NOVELTY - Production (M1) of biodiesel from transesterification reaction of alcohol and triglycerides in multi-zone tubular reactor involves allowing fluid reaction mixture to flow through multi-zone tubular reactor having three zones along its axis. The alkyl esters and glycerin are formed from alcohol and triglycerides in reaction mixture as the reaction mixture flows through zones which comprise entrance, exit, and intermediate zone between entrance and exit zones, where flow of reaction mixture in intermediate zone is turbulent and flow changes to transitional or laminar in exit zone.    USE - For production of biodiesel from transesterification reaction of alcohol and triglycerides in multi-zone tubular reactor (claimed).    ADVANTAGE - The methods improves conversion of process feedstocks and yield of alkyl ester products, performance and efficiency in reactor and decanter systems, coalescing and decanting of biodiesel reaction products.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) multi-zone tubular reactor (R1) for production of biodiesel from alcohol and triglycerides from transesterification reaction, the reactor comprising tubular section adapted to allow flow of reaction mixture from entrance to exit of the section, where the tubular section comprises at least three zones along its axis, where the zones comprise entrance zone, exit zone, and intermediate zone between the entrance and exit zones, where at least one static mixer is positioned in the entrance zone, intermediate zone, or both for increasing the homogeneity of reaction mixture whose physical properties change as it flows throughout the zones; and    (2) separating (M2) biodiesel phase from glycerin phase of fluid mixture from transesterification reactor involving allowing liquid mixture from transesterification reactor to flow through coalescer to increase droplet size of dispersed glycerin phase in alkyl ester phase; and allowing the liquid mixture from the coalescer to flow through decanter to provide phase separation of the alkyl phase from the glycerin phase, where transesterification reaction generates alkyl ester as the liquid mixture flows through the coalescer and the decanter.