(148b) Refinery Preheat Train Fouling Management for Enhanced Energy Efficiency

Heat exchanger fouling in modern refineries continues to be a major issue for both energy efficiency and environmental impact. Fouling is most acute in crude distillation units (CDUs). It reduces preheat temperatures, necessitating higher heater duties which incur increased fuel consumption. This in turn leads to increased fuel costs and higher emissions. It also can reduce throughput and lead to reliability and maintenance issues.

This paper describes a method for managing fouling to minimize its effect on cost, the environment, reliability and maintenance. The approach combines advanced process modelling and optimization techniques with the latest data visualization techniques in an Operational Excellence (OE) platform.

A key development is the use of equation-oriented process modelling tools to model network performance through time. By predicting future performance over an operating window, for example up to the next turnaround, overall costs and environmental impact can be calculated and informed decisions made. The approach results in heat exchanger networks which achieve a practical balance between thermal efficiency and operability, with all fouling effects presented to operators both as costs and environmental impact. An added advantage is that when implemented online the tool can immediately detect anomalies in operation that give rise to abnormal rates of fouling.

Another key feature of the approach is the visualization of results. The technology is deployed via various dashboards, depending on the user’s role. One dashboard is used by engineering teams to study ‘what-ifs’, another by operations staff to ensure day-to-day performance is optimal, and another by the maintenance department to plan maintenance schedules which tie in to cost and environmental objectives. Current plant data and operational status are displayed in real time.

A real-life case study is presented showing how the technology is used to predict the effects of temperature and flow on fouling, and also the effects of more significant process changes such as throughput increase, bypassing exchangers and the effects of removing heat exchangers. Associated cost and environmental benefits are presented.