Flue gas desulfurization and carbon capture integrated system and method

Abstract

The invention discloses a flue gas desulfurization and carbon capture integrated system and method. The system comprises a denitration and heat recovery device, a desulfurization and carbon dioxide capture device, a regeneration device, an oxidation device, an evaporative crystallization device and a barren liquor cooler, the denitration and heat recovery device is communicated with the desulfurization and carbon dioxide trapping device, the desulfurization and carbon dioxide trapping device is communicated with the regeneration device, a material outlet of the regeneration device is communicated with the oxidation device and the barren liquor cooler, the oxidation device is communicated with the evaporative crystallization device, and the barren liquor cooler is communicated with the evaporative crystallization device. And the barren liquor cooler is communicated with the carbon dioxide trapping device. By integrating desulfurization and carbon dioxide capture processes, the process is simplified, a flue gas pretreatment tower and a flue gas carbon dioxide capture tower are omitted, the pressure drop of a flue gas system is reduced, the energy consumption is reduced, and the equipment investment cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of carbon dioxide emission reduction technology, and specifically relates to an integrated system and method for flue gas desulfurization and carbon capture. Background Technology

[0002] Flue gas is a significant source of carbon dioxide emissions. Currently, the most widely used carbon capture method is the amine process, which involves absorbing carbon dioxide with an alkanolamine solution at low temperatures and then regenerating and desorbing the carbon dioxide at high temperatures, thereby achieving carbon dioxide capture. However, the alkanolamine carbon dioxide capture process suffers from problems such as absorbent degradation and oxidation losses, and difficulties in treating high-concentration amine-containing organic wastewater. Furthermore, the process requires desulfurization before carbon dioxide capture, resulting in a long process and high investment costs. All of these factors are the main reasons hindering the industrialization of carbon dioxide capture.

[0003] Chinese patent CN115301059A discloses a carbon dioxide capture device and method, comprising: a CO2 flue gas scrubbing assembly and a carbon decomposition tower. The carbon decomposition tower is connected to a preheated mixed liquid inlet and a decomposed gas outlet. The CO2 flue gas scrubbing assembly is connected to a hydrophobic heat exchanger via a washed mixed liquid conveying pipe. The hydrophobic heat exchanger is connected to a preheated mixed liquid inlet via a preheated mixed liquid conveying pipe. The carbon decomposition tower is connected to an anti-mist device via the decomposed gas outlet. The anti-mist device is connected to a cryogenic cooler via an exhaust pipe. The cryogenic cooler is connected to a gas storage tank via a dehydrated CO2 conveying pipe. The flue gas feedstock used in this technology is clean flue gas that has undergone denitrification, desulfurization, and dust removal. The flue gas feedstock is a treated raw material, and the NO content in this flue gas feedstock is... X SO2 and particulate matter have been removed beforehand; secondly, the washing and absorption process used in this technology will increase the resistance of the original flue gas system. For some process flue gas, such as catalytic cracking flue gas, a special induced draft fan is required for pressurization; thirdly, the process flow of this technology is long, the construction investment is high, and the operating energy consumption is high.

[0004] Chinese patent CN109701362A discloses a liquid-solid phase change absorbent for carbon dioxide capture and its application. By mass percentage, it comprises the following components: 10%–60% carbonate, 2%–40% bicarbonate, 1%–20% absorbent activator, 0.01%–10% absorbent aid, and the balance being water. It utilizes the difference in solubility between carbonate and bicarbonate in aqueous solution to precipitate bicarbonate through chemical exchange or cooling crystallization, followed by pyrolysis regeneration of the high-concentration bicarbonate crystal slurry. While this technology utilizes the solubility difference between carbonate and bicarbonate to capture carbon dioxide, the crystallization and precipitation of bicarbonate during the capture process easily leads to equipment blockage. Therefore, the carbon dioxide absorption process is unsuitable for absorption devices with internal components, such as packed towers or sieve tray towers. Furthermore, the addition of organic aids and antioxidants to the carbonate-based absorbent results in organic wastewater, increasing the difficulty and cost of subsequent environmental treatment. In addition, this technology also has problems such as difficulty in long-cycle operation and low environmental friendliness.

[0005] Chinese patent CN14100688A discloses the preparation of an immobilized biomimetic enzyme and its application in the capture of carbon dioxide in flue gas. Utilizing biomimetic principles, it synthesizes a biomimetic material with natural carbonic anhydrase activity and applies it to the capture of carbon dioxide in flue gas. First, an immobilized biomimetic enzyme ZIF8 is synthesized in an aqueous phase under ambient temperature and pressure. Then, the flue gas is purified and cooled. After cooling, the flue gas containing carbon dioxide is passed into a sodium carbonate solution containing the biomimetic enzyme. The carbon dioxide reacts with the sodium carbonate, converting the sodium carbonate solution into a sodium bicarbonate solution. The presence of the biomimetic enzyme accelerates the absorption and conversion rate of carbon dioxide. Subsequently, the sodium bicarbonate solution is heated or subjected to reduced pressure to collect pure carbon dioxide. The biomimetic enzyme accelerates the desorption of carbon dioxide during this process. This technology proposes using a biomimetic enzyme to accelerate the absorption of carbon dioxide by a sodium carbonate solution. The absorbed sodium bicarbonate is then heated or subjected to reduced pressure to release the captured carbon dioxide, thereby achieving carbon dioxide capture. However, this technology requires pre-desulfurization and denitrification treatment of the flue gas; secondly, the absorption and desorption processes employed in this technology additionally increase the pressure drop of the flue gas system and equipment investment. Therefore, this technology suffers from a long process flow and high energy consumption.

