Exploring the Solvent Extraction Tower: The Key Role of Industrial Separation

In the grand landscape of modern industry, the solvent extraction tower is like a bright pearl, emitting a unique and indispensable light. It stands quietly on the production lines of many key fields such as chemical, pharmaceutical, food, and environmental protection. With its excellent separation performance, it has become the mainstay to ensure smooth production processes, high product quality, rational use of resources and environmental protection.

In the chemical industry, from the purification of basic chemical raw materials to the synthesis and preparation of fine chemicals, solvent extraction towers are everywhere. It can accurately separate various components in complex mixtures, provide high-purity raw materials for subsequent chemical reactions, and ensure that the quality of chemical products is stable and meets strict standards. In the pharmaceutical industry, the purity of drugs is directly related to the life, health and treatment effect of patients. The solvent extraction tower shoulders the heavy responsibility of extracting and purifying effective drug ingredients from complex biological raw materials or synthetic intermediates. It is like a rigorous "pharmacist" who carefully removes impurities, so that every pill and every injection contains precise and effective therapeutic power.​

For the food industry, consumers have increasingly stringent requirements for food quality, taste and safety. Solvent extraction towers play a vital role in this. From extracting natural flavors and pigments to removing harmful residual substances in food raw materials, they bring us all kinds of food with attractive colors, fragrant aromas, safety and health. In the field of environmental protection, facing the increasingly severe environmental pollution problems, solvent extraction towers have become a powerful weapon for treating wastewater, waste gas and recycling valuable components in industrial waste, helping enterprises to achieve green production and protect our common home planet.
​
It is precisely because solvent extraction tower play such a key role in these fields that it is particularly important and meaningful for professionals in related industries and people interested in the development of industrial technology to explore its mysteries, understand its working principles, advantages and characteristics, and key points of operation and maintenance. Next, let us unveil the mysterious veil of solvent extraction towers and explore its inner world in depth.

I. Unveiling the mystery of solvent extraction towers

(I) Precise definition and conceptual explanation

Solvent extraction towers are essentially tower equipment that plays a key role in the liquid-liquid extraction process. In many industrial fields such as chemical engineering, petroleum refining, and environmental protection, they are important equipment for achieving liquid-liquid mass transfer, and are sometimes also called extraction towers. ​

Its core working principle is based on the mass transfer method of liquid-liquid extraction. Imagine a complex mixture solution that contains one or several compound components that we want to separate, enrich, or purify. At this time, another liquid that is immiscible with the solvent of the mixture solution is introduced, which we call a solvent. The different solubility or distribution coefficient of the compound in these two immiscible (or slightly soluble) solvents is used to transfer the compound from the original solvent to the newly introduced solvent. This process is like a carefully planned "molecular migration journey". Through repeated extraction and transfer, most of the target compounds can be extracted, thereby achieving separation, enrichment, and purification of the mixture.​

Take the process of extracting active ingredients from plants as an example. The active ingredients in plants (such as natural spices, medicinal ingredients, etc.) are originally dispersed in the cell fluid of plant tissues, which can be regarded as a mixture solution. We select a suitable organic solvent (such as ethanol, petroleum ether, etc.) as the extractant. Since the solubility of the active ingredients in this organic solvent is much greater than that in the cell fluid, when we fully contact the plant raw materials with the organic solvent in the solvent extraction tower, the active ingredients will be transferred from the cell fluid to the organic solvent. After many such extraction processes, the concentration of the active ingredients in the organic solvent continues to increase, and finally the purpose of extracting active ingredients from plants is achieved. ​

(II) Indispensable structural composition​

Although the solvent extraction tower may look like a tall tower structure, it is actually composed of multiple well-designed and coordinated parts, each of which plays an indispensable role in the extraction process.​

1. Main tower body: As the core bearing component of the solvent extraction tower, the main tower body is usually made of high-quality metal materials (such as stainless steel, carbon steel, etc.). In some special application scenarios with extremely high corrosion resistance requirements, special alloy materials or non-metallic materials (such as glass, engineering plastics, etc.) are also selected. Its main function is to provide a closed and stable space for the entire extraction process, ensuring that the raw material liquid and the solvent can fully contact and transfer mass reactions according to the predetermined process. The shape of the main tower body is generally cylindrical. This shape can not only ensure the uniform distribution and stable flow of the internal fluid, but also has good mechanical properties, and can withstand the pressure of the internal liquid and the force of the external environment. The design of its height and diameter needs to be accurately calculated and optimized according to specific production requirements, material properties, and processing volume to achieve the best extraction effect. ​

2. Feed port: The feed port is the channel for the raw material liquid and solvent to enter the solvent extraction tower, which is usually set at different heights of the tower body. The feed port of the raw material liquid is generally located in the middle and lower part of the tower body. This design is to allow the raw material liquid to flow from top to bottom under the action of gravity and form a countercurrent contact state with the solvent entering from the upper part of the tower body. Countercurrent contact can significantly increase the mass transfer driving force between the raw material liquid and the solvent and improve the extraction efficiency. The solvent feed port is located at the upper part of the tower body to ensure that the solvent can be evenly distributed in the tower and fully mixed with the raw material liquid. The design of the feed port needs to fully consider factors such as the flow rate, flow rate and distribution uniformity of the fluid. Usually, it is equipped with special distribution devices, such as distributors and nozzles, to ensure that the raw material liquid and the solvent can enter the tower in a suitable manner to avoid bias flow, short circuit and other situations that are not conducive to extraction. ​

3. Discharge port: The discharge port undertakes the important task of discharging the two-phase liquid after extraction. It is divided into a light phase discharge port and a heavy phase discharge port. During the extraction process, due to the different densities of the two liquids, two layers of light phase and heavy phase liquid will be formed. The light phase discharge port is generally set at the top of the tower body to discharge the light phase liquid rich in target products and relatively low density after extraction; the heavy phase discharge port is located at the bottom of the tower body to discharge the heavy phase liquid with high density, which contains impurities that have not been completely extracted and part of the solvent. The position and size design of the discharge port also need to be accurately considered according to the actual situation to ensure the smoothness and stability of the discharge and avoid problems such as blockage and flooding. ​

4. Raw material distributor: The raw material distributor is installed below the raw material liquid feed port. Its function is to evenly distribute the raw material liquid entering the tower on the cross section of the tower so that the raw material liquid can fully contact with the solvent. It usually adopts special structural designs, such as porous plates, overflow weirs, etc., through which the raw material liquid is dispersed into fine droplets or liquid flows, increasing its contact area with the solvent, thereby improving the mass transfer efficiency. ​

5. Solvent distributor: Similar to the raw material distributor, the solvent distributor is installed below the solvent feed port and is responsible for evenly distributing the solvent into the tower. Its design also focuses on the dispersion effect and uniformity of the solvent to ensure that the solvent can achieve good mixing and mass transfer with the raw material liquid throughout the tower. ​

6. Packing layer: The packing layer is a key component in the solvent extraction tower to promote mass transfer, and is filled in a specific area inside the tower. There are many types of packing, the most common of which are Raschig rings, ball rings, saddle packings, etc., which have a large specific surface area and good fluid mechanics. When the raw material liquid and the solvent flow in the packing layer, the packing can continuously disperse and re-aggregate the liquid, increase the contact area and contact time between the two phases, thereby strengthening the mass transfer process and improving the extraction efficiency. Different types of packing are suitable for different material systems and process requirements, and in practical applications, they need to be reasonably selected according to specific circumstances. ​

7. Collector: The collector is located at the bottom and top of the tower body, and is used to collect heavy phase and light phase liquids respectively. The heavy phase collector at the bottom can effectively collect the settled heavy phase liquid and discharge it out of the tower through the heavy phase outlet; the light phase collector at the top is responsible for collecting the light phase liquid that rises to the top of the tower to ensure that it flows out smoothly from the light phase outlet. The design of the collector needs to ensure the collection efficiency and discharge stability of the liquid, and avoid problems such as liquid retention or secondary mixing. ​

It is the close cooperation and mutual complementation between these structural components that enable the solvent extraction tower to operate efficiently and stably, achieve accurate separation and purification of the mixture, and play an irreplaceable and important role in industrial production.

