2t/h calcium chloride MVR evaporation and concentration system for fine chemical industry

I.Project Background

Calcium chloride, as a common byproduct or component in specific process steps, is frequently found in wastewater or intermediates during fine chemical production. Its solution is characterized by a high boiling point, high corrosiveness, and a tendency to scale, making it difficult to treat. Conqinphi's fine chemical client generates a large amount of low-concentration calcium chloride solution daily and designed an MVR (Mechanical Vapor Recompression) evaporation and concentration system. The client urgently needed a high-efficiency, energy-saving concentration treatment solution that could achieve resource recovery, as traditional disposal methods were costly and did not conform to the principles of a green circular economy.

II.Solution

Based on a deep understanding of the characteristics of calcium chloride, Conqinphi designed and built a 2-ton/hour MVR forced circulation evaporation and concentration system for the client. This solution utilizes mechanical vapor recompression (MVR) technology as its core, combined with special anti-scaling and anti-corrosion designs, successfully concentrating the low-concentration calcium chloride solution to a high concentration, laying a solid foundation for subsequent resource utilization.

III.System Core Advantages

1.Targeted Anti-scaling Design for Continuous Operation

Addressing the challenge of calcium chloride crystallization and scaling during evaporation, the system's core evaporator employs forced circulation (FC) mode. A high-flow-rate circulating pump maintains high-speed turbulent flow of the material within the tubes, significantly inhibiting crystal adhesion and growth on the heated tube walls. This effectively solves the scaling and clogging problem, ensuring long-term stable and continuous system operation.

2.Significant Energy Savings

This MVR system fully utilizes the latent heat of secondary steam. The secondary steam generated by evaporation is compressed by a high-efficiency turbo compressor, increasing its temperature and pressure, serving as the system's primary heat source. This significantly reduces reliance on external fresh steam, lowering operating energy consumption by approximately 60% compared to traditional multi-effect evaporators, resulting in substantial economic benefits for customers. 

3.Advanced Materials and Corrosion Protection Technology

Given the strong corrosiveness of calcium chloride solution, especially under high temperature and high concentration conditions, to carbon steel, the core components of this system that come into contact with the material (such as heating pipes, evaporation chambers, and circulating pumps) are all made of high-grade stainless steel (such as 2205 duplex stainless steel) or titanium. This fundamentally solves the equipment corrosion problem, extends the system's service life, and reduces maintenance costs.

4.Highly Automated Control

The system integrates an advanced PLC control system, which can precisely and automatically adjust key parameters such as feed concentration, liquid level, temperature, pressure, and compressor speed. The system can automatically adapt to fluctuations in operating conditions, achieving one-button start/stop and fully automatic operation, effectively ensuring the stability of the final concentrate concentration and reducing the intensity and error of manual operation.

5.Resource Utilization, Turning Waste into Treasure

The system successfully concentrates dilute calcium chloride solution to a high concentration of 40% or higher (or further processes it into a solid). The output can be sold as a product and widely used in dehumidifiers, snow-melting agents, desiccants, building materials, and other fields, realizing waste resource utilization and creating new economic benefits.

IV.System Process Flow Overview

1.Feeding and Preheating: The raw liquid first passes through a plate heat exchanger, undergoing multi-stage heat exchange with the system's condensate and concentrate, preheating to near boiling point and fully recovering the system's waste heat.

2.Forced Circulation Evaporation: The preheated material enters the forced circulation evaporator. Driven by a circulation pump, the material flows at high speed through the heating chamber, absorbing heat from the compressed secondary steam and heating up (but without boiling). Upon entering the evaporation separation chamber, due to a sudden pressure drop, the material flashes to generate secondary steam.

3.Steam Compression and Reuse: The secondary steam generated by flash evaporation enters the compressor, is compressed to increase its grade, and then sent back to the heating chamber as a heat source. This cycle constitutes a highly efficient thermal energy utilization system.

4.Concentration and Discharge: The material continuously circulates within the system, and moisture continuously evaporates, gradually increasing the concentration. When the preset concentration is reached, a high-concentration calcium chloride solution is continuously discharged from the system; after cooling, it can be used as the product.

5.Condensate Reuse: The clean condensate formed by the condensation of heating steam, after preheating the raw liquid in a heat exchanger, can be reused as high-quality process water, achieving water resource recycling.

V.Project Results and Customer Value

Since the stable operation of this 2t/h calcium chloride MVR forced circulation evaporation and concentration system, it has created multi-dimensional value for the customer:

1.Significantly Reduced Operating Costs: Extremely low electricity consumption replaces the vast majority of steam consumption, saving over one million yuan in annual operating costs.

2.Environmental Compliance and Resource Utilization: It completely solves the problem of disposing of high-salinity wastewater and produces economically valuable calcium chloride products, achieving a win-win situation for both environmental and economic benefits.

3.Stable Production Guarantee: Strong anti-scaling capabilities ensure that the system operates for over 8,000 hours annually, providing strong support for the continuity and stability of the customer's production.

The successful implementation of this project once again demonstrates Conqinphi's strong technical capabilities and rich engineering experience in handling highly difficult, easily scaling, and highly corrosive chemical materials.