Field Enhancements of Packed-Bed Performance for Low-Concentration Acidic and Basic-Waste Gases from Semiconductor Manufacturing Process

• Published in: Journal of the Air & Waste Management Association (1995) Vol. 55; no. 5; pp. 647 - 657
• Main Authors: Chein, Hung Min, Aggarwal, Shankar Gopala, Wu, Hsin Hsien, Chen, Tzu Ming, Huang, Chun-Chao
• Format: Journal Article
• Language: English
• Published: Pittsburgh, PA Taylor & Francis Group 01.05.2005; Air & Waste Management Association; Air and Waste Management Association; Taylor & Francis Ltd
• Subjects: Air Movements; Air Pollution - prevention & control; Air quality management; Applied sciences; Atmospheric pollution; Chemical engineering; Continental surface waters; Emissions testing; Environmental aspects; Exact sciences and technology; Facility Design and Construction; Gases; General processes of purification and dust removal; Hydrodynamics of contact apparatus; Natural water pollution; Pollutants; Pollution; Prevention and purification methods; Semiconductor industry; Semiconductors; Surface-Active Agents; Surfactants; Waste management; Water; Water treatment and pollution; United States; Packed bed; Emission content; Hydrodynamics; Blow down; Scrubbing; Surfactant; Pollutant emission; Operating conditions; Ionic liquid; Gaseous effluent; Liquid liquid flow; Chemical equilibrium; Pollutant; Vents; Manufacturing process; Surface water; pH; Air pollution
• ISSN: 1096-2247; 2162-2906
• DOI: 10.1080/10473289.2005.10464644

Low-concentration acidic and basic-waste gas pollutants contribute significantly in the total emission of a facility. Previous results show that the control of high volumetric flow rate (∼ 500 m 3 /min), low-concentration acidic (<1 ppm by vol) and basic (<3 ppm by vol) gases from semiconductor process vent, by conventional wet scrubbing technique is a challenging task. This work was targeted to enhance the performance of packed beds for high-volumetric flow rate, low-concentration acidic (HF, HCl), and basic (NH 3 )-waste gases from the semiconductor manufacturing process. The methodology used to meet the goal was the application of fine-water mist over the inlet stream before entering to the packed bed and use of the surfactant with mist/packed-bed liquid in low concentration. An experimental study was carried out in two acid-packed beds to optimize the operating conditions, such as pH of the liquid, circulating liquid flow rate, blow-down cycle, and so forth. The relationship among liquid pH, liquid ionic concentration, and the removal efficiency of the packed bed for the pollutants has been discussed considering chemical equilibrium, two-film theory, and Henry's law. For the potential utilization of scrubbing water, the dependency of the efficiency on blow-down cycle was studied, and a mechanism is suggested. The proposed water-mist surfactant system was installed in two acid-packed beds, and performance of the packed beds was compared. The background efficiencies of the acid-packed beds for HF, HCl, and NH 3 were found max to be (n = 11) 53, 40, and 27%, whereas after installation of the system, they increased significantly and became 76 ± 13% (n = 10), 76 ± 8% (n = 7), and 78 ± 7% (n = 7), respectively, for inlet concentrations of HF and HCl <1 ppm and NH 3 <14 ppm. The mechanism by which the surfactants operate to enhance the removal in scrubbing process is suggested considering the hydrodynamic effect and the interfacial effect with the charge-generating characteristic of surfactants on water surface, when dissolved into water. The results show that a proposed rectification system can effectively reduce the emission rates below the regulatory level (0.6kg/hr) at the present conditions of the facility.