China
Africa
Explore chapters and articles related to this topic
3])
Published in Leo M. L. Nollet, Dimitra A. Lambropoulou, Chromatographic Analysis of the Environment, 2017
Carolina Santamaría, David Elustondo, Esther Lasheras, Jesús Miguel Santamaría
Sulfur dioxide is one of the major pollutants of air, and it is considered a primary criteria pollutant. SO2 is released into the air from fuel combustion and is responsible for local air pollution and can exacerbate smog formation and acid rain. Although the emission of SO2 has gradually decreased during the past few decades because of the control measures carried out by international environmental agencies, sulfur dioxide is still routinely measured in both air quality monitoring surveys and indoor environments. The most employed method to determine this pollutant is UV fluorescence, which allows for monitoring gas concentration in a continuous way. One example of this UV fluorescence continuous system was used by Mallik et al. (2012) in an air quality survey carried out in India. The SO2 is excited using a 214 nm wavelength and a band-pass filter centered around 350 nm to measure the fluorescence. Other continuous gas analyzers, designed to direct determinations of multiple gases in stack or exhaust pipes, use different systems such as electrochemical nondispersive infrared sensor or infrared absorption gas filter correlation.
Determination of methane during anaerobic digestion by tunable diode laser absorption spectroscopy (TDLAS)
Published in Instrumentation Science & Technology, 2023
Haibin Cui, Fei Wang, Shengyu Hu, Wenyuan Wang, Jinhui Fan
To validate this hypothesis, a gas sampling bag with a volume of 3 L was attached to the outlet of the nondispersive infrared sensor to prevent air in the external environment from flowing into the nondispersive infrared sensor. Tests were conducted from 13:00 to 18:30 on the third day, as shown in Figure 8.
A Simple Method for Monitoring Fire-Resistant Fluids Used in Electro-Hydraulic Governing Systems
Published in Tribology Transactions, 2018
Kiyoshi Sakuragi, Hiroyuki Nishida
In this regard, several approaches related to the quality management of hydraulic fluids—for example, the use of ion-exchange resins to improve the condition of the fluid (Dufresne (1); Phillips, et al. (2))—have been reported to prevent such occurrences, control the properties of phosphate esters, and ensure fluid longevity. In particular, the detection of phosphate ester deterioration at an early stage is imperative so that remedial action can be promptly taken. Several promising technologies have been developed for the monitoring of hydraulic oil; these include pH-metric methods (Strochkova, et al. (3)), nondispersive infrared sensor systems (Bley, et al. (4)), color measurements of deposits (Sasaki, et al. (5)), and conductivity measurements (Hedges (6)). Typically, in industry, the quality of phosphate esters is monitored by the acid number (ISO 6618 (7)), water content (JIS K2275 (8)), viscosity (ISO 3104 (9)), color (ISO 2049 (10)), and solid particle analysis (ISO 4021 (11); ISO 4407 (12)). These control indices permit the detection of the initial signs of system problems, thereby preventing turbine shutdown caused by the malfunction of EHC systems. Among these monitoring methods, the acid number is used as a guide for the quality control of phosphate esters during degradation. Acid number, which is the mass of potassium hydroxide (KOH) in milligrams required to neutralize 1 g of degraded phosphate ester, represents a measure of the total amount of acidic substances in the degraded phosphate ester. Because the acid number increases with the degradation of the phosphate ester, this measure is widely used as a monitoring method. Notably, the acid number indicates the total amount of acidic substances and not acidity. In addition, current monitoring methods that include the acid number require expensive equipment, a high skillset, and considerable analysis times. Accordingly, these analyses are frequently outsourced to an external institution, making it difficult to rapidly evaluate the conditions of phosphate esters on-site and obtain a response in a timely manner. Therefore, an efficient on-site measurement methodology can provide beneficial information, leading to more optimized operations in thermal power plants by preventing breakdown and managing the properties of phosphate esters, including the replacement of the degraded oil or performing more detailed analyses whenever applicable.