更换分子筛时需要注意哪些事项？

 更换分子筛时需要注意哪些事项？塑料分子筛除湿机，分子筛干燥机，节通干燥机

# Precautions for Molecular Sieve Replacement 更换分子筛注意事项（中英双语） ## English ### 1. Safety preparation before disassembly 1. Shut down the whole dryer, turn off heating and fan system, cut off main power supply, and wait at least 2 hours for the tower to cool down completely to avoid scalding. 2. Close all air circuit valves, release residual pressure inside the adsorption tower. 3. Wear dust mask, gloves and goggles to prevent molecular sieve powder from irritating respiratory tract and eyes. 4. Prepare sealing gaskets, filter screens, new 3A molecular sieve, brush and vacuum cleaner in advance. ### 2. Cleaning the tower inner cavity thoroughly 1. Take out all failed molecular sieve, use vacuum cleaner to suck all powder and residues at the bottom and corner of tower. 2. Brush the internal partition, support net and air distribution plate to clear sticky dust and volatile carbon deposits. 3. Check the stainless steel filter screen at the bottom; replace if broken, hole-leaked or severely blocked to prevent new sieve leakage later. 4. Wipe the tower wall clean, make sure no oil, dust and old powder remain inside. ### 3. Filling requirements for new molecular sieve 1. Must use food-grade 3A molecular sieve dedicated for plastic drying; 4A sieve is forbidden for PET drying. 2. Fill the tower evenly while tapping the tower wall slightly to eliminate internal gaps and voids; avoid loose filling leading to airflow bias and uneven moisture adsorption. 3. Do not overfill or underfill; reserve a small expansion space to prevent sieve expansion blockage during regeneration heating. 4. After filling, install the top filter and pressing plate tightly to stop sieve powder from entering circulating air duct. ### 4. Sealing and air tightness inspection after assembly 1. Replace all aging rubber gaskets with new ones; old deformed gaskets will cause air leakage and dew point failure. 2. Tighten the tower flange bolts diagonally and evenly to avoid partial sealing gap. 3. After assembly, run the dryer without heating first, check all flange joints for air leakage with soap water. Stop and re-tighten bolts if air bubbles appear. ### 5. Pre-regeneration treatment before formal production 1. After replacement, run full regeneration cycle for 2–3 times continuously without feeding PET materials. Let the new sieve fully remove surface adsorbed moisture before putting into drying production. 2. Monitor dew point change in real time; only start feeding when dew point can stably reach -40℃~-50℃. ### 6. Daily protection after replacement 1. Strictly ensure compressed air is oil-free and dry; oil mist will quickly contaminate new molecular sieve and shorten its service life. 2. Clean primary and medium-efficiency air filters regularly to reduce dust entering adsorption tower. 3. Avoid long-term shutdown with high humidity air sealed inside the tower; empty material and keep low dew point circulation if stop production for more than one day. ## 中文对照 更换分子筛全过程注意事项 ### 一、拆机前**准备 1. 整机停机，关闭加热、风机，切断总电源，静置至少2小时让塔体完全降温，防止高温**； 2. 关闭所有气路阀门，释放吸附塔内部残余气压； 3. 佩戴防尘口罩、防护手套、护目镜，分子筛粉末易刺激呼吸道与眼睛； 4. 提前备好新密封垫、滤网、3A分子筛、毛刷、工业吸尘器。 ### 二、塔腔彻底清洁要求 1. 全部倒出失效旧分子筛，吸尘器吸净塔底、边角残留细粉； 2. 刷洗塔内隔板、支撑网、布风板，清理积灰与塑料挥发积碳； 3. 检查底部不锈钢滤网，破损、穿孔、严重堵塞必须换新，防止后续新分子筛漏粉； 4. 擦拭塔壁，保证内部无油污、粉尘、旧粉残留。 ### 三、新分子筛装填规范 1. 必须选用塑胶干燥专用3A分子筛，严禁使用4A分子筛用于PET除湿； 2. 装填时均匀倒入，轻敲塔壁消除内部空隙，装填疏松会造成气流偏流、吸水不均； 3. 不可装填过满或过少，预留少量膨胀间隙，避免再生加热后分子筛膨胀堵塔； 4. 装填完成后压紧顶部滤网与压板，防止分子筛粉末窜入循环风道。 ### 四、装配密封与气密性检测 1. 法兰橡胶密封垫全部换新，老化变形旧垫片会漏风，直接导致露点降不下去； 2. 对角均匀拧紧法兰螺栓，防止单边出现密封缝隙； 3. 装配完成后不开加热空载运行，肥皂水涂抹所有法兰接缝查漏，出现气泡需重新紧固。 ### 五、正式生产前预再生处理 1. 更换完毕后，空载连续运行2～3个完整再生循环，让新分子筛彻底脱除表面吸附水分，再投入原料烘干； 2. 实时观察露点，露点稳定达到-40℃~-50℃后，才能上料生产。 ### 六、更换后日常防护要点 1. 前端压缩空气必须保证无油干燥，油雾会快速污染新分子筛，大幅缩短使用寿命； 2. 定期清理初效、中效空气滤芯，减少粉尘进入吸附塔； 3. 长期停机不要让高湿空气封存在塔内；停产超过1天需清空原料，保持低露点循环运行。