Industrial Solutions

Transient Thermal Event Monitoring

Transient temperature variation is a critical thermal event in many industrial processes, including ablation, welding, combustion, and power generation efficiency improvements. In these harsh environments, the startup events could rapidly increase temperature within short time, except the high-pressure, high gas flow rate, and thermal blast induced vibration, such as gas turbine blade vibration at startup moment. Many failure modes from industrial machinery systems are due to inappropriate transient temperature control. For static or slow-varying temperature measurement the thermocouple, pyrometer, and blackbody techniques have been favored historically, but they are not suitable for transient thermal detection with a bandwidth higher than 10-100Hz. Transient temperature detection with fiber sensor is highly desirable due to their advantages in low mass, small size (ø0.125mm x2mm), low specific heat, multiplexing, multi-point distribution, and electromagnetic interference immunity. With silica fiber sensor its maximum operation for dynamic thermal detection could be up to 1200°C, while sapphire fiber sensor could be used up to 1800°C. The thermal response rate could be from 150°C to 300°C per second. Such a dynamic thermal response feature could be leveraged for fast industrial process monitoring and diagnostics (M&D). One of its merits lies in its guided-mode nature that strongly limits ambient light for not overwelming the signal background. To provide a real high dynamic thermal event monitoring solution, Boston Instruments could provide either thermal radiation-based transient thermal event detection or FBG sensor wavelength-based transient thermal event detection for measuring dynamic temperature variation. Boston Instruments ThermoLine™ sensors could provide very dynamic thermal event monitoring with 250Hz to 5kHz thermal response rate.

Thermal Event Monitoring from Electromagnetic Field Systems

Superconducting magnets and inductors are capable of generating high magnetic fields and thereby storing large amounts of energy. Every superconducting material has a critical temperature Tc for a given ambient magnetic field above which the material is no longer superconducting. If a region of a superconducting conductor loses its superconducting property (i.e., becomes normal or quenches) while current is flowing in the conductor, joule heating occurs in the normal or nonsuperconducting region. If the region is small enough, the small amount of heat will be dissipated and the region will return to its superconducting state. If not, large amount of joule heating could overcome the system's ability to dissipate the heat, the normal zone will propagate and grow larger, causing a catastrophic condition which can result in severe damage to the inductor or magnet, as even more energy is dissipated in portions of the inductor or magnet. Quenching effect of the superconducting phase to normal phase transition can be detected by thermal detection. The great challenge lies in using a conventional thermocouple for measuring hot spots from magnetic coils. In fact, for such applications any electronic sensing device would suffer from interference noise so that any detection device must be completely nonmagnetic. Fiber sensor is entirely nonmetallic dielectric material (silicon dioxide), which could be used for quenching effect and hotspot detection with axial thermal profile sensor (ThermoLine™) for dynamic thermal event monitoring and detection. The fiber sensing cable could use Teflon and PTFE nonmetallic material as sheath for protection. The dynamic thermal signal will include dynamic temperature, averaged coil temperature: localized coil temperature, and whole magnet coil thermal trend analyses etc.

Similar to MRI high-magnetic coil situation, there are many other applications from CT, x-ray and high-energy detector development, radioactive therapy dosage control, and microwave-assisted coal gasificaiton. Dynamic thermal profile detection will provide real-time transient event monitoring. In addition, utilizing a probe package of the fiber bundle based displacement sensor can be used for high magnetic field of >10T displacement detection from a superconducting magnets. In general, fiber optical based temperature, strain, vibration, and displacement sensors have demonstrated to be a desirable measurement technique to avoid electromagnetic interference issue. Boston Instruments ThermoLine™ sensors could provide very dynamic thermal event monitoring with 250Hz to 5kHz thermal response rate under high-magnetic field condition.

Temperature Uniformity Monitoring from Electric Power Generation Equipment

End-winding in electric generators, stators, and transformers are typical representations of power generation industrial systems, where the operation condition monitoring is critical part of condition-based maintenance practices. For maintaining these assets for long-term safe operations the end-winding coil inside the large capacity transformer or generator or stator may have non-uniformed temperature distribution or random vibration or displacement from different windings or locations. In some case the insulation degradation causes localized hot spots that could shorten whole equipment's lifetime, and may lead to unexpected fire, loss of the property, and damage on other electric equipment. Several methods, such as detecting dissolved gas (H2) and acoustic noise, acceleration, vibration, and RTD etc. for detecting these electric equipment structural health condition. However, fiber Bragg grating based temperature sensor is entirely nonmetallic dielectric material, which could be used for hot-spot, vibration, displacement detection.

