A method and system for low temperature regeneration of a so2 absorbent

Abstract

The application discloses a kind of SO2 absorbent low-temperature regeneration method and system, belong to flue gas desulfurization technical field.The method includes: SO2-containing flue gas is contacted with circulating lean liquid in absorption tower, and rich liquid is obtained;rich liquid is sent into desorption tower after heat exchange and temperature rise, and the temperature sensitivity of acid-base balance of buffer component is used to induce solution pH to rise under the condition that it is lower than the boiling point of SO2 absorbent solution solvent, promote the conversion of sulfur-containing species in liquid phase to molecular SO2 and release;while stripping gas is introduced into desorption tower to carry out SO2, and desorption driving force is maintained;regeneration tail gas is output after condensation and gas-liquid separation, and SO2 enrichment gas is output, and regeneration lean liquid is recycled.The application is mainly driven by heat-induced pH control, and SO2 is effectively regenerated under the condition that it is lower than the boiling point of solvent, and the regeneration energy consumption is significantly reduced, and the SO2 concentration of regeneration gas can meet the requirements of subsequent contact method for acid production.

Description

Technical Field

[0001] This invention relates to the field of renewable flue gas desulfurization and sulfur resource utilization technology, specifically to a low-temperature regeneration method and system for SO2 absorbent. Background Technology

[0002] Existing regenerable SO2 absorption processes typically combine absorption in an absorption tower with heating and stripping in a desorption tower. In these processes, rich-liquid regeneration relies not only on heating to weaken the liquid-phase stabilizing effect of SO2, but more importantly, on the continuous vaporization of water to reduce the partial pressure of SO2 in the gas phase, thereby maintaining the driving force for SO2 transfer from the liquid phase to the gas phase. Consequently, a large amount of water evaporation is inevitably generated during the regeneration process. The high latent heat of vaporization of water means that a significant portion of the input heat is consumed in solvent vaporization rather than for the reverse dissociation of SO2. Therefore, the regeneration unit has long been the main energy source of the entire SO2 capture process.

[0003] To reduce regeneration energy consumption, researchers have attempted improvements at the absorbent level. Composite absorption systems composed of organic amines and polybasic acids have been proposed for SO2 absorption, such as the ethylenediamine-phosphoric acid (EDA-H3PO4) system. This system utilizes the binding effect of amine groups on SO2 to achieve a high absorption capacity, and the absorbent can be regenerated and cycled through heating. However, the regeneration process of these absorbents still relies on traditional heating and stripping methods. The regeneration operating temperature is usually close to or exceeds the solvent boiling point, and the regeneration mechanism still mainly relies on heating to weaken the binding force and stripping to reduce the partial pressure of the gas phase. This fails to fundamentally eliminate the dependence on large amounts of water vapor stripping, resulting in still relatively high regeneration energy consumption.

[0004] On the other hand, from the perspective of integration with downstream resource recovery processes, traditional high-temperature steam stripping is not the only feasible path. Contact-based acid production, as an important method for SO2 resource recovery, typically only requires an SO2 volume fraction of about 8% to 12% in the feed gas, and does not require a high-purity SO2 stream. However, in existing regeneration processes, regardless of the absorbent system used, the selection of regeneration operating conditions is solely aimed at maximizing the SO2 desorption rate. The SO2 concentration in the regeneration gas is often much higher than the inlet requirements for acid production, or additional gas dilution is needed to meet the acid production requirements. This fails to consider the energy consumption and concentration matching issues of the entire absorption-regeneration-resource recovery process at the system level.

