Modelling of an entrained flow coal gasifier. 2. Effect of operating conditions on reactor performance

Product separation and regeneration of sorbent was accomplished in a novel pressure swing reactor through pressurisation, adsorption, blowdown and purge steps. The switching from sorption to reaction to regeneration was tested in a two bed sorption/reaction apparatus. Models developed for the mass and momentum transfer in the catalyst bed and sorber, were solved using orthogonal collocation within the method of lines. The effects of operating conditions and cycle configurations on performance were assessed. The results from dynamic experiments with propene metathesis to produce ethene and 2-butene in a fixed-bed catalytic reactor were in agreement with model predictions. Both pressure and vacuum swing demonstrated that conversion and product quality can be enhanced by periodic cycling with greater separation obtained with vacuum swing. The separation of products help reduce the downstream processing costs of exit mixtures, enable reactant utilisation by recycling and improve product handling at subsequent stages. The efficacy of the periodic separating reactor in terms of conversion, product purity and recovery were investigated.

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Heat Transfer Modeling in a Counter-Current Moving-Bed Tubular Reactor for High-Temperature Thermochemical Energy Storage

ASME 2021 15th International Conference on Energy Sustainability ◽

10.1115/es2021-63490 ◽

2021 ◽

Author(s):

Wei Huang ◽

Eric Million ◽

Kelvin Randhir ◽

Joerg Petrasch ◽

James Klausner ◽

...

Keyword(s):

Heat Transfer ◽

High Temperature ◽

Tubular Reactor ◽

Operating Conditions ◽

Transfer Model ◽

Reactor Performance ◽

Low Oxygen ◽

Moving Bed ◽

Oxidation Reactor ◽

Counter Current

Abstract An axisymmetric model coupling counter-current gas-solid flow, heat transfer, and thermochemical redox reactions in a moving-bed tubular reactor was developed. The counter-current flow enhances convective heat transfer and a low oxygen partial pressure environment is maintained for thermal reduction within the reaction zone by using oxygen depleted inlet gas. A similar concept can be used for the oxidation reactor which releases high-temperature heat that can be used for power generation or as process heat. The heat transfer model was validated with published results for packed bed reactors. After validation, the model was applied to simulate the moving-bed reactor performance, through which the effects of the main geometric parameters and operating conditions were studied to provide guidance for lab-scale reactor fabrication and testing.

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Investigation of the Coal Gasification Process Under Various Operating Conditions Inside a Two-Stage Entrained Flow Gasifier

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4005603 ◽

2012 ◽

Vol 4 (2) ◽

Cited By ~ 10

Author(s):

Armin Silaen ◽

Ting Wang

Keyword(s):

Coal Gasification ◽

Operating Conditions ◽

Coal Slurry ◽

Two Stage ◽

Heating Value ◽

Fuel Distribution ◽

Entrained Flow ◽

One Stage ◽

Gasification Process ◽

Entrained Flow Gasifier

Numerical simulations of the coal gasification process inside a generic 2-stage entrained-flow gasifier fed with Indonesian coal at approximately 2000 metric ton/day are carried out. The 3D Navier–Stokes equations and eight species transport equations are solved with three heterogeneous global reactions, three homogeneous reactions, and two-step thermal cracking equation of volatiles. The chemical percolation devolatilization (CPD) model is used for the devolatilization process. This study is conducted to investigate the effects of different operation parameters on the gasification process including coal mixture (dry versus slurry), oxidant (oxygen-blown versus air-blown), and different coal distribution between two stages. In the two-stage coal-slurry feed operation, the dominant reactions are intense char combustion in the first stage and enhanced gasification reactions in the second stage. The gas temperature in the first stage for the dry-fed case is about 800 K higher than the slurry-fed case. This calls for attention of additional refractory maintenance in the dry-fed case. One-stage operation yields higher H2, CO and CH4 combined than if a two-stage operation is used, but with a lower syngas heating value. The higher heating value (HHV) of syngas for the one-stage operation is 7.68 MJ/kg, compared with 8.24 MJ/kg for two-stage operation with 75%–25% fuel distribution and 9.03 MJ/kg for two-stage operation with 50%–50% fuel distribution. Carbon conversion efficiency of the air-blown case is 77.3%, which is much lower than that of the oxygen-blown case (99.4%). The syngas heating value for the air-blown case is 4.40 MJ/kg, which is almost half of the heating value of the oxygen-blown case (8.24 MJ/kg).