[0006] Chinese patent CN108970360A discloses an energy-saving method for cyclically capturing carbon dioxide from flue gas. The method includes: (1) treating the flue gas; (2) adjusting the temperature of the flue gas to no higher than 50°C, and then having it come into gas-liquid two-phase contact with a sodium carbonate solution (carbon dioxide-poor solution) in an absorption tower; (3) converting the carbon dioxide-poor solution into a carbon dioxide-rich solution; (4) introducing the carbon dioxide-rich solution into a heating device and heating it to release carbon dioxide, while the liquid continues to circulate and absorb carbon dioxide; and (5) collecting and storing the carbon dioxide. However, this method only captures carbon dioxide from the flue gas and does not involve sulfur dioxide. In practical applications, a separate sulfur dioxide capture device is required, resulting in a long process and high investment costs.

[0007] Chinese patent CN110496517A discloses a process for the synergistic removal of carbon, sulfur, and nitrates from industrial flue gas. This process employs a chemical conversion method, where carbon dioxide, sulfur dioxide, and nitrate monoxide in the flue gas are neutralized or reduced by absorbents through chemical reactions within corresponding absorption systems. The process involves adding an absorbent to absorb a certain component of the flue gas, transforming it into an absorbent for purifying another component. The product of this secondary conversion then becomes a denitrification reducing agent, thus achieving the synergistic removal of carbon, sulfur, and nitrates. However, the described collection sequence is as follows: sodium carbonate solution contacts the flue gas, first absorbing carbon dioxide, then proceeding to the next layer to absorb sulfur dioxide. Based on the electrical balance constants of carbon dioxide and sulfur dioxide, it is known that when flue gas contacts the sodium carbonate solution, sulfur dioxide absorption occurs first, followed by carbon dioxide absorption. Therefore, the process described in this invention is theoretically infeasible. Meanwhile, according to current flue gas denitrification theories and methods, the removal of nitrogen oxides typically takes place at 200–300°C, generally requiring combination with heat recovery devices to reduce energy consumption. Directly combining this process with the relatively low-temperature desulfurization and decarbonization processes would result in significant energy waste. Furthermore, nitrogen oxides in flue gas exist in various forms, and removing only nitric oxide is insufficient to meet the required nitrogen oxide concentration levels in the post-denitrification flue gas.

[0008] Chinese patent CN206295788U discloses a dry flue gas desulfurization device based on sodium bicarbonate, comprising a desulfurizing agent supply device, a flue gas absorption device, a dust removal device, and a desulfurizing agent regeneration device. The desulfurizing agent supply device supplies a sodium bicarbonate-containing desulfurizing agent to the flue gas absorption device. The flue gas absorption device uses the desulfurizing agent to absorb sulfur dioxide and carbon dioxide from the flue gas, thereby forming a mixed flue gas containing sodium carbonate, sodium sulfate, and fly ash. The dust removal device is connected to the flue gas absorption device and is used to separate the mixed flue gas into a dust collector containing sodium carbonate, sodium sulfate, and fly ash, and purified flue gas. The desulfurizing agent regeneration device is connected to the dust removal device. However, this method belongs to dry desulfurization technology, and its reaction process is mainly gas-solid, resulting in low desulfurization efficiency and high equipment investment. Summary of the Invention

[0009] This invention addresses the problems of difficult wastewater treatment and high investment and operating costs in amine-based carbon capture processes by proposing an integrated flue gas desulfurization and carbon capture system.

[0010] To address the problems existing in the prior art, this invention provides an integrated flue gas desulfurization and carbon capture system, comprising: a denitrification and heat recovery device, a desulfurization and carbon dioxide capture device, a regeneration device, an oxidation device, an evaporation and crystallization device, and a lean liquor cooler; the denitrification and heat recovery device is connected to the desulfurization and carbon dioxide capture device, the desulfurization and carbon dioxide capture device is connected to the regeneration device, the material outlet of the regeneration device is connected to both the oxidation device and the lean liquor cooler, the oxidation device is connected to the evaporation and crystallization device, and the lean liquor cooler is connected to the carbon dioxide capture device.

[0011] In one embodiment, the number of the evaporation crystallization apparatus is one, two, or more.

[0012] In one embodiment, when the number of evaporation crystallization devices is two or more, the evaporation crystallization devices are connected in series, and the evaporation crystallization device connected to the oxidation device is a primary evaporation crystallization device. The primary evaporation crystallization device is also connected to the pipeline between the material outlet of the regeneration device and the lean liquid cooler.

