Continuous reaction device and method for preparing sodium carbonate from sodium sulfate

Abstract

The invention discloses a continuous reaction device and method for preparing sodium carbonate from sodium sulfate, and aims to overcome the defects that in the process of preparing sodium carbonate from sodium sulfate, residual mother liquor still contains unreacted ammonium bicarbonate, a large number of unreacted ammonium radicals and bicarbonate radicals are wasted, and the utilization rate of raw materials is low. The device comprises a reaction tank and a calcining furnace, a solid-liquid separation unit is arranged between the reaction tank and the calcining furnace, the calcining furnace is connected with a gas storage tank through a recovery pipe, and an exhaust pipe is connected between the reaction tank and the gas storage tank; the solid-liquid separation unit comprises a solid collecting tank and a filter screen, solid products after reaction in the reaction tank are collected in the solid collecting tank, and liquid discharged from the reaction tank flows into the calcining furnace through the filter screen. According to the technical scheme provided by the invention, incompletely reacted components in the raw material liquid can be effectively utilized to realize continuous reaction.

Description

Technical Field

[0001] The invention relates to the field of chemical engineering, and more specifically to a continuous reaction device and method for preparing sodium carbonate from sodium sulfate. Background Art

[0002] As a basic chemical raw material, sodium sulfate is mainly sourced from the following sources: first, it is the mineral sodium sulfate, second, it is produced as a by-product in the chemical reaction process, and third, it is high-salt wastewater. These industrial by-product sodium sulfates are difficult to be recycled, and long-term storage will lead to land salinization and water acidification, posing a threat to the environment and human health. Therefore, in order to solve the problem of sodium sulfate resource utilization, promoting its conversion into high-value-added products has become an important problem that the environmental protection industry urgently needs to solve. Among them, sodium carbonate is one of the main products of high-value conversion of sodium sulfate.

[0003] Sodium carbonate is an important inorganic chemical raw material, widely used in building materials, food processing, petrochemical and other fields. In the process of preparing sodium carbonate, due to the precipitation of crystals in the solution, it is very easy to adhere to the wall of the reactor, causing problems such as difficulty in cleaning, collection and separation from the mother liquor. In the separation device invented by patent CN210434083U, the alkali solution flows to the liquid distribution cone cover in the guide hopper and is evenly distributed on the filter cone to achieve the purpose of solid-liquid separation. Patent CN117582718A uses the inner wall extrusion of the barrel body and the filter screen to achieve the effect of separating the product from the mother liquor. However, these two devices do not effectively utilize the unreacted components in the raw material liquid during the working process, and cannot realize the continuous reaction process of sodium carbonate preparation and solid-liquid separation. After the sodium sulfate and ammonium bicarbonate solution are subjected to double decomposition reaction, the remaining mother liquor still contains unreacted ammonium bicarbonate, which wastes a large amount of unreacted ammonium and bicarbonate, and the raw material utilization rate is low. Summary of the invention

[0004] In order to overcome the above-mentioned shortcomings, the present invention provides a continuous reaction device and method for preparing sodium carbonate from sodium sulfate, which can achieve two invention purposes: first, effectively utilizing the components that have not been completely reacted in the raw material liquid to achieve continuous reaction; second, the crystallized product is not easy to adhere to the bottom of the reaction tank, and is convenient to clean and collect.

[0005] In order to solve the above technical problems, the present invention adopts the following technical scheme: a continuous reaction device for preparing sodium carbonate from sodium sulfate, comprising a reaction tank and a calcining furnace, a solid-liquid separation unit is arranged between the reaction tank and the calcining furnace, the calcining furnace is connected to a gas storage tank through a recovery pipe, and an exhaust pipe is connected between the reaction tank and the gas storage tank; the solid-liquid separation unit comprises a solid collecting tank and a filter screen, the solid product after the reaction in the reaction tank is collected in the solid collecting tank, and the liquid discharged from the reaction tank flows into the calcining furnace through the filter screen.

[0006] In the process of preparing sodium carbonate, solid raw materials sodium sulfate and ammonium bicarbonate powder are added to the reaction tank, and water is added. Sodium sulfate and ammonium bicarbonate undergo double decomposition reaction to generate sodium bicarbonate and ammonium sulfate. The solubility of ammonium sulfate in water is much greater than that of sodium bicarbonate in water, so ammonium sulfate dissolves in water and flows into the calciner through the filter with the water. The sodium bicarbonate crystals are blocked by the filter and collected in the solid collection tank. Solid-liquid separation is achieved through the solid-liquid separation unit. The mixed liquid in the calciner is heated, and the incompletely reacted ammonium bicarbonate is decomposed. The generated ammonia and carbon dioxide are collected in the gas storage tank through the recovery pipe and stored, and sent to the reaction tank through the exhaust pipe to achieve continuous reaction.

