System for preparing halogen in brine by flue gas method

Abstract

The invention relates to the technical field of halogen preparation, in particular to a system for preparing halogen in brine through a flue gas method, which comprises a boiler, a flue gas purification unit, a brine purification unit, a bromine extraction unit, a nitrate preparation system, a high-nitrate liquid storage device, a chlorine storage device and a caustic soda storage device, and 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 brine purification unit; the output end of the brine purification unit is connected with the nitrate preparation system, the high-nitrate liquid storage device, the chlorine storage device and the caustic soda storage device; the caustic soda storage device is connected to the purified brine; the chlorine storage device is connected to the bromine extraction unit; according to the invention, multiple halogens are prepared on the whole, and partial circulating units are formed among a part of systems, so that waste materials after production can be extracted and utilized again, the utilization rate of resources is improved, and the utilization rate of flue gas can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of halogen preparation, in particular to a halogen preparation system in brine using a flue gas method. Background Art

[0002] Halogens are a class of non-metallic elements, including fluorine (F), chlorine (Cl), bromine (Br), iodine (I), etc. The preparation of these elements usually involves complex chemical reaction processes, such as electrolysis, chemical method, thermal decomposition method, etc. The preparation of halogens in flue gas brine is actually a staged process. First, the brine is purified by the flue gas method to remove the impurity ions therein and improve the purity of the brine. Then, the purified brine is used as a raw material to prepare the required halogens by electrolysis, chemical method or thermal decomposition. However, the halogen preparation system in the prior art has a single halogen and low efficiency in the utilization of flue gas, and therefore, low efficiency in flue gas recovery. Summary of the invention

[0003] The technical problem to be solved by the present invention is: in order to overcome the problem that the impurities in the brine are deposited on the cathode side surface of the membrane in the chlor-alkali industry in the prior art, which will cause mechanical damage to the membrane and reduce the current efficiency; if they are deposited in the membrane, the cell voltage will increase. The impact caused by impurities is cumulative. Even if the amount of impurities is not large, its long-term impact is large, the energy consumption is high, and the membrane life is affected.

[0004] In addition to producing steam and electricity, thermal power plants also produce a large amount of flue gas. The main components of flue gas are N2, O2, NO X 、SO X , CO2, H2O, and heat are directly discharged into the atmosphere, causing environmental pollution and wasting resources and energy. The current flue gas utilization efficiency is low. Therefore, in order to overcome the problem that the halogen preparation system in the prior art prepares a single halogen and has low efficiency in flue gas recovery and utilization, a flue gas brine halogen preparation system is provided.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a flue gas method brine halogen preparation system, including a boiler, a flue gas purification unit, a brine purification unit, a bromine extraction unit, a nitrate preparation 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 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.

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

[0009] The output of the caustic soda storage device is connected to the input 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 end of the high nitrate liquid storage device is connected to the input end of the bromine extraction unit. Through the design of the boiler, the flue gas purification unit, the brine purification unit, the bromine extraction unit, the nitrate making system, the high nitrate liquid storage device, the chlorine storage device and the caustic soda storage device, a variety of halogens are prepared as a whole and local circulation units are formed between some systems, so that the waste after production can be extracted and utilized again, thereby improving the utilization rate of resources and thus improving the utilization rate of flue gas.

[0012] In order to solve the problem of low purification efficiency of the flue gas purification unit, the flue gas purification unit further includes a denitrification and dust removal system, a desulfurization and dust removal system and a compression system, the output end of the boiler is connected to the input end of the denitrification and dust removal system, the output end of the denitrification and dust removal system is connected to the input end of the desulfurization and dust removal system and the bromine extraction unit, the output end of the desulfurization and dust removal system is connected to the input end of the compression system, and the output end of the compression system is connected to the input end of the brine purification unit and the input end of the bromine extraction unit.

[0013] In order to solve the problem of low production efficiency of the bromine extraction unit for raw materials at different stages if the whole process is carried out, the bromine extraction unit further includes an acidification oxidation system, a hot blowing system, an absorption system, an oxidation distillation system and a bromine storage device.

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

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

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

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

[0018] The output end of the hot blowing system is connected to the input end of the absorption system and the input end of the nitrate making system;

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

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

[0021] In order to solve the problem of low purification efficiency of the brine purification unit, the brine purification unit further includes a purification system, a defoaming system and a membrane filtration system;

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

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

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

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

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

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

[0028] In order to solve the problem that some halogens still remain in the waste, the output end of the caustic soda storage device is further connected to the input end of the purification system.