II. In-depth analysis of the working principle

(I) Core principle: the wonderful application of solubility and distribution coefficient

The core working principle of the solvent extraction tower is based on a seemingly simple but profound chemical mystery, that is, using the significant difference in the solubility or distribution coefficient of the compound in two immiscible (or slightly soluble) solvents to achieve the transfer of the compound from one solvent to another, thereby achieving the goal of separation, enrichment and purification of the mixture. ​

When we place a solute in two immiscible solvent systems, the solute will be distributed between the two solvents. Under certain temperature and pressure conditions, if the molecular form of the solute in the two solvents remains consistent, then after a period of time, the concentration of the solute in the two phases will reach a dynamic equilibrium state, at which time the concentration ratio of the solute in the two phases is a fixed constant, which is the famous distribution law.

For example, in the classic experiment of extracting iodine from an aqueous solution containing iodine, we selected carbon tetrachloride as the extractant. Since the solubility of iodine in carbon tetrachloride is much greater than that in water, when carbon tetrachloride is added to the iodine aqueous solution and fully shaken and mixed, the iodine originally dissolved in water will quickly transfer to the carbon tetrachloride phase. In this process, the concentration of iodine in the carbon tetrachloride phase and the water phase changes continuously until it reaches a state of equilibrium. At this time, the ratio of the concentration of iodine in the carbon tetrachloride phase to the concentration in the water phase is its distribution coefficient. Through experimental determination, under specific temperature and pressure conditions, the distribution coefficient of iodine in the carbon tetrachloride-water system is a relatively stable value. ​

The distribution coefficient plays an important role in the solvent extraction process. It is a key indicator for measuring extraction efficiency. The larger the distribution coefficient, the higher the concentration of the solute in the organic phase, which means that the extractant has a stronger extraction ability for the solute and can more effectively extract the solute from the original solvent. In actual industrial production, we can optimize the distribution coefficient by cleverly selecting a suitable extractant and accurately controlling conditions such as extraction temperature and pressure, thereby significantly improving extraction efficiency and reducing production costs.
​
(II) Full analysis of the extraction process: every step from feeding to discharging​

1. Raw material feeding: The raw material liquid is like a "traveler" with a mission. It enters the solvent extraction tower in an orderly manner from the middle and lower part of the tower body through a carefully designed feed port. The raw material distributor equipped at the feed port is like a skilled "conductor". It can evenly disperse the raw material liquid on the cross-section of the tower body to ensure that every drop of raw material liquid has the opportunity to fully contact with the subsequent solvent. This process is crucial to improving the overall extraction efficiency. The evenly distributed raw material liquid can increase the contact area with the solvent and create good conditions for the mass transfer process. ​

2. Solvent feeding: At the same time, the solvent enters the tower lightly from the upper part of the tower body. The solvent distributor also plays a key role. It sprays or distributes the solvent evenly in the tower, so that the solvent can collide and blend with the raw material liquid flowing from top to bottom in the best state. The feed rate and distribution uniformity of the solvent need to be strictly controlled and adjusted to ensure efficient mass transfer between it and the raw material liquid. If the solvent is not fed evenly, the raw material liquid in some areas may not be able to fully contact with the solvent, thereby reducing the extraction effect. ​

3. Reaction and separation: When the raw material liquid and the solvent meet in the tower, a fierce and orderly "molecular exchange dance" officially begins. On the magical "stage" of the packing layer, the raw material liquid and the solvent are fully mixed, and the target compound is quickly transferred from the raw material liquid phase to the solvent phase according to the difference in its solubility and distribution coefficient in the two solvents. The presence of the packing layer greatly increases the contact area and contact time between the two phases, allowing the mass transfer process to be carried out efficiently. In this process, the temperature and pressure conditions in the tower will also have a significant impact on the extraction effect. Changes in temperature will change the solubility and distribution coefficient of the compound, and adjustments in pressure may affect the volatility and mass transfer rate of the solvent. Therefore, accurately controlling the temperature and pressure in the tower to keep them within an appropriate range is the key to achieving efficient extraction. ​

4. Discharge and collection: After sufficient reaction and separation in the tower, the light phase and heavy phase liquids have completed their missions and move toward their respective discharge ports in an orderly manner. The light phase liquid, which is usually rich in target products and has a relatively low density, will slowly rise to the top of the tower and be smoothly discharged from the tower through the light phase outlet; while the heavy phase liquid, which contains impurities that have not been completely extracted and some solvents, will sink to the bottom of the tower under the action of gravity due to its high density, and will eventually be collected from the heavy phase outlet. The collector at the outlet is like a diligent "guardian", ensuring that the light and heavy phase liquids can be stably and smoothly collected and discharged to avoid any blockage or leakage. ​

The entire extraction process is like a carefully choreographed symphony, and every link is closely connected and indispensable. From the orderly distribution of raw materials during feeding, to the precise control of solvent feeding, to the efficient mass transfer during the reaction and separation process, and finally the stability and smoothness of discharge and collection, each step has been carefully designed and strictly controlled by engineers, which together ensures that the solvent extraction tower can operate efficiently and stably, and achieve accurate separation and purification of the mixture.

III. Significant advantages of solvent extraction towers

(I) High efficiency: rapid and efficient separation

The solvent extraction tower has demonstrated remarkable performance in separation efficiency. Compared with traditional separation methods, it can achieve higher separation purity in a shorter time. This advantage is of great significance in industrial production.

Take the production example of a chemical company as an example. When separating a complex organic mixture, the traditional distillation separation method requires a long 6-hour operation, and the purity of the target product can only reach 80%. When the solvent extraction tower is used for separation, this process is greatly shortened to 1.5 hours, and the purity of the target product soars to more than 95%. This sharp data comparison intuitively and powerfully highlights the huge advantages of the solvent extraction tower in separation efficiency.

The key to the solvent extraction tower's ability to achieve such efficient separation lies in its unique internal structure and scientific and reasonable workflow. As mentioned above, the carefully designed packing layer in the tower is like a microscopic "molecular exchange battlefield", which can greatly increase the contact area and contact time between the raw liquid and the solvent. When the raw liquid and the solvent flow in the packing layer, the special shape and surface properties of the packing make the liquid constantly dispersed and re-aggregated, forming countless tiny droplets and liquid films. These tiny interfaces provide a broad stage for the mass transfer of solutes. In this microscopic world, solute molecules can quickly transfer from the raw liquid phase to the solvent phase, greatly accelerating the separation speed. ​

In addition, the solvent extraction tower usually adopts the countercurrent extraction method, which is like a relay race, where the two athletes run in opposite directions and continuously exchange substances. The raw liquid enters from the bottom of the tower and flows from bottom to top; the solvent enters from the top of the tower and flows from top to bottom. This countercurrent contact method keeps the mass transfer driving force at a high level, thereby significantly improving the extraction efficiency. Compared with cocurrent extraction, countercurrent extraction can achieve higher separation efficiency under the same tower height and tower diameter conditions, which is also one of the important manifestations of the high efficiency of solvent extraction towers.​

(II) Low energy consumption: an environmental pioneer in energy saving and consumption reduction

Under the background of the global active advocacy of energy conservation, emission reduction and green development, the solvent extraction tower has become a well-deserved pioneer in energy conservation and consumption reduction in the industrial field with its outstanding low energy consumption characteristics. ​