[0007] After the calcining furnace is heated, the crystallized ammonium sulfate is collected and the calcining furnace is cleaned. After that, the filter screen is moved to make the sodium bicarbonate crystals in the solid collection tank fall into the calcining furnace. The calcining furnace is heated to calcine the sodium bicarbonate to obtain the sodium carbonate product. The carbon dioxide generated in the process is collected through the recovery pipe and stored in the gas storage tank.

[0008] The technical solution of the present application can effectively utilize the components in the raw material liquid that have not been completely reacted to achieve continuous reaction.

[0009] Preferably, a rotatable scraper is installed in the reaction tank, and a plurality of scraper heads are arranged at intervals on the scraper, and the scraper heads are close to the bottom of the reaction tank.

[0010] During the reaction of sodium sulfate and ammonium bicarbonate in the reaction tank, the scraper rotates, and the scraper and the scraper head stir the mixture together to fully mix the two and improve the reaction effect. In addition, the scraper head is close to the bottom of the reaction tank, and the bottom of the reaction tank is cleaned without dead angles, and the crystals at the bottom of the reaction tank are cleaned, which is convenient for collecting the crystals into the solid collection tank to avoid long-term accumulation of products at the bottom.

[0011] Preferably, a plurality of scrapers are arranged at circumferential intervals, and the scraper heads installed on different scrapers are radially staggered.

[0012] The provision of multiple scrapers is beneficial to improving the stirring effect. The scraper heads on different scrapers are staggered so that every position on the bottom of the reaction tank can be scraped, thereby achieving a clean bottom of the reaction tank without dead angles.

[0013] Preferably, the bottom of the reaction tank is in a conical structure that is larger at the top and smaller at the bottom, and the solid collection tank is connected to the lowest point of the bottom of the reaction tank.

[0014] The bottom of the reaction tank is in a conical structure, which is conducive to the crystals falling into the solid collection tank.

[0015] Preferably, the calcining furnace is connected to a vacuum pump via a pipeline.

[0016] When performing solid-liquid separation, the calcining furnace is evacuated by a vacuum pump to generate negative pressure in the calcining furnace, which is conducive to the mixed liquid in the reaction tank to flow quickly into the calcining furnace.

[0017] Preferably, an air suction pump is provided on the gas storage tank, and the air suction pump extracts the gas in the calcining furnace and stores it in the gas storage tank.

[0018] The suction pump generates suction to collect the ammonia and carbon dioxide generated in the calcining furnace through the recovery pipe and store them in the gas storage tank.

[0019] Preferably, an air source dryer is installed on the recovery pipe.

[0020] The gas source dryer can absorb the water vapor in the mixed gas to prevent the water from flowing into the gas storage tank and reacting with ammonia and carbon dioxide to produce ammonium bicarbonate.

[0021] Preferably, an air inlet valve is installed on the recovery pipe, an exhaust valve is installed on the exhaust pipe, and an opening valve is installed between the solid-liquid separation unit and the calcining furnace.

[0022] The air inlet valve realizes the opening and shutoff of the return pipe, the exhaust valve realizes the opening and shutoff of the exhaust pipe, and the opening valve realizes the connection and shutoff between the solid-liquid separation unit and the calcining furnace.

[0023] Preferably, the filter is movably arranged, one end of the filter is connected to a preload spring, and the preload spring abuts against the filter to achieve positioning of the filter.

[0024] Under the action of the preloaded spring, the filter screen is blocked in the solid collection tank. When the crystals need to be sent to the calcining furnace, the filter screen is moved so that the filter screen and the solid collection tank are offset, and the crystals fall into the calcining furnace under the action of gravity.

[0025] A method for preparing sodium carbonate from sodium sulfate is carried out by using a continuous reaction device for preparing sodium carbonate from sodium sulfate, and the method comprises the following steps: S1, adding sodium sulfate, ammonium bicarbonate and water into a reaction tank, stirring the reaction tank, and scraping sodium bicarbonate crystals at the bottom of the reaction tank into a solid collection tank; S2, heating the liquid flowing from the reaction tank to a calcining furnace, collecting the obtained ammonia and carbon dioxide into a gas storage tank to be transported to the reaction tank for the next reaction; S3, cleaning the calcining furnace, moving a filter screen to make the sodium bicarbonate crystals in the solid collection tank fall into the calcining furnace; S4, heating the calcining furnace to calcine the sodium bicarbonate to obtain sodium carbonate.

