Optimization of inhibition conditions of tetrahydrofuran hydrate formation via the fractional factorial design methodology

In the present study, 24−1 fractional factorial design has been used to optimize the inhibition conditions of tetrahydrofuran (THF) hydrate formation in the presence of acetone and l-leucine. The variables, l-leucine concentration (wt%), acetone content (v/v%), operating temperature and stirrer speed of reactor have been selected as the independent variables. This method has been designed to obtain significant effects on two responses variables, delay time and equilibrium temperature of THF hydrate formation, and 8 experimental runs have been carried out with two replications and four central points. The ANOVA results show that at the 95% confidence level the operating temperature and l-leucine concentration significantly affect the delay time and equilibrium temperature of hydrate formation, respectively. A first-order polynomial equation is developed to relate the responses and operational variables. The fitted model shows a good agreement between predicted and actual responses (R2 = 0.814 and 0.823; mean deviation = ±3 and ±1%). The optimal process conditions were: l-leucine concentration of 1 wt%, acetone of 7.5 v/v% and operating temperature of −5 °C for both responses and stirrer speed of reactor of 5 rpm for response 1 and 7 rpm for response 2.