Product Introduction

　　 Draft Tube Crystallizer (also known as DTB Crystallizer, Draft Tube Baffle Crystallizer) It is a highly efficient suspension crystallization device based on the principle of “built-in guide cylinder + baffle-induced forced internal circulation.” At its core, it features a combined structure of a “guide cylinder and baffles,” which, driven by a stirrer, creates a stable axial flow within the crystallization chamber, ensuring that crystals remain uniformly suspended at all times and grow slowly under controllable levels of supersaturation. The device’s key advantages—high internal circulation efficiency, uniform crystal suspension, compact structure, and ease of operation—make it widely applicable to medium- and small-scale crystallization processes in industries such as chemical engineering, fine chemicals, pharmaceuticals, and food processing. It is particularly well-suited for producing products requiring uniform crystal particle size and regular crystal morphology. Based on the characteristics of the feed material (such as solubility, viscosity, and thermal sensitivity) and production capacity requirements (ranging from 0.1 t/h to 50 t/h), the device can be customized with specific stirring speeds, guide cylinder dimensions, and crystallization parameters to accommodate either batch or continuous production modes.

Product Category

　　According to the operating mode, stirring method, and application scenario, the flow-guiding cylinder crystallizer is mainly divided into the following categories:

　　1. Classified by operation mode

　 　▪ Batch-type guide-tube crystallizer: Single-batch operation for feeding—crystallization—discharge, with precise temperature control and a stable crystallization environment, suitable for crystallizing small-batch, multi-variety materials (such as pharmaceutical intermediates and fine chemical products). Single-reactor volume ranges from 0.1 m³ to 10 m³.

　　 ▪ Continuous-flow guide tube crystallizer: The entire process—feed addition, crystallization, and discharge—is continuous. Stable internal circulation ensures uniform crystal growth, with production capacity fluctuations no greater than 3%. This system is suitable for medium-scale industrial production (e.g., in the food additives and fertilizer industries), with a capacity ranging from 1 ton/hour to 50 tons/hour.

　 　▪ Semi-continuous flow-through crystallizer: The crystallization process is carried out in a continuous cycle, with intermittent feeding and discharging operations, balancing flexibility and stability, and well-suited for medium-scale production of products with multiple specifications.

　 　2. Classified by mixing method

　　 ▪ Propeller-type guide tube crystallizer: Equipped with a propeller agitator, it promotes axial circulation of the slurry, offering high circulation efficiency and suitable for low-viscosity materials (<300 mPa·s) with excellent uniformity in crystal suspension.

　 　▪ Turbine-type guide cylinder crystallizer: The turbine agitator generates a combined radial and axial flow with moderate shear force, making it suitable for medium- to high-viscosity fluids (300–1000 mPa·s) or liquid formulations containing small amounts of suspended solids, thereby preventing crystal aggregation.

　　 ▪ Anchor-type + flow-directing cylinder combined crystallizer: The anchor-type agitator, paired with a flow guide cylinder, combines circulation and wall-scraping functions. It is ideal for materials that are prone to scaling and have high viscosity, preventing crystals from adhering to the vessel walls.

　 　3. Classified by Crystallization Process

　　 ▪ Cooling-type guide tube crystallizer: The liquid feed is cooled via a jacket or built-in coil, reducing its solubility and creating supersaturation. This method is particularly suitable for materials whose solubility varies significantly with temperature (such as potassium nitrate, citric acid, and lactic acid).

　　 ▪ Evaporative Deflector Crystallizer: When used with an external heater, the solution is concentrated by evaporation to achieve supersaturation, making it suitable for materials whose solubility changes gradually with temperature (such as sodium chloride, sodium sulfate, and ammonium chloride).

　　 ▪ Vacuum-cooled guide-tube crystallizer: Achieves self-evaporation and cooling of the feed liquid in a vacuum environment, with low operating temperatures (40–70℃), making it suitable for heat-sensitive materials such as enzyme preparations, biological extracts, and pharmaceutical raw materials.

　　 ▪ Reactive flow-guide crystallizer: Integrating chemical reactions with crystallization processes, the method achieves immediate crystallization of reaction products—such as calcium carbonate, barium carbonate, and aluminum hydroxide—by precisely controlling the reaction pH, temperature, and circulation conditions.

