Volatile organic compounds (VOCs) come off storage tanks, loading operations, process vents, wastewater systems and tank cleaning work. They affect air quality and worker safety, and industrial sites in Saudi Arabia are expected to control emissions under national environmental requirements. Choosing the right treatment technology depends on the vapour, the concentration and the flow.
First, understand the stream
- Which compounds are in the vapour, and do any need special handling, such as benzene or chlorinated solvents?
- Concentration and whether it is steady or changes in batches.
- Air flow rate to be treated.
- Humidity, dust and corrosive gases that can affect the equipment.
- Explosion risk. Concentrations near the lower explosive limit need safe design.
Common VOC removal technologies
Activated carbon adsorption
Vapour passes through a bed of activated carbon that holds the VOCs. It suits low to medium concentrations and a wide range of solvents. The carbon needs replacement or regeneration, so running cost depends on the load.
Thermal oxidisers
The vapour is heated to a high temperature so the VOCs break down into carbon dioxide and water. They achieve very high destruction efficiency and handle mixed streams. Fuel use is the main cost, and heat recovery reduces it.
Catalytic oxidisers
These work like thermal oxidisers but use a catalyst to operate at a lower temperature, which saves fuel. They need a clean stream because some contaminants poison the catalyst.
Wet scrubbers
The gas is contacted with a liquid that absorbs the pollutant. They suit water-soluble VOCs and can handle acid gases at the same time, but they create a liquid stream that needs treatment.
Condensation and vapour recovery
Cooling the vapour recovers the solvent as a liquid. This works well for high concentrations and when the recovered product has value.
Biofiltration
Microorganisms break down biodegradable VOCs at low concentrations. It has low operating cost, but it needs stable conditions and more space.
How to choose
| Situation | Often suitable |
|---|---|
| Low concentration, varied solvents | Activated carbon |
| High concentration, mixed stream | Thermal oxidiser |
| Medium concentration, clean air | Catalytic oxidiser |
| Water-soluble VOCs or acid gases | Wet scrubber |
| High concentration of valuable solvent | Condensation recovery |
This table is a starting point. The right answer depends on the measured stream, so sampling and analysis should come before any equipment decision.
Do not forget the supporting equipment
Fans and blowers, ducting, valves, pumps for scrubber liquor and instrumentation all decide whether a system works day to day. Under-sized fans or poor materials are a common reason that a good technology performs badly.
Power Energy Gulf supports VOC and emission control projects for industrial plants in Saudi Arabia and the GCC. Read about our VOC removal and emission control services and our industrial fans and blowers, or contact us to discuss your site.