High Alumina Alternative to Saddles

Cell Stone Extruded monolith is an alternative to random packed media. Monolith requires smaller recovery chambers (lower bed height and higher allowable velocities) to reach the desired thermal efficiency. Due to its thin wall thickness, as the heat dissipates rapidly, the monolith must be cycled more often than random packed media to achieve the desired thermal efficiency.

On a cubic foot basis, monolith will cost about 2.5x greater to purchase than random packed chemical stoneware. When the process fume is relatively free of particulate, and considering the price differential between random packed media vs monolith, the cost saving when building a new RTO is negligible.

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Cost Savings

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The savings is realized with the foundation costs, as a full complement of monolith weighs about half that of random packed media. In new applications where there is a possibility of monolith clogging due to particulate, a wider monolith cell size, such as 25 cell should be used.

To attain 95% thermal efficiency, using 25 cell, the same amount of monolith as random packed must be used; simply because of the 25 cell’s inability to transfer heat in an efficient manner (surface area of 164 ft²/ft³ for 25 cell vs. 305 ft²/ft³ for 43 cell).

To achieve a thermal efficiency equal to 43 cell, the system needs double the monolith height using 25 cell, and a cross sectional area equal to that of random packed must be used. Make no mistake; all media will clog…it’s just a matter of when.  How long before the RTO plugs will depend on the process, the amount of particulate present and the media selected.

Typically in an RTO where random packed was used, conversion to monolith first requires at least 12” of random packed media just above the cold-face plate to force equal flow distribution over the entire monolith surface.

Without this addition, air flow through the bed will be uneven, generating less than adequate thermal efficiency. It is also suggested that a multi-layer approach be used (2 different types of media). Because of its heat storage ability, including a 12” layer of Cell Stone ULTRA, installed on top of the monolith to retain heat, delivers longer cycle times, which then dually helps in destruction efficiency and longevity of the RTO equipment.