Carbon dioxide trapping and wastewater recycling treatment method based on cavitation air flotation method

Abstract

The invention relates to the technical field of gas-liquid treatment, and discloses a carbon dioxide trapping and wastewater recycling treatment method based on a cavitation air flotation method, which comprises the following steps: S1, flue gas of a blast furnace and a hot blast stove in an iron and steel plant is communicated with an air inlet of a cavitation air flotation fan blade through a flue gas channel, and the fan blade rapidly rotates to generate a negative pressure environment underwater; the method comprises the following steps: (1) adding a liquid into a cavitation air floatation tank, enabling flue gas to enter the liquid through fan blades, and dispersing the flue gas through the fan blades to form microbubbles, (2) injecting whole-plant comprehensive wastewater containing calcium and / or magnesium ions in a steel plant into the cavitation air floatation tank, and enabling carbon dioxide in the flue gas to react with the calcium and magnesium ions in the wastewater to form precipitates; according to the method, a brand new thought is provided, the wastewater and the flue gas of the steel mill are subjected to economic cooperative treatment, and compared with a traditional flue gas treatment method, the method provided by the invention has the advantages that the process of carbon dioxide absorption and wastewater treatment is more simplified, the mass transfer efficiency is enhanced, and meanwhile, the difficulty of collection after precipitation of calcium and magnesium ions in water is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of gas-liquid treatment, and in particular to a method for capturing carbon dioxide and recycling wastewater based on cavitation flotation. Background Art

[0002] The steel industry is actively exploring the application of carbon capture technology to meet the challenges of global climate change and carbon emission reduction. Although carbon capture technology has been applied to a certain extent in the steel industry, it still faces challenges in terms of technology maturity, energy efficiency, and cost. The stability and reliability of the technology need to be further verified and optimized in practical applications. The construction and operation costs of carbon capture technology are high, which limits its promotion in large-scale commercial applications. The installation of carbon capture facilities will lead to an increase in the cost of steel products, thereby affecting the competitiveness of enterprises. The carbon capture process itself consumes a lot of energy, which may reduce the energy efficiency of the entire steel production system. How to improve the energy efficiency of the carbon capture process and reduce energy consumption is a problem that needs to be solved urgently.

[0003] The conventional carbon dioxide capture facilities in existing steel plants have high energy consumption and are subject to greater energy consumption constraints during actual use. The existing methods for wastewater treatment in the steel industry are relatively complete, but the removal of calcium and magnesium ions mainly relies on the input of sodium carbonate, which increases the cost of external purchases. Summary of the invention

[0004] The purpose of the present invention is to provide a method for capturing carbon dioxide and disposing wastewater resources based on cavitation flotation. The high-speed rotation of the fan blades of the cavitation flotation inhales flue gas to form microbubbles. The flue gas and wastewater produce economic product crystals and the microbubbles are used to float and collect them, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] Carbon dioxide capture and wastewater resource disposal methods based on cavitation flotation include:

[0007] Step S1: The flue gas from the blast furnace and hot blast furnace in the steel plant is connected to the air inlet of the vortex air flotation blade through the flue gas channel. The blades rotate rapidly to generate a negative pressure environment underwater, so that the flue gas enters the liquid through the blades and is dispersed by the blades to form microbubbles;

[0008] Step S2: injecting the comprehensive wastewater from the steel plant containing calcium and / or magnesium ions into the vortex flotation tank, so that the carbon dioxide in the flue gas reacts with the calcium and magnesium ions in the wastewater to form a precipitate, the precipitate is calcium carbonate and / or magnesium carbonate, the buoyancy of the precipitate is increased due to the attachment of microbubbles, the precipitate rises to the liquid surface, and is collected by a scraper;

[0009] Step S3: injecting waste ammonia water obtained from the coking plant into the vortex flotation tank to adjust the liquid environment and promote the formation of sediment.

[0010] As a further solution of the present invention: step S1 is replaced by step S1a, step S1a: the flue gas from the blast furnace and hot blast stove in the steel plant is first filtered through pores to remove fly ash and solid impurities, and then enters the air inlet of the vortex air flotation fan blade through the flue gas channel.

[0011] As a further solution of the present invention: step S1 is replaced by step S1b, step S1b: the carbon dioxide gas in the carbon capture equipment in the steel plant is directly connected to the air inlet of the cavitation air flotation fan blade.

[0012] As a further solution of the present invention: step S1 is replaced by step S1c, step S1c: carbon dioxide gas or flue gas or air is transported to the air inlet of the vortex air flotation fan blade as the gas for generating microbubbles, and additional air inlets for carbon dioxide gas and flue gas are provided, so that the flue gas is directly transported to the bottom of the waste liquid and generates air bubbles.

