Patent ID: 8664416

Claim:
A process for the production of methyl esters of fatty acids and high purity glycerine, employing at least one transesterification reaction between a vegetable or animal oil and methanol, in the presence of a solid heterogeneous catalyst, comprising in succession: at least one transesterification step during which the vegetable or animal oil is mixed with an excess of methanol in a reactor containing a fixed bed of catalyst; at least one step for expansion of the effluent from the reactor, followed by a step for separation, at the end of which a phase which is rich in methanol and a phase which is depleted in methanol are obtained; at least one step for concentration of the methanol contained in the rich phase; at least one step for decanting the methanol-depleted phase to separate the glycerine from the upper phase which is rich in methyl esters; said process being characterized in that said step for expansion and separation of methanol is staged and is carried out in at least two phases: a) a first phase for expansion of the effluent obtained at the reactor outlet, carried out at a pressure of at least 0.5 MPa, in order to obtain a first fraction of methanol vapour and a liquid fraction containing non-evaporated methanol, methyl esters, glycerol and partially converted triglycerides, said first phase for expansion and separation being followed by a step for condensation of said methanol vapour fraction into a fraction of methanol which is liquid at a temperature of at least 111° C., releasing a quantity of energy Q, the liquid methanol fraction obtained being sent directly to a recycle knockout drum, said quantity Q being used to heat at least one of the process streams; b) a second phase for expansion, at a pressure which is lower than that of step a) of the liquid fraction containing non-evaporated methanol, methyl esters, glycerol and partially converted triglycerides, in order to obtain a second fraction of methanol vapour, at least a portion of said second fraction being sent to the recycle knockout drum after having undergone a condensation step, the other portion of said second fraction being sent to the methanol concentration step.