VOCs Abatement Evaluation of Supercritical Carbon Dioxide Green Spraying in Industrial Surface Coating
Source reduction of volatile organic compounds (VOCs) from industrial emissions is a core task for air quality improvement during China's 15th Five-Year Plan period. Supercritical carbon dioxide (ScCO2) spraying technology emerges as a cutting-edge VOCs abatement approach, as it reduces both VOCs content in coatings and coating consumption. However, empirical research on coating efficiency enhancement and VOCs emission reduction at demonstration scale remains scarce. This study selected three solvent-based coating systems widely used in Chinese industry: wooden furniture-polyurethane, wooden furniture-acrylic, and metal parts-fluorocarbon. A calculation method for ScCO2 spraying efficiency and VOCs emission reduction rate was established, and emission reduction performance was systematically measured. Results indicated that compared with high-pressure airless spraying, average coating efficiency improvement rates of ScCO2 spraying at spray distances of 60 cm and 40 cm across the three scenarios were (30.62±8.75)% and (31.74±12.83)%, respectively. Correspondingly, average VOCs emission reduction rates were (62.10±1.59)% (60 cm) and (53.73±11.78)% (40 cm). VOCs content reduction rates for the three systems were 46.03%, 23.80%, and 37.60%, respectively. Diluent addition was reduced from 60% to 10%, achieving a substitution rate of 83%. The study confirms that ScCO2 spraying can achieve significant reductions in VOCs and solvent emissions in wooden furniture and metal parts coating processes, providing empirical support for industrial promotion.