MVC desalination plant (Mechanical vapor compression)

MVC is the smallest, most energy-efficient, and smartest desalination technology for small and medium-sized industries — but without proper chemical management, the smallest mistakes can cause the biggest losses.

In this expert guide, we’ll cover everything about MVC desalination — from how it works and benefits to chemical challenges and practical solutions — in simple, actionable language. And, finally, we’ll show you how to increase efficiency, reduce costs, and extend equipment life.

Why read this article?

✅ Gain a deep understanding of how MVC desalination works

✅ Identify its advantages and disadvantages in industrial applications

✅ Learn about the industries that use MVC the most and why

✅ Expert solutions for controlling scale, corrosion, and chemical washing of evaporators

What is MVC desalination?

MVC stands for Mechanical Vapor Compression. A thermal technology that uses salt or brackish water to produce fresh water with very low energy consumption.

How MVC works:

• The salt water is heated and evaporated in the evaporator.
• The steam produced is compressed by a mechanical compressor and its temperature increases.
• The hot and compressed steam returns to the evaporator as a heat source and gives its heat to the incoming water.
• After condensation, the steam is collected as fresh water.
• The concentrated water (brine) is discharged from the system.

Key advantage: Closed system — no external heat source required — very low energy consumption.

Advantages of MVC desalination — why is it popular in small and medium industries?

1. Very low energy consumption (5 to 10 kWh per cubic meter of water)

• Only electricity required for the compressor — no steam or fuel required

2. Fully enclosed and compact system

• Suitable for confined spaces and mobile or remote projects

3. Automatic operation without the need for constant monitoring

• Advanced control systems — Ability to start up and maintain with minimal human effort

4. No need for external heat source

• Unlike MED or MSF, no need for steam or hot water — Suitable for industries without access to thermal energy

5. Very high outlet water quality (TDS < 10 ppm)

• Suitable for feeding boilers, laboratory uses and sensitive processes

Disadvantages and challenges of MVC desalination — What causes system failure?

1. Evaporator scale formation

• Formation of calcium carbonate, calcium sulfate and magnesium hydroxide on hot surfaces → Reduced heat transfer → Increased compressor load → Increased power consumption

2. Corrosion in compressor and pipes

• Presence of chlorides and dissolved oxygen → Corrosion of carbon steel and stainless steel — especially at high temperatures

3. Sensitivity to incoming water quality

• Highly hard or silica-containing water → Rapid scale formation — efficiency loss in less than 3 months

4. Relatively high initial cost (compared to RO in small capacities)

• Mechanical compressors and precise control equipment — increase investment cost

5. Need for periodic flushing with specialized chemicals

• Washing with strong acids → Damage to metals → Leakage and emergency shutdown
• Need for non-corrosive, temperature-compatible sedimentation vectors

In which industries is MVC desalination used? And why?

1. Small and medium industries (capacity 100 to 5000 cubic meters per day)

• → Why?
• Need for high quality water without heavy investment
• Lack of access to steam or hot water
• Limited space for equipment installation

2. Remote and island projects

• → Why?
• Need for an independent and low-consumption system
• Possibility of power supply with generator or solar panel
• Easy transportation and installation

3. Food and pharmaceutical industries

• → Why?
• Production of high purity water for production and washing processes
• Continuous operation and no need for regeneration chemicals

4. Small power plants and steam generation units

• → Why?
• Production of high purity boiler feed water
• Cost reduction by using local salty or brackish water

When should the MVC system be flushed?

• 10-15% increase in compressor power consumption
• 10-20% decrease in fresh water production
• Increase in operating temperature in evaporator
• Increase in pressure in evaporation chamber
• Increase in vibration or noise in compressor or pipes

Golden tip:

Don’t wait for the system to experience a significant drop in efficiency! Periodic cleaning (every 6-12 months) can double the life of the equipment and reduce energy costs by up to 25%.

Final conclusion:

The MVC desalination plant is an energy-efficient, smart technology ideal for small and medium-sized industries — but without proper chemical management, it becomes a source of cost and reduced efficiency.