A waste heat recovery and reuse air blowing bromine extraction system and method

Abstract

This invention belongs to the field of bromine extraction technology, and particularly relates to an air-blowing bromine extraction system and method for waste heat recovery and reuse. The air-blowing bromine extraction system includes an acidification unit, an oxidation tower, a blowing tower, an absorption tower, and a distillation tower, as well as a tail gas circulation path and a tail gas heat exchange path. The tail gas circulation path includes tail gas treatment equipment, heat exchange equipment, and a blower. Tail gas discharged from the absorption tower is treated by the tail gas treatment equipment and then sent to the cold medium channel of the heat exchange equipment for heat exchange. The heated tail gas is then circulated back to the blowing tower by the blower. A portion of the distillation waste liquid discharged from the distillation tower is diverted through branch pipes and sent to the hot medium channel of the heat exchange equipment for heat exchange. The cooled distillation waste liquid is then sent back to the distillation waste liquid treatment unit through a return pipe. This invention, by treating the tail gas generated in the blowing and absorption processes and then exchanging heat with the distillation waste liquid to raise its temperature, and then recycling it back to the blowing process, achieves better bromine blowing results and also realizes the reuse of waste heat.

Description

Technical Field

[0001] This invention belongs to the field of bromine extraction technology, and in particular relates to an air blowing bromine extraction system and method that utilizes waste heat recovery and reuse. Background Technology

[0002] Bromine is an important chemical raw material and a major branch of the marine chemical industry. Its diverse derivatives, including inorganic bromides, bromates, and organic bromine compounds, hold special value in national economic and technological development and are permeating various industries and fields with industrial growth. Natural bromine resources are mainly found in seawater, concentrated underground brine, ancient marine sediments, rock salt deposits, and salt lakes. Due to the vast volume of seawater, which contains 99% of the Earth's total bromine resources, the concentration of bromine in seawater is approximately 65 ppm, while the bromine content in rock salt deposits is only 0.1 ppm, and in some areas, underground brine contains 200–300 ppm of bromine.

[0003] The main technologies for producing bromine include steam distillation, air blowing, resin adsorption, gas membrane extraction, emulsion membrane extraction, solvent extraction, and precipitation. Currently, only steam distillation and air blowing are relatively mature and widely used both domestically and internationally. The air blowing method for extracting bromine from bromine-containing brines (such as seawater) mainly involves acidification, oxidation, blowing, absorption, and distillation of the seawater. During the distillation process, the waste liquid produced at the bottom of the distillation column contains a certain amount of heat, which is not fully utilized in current technologies, resulting in a waste of thermal energy. Similarly, the tail gas produced during the blowing and absorption processes also contains a certain amount of heat, which is also not utilized, leading to further heat waste. Summary of the Invention

[0004] In view of this, in order to solve the above-mentioned technical problems, the present invention proposes an air blowing bromine extraction system and method for waste heat recovery and reuse. By treating the tail gas generated in the blowing and absorption processes and then exchanging heat with the distillation waste liquid to raise the temperature, the air is recycled back to the blowing process. The heated blowing air is more effective when blowing bromine, and the waste heat is reused.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] An air-blowing bromine extraction system for waste heat recovery and reuse includes an acidification unit, an oxidation tower, a blow-out tower, an absorption tower, and a distillation tower connected sequentially via connecting pipelines, and further includes:

[0007] The exhaust gas circulation path includes an exhaust gas treatment device, a heat exchange device and a blower connected in sequence. The exhaust gas discharged from the exhaust gas outlet of the absorption tower is treated by the exhaust gas treatment device and then sent into the cold medium flow channel of the heat exchange device to exchange heat. The exhaust gas with increased temperature is circulated back to the blow-out tower by the blower.

[0008] The exhaust gas heat exchange passage shares the same heat exchange equipment as the exhaust gas circulation passage. Part of the distillation waste liquid discharged from the distillation tower is diverted through a branch pipeline and sent to the heat medium flow channel of the heat exchange equipment for heat exchange. The distillation waste liquid after the temperature is reduced is then sent to the distillation waste liquid treatment unit through the return pipeline.

[0009] In the above technical solution, the exhaust gas treatment equipment includes an exhaust gas treatment tower and a gas buffer tank. The exhaust gas inlet of the exhaust gas treatment tower is connected to the exhaust gas outlet of the absorption tower, the exhaust gas outlet is connected to the input end of the gas buffer tank, and the output end of the gas buffer tank is connected to the inlet of the cold medium flow channel of the heat exchange equipment.

