A device for coupling preparation of soda ash based on ammonia method and sodium sulfate waste salt

Abstract

This invention discloses an apparatus for producing soda ash based on the coupling of ammonia-based carbon capture and sodium sulfate waste salt. The apparatus includes an ammonia-based carbon capture section, comprising a carbon capture tower with a flue gas inlet on its lower side wall. The carbon capture tower is connected to a concentrated ammonia water storage tank and has multiple ammonia water spray inlets. The concentrated ammonia water storage tank is connected to these inlets via a circulating pump. The carbon capture tower is connected to an ammonium bicarbonate crystallization tank via an ammonium bicarbonate enrichment pipeline. The ammonium bicarbonate crystallization tank is connected to an ammonium bicarbonate solution storage tank, which is connected to the tube-side inlet of a heat exchanger. The tube-side outlet of the heat exchanger is connected to a reaction vessel, into which ammonium bicarbonate solution and sodium sulfate solution are fed to prepare soda ash. This invention uses ammonium bicarbonate, a product of ammonia-based carbon capture, and sodium sulfate waste salt as raw materials to produce high-value-added soda ash, while simultaneously achieving high-value resource utilization through the synergistic treatment of waste gas decarbonization and waste salt.

Description

Technical Field

[0001] This utility model belongs to the field of energy-saving and environmental protection technology, and relates to the preparation of soda ash, specifically to an apparatus for preparing soda ash based on carbon capture by ammonia method and sodium sulfate waste salt coupling. Background Technology

[0002] In my country's industrial production, enterprises generate large quantities of industrial waste salt containing sodium sulfate through various means, including byproducts of acidification / condensation / washing processes, evaporation and crystallization of high-salt industrial wastewater, and crystallization of low-salt wastewater from "zero-discharge" wastewater treatment. According to relevant data, my country's industrial waste salt production was approximately 25 million tons in 2020 and is projected to reach 35 million tons by 2025. Currently, the added value of sodium sulfate products after purification from industrial waste salt is low, leading to large-scale stockpiling.

[0003] Meanwhile, enterprises generate large amounts of waste gas during industrial production, and a significant portion of this waste gas, including greenhouse gases such as carbon dioxide, is not effectively treated, contributing to a series of environmental problems, including accelerated global warming. Under my country's development goal of "peaking carbon and achieving carbon neutrality," CO2 capture technology has broad application prospects. Chemical absorption is the most widely used technical route, and ammonia water, as a carbon dioxide absorbent, produces ammonium bicarbonate (NH4HCO3), a fast-acting nitrogen fertilizer suitable for various crops. It is also an important chemical raw material with high resource value.

[0004] If sodium sulfate waste (mainly obtained from wastewater treatment) and ammonium bicarbonate (obtained from carbon capture in waste gas) can be used as raw materials to prepare soda ash (sodium carbonate) and ammonium sulfate through metathesis reaction, the problem of coupled and synergistic treatment of CO2 capture in waste gas and sodium sulfate waste product in industrial production can be solved, and high-value resource utilization can be achieved at the same time.

[0005] Soda ash (sodium carbonate), a bulk chemical raw material, is generally produced from sodium chloride via the ammonia-soda process (Solvay process) or the combined soda ash production process (Hou's process). Ammonium sulfate, a bulk fertilizer and industrial raw material, is generally produced by reacting sulfuric acid with ammonia or ammonium carbonate. Conventional methods for preparing soda ash and ammonium sulfate suffer from high costs and significant fluctuations in raw material prices. Currently, extensive research has been conducted both domestically and internationally on technical routes for preparing soda ash (sodium carbonate) from sodium sulfate. For example, Chinese patent CN104355326A discloses a thermal cycle process for co-producing soda ash and ammonium sulfate using sodium sulfate solution or carrier; Chinese patent CN111039310A discloses a method for preparing sodium bicarbonate from sodium sulfate and co-producing ammonium sulfate; Chinese patent CN117361583A discloses a method for extracting sodium sulfate from wastewater and co-producing sodium carbonate; and Chinese patent CN115321560A discloses a method for producing sodium bicarbonate from sodium sulfate via metathesis and co-producing ammonium sulfate. However, problems still exist, such as complex preparation processes, low raw material utilization, material waste in intermediate stages, high energy consumption, and insufficient product purity. Furthermore, the carbon capture products from waste gas and the sodium sulfate waste salt from wastewater treatment are not treated synergistically, resulting in low added value and significant stockpiling of sodium sulfate waste salt. Additionally, the ammonia-based carbon capture technology suffers from ammonia escape and ineffective utilization of the enriched products from the circulating washing liquid. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention proposes a device for the coupled preparation of soda ash using carbon capture via ammonia and sodium sulfate waste salt, thereby solving the problem that the carbon capture products and waste salt in the existing technology cannot be treated synergistically.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] An apparatus for producing soda ash based on carbon capture and sodium sulfate waste salt coupling using an ammonia method includes a soda ash preparation section, which includes a sodium sulfate impurity removal section, which includes a sodium sulfate wastewater impurity removal tank connected to a sodium sulfate solution storage tank, which is connected to the tube-side feed inlet of a heat exchanger.

