Improving the Efficiency of Essential Oil Distillation via Recurrent Water and Steam Distillation: Application of a 500-L Prototype Distillation Machine and Different Raw Material Packing Grids

This research presents an essential oil (EO) distillation method with improved efficiency, called recurrent water and steam distillation (RWASD), as well as the testing of a 500 L prototype essential oil distillation machine (500 L PDM). The raw material used was 100 kg of lime fruit. At each distillation time point, the test result was compared with that obtained via water and steam distillation (WASD), and different raw material grid configurations were taken into consideration. It was found that distillation using the RWASD method increased the amount of EO obtained from limes by 53.69 ± 2.68% (or 43.21 ± 2.16 mL) compared with WASD. The results of gas chromatography mass spectrometry (GC-MS) analysis of bioactive compounds from the distilled EO revealed that important compounds were present in amounts close to the standards reported in many studies; namely, β-myrcene (2.72%), limonene (20.72%), α-phellandrene (1.27%), and terpinen-4-ol (3.04%). In addition, it was found that the temperature, state of saturated steam, and heat distribution during distillation were relatively constant. The results showed the design, construction, and heat loss error values of the 500 L PDM were 5.90 ± 0.29% and 7.83 ± 0.39%, respectively, leading to the use and percentage of useful heat energy to stabilize at 29,880 ± 1,494 kJ/s and 22.47 ± 1.12%, respectively. Additionally, the shape of the grid containing the raw material affects the temperature distribution and the amount of EO distilled, with values 10.14 ± 0.51% and 8.07 ± 0.40% higher for the normal grid (NS), respectively, as well as an exergy efficiency of 49.97 ± 2.49%. The highest values found for exergy in, exergy out, and exergy loss were 294.29 ± 14.71 kJ/s, 144.76 ± 7.23 kJ/s, and 150.22 ± 7.51 kJ/s, respectively. The obtained results can be further developed and expanded to promote the application of this method in SMEs, serving as basic information for the development of the EO distillation industry.