[0013] In one embodiment, when the number of evaporation crystallization devices is two or more, the evaporation crystallization devices are connected in series, the material outlet of the evaporation crystallization device connected to the oxidation device is also connected to the pipeline between the carbon dioxide capture device and the regeneration device, and the material inlet of the evaporation crystallization device is connected to the regeneration device.

[0014] In one embodiment, the flue gas inlet operating pressure of the denitrification and heat recovery device is 2.0 to 15.0 kPa(G), preferably 2.0 to 8.0 kPa(G).

[0015] In one embodiment, the desulfurization and carbon dioxide capture device includes an absorbent, which is a sodium carbonate solution with a mass concentration of 5-35%, preferably 10-25%.

[0016] In one embodiment, the desulfurization and carbon dioxide capture device employs an absorption tower, and the liquid phase outlet operating temperature of the desulfurization and carbon dioxide capture device is 40-60°C, the gas-liquid volume ratio is 50-400:1, and the operating pressure is 0-10 kPa(G); preferably, the operating temperature is 45-50°C, the gas-liquid volume ratio is 100-300:1, and the operating pressure is 0-5 kPa(G).

[0017] In one embodiment, the pH value (25°C) of the regenerated lean liquid at the liquid phase outlet of the regeneration device is controlled at 8.5 to 9.5, preferably 8.8 to 9.2.

[0018] In one embodiment, the ratio of sodium carbonate mass concentration to sodium sulfate mass concentration in the liquid phase outlet solution of the evaporation crystallization apparatus is less than 1.0, preferably less than 0.5.

[0019] In one embodiment, the evaporation crystallization process in the evaporation crystallization apparatus is at least one of direct evaporation crystallization, single-effect evaporation, multi-effect evaporation, multi-stage flash evaporation, and mechanical vapor recompression.

[0020] In one embodiment, the lean liquid temperature output by the lean liquid cooler is ≤45°C, preferably ≤42°C.

[0021] This invention also discloses an integrated method for flue gas desulfurization and carbon capture, the method comprising:

[0022] Flue gas enters the denitrification and heat recovery unit to complete NO removal. X After waste heat recovery, the denitrification flue gas enters the desulfurization and carbon dioxide capture device, where it comes into contact with the lean liquor to remove sulfur dioxide and carbon dioxide. The denitrified flue gas is then output from the desulfurization and carbon dioxide capture device. The rich liquor that has absorbed sulfur dioxide and carbon dioxide enters the regeneration device for regeneration. The regenerated carbon dioxide is then output from the regeneration device. Part of the regenerated lean liquor is cooled by the lean liquor cooler and returned to the desulfurization and carbon dioxide capture device for reuse. The other part of the regenerated lean liquor is input into the oxidation device for oxidation. The oxidized regenerated lean liquor is then input into the evaporation and crystallization device for evaporation.

[0023] In one embodiment, when there is one evaporation crystallization device, the oxidized regenerated lean liquor is input into the evaporation crystallization device and evaporated to form evaporation crystals, which are then discharged as solid waste.

[0024] In one embodiment, when there are two or more evaporation crystallization devices, the oxidized regenerated lean liquid S5 is input into the primary evaporation crystallization device to evaporate and form sodium carbonate-rich crystal material. The sodium carbonate-rich crystal material is dissolved using the regenerated lean liquid and returned to the desulfurization and carbon dioxide capture device for reuse. The remaining solution after evaporation is input into the secondary evaporation crystallization device to evaporate and crystallize, forming sodium sulfate-rich crystals as solid waste and discharged.

[0025] In one embodiment, when there are two or more evaporation crystallization devices, the oxidized regenerated lean liquor is fed into the primary evaporation crystallization device for evaporation. During the evaporation crystallization process in the primary evaporation crystallization device, carbon dioxide gas generated by the regeneration device is introduced to form sodium bicarbonate-rich crystal material in the primary evaporation crystallization device. The sodium bicarbonate-rich crystal material is introduced into the rich liquor for dissolution and then enters the regeneration device for regeneration along with the rich liquor. The remaining solution after evaporation is fed into the secondary evaporation crystallization device for evaporation crystallization to form sodium sulfate-rich crystals, which are discharged as solid waste.

[0026] In one embodiment, the proportion of the regenerated lean liquor input to the oxidation device is 0.1 to 2% of the total volumetric flow rate of the regenerated lean liquor, preferably 0.3 to 1.0%.

