Flue-gas-analysis products from Emerson Process Management, Austin, Texas, are helping maintain efficient operations at a combined heat and power (CHP) plant in Barry, South Wales. This cogen plant, owned by RWE Npower, Wiltshire, Swindon in the United Kingdom, supplies electricity, steam and treated process water to the adjacent Dow Corning manufacturing plant.

Close monitoring of the flue-gas oxygen levels by Emerson’s Rosemount brand analytical instruments is helping to maintain an overall efficiency rate of about 75 percent for the CHP plant. This means the plant uses substantially less fuel than conventional methods for generating heat and power, prompting the U.K. Department for Environment, Food and Rural Affairs to consider the plant a “Good Quality CHP.”

The 28 MW of generating capacity is developed from two 6.5-MW Tornado gas turbines and a 15-MW Thermodyn steam turbine. Multiple high-pressure waste-heat recovery boilers and low-pressure boilers also supply up to 250 tons of steam capacity to the Dow Corning site.

Rosemount’s instrumentation has been well established at the RWE plant, particularly for monitoring the boiler and process water treatment systems. After recent problems with the existing flue-gas analyzer equipment, RWE Npower installed the new oxygen transmitter on a trial basis. This zirconium-oxide-based unit is designed to be directly mounted into high-temperature flues. Its gas-analysis measurements are used to fine tune the burner air/fuel ratios for maximum efficiency and reduced NOX emissions. Following the successful completion of this trial, the plant installed more units.

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