Emission characteristics and control efficiency of acidic and basic gases and aerosols from packed towers

Tsai, Chuen-Tinn; Chang, Chang Tso; Liu, Tsing Wei; Huang, Chun; Chien, Chih Liang; Chein, Hung Min

doi:10.1016/j.atmosenv.2003.10.002

Cited by 15 publications

(17 citation statements)

References 4 publications

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“…The prior researches point out that the wet scrubbers in the semiconductor factories result in the low removal efficiency when the inlet concentration is lower than 1 ppm. 10 To improve the low inlet concentration removal efficiency, Chen retrofitted a mist spray module to promote mass transfer efficiency of air washing under different working conditions such as Qg/Ql, washing pH value, and conductivity. The serial experiments showed that added module of the spray tower increased the removal efficiency.…”

Section: Model Confirmation Confirmation From Experimental Plantmentioning

confidence: 99%

A rapid tool for emission outlet concentration simulation of scrubber and make-up air unit at different inlet concentrations

Kuo

Chuang

Chang

2017

Building Services Engineering Research and Technology

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Currently in the cleanroom-related industries, both the air quality of indoors intake and outdoors emission should be controlled at a certain level. Wet scrubbers and air washers are the main facilities to clean up air for the process required. However, previous studies have found that these devices typically have lower removal efficiency for low inlet concentration contaminations; little information is available to explain the efficiency deterioration and only on the empirical basis. A theoretical model is proposed, which applies Fick's second law to derive a rapid efficiency simulating formula. This model is different from the empirical equations of former studies, and is able to describe the relationship between the inlet concentration and removal efficiency of the air washing facilities. Moreover, the calculation time of the nonlinear recurrence equation is effectively lessened by the Euler equation and proven to be practical and concise for the rapid efficiency determination. Confirmation of the simulation formula was conducted by using the experimental data from the previous studies of the wet scrubber and in situ historical record of a make-up air unit. In this article, we describe how an outlet concentration and removal efficiency can be predicted using a generic simulating formula, leading to better design with less effort. The proposed model and equation minimize the design complexity and help to optimize the sizing and operational control of the air washing facilities. This not only decreases the construction and operating costs, but also lead to better energy usage. Practical application: Engineers can use the output of this paper to optimize air washer facility designs instead of intuitively extending the rinsing duration or enlarging the scale of the equipment. The model can be applied to both residential and industrial air washers to predict the efficiency and evaluate the performance. It also allows the quantitative analysis and risk assessment of an abrupt air washer breakdown in the clean manufacturing industries.

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Section: Model Confirmation Confirmation From Experimental Plantmentioning

confidence: 99%

A rapid tool for emission outlet concentration simulation of scrubber and make-up air unit at different inlet concentrations

Kuo

Chuang

Chang

2017

Building Services Engineering Research and Technology

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“…4,10,11 However, there are still no emission factors from semiconductor-related processes reported by either EPA or the EEA, 12-14 so emission factors estimated in this study were compared with those of Taiwan for evaluation. 15,16 The comparison of emission factors for both countries has limitations, mainly because of the control-based method of the Korean study and the uncontrolled nature of the Taiwanese research. Thus, emission factors derived from this study were converted into an uncontrolled basis to compare the average removal efficiencies.…”

Section: Mek Hibk Trichloroethylenementioning

confidence: 99%

Emission Factors of Air Toxics from Semiconductor Manufacturing in Korea

Eom

Hong

Lee

et al. 2006

Journal of the Air & Waste Management Association

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The development of local, accurate emission factors is very important for the estimation of reliable national emissions and air quality management. For that, this study is performed for pollutants released to the atmosphere with source-specific emission tests from the semiconductor manufacturing industry. The semiconductor manufacturing industry is one of the major sources of air toxics or hazardous air pollutants (HAPs); thus, understanding the emission characteristics of the emission source is a very important factor in the development of a control strategy. However, in Korea, there is a general lack of information available on air emissions from the semiconductor industry. The major emission sources of air toxics examined from the semiconductor manufacturing industry were wet chemical stations, coating applications, gaseous operations, photolithography, and miscellaneous devices in the wafer fabrication and semiconductor packaging processes. In this study, analyses of emission characteristics, and the estimations of emission data and factors for air toxics, such as acids, bases, heavy metals, and volatile organic compounds from the semiconductor manufacturing process have been performed. The concentration of hydrogen chloride from the packaging process was the highest among all of the processes. In addition, the emission factor of total volatile organic compounds (TVOCs) for the packaging process was higher than that of the wafer fabrication process. Emission factors estimated in this study were compared with those of Taiwan for evaluation, and they were found to be of similar level in the case of TVOCs and fluorine compounds.

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“…3,4 But it is reported that under atmospheric conditions almost all gas-phase ammonia dissolves in slightly acidic/neutral cloud water. 11 Furthermore, fine spray has long been used for efficiently scrubbing low-concentration NH 3 from a waste stream.…”

Section: Introductionmentioning

confidence: 99%

“…or 3 ppm (by vol) for NH 3 . 3,4 A recent report of the U.S. Environment Protection Agency (EPA) on national emission standards for hazardous air pollutants (NESHAP) for semiconductor manufacturing also mentioned that wet-scrubbers showed erratic performance characteristics with high-volume, low-concentration emission streams.…”

Section: Introductionmentioning

confidence: 99%

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

Chein

Aggarwal

et al. 2005

Journal of the Air & Waste Management Association

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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 (ϳ500 m 3 /min), low-concentration acidic (Ͻ1 ppm by vol) and basic (Ͻ3 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 acidpacked 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 ϭ 11) 53, 40, and 27%, whereas after installation of the system, they increased significantly and became 76 Ϯ 13% (n ϭ 10), 76 Ϯ 8% (n ϭ 7), and 78 Ϯ 7% (n ϭ 7), respectively, for inlet concentrations of HF and HCl Ͻ1 ppm and NH 3 Ͻ14 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.

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Emission characteristics and control efficiency of acidic and basic gases and aerosols from packed towers

Cited by 15 publications

References 4 publications

A rapid tool for emission outlet concentration simulation of scrubber and make-up air unit at different inlet concentrations

A rapid tool for emission outlet concentration simulation of scrubber and make-up air unit at different inlet concentrations

Emission Factors of Air Toxics from Semiconductor Manufacturing in Korea

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

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