Pollution control with Ceramic Filtration Systems:

the technology for the present and the future.

Tuesday 19 October 2021

Every day, producers and consumers alike are paying more attention to the environmental impact of their activities and the products they use.

Glass furnaces are on the top of the list of polluting emission sources for both micro-pollutants and CO2, but fortunately Air Pollution Control systems are readily available for reducing these impacts and these systems are constantly improving in performance and operational efficiency.

Ceramic Filtration (CF) is the cutting-edge technology for furnace emission control: let’s try understanding why.

Typical Ceramic Filter Treatment Scheme

A typical ceramic filter system is a compact process, simply composed by three stages:

-          Temperature control stage, where gas temperatures above 400°C/750°F are reduced with heat exchangers, air dilution, water quenching, or a combination of the above.

-          Reactant injection stage, usually performed in-duct, with injection of a deacidification sorbent (via lime- or sodium-based) and a denitrification reduction agent (via ammonia or urea dissolved in water).

-          Abatement Stage, using Catalytic ceramic filter housings, where all the pollutant families are abated thanks to a set of ceramic filtration elements, embedded with SCR catalyst. Abatement includes PM, heavy metals, SOx and acid gases, and NOx.

Other ancillary systems are captured dust collection and recycling to batch and ID fan for suction.

Ready for Present and Future Regulations

The Ceramic Filter system is more efficient than other Air Pollution Control Systems present in the market.

The expectation is that there will be also a general reduction of the APC downtime allowed for yearly maintenance, targeting 72 hours as maximum continuous stoppage allowed. This is already happening in countries such as Germany. Other countries or regions often request even more stringent allowances, with no downtime allowed. Technologies like electrostatic precipitators would require a fully redundant system, while a CF system can ensure these guarantees with:

o   Filter lifetimes often longer than furnace campaigns;

o   modular design, allowing to isolate one compartment while operating the others;

o   predictive maintenance, thanks to proprietary Tri-Mer’s devices, allowing on-line management of the filter status;

o   a patented system preventing catastrophic filter failures and maintaining compliant abatement performance in case of minor breakages.

The modularity of the CF system ensures that furnace size increases or unexpected temperature / flow rate increases will not generate problems to the system, allowing the spread of the CAPEX investment along the entire furnace campaign.

A More Profitable Choice for Waste Heat Recovery

Waste Heat Recovery (WHR) systems are spreading in the glass industry. The best equipment train is a combined installation of WHR with CF, realizing a profitable return on investment.

The reason is linked to the following aspects:

o   The high temperature available at the exit of the CF.

o   The high efficiency on SOx (and namely SO3) lowers the acid dew point and allows lower temperature of flue gas at heat exchanger exit (+10% recovery).

o   The very low dust level after the CF allows the use of finned heat exchangers, without soot-blowing systems, with a reduction of 50% of the heat exchanger cost for the same energy capture.

On a recent project on a container plant with furnaces reaching 900 tpd of total pull, a system designed to produce 2 MW electric with ORC module could reach a payback time of 3 years. Tri-Mer has now successfully equipped two furnaces with WHR with three additional systems currently under construction

Organic Rankine Cycle (ORC) turbines are the most suitable for power and/or compressed air production from waste heat, but also district heating can be implemented. Low pressure steam and other heat recovery systems have been successfully applied. A combination of waste heat recovery upstream and downstream of the filtration unit is also possible for maximum utilization results.

Summarizing the above, we can say that with Ceramic Filter Systems in Glass:

-          There is no single-stage technology with equal efficiency on the market; this generates advantages that go beyond the simple compliance with statutory emission limits and but in addition can generate profit with waste heat recovery systems and flue gas reutilisation.

-          The technology is now mature and reliable enough to serve the entire furnace campaign, also in case of future emission limit reduction and new BREFs that could arrive during the furnace lifetime. The modularity makes the system flexible and adaptable to the real furnace needs.

-          The system is easy to operate and maintain with lifetimes above 20 years; nevertheless, its design requires experience and care of a multitude of details that can only come from experienced providers.

Find out more in our article published by the trade magazine Glass Woldwide Issue 97 (page 74).