[0027] The integrated flue gas desulfurization and carbon capture system and method of this invention uses sodium carbonate solution to simultaneously capture sulfur dioxide and carbon dioxide in catalytic flue gas. The resulting sodium carbonate solution containing sodium bicarbonate and sodium sulfite is then thermally regenerated to release carbon dioxide. A portion of the regenerated sodium carbonate solution containing sodium sulfite is oxidized to form sodium sulfate and sodium carbonate solutions. The oxidized sodium carbonate solution is then gradually evaporated, concentrated, and crystallized to form sodium carbonate-rich crystals and sodium sulfate-rich crystals, respectively. The former is dissolved in water and used as a replenishing solution for reuse in the desulfurization and carbon dioxide capture devices, while the latter (sulfate) is disposed of as solid waste. Using the integrated flue gas desulfurization and carbon capture system and method of this invention, sulfur dioxide removal and carbon dioxide capture can be completed simultaneously in flue gas. Since the absorbent used is an inorganic salt, the degradation and oxidation problems of traditional organic absorbents and the high costs of subsequent wastewater treatment are avoided. Furthermore, through process integration, compared to the traditional process of first desulfurizing and then using amine-based or other absorbents to capture carbon dioxide, the process of this invention is shorter, saving investment and carbon dioxide capture costs.

[0028] This invention simplifies the process by integrating desulfurization and carbon dioxide capture, eliminating the need for a flue gas pretreatment tower and a flue gas carbon dioxide capture tower. This reduces the pressure drop of the flue gas system, saves energy, and lowers equipment investment costs. The invention uses sodium carbonate as the absorbent. Compared to the amine-containing wastewater generated by traditional organic amine absorption processes, the solid waste generated by this invention is inorganic salt, making it easier and cheaper to treat. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the integrated flue gas desulfurization and carbon capture system of Example 1.

[0030] Figure 2 This is a schematic diagram of the integrated flue gas desulfurization and carbon capture system of Example 2.

[0031] Figure 3 This is a schematic diagram of the integrated flue gas desulfurization and carbon capture system of Example 3.

[0032] In the attached figures, the following labels are used:

[0033] S1 – Flue gas; S2 – Denitrification flue gas; S3 – Rich liquor; S4 – Regenerated lean liquor; S5 – Regenerated lean liquor after oxidation; S6 – Sodium carbonate-rich crystalline material; S7 – Solution remaining after evaporation; S8 – Lean liquor; S9 – Flue gas after denitrification; S10 – Carbon dioxide; S11 – Sodium sulfate-rich crystals; S12 – Carbon dioxide gas; S13 – Evaporated crystals; S14 – Sodium bicarbonate-rich crystalline material; E1 – Denitrification and heat recovery unit; E2 – Desulfurization and carbon dioxide capture unit; E3 – Regeneration unit; E4 – Oxidation unit; E5 – Primary evaporation crystallization unit; E6 – Secondary evaporation crystallization unit; E7 – Lean liquor cooler. Detailed Implementation

[0034] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0035] The integrated flue gas desulfurization and carbon capture system of the present invention includes a denitrification and heat recovery device E1, a desulfurization and carbon dioxide capture device E2, a regeneration device E3, an oxidation device E4, an evaporation and crystallization device, and a lean liquor cooler E7. The desulfurization and carbon dioxide capture device E2 contains an absorbent, which is a sodium carbonate solution. The desulfurization and carbon dioxide capture device E2 is used to simultaneously capture sulfur dioxide and carbon dioxide in the flue gas, forming sodium bicarbonate and sodium sulfite after capture. The sodium carbonate solution containing sodium bicarbonate and sodium sulfite generated in the desulfurization and carbon dioxide capture device E2 is input into the regeneration device E3, where carbon dioxide S10 is released through thermal regeneration. The oxidation device E4 is used to deoxidize a portion of the regenerated lean liquor produced by the regeneration device E3. The evaporation and crystallization device is used to evaporate, concentrate, and crystallize the oxidized regenerated lean liquor produced by the oxidation device E4. The lean liquor cooler E7 is used to cool another portion of the regenerated lean liquor produced by the regeneration device E3. The cooled regenerated lean liquor, as lean liquor S8, is returned to the desulfurization and carbon dioxide capture device E2 for reuse.

[0036] In this invention, the number of evaporation crystallization devices can be one, two, or more; this invention is not particularly limited.

[0037] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the integrated flue gas desulfurization and carbon capture system of Example 1. In this example, there are two evaporation crystallization devices: a primary evaporation crystallization device E5 and a secondary evaporation crystallization device E6, connected in series. The denitrification and heat recovery device E1 is connected to the desulfurization and carbon dioxide capture device E2. The desulfurization and carbon dioxide capture device E2 is connected to the regeneration device E3. The material outlet of the regeneration device E3 is connected to both the oxidation device E4 and the lean liquor cooler E7. The oxidation device E4 is connected to the primary evaporation crystallization device E5. The primary evaporation crystallization device E5 is also connected to the pipeline between the material outlet of the regeneration device E3 and the lean liquor cooler E7. The lean liquor cooler E7 is connected to the carbon dioxide capture device E2.

[0038] The oxidized regenerated lean liquor S5 is fed into the primary evaporation crystallization unit E5 to evaporate and form sodium carbonate-rich crystal material S6. The sodium carbonate-rich crystal material S6 is dissolved using the regenerated lean liquor S4 and then returned to the desulfurization and carbon dioxide capture unit E2 for reuse. The remaining solution S7 is fed into the secondary evaporation crystallization unit E6 to evaporate and crystallize, forming sodium sulfate-rich crystals S11, which are discharged as solid waste.

