System for producing halogens from flue-gas brine

Abstract

The present application relates to the technical field of halogen preparation, and particularly relates to a flue gas method halogen preparation system, which comprises a boiler, a flue gas purification unit, a purified brine unit, a bromine extraction unit, a nitrate preparation system, a high nitrate solution storage device, a chlorine storage device, and a caustic soda storage device, wherein the output end of the boiler is connected with the input end of the purification unit; the output end of the flue gas purification unit is connected with the input end of the bromine extraction unit and the input end of the purified brine unit, and the output end of the purified brine unit is connected with the nitrate preparation system, the high nitrate solution storage device, the chlorine storage device, and the caustic soda storage device; the caustic soda storage device is connected with the purified brine; the chlorine storage device is connected with the bromine extraction unit; the system constitutes preparation of various halogens as a whole and forms a local circulation unit between part of the system, so that the waste after production can be extracted and utilized again, the utilization rate of resources is improved, and the utilization rate of flue gas is improved.

Description

Technical Field

[0001] This invention relates to the field of halogen preparation technology, and in particular to a halogen preparation system for flue gas brine. Background Technology

[0002] Halogens are a class of nonmetallic elements, including fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). The preparation of these elements typically involves complex chemical reaction processes, such as electrolysis, chemical methods, and thermal decomposition. The preparation of halogens from flue gas brine is actually a staged process. First, the brine is purified using flue gas to remove impurity ions and improve its purity. Then, the purified brine is used as raw material to prepare the desired halogens through electrolysis, chemical methods, or thermal decomposition. However, existing halogen preparation systems produce only one type of halogen and have low efficiency in utilizing flue gas, resulting in low efficiency in flue gas recovery and utilization. Summary of the Invention

[0003] The technical problem this invention aims to solve is: in existing chlor-alkali industry ion-exchange membrane alkali production equipment, impurities in the brine deposit on the cathode side of the membrane cause mechanical damage and reduce current efficiency; if deposited within the membrane, they also increase the cell voltage. The effects of impurities are cumulative; even small amounts have a significant long-term impact, leading to high energy consumption and reduced membrane lifespan.

[0004] In addition to producing steam and electricity, thermal power plants also generate a large amount of flue gas, the main components of which are N2, O2, and NO. X SO X Flue gas contains CO2, H2O, and heat, which are directly emitted into the atmosphere, causing environmental pollution and wasting resources and energy. Currently, the utilization efficiency of flue gas is low. Therefore, in order to overcome the problem that the existing halogen preparation system produces only one type of halogen and has low efficiency in flue gas recovery and utilization, a halogen preparation system for brine using flue gas is provided.

[0005] The technical solution adopted by the present invention to solve its technical problem is: a halogen preparation system in brine by flue gas method, including a boiler, a flue gas purification unit, a brine purification unit, a bromine extraction unit, a nitrate production system, a high nitrate liquid storage device, a chlorine storage device, and a caustic soda storage device.

[0006] The boiler is used to generate flue gas, and the output end of the boiler is connected to the input end of the purification unit;

[0007] The output of the flue gas purification unit is connected to the input of the bromine extraction unit and the input of the brine purification unit.

[0008] The output of the brine purification unit is connected to the input of the nitrate production system, the input of the high-nitrate liquid storage device, the input of the chlorine storage device, and the input of the caustic soda storage device.

[0009] The output end of the caustic soda storage device is connected to the input end of the purified brine;

[0010] The output of the chlorine storage device is connected to the input of the bromine extraction unit;

[0011] The output of the high-nitrate liquid storage device is connected to the input of the bromine extraction unit. The design of the boiler, flue gas purification unit, brine purification unit, bromine extraction unit, nitrate production system, high-nitrate liquid storage device, chlorine storage device and caustic soda storage device constitutes a whole for the preparation of multiple halogens and makes some systems form a local circulation unit, so that the waste materials after production can be extracted and reused again, improving the utilization rate of resources and thus improving the utilization rate of flue gas.