From the perspective of energy consumption, the reason for the low energy consumption of the solvent extraction tower is mainly due to its unique structural design and working principle. First of all, the structural optimization inside the solvent extraction tower makes the flow of liquid in the tower smoother, reducing unnecessary resistance and energy loss. For example, the reasonably designed feed and discharge ports can ensure the smooth and orderly entry and exit of the raw material liquid and the solvent, avoiding the energy waste caused by the sudden change of flow rate; the carefully arranged tower internals, such as distributors, fillers, etc., can promote the uniform distribution and full mixing of the liquid, improve the mass transfer efficiency, and reduce the power consumption required to achieve the same separation effect.
​
Secondly, the working process of the solvent extraction tower is mainly based on the physical dissolution and distribution principles. Compared with some separation methods that require high temperature, high pressure and other drastic conditions, such as distillation and rectification, it does not need to consume a lot of heat energy to achieve the phase change of the substance. In the distillation process, the mixture needs to be heated to the boiling point to vaporize some of the components, and then recovered by condensation. In this process, a large amount of heat energy is used to maintain high temperature and achieve phase change, which consumes a lot of energy. The solvent extraction tower can perform extraction operations at room temperature and pressure, and only a small amount of power is required to drive the flow and stirring of the liquid, thereby greatly reducing energy consumption.
​
Take the production practice of a large pharmaceutical company as an example. After the company used solvent extraction towers to replace traditional distillation equipment for drug component extraction, the annual energy consumption was greatly reduced by more than 30%. This not only saves a lot of energy costs for the company and reduces carbon emissions to the environment, but also responds to the country's environmental protection policies and enhances the company's social image. ​

From an environmental protection perspective, the low energy consumption characteristics of the solvent extraction tower have multiple positive meanings. On the one hand, reducing energy consumption means reducing dependence on traditional fossil energy such as coal and oil, thereby indirectly reducing the pollution caused to the environment during the mining and combustion of these energy sources, such as air pollution, water pollution and soil pollution. On the other hand, low energy consumption can also help ease the global energy shortage and contribute to sustainable development. In addition, the organic solvents commonly used in the extraction process of the solvent extraction tower can be recycled and reused, further reducing the generation of waste and the impact on the environment, which is in line with the concept of green chemistry and circular economy. ​

(III) Cost-effectiveness: low cost and high return ​

The solvent extraction tower performs well in cost-effectiveness. Considering from multiple dimensions such as equipment cost and operating cost, it can significantly reduce the overall cost of the enterprise during long-term use and bring considerable economic benefits to the enterprise. It can be called a "cost optimization tool" in the production and operation of the enterprise. ​

In terms of equipment cost, although the initial investment of the solvent extraction tower may be relatively high, its excellent performance and long service life give it an excellent cost-sharing advantage in the long-term production process. High-quality solvent extraction towers are usually made of high-strength, corrosion-resistant materials, such as stainless steel and special alloys. Although these materials are expensive, they can ensure long-term stable operation of the equipment in harsh working environments, reducing the frequency of equipment maintenance and replacement. Compared with some low-priced but unstable and easily damaged equipment, solvent extraction towers can avoid additional costs caused by frequent maintenance and replacement of equipment in long-term use, such as equipment procurement costs, installation and commissioning costs, and production stoppage losses. According to relevant statistics, a high-quality solvent extraction tower can have a service life of 15-20 years under normal maintenance, which is much higher than ordinary equipment of the same type. ​

From the perspective of operating costs, the low energy consumption characteristics of solvent extraction towers have been elaborated in detail in the previous article, which is undoubtedly one of the key factors in reducing operating costs. Lower energy consumption means that the company's expenditure on electricity, steam and other energy sources is greatly reduced. Taking a medium-sized chemical company as an example, if the company uses solvent extraction towers for production, the annual energy savings can reach hundreds of thousands or even millions of yuan. In addition, the continuous production capacity and high separation efficiency of the solvent extraction tower greatly increase the output per unit time, thereby reducing the production cost per unit product. For example, in the same production time, the production line using the solvent extraction tower can produce more qualified products, and the equipment depreciation, labor costs, raw material consumption and other expenses allocated to each product are reduced accordingly. ​

Furthermore, the efficient utilization and recycling capacity of the solvent extraction tower for the extractant also saves a lot of costs for the enterprise. During the extraction process, the solvent extraction tower can maximize the extraction efficiency of the extractant for the target substance and reduce the amount of the extractant by optimizing the design and operating conditions. At the same time, it is also equipped with a complete extractant recovery system, which can recycle, regenerate and recycle the used extractant, reducing the company's procurement cost of fresh extractant. Some advanced solvent extraction towers can even achieve near-zero emissions of extractants, which is both environmentally friendly and economical. ​

(IV) Easy to control: simple and precise operation​

In modern industrial production, the widespread application of automation control technology has greatly improved production efficiency and product quality stability. Solvent extraction towers keep pace with the times and are equipped with advanced automation control systems, which enable operators to easily and accurately control various operating parameters to ensure that the extraction process is always in a stable and efficient operating state. ​

The automation control system of the solvent extraction tower is like an experienced and responsive "smart housekeeper". It integrates advanced sensor technology, automation instruments and computer control systems. Through sensors installed in various key parts of the tower body, such as temperature sensors, pressure sensors, flow sensors, etc., important parameters such as temperature, pressure, liquid level, flow, etc. in the tower can be collected in real time and accurately. These sensors are like the "eyes" and "ears" of the system, and quickly transmit the collected data to the automation instruments and computer control systems. ​

After the automation instruments perform preliminary processing and analysis on these data, they are transmitted to the computer control system. The computer control system conducts in-depth analysis and calculation of the collected data according to the preset program and control strategy, and then issues precise control instructions. These instructions accurately control various equipment in the tower through actuators, such as regulating valves, pumps, motors, etc. For example, when the temperature in the tower is detected to be too high, the control system will automatically adjust the flow of the cooling medium to reduce the temperature in the tower; when the feed flow is found to be unstable, the speed of the feed pump will be automatically adjusted to ensure the stability of the feed flow. ​

This automated control method not only greatly improves the accuracy and stability of the operation, but also significantly reduces the workload of the operator. The operator does not need to keep an eye on the equipment and manually adjust various parameters. He only needs to monitor the computer system in the control room to grasp the operation of the tower in real time and make remote intervention and adjustments when necessary. This not only reduces the impact of human factors on the extraction process and improves the consistency of product quality, but also reduces the risk of production accidents caused by human operational errors. ​

In addition, some advanced solvent extraction tower automation control systems also have fault diagnosis and early warning functions. When the system detects an abnormal situation in the equipment, it can quickly issue an alarm, and through data analysis and fault diagnosis algorithms, accurately determine the cause and location of the fault, and provide detailed maintenance suggestions and guidance for maintenance personnel. This greatly shortens the maintenance time of the equipment and improves the utilization rate and production efficiency of the equipment.

IV. Standard Operation Guidelines​

(I) Cold Start-up: Preparation and Start-up Steps​

1. Comprehensive Inspection: Before starting the solvent extraction tower, the equipment must be thoroughly and carefully inspected to ensure that the equipment is in a good state for operation. The inspection covers the tower body, feed port, discharge port, distributor, packing layer, collector, and the pipes, valves, pumps and other equipment connected to it to check for damage, leakage, blockage and other problems. Pay special attention to the integrity of the tower body to ensure that there are no cracks, deformations and other defects that affect the strength and sealing of the equipment; check the unobstructed conditions of the feed port and discharge port to prevent blockage by foreign matter; check the distributor and collector to ensure that they can evenly distribute and collect liquid; carefully check the packing layer to ensure that the packing is not damaged or unevenly stacked. At the same time, all connection parts, such as flanges and pipe fittings, should be checked to ensure that they are well sealed and have no signs of looseness. ​

2. Watering Operation: After the inspection is completed, the tower body is watered. The purpose of this step is to conduct preliminary commissioning and inspection of the tower body and create a stable liquid environment for subsequent extraction operations. First, slowly open the water source valve connected to the tower body to allow water to enter the tower at an appropriate flow rate. During the water filling process, pay close attention to the changes in the liquid level in the tower and monitor the liquid level height in real time through the liquid level meter. When the liquid level reaches a certain proportion of the tower height (usually 50% - 60%), gradually reduce the water flow rate to avoid the liquid level rising too fast, causing water overflow or impact on the structure inside the tower. When the liquid level reaches the predetermined height, close the water source valve and stop filling. At this time, further inspect the tower body to check whether there is any leakage, especially at the welds, joints and valves of the tower body. If there is any leakage, it should be repaired in time to ensure the sealing of the tower body. ​