[0010] In the above technical solution, the blower includes a blower, and the outlet of the cold medium flow channel of the heat exchanger is connected to the air inlet of the blow-out tower via the blower.

[0011] In the above technical solution, a gas mixing tank is also provided at the air inlet of the blowing tower. The gas mixing tank has two air inlets, one of which is connected to the outlet of fan one, and the other air inlet is connected to fan two.

[0012] In the above technical solution, the branch pipeline is set at the distillation waste liquid outlet of the distillation tower. The branch pipeline is connected to the inlet of the heat medium flow channel of the heat exchange equipment. The outlet of the heat medium flow channel of the heat exchange equipment merges with the distillation waste liquid outlet through the return pipeline and is then connected to the distillation waste liquid treatment unit.

[0013] In the above technical solution, a liquid pump is provided on the return pipeline.

[0014] In the above technical solution, the absorption tower adopts an alkaline absorption process, and the absorbent is a sodium hydroxide solution, wherein the mass concentration of sodium hydroxide in the branch pipeline is 10% to 20%.

[0015] The second objective of this invention is to provide a method for bromine extraction by blowing out air and recovering waste heat, comprising the following steps:

[0016] S1. Bromine is obtained by acidification, oxidation, air blowing, alkaline absorption, and acidification distillation of bromine-containing brine.

[0017] S2. Part of the distillation waste liquid discharged in the acidification distillation process is diverted to the heat medium flow channel of the heat exchange equipment through branch pipelines.

[0018] S3. The tail gas discharged from the alkaline absorption process is treated by the tail gas treatment equipment and then enters the cold medium flow channel of the heat exchange equipment to exchange heat with the distillation waste liquid in the hot medium flow channel.

[0019] S4. The exhaust gas after the temperature rises is recycled back to the air blowing-out process as blown-in air.

[0020] S5. The distillation waste liquid after the temperature is reduced is combined with the remaining distillation waste liquid from the acidification distillation process and sent to the distillation waste liquid treatment unit.

[0021] In the above technical solution, in step S4, the exhaust gas discharged in the alkaline absorption process is treated and heat-exchanged, then mixed with the blown-in air and used as blown-in air, and then sent to the air blowing-out process together.

[0022] In the above technical solution, the brine pump draws bromine-containing brine from the raw brine tank to the conveying pipeline and injects it into the acidic waste liquid obtained after bromine distillation in the distillation process for acidification; in the oxidation process, chlorine is used to oxidize the bromine-containing brine to generate an oxidized liquid, and the chlorine ratio is controlled at 110% to 115%.

[0023] In the above technical solution, during the air blowing process, the oxidizing liquid is sprayed from the top of the blowing tower through a spray device and comes into countercurrent contact with the air blown in from the bottom of the blowing tower. The bromine in the oxidizing liquid is blown out and mixed with the air to form bromine-containing air. The oxidizing liquid after the bromine is blown out becomes waste brine and is discharged from the bottom of the tower bottom of the blowing tower. The gas-liquid flow ratio of the air flow rate entering the blowing tower to the spray flow rate of the oxidizing liquid in the blowing tower is 280:1 to 300:1.

[0024] In the above technical solution, sodium hydroxide solution is used as the absorbent in the alkaline absorption process, with a mass concentration of 10% to 20%.

[0025] Compared with existing technologies, the waste heat recovery and reuse air blowing bromine extraction system and method of the present invention have the following advantages:

[0026] 1. The waste heat recovery and reuse air blowing bromine extraction system and method of the present invention treats the tail gas generated in the blowing and absorption processes and exchanges heat with the distillation waste liquid, and uses it as blowing air to be recycled back to the blowing process. While optimizing the bromine blowing effect, the waste heat in the tail gas and distillation waste liquid is reused.

