PTQ Q3 2023 Issue

Technology in Action

can be balanced to control the reaction and reduce fuel consumption. In turn, this also reduces emissions of NOx, SOx, CO, and the greenhouse gas carbon dioxide (CO₂). Removing harmful substances from process gases ensures they cannot then be emitted by the plant. Typical examples of these applications include DeNOx (ammonia slip) treatment and flue gas desulphurisation, as well as dust abatement if required. In ammonia slip, ammonia (NH₃) or urea is used in either a selective catalytic reduction (SCR) or selective non-cat - alytic reduction (SNCR) process to suppress harmful NOx emissions created by combustion. Using insufficient NH₃ means NOx emissions are not properly suppressed, while an excess of only a few parts per million (ppm) leads to ammonium bisulphate (ABS) forma - tion. ABS can plug the catalyst in SCR processes, damaging equipment and reducing the value of the fly ash by-product. Measurement accuracy, therefore, is vital to both methods. A TDL analyser installed directly into the process ducts is the most effective analysis solution. This provides a highly sensitive, average measurement across the duct, so the NH₃ reading is accurate even when flow conditions are inconsistent. In late 2021, the US Environmental Protection Agency (EPA) strongly recommended that analysers used for con - tinuous ammonia (NH₃) monitoring in combustion emis - sions meet performance specification PS18. Although NH₃ is not currently regulated as a hazardous air pollutant under the Clean Air Act, some states regard it as a precursor to particulate matter of 2.5 microns (PM2.5) and find that 5 ppm NH₃ in emissions can cause eye and respiratory irritations. Many US state regulatory agencies are targeting the pre - cursors that create PM2.5 as a pathway to lower PM2.5 emission, so EPA PS18 looks set to become the basis of future regulation. Additionally, Procedure 6 (40 Code of Federal Regulations Part 60, Appendix F) states that all continuous emissions monitoring system (CEMS) equipment must also be able to perform daily quality tests. This has made it essential to avoid unnecessary down - time that can affect analyser validation and may in turn incur significant financial penalties. Flue gas desulphurisation (FGD) systems remove sulphur compounds (SOx, mainly SO₂) from exhaust gases – this process is often used by fossil-fuel power plants and waste incinerators. The flue gas is typically sprayed with a wet slurry of lime, which reacts with SOx and scrubs up to 95% of the SO₂ content from the gas. Measuring the SO₂ content before and after treatment ensures that any remaining sulphur compounds fall within regulatory limits and allows dosing to be accurately controlled.

Servomex to use gas analysis to support a comprehensive clean air strategy

The need to limit emissions of carbon dioxide (CO₂) and other greenhouse gases (GHGs) into the atmosphere has never been greater. Sustainable development and the move towards carbon net zero are among the most important challenges facing industrial operators. Clean air strategies, supported by effective and reliable gas analysis, are playing an important role in reducing harmful emissions from industrial operations. As a result, gas analysis suppliers are delivering inno - vative technological solutions that help their customers reduce their global resource consumption and decrease the emissions of atmospheric pollution. Additionally, research and development programmes are supporting clean air and hydrogen initiatives, which will be a key component in the reduction of global carbon foot - prints and emissions. Gas sensors and analyser systems will play an ever- increasing role in the technologies used to support low- carbon and carbon-free industries. Operating throughout industrial processes, these products already help to ensure greater efficiency, which in turn leads to fewer emissions and a cleaner environment. Typical industrial strategies for cleaner air A three-stage approach that focuses on combustion effi - ciency, gas clean-up, and emissions monitoring not only helps ensure cleaner air, but also optimises processes to deliver reduced fuel consumption and higher yields. With no realistic alternatives to combustion as a method of creating the high temperatures needed for many hydro - carbon processing applications, achieving an efficient reac - tion is key. In the combustion reaction, fuel is mixed with oxygen (traditionally from air) at the burner and ignited to create heat energy for use in the process. Typically, this reaction consumes a significant amount of fuel, creates potential safety hazards, and generates harmful emissions. Originally, fired heaters were run in conditions of high excess air. This was inefficient and increased the level of fuel consumption, but it did avoid the creation of unsafe, explosive conditions. A further disadvantage, particularly from the envi - ronmental perspective, is that excess oxygen (O₂) com - bines with nitrogen and sulphur from the fuel to produce unwanted emissions such as oxides of nitrogen (NOx) and sulphur (SOx). The development of gas analyser technology, however, has allowed the accurate measurement of oxygen and combustibles – principally carbon monoxide (CO) – within the combustion reaction. This means the air-to-fuel ratio

PTQ Q3 2023