Ammonia Drop Aldehyde Treatment System

This paper comes from the extended project of National Forestry Department. The study can be mainly divided to two stages, firstly the design of equipment for reducing formaldehyde emission with ammonia gas that used in laboratory and related experiments of process parameters; secondly the design of equipment used in plant and related experiment of parameters. Finally we give an estimate on the cost of ammonia treatment.The ammonia treatment could reduce the free formaldehyde emission of MDF, and the panels can achieve E1 standard, which restrict free formaldehyde emission to 9mg/100g. We found that the formaldehyde emission significantly decreased with an increase of concentration of ammonia and it was saturated at the concentration of 0.3kg/m3 through the experiment at laboratory. Moreover, the formaldehyde emission reduced with the treatment time. While the formaldehyde emission rebounded slightly with the increasing of the time and it reached to equilibrium after 18 days.The results from plant experiment were consistent with that from the trial experiment. With 0.4 kg/m3 of ammonia, 2.5h treatment and 0.5h ammonia cycle under vacuum condition, the formaldehyde emission could decrease significantly in the term of efficiency, energy and cost.The cost of ammonia treatment was 15yuan per cubic meters, while the cost of E1 urea-formaldehyde resin is 42yuan much more than E2 urea-formaldehyde resin; if we use formaldehyde scavenger, the cost will increase about 30yuan per cubic meters, so ammonia treatment has a great cost advantage.