A method for producing sodium bicarbonate using staged cooling

Abstract

This application provides a method for producing baking soda using staged cooling, comprising the following steps: S1, baking soda preparation, where baking soda is prepared by introducing carbon dioxide into a soda ash solution, and the prepared baking soda is dehydrated and dried to obtain powdered baking soda at a higher temperature; S2, primary cooling, where the baking soda obtained in step S1 is conveyed to a powder flow cooler for cooling and drying; S3, secondary cooling, where the baking soda that has undergone primary cooling is conveyed to a soda ash cooler for further cooling and drying. The staged cooling method for producing baking soda provided by this application significantly reduces the temperature and moisture content of the cooled baking soda, thereby extending the pseudo-caking period and improving the quality of the baking soda.

Description

Technical Field

[0001] This invention relates to the field of baking soda production technology, and in particular to a method for producing baking soda using staged cooling. Background Technology

[0002] Sodium bicarbonate (baking soda) in small bags tends to clump after 3-4 days of production, while in bulk bags it clumps after 2-3 days. If produced on the same day and sold to domestic customers the next, the estimated delivery time, 5-7 days, is insufficient to prevent clumping. This leads to quality complaints and severely damages the company's image. Therefore, each batch of baking soda is allowed to clump for 7 days before being crushed using a crushing device to prevent clumping, resulting in high transportation and crushing costs. Furthermore, previously exported bulk bags of baking soda (made by filling reusable bulk bags into export bulk bags) still exhibited clumping, with hard clumps. After investigation, it was found that the main causes of secondary clumping were excessively high alkali discharge temperature and high moisture content in the product, leading to further clumping during long-distance transportation. Therefore, improvements to the baking soda production process are urgently needed to reduce the alkali discharge temperature and product moisture content, thus delaying the clumping process. Summary of the Invention

[0003] The purpose of this invention is to provide a sodium bicarbonate production method using staged cooling, which solves the technical problem that pseudo-caking occurs again during long-term transportation of products made by traditional sodium bicarbonate production processes due to excessively high alkali discharge temperature and high moisture content.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a method for producing baking soda using staged cooling, the method comprising the following steps:

[0005] S1. Baking soda preparation: Baking soda is prepared by passing carbon dioxide into a soda ash solution, and the prepared baking soda is dehydrated and dried to obtain powdered baking soda at a higher temperature.

[0006] S2. First-stage cooling: The baking soda obtained in step S1 is conveyed to the powder flow cooler, where it is cooled and dried.

[0007] S3, Secondary Cooling: The baking soda that has completed the primary cooling process is transported to the alkali cooling machine. The alkali cooling machine further cools and dries the baking soda. After cooling, the temperature of the baking soda is below 35°C and the moisture content is controlled within 0.06%, thus obtaining the baking soda product.

[0008] In one embodiment, step S1 specifically includes:

[0009] S11, Alkali treatment: Solid soda ash is added to the alkali treatment tank and mixed with water to form an alkali solution.

[0010] S12. The alkali solution in the alkali dissolving tank is sequentially passed into the clarification tank, the clear liquid tank and the PE filter. The solid residue in the alkali solution is removed by standing clarification and filtration to obtain clear alkali solution, i.e. sodium carbonate solution.

[0011] S13, Carbonization: The lye solution is introduced into the carbonization tower, and carbon dioxide gas is introduced into the carbonization tower at the same time, so that the lye solution and carbon dioxide gas react to produce solid sodium bicarbonate.

[0012] S14. Baking soda extraction: The mixture containing baking soda after carbonization in the carbonization tower is passed through a thickener and a centrifuge in turn to separate the solid baking soda from the liquid in the mixture.

[0013] S15. Drying and dehydration: The baking soda obtained in step S14 is fed into a drying tube and dried through the drying tube.

[0014] In one embodiment, in step S14, the upper clear liquid in the thickener is passed into the filtrate tank. The filtrate after filtration in the filtrate tank can be passed into the carbonization tower for further carbonization treatment, or passed into the alkali-forming tank in step S11 as the liquid required for alkali-forming.

[0015] In one embodiment, step S15 further includes an exhaust gas treatment system, which specifically includes a cyclone separator and a bag filter. The exhaust gas discharged from the drying tube enters the cyclone separator and the bag filter in sequence. The cyclone separator and the bag filter are used to collect and remove the baking soda powder in the exhaust gas, and the collected baking soda powder can be directly packaged as finished product.

