Heat Integration using Pinch Analysis of Ammonia Plant

Abstract

Around 80% of ammonia produced is being used for the manufacturing of urea-based fertilizers, however its production requires extensive amount of energy. Retrofitting of an existing ammonia plant for improving energy efficiency is done by using Pinch Analysis. This method relates the core process with the utility system to reduce the energy consumption and heat waste of the plant. The technique is applied on the convective section of the primary reformer by changing the arrangement of heating coils and by doing this significant waste heat was recovered from the flue gases. Otherwise, this heat would have lost in atmosphere. The analysis was performed using Aspen Energy Analyser. The problem came out be threshold problem i.e. the system requires only one utility (cold utility) to meet the desired temperatures of different streams. Using thermodynamics principles, pinch rules and limitation imposed by the current plant design, new modifications are suggested to improve the plant efficiency. As a result of these suggestions, around 7% more high pressure steam can be generated with only slight modifications.