Distributed gas sensing using hollow core optical fibre

使用空心光纤的分布式气体传感

• 批准号: EP/X012182/1
• 负责人: Jane Hodgkinson
• 金额: $ 109.69万
• 依托单位: CRANFIELD UNIVERSITY
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FX012182%2F1
• 关键词: Distributed; gas; sensing; using; hollow

Distributed optical fibre sensors can map measurements along an optical fibre, and are commercially deployed for the measurement of physical parameters such as temperature, strain and acoustic emission. They are used to monitor large structures such as pipelines, wind turbines, oil and gas wells, underground electricity cables, and geological sites used for carbon capture and storage. The fibre can be installed along or around the structure, and measurements read by a single interrogator box connected at one end. A large number of sensing sections can be monitored, e.g. every 1 m along a 100m - 1km length. The ability to map measurements in space and over time provides a rich source of information that has revolutionised the understanding and operation of large engineering structures.Distributed measurement is not currently available for chemical parameters. Our vision is to develop a new distributed sensor that can detect, locate and quantify gas concentrations along the length of an optical fibre. The sensor will combine the performance advantages of laser spectroscopic measurement of gas with the rich information content of distributed sensing. The process industries have well-established sensors for detection of potentially explosive hydrocarbons, including methane. For conventional point-by-point sensing, the UK Health and Safety Executive recommends that there should be no more than 5m between each sensor. If applied across an entire site, this would require thousands of sensors, therefore coverage is limited to safety-critical areas. Challenges include routine calibration, maintenance and replacement of sensors in difficult to access areas. Methane has a greenhouse warming potential of 32x that of carbon dioxide over a 100 year period. As the main constituent of natural gas and biogas, and a product of anaerobic processes within landfill sites and wastewater treatment, methane emission is an ongoing and significant problem. Reduction of fugitive methane leaks from industrial sites is recognised as an early target to reduce greenhouse emissions, but this requires a step change in measurement coverage. Site surveys can miss episodic leaks; to minimise emission requires a permanently available solution. The current generation of point sensors can miss fugitive leaks, which can originate from all over a site and be large enough to require mitigation, but may be below the detection threshold of existing flammable gas sensors. Many fugitive leaks are only detectable within a few metres downwind of the source, therefore an impractically large number of point sensors would be required for full site coverage.Currently available alternatives include passive thermal imaging of gas leaks, which has quantification / fail safety issues and requires a clear line of sight, and acoustic emission sensors, which can only find high-pressure leaks and are difficult to use in noisy environments. Site perimeter sensing using open-path optical (usually laser) beams can work well, but requires a clear line of sight and provides limited information on leak location.A new strategy is needed to complement these measures. Distributed optical fibre gas sensors have the potential to address the above issues; because gas can be measured along the sensor's entire length, with no significant gaps, leaks are less likely to be missed. Recent technology developments make a distributed gas sensor an enticing possibility. The Cranfield team has developed a novel interrogation instrument for gas detection in multiple sensing regions along a fibre, with high sensitivity. Southampton researchers have developed new hollow core fibres (HCFs); by drilling tiny side holes along the fibre length so that gas can enter the core, light can detect its presence. Together, we aim to develop a working demonstrator that can be field tested on simulated gas leaks.

分布式光纤传感器可以沿着光纤沿着映射测量，并且在商业上被部署用于测量诸如温度、应变和声发射的物理参数。它们用于监测大型结构，如管道、风力涡轮机、油气威尔斯井、地下电缆以及用于碳捕获和储存的地质地点。光纤可以沿着或围绕结构安装，测量值由一端连接的单个测量盒读取。可以监测大量的感测区段，例如沿着沿着100 m-1 km的长度每隔1 m。在空间和时间上绘制测量图的能力提供了丰富的信息来源，彻底改变了对大型工程结构的理解和操作。分布式测量目前还不适用于化学参数。我们的愿景是开发一种新的分布式传感器，可以检测，定位和量化气体浓度沿着长度的光纤。该传感器将联合收割机结合气体激光光谱测量的性能优势和分布式传感的丰富信息内容。过程工业具有用于检测潜在爆炸性烃（包括甲烷）的完善的传感器。对于传统的逐点传感，英国健康与安全执行局建议每个传感器之间的距离不应超过5米。如果应用于整个场地，这将需要数千个传感器，因此覆盖范围仅限于安全关键区域。挑战包括常规校准、维护和更换难以进入区域的传感器。在100年的时间里，甲烷的温室效应是二氧化碳的32倍。作为天然气和沼气的主要成分，以及垃圾填埋场和废水处理中厌氧过程的产物，甲烷排放是一个持续且重要的问题。减少工业场所的逃逸性甲烷泄漏被认为是减少温室气体排放的早期目标，但这需要测量范围的逐步变化。现场调查可能会遗漏偶发性泄漏;为了最大限度地减少排放，需要永久可用的解决方案。当前一代的点传感器可能会错过易散泄漏，易散泄漏可能来自整个现场，并且大到足以需要缓解，但可能低于现有可燃气体传感器的检测阈值。许多逃逸性泄漏仅在源的下风处几米内可检测到，因此需要不切实际的大量点传感器来覆盖整个现场。目前可用的替代方案包括气体泄漏的被动热成像，其具有量化/故障安全问题并且需要清晰的视线，以及声发射传感器，其只能发现高压泄漏并且难以在嘈杂的环境中使用。使用开放路径光学（通常为激光）光束的场地周边传感可以很好地工作，但需要清晰的视线，并且提供的泄漏位置信息有限。需要一种新的策略来补充这些措施。分布式光纤气体传感器具有解决上述问题的潜力;因为气体可以沿着传感器的整个长度沿着测量，没有明显的间隙，泄漏不太可能被遗漏。最近的技术发展使分布式气体传感器成为一种诱人的可能性。克兰菲尔德团队开发了一种新型的询问仪器，用于沿着光纤的多个传感区域的气体检测，具有高灵敏度。南安普顿的研究人员已经开发出了新的空芯光纤（HCF）;通过沿着光纤长度钻沿着微小的侧孔，气体可以进入核心，光可以检测到它的存在。我们的目标是共同开发一种可以在模拟气体泄漏情况下进行现场测试的工作演示器。