[0027] 2. The waste heat recovery and reuse air blowing bromine extraction system of the present invention only requires the construction of heat exchange systems for tail gas and distilled waste liquid, as well as their respective recycling pipelines, on the existing air blowing bromine extraction system, resulting in low construction cost. Attached Figure Description

[0028] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0029] Figure 1 This is a schematic diagram of the process flow of the waste heat recovery and reuse air blowing bromine extraction system according to an embodiment of the present invention. Detailed Implementation

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Example 1

[0033] An air-blowing bromine extraction system for waste heat recovery and reuse includes an acidification unit, an oxidation tower, a blow-out tower, an absorption tower, and a distillation tower connected sequentially via connecting pipelines. It also includes a tail gas circulation path and a tail gas heat exchange path, wherein:

[0034] The exhaust gas circulation path includes an exhaust gas treatment device, a heat exchange device and a blower connected in sequence. The exhaust gas discharged from the exhaust gas outlet of the absorption tower is treated by the exhaust gas treatment device and then sent into the cold medium flow channel of the heat exchange device to exchange heat. The exhaust gas with increased temperature is circulated back to the blow-out tower by the blower.

[0035] The exhaust gas heat exchange passage and the exhaust gas circulation passage share the same heat exchange equipment. Part of the distillation waste liquid discharged from the distillation tower is diverted through a branch pipeline and sent to the heat medium flow channel of the heat exchange equipment for heat exchange. After the temperature is reduced, the distillation waste liquid is then sent to the distillation waste liquid treatment unit through the return pipeline.

[0036] Furthermore, in this embodiment, the exhaust gas treatment equipment may include an exhaust gas treatment tower and a gas buffer tank. The exhaust gas inlet of the exhaust gas treatment tower is connected to the exhaust gas outlet of the absorption tower, the exhaust gas outlet is connected to the input end of the gas buffer tank, and the output end of the gas buffer tank is connected to the inlet of the cold medium flow channel of the heat exchange equipment.

[0037] Furthermore, in this embodiment, the blower may include a blower, and the outlet of the cold medium flow channel of the heat exchanger is connected to the air inlet of the blow-out tower via the blower.

[0038] Furthermore, in this embodiment, a gas mixing tank can be provided at the air inlet of the blowing tower. The gas mixing tank has two air inlets, one of which is connected to the outlet of the first blower, and the other air inlet is connected to the second blower. When the treated exhaust gas for recycling is insufficient, the second blower is used to blow air, which is then mixed evenly in the mixing tank before being sent into the blowing tower.

[0039] Furthermore, in this embodiment, a liquid pump can be installed on the reflux pipeline. A portion of the waste liquid diverted from the bottom of the distillation column is sent to a heat exchanger to heat the treated tail gas as a heat source. After heat exchange, it returns through the reflux pipeline and merges into the remaining distillation waste liquid.

[0040] Furthermore, in this embodiment, the absorption tower may employ an alkaline absorption process.

[0041] Furthermore, in this embodiment, the absorbent can be a sodium hydroxide solution, wherein the mass concentration of sodium hydroxide in the branch pipe is 10% to 20%.

[0042] In this embodiment, the bromine-containing brine is first acidified, then oxidized by chlorine gas, and then blown out free bromine by air in the blow-out tower. It then enters the absorption tower for alkaline absorption, enriching the bromine to form an absorption liquid, which is sent to the distillation tower to distill out bromine and the remaining mother liquor. The tail gas discharged from the tail gas outlet of the absorption tower is treated in the tail gas treatment tower and still has a certain amount of heat. After exchanging heat with a portion of the distillation waste liquid that has a certain amount of heat from the mother liquor of the tower, it is further heated and then reused in the blow-out tower. This method is more effective when blowing out bromine from the oxidized liquid.

[0043] Specifically: such as Figure 1 As shown, an air-blowing bromine extraction system for waste heat recovery and reuse includes an acidification unit, an oxidation tower, a blowing tower, an absorption tower, and a distillation tower connected in sequence; it also includes a tail gas treatment tower, a gas buffer tank, a heat exchanger, and a blower connected in sequence; the exhaust gas inlet of the tail gas treatment tower is connected to the tail gas outlet of the absorption tower; the inlet of the cold medium flow channel of the heat exchanger is connected to the outlet of the gas buffer tank, and the outlet of the cold medium flow channel of the heat exchanger is connected to one inlet of a gas mixing tank via blower, while the other inlet of the gas mixing tank is connected to blower; a branch pipe is provided at the outlet of the distillation waste liquid of the distillation tower, the branch pipe is connected to the inlet of the heat medium flow channel of the heat exchanger, and the outlet of the heat medium flow channel is connected to the distillation waste liquid treatment unit via a return pipe. Example 2