3. Start the heat exchanger: Next, start the heat exchanger that matches the solvent extraction tower to preheat or cool the raw material liquid and solvent entering the tower to meet the temperature requirements of the extraction process. According to the process requirements, set the temperature parameters of the heat exchanger to ensure that it can heat or cool the material to a suitable temperature range. When starting the heat exchanger, first slowly open the inlet valves of the cold and hot media, and pay close attention to the operating status of the heat exchanger, such as changes in parameters such as pressure, temperature, and flow. Gradually adjust the flow of cold and hot media to make the heat exchanger reach a stable working state and ensure that the material can enter the extraction tower at the specified temperature. Note that when adjusting the flow, avoid large adjustments to avoid causing excessive temperature fluctuations and affecting the extraction effect. ​

4. Introducing the reaction liquid: After the heat exchanger is operating normally, start the raw liquid delivery pump to extract the raw liquid from the raw material storage tank and transport it to the feed port of the extraction tower through the pipeline. Before starting the pump, check the lubrication of the pump, whether the motor wiring is correct, and the status of the inlet and outlet valves. After ensuring that the pump is in good working condition, open the inlet valve of the pump, then start the pump, and then slowly open the outlet valve of the pump to adjust the flow of the raw liquid to the value required by the process. At the same time, start the solvent delivery pump to transport the solvent from the solvent storage tank to the other feed port of the extraction tower. Similarly, before starting the solvent pump, conduct a comprehensive inspection to ensure the normal operation of the pump. Adjust the flow rate of the solvent to match the flow rate of the raw liquid to ensure good countercurrent contact and mass transfer in the tower. During the process of introducing the reaction liquid, pay close attention to the changes in parameters such as liquid level, pressure, and temperature in the tower to ensure that the entire process proceeds smoothly.
​
(II) Normal operation: Key points for stable operation

1. Parameter monitoring and adjustment: During the normal operation of the solvent extraction tower, strict monitoring and timely adjustment of various operating parameters are the key to ensuring the extraction effect and stable operation of the equipment. Sensors installed at various key parts of the tower body, such as temperature sensors, pressure sensors, flow sensors, liquid level sensors, etc., are used to collect parameters such as temperature, pressure, liquid level, and flow in the tower in real time. The operator closely monitors the changes in these parameters through the display screen of the control system to ensure that they always remain within the range of process requirements. Once a parameter is found to deviate from the set value, the cause is immediately analyzed and corresponding adjustment measures are taken. For example, if the temperature in the tower is found to be rising, it may be caused by poor heat exchange of the heat exchanger, too high feed temperature or reaction exotherm. At this time, the operation of the heat exchanger should be checked first, and the flow of the cold medium should be adjusted to enhance the heat exchange effect; if the feed temperature is too high, the raw material liquid or solvent can be further cooled; if it is determined that the temperature rise is caused by reaction exotherm, the feed flow rate can be appropriately adjusted or coolant can be added to control the temperature. Similarly, for abnormal changes in parameters such as pressure, liquid level and flow, the reasons should be analyzed in time and adjusted accordingly to ensure stable operating conditions in the tower.
​
2. Regular equipment inspection: In addition to monitoring operating parameters, regular and comprehensive inspection of equipment is also essential. Develop a detailed equipment inspection plan and inspect the solvent extraction tower and related equipment at certain time intervals (such as daily, weekly or monthly). The inspection content includes the appearance of the tower body, check whether there is corrosion, deformation, leakage, etc.; check the working status of the feed port, discharge port, distributor, collector and other components to ensure their normal operation; check the packing layer to observe whether the packing is damaged, blocked, lost, etc., and repair or replace it in time if there is any problem; check the operation of pipelines, valves, pumps and other equipment to check whether there are leakage, vibration, abnormal noise and other problems, check the opening and closing flexibility and sealing of the valves, and check the lubrication of the pump and the operating current of the motor. In addition, the control system should be checked to ensure that the sensors, instruments, automation devices, etc. are working properly and the data transmission is accurate. Through regular equipment inspections, potential problems can be discovered in time, and effective measures can be taken to deal with them, avoid equipment failures, and ensure the continuity and stability of production.

3. Timely handling of small problems: During the operation of the solvent extraction tower, some small problems are inevitable, such as slight leakage, local blockage, abnormal instrument display, etc. For these small problems, operators must not take them lightly, and must deal with them in time to prevent the problems from expanding and affecting the normal operation of the equipment and the extraction effect. Once a slight leak is found, the location and cause of the leak must be determined first. If the leak is caused by damage to the gasket at the pipe connection, the machine should be shut down in time and the gasket should be replaced; if the valve is not tightly sealed, the valve can be repaired or replaced. For local blockage problems, such as blockage of the small holes of the feed port or distributor, flushing and unblocking can be used to deal with it. If the instrument displays abnormality, first check whether the power supply and wiring of the instrument are normal. If the abnormality is still displayed after eliminating these problems, the instrument can be calibrated or replaced. When dealing with these minor problems, strictly abide by the operating procedures and take necessary safety measures to ensure the personal safety of operators and the safety of equipment. Timely handling of minor problems can not only avoid equipment failures, but also improve the operating efficiency of the equipment and reduce production costs. ​

(III) Stop operation: Stop operation safely and orderly​

1. Close equipment and valves in order: When it is necessary to stop the operation of the solvent extraction tower, the equipment and valves must be closed in a strict order to ensure the safety and orderliness of the shutdown process. First, gradually reduce the feed flow of the raw material liquid and solvent until the feed is stopped. By adjusting the speed of the feed pump or closing the feed valve, the feed flow rate can be gradually reduced. In the process of reducing the feed flow rate, pay close attention to the changes in parameters such as the liquid level and pressure in the tower to prevent abnormal conditions such as too high or too low liquid level and excessive pressure fluctuations. When the feed is completely stopped, continue to keep the liquid in the tower flowing for a period of time so that the residual materials in the tower can be discharged as much as possible. Then, close the discharge valve connected to the tower body to prevent the material from flowing back. When closing the discharge valve, pay attention to slow operation to avoid water hammer caused by the valve closing too quickly, which may damage the equipment. Next, stop the stirring device (if any) and related auxiliary equipment in the tower, such as pumps, heat exchangers, etc. When stopping these equipment, follow the operating procedures, turn off the power switch of the equipment first, and then close the inlet and outlet valves of the equipment. Finally, close the vent valve of the tower body to connect the tower to the atmosphere, so as to prepare for subsequent cleaning and maintenance work. ​

2. Cleaning and maintenance: After parking, comprehensive cleaning and maintenance of the solvent extraction tower is an important measure to ensure the long-term stable operation of the equipment. First, clean the tower to remove residual materials and dirt. According to the nature of the material and the degree of dirt, choose the appropriate cleaning method and cleaning agent. If the material is easily soluble in water, water flushing can be used; for some insoluble dirt, special cleaning agents can be used for cleaning. During the cleaning process, the spray device in the tower or manual flushing can be used to ensure that all parts of the tower can be fully cleaned. After the cleaning is completed, the cleaning liquid is discharged from the tower and properly disposed of to avoid pollution to the environment. After the cleaning is completed, the equipment is fully inspected and maintained. Check whether the tower body, packing layer, distributor, collector and other parts are damaged, deformed, corroded, etc. If there are any problems, repair or replace them in time. Inspect and maintain equipment such as pipelines, valves, pumps, replace worn parts, lubricate and debug valves to ensure that they are flexible and well sealed. Inspect and maintain the control system, calibrate sensors and instruments, and check the operation of automation devices to ensure their normal operation. In addition, the equipment should also be treated with anti-corrosion treatment, such as painting anti-corrosion paint, to extend the service life of the equipment. Through regular cleaning and maintenance, problems with the equipment can be discovered and solved in a timely manner to ensure that the equipment can operate normally the next time it is started.

