scholarly journals Influence of the Composition of Solid Fuel on the Equilibrium Characteristics of a Gasification Process in the Mixtures of Oxygen and Carbon Dioxide

2021 ◽  
Vol 55 (6) ◽  
pp. 399-406
Author(s):  
I. G. Donskoi
Keyword(s):  
Carbon Dioxide ◽  
Coal Gasification ◽  
Solid Fuels ◽  
Endothermic Effect ◽  
Stoichiometric Ratio ◽  
Process Characteristics ◽  
Gasification Process ◽  
Chemical Efficiency ◽  
The One ◽  
Gasification Reaction

Abstract The gasification of solid fuels of different elemental compositions in O2/N2 and O2/CO2 mixtures was studied using equilibrium thermodynamic modeling. The dependences of process characteristics (temperature and the yield of carbon residue) on the composition of gasification agent and the stoichiometric ratio were calculated. The addition of carbon dioxide, on the one hand, promoted the conversion of carbon due to an increase in the concentration of gasifying agents and, on the other hand, decreased the process temperature due to an increase in heat capacity and an endothermic effect of the gasification reaction. The efficiency of using O2/CO2 mixtures for the gasification of fuels increased with the carbon content. The highest chemical efficiency of coke and coal gasification was achieved at an initial CO2 concentration of about 40–60 vol %.

scholarly journals Separating Hydrogen From Coal Gasification Gases With Alumina Membranes

1991 ◽  
Author(s):  
B. Z. Egan ◽  
D. E. Fain ◽  
G. E. Roettger ◽  
D. E. White
Keyword(s):  
Carbon Dioxide ◽  
Coal Gasification ◽  
Process Development ◽  
Porous Alumina ◽  
Mean Value ◽  
Knudsen Flow ◽  
Gasification Process ◽  
Alumina Membranes ◽  
Separation Factors ◽  
Membrane Permeabilities

Synthesis gas produced in coal gasification processes contains hydrogen, along with carbon monoxide, carbon dioxide, hydrogen sulfide, water, nitrogen, and other gases, depending on the particular gasification process. Development of membrane technology to separate the hydrogen from the raw gas at the high operating temperatures and pressures near exit gas conditions would improve the efficiency of the process. Tubular porous alumina membranes with mean pore radii ranging from about 9 to 22 A have been fabricated and characterized. Based on the results of hydrostatic tests, the burst strength of the membranes ranged from 800 to 1600 psig, with a mean value of about 1300 psig. These membranes were evaluated for separating hydrogen and other gases. Tests of membrane permeabilities were made with helium, nitrogen, and carbon dioxide. Measurements were made at room temperature in the pressure range of 15 to 589 psi. In general, the relative gas permeabilities correlated qualitatively with a Knudsen flow mechanism; however, other gas transport mechanisms such as surface adsorption may also be involved. Efforts are under way to fabricate membranes having still smaller pores. At smaller pore sizes, higher separation factors are expected from molecular sieving effects.

scholarly journals Separating Hydrogen From Coal Gasification Gases With Alumina Membranes

1992 ◽  
Vol 114 (2) ◽  
pp. 367-370 ◽  
Author(s):  
B. Z. Egan ◽  
D. E. Fain ◽  
G. E. Roettger ◽  
D. E. White
Keyword(s):  
Carbon Dioxide ◽  
Coal Gasification ◽  
Process Development ◽  
Porous Alumina ◽  
Mean Value ◽  
Knudsen Flow ◽  
Gasification Process ◽  
Alumina Membranes ◽  
Separation Factors ◽  
Membrane Permeabilities

Synthesis gas produced in coal gasification processes contains hydrogen, along with carbon monoxide, carbon dioxide, hydrogen sulfide, water, nitrogen, and other gases, depending on the particular gasification process. Development of membrane technology to separate the hydrogen from the raw gas at the high operating temperatures and pressures near exit gas conditions would improve the efficiency of the process. Tubular porous alumina membranes with mean pore radii ranging from about 9-22 Å have been fabricated and characterized. Based on the results of hydrostatic tests, the burst strength of the membranes ranged from 800-1600 psig, with a mean value of about 1300 psig. These membranes were evaluated for separating hydrogen and other gases. Tests of membrane permeabilities were made with helium, nitrogen, and carbon dioxide. Measurements were made at room temperature in the pressure range of 15-589 psi. In general, the relative gas permeabilities correlated qualitatively with a Knudsen flow mechanism; however, other gas transport mechanisms such as surface adsorption also may be involved. Efforts are under way to fabricate membranes having still smaller pores. At smaller pore sizes, higher separation factors are expected from molecular sieving effects.