[0012] To address the issue of low purification efficiency in the flue gas purification unit, the system further includes a denitrification and dust removal system, a desulfurization and dust removal system, and a compression system. The boiler output is connected to the input of the denitrification and dust removal system, the output of the denitrification and dust removal system is connected to the input of the desulfurization and dust removal system and the bromine extraction unit, the output of the desulfurization and dust removal system is connected to the input of the compression system, and the output of the compression system is connected to the input of the brine purification unit and the input of the bromine extraction unit.

[0013] To address the issue of low production efficiency in bromine extraction units when raw materials at different stages undergo the entire process, the bromine extraction unit further includes an acidification oxidation system, a hot blowing system, an absorption system, an oxidative distillation system, and a bromine storage device.

[0014] The output of the compression system is connected to the input of the acidification and oxidation system and the input of the hot blowing system.

[0015] The output end of the high-nitrate liquid storage device is connected to the input end of the acidification and oxidation system;

[0016] The output of the chlorine storage device is connected to the input of the acidification oxidation system and the input of the oxidative distillation system.

[0017] The output of the acidification oxidation system is connected to the input of the hot blowing system;

[0018] The output of the hot blowing system is connected to the input of the absorption system and the input of the nitrate production system.

[0019] The output of the absorption system is connected to the input of the oxidative distillation system;

[0020] The output of the oxidative distillation system is connected to the input of the acidification oxidation system and the input of the bromine storage device.

[0021] To address the issue of low purification efficiency in the brine purification unit, the brine purification unit further includes a purification system, a defoaming system, and a membrane filtration system.

[0022] The output of the compression system is connected to the input of the purification system;

[0023] The output of the purification system is connected to the input of the defoaming system;

[0024] The output of the defoaming system is connected to the input of the membrane filtration system.

[0025] The preparation system further includes an evaporation salt production system, the output end of the membrane filtration system is connected to the input end of the evaporation salt production system, and the output end of the evaporation salt production system is connected to the input end of the high-nitrate liquid storage device.

[0026] The preparation system further includes a nanofiltration system, with the output end of the membrane filtration system connected to the input end of the nanofiltration system, and the output end of the nanofiltration system connected to the nitrate production system, the caustic soda storage device, and the chlorine storage device.

[0027] The preparation system further includes an ion-exchange membrane electrolysis system, with the output end of the nanofiltration system connected to the input end of the ion-exchange membrane electrolysis system, and the output end of the ion-exchange membrane electrolysis system connected to a caustic soda storage device and a chlorine storage device.

[0028] To address the issue of some halogen remaining in the waste, the system further includes connecting the output of the caustic soda storage device to the input of the purification system.

[0029] The beneficial effects of this invention are as follows: This invention provides a halogen preparation system for brine using flue gas. Through the design of a boiler, a flue gas purification unit, a brine purification unit, a bromine extraction unit, a nitrate production system, a high-nitrate liquid storage device, a chlorine storage device, and a caustic soda storage device, it can prepare multiple halogens as a whole and make some systems form a local circulation unit, thereby enabling the extraction and reuse of waste materials after production, improving resource utilization, and thus improving the utilization rate of flue gas.

[0030] The bromine extraction yield from concentrated nitrate solution is higher than 90%, which reduces impurities in brine and lowers the energy consumption of ion-exchange membrane alkali production equipment. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] Figure 1 This is a schematic diagram of the structure of the present invention.

[0033] In the diagram: 1. Boiler; 2. Denitrification and dust removal system; 3. Desulfurization and dust removal system; 4. Compression system; 5. Acidification and oxidation system; 6. Hot blowing system; 7. Absorption system; 8. Oxidative distillation system; 9. Bromine storage device; 10. Purification system; 11. Defoaming system; 12. Membrane filtration system; 13. Evaporation and salt production system; 14. Nanofiltration system; 15. Ion-exchange membrane electrolysis system; 16. Nitrate production system; 17. High-nitrate liquid storage device; 18. Chlorine storage device; 19. Caustic soda storage device. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0035] like Figure 1 This is a schematic diagram of the structure of the present invention. A halogen preparation system for brine using flue gas method includes a boiler 1, a flue gas purification unit, a brine purification unit, a bromine extraction unit, a nitrate production system 16, a high-nitrate liquid storage device 17, a chlorine storage device 18, and a caustic soda storage device 19. It can form a system for the preparation of multiple halogens as a whole and enable some systems to form a local circulation unit, thereby enabling the extraction and reuse of waste materials after production, improving resource utilization, and thus improving the utilization rate of flue gas.

