Process for concentrating and desalting sulfuric acid

Abstract

The invention discloses a process for concentrating and desalting sulfuric acid. The process comprises the following steps: step 1, preparing a pre-cooling system; step 2, feed liquid feeding; step 3, crystallization process control; step 4, heating and melting; step 5, crystal recovery; step 6, recording and analyzing data; 7, cleaning and maintaining equipment; compared with an existing evaporation concentration process, the low-temperature crystallization sulfuric acid concentration and desalination process designed by the invention has the advantages that the corrosivity of sulfuric acid is lower, and strict requirements on materials of production equipment are greatly reduced, which means that more economical and applicable materials can be adopted; the initial investment cost and the long-term maintenance cost of the equipment are obviously reduced, the production economy is improved, meanwhile, the power consumption is greatly reduced compared with that of a traditional process, the production cost is reduced, the environment-friendly call of energy conservation and emission reduction is actively responded, the contribution is made to sustainable development of enterprises, and the economic benefit is increased. And waste materials generated by concentration and desalination are easy to recover.

Description

Technical Field

[0001] The invention relates to the technical field of sulfuric acid processing, in particular to a process for concentrating and desalting sulfuric acid. Background Art

[0002] Sulfuric acid is known as an indispensable raw material in many industrial processes. It is widely used in fertilizer, metallurgy, petroleum, textile, papermaking, medicine and other industries. It is an important catalyst and reactant in the production process of these industries. During the production and use process, sulfuric acid often contains a certain amount of salt, suspended matter, organic matter and other impurities; the presence of these impurities not only affects the purity of sulfuric acid, but also limits its application in high-end fields; for example, in the electronics industry, pharmaceutical manufacturing and other fields, the purity of sulfuric acid is required to be extremely high, and any trace impurities may affect the quality of the product. The sulfuric acid concentration and desalination process can significantly improve the purity of sulfuric acid by removing salt and impurities in sulfuric acid; high-purity sulfuric acid has broad application prospects in the fields of electronics, medicine, fine chemicals, etc., and can meet the needs of these industries for high-quality sulfuric acid.

[0003] The existing sulfuric acid concentration and desalination process has the following defects: First, it relies on high-temperature evaporation to concentrate sulfuric acid. However, under high temperature conditions, sulfuric acid exhibits extremely strong corrosiveness, which places extremely stringent requirements on the material and structure of production equipment. In order to meet this condition, special materials with high cost and high corrosion resistance have to be selected, which greatly increases the initial investment and subsequent maintenance costs of the equipment. Second, sulfuric acid itself has a high boiling point. This characteristic results in a large amount of energy being consumed during the evaporation and concentration process to maintain the necessary operating temperature, and high energy consumption further increases production costs. Third, the recovery of waste generated by sulfuric acid concentration and desalination is relatively troublesome. Summary of the invention

[0004] The object of the present invention is to provide a process for concentrating and desalting sulfuric acid to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a process for sulfuric acid concentration and desalination, comprising step one, preparation of a precooling system; step two, feeding of liquid feed; step three, control of crystallization process; step four, heating and sweating; step five, crystal recovery; step six, data recording and analysis; step seven, equipment cleaning and maintenance;

[0006] In the above step 1, the cooling circulation system is started for precooling;

[0007] wherein in the above step 2, the sulfuric acid to be concentrated is transported to the top of the crystallization tube;

[0008] Wherein in the above step 3, the sulfuric acid crystallization process is controlled by monitoring various parameters;

[0009] In the above step 4, the temperature is raised to melt the crystals, thereby removing impurities and salts;

[0010] wherein in the above step 5, the crystals are recovered for subsequent waste treatment;

[0011] In the above step 6, various data at the beginning and after concentration are recorded to evaluate the concentration effect;

[0012] In the above step seven, the equipment is cleaned and maintained regularly to ensure safe and efficient operation of the system.

[0013] As a further technical solution of the present invention, in the step one, the set temperature of the thermostatic bath is 5°C lower than the solidification point of the slurry to ensure sufficient cooling effect. The cooling medium adopts ethylene glycol aqueous solution, the initial temperature is room temperature, and then it is cooled to the set temperature through the refrigeration system. The flow rate of the cooling medium circulation pump is adjusted according to the size of the crystallization tube jacket to ensure uniform cooling. The thermostatic bath refrigeration system is started. After the temperature drops to the set value, the cooling medium circulation pump is turned on to check whether there is leakage in the circulation pipeline to ensure the sealing of the system.

