Improvement of gas recovery efficiency by measuring O2 in LDG of steel plant with laser gas spectrometer TDLS8000

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In LDG(converter gas) Recovery of steel plant, O2 measurement is important to safely recover LDG containing high concentrations of CO gas. Paramagnetic O2 analyzer with a sample conditioning system (SCS) has been conventionally used to measure O2. But it requires running costs for the SCS and slow measurement time, which made it difficult to fully recover fuel resources. The TDLS8000 Laser Gas Analyzer solves these problems.


Customer’s expectation

  • Reduction of maintenance costs and running costs without SCS.
  • Improvement of gas recovery rate, reuse of recovered gas, and reduction of fuel cost by fast response and control.
  • Improved safety by continuous and highly accurate measurement


Process overview

LDG Recovery safely recovers combustible gases containing high concentrations of CO. The recovered gas is reused as a fuel resource, contributing to energy conservation and CO2 reduction. For example, LDG Recovery systems installed in all converter furnaces in Japan recovers the energy of about 67 PJ*(equivalent to a CO2 reduction of about 4 million tons/year) in 2005.
* PJ (Petajoules):the unit of energy, the Peta is a thousand trillion times.

Process overview


Solution provided by Yokogawa

The key is to select a model that can directly measure O2 concentration in LDG after induced draft fun (IDF), rather than a conventional analyzer with SCS. The TDLS8000, which can be installed directly in the process, provides fast response. This enables efficient and high purity gas recovery in LDG Recovery.

Solution provided by Yokogawa


Field data

The TDLS8000 has a shorter response time than conventional Paramagnetic O2 analyzers because of non-sampling device. And it can detect the reference value point of recovered converter gas without delay. The TDLS8000 can recover about 2 minutes worth of converter gas (Figure). This can be expected to result in significant fuel cost savings.。

Changes in measured O2 concentrations in a converter process (Comparison with an existing oxygen analyzer)
Figure : Changes in measured O2 concentrations in a converter process
(Comparison with an existing oxygen analyzer)


Measurement system

  • Analyzer (O2)
  • Insertion tube (Tokuchu)

*1: Please issue Tokuchu request for all the system above.

Measurement system


  • Dust loading should be 15 g/Nm3 or less.
  • Process purge gas flow must be 50 L/ more



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