V. Operational precautions that cannot be ignored

(I) Safety protection: protecting the life safety of operators

During the operation of the solvent extraction tower, safety protection is the primary task, which is directly related to the life safety and physical health of the operators. Since the extraction process involves various chemical substances, most of these substances are corrosive, irritating or toxic. Once in contact with the human body, they may cause serious damage to the skin, eyes, respiratory tract, etc. Therefore, operators must strictly follow safety regulations and wear complete personal protective equipment such as protective clothing, gloves, and goggles. ​

Protective clothing should be made of materials with good chemical corrosion resistance, such as acid and alkali resistant rubber, plastic or special fiber materials, to ensure that it can fully cover the body and prevent chemicals from penetrating into the skin. Gloves should also be corrosion-resistant and fit the hands to ensure that operators can flexibly perform various actions during operation, and at the same time, the hands will not be exposed to danger due to the fall or damage of gloves. Goggles should be able to effectively block liquid splashes and the invasion of particulate matter to protect the eyes from chemical damage. In some extraction operations that may produce toxic gases or vapors, operators also need to wear gas masks or respirators to ensure that the air they breathe is safe. ​

Take a chemical company as an example. During the operation of a solvent extraction tower, the operator did not wear goggles correctly. When adding solvent, the solvent accidentally splashed into the eyes, causing severe eye burns. This not only caused great pain to the operator, but also affected the normal production of the company. This painful lesson profoundly shows that safety protection measures are by no means optional, but a solid line of defense to protect the life safety of operators. They must be highly valued and strictly implemented. ​

(II) Avoid overheating and overpressure: prevent accidents ​

Overheating and overpressure are serious problems that may occur during the operation of solvent extraction towers. It is like a time bomb hidden inside the equipment. Once triggered, it is very likely to cause catastrophic accidents such as equipment damage, material leakage, and even explosion, causing huge property losses and casualties to the company.

The hazards of overheating are mainly reflected in many aspects. On the one hand, excessively high temperature may cause the volatilization of the extractant to intensify, thereby causing the pressure in the tower to rise sharply. On the other hand, high temperature may also trigger chemical reactions such as decomposition and polymerization of materials, generate a large amount of heat and gas, and further aggravate the situation of over-temperature and over-pressure. For example, in the extraction process of some organic compounds, if the temperature exceeds a certain limit, the organic compounds may decompose and produce flammable and explosive gases, increasing the risk of explosion. ​

Overpressure is also dangerous. Excessive pressure may cause excessive stress on equipment such as tower bodies, pipelines, and valves, causing equipment deformation and rupture, thereby causing material leakage. Once the material leaks, it will not only cause environmental pollution, but also may cause accidents such as fire and explosion. Moreover, overpressure may also affect the normal progress of the extraction process, reduce extraction efficiency and product quality. ​

In order to effectively prevent the occurrence of over-temperature and over-pressure accidents, enterprises usually take a series of scientific and effective measures. First of all, it is essential to install advanced temperature and pressure monitoring devices. These monitoring devices can monitor the temperature and pressure changes in the tower in real time and accurately, and transmit the data to the control system. The operator can understand the operating status of the tower at any time through the control system. Once the temperature or pressure is found to be close to or exceeds the set alarm value, the system will immediately issue an alarm. For example, when the temperature sensor detects that the temperature in the tower has risen to a level close to the alarm value, it will transmit a signal to the control system, which will trigger an audible and visual alarm to alert the operator.
​
Secondly, it is crucial to set reasonable alarm values ​​and interlocking control measures. The alarm value should be accurately set based on factors such as the design parameters of the equipment, the nature of the material, and the process requirements. When the temperature or pressure reaches the alarm value, the interlocking control device will automatically start and take appropriate measures to reduce the temperature or pressure. For example, when the pressure exceeds the set value, the interlocking control device will automatically open the safety valve to discharge part of the gas in the tower to reduce the pressure; or automatically adjust the flow rate of the cooling medium to cool the material in the tower. ​

In addition, regular maintenance and calibration of monitoring devices and safety accessories is also the key to ensuring their normal operation. Monitoring devices and safety accessories may fail or lose accuracy during long-term use, so they need to be inspected, repaired, and calibrated regularly. For example, safety valves need to be calibrated regularly to ensure that they can be opened accurately and promptly in case of overpressure to discharge excess pressure. Through the comprehensive implementation of these measures, the occurrence of over-temperature and over-pressure accidents can be effectively avoided, and the safe and stable operation of the solvent extraction tower can be guaranteed. ​

(III) Material compatibility: Ensure the correct selection of materials ​

In the operation of the solvent extraction tower, material compatibility is a key factor that cannot be ignored. It directly affects the extraction effect, equipment life and production safety. Different materials have their own unique chemical and physical properties. When they come into contact with the material of the equipment and the solvent used, various chemical reactions or physical changes may occur. These changes have a multi-faceted impact on the equipment. ​

From the perspective of chemical reaction, if the material reacts chemically with the material of the equipment, it may cause corrosion of the equipment. For example, when some acidic materials come into contact with metal equipment, acid etching reactions will occur, gradually corroding the surface of the equipment, making the wall thickness of the equipment thinner and the strength lower, which may eventually cause damage to the equipment. Even if the material does not react chemically with the material of the equipment, some impurities or additives in the material may have adverse effects on the equipment. For example, particulate impurities contained in the material may cause wear on the inner wall of the equipment when flowing inside the equipment, affecting the service life of the equipment. ​

The compatibility between the material and the solvent is also crucial. If the material and solvent are incompatible, it may lead to poor extraction effect. For example, when the selected solvent has a low solubility in the target material, the target material cannot be effectively extracted from the raw material, thereby reducing the extraction efficiency. In addition, incompatible materials and solvents may also cause stratification, emulsification and other phenomena, which not only affect the normal progress of the extraction process, but also may cause equipment blockage, operation difficulties and other problems. ​

In order to ensure material compatibility, multiple factors need to be considered when selecting materials and solvents. First, it is necessary to fully understand the chemical properties of the materials and solvents, including their acidity, alkalinity, oxidizing properties, and reducing properties. By analyzing these properties, it is possible to determine whether a chemical reaction may occur between them. Secondly, the physical properties of the materials and solvents, such as density, viscosity, boiling point, etc., should be considered. These properties will affect the flow state and mixing effect of the materials and solvents in the equipment, and thus affect the extraction efficiency. It is also necessary to refer to relevant experimental data and actual production experience. When selecting new materials and solvents, you can first conduct a small test experiment to observe their interaction under simulated production conditions and evaluate their compatibility.​

For example, in the solvent extraction process of a pharmaceutical company, although the solvent initially selected had a certain extraction capacity for the target drug component in theory, it was found in actual production that the solvent reacted chemically with certain impurities in the raw materials to generate insoluble precipitates, causing equipment blockage and production to be unable to proceed normally. Later, through re-screening and experiments on materials and solvents, a solvent with better compatibility was selected, which successfully solved this problem and ensured the smooth progress of production. Therefore, in the operation of the solvent extraction tower, the correct selection of materials and solvents and ensuring their compatibility are important prerequisites for achieving efficient and safe production.

VI. Key points of maintenance and cleaning

(I) Daily maintenance: keep the equipment in good condition

Daily maintenance is the cornerstone to ensure that the solvent extraction tower is always in the best operating state. It is like a dose of "vitality injection" injected into the equipment, which can timely discover and solve potential problems and effectively extend the service life of the equipment. Its main contents cover many key aspects such as connector inspection, component lubrication and operating parameter monitoring. ​

Every day, operators need to carefully check the connectors of the equipment, just like doctors perform physical examinations on patients, without missing any details. They will use professional tools such as wrenches to tighten bolts, nuts and other connectors to ensure that they are not loose. Because once the connector is loose, it may cause serious problems such as vibration and leakage during the operation of the equipment, which will not only affect the normal operation of the equipment, but also pose a threat to the safety of the operator. For example, during the operation of a solvent extraction tower in a chemical enterprise, due to the negligence of the operator, the bolts at the connection of a feed pipeline were not found to be loose in time. As a result, when the equipment was running, the pipeline suddenly leaked, and a large amount of chemical materials leaked out, which not only caused serious environmental pollution, but also led to the emergency shutdown of the production line, causing huge economic losses to the enterprise. ​

