Condition monitoring is as essential as insurance

A recent press launch described the combined condition monitoring experience and businesses within Schaeffler, CNES (Corus Northern Engineering Services), and a marine supplier who uses their monitors.

A recent presentation on condition monitoring techniques and experience, led by Schaeffler, adopts the view that expenditure justification on condition monitoring services or installations should be based on the approach of an insurance policy.

Finance Directors would be felt to be irresponsible if they did not have fire insurance, to protect the company assets.

They would probably accept the need for building and factory security as a service, and might even pay for AA breakdown cover for their car.

So the same should apply to the monitoring of the factory machinery to prevent production shutdowns as a result of a bearing failure, an event that could have been predicted by regular monitoring.

A financial risk assessment could also be used to highlight the most critical machines, in terms of impact on the continuing business of the factory, to see the consequential costs of a failure.

Schaeffler are bearing manufacturers, but a large proportion of their news stories are related to the condition monitoring equipment and services they offer to assist their customers, the users of bearings, in improving the maintenance operations and efficiency.

Within Schaeffler, FAG Industrial Services, known as F’IS, produce automatic lubrication systems, alignment systems and vibration monitoring/condition monitoring equipment as well.

F’IS will provide the equipment, training, or the condition monitoring services themselves: but have joined forces with CNES, Corus Northern Engineering Services, to provide an even more comprehensive range of condition monitoring services, under the new name of Praxis.

CNES expertise was obviously developed in the steel industry, but they are now possibly better seen as a provider of heavy engineering expertise, particularly in condition monitoring (with an experienced staff of 25) and repair and refurbishment of large plant – for industries such as cement, mining, minerals etc.

Inevitably large plant, with long lead times, and high value, is where condition monitoring is used already: but the effects of failure can be critical in any industry.

An interesting parallel has been in the marine industry, where Schaeffler DTECT permanently installed vibration monitors have been adapted into the Voyager system produced by RCM Marine.

Particularly for diesel electric powered chemical tankers, this turbocharger monitoring system provides an alarm indication should a problem develop on any of the ship turbochargers, and the signals are also transmitted via satellite or email back to RCM Marine, who can help assist in the analysis of the problem and the decisions needed.

CNES and Schaeffler have an archive of interesting application stories: its maybe time to review the technology for your plant, plus even find out how to win over the finance director, by talking to the experts!

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Optical spectroscopy techniques for gas analysis

Several Tunable Diode Laser gas analyser systems have been reported recently, in quite different applications! This is a review of the different systems, to illustrate the scope of the technology.

Recently we have seen several applications quoted for Tunable Diode Laser gas analyser systems, in quite different applications, and price levels! These are those known as at September 2007.

** The Yokogawa product launch in Europe of the ‘TruePeak’ tunable diode laser analyser, for gas analytical measurements, described the background to the technology: this unit uses a beam transmitted directly across a pipeline or flue.

Straightaway this gives a major advantage over GC and similar gas analysers, which have to use an extracted sample, which inevitably undergoes cleaning and conditioning: this can seriously affect the chemicals and relative concentrations that are present in the stream, before they reach the analyser.

The TruePeak is an in-situ optical transmission system, inserted into the process line, so it avoids the need for a sample, and also gives a reading in a few seconds, rather than the minutes or hours that sampling systems might require.

This unit is offered for monitoring O2, CO, CO2 and moisture on-line, in situ, using measurements at narrow absorption peaks specific to these gases, compared to reference measurements made at wavelengths away from absorption peaks, to give the zero reference.

This is where the tuning is required.

Once again the instrumentation industry benefits from telecommunications: without the mobile phone industry we would not have the components available that have made radar level measurement possible, or for that matter, wireless adaptations of pressure transmitters.

This time the tunable lasers that are used by this Yokogawa technology have been made available because of the need for tunable lasers for near infra-red fibre-optic transmission of telephone conversations.

It is pure serendipity that these devices can be tuned across these useful gas analysis absorption lines.

The near IR region is a good region for monitoring dual element gases, like H2O, CO, CO2, and the technique has been extended to H2S and Hydrocarbons as well.

Yokogawa admit that all the research and basic work has come from Dow Chemicals: the pioneers there have hundreds of these units installed, in Dow processes across the world.

