GAS DETECTION 47
Onshore and offshore facilities in the hydrocarbon processing sector represent sources of methane emissions. Despite the vast quantities of methane that are produced and transmitted by the natural gas processing sector, methane emission levels from a major site are generally much lower than those from a typical large landfill site.
LNG storage terminal
web of these detectors can be used to straddle an LNG terminal comfortably.
The abundance of US shale gas has led to the balance of electrical power generation in the US moving from coal as the staple feedstock to a more even balance of natural gas and coal combustion. Power generation is another area where methane detection is of primary importance.
Natural gas distribution and power generation methane monitoring
Methane emissions monitoring in the natural gas extraction, distribution and power generation sector is essential for environmental management. According to the European Pollutant Release and Transfer Register (E-PRTR), power plants, gas terminals and offshore production platforms, which reported data in the classification of combustion plants, emitted between circa 100 and 1600 Tonnes of methane per facility in 2017.
Research into methane emissions from natural gas fired power plants operating at steady state has indicated that up to 0.2% of the methane fed to the plant is emitted due to incomplete combustion. During start up, this has been shown to increase to a level up to 2.5%. To conduct this study Cavity Ring Down Spectroscopy (CRDS) instrumentation installed in a small aircraft was used to over-fly 14 natural gas fired power plants in the USA1
Adaptations, of the CRDS technique, such as the Off-Axis Integrated Cavity Output Spectroscopy have enhanced its range of applications in environmental detection and these analysers can now be used for permanent landfill gas emissions monitoring where they analyse trace levels of methane and other landfill site greenhouse gas emissions. Perhaps surprisingly, landfill sites are one of the most numerous sources of methane emissions, and according to the data filed with the E-PRTR they can also be some of the heaviest emitters of methane, which is a potent greenhouse gas.
The EU Industrial Emissions Directive and its associated BREF notes have no emissions limit values for methane from gas turbine power plants. On the other hand, BAT 45 of the Large Combustion Plant (LCP) BREF note does specify Best Available Technology Associated Emission Limit values (BAT-AELs) for methane emissions from spark-ignited lean-burn gas engines with a total thermal input greater than 50 MW. Gas engines use positive displacement pistons and work in a similar way to spark-ignition petrol-fired car engines. When compared to large gas turbines, they are suitable for smaller power generation applications typically in the range of 5 to 20 MW. This size range makes them ideal for the combustion of methane produced at biogas facilities or anaerobic sludge digesters in waste-water treatment. Methane leak detection around such equipment can be readily achieved using a fixed gas detection system with fuel cell type detectors: these are readily available, low cost devices.
can help to minimise the risks significantly, but these gas detection devices were not in common usage on the 24th of July 1979 when a massive methane explosion ripped through parts of the Appin coal mine 600m below the surface of New South Wales killing fourteen miners. The judicial inquiry that followed the accident recommended continuous gas monitoring equipment should be used in mines in the future. This was a major turning point in the history of underground gas detection and mining safety. Safety policies, appropriate enforcement and affordable gas detection technologies have all played a tremendous role in the progressive improvement in mine safety.
European Pollutant Release and Transfer Register, 2017 Site
Methane* Aterro Sanitario da Raposa
3C Waste Limited, Arpley Landfill, UK Hedeland Deponi, Copenhagen, DK Equinor Mongstad Refinery, NO Equinor Refining, Kalundborg, DK Hempsted Landfill Site, UK Brae Bravo Platform, UK
Repsol Cartagena Refinery, SP
Hazel Lane Quarry And Landfill, UK Brae Alpha Platform, UK Shell Bacton Gas Terminal Perenco Bacton Gas Terminal
Henriksdals Reningsverk, Stockholm, SE Hammerfest LNG, NO
Foinaven Floating Production & Storage, UK Orlen Południe, PL
Gasunie PeakShaver LNG vaporiser Maasvlakte, NL
Abfallwirtschaft, Halle-Lochau, DE
. Due to the long path length of the light beam, this laser adsorption analytical technique is one of the most sensitive methods for the detection of trace concentrations of small gas molecules such as methane, carbon dioxide and ammonia which are optically active in the near infrared region.
