Kulchanat Prasertsit

Feasibility Study of Reactive Distillation Column for Transesterification of Palm Oils

The production of biodiesel by transesterification in existing processes requires excess alcohol, typically 100%, over its stoichiometric requirement in order to drive the chemical reaction to complete. This excess alcohol must be recovered and purified for reusing by rectification and distillation, which involves additional capital and operating costs. Therefore, combination of reactor and distillation column in only one unit called reactive distillation column (RD) may lead to an enormous capital-investment cost reduction. This research is proposed the feasibility study of biodiesel production from palm oil by transesterification using reactive distillation. The hypothesis is to reduce the amount of alcohol in the feed stream closing to its stoichiometric ratio with oil. This dues to the less energy used in the methanol recovery for the processes. The effects of process parameters were conducted by lab scale RD packed column. The results indicated that process parameters of 900 ml/hr flow rate, reboiler temperature 90C with 4.0:1 molar ratio of methanol to oil and residence time of 5 minutes in the column produced 92.75 percent biodiesel purity.

Transesterification of Triolein with Methanol in Reactive Distillation Column: Simulation Studies

Biodiesel is one of the most famous alternative petroleum diesel fuels. It is a clean fuel that causes less pollution than petroleum diesel does. To produce biodiesel by the conventional process, a biodiesel plant requires at least a reactor and a distillation column. Therefore, this work focuses on a feasibility study of using reactive distillation (RD), the combination of a reactor with a distillation column in one unit, to produce biodiesel from palm oil. The hypothesis of using RD is to reduce the amount of excess alcohol in the feed stream bringing its stoichiometric ratio close to that of oil. That causes less energy to be required for the methanol recovery process. Aspen Plus 2006 has been used to simulate this process. The kinetic constants of the conventional process need to be modified for the RD process. The preliminary results show a 4:1 molar ratio of methanol to oil, and the reboiler temperature at 150°C produces a 97.36 %(wt) methyl ester in 5.6 minutes. It can be concluded that using the RD process is more efficient and more feasible than using the conventional process to produce biodiesel from palm oil.

The Inhibiting Behavior of Glycerol on the Kinetics of Transesterification of Palm Oil

Glycerol, a by-product from transesterification, is well-known as one of the factors inhibiting the reaction. Previous works have mostly shown that the reaction rate slows to a near-steady state and eventually reaches chemical equilibrium. This work aimed to study the inhibiting behavior of glycerol on the transesterification of palm oil. Observation under an LCD digital microscopy showed that glycerol-coated droplets of catalyst-methanol dispersed in the triglyceride phase. This work proposes that glycerol inhibits transesterification by the following mechanism: Droplets of catalyst-methanol disperse into the triglyceride phase; the reaction takes place at an interphase called the reactive zone; methyl ester, the desired product, has low polarity and moves to the triglyceride phase, whereas glycerol, the non-desired product, is more highly polar and accumulates on the droplet surface of catalyst-methanol droplets, inhibiting triglyceride mass transfer and diluting the concentration of the catalyst-methanol. The triglyceride mass transfer coefficient and reaction rate constant were both investigated and expressed as the exponential function.

Comparing Usage of Temperature Control and Composition Control for Reactive Distillation Column in Methyl Ester Production

The temperature control and the composition control for the production process was used to evaluated a method to control the quality of methyl ester production in a reactive distillation column. The optimum condition at steady state was selected as the base case condition for the control study by using Aspen Dynamic Simulation. In this work, two controller settings for PID controller of each control loop were based on the Zeigler-Nichol and the Tyreus-Luyben tuning formulae. The controllability and performance of both control structures were compared. The result shows that the control loop using the Ziegler-Nichols setting gave better control performance than the other using the Tyreus-Luyben setting. It also found that the control structure based on temperature control gives the same control performance as the other based on composition control, but less expensive and less complicated to implement.