Ammonia plants typically use high volumes of water, predominantly as make-up for process steam use and as cooling water. Water use minimimtion in the ammonia and fertilizer industries presents unique
challenges related to the potential for ammonia contamination. This can lead to concerns with water or air discharge of ammonia, increased microbiological activity, and concern for ammonia-enhanced corrosion. Copperbased metallurgy is understandably rare in ammonia plants, consequently the last concern is of little practical importance. Developing an advanced water resource management strategy for the ammonia and fertilizer industries requires a plant audit with a complete water and contaminant mass balance. Analysis of this information allows
development of potential conceptual design flowsheets, incorporating options for reduced water use. Attractive options for water use minimkation in an ammonia plant often include the reuse of process condensates as makeup to the demineralization system or as make-up to the cooling water system. Modeling the water chemistry resulting from water reuse, as well as the effectiveness of any recommended treatment operations, allows for a technical and economic comparison of the options. Operations of particular interest to the ammonia industry include ammonia stripping across an open cooling tower and ammonia removal techniques such as air or steam stripping. This paper will outline the general approach to water resource management, and present case studies illustrating the effectiveness of this approach.
Keywords: ammonia, water reuse, water recycle, modeling, stripping