[0026] Sodium sulfate and ammonium bicarbonate in the reaction tank undergo double decomposition reaction to generate sodium bicarbonate and ammonium sulfate. The solubility of ammonium sulfate in water is much greater than that of sodium bicarbonate in water, so ammonium sulfate dissolves in water and flows into the calciner through the filter with the water. The sodium bicarbonate crystals are blocked by the filter and collected in the solid collection tank. Solid-liquid separation is achieved through the solid-liquid separation unit. The mixed liquid in the calciner is heated, and the incompletely reacted ammonium bicarbonate is decomposed. The generated ammonia and carbon dioxide are collected in the gas storage tank through the recovery pipe and stored. In the next reaction, they are sent to the reaction tank through the exhaust pipe to achieve continuous reaction.

[0027] After the calcining furnace is heated, the crystallized ammonium sulfate is collected and the calcining furnace is cleaned. After that, the filter is moved to make the sodium bicarbonate crystals in the solid collection tank fall into the calcining furnace, and the calcining furnace is heated to calcine the sodium bicarbonate to obtain the sodium carbonate product. The carbon dioxide generated in this process is collected through the recovery pipe and stored in the gas storage tank.

[0028] Compared with the prior art, the present invention has the following beneficial effects: (1) the technical solution of the present application can effectively utilize the components in the raw material liquid that have not been completely reacted to achieve continuous reaction; (2) the crystallized product is not easy to adhere to the bottom of the reaction tank, and is easy to clean and collect; (3) the conical bottom of the reaction tank is linked with the scraper and the scraper head, and the synergistic effect of the vacuum pump can efficiently separate the crystallized product from the mother liquor. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the present invention.

[0030] Figure 2 The present invention Figure 1 Enlarged view of point A in the middle.

[0031] Figure 3 The present invention Figure 1 Enlarged view of point B in the middle.

[0032] Figure 4 It is a schematic diagram of the feed hopper installation of Example 2 of the present invention.

[0033] Figure 5 It is a schematic diagram of the feed hopper installation of Example 3 of the present invention.

[0034] In the figure: 1, reaction tank, 2, calcining furnace, 3, support column, 4, solid collection tank, 5, filter screen, 6, opening valve, 7, scraper, 8, scraper head, 9, drive motor, 10, rotating shaft, 11, paddle frame, 12, solid feed port, 13, liquid feed pipe, 14, liquid inlet valve, 15, feed hopper, 16, mixing barrel, 17, spiral conveyor bar, 18, mounting ring, 19, water storage ring groove, 20, water outlet pipe , 21. Water outlet, 22. Partition, 23. Air storage tank, 24. Exhaust pipe, 25. Inlet valve, 26. Exhaust valve, 27. Suction pump, 28. Air source dryer, 29. Preload spring, 30. Material passing pipeline, 31. Slide, 32. Slider, 33. End cover, 34. Push rod, 35. Avoidance groove, 36. Boss, 37. Maintenance door, 38. Air pump, 39. Air exhaust valve, 40. Blade. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings: Example 1: A continuous reaction device for preparing sodium carbonate from sodium sulfate (see Figure 1 , Figure 2 , Figure 3 ), including a reaction tank 1 and a calcining furnace 2, the calcining furnace 2 is placed below the reaction tank 1, and a plurality of support columns 3 are connected between the calcining furnace 2 and the reaction tank 1. A solid-liquid separation unit is arranged between the reaction tank 1 and the calcining furnace 2, and the solid-liquid separation unit includes a solid collecting tank 4 and a filter screen 5. The solid product after the reaction in the reaction tank 1 is collected in the solid collecting tank 4, and the liquid discharged from the reaction tank 1 flows into the calcining furnace 2 through the filter screen 5. An opening valve 6 is installed between the solid-liquid separation unit and the calcining furnace 2.

[0036] The bottom of the reaction tank 1 is a conical structure with a large top and a small bottom, and the solid collecting tank 4 is connected to the lowest point of the bottom of the reaction tank 1. A rotatable scraper 7 is installed in the reaction tank 1, and the scraper 7 is arranged close to the bottom of the reaction tank 1. A plurality of scraper heads 8 are arranged at intervals on the scraper 7, and the scraper heads 8 are close to the bottom of the reaction tank 1, and the ends of the scraper heads 8 are in an isosceles trapezoidal structure. Multiple scrapers 7 are arranged at intervals in the circumferential direction, and the scrapers 7 are arranged upwardly tilted away from the center of the reaction tank 1, and the scraper heads 8 installed on different scrapers 7 are radially staggered. Arranging multiple scrapers 7 is conducive to improving the stirring effect. The scraper heads 8 on different scrapers 7 are staggered, so that every position of the bottom of the reaction tank 1 can be scraped, thereby achieving a clean bottom of the reaction tank 1 without dead angles, and the staggered scraper heads 8 can reduce the resistance in the liquid.