Regular lubrication of the lubricating parts of the equipment is also an indispensable and important part of daily maintenance. During the long-term operation, key parts such as bearings and seals in the equipment will wear due to friction, affecting the performance and service life of the equipment. Therefore, the operator needs to add appropriate lubricants to these parts regularly according to the operating instructions of the equipment. Lubricants are like "protective oil" for equipment, which can form a protective film on the surface of the parts, reduce friction and wear, and make the equipment run more smoothly. Generally speaking, some high-speed running parts, such as pump bearings, need to be lubricated every day; while some relatively low-speed running parts, such as the stirring shaft bearings in the tower, can be lubricated once a week. ​

During the operation of the equipment, it is also very important to closely monitor various operating parameters. Operators will use various sensors and instruments installed on the equipment, such as temperature sensors, pressure sensors, flow sensors, etc., to obtain the temperature, pressure, flow and other parameters of the equipment in real time, and compare these parameters with the normal operating range of the equipment. Once a parameter is found to deviate from the normal range, the operator will immediately take corresponding measures to adjust it. For example, if the temperature in the tower is found to be too high, it may be caused by a failure in the cooling system, abnormal feed temperature or reaction exothermicity. The operator will first check the cooling system to see if the flow of the cooling medium is normal and whether the cooler is blocked. If the feed temperature is abnormal, the raw material liquid or solvent will be cooled down. If the reaction exothermicity causes the temperature to rise, the feed flow rate can be appropriately adjusted or coolant can be added to control the temperature. By timely and accurate monitoring and adjustment of operating parameters, it can ensure that the equipment is always operating in a safe and stable state. ​

(II) Regular in-depth maintenance: comprehensive inspection and repair​

Regular in-depth maintenance is a comprehensive "physical examination" and "repair" of the solvent extraction tower. It can deeply explore potential problems inside the equipment and make timely and effective repairs to ensure that the performance of the equipment is always in the best condition. Generally speaking, it is recommended to perform regular deep maintenance every six months or one year. The specific time interval can be reasonably adjusted according to the frequency of use of the equipment, the working environment, and the requirements of the production process. ​

When performing regular deep maintenance, the equipment must first be disassembled and the internal components must be carefully inspected. This is like opening a precision instrument and carefully checking whether each part is working properly. The inspection includes whether the inner wall of the tower body has signs of corrosion and wear, whether the packing layer is damaged, blocked or lost, whether the distributor and collector can work properly, and whether the internal structure of various pipes, valves, pumps and other equipment is intact. Any damaged or worn parts found need to be repaired or replaced in time. For example, if local corrosion is found on the inner wall of the tower body, the corroded parts need to be polished, repaired, and repainted with anti-corrosion paint; if part of the packing in the packing layer is severely damaged, it will affect the mass transfer effect, and new packing needs to be replaced in time. ​

In addition to inspecting and repairing parts, the equipment also needs to be fully pressure tested. Pressure testing is like giving the equipment an "extreme challenge". By applying a certain amount of pressure inside the equipment, the pressure resistance and sealing of the equipment are tested. During the pressure test, it is necessary to strictly follow the relevant standards and specifications, gradually increase the pressure, and observe whether there are abnormal conditions such as leakage and deformation in various parts of the equipment. If it is found that the equipment has insufficient pressure resistance or poor sealing, it is necessary to find out the cause and carry out targeted repairs. For example, if the leakage is caused by aging of the gasket, a new gasket needs to be replaced; if there are cracks in the pipeline that cause insufficient pressure resistance, the pipeline needs to be welded or replaced. ​

It is also very important to evaluate the performance of the equipment regularly. Performance evaluation is like a "capacity test" for the equipment. By testing and analyzing the various performance indicators of the equipment, it is determined whether the equipment can meet the requirements of the production process. The indicators of performance evaluation include extraction efficiency, product purity, energy consumption, etc. By comparing with the design parameters and historical data of the equipment, it is evaluated whether the performance of the equipment has declined. If the extraction efficiency of the equipment is found to be reduced, it may be caused by the decline in the performance of the packing layer, uneven distribution of feed, or changes in solvent performance. In response to these problems, corresponding measures need to be taken for optimization and improvement, such as cleaning or replacing fillers, adjusting feed distributors or replacing suitable solvents, etc., to ensure that the equipment can continue to operate efficiently.
​
(III) Cleaning methods and processes: Removing dirt and impurities

With the long-term operation of the solvent extraction tower, various dirt and impurities will inevitably accumulate in the tower. These dirt and impurities are like "time bombs" inside the equipment, which will seriously affect the normal operation and extraction effect of the equipment. Therefore, it is very necessary to clean the equipment regularly, which can effectively remove the dirt and impurities in the tower, restore the performance of the equipment, and ensure the smooth progress of production. According to the nature and degree of dirt, different cleaning methods can be selected, and common ones are water washing and chemical cleaning.

1. Water washing: When the dirt in the tower is mainly some water-soluble impurities or lighter sediments, water washing is a simple and effective cleaning method. The process of water washing is relatively simple. First, the equipment needs to be shut down and the connection with other equipment needs to be cut off to ensure the safety of the cleaning operation. Then, inject an appropriate amount of clean water into the tower through the feed port of the equipment or the specially set cleaning liquid injection port. Clean water is like a clear stream that can gradually wash away the dirt and impurities in the tower. Start the equipment's circulation pump or a special cleaning pump to circulate clean water in the tower to better dissolve and remove dirt. During the circulation process, the speed and temperature of the water flow can be appropriately adjusted. Generally speaking, higher water flow speed and temperature can improve the cleaning effect. For example, controlling the water flow speed within a certain range can ensure the cleaning effect without causing excessive impact on the equipment; heating the water temperature to an appropriate temperature can enhance the solubility of dirt. After circulating for a period of time, open the drain valve and discharge the cleaning water containing dirt out of the tower. In order to ensure the cleaning effect, it is usually necessary to wash with water several times until the discharged cleaning water is clear and transparent. During the washing process, it is important to ensure that the cleaning water can fully cover all parts of the tower to avoid cleaning dead corners. At the same time, pay close attention to the drainage situation to prevent the drainage pipe from being blocked.
​
2. Chemical cleaning: For some insoluble dirt or deposits formed by chemical reactions with the surface of the equipment, water washing often cannot achieve the ideal cleaning effect. At this time, chemical cleaning methods are needed. Chemical cleaning uses the chemical reaction between chemical cleaning agents and dirt to dissolve, decompose or convert dirt into substances that are easily soluble in water, thereby achieving the purpose of cleaning. When selecting chemical cleaning agents, it is necessary to comprehensively consider factors such as the nature of the dirt, the material of the equipment, and environmental protection requirements. For example, for some metal oxide dirt, acidic cleaning agents such as hydrochloric acid and sulfuric acid can be selected; for some organic dirt, alkaline cleaning agents or organic solvents can be selected. However, it should be noted that acidic and alkaline cleaning agents are corrosive to a certain extent. During use, the concentration and cleaning time of the cleaning agent must be strictly controlled to avoid damage to the equipment. The process of chemical cleaning is relatively complicated. First, the equipment also needs to be shut down and safely isolated. Then, the prepared chemical cleaning agent is injected into the tower through the injection port to control the amount and concentration of the cleaning agent to ensure the cleaning effect. Start the circulation pump to make the cleaning agent circulate in the tower, fully contact and react with the dirt. During the circulation process, the temperature and flow rate of the cleaning agent can be adjusted as needed to enhance the cleaning effect. For example, for some dirt with a slow reaction speed, the temperature of the cleaning agent can be appropriately increased to speed up the reaction speed. After a certain period of cleaning, stop the circulation pump and discharge the cleaning agent out of the tower. In order to completely remove the residual cleaning agent, water washing is also required. The steps of water washing are the same as the above-mentioned water washing method. Usually, multiple water washings are required until the pH value of the discharged water is close to neutral. Safety issues are particularly important during chemical cleaning. Operators must wear personal protective equipment such as protective clothing, gloves, and goggles to avoid contact between skin and eyes with chemical cleaning agents. At the same time, ensure that the cleaning site is well ventilated to prevent harmful gases generated by the volatilization of chemical cleaning agents from causing harm to the human body. After cleaning, the cleaning waste liquid should be properly handled, and neutralization, precipitation, filtration and other operations should be carried out in accordance with environmental protection requirements to ensure that it meets the emission standards before discharge.

