Paper Industry Industrial Boiler EN 1.4306 Alkali Recovery Boilers For Pulp

High-Efficiency Alkali Recovery Boilers for the Pulp and Paper Industry

• Operational Stability: The units provide exceptionally stable combustion with a wide load range of 60% to 110%, ensuring high availability of up to 350 days per year and a service life exceeding 30 years.
• Severe Corrosion Protection: To combat the highly corrosive environment of the lower furnace, the membrane water walls below the 500mm elevation of the primary air outlet are welded from specialized, highly resistant materials including SAN38 and Alloy 825. Carbon steel combined with EN 1.4306 is utilized for the remaining lower composite pipes.
• Advanced Superheater Integrity: The superheater is designed with an efficient cooling ring, a swallowtail groove bite structure, and a whole-body sealing box with secondary sealing technology. This guarantees that the tubes do not burst, scatter, or leak smoke, maintaining an oxygen level of O2 ≤ 3.5% in the sealing box.
• Safe and Rapid Control: The system operates safely using advanced DCS (Distributed Control System), BMS (Burner Management System), and SIS (Safety Instrumented System), allowing for a fast cold startup time of approximately 8 hours.

• Multi-Stage Air Supply: The boiler features an optimized air supply system divided into primary air, lower secondary air, upper secondary air, and tertiary/fourth air levels to ensure sufficient and stable combustion. The air hoods are precision cast to be high-temperature and corrosion-resistant, ensuring uniform air supply with low resistance.
• Black Liquor Atomization: The fuel is injected using corrosion-resistant stainless steel spray guns. These are engineered via simulation design to ensure perfect atomization, preventing wall-hanging and ensuring the proper formation rules of the combustion cushion layer.
• Strict Emissions Compliance: Flue gas treatment is handled by a high-efficiency Electrostatic Precipitator (ESP) featuring two chambers with no less than four electrical fields each. Guaranteed emissions (corrected to 6% O2) are strictly controlled: Dust ≤ 20mg/Nm3, SO2 ≤ 50mg/Nm3, and NOx ≤ 200mg/Nm3.

• How does the boiler prevent leakage in the generating banks and economizers? Our boiler banks and economizers utilize a fully welded membrane tube structure (carbon steel pipes with fins). The connection nodes between the pipes and headers are fully welded to prevent any leakage, and the internal integrity of small headers is verified via strict endoscopic examinations.
• How is the alkali ash handled and recycled? Alkali ash deposited on the boiler is dislodged by 32 retractable steam soot blowers. The fly ash in the flue gas is also captured and vibrated by the electrostatic precipitator. This ash falls into ash buckets and is sent to an alkali ash dissolving tank, where it is ultimately pumped into the green liquor tank to be entirely recycled back into the caustic chemical section.
• Is the boiler suitable for outdoor installation? Yes, this is designed as an outdoor boiler. To protect critical upper components, we set up robust furnace roof canopies over the all-steel structural framework.