In recent years many environmental regulations have been amended by the regulatory bodies. This has led to a significant reductions in the permissible emission levels for ammonia and urea dust for new urea fluid-bed granulation plants. Existing plant operators are also faced with the demands from their environmental authorities to reduce their emissions to the environment as well.
While the reduction of dust emissions can be achieved by using scrubbing systems with a higher separation efficiency, reducing ammonia emissions in a urea granulation plant is more complicated. In principle significant ammonia reductions can be achieved by installing acidic scrubbing systems well known in the fertilizer industry.
In NPK or AN plants the resulting bleed stream from the acidic scrubber can be reintroduced into the process without any difficulty, as in these plants the bleed contains components which are already present in the plant and the product. For a urea fluid-bed granulation plant the situation is more complicated. In this case the bleed from the acidic scrubber contains components which cannot be processed in a standard urea synthesis and evaporation plant and which until now are usually not part of the product specification.
The bleed from the ammonia scrubber must be processed in some way. This processing can be done in various ways. In accordance with UFT's commitment to improve the fluid-bed granulation process UFT has developed options for achieving ammonia emission reductions from fluid-bed urea granulation plants. With UFT's Ammonia Convert Technology the acidic bleed from the ammonia scrubber has been successful integrated into the granulation process. In this paper various available and industrially proven options for granulation plant operators are presented. In especially UFT´s proprietary Ammonia Convert Technology, which combines minimized ammonia emissions with reduced production cost will be discussed.