CN111362343A - Method and equipment for extracting bromine from seawater by air blowing method - Google Patents
Method and equipment for extracting bromine from seawater by air blowing method Download PDFInfo
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- CN111362343A CN111362343A CN201811604466.7A CN201811604466A CN111362343A CN 111362343 A CN111362343 A CN 111362343A CN 201811604466 A CN201811604466 A CN 201811604466A CN 111362343 A CN111362343 A CN 111362343A
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B7/00—Halogens; Halogen acids
- C01B7/09—Bromine; Hydrogen bromide
- C01B7/096—Bromine
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/12—Halogens or halogen-containing compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/08—Seawater, e.g. for desalination
Abstract
The invention discloses a method and equipment for extracting bromine from seawater by using an air blowing method, wherein sulfuric acid and chlorine are introduced into the seawater to react bromide ions into free bromine; introducing raw material liquid containing free bromine from a blow-off tower, spraying downwards through a liquid distributor, introducing air from the lower part of the blow-off tower, and carrying out countercurrent contact on the air and the raw material liquid containing free bromine in the blow-off tower; the air carrying with the free bromine, the absorption liquid circulated from the bottom of the absorption tower and the externally introduced sulfur dioxide gas are jointly introduced into the absorption tower from the top of the absorption tower and then react to generate the absorption liquid containing the hydrobromic acid. The absorption liquid is discharged from the bottom of the absorption tower and circularly pumped into the top of the absorption tower through a pump, the air without free bromine is discharged from the lower part of the absorption tower, and the air is sent to a blow-off tower for recycling after entrained liquid foam is removed. And (4) sending the finished liquid to a distillation tower for reoxidation, and then obtaining liquid bromine after distillation, condensation and refining. The invention is suitable for the reconstruction of the existing bromine extraction device or the new construction of the bromine extraction device, effectively reduces the bromine extraction energy consumption, reduces the investment and improves the economic benefit.
Description
Technical Field
The invention relates to a bromine extraction technology, in particular to a bromine extraction method and equipment which take seawater as a raw material and mainly adopt regular packing.
Background
Bromine is widely used in the industries of pesticide, medicine, petroleum, fuel and the like, and is one of the basic chemical raw materials for producing flame retardants, fire extinguishing agents and photosensitive materials. China mainly uses Shandong underground brine as a raw material and adopts an air blowing method to extract bromine, for example, an authorized patent 201210524036.X provides a method for extracting bromine in brine. However, as the total amount and grade of underground brine are reduced day by day, the increasing demand of bromine in China cannot be met only by extracting bromine from brine. On the other hand, brine is easy to precipitate salts such as calcium sulfate and the like to be attached to the surface of the filler or block the pore channels of the filler due to a large amount of impurities and high salt concentration. Therefore, the traditional bromine extraction device adopts a polypropylene stepped ring as a packing because the random packing is easy to take out and refill. However, the random packing layer formed by a plurality of monomer cascade ring packing has the defects of small porosity and irregular gas-liquid flow path, the gas-liquid contact in the packed tower, particularly the blowing-out tower, is insufficient, and the back-mixing phenomena of channeling, wall flow and the like exist, so that the yield is not high, and 120: the gas-liquid ratio of more than 1, the pressure drop of the packing layer is large, and the energy consumption is high.
Disclosure of Invention
Aiming at the defects of increasingly reduced bromine resource sources and high bromine extraction energy consumption in the existing bromine extraction industry, the invention provides a method and equipment for extracting bromine from seawater (namely the method and equipment for extracting bromine from seawater by using an air blowing method), which can fully utilize the advantages of low salt concentration of seawater, clean water quality, no scaling and large total bromine storage amount to replace the original underground brine as a novel bromine resource source, and simultaneously fully utilize the advantages of large specific surface area of regular packing, high void ratio, reduced unit pressure, full gas-liquid two-phase contact and high mass transfer efficiency to replace a ladder ring in the traditional bromine extraction packing tower, and carry out matching optimization on tower internals such as a liquid distributor, a gas distributor and the like, thereby effectively reducing the bromine extraction energy consumption and improving the yield of a single tower. The new tower can reduce the total tower height, and the old tower can improve the productivity and reduce the unit bromine extraction energy consumption without changing other matching processes by adopting the process for technical transformation.
The technical purpose of the invention is realized by the following technical scheme.