[0014] As a further technical solution of the present invention, in the step 2, check that the inner wall of the crystallization tube is smooth and free of dirt, ensure uniform crystallization, the peristaltic pump is correctly installed, and the pipeline is not twisted or blocked. The pre-cooled cooling medium is continuously pumped to the crystallization tube jacket and the established cooling rate of 0.5°C / h is maintained to start cooling.

[0015] As a further technical solution of the present invention, in step 2, the peristaltic pump is started to transport the slurry from the feed barrel to the top of the crystallization tube at a stable flow rate, the slurry is observed to form a film flow on the tube wall, and the temperature is monitored to ensure that crystallization begins below the freezing point.

[0016] As a further technical solution of the present invention, in the step three, the inlet and outlet temperatures of the feed liquid are monitored in real time to ensure that the temperature difference is within the set range. The cooling rate is adjusted according to the crystallization speed to keep it constant or fine-tune it. The cooling rate is adjusted in time according to the crystallization situation to avoid too fast resulting in small crystals or too slow affecting efficiency. When the crystal layer grows to a predetermined thickness, the feed liquid circulation is stopped.

[0017] As a further technical solution of the present invention, in the step three, water in sulfuric acid is precipitated in the form of ice crystals through cooling crystallization, and sulfuric acid is concentrated due to the increase in concentration. This process reduces the solvent water content in the solution and increases the concentration of the solute sulfuric acid. At the same time, since the freezing point of sulfuric acid is much lower than that of water, during the cooling process, water first reaches the freezing point and crystallizes and precipitates, while taking away most of the inorganic salts and other salts dissolved in the water. Therefore, through crystallization and the subsequent heating and sweating process, the salt in sulfuric acid can be effectively removed to achieve the purpose of desalination.

[0018] As a further technical solution of the present invention, in the step four, the temperature of the cooling medium in the jacket of the crystallization tube is slowly increased to 1 to 2°C below the solidification point of the liquid, and this temperature is maintained for 10 to 20 minutes to melt the surface of the crystal and discharge the entrained impurities and salts, and a collecting device is set below the surface of the crystal to collect the melted crystal melt.

[0019] As a further technical solution of the present invention, in step five, the heating system is turned off, and after the crystal melt is collected, the circulation of the cooling medium is stopped, the valve under the crystallization tube is opened, and the crystals are discharged into the collection container by gravity or slight air pressure, and the waste is recovered and subsequently harmlessly treated.

[0020] As a further technical solution of the present invention, in step six, the mass fraction and volume of the initial and concentrated feed liquid, the concentration and volume of the crystal melt, the feed liquid inlet and outlet temperatures, the cooling medium temperature, and the cooling rate are recorded, the initial and final data are compared, the concentration and desalination efficiency is evaluated, the influence of parameters such as temperature and flow rate on the crystallization quality is analyzed, and the process parameters are optimized.

[0021] As a further technical solution of the present invention, in step seven, clean water or a specific solvent is used to clean the crystallization tube, the feed cylinder and related pipelines to remove residual sulfuric acid and impurities, and worn or damaged parts such as peristaltic pump hoses, seals, etc. are checked and replaced. The operating status of the thermostatic bath, cooling medium circulation pump and heating system is regularly checked to keep the equipment clean and dry to prevent corrosion and blockage.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention is designed with a low-temperature crystallization sulfuric acid concentration and desalination process. Compared with the existing evaporation and concentration process, sulfuric acid exhibits lower corrosiveness, which greatly reduces the strict requirements on the material of production equipment, which not only means that more economical and applicable materials can be used, but also significantly reduces the initial investment cost and long-term maintenance costs of the equipment, improves the economy of production, and at the same time, the power consumption is greatly reduced compared with the traditional process, which is not only conducive to reducing production costs, but also actively responds to the environmental protection call for energy conservation and emission reduction, and contributes to the sustainable development of enterprises. In addition, the waste generated by concentration and desalination is relatively easy to recycle, making the recycling and treatment of waste more convenient and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] Please see attached Figure 1 The present invention provides an embodiment: a sulfuric acid concentration and desalination process, comprising step 1, pre-cooling system preparation; step 2, liquid feeding; step 3, crystallization process control; step 4, heating and sweating; step 5, crystal recovery; step 6, data recording and analysis; step 7, equipment cleaning and maintenance;

[0026] In the above step 1, the set temperature of the thermostatic bath is 5°C lower than the solidification point of the feed liquid to ensure sufficient cooling effect. The cooling medium is ethylene glycol aqueous solution, the initial temperature is room temperature, and then it is cooled to the set temperature through the refrigeration system. The flow rate of the cooling medium circulation pump is adjusted according to the size of the crystallization tube jacket to ensure uniform cooling. The thermostatic bath refrigeration system is started. After the temperature drops to the set value, the cooling medium circulation pump is turned on to check whether there is leakage in the circulation pipeline to ensure the sealing of the system;

