This was a question was posed to me this week on meeting a prospective new customer and, having been in this industry for many years, it’s a question that I’ve been asked before. So why the specific interest in the method of Infrared Spectroscopy used by the solution we have presented?
I have a hunch, one that comes from being in and around the industry for a quarter of a century. In fact it is maybe more than a hunch, but I believe a peddled ‘message’ that FTIR is superior to NDIR. However, I think it is important to ask if this is true when considering CEMS and what difference does the technology make to a plant operator? Should a FTIR vs NDIR ‘debate’ be a sensible defining parameter when selecting CEMS?
Is the performance of an NDIR analyser the same of an FTIR analyser?
By looking through Mcerts approved products, and on the basis of the certification we can see that absolutely it can be! Ranges, uncertainties and performance characteristics between the two technologies certainly appear comparable. The MCA10 is an NDIR analyser at the top of its game, and it is evident that when looking at the components associated with permit compliance its tested performance is equivalent to its FTIR Peers. With any instrument, there are nuanced differences/ strengths and for example it may be that for a low NOx ELV the MCA10/NDIR is the more suitable device.
So, performance doesn’t appear to be a defining argument between the technologies, what other factors should we consider?
Operating Costs – Running costs are made up from several different factors:
- Maintenance intervals – the longer the maintenance interval the fewer site visits required. It can also be a proxy indicator to equipment reliability, after all the device had to prove itself on field trials for a period twice as long as the maintenance interval.
- Calibration intervals – this is typically the same as the maintenance interval. When using Shewhart charts, the calibration interval must be at least as frequent as the maintenance interval. A longer maintenance interval therefore reduces calibration gas consumption (whilst providing re-assurance that the analyser is stable).
- Consumable spares – These parts require replacing at set intervals and so in some respect are fixed costs – Systems using ejector pumps will require fewer consumable parts.
- Breakdown Spares – all certified systems are generally reliable ( subject to them being correctly specified for the application and subject to the quality of installation), but things can go wrong. The measurement cell is the heart of any analyser. NDIR cells are typically less complex than their FTIR equivalents and this is reflected in the cost of their respective parts.
- Packaging – Physically, the footprint of NDIR and FTIR devices is similar. Due to the relative simplicity of the NDIR systems, they can often have more room inside their panels. Front access only is a very important consideration, both for maintenance and for packaging inside a container or CEMS room.
- Reliability – The less there is to go wrong, fewer breakdowns will be experienced and the cost of these will be less. NDIR systems are inherently less complex.
Should you choose NDIR or FTIR analysers?
When selecting a CEM system to reliably serve your plant, if you value performance, reliability, simplicity and user friendliness then absolutely not.
The best analyser for an application should be selected on a range of criteria. When considering measurement technology, this should be in terms of performance, reliability, packaging and operating costs.
For the operator, the discussion on measurement technique can be a distraction from more important points.
If you want to know more about a class leading Hot Wet Multigas analyser system (which just happens to be NDIR) then contact us to hear about the Dr. Fodisch MCA10 analyser.
The MCA10 has an air injector – this means the sample path is free from any mechanical devices and so it is inherently more reliable than pump based systems
The MCA10 has integral O2 measurement and has been certified complete with a FID
The MCA10 has 6 Month service interval for ALL components.
To get a balanced view on a system, there is no better way than to speak to an existing site the equipment. We would encourage discussion between operators and suggest that feedback is sought on the following:
- Ask them how user-friendly the device is – ease of operation.
- Ask them about downtime of the analyser – reliability.
- Ask them about the costs of service and spares – operating costs.
- Ask them about the service team behind the day-to-day – response times and reliability.
- Ask them about QAL 2 / AST / QAL 3 Experience
Look at the CEM system on offer as a whole – don’t be distracted away from the important matter of which analyser will serve you best.
For a more in-depth look at what to consider when choosing a CEM system click below.
Stack Gas Emission Monitoring System | MCERTS Flow Meter – CEM Solutions