¦FIRE & EXPLOSION
IMPROVING EARLY WARNING FIRE DETECTION: THERMAL IMAGING AND THE INTERNET OF THINGS BY DAVID BURSELL
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iomass is commonly stored in bulk outdoor piles near the power generation facility. These mounds of material are especially prone to self-heating as they naturally decompose. The decomposition process is accelerated as moisture is introduced from rain and humidity, generating even more heat. As most biomass materials are good insulators, the internal pile heat generated is not allowed to escape and cool, thus increasing temperatures and spreading to a larger internal area. Eventually, the material begins to smolder. Smoldering and flameless fires are more easily ignited than flaming fires and more challenging to extinguish. Early detection is critical if a bulk biomass pile fire is to be avoided. Unfortunately, detecting early stage fire formation within a bulk pile fire is difficult. For example, a pile’s surface temperature may be ambient while the internal temperature could be more than 200 degrees Celcius. Traditional methods using linear heat detection cable can be used, but are susceptible to damage during material transport and are generally not recommended. Spot measurements are also used but do not detect gradient effects. Monitoring the temperature trends over time is generally more helpful in detecting the early onset of heating, when mitigation measures can be deployed before the situation becomes dangerous.
Infrared (IR) Cameras for Early Fire Detection
IR cameras operate on the heat transfer principle of radiation. The infrared camera has a focal plane array of detector elements that sense infrared light from object surfaces. The radiation captured by the infrared cam-
Biomass pile thermal image with area regions of interest IMAGE: MoviTHERM
era detector is digitized, converted to data and displayed as a viewable image. Calibrated IR cameras can report temperature measurements from specific spots, lines and areas on live or recorded images. IR cameras are the first to alert before a fire develops. They “see” a warming up of material early in the fire development process before forming smoke particles or flames. These warming materials appear as hot spots in a thermal image and are quantified with regions of interest (ROIs) like spots, lines or areas that report temperature values. Applying multiple ROIs to an image and setting temperature thresholds per ROI allows monitoring and alarming at multiple locations within the camera’s field of view. When the threshold condition of an ROI is satisfied, alarms trigger notifications to the appropriate personnel.
What is IoT (Internet of Things)?
The internet of things (IoT) refers to interconnected sensors, instruments and other devices networked into software applications that use predictive analytics and artificial intelligence (AI). These connected networks create systems that monitor, collect, exchange, analyze and deliver valuable insights into a system or process. IoT revolutionizes automation by using cloud computing to simplify integration and enhance process control.
Thermal Imaging and IoT Early Fire Detection
Fire safety for biomass storage is an area that realizes the benefits of thermal imaging when combined with IoT. By connecting infrared cameras that alert at the earliest stages of development, potential fires can more
CONTRIBUTION: The claims and statements made in this article belong exclusively to the author(s) and do not necessarily reflect the views of Biomass Magazine or its advertisers. All questions pertaining to this article should be directed to the author(s).
26 BIOMASS MAGAZINE | ISSUE 3, 2022
