Fixed Bed Fischer-Tropsch Reactor Research Articles

Effect of mass transfer on the deactivation model and GPLE parameters of Co/γ-Al2O3 catalysts in the Fischer Tropsch synthesis

The activity of catalysts with various sizes was compared in a fixed-bed Fischer–Tropsch reactor under similar operating conditions by determining the deactivation model. Catalyst size had no impact on the type of deactivation model. The smaller catalyst showed a smaller deactivation constant of catalyst (kd) and a lower deactivation rate in the initial stage. The decline in the activities of the catalyst with a mesh size of 40 was lower than the other catalysts, suggesting its higher long-term stability (ass). Larger catalyst sizes led to the fouling of carbon and heavy hydrocarbons, decreasing the specific surface of the catalyst, thus increasing the pore diffusion resistance and further decrementing the catalyst activities.

Experimental and simulation study of the temperature distribution in a bench‐scale fixed bed Fischer–Tropsch reactor

AbstractThe temperature distribution in a bench‐scale fixed bed Fischer–Tropsch reactor using Co‐based catalyst was investigated under conditions of 2 MPa and 458 K at various syngas partial pressures and space velocities. The single‐tube reactor had a diameter of 0.05 m, which is representative of the diameters used in industrial applications. With a special designed temperature measurement, the detailed temperature distribution in a bench‐scale reactor was reported for the first time. The changes of maximum temperature in the bed and hot spot region were discussed at different N2 flow rate and gas hourly space velocity. A 2D pseudo‐homogeneous fixed bed reactor model was developed using ANSYS Fluent. A position‐dependent heat‐transfer coefficient, which considered more accurate in temperature prediction, was applied. The model was validated against both the reaction results and the measured temperatures. The inferred properties within the reactor were analyzed to give insight as to how to increase the reactor production capacity.

Fischer-Tropsch route for the conversion of biomass to liquid fuels - Technical and economic analysis

The techno-economics of biomass gasification systems for the production of Fischer-Tropsch (FT) based liquid fuels are analysed by estimating the overall mass and energy conversion of biomass to liquid (BTL) fuel. The investigation of BTL systems for 1000 kg/h biomass gasification system and an expected liquid hydrocarbon output of 1500 tonnes are estimated. The cost analysis, based on the annualized life cycle of the systems, includes a steam-oxygen based biomass gasification plant paired with the FT unit. The gasifier considered in this analysis is the downdraft reactor design, operating on oxygen-steam gasifying medium at an equivalence ratio of 0.1 and a steam-to-biomass ratio in the range of 0.8–1.2 to generate syngas with H2/CO ratio of 2.1:1, ideally suitable for the cobalt based fixed bed FT reactor. The mass and energy balance reveal that for a once-through FT reactor configuration, substantial energy exists in the gas phase, which includes C1-C5 hydrocarbons and unconverted syngas. The study suggests that the product gas be utilized in an IC engine and converted to electricity, for in-house power demands and for the sale of excess electricity to the grid. The analysis indicates a market competitive liquid fuel production with CO conversion greater than 60%, at a cost ranging from INR 35–40/litre (0.5–0.6 USD/litre) alongside electricity as a major co-product in the BTL system. This study examines the economics of building economically affordable and environmentally favourable BTL systems of smaller throughputs with particular reference to India.

Increasing ethylene production as a high value hydrocarbon in Fischer-Tropsch (FT) reactor: A concept reactor for combining FT with oxidative coupling of methane

The paper proposes a concept configuration of reactors for coupling OCM and FTS, and presents systematic simulation results. FTS section is a combination of fixed bed and membrane fluidized bed reactor, and feed of the FT reactor is supplied by OCM. The reactor configuration is compared with the consecutive reactors of OCM and one fixed bed FT reactor. Effects of CH4/O2 ratio, percent of N2 in the feed, contact time, and input temperature on the yield of ethylene and valuable hydrocarbons are studied. The results show that compared with one FTS reactor configuration, the dual FTS reactor configuration is more effective and thus gives much higher product yields. Furthermore, a main decrease is observed in the formation of CO2 and CH4.

Comparison of CFD results and experimental data in a fixed bed Fischer–Tropsch synthesis reactor

Hydrogenation of carbon monoxide in a fixed bed Fischer–Tropsch reactor has been simulated using computational fluid dynamics. The geometry of fixed bed reactor was modeled using the discrete packing method. The effects of reaction temperature, feed flow rate and H2/CO ratio on CO conversion and product selectivity were investigated. The mass fraction of products was also predicted by using the CFD model at different H2/CO ratios. It was observed that the CO conversion increased with increasing temperature, while decreased with increasing mass flow rate. The selectivity and mass fraction of products also increased with increasing temperature and H2/CO ratio.

Experimental studies and modeling of a fixed bed reactor for Fischer–Tropsch synthesis using biosyngas

The aim of this work was to study the Fischer–Tropsch (FT) synthesis of a model biosyngas (33% H2, 17% CO and 50% N2) in a single tube fixed-bed FT reactor. The FT reactor consisted of a shell and tube with high-pressure boiling water circulating throughout the shell. A spherical unpromoted cobalt catalyst was used with the following reaction conditions: a wall temperature of 473K, a pressure of 20bars and a gas hour space velocity (GHSV) of 37 to 180NmL.gcat−1.h−1. The performance of the FT reactor was also validated by developing a 2D pseudo-homogeneous model that includes transport equations and reaction rate equations. Good agreement between the model predictions and experimental results were obtained. This developed model was extended to predict and quantify the influence of the FT kinetics as well as determine the influence of the tube diameter and the wall temperature. The predicted behaviors for CO and H2 conversion, productivity of hydrocarbons (mainly CH4 and C5+) and fluid temperature along the axis of the reactor have been analyzed.

Fischer–Tropsch catalyst testing in a continuous bench-scale coal gasification system

A bench-scale oxygen-blown fluid-bed gasifier was coupled to a modular fixed-bed Fischer–Tropsch (FT) reactor system for testing an FT catalyst under syngas. Various blends of subbituminous coal, torrefied biomass, and untreated biomass were gasified at 22 bar absolute, 800°–860 °C, and 4 kg/h. Syngas exiting the fluid bed passed through a cyclone, candle filter, and sulfur sorbent to reduce fine particulate and H 2S to levels well below 1 ppmv. The syngas was cooled to condense out moisture and volatiles and then reheated to temperatures required for FT synthesis. The clean syngas then flowed into the FT reactor with a 5:1 ratio of recycled FT product gas-to-fresh syngas feed. A 70% overall conversion of CO and H 2 was achieved at 269 °C and 18.9 bar over an iron-based catalyst supported on gamma-alumina pellets.