How Green is the Stamicarbon Urea Process?

摘要

The Stamicarbon urea process, like other processes, unfortunately emits gaseous (ammonia) emissions due to the fact that the urea reaction is an equilibrium reaction. In principle, emission problems can be solved in two different ways, either with an in–line and/or with an end-of-pipe solution. The combination of the equilibrium reaction and the presence of inerts make an in-line solution not feasible. Therefore end-of-pipe solutions to eliminate ammonia emissions in both urea melt and finishing plants are still needed to obtain a green and environmentally sustainable process. This paper covers the different available end-of-pipe solutions such as absorbers (including emergency absorber), acidic scrubbers and flares. These options have a wide range of operating windows for further optimization and achieving optimum environmental performance. Flaring reduces the ammonia emission by converting the ammonia into carbon dioxide and nitrogen oxides (NOx). Therefore, the environmental impact evaluation - after implementation of the new end-of-pipe solution - needs to be reviewed, especially when applying continuous emission flare because the environmental impact of these new type emissions are not more tolerable than ammonia emission. Stamicarbon believes that a green urea process combines optimum process conditions with a good choice of end-of-pipe solutions. The available alternatives for end-of-pipe solutions target an optimum “Triple P” balance, i.e. the balancing between financial-economical achievements (profit), environmental impact (planet) and public acceptance (people).