Minimizing Explosion Risk Where Other Solutions Cannot

By Mettler Toledo CE |

Minimizing Explosion Risk
Where Other Solutions Cannot

To run carbon disulfide recovery with the highest safety, a Chinese chemical company wanted to install a tunable diode laser (TDL) oxygen analyzer. But the line size of the pipe at the installation point was too small. A METTLER TOLEDO TDL analyzer provided the answer.

Recovery of valuable raw material
Polyacrylamide (PAM) is a polymer widely used as a flocculant in water treatment and processes such as paper manufacture. One PAM production method uses carbon disulfide (CS2) as a raw material. Carbon disulfide is highly toxic and waste gases from PAM production that contain unused CS2 must be processed before being released to the environment.

Regenerative thermal oxidizers (RTOs) are commonly used for such processing. But as CS2 is a valuable raw material, some plants recover as much of it as possible before sending the waste gas to the RTO.

The world’s leading manufacturer of PAM operates production facilities in more than 20 countries, including China. In one of its Chinese plants, measurements from a paramagnetic analyzer were being used to control O2 levels in the facility’s CS2 recovery unit, as CS2 is highly flammable.

Paramagnetic analyzers risk process safety
Production engineers were concerned that the sampling system on the paramagnetic analyzer was significantly delaying measurements and represented a safety risk.

In addition, the sample conditioning system attached to the paramagnetic analyzer would not always eliminate all hydrocarbons in the sample. As the presence of hydrocarbons interferes with paramagnetic analyzers, there was always uncertainty regarding the accuracy of measurements.

In situ technology delivers an immediate measurement
Production engineers at the plant were eager to replace the paramagnetic unit with a tunable diode laser (TDL) oxygen analyzer, as this technology can be installed directly into process pipes to provide an almost instant measurement and is immune to hydrocarbon interference.

However, due to the small line size of the CS2 recovery unit gas stream feeding lines, the engineers were disappointed to discover that the TDL analyzer they were considering could not be fitted. And proximity of other equipment would not allow installation in a bypass. METTLER TOLEDO had the solution.

Scalable TDL analyzer for a wide range of applications
GPro® 500 is a range of TDL gas analyzers that can be equipped with a wide variety of process adaptions to meet virtually any installation requirement. Crucially for the PAM production facility, these adaptions include a wafer cell that allows installation of the GPro 500 into pipes down to 2 inch. Also, the compact size of the GPro 500 meant the solution could easily be fitted in the available space at the facility.

In addition, production engineers at the plant were happy to learn that the only maintenance needed on the GPro 500 is occasional cleaning of the analyzer’s optics, and annual verification.

High confidence in safety of volatile compound recovery
A GPro 500 oxygen analyzer with wafer cell adaption has been installed at the plant and is providing rapid, problem-free assurance of CS2 recovery unit safety. Plans are in place to replace other paramagnetic analyzers at the facility with the GPro 500.

Find out in our success story how the GPro 500 is now providing Europe’s largest producer of chlorine with:
- Greater process confidence
- High measurement accuracy
- Low maintenance costs


The GPro 500 series of gas analyzers is available for oxygen, carbon dioxide, carbon monoxide, water vapor and other critical gases.

Tunable Diode Laser (TDL) gas analyzers are rapidly becoming the technology of choice for chemical and petrochemical companies across the world. See in this animated video, the simple design and installation of METTLER TOLEDO’s GPro® 500 series of TDLs.

See more about the GPro 500 series: GO TO THE PAGE

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