the pressure for SO2 desorption is 0.1 MPa; the gas velocity in regeneration tower 3 is controlled within the range of 0.6-0.8 m / s;

[0097] Regeneration tower 3 is a three-stage packed tower with a liquid holding capacity of 4m 3 Liquid / m 3 filler.

[0098] The concentration of SO2 desorbed from the regeneration tower 3 can reach over 95%. The SO2 is cooled by the condenser 8 and then enters the gas-liquid separator 9. The separated and purified SO2 is sent to the subsequent process, such as the sulfuric acid plant to produce sulfuric acid. It can also be pressurized and cooled to produce liquid SO2 products. The concentration of SO2 in the purified gas is reduced to 48mg / Nm 3 , the desulfurization efficiency is 99.5%.

[0099] The process operation results show that the system and method of the present application can effectively absorb SO2 in flue gas with high absorption efficiency and good selectivity, and the system can operate stably for a long time.

[0100] Example 3

[0101] In step S2 of this embodiment, the SO2 absorbent is composed of (all component proportions are by mass): 30 wt% metformin lactate, 0.3 wt% n-butanol, 0.15 wt% hydroquinone, 0.2 wt% basic copper carbonate, and the remainder water. The remaining steps are the same as in Example 2.

[0102] After desulfurization by the absorbent, the concentration of SO2 in the purified gas is reduced to 50mg / Nm 3 , the desulfurization efficiency is 99.5%.

[0103] Example 4

[0104] In step S2 of this embodiment, the SO2 absorbent is composed of (all component proportions are by mass): 70 wt% ethanolamine tartrate, 0.3 wt% n-butanol, 0.15 wt% hydroquinone, 0.2 wt% basic copper carbonate, and the remainder water. The remaining steps are the same as in Example 2.

[0105] After desulfurization by the absorbent, the concentration of SO2 in the purified gas is reduced to 70mg / Nm 3 , the desulfurization efficiency is 99.3%.

[0106] The above are only some preferred embodiments of the present invention, and the present invention is not limited to the contents of the embodiments. For those skilled in the art, various changes and modifications can be made within the scope of the technical solution of the present invention, and any changes and modifications made are within the scope of protection of the present invention.

Claims

1. A SO2 absorption and desorption system, characterized in that: It includes a water washing tower, an absorption tower, a regeneration tower, a rich liquid pipeline and a lean liquid pipeline; among which, The water washing tower comprises a first feed inlet and a first tower top outlet, wherein the first feed inlet is respectively connected to an exhaust gas feed pipeline and a supplementary water pipeline; The absorption tower comprises a second feed inlet, a first tower top inlet and a second tower bottom outlet; the first tower top outlet is connected to the second feed inlet; The regeneration tower comprises a third feed inlet, a fourth feed inlet, a second tower top inlet, a third tower bottom outlet and a third tower top outlet; the third feed inlet is located above the fourth feed inlet; the rich liquid pipeline passes through the cold fluid channel of the heat exchanger from the second tower bottom outlet and is connected to the third feed inlet; the lean liquid pipeline passes through the hot fluid channel of the heat exchanger and the lean liquid cooler from the third tower bottom outlet and is connected to the first tower top inlet and the fourth feed inlet respectively; The third tower top outlet is connected to the second tower top inlet via a water cooler to form a tower top circulation loop.

2. A SO2 absorption and desorption system as claimed in claim 1, characterized in that: An electric demisting device is provided in the top of the water washing tower; And / or, the water scrubber further comprises a first tower kettle outlet and a water cooling circulation pipeline, wherein the water cooling circulation pipeline is connected to the make-up water pipeline and the tower top inlet of the water scrubber respectively after passing through a water cooling tower circulation cooler from the first tower kettle outlet; And / or, the water washing tower comprises a plate tower or a packed tower; And / or, the first feed inlet is provided with a gas distributor; And / or, the first feed inlet is arranged at the lower part of the water washing tower.