[0013] As a further solution of the present invention: the top of the vortex concave air flotation tank is a closed environment, and is equipped with an exhaust mechanism to extract the residual smoke to the outside, and an additional step S4 is provided. Step S4: the extracted smoke is tested, and if there is still residual smoke, the smoke is returned to the air inlet of the vortex concave air flotation fan blade.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The present invention proposes a new idea for economically co-processing wastewater and flue gas from a steel plant. Compared with traditional flue gas treatment methods, the method provided by the present invention simplifies the process of carbon dioxide absorption and wastewater treatment, enhances mass transfer efficiency, and reduces the difficulty of collecting calcium and magnesium ions in water after precipitation. The carbon dioxide in the flue gas reacts with the calcium and magnesium ions in the wastewater to produce economic products of calcium carbonate and magnesium carbonate, and the economic products are collected by rising under the action of microbubble flotation, thereby improving the process treatment efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1 It is a schematic diagram of the carbon dioxide capture and wastewater resource disposal method based on cavitation flotation; DETAILED DESCRIPTION

[0018] Embodiment 1:

[0019] This embodiment includes: Step S1: The flue gas from the blast furnace and hot blast stove in the steel plant is connected to the air inlet of the vortex air flotation fan blade through the flue gas channel. The fan blades rotate rapidly to produce a negative pressure environment underwater, so that the flue gas enters the liquid through the fan blades and is dispersed by the fan blades to form microbubbles.

[0020] Step S2: injecting the comprehensive wastewater from the steel plant containing calcium and / or magnesium ions into the vortex flotation tank, so that the carbon dioxide in the flue gas reacts with the calcium and magnesium ions in the wastewater to form a precipitate, the precipitate is calcium carbonate and / or magnesium carbonate, the buoyancy of the precipitate is increased due to the attachment of microbubbles, the precipitate rises to the liquid surface, and is collected by a scraper.

[0021] Step S3: injecting waste ammonia water obtained from the coking plant into the vortex flotation tank to adjust the liquid environment and promote the formation of sediment.

[0022] In this embodiment: the flue gas produced by the blast furnace and hot blast stove in the steel plant contains carbon dioxide, and the fan blades of the vortex gas flotation will generate negative pressure in the liquid during high-speed rotation, so that the gas enters the channel at the fan blade through the pipeline and generates microbubbles. At the same time, the gas will produce carbonates after contacting the wastewater containing calcium and magnesium ions, specifically calcium carbonate and magnesium carbonate. Due to the production process of steel, some raw materials such as dolomite, limestone, etc. contain calcium and magnesium. The reaction of these raw materials during the high-temperature smelting process will release calcium and magnesium ions, and the wastewater includes clean wastewater, cooling wastewater, etc., and calcium and magnesium will remain in this type of wastewater. This treatment method can not only remove the carbon dioxide in the flue gas, but also the economic products produced by carbon dioxide and wastewater are also affected by microbubbles to float and collect, and economic products are obtained in the process of wastewater and waste gas treatment.

[0023] In this embodiment, the main purpose of the waste ammonia water introduced into the coking plant is to provide an alkaline environment inside the cavitation flotation to promote the formation of crystals. Optionally, a small portion of the waste ammonia water is taken from the coking plant of the steel plant or purchased from outside as an alternative, and the remaining ammonia-containing wastewater is reused in the cavitation flotation device, and the rest is subjected to subsequent treatment, which may include the preparation of ammonium sulfate or sodium carbonate, sodium bicarbonate.

[0024] Embodiment 2:

[0025] In this embodiment: Step S1a: The flue gas from the blast furnace and hot blast furnace in the steel plant is first filtered through pores to remove fly ash and solid impurities, and then enters the air inlet of the vortex air flotation fan blade through the flue gas channel;

[0026] Step S2: injecting the comprehensive wastewater from the steel plant containing calcium and / or magnesium ions into the vortex flotation tank, so that the carbon dioxide in the flue gas reacts with the calcium and magnesium ions in the wastewater to form a precipitate, the precipitate is calcium carbonate and / or magnesium carbonate, the buoyancy of the precipitate is increased due to the attachment of microbubbles, the precipitate rises to the liquid surface, and is collected by a scraper;

[0027] Step S3: injecting waste ammonia water obtained from the coking plant into the vortex flotation tank to adjust the liquid environment and promote the formation of sediment.

[0028] In this embodiment, in order to prevent the floating materials of waste liquid crystal from being too complicated, the flue gas can be filtered before being put into use, thereby avoiding excessive floating materials and causing inconvenience in taking.

[0029] Embodiment three:

[0030] In this embodiment: Step S1b: directly connecting the carbon dioxide gas in the carbon capture equipment in the steel plant to the air inlet of the cavitation air flotation fan blade;

[0031] Step S2: injecting the comprehensive wastewater from the steel plant containing calcium and / or magnesium ions into the vortex flotation tank, so that the carbon dioxide in the flue gas reacts with the calcium and magnesium ions in the wastewater to form a precipitate, the precipitate is calcium carbonate and / or magnesium carbonate, the buoyancy of the precipitate is increased due to the attachment of microbubbles, the precipitate rises to the liquid surface, and is collected by a scraper;

[0032] Step S3: injecting waste ammonia water obtained from the coking plant into the vortex flotation tank to adjust the liquid environment and promote the formation of sediment.

