Black Liquor Recovery Boiler Smelt Bed Imaging
A black liquor recovery boiler is a vital component of the pulp and paper industry, designed to efficiently recover chemicals from black liquor, a byproduct of the pulping process, through combustion and subsequent chemical recovery processes.

It provides a significant proportion of the energy required for the pulp and paper mill's operations, often producing up to two-thirds of the facility's total energy needs.

Imaging inside a black liquor recovery boiler is mandatory for insurance purposes as visualising the combustion and recovery processes reduces the likelihood of an incident. Thermal imaging using an infrared (IR) camera takes it a step further as it also monitors temperature gradients and gives a much clearer image. This is especially useful for assessing smelt bed geometry and detecting potential issues such as salt cake accumulation, ensuring efficient operation and promoting safety.

Maintaining the ideal temperature in the smelt bed is crucial for efficient chemical extraction – in this case, the hotter the better, with smelt bed temperatures over 1000 °C (1830 °F).  However, as temperatures rise, traditional infrared (IR) imaging struggles to provide clear visuals. So, what's the solution?

AMETEK Land’s MWIR-B-640, is an advanced highly accurate radiometric IR camera with spectral filtering, designed to deliver invaluable insights in extreme conditions.  It has a 3.9 µm spectral response working in the midwave infrared range, enabling a clear view through dusty/smoky and hot furnace atmospheres.  But why does temperature affect image quality, and what sets one IR camera apart from another?

The answer lies in the physics of infrared radiation. As temperatures increase, thermal radiation intensifies, overwhelming conventional IR cameras and resulting in distorted images. However, advanced models like the MWIR-B-640 employ innovative techniques to mitigate these challenges, offering clearer imaging and precise thermal data despite the temperature extremes.  AMETEK Land’s thermal imagers are radiometric which means that every pixel in the image has a temperature value, increasing the accuracy and delivering precise process monitoring.

The MWIR-B-640 comprises a thermal imager coupled to an infrared borescope and mounted in a cooling jacket on a pneumatic auto-retraction system (LPAR) to protect the instrument from overheating. The jacket uses compressed air to keep the optics cool, and a small flow of instrument air protects the tip of the probe from contamination. The highly efficient cooling jacket avoids the need for water cooling.

Does this give you a clearer image of the inside of a black liquor recovery boiler than you currently have?

What additional control to your process would you have if you could see the smelt bed geometry clearly and monitor temperature gradients across the recovery boiler?

What temperature would you ideally want the smelt bed to be?  Get in touch if you have a black liquor recovery boiler you want to try out our system on to see how much more valuable information we can give you than your current system.

Safely running a black liquor recovery boiler requires a comprehensive approach that integrates technology with operational expertise. With tools like the MWIR-B-640, operators can navigate the complexities of black liquor recovery with confidence, ensuring both efficiency and safety are never compromised. So, when it comes to managing your smelt bed, remember: with the right tools, the possibilities are endless.