The equipment for extracting bromine from seawater by using an air blowing method comprises a blowing tower, an absorption tower and a foam capturing tower, wherein:
the seawater raw material liquid is pumped by a raw material liquid pump and then is conveyed to the top of a blow-off tower through a pipeline, a sulfuric acid pipeline and a chlorine pipeline are sequentially connected in the pipeline between the raw material liquid pump and the top of the blow-off tower, a blow-off tower liquid distributor, a blow-off tower packing layer and a gas distributor are sequentially arranged in the blow-off tower from top to bottom, a blow-off tower purified air inlet is arranged on the side of the lower part of the blow-off tower, a blow-off tower liquid outlet is arranged at the bottom of the blow-off tower, the top of the blow-off tower is connected with an absorption tower top pipeline, and a sulfur dioxide gas pipeline and an absorption liquid pipeline containing hydrobromic acid are arranged at the;
an absorption tower liquid distributor and an absorption tower filler layer are sequentially arranged in the absorption tower from top to bottom; an absorption tower absorption liquid outlet is arranged at the bottom of the absorption tower, an absorption tower air outlet is arranged on the absorption tower between the absorption tower absorption liquid outlet and the absorption tower packing layer, the absorption tower absorption liquid outlet is connected with an absorption liquid inlet of an absorption liquid storage tank through a pipeline, and the absorption tower air outlet is connected with a foam capturing tower gas inlet through a pipeline; the bottom of the absorption liquid storage tank is provided with an absorption liquid outlet of the absorption liquid storage tank and a finished liquid outlet of the absorption liquid storage tank, the finished liquid outlet of the absorption liquid storage tank is connected with the distillation tower through a pipeline, the absorption liquid outlet of the absorption liquid storage tank is connected with a circulating absorption liquid inlet of the absorption tower through a pipeline, an absorption liquid circulating pump is arranged in the pipeline, and the finished liquid outlet of the absorption liquid storage tank is sent to the distillation tower through the pipeline;
the foam catching tower is internally provided with a packing layer of the foam catching tower, the top of the foam catching tower is provided with a gas outlet of the foam catching tower and is connected with a fan inlet of a fan through a pipeline, and the fan outlet is connected with a purified air inlet of the blow-out tower through a pipeline.
In the technical scheme, the top of the outer part of the absorption tower is provided with an inlet of air containing free bromine, a sulfur dioxide gas inlet and a circulating absorption liquid inlet.
In the technical scheme, the hydrobromic acid-containing absorption liquid pipeline is arranged on the side of the upper part of the absorption tower; an absorption liquid inlet is arranged between the bottom and the top of the absorption liquid storage tank; the gas inlet of the foam catching tower is arranged at the side of the lower part of the foam catching tower.
In the above-described embodiment, a detection device is provided in the absorbing liquid storage tank to detect the concentration of the hydrobromic acid-containing absorbing liquid a7 (bromide ion concentration).
In the technical scheme, the upper part of the blow-out tower is provided with an emptying pipeline.
In the technical scheme, the blowing-out tower, the absorption tower and the foam capturing tower are all filled with regular packing, and the distillation tower is filled with regular packing or random packing. The equipment and the filler are all non-metallic materials resistant to bromine, acid and chlorine corrosion. Regular packing is filled in the blow-out tower, the absorption tower and the foam catching tower. The regular packing is in the form of orifice plate corrugated packing, pulse packing, wire mesh corrugated packing or other types and specifications of regular packing, all of which are subjected to surface treatment, and the contact angle after the treatment is less than 120 degrees, preferably 80-100 degrees. The packing layer can be filled with one kind of structured packing, and can also be filled with various kinds of structured packing or the same kind of structured packing with different models. In principle, the lower part of the packing layer is regular packing with large void ratio and small surface area, which can be used for supporting the upper packing and also can be used as a gas distributor; the higher the specific surface area, the more fillers are selected. But the height of the minimum specific surface area at the bottommost part is not more than 1 m, the height of the minimum specific surface area at the middle part is not less than 4 m, for example, the bottom layer is 1 m of structured packing with the small specific surface area, and the top layer is 4 m with the large specific surface area; or the bottom layer is regular packing with small specific surface area of 1 meter, the middle part is regular packing with large specific surface area of 3 meters, and the top part is regular packing with larger specific surface area of 0.5 meter.
In the technical scheme, the packing layer of the blow-off tower is not higher than 6 meters, and the packing layers of the absorption tower and the mist capturing tower are not higher than 4 meters, so that segmentation is not needed.
In the technical scheme, the liquid distributor at the top of the blowing tower is in a groove type or a tube array type, wherein the tube array type nozzle can be in a butterfly type or a spiral type, and the number of spraying points is more than 20 points/square meter. The gas distributor inside the blow-off column is in the form of a flat surface, such as a grid. The liquid distributor at the top of the absorption tower is a groove type or a tube array type, wherein a butterfly type or a spiral type nozzle can be selected as the tube array type nozzle, and the number of spraying points is more than 20 points per square meter.
