德国InfraTec热像仪在火灾早期预警中的应用
热成像解决方案
WASTE-SCAN废弃物堆场火灾早期探测管理系统
作者：InfraTec GmbH 译者：雅世恒源
废弃物堆场是作为临时储存工业和家庭垃圾的场所，因此废弃物堆场是一种高风险的环境污染源。尽管其对于地下水污染的危险可以通过建筑构造的手段给与完全的预防，但是由于火灾造成的危险化学品燃烧生成的有害气体和生成物给环境和人类带来的危害，则只能通过防患于未“燃”的火灾早期预警的措施来预防。
根据德国《联邦排放保护法》(BImSchG)的规定，放置和处理危险废弃物的工厂须具有火灾早期预警装置，其中一种预警探测方法就是使用红外热成像法。德国北莱茵地区威斯特法伦州环境管理局的8号环境文件编制了“使用红外热成像检测方法避免废物焚烧厂火灾”基本规则，包括这种红外热成像火灾早期预警系统的概念，安装和检查制度。
废弃物处理场所回收、堆积的废弃物存在着很大的火隐患，WASTE-SCAN为发现这些废弃物的表面温度变化提供了一种独特的监控方法。这种方法可以在废弃物燃烧之前及时预防。这样,废弃物燃烧所产生的那些未经处理的产物和有毒气体污染物能够得到有效地控制,从而尽量减小对人类和环境带来的危害。,这项技术在欧洲的成功应用证明了WASTE-SCAN废弃物堆场火灾早期探测管理系统的优越性，该系统是基于红外热成像原理。即使相距很远,它也可以对废弃物表面提供一个持续地,非接触地温度测量。
这个系统最主要的部分来自德国英福泰克红外传感与测量技术公司(InfraTec GmbH Thermosensorik und Messtechnik)制造的最新一代高性能红外热成像系统VarioCAM hr head。 高性能红外热成像系统VarioCAM hr head采用符合IP65防护等级全金属坚固外壳,适合在各种恶劣复杂的环境中使用。附加一个高分辨率可见光摄像机可以用来帮助调整最佳的工作位置。废弃物储仓被分割成几个监控区进行自动扫描,精确度不低于0.2°,最大的循环周期小于2分钟，一个完整的废弃物储仓可以通过遥控或手控来监视。为了便于仔细观察可疑区域，可以从自动模式切换到手动模式。红外热成像系统VarioCAM hr head须安放在所有监控区域上方,信号处理单元放置在废的无尘控制室里。WASTE-SCAN废弃物堆场火灾早期探测管理系统的设计特点主要有以下特征:适于连续工作(一天24小时,一年365天),红外热图像到中控室的传输,软性布线技术(铜线或是光纤),TFT色彩显示以及设在吊架操作室和控制显示室的控制面板,在控制室利用PC机完成系统维护(可遥控).探测的信号通过烟或尘埃传输时会有一定的衰减,但可以借助于黑体参照物得到补偿.对于有内置校准参照物的红外热像仪就不需要再次校准了。
红外热图像分析、系统硬件控制和仪器操作由一整套软件来进行,软件运行界面可以连续的展示系统状态,提供所有相关的信息。比如:连续实时显示所有监控区域的当前红外热图像,每一个区域的最高、最低和平均温度,所有区域的温度-时间变化趋势图，操作记录以及红外热像仪和系统的状态显示。附加的实时显示器可以提供与红外热像仪或者可见光摄像机同步的实况图像。可见光图像可以方便地融合显示热成像的"热点"。这种热图像和可视图像的融合显示可以使机器在最佳的角度监控,特别是在一些周围环境比较恶劣的地方。当温度超过警戒温度时,系统就会自动的发出警报信号。
WASTE-SCAN® Waste Dump Fire Detection
The collection of waste materials in waste combustion plants or waste dumps holds a high risk of a fire emergence.
WASTE-SCAN offers a unique monitoring solution to detect thermal developments at the surface of the collected waste in such a way that fires can be prevented upfront and not only after their emergence.
