Modelling Test of Autothermal Gasification Process Using CFD

AbstractThere are many complex physical and chemical processes, which take place among the most notable are the chemical reactions, mass and energy transport, and phase transitions. The process itself takes place in a block of coal, which properties are variable and not always easy to determine in the whole volume. The complexity of the phenomena results in the need for a construction of a complex model in order to study the process on the basis of simulation. In the present study attempts to develop a numerical model of the fixed bed coal gasification process in homogeneous solid block with a given geometry were mode. On the basis of analysis and description of the underground coal gasification simulated in the ex-situ experiment, a numerical model of the coal gasification process was developed. The model was implemented with the use of computational fluid dynamic CFD methods. Simulations were conducted using commercial numerical CFD code and the results were verified with the experimental data.

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Regression Models Utilization to the Underground Temperature Determination at Coal Energy Conversion

Energies ◽

10.3390/en14175444 ◽

2021 ◽

Vol 14 (17) ◽

pp. 5444

Author(s):

Milan Durdán ◽

Marta Benková ◽

Marek Laciak ◽

Ján Kačur ◽

Patrik Flegner

Keyword(s):

Coal Seam ◽

Regression Model ◽

Regression Models ◽

Coal Gasification ◽

Cavity Growth ◽

Temperature Data ◽

Ex Situ ◽

Underground Coal Gasification ◽

Gasification Process ◽

Cavity Growth Rate

The underground coal gasification represents a technology capable of obtaining synthetic coal gas from hard-reached coal deposits and coal beds with tectonic faults. This technology is also less expensive than conventional coal mining. The cavity is formed in the coal seam by converting coal to synthetic gas during the underground coal gasification process. The cavity growth rate and the gasification queue’s moving velocity are affected by controllable variables, i.e., the operation pressure, the gasification agent, and the laboratory coal seam geometry. These variables can be continuously measured by standard measuring devices and techniques as opposed to the underground temperature. This paper researches the possibility of the regression models utilization for temperature data prediction for this reason. Several regression models were proposed that were differed in their structures, i.e., the number and type of selected controllable variables as independent variables. The goal was to find such a regression model structure, where the underground temperature is predicted with the greatest possible accuracy. The regression model structures’ proposal was realized on data obtained from two laboratory measurements realized in the ex situ reactor. The obtained temperature data can be used for visualization of the cavity growth in the gasified coal seam.

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CFD Simulations of Allothermal Steam Gasification Process for Hydrogen Production

Energies ◽

10.3390/en14061532 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1532

Author(s):

Tomasz Janoszek ◽

Wojciech Masny

Keyword(s):

Numerical Model ◽

Coal Gasification ◽

Steam Gasification ◽

Ex Situ ◽

Hard Coal ◽

Exchange Flow ◽

Atmospheric Conditions ◽

Ansys Fluent ◽

Gasification Process ◽

Experimental Laboratory

The article presents an experimental laboratory setup used for the empirical determination of the gasification of coal samples in the form of solid rock, cut out in the form of a cylinder. An experimental laboratory set enabled a series of experiments carried out at 700 °C with steam as the gasification agent. The samples were prepared from the coal seam, the use of which can be planned in future underground and ground gasification experiments. The result of the conducted coal gasification process, using steam as the gasification agent, was the syngas, including hydrogen (H2) with a concentration between 46% and 58%, carbon dioxide (CO2) with a concentration between 13% and 17%, carbon monoxide (CO) with a concentration between 7% and 11.5%, and methane(CH4) with a concentration between 9.6% and 20.1%.The results from the ex-situ experiments were compared with the results of numerical simulations using computational fluid dynamics (CFD) methods. A three-dimensional numerical model for the coal gasification process was developed using Ansys-Fluent software to simulate an ex-situ allothermal coal gasification experiment using low-moisture content hard coal under atmospheric conditions. In the numerical model, the mass exchange (flow of the gasification agent), the turbulence description model, heat exchange, the method of simulating the chemical reactions, and the method of mapping the porosity medium were included. Using the construction data of an experimental laboratory set, a numerical model was developed and its discretization (development of a numerical grid, based on which calculations are made) was carried out. Tip on the reactor, supply method, and parameters maintained during the gasification process were used to define the numerical model in the Ansys-Fluent code. A part of the data were supplemented on the basis of literature sources. Where necessary, the literature parameters were converted to the conditions corresponding to the experiment, which were carried out. After performing the calculations, the obtained results were compared with the available experimental data. The experimental and the simulated results were in good agreement, showing a similar tendency.

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An ex Situ Underground Coal Gasification Experiment with a Siderite Interlayer. Course of the Process, Production Gas, Temperatures and Energy Efficiency

10.21203/rs.3.rs-127348/v1 ◽

2020 ◽

Author(s):

Marian Wiatowski ◽

Krzysztof Kapusta ◽

Jacek Nowak ◽

Marcin Szyja ◽

Wioleta Basa

Keyword(s):

Energy Efficiency ◽

High Temperature ◽

Flow Rate ◽

Coal Gasification ◽

High Energy ◽

Ex Situ ◽

Hard Coal ◽

Underground Coal Gasification ◽

Gasification Process ◽

Process Gas

Abstract A 72-hour ex situ hard coal gasification test in one large block of coal was carried out. The gasifying agent was oxygen with a constant flow rate of 4.5 Nm3/h. The surroundings of coal were simulated with wet sand with 11% moisture content. A 2-cm interlayer of siderite was placed in the horizontal cut of the coal block. As a result of this process, gas with an average flow rate of 12.46 Nm3/h was produced. No direct influence of siderite on the gasification process was observed; however, measurements of CO2 content in the siderite interlayer before and after the process allowed to determine the location of high-temperature zones in the reactor. The greatest influence on the efficiency of the gasification process was exerted by water contained in wet sand. At the high temperature that prevailed in the reactor, this water evaporated and reacted with the incandescent coal, producing hydrogen and carbon monoxide. This reaction contributed to the relatively high calorific value of the resulting process gas, averaging 9.41 MJ/kmol, and to the high energy efficiency of the whole gasification process, which amounted to approximately 70%.