[0016] In one embodiment, the powder flow cooler adopts a vertical structure. The upper cooling section of the powder flow cooler is rectangular and has an inlet for introducing baking soda at the top. Several hollow heat transfer plates are arranged side by side in the cooling section. Cooling water outlet pipes and cooling water inlet pipes are respectively provided at the upper and lower ends of the heat transfer plates. The baking soda entering the cooling section flows downward through the gaps between the hollow heat transfer plates. A collection hopper is provided at the lower part of the powder flow cooler. The top of the collection hopper is connected to the cooling section, and a discharge port is provided at the bottom of the collection hopper.

[0017] In one embodiment, the alkali cooling machine includes a cooling cylinder, a stirring device, and a power unit. The cooling cylinder has a feed inlet at one end and a discharge outlet at the other end, and is tilted downwards towards the discharge outlet. The stirring device includes a hollow stirring shaft and hollow stirring blades. The hollow stirring shaft is rotatably disposed within the cooling cylinder, and has a cooling water inlet and a cooling water outlet at both ends. The hollow stirring blades are disposed on and connected to the hollow stirring shaft. The hollow stirring shaft is connected to the power unit, which drives the stirring shaft to rotate.

[0018] In one embodiment, both the powder flow cooler and the alkali cooler are equipped with temperature / humidity monitoring devices to ensure that environmental parameters during the cooling and drying process are within a predetermined range.

[0019] In one embodiment, the powder flow cooler and the alkali cooling machine further include an automatic water inlet and outlet control system, which is electrically connected to the temperature / humidity monitoring device. The automatic water inlet and outlet control system automatically adjusts the amount of cooling water entering and leaving the machine based on the temperature and humidity of the sodium bicarbonate monitored by the temperature / humidity monitoring device.

[0020] The above-described technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0021] The baking soda production method using staged cooling provided in this invention employs a powder flow cooler for primary cooling of the baking soda, followed by a alkali cooler for secondary cooling. This staged cooling method effectively reduces the temperature and moisture content of the baking soda product, ensuring that the temperature of the cooled baking soda is below 35°C and the moisture content is controlled below 0.06%. This extends the pseudo-caking period of the baking soda, prevents secondary agglomeration, and significantly improves the quality of the baking soda. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A process flow diagram of a sodium bicarbonate production method using staged cooling provided in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the structure of a powder flow cooler provided in an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the alkali cooling machine provided in an embodiment of the present invention.

[0026] The labels for the various figures are as follows:

[0027] 1. Powder flow cooler; 2. Alkali cooler; 11. Cooling section; 12. Collection hopper; 111. Cooling water outlet pipe; 112. Cooling water inlet pipe; 21. Cooling cylinder; 22. Agitator; 23. Power unit; 221. Hollow agitator blades. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0029] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

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

[0032] Please see Figures 1 to 3 This application provides a method for producing baking soda using staged cooling, comprising the following steps:

[0033] S1. Baking soda preparation: Baking soda is prepared by passing carbon dioxide into a soda ash solution, and the prepared baking soda is dehydrated and dried to obtain powdered baking soda at a higher temperature.

[0034] S2. First-stage cooling: The baking soda obtained in step S1 is conveyed to the powder flow cooler, where it is cooled and dried.

[0035] S3, Secondary Cooling: The baking soda that has completed the primary cooling process is transported to the alkali cooling machine 2. The alkali cooling machine 2 further cools and dries the baking soda. After cooling, the temperature of the baking soda is below 35°C and the moisture content is controlled within 0.06%, thus obtaining the baking soda product.

[0036] This example demonstrates a staged cooling method for producing baking soda. The method employs a powder flow cooler for primary cooling, followed by a secondary cooling process using a lye cooler. This staged cooling effectively reduces the temperature and moisture content of the baking soda product, ensuring the cooled product temperature remains below 35°C and the moisture content is controlled below 0.06%. This extends the pseudo-caking period of the baking soda, preventing secondary agglomeration and significantly improving its quality.

[0037] In this embodiment, the order in which the baking soda is cooled firstly by a powder flow cooler and then cooled secondarily by an alkali cooler 2 is very important.