[0037] A driving motor 9 is installed at the upper end of the reaction tank 1, and the output shaft of the driving motor 9 is connected to the rotating shaft 10. The scraper 7 is fastened to the rotating shaft 10, and a paddle frame 11 is installed on the rotating shaft 10. The paddle frame 11 is placed in the reaction tank 1. A solid feed port 12 is arranged at the upper end of the reaction tank 1, and a liquid feed pipe 13 is installed on the side wall of the reaction tank 1. The liquid feed pipe is arranged close to the upper part of the reaction tank 1, and a liquid feed valve 14 is installed on the liquid feed pipe 13.

[0038] The calcining furnace 2 is connected to the gas storage tank 23 through a recovery pipe, and an exhaust pipe 24 is connected between the reaction tank 1 and the gas storage tank 23; an air intake valve 25 is installed on the recovery pipe, and an exhaust valve 26 is installed on the exhaust pipe 24. An air suction pump 27 is provided on the gas storage tank 23, and the air suction pump 27 extracts the gas in the calcining furnace 2 and stores it in the gas storage tank 23. A gas source dryer 28 is installed on the recovery pipe, and the gas source dryer 28 can absorb the water vapor in the mixed gas to prevent the water from flowing into the gas storage tank 23 to react with ammonia and carbon dioxide to generate ammonium bicarbonate.

[0039] The filter screen 5 is arranged to be movable, and one end of the filter screen 5 is connected to a preload spring 29, which abuts against the filter screen 5 to realize the positioning of the filter screen 5. A material-passing pipeline 30 is connected between the reaction tank 1 and the calcining furnace 2, and the filter screen 5 is installed in the material-passing pipeline 30. The internal cavity of the material-passing pipeline 30 above the filter screen 5 forms a solid collection tank 4. An opening valve 6 is installed on the material-passing pipeline 30, and the opening valve 6 is placed below the filter screen 5. A slideway 31 corresponding to the filter screen 5 is arranged on the outer wall of the material-passing pipeline 30, and a slider 32 is arranged at one end of the filter screen 5. The slider 32 is slidably connected to the slideway 31, and the slider 32 slides along the slideway 31. The end of the slideway 31 is connected to the end cover 33, and the preload spring 29 abuts between the end cover 33 and the slider 32. A lever 34 extending outward is arranged on the slider 32, and a long strip-shaped avoidance groove 35 is arranged on the slideway 31, and the lever 34 extends out of the avoidance groove 35. A boss 36 is provided at the outer end of the slider 32, and the boss 36 is fixed on the outer wall of the material passage pipe 30, and a sealing ring is provided between the boss 36 and the outer wall of the material passage pipe 30. A maintenance window is provided on the side wall of the material passage pipe 30, and the maintenance window is provided corresponding to the filter screen 5, and a maintenance door 37 is installed at the maintenance window to facilitate the maintenance and replacement of the filter screen 5.

[0040] The upper part of the calcining furnace 2 is connected to a vacuum pump 38 through a pipeline, and a vacuum valve 39 is installed on the pipeline between the vacuum pump 38 and the calcining furnace 2. When performing solid-liquid separation, the calcining furnace 2 is evacuated by the vacuum pump 38 to generate negative pressure in the calcining furnace 2, which is conducive to the mixed liquid in the reaction tank 1 to quickly flow into the calcining furnace 2, thereby improving the solid-liquid separation effect.

[0041] A method for preparing sodium carbonate from sodium sulfate is carried out by using a continuous reaction device for preparing sodium carbonate from sodium sulfate, comprising the following steps: S1, a liquid inlet valve 14 is opened, sodium sulfate, ammonium bicarbonate and water are added into a reaction tank 1 for reaction, the temperature in the reaction tank 1 is controlled at about 60°C, a driving motor 9 is started to drive a rotating shaft 10 to rotate, and a paddle frame 11 installed on the rotating shaft 10 stirs the reaction tank 1; at the same time, a scraper 7 and a scraper head 8 rotate together with the rotating shaft 10 to make sodium sulfate and ammonium bicarbonate fully mixed and reacted, and sodium bicarbonate crystals generated after the reaction at the bottom of the reaction tank 1 are scraped into a solid collection tank 4.

[0042] S2, solid-liquid separation is performed, the opening valve 6 and the air extraction valve 39 are opened, and the air extraction pump 38 is started to generate negative pressure in the calcining furnace 2, and the mixed liquid in the reaction tank 1 flows into the calcining furnace 2 after passing through the filter screen 5, and the sodium bicarbonate crystals generated after the reaction are blocked by the filter screen 5 and remain in the solid collection tank 4. After the solid-liquid separation is completed, the air extraction valve 39 and the opening valve 6 are closed. Then the air inlet valve 25 and the air suction pump 27 are opened to heat the liquid flowing from the reaction tank 1 to the calcining furnace 2, and the temperature of the calcining furnace 2 is controlled between 30°C and 60°C. The obtained ammonia and carbon dioxide are collected in the gas storage tank 23 and transported to the reaction tank 1 for the next reaction; the gas source dryer 28 installed on the recovery pipe can absorb the water vapor in the mixed gas to prevent the water from being sucked into the gas storage tank 23.