[0005] Therefore, there is an urgent need in the field for a regeneration method and system that can achieve effective SO2 regeneration at lower temperatures, reduce stripping steam consumption, and directly match the regenerated gas concentration to the subsequent acid production requirements. Summary of the Invention

[0006] The purpose of this invention is to provide a low-temperature regeneration method and system for SO2 absorbent, so as to solve the technical problems of high regeneration energy consumption and mismatch between regenerated gas concentration and downstream acid production process in the existing regenerable SO2 absorption process.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: The present invention provides a low-temperature regeneration method for SO2 absorbent, comprising the following steps: S1. Absorption step: SO2-containing flue gas is absorbed by circulating lean liquid in the absorption tower to obtain rich liquid; the circulating lean liquid is a regenerated SO2 absorbent solution. S2, Rich liquid heat exchange step: The rich liquid is drawn out from the bottom of the absorption tower and exchanged with the regenerated high-temperature lean liquid through the rich-lean liquid heat exchanger, so that the rich liquid is preheated to form a medium-temperature rich liquid. S3. Heating and regeneration step: The preheated medium-temperature rich liquid is further fed into a heater and heated to the set regeneration temperature to obtain a high-temperature rich liquid, which is then sent to the desorption tower; under conditions lower than the solvent boiling point of the SO2 absorbent solution, the pH of the rich liquid system rises as the temperature increases, which promotes the conversion and release of sulfur-containing species in the liquid phase into molecular SO2. S4. Gas stripping step: Gas stripping gas is continuously introduced into the desorption tower so that the released SO2 is continuously carried out, thereby reducing the partial pressure of SO2 in the gas phase, maintaining the driving force for SO2 to transfer from the liquid phase to the gas phase, and forming SO2-containing regenerated tail gas. S5. Gas-liquid separation step: The regenerated tail gas is sequentially fed into a condenser and a gas-liquid separator to separate entrained droplets and condensate, thereby obtaining SO2-enriched gas.

[0008] S6. Lean liquor reflux step: The regenerated lean liquor is drawn from the bottom of the desorption tower, and after recovering heat from the rich liquor through the lean-rich liquor heat exchanger, it is cooled down to the absorption temperature by the cooler and returned to the absorption tower for continued recycling.

[0009] Further, in step S1, the SO2 absorbent is a double buffer absorbent consisting of an anion and a cation, composed of an organic amine component and a polyacid component; the SO2 absorbent solution is an aqueous solution system or a water-deficient system, wherein the water-deficient system contains a physical solvent, which is a small molecule polyether polyol, and its volume fraction is 10% to 40% of the water-deficient system.

[0010] Preferably, the SO2 absorbent is a HEP-H3Cit double buffer absorbent composed of N-hydroxyethylpiperazine (HEP) and citric acid (H3Cit); the molar ratio of HEP to H3Cit is 2:(1±0.2), and the initial pH of the SO2 absorbent solution is 5.5±0.5.

[0011] Furthermore, in step S3, the sulfur-containing species is one or both of sulfite and bisulfite.

[0012] Furthermore, in step S3, the regeneration temperature is 80°C to 95°C.

[0013] Further, in step S4, the gas being lifted is air, nitrogen, or a mixture of air and nitrogen.

[0014] Furthermore, in step S4, the humidity of the regenerated exhaust gas is 5% to 30%.

[0015] Further, in step S4, the flow rate of the stripping gas is adjusted so that the dry basis SO2 volume fraction of the SO2 enriched gas is 8% to 12%.

[0016] The present invention also provides a low-temperature regeneration system for SO2 absorbent, comprising an absorption tower, a lean-rich liquid heat exchanger, a heater, a desorption tower, a condenser, and a gas-liquid separator; The lower part of the absorption tower is connected to a pipe for inputting SO2-containing flue gas into the tower body, the top of the absorption tower is connected to a pipe for outputting purified gas, the bottom of the absorption tower is connected to the heat-extracting inlet of the lean-rich liquid heat exchanger, the heat-extracting outlet of the lean-rich liquid heat exchanger is connected to the upper part of the desorption tower through a heater, the bottom of the desorption tower is connected to the heat-supplying inlet of the lean-rich liquid heat exchanger, the heat-supplying outlet of the lean-rich liquid heat exchanger is connected to the upper part of the absorption tower through a condenser, the top of the desorption tower is connected to a gas-liquid separator through a condenser, the top of the gas-liquid separator discharges SO2-enriched gas, and the bottom discharges condensate. The lower part of the desorption tower is also connected to a pipe for inputting gas into the tower body.

