Moisture Removal Techniques for a Continuous Emission Monitoring System: A Review

Abstract

A continuous emission monitoring system (CEMS) is a well-known tool used to analyze the concentrations of air pollutants from stationary sources. In a CEMS, the presence of a high moisture level in a sample causes a loss of analytes due to artifact formation or absorption. This issue brings about a bias in the measurement data. Thus, moisture removal is an important pretreatment step. Condensation and permeation methods have been widely employed to remove moisture from the CEMS for gaseous compounds. In terms of particulate matter, dilution methods have been applied to reduce the moisture level in the gas stream. Therefore, condensation, permeation, and dilution methods are critically reviewed in this work. The removal efficiencies and recovery rates of analytes are discussed, as well as the advantages and disadvantages of each technique. Furthermore, the suitable applications of each technique are determined. Condensation methods have not been well documented so far, while permeation and dilution methods have been continuously studied. Many types of permeation materials have been developed. The limitations of each method have been overcome over the years. However, the most reliable technique has not yet been discovered.

Analisis Keterampilan Berpikir Kreatif Mahasiswa PGSD Berbasis Etnosains Pada Materi Energi

“…Pembelajaran IPA mempelajari tentang ilmu alam yang disertai dengan gejala alam (Dave, 2018). Pembelajaran IPA memerlukan keterampilan pemahaman konsep, hukum-hukum, dan perkembangan pengetahuan tentang alam dan budaya lingkungan yang menyertai proses pembelajaran (Dinh & Jo, 2021). Suatu ilmu pengetahuan yang berkaitan dengan kebudayaan setempat dan dimiliki oleh suatu bangsa atau suku disebut sebagai etnosains (Aji, 2017).…”

Effects of Humidity Pretreatment Devices on the Loss of HCl Gas Emitted from Industrial Stacks

“…For the measurement of HCl in the CEMS, a non-dispersive infrared analyzer coupled with gas filter correlation and an ion electrode analyzer have been widely applied [11]. However, since HCl levels are only sub-ppmv (Table 1) and flue gas comprises a high humidity at high temperatures, this can cause damage to the analyzers and analytical bias [13,14]. Therefore, humidity should be removed from the flue gas before it enters the analyzers.…”

“…The Nafion ™ dryer has been widely used in this way, and it is usually employed to remove humidity from flue gas in a CEMS [11,15]. The basic structures of a cooler and a Nafion ™ dryer are presented in Figure 1 [14]. The cooler consists of an impinger-which is cooled to about 2~4 • C by a Peltier so that the water vapor in the flue gas at a high temperature may be condensed as liquid droplets and accumulated at the bottom of the impinger-and a drain pump to drain out liquid droplets [14].…”

“…The basic structures of a cooler and a Nafion ™ dryer are presented in Figure 1 [14]. The cooler consists of an impinger-which is cooled to about 2~4 • C by a Peltier so that the water vapor in the flue gas at a high temperature may be condensed as liquid droplets and accumulated at the bottom of the impinger-and a drain pump to drain out liquid droplets [14]. With the Nafion™ dryer, there is a tube consisting of a Nafion™ membrane which has high selectivity to water.…”

“…With the Nafion™ dryer, there is a tube consisting of a Nafion™ membrane which has high selectivity to water. The sample gas normally passes through the dryer, then water vapor penetrates the membrane and follows the purging air, while other gases keep moving to the outlet of the dryer [14]. Since HCl has a high solubility in water (i.e., 720 g/L at 20 • C) [1] and is strongly acidic, it might be lost in these pretreatment devices.…”