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Instrumatics Applications

Crowcon’s Gas Detectors Ensure Safe Operation at Indian Oil and Gas Terminal

One hundred Crowcon Nimbus flameproof (Exd) hydrocarbon gas detectors have been installed at Cairn Energy’s Mangala oil and gas processing terminal in Rajasthan, India. Supplied via Larson & Toubro, the Nimbus units are located at strategic locations throughout the facility and ensure the safety of workers and equipment by detecting elevated levels of flammable hydrocarbon gases.

“Hydrocarbon gas detectors are required by local legislation,” commented Crowcon’s Indian distributor, Mr Kishore Degwekar of Detection Instruments Pvt. Ltd. “Our customer Larsen and Toubro, purchased the Nimbus detectors as they are certified by the Indian Directorate General of Mines Safety”.


Crowcon’s Nimbus gas detectors have an excellent 10-year proven track record and, as well as having local certification, are also ATEX and UL certified. The detector is also assessed to the globally recognised functional safety standard IEC61508 and is suitable for use as part of SIL 2 systems.


Many thousands of Nimbus detectors are installed in locations across the globe, in all climatic conditions, such as the north of Sweden with its sub-zero winters, the deserts of Qatar, where summer temperatures can exceed 50oC and where sandstorms are common, and hot and very humid regions such as Malaysia.

It is used in all manner of locations, including underground tunnels, oil and gas rigs, oil and gas refineries, over-ground pipelines, compressor stations, turbine halls, pumping stations, sewage works, chemical works, aerosol filling plants, floating production ships (FPSO’s) and power stations.

Designed to be integrated with existing gas detection systems, Nimbus can be used in conjunction with digital communication networks (via RS-485 Modbus) or conventional 4-20mA control systems such as Crowcon’s Gasmonitor.

Rated to IP67, Nimbus functions in even the dirtiest conditions. The optics operate at up to 90% obscuration, with a dirty optics warning light activating at 75% obscuration. An external status light indicates whether the unit is in normal function or fault, alerts users to rising gas levels, and also identifies 22 further conditions for simple diagnosis.

About Cairn Energy’s Mangala oil processing terminal

The Mangala processing terminal covers an area equivalent to 200 football pitches and includes oil, gas, power and water infrastructure. At an eventual length of 670 km, the pipeline will provide access to more than 75% of India’s refining capacity. At the peak of construction, approximately 16,000 workers were involved: 5,000 on the pipeline and 11,000 on the processing terminal.


Evaporator in a distillation column

The application

In a petrochemical research facility, an evaporator (reboiler) heats the liquid from the bottom of a distillation column together with different additives, so-called catalysts, and splits it into its constituent parts. The temperature in this vessel is about 350° C. The different types of benzol released are then extracted in the fractionation process.

The level in the evaporator must be continuously monitored and kept constant during the process. In addition, a point level measuring system is needed to reliably detect when the maximum level is reached, regardless of the mixing ratio of the raw materials.
The different catalysts cause large fluctuations in the density and dielectric constant of the measured medium. These variations and the extreme thermal process conditions place particularly high demands on the measurement technology used.



The process data

Medium: Benzol
Vessel: Evaporator (reboiler)
Process temperature: + 350 °C
Process pressure: 20 bar
Process conditions: Extreme temperatures and high pressures, fluctuating density and dielectric values

The solution

The high temperatures and changing conditions in the evaporator require a robust and reliable measurement technology.
The vibrating level switch VEGASWING 66 is ideal for point level measurement in liquids with extreme temperatures up to +450° C and pressures up to +160 bar.
VEGASWING 66 detects the maximum permissible level of the crude oil in the distillation column and reliably prevents overfilling of the container.

The TDR level sensor VEGAFLEX 86, which is also ideal for use in hot media, measures the actual level in the evaporator. With its operating range of -196° to +450° C and 400 bar, VEGAFLEX 86is quite suitable for extreme applications. The applied TDR sensor is also SIL2 qualified (IEC 61508) and has all required approvals for use in hazardous areas.

The dependable level control system and fail-safe overfill protection device are installed in the evaporator (reboiler), which is located at the bottom of the column in the petrochemical research facility. Together, they ensure constant recirculation of product and thus effective operation of the entire distillation column.


User benefits

Advantage Robust, long-lived sensors with high temperature resistance
Advantage Universally applicable point level switch not influenced by changing product properties
Advantage Efficient, reliable operation of the distillation column through precise, reliable measured values
Advantage Extensive diagnostic functions and SIL qualification increase plant safety

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Reboiler in a distillation column

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For extreme process conditions - VEGASWING 66 and VEGAFLEX 86

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Rugged and reliable for high temperatures and pressures



See below for even more unique level applications

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Instrumatics is a supplier of quality field instrumentation, offering a wide range of technology and more than 35 years in the business.
Our dedicated team of experienced engineers are able to specify appropriate instrumentation for given requirements.






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