Measurement of O2 Concentration in Exhaust Gases from Pulverized Coal-fired Boilers

Introduction

In a pulverized coal-fired boiler of a large power plant, an oxygen analyzer is essential for combustion control. Exhaust gases from the pulverized coal boiler contain a large quantity of dust and flow very fast. Oxygen analyzers that employ a sampling method may be subject to wear or clogging, resulting in increased maintenance workload and cost.

A solution to this problem is the ZR22G/ZR802G Zirconia Oxygen Analyzer that has no sampling system and utilizes a long-life sensor. A probe protector is attached to protection it against wear.

Expected Benefits

• Improves combustion efficiency for pulverized coal-fired boilers 
• Ensures stable, continuous oxygen measurement 
• Reduces operating costs
• Minimizes the need for equipment replacement

Process Overview

While oil is commonly used as a boiler fuel, coal is also used because it is inexpensive and readily available. Unlike oil, coal produces a large quantity of ashes when it is burned, necessitating pulverized coal-fired boilers to be equipped with an ash removal system such as a cyclone. Exhaust gases from these boilers contain a large quantity of dust (10 to 30 g/Nm3) and flow very fast as the result of the large volume of air being blown into the boiler. For oxygen measurement in large ducts, a probe with a long insertion length is used.

Solution Details

Field Data

Process conditions

 

Notes

• A probe protector should be attached to the probe for protection against wear or damage. The probe protector should be mounted with the notch of the probe head pointing downstream in the gas flow.
• It is recommended that the detector be installed with the probe tip pointing downward. As shown in the figure, it may be installed horizontally, too. The probe head tip should not point upstream in the gas flow.