Product Introduction

　　Oslo Crystallizer (also known as the OSLO Crystallizer) It is a continuous industrial crystallization equipment based on the principle of “suspension-bed crystallization + clarification and grading.” At its core, it employs “forced circulation + clear-liquid overflow” technology. By precisely controlling supersaturation to ensure its uniform distribution within the suspension bed at the bottom of the crystallizer, the equipment enables crystals to grow slowly and steadily in a stable environment. Meanwhile, the upper clarification zone is utilized to achieve crystal-size grading. With its key advantages—uniform crystal size (CV value ≤ 20%), continuous and stable production, high operational flexibility, and ease of scale-up—the equipment is widely applied in large-scale crystal product preparation and solution purification processes across industries such as chemical engineering, salt chemical industry, metallurgy, and environmental protection. It is particularly well-suited for large-scale production scenarios that demand regular crystal morphology and a narrow particle-size distribution. The equipment’s dimensions and circulation system parameters can be customized according to the material’s solubility characteristics and production capacity requirements (ranging from 1 ton/hour to 100 tons/hour).

Product Category

　　According to the operating method, circulation mode, and application scenarios, Oslo crystallizers are mainly divided into the following categories:

　　1. Classified by operation mode

　　▪ Continuous Oslo Crystallizer: The entire process—from feed addition, crystallization, to product discharge—is carried out continuously, ensuring a stable crystal growth environment and high production capacity (5 t/d to 500 t/d). This process is well-suited for large-scale industrial production, such as in the salt chemical and fertilizer industries.

　　▪ Intermittent Oslo Crystallizer: Single-batch completion of feeding—crystallization—discharge; simple structure, precise temperature control, suitable for preparing small-batch, multi-variety crystal products (such as fine chemicals and pharmaceutical intermediates).

　　▪ Semi-continuous Oslo crystallizer: The feeding and crystallization processes are continuous, while the discharge is intermittent, striking a balance between stability and flexibility, making it suitable for medium-scale production of products with multiple specifications.

　　2. Classified by cyclic power

　　▪ Forced-circulation Oslo crystallizer: A peripheral circulation pump is used to force the feed liquid to circulate between the crystallizer and the heat exchanger. The circulation flow rate is controllable (1–3 m/s), and the heat transfer efficiency is high, making this system suitable for materials with high viscosity and a tendency to scale.

　　▪ Natural circulation Oslo crystallizer: Utilizing the density difference of the liquid feed to create natural convection circulation, this system features no external circulation pump, resulting in low energy consumption and simple maintenance. It is particularly suitable for materials with low viscosity (<100 mPa·s) that are not prone to scaling.

　　3. Classified by crystallization process

　　▪ Cooling-type Oslo crystallizer: By cooling the feed liquid through a heat exchanger, the solubility is reduced, creating supersaturation that triggers crystallization. This process is particularly suitable for materials whose solubility varies significantly with temperature (such as potassium chloride and potassium nitrate).

　　▪ Evaporative Oslo Crystallizer: By heating and evaporating the solvent, the solute concentration is increased, creating supersaturation suitable for materials whose solubility changes gradually with temperature (such as sodium chloride and sodium sulfate).

　　▪ Vacuum-cooled Oslo crystallizer: By combining vacuum evaporation with a cooling effect, this process simultaneously reduces temperature and solvent content, resulting in high crystallization efficiency and low energy consumption. It is particularly suitable for heat-sensitive materials or scenarios requiring rapid crystallization.

　　4. Classified by Equipment Structure

　　▪ Standard Oslo Crystallizer: It consists of a crystallization chamber, a clarification zone, a circulation pipe, and a heat exchanger. With its compact structure and small footprint, it is suitable for the crystallization of conventional materials.

　　▪ Graded Oslo Crystallizer: Adding grading devices (such as sieve plates and flow-guiding cylinders) in the clarification zone can enhance the crystal size grading effect, enabling the production of crystals with a narrow particle size distribution (particle size range: 0.5–2 mm).

　　▪ Oslo crystallizer with washing section: A crystal-washing zone has been added at the bottom to remove the mother liquor from the crystal surface via countercurrent washing, thereby enhancing product purity and making it suitable for applications requiring high-purity crystals.