Conventional thermal sensors, such as RTDs, are used to monitor hot spots from generator end-windings or from stator slots but the number of the sensing points are not sufficient to address hot-spot and thermal nonuniformity because of RTD size, axial and circumferential thermal profile distribution. Thus, the fiber optical ThermoLine™ sensors have demonstrated the advantages in the nature of the electromagnetic immunity and its small size and wavelength multiplexing capability. This means that one fiber sensing cable could be deployed inside the end-winding or stator slots with one penetration requirement. To avoid electromagnetic interference the fiber sensing cable could use Teflon and PTFE nonmetallic material as sheath for protection, and a hermetical sealing gland will transit fiber cable from outside to end-winding locations. Several fiber sensing cables with several FBG temperature sensors are installed in the end-windings with nonmetal sheath material for sensing cable. The packaged fiber sensor could be simply used for thermal profile, and localized thermal anomaly monitoring. More than this thermal anomalous M&D, fiber sensors could be used for end-winding vibration and displacement measurements with a properly installation package design. Boston Instruments could provide its expertise for assisting customer's to make a low-cost and reliable sensing instrument for transformer, motor, generator and any other machinery system's remote monitoring, diagnostic, control and optimization.

Downhole & Wellbore Temperature Profile Monitoring

Distributed temperature sensing (DTS) has been widely used for Oil/Gas industrial oil and gas extraction. As a fact that the flow dynamics of the hydrocarbon fluid will vary a wellbore's temperature profile. Using DTS technology for monitoring hydrocarbon production condition has become a very useful tool for gas artificial lift, multi-phase fluid composition analyses.

DTS System Application in Oil Filed & Downhole Environment


The DTS systems have been installed in several oil fields, located at North Asia since 2008. In addition, a high-pressure and high-temperature (HPHT-PT) gage, with pressure range from 5kpsi, 10kpsi, 15kpsi, and 20kpsi, is also combined together in each installation for obtaining baseline data and pressure information. There are several configurations can be designed to fit to different well production requirements. For example, a PT gage may be sufficient for single-layered oil/gas field. However, a PT gage combined with a DTS fiber cable may be a better option to ensure long-term reliability in measuring both temperature profile and single-point pressure. In other case, a looped fiber cable, an optical turnaround sub at the distal end of the fiber cable, can be used to ensure a correction for nonlinear Stokes and anti-Stoke attenuation. In specific case, a multiple or distributed PT gages could be deployed along a fiber sensing cable with multiple optical couplers. Boston Instruments could leverage its expertise to provide a right sensing system and configuration to fit to your application and budget.

Distributed temperature sensing can be deployed successfully in multiple industrial segments:

  • Oil and gas production permanent downhole monitoring, coil tubing optical enabled deployed intervention systems, slickline optical cable deployed intervention systems.
  • Power cable and transmission line monitoring (ampacity optimisation)
  • Fire detection in tunnels and special hazard buildings
  • Industrial induction furnace surveillance
  • Integrity of liquid natural gas (LNG) carriers and terminals
  • Leakage detection at dikes and dams
  • Temperature monitoring in plant and process engineering, including transmission pipelines
  • Storage tanks and vessels
More recently, DTS has been applied for ecological monitoring as well:
  • Stream temperature
  • Groundwater source detection
  • Temperature profiles in a mine shaft and over lakes and glaciers
  • Deep rainforest ambient temperature at various foliage densities
  • Temperature profiles in an underground mine, Australia

Pipeline Fouling Severity & Condition Monitoring

The great challenges for various industrial processes (food, water, power generation, petrochemical production, wellbore, water/steam generator, boiler, furnace etc.) come from fouling/scaling issues that could lead corrosion, erosion, and structural degradation. Several sensing technologies (ultrasonic, quartz resonator, x-ray and gamma-ray instruments etc.) are available for evaluating fouling severity. However, it becomes very challenge for deploying any of these instruments inside industrial environment for real-time and online fouling monitoring and detection because of elevate temperature (300-900°C) and many constrains.

Fiber optic sensor has shown its advantages for measuring fouling/scaling severity. Although fiber sensor has been used for measuring physical parameter, such as temperature, pressure, strain, vibration etc., but it is not directly measuring fouling thickness or chemicals from inside the industrial system, rather measuring hot-spot, thermal profile variation from a particular surface, pipe section, or circumferential strain variation etc. from outside the pipeline, or section of the industrial system. The sensor doesn't need intrusively install inside a pipeline, which still can measure fouling formation and its trend. This indirect sensing method make it possible for many industrial fouling detection, where the localized hot-spot, mechanical structure degradation, and anomalous thermal event can be monitored with fiber sensor arrays or ThermoLine™ or ThermoSurf™ products.

The fouling detection with the fiber sensor will require FBG sensor having highly thermal stability and survivability. Several types of fiber sensor could be used for such applications, such as chiral grating, femtosecond laser inscribed FBGs, Type-1B, Type-IIA, and Type-II FBGs etc. It should be pointed out that these fiber sensors also can be used for cryogenic thermal transient and phase transition monitoring. Boston Instruments ThermoLine™ and PresoLine™sensors could provide fouling severity monitoring for production efficiency control and optimization. The utimate goal in using these sensors is to change regular maintenance as condition-based maintenance. The obtained "Average Temperature", "Localized Temperature", "Thermal Long-term trend", and "Transient Dynamic Temperature" will be integrated together for reporting the status of "Pipeline Fouling Severity".