[0009] An apparatus for producing soda ash by coupling carbon capture and sodium sulfate waste salt based on ammonia method further includes an ammonia carbon capture section. The ammonia carbon capture section includes a carbon capture tower. The lower side wall of the carbon capture tower is provided with a flue gas inlet. The lower side wall of the carbon capture tower is connected to a concentrated ammonia water storage tank through an ammonia water circulation pipe. The upper side wall of the carbon capture tower is provided with multiple ammonia water spray inlets. The concentrated ammonia water storage tank is connected to the multiple ammonia water spray inlets through a circulation pump to spray ammonia water into the carbon capture tower. The carbon capture tower is connected to the concentrated ammonia water storage tank through an ammonia water circulation pipe for circulating washing to generate ammonium bicarbonate.

[0010] The lower wall of the carbon capture tower is provided with an ammonium bicarbonate outlet, which is connected to the soda ash calcining furnace in the ammonium bicarbonate crystallization section through an ammonium bicarbonate enrichment liquid pipeline. The ammonium bicarbonate crystallization tank is connected to the ammonium bicarbonate solution storage tank, and the ammonium bicarbonate solution storage tank is connected to the tube-side feed inlet of the heat exchanger.

[0011] The tube outlet of the heat exchanger is connected to the reactor, and ammonium bicarbonate solution and sodium sulfate solution are fed into the reactor to prepare soda ash.

[0012] This utility model also has the following technical features: The soda ash outlet of the reactor is connected to the soda ash calcining furnace in the soda ash calcining section, and the product output end of the soda ash calcining furnace is connected to the sodium carbonate product pipeline.

[0013] The gas output end of the soda ash calcining furnace is connected to the shell-side input end of the heat exchanger, and the shell-side output end of the heat exchanger is connected to the carbon capture tower.

[0014] The carbon capture tower has a carbon capture tower flue gas outlet on its upper wall. The carbon capture tower flue gas outlet is connected to the ammonia escape control tower through a flue gas pipe. A liquid collector is installed in the middle of the ammonia escape control tower. The liquid collector divides the interior of the ammonia escape control tower into a lower water washing ammonia removal zone and an upper acid washing ammonia removal zone.

[0015] The lower side wall of the lower water washing and ammonia removal zone is provided with an ammonia escape control tower flue gas inlet, and the flue gas pipeline is connected to the ammonia escape control tower flue gas inlet.

[0016] The lower sidewall of the lower water washing and ammonia removal zone is connected to the water storage tank through a water circulation pipe. The upper sidewall of the lower water washing and ammonia removal zone is provided with a water washing liquid spray inlet. The water storage tank is connected to the water washing liquid spray inlet through a circulation pump to spray fresh water into the lower water washing and ammonia removal zone. The lower water washing and ammonia removal zone is connected to the water storage tank through a water circulation pipe for circulating washing. The water storage tank is provided with a water inlet.

[0017] The upper wall of the upper acid washing and ammonia removal zone is equipped with an ammonia escape control tower flue gas outlet.

[0018] The lower sidewall of the upper acid rinsing and deammoniation zone is connected to the ammonium sulfate solution storage tank via an ammonium sulfate circulation pipe. The upper sidewall of the upper acid rinsing and deammoniation zone is provided with an ammonium sulfate washing liquid spray inlet. The ammonium sulfate solution storage tank is connected to the ammonium sulfate washing liquid spray inlet via a circulation pump to spray the ammonium sulfate solution into the upper acid rinsing and deammoniation zone. The upper acid rinsing and deammoniation zone is connected to the ammonium sulfate solution storage tank via an ammonium sulfate circulation pipe for circulating washing.

[0019] The ammonia and ammonium bicarbonate outputs of the ammonium sulfate solution storage tank are connected to the ammonia stripping tower, and the output of the remaining mother liquor from the reactor is also connected to the ammonia stripping tower.

[0020] The gas output end of the ammonia stripping tower is connected to the shell-side input end of the heat exchanger, and the ammonium sulfate output end of the ammonia stripping tower is connected to the ammonium sulfate crystallization tank in the ammonium sulfate crystallization section.

[0021] The ammonium sulfate output end of the ammonium sulfate crystallizer is connected to an ammonium sulfate pipeline, and the ammonium sulfate output end of the ammonium sulfate crystallizer is also connected to an ammonium sulfate solution storage tank. The sodium sulfate output end of the ammonium sulfate crystallizer is connected to a sodium sulfate solution storage tank.

[0022] The reactor is equipped with a stirrer.