The air blowing method is used for extracting bromine from seawater by the equipment, and the method comprises the following steps:
the seawater raw material liquid is pumped by a raw material liquid pump and then is conveyed to the top of the blow-off tower through a pipeline, a sulfuric acid pipeline and a chlorine pipeline are sequentially connected in the pipeline between the raw material liquid pump and the top of the blow-off tower, so that sulfuric acid and chlorine are added after the seawater raw material liquid passes through the raw material liquid pump to form a raw material liquid containing free bromine, and then the raw material liquid enters the top of the blow-off tower through the pipeline; the content of bromide ions in the seawater raw material liquid is 50-120 ppm, and the flow rate is 600-2000 m3The temperature is normal temperature (20-25 ℃) to 50 ℃, the mass percent of dilute sulfuric acid is 5-50%, preferably 10-30%, and the chlorine mixing rate is 100-150% (based on the bromine content in the seawater raw material liquid, calculating the theoretical chlorine demand, and increasing the usage amount by at most half based on the theoretical chlorine demand);
raw material liquid containing free bromine is sprayed downwards through a blowing tower liquid distributor, purified air enters a blowing tower from a blowing tower purified air inlet through a pipeline, and is in countercurrent contact with the raw material liquid containing free bromine in the blowing tower in the upward diffusion process, the free bromine in the raw material liquid containing free bromine is entrained by the purified air and blown out to form an air mixture containing free bromine, the air mixture is discharged from the top of the blowing tower, and the raw material liquid desorbing the free bromine is discharged from a blowing tower liquid outlet of the blowing tower;
introducing an air mixture containing free bromine, absorbing liquid containing hydrobromic acid recycled from the bottom of the absorption tower and sulfur dioxide gas introduced from the outside into the absorption tower together from the top of the absorption tower in a forward flow manner, and reacting the free bromine, water and the sulfur dioxide in the absorption tower to generate the absorbing liquid containing the hydrobromic acid; the absorption liquid containing hydrobromic acid is discharged to an absorption liquid storage tank from an absorption liquid outlet of the absorption tower at the bottom of the absorption tower, and is circularly introduced to the top of the absorption tower through an absorption liquid outlet of the absorption liquid storage tank and an absorption liquid circulating pump; when the concentration of the hydrobromic acid-containing absorption liquid meets the requirement, forming finished liquid, sending the finished liquid from a finished liquid outlet of an absorption liquid storage tank to a distillation tower through a pipeline, oxidizing the finished liquid by chlorine again, and distilling, condensing and refining by steam to obtain liquid bromine;
the air mixture that contains free bromine has got rid of free bromine in the absorption tower, forms the air of having got rid of free bromine, gets into the mist capturing tower and upwards passes through the packing layer of mist capturing tower from absorption tower air outlet, connecting line and mist capturing tower gas inlet, becomes the air after purifying after the liquid foam of detaching smuggleing secretly, gets rid of from the gas outlet of mist capturing tower, gets into the blow-off tower through pipeline, fan and blow-off tower air-purifying inlet, realizes closed cyclic utilization.
In the technical scheme, in the blow-off tower, the volume ratio of the purified air to the raw material liquid containing free bromine is (80-120): 1, reacting at normal temperature and normal pressure.
In the technical scheme, the absorption liquid containing hydrobromic acid becomes finished liquid after reaching the preset concentration, and the finished liquid can be determined when the bromine content reaches over thousand times based on the bromine content in the seawater raw material liquid; and (4) carrying out preliminary judgment according to the concentration of the absorption liquid tested by the densimeter, and then carrying out detection on bromide ions.
In the above technical scheme, the determination of the usage amount of sulfur dioxide gas: based on the bromine content in the seawater raw material liquid, the theoretical required amount of sulfur dioxide is calculated for aeration, air is considered to be introduced into the sulfur dioxide, the volume percentage of the sulfur dioxide in the mixed gas is 8-12%, and an emptying pipeline (such as Chinese invention patent 2018100042286) can be considered to be connected to the upper part of the blow-out tower to avoid the overlarge pressure of the whole system.
The equipment and the process method are suitable for extracting bromine from seawater, the concentration of the bromine in the common seawater is 50-60 ppm, and the concentration of the bromine in the concentrated seawater is 80-120 ppm.
The method and the equipment for extracting bromine from seawater have the following beneficial effects:
(1) the bromide ions in the common seawater and the concentrated seawater are 50-120 ppm, but the total reserve is much larger than that of underground brine, and the bromide ions are almost inexhaustible and are a novel bromine resource source; the concentrated seawater produced by the reverse osmosis membrane method has clean water quality, the concentrated seawater produced by the low-temperature multi-effect thermal method has clean water quality and high temperature, and the warm seawater used for cooling other alkali plants or power plants has high temperature, is an excellent bromine extraction raw material, and is beneficial to reducing the cost of bromine extraction.