[0043] S3, cleaning the calcining furnace 2, collecting and cleaning the ammonium sulfate crystallized after the calcination of S2. Turn off the suction pump 27 and the air inlet valve 25, open the start valve, pull the slider 32 outward to move the filter 5 so that the sodium bicarbonate crystals in the solid collection tank 4 fall into the calcining furnace 2.

[0044] S4, heating the calcining furnace 2, controlling the temperature in the calcining furnace 2 between 50°C and 200°C, calcining the sodium bicarbonate to obtain a sodium carbonate product. The carbon dioxide generated in the process is collected through a recovery pipe and stored in a gas storage tank 23.

[0045] Sodium sulfate and ammonium bicarbonate in the reaction tank 1 undergo double decomposition reaction to generate sodium bicarbonate and ammonium sulfate. The solubility of ammonium sulfate in water is much greater than that of sodium bicarbonate in water, so ammonium sulfate dissolves in water and flows into the calcining furnace 2 through the filter screen 5 with the water flow. The sodium bicarbonate crystals are blocked by the filter screen 5 and collected in the solid collection tank 4. Solid-liquid separation is achieved by the solid-liquid separation unit. The mixed liquid in the calcining furnace 2 is heated, and the incompletely reacted ammonium bicarbonate is decomposed. The generated ammonia and carbon dioxide are collected in the gas storage tank 23 through the recovery pipe for storage, and are sent to the reaction tank 1 through the exhaust pipe 24 during the next reaction to achieve continuous reaction. During the reaction of sodium sulfate and ammonium bicarbonate in the reaction tank 1, the scraper 7 rotates, and the scraper 7 and the scraper head 8 stir the mixture together to fully mix the two and improve the reaction effect. In addition, the scraper head 8 is close to the bottom of the reaction tank 1, and the bottom of the reaction tank 1 is cleaned without dead angles, and the crystals at the bottom of the reaction tank 1 are cleaned, so that the crystals are collected in the solid collection tank 4 to avoid long-term accumulation of the product at the bottom.

[0046] After the heating of the calcining furnace 2 is completed, the crystallized ammonium sulfate is collected and the calcining furnace 2 is cleaned. Afterwards, the filter screen 5 is moved to make the sodium bicarbonate crystals in the solid collection tank 4 fall into the calcining furnace 2, and the calcining furnace 2 is heated to calcine the sodium bicarbonate to obtain a sodium carbonate product. The carbon dioxide generated in the process is collected through a recovery pipe and stored in a gas storage tank 23.

[0047] Example 2: A continuous reaction device for preparing sodium carbonate from sodium sulfate (see Figure 1 , Figure 2 , Figure 3 ), including a reaction tank 1 and a calcining furnace 2, the calcining furnace 2 is placed below the reaction tank 1, and a plurality of support columns 3 are connected between the calcining furnace 2 and the reaction tank 1. A solid-liquid separation unit is arranged between the reaction tank 1 and the calcining furnace 2, and the solid-liquid separation unit includes a solid collecting tank 4 and a filter screen 5. The solid product after the reaction in the reaction tank 1 is collected in the solid collecting tank 4, and the liquid discharged from the reaction tank 1 flows into the calcining furnace 2 through the filter screen 5. An opening valve 6 is installed between the solid-liquid separation unit and the calcining furnace 2.

[0048] The bottom of the reaction tank 1 is a conical structure with a large top and a small bottom, and the solid collecting tank 4 is connected to the lowest point of the bottom of the reaction tank 1. A rotatable scraper 7 is installed in the reaction tank 1, and the scraper 7 is arranged close to the bottom of the reaction tank 1. A plurality of scraper heads 8 are arranged at intervals on the scraper 7, and the scraper heads 8 are close to the bottom of the reaction tank 1, and the ends of the scraper heads 8 are in an isosceles trapezoidal structure. Multiple scrapers 7 are arranged at intervals in the circumferential direction, and the scrapers 7 are arranged upwardly tilted away from the center of the reaction tank 1, and the scraper heads 8 installed on different scrapers 7 are radially staggered. Arranging multiple scrapers 7 is conducive to improving the stirring effect. The scraper heads 8 on different scrapers 7 are staggered, so that every position of the bottom of the reaction tank 1 can be scraped, thereby achieving a clean bottom of the reaction tank 1 without dead angles, and the staggered scraper heads 8 can reduce the resistance in the liquid.

