Lyure Screw Press in Reed Papermaking Pulping

Introduction

The pulp and paper industry is increasingly leveraging non-wood fibers to meet the demand for sustainable and cost-effective raw materials. Reeds, a fast-growing aquatic plant abundant in wetlands across regions like China, India, and Eastern Europe, are an excellent alternative to wood pulp due to their high cellulose content and renewability. However, reed pulping presents challenges, including high silica content, fine fiber structure, and significant ash residues. The Lyure Screw Press, developed by our company, is an advanced solution designed to optimize reed pulping processes. This article examines the application of the Lyure Screw Press in reed papermaking pulping, its operational principles, benefits, and its impact on the industry.

Challenges of Reed Pulping

Reeds are lignocellulosic materials composed of cellulose, hemicellulose, and lignin, with a high silica content (5–10% in black liquor) and ash (up to 15%). These properties complicate pulping, causing issues such as equipment corrosion, inefficient black liquor recovery, and environmental concerns from chemical-laden wastewater. The fine and short fibers of reeds also result in poor pulp drainability, increasing water and chemical consumption. Effective black liquor extraction and pulp washing are critical to producing high-quality reed pulp while minimizing environmental impact.

The Role of Lyure Screw Press in Reed Pulping

The Lyure Screw Press is a cutting-edge single screw press tailored to address the unique challenges of reed pulping. Positioned after the digester or blow tank, it performs dewatering, black liquor extraction, and pulp washing. The Lyure Screw Press is engineered to handle the high silica and ash content of reed pulp, ensuring efficient processing and consistent pulp quality.

Working Principle

The Lyure Screw Press operates through mechanical extrusion using a single screw with variable pitch and diameter. The reed pulp slurry, with an inlet consistency of 3–10%, is fed into the press. As the screw rotates within a perforated filter frame, the pulp is compressed, reducing the slurry volume. This forces black liquor and water to exit through the filter plate, concentrating the pulp to an outlet consistency of 25–35%. The press operates in three zones:

• Low-pressure zone: Initial dewatering removes free water and fine particles.

• Medium-pressure zone: Increased compression separates additional black liquor.

• High-pressure zone: Maximum compression produces a dense pulp cake with high dryness.

A proprietary pneumatic back-pressure system stabilizes pulp output, preventing clogging and ensuring reliable performance. The Lyure Screw Press features a specialized filter design to manage the fine fibers and high ash content of reeds, enhancing dewatering efficiency.

Applications in Reed Pulping

The Lyure Screw Press serves multiple functions in reed pulping:

1. Black Liquor Extraction: It removes up to 85% of black liquor from reed pulp, reducing silica, ash, and lignin residues. This improves black liquor recovery and minimizes environmental pollution.

2. Pulp Washing: The press efficiently washes the pulp, removing residual chemicals and impurities, enhancing pulp quality and reducing chemical use in subsequent bleaching stages.

3. Pulp Concentration: By increasing pulp consistency, the Lyure Screw Press prepares the pulp for downstream processes like bleaching or paper formation, optimizing water and energy usage.

Benefits of Lyure Screw Press in Reed Pulping

The Lyure Screw Press offers numerous advantages, making it indispensable for reed pulping:

1. High Dewatering Efficiency: With a black liquor extraction rate of 83–88% for reed pulp, the press produces a drier pulp cake, reducing energy costs for drying.

2. Environmental Sustainability: Efficient black liquor separation minimizes the release of harmful pollutants and greenhouse gases. The enclosed design prevents odor and liquor overflow, improving workplace safety.

3. Cost Efficiency: Operating at low rotational speeds, the Lyure Screw Press consumes minimal power and requires low maintenance. Its washing efficiency reduces chemical and water usage, lowering production costs.

4. Versatility: The press is adaptable to various non-wood fibers, including reeds, bagasse, rice straw, and wheat straw, making it suitable for diverse pulping applications.

5. Stable Performance: The non-clogging filter and anti-slip screw design ensure consistent operation, even with the challenging properties of reed pulp, such as high silica and ash content.

Impact on the Pulp and Paper Industry

The Lyure Screw Press has transformed reed pulping, enabling pulp mills to utilize this abundant and renewable resource effectively. In regions like China’s Jiangsu Province, India’s wetlands, and Eastern Europe, where reeds are plentiful, the press has facilitated the production of high-quality paper products, including writing paper, printing paper, and packaging materials. By reducing reliance on wood fibers, the Lyure Screw Press supports sustainable forestry practices and contributes to a circular economy.

Economically, the technology benefits local communities by creating a market for harvested reeds, providing income for farmers and reducing environmental degradation from uncontrolled reed growth in wetlands. The Lyure Screw Press also supports the scalability of modern pulp mills, allowing them to blend reed pulp with recycled or wood pulp to meet diverse market demands.

Challenges and Future Innovations

While the Lyure Screw Press excels in reed pulping, challenges remain. The high silica and ash content of reeds can cause equipment wear, requiring robust materials and periodic maintenance. Optimizing press parameters, such as screw speed and filter mesh size, for specific reed varieties is an ongoing focus. Looking ahead, Lyure is investing in innovations to enhance screw press performance, including advanced filter materials to handle fine fibers and smart control systems for real-time process optimization. Integration with eco-friendly pulping methods, such as soda pulping or organosolv processes, is also a priority to further reduce environmental impact.

Conclusion

The Lyure Screw Press is a pivotal technology in reed papermaking pulping, overcoming the challenges of high silica, fine fibers, and environmental concerns. Its efficient black liquor extraction, pulp washing, and concentration capabilities make it a cornerstone of sustainable pulping processes. By enabling the use of reeds as a viable raw material, the Lyure Screw Press supports resource conservation, cost efficiency, and economic development in reed-rich regions. As the pulp and paper industry continues to prioritize sustainability, the Lyure Screw Press will play a critical role in shaping a greener, more efficient future.