Continuous Emission Monitoring System Working Principle

Ⅰ. Introduction to continuous emission monitoring system

The working principle of the continuous emission monitoring system consists of a particulate matter monitoring subsystem, a gaseous pollutant monitoring subsystem, a flue gas parameter monitoring subsystem, a system control, and a data acquisition and processing subsystem. It can monitor gases such as SO₂, NOx, O₂, dust, temperature, pressure,and flow. And a precision hygrometer can monitor humidity. It can also be extended to specific occasions to monitor HCl, HF, CO, CO₂, NH₃, H₂S, Cl₂, VOC and other parameters. The measured gas is dust-removed by the sampling probe, and the heating tube is sampled, and then enters the gas analysis module for violet differential absorption spectroscopy (DOAS) for analysis and measurement. It effectively solves the technical problems of dust and moisture interference measurement, especially in the case of low concentration measurement, with unparalleled advantages. It is suitable for emission monitoring and process analysis of coal-fired power plants, garbage power plants, cement, glass, lime plants, ceramic plants, sintering plants, coke ovens, and desulfurization and denitrification processes.

Ⅱ. Continuous emission monitoring system working principle

A. Continuous emission monitoring system working principle (particulate matter)

The function of the particle measurement subsystem:

1. Direct measurement without sampling system;

2. The probe is not in contact with smoke;

3. Since it is difficult to obtain standard materials, CEMS manufacturers usually use filters for calibration.

4. The influence of dust and water vapor is greater. Unless the flue gas is reheated to a temperature higher than the dew point of water, it is not suitable for measurement after a wet purification facility.

5. The blowing curtain needs 24 hours to run (also stop in the furnace);

6. Changes in particle composition and particle size will affect the calibration of such analyzers.

Online performance requirements for particulate matter:

Zero drift: ≤±2%FS;

Span drift: ≤±2%FS;

Correlation coefficient: ≥0.85 (when the upper limit of the measurement range ≤50mg/m³, ≥0.75)

B. Working principle of continuous emission monitoring system (air pollutants)

Classification of online monitoring methods for gaseous pollutants:

1. Continuous monitoring of drainage (dilution sampling method, direct sampling method)

a. Dilution sampling method: Use a dust particle measuring device to collect the flue gas and remove dust, and then use clean zero gas to dilute the flue gas at a certain dilution ratio to reduce the concentration of gaseous pollutants, and introduce the diluted flue gas into the smoke.

b. Direct extraction and sampling method (heating pipe method): The flue gas after dust removal is insulated through a heating pipe to keep the flue gas without condensation, and then sent to the drying device for dehumidification, and then sent to the analysis device for concentration analysis.