Measurement and Monitoring of O2 Concentrations in Steel Mill Reheating Furnaces

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A furnace for heating slabs needs to be operated under low oxygen conditions at high temperatures of 1000℃ and above to prevent oxidation of the steel. The measurement of oxygen concentrations in the furnace is essential in this process.

The ZR22G/ZR802G Zirconia Oxygen Analyzer requires no sampling system and utilizes a long-life sensor, and is therefore ideally suited for measurement of oxygen concentrations in a hightemperature environment. The ZR22G detector with the ZO21P high temperature probe adapter can be used in gas furnaces at temperatures up to 1400℃.

Expected Benefits

  • Maintains high product quality by monitoring oxygen concentrations in steel mill reheating furnaces
  • Ensures stable, continuous measurement of oxygen concentrations
  • Reduces operating costs

Process Overview

Slabs are loaded on a conveyor and fed to a reheating furnace, which is heated to between 900 and 1400℃ by burners that use fuels such as by-product gas. In order to keep the oxygen concentration between 1 and 2%, it is monitored in the preheat, heat , and soak zones. The slabs are heated uniformly without being oxidized, and then sent to the next processing stage.

Reheating Furnace Process

Solution Details

Field Data

Process conditions
Measurement point: furnace reheat, heat, and soak zones
Temperature: 900°C to 1400°C
Pressure: 30 to 50 kPa
Dust: Trace
Fuel: Gas

Measurement system

Auxiliary Ejector for High Temperature Use

Detector: ZR22G-015-S-Q-☐-☐-☐-E-A/CV
High temperature probe adapter: ZO21P-H-☐-☐☐☐-☐*B
Auxiliary ejector for high temperature use: E7046E☐
Converter: ZR802G-☐-☐-N-N/☐
Flow setting unit: ZA8F-☐*C
Calibration gas unit
Pressure regulator for gas cylinder: G7013XF (inlet W22, outlet Rc1/4) or G7014XF (inlet W22, outlet 1/4NPT)
Case assembly for calibration gas cylinder: E7044KF

Note: the calibration gas cylinder must be purchased locally.

Probe Adapter

Power supply: 85 to 264 V AC, 50/60 Hz
Instrument air (reference gas): pressure, 300 to 700 kPa


The material selected for the high temperature probe adapter depends on the temperature of the sample gas. Follow instructions carefully when installing the probe.

SUS: Sample gas temperature ≤ 750°C
Probe orientation: vertical or horizontal
Inconel: 750°C < sample gas temperature ≤ 900°C
Probe orientation: vertical or horizontal
SiC: 900°C < sample gas temperature ≤ 1400°C
Probe orientation: vertical

When the probe is installed horizontally, bracings must be provided for mechanical support




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