VII. Wide application fields of solvent extraction towers

(I) Chemical production: a powerful assistant for organic synthesis

In the vast field of chemical production, the solvent extraction tower is like a powerful "chemical craftsman" and plays an indispensable and key role. Especially in the field of organic synthesis, it has become a powerful assistant for improving product purity and production efficiency. ​

Take the production of fine chemical product dibutyl phthalate (DBP) as an example. During its synthesis process, a complex mixture is produced, which includes unreacted raw materials, reaction by-products and the target product DBP. Traditional separation methods often find it difficult to separate these components efficiently, resulting in low product purity and low production efficiency. The application of solvent extraction towers has completely changed this situation. ​

In the production process of DBP, a suitable organic solvent is selected as the extractant, and the reaction mixture is introduced into the solvent extraction tower. Due to the significant difference in the solubility of DBP and other impurities in the organic solvent, DBP will quickly transfer to the organic solvent phase in the extraction tower, while the unreacted raw materials and most impurities remain in the other phase. In this way, DBP can be separated from impurities quickly and efficiently, greatly improving the purity of the product. According to relevant data, after separation using a solvent extraction tower, the purity of DBP can be increased from about 85% of the traditional method to more than 98%. ​

From the perspective of production efficiency, the continuous operation characteristics of the solvent extraction tower enable it to achieve large-scale industrial production. In the traditional intermittent separation process, each batch of separation requires multiple steps such as feeding, reaction, separation, and discharging, which is cumbersome and time-consuming. The solvent extraction tower can realize the continuous feeding and discharging of raw material liquid and solvent, greatly shortening the production cycle. Take a chemical company as an example. Before the use of the solvent extraction tower, the company's monthly production of DBP was only 500 tons, and the production cycle was 10 days; after the use of the solvent extraction tower, the monthly output quickly increased to 800 tons, the production cycle was shortened to 7 days, and the production efficiency was significantly improved.​

In addition to the production of DBP, the solvent extraction tower has demonstrated excellent performance in the production process of many organic synthetic products, such as organic pigments, fragrances, and pharmaceutical intermediates. It can effectively remove impurities in the product, improve the purity and quality stability of the product, and meet the market demand for high-quality chemical products. At the same time, its efficient separation ability and continuous production characteristics also reduce production costs for chemical companies and improve market competitiveness. ​

(II) Wastewater treatment: a weapon for purifying water resources​

With the acceleration of industrialization, the discharge of industrial wastewater has posed an increasingly serious threat to the environment. These wastewaters often contain a large amount of heavy metal ions, organic matter and other pollutants. If they are directly discharged without effective treatment, they will cause great harm to the water ecosystem, soil quality and human health. In this battle against water pollution, the solvent extraction tower has become a powerful weapon for purifying water resources with its unique separation technology, playing a vital role in the field of wastewater treatment.​

In terms of heavy metal wastewater treatment, taking copper-containing wastewater as an example, copper ions are a common heavy metal pollutant with high toxicity, which is seriously harmful to aquatic organisms and human health. Using a solvent extraction tower, a suitable extractant, such as an oxime extractant, can be selected to selectively extract copper ions from copper-containing wastewater. In the extraction tower, copper ions react with the extractant to form a stable complex, which is transferred from the aqueous phase to the organic phase. In this way, the concentration of copper ions in the wastewater can be effectively reduced to meet the discharge standard. After treatment with a solvent extraction tower, the concentration of copper ions in copper-containing wastewater can be reduced from hundreds of milligrams per liter to less than a few milligrams per liter, with a removal rate of more than 99%. ​

For wastewater containing organic matter, the solvent extraction tower also performs well. For example, wastewater generated in the petrochemical industry often contains a large amount of organic matter such as phenols and aromatic hydrocarbons. These organic matter are not only toxic, but also difficult to biodegrade, which will cause long-term pollution to the water body. By using a solvent extraction tower and selecting a suitable organic solvent, such as methyl isobutyl ketone (MIBK), organic matter in wastewater can be extracted. During the extraction process, the solubility of organic matter in organic solvents is much greater than that in water, thereby realizing the transfer of organic matter from aqueous phase to organic phase. Through the treatment of the solvent extraction tower, the content of organic matter in wastewater can be greatly reduced, creating favorable conditions for subsequent biological treatment or deep treatment.

From an environmental protection perspective, the application of solvent extraction towers in wastewater treatment is of great significance. It can effectively remove pollutants in wastewater, reduce pollution to the environment, and protect the safety of water resources. At the same time, through the recovery and recycling of the extractant, resource conservation and recycling can also be achieved, which is in line with the concept of sustainable development. In addition, the application of solvent extraction towers can also reduce the cost of wastewater treatment, improve treatment efficiency, and reduce environmental pressure for enterprises. For example, after a chemical company used a solvent extraction tower to treat wastewater, the annual wastewater treatment cost was reduced by 30%, and the risk of fines due to excessive wastewater discharge was reduced.​

(III) Drug synthesis: ensuring drug quality​

In the precise world of drug synthesis, the purity and safety of drugs are crucial core elements, which are directly related to the life, health and treatment effect of patients. As a key equipment in the drug purification process, the solvent extraction tower is like a rigorous "quality guardian" and plays a pivotal role. ​

Take the production of antibiotic penicillin as an example. During the fermentation process of penicillin, a complex fermentation broth is produced, which contains not only the target product penicillin, but also a large number of impurities, such as proteins, polysaccharides, pigments and unreacted culture medium components. The presence of these impurities not only affects the purity and stability of penicillin, but also may cause adverse reactions such as allergic reactions, posing a threat to the health of patients. Using a solvent extraction tower and selecting a suitable extractant, such as butyl acetate, penicillin can be effectively extracted from the fermentation broth. In the extraction tower, the solubility of penicillin in butyl acetate is much greater than that in the aqueous phase. By controlling the appropriate extraction conditions, penicillin is quickly transferred from the aqueous phase to the butyl acetate phase, while most of the impurities remain in the aqueous phase. After multiple extraction and back extraction processes, the purity of penicillin can be increased to more than 95%, meeting the requirements of drug quality standards. ​

In the process of drug synthesis, the purification of some intermediates is also inseparable from the help of solvent extraction towers. For example, in the process of synthesizing the anticancer drug paclitaxel, the purity of the intermediate has an important impact on the quality and efficacy of the final product. Through the solvent extraction tower, the use of a suitable extraction system, such as the chloroform-methanol system, can effectively remove impurities in the intermediate and improve the purity of the intermediate, thereby providing high-quality raw materials for subsequent synthesis reactions and ensuring the quality and efficacy of the final product. ​

From the perspective of drug quality and safety, the application of solvent extraction towers in drug purification is of irreplaceable importance. It can accurately remove impurities in drugs, improve the purity of drugs, reduce the risk of adverse drug reactions, and ensure the safety of patients' medication. At the same time, its efficient separation ability and stable operating performance also provide reliable technical support for the large-scale production of drugs, ensuring that the supply of drugs can meet clinical needs. For example, after a pharmaceutical company adopted a solvent extraction tower to purify drugs, the quality stability of the drugs was significantly improved, and the product qualification rate was increased from the original 80% to more than 95%, greatly enhancing the company's market competitiveness.

VIII. Looking to the future: Development trend of solvent extraction towers

(I) Intelligent upgrade: more accurate and efficient control

At a time when science and technology are developing rapidly, intelligent technology is penetrating into various industrial fields at an unprecedented speed, and solvent extraction towers are no exception. In the future, solvent extraction towers will take a big step towards intelligence. By introducing artificial intelligence and big data technologies, intelligent control and fault prediction of equipment can be realized, thereby further improving their operating efficiency and stability.