[0036] Boiler 1 is used to generate flue gas. The output end of boiler 1 is connected to the input end of the purification unit. The main components of the flue gas combustion products are N2, O2, CO2, SOx, and NO. X Dust, water vapor, and heat;

[0037] The output of the flue gas purification unit is connected to the input of the bromine extraction unit and the input of the brine purification unit. The flue gas purification unit includes a denitrification and dust removal system 2, a desulfurization and dust removal system 3, and a compression system 4.

[0038] Denitrification and dust removal system 2 is used to remove NO X Dust is purified into flue gas 1. The main components of purified flue gas 1 are N2, O2, CO2, and SO2 (800-1400 mg / m³). 3 ), water vapor, flue gas temperature (75-85℃), trace amounts of NO X The denitrification and dust removal system 2 uses ammonia (NH3) as a reducing agent. In the presence of a catalyst, it removes NO from the flue gas. X The nitrogen is reduced to N2 and water, achieving a denitrification rate of 80-90%. The main reaction principle is as follows:

[0039] 4NH3 + 4NO + O2 = 4N2 + 6H2O

[0040] 4NH3 + 2NO2 + O2 = 3N2 + 6H2O;

[0041] The desulfurization and dust removal system 3 is used to remove SOx and dust to obtain purified flue gas 2. The main components of purified flue gas 2 are N2, O2, CO2, water vapor, heat (50-70℃), and trace amounts of NO. X and SO2 (20-45 mg / m³) 3 The desulfurization and dust removal process uses wet calcium carbonate desulfurization, which mainly converts calcium carbonate into calcium sulfate through three steps: absorption, neutralization, and oxidation. The specific steps are as follows:

[0042] Absorption: SO2 + H2O → H2SO3

[0043] Neutralization: CaCO3 + H2SO3 → CaSO3 + CO2↑ + H2O

[0044] Oxidation: 2CaSO3 + O2 → 2CaSO4↓;

[0045] Compression system 4 is used to purify flue gas to obtain compressed flue gas, removing trace amounts of SOx and NO. X The main components of the compressed flue gas are N2, O2, CO2, moisture, and flue gas temperature (30-45℃), with trace amounts of NO and SO2. The main reaction principle of the compression system 4 for further purification of the flue gas is as follows:

[0046] 4NO + 3O₂ + 2H₂O → 4HNO₃

[0047] SO2 + H2O → H2SO3

[0048] 2HNO3+3H2SO3→3H2SO4+2NO↑+H2O;

[0049] The output end of boiler 1 is connected to the input end of denitrification and dust removal system 2. The output end of denitrification and dust removal system 2 is connected to the input end of desulfurization and dust removal system 3 and the bromine extraction unit (i.e., the input end of the absorption system). The output end of denitrification and dust removal system 2 is connected to the input end of absorption system 7. The output end of desulfurization and dust removal system 3 is connected to the input end of compression system 4. The output end of compression system 4 is connected to the input end of purification brine unit (i.e., the input end of purification system 10) and the input end of bromine extraction unit (i.e., the input end of acidification and oxidation system 5 and the input end of hot blowing system 6).

[0050] The brine purification unit includes a purification system 10, a defoaming system 11, and a membrane filtration system 12;

[0051] Purification system 10 is used to purify brine using the caustic soda-flue gas method, removing calcium, magnesium, and iron from the brine. The purification system 10 produces purified brine. The main reaction principle of brine purification (purification system 10) is as follows:

[0052] Mg 2 ++2OH-→Mg(OH)2↓

[0053] Fe 3 ++3OH-→Fe(OH)3↓

[0054] CO2 + 2OH- → H2O + CO32- 2 -

[0055] Ca 2 ++CO3 2 -→CaCO3↓;

[0056] The defoaming system 11 is used to eliminate residual flue gas to prevent corrosion of the salt production equipment; the membrane filtration system 12 is used to remove solid waste generated during the purification process. The membrane filtration system produces refined brine with SS ≤ 1.2 mg / L.

