Monday, 14 May 2012

Sniffing the way to environmental conformity

Thames Water uses analysers to meet stringent environmental standards

Mogden Sewage Treatment Works is one of five in the London (GB) area being upgraded by Thames Water, to ensure the stricter treatment standards to be introduced by its regulator, the Environment Agency, in 2013 are met. As Mogden is situated in a densely populated area and part of the upgrade project includes modifying the digesters, Thames Water has added new odour monitors around this area, which all use industry-leading Jerome hydrogen sulphide analysers and are linked to the SCADA network. ABLE supplied the eight Jerome 631-XE analysers used to expand the number of monitors from the five existing boundary monitors to 13, all of which are located in strategic positions around the site.

Exclusively available in Britain and Ireland from specialist supplier of process control solutions and analytical instrumentation, ABLE Instruments & Controls Ltd., the Jerome range of hydrogen sulphide analysers reliably offer the resolution, accuracy and range to measure the concentration of hydrogen sulphide to meet the stringent trigger levels set out in the site’s odour management plan.

All 13 odour monitoring systems consist of an IP67 enclosure housing a Jerome hydrogen sulphide analyser, with an air sampling inlet pipe, a thermostatically controlled enclosure heater to maintain the temperature in cold weather, and a power supply designed, built and supplied by ABLE Instruments & Controls Ltd. Each analyser samples the ambient air every 5 minutes and transmits a 4-20mA analogue signal to the site’s SCADA system. Should any measurement exceed the very strict 15ppb (parts per billion) limit, this is displayed in the central control room indicating which analyser has created the alarm. Thus investigations can be carried out quickly in targeted locations.

While some hydrogen sulphide analysers suffer from cross interference induced errors relating to the presence of sulphur dioxide, water, carbon dioxide or carbon monoxide, the rugged Jerome with its patented gold film sensor, offers a very high specificity to hydrogen sulphide enabling accurate readings down to 3ppb with a resolution of 1ppb. Designed originally with an integral rechargeable battery pack as a portable unit for immediate detection and measurement, the Jerome 631-XE offers an optional data logging module for unattended sampling as well as 4-20mA or 0-2V analogue outputs.
The latest Jerome Hydrogen Sulphide analyser is the J605 which features a longer life battery, on-board data logging and USB communication, as well as being easier to use and maintain.

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