3. A SO2 absorption and desorption system as claimed in claim 2, characterized in that: The water cooling circulation pipeline is provided with a water cooling tower bottom circulation pump; And / or, the water cooling circulation pipeline is provided with an external liquid discharge outlet; And / or, the water washing tower is a two-stage packed tower.

4. A SO2 absorption and desorption system as claimed in claim 1, characterized in that: The absorption tower further comprises a second tower top outlet, wherein the second tower top outlet is used to discharge tail gas; And / or, the absorption tower is a packed tower, preferably a two-stage packed tower; And / or, the second feed inlet is arranged at the lower part of the absorption tower; And / or, a rich liquid pump is provided on the pipeline between the second tower kettle outlet and the heat exchanger; And / or, a lean liquid pump is provided on the pipeline between the heat exchanger and the lean liquid cooler; And / or, a pre-filtration cooler and a filter are sequentially provided on the pipeline between the lean liquid cooler and the fourth feed inlet.

5. A SO2 absorption and desorption system as claimed in claim 1, characterized in that: The regeneration tower is a packed tower, preferably a three-stage packed tower; And / or, the fourth feed inlet is arranged at the lower part of the regeneration tower; And / or, a regeneration tower top reflux pump is provided on the tower top circulation loop; And / or, a regeneration tower top reflux tank is provided on the tower top circulation loop, the inlet of the regeneration tower top reflux tank is connected to the outlet of the water cooler, the liquid phase outlet of the regeneration tower top reflux tank is connected to the second tower top inlet, and the gas phase outlet of the regeneration tower top reflux tank is connected to the sulfur dioxide collection device; And / or, the kettle of the regeneration tower is provided with a reboiler circuit, and the reboiler circuit is provided with a reboiler; the heat exchange medium of the reboiler is low-pressure steam, and the low-pressure steam forms steam condensate after heat exchange.

6. A SO2 absorption and desorption method, characterized in that: The method adopts the SO2 absorption and desorption system as described in any one of claims 1 to 5, and comprises the following steps: S1. The flue gas is passed from the exhaust gas feed pipeline into the water washing tower for water washing, and the washed flue gas is obtained at the top of the water washing tower. The liquid-to-gas ratio of the water washing is 5-10 L / Nm 3 ; The temperature of the flue gas after water washing is 30-45°C; S2, passing the washed flue gas into the absorption tower containing SO2 absorbent to absorb SO2, and obtaining SO2 rich liquid in the bottom of the absorption tower; S3, the SO2 rich liquid is passed from the rich liquid pipeline to the regeneration tower for SO2 desorption after heat exchange through the heat exchanger, and a mixed gas and a SO2 lean liquid are obtained at the top and bottom of the regeneration tower respectively; the mixed gas passes through the top circulation loop to obtain SO2 gas; the SO2 lean liquid passes through the lean After heat exchange in the heat exchanger, the liquid pipeline enters the absorption tower and the regeneration tower from the first tower top inlet and the fourth feed inlet respectively.

7. The SO2 absorption and desorption method according to claim 6, characterized in that: In step S1, the content of SO2 in the flue gas is 5000-12000 mg / Nm 3 , for example 10000mg / Nm 3 ; And / or, before entering the water scrubber, the flue gas is further subjected to a pressure-boosting treatment; the pressure-boosting treatment is achieved by a booster fan; And / or, the water washing tower is a two-stage packed tower, which is divided into a first packed section and a second packed section from bottom to top; preferably, the gas temperature in the first packed section is 35-45°C, and the gas temperature in the second packed section is 30-40°C; And / or, the washing water flowing out from the first kettle outlet of the water washing tower is refluxed to the top inlet of the water washing tower through the water cooling circulation pipeline of the water washing tower for recycling, and preferably, the washing water is pressurized by a water cooling tower bottom circulation pump on the water cooling circulation pipeline; And / or, the gas velocity of the water scrubber is 1-2 m / s.