(2) Because the raw material liquid seawater does not have the risk of calcium sulfate precipitation and scaling or other impurities blocking filler channels, regular fillers with larger specific surface area, smaller unit pressure drop and higher mass transfer efficiency can be adopted. By carrying out surface modification on the regular packing, modifying the liquid spraying device and optimizing by combining specific process parameters, the bromine extraction production cost can be effectively reduced, and the advantages of the regular packing are exerted to the maximum extent. Aiming at a newly built bromine plant, a structured packed tower is adopted, so that the height of the packed tower can be effectively reduced by nearly 40 percent, and the investment cost is reduced; aiming at the technical improvement of the existing bromine factory, the productivity can be improved by nearly 50 percent on the basis of the existing treatment capacity by replacing regular packing and correspondingly modifying other tower internals, or the yield of bromine is improved by nearly 5 percent on the basis of keeping the treatment capacity unchanged.
Drawings
Fig. 1 is a schematic diagram of a tower apparatus for extracting bromine from (concentrated) seawater according to the present invention, wherein the components and reference numerals are shown in the following table.
Detailed Description
The technical solution of the present invention is further illustrated by the following examples.
As shown in the attached figure 1, the equipment for extracting bromine from seawater by using an air blowing method comprises a blowing tower, an absorption tower and a mist capturing tower, wherein:
the seawater raw material liquid a1 is pumped by a raw material liquid pump P1 and then is conveyed to the top of a blow-off tower T1 through a pipeline, a sulfuric acid pipeline a2 (namely sulfuric acid a2) and a chlorine gas pipeline a3 (namely chlorine gas a3) are sequentially connected in the pipeline between the raw material liquid pump P1 and the top of the blow-off tower T1, so that sulfuric acid a2 and chlorine gas a3 are added after the seawater raw material liquid a1 passes through the raw material liquid pump P1 to form a raw material liquid a4 containing free bromine, and the raw material liquid a4 enters the top of the blow-off tower T1 through a pipeline, preferably the upper side of the blow-off tower;
a blowing tower liquid distributor A1, a blowing tower filler layer B1 and a gas distributor Z are sequentially arranged in a blowing tower from top to bottom, a blowing tower purified air inlet 2 is arranged on the side of the lower part of the blowing tower, a blowing tower liquid outlet is arranged at the bottom of the blowing tower, raw material liquid a4 containing free bromine is sprayed downwards through the blowing tower liquid distributor A1, purified air a5 enters the blowing tower from the blowing tower purified air inlet through a pipeline, and is in countercurrent contact with raw material liquid a4 containing free bromine in the blowing tower T1 in the upward diffusion process, the raw material liquid a4 containing free bromine is entrained by the purified air a5 in the raw material liquid a4 to be blown out to form an air mixture a6 containing free bromine, the air mixture is discharged from the top of the blowing tower T1, and the raw material liquid a7 desorbing the free bromine is discharged from the blowing tower liquid outlet of the blowing tower;
the top of the stripping tower is connected with a top pipeline of the absorption tower, a sulfur dioxide gas pipeline a8 (namely sulfur dioxide a8) and an absorption liquid pipeline a7 containing hydrobromic acid (namely absorption liquid a7 containing hydrobromic acid) are arranged at the top of the absorption tower, and preferably, the absorption liquid pipeline a7 containing hydrobromic acid is arranged at the side of the upper part of the absorption tower; an absorption tower liquid distributor A2 and an absorption tower filler layer B2 are sequentially arranged in the absorption tower from top to bottom; an absorption tower absorption liquid outlet 8 is arranged at the bottom of the absorption tower, an absorption tower air outlet 7 is arranged on the absorption tower between the absorption tower absorption liquid outlet and the absorption tower filler layer, the absorption tower absorption liquid outlet 8 is connected with an absorption liquid inlet 9 of an absorption liquid storage tank through a pipeline, and preferably, an absorption liquid inlet is arranged between the bottom and the top of the absorption liquid storage tank; the air outlet 7 of the absorption tower is connected with the foam capturing tower gas inlet 12 through a pipeline, and the foam capturing tower gas inlet 12 is preferably arranged at the lower side of the foam capturing tower.
An absorption liquid outlet 10 of the absorption liquid storage tank and a finished liquid outlet 11 of the absorption liquid storage tank are arranged at the bottom of the absorption liquid storage tank V1, the finished liquid outlet of the absorption liquid storage tank is connected with the distillation tower through a pipeline, the absorption liquid outlet of the absorption liquid storage tank is connected with a circulating absorption liquid inlet of the absorption tower through a pipeline, and an absorption liquid circulating pump P2 is arranged in the pipeline, so that the absorption liquid a7 containing hydrobromic acid is circularly introduced into the top of the absorption tower T2; a detector is arranged in the absorbing liquid storage tank V1 to detect the concentration (bromide ion concentration) of the absorbing liquid a7 containing hydrobromic acid, when the concentration of the absorbing liquid a7 containing hydrobromic acid meets the requirement, a finished liquid a8 is formed, and the finished liquid is sent to the distillation tower T4 through a pipeline from the finished liquid outlet 11 of the absorbing liquid storage tank, oxidized by chlorine gas again, distilled by steam, condensed and refined to obtain liquid bromine.
