Additional work on towers with standard and new high performance packings is called for. In our view, the approach of Leva has many merits. Data from fertiziler plants would be very useful. Characterization of newer packings would also allow better comparisons which would help owners in deciding what to do. There is also an open question as to packing heights and the extent to which mist eliminators can be counted on to finish the mass transfer process. Similarly, using a large number of irrigation points has been advocated by some to allow much shorter packing heights. Candles can do a good job of removing residual sulfur trioxide but only if the candles are irrigated. This happens sometimes by default if the distributor generates spray if the tower is overloaded. Candles are more expensive than mesh pads and it may be less expensive to use more packing. More irrigation points, over one point per square foot, would clearly be desirable with smaller packing and also with mesh or similar packings where liquid tends to fall
vertically. The value of high irrigation points counts with large saddles is debatable, especially as more points leads to systems which are more expensive and also much more easily plugged with chips because of smaller distributors holes or downcomers.
References
1. VFF Data Sheet for Novalox Saddles
2. U.S. Stoneware Design Manual, Pressure Drop vs. Gas Rate for 1 1/2" INTALOX Saddles, Ceramic
3. Dr. M. Leva, private communication
4. Tower Sizing Program, Kock Engineering
5. Dr. G. A. Morris, ICI, private communication
6. Perry's Chemical Engineers' Handbook, 6th Edition, Figure 18-38
7. Website, http://www.epa.gov/, TTNWeb, Clearinghouse for Inventories and Emmission Factors
Acknowledgements
Wave Packing is a registered trademark of MEC
INTALOX is a registered trademark of Norton Chemical Company
NOVALOX is a registered trademark of VFF Industries
HPTM is a registered trademark of CECEBE Technologies Inc.
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