Plant maintenance, test + measurement
Managing emissions in on-site boilers Requirements to manage industrial emissions are shiing. Local manufacturers face rising carbon taxes and tightening restrictions from first-world economies. Dennis Williams, Commercial Director of steam and boiler operations and maintenance service provider Associated Energy Services, says, “The South African government aims to push towards global standards in this space – but it might be diicult for South African industries to carry the financial burden. AES can identify opportunities and provide the insights businesses need – for short- term benefits and to prepare for the future.”
W illiams adds that there has been a tightening of local regulations around combustion and boilers, aecting nitrous oxide (NO x ), sulphur oxide (SO x ) and particulate emissions. Legislation relating to Small Boilers as Controlled Emitters (part of South Africa’s National Environmental Management Act: Air Quality Act, 2004) sets 10 megawatts of thermal input as the base threshold for the current limits. Existing boilers have specific timeframes and emissions standards for compliance. New boilers have slightly lower emissions standards, and all aected boilers have to undertake annual isokinetic emissions tests. As more stringent particulate emissions standards are typically the most diicult to achieve, many AES clients have upgraded the back-end of their plants, introducing various abatement technologies: “For new boilers, we have seen some uptake of alternative technologies such as bag filters. These come with specific operational and maintenance-related challenges and can be capital and operating cost-intensive. Other options – high- eiciency grit arresters, or high-eiciency multi-cyclones – are the preferred route on new plant and equipment,” Williams says. Emissions interventions While equipment interventions can deal with particulate emissions (visibly smoking stacks and soot particles in the air), SO x and NO x emissions are usually combustion process related. Very high combustion temperatures can be controlled by adjusting the combustion settings, to achieve lower NO x readings in the flue gas. SO x emissions can be managed by changing the fuel source. With coal, there should be less than 1% sulphur in the fuel composition. Users of heavy furnace oil (HFO) need to clean up their flue gas to address SO x – as well as particulates. However, grit arresters which control particulates cannot address SO x , NO x or CO 2 emissions – and as HFO typically contains 3% sulphur, users have to convert to more expensive fuel oils with a lower sulphur content. At present, Williams points out that there is no industrial- scale commercially viable mechanical or process intervention to mitigate carbon dioxide (CO 2 ) emissions. The only remedy is to use a ‘greener’ (lower carbon) fuel. For example, in natural gas, the hydrogen content is higher than in coal. Alternatively, there are renewable fuels – such as biomass – where the CO 2 emitted is viewed as being part of a circular carbon cycle. Emissions management successes AES has already assisted a number of companies to reduce their emissions. In one case, a food producer needed to replace very old boiler plant, where fuel usage was high and particulate
Combustion control is critical to reducing emissions.
A high efficiency multi-cyclone helps mitigate particulate emissions.
18 Electricity + Control FEBRUARY 2026
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