Tubular Falling Film Low-Temperature Evaporation Crystallizer

The tubular falling film low-temperature evaporation crystallizer is an advanced device that organically combines falling film evaporation technology with crystallization separation process. It is specifically designed for treating high-salt wastewater, heat-sensitive materials, and systems prone to scaling. This equipment achieves rapid evaporation and continuous crystallization in a vacuum low-temperature environment by forming a uniform thin film of liquid on the inner wall of vertical heat exchange tubes and allowing it to flow downwards. It boasts significant advantages such as high heat transfer efficiency, short residence time, and good crystal quality, and is widely used in various industrial fields including chemical, pharmaceutical, environmental protection, and food industries.

I. Structural Principle: Synergy of Thin Film Flow and Low-Temperature Evaporation

The core structure of the tubular falling film low-temperature evaporation crystallizer consists of a heating chamber, a separation chamber, a circulating pump, a crystallization settling zone, and an automated control system. Multiple vertical heat exchange tubes are densely arranged within the heating chamber. The feed liquid is evenly distributed to the inner wall of each tube by a top liquid distributor, forming a liquid film only 0.52 mm thick that flows downwards under the influence of gravity. Meanwhile, heating steam condenses and releases heat outside the tubes, and the liquid film rapidly boils and evaporates under vacuum and low-temperature conditions (3570℃). The solvent vaporizes and enters the separation chamber for gas-liquid separation. The secondary steam is compressed and recycled or condensed for recovery.

The concentrated liquid enters the lower crystallization sedimentation zone, where the solute in the supersaturated solution gradually precipitates to form crystals. Due to the system maintaining a stable vacuum and temperature gradient, the crystals continue to grow in suspension, resulting in uniform and controllable particle size. Large crystal particles settle to the bottom and are discharged by the discharge pump, while fine crystal nuclei are circulated back to the heating chamber with the mother liquor to continue growing, achieving continuous and automated production.

II. Technical Advantages: Four Major Performance Breakthroughs

1. Extreme Heat Transfer Efficiency, Doubling Evaporation Intensity

In the falling film flow state, the liquid film thickness is extremely thin and constantly renewed, resulting in a heat transfer coefficient as high as 2000-5000 W/(㎡·K), far exceeding that of traditional batch evaporators. 1. Material residence time within the heat exchange tubes is only a few seconds to tens of seconds, effectively preventing the decomposition and deterioration of heat-sensitive materials. Simultaneously, the evaporation intensity per unit heat exchange area can reach 35 times that of conventional equipment. The equipment is compact and requires less investment.

2. Low-temperature vacuum operation, eliminating scaling problems. 

In a low-temperature vacuum environment of 40-50℃, the solubility of substances with reverse solubility, such as calcium sulfate and calcium carbonate, actually increases, making it less likely to precipitate and form scale on the tube walls. At the same time, the high-speed flowing liquid film exerts a strong scouring effect on the tube walls, promptly carrying away any trace crystals that adhere. This characteristic makes the equipment particularly suitable for treating high-hardness, high-alkalinity, and easily scaling high-salt wastewater, extending the cleaning cycle to several weeks or even months, and its operational stability far exceeds that of traditional evaporators.

3. Excellent crystal quality, uniform and controllable particle size. 

The integrated design of the crystallization zone and evaporation zone, through precise control of the evaporation rate, circulation flow rate, and crystal slurry density, can obtain crystal products with narrow particle size distribution, high purity, and good flowability. The mother liquor undergoes graded sedimentation in the crystallization zone, with large crystals preferentially discharged and fine crystals regenerating, avoiding fine crystal entrainment and impurity encapsulation. Product purity can reach over 99%, meeting pharmaceutical and food-grade standards.

4. Significant Energy Saving and Low Operating Costs

Utilizing mechanical vapor recompression (MVR) or heat pump technology, the latent heat of secondary steam is fully recovered, achieving a coefficient of performance (COP) of up to 10¹⁵, meaning that 1 unit of electrical energy consumption generates 10¹⁵ units of evaporative heat. Compared to traditional multi-effect evaporation, energy savings reach 60%-80%; no external cooling water is required, reducing water consumption by over 90%. For example, treating 10 tons/hour of high-salinity wastewater can save millions of yuan in annual operating costs.

III. Application Scenarios: Precisely Matching Industry Needs

Chemical High-Salt Wastewater: Targeting chemical wastewater containing sodium chloride, sodium sulfate, sodium nitrate, and ammonium salts, achieving salt recovery and zero wastewater discharge, solving environmental compliance challenges.

Pharmaceutical Mother Liquor Treatment: Low-temperature concentration and crystallization of pharmaceutical mother liquors such as antibiotics, amino acids, and vitamins to recover active ingredients and reduce hazardous waste disposal costs.

Heat-Sensitive Material Concentration: Low-temperature concentration of food products such as fruit juices, dairy products, plant extracts, and enzyme preparations to retain active ingredients and flavor compounds.

Scaling-Prone Systems: Treatment of high-hardness water such as desulfurization wastewater, reverse osmosis concentrate, and electroplating wastewater, overcoming the pain point of frequent scaling and cleaning of traditional evaporators.

IV. Customized Services and Quality Assurance

Conqinphi offer a series of products with heat exchange areas ranging from 10㎡ to 500㎡, with materials including 304, 316L, duplex steel, or titanium, adaptable to various corrosive media. Equipped with an advanced PLC control system, it achieves full automation of the feeding, evaporation, crystallization, and discharging process, supporting remote monitoring and fault diagnosis. From process design and equipment manufacturing to installation, commissioning, and operation training, we provide full life-cycle technical services to ensure long-term stable and efficient operation of the equipment, helping customers achieve a win-win situation of economic and environmental benefits.

With its comprehensive advantages of high efficiency, energy saving, anti-scaling, and high quality, the tubular falling film low-temperature evaporator crystallizer is becoming a technological benchmark in the field of industrial evaporation crystallization. Choosing this equipment means choosing a more reliable, economical, and environmentally friendly production method.