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Mission Accomplished

Posted on 9th September 2021

Last year, Parsons was engaged by a specialised glass manufacturing company to develop a new manufacturing process based on glass smelting. This procedure also entailed dealing with extreme temperatures up to 1200 Celsius / 2192 Degrees Fahrenheit had to be catered for.

As the original R&D investigations were anticipated to run for six months only, we advised the client to take advantage of our equipment rental offering. Rather than purchasing, this supported the pilot and continuous improvement to prove out and their new production vision.

The company R&D unit Parsons were tasked to support didn’t understand the exhaust fumes’ exact chemistry but was experiencing significant localised issues. One of the first challenges we faced was precisely identifying the toxic fumes. Although we were expecting that the principal pollutant would be Phosphoric Acid which is toxic and highly corrosive, it soon became apparent that there were significant amounts of ammonia gas also being discharged from the furnace.

Parsons updated the plant into a two-stage system that allowed the ammonia to be treated and a second stage to remove the phosphoric Acid. Following the upgrade to the rental system, the first stage removed the ammonia; however, after analysing the emissions discharged into the atmosphere, it was clear that the Phosphoric Acid fume was not being absorbed in the second stage?

Parsons knew that this indicated the phosphoric Acid was not present as a fume. Still, as a sub-micron aerosol, aerosols are notoriously tricky to measure and capture. Hence, Parsons drew on their experience of aerosol removal and upgraded the second stage scrubber with a fluidised bed aerosol arrestment stage, designed as a primary or roughing stage. The roughing step is a multi-layered mesh pad through which the process gas flows, entrained droplets and larger mist droplets captured through impingement. From here, the water droplets coalesce to form liquid droplets, which trickle down the mesh and fall back into the scrubber. The resulting modification removed a substantial amount of the discharge, as can be seen by the second photograph. However, still, the release was not acceptable to the client and the local environment agency. After installing the roughing stage, it confirmed that further treatment was required.

Parsons could determine the discharged aerosol was <30 micron. Concluding a third stage to the system was needed; namely a candle filter – a fibre bed filter made from chemical-resistant fibre-packed into a cage for support. The aerosol laden gas is forced horizontally through the bed. The aerosol particles are contracted and collected on individual fibres through the mechanisms of inertial impaction, direct interception, and random Brownian diffusional deposition. The candle filter was installed onto the rental plant, and once tested, the remaining discharge was entirely eliminated, as seen In the Video case study.

Following the successful trials, the client converted the pilot plant into a small-scale production facility that is now producing a product and generating a revenue stream. As the new manufacturing process and production are chemical-free, the client has gained the confidence to move forward and invest in a new production plant tripling manufacturing capacity and has purchased a complete Parsons fume scrubbing unit, as now proven.

Parsons will be undertaking the complete Installation and will be giving ongoing service and maintenance support to enable the client to focus on production. Here at Parsons, we designed, manufactured, installed, and commissioned the three-stage (ammonia removal, phosphoric acid removal and aerosol removal) rental abatement systems capable of pollutant removal from the gaseous phase and aerosol phase down to the submicron range.

New manufacturing process completed, post successful trials with Parsons support – Mission Accomplished…

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