Emissions monitoring at some pharmaceutical process plants.can throw up interesting and unexpected compounds. Protea uses the latest infra-red spectrometers and powerful spectroscopic soft-ware to identify exactly what is out there
The monitoring and control of industrial emissions has been high on the environmental agenda in the UK for almost 50 years, since the first large-scale programmes to measure sulphur dioxide and 'black smoke' were set up in 1961. Since then, UK air quality has greatly improved - to the extent that the famous "pea-souper" smogs are now but a distant folk memory.
Today, industrial plants have an ever-increasing barrage of legislation and regulation to adhere to with strict requirements regarding the nature and quantity of allowable stack emissions and tight timetables of monitoring and control to be met. The stakes are high at this end of the pipe: if a plant loses its emissions monitoring capability, then within hours it may be shut down completely.
Even the best-maintained site can lose a sensor with little or no warning, making the availability of a rapid back-up critical. This is where companies such as Protea, which specialise in process investigation, come in.
Protea can measure the environmental performance and efficiency of existing processes, and is expert in the use of monitoring techniques such as Fourier Transform infra-red (FT-IR) and mass spectrometry. It carries out MCERTS-accredited monitoring of gas emissions from all types of manufacturing processes in the UK and Ireland.
As well as these expert monitoring services, Protea manufactures portable analysers to its own design. Its ProtIR 204M portable FTIR instrument is designed specifically for stack emissions testing and process investigation and can be deployed rapidly on site should a monitoring system go offline.
"This is very much a wheel it in, plug it in. machine," says Protea's Andy Toy. "A man in a van can get it onto site, roll it up to the stack, put a line into wherever it is that the samples are to be drawn from and press Go."
The ProtIR 204M was the first analyser to be specifically designed for use as a back-up continuous emissions monitor (CEM) for operation within the European Standard EN 14181 and simultaneously measures all gases required on Waste Incineration Directive permits.
"The thing with emissions monitoring," explains Toy, "is that you don't always know what it is you're looking for. With combustion industries like waste incineration it may be fairly
predictable - carbon monoxide and oxides of nitrogen are the main gases of interest here. But in the chemical and pharmaceutical markets you can find quite a complex mixture of organic compounds. This is why we made the machine as versatile as we could."
As well as taking the infra-red spectra of the stack emissions, the ProtIR 204M has an inbuilt oxygen monitor and can accept inputs from additional external systems, such as dust monitors. All this in a device just a metre high and 60cm wide that can be wheeled into place as easily as a suitcase.
With any sensor technology, the value of the information yielded depends on both the quality of the data collected and the power with which it is analysed. Protea uses GRAMS software from Thermo Scientific, supplied by UK distributor Adept Scientific, to validate the spectra collected on the ProtIR 204M.
GRAMS is a premier spectroscopy suite that enables data to be visualised, processed and managed and is compatible with many different types of instrument. "It has a number of features that are useful for producing calibration spectra like the spectral maths facility and the way you can add and subtract spectra," explains Toy.
"We use a partial least squares plug-in called PLSplus/IQ that extends it even further to build models of the spectra. We plug the calibration spectra into the model - and you can put
hundreds of them in - then using the tools in GRAMS, we can optimise the models to pick out features that best suit the job. At this stage, we haven't even seen a stack emission sample yet - we're just testing the model to see if it could predict, say, benzene. We can see what we would expect with benzene, then add acetone or water or both, and review it.
"It gets really interesting when you find something unexpected in the sample - in what we call the component matrix. The customer might tell us that there are five compounds in the matrix, but in reality the analysis might show twice that number, so then we have to revisit the model and start building it up.
"There was a good example of this a few months ago, when we spent a little while puzzling over the spectra we obtained at a pharmaceutical plant. After a bit of detective work, and using the power of GRAMS to build several spectral models, we came up with some far-fetched oxide of silicon. When we presented the information to the client, he said: Oh yes, we use that in the process - but it shouldn't be in the emissions. - but we'd found it there."
analytical power
This sort of example shows the power of modern analytical technology and its potential for not only monitoring compliance with regulations but also as a plant maintenance indicator. The detection of such unexpected components could indicate a fault in the scrubbers or perhaps further upstream.
Toy clearly revels in the power: "We can work on any batch chemical and pharmaceutical plant, incineration plant or just about any other industrial site, with a quick response and long monitoring periods.
"In the old days you would put a tube into the flow, suck out a sample for an hour and then send it off to the lab for analysis. Now we can do it continuously for weeks and with our ProtIR spectrometer and GRAMS software we can speciate out all the organics in the stream. Nobody else can do that!"