Hot Spot Monitoring for Safety

Early detection of failures in refractory materials can be caught and corrected, ensuring safety and saving production losses, Yokogawa’s distributed temperature sensor can quickly spot problems, using fiber optical temperature sensors.


ApplicationReactor and processing tanks for chemical factory with heat detection in use

Early detection of failures in refractory materials

Temperatures inside a harsh-condition reactor such as a synthesis gas reactor that produces carbon monoxide can reach as high as 1,600 degrees Celsius, and the outer surface of the reactor vessel can get as hot as 300 degrees Celsius. To protect their iron walls and enhance combustion efficiency, these facilities are lined on the inside with refractory bricks. As these bricks age and deteriorate, a variety of problems such as a drop in combustion efficiency and breaks in the iron wall can occur and result in the initiation of an emergency shutdown by the plant control system. In addition to being a safety issue, such unplanned shutdowns result in lost production and financial losses.

Fig.1 Deterioration of refractory bricks / Fig.2 Hot spots on the reactor surface

Solutions and Benefits

Quick detection of hot spots

Hot spots on the outer surface of a reactor or furnace occur wherever there are breaks in the refractory brick lining. With its optical fiber sensor cable, the Yokogawa DTSX distributed temperature sensor is able to constantly monitor for changes in the temperature of the outer wall and quickly spot problems early on before they have a chance to grow into big problems and result in plant shutdowns or worse.

Proper maintenance period according to the conditions

Any reactor or furnace with a refractory brick lining needs to be shut down more frequently than other industrial facilities so that personnel can look inside and check the condition of the bricks. With the DTSX’s ability to monitor surface temperature 24/7/365, maintenance can be performed as soon as any signs are detected that indicate deterioration in the refractory liner. This switch to condition-based maintenance ensures that problems are caught early on and corrected.

How DTSX Works

Measuring the intensity of Raman scattered light
Using pulses of laser light beamed through an optical fiber cable, the DTSX is able to detect temperature-dependent variations in signal frequency that are the result of a phenomenon known as Raman scattering that occurs along the entire length of the optical fiber cable, and it also can determine the locations of those temperature readings using light that is bounced back (backscattering) to the source.

Example: Along a 6,000-meter optical fiber cable, nearly 6,000 measurement points
By measuring how long it takes light to make a round trip back to the source (backscattering), the DTSX is able to calculate the location for each temperature reading. Abnormalities can be located with a spatial resolution of just one meter.

Fig.4 Temperature monitoring using optical fiber cable

Fig.3 Raman backscattering


There is no need to install many temperature sensors. A single length of optical fiber sensor cable can be affixed to the surface of the reactor or furnace using aluminum tape or something similar. Figure 5 shows the layout of the optical fiber sensor cable on a reactor's outer wall.

                                Fig.5 Installation examples / Fig.6 Paperless recorder's monitoring screenYokogawa DTSX3000

Key Benefits

  • Long distance, wide area coverage, a single DTSX can monitor variations in surface temperature at any point. 
  • No power supply is required for the sensor.
  • Flexible installation, measuring temperature in specific locations, accommodating the needs of all kinds of facilities, both greenfield and brownfield.
  • Lower installation, operational, and maintenance costs due to fewer wires and parts.
  • Able to operate under a wide range of conditions, can withstand temperatures up to 300 degrees Celsius.



  • Chemical

    Chemical plants rely on continuous and batch production processes, each posing different requirements for a control system. A continuous process calls for a robust and stable control system that will not fail and cause the shutdown of a production line, whereas the emphasis with a batch process is on having a control system that allows great flexibility in making adjustments to formulas, procedures, and the like. Both kinds of systems need to be managed in available quality history of product, and to be able to execute non-routine operations. With its extensive product portfolio, experienced systems engineers, and global sales and service network, Yokogawa has a solution for every plant process.

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  • Iron & Steel

    • Iron and steel industry
    • Improve quality of products, manufacturing, and operation technologies
    • Address environmental and energy-efficiency issues
    • Create the ideal plant and evolve for mutual growth
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  • Oil & Gas

    Yokogawa has a wealth of experience in every part of the oil and gas business, from offshore and onshore facilities to pipelines, terminals, and deepwater operations. We provide solutions that enhance safety, ensure accurate and reliable operation, and increase plant efficiency.

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  • Oil & Gas Downstream

    The oil & gas downstream industry has been facing an increasing number of challenges in recent years. These include the changing characteristics of the feedstock to be processed, aging of process facilities and equipment, rising cost of energy, lack of skilled plant operators who can run a refinery safely and efficiently, and the ever-changing requirements from both the market and the customer.

    Over the years, Yokogawa has partnered with many downstream companies to provide industrial solutions focused on solving these challenges and problems. Yokogawa's VigilantPlant solutions have helped plant owners to achieve maximum profitability and sustainable safety within their plants.

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Related Products & Solutions

  • DTSX200

    • DTSX200 distributed temperature sensing
    • Short range, low sampling resolution capable product
    • Measurement range up to 6km
    • 0.1 °C temperature accuracy
    • 19" rack 
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  • DTSX3000

    The DTSX3000 is the long range, high accuracy product, with a measurement range of up to 50km, a temperature accuracy of 0.01 °C, and 19" rack design.

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Have Questions?

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