Biodiesel synthesis

An apparatus for reacting a natural oil with a short chain alcohol in the presence of alkaline catalyst, comprising a pipe reactor that has a diameter in the range of 2 to 200 mm and a length in the range of 30 to 100 meters, a feed of natural oil, a feed of short chain alcohol and a feed of alkaline catalyst, the feed being arranged to feed reactants in one direction along the pipe reactor, static mixing elements being provided in the pipe reactor so that the reactants are fed in transitional or turbulent conditions, wherein static mixing elements are present for at least a first 20% of the length of the pipe reactor and for at least a last 30% of the length of the pipe reactor, and there is a portion of the pipe reactor that comprises at least 20% of the length of the pipe reactor and is displaced from the ends thereof which has no mixer elements, so that reactants are mixed in a direction normal to the flow direction to a greater degree than in a direction parallel to the flow direction.

A method of reacting a natural oil with a short chain alcohol in the presence of alkaline catalyst, in which a mixture of reactants comprising natural oil, short chain alcohol and alkaline catalyst is fed in one direction along a pipe reactor under transitional or turbulent conditions, the pipe reactor having a diameter in the range of 2-200 mm and a length in the range of 30 to 100 meters, and including static mixing elements that are present for at least a first 20% of the length of the pipe reactor and for at least a last 30% of the length of the pipe reactor, and wherein a portion of the pipe reactor that comprises at least 20% of the length of the pipe reactor and is displaced from the ends thereof has no mixer elements, so that the reactants are mixed in a direction normal to the flow direction such that the time taken for 90% of the elements of fluid to pass through the reactor is within 20% of the mean residence time of reactant in the reactor.

An apparatus for reacting a natural oil with a short chain alcohol in the presence of alkaline catalyst, comprising a pipe reactor that has a diameter in the range of 2-200 mm and a length in the range of 30 to 100 meters, a feed of natural oil, a feed of short chain alcohol and a feed of alkaline catalyst, the feed being arranged to feed reactants in one direction along the pipe reactor, static mixing elements being provided in the pipe reactor so that the reactants are fed in transitional or turbulent conditions, wherein static mixing elements are present for at least a first 20% of the length of the pipe reactor and for at least a last 30% of the length of the pipe reactor, and there is a portion of the pipe reactor that comprises at least 20% of the length of the pipe reactor and is displaced from the ends thereof which has no mixer elements, so that the reactants are mixed in a direction normal to the flow direction such the time taken for 90% of the elements of fluid to pass through the reactor is within 20% of the mean residence time of reactant in the reactor.