[0017] Compared with the prior art, the beneficial effects of the present invention are: First, this invention transforms the SO2 regeneration driving force from the traditional steam stripping-dominated gas phase dilution mechanism to the thermally induced pH regulation-dominated liquid phase equilibrium migration mechanism, thereby establishing a desorption driving force within the liquid phase. This mechanism makes solvent vaporization no longer a necessary condition for maintaining the desorption driving force, thus reducing the high latent heat consumption caused by solvent vaporization from the fundamental aspect of the process.

[0018] Secondly, the present invention uses stripped gas to continuously carry out SO2, so that the SO2 concentration of the regenerated gas can directly match the requirement of 8% to 12% SO2 volume fraction for subsequent contact acid production, thereby enhancing the coupling between SO2 capture and sulfur resource utilization. The introduced stripped gas only undertakes the function of carrying out the released SO2 and maintaining low partial pressure. The stripped gas itself does not undergo phase change and does not introduce additional phase change heat load.

[0019] Third, in this invention, the regeneration temperature is lower than the solvent boiling point, and the solvent remains in a liquid state, thus avoiding the consumption of latent heat of phase change associated with the vaporization of a large amount of solvent. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the SO2 absorbent low-temperature regeneration system in Embodiment 1 of the present invention.

[0021] Figure 2 The graph shows a comparison between the predicted and experimental values ​​of SO2 equilibrium capacity and solution pH in two absorbents, HEP-H3Cit and EDA-H3PO4. Among them, (a) shows the changes in SO2 equilibrium capacity and solution pH during the isothermal absorption of the HEP-H3Cit system, (b) shows the changes in SO2 equilibrium capacity and solution pH during the heating desorption of the HEP-H3Cit system, (c) shows the changes in SO2 equilibrium capacity and solution pH during the isothermal absorption of the EDA-H3PO4 system, and (d) shows the changes in SO2 equilibrium capacity and solution pH during the heating desorption of the EDA-H3PO4 system.

[0022] Figure 3 The graph shows the effect of pH fluctuations on the SO2 equilibrium capacity in the HEP-H3Cit double buffer aqueous solution system.

[0023] Figure 4 The graph shows the effect of pH fluctuations on SO2 equilibrium capacity in the HEP-H3Cit double-buffered, water-poor system (containing 20% ​​tetraethylene glycol by volume).

[0024] Figure 5 The graph shows the effect of pH fluctuations on SO2 equilibrium capacity in the HEP-H3Cit double-buffered, water-poor system (containing 30% tetraethylene glycol by volume).

[0025] Figure 6 The figure shows the effect of regeneration temperature and humidity of regeneration tail gas on the capture performance of different absorbent systems. Among them, (a) is the HEP-H3Cit aqueous solution system, (b) is the HEP-H3Cit water-poor system with a tetraethylene glycol volume fraction of 20%, (c) is the HEP-H3Cit water-poor system with a tetraethylene glycol volume fraction of 30%, and (d) is the relationship between regeneration temperature and SO2 partial pressure in regeneration gas in the HEP-H3Cit aqueous solution system.

[0026] Figure 7 The diagram shows the total energy consumption and energy consumption distribution of each component in the regeneration process of the HEP-H3Cit water-poor system (20% tetraethylene glycol volume fraction) at different regeneration temperatures.

