Device and method for producing alkali by capturing carbon dioxide in industrial waste gas

Abstract

The invention relates to a device and method for producing alkali by capturing carbon dioxide in industrial waste gas, and belongs to the technical field of industrial waste gas treatment.The method for producing alkali by capturing carbon dioxide in industrial waste gas comprises the following steps that the industrial waste gas is treated, and carbon dioxide CO2 and ammonia gas NH3 in the industrial waste gas are captured; the method comprises the following steps: introducing carbon dioxide CO2 and ammonia gas NH3 in industrial waste gas into a carbonization cleaning tower to generate ammonium carbonate (NH4) 2CO3; the method comprises the following steps: reacting ammonium carbonate (NH4) 2CO3 with a sodium chloride NaCl solution in a reaction tower to generate sodium bicarbonate NaHCO3 and ammonium chloride NH4Cl, and separating the sodium bicarbonate NaHCO3 from the ammonium chloride NH4Cl; and carrying out steam calcination on the separated sodium bicarbonate NaHCO3 to generate a Na2CO3 product, and carrying out cooling crystallization on ammonium chloride NH4Cl to generate a NH4Cl product. According to the method, effective recovery and cyclic utilization of carbon dioxide can be achieved, valuable chemical products are generated through multiple reactions and resource conversion, and good balance is achieved between environmental protection and economic benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial waste gas treatment, and specifically relates to a device and method for capturing carbon dioxide in industrial waste gas to make alkali. Background Art

[0002] In the process of rapid development of modern industry, the large-scale emission of industrial waste gas has become an extremely severe environmental challenge. Among them, carbon dioxide, as the primary greenhouse gas, has caused a profound and irreversible impact on global warming. In this context, capturing carbon dioxide from industrial waste gas is of great significance. It can not only effectively reduce the total amount of greenhouse gases discharged into the atmosphere, but also achieve effective recycling and reuse of resources, which is highly consistent with the advanced concept of sustainable development.

[0003] The alkali industry has always occupied an important position in the chemical industry. The traditional alkali production process has always been strongly dependent on high-purity carbon dioxide gas sources. In fact, industrial waste gas contains considerable carbon dioxide resources, which undoubtedly creates an excellent opportunity for carbon dioxide capture and alkali production. With the increasingly stringent environmental protection standards and the deep rooted concept of resource recycling in the whole society, the research and development and breakthrough of carbon dioxide capture and alkali production technology in industrial waste gas will undoubtedly have immeasurable and extremely critical significance for vigorously promoting the green transformation process of the chemical industry and actively responding to the various crises brought about by climate change. Summary of the invention

[0004] The present invention application proposes a device and method for capturing carbon dioxide in industrial waste gas to make alkali, which aims to partially or completely solve the technical problem of how to achieve the capture of carbon dioxide in industrial waste gas to make alkali in the prior art. The technical solution of the present invention application is as follows:

[0005] In a first aspect, a device for capturing and making alkali from carbon dioxide in industrial waste gas comprises: a capturing unit for treating industrial waste gas to capture carbon dioxide CO2 and ammonia NH3 in the industrial waste gas; a first reaction unit for passing carbon dioxide CO2 and ammonia NH3 in the industrial waste gas into a carbonization cleaning tower for reaction to generate ammonium carbonate (NH4)2CO3; a second reaction unit for reacting ammonium carbonate (NH4)2CO3 with a sodium chloride NaCl solution to generate sodium bicarbonate NaHCO3 and ammonium chloride NH4Cl, and separating the sodium bicarbonate NaHCO3 and the ammonium chloride NH4Cl; a third reaction unit one for steam calcining the separated sodium bicarbonate NaHCO3 to generate a Na2CO3 product; and a third reaction unit two for cooling and crystallizing the separated ammonium chloride NH4Cl to generate an NH4Cl product.

[0006] Optionally, the carbon dioxide capture and alkali production device in industrial waste gas also includes: a dissolution unit and a third reaction unit three, the dissolution unit dissolves the Na2CO3 product to form a Na2CO3 solution, and the third reaction unit three reacts the Na2CO3 solution with urea CO(NH2)2 to generate a NaOCN product.

[0007] Optionally, the carbon dioxide capture and alkali production device in industrial waste gas also includes: a carbon dioxide capture and transportation unit and an ammonia capture and transportation unit. The carbon dioxide capture and transportation unit captures the carbon dioxide after steam calcination of sodium bicarbonate NaHCO3, and transports the carbon dioxide to the first reaction unit; the ammonia capture and transportation unit captures the ammonia generated by the decomposition of the NH4Cl product, and transports the ammonia to the first reaction unit.

[0008] Optionally, the carbon dioxide capture and alkali production device in industrial waste gas also includes: a carbon dioxide and ammonia capture and transportation unit, which captures carbon dioxide and ammonia generated by the reaction of Na2CO3 solution and urea CO(NH2)2, and transports the carbon dioxide and ammonia to the first reaction unit.