The foam catching tower T3 is provided with a filler layer B3 of the foam catching tower, the top of the foam catching tower is provided with a gas outlet 13 of the foam catching tower and is connected with a fan inlet 14 of a fan C1 through a pipeline, and a fan outlet 15 is connected with a purified air inlet 2 of the blowing-out tower through a pipeline.
An air mixture a6 containing free bromine, an absorption liquid a7 containing hydrobromic acid recycled from the bottom of an absorption tower T2 and an externally introduced sulfur dioxide gas a8 are jointly introduced from the top of the absorption tower downstream (passing through an absorption tower liquid distributor A2 and an absorption tower filler layer B2), and the free bromine, water and sulfur dioxide react in an absorption tower T2 to generate the absorption liquid a7 containing hydrobromic acid; absorbing liquid a7 containing hydrobromic acid is discharged to an absorbing liquid storage tank V1 from an absorbing liquid outlet of the absorbing tower at the bottom of an absorbing tower T2, and circularly introduced into the top of the absorbing tower T2 through an absorbing liquid outlet 10 of the absorbing liquid storage tank and an absorbing liquid circulating pump P2; when the concentration of the hydrobromic acid-containing absorption liquid a7 meets the requirement, a finished liquid a8 is formed, and the finished liquid is sent to a distillation tower T4 from a finished liquid outlet 11 of an absorption liquid storage tank through a pipeline, oxidized by chlorine again, distilled by steam, condensed and refined to obtain liquid bromine.
The air mixture a6 containing free bromine, the absorption liquid a7 containing hydrobromic acid and the sulfur dioxide gas A8 introduced from the outside, which circulate from the bottom of the absorption tower T2, act together through the absorption tower liquid distributor A2 and the absorption tower filler layer B2, the air mixture a6 containing free bromine removes free bromine to form air a9 without free bromine, the air a9 enters the mist capturing tower T3 from the absorption tower air outlet 7, the connecting pipeline and the mist capturing tower gas inlet 12 and passes through the filler layer B3 of the mist capturing tower upwards to remove entrained liquid foam to form purified air a5, the purified air a5 is discharged from the mist capturing tower gas outlet 13 and enters the blowing tower T1 through the pipeline, the fan C1 and the blowing tower purified air inlet 2, and the closed cycle utilization is realized.
Determination of the usage amount of sulfur dioxide gas: based on the bromine content in the seawater raw material liquid, the theoretical required amount of sulfur dioxide is calculated for aeration, air is considered to be introduced into the sulfur dioxide, the volume percentage of the sulfur dioxide in the mixed gas is 8-12%, and an emptying pipeline (such as Chinese invention patent 2018100042286) can be considered to be connected to the upper part of the blow-out tower to avoid the overlarge pressure of the whole system.
Regular packing is filled in the blow-out tower T1, the absorption tower T2 and the foam capturing tower T3, and regular packing or random packing can be filled in the distillation tower T4. The equipment and the filler are all non-metallic materials resistant to bromine, acid and chlorine corrosion. Regular packing is filled in the blow-out tower, the absorption tower and the foam catching tower. The regular packing is in the form of orifice plate corrugated packing, pulse packing or wire mesh corrugated packing, all of which are surface treated to have contact angles of less than 120 degrees, preferably 80-100 degrees. The packing layer can be filled with one kind of structured packing, and can also be filled with various kinds of structured packing or the same kind of structured packing with different models. In principle, the lower part of the packing layer is regular packing with large void ratio and small surface area, which can be used for supporting the upper packing and also can be used as a gas distributor; the higher the specific surface area, the more fillers are selected. But the height of the minimum specific surface area at the bottommost part is not more than 1 m, the height of the minimum specific surface area at the middle part is not less than 4 m, for example, the bottom layer is 1 m of structured packing with the small specific surface area, and the top layer is 4 m with the large specific surface area; or the bottom layer is regular packing with small specific surface area of 1 meter, the middle part is regular packing with large specific surface area of 3 meters, and the top part is regular packing with larger specific surface area of 0.5 meter.
The packing layer of the blow-out tower is not higher than 6 meters, and the packing layers of the absorption tower and the foam capturing tower are not higher than 4 meters, and the sections are not needed.
