Opsis blog

Gas Concentration Monitoring in the Industry

Gas Concentration Monitoring in the Industry

There are often rules and regulations dictating what and how to monitor when it comes to emissions to the ambient air. By example, the European Union has established the Industrial Emissions Directive (the IED, 2010/75/EU) with conclusions on best available techniques (BATCs) for different types of industries.

These documents serve as guidance and in some cases minimum requirements for national authorities when they decide on operating permits for individual industries, including requirements on limiting the emissions and emissions monitoring.

Emissions Monitoring

Quite often, there are limits for SO2, NO and NO2 (or NOX), and CO emissions, but sometimes also for more niched substances such as HCl, HF, NH3, and Hg. The limits may be expressed in “weight per time” (e.g. tonnes per hour), and then it may also be necessary to measure the flue gas flow. Alternatively, the limits are expressed as “normalized weight per volume”, where the concentrations are recalculated to a set oxygen level. Then the actual O2 concentration also needs to be measured, but there is no need to measure the gas flow.

Flue Gas Treatment

To meet the limits on emissions to air, the flue gas to be emitted from a process often passes treatment stages (filters) for the purpose of reducing the levels of the emitted pollutants. Gas concentration monitoring is often applied before and/or after such filters to control the treatment process, and sometimes also to protect the filter from being damaged by the contents of the flue gas. Parameters to monitor for these purposes are often dust, SO2, HCl, HF, NO, and NH3.

Process Control

Controlling flue gas cleaning stages is a type of control of what might be considered as auxiliary processes not tied to the actual production at the industry. However, there are quite often also needs for gas concentration monitoring with direct impact on the production process. By example, in incineration processes such as at waste-to-energy plants, the CO and/or O2 concentrations are often monitored immediately after the furnace to be able to optimize the incineration process. At chemical industries, it is quite common to find needs for monitoring of production process intermediates, for example SO2 and SO3 at sulfuric acid plants, and NH3 at fertilizer plants.

Rest assured that if there is a need for a parameter to be measured, then there is also a technique for measuring it. Feel free to contact OPSIS or its representatives to find the best solutions for your monitoring needs!