[0009] In a second aspect, a method for capturing carbon dioxide in industrial waste gas to produce alkali comprises the following steps:

[0010] Step S100: treating the industrial waste gas to capture carbon dioxide CO2 and ammonia NH3 in the industrial waste gas;

[0011] Step S200: Carbon dioxide CO2 and ammonia NH3 in industrial waste gas are introduced into a carbonization cleaning tower to generate ammonium carbonate (NH4)2CO3;

[0012] Step S300: in a reaction tower, reacting ammonium carbonate (NH4)2CO3 with sodium chloride NaCl solution to generate sodium bicarbonate NaHCO3 and ammonium chloride NH4Cl, and separating the sodium bicarbonate NaHCO3 and ammonium chloride NH4Cl;

[0013] Step S400: steam calcining the separated sodium bicarbonate NaHCO3 to generate Na2CO3 product, and cooling and crystallizing the ammonium chloride NH4Cl to generate NH4Cl product.

[0014] Optionally, in step S400, during the steam calcination of NaHCO3, the furnace gas is condensed and washed to release carbon dioxide CO2, and the carbon dioxide CO2 is transported to the carbonization washing tower.

[0015] Optionally, step S400 includes:

[0016] Step S401: Cooling the ammonium chloride solution: When the ammonium chloride solution reaches a saturated state, the solution is gradually cooled by controlling the temperature. As the temperature decreases, the solubility of ammonium chloride decreases, and the ammonium chloride in the solution will precipitate from the solution to form ammonium chloride solid crystals;

[0017] Step S402: Drying treatment: The separated ammonium chloride crystals need to be dried to remove residual moisture, and the crystals are dissolved again by recrystallization, and after filtering to remove impurities, they are cooled and crystallized again to obtain ammonium chloride with higher purity;

[0018] Step S403: NH4Cl product: The dried pure ammonium chloride crystals form NH4Cl product.

[0019] Optionally, the method for capturing carbon dioxide in industrial waste gas to produce alkali further includes step S500: decomposing ammonium chloride NH4Cl to produce ammonia NH3, and the ammonia NH3 can enter the carbonization cleaning tower.

[0020] Optionally, the method for capturing carbon dioxide in industrial waste gas to produce alkali further includes step S600: feeding the Na2CO3 product into an alkali dissolving machine to form a Na2CO3 solution, and reacting the Na2CO3 solution with urea CO(NH2)2 to generate a NaOCN product.

[0021] Optionally, in step S600, carbon dioxide CO2 and ammonia NH3 are generated in the reaction between Na2CO3 solution and urea CO(NH2)2, which can be used to supplement carbon dioxide CO2 and ammonia NH3 in industrial waste gas.

[0022] The beneficial effects achieved by the present invention are as follows:

[0023] (1) In the present application, in step S400, the carbon dioxide CO2 generated by steam calcining NaHCO3 is captured and transported back to the carbonization cleaning tower to further replenish and recover the carbon dioxide CO2 in the industrial waste gas. In step S500, after the ammonium chloride NH4Cl is decomposed to generate ammonia, the ammonia NH3 is captured and transported back to the carbonization cleaning tower to further replenish and recover the ammonia NH3 in the industrial waste gas. In step S600, the carbon dioxide CO2 and ammonia NH3 generated simultaneously with the generation of sodium cyanate NaOCN can also further replenish and recover the carbon dioxide CO2 and ammonia NH3 in the industrial waste gas, forming a carbon dioxide CO2 recycling closed loop, an ammonia NH3 recycling closed loop and a carbon dioxide CO2 and ammonia NH3 recycling closed loop. The capture and recovery of carbon dioxide CO2 not only reduces the emission of waste gas, but also reduces the impact of greenhouse gases and reduces pollution to the environment.

[0024] (2) In the present application, in step S200, carbon dioxide reacts with ammonia to generate ammonium carbonate (NH4)2CO3, in step S300, ammonium carbonate (NH4)2CO3 reacts with sodium chloride NaCl to generate sodium bicarbonate NaHCO3 and ammonium chloride NH4Cl, in step S400, NaHCO3 is subjected to steam calcination reaction to generate sodium carbonate Na2CO3 (soda ash), and NH4Cl is subjected to cooling crystallization to obtain pure chloride, and in step S600, Na2CO3 solution reacts with urea to generate sodium cyanate NaOCN, and carbon dioxide CO2 and ammonia NH3 in industrial waste gas are converted into valuable chemical products: sodium carbonate Na2CO3 products, ammonium chloride NH4Cl products, sodium cyanate NaOCN products, which are widely used in fertilizer production, chemical synthesis, agriculture and other industrial fields, and can provide important raw materials for related industries and improve industrial efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments are 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 creative work.

[0026] Figure 1 A schematic diagram of the composition of a device for capturing carbon dioxide from industrial waste gas and making alkali according to the present invention;

[0027] Figure 2 A schematic diagram of a process for capturing carbon dioxide from industrial waste gas and producing alkali according to the present invention;

[0028] Figure 3 A schematic diagram of the principle of a method for capturing carbon dioxide from industrial waste gas to produce alkali applied for by the present invention;

[0029] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments; based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention. In order to make the purpose, technical solution and advantages of the present invention clearer, the implementation methods of the present invention will be further described in detail below in conjunction with the drawings.