[0023] The concentrated ammonia storage tank is equipped with a concentrated ammonia inlet.

[0024] Compared with the prior art, the present invention has the following beneficial technical effects: (I) The apparatus for preparing soda ash based on ammonia carbon capture and sodium sulfate waste salt coupling proposed in this utility model selects relatively inexpensive ammonia water for ammonia carbon capture to obtain ammonium bicarbonate raw material, which solves the problem of high price of ammonium bicarbonate raw material when preparing soda ash from sodium sulfate waste salt. Using ammonium bicarbonate, the product of ammonia carbon capture, and sodium sulfate waste salt as raw materials, high value-added soda ash products can be produced. At the same time, ammonia carbon capture can also meet the decarbonization requirements of external front-end industrial waste gas and the waste gas generated by its own process, meet the green carbon reduction requirements of industrial production, and realize the high-value resource utilization of waste gas decarbonization and waste salt synergistic treatment.

[0025] (II) The apparatus for preparing soda ash based on the ammonia-based carbon capture and sodium sulfate waste salt coupling proposed in this utility model effectively recycles intermediate products and increases soda ash production. By selecting ammonium sulfate as the circulating pickling agent, ammonia and ammonium bicarbonate (residual in the flue gas from the initial carbon capture) enriched to a certain extent in the pickling circulating liquid can be fed into the ammonia stripping tower to extract ammonia, carbon dioxide, and water for recycling. The remaining product can be used in the downstream process to further produce ammonium sulfate, forming an effective recycling of the pickling agent and enriched products. This allows for secondary absorption and utilization of carbon dioxide and water generated during sodium bicarbonate calcination and ammonia, carbon dioxide, and water generated in the ammonia stripping tower, reducing material waste in intermediate stages and achieving the recycling of NH3 and CO2. This reduces material waste in intermediate stages, improves raw material utilization, and increases soda ash production.

[0026] (III) The device for preparing soda ash based on carbon capture and sodium sulfate waste salt coupling proposed in this utility model adopts a two-stage cyclic washing process of water washing and acid washing, which can effectively reduce the ammonia escape problem in the carbon capture process of ammonia method.

[0027] (IV) The device for preparing soda ash based on carbon capture and sodium sulfate waste salt coupling proposed in this utility model utilizes the secondary energy of the steam generated by high-temperature calcination of sodium bicarbonate and the high-temperature steam of the ammonia stripping tower in the process through a heat exchanger, which is used to heat the raw materials for the metathesis reaction, thereby reducing the overall energy consumption of the process.

[0028] (V) The device for preparing soda ash based on carbon capture and sodium sulfate waste salt coupling proposed in this utility model adopts the ammonia carbon capture process, which eliminates the need for the large carbonation tower equipment used in the traditional sodium sulfate to soda ash (sodium carbonate) process to recover residual ammonium bicarbonate from the reaction residue mother liquor, thus shortening the process flow and reducing equipment investment. In addition, the high-concentration sodium sulfate solution after wastewater pretreatment is used as raw material to prepare soda ash products, which can eliminate the ammonia removal process for the treatment of traditional nitrogen-containing sodium sulfate wastewater. At the same time, it realizes the resource utilization of ammonia components in wastewater, which has significant environmental and economic benefits. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the process flow for a device that couples carbon capture and sodium sulfate waste salt to produce soda ash based on the ammonia process.

[0030] Figure 2 This is the phase diagram for the reaction of sodium sulfate and ammonium bicarbonate.

[0031] The meanings of the labels in the diagram are as follows: 1-Ammonia carbon capture section, 2-Soda ash preparation section, 3-Heat exchanger, 4-Ammonia stripping tower, 5-Ammonium sulfate crystallization tank, 6-Pipeline, 7-Ammonium sulfate crystallization section.

[0032] 101-Carbon capture tower, 102-Ammonium bicarbonate enrichment liquid pipeline, 103-Ammonium bicarbonate crystallization tank, 104-Ammonium bicarbonate solution storage tank, 105-Ammonia water circulation pipeline, 106-Concentrated ammonia water storage tank, 107-Concentrated ammonia water inlet, 108-Flue gas pipeline, 109-Ammonia escape control tower, 110-Liquid collector, 111-Water circulation pipeline, 112-Water storage tank, 113-Water inlet, 114-Ammonium sulfate circulation pipeline, 115-Ammonium sulfate solution storage tank, 116-Ammonium bicarbonate crystallization section.

[0033] 201-Sodium sulfate wastewater removal tank, 202-Sodium sulfate solution storage tank, 203-Reaction vessel, 204-Soda ash calcination furnace, 205-Agitator, 206-Sodium carbonate product pipeline, 207-Sodium sulfate removal section, 208-Soda ash calcination section.