[0027] In the above step 2, check that the inner wall of the crystallization tube is smooth and free of dirt, ensure uniform crystallization, the peristaltic pump is correctly installed, and the pipeline is not twisted or blocked. The pre-cooled cooling medium is continuously pumped to the jacket of the crystallization tube, and the temperature is kept at a predetermined cooling rate of 0.5°C / h to start cooling. The peristaltic pump is started to transport the feed liquid from the feed barrel to the top of the crystallization tube at a stable flow rate. The film-like flow of the feed liquid on the tube wall is observed, and the temperature is monitored to ensure that crystallization begins below the freezing point.

[0028] In the above step three, the inlet and outlet temperatures of the feed liquid are monitored in real time to ensure that the temperature difference is within the set range. The cooling rate is adjusted according to the crystallization speed to keep it constant or fine-tune it. The cooling rate is adjusted in time according to the crystallization situation to avoid too fast resulting in small crystals or too slow affecting the efficiency. When the crystal layer grows to a predetermined thickness, the feed liquid circulation is stopped. Through cooling crystallization, the water in the sulfuric acid is precipitated in the form of ice crystals, and the sulfuric acid is concentrated due to the increase in concentration. This process reduces the solvent water content in the solution and increases the concentration of the solute sulfuric acid. At the same time, since the freezing point of sulfuric acid is much lower than that of water, during the cooling process, water first reaches the freezing point and crystallizes and precipitates, and at the same time takes away most of the inorganic salts and other salts dissolved in the water. Therefore, through crystallization and subsequent temperature rise and sweating process, the salt in the sulfuric acid can be effectively removed to achieve the purpose of desalination;

[0029] In the above step 4, the temperature of the cooling medium in the jacket of the crystallization tube is slowly increased to 1-2°C below the solidification point of the feed liquid, and this temperature is maintained for 10-20 minutes to melt the surface of the crystal and discharge the impurities and salts carried by the crystal, and a collection device is set below the surface of the crystal to collect the melted crystal liquid;

[0030] In the above step 5, the heating system is turned off, and after the crystal melt is collected, the cooling medium circulation is stopped, the valve under the crystallization tube is opened, and the crystals are discharged into the collection container by gravity or slight air pressure, and the waste is recovered and subsequently harmlessly treated;

[0031] In the above step 6, the mass fraction and volume of the initial and concentrated feed liquid, the concentration and volume of the crystal melt, the feed liquid inlet and outlet temperature, the cooling medium temperature, and the cooling rate are recorded, and the initial and final data are compared to evaluate the concentration and desalination efficiency, analyze the effects of parameters such as temperature and flow rate on the crystal quality, and optimize the process parameters;

[0032] In the above step seven, use clean water or a specific solvent to clean the crystallization tube, feed cylinder and related pipelines to remove residual sulfuric acid and impurities, check and replace worn or damaged parts such as peristaltic pump hoses, seals, etc., regularly check the operating status of the thermostatic bath, cooling medium circulation pump and heating system, keep the equipment clean and dry, and prevent corrosion and blockage.

[0033] Based on the above, the advantages of the present invention are: the present invention is designed with a low-temperature crystallization sulfuric acid desalination process. Compared with the existing evaporation concentration process, sulfuric acid exhibits lower corrosiveness, which greatly reduces the strict requirements on the material of production equipment. This not only means that more economical and applicable materials can be used, but also significantly reduces the initial investment cost and long-term maintenance costs of the equipment, and improves the economy of production. The low-temperature crystallization process avoids the high boiling point limitation of sulfuric acid, so that the entire concentration process can be completed at a lower energy consumption. This significant reduction in energy consumption is not only conducive to reducing production costs, but also actively responds to the environmental protection call for energy conservation and emission reduction. The waste components generated in the desalination process are relatively simple, which reduces the complexity of harmful substances in the waste, making the recovery and treatment of the waste more convenient and efficient.

[0034] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A process for sulfuric acid concentration and desalination, comprising step 1, preparation of a precooling system; step 2, feeding of liquid feed; step 3, control of crystallization process; step 4, heating and melting; step 5, crystal recovery; step 6, data recording and analysis; step 7, equipment cleaning and maintenance; characterized in that: In the above step 1, the cooling circulation system is started for precooling; wherein in the above step 2, the sulfuric acid to be concentrated is transported to the top of the crystallization tube; Wherein in the above step 3, the sulfuric acid crystallization process is controlled by monitoring various parameters; In the above step 4, the temperature is raised to melt the crystals, thereby removing impurities and salts; wherein in the above step 5, the crystals are recovered for subsequent waste treatment; In the above step 6, various data at the beginning and after concentration are recorded to evaluate the concentration effect; In the above step seven, the equipment is cleaned and maintained regularly to ensure safe and efficient operation of the system.