[0032] First, as Figure 1 As shown, a carbon dioxide capture and alkali-making device in industrial waste gas includes: a capture unit, which processes the industrial waste gas and captures carbon dioxide CO2 and ammonia NH3 in the industrial waste gas; a first reaction unit, which passes the carbon dioxide CO2 and ammonia NH3 in the industrial waste gas into a carbonization cleaning tower for reaction to generate ammonium carbonate (NH4)2CO3; a second reaction unit, which reacts ammonium carbonate (NH4)2CO3 with a sodium chloride NaCl solution to generate sodium bicarbonate NaHCO3 and ammonium chloride NH4Cl, and separates the sodium bicarbonate NaHCO3 and the ammonium chloride NH4Cl; a third reaction unit one, which steam-calcines the separated sodium bicarbonate NaHCO3 to generate a Na2CO3 product; and a third reaction unit two, which cools and crystallizes the separated ammonium chloride NH4Cl to generate an NH4Cl product.

[0033] In some embodiments, the first reaction unit includes a carbonization cleaning tower, which is provided with an air inlet for respectively introducing carbon dioxide and ammonia in industrial waste gas; the carbonization cleaning tower is provided with a gas distributor so that carbon dioxide and ammonia can be evenly mixed and fully contacted, and the carbonization cleaning tower is also equipped with a multi-layer spray device, which can spray an appropriate amount of water mist to allow carbon dioxide CO2 and ammonia NH3 to react to generate ammonium carbonate (NH4)2CO3. The reacted ammonium carbonate (NH4)2CO3 can be discharged from the bottom discharge port of the carbonization cleaning tower.

[0034] In some embodiments, the second reaction unit comprises a reactor, and the reactor is provided with an inlet for ammonium carbonate solution and an inlet for sodium chloride solution, and a pipeline is connected to a precise metering device to ensure that the two are fed in proportion. A powerful agitator is provided in the reactor to allow the solution to be quickly and fully mixed and reacted. The mixed solution after the reaction flows into a sedimentation tank, and an alkali washer can be used. The alkali washer utilizes the difference in solubility of sodium bicarbonate and ammonium chloride for separation, and sodium bicarbonate is precipitated at the bottom of the tank, and the ammonium chloride solution is on the upper layer. There is a discharge port at the bottom of the tank connected to a filter to filter out impurities to obtain purer sodium bicarbonate. The upper ammonium chloride solution enters a subsequent processing device through an overflow pipe, and operations such as crystallization can be performed to obtain ammonium chloride crystals.

[0035] In some embodiments, the third reaction unit 301 includes a steam calcining furnace, and a high-temperature resistant and evenly distributed material tray is provided inside the steam calcining furnace for placing sodium bicarbonate material; the steam calcining furnace includes a steam generating device, which controls the steam input amount and temperature so that the steam can fully contact with the sodium bicarbonate for calcination reaction; an exhaust port is provided on the top of the steam calcining furnace to discharge the furnace gas containing carbon dioxide, water vapor and possible impurity gases generated by the reaction, and a discharge port is provided at the bottom of the steam calcining furnace, through which the calcined sodium carbonate product can be discharged and enter the subsequent cooling and packaging process, and the furnace body structure of the entire steam calcining furnace is well sealed to ensure a stable and safe reaction environment.

[0036] In some embodiments, the third reaction unit 2 402 includes a cooling crystallizer, which includes a tank body with a jacket, and a cooling medium, such as cooling water, can be introduced into the jacket to control the cooling temperature in the tank. The tank body is provided with a stirring paddle to evenly cool the ammonium chloride solution to prevent local overcooling; a solution inlet is provided at the top of the tank body, which is connected to an ammonium chloride solution source, and a discharge port is provided at the bottom of the tank body for discharging the crystallized ammonium chloride product. The cooling crystallizer may also include a temperature sensor and a liquid level meter to monitor and control the crystallization process in real time to ensure the production of high-purity, uniformly sized ammonium chloride products.

[0037] Therefore, in the carbon dioxide capture and alkali-making device in industrial waste gas applied for by the present invention, through the integrated multiple reaction units, the capture unit can accurately process the industrial waste gas, quickly capture the carbon dioxide CO2 and ammonia NH3 therein, ensure that the harmful gases in the waste gas are effectively removed, and reduce pollution to the environment; the first reaction unit reacts carbon dioxide with ammonia through a carbonization cleaning tower to generate ammonium carbonate (NH4)2CO3, providing high-purity raw materials for subsequent reactions; the second reaction unit reacts with ammonium carbonate through sodium chloride solution to generate sodium bicarbonate and ammonium chloride, and effectively separates them through an alkali washing machine; the third reaction unit 1 converts sodium bicarbonate into sodium carbonate through steam calcination technology; the third reaction unit 2 produces high-purity ammonium chloride through cooling crystallization technology, realizing the production of sodium carbonate Na2CO3 products and ammonium chloride NH4Cl products, which can not only realize the effective recovery and recycling of carbon dioxide, but also generate valuable chemical products through multiple reactions and resource conversion, achieving a good balance between environmental protection and economic benefits, and greatly adapting to the sustainable development needs of current industrial production.

[0038] Optionally, the carbon dioxide capture and alkali production device in industrial waste gas also includes: a dissolution unit and a third reaction unit three, the dissolution unit dissolves the Na2CO3 product to form a Na2CO3 solution, and the third reaction unit three reacts the Na2CO3 solution with urea CO(NH2)2 to generate a NaOCN product.