[0034] 10101 - Carbon capture tower flue gas inlet, 10102 - Ammonium bicarbonate outlet, 10103 - Ammonia water spray inlet, 10104 - Carbon capture tower flue gas outlet, 10901 - Lower water washing ammonia removal zone, 10902 - Upper acid washing ammonia removal zone, 10903 - Ammonia escape control tower flue gas inlet, 10904 - Water washing liquid spray inlet, 10905 - Ammonia escape control tower flue gas outlet, 10906 - Ammonium sulfate washing liquid spray inlet.

[0035] The specific content of this utility model will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0036] It should be noted that, unless otherwise specified, all equipment and materials in this utility model are based on existing technologies.

[0037] In this invention, the various devices are mainly connected by pipelines, and each pipeline is equipped with valves as needed, which are opened or closed according to process requirements. All valves in this invention are commonly used valves in the prior art.

[0038] In this invention, the ammonium sulfate crystallization section, the ammonium bicarbonate crystallization section, the sodium sulfate impurity removal section, and the soda ash calcination section are all commonly known in the prior art.

[0039] Following the above technical solution, the following are specific embodiments of this utility model. It should be noted that this utility model is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solution of this application fall within the protection scope of this utility model.

[0040] Example: This embodiment provides an apparatus for the coupled production of soda ash based on ammonia-based carbon capture and sodium sulfate waste salt, such as... Figure 1 As shown, it includes a soda ash preparation section 2, which includes a sodium sulfate removal section 207. The sodium sulfate removal section 207 includes a sodium sulfate wastewater removal tank 201, which is connected to a sodium sulfate solution storage tank 202. The sodium sulfate solution storage tank 202 is connected to the tube-side feed inlet of the heat exchanger 3.

[0041] like Figure 1As shown, it also includes an ammonia-based carbon capture section 1, which includes a carbon capture tower 101. The lower side wall of the carbon capture tower 101 is provided with a carbon capture tower flue gas inlet 10101. The lower side wall of the carbon capture tower 101 is connected to a concentrated ammonia water storage tank 106 through an ammonia water circulation pipe 105. The upper side wall of the carbon capture tower 101 is provided with multiple ammonia water spray inlets 10103. The concentrated ammonia water storage tank 106 is connected to the multiple ammonia water spray inlets 10103 through a circulation pump to spray ammonia water into the carbon capture tower 101. The carbon capture tower 101 is connected to the concentrated ammonia water storage tank 106 through the ammonia water circulation pipe 105 for circulating washing to generate ammonium bicarbonate.

[0042] like Figure 1 As shown, the lower wall of the carbon capture tower 101 is provided with an ammonium bicarbonate outlet 10102. The ammonium bicarbonate outlet 10102 is connected to the ammonium bicarbonate crystallization tank 103 in the ammonium bicarbonate crystallization section 116 through the ammonium bicarbonate enrichment liquid pipeline 102. The ammonium bicarbonate outlet 10102 of the carbon capture tower 101 is connected to the ammonium bicarbonate crystallization tank 103 through the ammonium bicarbonate enrichment liquid pipeline 102. The ammonium bicarbonate crystallization tank 103 is connected to the ammonium bicarbonate solution storage tank 104. The ammonium bicarbonate solution storage tank 104 is connected to the tube-side feed inlet of the heat exchanger 3.

[0043] like Figure 1 As shown, the tube side outlet of heat exchanger 3 is connected to reactor 203, and ammonium bicarbonate solution and sodium sulfate solution are fed into reactor 203 to prepare soda ash.

[0044] As a preferred embodiment of this invention, such as Figure 1 As shown, the soda ash outlet of the reactor 203 is connected to the soda ash calcining furnace 204 in the soda ash calcining section 208, and the product output end of the soda ash calcining furnace 204 is connected to the sodium carbonate product pipeline 206.

[0045] As a preferred embodiment of this invention, such as Figure 1 As shown, the gas output end of the soda ash calcining furnace 204 is connected to the shell-side input end of the heat exchanger 3, and the shell-side output end of the heat exchanger 3 is connected to the carbon capture tower 101.

[0046] As a preferred embodiment of this invention, such as Figure 1 As shown, the upper wall of the carbon capture tower 101 is provided with a carbon capture tower flue gas outlet 10104. The carbon capture tower flue gas outlet 10104 is connected to the ammonia escape control tower 109 through a flue gas pipe 108. A liquid collector 110 is provided in the middle of the ammonia escape control tower 109. The liquid collector 110 divides the interior of the ammonia escape control tower 109 into a lower water washing deammoniation zone 10901 and an upper acid washing deammoniation zone 10902.

[0047] As a preferred embodiment of this invention, such as Figure 1As shown, the lower side wall of the lower water washing and ammonia removal zone 10901 is provided with an ammonia escape control tower flue gas inlet 10903, and the flue gas pipe 108 is connected to the ammonia escape control tower flue gas inlet 10903.