[0044] A waste heat recovery and reuse air blowing method for bromine extraction involves acidifying, oxidizing, air blowing, alkaline absorption, and acid distillation of bromine-containing brine to obtain bromine. Specifically, a portion of the distillation waste liquid from the distillation process is diverted to the hot medium channel of a heat exchanger. The exhaust gas from the alkaline absorption process is treated and then enters the cold medium channel of the heat exchanger to exchange heat with the distillation waste liquid in the hot medium channel. After the temperature rises, the gas is recycled back to the air blowing process as incoming air. The heat-exchanged distillation waste liquid is combined with the remaining distillation waste liquid from the distillation process and sent to a distillation waste liquid treatment unit.

[0045] Furthermore, in this embodiment, the exhaust gas discharged during the alkaline absorption process can be treated and heat-exchanged, then mixed with the blown-in air before being sent to the air blowing process.

[0046] Furthermore, in this embodiment, a brine pump can be used to pump bromine-containing brine from the raw brine tank to a conveying pipeline and inject it into the acidic waste liquid obtained after bromine distillation in the distillation process for acidification; in the oxidation process, chlorine is used to oxidize the bromine-containing brine to generate an oxidized liquid, and the chlorine ratio is controlled at 110% to 115%.

[0047] Furthermore, in this embodiment, it can also be considered that in the air blowing process, the oxidizing liquid is sprayed from the top of the blowing tower through a spray device and comes into countercurrent contact with the air blown in from the bottom of the blowing tower. The bromine in the oxidizing liquid is blown out and mixed with the air to form bromine-containing air. The oxidizing liquid after the bromine is blown out becomes waste brine and is discharged from the bottom of the tower bottom of the blowing tower. The gas-liquid flow ratio of the air flow rate entering the blowing tower to the spray flow rate of the oxidizing liquid in the blowing tower is 280:1 to 300:1.

[0048] Furthermore, in this embodiment, sodium hydroxide solution with a mass concentration of 10% to 20% can be used as the absorbent in the alkaline absorption process.

[0049] like Figure 1 As shown, the process of bromine extraction by air blowing is as follows:

[0050] S1. The brine pump draws bromine-containing brine from the raw brine tank to the conveying pipeline and injects it into the acidic waste liquid obtained after bromine distillation in the distillation process for acidification.

[0051] S2. In an acidic environment, chlorine is used to oxidize bromine-containing brine to generate an oxidized liquid, and the chlorine concentration is controlled at 110% to 115%.

[0052] S3. The oxidizing liquid is sprayed from the top of the blowing tower through a spray device and comes into countercurrent contact with the air blown in from the bottom of the blowing tower. The bromine in the oxidizing liquid is blown out and mixed with the air to form bromine-containing air. The oxidizing liquid after the bromine is blown out becomes waste brine and is discharged from the bottom of the blowing tower. The gas-liquid flow ratio of the air flow rate entering the blowing tower to the spray flow rate of the oxidizing liquid in the blowing tower is 280:1 to 300:1.

[0053] S4, 10%~20% sodium hydroxide solution is pumped into the absorption tower, reacts with bromine in the air entering the absorption tower to produce sodium bromide, sodium bromate, and sodium hypobromite, and then pumped into the finished liquid tank and sent to the distillation process.

[0054] S5. Add hydrochloric acid to the absorption liquid pipeline to make Br - It is oxidized to free bromine and enters the distillation column, where the reaction is as follows:

[0055] 5NaBr+NaBrO3+6HCl=6NaCl+3Br2+3H2O;

[0056] The distillation column is heated with steam, causing the absorbed liquid to react with hydrochloric acid, and bromine is obtained by distillation.