[0038] If a primary cooling process using a caustic soda cooler 2 is employed, this type of equipment is typically designed to process large quantities of materials, and its internal structure and cooling mechanism are better suited for handling liquid or materials with a certain level of moisture. This is because caustic soda coolers 2 are often equipped with stirring or circulating devices to ensure that the material is heated or cooled evenly during the cooling process.

[0039] When using a powder flow cooler for secondary cooling, the cooler combines the principle of dense-phase material conveying with a traditional plate heat exchanger. It utilizes the material's own gravity and the micro-boiling state within the equipment to achieve cooling during the material's flow. However, during the cooling process of the baking soda in the alkali cooler 2, as the material temperature gradually decreases, the moisture contained within the material continuously precipitates onto the surface. The alkali cooler 2 only removes most of this moisture in the middle to later stages of the cooling process. However, since the moisture has already precipitated at the end of the alkali cooler 2, and with the rapid removal of the material, there is no time for it to be removed from the surface. The lower-temperature baking soda material with a certain amount of moisture on its surface will have reduced fluidity. In the secondary cooling powder flow equipment, the slowed flow of the baking soda material makes it prone to blockage, thus preventing the powder flow equipment from operating normally.

[0040] Furthermore, baking soda exists in powder form during the cooling stage. Powdered materials differ significantly from liquid or wet materials in terms of flowability and handling. If powdered baking soda is directly added to the primary cooling alkali cooler 2, uneven processing or even blockages may occur due to the equipment design.

[0041] In conclusion, because the design and structure of the primary cooling alkali cooler 2 are incompatible with the processing characteristics of powder materials, it is unreasonable to pre-cool baking soda through the alkali cooler 2. While the baking soda will experience some temperature reduction if pre-cooled by the alkali cooler 2, its cooling effect may be insufficient due to design limitations. This could lead to a decrease in temperature and water separation in the secondary cooling powder flow cooler, resulting in reduced fluidity and malfunction of the cooler. Powder flow coolers are typically designed to ensure uniform and effective cooling of powder materials during flow. However, if the baking soda is already at a low temperature before entering the powder flow, the equipment (due to the reduced fluidity of the baking soda) may not function properly, failing to lower its temperature to the ideal level and increasing the risk of false agglomeration.

[0042] Therefore, in this embodiment, the order of using a powder flow cooler for primary cooling of baking soda and then using a cooling alkali machine 2 for secondary cooling of baking soda is very important.

[0043] In one embodiment, step S1 specifically includes:

[0044] S11, Alkali treatment: Solid soda ash is added to the alkali treatment tank and mixed with water to form an alkali solution.

[0045] S12. The alkali solution in the alkali dissolving tank is sequentially passed into the clarification tank, the clear liquid tank and the PE filter. The solid residue in the alkali solution is removed by standing clarification and filtration to obtain clear alkali solution, i.e. sodium carbonate solution.

[0046] S13, Carbonization: The alkali solution is introduced into the carbonization tower, and carbon dioxide gas is introduced into the carbonization tower at the same time, so that the alkali solution and carbon dioxide gas react to produce solid baking soda; the chemical equation for the carbonization process is: Na2CO3(aq) + CO2(g) + H2O(l) = 2 NaHCO3(s).

[0047] S14. Baking soda extraction: The mixture containing baking soda after carbonization in the carbonization tower is passed through a thickener and a centrifuge in turn to separate the solid baking soda from the liquid in the mixture.

[0048] S15. Drying and dehydration: The baking soda obtained in step S14 is fed into a drying tube and dried through the drying tube.

[0049] This embodiment achieves efficient continuous production by optimizing processes such as carbonization, cooling, and drying. Furthermore, the modular design of the equipment makes maintenance and replacement more convenient, reducing downtime and further improving production efficiency.

[0050] In one embodiment, in step S14, the upper clear liquid in the thickener is passed into the filtrate tank. The filtrate after filtration in the filtrate tank can be passed into the carbonization tower for further carbonization treatment, or passed into the alkali-forming tank in step S11 as the liquid required for alkali-forming.

[0051] By filtering the upper clear liquid (containing sodium carbonate) in the thickener through a filter barrel and then passing it into the carbonation tower for further carbonation, or into the alkali-forming tank in step S11, the loss of sodium carbonate raw material is reduced, the utilization rate of sodium carbonate raw material is improved, and thus production costs are saved.

