Fluoride emissions monitoring in aluminum smelters - Manufacturing, Other

Production of aluminum from its ores at aluminum smelters results in carbon dioxide CO2, carbon monoxide CO, sulfur dioxide SO2, and hydrogen fluoride HF gas emissions during the electrolytic process phase to the atmosphere. The gas emissions need to be monitored. Typically the smelters have emission limit values (ELVs) for sulfur dioxide and hydrogen fluoride emissions. These emissions should be measured accurately and with good precision, to ensure the smelter does not exceed its emission limit values. In addition several fluoride compounds may be produced in the electrolytic bath in the event of an oxygen shortage. These compounds include carbon tetrafluoride CF4, hexafluoroethane C2F6, sulfur hexafluoride SF6, and silicon tetrafluoride SiF4.

These additional emission components are problematic, as they have high Global Warming Potential (GWP) values. The GWP is a relative measure designed to demonstrate how much heat a greenhouse gas (GHG) traps in the atmosphere. Emission of one kilogram of carbon tetrafluoride into the atmosphere today has the potential of heating the atmosphere as much as 7,000 kilograms of carbon dioxide over the next 100 years.

The Gasmet FTIR Gas Analyzers provide accurate analysis of all above-mentioned gases both in through its simultaneous multicomponent monitoring capability. Gasmet’s tried and tested technologies have been incorporated into the GasmetCEM II measurement system, which is specifically designed and certified as a Continuous Emissions Monitoring System (CEMS). The system operates using extractive, hot-and-wet gas sampling method. The same core technology has also been made portable in the form of Gasmet DX4000 FTIR Gas Analyzer, which is an ideal solution for short-term measurement campaigns. An alternative to the CEM II system is offered in the form of Gasmet In-Situ FTIR Gas Analyzer, which omits the extractive sampling. Instead the gas sample cell is inserted directly into the stack or process gas channel, so the measurement is done in the spot where the sampling would otherwise take place.