[0039] Please refer to Figure 2 , Figure 2 This is a schematic diagram of the integrated flue gas desulfurization and carbon capture system in Example 2. In this example, there is only one evaporation crystallization device, specifically a primary evaporation crystallization device E5, and no secondary evaporation crystallization device E6. The primary evaporation crystallization device E5 is not connected to the pipeline between the material outlet of the regeneration device E3 and the lean liquor cooler E7. The oxidized regenerated lean liquor S5 is fed into the evaporation crystallization device and evaporated to form evaporated crystals S13, which are discharged as solid waste. Other connection methods are the same as... Figure 1 The same applies, so I won't repeat it here.

[0040] Please refer to Figure 3 , Figure 3This is a schematic diagram of the integrated flue gas desulfurization and carbon capture system of Example 3. In this example, there are two evaporation crystallization devices: a primary evaporation crystallization device E5 and a secondary evaporation crystallization device E6, connected in series. The material outlet of the primary evaporation crystallization device E5 is connected to the pipeline between the carbon dioxide capture device E2 and the regeneration device E3, and the material inlet of the primary evaporation crystallization device E5 is connected to the regeneration device E3. The oxidized regeneration lean liquid S5 is input into the primary evaporation crystallization device E5 for evaporation. During the evaporation crystallization process in the primary evaporation crystallization device E5, carbon dioxide gas S12 generated by the regeneration device E3 is introduced, forming sodium bicarbonate-rich crystal material S14 in the primary evaporation crystallization device E5. The sodium bicarbonate-rich crystal material S14 is introduced into the rich liquid S3 for dissolution and then enters the regeneration device E3 for regeneration. The remaining solution S7 is input into the secondary evaporation crystallization device E6 for evaporation crystallization, forming sodium sulfate-rich crystals S11, which are discharged as solid waste. Other connection methods are the same as... Figure 1 The same applies, so I won't repeat it here.

[0041] In one embodiment, the flue gas inlet operating pressure of the denitrification and heat recovery device E1 is 2.0 to 15.0 kPa(G), preferably 2.0 to 8.0 kPa(G).

[0042] In one embodiment, the desulfurization and carbon dioxide capture device E2 includes an absorbent, which is a sodium carbonate solution with a mass concentration of 5-35%, preferably 10-25%.

[0043] In one embodiment, the desulfurization and carbon dioxide capture device E2 adopts an absorption tower. The liquid phase outlet operating temperature of the desulfurization and carbon dioxide capture device E2 is 40-60°C, the gas-liquid volume ratio is 50-400:1, and the operating pressure is 0-10 kPa(G). Preferably, the operating temperature is 45-50°C, the gas-liquid volume ratio is 100-300:1, and the operating pressure is 0-5 kPa(G).

[0044] In one embodiment, the pH value (25°C) of the regenerated lean liquid S4 at the liquid phase outlet of the regeneration device E3 is controlled at 8.5 to 9.5, preferably 8.8 to 9.2.

[0045] In one embodiment, the ratio of sodium carbonate mass concentration to sodium sulfate mass concentration in the liquid phase outlet solution of the evaporation crystallization apparatus is less than 1.0, preferably less than 0.5.

[0046] In one embodiment, the evaporation crystallization process in the evaporation crystallization apparatus is at least one of direct evaporation crystallization, single-effect evaporation, multi-effect evaporation, multi-stage flash evaporation, and mechanical vapor recompression.

[0047] In one embodiment, the lean liquid temperature output by the lean liquid cooler E7 is ≤45°C, preferably ≤42°C.

[0048] The integrated flue gas desulfurization and carbon capture method provided by this invention includes:

[0049] Flue gas S1 enters the denitrification and heat recovery unit E1 to complete the NO removal process. X After waste heat recovery, the denitrification flue gas S2 enters the desulfurization and carbon dioxide capture device E2, where it comes into contact with the lean liquor S8 to complete the removal of sulfur dioxide and carbon dioxide. The denitrified flue gas S9 exits the desulfurization and carbon dioxide capture device E2. The rich liquor S3, which has absorbed sulfur dioxide and carbon dioxide, enters the regeneration device E3 for regeneration. The regenerated carbon dioxide S10 exits the regeneration device E3. A portion of the regenerated lean liquor S4 is cooled by the lean liquor cooler E7 and returned to the desulfurization and carbon dioxide capture device E2 for reuse. Another portion of the regenerated lean liquor S4 is input into the oxidation device E4 for oxidation. The oxidized regenerated lean liquor S5 is input into the evaporation and crystallization device for evaporation.

[0050] In one embodiment, the proportion of the regenerated lean liquor S4 oxidized by the oxidation device E4 is 0.1 to 2% of the total volumetric flow rate of the regenerated lean liquor S4, preferably 0.3 to 1.0%.

[0051] The present invention will be further described below with reference to the embodiments.

[0052] Example 1

[0053] use Figure 1 The diagram shows the structure of an integrated flue gas desulfurization and carbon capture system.