[0048] As a preferred embodiment of this invention, such as Figure 1 As shown, the lower side wall of the lower water washing and ammonia removal zone 10901 is connected to the water storage tank 112 through a water circulation pipe 111. The upper side wall of the lower water washing and ammonia removal zone 10901 is provided with a water washing liquid spray inlet 10904. The water storage tank 112 is connected to the water washing liquid spray inlet 10904 through a circulation pump to spray fresh water into the lower water washing and ammonia removal zone 10901. The lower water washing and ammonia removal zone 10901 is connected to the water storage tank 112 through the water circulation pipe 111 for circulating washing. The water storage tank 112 is provided with a water inlet 113.

[0049] As a preferred embodiment of this invention, such as Figure 1 As shown, the upper wall of the upper pickling and ammonia removal zone 10902 is equipped with an ammonia escape control tower flue gas outlet 10905.

[0050] As a preferred embodiment of this invention, such as Figure 1 As shown, the lower sidewall of the upper pickling and deammoniation zone 10902 is connected to the ammonium sulfate solution storage tank 115 via an ammonium sulfate circulation pipe 114. The upper sidewall of the upper pickling and deammoniation zone 10902 is provided with an ammonium sulfate washing liquid spray inlet 10906. The ammonium sulfate solution storage tank 115 is connected to the ammonium sulfate washing liquid spray inlet 10906 via a circulation pump to spray the ammonium sulfate solution into the upper pickling and deammoniation zone 10902. The upper pickling and deammoniation zone 10902 is connected to the ammonium sulfate solution storage tank 115 via the ammonium sulfate circulation pipe 114 for circulating washing.

[0051] As a preferred embodiment of this invention, such as Figure 1 As shown, the ammonia and ammonium bicarbonate output ends of the ammonium sulfate solution storage tank 115 are connected to the ammonia stripping tower 4, and the residual mother liquor output end of the reactor 203 is also connected to the ammonia stripping tower 4.

[0052] As a preferred embodiment of this invention, such as Figure 1 As shown, the gas output end of the ammonia stripping tower 4 is connected to the shell-side input end of the heat exchanger 3, and the ammonium sulfate output end of the ammonia stripping tower 4 is connected to the ammonium sulfate crystallization tank 5 in the ammonium sulfate crystallization section 7.

[0053] As a preferred embodiment of this invention, such as Figure 1 As shown, the ammonium sulfate output end of the ammonium sulfate crystallizer 5 is connected to the ammonium sulfate pipeline, the ammonium sulfate output end of the ammonium sulfate crystallizer 5 is also connected to the ammonium sulfate solution storage tank 115, and the sodium sulfate output end of the ammonium sulfate crystallizer 5 is connected to the sodium sulfate solution storage tank 202.

[0054] As a preferred embodiment of this invention, such as Figure 1 As shown, a stirrer 205 is installed inside the reaction vessel 203.

[0055] As a preferred embodiment of this invention, such as Figure 1 As shown, the concentrated ammonia storage tank 106 is equipped with a concentrated ammonia inlet 107.

[0056] The process flow of the device for preparing soda ash based on the coupling of carbon capture by ammonia method and sodium sulfate waste salt in this embodiment is as follows: Ammonia-based carbon capture section 1: CO2-containing industrial flue gas enters the carbon capture tower 101 through the flue gas inlet 10101. Simultaneously, fresh concentrated ammonia water is injected into the concentrated ammonia water storage tank 106 through the concentrated ammonia water inlet 107. The fresh concentrated ammonia water in the concentrated ammonia water storage tank 106 is sprayed into the carbon capture tower 101 through multiple ammonia water spray inlets 10103 on the carbon capture tower 101 via a circulation pump. Unconsumed concentrated ammonia water in the carbon capture tower 101 is circulated through the ammonia water circulation pipe 105. The gas then enters the concentrated ammonia water storage tank 106 for circulating washing to generate ammonium bicarbonate. The CO2 in the industrial flue gas reacts with the concentrated ammonia water to generate ammonium bicarbonate enriched solution at the bottom of the carbon capture tower 101 (the bottom of the tower is equipped with a stirring device to prevent premature crystallization). After the ammonium bicarbonate at the bottom of the carbon capture tower 101 is enriched to a certain extent, it is sent to the ammonium bicarbonate crystallization section 116 to prepare ammonium bicarbonate products, which can be sold externally or used as raw materials to prepare solutions and then stored in the ammonium bicarbonate solution storage tank 104.

