Flue-gas cleaning equipment for bagasse-fired boilers to comply with new environmental regulations

Australia’s regulations on industrial air emissions set specific standards for boilers, requiring compliance with particulate emission limits based on the size and age of the equipment. The air release limits for bagasse fired boilers are part of a broader regulatory framework for air emissions within Queensland and New South Wales. Historic particulate limits for Queensland sugar mill bagasse fired boilers were typically up to 600 mg/Nm3 but varied depending on the size, location and operational conditions of the boiler and were specified in the environmental licence (NSW) or environmental authority (Qld) for the operation of the boiler. The increasing awareness of the health impacts of air emissions has seen the legislated particulate emissions limits being steadily tightened in recent years and itis likely that emission limits in Australia and other industries will become more stringent. A review of various flue gas cleaning technologies for bagasse-fired boilers in South Africa identified that not all technologies can meet the 120 mg/Nm³ limit for smaller boilers. For larger boilers, the 50 mg/Nm³ limit is particularly challenging, with only a few technologies providing viable options for achieving compliance when using sugarcane bagasse as fuel. These include venturi scrubbers, sieve-plate scrubbers, and electrostatic precipitators. Each technology has its own set of advantages and limitations, depending on the specific plant circumstances. However, for most applications, high-efficiency sieve-plate scrubbers are recommended as the most cost-effective solution, offering the lowest capital and operating costs.