[0054] Process flow: Flue gas S1 enters the denitrification and heat recovery unit E1 to complete NO removal. X After waste heat recovery, the denitrification flue gas S2 enters the desulfurization and carbon dioxide capture device E2, where it contacts the lean liquor S8 to complete the removal of sulfur dioxide and carbon dioxide. The denitrified flue gas S9 exits the desulfurization and carbon dioxide capture device E2. The rich liquor S3, which has absorbed sulfur dioxide and carbon dioxide, goes to the regeneration device E3 for regeneration. The regenerated carbon dioxide S10 exits the regeneration device E3. Part of the regenerated lean liquor S4 is cooled by the lean liquor cooler E7 and returned to the desulfurization and carbon dioxide capture device E2 for reuse. Another part of the regenerated lean liquor S4 is input into the oxidation device E4 for oxidation. The oxidized regenerated lean liquor S5 is input into the primary evaporation crystallization device E5 for evaporation. The resulting sodium carbonate-rich crystal material S6 is dissolved in the regenerated lean liquor S4 and reused. The remaining solution S7 is input into the secondary evaporation crystallization device E6 for evaporation and crystallization to form sodium sulfate-rich crystals S11, which are discharged as solid waste.

[0055] Process parameter operation control:

[0056] 1) Denitrification and heat recovery unit E1, flue gas inlet operating pressure 2.0 kPa(G);

[0057] 2) The absorbent used in this process is a sodium carbonate solution with a mass concentration of 15%;

[0058] 3) The desulfurization and carbon dioxide capture device E2 adopts a sieve plate absorption tower. The liquid outlet rich liquid operating temperature of the desulfurization and carbon dioxide capture device E2 is 48℃, the gas-liquid volume ratio is 120:1, and the tower top operating pressure is 0.5kPa(G).

[0059] 4) The regeneration unit E3 adopts a sieve plate regeneration tower. The pH value (25℃) of the lean liquid S4 after regeneration at the liquid phase outlet of the regeneration unit E3 is controlled at 9.1, and the operating pressure is 20kPa(G).

[0060] 5) The proportion of the regenerated lean liquor S4 input to the oxidation unit E4 for oxidation accounts for 0.4% of the total volumetric flow rate of the regenerated lean liquor S4;

[0061] 6) The ratio of sodium carbonate mass concentration to sodium sulfate mass concentration in the liquid phase outlet solution of the primary evaporation crystallization unit E5 is 0.3;

[0062] 7) The evaporation and crystallization process of the E5 primary evaporation crystallization unit is achieved using mechanical vapor recompression technology, with an operating temperature of 70℃ and an operating pressure of 15kPa (absolute pressure).

[0063] 8) The E6 secondary evaporation crystallization device adopts single-effect evaporation in the evaporation crystallization process, with an operating temperature of 80℃;

[0064] 9) The lean liquid temperature output by the regenerated lean liquid cooler E7 is 40℃.

[0065] Table 1 Raw material conditions:

[0066]

[0067]

[0068] Implementation results:

[0069] Carbon dioxide capture rate: 95%;

[0070] Carbon dioxide product purity: 99.2% (dry basis).

[0071] Example 2

[0072] use Figure 2 The diagram shows the structure of an integrated flue gas desulfurization and carbon capture system.

[0073] Process flow: Flue gas S1 enters the denitrification and heat recovery unit E1 to complete NO removal. XAfter waste heat recovery, the denitrification flue gas S2 enters the desulfurization and carbon dioxide capture device E2, where it comes into contact with the lean liquor S8 to complete the removal of sulfur dioxide and carbon dioxide. The denitrified flue gas S9 exits the desulfurization and carbon dioxide capture device E2. The rich liquor S3, which has absorbed sulfur dioxide and carbon dioxide, enters the regeneration device E3 for regeneration. The regenerated carbon dioxide S10 exits the regeneration device E3. Part of the regenerated lean liquor S4 is cooled by the lean liquor cooler E7 and returned to the desulfurization and carbon dioxide capture device E2 for reuse. The other part of the regenerated lean liquor S4 is input into the oxidation device E4 for oxidation. The oxidized regenerated lean liquor S5 is input into the primary evaporation crystallization device E5 for evaporation, forming evaporated crystals S13 which are discharged as solid waste.

[0074] Process parameter operation control:

[0075] 1) Denitrification and heat recovery unit E1, flue gas inlet operating pressure 15.0 kPa(G);

[0076] 2) The absorbent used in this process is a sodium carbonate solution with a mass concentration of 35%;

[0077] 3) The desulfurization and carbon dioxide capture device E2 adopts a sieve plate absorption tower. The liquid outlet rich liquid operating temperature of the desulfurization and carbon dioxide capture device E2 is 60℃, the gas-liquid volume ratio is 400:1, and the tower top operating pressure is 10kPa(G).

[0078] 4) The regeneration unit E3 adopts a sieve plate regeneration tower. The pH value (25℃) of the lean liquid S4 after regeneration at the liquid phase outlet of the regeneration unit E3 is controlled at 9.5, and the operating pressure is 10kPa(G).

