Field-mounted in-line process analysers add new measurement capabilities

01 February 2006

Today’s process gas chromatographs are an advanced combination of technology and rugged instrumentation. The trend in engineering staff downsizing means instrument technicians have more to do in less time, so instrument makers know they have to make their products more reliable and easier to use than ever before.

Emerson Process Management’s Rosemount Analytical Model 700 is designed for a variety of refining, petrochemical, food and beverage, pharmaceutical, power and environmental applications where selected components in gaseous or liquid streams must be precisely monitored on a continuous basis. The company has announced a series of enhancements to the Model 700, including

....Micro-Flame Ionisation Detector (mFID);
....Detector pre-amplifier/electrometer;
....Micropacked Methanator;
....Heated liquid sample injection valve;
....Heated sample transfer tubing; and
....Flame Photometric Detector module (FPD).

The micro-flame ionisation detector with its new detector preamplifier/ electrometer board permits measurement of trace hydrocarbons in a variety of samples at parts-per-billion (ppb) concentrations. The mFID is unique in the industry because of its small size (less than 8 cm high) that fits inside the explosion-proof housing of the Model 700. Typical applications include measuring trace impurities in gases and light hydrocarbons, as well as ambient air monitoring.

The micropacked methanator permits measurement of trace carbon monoxide and carbon dioxide in ethylene, propylene and other polymer-grade chemicals by converting the trace gases to methane, which can then be measured at ppb levels using the mFID.

The heated liquid sample inject valve expands the analyser’s capability to measure liquid hydrocarbon samples, especially sample streams prone to polymerisation such as styrene, dicyclopentadiene and 1,3-butadiene.

The heated sample transfer tubing is used with the heated liquid sample inject valve to transport sample from the injection valve to the column oven. The heated sample transfer tubing is also used for vapour samples that require heat to prevent condensation of water or hydrocarbons.

The Flame Photometric Detector (FPD) module expands the application capability of the chromatograph to trace sulphur compounds with sensitivities typically better than 50 ppb. The freestanding FPD module can also be connected to the Rosemount Analytical Model 500 Process Gas Chromatograph.

The Rosemount Analytical Model 700 Process Gas Chromatograph, with its airless heat sink oven is designed to be an alternative to traditional process gas chromatographs that must be protected from the weather in temperaturecontrolled shelters. The Model 700 is field-mountable near the sample point,
minimising cost-of-ownership expenses such as insulated shelters, air conditioning, heating and long heated sample lines. To ensure the reliability of the analyser and application in the field, the measurement repeatability of every Model 700 is tested in an environmental chamber from -18 deg to +55 deg C. Applications employing the new process enhancements are built and tested to the same rigorous standards.

Emerson Process Automation

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