Immobilization of Calcium Oxide Absorbent on a Fibrous Alumina Mat for High Temperature Carbon Dioixde Capture

2008 ◽  
Author(s):  
Man Su Lee ◽  
D. Yogi Goswami ◽  
Nikhil Kothurkar ◽  
Elias K. Stefanakos
Keyword(s):  
Carbon Dioxide ◽  
High Temperature ◽  
Calcium Oxide ◽  
Power Plants ◽  
Coal Gasification ◽  
Carbon Dioxide Emission ◽  
Oxide Content ◽  
Gasification Process ◽  
Cyclic Operation ◽  
Number Of Cycles

Anthropogenic carbon dioxide emission from its sources must be reduced to decrease the threat of global warming. Calcium oxide is considered as an effective carbon dioxide absorbent in biomass or coal gasification process as well as conventional power plants. It reacts with carbon dioxide to form calcium carbonate which can be decomposed into the original oxide and carbon dioxide at high temperature by calcination. In order to make this method practical for the carbon dioxide capture and sequestration, the performance of the calcium oxide absorbent must be maintained over a large number of carbonation/calcination cycles. For this reason, loss in the surface area of the absorbent due to pore plugging and sintering of particles in cyclic operation must be avoided. To prevent or minimize this problem, a simple and effective procedure for immobilization of calcium oxide on a fibrous alumina mat was developed in this study. The prepared samples were observed by SEM and the cyclic performance of the calcium oxide absorbent was evaluated by TGA experiments and compared to the previous studies in literature. 75% and 62% maximum carbonation conversions of the prepared absorbents with 23 wt % and 55 wt % calcium oxide content were achieved respectively and remained stable even after ten cycles whereas conversion in the literature data dropped steeply with the number of cycles.

scholarly journals Simulation of circulating fluidized bed gasification for characteristic study of pakistani coal

2015 ◽  
Vol 17 (1) ◽  
pp. 66-78 ◽  
Author(s):  
Naveed Ramzan ◽  
Muhammad Athar ◽  
Sharmina Begum ◽  
Syed Waqas Ahmad ◽  
Shahid Naveed
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Coal Gasification ◽  
Circulating Fluidized Bed ◽  
Stoichiometric Ratio ◽  
Carbon Conversion ◽  
Heating Value ◽  
Coal Gasifier

Abstract A process model for turbulent pressurized circulating fluidized-bed coal gasifier is created using ASPEN PLUS software. Both hydrodynamic and reaction kinetics parameter are taken into account, whose expressions for fluidized bed are adopted from the literature. Various reactor models available in ASPEN PLUS with calculator as External Block are nested to solve hydrodynamics and kinetics. Multiple operational parameters for a pilot-plant circulating fluidized-bed coal gasifier are used to demonstrate the effects on coal gasification characteristics. This paper presents detailed information regarding the simulation model, including robust analysis of the effect of stoichiometric ratio, steam to coal ratio, gasification temperature and gasification agent temperature. It is observed that, with the increase in the flow rate of air, the components hydrogen, carbon monoxide, carbon dioxide and methane reduce, which causes the Lower Heating Value (LHV) of synthesis gas (Syn. Gas) to decrease by about 29.3%, while increment in the steam flow rate shows a minute increase in heating value of only 0.8%. Stoichiometric ratio has a direct relationship to carbon conversion efficiency and carbon dioxide production. Increasing the steam to coal ratio boosts the production of hydrogen and carbon monoxide, and causes a drop in both carbon dioxide concentration and the conversion efficiency of carbon. High gasifying agent temperature is desired because of high concentration of CO and H2, increasing carbon conversion and LHV. A high gasifying agent temperature is the major factor that affects the coal gasification to enhance H2 and CO production rapidly along with other gasification characteristics.

scholarly journals Mathematical modelling of the oxyfuel gasification of pulverized coal fuel

2020 ◽  
Vol 209 ◽  
pp. 03011
Author(s):  
Igor Donskoy
Keyword(s):  
Mathematical Modelling ◽  
Coal Gasification ◽  
Stoichiometric Ratio ◽  
Gasification Process ◽  
Cold Gas Efficiency ◽  
Coal Fuel ◽  
Pulverized Coal Fuel ◽  
Optimal Values ◽  
Gas Efficiency ◽  
Cold Gas

In this work, we studied the efficiency of the coal gasification process under oxyfuel conditions. Using mathematical modelling one-dimensional stationary statement, the optimal parameters of coal processing were determined, air and oxyfuel conditions are compared. The calculated dependences of the characteristics of the gasification process on the stoichiometric ratio at different initial temperatures are constructed. The optimal values of oxygen stoichiometric ratio and the maximum values of cold gas efficiency in the selected range of parameters are determined. The contribution of the thermophysical and reactive properties of the gasification agent to the change in the cold gas efficiency is estimated.

scholarly journals Mathematical modelling of a staged pulverized coal gasification using O2/CO2 mixtures

2021 ◽  
Vol 2057 (1) ◽  
pp. 012064
Author(s):  
I G Donskoy
Keyword(s):  
Carbon Dioxide ◽  
Carbon Capture ◽  
Power Plants ◽  
Coal Gasification ◽  
Pulverized Coal ◽  
Process Efficiency ◽  
Transfer Coefficients ◽  
Process Change ◽  
Gasification Process ◽  
Gaseous Reagent

Abstract Conversion of pulverized coal in a two-stage gasifier is studied. When considering carbon capture power plants, mixtures of oxygen with carbon dioxide may be used as a gasification agent. Carbon dioxide is a gasification agent, so characteristics of the gasification process change significantly compared to gasification in oxygen-nitrogen mixtures. The conversion efficiency is determined by the thermophysical factor (change in the heat capacity of the gas mixture and transfer coefficients) and the concentration factor (increase in the concentration of the gaseous reagent). The ratio of primary and secondary fuel consumption determines the leading stage of the process. The influence of process efficiency on oxygen concentration is estimated in the range of 21–30 vol. %.

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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