Base case process development for energy efficiency improvement, application to a Kraft pulping mill. Part II: Benchmarking analysis

A new procedure for benchmarking analysis has been developed to evaluate the energy efficiency of a chemical process. Benchmarking is performed to identify process inefficiencies before developing energy enhancement measures. The new procedure combines typical techniques, such as the comparison with current practice, with utilization of new performance indicators based on exergy and energy content and the targeting by Pinch Analysis and Water Pinch. All process sections and the steam and water utility systems are evaluated. The procedure consists of five phases. In the first phase the data required is compiled. The second phase consists of comparing the energy and water efficiency of the base case to the current practice of the industry. In the third phase, the new energy and exergy content indicators are used to analyze the efficiency of utilities systems and to quantify the heat rejected by the process. In the fourth phase the minimum energy and water requirements are determined. The last phase is a synthesis by which the inefficiencies are identified and guidelines established for process improvement. Interactions between the utilities systems and the process are developed. The procedure has been applied to an operating Kraft pulping mill in Eastern Canada.

Research highlights▶ Systematic procedure for benchmarking the energy efficiency of chemical processes. ▶ Utilization of exergy and energy content indicators and targeting by Pinch Analysis ▶ Interactions between the utilities systems and process units can be identified. ▶ Targeting sets the limits of the potential energy efficiency enhancements. ▶ Utilization of exergy analysis strengthens the grasp of existing energy inefficiencies.