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The Eye Power Station is owned and operated by EPR Ltd, a renewable energy generator in the U.K. that produced 10% of the country’s electricity from renewable energy in 2005. The station consumes 140,000 tonnes annually of chicken litter, which is sourced from a large number of farms in the region. It also includes horse bedding and feathers in the fuel, which amount to an additional 20,000 tonnes. The products are burned in a conventional moving grate boiler. The combustionashes are used as agricultural fertiliser.
Since the Eye plantwas constructed in 1992 emissions have been tightly controlled. However, from December 2005, the Waste Incineration Directive (WID) imposedlower emission limits and as a result the Eye plant made an additional€ 4.4 million investment in abatement and monitoring equipment.
The FTIR monitoring equipment was supplied by Quantitech and was configured to precisely meet the plant’s new requirements. This includedthe measurement of CO, CO2, NOx, SO2, HCl, H2O, O2 and particulates. In addition to the multi-component FTIR analyser that does the analysis, a portable one is used as a back up for Eye and its sister plants.
An MCERTS approved FTIR analyser was chosen because of its ability to perform continuous multiparameter measurements. MCERTS is the U.K.’s Environment Agency’s Monitoring Certification Scheme, which provides a framework for environmental measurements, such as continuous emissions monitoring systems (CEMS) can be made in accordance with the Agency's quality requirements. The agency has also provided guidelines for instruments to be validated at testing laboratories for compliancewith the Monitoring Certification Scheme.
FTIR analysers
Fourier Transform Infrared (FTIR) analysers are a technology that has, inthe recent past, been taken from the laboratory to online usage in CEMS. The advent of inexpensive and powerful microprocessors has made this possible. One advantage of the FTIR method is that several gases can be monitored at the same time by the same instrument. Heated versions are available that make it possible to monitor hard-to-handle gaseslike HCl and NH3 down to 10ppm. These units find application in the monitoring of combustion sources, toxic-waste incinerators, and industrial processes, as well as ambient monitoring applications for hazardousair pollutants.
FTIRs can produce detailed infrared spectra over wavelengths of 2.5 to 25 microns. Spectra are calculated from an interference pattern and matched mathematically with the sample data held in memory. A variety of algorithms derive the concentration values from these data. Digital spectra as well as calculated values can be stored. At some later time, the stored spectra can be processed to determine concentrations of other gas components that may have been deemedunimportant earlier.
Software-configured FTIR systems display all results and status messages, allow manual interactive operation during commissioning and servicing, feature self-diagnosis or remote diagnosis by modem, and the ability to archive measured and diagnostic data.
FTIR technology has become the preferred method for infrared spectroscopy, and Quantitech’s multicomponent gas analyser, the Gasmet FTIR is particularly well suited for the application because it cananalyse several gas components at once, and it can analyse hot and wet gas (e.g., hot humid applications for HCN, NH3 or HCl etc). It can also be used to analyse any gas in complicated gas mixtures
Quantitech’s Dominic Duggan says that in comparison with multiple analyser CEMS, the FTIR is “Extremely easy to operate” adding “Zero point calibration with Nitrogen (background) just takes a few minutes and is required once a day. Water vapour calibration must be performed after every major maintenance operation and at least once per year. Under normal circumstances no other calibration is required which saves our customers a great deal of time, effort, and money.”
Summarising hisexperience with the Quantitech monitoring system, Eye Station Manager, Kevin Williams says “The reliability and accuracy of the monitoringequipment are vitally important for the environmental performance of the power station. However, the data management regime not only helps us to ensure that we remain constantly within the emission limits, butalso helps us to operate the plant as efficiently as possible.
We are very happy with the FTIR monitoring technology for two important reasons. First, as a multi-component measurement technique it savesus from the extra costs that would be incurred with the addition of new parameters such as volatile organic compounds (VOCs). Secondly, theavailability of a portable FTIR that exactly mimics our on-line version means that we have a highly effective back-up system, so we do not have to worry about loss of data if a problem occurs.”
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