Precision Energy Services, Inc. (PES) of Hayden, Idaho, recently designed and supplied a recycled paper mill sludge-to-energy system for Atlantic Packaging in Ontario, Canada. This system is designed to process 100,000 tons of paper mill sludge per year that was previously being sent to local area landfills. The system eliminates the cost of sludge disposal and reduces the cost of fossil fuels by the offset generation of plant steam, the company says.
PES designed the system to supply the necessary energy in the form of hot gas to dry the 60 percent + MC wet basis sludge to 40 percent MC wet basis with the majority of the energy produced from the sludge used to generate process steam. The combined energy is produced from a single PES system without the use of natural gas. Natural gas is only used for startup of the system to obtain the required temperature for sludge feeding.
Producing process steam from the sludge-waste residuals, or biomass, promotes the plant’s green energy independence and the company’s green recycling plan by reducing the volume of waste sent to landfills.
The PES system receives the incoming sludge and processes it through PES’ proprietary fluid bed technology, which combusts the sludge, leaving only an ash that is white in color with no carbon residual. This ash is collected from nine points throughout the boiler, economizer, air heater, multiclones and baghouse and is conveyed pneumatically to an ash silo. The ash system was designed and supplied by PES to have no rotary valves, which are a constant maintenance issue on biomass boilers, the company says. The sealed ash system conveys all of the fly ash to a sealed ash silo for unloading into sealed trailers. This feature ensures that the complete boiler system is sealed from the point the fuel is pneumatically conveyed into the fluid bed combustor, providing a clean plant environment.
The ash is held in the ash silo for pickup by a nearby cement plant where it is utilized as an admixture to the concrete manufactured by the plant. The beneficial utilization of the ash from the sludge is a major advantage to the plant as there is not a requirement for ash landfilling.
The system was the second such plant PES designed for Atlantic Packaging, who commissioned the first in 2011 to replace a combustion technology that was unable to reliably burn the facility’s wet paper mill sludge.
“We are excited to announce that our client’s second sludge-to-energy plant was completed in early 2017. Our client will see a sufficient reduction in the plant’s overall waste disposal cost as well as a major reduction of their energy costs by the savings obtained in burning the biomass fuel to produce steam, offsetting the use of natural gas,” Mike Oswald, president of Precision Energy Services, says.