[0057] In this process, the exhaust gas discharged from the absorption stage is treated by the exhaust gas treatment tower and then enters the cold medium flow channel of the heat exchange equipment. The distillation waste liquid discharged from the distillation stage is diverted through branch pipelines and sent to the hot medium flow channel of the heat exchange equipment to heat the gas treated by the exhaust gas treatment tower in the cold medium flow channel. The gas is then sent back to the main pipeline through the return pipeline to merge with the distillation waste liquid and sent to the distillation waste liquid treatment unit. The heated gas is sent to the gas buffer tank by blower one and mixed with the air blown in by blower two. The mixture is then circulated back to the blow-out tower, where the oxidizing liquid is blown out with bromine.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A waste heat recovery and reuse air stripping system for bromine, comprising, in order, an acidification unit, an oxidation tower, a stripping tower, an absorption tower and a distillation tower connected by connecting pipes, characterized in that: Also comprising: A tail gas circulation passage comprising, in sequence, a tail gas treatment device, a heat exchange device and a blower device, tail gas discharged from the tail gas outlet of the absorption tower being treated by the tail gas treatment device, then being sent to the cold medium flow channel of the heat exchange device to be heat exchanged, and the tail gas with increased temperature being circulated back to the blowout tower by the blower device, the tail gas treatment device comprising a tail gas treatment tower and a gas buffer tank, the waste gas inlet of the tail gas treatment tower being connected with the tail gas outlet of the absorption tower, the waste gas outlet being connected with the input end of the gas buffer tank, and the output end of the gas buffer tank being connected with the cold medium flow channel inlet of the heat exchange device; A tail gas heat exchange passage sharing the heat exchange device with the tail gas circulation passage, part of the distillation waste liquid discharged from the distillation tower being sent to the hot medium flow channel of the heat exchange device through a branch pipeline to be heat exchanged, and the distillation waste liquid with reduced temperature being sent to the distillation waste liquid treatment unit through a reflux pipeline, the branch pipeline being arranged at the distillation waste liquid outlet of the distillation tower, the branch pipeline being communicated with the hot medium flow channel inlet of the heat exchange device, and the hot medium flow channel outlet of the heat exchange device being connected with the distillation waste liquid outlet through the reflux pipeline, and then being connected with the distillation waste liquid treatment unit.

2. The waste heat recovery and reuse air blowing bromine extraction system according to claim 1, characterized in that: The blower device comprises a blower one, and the cold medium flow channel outlet of the heat exchange device is connected with the air inlet of the blowout tower through the blower one.

3. The waste heat recovery and reuse air blowing bromine extraction system according to claim 2, characterized in that: The air inlet of the blowout tower is further provided with a gas mixing tank, the gas mixing tank is provided with two air inlets, one of which is connected with the outlet of the blower one, and the other is connected with a blower two.

4. The waste heat recovery and reuse air blowing bromine extraction system according to claim 1, characterized in that: A liquid pump is arranged on the reflux pipeline.

5. A method of air blowing and bromine extraction of a waste heat recovery and reuse air blowing and bromine extraction system according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: S1, bromine-containing brine is subjected to acidification, oxidation, air blowing, alkali absorption and acidification distillation to obtain bromine; S2, part of the distillation waste liquid discharged in the acidification distillation process is branched to the hot medium flow channel of the heat exchange device through a branch pipeline; S3, tail gas discharged in the alkali absorption process is treated by a tail gas treatment device, then enters the cold medium flow channel of the heat exchange device, and is heat exchanged with the distillation waste liquid in the hot medium flow channel; S4, the tail gas with increased temperature is circulated back to the air blowing process as blowing air; S5, the distillation waste liquid with reduced temperature is combined with the remaining distillation waste liquid of the acidification distillation process, and is sent to the distillation waste liquid treatment unit.

6. The method of claim 5, wherein the method further comprises: In step S4, the tail gas discharged in the alkali absorption process is treated and heat exchanged, then is mixed with the air to be blown in as blowing air, and is sent to the air blowing process.

7. The method of claim 5, wherein the method further comprises: The bromine-containing brine is pumped from a raw material brine pool to a conveying pipeline by a brine pump, and is acidified after bromine distillation in the distillation process; chlorine gas is used in the oxidation process to oxidize the bromine-containing brine to generate an oxidation liquid, and the chlorine gas ratio is controlled at 110% to 115%.

8. The method of claim 5, wherein the method further comprises: In the air blowing process, the oxidation liquid is sprayed from the top of the blowout tower through a spraying device, and is countercurrently contacted with the air blown in from the bottom of the blowout tower, the bromine in the oxidation liquid is blown out and mixed with the air to form bromine-containing air, and the oxidation liquid after blowing out the bromine becomes waste brine which is discharged from the bottom of the blowout tower; wherein the gas-liquid flow ratio of the air flow entering the blowout tower to the spraying flow of the oxidation liquid in the blowout tower is 280:1 to 300:1.

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