5 main components of CEMs

CEMs, or Continuous Emission Monitors, are a type of system used to track emissions over time. A new law mandates the use of CEMs systems in many manufacturing facilities, and it was passed by the Department of Industrial Works. The penalties for not having it installed range from a fine to being forced to shut down the plant; if anyone is interested in the specifics, we have already written an article on that matter. Please click here.


We have already covered some of the basics of CEMs in previous articles. If you haven't read those yet, we suggest you check them out >>> here.


Today, we'll have a look at the CEMs system's components and how they work together. Overall, the CEMs system is made up of many different components. Each component works together to ensure the effectiveness of the CEMs system. Here, though, we shall narrow in on five of the most crucial components.


1. Sampling Systems

This component is responsible for collecting a representative sample of the emissions from the stack or other source. There are two key devices that you should be aware of. They are known as the Sample probe and the Sample line.

(1) Sample Probe

It is a device that extracts gas from a chimney. The first thing to keep in mind is that this device needs to be able to reach temperatures of at least 180 °C to prevent the gas sample from condensing into a liquid.

The second thing to think about is whether or not the measuring device has a dust filter to avoid malfunction due to a buildup of dust. Sticky particles might block the gas route after coming into contact with fluids. Preventing the filter from becoming clogged requires frequent upkeep. Periodically, you should give the filter a "blow back," or a hard whack, to force the dust out.

When choosing a sample probe, however, one must think about the gas, heat, and other things that are being measured inside the shaft in order to choose the best equipment.


(2) Sample Line 

A tube or pipe that can keep temperatures between zero and hundreds of degrees Celsius while transporting samples from the sampling unit to the sampling conditioning system.

It is important to know the dew point of the gases in the sample and to keep the sample above that temperature when choosing a sample line or tube. They need a system that keeps the temperature consistent down the entire line, as well as thick walls and insulation to keep the heat in and the weather out.

This is because the gases we gather from the stack are only part of what we find to be contaminated. It also contains water vapor, which can cause problems if it condenses into a liquid and mixes with the gas sample being measured. This can make the readings wrong or, if the gas is polluting, create an environment where the acidic liquid damages the instrument.


2. Sampling Conditioning System

This component is responsible for collecting a representative sample of emissions from the stack or other source and conditioning it so that it can be accurately analyzed by the monitoring instruments. In order to get the sample into the correct shape for examination, a lot of people dilute it, heat it up, and filter it.

Many factors must be considered before developing a sample system, for example:

  • Sample collection
    The sampling system must be capable of collecting a representative sample of the monitored emissions.
  • Sample transport 
    There can be no loss or contamination of the sample on its way to the analyzer.

  • Sample analysis
    The sampling system must work with the analyzer that is used to measure the emissions, and the sample must be at the right temperature, pressure, and flow rate for the analyzer.
  • Quality control 
    -  Sample quality control ensures that the sample is representative and free of contamination.
    -  Quality control of the system is necessary since the system may be malfunctioning due to a leak or other issues. As a result, the system must be checked on a regular basis.
  • Safety
    A safe sampling system is one that is both built and used in a way that doesn't endanger the people working with it or the surrounding environment.

  • Maintenance and calibration 
    Sampling systems need to be maintained and calibrated often to make sure they work well and give accurate results.

  • Compliance with regulations 
    For continuous monitoring of emissions, sampling systems must be built and run according to all relevant rules and suggestions.

3. Analytical measurement

Depending on the type of gas being monitored and the purpose of the CEMS system, several analytical equipment are employed to calculate the emission intensity.

Please allow me to explain this by providing examples of standard CEM measurements.

  • Infrared absorption 
    Gas concentrations like CO2, CO, and NOx can all be calculated using this method. If infrared light is shined through the spent gas, the amount of light absorbed by the target gas can be calculated.
  • Ultraviolet fluorescence
    A concentration of SO2 can be calculated using this principle. After shining ultraviolet light through the exhaust, the SO2 fluorescence is measured.
  • Electrochemical sensors
    These sensors can detect low concentrations of gases like O2, CO, and H2S through an electrochemical reaction. A current generated by the electrochemical reaction between the electrode and the exhaust gas is measured.
  • Non-dispersive infrared (NDIR)
    CO2 and CH4 concentrations are determined using this technique. To determine how much light the target gas absorbs, the device uses an infrared light source and a detector.
  • Laser-based measurement
    One method for measuring the amount of a specific gas in the air makes advantage of the laser beam's absorption at a specific wavelength.

4. Data acquisition and handling

Data acquisition systems collect data from analytical instruments. These systems typically include hardware and software components that collect, process, and store data from instruments.

After the data has been cleaned of any mistakes or abnormalities and any calculations have been performed, it is saved in a database that can only be accessed and analyzed by those with the proper permissions.

The database data can be analyzed to identify trends, patterns, and potential problems with the manufacturing process. Reports can be created to offer an overview of the data as well as to demonstrate compliance with environmental regulations. The data can also be provided to regulatory agencies and other stakeholders as required by law. This is often performed through the use of electronic reporting systems.


5. Reporting CEMS data

CEMS data in Thailand is reported through the Pollution Online Monitoring System (POMS). The POMS is a system for monitoring and reporting industrial and power plant emissions. The POMS system is managed by the Department of Pollution Control (DPC) of the Ministry of Natural Resources and Environment.

Once the CEMS system has been installed successfully, data recording occurs almost entirely automatically, without our intervention. The distribution of CEMS data can be simply broken down into four steps.

Get Data  >  Review Data  >  Submit Data  >  Analyze Data

The steps to report it via the POMS system have been outlined in a manual that has been compiled by the Department of Industrial Works for business owners on how to utilize the POMS system. Simply clicking on this link will take you to the user manual. The instructions on how to use the system are very detailed.


Besides the basics, there is a lot more to learn about CEMs. In this knowledge center, we'll do our best to simplify the relevant information into digestible chunks. Whether you are a beginner or an experienced user, this knowledge center has something for everyone

In order to stay up-to-date, make sure to like and follow our Facebook page.

And if you have any suggestions for our future articles or any CEMs-related questions, you can leave a message on our LINE OA by clicking here. Our admins are happy to arrange for you to speak with one of our professionals who can directly address your queries. ​

Powered by MakeWebEasy.com
เว็บไซต์นี้มีการใช้งานคุกกี้ เพื่อเพิ่มประสิทธิภาพและประสบการณ์ที่ดีในการใช้งานเว็บไซต์ของท่าน ท่านสามารถอ่านรายละเอียดเพิ่มเติมได้ที่ Privacy Policy  and  Cookies Policy