[0033] In this embodiment: since there is carbon capture equipment in the steel plant, in order to reduce carbon dioxide emissions, the carbon dioxide gas generated by the carbon capture equipment can also be introduced into the cavitation flotation device in the method for economical treatment.

[0034] Embodiment 4:

[0035] In this embodiment: Step S1c: transporting carbon dioxide gas or flue gas or air to the air inlet of the vortex air flotation fan blade as a gas for generating microbubbles, and additional air inlets for carbon dioxide gas and flue gas are provided, so that the flue gas is directly transported to the bottom of the waste liquid and generates air bubbles;

[0036] Step S2: injecting the comprehensive wastewater from the steel plant containing calcium and / or magnesium ions into the vortex flotation tank, so that the carbon dioxide in the flue gas reacts with the calcium and magnesium ions in the wastewater to form a precipitate, the precipitate is calcium carbonate and / or magnesium carbonate, the buoyancy of the precipitate is increased due to the attachment of microbubbles, the precipitate rises to the liquid surface, and is collected by a scraper;

[0037] Step S3: injecting waste ammonia water obtained from the coking plant into the vortex flotation tank to adjust the liquid environment and promote the formation of sediment.

[0038] In this embodiment: in order to ensure sufficient mixing of gas and liquid, air can be selected to enter the air inlet of the vortex air flotation fan blade, but it is necessary to add a flue gas duct in the flotation tank so that the flue gas is directly injected into the waste liquid, so that the flue gas and the waste liquid are fully in contact, and the generated sediment is adhered and floated by the microbubbles generated by the fan blade.

[0039] Embodiment five:

[0040] In this embodiment: Step S4: The top of the vortex air flotation tank is a closed environment and is equipped with an exhaust mechanism to extract the residual smoke to the outside, and the extracted smoke is tested. If there is still residual smoke, the smoke is returned to the air inlet of the vortex air flotation fan blade.

[0041] In this embodiment: since the flue gas may contain other substances, when the gas escapes upward through the liquid surface, the space above the flotation tank can be sealed in a closed manner, and the gas can be extracted for detection. When the carbon dioxide concentration is still lower than the specified requirement, a reflux cycle can be performed. If the carbon dioxide concentration is significantly reduced, the gas can be transported to the subsequent process for secondary treatment.

[0042] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for capturing carbon dioxide and treating wastewater as a resource based on cavitation flotation, characterized in that: include: Step S1: The flue gas from the blast furnace and hot blast furnace in the steel plant is connected to the air inlet of the vortex air flotation blade through the flue gas channel. The blades rotate rapidly to generate a negative pressure environment underwater, so that the flue gas enters the liquid through the blades and is dispersed by the blades to form microbubbles; Step S2: injecting the comprehensive wastewater from the steel plant containing calcium and / or magnesium ions into the vortex flotation tank, so that the carbon dioxide in the flue gas reacts with the calcium and magnesium ions in the wastewater to form a precipitate, the precipitate is calcium carbonate and / or magnesium carbonate, the buoyancy of the precipitate is increased due to the attachment of microbubbles, the precipitate rises to the liquid surface, and is collected by a scraper; Step S3: injecting waste ammonia water obtained from the coking plant into the vortex flotation tank to adjust the liquid environment and promote the formation of sediment.

2. The method for capturing carbon dioxide and treating wastewater as a resource based on cavitation flotation according to claim 1 is characterized in that: Step S1 is replaced by step S1a. Step S1a: the flue gas from the blast furnace and hot blast stove in the steel plant is first filtered through pores to remove fly ash and solid impurities, and then enters the air inlet of the vortex air flotation fan blade through the flue gas channel.

3. The method for carbon dioxide capture and wastewater resource disposal based on cavitation flotation according to claim 1 is characterized in that: Step S1 is replaced by step S1b. Step S1b: directly connect the carbon dioxide gas in the carbon capture equipment in the steel plant to the air inlet of the cavitation air flotation fan blade.

4. The method for carbon dioxide capture and wastewater resource disposal based on cavitation flotation according to claim 1 is characterized in that: Replace step S1 with step S1c, step S1c: transport carbon dioxide gas or flue gas or air to the air inlet of the vortex air flotation fan blade as the gas for generating microbubbles, and add air inlets for carbon dioxide gas and flue gas, so that the flue gas is directly transported to the bottom of the waste liquid and generates air bubbles.

5. The method for carbon dioxide capture and wastewater resource disposal based on cavitation flotation method according to claim 1 is characterized in that: The top of the vortex concave air flotation tank is a closed environment and is equipped with an exhaust mechanism to extract the residual smoke to the outside, and an additional step S4 is provided. Step S4: the extracted smoke is tested, and if there is still residual smoke, the smoke is returned to the air inlet of the vortex concave air flotation fan blade.

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