Evaporation and Crystallization

Imagine this: your production line suddenly slows down, energy bills spike, and product quality plummets. The culprit? A clogged evaporator. This is not just an inconvenience; it's a significant threat to your efficiency, product consistency, and profitability. If left unchecked, a clogged evaporator can lead to extended downtime, costly repairs, and substantial financial losses. The frustration and stress of frequent breakdowns can be overwhelming, but there's a way to address this issue head-on. Signs of a Clogged Evaporator Recognizing the symptoms of a clogged or fouled shell and tube evaporator early can save you time and money. Here are the key indicators: 1. Decreased Evaporation Rate: When your evaporator is clogged, the flow of feed liquid over the heat transfer surfaces is restricted. This reduction in flow rate directly impacts the overall evaporation rate and throughput of the system. If you notice a decline in your evaporator's performance, it might be due to clogging. 2. Increased Pressure Drop: As fouling builds up on the tube surfaces, it creates flow restrictions, leading to an abnormal increase in pressure drop across the evaporator. Monitoring the pressure differential can help identify this issue. 3. Poor Heat Transfer: Fouling deposits act as an insulating layer, reducing heat transfer efficiency. This can be detected by uneven temperature distribution or localized hot spots on the evaporator surface. Reduced heat transfer can significantly affect the efficiency of your process. 4. Frequent Cleaning Required: If you find yourself needing to perform chemical cleaning cycles more frequently, such as acid cleaning, to maintain performance, it is a clear sign of fouling buildup. This indicates that your evaporator is not functioning optimally and requires more attention. 5. Visible Scaling/Fouling: If you can visually inspect the evaporator tubes and the shell side, look for the buildup of scales, precipitates, or fouling deposits. Visible signs of scaling are a direct indicator of clogging and fouling. 6. Inconsistent Product Quality: Clogging can lead to uneven liquid distribution and heating, resulting in inconsistent concentration or quality of the evaporated product. Variations in product quality are a significant red flag indicating problems within the evaporator. 7. Increased Energy Consumption: As fouling increases, more energy is required to compensate for the poor heat transfer, leading to higher utility costs. If you notice a sudden increase in energy consumption without a corresponding increase in production, it could be due to a clogged evaporator. Regular monitoring of key performance parameters like flow rates, temperatures, pressures, and energy consumption is crucial for early detection of evaporator clogging. Implementing a preventive maintenance schedule based on the nature of the feed stream can help mitigate fouling issues and keep your evaporator running efficiently. Understanding the symptoms of a clogged evaporator is just the beginning. To maintain optimal performance and avoid costly downtime, it's essential to know how your evaporator works and how to clean it effectively. By delving deeper into the operation and maintenance of shell and tube evaporators, you can ensure your equipment remains in top condition, providing reliable and efficient service. How Does a Shell and Tube Type Evaporator Work? A shell and tube type evaporator is a specific configuration of a shell and tube heat exchanger used for evaporation processes. Here's a detailed look at how it works: Basic Structure1. Tube Bundle: The evaporator consists of a bundle of tubes enclosed within a cylindrical shell.2. Fluid Flow: The fluid to be evaporated (feed liquid) flows through the tubes, while the heating medium (steam, hot fluid, etc.) flows over the outer surface of the tubes within the shell. Flow Arrangement1. Feed Liquid Entry: The feed liquid enters the tube bundle through an inlet nozzle in the tube sheet at one end.2. Flow Through Tubes: The feed liquid flows through the tubes, where it is heated and partially/fully evaporates.3. Exit of Vapor and Liquid: The vapor and any remaining liquid exit through an outlet nozzle at the other end of the tube bundle.4. Heating Medium Flow: The heating medium enters the shell through an inlet nozzle, flows across the tube bundle in a specific pattern aided by baffles, and exits through an outlet nozzle. Heat Transfer Process1. Heat Transfer: Heat is transferred from the hot heating medium to the cooler feed liquid through the tube walls.2. Evaporation: As the feed liquid flows through the tubes, it absorbs heat, causing a portion of it to vaporize (evaporate).3. Evaporation Factors: The degree of evaporation depends on factors like the heat transfer area, flow rates, and temperature differences. Multi-Pass Design1. Efficiency Improvement: To increase heat transfer efficiency, the tube bundle can be designed for multiple passes, where