The liquid distributor at the top of the blowing tower is of a groove type, a calandria type, a butterfly type and a spiral type, and the number of spraying points is more than 20 points/square meter. The gas distributor inside the blow-off column is in the form of a flat surface, such as a grid. The liquid distributor at the top of the absorption tower is in a groove type, a calandria type, a butterfly type, a spiral type and the like, and the number of spraying points is more than 20 points/square meter.
The technical scheme is utilized to modify and upgrade the packing tower and the process of the polypropylene random packing originally filled with DN75, and the alkali liquor modified specific surface area is selected to be 125m2The contact angle of the PP regular packing is 95 degrees, and the blowing-out tower T1, the absorption tower T2, the foam capturing tower T3 and the distillation tower T4 are filled with the regular packing; the packing layer of the blow-off tower is 5 meters, and the packing layers of the absorption tower, the foam catching tower and the distillation tower are 4 meters; the liquid distributors A1 and A2 are two-stage trough distributors, and the spraying point density is 50 points/m2。
1. Bromide ion oxidation
The concentrated seawater raw material liquid a1 containing 80ppm bromine after desalination is delivered to a blow-off tower T1 by a pump P2 through a pipeline, the delivery capacity is 1800m3H is used as the reference value. 20% sulfuric acid a2 (mass percent of sulfuric acid) and 120% excess chlorine a3 (calculated based on the bromine content in the seawater raw material solution, the theoretical chlorine demand is calculated, and the amount of the chlorine demand is increased by 20% based on the theoretical chlorine demand) are sequentially introduced into a pipeline behind a pump P2, and bromide ions in the concentrated seawater react to form free bromine to form a raw material solution a4 containing the free bromine.
2. Blowing free bromine
The raw material liquid a4 containing free bromine was introduced into the blow-off column T1 through a side nozzle 1 at the upper part thereof, and was sprayed downward through a liquid distributor A1. The purified air a5 is introduced from a side nozzle 2 at the lower part of the blow-off tower T1, and contacts with the raw material liquid a4 containing free bromine in the upward diffusion process in a countercurrent way on the surface of a filler layer B1 in the blow-off tower T1. The free bromine in the raw material liquid is entrained by the purified air a5 and blown out to form an air mixture a6 containing free bromine, and the air mixture is discharged from a top nozzle 3 of a blow-out tower T1, and the raw material liquid a7 from which the free bromine is desorbed is discharged from a bottom nozzle 4 of the blow-out tower T1. The volume ratio of the purified air a5 to the desalinated concentrated seawater a1 is 100:1,
3. preparation of the completion solution
An air mixture a6 containing free bromine, an absorption liquid a7 containing hydrobromic acid and circulating from the bottom of the absorption tower, and a sulfur dioxide gas a8 (based on the bromine content in the seawater raw material liquid, the theoretical required amount of sulfur dioxide is calculated for aeration, and it is considered that air is used to bring in sulfur dioxide, and the volume percentage of sulfur dioxide in the mixed gas is 8-12%) are respectively introduced from a top nozzle 4, a nozzle 5 and a nozzle 6 of the absorption tower T2 to co-flow, so that the free bromine, water and sulfur dioxide react in the absorption tower T2 to generate the hydrobromic acid-containing absorption liquid a 7. The hydrobromic acid-containing absorption liquid a7 enters an absorption liquid tank V1 from a bottom nozzle 8 of an absorption tower T2 through a nozzle 9. And (3) discharging the hydrobromic acid-containing absorption liquid a7 from a bottom nozzle 10 of an absorption liquid tank V1, circularly introducing the hydrobromic acid-containing absorption liquid a7 into the top of an absorption tower T2 through a pump P2, obtaining a finished liquid a8 after the absorption liquid reaches a preset concentration, carrying out preliminary judgment according to the concentration of the absorption liquid tested by a densimeter on the basis of the bromine content in the seawater raw material liquid, and carrying out titration by a chemical volumetric method of bromide ions. The air a9 without free bromine is discharged from a side nozzle 7 at the lower part of the absorption tower T2, enters a mist capturing tower T3 through a pipe opening 12 to remove entrained liquid mist to form purified air a5, the purified air a5 is discharged from a top nozzle 13 of the mist capturing tower T3, is pressurized by a fan C1, is sent to a nozzle 2 of a blowing tower T1, and is sealed for recycling.
The bromine ion concentration of the finished solution a8 was 80kg/m3And special additional water is not needed in the step.
4. Distillation of bromine
And (4) sending the finished liquid a8 to a distillation tower T4 for reoxidation, and carrying out steam distillation, condensation and refining to obtain liquid bromine.
Through field experiments, the bromine extraction capacity can be improved by nearly 50 percent under the condition of only improving and optimizing the internal parts of the blow-out tower, and the economic benefit is greatly improved.
