VOC removal technologies

Depending on the problem, VOC emission source reductions there are several options in regard to VOC emission source reduction. Possible approaches to reduce VOC emissions are:

• On-board degassing equipment;
• On-shore degassing facilities;
• Re-evaluation of cargo compatibilities;
• Dedicated transport.

The shore side facilities at a loading berth include a moveable arm that connects to flanges on the ship in order to transfer liquid to and from the ship’s tank(s). To be able to return vapour to shore, a vapour return line can be added to the loading arm. Alternatively, a separate arm can be used to collect vapour.

To transfer the vapour from the loading arm to the vapour treatment plant, a pipeline is needed. The cost of the piping will mainly depend on the distance to be covered and the loading rate (which determines the pipe diameter). The distance from the berth to the treatment plant is the main factor determining the cost and this will be highly site specific. Depending on the nature of the site, this distance could vary from a few dozens of metres to several kilometres. Reducing the distance by using mobile treatment systems has an impact on the capital cost of the piping. In addition to the piping, the following items are also required:

• Booster fans;
• Flame arrestors;
• Support fuel injection (for combustion processes);
• Monitoring instrumentation.

The main factor influencing the cost of a vapour treatment plant, is the maximum flow rate that needs to be treated and the type of VOC molecules that need to be removed. The type of VOC molecules or mixture of VOC molecules will eventually determine the installed technology.

VOC removal trough adsorption: activated carbon

There are several VOC removal technologies that can be applied, depending in the specific situation:

• Absorption;
• Adsorption;
• Cryogenic condensation;
• Membrane Separation;
• Reducing volatility;
• Thermal oxidation;
• Vapour balancing.

In an adsorption process, the contaminated air or gas passes through an activated carbon bed where the contaminants are removed by adsorption or chemisorption and the treated gases are released into the atmosphere. The activated carbon bed gradually becomes saturated. Once the activated carbon is saturated or breakthrough occurs, the used activated charcoal is:

• Regenerated in situ with steam or vacuum;
• Recycled by thermal reactivation or;
• Treated as a waste product that is valorised as fuel for the cement industry (with or without conditioning).

The product can either be installed in fixed bed system with or without regeneration system, but in a lot of cases mobile filter units like AIRCON^® are a cost-effective solution.

VOC removal in practice

Example : Degassing of chemical (inland) barges
	Challenge: Styrene emissions during loading Treatment objective <2mg/m3 Our Solution 2 x FILTRAFIX® L 1,000 kg AIRPEL®

Degassing of inland boats
	Challenge: Benzene removal Inlet concentration: 50g/m3 Treatment objective <2mg/m3 Flow rate: 3,000m3/h Our Solution AIRCON® HC ORGANOSORB® 10-CO CO monitoring CO2 inertisation CO2-inertisering

Don’t hesitate to contact us on VOC removal solutions, we’re at your service! DESOTEC Activated Carbon specialises in selecting the most appropriate activated carbon type and offering tailor-made purification solutions.

At DESOTEC’s facilities, all used carbon is analysed so the right measures can be taken for handling and removing the saturated carbon out of the mobile filters. All molecules that were adsorbed on the activated carbon at the customers’ site, are desorbed inside DESOTEC’s reactivation furnaces. These contaminants are then fully destroyed, in accordance with National and European legislation, by an incineration and neutralisation setup. The entire installation and it's emissions are under continuous on-line monitoring, which guarantees that only harmless water vapour is seen exiting the chimney.