the fluid makes multiple passes through different sections of the tube bundle.2. Heat Transfer Length: This increases the effective heat transfer length and improves evaporation rates. Baffles and Tube Arrangements1. Flow Direction: Baffles are installed in the shell to direct the flow of the heating medium across the tube bundle and induce turbulence, enhancing heat transfer.2. Tube Patterns: Tube arrangements like triangular or rotated square patterns are used to optimize heat transfer and fluid flow.Shell and tube evaporators are widely used in various industries, such as chemical processing, lithium extraction, food and beverage, pharmaceutical, and desalination plants, for concentrating or evaporating liquids. Their design can be customized based on the specific process requirements, heat transfer rates, and desired evaporation rates. How Do You Clean a Shell and Tube Evaporator? Cleaning a shell and tube evaporator is essential to maintain its efficiency and longevity. Here are the typical methods used to clean these evaporators: Mechanical Cleaning1. Tube Lancing/Rodding: A rodding machine is used to clean the evaporator tubes by propelling flexible lances or rods at high pressure (up to 10,000 psi) to dislodge fouling and deposits from the inside of the tubes.2. Tube Brushing/Drilling: Mechanical brushes or drilling tools can be inserted into the tubes to scrape off and remove hard deposits. Chemical CleaningA closed-loop chemical cleaning system is used to circulate chemical solutions (acidic or alkaline) through the evaporator to dissolve and remove scales, fouling, oil/grease deposits. The steps typically involve: 1. Preparation: Isolating and preparing the evaporator by removing covers/heads.2. Chemical Circulation: Circulating the heated chemical solution through the tube side and shell side using pumps.3. Solution Monitoring: Monitoring solution strength and replenishing/adjusting as needed.4. Rinsing: Rinsing with clean water to remove chemical residues. Water JettingHigh-pressure water jetting (up to 2500 bar or 36,000 psi) can be used to blast away fouling from the inside of the tubes using flexible lances or rigid lances mounted on tube lancing equipment (TLE). The key steps include: Isolation: Shutting down and isolating the evaporator.Access: Removing heads/covers to access the tube bundle.Jetting: Deploying high-pressure water jetting lances into the tubes.Waste Management: Collecting and treating the wastewater generated.Regular cleaning intervals (e.g., every 3 years for evaporators) are recommended to maintain efficiency and prevent excessive fouling buildup. Proper planning for downtime, safety precautions, and waste handling is crucial for effective evaporator cleaning. ConclusionMaintaining your evaporator in peak condition is essential for ensuring efficient operation, consistent product quality, and cost-effective production. By understanding the signs of clogging, the working principles of shell and tube evaporators, and effective cleaning methods, you can prevent downtime and extend the life of your equipment. Regular monitoring and preventive maintenance are your best allies in keeping your evaporator running smoothly and your production line efficient. Remember, a proactive approach to maintenance can save you from significant headaches and expenses down the line.

Recently，Myande signed a contract with Jiangxi H-zone Lithium Industry Co., Ltd, under which Myande will supply a 25TPH three-effect evaporation & crystallization system for the treatment of salt-containing effluent. The system will adopt advanced evaporation and crystallization separation technology to treat the wastewater containing sodium sulfate, potassium sulfate and salt during the production process of the lithium industry. It will also crystallize the salt from wastewater and recycle the condensation water generated in the evaporation system. The completion of the project will enable Jiangxi H-zone Lithium Industry Co system to improve its environmental performance, save energy, and thus effectively reduce its operational cost.   H-zone Lithium is a high-tech enterprise engaged in the production of lithium products by lepidolite, such as battery grade Li2CO3, technical development and large-scale production of potassium, rubidium and cesium salt products. The company has been committed to the process development of lithium. With the rapid development of the company, wastewater containing a lot of salt is increasing in the production process and it’s difficult to treat the wastewater.   Myande has a mature design system and rich project experience in multi-effect evaporation crystallization technology. According to the characteristics of wastewater of lithium industry, combined with the past engineering data, Myande designing team came up with a highly individualized solution which nicely meets with H-zone Lithium’s requirements of actual production as well as its expectation for automatic mode of operation.