[0049] A driving motor 9 is installed at the upper end of the reaction tank 1, and the output shaft of the driving motor 9 is connected to the rotating shaft 10. The scraper 7 is fastened to the rotating shaft 10, and a paddle frame 11 is installed on the rotating shaft 10. The paddle frame 11 is placed in the reaction tank 1. A solid feed port 12 is arranged at the upper end of the reaction tank 1, and a liquid feed pipe 13 is installed on the side wall of the reaction tank 1. The liquid feed pipe is arranged close to the upper part of the reaction tank 1, and a liquid feed valve 14 is installed on the liquid feed pipe 13.

[0050] like Figure 4 As shown, a feed hopper 15 is installed at the upper end of the reaction tank 1, a mixing barrel 16 is rotatably installed at the lower part of the feed hopper 15, a spiral conveying strip 17 is arranged on the inner wall of the mixing barrel 16, a mounting ring 18 is arranged below the feed hopper 15, the mixing barrel 16 is rotatably connected to the mounting ring 18, a water storage ring groove 19 is arranged on the mounting ring 18, a plurality of water outlet pipes 20 are installed at intervals on the mixing barrel 16, a plurality of water outlet holes 21 are arranged at intervals on the water outlet pipes 20, the opening ends of the water outlet holes 21 are all arranged clockwise or counterclockwise downward, and the water outlet pipe 20 and the liquid feed pipe 13 are both connected to the water storage ring groove 19. The upper end opening of the feed hopper 15 serves as the solid feed port 12.

[0051] The spiral conveyor bar 17 forms a ring structure after spiraling, so that a cavity is formed in the center to facilitate the falling of materials. A partition 22 is set in the feed hopper 15, and the partition 22 divides the feed hopper 15 into two chambers. Sodium sulfate and ammonium bicarbonate are respectively loaded into two different chambers for feeding. The inner wall of the mounting ring 18 is inclined from top to bottom and outward, and the water storage ring groove 19 is set on the outer wall of the mounting ring 18. The liquid feed pipe 13 is connected to the outer wall of the mounting ring 18 and communicates with the water storage ring groove 19.

[0052] When sodium sulfate, ammonium bicarbonate and water are added to the reaction tank 1, water is transported to the water storage ring groove 19 through the liquid feed pipe 13 and discharged outward through the water outlet 21 on the water outlet pipe 20. Since the opening ends of the water outlet 21 are all set clockwise or counterclockwise, the mixing barrel 16 is driven to operate under the reverse thrust of the water flow ejected from the water outlet 21. The spiral conveying bar 17 can drive the material to move downward as the mixing barrel 16 rotates, which helps to improve the mixing effect of sodium sulfate and ammonium bicarbonate, and thus facilitates the full reaction of the two, and prevents the mixing barrel 16 from blocking. Moreover, the water outlet 21 is set downward, and the water jetting downward can mix well with the material.

[0053] The calcining furnace 2 is connected to the gas storage tank 23 through a recovery pipe, and an exhaust pipe 24 is connected between the reaction tank 1 and the gas storage tank 23; an air intake valve 25 is installed on the recovery pipe, and an exhaust valve 26 is installed on the exhaust pipe 24. An air suction pump 27 is provided on the gas storage tank 23, and the air suction pump 27 extracts the gas in the calcining furnace 2 and stores it in the gas storage tank 23. A gas source dryer 28 is installed on the recovery pipe, and the gas source dryer 28 can absorb the water vapor in the mixed gas to prevent the water from flowing into the gas storage tank 23 to react with ammonia and carbon dioxide to generate ammonium bicarbonate.

[0054] The filter screen 5 is arranged to be movable, and one end of the filter screen 5 is connected to a preload spring 29, which abuts against the filter screen 5 to realize the positioning of the filter screen 5. A material-passing pipeline 30 is connected between the reaction tank 1 and the calcining furnace 2, and the filter screen 5 is installed in the material-passing pipeline 30. The internal cavity of the material-passing pipeline 30 above the filter screen 5 forms a solid collection tank 4. An opening valve 6 is installed on the material-passing pipeline 30, and the opening valve 6 is placed below the filter screen 5. A slideway 31 corresponding to the filter screen 5 is arranged on the outer wall of the material-passing pipeline 30, and a slider 32 is arranged at one end of the filter screen 5. The slider 32 is slidably connected to the slideway 31, and the slider 32 slides along the slideway 31. The end of the slideway 31 is connected to the end cover 33, and the preload spring 29 abuts between the end cover 33 and the slider 32. A lever 34 extending outward is arranged on the slider 32, and a long strip-shaped avoidance groove 35 is arranged on the slideway 31, and the lever 34 extends out of the avoidance groove 35. A boss 36 is provided at the outer end of the slider 32, and the boss 36 is fixed on the outer wall of the material passage pipe 30, and a sealing ring is provided between the boss 36 and the outer wall of the material passage pipe 30. A maintenance window is provided on the side wall of the material passage pipe 30, and the maintenance window is provided corresponding to the filter screen 5, and a maintenance door 37 is installed at the maintenance window to facilitate the maintenance and replacement of the filter screen 5.