[0052] In one embodiment, step S15 further includes an exhaust gas treatment system, which specifically includes a cyclone separator and a bag filter. The exhaust gas discharged from the drying tube enters the cyclone separator and the bag filter in sequence. The cyclone separator and the bag filter are used to collect and remove the baking soda powder in the exhaust gas, and the collected baking soda powder can be directly packaged as finished product.

[0053] The introduction of the exhaust gas treatment system reduces environmental pollution during the production process, aligning with the concept of green production. Furthermore, the system can collect fine baking soda powder from the exhaust gas, thereby reducing baking soda product loss and increasing baking soda output.

[0054] like Figure 2As shown, in one embodiment, the powder flow cooler 1 adopts a vertical structure. The upper cooling section 11 of the powder flow cooler 1 is rectangular and elongated. The top of the cooling section 11 is provided with an inlet for introducing baking soda. Several hollow heat transfer plates are arranged side by side inside the cooling section 11. The upper and lower ends of the heat transfer plates are respectively connected to cooling water outlet pipes 111 and cooling water inlet pipes 112. The baking soda entering the cooling section 11 flows downward through the gaps between the hollow heat transfer plates. The lower part of the powder flow cooler 1 is provided with a collecting hopper 12. The top of the collecting hopper 12 is connected to the cooling section 11, and the bottom of the collecting hopper 12 is provided with a discharge port. After the baking soda powder enters the cooling section 11 from the top inlet, the baking soda transfers heat to the hollow heat transfer plates through heat exchange. Then, the cooling water inside the hollow heat transfer plates carries away the heat, thereby achieving the cooling treatment of the baking soda. As the temperature decreases, the water contained in baking soda continuously precipitates out onto the surface of the baking soda (the powder flow and alkali cooling machine are equipped with an automatic negative pressure adjustment device, which discharges the precipitated free water through a micro-negative pressure exhaust pipe), thereby reducing the water content of the baking soda.

[0055] like Figure 3 As shown, in one embodiment, the alkali cooling machine 2 includes a cooling cylinder 21, a stirring device 22, and a power unit 23. The cooling cylinder 21 has a feed inlet at one end and a discharge outlet at the other end. The cooling cylinder 21 is inclined downwards towards the discharge outlet. The stirring device 22 includes a hollow stirring shaft and hollow stirring blades 221. The hollow stirring shaft is rotatably disposed inside the cooling cylinder 21. Cooling water inlets and cooling water outlets are respectively disposed at both ends of the hollow stirring shaft. The hollow stirring blades 221 are disposed on the hollow stirring shaft and are connected to the hollow stirring shaft. The hollow stirring shaft is connected to the power unit 23, and the power unit 23 drives the stirring shaft to rotate.

[0056] During secondary cooling, cooling water is input from the cooling water inlet of the hollow stirring shaft. After entering the hollow stirring shaft, the cooling water flows into each hollow stirring blade 221 and then exits from the cooling water outlet of the hollow stirring shaft. By setting the hollow stirring shaft and the hollow stirring blades 221, the stirring device 22 can simultaneously cool the baking soda while stirring it, thereby improving the cooling efficiency.

[0057] In one embodiment, both the powder flow cooler and the alkali cooler 2 are equipped with temperature / humidity monitoring devices to ensure that environmental parameters during the cooling and drying process are within a predetermined range. Specifically, the temperature / humidity monitoring devices can be installed on the powder flow cooler and the alkali cooler 2 near the discharge port.

[0058] In one embodiment, the powder flow cooler and alkali cooler 2 also include an automatic water inlet / outlet control system. This system is electrically connected to a temperature / humidity monitoring device. The automatic water inlet / outlet control system automatically adjusts the cooling water inlet / outlet flow rate based on the temperature and humidity of the baking soda monitored by the device. By setting up this automatic water inlet / outlet control system, when the outlet temperature of the baking soda is too high (e.g., the outlet temperature of the baking soda in the alkali cooler 2 exceeds a predetermined value of 35°C), the system adjusts the cooling water inlet / outlet flow rate, increasing the flow rate and thus improving the cooling effect of the powder flow cooler / alkali cooler 2, ensuring that the outlet temperature of the baking soda meets the requirements. By setting up this automatic water inlet / outlet control system, automatic monitoring of the primary and secondary cooling processes is achieved, and automatic adjustments can be made based on the monitoring results to ensure the cooling temperature and quality of the baking soda.

