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Tunable diode lasers (TDLs) are rapidly replacing paramagnetic analyzers in many petrochemical unit operations. By providing fast, accurate measurements directly from within the process, TDLs maintain process safety.
Strict oxygen levels are essential in vapor recovery units
Volatile organic compounds (VOCs) are present in many oil refineries and petrochemical plant unit operations. In some unit’s flares are used to ignite the VOCs before they are released to the atmosphere. In other applications, such as oil / petrochem storage, handling, transport and waste systems, vapor recovery units (VRUs) collect the gas for processing as it commonly contains useful compounds.
If oxygen levels in VRUs are not kept below safe limits, there is an explosion risk; therefore, strict O2 monitoring is employed.
Safe VRU operation requires swift oxygen measurement
One of China’s largest petrochemical companies operates multiple facilities across the country. Like most companies, for monitoring oxygen levels in VRUs they traditionally installed paramagnetic analyzers, as that was the best available technology at the time. But a number of problems with the instruments, including slow response, poor measurement reliability due to cross-interference from background gases, and stability issues caused by fluctuations in the sample pre-treatment system meant there were constant concerns about oxygen levels in the VRUs.
In situ analyzer provides safety assurance
Consequently, the company was always looking for alternatives to paramagnetic instruments and were happy when METTLER TOLEDO China introduced to them our GPro® 500 tunable diode laser analyzer. TDLs operate in situ so sample treatment is not required. They are also largely immune to background gas cross interference, dust in the process and require almost no maintenance. Critically, they have a rapid response time of two seconds, so any sudden increase in VRU oxygen levels is quickly identified.
GPro 500 TDL Oxygen Analyzer
- Dependable, industry-proven tunable diode laser technology
- Direct measurement in the gas stream is fast and reliable
- Response time of two seconds maintains process safety
- Simple installation thanks to probe design and single flange connection
- No sampling or conditioning equipment. Annual verification and periodic optics cleaning are the only maintenance
- Low nitrogen purging consumption means low operating costs
- Sensor diagnostics continually monitor optical path quality to determine when cleaning will be required
Tests of the GPro 500 on a VRU at one of the company’s plants confirmed its ability to accurately monitor oxygen, despite changes in process conditions. With high satisfaction in the GPro 500’s performance, the company has embarked on a program to install them in place of their VRU paramagnetic analyzers.
Learn more about our Mettler Toledo GPro 500 TDL Analyzer and how they can help your refinery on our website or call to speak to one of our technical representatives at 1-800-912-9262.
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