[0039] In some embodiments, the dissolution unit includes a dissolution tank, with a Na2CO3 product feed port and a solvent water inlet at the top, both of which are equipped with flow control devices. An agitator is installed inside the dissolution tank to promote dissolution, and a discharge port is provided at the bottom; at the same time, the third reaction unit 3 403 includes a reaction tank, and a stirring device is provided inside the reaction tank to enable the sodium carbonate solution and urea to be fully mixed. There is a feed port at the top of the reaction tank, which is connected to the delivery pipelines of the sodium carbonate solution and urea respectively, and is equipped with a precise metering device to control the feed ratio. The tank body of the reaction tank can be wrapped with a heating jacket to adjust and maintain the temperature required for the reaction. There is a discharge port at the bottom of the reaction tank, which is connected to a filter for separating the NaOCN product generated by the reaction from other impurities or unreacted substances. At the same time, pressure monitoring and safety valves are provided to ensure the safe and stable progress of the reaction.

[0040] In the present application, sodium cyanate NaOCN is generated by the reaction of urea and Na2CO3, thereby further improving the added value of sodium carbonate products. Sodium cyanate can be used in various industries such as fertilizers and plastics, thus promoting the recycling of resources. While effectively capturing carbon dioxide and generating sodium carbonate and ammonium chloride, higher value products are generated through dissolution and reaction processes, thus achieving the resource utilization and environmental protection goals in the waste gas treatment process, and further improving the economic benefits and environmental protection effects.

[0041] Optionally, the carbon dioxide capture and alkali production device in industrial waste gas also includes: a carbon dioxide capture and transportation unit, an ammonia capture and transportation unit, the carbon dioxide capture and transportation unit captures the carbon dioxide after steam calcination of sodium bicarbonate NaHCO3, and transports the carbon dioxide to the first reaction unit, and the ammonia capture and transportation unit captures the ammonia generated by the decomposition of the NH4Cl product, and transports the ammonia to the first reaction unit.

[0042] In some embodiments, the diammonia gas capture and delivery unit includes a gas collection hood, a condenser, a gas delivery pipe, and a fan. The gas collection hood collects ammonia gas generated by the decomposition of ammonium chloride, the condenser removes water vapor impurities therein, the gas delivery pipe connects the gas collection hood with the first reaction unit, and the fan provides power to promote the stable delivery of ammonia gas along the pipeline to the first reaction unit, thereby ensuring the recovery and reuse of ammonia gas.

[0043] In the present application, the carbon dioxide capture and delivery unit can efficiently capture the carbon dioxide generated during the steam calcination of sodium bicarbonate NaHCO3, and promptly deliver it to the first reaction unit (middle carbonization cleaning tower) for secondary recycling, which not only reduces carbon dioxide emissions, but also the recycling of carbon dioxide can improve the carbon dioxide utilization rate and reaction efficiency during the reaction of ammonium carbonate (NH4)2CO in the first reaction unit, and improve the efficiency and quality of ammonium carbonate generation; the ammonia capture and delivery unit can capture and deliver the ammonia released during the decomposition of the NH4Cl product, and reflux it to the first reaction unit, ensuring the utilization rate and reaction efficiency of ammonia during the reaction of ammonium carbonate (NH4)2CO in the first reaction unit, and improving the efficiency and quality of ammonium carbonate generation. Thus, through the efficient recovery and recycling of carbon dioxide and ammonia, the production process of sodium carbonate and ammonium chloride is optimized, and the stability, economy and environmental friendliness of the production process are enhanced.

[0044] Optionally, the carbon dioxide capture and alkali production device in industrial waste gas also includes: a carbon dioxide and ammonia capture and transportation unit, which captures carbon dioxide and ammonia generated by the reaction of Na2CO3 solution and urea CO(NH2)2, and transports the carbon dioxide and ammonia to the first reaction unit.

[0045] In some embodiments, the carbon dioxide and ammonia gas capture and delivery unit includes a gas collection hood, a gas pipeline, a compressor, and a purification device. The gas collection hood is located above the third reaction unit 3 403 to collect gases such as carbon dioxide and ammonia after the reaction is completed. The gas pipeline is connected to the gas collection hood. The compressor is installed on the gas pipeline to provide gas delivery power. The purification device is used to remove impurities and moisture in the gas to ensure gas purity. The purified carbon dioxide and ammonia are transported to the carbonization cleaning tower of the first reaction unit through the pipeline.

[0046] In the present application, the carbon dioxide and ammonia capture and transportation unit can efficiently capture the carbon dioxide and ammonia generated during the reaction of Na2CO3 solution and urea, and transport them to the first reaction unit in time, realizing dual gas capture and transportation, avoiding the waste of carbon dioxide and ammonia, and ensuring the optimized ratio of carbon dioxide and ammonia during the reaction of ammonium carbonate (NH4)2CO in the first reaction unit, improving the efficiency and quality of ammonium carbonate generation, and enhancing the overall environmental performance and sustainability of the carbon dioxide capture and alkali production device in industrial waste gas.

[0047] Second, as Figure 2 As shown, a method for capturing carbon dioxide in industrial waste gas to make alkali, using or not using the device for capturing carbon dioxide in industrial waste gas to make alkali as described in any one of the first aspects above, comprises:

[0048] Step S100: treating the industrial waste gas to capture carbon dioxide CO2 and ammonia NH3 in the industrial waste gas;

[0049] Specifically, step S100 includes: the industrial waste gas treatment process covers multiple treatment operations, including at least dust removal, filtration and separation of industrial waste gas to obtain carbon dioxide CO2 and ammonia NH3 in industrial waste gas. In this way, through dust removal, filtration and separation operations, impurity particles, harmful pollutants, etc. in the waste gas can be effectively removed, the waste gas can be purified, and the pollution emissions to the environment can be reduced, meeting the environmental quality requirements. When obtaining carbon dioxide and ammonia, a way is opened up for resource recycling, resource utilization is improved, and the cost of raw materials for enterprises is reduced. Carbon dioxide and ammonia can be extracted, making subsequent carbon dioxide capture more efficient, and alkali raw materials more sufficient and of guaranteed quality, which effectively promotes the smooth progress of the alkali process and improves the stability and economy of the entire production process.

