Validation of the method for determination of the thermal resistance of fouling in shell and tube heat exchangers

• Heat recovery in a heat exchanger network (HEN).
• A novel method for on-line determination of the thermal resistance of fouling is presented.
• Details are developed for shell and tube heat exchangers.
• The method was validated and sensibility analysis was carried out.
• Developed approach allows long-term monitoring of changes in the HEN efficiency.

A novel method for on-line determination of the thermal resistance of fouling in shell and tube heat exchangers is presented. It can be applied under the condition that the data on pressure, temperature, mass flowrate and thermophysical properties of both heat-exchanging media are continuously available. The calculation algorithm for use in the novel method is robust and ensures reliable determination of the thermal resistance of fouling even if the operating parameters fluctuate. The method was validated using measurement data retrieved from the operation records of a heat exchanger network connected with a crude distillation unit rated 800 t/h. Sensibility analysis of the method was carried out and the calculated values of the thermal resistance of fouling were critically reviewed considering the results of qualitative evaluation of fouling layers in the exchangers inspected during plant overhaul.