Careers Paper Mill Saves $8Million+ on Recovery Boiler Maintenance
Commercial Impact of the Project
Compared to carbon steel tube panel ($11.1 million) and composite tube panel ($14 million) costs, IGS HVTS cladding saved the mill $8Million+ and critical path time. IGS installed the cladding within 10 days (compared to 25 days needed for replacement) to protect the recovery boiler from the future higher sulfur environment.
Problem
The mill’s capacity is expanding from 2300 to 3600 tons per day. A higher sulfur environment in the recovery boiler would have caused corrosion in the lower furnace zone.
The area of potential concern extends from the floor to just above the tertiary airport region of the boiler. Management evaluated composite panel upgrade, carbon steel replacement, and IGS HVTS cladding to mitigate future corrosion.
Solution
Due to significant cost savings, the plant commissioned the life extension project of existing carbon steel tubes with HGS HVTS cladding. The 34-foot-high area was protected on all four walls.
IGS commenced work on October 3, 2022, and completed it on schedule on October 13, 2022. IGS provided one hole watch on each shift, an air compressor, a forklift for material handling, and a specially designed boiler ventilation system to remove dust and gases.
Evaluation of Alternatives
Image: Solution Comparison
Key Benefits
Reliability
When the mill increases its throughput, the boiler tubes will be protected against an expected increase in sulfidation. Life extension in this more aggressive environment has eliminated the large capital expense of purchasing a new recovery boiler or replacing the lower furnace zone.
Longevity
IGS HVTS cladding is expected to protect boiler tubes for many years. If the plant sees corrosion moving higher in the boiler, IGS is prepared to add additional cladding during annual outages.
About the Pulp Mill
The mill’s parent companay is North America’s third largest producer of containerboard and cardboard boxes. The company operates eight pulp and paper mills and ninety corrugated products plants.
The mill in question has operated for over 50 years and employs more than 500 workers. It recently made a $440 million investment to convert a paper machine to produce liner board. They expect to optimize the mill’s profitability and viability for many years to come.
Recovery Boiler and Previous Maintenance Techniques
The mill operates a 750 psi Combustion Engineering recovery boiler commissioned in 1974. Over time they started to experience operational issues and thinning water wall tubes in the unit. In 2015 they replaced the boiler’s lower furnace zone with an Andritz lower furnace bottom.
Due to plans to expand the mill’s capacity from 2300 to 3600 tons per day production capacity, management had to decide whether to purchase a new recovery boiler or to protect the carbon steel tubes from an expected higher sulfur environment with cladding.
2024 Inspection
The recovery boiler was inspected after 16 months of operation where 99.6% of the HVTS cladding was in perfect shape. IGS conducted minor repairs on the 20sq.f. (of the original 4500 sq.f. application) cladding in the primary, secondary and tertiary airport tubes in the areas where IGS was not previously able to clad the entire tube where the inserts were not removed.
The Corporate Quality Control Manager said: “Very pleased with the initial application and inspection. We should have removed the inserts before the original application. We have also invited IGS to perform HVTS on additional areas of the boiler sections that we replaced. They did a great job completing the project on time and to a high standard.”
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