MVR Evaporator Cleaning and Online Maintenance Strategy – Extending Continuous Operation Cycles

During long-term operation, MVR evaporators are prone to scaling, clogging, and corrosion on their heat exchange surfaces and inside the system due to factors such as material characteristics, water quality, and temperature. This leads to decreased heat transfer efficiency, increased energy consumption, and even affects system safety and stability. Scientific cleaning and online maintenance strategies are key to extending the continuous operating cycle of MVR evaporators and ensuring efficient system operation.

I. Main Types of Contamination and Their Impact on MVR Evaporators

Scale (deposition of inorganic salts, organic matter, colloids, etc.)

Reduces heat exchange efficiency, increases energy consumption, and can clog flow channels in severe cases.

Corrosion and Pitting

Damages equipment materials, shortens service life, and poses a risk of leakage.

Biological Contamination and Sludge

Especially in systems containing organic matter or circulating cooling water, it affects fluid flow and heat exchange.

Crystallization Blockage

In high-salt wastewater treatment, supersaturated crystals easily deposit on heat exchange surfaces or pipes.

II. Cleaning Strategies

1. Clean-in-Place (CIP)

• Automated Cleaning System: Equipped with a dedicated cleaning pump, cleaning fluid tank, and spray device, it achieves automatic circulating cleaning of the system without disassembling the equipment.

• Cleaning Cycle Setting: The cleaning cycle is dynamically set based on monitoring operating parameters (temperature difference, pressure difference, heat transfer coefficient, etc.) for preventative maintenance and to avoid severe scaling.

• Cleaning Agent Selection:Acid Washing (e.g., citric acid, nitric acid): Removes inorganic salt scale.

• Alkaline cleaning (e.g., sodium hydroxide, surfactants): Removes organic matter, grease, and biological slime.

• Compound cleaning agents: Enhance cleaning effectiveness for mixed-type fouling.

• Cleaning process: Cleaning solution circulation → soaking → rinsing → passivation treatment (corrosion prevention), ensuring thorough removal of fouling and protecting equipment surfaces.

2. Physical cleaning: High-pressure water jet cleaning: For severely scaled or hard-to-reach areas, high-pressure water jets are used for impact peeling, suitable for shutdown maintenance.

• Mechanical scraping/brushing: For specific heat exchange tubes or plates, manual or mechanical cleaning is performed.

3. Preventative chemical treatment: Adding scale inhibitors, dispersants, corrosion inhibitors, etc., reduces scaling and corrosion.

• Optimizing feed pretreatment (e.g., softening, filtration), reducing fouling at the source.

III. Online maintenance strategy:

1. Operating parameter monitoring and intelligent early warning: Real-time monitoring of key parameters: inlet and outlet temperature difference, pressure difference, steam pressure, flow rate, conductivity, etc.

Setting thresholds for automatic alarms, timely detection of scaling and clogging trends, and early intervention for maintenance.

2. Compressor and Vacuum System Maintenance: Regularly inspect the compressor's seals, lubrication, and cooling systems, and replace oils and filters promptly to prevent abnormal wear and efficiency decline.

Maintain the vacuum pump regularly to prevent cavitation and performance degradation, ensuring stable evaporation temperatures.

3. Heat Exchanger Surface and Circulating Pump Maintenance: Regularly observe the surface condition of heat exchanger tubes/plates, and clean or address any abnormalities promptly.

Monitor the vibration, noise, and flow rate of the circulating pump to prevent pump wear or cavitation.

4. Intelligent Control System Optimization: Utilize a PLC/DCS system to automatically adjust load, flow rate, and temperature to maintain optimal operating conditions and reduce localized overheating and fouling.

5. Regular Inspection and Planned Maintenance: Develop annual or quarterly maintenance plans, including equipment disassembly and inspection, seal replacement, and key component updates, prioritizing prevention.

IV. Typical Cases and Effect Analysis

Case 1: Oilfield High-Salinity Produced Water MVR System

Equipped with an automatic CIP system, online cleaning is performed every 30 days. Acid washing and passivation processes are used, extending the continuous operating cycle from 2 months to 6 months and reducing energy consumption by 15%. 

Case Study 2: Pharmaceutical Low-Temperature Concentration MVR Project

Combining intelligent monitoring and variable frequency control, the evaporation load and flow rate were dynamically optimized. Alkaline washing was used to remove organic matter, achieving continuous operation for over 8 months without significant scaling.

V. Common Misconceptions and Warnings

• Ignoring preventative maintenance and waiting until heat transfer efficiency significantly decreases before cleaning leads to increased energy consumption and costs.

• Inappropriate cleaning agent selection causes equipment corrosion or poor cleaning results.

• Failure to regularly replace vulnerable parts leads to sudden failures and unplanned downtime.

• Ignoring intelligent monitoring and data analysis results in missed early warning and optimization opportunities.

VI. Conclusion

A scientific cleaning and online maintenance strategy is the cornerstone for extending the continuous operating cycle of MVR evaporators and ensuring efficient, energy-saving, and safe system operation. Through multi-dimensional collaboration including automated online cleaning, preventative chemical treatment, real-time operation monitoring and intelligent control, and regular planned maintenance, scaling, clogging, and corrosion can be effectively reduced, significantly improving equipment reliability and economy. In the future, intelligent and digital operation and maintenance will further promote the long-term, high-efficiency application of MVR evaporators under complex operating conditions.