IMPROVING RECOVERY BOILER AVAILABILITY • THE MAHRT EXPERIENCE, 2010 TAPPI PEERS Conference

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An air system upgrade was implemented at the Mahrt mill number two recovery boiler (RB2). The implementation goals were to improve recovery boiler availability and efficiency by reducing the number of sootblowers in co-current use from four to two, and extending the run-time between water washes to at least twelve months. The mill determined that a continuous effort to improve boiler operations was required in addition to the air system upgrade to accomplish the desired goals; ranging from management of recovery cycle liquor chemistry to boiler tuning and implementation of a firing strategy using automatic control. As a result of these combined process improvements, the mill has achieved a reduction of as-fired black liquor chloride level by about 50%, a reduction in total combustion air and implementation of a system for automatic control of furnace excess oxygen at 2.0%, and increased total steam output to the header while sustaining the final steam temperature at superheater design. The goals of reduced co-current sootblower utilization and extended boiler run-time have been achieved through these process changes. This paper is a detailed review of the investigations and actions taken to accomplish these process improvements and their impact on continuous operations and goals.