The AWS Technology
Technology
The internationally patented AWS regenerative fall film technology is based on wet mechanical and/or wet chemical or physical separation.
In the conventional washing processes, the separation of pollutants either takes place at the actual drip of the washing liquid, or during the passage of the contaminated gases through the washing liquid. This process is not very effective and is hard to control accurately.
In contrast, the AWS technology employs polyester tubes, which have been specially treated to make them stable and porous. This enables a water film to develop on the tubes, which then represents the reactive surface for the mass transfer.
The washing liquid is fed into the tubes from above, and on its way down it permeates to the outer side of the tubes. This process enables an even and cohesive liquid film to develop on the tubes.
The low running speed or rather the adherence of the liquid to the surface of the tubes prevents drop formation and absorption of drops by the gas stream. This is why there is no need for a droplet separator.
The tubes are arranged in offset fashion inside a container to ensure that the waste air passing through the container is permanently in turbulence or redirected during its horizontal passage through the reactor.
These basic properties of the AWS process technology – the downward-flowing water film on the porous polyester tubes and the flow of a constantly redirected gas stream through the reactor – are the prerequisite to allow effective contact between the washing liquid and the pollutants to be separated.
The separation performance can be adjusted to the required level by the number of tube levels inside the reactor. This makes the technology highly scalable in size, throughput and separation results.
The principle of this process is explained in the diagram below:
AWS TechnologyThe absorption liquid enters the polyester tubes from above and exits at the lower end of the tubes outside the reactor. On its way down, the liquid permeates through the porous tube sides onto the outer side of the tube, where it runs downwards. The water film generated by this process represents the reactive surface for the gas cleaning process.
The excellent conditions for mass transfer resulting from the use of the porous polyester tubes and the arrangement of these tubes within the reactor, also allow the system to be used for the filtration of particulate matter or for the humidification of breathable or process air. During the separation of gaseous pollutants from waste gas containing particulate matter, the particulate matter and the gaseous particles are simultaneously separated. This represents an additional cleaning effect.
Depending on the use case, organic or inorganic solvents – partially mixed with water – are employed for the separation process. If desired, the separated organic pollutants can be recycled using distillation or stripping processes. The application of these simple and proven technologies is particularly useful when the separated substances are valuable and are destined for reuse. In addition, the cyclical arrangement ensures that the absorption liquid can constantly be reused in the VOC-recycling process.
The AWS technology can be employed for almost all waste air or waste gas cleaning tasks required by law.
It is particularly suited for the following use cases of waste air and waste gas cleaning:
- soluble and insoluble VOC separation
- inorganic gas separation (HCl, HF, SO2, SO3)
- soluble and non-soluble odorant separation
- particle separation up to a grain size of 0.3 µm
- air hygienisation and humidification.
Currently, AWS Group AG offers the following products on the basis of the regenerative fall film technology: