Measurement and Monitoring of O2 Concentrations in Steel Mill Reheating Furnaces

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Reheating furnace process
Reheating Furnace Process

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

The ZR22/ZR402 Direct In-Situ 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 high-temperature environment. The ZR22G detector with the ZO21P high temperature probe adapter can be used in gas furnaces at temperatures up to 1400°C.

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°C 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.

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: P/N E7046E☐
Converter: ZR402G-☐-☐-E-A
Flow setting unit: ZA8F-☐*C
Calibration gas unit
Pressure regulator for gas cylinder: P/N G7013XF (inlet W22, outlet Rc1/4) or P/N G7014XF (inlet W22, outlet 1/4NPT)
Case assembly for calibration gas cylinder: P/N 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




Related Products & Solutions

Single Channel Oxygen Analyzer System ZR22/ZR402

The ZR probe's in-situ measurement method does not require any process conditioning or extractive sampling. This reduces maintenance costs and allows faster measurement response to changes in the process.

Oxygen Analyzers

Oxygen analyzers provide valuable measurements in combustion control, process quality, safety and environmental applications.


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