Overview
Pulp cooking is the industrial process of breaking down lignocellulosic materials (e.g., wood, bamboo) to isolate cellulose fibers for paper production. It involves treating raw materials with chemical solutions under controlled temperature and pressure. The two dominant methods are the Kraft (alkaline) and Sulfite (acidic) processes, accounting for over 80% of global pulp production. This process not only separates fibers but also removes lignin, hemicellulose, and other impurities. The choice of method depends on raw material type and desired pulp quality. Modern systems often integrate energy recovery and chemical recycling to improve sustainability.
Physical and Chemical Properties
Kraft cooking uses a mixture of sodium hydroxide (NaOH) and sodium sulfide (Na₂S) in water, creating a highly alkaline solution (pH 13-14) that operates at 150-170°C. The Sulfite process employs sulfurous acid (H₂SO₃) or its salts at pH 1.5-5 and 120-150°C. Both processes require pressurized digesters to maintain liquid state at high temperatures. Key reactions include lignin depolymerization and saponification of resins. The Kraft process yields darker but stronger fibers, while Sulfite produces lighter-colored pulp. Cooking time ranges from 1-4 hours depending on chip size and desired delignification degree.
Main Applications
Over 90% of cooked pulp supplies paper mills for manufacturing printing/writing paper, packaging materials (e.g., corrugated boxes), and specialty products like tissue. High-purity dissolving pulp from cooking is used for rayon, cellophane, and bioethanol production. Emerging applications include nanocellulose for composites and biomedical uses. Byproducts like tall oil (Kraft) and lignosulfonates (Sulfite) are valorized in adhesives, dispersants, and vanillin synthesis. The process is integral to circular economy approaches in the forestry sector.
Safety and Storage
Cooking chemicals require strict handling: NaOH causes severe burns, while H₂SO₃ releases toxic SO₂ gas. Facilities must have emergency showers, acid/alkali spill kits, and gas detectors. Digester pressure vessels undergo regular ASME inspections to prevent explosions. Chemical storage follows NFPA standards: NaOH in polyethylene-lined steel drums, Na₂S in airtight containers to prevent oxidation. Spent cooking liquor ('black liquor' in Kraft) is immediately processed in recovery boilers to prevent sulfide emissions. Personnel need acid-resistant suits, face shields, and respiratory protection during maintenance.
B2B Procurement Guide
Industrial buyers should evaluate suppliers based on chemical purity (e.g., 99% NaOH flakes), logistics capability for bulk shipments (railcars/tank trucks), and sustainability certifications like ECOLABEL. For equipment, prioritize digester manufacturers with ASME U-stamp certification and energy-efficient designs. Key contract terms include: minimum 98.5% Na₂S content for Kraft plants, mercury limits below 0.1ppm in Sulfite chemicals, and INCOTERMS specifying temperature-controlled transport for liquid reagents. Spot prices fluctuate with energy costs; long-term agreements often provide 5-15% cost stability.
Related Manufacturers
- 主营：高压釜、反应釜、压蒸釜、强力蒸压釜、法兰蒸养釜、加砌块蒸养釜、混凝土蒸压釜
- 主营：锅炉、蒸压釜、除氧器、布袋除尘器、分气缸、储气罐、蒸汽发生器、除渣机、加气砖生产线
- 主营：化机浆设备、挤浆机、高浓磨浆机、蒸煮管、螺旋压榨脱水机、料片筛选机、脱墨机、双螺杆搓丝机、挤压撕裂机、单螺杆浓缩脱水机、大型预蒸螺旋机、洗涤机、双网挤浆机、单螺旋压榨机、浆料浓缩机、双螺旋挤浆机、脱墨废水浮选机、单螺旋挤浆机
- 主营：硫化碱、硫化钠、硫化钠溶液、造纸蒸煮剂、硫氢化钠、硫化锰、硫氢化钠溶液、多硫化钠、沉淀硫酸钡
- 主营：非离子表面活性剂、一乙醇胺、二乙醇胺、三乙醇胺、乙二醇单丁醚、二氯甲烷、壬基酚聚氧乙烯醚、硫脲、苯酚、氨基磺酸、亚硫酸氢钠、硼酸、甲酸-94%、磷酸、异丙醇、乙二胺、氢氧化钠、氢氧化钾、一异丙醇胺、二乙胺、磺酸、二乙烯三胺
- 主营：炉门框、支撑板、炉底垫板、耐磨衬板、耐热滑轨、高温炉板、退火托盘、耐热钢滑块、箱式炉炉底板
- 主营：贝壳粉、氧化铁、填充剂、萤石球、海泡石、火山石、沸石粉、加重剂、电气石、金刚砂、金云母、碳酸钙、麦饭石、修复剂、夜光粉、鹅卵石、夜光石、石英砂、萤石粉、造纸木粉、耐火材料、园艺造景、粉体材料、煅烧工业、轻质绝热
- 主营：竹浆蒸煮设备、蒸煮管、高浓磨浆机、双螺旋分丝机
- 主营：管中泵、不锈钢深井泵、温泉泵、海水泵、管中泵维修、变频供水设备
- 主营：自吸泵、防爆磁力泵、锅炉给水多级泵
- 主营：双层筛、微滤机、磨浆机、蒸煮管、喂料机、压榨脱水机、陶瓷过滤机
- 主营：捕收剂、浮选剂、硫化矿、蒸煮剂、萃取剂、液体松香、稀土镍钴、苯氧肟酸、苄基胂酸、水杨羟肟酸、氧化石蜡皂、丁基钠黄药、磷酸二异辛酯、金属氧化矿物、乙二胺磷酸盐、硫铁矿的抑制剂、冶金行业螯合剂、医药中间体
- 主营：不锈钢BA管、不锈钢EP管、不锈钢卡套管、纸浆厂蒸煮器、不锈钢气源管、不锈钢高压管、不锈钢英制管、不锈钢洁净管、不锈钢TUBE管、不锈钢光亮管、不锈钢仪表管、光亮退火管、高纯气路管道、脱脂不锈钢管、超高压不锈钢管、水刀高压管、电解抛光管、内孔光亮管
- 主营：润滑油、汽油泵、水分析仪、丙烯树脂、阻燃面料、3d检测系统、挠性联轴器、电压测试仪、图像分析系统、集成电路测试