What is furnace monitoring? The reasons for "seeing" the high-temperature inside of a furnace and the methods of monitoring.

When we talk about furnace monitoring, we might imagine "monitoring the furnace temperature." Of course, temperature is an important control item. However, in actual manufacturing processes, there are times when we want to check not only the temperature values but also the conditions inside the furnace itself.

Observe the flames and the state of combustion.

In facilities involving combustion, such as cement kilns and waste incinerators, it's not just the temperature at a given location that matters; whether the flame is present and whether there are any changes in the combustion state are also crucial management points.

Check the materials and firing conditions.

Inside a furnace, the manufacturing process progresses through heating, firing, and melting of materials. For example, in a rotary kiln, the material moves inside as the furnace rotation. In addition to temperature, understanding the state, movement, distribution, and accumulation of the material can be helpful in determining the manufacturing process.

To detect ignition or abnormal conditions early.

Monitoring isn't limited to just the inside of the furnace. Materials immediately after leaving the furnace are still at high temperatures and may ignite or accumulate abnormally during transport to subsequent process. Early detection of these conditions can not only improve quality but also contribute to stable equipment operation and prevent problems from occurring.

What problems arise when the inside of the furnace is not visible?

If you don't understand what's happening inside the furnace, it becomes difficult to detect changes in conditions or abnormalities at an early stage. Temperature readings alone may not adequately capture the state of the flame, the movement of materials, or abnormal deposits. As a result, there is a risk of delays in noticing changes in the manufacturing process, delays in understanding the impact on quality, delays in detecting equipment malfunctions, and even equipment failures or operational shutdowns.

Even if it's necessary to view the inside of a furnace, simply installing a standard camera won't solve the problem. This is because the inside of a furnace is an extremely harsh environment for measuring instruments.

high temperature environment

The furnace is extremely hot, and it's not possible to place typical cameras or electronic devices directly inside. Not only the camera, but also the lens and peripherals need to be protected from the heat.

dust and smoke

Depending on the equipment, dust and smoke may be generated, making it difficult to adequately check the internal conditions visually. Furthermore, if dust adheres to optical components such as lenses, it becomes difficult to maintain stable monitoring.

Influence of water vapor, gases, etc.

Depending on the equipment, water vapor and gases may also be present. Water droplets, dust, smoke, and water vapor should be avoided as much as possible in sight path, and if this is unavoidable, countermeasures such as air purging will be necessary. Furthermore, vibration, external thermal radiation, and dew condensation must also be considered in order to ensure stable monitoring.

There isn't just one way to manage the inside of a furnace. Depending on the equipment and purpose, thermocouples, radiation thermometer, thermal imaging, and other methods are used. The important thing is not which method is superior, but that the appropriate method differs depending on what you want to know.

From "measuring temperature" to "viewing as an image"

To determine where high temperatures are located and what the temperature distribution is like across a wide area inside a furnace, it is necessary to capture temperature as a "surface" rather than a "point." One such method is thermal imaging. By using a camera that captures thermal radiation in the near-infrared region, it is sometimes possible to capture high-temperature objects as images. By display the detected thermal energy as a thermal image, the temperature can be viewed not as a single number, but as a temperature distribution on the screen.

A furnace monitoring system is used to monitor the inside of a high-temperature furnace using images. Since it is difficult to place a regular camera directly inside a high-temperature furnace, it combines optics that transmits thermal radiation from inside the furnace to the camera with a mechanism to protect the equipment from heat.

What is a relay lens?

Simply put, a relay lens is optics that transmits thermal radiation from inside a furnace to a camera outside the furnace. Instead of placing the camera itself inside the high-temperature furnace, the relay lens is introduced near the furnace wall, and the camera captures the inside of the furnace beyond that point. By configuration optics and the camera, the high-temperature inside of the furnace can be monitored from outside.

Protecting equipment from high-temperature environments

Relay lenses and cameras are exposed to high-temperature environments, so cooling and protection mechanisms are necessary. Furthermore, dust and other particles adhering to optical components can make stable image capture difficult, so measures such as air purging are combined depending on the equipment conditions. A furnace monitoring system is not simply a camera mounted in the furnace; it's a device that combines optics for viewing the inside of the furnace with a mechanism to protect it from harsh environments.

Simply installing an in-reactor monitoring system doesn't automatically tell you the condition of the equipment. What's important is to consider in advance "what needs to be monitored in this equipment?"​

Key control points to monitor inside the reactor

What kind of equipment will it be used in?

In-furnace monitoring is not a technology limited to specific industries; it can be considered if there is a need to "confirm what is happening inside high-temperature equipment."

You can't decide based on catalog specifications alone.

In furnace monitoring, applicability cannot be determined solely by the target temperature. The necessary configuration varies depending on the following equipment conditions:

It's important to check not only the maximum temperature the device can measure, but also whether you can actually see what you want to see in the actual equipment.

Chino has been providing equipment that uses relay lenses to capture thermal radiation from inside the furnace and monitor the conditions inside the furnace as an image. The CPA-RA furnace temperature monitoring system is the successor model to that system.

A relay lens is introduced into the furnace to monitor the temperature distribution over a wide area as a thermal image. The high-pixel 720x540 pixel sensor allows for a clearer configuration of the temperature distribution inside the furnace.

Main specifications

The relay lens length and field field of view are selected according to the size of the furnace, the measurement distance, and the area to be monitored. Additionally, the "CPA-RAS" model is also available in the same series for measurements taken from outside the furnace through a window.

Examine thermal images from various perspectives.

The high-temperature thermal imaging software (CPY-VXGR) supports spot/line/area measurement, trend display, emissivity compensation, and data storage. Beyond simply display thermal images, it allows you to focus on specific locations to check temperature and track changes over time.

PoE support simplifies system configuration.

PoE allows power supply and communication to be handled through a single LAN cable, simplifying wiring. Up to four devices can be connected to one system, supporting configuration that monitor multiple locations.

View the product page for the CPA-RA furnace temperature monitoring device.