The obvious application for these analysers is in combustion gas analysers, to ensure the boiler or furnace is operating at peak efficiency, with the correct fuel / air mixture.

But the Dow applications have gone further, their units are also used for monitoring water vapour in chlorine plants, to stop corrosion: and critically for the monitoring of acetylene at 1-2ppm in ethylene plants, which allows the plant efficiency to be much improved.

Further serendipity comes to answer the query that the more alert of you readers will be asking: how come a near IR analyser can measure O2 then, as it is not a dual element gas? Apparently this is one of nature’s quirks, that oxygen is paramagnetic, both outer electrons spin in the same direction, which is what makes oxygen so important maybe! But it produces a near IR absorption band, when it should not have one! Such analysers get immediate application in monitoring incinerators etc, preventing harmful emissions, because the unit can work at temperatures up to 1500C.

This TruePeak is not cheap, but it is not an inordinately expensive unit: and it must be one of the best of the ‘Boy’s Toys’ available to satisfy any Process Gas Analytical Research Chemist this Christmas!.

** Vaisala also introduced an oxygen monitoring system using a similar tunable diode laser detector earlier in the year: this is called the Vaisala Spectracap Oxygen Transmitter.

Again this can be flange-mounted directly into a process without sampling or sample conditioning equipment, but this unit uses a stainless steel probe in the flow stream, which tolerates chemicals and excessive amounts of moisture.

This Vaisala probe is quoted as suitable for process gas monitoring, in terms of monitoring oxygen in gas generation systems, inert gas blanket monitors, and monitoring the gas levels in composting and biological processes.

Their unit is not intrinsically safe, and I have the impression it would not be suitable for insertion into flue gas streams.

But a sampler system is available, to extract a small gas flow for analysis.

Currently Vaisala only offer this unit tuned for oxygen measurements.

** Offshore Europe in Aberdeen turned up yet another application of a Tunable Diode Laser (TDL) in a gas detection system from Allison Engineering.

Apparently their TDL system is used as a perimeter gas detection alarm, with the laser beam bounced around a whole area, like a chemical plant or a compound.

The typical gases detected this time are HF or H2S, in the atmosphere traversed by the light beam.

The concentration in the atmosphere is monitored to provide an alarm system to initiate a process shutdown of the plant should a major escape of these gases be seen, detected by the TDL, to protect the surrounding population, and environment.

Such systems as these are apparently in operation around critical areas on chemical plants in Coryton and Grangemouth.

** A Manchester based company, surprisingly called TDL Sensors, announced a process tunable diode laser spectrometer in 2006.

This product was quoted as designed primarily for the in-situ measurement of gases such as O2, CO, CO2, H2O, HCl, HF and NH3 from ambient temperatures up to 1500C, with both cross duct and single access point configurations available.

** Water vapour measurement in natural gas is particularly important as high moisture levels can encourage the formation of methane hydrate, a solid that forms in the pipeline and reduces flow or can even block the line completely.

The heart of the water vapour sensing system from IMA for this duty is a small tunable laser diode (about 2mm2) that produces a very narrow and specific wavelength of light tuned to a harmonic of the water vapour molecule in the near-infra-red band.

The light causes the molecule to vibrate and therefore absorb energy.

The laser is scanned through the specific wavelength of interest and, by comparing the light energy being absorbed at a water vapour wavelength to the light energy at surrounding wavelengths, a very precise measurement can be made.

What sets The IMA tunable diode laser (TDL) systems apart from other NIR analysers is the ability to get down to parts-per-million levels.

**Siemens has a Process Analyser that appears to use TDL techniques.

Up to three in-situ cross duct sensors, optionally available in an intrinsically safe version for operation in Ex zones, can be connected with their LDS analyser.

The list of gases able to be measured with their NIR diode lasers includes gases like O2, NH3, HCl, HF, H2O, CO, CO2, H2S, CH4, …and it is continuously growing with the state of the development in semiconductor laser technology.

Even traces of NH3, HCl or HF concentrations can be determined in wet process gases in front of any gas cleaning step.

See the LDS6 on https://pia.khe.siemens.com/index_process_analytics.products_solutions.products_systems.continuous_process_gas_analytics.in-situ-10231.htm.