Sludge-Drying Ovens Monitored Digitally
The Daldowie sludge-drying plant plans to activate the communications technology of PlantWeb digital plant architecture to monitor calibration and performance. The project is part of the overall strategy of Scottish Water to invest in new technologies and advanced methods of recycling sewage sludge in keeping with the European Union's prohibition on sludge disposal at sea.
The sludge dryers are operated to ensure that oxygen levels are kept below the point at which gases and dust in the dryer atmosphere would allow combustion. The oxygen analyzers enable the sludge dryers to operate safely.
Daldowie will process the entire sewage output from the greater Glasgow area, which has a population of 1 million people creating up to 65,000 tons per year of waste-derived fuel. The fuel granules have a similar energy content to brown coal and can be burned at power stations for power generation.
In prior applications in other United Kingdom plants, the Rosemount oxygen analyzers have demonstrated tolerance to dirty, dusty, humid and sometimes wet conditions in drying ovens. More often applied to flue-gas monitoring for combustion control, the standard analog output calibration range covers 0 percent to 21 percent oxygen. The analyzer has three relay alarm outputs at adjustable concentration levels.