[0059] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing small soda by fractional cooling, characterized by, The soda ash production method with staged cooling comprises the following steps: S1, soda ash preparation, soda ash is prepared by introducing carbon dioxide into a soda solution, and the prepared soda ash is subjected to dehydration and drying treatment to obtain powder-like soda ash with a relatively high temperature; S2, first-stage cooling, the soda ash prepared in step S1 is transported into a powder flow cooler, and the powder flow cooler is used to cool and dry the soda ash; S3, second-stage cooling, the soda ash subjected to the first-stage cooling is transported into a soda ash cooler, and the soda ash cooler is used to cool and dry the soda ash again, the temperature of the soda ash after cooling is lower than 35℃, the water content is controlled within 0.06%, and then the soda ash product is obtained; The powder flow cooler adopts a vertical structure, the upper cooling section of the powder flow cooler is in a rectangular strip shape, the top of the cooling section is provided with a feeding port for feeding in soda ash, and a plurality of hollow heat transfer plates are arranged side by side in the cooling section, the upper and lower ends of the heat transfer plates are respectively provided with a cooling water outlet pipe and a cooling water inlet pipe, the soda ash entering the cooling section flows downward through the gaps between the hollow heat transfer plates, and the lower part of the powder flow cooler is provided with a collecting hopper, the top of the collecting hopper is communicated with the cooling section, and the bottom of the collecting hopper is provided with a discharging port; The soda ash cooler comprises a cooling cylinder, a stirring device and a power unit, one end of the cooling cylinder is provided with a feeding port, the other end is provided with a discharging port, the cooling cylinder is inclined downward toward the discharging port, the stirring device comprises a hollow stirring shaft and a hollow stirring blade, the hollow stirring shaft is rotatably arranged in the cooling cylinder, and the two ends of the hollow stirring shaft are respectively provided with a cooling water inlet and a cooling water outlet; the hollow stirring blade is arranged on the hollow stirring shaft and is communicated with the hollow stirring shaft; the hollow stirring shaft is connected with the power unit, and the power unit drives the stirring shaft to rotate.

2. A process for producing small soda by fractional cooling according to claim 1, characterized in that, Step S1 specifically comprises: S11, soda ash preparation, solid soda ash is added into a soda ash bucket, and soda solution is prepared by mixing with water; S12, the soda solution in the soda ash bucket is sequentially introduced into a clarifying barrel, a clear liquid barrel and a PE filter, solid residues in the soda solution are removed by standing and clarifying and filtering, and clear soda solution, i.e., sodium carbonate solution, is obtained; S13, carbonization, the clear soda solution is introduced into a carbonization tower, and carbon dioxide gas is introduced into the carbonization tower at the same time, so that the clear soda solution reacts with the carbon dioxide gas to prepare solid soda ash; S14, soda ash extraction, the mixed solution containing soda ash after carbonization in the carbonization tower is sequentially introduced into a thickener and a centrifugal machine to separate the solid soda ash from the liquid; 3. The soda ash production method with staged cooling according to claim 2, wherein: In step S14, the upper layer of the clear solution in the thickener is introduced into a filtrate barrel, the filtrate after filtering in the filtrate barrel is introduced into the carbonization tower for carbonization treatment again or into the soda ash bucket in step S11 as liquid required for soda ash preparation. ​ 4. The method for producing small soda by using staged cooling according to claim 2, characterized in that: In step S15, a tail gas treatment system is further included, which specifically comprises a cyclone separator and a bag-type dust collector. The tail gas discharged from the drying pipe enters the cyclone separator and the bag-type dust collector in sequence. The cyclone separator and the bag-type dust collector are used to collect and remove the small soda fine powder in the tail gas, and the collected small soda fine powder is directly packaged as a finished product.

5. The method for producing small soda by using staged cooling according to claim 1, characterized in that: The powder flow cooler and the soda cooling machine are both equipped with temperature / humidity monitoring devices to ensure that the environmental parameters during the cooling and drying process are within a predetermined range.

6. The method for producing small soda by using staged cooling according to claim 5, characterized in that: The powder flow cooler and the soda cooling machine further include an automatic water inlet and outlet control system, which is electrically connected to the temperature / humidity monitoring device. The automatic water inlet and outlet control system automatically adjusts the water inlet and outlet amount according to the temperature / humidity monitoring device monitoring the temperature and humidity of the small soda.

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