Thoresby Colliery has been equipped with the latest Trolex Sentro 8 gas and environmental monitoring system and a Trolex Sentrum methane drainage monitoring system. At Thoresby, the environmental or eModules used are for detecting CH4, O2 and CO in two ranges from 0 – 50 ppm and 0 – 500 ppm. The coal mine is also using remote or rModules with an output of 0.4 to 2V for remote sensors. The Sentrum system is used for methane drainage pipe monitoring to measure methane purity. This methane is then used in power turbines for the mine’s consumption or providing energy for export onto the grid. The mine may also sell on methane in the future to other companies. The accurate continuous monitoring of methane composition by Trolex Sentrum is crucial for the plant to perform satisfactorily.
An intensive two-year development program by Trolex on Sentro 8 resulted in what it describes as “a completely new concept in environmental and gas detection. It’s an integrated multi-purpose sensing station ready to be configured to meet gas detection and condition monitoring requirements without the need for complex investment in system design or the need for specialist back-up. The system features intelligent inter-changeable sensing modules served by universal data communications architecture, making it straight forward to network sensor stations to a master computer and expand the system if required at a later date.”
Sentro 8 is so named as it can accommodate up to eight pre-calibrated sensing modules. These are literally intelligent ‘plug-and-play’ elements, each with its own processor for intelligent data storage and signal conditioning circuits. Indeed, they have a massive capacity to store up to 4,000 points of data. They are designed to continuously display the data they retrieve, store the full service history such as data logging, calibration, failure modes and alarm settings, and they run self-diagnostic checks. They are also designed to be simply replaced with pre-calibrated modules whenever required, making maintenance, service and calibration straight forward.
The Trolex Sentrum system has also been installed at Thoresby. This, explains Trolex, “is another product which was in development for two years before being launched last year. Unlike other systems before it, the Sentrum system keeps continuous high accuracy monitoring of methane. It uses complex algorithms to correct the effects of non-methane hydrocarbons cross-sensitivity, together with mass flow calculations. It uses infra-red detection coupled with a unique method to measure the methane content from the sample on a continuous basis. The way this works is that an initial gas analysis is used to ‘train’ the system and subsequent analysis can be used to fine-tune the system. Contributions to the overall signal from the detector caused by methane and other hydrocarbon gases are evaluated and the methane content is derived from the overall signal and the individual contributions from the different gases.”
