scholarly journals A Modified Gibbs Free Energy Minimisation Model for Fluid Bed Coal Gasification

2015 ◽  
Vol 36 (1) ◽  
pp. 73-87 ◽  
Author(s):  
Marek Ściążko ◽  
Leszek Stępień
Keyword(s):  
Large Scale ◽  
Coal Gasification ◽  
Heterogeneous Reactions ◽  
Boudouard Reaction ◽  
Quasi Equilibrium ◽  
Gaseous Species ◽  
Gasification Process ◽  
Energy Minimisation ◽  
Inorganic Matter ◽  
Fluid Bed

Abstract A modified approach to equilibrium modelling of coal gasification is presented, based on global thermodynamic analysis of both homogeneous and heterogeneous reactions occurring during a gasification process conducted in a circulating fluid bed reactor. The model is based on large-scale experiments (ca. 200 kg/h) with air used as a gasification agent and introduces empirical modifications governing the quasi-equilibrium state of two reactions: water-gas shift and Boudouard reaction. The model predicts the formation of the eight key gaseous species: CO, CO2, H2O, H2, H2S, N2, COS and CH4, volatile hydrocarbons represented by propane and benzene, tar represented by naphthalene, and char containing the five elements C, H, O, N, S and inorganic matter.

Characteristics of "Three Zones" during Underground Coal Gasification

2012 ◽  
Vol 524-527 ◽  
pp. 56-62 ◽  
Author(s):  
Hong Tao Liu ◽  
Hong Yao ◽  
Kai Yao ◽  
Feng Chen ◽  
Guang Qian Luo
Keyword(s):  
Large Scale ◽  
Coal Gasification ◽  
Basic Knowledge ◽  
Gas Composition ◽  
Underground Coal Gasification ◽  
Reduction Zone ◽  
Gasification Process ◽  
Product Gas ◽  
Dry Distillation ◽  
Major Chemical

According to the temperature, major chemical reactions and gas compositions, the gasification process along the tunnel of underground coal gasification is divided into three zones, i.e. oxidation zone, reduction zone and dry distillation zone. A model test in the laboratory was carried out by using large-scale coal blocks to simulate the coal seam. The characteristics of the “three zones”, and the relation between the temperature and gas composition were also quantitative studied. It provided the necessary basic knowledge for further studying the process of underground coal gasification, including predicting compositions of product gas, life-cycle analyzing, selecting optimistic control parameters and determining suitable gasification craft.

Coal Gasification Characteristics in a 2MWth Second-Generation PFB Gasifier

2005 ◽  
Author(s):  
Xiao Rui ◽  
Baosheng Jin ◽  
Yunquan Xiong ◽  
Yufeng Duan ◽  
Zhaoping Zhong ◽  
...  
Keyword(s):  
Coal Gasification ◽  
Pilot Scale ◽  
Test Results ◽  
Fuel Gas ◽  
Gasification Process ◽  
Feasibility Research ◽  
Fluid Bed ◽  
Long Time ◽  
Run Test ◽  
Gasification Temperature

Coal gasification process and equipment feasibility research were carried out in a 2 MW thermal input pressurized spout-fluid bed pilot-scale gasifier and a long-time-run test was performed to study the effects of operating parameters on coal partial gasification behaviors. The test results have demonstrated the feasibility of the gasifier to provide suitable fuel gas and residual char for downstream system of 2G PFBC-CC. The concentration of methane decreased at higher gasification temperature due to the secondary cracking of methane while the carbon conversion increased, and the concentration of hydrogen increased with an increase of steam flow rate. The main experimental results were compared with those of pilot-scale facilities in the world.

Effect of Radiation Models on Coal Gasification Simulation

2012 ◽  
Author(s):  
Xijia Lu ◽  
Ting Wang
Keyword(s):  
Wall Temperature ◽  
Coal Gasification ◽  
Cfd Simulation ◽  
Stokes Equations ◽  
Heterogeneous Reactions ◽  
Coal Slurry ◽  
Radiation Model ◽  
Entrained Flow ◽  
Gasification Process ◽  
Coal Particles