2. A process for sulfuric acid concentration and desalination according to claim 1, characterized in that: In the step 1, the set temperature of the thermostatic bath is 5°C lower than the solidification point of the slurry to ensure sufficient cooling effect. The cooling medium is an ethylene glycol aqueous solution, and the initial temperature is room temperature, which is then cooled to the set temperature through the refrigeration system. The flow rate of the cooling medium circulation pump is adjusted according to the size of the crystallization tube jacket to ensure uniform cooling. The thermostatic bath refrigeration system is started. After the temperature drops to the set value, the cooling medium circulation pump is turned on to check whether there is leakage in the circulation pipeline to ensure the sealing of the system.

3. A process for sulfuric acid concentration and desalination according to claim 1, characterized in that: In the step 2, check that the inner wall of the crystallization tube is smooth and free of dirt, ensure uniform crystallization, the peristaltic pump is correctly installed, and the pipeline is not twisted or blocked. The pre-cooled cooling medium is continuously pumped to the crystallization tube jacket and the established cooling rate of 0.5°C / h is maintained to start cooling.

4. A process for sulfuric acid concentration and desalination according to claim 3, characterized in that: In the step 2, the peristaltic pump is started to transport the liquid from the feed barrel to the top of the crystallization tube at a stable flow rate, the liquid is observed to form a film flow on the tube wall, and the temperature is monitored to ensure that crystallization begins below the freezing point.

5. A process for sulfuric acid concentration and desalination according to claim 1, characterized in that: In the step three, the inlet and outlet temperatures of the feed liquid are monitored in real time to ensure that the temperature difference is within the set range. The cooling rate is adjusted according to the crystallization speed to keep it constant or fine-tune it. The cooling rate is adjusted in time according to the crystallization situation to avoid too fast resulting in small crystals or too slow affecting efficiency. When the crystal layer grows to a predetermined thickness, the feed liquid circulation is stopped.

6. A process for sulfuric acid concentration and desalination according to claim 5, characterized in that: In the step three, water in sulfuric acid is precipitated in the form of ice crystals through cooling crystallization, and sulfuric acid is concentrated due to the increase in concentration. This process reduces the solvent water content in the solution and increases the concentration of the solute sulfuric acid. At the same time, since the freezing point of sulfuric acid is much lower than that of water, during the cooling process, water first reaches the freezing point and crystallizes and precipitates, while taking away most of the inorganic salts and other salts dissolved in the water. Therefore, through crystallization and the subsequent heating and sweating process, the salt in sulfuric acid can be effectively removed to achieve the purpose of desalination.

7. A process for sulfuric acid concentration and desalination according to claim 1, characterized in that: In the step 4, the temperature of the cooling medium in the jacket of the crystallization tube is slowly increased to 1-2°C below the solidification point of the feed liquid, and this temperature is maintained for 10-20 minutes to melt the surface of the crystal and discharge the entrained impurities and salts. A collection device is set below the surface of the crystal to collect the melted crystal melt.

8. A process for sulfuric acid concentration and desalination according to claim 1, characterized in that: In step five, the heating system is turned off, and after the crystal melt is collected, the circulation of the cooling medium is stopped, the valve below the crystallization tube is opened, and the crystals are discharged into the collection container by gravity or slight air pressure, and the waste is recovered and subsequently harmlessly treated.

9. A process for sulfuric acid concentration and desalination according to claim 1, characterized in that: In the step six, the mass fraction and volume of the initial and concentrated feed liquid, the concentration and volume of the crystal melt, the feed liquid inlet and outlet temperatures, the cooling medium temperature, and the cooling rate are recorded, the initial and final data are compared, the concentration and desalination efficiency is evaluated, the effects of parameters such as temperature and flow rate on the crystallization quality are analyzed, and the process parameters are optimized.

10. A process for sulfuric acid concentration and desalination according to claim 1, characterized in that: In step seven, clean water or a specific solvent is used to clean the crystallization tube, the feed cylinder and related pipelines to remove residual sulfuric acid and impurities, and worn or damaged parts such as peristaltic pump hoses and seals are checked and replaced. The operating status of the thermostatic bath, cooling medium circulation pump and heating system is regularly checked to keep the equipment clean and dry to prevent corrosion and blockage.

Images