[0057] After decarbonization, the industrial flue gas is discharged from the carbon capture tower flue gas outlet 10104 of the carbon capture tower 101, and enters the lower water washing deammoniation zone 10901 of the ammonia escape control tower 109 through the ammonia escape control tower flue gas inlet 10905 for water washing. Subsequently, the industrial flue gas enters the upper acid washing deammoniation zone 10902 through the liquid collector 110 for acid washing, and is discharged from the ammonia escape control tower flue gas outlet 10905 at the top of the upper acid washing deammoniation zone 10902 of the ammonia escape control tower 109. When the sulfuric acid in the ammonium sulfate solution storage tank 115... After the ammonia and ammonium bicarbonate (residual in the flue gas during the initial carbon capture) in the ammonium circulating solution are enriched to a certain extent (when the solution pH exceeds 6.5), they are discharged from the ammonium sulfate solution storage tank 115 to the ammonia stripping tower 4. The evaporation temperature of the ammonia stripping tower 4 is 80℃~105℃. The ammonia stripping tower 4 is connected to the heat exchanger 3. The CO2, NH3 and water vapor generated by the ammonia stripping tower 4 are cooled to 25℃~35℃ in the heat exchanger 3 and then fed into the carbon capture tower 101 for recycling. At the same time, the ammonium sulfate solution in the ammonia stripping tower 4 is transported to the ammonium sulfate crystallization section 7 for regeneration or sale.

[0058] In this embodiment, ammonium sulfate is preferably used as a circulating pickling agent in the ammonium sulfate solution storage tank 115 (the pH value of the pickling agent needs to be maintained at 4.5-6.0).

[0059] Soda ash preparation section 2: Wastewater or waste salt containing sodium sulfate is purified by passing it through sodium sulfate purification section 207, and then the solution is prepared and stored in sodium sulfate solution storage tank 202.

[0060] In this embodiment, the impurities in the sodium sulfate crystals entering the metathesis process are ensured to be within the allowable limits, as detailed in Table 1. A small amount of unremoved impurities (such as trace amounts of COD) enter the subsequent process stages. When the impurities in the circulating mother liquor accumulate to a certain level (COD > 50 mg / L) and affect product quality, the mother liquor with excessive impurities is transported to the sodium sulfate impurity removal section 207 for impurity removal before being returned to the system for continued production.

[0061] Table 1. Composition requirements of sodium sulfate waste salt after impurity removal

[0062] The ammonium bicarbonate solution in storage tank 104 and the sodium sulfate solution in storage tank 202 are mixed in a molar ratio of [NH4] to [NH4]. + ]:[Na + The mixture of ammonium bicarbonate and sodium sulfate at a ratio of 1 to 1.2 is introduced into heat exchanger 3 for mixing. The mixture is then heated to 35°C–40°C via heat exchanger 3 before being introduced into reactor 203. Simultaneously, a promoter is added to reactor 203 at a molar ratio of (0.7–2):1 to sulfate ions. The pH of the metathesis reaction in reactor 203 is controlled between 8.0 and 8.4, the reaction time between 30 and 60 minutes, and the stirring speed between 40 and 60 r / min. The reaction is carried out under the following conditions: sodium bicarbonate product precipitates at the bottom of reactor 203 and is periodically discharged to soda ash calcination section 208 for calcination (calcination temperature is 200℃~270℃). Soda ash product is produced and sold. At the same time, the high-temperature mixture of CO2 and water vapor generated in soda ash calcination section 208 is cooled by heat exchanger 3 (cooled to between 25℃ and 35℃, and cooling equipment can be added to assist in cooling) and then passed into carbon capture tower 101 to form ammonium bicarbonate solution, realizing the recycling of CO2.

[0063] In this embodiment, the accelerator is a single or mixture of multiple substances such as ammonium nitrate, sodium nitrate, or sodium formate, which are known in the art.

[0064] The remaining mother liquor after the metathesis reaction is discharged from the reactor 203 into the ammonia stripping tower 4. The evaporation temperature of the ammonia stripping tower 4 is 80℃~105℃. Under the hot steam of 80℃~105℃, the heat exchanger 3 provides auxiliary heating (the insufficient part is supplemented by low temperature steam) to release ammonia from the remaining mother liquor. At the same time, CO2 and water vapor are also generated. The high-temperature mixed gas of NH3, CO2 and water vapor generated by the ammonia stripping tower 4 is cooled by the heat exchanger 3 (cooled to 25℃~35℃, and cooling equipment can be added to assist in cooling) and then passed into the carbon capture tower 101 to react and form ammonium bicarbonate solution, realizing the recycling of NH3 and CO2.

[0065] The remaining mother liquor in the ammonia stripping tower 4 is discharged into the ammonium sulfate crystallization section 7, where residual sodium sulfate raw material and ammonium sulfate product are precipitated through high-temperature evaporation (80℃~105℃). The sodium sulfate is discharged into the sodium sulfate solution storage tank 202 for recycling. Most of the ammonium sulfate product is packaged and stored for sale, while a small portion is discharged into the ammonium sulfate solution storage tank 115 for recycling as an acid washing agent in the ammonia escape control process of the ammonia carbon capture method.

