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Gas Detection Landfill Gas H2S Increase Measured with High-range Analysers
Hydrogen sulphide levels (H2S) in landfill gas have increased and Geotech (UK) has responded to changes reported by landfill site operators by now offering analysers measuring H2S up to 10,000 ppm. Rapidly rising H2S levels are thought to be caused by waste-to-landfill content changing largely as a result of success in recycling and other initiatives to avoid sending waste
to landfill. Previously, H2S was measured at 0-500ppm – still typical for post-scrubber H2S measurement – but higher level monitoring is now essential on many UK landfill sites.
Currently the two main methods of landfill gas measurement are either with portable or fixed-
position gas analysers. Geotech reports strong interest in high-range H2S analysis at 0-10,000 ppm which is an option on its newly launched portable landfill analyser, the GA5000 . This option is also available on the Geotech fixed-position, automated landfill and biogas gas analysers, the GA3000 and the Geotech AEMS system.
As well as presenting a significant health risk to operators, H2S can also ‘poison’ the electrochemical cells which provide the most cost-effective solution for H2S monitoring.
Higher H2S levels present a greater challenge. The cells must be regularly purged with clean air. Geotech’s portable analysers are easily purged manually after taking each reading and Geotech fixed position gas analysers purge automatically. Without purging, the life of the H2S cell is dramatically reduced and accuracy compromised. Some analyser systems dilute biogas with air in order to monitor H2S continuously but there is a significant danger of adding error with this approach and it may well not be enough to cope with new, high H2S levels.
For the many landfill operators using landfill gas to produce electricity from CHP engines, accurate H2S measurement is essential. To protect CHP engines, inbuilt gas content and quality sensors may cause auto-shut down to protect engines from corrosive H2S damage and CHP engine manufacturers usually specify an upper H2S limit above which warranties can be invalidated. Consequently, landfill operators often prefer to analyse the gas used in CHPs. If the gas is not suitable for CHP use and without an H2S scrubber, likely to cause damage with excessive H2S, they may divert it to flare or use it elsewhere.
High levels of H2S are often reduced with scrubbing systems and gas analysers can measure levels before and after scrubbing. This monitors scrubber performance as well as avoiding high levels of corrosive H2S reaching and damaging CHPs.
Geotech advises that all landfill gas analysers must be used and managed properly, including appropriate purging, to give operators the reliable gas
readings essential for gas field management. As H2S levels rise, so does the need for accurate, dependable landfill gas analysis. Geotech works closely with landfill operators and other stakeholders to ensure equipment is in-line with changing conditions as well as being reliable and well-supported.
Reader Reply Card No. 79
DOD Technologies Europe – represented by Solidsense GmbH (Germany) – has launched a new portable colorimetric detection device.
The Next Generation ChemLogic Portable (CLPX) provides powerful portable gas detection to meet a wide variety of applications. Its Improved Optics Design and Automated Optics Calibration makes the CLPX the most reliable, fool proof, user friendly gas detector on the market.
New Automated Gas Standards Generator
KIN-TEK’s (USA) new automated FlexStream™ gas standards generating system is now CE approved and available in Europe, offering total flexibility for creating precision gas mixtures. Mixtures are produced by diluting the emission from permeation tubes, or diffusion tubes with an inert diluent, typically nitrogen or zero air.
The FlexStream™ is ideally suited for creating trace concentration – ppm, ppb, and pptr – mixtures. An internal microprocessor sets the operating mode and automatically adjusts dilution flows to achieve desired concentrations.
The FlexStream™ can also be controlled remotely by a PC or process computer using Modbus connectivity. Using an external PC allows remote control of the FlexStream™, uploading QC methods that can run automatically, and evaluating ‘scenarios’ to aid in setting up the unit to create specific mixture concentration ranges.
Reader Reply Card No. 192
The CLPX is a versatile instrument that can be configured to detect a variety of gases, eliminating the need to purchase different instruments or different gas keys to sample different gases. Changing the instrument from detecting one gas to another requires a simple change of the cassette.
The CLPX uses DOD Technologies’ reliable ChemLogic tape technology to detect toxic gases and utilises the most advanced electronics and analysis software to meet the needs of health and safety professionals.
Reader Reply Card No. 80
New Colorimetric Instrument Offers Simple and Reliable Detection for a Wide Range of Gases
New Mobile Gas Monitoring Perimeter System
Oldham (France), an Industrial Scientific recently introduced the Mobile Perimeter System (MPS) IV. The MPS IV is a mobile gas monitoring platform that can be rapidly deployed for temporary or remote gas detection applications. It is solar powered, has onboard strobe and siren, and can be configured with wireless communication, making it a truly stand- alone mobile gas monitor.
“The MPS IV provides a unique solution for our customers who need to monitor for potentially dangerous gas levels in areas where conventional wired gas monitors are difficult or costly to install,” says Tom Cunningham, President, Oldham.
The MPS IV monitors up to four gas readings simultaneously and can transmit those readings wirelessly back to a primary alarm station. The monitoring platform is configurable with a convenient tripod mount, or it can be wall mounted, pole mounted or mounted using available magnetic mounting brackets
Reader Reply Card No. AET Annual Buyers’ Guide 2012
www.envirotech-online.com 81 Reader Reply Card No. 82
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