Brechbuehler AG: Process MS

Introduction

The Thermo Scientific Prima and Sentinel family of Process mass spectrometers have been successfully deployed worldwide to provide fast, accurate and complete gas composition analysis in a wide range of applications for the purpose of process optimization, enhanced safety and regulatorycompliance. Ever-increasing global competition, over-stretched maintenance departments and strictrequirements for carbon emission auditing require continuous improvements in process analyticaltechnologies. Because of its inherent flexibility, mass spectrometry is expected to play a major role inthe next generation of process gas analyzers. The new Prima PRO has been designed to provide truenext-generation performance with significant improvements in accuracy, precision and stability in a package that is highly reliable and easy to deploy and maintain.

Technology Selection

Thermo Fisher Scientific has a wide-range of mass spectrometer technologies at its disposal, more in fact than any other process analyser company. The technology selected for the Prima PRO and Sentinel PRO is the scanning magnetic sector. This provides a flat-topped peak profile that tolerates mass scale drift with no effect on the measurement results. It is also a high-energy device that offers the best resistance to contamination. Finally, the ability to measure very small concentrations at masses immediately adjacent to high concentrations is made possible by the clean baseline between peaks.

Why use Process MS?

Fast analysis of process gases
seconds not minutes
Multi-component analysis
Analyze inorganics & organics
Multi-stream analysis
Up to 64 streams
Flexible analysis
Analysis defined in software
Can analyze different compounds in different streams
Precision, accuracy
Between 0.1% and 1% relative
Dynamic range
ppm to 100%

Prima PRO or Sentinel PRO?

The Prima PRO is intended for use in process development and online process optimization where gas component concentrations in the range 20ppm - 100% require precise measurement.
Additional low parts per million (ppm) concentrations can be added to the analysis by use of the optional multiplier detector.

The Sentinel PRO is intended specifically for use detecting fugitive emissions of toxic volatile organic compounds (VOC) in the ppm and parts per billion (ppb) range. The Sentinel is basically the same product as the Prima PRO but it uses membrane inlet technology to lower the detection limit down to 10 ppb for selected VOCs. This type of inlet is not appropriate for measurements in the % range. If you are looking for an online process gas analyzer then the Prima PRO provides the best available measurement quality. If on the other hand, you require an analyzer that will monitor as many as 100 sample points around a process unit within the 15 minutes that define short-term exposure Limits (STEL) to potentially leaking VOCs then the Sentinel PRO should fit the bill perfectly.

Principles of Operation

Magnetic sector mass spectrometers rely on the interaction of ionized sample molecules and magnetic fields in order to filter and measure individual atomic mass components that collectively contribute to the total sample composition. The ions are formed in an ionization chamber by interaction of the neutral gas phase sample molecules with a beam of energetic electrons. The newly formed ions are immediately accelerated towards the magnetic field. Each charged particle will experience a sideways force that is proportional to the strength of the magnetic field, the velocity of the particle and its charge. Each appropriate mass can be selected in turn by setting the magnetic field strength to a value that will direct the selected ions through a narrow window in front of the detector. The signal measured here is directly proportional to the molecular concentration of the selected component. By measuring a predetermined number of ions, a complete compositional analysis can be performed.

Sample Introduction

The most popular device for introducing sample gas into the analyzer is the Rapid Multistream Sampler (RMS). This is a highly reliable device for switching sample streams without compromising the quality of the sample presented to the analyzer. The RMS has a long track record of rock-solid reliability with its proven capability to switch streams six million times a year (for year after year) with little or no maintenance. This allows a single RMS system to monitor up to 63 sample ports and a dual RMS Sentinel to monitor up to 126 streams. The stepper-motor driven device diverts one sample stream at a time to the mass spectrometer and records the flow for each stream in turn. The device can be heated to 120°C and has been designed to ensure rapid response to polar species such as methanol, ethanol and ammonia.

Prima BT Process Development Benchtop MS

The Thermo Scientific™ Prima™ BT Bench top Mass Spectrometer, based on the Prima PRO, the market leader in on-line process MS, is a highly reliable, precise, and flexible gas analyzer specifically designed for process development laboratories.

It is an industrial laboratory gas analyzer based on scanning magnetic-sector mass spectrometry. Designed for continuous operation in a process environment, the Prima BT mass spectrometer is simple to operate and easy to maintain.