Multiphase CFD simulations have shown how to design reactors using Fischer-Tropsch chemistry. The new design uses large catalyst particles to eliminate large bubbles, has no cooling tube bundles and produces up to 50,000 bbl/day of Diesel fuel in a 7 m diameter, 12 m high reactor at a pressure of 3 MPa and a temperature of 530 K. (C) 2015 Elsevier Ltd. All rights reserved.