[0057] The output of the brine purification unit is connected to the input of the nitrate production system 16, the input of the high nitrate liquid storage device 17, the input of the chlorine storage device 18, and the input of the caustic soda storage device 19. The nitrate production system 16 is used to prepare calcium sulfate (containing water).

[0058] The preparation system also includes a nanofiltration system 14. The output end of the membrane filtration system 12 is connected to the input end of the nanofiltration system 14. The output end of the nanofiltration system 14 is connected to the nitrate production system 16, the caustic soda storage device 19, and the chlorine storage device 18. The nanofiltration system 14 is used to remove sulfate ions from the brine. The nanofiltration system yields low-nitrate refined brine, which contains SO4. 2 -≤1.0mg / L, chlorine storage device 18 is used to store chlorine.

[0059] The preparation system also includes an evaporation salt production system 13, the output end of the membrane filtration system 12 is connected to the input end of the evaporation salt production system 13, the output end of the evaporation salt production system 13 is connected to the input end of the high-nitrate liquid storage device 17, and the evaporation salt production system 13 is used for salt production.

[0060] The preparation system also includes an ion-exchange membrane electrolysis system 15. The output end of the nanofiltration system 14 is connected to the input end of the ion-exchange membrane electrolysis system 15. The output end of the ion-exchange membrane electrolysis system 15 is connected to the caustic soda storage device 19 and the chlorine storage device 18. The ion-exchange membrane electrolysis system 15 is used to prepare caustic soda, chlorine, and hydrogen. The main reaction principle of the ion-exchange membrane electrolysis system 15 is as follows:

[0061] 2NaCl+2H2O→Cl2↑+H2↑+2NaOH.

[0062] The output end of the caustic soda storage device 19 is connected to the input end of the purification system 10.

[0063] The output of the compression system 4 is connected to the input of the purification system 10;

[0064] The output of the purification system 10 is connected to the input of the defoaming system 11;

[0065] The output of the defoaming system 11 is connected to the input of the membrane filtration system 12.

[0066] The output end of the caustic soda storage device 19 is connected to the input end of the purified brine;

[0067] The output of the chlorine storage device 18 is connected to the input of the bromine extraction unit. The chlorine storage device 18 is used to store caustic soda solution.

[0068] The output of the high-nitrate liquid storage device 17 is connected to the input of the bromine extraction unit.

[0069] The bromine extraction unit includes an acidification oxidation system 5, a hot blowing system 6, an absorption system 7, an oxidative distillation system 8, and a bromine storage device 9. The acidification oxidation system 5 is used for oxidative bromine production, removing bromide ions from concentrated high-nitrate solutions. The main reaction principle of the bromine acidification oxidation system 5 is as follows:

[0070] Cl₂ + 2Br⁻ → 2Cl⁻ + Br₂;

[0071] The hot blowing system 6 is used to compress and purify flue gas 2 by hot blowing out bromine; the absorption system 7 is used to purify flue gas 1 by hot absorption of bromine to generate bromide ions and concentrate bromide ions. The main reaction principle of the absorption system 7 is as follows:

[0072] Br2 + SO2 + 2H2O → H2SO4 + 2HBr;

[0073] Oxidative distillation system 8 is used for the oxidation of bromine and the evaporation of bromine. The main reaction principle of oxidative distillation system 8 is as follows:

[0074] Cl₂ + 2Br⁻ → 2Cl⁻ + Br₂;

[0075] The output of the compression system 4 is connected to the input of the acidification and oxidation system 5 and the input of the hot blowing system 6;

[0076] The output end of the high-nitrate liquid storage device 17 is connected to the input end of the acidification and oxidation system 5;

[0077] The output of the chlorine storage device 18 is connected to the input of the acidification oxidation system 5 and the input of the oxidation distillation system 8;

[0078] The output of the acidification oxidation system 5 is connected to the input of the hot blowing system 6;

[0079] The output of the hot blowing system 6 is connected to the input of the absorption system 7 and the input of the nitrate production system 16;

[0080] The output of the absorption system 7 is connected to the input of the oxidative distillation system 8;

[0081] The output of the oxidative distillation system 8 is connected to the input of the acidification oxidation system 5 and the input of the bromine storage device 9.

