At the core of any pulp and paper mill is the recovery boiler – which drives the chemical recovery process that enables the mill to break down wood into pulp. As a crucial component, its performance and reliability directly impact the mill’s overall efficiency. Maintaining and optimizing this key equipment often presents challenges, especially when upgrading or retrofitting older facilities.
In fact, the recovery boiler often limits a mill’s capacity, and a failure can halt operations entirely. Regular maintenance and strategic upgrades remain essential for ensuring maximum uptime and efficiency. Here are three best practices that can help drive and optimize performance.
1. Leverage New Technologies for Enhanced Performance
Advances in recovery boiler technology, such as bottle headers and high crown seals, can offer more durable and reliable solutions. Older economizers used cross-header systems with numerous welds that increased the risk of tube leaks. The bottle header system provides a streamlined design that can help reduce maintenance needs and prolong the life of the equipment.
Issues like dust buildup and weak seals can often create operational challenges in the penthouse or upper section of the recovery boiler. High crown seal technology helps address these problems by welding directly to the tubes, creating a tighter, more effective seal that prevents dust accumulation and reduces maintenance requirements.
Building a WINGEMS model of the liquor recovery system can further optimize recovery boiler performance and system integration. White liquor, the main ingredient in the kraft pulping process, undergoes a series of unit operations to recycle black liquor back into white liquor. Each of these operations—such as concentration, burning, chemical transformation, and clarification—relies on various utilities, chemicals and equipment. By utilizing a heat and material balance program like WINGEMS, mills can analyze these unit operations individually and as a system to identify efficiency improvements and cost savings. For example, modeling a recovery boiler can help determine how changes in solids impact green liquor capacity and quality, steam generation and stack emissions.
Additionally, critical systems such as attemperation, tube handcuffs, metallurgy, non-destructive testing inspections, and steam blow cleaning need to be considered in a boiler rebuild.
2. Prioritize Maintenance in Project Design
For recovery boiler projects, especially retrofits, incorporating maintenance planning early in the design phase can greatly enhance long-term performance. Pulp and paper leaders and EPC teams should prioritize access to critical areas and safe working conditions for maintenance and outages. By integrating these considerations into the boiler update design, mills can streamline servicing and cleaning, helping to reduce operational downtime.
3. Achieve Long-Term Efficiency and Reduced Downtime
Partnering with an experienced EPC firm is critical for maximizing the efficiency and reliability of recovery boilers. By implementing the latest technologies and planning maintenance from the design phase, an expert like S&B ensures consistent operations, minimizes unplanned downtime and reduces maintenance costs.
S&B’s extensive experience optimizing recovery boiler systems provides mills with best practices for chemical cleaning and system enhancement, helps address common challenges and improves overall performance. An S&B team can guide a mill through the tedious process of project development and estimate all the way through startup and commissioning.
Learn more about S&B's expertise in the Pulp and Paper industry here.