[0079] 5) The proportion of the regenerated lean liquor S4 input to the oxidation unit E4 for oxidation accounts for 2.0% of the total volumetric flow rate of the regenerated lean liquor S4;

[0080] 6) The E5 evaporation crystallization device adopts single-effect evaporation in the single-stage evaporation crystallization process, with an operating temperature of 85℃;

[0081] 7) The lean liquid temperature output by the regenerated lean liquid cooler E7 is 42℃.

[0082] Table 2 Raw material conditions:

[0083]

[0084] Implementation results:

[0085] Carbon dioxide capture rate: 96%;

[0086] Carbon dioxide product purity: 99.5% (dry basis).

[0087] Example 3

[0088] use Figure 3The diagram shows the structure of an integrated flue gas desulfurization and carbon capture system.

[0089] Process flow: Flue gas S1 enters the denitrification and heat recovery unit E1 to complete NO removal. X After waste heat recovery, the denitrification flue gas S2 enters the desulfurization and carbon dioxide capture device E2, where it contacts the lean liquor S8 to complete the removal of sulfur dioxide and carbon dioxide. The denitrified flue gas S9 exits the desulfurization and carbon dioxide capture device E2. The rich liquor S3, which has absorbed sulfur dioxide and carbon dioxide, enters the regeneration device E3 for regeneration. The regenerated carbon dioxide S10 exits the regeneration device E3. Part of the regenerated lean liquor S4 is directly returned to the desulfurization and carbon dioxide capture device E2 for reuse, while the other part of the regenerated lean liquor S4 is input into the oxidation device E4 for oxidation. The oxidized regenerated lean liquor S5 is input into the primary evaporation crystallization device E5 for evaporation. During the evaporation crystallization process in the primary evaporation crystallization device E5, carbon dioxide gas S12 generated by the regeneration device S3 is introduced. The sodium bicarbonate-rich crystal material S14 formed in the primary evaporation crystallization device E5 is introduced into the rich liquor S3 for dissolution and then enters the regeneration device E3 for regeneration. The remaining solution S7 evaporated in the primary evaporation crystallization device E5 is sent to the secondary evaporation crystallization device E6 for evaporation crystallization to form sodium sulfate-rich crystals S11, which are discharged as solid waste.

[0090] Process parameter operation control:

[0091] 1) Denitrification and heat recovery unit E1, flue gas inlet operating pressure 10.0 kPa(G);

[0092] 2) The absorbent used in this process is a sodium carbonate solution with a mass concentration of 5%;

[0093] 3) The desulfurization and carbon dioxide capture device E2 adopts a sieve plate absorption tower. The liquid outlet rich liquid operating temperature of the desulfurization and carbon dioxide capture device E2 is 40℃, the gas-liquid volume ratio is 50:1, and the tower top operating pressure is 0kPa(G).

[0094] 4) The regeneration unit E3 adopts a sieve plate regeneration tower. The pH value (25℃) of the lean liquid S4 after regeneration at the liquid phase outlet of the regeneration unit E3 is controlled at 8.5, and the operating pressure is 5kPa(G).

[0095] 5) The proportion of the regenerated lean liquor S4 input into the oxidation unit E4 for oxidation accounts for 0.1% of the total volumetric flow rate of the regenerated lean liquor S4;

[0096] 6) The ratio of sodium carbonate mass concentration to sodium sulfate mass concentration in the liquid phase outlet solution of the primary evaporation crystallization unit E5 is 0.1;

[0097] 7) The evaporation and crystallization process of the E5 primary evaporation crystallization unit is achieved using mechanical vapor recompression technology, with an operating temperature of 65℃ and an operating pressure of 12kPa (absolute pressure).

[0098] 8) The secondary evaporation crystallization device E6 adopts single-effect evaporation in the evaporation crystallization process, with an operating temperature of 75℃;

[0099] 9) The lean liquid temperature output by the regenerated lean liquid cooler E7 is 42℃.

[0100] Table 3 Raw material conditions:

[0101]

[0102]

[0103] Implementation results:

[0104] Carbon dioxide capture rate: 95.5%;

[0105] Carbon dioxide product purity: 99.6% (dry basis).

[0106] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the present invention.

Claims

1. An integrated system for flue gas desulfurization and carbon capture, characterized by, The system comprises: a denitration and heat recovery device, a desulfurization and carbon dioxide capture device, a regeneration device, an oxidation device, an evaporative crystallization device, and a lean liquid cooler; the denitration and heat recovery device is in communication with the desulfurization and carbon dioxide capture device, the desulfurization and carbon dioxide capture device is in communication with the regeneration device, the material outlet of the regeneration device is in communication with the oxidation device and the lean liquid cooler, the oxidation device is in communication with the evaporative crystallization device, and the lean liquid cooler is in communication with the desulfurization and carbon dioxide capture device.

2. The integrated flue gas desulfurization and carbon capture system of claim 1, wherein, The number of the evaporative crystallization devices is one, two or more.