[0027] Figure 8 The graph shows the effect of pH fluctuations on the SO2 equilibrium capacity in the EDA-H3PO4 aqueous solution system. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1 Please see Figure 1 This embodiment provides a low-temperature regeneration system for SO2 absorbent, including an absorption tower, a lean-rich liquid heat exchanger, a heater, a desorption tower, a condenser, and a gas-liquid separator. The lower part of the absorption tower is connected to a pipe for inputting SO2-containing flue gas into the tower body, the top of the absorption tower is connected to a pipe for outputting purified gas, the bottom of the absorption tower is connected to the heat-extracting inlet of the lean-rich liquid heat exchanger, the heat-extracting outlet of the lean-rich liquid heat exchanger is connected to the upper part of the desorption tower through the heater, the bottom of the desorption tower is connected to the heat-supplying inlet of the lean-rich liquid heat exchanger, the heat-supplying outlet of the lean-rich liquid heat exchanger is connected to the upper part of the absorption tower through the condenser, the top of the desorption tower is connected to the gas-liquid separator through the condenser, the top of the gas-liquid separator discharges SO2-enriched gas, and the bottom discharges condensate. The lower part of the desorption tower is also connected to a pipe for inputting gas into the tower body.

[0030] This embodiment also provides a low-temperature regeneration method for SO2 absorbent based on the above system, including: (1) Flue gas containing SO2 enters from the bottom of the absorption tower, and the circulating lean liquid (regenerated SO2 absorbent solution) enters from the top of the absorption tower. The gas and liquid phases come into countercurrent contact in the tower, SO2 is absorbed and enters the liquid phase, and the purified flue gas is discharged from the top of the tower. The rich liquid that has absorbed SO2 is drawn out from the bottom of the absorption tower, and after passing through the lean-rich liquid heat exchanger, it exchanges heat with the high-temperature lean liquid from the desorption tower. After recovering some heat, it enters the heater for further heating, and then is sent to the desorption tower. (2) The operating temperature of the desorption tower is lower than the boiling point of the solvent used in the absorbent solution. Under this temperature condition, the acid-base balance of the buffer component in the absorbent shifts with the increase of temperature, the pH value of the rich solution rises, and the sulfur-containing species in the liquid phase in the form of sulfite and bisulfite are converted into molecular SO2 and released from the liquid phase. At the same time, gas stripping gas (air, nitrogen or a mixture of the two) is continuously introduced into the lower part of the desorption tower. The gas stripping gas flows upward and contacts the liquid phase, continuously carrying the released SO2 out of the tower to form regeneration tail gas containing SO2 and water vapor. (3) The regenerated tail gas is discharged from the top of the desorption tower and enters the condenser to cool down, so that the water vapor and a small amount of solvent vapor entrained in it are condensed. Then it enters the gas-liquid separator for gas-liquid separation. The separated liquid phase (mainly condensate and a small amount of solvent) can be returned to the system or processed separately. The separated gas phase is SO2 enriched gas, which is sent to the subsequent contact acid production unit. (4) The regenerated lean liquid is discharged from the bottom of the desorption tower, and after releasing heat to the rich liquid through the lean-rich liquid heat exchanger, it is cooled to the absorption temperature by the cooler and returned to the absorption tower to participate in SO2 absorption again, forming a closed loop.

[0031] Example 2 SO2 absorption and low-temperature regeneration of the SO2 absorbent were carried out according to the method in Example 1.

[0032] In this embodiment, HEP-H3Cit dual-buffered absorbent is used as the SO2 absorbent, and water is used as the solvent to form an HEP-H3Cit aqueous solution system. The HEP concentration is 1.0 mol·L⁻¹. -1 The H3Cit concentration was 0.5 mol·L⁻¹ -1 The initial pH of the solution was 5.26.

[0033] The absorption conditions were: absorption temperature 40℃ (313.15 K) and partial pressure of SO2 in the gas phase 500 Pa.

