Slurry reactors for gas-to-liquid processes: A review

With the dramatic increase in the international oil price, gas-to-liquid processes of Fischer-Tropsch (FT) synthesis, methanol synthesis, and dimethyl ether (DME) synthesis have become increasingly important and received much attention from both academic and industrial interests. The slurry reactor has the advantages of simple construction, excellent heat transfer performance, online catalyst addition and withdrawal, and a reasonable interphase mass transfer rate with low energy input, which make it very suitable for gas-to-liquid processes. However, its multiphase flow behaviors are very complex and the multiphase reactor has some remarkable scale-up effects; therefore, extensive studies are still needed for the development and design of a high-performance slurry reactor. This article gives a state-of-the-art review of the recent studies on the slurry reactor for gas-to-liquid processes. The influences of the superficial gas velocity, operating pressure and temperature, solid concentration, column dimensions, and gas distributor are discussed. Some recent developments in the liquid-solid separation in a slurry reactor are also summarized. The concept of using internals to intensify the mass transfer and improve the hydrodynamics is discussed based on both experimental results and theoretical analysis. Modeling and simulations of the gas-liquid and gas-liquid-solid flows are briefly reviewed, with focus on the new trend of coupling the population balance model (PBM) into the computational fluid dynamics (CFD) framework to describe the complex bubble behaviors and gas-liquid interphase interactions. The results of a 3000 ton/year pilot plant for DME synthesis are given, showing that the slurry reactor has promising applications in gas-to-liquid processes.