[0055] The upper part of the calcining furnace 2 is connected to a vacuum pump 38 through a pipeline, and a vacuum valve 39 is installed on the pipeline between the vacuum pump 38 and the calcining furnace 2. When performing solid-liquid separation, the calcining furnace 2 is evacuated by the vacuum pump 38 to generate negative pressure in the calcining furnace 2, which is conducive to the mixed liquid in the reaction tank 1 to quickly flow into the calcining furnace 2, thereby improving the solid-liquid separation effect.

[0056] A method for preparing sodium carbonate from sodium sulfate is carried out by using a continuous reaction device for preparing sodium carbonate from sodium sulfate, comprising the following steps: S1, a liquid inlet valve 14 is opened, sodium sulfate, ammonium bicarbonate and water are added into a reaction tank 1 for reaction, the temperature in the reaction tank 1 is controlled at about 60°C, a driving motor 9 is started to drive a rotating shaft 10 to rotate, and a paddle frame 11 installed on the rotating shaft 10 stirs the reaction tank 1; at the same time, a scraper 7 and a scraper head 8 rotate together with the rotating shaft 10 to make sodium sulfate and ammonium bicarbonate fully mixed and reacted, and sodium bicarbonate crystals generated after the reaction at the bottom of the reaction tank 1 are scraped into a solid collection tank 4.

[0057] S2, solid-liquid separation is performed, the opening valve 6 and the air extraction valve 39 are opened, and the air extraction pump 38 is started to generate negative pressure in the calcining furnace 2, and the mixed liquid in the reaction tank 1 flows into the calcining furnace 2 after passing through the filter screen 5, and the sodium bicarbonate crystals generated after the reaction are blocked by the filter screen 5 and remain in the solid collection tank 4. After the solid-liquid separation is completed, the air extraction valve 39 and the opening valve 6 are closed. Then the air inlet valve 25 and the air suction pump 27 are opened to heat the liquid flowing from the reaction tank 1 to the calcining furnace 2, and the temperature of the calcining furnace 2 is controlled between 30°C and 60°C. The obtained ammonia and carbon dioxide are collected in the gas storage tank 23 and transported to the reaction tank 1 for the next reaction; the gas source dryer 28 installed on the recovery pipe can absorb the water vapor in the mixed gas to prevent the water from being sucked into the gas storage tank 23.

[0058] S3, cleaning the calcining furnace 2, collecting and cleaning the ammonium sulfate crystallized after the calcination of S2. Turn off the suction pump 27 and the air inlet valve 25, open the start valve, pull the slider 32 outward to move the filter 5 so that the sodium bicarbonate crystals in the solid collection tank 4 fall into the calcining furnace 2.

[0059] S4, heating the calcining furnace 2, controlling the temperature in the calcining furnace 2 between 50°C and 200°C, calcining the sodium bicarbonate to obtain a sodium carbonate product. The carbon dioxide generated in the process is collected through a recovery pipe and stored in a gas storage tank 23.

[0060] Sodium sulfate and ammonium bicarbonate in the reaction tank 1 undergo double decomposition reaction to generate sodium bicarbonate and ammonium sulfate. The solubility of ammonium sulfate in water is much greater than that of sodium bicarbonate in water, so ammonium sulfate dissolves in water and flows into the calcining furnace 2 through the filter screen 5 with the water flow. The sodium bicarbonate crystals are blocked by the filter screen 5 and collected in the solid collection tank 4. Solid-liquid separation is achieved by the solid-liquid separation unit. The mixed liquid in the calcining furnace 2 is heated, and the incompletely reacted ammonium bicarbonate is decomposed. The generated ammonia and carbon dioxide are collected in the gas storage tank 23 through the recovery pipe for storage, and are sent to the reaction tank 1 through the exhaust pipe 24 during the next reaction to achieve continuous reaction. During the reaction of sodium sulfate and ammonium bicarbonate in the reaction tank 1, the scraper 7 rotates, and the scraper 7 and the scraper head 8 stir the mixture together to fully mix the two and improve the reaction effect. In addition, the scraper head 8 is close to the bottom of the reaction tank 1, and the bottom of the reaction tank 1 is cleaned without dead angles, and the crystals at the bottom of the reaction tank 1 are cleaned, so that the crystals are collected in the solid collection tank 4 to avoid long-term accumulation of the product at the bottom.