[0029] The beneficial effects of the present invention are as follows: the flue gas method brine halogen preparation system provided by the present invention, through the design of boiler, flue gas purification unit, brine purification unit, bromine extraction unit, nitrate preparation system, high nitrate liquid storage device, chlorine storage device and caustic soda storage device, constitutes the preparation of multiple halogens as a whole and makes a part of the system constitute a local circulation unit, so that the waste after production can be extracted and utilized again, the utilization rate of resources can be improved, and thus the utilization rate of flue gas can be improved;

[0030] The yield of bromine from concentrated nitrate solution is higher than 90%, which reduces impurities in brine and reduces the high energy consumption of the operation process of ion membrane alkali making equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0032] Figure 1 It is a structural schematic diagram of the present invention.

[0033] In the figure: 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. Oxidation distillation system, 9. Bromine storage device, 10. Purification system, 11. Defoaming system, 12. Membrane filtration system, 13. Evaporation salt production system, 14. Nanofiltration system, 15. Ion membrane electrolysis system, 16. Nitrate production system, 17. High nitrate solution storage device, 18. Chlorine storage device, 19. Caustic soda storage device. DETAILED DESCRIPTION

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

[0035] like Figure 1 The present invention is a schematic diagram of a halogen preparation system in brine by flue gas method, comprising a boiler 1, a flue gas purification unit, a brine purification unit, a bromine extraction unit, a nitrate preparation system 16, a high nitrate liquid storage device 17, a chlorine storage device 18 and a caustic soda storage device 19, which can constitute the preparation of multiple halogens as a whole and make a part of the system constitute a local circulation unit, so that the waste after production can be extracted and utilized again, and the utilization rate of resources can be improved, thereby 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 flue gas are N2, O2, CO2, SOx, NO X , dust, water vapor, heat;

[0037] 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 denitration 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 to obtain purified flue gas 1, the main components of purified flue gas 1 are N2, O2, CO2, SO2 (800-1400mg / m 3 ), water vapor, flue gas temperature (75-85°C), trace NO X The denitrification and dust removal system 2 uses ammonia (NH3) as a reducing agent to reduce NO in the flue gas in the presence of a catalyst. X Reduction to N2 and generated water, denitrification rate reaches 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 the purified flue gas 2 are N2, O2, CO2, water vapor, heat (50-70°C), trace NO X and SO2 (20-45 mg / m 3 ), desulfurization and dust removal adopts calcium carbonate wet desulfurization, which mainly converts calcium carbonate into calcium sulfate through the following 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] The compression system 4 is used to purify the flue gas to obtain compressed flue gas and remove trace amounts of SOx and NO X The main components of the compressed flue gas are N2, O2, CO2, moisture, flue gas temperature (30-45°C), trace amounts of NO and SO2. The main reaction principle of the compression system 4 to purify the flue gas again is as follows:

[0046] 4NO+3O2+2H2O→4HNO3

[0047] SO2+H2O→H2SO3

[0048] 2HNO3+3H2SO3→3H2SO4+2NO↑+H2O;

[0049] 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 (i.e., the input end of the absorption system), the output end of the denitrification and dust removal system 2 is connected to the input end of the absorption system 7, the output end of the desulfurization and dust removal system 3 is connected to the input end of the compression system 4, and the output end of the compression system 4 is connected to the input end of the brine purification unit (i.e., the input end of the purification system 10) and the input end of the bromine extraction unit (i.e., the input end of the acidification and oxidation system 5 and the input end of the 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] The purification system 10 is used to purify brine by the caustic soda-flue gas method to remove calcium, magnesium and iron from the brine. The purification system 10 obtains 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+CO3 2 -

[0055] Ca 2 ++CO3 2 -→CaCO3↓;

[0056] The defoaming system 11 is used to eliminate residual flue gas to prevent corrosion of salt-making equipment; the membrane filtration system 12 is used to remove solid waste generated during the purification process, and the membrane filtration system obtains refined brine, and SS in the refined brine is ≤1.2mg / L;

[0057] The output end of the brine purification unit is connected to the input end of the nitrate making 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 nitrate making 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 system 16, the caustic soda storage device 19 and the chlorine storage device 18. The nanofiltration system 14 is used to remove sulfate from the brine. The nanofiltration system obtains low-nitrate refined brine, low-nitrate refined brine SO4 2 -≤1.0mg / L, the chlorine storage device 18 is used to store chlorine.