[0034] like Figure 3 As shown, under these absorption conditions, the measured SO2 equilibrium capacity of the HEP-H3Cit double buffer aqueous solution is 0.83 mol·L⁻¹. -1 The solution pH was 4.31. The rich solution after SO2 absorption was regenerated by heating to 90℃ (363.15 K). At this temperature (100℃ below the boiling point of the aqueous solvent), the solution pH rose to 4.82, and the SO2 equilibrium capacity decreased to 0.30 mol·L⁻¹. -1 .

[0035] pass Figure 2 The thermodynamic analysis shown indicates that 50.68% of the decrease in SO2 equilibrium capacity during the heating process was contributed by pH recovery (thermally induced pH regulation), demonstrating that thermoinduced pH regulation plays a crucial driving role in the low-temperature regeneration of this system. Further increasing the temperature to 120℃ (393.15 K, above the boiling point of water), the contribution of pH fluctuations to the SO2 desorption rate reached 65.17%.

[0036] Example 3 SO2 absorption and low-temperature regeneration of the SO2 absorbent were carried out according to the method in Example 1.

[0037] In this embodiment, HEP-H3Cit double buffer absorbent is used as the SO2 absorbent, and tetraethylene glycol is used as the physical solvent to construct a water-poor HEP-H3Cit system. In this embodiment, the volume fraction of tetraethylene glycol is 20%, and the concentration of HEP is 1.0 mol·L⁻¹. -1 The H3Cit concentration was 0.5 mol·L⁻¹ -1The initial pH of the solution was 5.26.

[0038] SO2 absorption was performed under the same conditions as in Example 2 (40°C, 500 Pa), followed by regeneration of the rich solution by heating it to 80°C. Figure 4 As shown, under these absorption conditions, the SO2 equilibrium capacity of the HEP-H3Cit water-poor system decreased significantly at 90℃, while the pH rose noticeably. Thermodynamic analysis revealed that at 90℃, the contribution of thermoinduced pH regulation to the SO2 desorption rate was 65.76%, significantly higher than the contribution rate (50.68%) of the aqueous solution system in Example 2 at the same temperature, indicating that a water-poor environment is conducive to the effect of thermoinduced pH regulation. When the temperature was further increased to 120℃, the contribution of thermoinduced pH regulation to the SO2 desorption rate reached 72.67%.

[0039] Example 4 SO2 absorption and low-temperature regeneration of the SO2 absorbent were carried out according to the method in Example 1.

[0040] In this embodiment, HEP-H3Cit dual-buffered absorbent is used as the SO2 absorbent, and tetraethylene glycol is used as the physical solvent to construct a water-poor HEP-H3Cit system. In this embodiment, the volume fraction of tetraethylene glycol is 30%, and the concentration of HEP is 1.0 mol·L⁻¹. -1 The H3Cit concentration was 0.5 mol·L⁻¹ -1 The initial pH of the solution was 5.26.

[0041] SO2 absorption was performed under the same conditions as in Example 2 (40°C, 500 Pa), followed by regeneration by heating the rich solution to 90°C. Figure 5 As shown, under these absorption conditions, the contribution of thermally induced pH regulation to the SO2 desorption rate of this HEP-H3Cit water-poor system is 62.20% at 90℃ and 68.99% at 120℃.

[0042] The results of Examples 3 and 4 show that a physical solvent volume fraction in the range of 20%–30% can significantly enhance the contribution of thermally induced pH regulation to SO2 desorption. However, when the volume fraction is too high (30% compared to 20%), the contribution rate of pH swing decreases slightly due to the reduced water content in the absorbent affecting SO2 dissolution and ionization. Therefore, the preferred physical solvent volume fraction is 10%–40%, more preferably 20%–30%.

[0043] Example 5 Based on Example 3, air was introduced into the desorption tower as the stripping gas. By adjusting the stripping gas flow rate, SO2 in the gas phase was continuously carried out, and the concentration of the resulting regenerated gas was controlled.