In the gas distribution sector, gas detectors are being used to improve natural gas pipeline maintenance and reduce methane leaks. Modern wearable natural gas detection units combine location tracking using cell-phone type GPS technology, cloud computing and big-data to enable gas distribution operating companies to monitor and store gas detection data from the devices worn by their employees. Maps can be generated which provide a clear indication of where gas-leak trouble spots exist. This ongoing data gathering is especially effective when used over a long period of time by teams of operators and is highly insightful in urban areas where the gas distribution grid may be aged. Low value data can become highly valuable management information which enables the maintenance and repair of gas pipeline leaks to be prioritised and thereby ensuring cost-effective and safe operations.
Landfill methane and waste water management
Automotive CNG tank in car boot Explosive impact
Methane leakage from the natural gas grid is only one example of the flammability hazard that this gas poses. Methane gas detonation is one of the biggest killers in mining history. It is a common hazard in coal mining and the issue extends into other sub-surface mining operations such as the search for gold. In a case that is sadly not unique, a methane gas explosion killed 18 miners at the world’s deepest gold mine, the Mponeng west of Johannesburg in South Africa in July 1999. The mine operator confirmed that “39 men had been drilling a rock face when their gas monitors indicated the presence of methane. They started to evacuate the area but there was an explosion before they were all clear”. Sadly, this points to the fact that whilst it is essential to select and wear appropriate gas detectors, they are in themselves no guarantee of safety in harsh and unpredictable underground conditions.
When choosing a gas detector for mining applications several criteria must be met. Firstly, the gases to be detected must comply with the local safety legislation and any additional practices in place in the mine. At a minimum, this would typically involve simultaneous measurement of methane, carbon monoxide, hydrogen sulphide and oxygen. The device must also be intrinsically safe and thereby avoid creating additional ignition risks. Beyond that, many factors come into play such as the robustness of the unit, its weight and battery life. The ease with which the daily functional test using bump-test specialty gas mixtures can be performed and the associated data capture for audit purposes are also key considerations to ensure that an operator can prove to auditing authorities that safety procedures have been correctly adhered to.
Fixed flammable gas detection system The methane gas detection technology available to miners today
Author Contact Details Stephen B. Harrison, Principal, Germany at Nexant • Kranzlstraße 21, 82538 Geretsried, Germany • Tel: +49 (0)8171 24 64 954 • Email:
sbharrison@nexant.com • Web:
www.nexant.com
WWW.ENVIROTECH-ONLINE.COM IET ANNUAL BUYERS’ GUIDE 2020/21
Captain Floating Production & Storage, UK RWE Pembroke CCGT Power Station, UK Scunthorpe Integrated Iron & Steel Works, UK Klärwerk München, Gut Großlappen, DE Repsol Tarragona Refinery, SP Tata Steel Ijmuiden, NL
Ineos Chemicals Grangemouth
RWE npower, Staythorpe C CCGT Power Station, UK
RWE npower, Didcot B Power Station, UK hanseWasser Bremen, Seehausen, DE ENGIE Zolling Power Station, DE BP Refinery Rotterdam, NL
Viridis 178, Nottingham Power Plant Esso Nederland Refinery, NL Total Antwerp Refinery, BE
ENGIE Farge Power Station, Bremen, DE
RWE npower, Little Barford CCGT Power Station, UK
Drax Power Station, UK Rosenheim CHP, DE
Landfill site Natural gas production & processing Steel production & processing Waste water treatment Oil refining
Power generation - gas fired Power generation - coal/biomass/waste fired
1 Observations of Methane Emissions from Natural Gas-Fired Power Plants, Kristian D. Hajny et al, Environ. Sci. Technol. 2019, 53, 8976−8984
* 2017 Annual methane emissions in Tonnes E-PRTR
https://prtr.eea.europa.eu/#/pollutantreleases Table is an extract from the full data base for illustrative purposes
5970 3790 3130 2230 2090 2040 1650 1190 1150 1100 855 663 663 650 566 488 480
452 358 328 282 260 235 228 203 196
176 174 134 140 120 114 110 111 107
106 102
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116
