The problem of collecting combustible dust, like coal dust, from polluted can only be solved with wet scrubbing methods. Not only wet air scrubbers are far superior to dry systems, but the latter present great danger as they provide the ideal environment for the combustion to happen.

However, wet scrubbers have drawbacks that often impact the production process in a negative way. Among some of the more prominent ones is the need for purified water to scrub the gas stream. Most conventional scrubber are not able to utilize contaminated water, containing dust and small rocks, in the scrubbing process, and if such water is used, it often leads to buildup forming on critical scrubber parts and premature scrubber breakdown, not to mention the need for frequent maintenance stops and increased maintenance costs. Coal dust facilities do not always have the access to purified water in the required quantities which makes wet air scrubbers use a nuissance rather than a simple pollution control solution.

Conventional wet air scrubbers, even when purified water is used, are higly prone to buildup, which are solid deposits settling inside the scrubber. The buildup needs to be frequently removed from the internal scrubber surfaces as it causes a significant drop in scrubing efficiency as well as eventual scrubber breakdown. Frequent maintenance stops not only present a hurdle for the production process, but also requires the use of additional equipment.

The formation of waves inside wet air scrubbers is another problem. The rocking of the foam layer inside the scrubber may lead to the exposure of the grid. Multiple solutions have been proposed, including wave suppressing grids and dividing the gas stream into multiple streams while using several wet scrubberts simultaneously.

We at Redwood technology have implemented a different approach to foam stabilization that has allowed out wet air scrubber to avoid all of the drawbacks that regular wet scrubber systems have. We have designed a grid that is able to stabilize the foam layer ay high gas flow speeds – over 100 tom-m3/s. Rigorous testing of the grids at a coal loading facility has shown that even after prolonged continuous use over the grids remained buildup-free despite all other surfaces being covered by solid deposits.

The grid used inside Redwood technology wet air scrubber makes our system 5 to 8 times more efficient at scrubbing particulate matter that conventional wet scrubbers. Multidirectional gas flows collide within the grid and form additional vortices that significantly increase treatment quality.

We have hands-on experience in using Redwood technology wet air scrubber at coal storage facilities. We have installed our system directly in coal discharge areas., where coal dust loaded air with a density of 1.3 g / cm3 contained 90% of dust with particles less than 10 microns in size.

Testing has revealed that Redwood technology wet air scrubber remains free of buildup after continuous use in harsh conditions. There was no need for maintenance stops or grid cleaning. The efficiency of the wet air scrubber remained stable and did not decrease over time. Coal dust treatment quality amounted to 98.7-99.5% at different coal discharge areas.


The polypropylene dispersive grating unit ready to be installed.


The wet air scrubber dispersive grating after one year of the continuous air treatment process. The gaps in the grating elements are clearly visible.