The technical scheme of the invention can be realized by adjusting the technological parameters according to the content of the invention, and the bromine extraction capacity can be effectively improved. The invention has been described in an illustrative manner, and it is to be understood that any simple variations, modifications or other equivalent changes which can be made by one skilled in the art without departing from the spirit of the invention fall within the scope of the invention.
Claims (10)
1. The equipment for extracting bromine from seawater by using an air blowing method is characterized by consisting of a blowing tower, an absorption tower and a foam capturing tower, wherein:
the seawater raw material liquid is pumped by a raw material liquid pump and then is conveyed to the top of a blow-off tower through a pipeline, a sulfuric acid pipeline and a chlorine pipeline are sequentially connected in the pipeline between the raw material liquid pump and the top of the blow-off tower, a blow-off tower liquid distributor, a blow-off tower packing layer and a gas distributor are sequentially arranged in the blow-off tower from top to bottom, a blow-off tower purified air inlet is arranged on the side of the lower part of the blow-off tower, a blow-off tower liquid outlet is arranged at the bottom of the blow-off tower, the top of the blow-off tower is connected with an absorption tower top pipeline, and a sulfur dioxide gas pipeline and an absorption liquid pipeline containing hydrobromic acid are arranged at the;
an absorption tower liquid distributor and an absorption tower filler layer are sequentially arranged in the absorption tower from top to bottom; an absorption tower absorption liquid outlet is arranged at the bottom of the absorption tower, an absorption tower air outlet is arranged on the absorption tower between the absorption tower absorption liquid outlet and the absorption tower packing layer, the absorption tower absorption liquid outlet is connected with an absorption liquid inlet of an absorption liquid storage tank through a pipeline, and the absorption tower air outlet is connected with a foam capturing tower gas inlet through a pipeline; the bottom of the absorption liquid storage tank is provided with an absorption liquid outlet of the absorption liquid storage tank and a finished liquid outlet of the absorption liquid storage tank, the finished liquid outlet of the absorption liquid storage tank is connected with the distillation tower through a pipeline, the absorption liquid outlet of the absorption liquid storage tank is connected with a circulating absorption liquid inlet of the absorption tower through a pipeline, an absorption liquid circulating pump is arranged in the pipeline, and the finished liquid outlet of the absorption liquid storage tank is sent to the distillation tower through the pipeline;
the foam catching tower is internally provided with a packing layer of the foam catching tower, the top of the foam catching tower is provided with a gas outlet of the foam catching tower and is connected with a fan inlet of a fan through a pipeline, and the fan outlet is connected with a purified air inlet of the blow-out tower through a pipeline;
regular packing is filled in the blowing-out tower, the absorption tower and the foam catching tower, and regular packing or random packing can be filled in the distillation tower.
2. The apparatus for extracting bromine from seawater by air blow-off method according to claim 1, wherein the structured packing is in the form of orifice plate corrugated packing, pulse packing, wire mesh corrugated packing or other kinds and specifications of structured packing; the fillers are surface treated to have contact angles of less than 120 degrees, preferably 80 to 100 degrees.
3. The apparatus for extracting bromine from seawater by air blowing according to claim 1 or 2, wherein the top of the outside of the absorption tower has an inlet for air containing free bromine, an inlet for sulfur dioxide gas and an inlet for circulating absorption liquid; the absorption liquid pipeline containing hydrobromic acid is arranged on the side of the upper part of the absorption tower; an absorption liquid inlet is arranged between the bottom and the top of the absorption liquid storage tank; the gas inlet of the foam catching tower is arranged at the side of the lower part of the foam catching tower; arranging a detection device in the absorption liquid storage tank to detect the concentration of bromide ion in the absorption liquid containing hydrobromic acid; an emptying pipeline is arranged at the upper part of the blow-out tower.
4. The apparatus for extracting bromine from seawater by air blowing according to claim 1, wherein the packing layer can be filled with one type of structured packing, or with a plurality of types of structured packing of different types or the same type; the lower part of the packing layer is regular packing with large void ratio and small surface area, the packing with larger specific surface area is selected to be more upward, the height of the minimum specific surface area at the bottommost part is not more than 1 meter, the middle layer mainly with medium specific surface area is not less than 4 meters, for example, the bottom layer is regular packing with small specific surface area 1 meter, and the upper layer is regular packing with large specific surface area 4 meters; or the bottom layer is regular packing with small specific surface area of 1 meter, the middle part is regular packing with large specific surface area of 3 meters, and the top part is regular packing with larger specific surface area of 0.5 meter.
