Collection coalescing filter

The collection of the pyrolysis oils is difficult due to their tendency to form aerosols and also due to the volatile nature of many of the oil constituents. As the aerosols agglomerate into larger droplets, they can be removed by cyclonic separators. However, the submicron aerosols cannot be efficiently collected by cyclonic or inertial techniques, and collection by impact of the aerosols due to their Brownian or random motion must be utilized. A coalescing filter is relatively porous, but it contains a large surface area for the aerosol particles to impact by Brownian motion as they are swept through by the pyrolysis gases. Once the aerosol droplets impact the filter fibers, they are captured and coalesce into large drops that can flow down the fibers and be collected. 

I recommend using a larger coalescer, and also adding another water filter and a gas dryer to try to remove as much moisture as possible. We found that the system in field tests carried a lot more water than expected. The storage tank collected much of this moisture, and although this not a big problem, it is not desirable. 

Once the oil is collected, it is then pumped to on-ship coalescers that use surfactants and oil-wet or water-wet filters to break the crude oil-brine emulsion. 

The droplets continue to grow in size until drag and gravity forces break them away from the fibre, and they drop off the filter mat into a sump. In practice, a final stripping stage is usually desirable, such as a fine mesh screen located downstream of the coalescer to collect smaller water droplets, which may spin free and be carried along with the oil stream, rather than settle under gravity. 

The oil wetting surface may also occur in the form of a fibrous pack or as a collection of granules. Coalescers of this type resemble filters but serve to "grow" rather than to capture oil droplets. 

Oleophilic material can also be fabricated into loose media, and the media collected in a vessel. If the material is fabricated in a granular form and assembled into a deep bed gravity settler, the deep bed filter can also perform a coalescing function. 

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