Page 45 - Altogether Magazine Issue 4 English

45 THE EOLIOS PITCH FUME TREATMENT SYSTEM IN QATALUM’S PASTE PLANT: Qatalum’s Pitch Fume Treatment in the Paste A NEW Plant, which incorporates a dry scrubber and RTO technology (Regenerative Thermal Oxiidser), sets a new benchmark in the Gulf, BENCHMARK demonstrating several indispensable qualities. It optimises capture and destruction efficiency while cutting natural gas consumption – and IN THE GULF the associated carbon footprint – dramatically. As we at Qatalum well know, in a carbon plant, treating was observed. The system is an optimized combination emissions of polycyclic aromatic hydrocarbons (PAH) of a dry scrubber, based on the adsorption of PAH on – some of which are known or suspected to be highly coke fines, and a Regenerative Thermal Oxidizer (RTO), carcinogenic – is a vital priority. Since the introduction using oxidation technology. This combination minimizes of paste mixer-coolers in the process fabrication of energy consumption while maximizing the treatment anodes, there has been a substantial proliferation of efficiency. volatile compounds. Accordingly, emissions standards have become more stringent. It is therefore crucial that PAHs are the main components of coal tar pitch volatiles treatment technology can cope with more concentrated (CTPV). This is produced when coal tar pitch – a binder streams at the inlet, and lower emission requirements at for the fabrication of anodes, which is solid at ambient the outlet. temperature – is heated at around 160-200 degrees centigrade to turn it into liquid. PAHs can exist as light How does this work in practice? The Eolios System, and heavy fractions, the former defined as having fewer developed by Solios, delivers an unprecedented level of than 3 aromatic rings in a molecule. Adding water to performance. Independent tests conducted in January cool the anode paste substantially increases production 2013 at the Qatalum Green Anode Plant, the largest of the light fraction, which are released in gaseous single line green anode plant in the world, found form. To illustrate, in the Deschambault paste plant, emissions of 1mg/Nm3 of PAH 16 (according to the tests showed that PAH emissions grew six-fold after NS 9815 Norwegian Standard) – a level never before the introduction of a paste-cooler. The conventional achieved. Eolios was introduced at Qatalum in 2010. Prior treatment method is the dry scrubber process. It to this, it was first used at the Alcoa Moesjen Anode entails injecting coke fines in a gas stream loaded by Plant in Norway in 2007 – where a PAH destruction pitch fumes, resulting in absorption of the pollutants. efficiency improvement from 97 per cent to 99 per cent Pitch loaded fines are collected by a dust collector