[0050] Step S200: Carbon dioxide CO2 and ammonia NH3 in industrial waste gas are introduced into a carbonization cleaning tower to generate ammonium carbonate (NH4)2CO3;

[0051] Specifically, step S200 includes:

[0052] In the industrial waste gas treatment process, when industrial waste gas rich in carbon dioxide CO2 and ammonia NH3 is introduced into the carbonization cleaning tower, under the internal environmental conditions of the carbonization cleaning tower, the carbon dioxide CO2 and ammonia NH3 in the industrial waste gas meet with the water H2O in the carbonization cleaning tower. Under the synergistic effect of suitable temperature, pressure, uniform mixing and other chemical conditions, a chemical reaction occurs to generate ammonium carbonate (NH4)2CO3. The reaction process equation is:

[0053] 2NH3+CO2+H2O→(NH4)2CO3.

[0054] Therefore, this chemical reaction has relatively mild reaction conditions and does not require extremely stringent equipment, which reduces the difficulty and cost of industrial implementation. It can efficiently convert carbon dioxide and ammonia in waste gas, realize the initial integrated utilization of resources, reduce harmful gas emissions, and comply with environmental protection concepts. At the same time, carbon dioxide CO2 and ammonia NH3 originally present in industrial waste gas in gaseous form are converted into ammonium carbonate (NH4)2CO3. Ammonium carbonate (NH4)2CO3 itself is relatively stable and easy to process and utilize. It is an important intermediate product for subsequent alkali production and other processes, providing a key connection for the entire industrial waste gas treatment and resource recovery chain, which helps to improve the quality and output of alkali production and other products.

[0055] Step S300: in a reaction tower, reacting ammonium carbonate (NH4)2CO3 with sodium chloride NaCl solution to generate sodium bicarbonate NaHCO3 and ammonium chloride NH4Cl, and separating the sodium bicarbonate NaHCO3 and ammonium chloride NH4Cl;

[0056] Specifically, step S300 includes:

[0057] In the reaction tower, ammonium carbonate (NH4)2CO3 and sodium chloride NaCl solution react to generate sodium bicarbonate NaHCO3 and ammonium chloride NH4Cl. The reaction equation of ammonium carbonate (NH4)2CO3 and sodium chloride NaCl solution is:

[0058] (NH4)2CO 3+2 NaCl→2NaHCO3+2NH4Cl.

[0059] In some embodiments, sodium bicarbonate NaHCO3 and ammonium chloride NH4Cl are separated by a caustic soda washer, which generally refers to a device used for treating alkaline substances (such as sodium bicarbonate, sodium hydroxide, etc.). In production, by-products (such as ammonium chloride) are often removed from the solution by this device to improve the purity of the main product. The caustic soda washer equipment can be a simple filtering device or a complex continuous flow system, depending on the properties of the mixture being treated and the separation requirements. Specifically, in the separation process of sodium bicarbonate (NaHCO3) and ammonium chloride (NH4Cl), the role of the caustic soda washer is to utilize the solubility difference of different substances in the solution, by adjusting the temperature, pH value and other conditions of the solution, through filtering, cleaning and washing steps, and finally achieving the separation of sodium bicarbonate (NaHCO3) and ammonium chloride (NH4Cl), thereby obtaining a pure product.

[0060] Therefore, in the present invention application, firstly, the raw materials ammonium carbonate and sodium chloride used in this chemical reaction are relatively cheap and easy to obtain, and the reaction process can produce two products with wide applications: sodium bicarbonate and ammonium chloride. Sodium bicarbonate can be widely used in detergents, food leavening agents and pharmaceutical products, while ammonium chloride can be widely used in agricultural fertilizers, chemical reagents and metal surface treatment. Secondly, the reaction process is simple and the reaction conditions are mild. The reaction is carried out at room temperature, which avoids the energy consumption and equipment wear caused by high-temperature operation. The reaction occurs in an aqueous solution, which has good reaction controllability, and the yield of the product can be optimized by adjusting the concentration of the reactants and the reaction time. In addition, the sodium bicarbonate generated by the reaction is usually precipitated in a solid form, which is convenient for separation and purification, so that the yield of the sodium bicarbonate product is high, and the generated ammonium chloride is dissolved in water, which can be further extracted by evaporation and concentration to ensure the quality of the product. In addition, the reaction has little impact on the environment and belongs to a green chemical reaction. No harmful waste gas or pollutants are generated during the reaction. It has great application potential in industrial production, reduces production costs and environmental pollution risks, and performs outstandingly in terms of the comprehensive benefits of chemical production.

[0061] Step S400: steam calcining the separated sodium bicarbonate NaHCO3 to generate Na2CO3 product, and cooling and crystallizing the ammonium chloride NH4Cl to generate NH4Cl product.

