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Wednesday, 15 March 2017

ABB gas analysers help Thames Water to keep compliance checks to once a year

ABB gas analysers fitted to a Combined Heat and Power (CHP) plant are ensuring Thames Water meets its emissions obligations while keeping  calibration checks to once a year.

The new CHP plant at Thames Water’s sewage treatment plant at Rainham in Essex uses cakes of dried sewage sludge to power three 2MW boilers in the CHP plant. The resulting steam is fed to turbine driven generators that provide the site’s power demand, with any excess exported to the grid.

Rod Kerr, Asset Integrator for Thames Water says: “Measuring nitrogen oxide and carbon monoxide emissions are key requirements of our environmental licence. We need to provide continuous monitoring from the boilers as part of our certification for the Environment Agency permit.”

Thames Water’s environmental consultants ESG recommended ABB EasyLine gas analysers as suitable for the application.

“The most important features were that it complies with the European guideline EN 15267, which sets out the process for the testing and certification of automated measuring systems,” says ABB’s Darren O’Neill. “This legislation also requires that equipment is calibrated and serviced. At ABB, we have large service teams that allow us to meet this requirement, although the features of the products means that this is kept to the bare minimum.”
"The fact that the products are self-checking and self-calibrating  means they largely look after themselves"
Fully compliant with EN 15267, the ABB EasyLine range features internal automatic validation. Combined with ABB calibration cell technology in the photometer, this means there is no need for expensive test gas cylinders in most applications. The device registers zero point with ambient air and offers proven long term stability.

ABB's EasyLine gas analysers offer a robust and reliable solution for measuring gas concentrations 
“The fact that the products are self-checking and self-calibrating  means they largely look after themselves,” says Kerr. “Manual intervention is kept to a minimum and we just need to calibrate annually to meet the terms of our certification.”

Using ABB’s EasyLine gas analysers has delivered a number of benefits for the application. A web server is included for easy access to collected data via an Internet browser. Easy to fit, the 19" wide units are designed for rack mounting, while the compact, purgeable IP65 enclosure is suitable for wall mounting, offering a choice of installation options.

Thames Water wanted the analysers in operation on the boilers as quickly as possible and the whole contract from tender to commissioning took only seven months.

“Another requirement was the need to record data on our SCADA system,” says Kerr. “It was essential we had the ability to record data every second of every day, as well as the resolution and accuracy offered by the EasyLine.”

The data gathered by ABB EasyLine is sent to Envirosoft’s CMESuite Plus for analysis. This package also incorporates QAL3 assessment software that allows Thames Water to check the quality of the emission measurement. Presented on a graphical display, QAL3 data is assessed constantly by Thames Water’s control room staff 24 hours a day, seven days a week, to ensure it stays within limits.The software also trends the data and alarms if a non-compliance event occurs.

Future developments will see Thames Water use ABB software to set up alarm points. “The software talks easily to the analysers, so it should be straightforward to set these alarms up. The analysed data is set up with alarm points and will visually indicate a problem with the NOX emissions on the engines. A TWUL controller will then act on this alarm as agreed in the site procedures. The Environment Agency will then be informed if the limit was over our upper alarm point.

“We will identify each alarm on a list and all the alarms will also be recorded for future analysis.”

ABB’s EasyLine continuous gas analysers offer a flexible solution for monitoring of gas concentrations in numerous process and emissions monitoring applications. A single analyser can be used to measure up to five different gas components, minimizing the cost and space required. Further flexibility is enabled by a choice of Ethernet, Profibus and Modbus communications, providing users with a choice of data access options, plus customizable analogue and digital inputs and outputs.

The EasyLine range is also fully compliant with the relevant legislation. As well as meeting the requirements of EN 15627, the EasyLine range also complies with the standards set out in EN 14181 for integrated QAL3 reporting.

For more information about the EasyLine range, including the options available and where it can be used, click here.

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