Simple Equation for Suitability of Heat Pump Use in Distillation

• Published in: Computer Aided Chemical Engineering Vol. 33; pp. 1327 - 1332
• Main Authors: Pleşu, Valentin, Bonet Ruiz, Alexandra E., Bonet, Jordi, Llorens, Joan
• Format: Book Chapter
• Language: English
• Published: 2014
• Subjects: Carnot efficiency; energy savings; heat pump assisted distillation (HPDA); heat pump assisted distillation (HPDA); energy savings; Carnot efficiency
• ISBN: 9780444634344; 0444634347
• ISSN: 1570-7946
• DOI: 10.1016/B978-0-444-63455-9.50056-8

A distillation column can be considered as a heat engine that produces separation instead of work. The heat is provided in the reboiler and collected degraded at a lower temperature at the condenser. The energy collected at low temperature at the top of the column can be upgraded back to higher temperatures by means of a heat pump and reused to heat a lower column stage.This can bring saving in terms of the overall amount of energy required. However, the energy required to increase the pressure is of higher quality and price than hot services. The aim of the present paper is to provide an easy way to check, in the early stages of design, when the use of a heat pump can provide a more sustainable distillation process decreasing its energy requirements. After several simplifications, it can be stated that it depends mainly on the efficiency of Carnot. When the efficiency of Carnot is evaluated for the industrial systems where the heat pumps are used, it is concluded that all have Carnot efficiency around 0.1 or lower. Therefore, in the early design of a new distillation column, this criterion is useful to decide when a heat pump is worth to be included in the more rigorous simulations.