Adequate modeling of radiation heat transfer is important in CFD simulation of coal gasification process. In an entrained-flow gasifer, the non-participating effect of coal particles, soot, ashes, and reactive gases could significantly affect the temperature distribution in the gasifier and hence affects the local reaction rate and life expectancy of wall materials. For slagging type gasifiers, radiation further affects the forming process of corrosive slag on the wall which can expedite degradation of the refractory lining in the gasifier. For these reasons, this paper focuses on investigating applications of five different radiation models to coal gasification process, including Discrete Transfer Radiation Model (DTRM), P-1 Radiation Model, Rosseland Radiation Model, Surface-to-Surface (S2S) Radiation Model, and Discrete Ordinates (DO) Radiation Model. The objective is to identify the pros and cons of each model’s applicability to the gasification process and determine which radiation model is most appropriate for simulating the process in entrained-flow gasifiers. The Eulerian-Lagrangian approach is applied to solve the Navier-Stokes equations, nine species transport equations, and seven global reactions consisting of three heterogeneous reactions and four homogeneous reactions. The coal particles are tracked with the Lagrangian method. Six cases are studied—one without the radiation model and the other five with different radiation models. The result reveals that the various radiation models yield uncomfortably large uncertainties in predicting syngas composition, syngas temperature, and wall temperature. The Rosseland model does not yield reasonable and realistic results for gasification process. The DTRM model predicts very high syngas and wall temperatures in the dry coal feed case. In the one-stage coal slurry case, DTRM result is close to the S2S result. The P1 method seems to behave stably and is robust in predicting the syngas temperature and composition; it yields the result most close to the mean, but it seems to underpredict the gasifier’s inner wall temperature.

A Multiphase Eulerian-Eulerian CFD Simulation of Fluidized Bed Gasification Using Malaysian Low-Rank Coal-Merit Pila

2017 ◽  
Vol 740 ◽  
pp. 163-172 ◽  
Author(s):  
Kamariah Md Isa ◽  
Kahar Osman ◽  
Nor Fadzilah Othman ◽  
Nik Rosli Abdullah ◽  
Mohd Norhakem Hamid
Keyword(s):  
Coal Gasification ◽  
Cfd Simulation ◽  
Heterogeneous Reactions ◽  
Low Rank ◽  
Maximum Temperature ◽  
Low Rank Coal ◽  
Gasification Process ◽  
Granular Particle ◽  
Experimental Values ◽  
Good Agreement

A multiphase Eulerian- eulerian model integrating the kinetic theory of granular particle (KTGF) was used to simulate the gasification of Malaysian low- rank coal (LRC), Merit- Pila inside a bubbling fluidised bed (BFB) gasifier. The model used includes the bubbling phenomenon and gasificationprocess that occurs inside a BFB gasifier. The gasification process simulated includes drying, heterogeneous reactions of char combustion, devolatilization, water- gas shift reaction, Boudourd reactionand gas phase homogenous reactions. The results from this model are compared to the results of Merit-Pila coal gasification, from which experimental data is available. Comparison of the pressure profile shows good agreement with experimental results. The temperature distribution shows that the maximum temperature is around 1100K which also shows good agreement with experimental values which is 1087K. Besides that, three out of six species mass fraction which is N2, H2 and CH4 produced similar values with experimental values. This shows the simulation conducted was capable to predict the gasification process of Low- rank coal, namely Merit-Pila.

scholarly journals Large-scale Experimental Investigations to Evaluate the Feasibility of Producing Methane-Rich Gas (SNG) through Underground Coal Gasification Process. Effect of Coal Rank and Gasification Pressure

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1334 ◽  
Author(s):  
Krzysztof Kapusta ◽  
Marian Wiatowski ◽  
Krzysztof Stańczyk ◽  
Renato Zagorščak ◽  
Hywel Rhys Thomas
Keyword(s):  
Energy Efficiency ◽  
Large Scale ◽  
Coal Gasification ◽  
Maximum Energy ◽  
Experimental Investigations ◽  
Hard Coal ◽  
Coal Rank ◽  
Underground Coal Gasification ◽  
Gasification Process ◽  
Pressure Regime

