Analysis and debottlenecking of process utilities for an industrial manufacturing site

Chemical plants may undergo significant modifications during their operational life, such as revamping and debottlenecking projects. As a result, the original design of the utility infrastructure may prove ineffective to meet the evolving requirements of the plant. This work considers a case study of an industrial chemical plant, which is now planning further expansion. The expected consumption of process utilities is estimated based on the current demand and the predicted increase in consumption due to the programmed expansion. The study focuses on the nitrogen and cooling water plants, which are identified as the utilities requiring modifications in order to meet future needs. With concern to the nitrogen plant, the proposed expansion of the production capacity is achieved by replacing one of the two production units with a new module providing higher production capacity. As regards the cooling water plant, first the installation of an additional water lift pump in the hot water basin is recommended to avoid circuit imbalances during utility peaks of demand; then, the revamping of the larger cooling tower module is proposed to both improve the cooling performance and increase the treated water flow rate; finally, the addition of a new cooling tower is suggested. The profitability analysis performed on the nitrogen expansion project highlights that the Net Present Value after 15 years is equal to 2.61 M€, while the internal rate of return is 33.5%, suggesting that the savings largely exceed the initial capital investment. As regards the interventions proposed on the cooling water plant, the estimated cost for revamping the current system and installing a new cooling tower is about 85000 €.