[0044] like Figure 6 and 7 As shown, the gas lift flow rate is 250 kmol·h -1 Under these conditions, the volume fraction of SO2 in the theoretical dry-basis regeneration gas is approximately 9.1%, falling within the 8% to 12% range commonly used in contact-process acid production feedstock gases. Therefore, direct coupling of the SO2 capture process and the acid production process can be achieved. Comparing the process energy consumption under different regeneration conditions, at 80℃ and with a regeneration tail gas humidity of approximately 5%, the total energy consumption is approximately 5.32 GJ·t. -1 -SO2; When the regeneration temperature is increased to 85℃ and the humidity of the regeneration tail gas is about 10%, the system's circulating load increases significantly while water evaporation remains controlled, and the total energy consumption decreases to about 3.18 GJ·t. -1 -SO2; When the temperature is further increased to 90℃ and 95℃, the proportion of latent heat of vaporization of water increases, and the total energy consumption rebounds. At 90℃ and with a regeneration tail gas humidity of about 20%, the total energy consumption is approximately 3.86 GJ·t. -1 -SO2, at 95℃ and with a regeneration exhaust gas humidity of approximately 30%, has a total energy consumption of approximately 4.51 GJ·t. -1 -SO2. The results above show that under the low-temperature regeneration conditions described in this invention (below the solvent boiling point), a higher regeneration temperature is not necessarily better. In the range of 80℃ to 85℃, increasing the temperature helps improve the SO2 desorption rate and cycling load, and energy consumption shows a decreasing trend; however, above 85℃, the solvent vaporization rate increases significantly with increasing temperature, and the proportion of latent heat of vaporization in the total energy consumption increases, leading to a rebound in total energy consumption. Therefore, around 85℃ is the preferred operating temperature window for this invention.

[0045] Comparative Example An aqueous solution of ethylenediamine-phosphoric acid (EDA-H3PO4) was used as the SO2 absorbent solution. The concentration of EDA was 1.0 mol·L⁻¹. -1 The concentration of H3PO4 is 0.5 mol·L⁻¹ -1 The initial pH of the solution was 7.0.

[0046] SO2 absorption was performed under the same absorption conditions as in Example 2 (40°C, 500 Pa), followed by regeneration of the rich solution by heating it to 90°C. Figure 2 As shown, the measured SO2 equilibrium capacity of the EDA-H3PO4 aqueous solution system is 1.00 mol·L⁻¹. -1 The measured pH of the solution was 3.8. (For example...) Figure 8 As shown, when the rich solution is heated to 90℃ (363.15 K), the pH of the solution rises to 4.79, while the SO2 equilibrium capacity only decreases to 0.94 mol·L⁻¹. -1 The SO2 desorption rate contributed by pH rise in this system was 17.82%, which was significantly lower than that of the HEP-H3Cit system in Examples 2 to 5.

[0047] These results indicate that not all absorbent systems with buffering capacity possess significant thermo-induced pH regulation characteristics. Although the pH of the EDA-H3PO4 aqueous solution system also changes during heating, this change fails to effectively drive the chemical equilibrium of sulfur-containing species in the liquid phase towards the molecular state of SO2. Its regeneration still relies on traditional stripping partial pressure, verifying the specific system dependence of the thermo-induced pH regulation mechanism of this invention.