[0062] Specifically, step S400 includes:

[0063] The reaction equation of the sodium bicarbonate NaHCO3 in the solution after the reaction is calcined by steam is:

[0064] 2NaHCO3→Na2CO3+CO2+H2O.

[0065] Thus, first, the calcination or thermal decomposition reaction of sodium bicarbonate is usually carried out under high temperature conditions, and the temperature needs to reach between 300°C and 400°C to ensure the high efficiency of the reaction and the high purity of the product; sodium bicarbonate will decompose into sodium carbonate, carbon dioxide and water after heating, that is, the calcination reaction can convert sodium bicarbonate into more stable and widely used sodium carbonate Na2CO3 (soda ash), and sodium carbonate Na2CO3 (soda ash) can be widely used in technical fields such as glass manufacturing, fertilizer production, detergents and chemical synthesis. Thus, the calcination reaction of sodium bicarbonate NaHCO3 not only provides an effective way to produce sodium carbonate, but also can contribute to the recovery and utilization of carbon dioxide; in addition, by controlling the temperature of ammonium chloride solution, ammonium chloride will precipitate from the saturated solution to form crystals, and impurities can be effectively excluded, ensuring the high purity of the prepared ammonium chloride product, ammonium chloride can be precipitated in solid form, and is also convenient for subsequent separation, drying and packaging, thereby improving the production efficiency of the ammonium chloride product, and does not require complex equipment and high energy consumption, simple operation and low cost, and ammonium chloride can be used as a widely used fertilizer or industrial raw material.

[0066] Optionally, in step S400, during the steam calcination of NaHCO3, the furnace gas is condensed and washed to release carbon dioxide CO2, and the carbon dioxide CO2 is transported to the carbonization washing tower.

[0067] In some embodiments, first, in the aforementioned steam calcining furnace, sodium bicarbonate (NaHCO3) is decomposed into sodium carbonate (Na2CO3), carbon dioxide (CO2) and water (H2O) by heat. The calcining process is usually carried out at high temperature (about 300°C to 400°C), and the furnace gas contains carbon dioxide, water vapor and possible impurity gases; then, the furnace gas first enters a cooling device (such as a cooling tower, a cooler, etc.). During the cooling process, the gas temperature gradually decreases, and the water vapor condenses into liquid water. The cooled furnace gas enters a washing device, which is usually filled with a washing liquid (such as water or a weak acid solution). When the furnace gas passes through the washing tower, the washing liquid can absorb soluble substances, dust and impurities in the gas to ensure the purity of the carbon dioxide; finally, after condensation and washing, the carbon dioxide in the furnace gas is separated from the mixed gas to obtain a relatively pure carbon dioxide gas flow. The pure carbon dioxide can be further processed or compressed, stored or transported to a carbonization cleaning tower to participate in subsequent chemical reactions. Therefore, carbon dioxide is extracted from the furnace gas and captured and utilized again, which helps to save resources and reduce greenhouse gas emissions. In addition, the carbon dioxide has a higher purity after washing. The recycling of carbon dioxide can promote the continuous progress of the reaction. Carbon dioxide can be used as a raw material to participate in the synthesis of ammonium carbonate (NH4)2CO3, thereby improving the economy and production efficiency of the reaction.

[0068] Optionally, in step S400, cooling and crystallizing ammonium chloride NH4Cl to generate NH4Cl product includes the following steps:.

[0069] Step S401: Cooling the ammonium chloride solution: When the ammonium chloride solution reaches a saturated state, the solution is gradually cooled by controlling the temperature. As the temperature decreases, the solubility of ammonium chloride decreases, and the ammonium chloride in the solution will precipitate from the solution to form solid ammonium chloride crystals. The crystallization process is affected by the temperature and solution concentration. The cooled ammonium chloride crystals are usually deposited at the bottom of the solution. The ammonium chloride crystals can be separated from the mother liquor by filtration, centrifugation, etc.

[0070] Step S402: Drying treatment: If impurities exist during the crystallization process, the crystals can be dissolved again by recrystallization, and after filtering to remove impurities, cooling and crystallization are performed again. The separated ammonium chloride crystals need to be dried to remove residual moisture. Common drying methods include hot air drying, vacuum drying, etc.; higher purity ammonium chloride is obtained.

[0071] Step S403: NH4Cl product: The dried pure ammonium chloride crystals form NH4Cl product. The NH4Cl product can be crushed and packaged as needed and further used as fertilizer or industrial raw material or chemical reagent.

[0072] In the present application, cooling crystallization is a mature separation and purification method with simple operation and relatively low equipment investment. A high-purity ammonium chloride product can be obtained by cooling crystallization, which is suitable for the production of high-purity chemical reagents or fertilizers. The cooling crystallization process is relatively energy-saving and does not generate a large amount of waste gas or wastewater, and has important application value in industrial production.

[0073] Optionally, the method for capturing carbon dioxide in industrial waste gas to produce alkali further includes step S500: decomposing ammonium chloride NH4Cl to produce ammonia NH3, and the ammonia NH3 can enter the carbonization cleaning tower.

[0074] In some embodiments, ammonium chloride NH4Cl is decomposed at high temperature to generate ammonia NH3 and hydrogen chloride HCl, usually at a temperature of about 350°C to 450°C, and the reaction formula is:

[0075] NH4Cl→NH3+HCl.