[0059] The preparation system also includes an evaporative salt-making system 13. The output end of the membrane filtration system 12 is connected to the input end of the evaporative salt-making system 13. The output end of the evaporative salt-making system 13 is connected to the input end of the high nitrate solution storage device 17. The evaporative salt-making system 13 is used to make salt.

[0060] The preparation system also includes an ion membrane electrolysis system 15, the output end of the nanofiltration system 14 is connected to the input end of the ion membrane electrolysis system 15, the output end of the ion membrane electrolysis system 15 is connected to a caustic soda storage device 19 and a chlorine storage device 18, and the ion membrane electrolysis system 15 is used to prepare caustic soda, chlorine, and hydrogen. The main reaction principle of the ion 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 end of the compression system 4 is connected to the input end of the purification system 10;

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

[0065] The output end of the defoaming system 11 is connected to the input end 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 end of the chlorine storage device 18 is connected to the input end of the bromine extraction unit, and the chlorine storage device 18 is used to store caustic soda solution;

[0068] The output end of the high nitrate solution storage device 17 is connected to the input end 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 oxidation distillation system 8 and a bromine storage device 9. The acidification oxidation system 5 is used to oxidize bromine and remove bromide ions in the concentrated high nitrate solution. 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 the flue gas 2 to blow out bromine by heat; the absorption system 7 is used to purify the flue gas 1 to absorb bromine by heat 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] The oxidation distillation system 8 is used to produce bromine by oxidation and bromine by evaporation. The main reaction principle of the oxidation distillation system 8 is as follows:

[0074] Cl2+2Br-→2Cl-+Br2;

[0075] 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;

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

[0077] 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 oxidation distillation system 8;

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

[0079] 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 making system 16;

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

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

[0082] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A system for preparing halogen from brine using a flue gas method, characterized in that: It comprises 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 fume purification unit is connected to the input end of the bromine extraction unit and the input end of the brine purification unit. The output end of the brine purification 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 output end of the caustic soda storage device (19) is connected to the input end of the purified brine; The output end of the chlorine storage device (18) is connected to the input end of the bromine extraction unit; The output end of the high nitrate solution storage device (17) is connected to the input end of the bromine extraction unit.

2. The halogen preparation system in brine by flue gas method according to claim 1, characterized in that: The flue gas purification unit comprises a denitration 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 denitration and dust removal system (2); the output end of the denitration and dust removal system (2) is connected to the input end of the desulfurization and dust removal system (3) and a 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.

3. The halogen preparation system in brine by flue gas method according to claim 2, characterized in that: The bromine extraction unit comprises an acidification oxidation system (5), a hot blowing system (6), an absorption system (7), an oxidation 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 solution storage device (17) is connected to the input end of the acidification 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 oxidation 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 making system (16); The output end of the absorption system (7) is connected to the input end of the oxidation distillation system (8), and the output end of the denitration and dust removal system (2) is connected to the input end of the absorption system (7); The output end of the oxidation distillation system (8) is connected to the input end of the acidification oxidation system (5) and the input end of the bromine storage device (9).

4. The halogen preparation system in brine by flue gas method according to claim 2, characterized in that: The brine purification unit comprises 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).

5. The system for preparing halogen from brine by flue gas method as claimed in claim 4, characterized in that: The preparation system also includes an evaporative salt-making system (13), the output end of the membrane filtration system (12) is connected to the input end of the evaporative salt-making system (13), and the output end of the evaporative salt-making system (13) is connected to the input end of the high nitrate solution storage device (17).

6. The system for preparing halogen from brine by flue gas method according to claim 4, 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 a nitrate production system (16), a caustic soda storage device (19) and a chlorine storage device (18).

7. The halogen preparation system in brine by flue gas method according to claim 6, characterized in that: The preparation system also includes an ion membrane electrolysis system (15), the output end of the nanofiltration system (14) is connected to the input end of the ion membrane electrolysis system (15), and the output end of the ion membrane electrolysis system (15) is connected to a caustic soda storage device (19) and a chlorine storage device (18).

8. The system for preparing halogen from brine by flue gas method as claimed in claim 4, 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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