Performance Features

　　1. Excellent crystal quality: The supersaturation is precisely controlled (≤0.2 kg/kg solvent), the crystal growth rate is stable (0.1–0.5 mm/h), the product particle size is uniform (CV value ≤ 20%), the crystal morphology is regular (e.g., cubic or needle-like crystals), there is no agglomeration of fine crystals, and subsequent drying and packaging are convenient.

　　2. Continuous and stable operation: The continuous-operation design ensures that the crystal growth environment—temperature, concentration, and supersaturation—remains constant, with production capacity fluctuations no greater than 5%. The system can operate continuously for up to 24 hours without interruption, and the equipment boasts a long continuous operation cycle (3 to 6 months without requiring shutdown for cleaning).

　　3. High operational flexibility: By adjusting parameters such as circulating flow rate, heat exchanger temperature, and feed flow rate, the crystal particle size (0.2–5 mm) and production capacity (adjustable range: 30%–120%) can be flexibly controlled to meet the requirements of different product specifications.

　　4. Strong antifouling capability: Strong The circulating design ensures a high flow rate of the feed liquid, making it less likely for crystals to deposit and adhere to the tube walls of the heat exchanger. In the suspended-bed reactor, the suspended state of crystals prevents local supersaturation from becoming excessively high, thereby reducing scaling on the reactor walls and lowering maintenance costs.

　　5. Wide compatibility: It can handle a wide variety of materials whose solubility changes significantly or gradually with temperature. It is compatible with solutions ranging from low viscosity to medium-to-high viscosity (<500 mPa·s) and containing small amounts of suspended solids (≤2%). By customizing the material (316L stainless steel, titanium, or rubber-lined), it can also be adapted for corrosive media such as acidic, alkaline, and saline solutions.

　　6. High energy efficiency: The crystallization process requires only cooling or evaporation energy consumption, with no additional power consumption. When paired with a multi-effect or MVR system, the evaporative Oslo crystallizer can further reduce energy consumption—achieving energy savings of more than 60% compared to single-effect evaporation crystallization.

　　7. Easy to scale and expand: The equipment structure features a favorable amplification effect, allowing laboratory-scale parameters to be directly applied to the design of industrial-scale equipment. The modular design enables future capacity expansion (by adding circulation pumps, heat exchangers, or increasing the height of the crystallization chamber), while keeping investment costs under control.

Application scenarios

　　Thanks to its core advantages of continuous stability and superior crystal quality, the Oslo crystallizer is widely used in the following industries:

　　1. Salt chemical industry: Production of salt crystals such as potassium chloride, sodium chloride, potassium nitrate, sodium sulfate, and ammonium chloride—particularly well-suited for large-scale preparation of high-purity industrial salts (purity ≥ 99.5%);

　　2. Fertilizer Industry: Fertilizer products such as urea, ammonium chloride, potassium dihydrogen phosphate, and ammonium sulfate crystallize to form uniformly sized granular crystals, enhancing product flowability and application effectiveness.

　　3. Fine Chemical Industry: Crystallization and purification of fine chemicals (such as citric acid, lactic acid, and sodium benzoate) and preparation of crystals for organic intermediates (such as terephthalic acid and adipic acid)—with requirements for controllable crystal morphology and particle size.

　　4. Metallurgical Industry: Recovery of by-products from non-ferrous metal smelting (such as copper sulfate and nickel sulfate), crystallization and separation of rare earth elements (such as rare earth chlorides and rare earth nitrates), and recovery and purification of precious metals.

　　5. Environmental protection industry: Salt crystal recovery from zero-discharge high-salinity wastewater (such as wastewater from chemical parks and electroplating wastewater)—including mixed salts like sodium chloride and sodium sulfate—as well as crystallization of solid byproducts generated after treating landfill leachate.

　　6. Other areas: Crystallization of food additives (such as monosodium glutamate and xylitol), preparation of crystals for pharmaceutical excipients (such as mannitol and lactose), and crystallization and purification of battery materials (such as lithium sulfate and lithium carbonate).