3t/h sodium chloride MVR evaporation crystallization system for fine chemical industry

I.Project Background

Sodium chloride is a common high-salt byproduct in fine chemical production processes, frequently participating in various chemical reactions. Direct discharge of its wastewater not only severely pollutes aquatic environments and causes soil salinization, but also results in a significant waste of industrial salt resources. Faced with increasingly stringent environmental regulations and the inherent requirements of sustainable development, Kangqinfei's fine chemical clients urgently need a mature solution capable of stably and efficiently treating their high-salt wastewater and achieving salt resource recovery and utilization.

II.Solution

Adhering to the circular economy concept of "turning waste into treasure," Kangqinfei designed and delivered a sodium chloride MVR evaporation crystallization system with a processing capacity of 3 tons/hour. This system employs mature mechanical vapor recompression (MVR) technology and precisely controls the crystallization characteristics of sodium chloride, successfully achieving the recovery of high-purity sodium chloride and near-zero wastewater discharge.

III. Core System Advantages

1.High-Quality Salt Crystallization and Resource Utilization:The core objective of this MVR evaporation system is to produce high-purity sodium chloride crystals. By precisely controlling the supersaturation of the evaporation chamber and employing a unique crystallizer design, it effectively promotes the regular growth of crystal nuclei and inhibits the formation of fine crystals, ultimately yielding sodium chloride products with uniform particle size and purity meeting industrial salt standards. These products can be directly sold as industrial raw materials, realizing a transformation from "waste treatment" to "product production."

2.Optimized anti-scaling and cleaning design:Although sodium chloride has a lower tendency to scale than calcium chloride, this is still significant in long-term operation. This system employs Oslo crystallization technology or a similar external circulating crystallizer, allowing crystals to grow in full suspension within the crystallizer, reducing sedimentation on the heating surface. Simultaneously, the system is equipped with an automatic online cleaning (CIP) function, which periodically cleans the heat exchange tubes, easily removing trace amounts of scale and ensuring heat transfer efficiency and continuous operation.

3.Significant energy efficiency: This system integrates high-efficiency heat pump compression technology and a multi-stage preheater, recovering and compressing all secondary steam generated during evaporation as the system's sole heat source. Compared to traditional triple-effect evaporators, this system saves over 60% on energy. For systems with a processing capacity of up to 3 tons/hour, significant annual savings in steam costs can be achieved, substantially shortening the investment payback period.

4.High Integration and Automated Control: The system integrates a PLC automatic control system, enabling precise control of the entire process from feeding, evaporation, crystallization, centrifugation to discharge. The system automatically maintains the optimal supersaturation range, ensuring stable crystal quality and enabling one-button start/stop and fault diagnosis. This greatly reduces reliance on operator experience, thus guaranteeing production stability and product consistency.

5.Comprehensive Environmental Benefits: The system ultimately produces two parts: high-purity sodium chloride crystals and clean condensate. After simple treatment, the condensate can be used as high-quality reclaimed water for factory cooling or cleaning processes, achieving "zero discharge" of wastewater, conserving valuable freshwater resources, and thus bringing significant environmental benefits.

IV.System Process Overview

1.Pretreatment and Preheating: After pH adjustment and filtration, the feed liquid enters a multi-stage preheater, where it exchanges heat with the concentrated liquid and condensate produced by the system, fully recovering waste heat.

2.Mechanical Steam Reforming Evaporation Crystallization: The preheated material enters a forced circulation evaporator, where it is heated by compressed secondary steam within the heat exchange tubes. Subsequently, the solution flashes in the evaporation separation chamber, generating secondary steam.

3.Crystal Growth and Classification: The concentrated supersaturated solution enters the Oslo crystallizer, where small crystals grow in suspension, while larger crystals settle to the bottom. This classification effectively ensures the uniformity of salt particle size.

4.Solid-Liquid Separation and Drying: The crystal slurry is discharged from the bottom of the crystallizer and enters a centrifuge for dehydration, yielding wet salt. The wet salt can be further dried using a fluidized bed dryer to obtain the dried finished salt product.

5.Steam Circulation and Condensation: The secondary steam generated by evaporation is pressurized and heated by a compressor.