What are Emission Monitoring Systems (EMS)?

By Inderpreet Shoker

Industry Trends

Many environmental regulatory authorities around the world require manufacturing industries to keep track of pollutant emission rates using continuous emission monitoring systems (EMS or CEMS). CEMS is the traditional equipment used for continuous monitoring of emission and is approved/required by most authorities. As an alternative, authorities in many countries permit the use of predictive emission monitoring systems for certain applications in lieu of an installed CEMS. For this study, our scope of emission monitoring systems in-cludes continuous emission monitoring systems (CEMS) and predictive emission monitoring systems (PEMS).

Main Emission Monitoring Systems Types

A CEMS system consists of several components to be able to determine gas or particulate matter concentration or emission rate of specific pollutants. Analyzer measurements and software produce results of the applicable emission limitation or standard in units.

CEMS are mainly classified by probe mounting style, either extractive or in-situ. In extractive systems, probe and analyzer are separated and the system extracts and conditions the gas sample before sending it to the analyzer to determine the constituents. In in-situ CEMS, the analyzer is in direct contact with the flue gas, eliminating the need for sample conditioning.

PEMS, in contrast, use modeling software for inferring gas concentration or emis-sion rate based on control device operating parameters to predict emission levels of the applicable emission limita-tion or standard in units. A PEMS may optionally include a sensor validation system to ensure accuracy of predicted emissions data. PEMS can be used inde-pendently for qualified emissions sources, in lieu of, or as a backup to con-ventional CEMS.

In PEMS, the system must be “trained” to create the appropriate emission model. In the training phase, a CEM sys-tem is used temporarily to measure actual emissions. The predictive system then collects process data from various sources and models a relationship between various inputs (process data) and outputs (emissions). Once the emission model is prepared, the system performs a series of tests to validate the model for various operating conditions. After validation, the CEM sys-tem can be removed and the PEM system used for emissions data. The PEM system predicts the emission level based on process data and emission modeling.

Key Emission Monitoring System Components

Total revenues reported for this market consists of hardware, software, and services. We’ve further segmented hardware revenues by:

· Sensor/Probe

· Hardware Mounting

· Sample Conditioning

· Shelter/Enclosure

· Analyzer

· Workstation

· Data Acquisition System

Software revenues include unbundled software and do not include reve-nues from software that are bundled with the hardware price. We’ve categorized service revenues by maintenance and integration services.

Typical Measured Variables and Measuring Technologies

The measured variables included in this study are:

· Ammonia (NH3)Predictive Emission Monitoring System

· Carbon Monoxide (CO)

· Carbon Dioxide (CO2)

· Hydrogen Sulfide (H2S)

· Hydrocarbons

· Hydrofluoric Acid (HF)

· Mercury (Hg)

· Nitrous & Nitric Oxides (NOx)

· Oxygen (O2)

· Dust/Particulates

· Sulfur Dioxide (SO2)

· Sulfur, Total (reduced)

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