8. The SO2 absorption and desorption method according to claim 6, characterized in that: In step S2, the temperature of SO2 absorption is 10-100°C, preferably 40-90°C; And / or, the pressure of the SO2 absorption is 0.01-0.2MPa, preferably 0.05-0.2MPa; And / or, the liquid-to-gas ratio of the SO2 absorption is 0.1-3L / Nm 3 , preferably 0.35-1.3L / Nm 3 ; And / or, the gas velocity of the absorption tower is 0.5-5 m / s, preferably 1.5-2.5 m / s; And / or, the absorption tower is a two-stage packed tower, and the liquid holding capacity of the packing layer of the two-stage packed tower is 3-10m 3 Liquid / m 3 Filler, preferably 4-8m 3 Liquid / m 3 filler; And / or, the SO2 absorbent comprises: 30wt%-70wt% ionic liquid, 0.1wt%-4.0wt% activator, 0.1wt%-0.5wt% antioxidant, 0.1wt%-0.5wt% corrosion inhibitor, and water; wt% refers to the ratio of the mass of a certain component to the total mass of the SO2 absorbent; And / or, after the SO2 absorption is completed, tail gas is obtained at the top of the absorption tower, and the tail gas is discharged from the second top outlet of the absorption tower.

9. The SO2 absorption and desorption method according to claim 8, characterized in that: In the SO2 absorbent, the water content is 35wt%-65wt%; And / or, the content of the ionic liquid is 35wt%-55wt%; And / or, the ionic liquid includes cations and anions; the cations include nitrogen-containing organic substances, and the anions include organic acids; preferably, the cations of the ionic liquid are selected from one or more of guanidine salts, alcohol amines, imidazoles, pyridines, tetrazoles, quaternary ammonium salts, thiazoles, and dicyandiamide substances; the anions are selected from one or more of lactic acid, tartaric acid, citric acid, methanesulfonic acid, malic acid, oxalic acid, and acetic acid; And / or, the activator comprises an organic alcohol substance; preferably, the activator comprises one or two of n-butanol, n-hexanol and n-octanol; And / or, the antioxidant includes phenolic or quinone substances with weak reducing properties; preferably, the antioxidant includes one or more of hydroquinone, butylated hydroxytoluene, tert-butylhydroquinone, naphthoquinone, anthraquinone and derivatives thereof; And / or, the corrosion inhibitor includes an inorganic salt substance; preferably, the corrosion inhibitor is selected from one or more of basic copper carbonate, potassium metavanadate, arsenic trioxide and antimony trichloride; Preferably, the composition of the SO2 absorbent is: 45wt% tetramethylguanidine tartrate, 0.3wt% n-butanol, 0.15wt% hydroquinone, 0.2wt% basic copper carbonate, and the rest is water; Preferably, the composition of the SO2 absorbent is: 30wt% of metformin lactate, 0.3wt% of n-butanol, 0.15wt% of hydroquinone, 0.2wt% of basic copper carbonate, and the rest is water; Preferably, the SO2 absorbent is composed of 70wt% ethanolamine tartrate, 0.3wt% n-butanol, 0.15wt% hydroquinone, 0.2wt% basic copper carbonate, and the rest is water.

10. The SO2 absorption and desorption method according to claim 6, characterized in that: In step S3, the temperature of SO2 desorption is 100-150°C, preferably 110-140°C; And / or, the pressure of the SO2 desorption is 0.01-0.2MPa, preferably 0.05-0.2MPa; And / or, the gas velocity of the regeneration tower is 0.2-1.5 m / s, preferably 0.6-0.8 m / s; And / or, the regeneration tower is a three-stage packed tower, and the liquid holding capacity of the packing layer of the three-stage packed tower is 1-8m 3 Liquid / m 3 Filler, preferably 1.5-5m 3 Liquid / m 3 filler.

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