印刷工業揮發性有機物排放特性探討

本研究主要為探討印刷業之揮發性有機污染物（VOCs）的排放方式、排放來源、及其可行之削減方式，著眼在原物料運送儲放及製程方式，探討經濟及技術可行的方法進行減量效益計算。印刷業通指從事印刷及加工技術服務之產業，印刷工業依印版形式可分為平版印刷、凸版印刷、凹版印刷、網版印刷等。印刷業VOCs污染主要來自於印刷油墨、清洗溶劑、保養用溶劑等。污染源為原物料保存時之逸散，調色或注料時之VOCs逸散；印刷過程中之逸散，主要為印刷機、烘乾機、調墨作業等機具及設備清潔作業。揮發性有機污染物含量與其被印材質及印刷速度有關，其印刷速度越快，要求之乾燥速度越快，則油墨中揮發性有機溶劑含量也越高。本研究選擇國內三家印刷廠，從原物料、製程、作業管理及管末端的VOCs著手，探討可行的削減方法或技術。案例一業者並無污染控制設備，VOCs的產生源主要來自印刷機所使用的油墨，與清洗機具用的清潔劑，雖然廠內之作業場所設有抽氣裝置，但抽氣口並未直接針對印刷機抽取VOCs，有些是散熱用的抽氣口，有些則是針對粉體進行抽氣，導致VOCs直接逸散於作業場所，建議將抽氣口加大並放置在油墨槽上方，可提升抽氣效率，預估油墨VOCs逸散量約為20%(本廠的油墨屬低揮發性，大都殘留在印刷品上)，抽氣效率70%，可收集油墨中的VOCs 為2.01 ton/yr。逸散的VOC另ㄧ主要來源為清潔劑的使用，每年8.880 ton/yr，要增加清潔劑VOCs的收集效率，可選擇在機具清洗過程，機具做適當的圍封，再啟動抽氣裝置，收集效率預估可達50%，可收集4.44 ton/yr，總收集量共可達2.01 ton/yr +4.44 ton/yr=6.45 ton/yr。此方案藉由氣罩的裝設能有效增加VOCs收集效率，進而減少VOCs之逸散量，若僅收集而無控制設備，亦無法降低VOC的總量，當然也無法節省空污費。建議在後續設活性碳吸附塔，操作費用與設備投資及折舊利息每年為500,613元，年空污費節省58,080元。案例二業者已申請通過自廠排放係數，該廠年繳交VOCs空污費達618,912元/年。本廠目前未設置抽氣集氣處理設備，因此以排放係數估算出之逸散量即為其年VOCs排放量。建議先在不妨害作業之情況下，沿著印刷機兩側邊欄竿設置透明之圍幕一直達到印刷機之上方裝置一抽氣罩，集氣率80%，根據進氣濃度，後續選用生物過濾法或蓄熱式焚化爐為較經濟之處理方案，利用生物濾床去除效率達80%，年繳VOCs空污排放費為85,320元，足足省下426,720元的空污排放費，但操作電費與設備投資及折舊利息的費用達529,000元。案例三的業者從事印刷業已有70幾年歷史。依照目前的營運現況，以質量平衡計算其溶劑逸散量為 0.182噸/月（=0.55噸/季），小於每季1噸之標準量，其減量空間已不大。

關鍵字

印刷業；揮發性有機物；排放係數；質量平衡；有害空氣污染物

並列摘要

The purposes of this study was to understand the characteristics of VOCs emission from printing industry (including the emission approaches, emission sources and feasible reduce methods of VOCs. Besides, the reduction efficiencies of VOCs from delivery and storage of raw materials and the process by the economic and technical feasibility methods were evaluated. According to the form of plate lithography, the printing industry can be divided letterpress printing, gravure, screen printing and so on. VOCs pollution release from the solvent of ink, cleaning reagent , and maintenance reagent during the storage of raw materials, coloring, addition of materials. The VOCs of process release from printing, drying machine, the equipments of ink adjustment and machinery of cleaning operations. In this study, possible VOCs reduction methods or techniques were valuated from raw materials, processes, operation management and control at the end of three printers selected. Case one the VOCs generated from the printing ink, and cleaning agents without pollution control equipment. The exhaust devices of plant's workplace were used to extracted powder and heat not for the VOCs of printing machine directly, so VOCs directly emitted in the workplace. It is recommended to increase the exhaust port placed in the top of the ink tank, and to improve the exhaust efficiency. 20% release of VOCs of ink and 70% extraction efficiency were estimated; therefore 2.01 ton / yr VOCs can be collected. Another VOCs release source was cleaning reagent, which was used with 8.880 ton / yr. To reach the collection efficiency of VOCs from detergent and the appropriate enclosure equipment was used during cleaning process before starting pumping device. The 4.44 ton/yr release VOCs can be collected under 50% collect efficiency. The total collected amount of VOCs was 6.45 ton / yr( 2.01 ton / yr +4.44 ton / yr). But the total amount of VOCs cannot decrease without treatment facilities, an activated carbon adsorption tower was recommended, and its operating costs and interest of equipment depreciation was 500,613 per year. The annual savings in air pollution fee was 58,080 dollars. Case two has been allowed to use the emission factor from the factory, and the VOCs air pollution fee was paid up to 618,912 dollars per year. Our collection is currently not set the exhaust gas processing equipment, and therefore out of the oven emission factor to estimate the amount that its annual emissions of VOCs. The emission factors were used to estimate the release amount of VOCs, which equals the emission amount without equipments of collection and treatment.If the curtain is set along the both sides of printing machine to the top of the device, an exhaust hood can collect 80% of release VOCs. Biological filtration or regenerative incinerator can be selected to degradation VOCs under consideration of inlet VOCs concentration. The removal efficiency of VOCs is 80% by bio-filter bed to save VOCs emission fees at 426,720 dollars per year. Case three has operated for 70 years in printing industry. In accordance with the current operating condition, the amount of VOCs escaping is 0.182 tons / month (= 0.55 tons/season) with the calculation of mass balance. The amount is less than one ton of standard amount quarterly.