5. The apparatus for extracting bromine from seawater by air blow-off according to claim 1, wherein the packing layer of the blow-off tower is not higher than 6 m, and the packing layers of the absorption tower and the mist capturing tower are not higher than 4 m, and both do not need to be segmented; the liquid distributor at the top of the blowing tower is in a groove type or a tube array type, wherein the tube array type nozzle can be in a butterfly type or a spiral type, and the number of spraying points is more than 20 points/square meter; the gas distributor inside the blow-off tower is in a plane form, such as a grid plate; the liquid distributor at the top of the absorption tower is a groove type or a tube array type, wherein a butterfly type or a spiral type nozzle can be selected as the tube array type nozzle, and the number of spraying points is more than 20 points per square meter.
6. A method for extracting bromine from seawater by air blowing using the apparatus of any one of claims 1 to 5, characterized by comprising the steps of:
the seawater raw material liquid is pumped by a raw material liquid pump and then is conveyed to the top of the blow-off tower through a pipeline, a sulfuric acid pipeline and a chlorine pipeline are sequentially connected in the pipeline between the raw material liquid pump and the top of the blow-off tower, so that sulfuric acid and chlorine are added after the seawater raw material liquid passes through the raw material liquid pump to form a raw material liquid containing free bromine, and then the raw material liquid enters the top of the blow-off tower through the pipeline; the content of bromide ions in the seawater raw material liquid is 50-120 ppm, and the flow rate is 600-2000 m3The temperature is between normal temperature (20-25 ℃) and 50 ℃, the mass percent of the dilute sulfuric acid is 5-50%, preferably 10-30%, and the chlorine mixing rate is 100-150%;
raw material liquid containing free bromine is sprayed downwards through a blowing tower liquid distributor, purified air enters a blowing tower from a blowing tower purified air inlet through a pipeline, and is in countercurrent contact with the raw material liquid containing free bromine in the blowing tower in the upward diffusion process, the free bromine in the raw material liquid containing free bromine is entrained by the purified air and blown out to form an air mixture containing free bromine, the air mixture is discharged from the top of the blowing tower, and the raw material liquid desorbing the free bromine is discharged from a blowing tower liquid outlet of the blowing tower;
introducing an air mixture containing free bromine, absorbing liquid containing hydrobromic acid recycled from the bottom of the absorption tower and sulfur dioxide gas introduced from the outside into the absorption tower together from the top of the absorption tower in a forward flow manner, and reacting the free bromine, water and the sulfur dioxide in the absorption tower to generate the absorbing liquid containing the hydrobromic acid; the absorption liquid containing hydrobromic acid is discharged to an absorption liquid storage tank from an absorption liquid outlet of the absorption tower at the bottom of the absorption tower, and is circularly introduced to the top of the absorption tower through an absorption liquid outlet of the absorption liquid storage tank and an absorption liquid circulating pump; when the concentration of the hydrobromic acid-containing absorption liquid meets the requirement, forming finished liquid, sending the finished liquid from a finished liquid outlet of an absorption liquid storage tank to a distillation tower through a pipeline, oxidizing the finished liquid by chlorine again, and distilling, condensing and refining by steam to obtain liquid bromine;
the air mixture that contains free bromine has got rid of free bromine in the absorption tower, forms the air of having got rid of free bromine, gets into the mist capturing tower and upwards passes through the packing layer of mist capturing tower from absorption tower air outlet, connecting line and mist capturing tower gas inlet, becomes the air after purifying after the liquid foam of detaching smuggleing secretly, gets rid of from the gas outlet of mist capturing tower, gets into the blow-off tower through pipeline, fan and blow-off tower air-purifying inlet, realizes closed cyclic utilization.
7. The method for extracting bromine from seawater according to claim 6, wherein the volume ratio of the purified air to the raw material liquid containing free bromine in the blow-off tower is (80-120): 1, reacting at normal temperature and normal pressure.
8. The method of claim 6, wherein the absorbing solution containing hydrobromic acid is a finished solution after reaching a predetermined concentration, and the finished solution is determined when the bromine content is more than thousand times based on the bromine content in the seawater feed solution; and (4) carrying out preliminary judgment according to the concentration of the absorption liquid tested by the densimeter, and then carrying out detection on bromide ions.
9. The method of claim 6, wherein the determination of the amount of sulfur dioxide gas: based on the bromine content in the seawater raw material liquid, the theoretical sulfur dioxide demand is calculated for aeration, and the introduction of air into sulfur dioxide can be considered, wherein the volume percentage of the sulfur dioxide in the mixed gas is 8-12%.
10. An apparatus for extracting bromine from seawater by air blowing according to any one of claims 1 to 5, or the use of the method according to claim 6 for extracting bromine from seawater, wherein the bromine concentration in normal seawater is 50 to 60ppm, and the bromine concentration in concentrated seawater is 80 to 120 ppm.
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