3. The integrated flue gas desulfurization and carbon capture system of claim 2, wherein, When the number of the evaporative crystallization devices is two or more, the evaporative crystallization devices are connected in series, the evaporative crystallization device in communication with the oxidation device is a primary evaporative crystallization device, and the primary evaporative crystallization device is also in communication with the pipeline between the material outlet of the regeneration device and the lean liquid cooler.

4. The integrated flue gas desulfurization and carbon capture system of claim 2, wherein, When the number of the evaporative crystallization devices is two or more, the evaporative crystallization devices are connected in series, the material outlet of the evaporative crystallization device in communication with the oxidation device is also in communication with the pipeline between the desulfurization and carbon dioxide capture device and the regeneration device, and the material inlet of the evaporative crystallization device is in communication with the regeneration device.

5. The integrated flue gas desulfurization and carbon capture system of claim 1, wherein, The operating pressure of the flue gas inlet of the denitration and heat recovery device is 2.0-15.0 kPa (G).

6. The integrated flue gas desulfurization and carbon capture system of claim 1, wherein, The desulfurization and carbon dioxide capture device contains an absorbent, and the absorbent is a sodium carbonate solution with a mass concentration of 5-35%.

7. The integrated flue gas desulfurization and carbon capture system of claim 1, wherein, The desulfurization and carbon dioxide capture device adopts an absorption tower, the operating temperature of the liquid phase outlet of the desulfurization and carbon dioxide capture device is 40-60℃, the gas-liquid volume ratio is 50-400:1, and the operating pressure is 0-10 kPa (G).

8. The integrated flue gas desulfurization and carbon capture system of claim 1, wherein, The pH value of the lean liquid after regeneration at the liquid phase outlet of the regeneration device is controlled to be 8.5-9.

5.

9. The integrated flue gas desulfurization and carbon capture system of claim 1, wherein, The ratio of the mass concentration of sodium carbonate to the mass concentration of sodium sulfate in the solution at the liquid phase outlet of the evaporative crystallization device is less than 1.

0.

10. The integrated flue gas desulfurization and carbon capture system of claim 1, wherein, The evaporative crystallization process in the evaporative crystallization device is at least one of direct evaporative crystallization, single-effect evaporation, multi-effect evaporation, multi-stage flash evaporation, and mechanical vapor recompression.

11. The integrated flue gas desulfurization and carbon capture system of claim 1, wherein, The lean liquid temperature output by the lean liquid cooler is ≯45℃.

12. An integrated flue gas desulfurization and carbon capture method, characterized by, The system comprises: The flue gas enters the denitration and heat recovery device to complete denitration X After heat recovery, the denitration flue gas enters the desulfurization and carbon dioxide capture device to contact with lean liquid, to complete the removal of sulfur dioxide and carbon dioxide, the flue gas after removal outputs the desulfurization and carbon dioxide capture device, the rich liquid absorbing sulfur dioxide and carbon dioxide enters the regeneration device for regeneration, the regenerated carbon dioxide outputs the regeneration device, part of the regenerated lean liquid is cooled by the lean liquid cooler E7 and then returns to the desulfurization and carbon dioxide capture device for reuse, and the other part of the regenerated lean liquid enters the oxidation device for oxidation, and the regenerated lean liquid after oxidation enters the evaporation crystallization device for evaporation.

13. The integrated flue gas desulfurization and carbon capture process according to claim 12, wherein, When the number of the evaporative crystallization devices is one, the regenerated lean liquid after oxidation is evaporated in the evaporative crystallization device to form evaporative crystals as solid waste.

14. The integrated flue gas desulfurization and carbon capture process according to claim 12, wherein, When the number of the evaporative crystallization devices is two or more, the regenerated lean liquid after oxidation is evaporated in the primary evaporative crystallization device to form a sodium carbonate-rich crystal material, the sodium carbonate-rich crystal material is dissolved with the lean liquid after regeneration and returned to the desulfurization and carbon dioxide capture device for reuse, and the remaining solution is evaporated in the secondary evaporative crystallization device to form a sodium sulfate-rich crystal as solid waste.

15. The integrated flue gas desulfurization and carbon capture process according to claim 12, wherein, When the evaporation crystallization device is two or more, the oxidized regenerated lean solution is evaporated in the primary evaporation crystallization device, carbon dioxide gas generated in the regeneration device is introduced in the primary evaporation crystallization device during the evaporation crystallization process, and the sodium bicarbonate-rich crystal material is formed in the primary evaporation crystallization device, the sodium bicarbonate-rich crystal material is introduced into the rich solution for dissolution, and the rich solution enters the regeneration device for regeneration, the remaining solution is evaporated in the secondary evaporation crystallization device for evaporation crystallization, and the sodium sulfate-rich crystal is formed as solid waste for discharge.

16. The integrated flue gas desulfurization and carbon capture process according to claim 12, wherein, The proportion of the regenerated lean solution input into the oxidation device accounts for 0.1-2% of the total volume flow of the regenerated lean solution.

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