Performance Features

　　 1. High internal circulation efficiency: The optimized design of the flow guide cylinder and baffle minimizes the resistance to material liquid circulation, enabling a circulation velocity of 0.5–2 m/s. This ensures excellent uniformity of crystal suspension (suspension rate ≥95%), eliminates dead zones, and prevents excessive local supersaturation that could lead to an overabundance of fine crystals.

　 　2. Excellent crystal quality: The supersaturation is precisely controlled, ensuring a stable crystal growth rate (0.1–0.6 mm/h). The product exhibits uniform particle size (CV value ≤ 22%) and well-defined crystal morphology (such as cubic or needle-shaped crystals), with excellent flowability, making subsequent drying and packaging convenient.

　 　3. Compact structure with a small footprint: The integrated design of the built-in flow guide cylinder and agitator eliminates the need for external circulation pumps and heat exchangers (whether batch or small-scale continuous), reducing the footprint to just 1/2 to 2/3 of that required by conventional forced-circulation crystallizers with equivalent capacity, making it ideal for sites with space constraints.

　 　4. Stable and controllable operation: Parameters such as stirring speed, temperature, and vacuum degree can be precisely adjusted. Automated control is achieved via a PLC system, reducing the need for manual intervention. The internal circulation flow is stable, resulting in minimal fluctuations in the crystal growth environment and ensuring high product quality consistency.

　　 5. Wide compatibility: The equipment can handle solutions with solute concentrations ranging from 5% to 25% and viscosities up to 1000 mPa·s. It is compatible with materials ranging from low viscosity to medium-to-high viscosity. By customizing the material (304 stainless steel, 316L stainless steel, titanium, or PTFE lining), it can be adapted to corrosive media. Additionally, the equipment supports various crystallization processes, including cooling, evaporation, and vacuum operations.

　　 6. Energy Consumption and Maintenance Advantages: The internal circulation system does not require an external circulation pump, reducing energy consumption by 30% to 50% compared to forced-circulation crystallizers. It features a simple structure with few moving parts (only the agitator), resulting in low failure risk, low maintenance costs, and convenient cleaning for batch-type models.

　　 7. High operational flexibility: By adjusting the stirring speed and cooling/heating power, production capacity can be flexibly modified (adjustment range: 20%-120%), making it suitable for meeting the production needs of different batches or product specifications. The same equipment can be shared for both small-batch trial production and medium-scale mass production.

Application scenarios

　　The flow-guided crystallizer, with its core advantages of efficient internal circulation, superior crystal quality, and a compact structure, is widely used in the following industries:

　　 1. Fine Chemical Industry: Crystallization of fine chemicals (such as sodium benzoate, potassium sorbate, and adipic acid); crystallization and purification of organic intermediates (such as terephthalic acid and phthalic anhydride); preparation of dyes and pigments with uniform particle size and high color fastness.

　 　2. Pharmaceutical Industry: Crystallization of pharmaceutical intermediates (such as ibuprofen intermediates and antibiotic side chains), purification of active pharmaceutical ingredients (such as vitamins, hormones, and antibiotics), and low-temperature crystallization of biological products (such as enzyme preparations and vaccine raw materials to prevent degradation of active ingredients).

　 　3. Food Industry: Crystallization of food additives (such as monosodium glutamate, xylitol, maltitol, and citric acid), crystallization of natural extracts (such as tea polyphenols, anthocyanins, and lactic acid), and dairy processing (such as lactose crystallization and whey protein purification);

　 　4. Chemical industry: Preparation of inorganic compounds (such as calcium carbonate, barium carbonate, and magnesium hydroxide), crystallization of salts (small-scale, high-purity industrial salts and specialty salts), and crystallization of fertilizer products (such as potassium dihydrogen phosphate and ammonium sulfate, produced in small batches and customized according to specific requirements).

　 　5. Environmental protection industry: Salt crystal recovery in the treatment of small- and medium-scale high-salinity wastewater (such as wastewater from the electronics industry and laboratory wastewater); concentration and crystallization to reduce the volume of organic wastewater (such as printing wastewater and coating wastewater).

　 　6. Other areas: Crystallization of cosmetic raw materials (such as hyaluronic acid and purified collagen), small-scale and pilot-scale testing of battery materials (such as laboratory-grade crystallization of lithium sulfate and lithium carbonate), and laboratory equipment for crystallization experiments and process development.