Claims

1. A low-temperature regeneration method for an SO2 absorbent, characterized in that, Includes the following steps: S1. Absorption step: SO2-containing flue gas is absorbed by circulating lean liquid in the absorption tower to obtain rich liquid; the circulating lean liquid is a regenerated SO2 absorbent solution. S2, Rich liquid heat exchange step: The rich liquid is drawn out from the bottom of the absorption tower and exchanged with the regenerated high-temperature lean liquid through the rich-lean liquid heat exchanger, so that the rich liquid is preheated to form a medium-temperature rich liquid. S3. Heating and regeneration step: The preheated medium-temperature rich liquid is further fed into a heater and heated to the set regeneration temperature to obtain a high-temperature rich liquid, which is then sent to the desorption tower; under conditions lower than the solvent boiling point of the SO2 absorbent solution, the pH of the rich liquid system rises as the temperature increases, which promotes the conversion and release of sulfur-containing species in the liquid phase into molecular SO2. S4. Gas stripping step: Gas stripping gas is continuously introduced into the desorption tower so that the released SO2 is continuously carried out, thereby reducing the partial pressure of SO2 in the gas phase, maintaining the driving force for SO2 to transfer from the liquid phase to the gas phase, and forming SO2-containing regenerated tail gas. S5. Gas-liquid separation step: The regenerated tail gas is sequentially fed into a condenser and a gas-liquid separator to separate entrained droplets and condensed water, and SO2-enriched gas is obtained. S6. Lean liquor reflux step: The regenerated lean liquor is drawn from the bottom of the desorption tower, and after recovering heat from the rich liquor through the lean-rich liquor heat exchanger, it is cooled down to the absorption temperature by the cooler and returned to the absorption tower for continued recycling.

2. The low-temperature regeneration method for an SO2 absorbent according to claim 1, characterized in that: In step S1, the SO2 absorbent is a double buffer absorbent consisting of an anion and a cation, composed of an organic amine component and a polyacid component; the SO2 absorbent solution is an aqueous solution system or a water-deficient system, wherein the water-deficient system contains a physical solvent, which is a small molecule polyether polyol, and its volume fraction is 10% to 40% of the water-deficient system.

3. The low-temperature regeneration method for an SO2 absorbent according to claim 2, characterized in that: The SO2 absorbent is a HEP-H3Cit double buffer absorbent composed of N-hydroxyethylpiperazine and citric acid, with a molar ratio of HEP to H3Cit of 2:(1±0.2) and an initial pH of 5.5±0.5 for the SO2 absorbent solution.

4. The low-temperature regeneration method for an SO2 absorbent according to claim 1, characterized in that: In step S3, the sulfur-containing species is one or both of sulfite and bisulfite.

5. The low-temperature regeneration method for an SO2 absorbent according to claim 1, characterized in that: In step S3, the regeneration temperature is 80°C to 95°C.

6. The low-temperature regeneration method for an SO2 absorbent according to claim 1, characterized in that: In step S4, the gas used for gas extraction is air, nitrogen, or a mixture of air and nitrogen.

7. The low-temperature regeneration method for an SO2 absorbent according to claim 1, characterized in that: In step S4, the humidity of the regenerated exhaust gas is 5% to 30%.

8. The low-temperature regeneration method for an SO2 absorbent according to claim 1, characterized in that: In step S4, the flow rate of the stripping gas is adjusted so that the dry basis SO2 volume fraction of the SO2 enriched gas is 8% to 12%.

9. The low-temperature regeneration method for an SO2 absorbent according to claim 2, characterized in that: The present invention also provides a low-temperature regeneration system for SO2 absorbent, comprising an absorption tower, a lean-rich liquid heat exchanger, a heater, a desorption tower, a condenser, and a gas-liquid separator; The lower part of the absorption tower is connected to a pipe for inputting SO2-containing flue gas into the tower body, the top of the absorption tower is connected to a pipe for outputting purified gas, the bottom of the absorption tower is connected to the heat-extracting inlet of the lean-rich liquid heat exchanger, the heat-extracting outlet of the lean-rich liquid heat exchanger is connected to the upper part of the desorption tower through a heater, the bottom of the desorption tower is connected to the heat-supplying inlet of the lean-rich liquid heat exchanger, the heat-supplying outlet of the lean-rich liquid heat exchanger is connected to the upper part of the absorption tower through a condenser, the top of the desorption tower is connected to a gas-liquid separator through a condenser, the top of the gas-liquid separator discharges SO2-enriched gas, and the bottom discharges condensate. The lower part of the desorption tower is also connected to a pipe for inputting gas into the tower body.

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