[0076] In some embodiments, the generated ammonia gas NH3 and hydrogen chloride HCl usually coexist in the reactor. In order to ensure the purity of the ammonia gas, impurities such as hydrogen chloride HCl can be removed by gas separation methods. After cooling and purification, the ammonia gas NH3 will enter the carbonization cleaning tower, where the ammonia gas NH3 reacts with water and carbon dioxide CO2 to form ammonium carbonate (NH4)2CO3.

[0077] In the present application, ammonia is generated by decomposing ammonium chloride and is fed into a carbonization cleaning tower, thereby increasing the ammonia content. This not only helps to form ammonium carbonate (NH4)2CO3, but can also be recycled, which has a significant effect on improving production efficiency and reducing pollution.

[0078] Optionally, the method for capturing carbon dioxide in industrial waste gas to produce alkali further includes step S600: feeding the Na2CO3 product into an alkali dissolving machine to form a Na2CO3 solution, and reacting the Na2CO3 solution with urea CO(NH2)2 to generate a NaOCN product.

[0079] In some embodiments, the sodium carbonate Na2CO3 product is fed into an alkali dissolving machine to form a Na2CO3 solution, and then the Na2CO3 solution is reacted with urea CO(NH2)2 to generate a NaOCN (sodium cyanate) product. Specifically, the alkali dissolving machine is a device for dissolving alkaline substances, usually using water or other solvents, and completely dissolving the Na2CO3 product in water or other solvents at a certain temperature and pressure, and the sodium carbonate Na2CO3 product will eventually be converted into a saturated Na2CO3 solution or a concentrated Na2CO3 solution.

[0080] In some embodiments, Na2CO3 solution is mixed with urea CO(NH2)2, usually at a moderate temperature, and heating conditions can also be used to promote the reaction, to generate sodium cyanate NaOCN and ammonia NH3, and the reaction equation is:

[0081] Na2CO3+CO(NH2)2→NaOCN+NH3+CO2.

[0082] After the reaction is completed, sodium cyanate NaOCN can be separated by filtration, crystallization, drying, etc. to obtain pure NaOCN products. Sodium cyanate NaOCN products can be widely used in fertilizer, pesticide production, chemical synthesis and other fields.

[0083] Optionally, in step S600, carbon dioxide CO2 and ammonia NH3 are generated in the reaction between Na2CO3 solution and urea CO(NH2)2, which can be used to supplement carbon dioxide CO2 and ammonia NH3 in industrial waste gas.

[0084] In some embodiments, the carbon dioxide CO2 and ammonia NH generated by the reaction of Na2CO3 solution with urea CO(NH2)2 can not only provide raw materials for chemical synthesis and fertilizer production, but also effectively replenish and recycle carbon dioxide in industrial waste gas, effectively reduce the emission of industrial waste gas, and reduce the impact of greenhouse gases.

[0085] Therefore, in the method for capturing and making alkali from carbon dioxide in industrial waste gas of the present invention, first, in step S400, carbon dioxide CO2 generated by steam calcining NaHCO3 is captured and transported back to the carbonization cleaning tower to further replenish and recover carbon dioxide CO2 in the industrial waste gas. In step S500, after ammonium chloride NH4Cl decomposes to generate ammonia, ammonia NH3 is captured and transported back to the carbonization cleaning tower to further replenish and recover ammonia NH3 in the industrial waste gas. In step S600, carbon dioxide CO2 and ammonia NH3 generated simultaneously with the generation of sodium cyanate NaOCN can also further replenish and recover carbon dioxide CO2 and ammonia NH3 in the industrial waste gas, forming a carbon dioxide CO2 recycling closed loop, an ammonia NH3 recycling closed loop and a carbon dioxide CO2 and ammonia NH3 recycling closed loop. The capture and recovery of carbon dioxide CO2 not only reduces the emission of waste gas, but also reduces greenhouse gas emissions. In addition, in step S200, carbon dioxide reacts with ammonia to generate ammonium carbonate (NH4)2CO3, in step S300, ammonium carbonate (NH4)2CO3 reacts with sodium chloride NaCl to generate sodium bicarbonate NaHCO3 and ammonium chloride NH4Cl, in step S400, NaHCO3 is calcined by steam to generate sodium carbonate Na2CO3 (soda ash), NH4Cl is cooled and crystallized to obtain pure chloride, in step S600, Na2CO3 solution reacts with urea to generate sodium cyanate NaOCN, and carbon dioxide CO2 and ammonia NH3 in industrial waste gas are converted into valuable chemical products: sodium carbonate Na2CO3 products, ammonium chloride NH4Cl products, sodium cyanate NaOCN products, which are widely used in fertilizer production, chemical synthesis, agriculture and other industrial fields, and can provide important raw materials for related industries and improve industrial efficiency.

[0086] Therefore, the present invention adopts a method for capturing carbon dioxide in industrial waste gas to produce alkali, which can not only realize the effective recovery and recycling of carbon dioxide, but also generate valuable chemical products through multiple reactions and resource conversions, thereby achieving a good balance between environmental protection and economic benefits. It plays an important role in reducing waste gas emissions, improving resource utilization efficiency, reducing environmental pollution, and improving corporate benefits, and greatly adapts to the current sustainable development needs of industrialized production.