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Evaluation of active sludge and aquatic ferns usage for removal of zinc in a biological wastewater treatment system

SIMI 2019, Abstract Book - International Symposium "The Environmental and The Industry" ◽

10.21698/simi.2019.fp04 ◽

2019 ◽

pp. 39-44

Author(s):

Amir Hajiali ◽

Lacramioara Diana Robescu

Keyword(s):

Ph Value ◽

Reaction Times ◽

Treatment Method ◽

Operating Conditions ◽

Industrial Scale ◽

Reactor Performance ◽

Solution Ph ◽

Active Sludge ◽

Simple Method ◽

Aquatic Fern

In this research capability of biological treatment method via active sludge and aquatic fern evaluated in different operating conditions and they were optimized in order to remove Zn (II). A simple reactor performance for treatment of model and real wastewater on laboratory and semi-industrial scale was investigated. This refining process proceeded with special attention to the effect of solution pH-value, pollutant concentration, absorbent concentration and reaction time. The batch semi-industrial scale reactor represented over 90 % removal efficiency under pH-value of 6 and 5-5.5 for aquatic ferns and active sludge, respectively. Effective reaction times represented various durations for aquatic ferns and active sludge with respect of 120 minutes and 90 minutes. The two biological masses had the best performances with 6 g/l for aquatic ferns and 5 g/l for active sludge. In the presence of 5 ppm of Zn (II) as the objective heavy metal, both absorbents had over 93.2 % removal efficiencies. While obviously laboratory-scale attempts introduced higher acceptable reduction efficiencies via this economic applicable treatment method. Additionally, economic considerations clarified feasibility of this recommended simple method.

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Investigation of chemical composition and morphology of ash deposition in syngas cooler of an industrialized two-stage entrained-flow coal gasifier

Energy ◽

10.1016/j.energy.2020.116901 ◽

2020 ◽

Vol 194 ◽

pp. 116901 ◽

Cited By ~ 4

Author(s):

Guangyu Li ◽

Shisen Xu ◽

Xuebin Zhao ◽

Ruijin Sun ◽

Chang’an Wang ◽

...

Keyword(s):

Chemical Composition ◽

Ash Deposition ◽

Two Stage ◽

Entrained Flow ◽

Coal Gasifier

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UV disinfection of water: the need for UV reactor validation

Water Science & Technology Water Supply ◽

10.2166/ws.2003.0075 ◽

2003 ◽

Vol 3 (4) ◽

pp. 293-300 ◽

Cited By ~ 8

Author(s):

Y.A. Lawryshyn ◽

B. Cairns

Keyword(s):

Legionella Pneumophila ◽

Uv Light ◽

Numerical Models ◽

Operating Conditions ◽

Analytical Models ◽

Human Consumption ◽

Average Dose ◽

Reactor Performance ◽

Uv Reactor ◽

Bioassay Data

Disinfection by ultraviolet light (UV) has received wide endorsement as an important contribution to the multiple barrier approach for protection of public health. UV can be used both to disinfect wastewater discharged to the environment, and to disinfect that water when it is picked up again for human consumption. UV readily blocks infectivity by such chlorine-resistant pathogens as Cryptosporidium parvum, Giardia lamblia and Legionella pneumophila. Multiple disinfectant use is now being discussed to broaden the spectrum of pathogens that can be inactivated by using disinfectants in their most strategically advantageous dose and function. Optimizing multiple barrier strategies requires attention to validation of the concepts and technologies involved. UV technology validation ensures that the equipment can deliver the target UV design dose, and that the monitoring/control technology modulates the dose appropriately with changes in water quality or operating conditions. The bioassay approach for UV reactor validation is recommended over analytical and numerical models. Analytical models, which provide an average dose estimate, have been shown to be inadequate. Numerical models, which utilize Computational Fluid Dynamics (CFD) and UV light intensity models to predict reactor performance, can be accurate when used by skilled professionals but require significant validation and/or calibration against bioassay data.

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Optimization modelling of anaerobic biofilm reactors

Water Science & Technology ◽

10.2166/wst.1994.0634 ◽

1994 ◽

Vol 30 (12) ◽

pp. 347-355 ◽

Cited By ~ 6

Author(s):

Makram T. Suidan ◽

Joseph R. V. Flora ◽

Pratim Biswas ◽

Gregory D. Sayles

Keyword(s):

Ionic Species ◽

Gas Production ◽

Biofilm Reactor ◽

Operating Conditions ◽

Reactor Performance ◽

Monod Kinetics ◽

Ph Changes ◽

Biofilm Model ◽

Steady State Model ◽

Completely Stirred Tank Reactor

A rigorous steady state model of acetate-utilizing methanogenic biofilms is developed accounting for the mass transfer of neutral and ionic species, pH changes within the biofilm, pH-dependent Monod kinetics, chemical equilibrium, electroneutrality, gas production within the biofilm, and the presence of a concentration boundary layer (CBL). In contrast to traditional biofilm models where the pH is assumed to be constant within the biofilm, an increase in pH in acetate-utilizing methanogenic biofilms is predicted. Furthermore, significant differences can exist between the flux predictions using the traditional models and when pH changes within the biofilm are taken into account. The optimum pH for acetate-utilizing biofilms is less than the optimum defined for suspended-growth systems. The biofilm model is coupled to a model of a completely-stirred tank reactor (CSTR), and strategies for the optimization of biofilm reactor performance are examined. For a fixed set of operating conditions, an optimum influent pH can be defined that corresponds to the maximum removal efficiency and flux of acetate into the biofilm.

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