Karn Pana-Suppamassadu

Conversion enhancement of tubular fixed-bed reactor for Fischer-Tropsch synthesis using static mixer

Abstract Recently, Fischer-Tropsch synthesis (FTS) has become an interesting technology because of its potential role in producing biofuels via Biomass-to-Liquids (BTL) processes. In Fischer-Tropsch (FT) section, biomass-derived syngas, mainly composed of a mixture of carbon monoxide (CO) and hydrogen (H 2 ), is converted into various forms of hydrocarbon products over a catalyst at specified temperature and pressure. Fixed-bed reactors are typically used for these processes as conventional FT reactors. The fixed-bed or packed-bed type reactor has its drawbacks, which are heat transfer limitation, i.e. a hot spot problem involved highly exothermic characteristics of FT reaction, and mass transfer limitation due to the condensation of liquid hydrocarbon products occurred on catalyst surface. This work is initiated to develop a new chemical reactor design in which a better distribution of gaseous reactants and hydrocarbon products could be achieved, and led to higher throughput and conversion. The main goal of the research is the enhancement of a fixed-bed reactor, focusing on the application of Kenics™ static mixer insertion in the tubular packed-bed reactor. Two FTS experiments were carried out using two reactors i.e., with and without static mixer insertion within catalytic beds. The modeled syngas used was a mixed gas composed of H 2 /CO in 2: 1 molar ratio that was fed at the rate of 30 mL(STP)-min– 1 (GHSV ≈ 136 mL. g ca −1 .h −1 ) into the fixed Ru supported aluminum catalyst bed of weight 13.3 g. The reaction was carried out at 180 °C and atmospheric pressure continuously for 36 h for both experiments. Both transient and steady-state conversions (in terms of time on stream) were reported. The results revealed that the steady-state CO conversion for the case using the static mixer was approximately 3.5 times higher than that of the case without static mixer. In both cases, the values of chain growth probability of hydrocarbon products (α) for Fischer-Tropsch synthesis were 0.92 and 0.89 for the case with and without static mixer, respectively.

Effect of Reaction Conditions on the Catalytic Performance of Ruthenium Supported Alumina Catalyst for Fischer-Tropsch Synthesis

A Ru/ɤ-Al2O3 catalyst was prepared using by sol-gel technique in order to study its conversion and selectivity in the Fischer-Tropsch Synthesis (FTS). The effects of reaction conditions on the performance of a catalyst were carried out in a fixed bed reactor. The variation of the steady-state experiments were investigated under reaction temperature of 160-220˚C, inlet H2/CO molar feed ratio of 1/1-3/1, which both atmospheric pressure and gas space hour velocity of 1061 hr− 1 were restricted. The influence of changing factors on CO conversion and on the selectivity of the formation of different hydrocarbon products in the reaction conditions was performed and compared to assess optimum operating conditions. In terms of FTS results, the increase of reaction temperatures led to increase of CO conversion and light hydrocarbon, while higher H2/CO ratio has strongly influenced to increase the selectivity to higher molecular weight hydrocarbons and chain growth probability (α). Moreover, our catalyst was also markedly found to maintain selectivity to diesel faction for a wide range of H2/CO molar feed ratios from BTL application.

Syngas Production via Carbon Dioxide Reforming of Methane in a Wall-Coated Monolith Reactor

The production of syngas via carbon dioxide reforming or dry methane reforming (DMR) was studied in the present study. To reduce pressure drop and improve the performance, the reaction was carried out over a 10%Ni/Al2O3-MgO catalyst in a wall-coated monolith reactor at about 600 °C, atmospheric pressure. The monolith reactor comprised of 37 circular flow channels of 3-mm-diameter. The reactant gases i.e. CH4 and CO2 at stoichiometric molar ratio of 1:2 was fed into the reactor at the volumetric flow rate of 450, 600 and 750 mL/min corresponding to various gas space velocities (GSV) i.e. 0.57, 0.76, and 0.96 s-1, respectively. Under 24-hr continuous operations, the stability of system could be sustained and the deactivation by carbon deposition was not observed. The experimental results did show that the conversion of methane depended upon the GSV i.e. the %CH4 conversion were 50, 45 and 40% for the GSV of 0.57, 0.76, and 0.96 s-1, respectively. In addition, the %H2 yield, %H2 selectivity, %CO yield, %CO selectivity also depended on the feeding rate and so affected the performance of the wall-coated monolith reactor as a reformer.

Investigations of Hydrodynamics and Heat Transfers in a Modified Reactor Using Fluid Mixers

The performance of a packed-bed reactor typically used in Gas-to-Liquid (GTL) or Biomass-to-Liquid (BTL) technologies in producing liquid fuels was affected by unfavorable high pressure drop, flow and temperature maldistributions which in turn could cause severe catalyst deactivation, and result in inefficient reaction etc. A certain types of fluid mixers such as KenicsTM or Mixing & Stirring type static mixers had been suggested to improve the performance of this type of reactor. In order to design a proper modified reactor by mean of an installation of such mixing structures for the pilot plant in liquid fuel production via Fischer-Tropsch Synthesis (FTS) conducted at the RCC research center, this study had to characterize the hydrodynamics and heat transfers within a packed-bed modified by KenicsTM and Mixing & Stirring type static mixers. During the FTS, the syngas i.e. CO and H2 was fed through the bed of catalyst causing the temperature rise due to an exothermic enthalpy, and the flow and temperature distributions of mixed gas within the catalyst bed were influenced. The improved velocity and temperature distributions and heat transfers were exhibited by using such mixers e.g. rather uniform distributions and higher heat transfer coefficient. Thus, the better performance of the reactor could be expected.

Technical Feasibility of Small-Scale GTL Process towards Heat Integration: A Case Study of Nongtum A Reservoir in Thailand

Natural gas can be a raw material to produce synthetic liquid fuels via Gas to Liquid process (GTL). The process is consist of 4 main parts which are cleaning unit, reforming unit, Fischer-Tropsch unit (FT) and product upgrading unit. To evaluate potential of having this kind of process for Nongtum A Reservoir, Thailand, technical feasibility of GTL process towards heat integration needed to be done. This work presented a process model, combined heat and power (gas generation) of Nongtum A Reservoir by using the total heat integration concept. Volume of natural gas at Nongtum A Reservoir is 56,634 m3/day at 10 bar, and 40 deg.C. ResuIts of the model simulation are the overall thermal efficiency of 10.32% to 14.88%, gasoline product of 435 to 575 bbl/day, and diesel product of 621 to 947 bbl/day depending upon a split ratio of natural gas to gas generation.