[0082] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A halogen preparation system for brine using flue gas, characterized in that, It includes a boiler (1), a flue gas purification unit, a brine purification unit, a bromine extraction unit, a nitrate production system (16), a high-nitrate liquid storage device (17), a chlorine storage device (18), and a caustic soda storage device (19). The boiler (1) is used to generate flue gas, and the output end of the boiler (1) is connected to the input end of the purification unit; The output end of the flue gas purification unit is connected to the input end of the bromine extraction unit and the input end of the brine purification unit. The flue gas purification unit includes a denitrification and dust removal system (2), a desulfurization and dust removal system (3), and a compression system (4). The output end of the boiler (1) is connected to the input end of the denitrification and dust removal system (2). The output end of the denitrification and dust removal system (2) is connected to the input end of the desulfurization and dust removal system (3) and the bromine extraction unit. The output end of the desulfurization and dust removal system (3) is connected to the input end of the compression system (4). The output end of the compression system (4) is connected to the input end of the brine purification unit and the input end of the bromine extraction unit. The output end of the purified brine unit is connected to the input end of the nitrate production system (16), the input end of the high nitrate liquid storage device (17), the input end of the chlorine storage device (18), and the input end of the caustic soda storage device (19). The bromine extraction unit includes an acidification oxidation system (5), a hot blowing system (6), an absorption system (7), an oxidative distillation system (8), and a bromine storage device (9). The output end of the compression system (4) is connected to the input end of the acidification oxidation system (5) and the input end of the hot blowing system (6); The output end of the high-nitrate liquid storage device (17) is connected to the input end of the acidification and oxidation system (5); The output end of the chlorine storage device (18) is connected to the input end of the acidification oxidation system (5) and the input end of the oxidative distillation system (8); The output end of the acidification oxidation system (5) is connected to the input end of the hot blowing system (6); The output end of the hot blowing system (6) is connected to the input end of the absorption system (7) and the input end of the nitrate production system (16); The output end of the absorption system (7) is connected to the input end of the oxidative distillation system (8), and the output end of the denitrification and dust removal system (2) is connected to the input end of the absorption system (7). The output of the oxidative distillation system (8) is connected to the input of the acidification oxidation system (5) and the input of the bromine storage device (9); The output end of the caustic soda storage device (19) is connected to the input end of the purified brine; The output of the chlorine storage device (18) is connected to the input of the bromine extraction unit; The output end of the high-nitrate liquid storage device (17) is connected to the input end of the bromine extraction unit.

2. The halogen preparation system for brine using flue gas as described in claim 1, characterized in that: The brine purification unit includes a purification system (10), a defoaming system (11), and a membrane filtration system (12). The output end of the compression system (4) is connected to the input end of the purification system (10); The output end of the purification system (10) is connected to the input end of the defoaming system (11); The output end of the defoaming system (11) is connected to the input end of the membrane filtration system (12).

3. The halogen preparation system for brine using flue gas as described in claim 2, characterized in that: The preparation system also includes an evaporation salt production system (13), the output end of the membrane filtration system (12) is connected to the input end of the evaporation salt production system (13), and the output end of the evaporation salt production system (13) is connected to the input end of the high-nitrate liquid storage device (17).

4. The halogen preparation system for brine using flue gas as described in claim 2, characterized in that: The preparation system also includes a nanofiltration system (14), the output end of the membrane filtration system (12) is connected to the input end of the nanofiltration system (14), and the output end of the nanofiltration system (14) is connected to the nitrate production system (16), the caustic soda storage device (19) and the chlorine storage device (18).

5. The halogen preparation system for brine using flue gas as described in claim 4, characterized in that: The preparation system also includes an ion-exchange membrane electrolysis system (15), the output end of the nanofiltration system (14) is connected to the input end of the ion-exchange membrane electrolysis system (15), and the output end of the ion-exchange membrane electrolysis system (15) is connected to the caustic soda storage device (19) and the chlorine storage device (18).

6. The halogen preparation system for brine using flue gas as described in claim 2, characterized in that: The output end of the caustic soda storage device (19) is connected to the input end of the purification system (10).

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