[0087] The present invention and its implementation methods are described above, but such description is not restrictive. The drawings show only one implementation method of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in this field are inspired by it and design structural methods and embodiments similar to the technical solution without creativity without departing from the purpose of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A device for capturing carbon dioxide from industrial waste gas and making alkali, characterized in that: include: The capture unit processes the industrial waste gas and captures the carbon dioxide CO2 and ammonia NH3 in the industrial waste gas; the first reaction unit passes the carbon dioxide CO2 and ammonia NH3 in the industrial waste gas into a carbonization cleaning tower for reaction to generate ammonium carbonate (NH4)2CO3; the second reaction unit reacts the ammonium carbonate (NH4)2CO3 with a sodium chloride NaCl solution to generate sodium bicarbonate NaHCO3 and ammonium chloride NH4Cl, and separates the sodium bicarbonate NaHCO3 and ammonium chloride NH4Cl; the third reaction unit one steam calcines the separated sodium bicarbonate NaHCO3 to generate a Na2CO3 product; the third reaction unit two cools and crystallizes the separated ammonium chloride NH4Cl to generate an NH4Cl product.

2. The device for capturing carbon dioxide from industrial waste gas and making alkali according to claim 1, characterized in that: The carbon dioxide capture and alkali production device in industrial waste gas also includes: a dissolution unit and a third reaction unit three. The dissolution unit dissolves the Na2CO3 product to form a Na2CO3 solution, and the third reaction unit three reacts the Na2CO3 solution with urea CO(NH2)2 to generate a NaOCN product.

3. The device for capturing carbon dioxide from industrial waste gas and making alkali according to claim 1, characterized in that: The device for capturing and making alkali from carbon dioxide in industrial waste gas also includes: a carbon dioxide capturing and conveying unit and an ammonia capturing and conveying unit. The carbon dioxide capturing and conveying unit captures carbon dioxide after steam calcination of sodium bicarbonate NaHCO3, and conveys the carbon dioxide to the first reaction unit; the ammonia capturing and conveying unit captures ammonia generated by decomposition of NH4Cl products, and conveys the ammonia to the first reaction unit.

4. The device for capturing carbon dioxide from industrial waste gas and making alkali according to claim 1, characterized in that: The carbon dioxide capture and alkali production device in industrial waste gas also includes: a carbon dioxide and ammonia capture and transportation unit, which captures carbon dioxide and ammonia generated by the reaction of Na2CO3 solution and urea CO(NH2)2, and transports the carbon dioxide and ammonia to the first reaction unit.

5. A method for capturing carbon dioxide in industrial waste gas to produce alkali, comprising the following steps: Step S100: treating the industrial waste gas to capture carbon dioxide CO2 and ammonia NH3 in the industrial waste gas; Step S200: Carbon dioxide CO2 and ammonia NH3 in industrial waste gas are introduced into a carbonization cleaning tower to generate ammonium carbonate (NH4)2CO3; Step S300: in a reaction tower, reacting ammonium carbonate (NH4)2CO3 with sodium chloride NaCl solution to generate sodium bicarbonate NaHCO3 and ammonium chloride NH4Cl, and separating the sodium bicarbonate NaHCO3 and ammonium chloride NH4Cl; Step S400: steam calcining the separated sodium bicarbonate NaHCO3 to generate Na2CO3 product, and cooling and crystallizing the ammonium chloride NH4Cl to generate NH4Cl product.

6. The method for capturing carbon dioxide in industrial waste gas to produce alkali according to claim 5, characterized in that: In step S400, during the steam calcination of NaHCO3, the furnace gas is condensed and washed to release carbon dioxide CO2, which is transported to a carbonization washing tower.

7. The method for producing alkali by capturing carbon dioxide in industrial waste gas according to claim 6, characterized in that: Step S400 includes: Step S401: Cooling the ammonium chloride solution: When the ammonium chloride solution reaches a saturated state, the solution is gradually cooled by controlling the temperature. As the temperature decreases, the solubility of ammonium chloride decreases, and the ammonium chloride in the solution will precipitate from the solution to form ammonium chloride solid crystals; Step S402: Drying treatment: dissolving the crystals again by recrystallization, filtering to remove impurities, and cooling and crystallizing again. The separated ammonium chloride crystals need to be dried to remove residual moisture and obtain ammonium chloride with higher purity; Step S403: NH4Cl product: The dried pure ammonium chloride crystals form NH4Cl product.

8. The method for capturing carbon dioxide in industrial waste gas and producing alkali according to claim 7, characterized in that: The method for capturing carbon dioxide in industrial waste gas and producing alkali also includes step S500: decomposing ammonium chloride NH4Cl to produce ammonia NH3, and the ammonia NH3 enters a carbonization cleaning tower.

9. The method for capturing carbon dioxide in industrial waste gas and producing alkali according to claim 8, characterized in that: The method for capturing carbon dioxide in industrial waste gas and producing alkali also includes step S600: feeding the Na2CO3 product into an alkali dissolving machine to form a Na2CO3 solution, and reacting the Na2CO3 solution with urea CO(NH2)2 to generate a NaOCN product.

10. The method for producing alkali by capturing carbon dioxide in industrial waste gas according to claim 9, characterized in that: In step S600, in the reaction between Na2CO3 solution and urea CO(NH2)2, carbon dioxide CO2 and ammonia NH3 are generated, which can be used as supplements for carbon dioxide CO2 and ammonia NH3 in industrial waste gas.

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