MIRA’s plant currently produces 62,000kW of electricity, sufficient to power over 50,000 homes and is fueled by solid waste. Once the municipal solid waste has been converted into a processed, refuse-derived fuel, it is used to power three steam boilers at MIRA’s power block facility. Two high capacity fans are used to transfer the odorous air from the refuse process facility into the boilers’ combustion furnaces, providing oxygen for the combustion process.
The combustion fans are located 25 feet from ground level and are exposed to harsh environmental conditions including snow, rain, dirt and widely fluctuating temperatures, which led to the breakdown of other types of shaft seals. Crucial to the functionality of the fan, the shaft seals maintain bearing lubrication and control condensation within the bearing housing, reducing wear, extending bearing lifespan and allowing for longer fan operation without maintenance. A set of two bearings cost an average of $15,000 to replace, and proper bearing maintenance and fan operation is critical to the viability of the plant.
Having to replace the bearing shaft seals every eight to 10 months, required significant maintenance time and money and caused plant downtime. MIRA decided to test the non-contact, centrifugal pressure design that is exclusive to Centritec Seals on one combustion fan. After one year of continuous and monitored operation, the bearings and the seal arrangement within the pillow block bearing (which were enclosed by Centritec Seals) show no signs of failure or impending failure.
While providing longer lifespan, Centritec Seals also provide better operational efficiency compared to other seal options, such as contact lip seals or hybrid seals, reports the company. By significantly reducing parasitic drag, Centritec Seals utilize up to 30 watts less power in their operation per seal, resulting in additional energy savings.
This trial has demonstrated that using the non-contact centrifugal pressure design allows for more breathability (to eliminate the build-up of moisture), better heat dissipation (allowing air flow through the fan housing) and an expanded tolerance of vibration (resulting in less wear on components), all crucial to the operation of the MIRA combustion air fan and the plant’s ability to successfully produce power.
“So far, after one year of use, the Centritec Seals are doing what we need them to do. They have been crucial in keeping the fans running smoothly”, says Rich Quelle, Chief Engineer of MIRA. “We certainly plan to continue to use Centritec Seals in the future.”
This article was submitted by Centritec Seals, a division of The Carlyle Johnson Machine Co. For more information, contact Doug Rode at firstname.lastname@example.org or 860-643-1531 ext. 117.