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

Abstract

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.