Damaged Boiler Becomes More Efficient
November 6, 2009
After a packaged boiler explosion at one of its plants, a major Canadian paper mill asked Coen Co. Inc., Foster City, Calif., to replace the unit’s burner but use as much of the original undamaged equipment as possible. In addition to the repair, the mill desired improved performance, which would eliminate flame impingement on the boiler tubes, and provide increased operating turndown and greater oil-flame stability.
Coen supplied an adjustable louver Dual Air Zone (DAZ) burner firing No. 6 oil on a Volcano D-type boiler with 75,000 pph capacity.
To reduce costs, Coen’s engineers reused the existing windbox, fan, inlet-vane damper and fuel piping. To improve air distribution, Coen designed new windbox baffles. The old burner lacked a refractory throat and register air adjustments, so Coen supplied an adjustable-louver dual-air-zone burner with a shaped refractory “Fyr Form” throat to improve the oil-flame shape and stability at all firing rates on the tight packaged boiler design. A fully adjustable atomizing steam valve was added to improve turndown.
At startup, the burner achieved greater than a 13:1 turndown with no stability problems. Particulate measurement showed a low 21 mg/MJ (0.045 lb/MBTU). NOX measured 234 ppm max, which is substantially under the regulation limit of 325 ppm for heavy fuel oil.