The lithium industry has been experiencing rapid growth over the past decade, driven by the increasing demand for lithium-ion batteries used in electric vehicles, energy storage systems, and other high-tech applications. As of early 2023, the lithium industry is still not recovered from the pandemic, with some supply chain disruptions and production delays still affecting the market. However, overall demand for lithium is expected to continue growing, driven by the ongoing transition to electric vehicles and renewable energy sources. However, do you know where all that lithium comes from and how it’s produced? In this article, we will take a look at some typical lithium production paths and how they compare.   What is lithium extraction? Lithium extraction refers to the process of obtaining lithium from its sources, which can be ores or brines. There are several methods for extracting lithium, depending on the source and the specific minerals present.   What are the paths to lithium extraction? There are several paths to lithium extraction, each with its own advantages and disadvantages. The most common methods of lithium extraction are:   1. Mining: Lithium can be mined from hard rock deposits, known as spodumene, using traditional underground or open-pit mining methods. Lithium extraction from hard rock, such as spodumene, typically involves a combination of crushing, grinding, roasting, leaching, purification, precipitation, drying and packaging. Lithium extraction from hard rock is typically more expensive and energy-intensive than brine extraction, but it can also yield higher-quality lithium. Spodumene is one of the most common sources of hard rock lithium, but other minerals such as petalite and lepidolite can also be used.   2. Brine Extraction: Lithium can also be obtained from brine deposits, which are underground reservoirs of salty water that contain dissolved lithium. Brine is typically pumped to the surface and allowed to evaporate in large ponds, leaving behind lithium salts that can be further processed. Brine extraction is generally less expensive than mining, but it can be slower and yield lower-quality lithium. In some cases, reverse osmosis (RO) is used to concentrate the lithium brine to speed up the evaporation process.   3. Geothermal Brine Extraction: Geothermal brine extraction is a variation of brine extraction that involves using hot water from geothermal wells to dissolve and extract lithium from underground brines. This method can be more sustainable and environmentally friendly than traditional brine extraction, but it is still in the experimental stages and is not yet widely used.   4. Lithium Clay Extraction: Lithium can also be obtained from clay deposits, which are mined using conventional open-pit mining methods. The clay is then leached with sulfuric acid to extract the lithium. This method can be less expensive than traditional mining, but it can also yield lower-quality lithium.   Each method of lithium extraction has its own set of advantages and disadvantages, and the choice of method will depend on factors such as the quality and quantity of the lithium source, environmental regulations, and economic considerations. As the demand for lithium continues to grow, there is ongoing research and development into new and more efficient methods of lithium extraction.   What are the trends in lithium extraction industry? In terms of future trends, several key developments are likely to shape the lithium extraction industry in the coming years:   1. Expansion of Production Capacity: As demand for lithium continues to grow, lithium producers are expanding their production capacity to meet this demand. This has led to the development of new lithium mines and processing facilities, particularly in countries with large lithium reserves such as Australia, Chile, and Argentina.   2. Diversification of supply: As demand for lithium grows, there is likely to be an increased focus on diversifying the sources of lithium production. Currently, the majority of lithium comes from just a few countries, including Australia, Chile, and Argentina. However, new sources of lithium, such as brine deposits in Nevada and clay deposits in Mexico, are being developed.   3. Technological advancements: Advances in battery technology, such as the development of solid-state batteries, could change the demand dynamics for lithium and other materials used in battery production. In addition, improvements in lithium extraction and processing techniques could help to reduce the environmental impact of lithium mining and production. Also the use of new membrane technologies and ion exchange resins will reduce the environmental impact of brine extraction.   4. Policy changes: Government policies, such as subsidies for electric vehicles and incentives for renewable energy development, are likely to continue to drive demand for lithium. However, there could also be regulatory changes aimed at reducing the environmental impact of lithium mining and production, which could increase costs for producers and affect the supply chain.   Overall, the lithium industry is likely to continue to experience strong growth in the coming years, driven by the ongoing transition to electric vehicles and renewable energy sources. However, the industry will need to navigate challenges such as supply chain disruptions, environmental concerns, and changing technology and policy landscapes in order to sustain this growth.   Myande offers a variety of technologies for major upstream and midstream lithium extraction processes, including evaporation concentration, crystallization, purification separation and drying. Myande processes provide its customers with a competitive advantage, achieving higher productivity under tighter specifications while reducing costs and increasing efficiency. And all of plants meet the complex safety requirements of the chemical industry.

Recently, Myande signed a contract with Cathay Industrial Biotech, by which Myande will supply Cathay with an MVR evaporation and crystallization facility to process wastewater and extract sodium sulfate as a value-adding by-product from the wastewater. This evaporation & crystallization facility to be supplied by Myande will enable Cathay to utilize wastewater and create economic benefit in an environmentally-friendly manner.   Cathay Industrial Biotech is a world-leading industrial biotechnology company specialized in the production of chemical intermediate long-chain dibasic acid for the synthesis of nylon, polyester, adhesive and bio-solvent. Long chain dibasic acid, a linear aliphatic dibasic acid containing 10 to 15 carbon atoms, is produced by a bio-fermentation method in which a large amount of high-salt wastewater is normally generated. It is difficult to process the wastewater because of the high concentration of pollution and poor biodegradation.   The technical solution to be supplied by Myande including MVR evaporation and concentration, frozen crystallization and fluid bed drying technology will be applied to process wastewater for recycling industrial sodium sulfate.