Artificial intelligence technology can deeply analyze and learn the operating data of solvent extraction towers and establish accurate mathematical models to optimize the operating parameters of equipment. For example, using machine learning algorithms, real-time monitoring and analysis of parameters such as temperature, pressure, flow, and liquid level in the extraction process can be performed. According to different working conditions and raw material characteristics, key parameters such as feed rate, solvent dosage, and extraction time can be automatically adjusted to keep the extraction process in the best state. This can not only improve extraction efficiency and product quality, but also effectively reduce energy consumption and production costs.

Big data technology provides strong data support for the intelligent control of solvent extraction towers. By collecting and integrating a large amount of production data, including equipment operation data, product quality data, raw material characteristic data, etc., using big data analysis technology to explore the laws and trends behind the data, a scientific basis is provided for the optimization control and fault prediction of the equipment. For example, by analyzing historical data, the optimal extraction conditions of different raw materials under different working conditions are predicted, and the equipment parameters are adjusted in advance to avoid poor extraction effects or equipment failures caused by improper parameters. ​

Fault prediction is one of the important applications of intelligent upgrading. With the help of artificial intelligence and big data technology, the equipment status of the solvent extraction tower can be monitored and evaluated in real time, potential failure risks can be predicted in advance, and early warning signals can be issued in time so that operators can take corresponding measures for prevention and maintenance. For example, by analyzing the vibration, noise, temperature and other data of the equipment, it can be judged whether the equipment has abnormal wear, looseness, overheating and other problems, predict the remaining service life of the equipment, arrange maintenance plans in advance, and avoid the impact of sudden equipment failures on production. ​

Intelligent upgrading will also realize remote monitoring and operation of solvent extraction towers. Operators can monitor and remotely operate the equipment in real time and remotely through the Internet at any place with network connection, realizing unattended and intelligent management of the production process. This not only improves the convenience and flexibility of operation, but also reduces the workload and safety risks of operators. ​

(II) Application of new materials: improving performance and lifespan​

With the continuous advancement of materials science, the research and development and application of new materials have brought new opportunities for improving the performance and extending the lifespan of solvent extraction towers. In the future, more new materials with excellent performance will be used in the manufacture of solvent extraction towers, thereby significantly improving the performance of the equipment and improving its adaptability and reliability under complex working conditions. ​

In terms of corrosion resistance, new corrosion-resistant materials will become an ideal choice for solvent extraction towers. For example, some high-performance alloy materials, such as nickel-based alloys and titanium alloys, have excellent acid and alkali resistance, oxidation resistance and chemical corrosion resistance, and can operate stably for a long time in extreme chemical environments. These alloy materials can not only resist the erosion of various chemical substances, but also maintain good mechanical properties and processing properties, providing more reliable guarantees for the application of solvent extraction towers in chemical industry, environmental protection and other fields. In addition, some new polymer materials, such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), also have excellent chemical stability and corrosion resistance. They can be used to manufacture seals, pipes, packings and other components in the tower, effectively improving the corrosion resistance of the equipment. ​

Higher strength materials can enhance the structural stability and load-bearing capacity of the solvent extraction tower. In some large solvent extraction towers, high-strength steel or composite materials are used to manufacture the tower body, which can withstand greater pressure and weight, ensuring the safety and reliability of the equipment under high-load operating conditions. At the same time, high-strength materials can also reduce the wall thickness of the tower body and reduce the weight of the equipment, thereby saving material costs and manufacturing costs. For example, carbon fiber reinforced composite materials have the advantages of light weight, high strength, and high modulus. Applying them to the manufacture of solvent extraction towers can greatly reduce the weight of the equipment while ensuring the performance of the equipment, and improve the convenience of transportation and installation of the equipment.

In addition to corrosion resistance and strength, new materials may also have other excellent properties, such as good thermal conductivity, wear resistance, and anti-fouling properties. These performance characteristics will help further improve the performance of solvent extraction towers. For example, materials with good thermal conductivity can improve the heat transfer efficiency in the tower and accelerate the heat transfer during the extraction process, thereby improving the extraction efficiency; materials with good wear resistance can reduce the wear of equipment components and extend the service life of the equipment; materials with strong anti-fouling properties can reduce the adhesion of dirt in the tower and reduce the frequency and cost of cleaning and maintenance. ​

(III) Green and environmental protection direction: the demand for sustainable development ​

Under the background of the global active advocacy of sustainable development, green and environmental protection has become an inevitable trend in the development of solvent extraction towers. In the future, solvent extraction towers will pay more attention to energy conservation and emission reduction and reduce pollutant emissions to adapt to increasingly stringent environmental protection requirements and contribute to the realization of green industrial production. ​

Reducing energy consumption is one of the key goals of the green and environmental development of solvent extraction towers. By optimizing the equipment structure and process flow, the operating efficiency of the equipment can be improved and energy consumption can be reduced. For example, by using efficient mass transfer elements and tower internals to enhance the mass transfer effect between the two phases, the height and diameter of the tower can be reduced under the same extraction requirements, thereby reducing the energy consumption of the equipment. At the same time, using advanced heat integration technology, the waste heat in the extraction process is recovered and utilized, and it is used to preheat the raw material liquid or other process links to improve energy utilization. Some new solvent extraction towers also use variable frequency speed regulation technology to automatically adjust the operating parameters of the equipment according to changes in production load to avoid energy waste. ​

Reducing pollutant emissions is also an important task for the green development of solvent extraction towers. During the extraction process, minimize the volatilization and leakage of organic solvents to reduce environmental pollution. Use equipment and pipelines with good sealing properties, equipped with advanced waste gas treatment systems, to recycle and purify volatile organic solvents. At the same time, develop and apply green, non-toxic, and renewable extractants to replace traditional toxic and harmful extractants to reduce the generation of pollutants from the source. For example, ionic liquids, as a new type of green extractant, have the advantages of extremely low vapor pressure, good chemical stability, and strong designability. In some fields, they have begun to gradually replace traditional organic solvents. ​

Solvent recovery and recycling are also important measures to achieve green environmental protection. By optimizing the solvent recovery process, the recovery rate of solvents can be improved, the use of fresh solvents can be reduced, and production costs and environmental pollution can be reduced. Advanced distillation, adsorption, membrane separation and other technologies are used to efficiently recover and purify the used solvents so that they can be used again in the extraction process. Some companies have also established a closed-loop system for solvent recycling, achieving zero emission and sustainable use of solvents. ​

The development of green environmental protection also requires strengthening the environmental impact assessment and monitoring of solvent extraction towers. Establish a complete environmental monitoring system to monitor the pollutant emissions during equipment operation in real time, and promptly discover and solve environmental problems. At the same time, strengthen the environmental impact assessment of the life cycle of solvent extraction towers, from the design, manufacture, use to scrapping of equipment, comprehensively consider its impact on the environment, and take corresponding measures to reduce negative impacts.

IX. Summary and Review

As a key equipment in the field of industrial separation, the solvent extraction tower plays an irreplaceable and important role in many fields such as chemical industry, pharmaceutical industry, food industry, environmental protection, etc. with its unique working principle based on the difference of solubility and distribution coefficient. Its significant advantages, such as high efficiency, low energy consumption, cost-effectiveness and easy control, make it a powerful assistant for improving efficiency, reducing costs, ensuring product quality and achieving environmental protection goals in modern industrial production. ​

During the operation process, strictly following the standardized operating guidelines and precautions, doing a good job of safety protection, avoiding over-temperature and over-pressure, and ensuring material compatibility are the key to ensuring the safe and stable operation of the equipment and achieving good extraction effects. At the same time, paying attention to daily maintenance, regular deep maintenance and scientific and reasonable cleaning can effectively extend the service life of the equipment and ensure that the equipment is always in the best operating state. ​

With the continuous advancement of science and technology, the solvent extraction tower is booming in the direction of intelligent upgrading, new material application and green environmental protection. The introduction of intelligent technology will make its operation more accurate and efficient, the application of new materials will improve its performance and life, and the development trend of green environmental protection will make it more in line with the needs of sustainable development.​

Looking to the future, the importance of solvent extraction towers in the industrial field will become increasingly prominent, and their application scope will continue to expand. We have reason to believe that driven by technological innovation, solvent extraction towers will continue to improve and develop, and make greater contributions to the efficient, green and sustainable development of industrial production.