Gas Phase Filtration Industrial Gas Purification
Purification of Industrial Gases
Gas phas filtration: Chemical scrubber vs Physical Adsorption
Gas phase filtration using a chemical scrubber is a technology that has been applied successfully for decades for the purposes of eliminating contaminants in a gas flow. However, although it is a technique that is easy to design and quite flexible, it entails certain disadvantages and/or risks.
In recent years there has been considerable interest in developing alternative technologies that, without losing efficiency in gas purification, would minimise the risks involved in the use of wet or chemical scrubber.
One of the technologies that has most advanced in this respect is dry purification or physical adsorption. The adsorbent media involved in these processes have ignition temperatures of over 400ºC and they accept a wide load range with no reduction in efficiency. This means they can treat gases at high temperatures and loads.
Along these lines, and as the result of a major R+D effort, Bioconservacion has developed a wide spectrum of adsorbent media (pellets) that make it possible to remove contaminants by surface adherence in a dry state (the physical adsorption process.)
There can be no doubt that the installation of a dry gas purification system is an economical and highly advantageous solution:
- Initial investment
In general, the equipment needed with a chemical scrubber purification system consists of two towers, two recirculation pumps, three reagent tanks, three dosifiers, and redox and pH measuring sensors, whereas in the case of the adsorption purification system only one deodorisation tower is needed.
Obviously a more complex equipment installation requires a larger construction project, in addition to installations adapted to comply with the current regulations for the storage of chemical reagents (APQ6), due to the need to use liquids in the process.
In contrast, dry medium purification systems do not use any type of reagent requiring a specific installation.
In summary, the installation of a dry gas purification system requires less investment than chemical scrubber, as the equipment and construction work needed is much simpler and, moreover, there is no need to store corrosive chemical reagents.
Obviously, the larger amount of equipment needed in a chemical scrubber gas purification system results in higher electricity consumption.
Moreover, unlike dry gas purification installations, they need chemical reagents and water.
Therefore another advantage of installing a dry medium gas purification system is the saving in electricity, chemical reagents and water.
The cost of maintaining all the equipment needed in a chemical scrubber gas purification installation is high, as the recirculation pumps and dosifiers often need minor repairs.
In addition, the presence of chemical reagents makes wet medium installations more susceptible to corrosion problems.
In adsorption gas purification systems the only item that requires maintenance is the fan.
Therefore the cost of maintaining a dry medium gas purification installation is less than that of those with chemical scrubbers.
The fact that they do not require chemical reagents makes dry medium gas purification installations safer for the workers, as there is less risk of workplace accidents.
- Waste management
In gas purification systems with scrubbers, depending on the nature of the contaminants eliminated, the resulting effluents require further treatment before being dumped.
In contrast, the majority of adsorbent media used in dry systems do not produce hazardous waste, are non-toxic and can be dumped normally.
In other words, waste management is simpler in the case of adsorption gas purification systems.
Given all these factors, it is clear that in the majority of cases the installation of a dry medium gas purification system is the most efficient and cost-effective option.