An experimental campaign on the methane-oriented underground coal gasification (UCG) process was carried out in a large-scale laboratory installation. Two different types of coal were used for the oxygen/steam blown experiments, i.e., “Six Feet” semi-anthracite (Wales) and “Wesoła” hard coal (Poland). Four multi-day gasification tests (96 h continuous processes) were conducted in artificially created coal seams under two distinct pressure regimes-20 and 40 bar. The experiments demonstrated that the methane yields are significantly dependent on both the properties of coal (coal rank) and the pressure regime. The average CH4 concentration for “Six Feet” semi-anthracite was 15.8%vol. at 20 bar and 19.1%vol. at 40 bar. During the gasification of “Wesoła” coal, the methane concentrations were 10.9%vol. and 14.8%vol. at 20 and 40 bar, respectively. The “Six Feet” coal gasification was characterized by much higher energy efficiency than gasification of the “Wesoła” coal and for both tested coals, the efficiency increased with gasification pressure. The maximum energy efficiency of 71.6% was obtained for “Six Feet” coal at 40 bar. A positive effect of the increase in gasification pressure on the stabilization of the quantitative parameters of UCG gas was demonstrated.

An Assessment of a Low-Cost Wastewater Disposal System after Twenty-Five Years of Operation

1987 ◽  
Vol 19 (5-6) ◽  
pp. 701-710 ◽  
Author(s):  
B. L. Reidy ◽  
G. W. Samson
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Wastewater Disposal ◽  
Industrial Base ◽  
Industrial Wastewaters ◽  
The Past ◽  
Gasification Process ◽  
Appropriate Treatment ◽  
Environmentally Safe ◽  
Coal Resource

A low-cost wastewater disposal system was commissioned in 1959 to treat domestic and industrial wastewaters generated in the Latrobe River valley in the province of Gippsland, within the State of Victoria, Australia (Figure 1). The Latrobe Valley is the centre for large-scale generation of electricity and for the production of pulp and paper. In addition other industries have utilized the brown coal resource of the region e.g. gasification process and char production. Consequently, industrial wastewaters have been dominant in the disposal system for the past twenty-five years. The mixed industrial-domestic wastewaters were to be transported some eighty kilometres to be treated and disposed of by irrigation to land. Several important lessons have been learnt during twenty-five years of operating this system. Firstly the composition of the mixed waste stream has varied significantly with the passage of time and the development of the industrial base in the Valley, so that what was appropriate treatment in 1959 is not necessarily acceptable in 1985. Secondly the magnitude of adverse environmental impacts engendered by this low-cost disposal procedure was not imagined when the proposal was implemented. As a consequence, clean-up procedures which could remedy the adverse effects of twenty-five years of impact are likely to be costly. The question then may be asked - when the total costs including rehabilitation are considered, is there really a low-cost solution for environmentally safe disposal of complex wastewater streams?

scholarly journals Changes in properties of tar obtained during underground coal gasification process

2021 ◽  
Author(s):  
Marian Wiatowski ◽  
Roksana Muzyka ◽  
Krzysztof Kapusta ◽  
Maciej Chrubasik
Keyword(s):  
Coal Gasification ◽  
Coal Tar ◽  
Liquid Product ◽  
Coke Oven ◽  
Underground Coal Gasification ◽  
Gasification Process ◽  
Dominant Component ◽  
Process Gas ◽  
High Volatility ◽  
Product Separator

AbstractIn this study, the composition of tars collected during a six-day underground coal gasification (UCG) test at the experimental mine ‘Barbara’ in Poland in 2013 was examined. During the test, tar samples were taken every day from the liquid product separator and analysed by the methods used for testing properties of typical coke oven (coal) tar. The obtained results were compared with each other and with the data for coal tar. As gasification progressed, a decreasing trend in the water content and an increasing trend in the ash content were observed. The tars tested were characterized by large changes in the residue after coking and content of parts insoluble in toluene and by smaller fluctuations in the content of parts insoluble in quinoline. All tested samples were characterized by very high distillation losses, while for samples starting from the third day of gasification, a clear decrease in losses was visible. A chromatographic analysis showed that there were no major differences in composition between the tested tars and that none of the tar had a dominant component such as naphthalene in coal tar. The content of polycyclic aromatic hydrocarbons (PAHs) in UCG tars is several times lower than that in coal tar. No light monoaromatic hydrocarbons (benzene, toluene, ethylbenzene and xylenes—BTEX) were found in the analysed tars, which results from the fact that these compounds, due to their high volatility, did not separate from the process gas in the liquid product separator.

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