[0066] In this embodiment, the reaction principle for preparing soda ash and fertilizer ammonium sulfate by metathesis reaction using sodium sulfate and ammonium bicarbonate as raw materials is as follows: Its core double decomposition reaction equation (endothermic) is: .

[0067] 2Na at 25℃ + 2NH4 + / / SO4 2- 2HCO3 - —The quaternary phase diagram of H2O is as follows Figure 2 As shown, in the above 4-salt quaternary water-salt system, sodium bicarbonate (baking soda) has the lowest solubility (and the largest crystallization region in phase diagram analysis), so it is the easiest to precipitate from the solution in crystal form, which is the thermodynamic basis for driving the reaction equation to the right-hand side.

[0068] In this embodiment, sodium sulfate and ammonium bicarbonate are used as raw materials to prepare soda ash and fertilizer ammonium sulfate through a metathesis reaction. The reaction parameters affecting these parameters are as follows: (1) Temperature When the temperature is too high, ammonium bicarbonate raw material is prone to decomposition and release NH3 and CO2, reducing the yield of sodium bicarbonate (Na). + (Utilization rate); when the temperature is too low, Na2SO4•10H2O (sodium sulfate) hydrate will precipitate and mix into the sodium bicarbonate product, thus reducing the sodium bicarbonate yield. + (Utilization rate), therefore, the optimal reaction temperature is 35℃~40℃.

[0069] (2) pH value When the solution is too acidic, CO2 gas will be released, leading to a decrease in the yield of sodium bicarbonate (Na). + The utilization rate decreased, and the principle behind it is as follows: .

[0070] When the solution is too alkaline, the precipitated sodium bicarbonate will redissolve, resulting in a decrease in the sodium bicarbonate yield (Na). + The utilization rate decreased, and the principle behind it is as follows: .

[0071] Therefore, the optimal reaction pH is between 8.0 and 8.4.

[0072] (3) Time If the material residence time is too short, the crystal nuclei will not grow to the expected particle size before being sent out, resulting in a product with a smaller particle size. Many small crystals will agglomerate to form crystal clusters, which can easily encapsulate and trap the reaction liquid, causing residual reaction liquid in the sodium bicarbonate product. The residual mother liquor on the surface of sodium bicarbonate can be removed by washing, but the sodium sulfate trapped in the crystals cannot be washed away, thus affecting the quality of soda ash. If the material residence time is too long, it will cause energy consumption and time waste. Therefore, the optimal reaction time is 30 min to 60 min.

[0073] (4) Stirring speed The stirring speed of reactor 203 has a great influence on the crystallization process of sodium bicarbonate. If the speed is too slow, it is difficult to mix the raw materials thoroughly. If the speed is too fast, the sodium bicarbonate crystal nuclei will collide excessively and be difficult to grow. Therefore, the optimal stirring speed is 40-60 r / min.

Claims

1. An apparatus for preparing soda ash based on carbon capture and sodium sulfate waste salt coupling of ammonia method, comprising a soda ash preparation section (2), wherein the soda ash preparation section (2) includes a sodium sulfate impurity removal section (207), the sodium sulfate impurity removal section (207) includes a sodium sulfate wastewater impurity removal tank (201), the sodium sulfate wastewater impurity removal tank (201) is connected to a sodium sulfate solution storage tank (202), and the sodium sulfate solution storage tank (202) is connected to the tube side inlet of a heat exchanger (3); Its features are: It also includes an ammonia-based carbon capture section (1), which includes a carbon capture tower (101). The lower side wall of the carbon capture tower (101) is provided with a carbon capture tower flue gas inlet (10101). The lower side wall of the carbon capture tower (101) is connected to a concentrated ammonia water storage tank (106) through an ammonia water circulation pipe (105). The upper side wall of the carbon capture tower (101) is provided with multiple ammonia water spray inlets (10103). The concentrated ammonia water storage tank (106) is connected to multiple ammonia water spray inlets (10103) through a circulation pump to spray ammonia water into the carbon capture tower (101). The carbon capture tower (101) is connected to the concentrated ammonia water storage tank (106) through an ammonia water circulation pipe (105) for circulating washing to generate ammonium bicarbonate. The lower wall of the carbon capture tower (101) is provided with an ammonium bicarbonate outlet (10102). The ammonium bicarbonate outlet (10102) is connected to the ammonium bicarbonate crystallization tank (103) in the ammonium bicarbonate crystallization section (116) through the ammonium bicarbonate enrichment liquid pipeline (102). The ammonium bicarbonate crystallization tank (103) is connected to the ammonium bicarbonate solution storage tank (104). The ammonium bicarbonate solution storage tank (104) is connected to the tube side inlet of the heat exchanger (3). The tube outlet of the heat exchanger (3) is connected to the reactor (203) to feed ammonium bicarbonate solution and sodium sulfate solution into the reactor (203) to prepare soda ash.