[0061] After the heating of the calcining furnace 2 is completed, the crystallized ammonium sulfate is collected and the calcining furnace 2 is cleaned. Afterwards, the filter screen 5 is moved to make the sodium bicarbonate crystals in the solid collection tank 4 fall into the calcining furnace 2, and the calcining furnace 2 is heated to calcine the sodium bicarbonate to obtain a sodium carbonate product. The carbon dioxide generated in the process is collected through a recovery pipe and stored in a gas storage tank 23.

[0062] Example 3: A continuous reaction device for preparing sodium carbonate from sodium sulfate (see Figure 5 ), which has a structure similar to that of Example 2, the main difference being that in this embodiment, a plurality of blades 40 are arranged circumferentially at intervals on the outer wall of the mixing barrel 16, the outlet of the exhaust pipe 24 is arranged toward the blades 40, and the high-pressure airflow in the gas storage tank 23 blows toward the blades 40, driving the blades 40 to rotate, further driving the mixing barrel 16 to rotate. The high-pressure airflow is mixed with recycled ammonia and carbon dioxide, and the airflow has a good mixing effect with the water flow sprayed from the water outlet pipe 20 after being sprayed downward, which is beneficial to improving the reaction effect of sodium sulfate in the reaction tank 1. The other structures are the same as those of Example 2.

[0063] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A continuous reaction device for preparing sodium carbonate from sodium sulfate, characterized in that: It includes a reaction tank and a calcining furnace, a solid-liquid separation unit is arranged between the reaction tank and the calcining furnace, the calcining furnace is connected to the gas storage tank through a recovery pipe, and an exhaust pipe is connected between the reaction tank and the gas storage tank; the solid-liquid separation unit includes a solid collecting tank and a filter screen, the solid product after the reaction in the reaction tank is collected in the solid collecting tank, and the liquid discharged from the reaction tank flows into the calcining furnace through the filter screen.

2. A sodium sulfate preparation sodium carbonate continuous reaction device according to claim 1, characterized in that, A rotatable scraper is installed in the reaction tank, and a plurality of scraper heads are arranged at intervals on the scraper, and the scraper heads are close to the bottom of the reaction tank.

3. A sodium sulfate preparation sodium carbonate continuous reaction device according to claim 2, characterized in that, A plurality of scrapers are arranged at circumferential intervals, and the scraper heads installed on different scrapers are arranged in radial staggered positions.

4. A sodium sulfate preparation sodium carbonate continuous reaction device according to claim 1, characterized in that, The bottom of the reaction tank is a conical structure that is larger at the top and smaller at the bottom, and the solid collection tank is connected to the lowest point of the bottom of the reaction tank.

5. A sodium sulfate preparation sodium carbonate continuous reaction device according to claim 1, characterized in that, The calcining furnace is connected to the vacuum pump through a pipeline.

6. A continuous reaction device for preparing sodium carbonate from sodium sulfate according to claim 1, characterized in that: An air suction pump is arranged on the gas storage tank, and the air suction pump extracts the gas in the calcining furnace and stores it in the gas storage tank.

7. A continuous reaction device for preparing sodium carbonate from sodium sulfate according to claim 1, characterized in that: A gas source dryer is installed on the recovery pipe.

8. A continuous reaction device for preparing sodium carbonate from sodium sulfate according to claim 1, characterized in that: An air inlet valve is installed on the recovery pipe, an exhaust valve is installed on the exhaust pipe, and an opening valve is installed between the solid-liquid separation unit and the calcining furnace.

9. A continuous reaction device for preparing sodium carbonate from sodium sulfate according to any one of claims 1 to 8, characterized in that: The filter is movable, one end of the filter is connected to a preload spring, and the preload spring abuts against the filter to achieve positioning of the filter.

10. A method for preparing sodium carbonate from sodium sulfate, characterized in that: The preparation of sodium carbonate by using the sodium sulfate continuous reaction device according to any one of claims 1 to 9 comprises the following steps: S1, adding sodium sulfate, ammonium bicarbonate and water into a reaction tank, stirring the reaction tank, and scraping the sodium bicarbonate crystals at the bottom of the reaction tank into a solid collection tank; S2, heating the liquid flowing from the reaction tank to the calcining furnace, collecting the obtained ammonia and carbon dioxide into a gas storage tank to be transported to the reaction tank for the next reaction; S3, cleaning the calcining furnace, moving the filter screen to allow the sodium bicarbonate crystals in the solid collection tank to fall into the calcining furnace; S4, heating the calcining furnace to calcine the sodium bicarbonate to obtain sodium carbonate.

Images