Acetaldehyde emission of high temperature beet pulp drying systems – Influencing process parameters and potential countermeasures

Acetaldehyde was reclassified as a carcinogen, resulting in new emissions limits that affect many industries that process materials such as mineral fiberboards, clay, asphalt, wood, fodder, or beet. Measurements in beet pulp dryers have shown a wide range of acetaldehyde contents in the flue gas across multiple production sites. Therefore, this paper investigates the influence of several process parameters of a high-temperature beet pulp dryer on acetaldehyde content in the raw and cleaned flue gas and the relevant side streams.

It was found that the drum load and the drum inlet temperature had the greatest impact on acetaldehyde content. The absence of molasses or carbonatation vapors did not lower the acetaldehyde content. Most of the acetaldehyde is probably formed in the drying process. Fluctuations in acetaldehyde content suggest other influencing factors that have not yet been considered. A scrubber reduced the acetaldehyde content by about 60%.