The uncontrolled production and emission of toxic air pollutions by burning waste can be forestalled efficiently. Hazards to people and environment are minimized.
Applications in Europe have proven the advantages of WASTE-SCAN as a solution for the waste management in the private and public sector.
Pict. 1: Bunker of a waste combustion plant Pict. 2: Typical waste collection
WASTE-SCAN - thermographic camera VarioCAM® head
The automated early fire detection system WASTE-SCAN is based on the principle of infrared thermography. It provides a continuous, non-contact temperature measurement at the surface of a waste collection, even over large distances.
Main item of the system is the high-resolution thermographic camera VarioCAM® head manufactured by the German company JENOPTIK Laser, Optik, Systeme GmbH. It is based on an uncooled microbolometer detector FPA.
The thermographic camera VarioCAM® head has the following performance parameters:
(320 x 240) pixels for high geometrical resolution
high-contrast, low-noise thermal image
localisation of hot spots, even under dusty or smokey conditions
spectral range (7.5 ... 14) µm
real-time data acquisition at 50 / 60 Hz frame rate
internal automatic calibration.
Pict. 3: Thermographic camera VarioCAM® head
WASTE-SCAN - complete bunker monitoring
The thermographic camera VarioCAM® head is mounted in a robust housing for operating under harsh ambient conditions. It can be (optionally) completed by an additional colour video camera to enable the operator an optimal orientation.
The complete waste bunker could be monitored with full geometrical resolution by one single camera using a remote-controlled pan / tilt head.
Pict. 4: Thermographic camera within robust housing at pan / tilt head
The bunker is partitioned into several inspection sectors which are automatically scanned with a position accuracy of < 0,2°. The maximum cycle period is < 2 minutes. For observing suspect spots and evacuating critical objects the operation can be switched from automatic mode to manual control.
Pict. 5: Waste bunker monitoring with one single thermographic camera (schema)
WASTE-SCAN - customised system design
The thermographic camera must be installed above the monitored bunker area. The signal processing units should be placed best in clean control rooms of the waste combustion plant.
The customised system design can be described by the following main features:
suited for sustained continuous operation (24 hours / day, 365 days / year)
transfer of thermal images from the camera to central control rooms
flexible wiring technology (copper or fibre optics)
TFT colour displays and control panels in crane operator's cab and master display room
system maintenance at PC in control cabinet (optional remote control).
Pict. 6: Camera head above crane operator's cab Pict. 7: TFT displays in crane operator's cab
The reduced atmospheric transmission by smoke or dust can be compensated by means of a large surface black body reference. It is not necessary for the calibration of the thermographic camera - it is calibrated automatically by internal references.
Pict. 8: Black body reference (optional)
Pict. 9: Control cabinet
WASTE-SCAN - user interface
The evaluation of thermal images, the hardware control of the system's components and the handling of the system are realised by a powerful software suite, suited for Windows 2000 or XP.
The User Interface is continuously shown on the system displays and provides all relevant informations, such as:
continuous display of current thermal images of all sectors,
maximum, minimum and mean temperature of each sector,
temperature-time graphs of all sectors,
operation logging and
camera and system status indication.
Pict. 10: User interface with thermal images, temperature values, temperature-time graphs of all sectors, log and status windows
The additional live displays provide simultaneously the current live image of the thermographic camera or the VIS image of the colour video camera. The VIS image can be optionally merged with the hot spots of the thermal image. The combination of thermal and visual image enables the operator an optimal orientation, especially under harsh ambient conditions.
Pict. 11: Video image with merged hot spot
WASTE-SCAN - alarm release
The system generates automatically alarm signals, when the temperature values exceed critical thresholds. The signal processing allows the realisation of multi-level alarms with adjustable warning and alarm threshold values. Additionally, the evaluation of long-term temperature trends with adjustable time basis is possible.
For subsequent analysing the fire formation the alarm situations are documented including image data storage.
Further Information
InfraTec GmbH, Dresden
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