2. The apparatus for preparing soda ash based on the ammonia method of carbon capture and sodium sulfate waste salt coupling as described in claim 1, characterized in that, The soda ash outlet of the reactor (203) is connected to the soda ash calcining furnace (204) in the soda ash calcining section (208), and the product output end of the soda ash calcining furnace (204) is connected to the sodium carbonate product pipeline (206).

3. The apparatus for preparing soda ash based on the ammonia method of carbon capture and sodium sulfate waste salt coupling as described in claim 2, characterized in that, The gas output end of the soda ash calcining furnace (204) is connected to the shell-side input end of the heat exchanger (3), and the shell-side output end of the heat exchanger (3) is connected to the carbon capture tower (101).

4. The apparatus for preparing soda ash based on the ammonia-based carbon capture and sodium sulfate waste salt coupling method as described in claim 1, characterized in that, The carbon capture tower (101) is provided with a carbon capture tower flue gas outlet (10104) on its upper wall. The carbon capture tower flue gas outlet (10104) is connected to the ammonia escape control tower (109) through a flue gas pipe (108). A liquid collector (110) is provided in the middle of the ammonia escape control tower (109). The liquid collector (110) divides the interior of the ammonia escape control tower (109) into a lower water washing deammoniation zone (10901) and an upper acid washing deammoniation zone (10902).

5. The apparatus for preparing soda ash based on the ammonia method of carbon capture and sodium sulfate waste salt coupling as described in claim 4, characterized in that, The lower side wall of the lower water washing and ammonia removal zone (10901) is provided with an ammonia escape control tower flue gas inlet (10903), and the flue gas pipe (108) is connected to the ammonia escape control tower flue gas inlet (10903); The lower sidewall of the lower water washing and ammonia removal zone (10901) is connected to the water storage tank (112) through a water circulation pipe (111). The upper sidewall of the lower water washing and ammonia removal zone (10901) is provided with a water washing liquid spray inlet (10904). The water storage tank (112) is connected to the water washing liquid spray inlet (10904) through a circulation pump to spray fresh water into the lower water washing and ammonia removal zone (10901). The lower water washing and ammonia removal zone (10901) is connected to the water storage tank (112) through a water circulation pipe (111) for circulating washing. The water storage tank (112) is provided with a water inlet (113).

6. The apparatus for preparing soda ash by coupling carbon capture and sodium sulfate waste salt based on the ammonia method as described in claim 4, characterized in that, The upper wall of the upper acid washing and ammonia removal zone (10902) is provided with an ammonia escape control tower flue gas outlet (10905). The lower sidewall of the upper acid washing and deammoniation zone (10902) is connected to the ammonium sulfate solution storage tank (115) through an ammonium sulfate circulation pipe (114). An ammonium sulfate washing liquid spray inlet (10906) is provided on the upper sidewall of the upper acid washing and deammoniation zone (10902). The ammonium sulfate solution storage tank (115) is connected to the ammonium sulfate washing liquid spray inlet (10906) through a circulation pump to spray the ammonium sulfate solution into the upper acid washing and deammoniation zone (10902). The upper acid washing and deammoniation zone (10902) is connected to the ammonium sulfate solution storage tank (115) through the ammonium sulfate circulation pipe (114) for circulating washing.

7. The apparatus for preparing soda ash based on the ammonia-based carbon capture and sodium sulfate waste salt coupling method as described in claim 6, characterized in that, The ammonia and ammonium bicarbonate output ends of the ammonium sulfate solution storage tank (115) are connected to the ammonia stripping tower (4), and the residual mother liquor output end of the reactor (203) is also connected to the ammonia stripping tower (4). The gas output end of the ammonia stripping tower (4) is also connected to the shell-side input end of the heat exchanger (3), and the ammonium sulfate output end of the ammonia stripping tower (4) is connected to the ammonium sulfate crystallization tank (5) in the ammonium sulfate crystallization section (7).

8. The apparatus for preparing soda ash based on the ammonia method of carbon capture and sodium sulfate waste salt coupling as described in claim 7, characterized in that, The ammonium sulfate output end of the ammonium sulfate crystallizer (5) is connected to the ammonium sulfate pipeline. The ammonium sulfate output end of the ammonium sulfate crystallizer (5) is also connected to the ammonium sulfate solution storage tank (115). The sodium sulfate output end of the ammonium sulfate crystallizer (5) is connected to the sodium sulfate solution storage tank (202).

9. The apparatus for preparing soda ash based on the ammonia method of carbon capture and sodium sulfate waste salt coupling as described in claim 1, characterized in that, The reactor (203) is equipped with a stirrer (205).

10. The apparatus for preparing soda ash based on the ammonia-based carbon capture and sodium sulfate waste salt coupling method as described in claim 1, characterized in that, The concentrated ammonia storage tank (106) is equipped with a concentrated ammonia inlet (107).

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