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MODELING OF MATERIAL BALANCE FROM THE EXPERIMENTAL UCG

Acta Polytechnica ◽

10.14311/ap.2020.60.0391 ◽

2020 ◽

Vol 60 (5) ◽

pp. 391-399

Author(s):

Milan Durdán ◽

Ján Terpák ◽

Ján Kačur ◽

Marek Laciak ◽

Patrik Flegner

Keyword(s):

Laboratory Experiments ◽

Coal Gasification ◽

Cavity Growth ◽

Material Balance ◽

Ex Situ ◽

Underground Coal Gasification ◽

Unknown Parameters ◽

Gasification Process ◽

General Mass ◽

The Mathematical Model

The underground coal gasification is a continually evolving technology, which converts coal to calorific gas. There are many important parameters in this technology, which are difficult to measure. These parameters include the underground cavity growth, amount gasified coal, and the leakage of input and output gaseous components into the surrounding layers during the coal gasification process. Mathematical modeling of this process is one of the possible alternatives for determining these unknown parameters. In this paper, the structure of the mathematical model of laboratory underground coal gasification process from the material balance aspect is presented. The material balance consists of mass components entering and leaving from the UCG process. The paper shows a material balance in the form of a general mass balance and atomic species balance. The material balance was testing by six UCG laboratory experiments, which were realized in two ex-situ reactors.

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APPROACHES TO THE GAS CONTROL IN UCG

Acta Polytechnica ◽

10.14311/ap.2017.57.0182 ◽

2017 ◽

Vol 57 (3) ◽

pp. 182-200 ◽

Cited By ~ 2

Author(s):

Ján Kačur ◽

Karol Kostúr

Keyword(s):

Energy Source ◽

Coal Mining ◽

Coal Gasification ◽

Air Flow ◽

Ex Situ ◽

Underground Coal Gasification ◽

Process Variables ◽

Oxidizing Agents ◽

Gasification Process ◽

Discrete Controller

Underground Coal Gasification represents an alternative for conventional coal mining. This technology is also less expensive than traditional mining. It is expected that coal will be an important energy source in the coming decades. In requirement to improve the gasification process we must ensure that the combustion reactions generated enough energy to heat the reactants. This can be achieved by controlling the flow of oxidizing agents and the underpressure control at the exit of the reactor UCG. This paper aims to propose the stabilization of air flow as a main gasification agent injected to the gasifier, underground temperature and concentration of O2 in syngas. Also there is proposed the mechanism that could cope with uncertainties in the process of UCG and its control on stabilization level. Paper presents utilization of discrete controller with adaptation in order to stabilization of UCG process variables. The controllers were verified on experimental ex-situ reactor (generator).

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An exsitu underground coal gasification experiment with a siderite interlayer: course of the process, production gas, temperatures and energy efficiency

International Journal of Coal Science & Technology ◽

10.1007/s40789-021-00456-y ◽

2021 ◽

Author(s):

Marian Wiatowski ◽

Krzysztof Kapusta ◽

Jacek Nowak ◽

Marcin Szyja ◽

Wioleta Basa

Keyword(s):

Energy Efficiency ◽

High Temperature ◽

Flow Rate ◽

Coal Gasification ◽

High Energy ◽

Ex Situ ◽

Hard Coal ◽

Underground Coal Gasification ◽

Gasification Process ◽

Process Gas

AbstractA 72-h ex situ hard coal gasification test in one large block of coal was carried out. The gasifying agent was oxygen with a constant flow rate of 4.5 m3/h. The surroundings of coal were simulated with wet sand with 11% moisture content. A 2-cm interlayer of siderite was placed in the horizontal cut of the coal block. As a result of this process, gas with an average flow rate of 12.46 m3/h was produced. No direct influence of siderite on the gasification process was observed; however, measurements of CO2 content in the siderite interlayer before and after the process allow to determine the location of high-temperature zones in the reactor. The greatest influence on the efficiency of the gasification process was exerted by water contained in wet sand. At the high temperature that prevailed in the reactor, this water evaporated and reacted with the incandescent coal, producing hydrogen and carbon monoxide. This reaction contributes to the relatively high calorific value of the resulting process gas, averaging 9.41 MJ/kmol, and to the high energy efficiency of the whole gasification process, which amounts to approximately 70%.

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Changes in properties of tar obtained during underground coal gasification process

International Journal of Coal Science & Technology ◽

10.1007/s40789-021-00440-6 ◽

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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Modelling of the underground coal gasification process at Thulin on the basis of thermodynamic equilibria and isotopic measurements

Fuel ◽

10.1016/0016-2361(90)90149-k ◽

1990 ◽

Vol 69 (5) ◽

pp. 624-632 ◽

Cited By ~ 33

Author(s):

A DUFAUX ◽

B GAVEAU ◽

R LETOLLE ◽

M MOSTADE ◽

M NOEL ◽

...

Keyword(s):

Coal Gasification ◽

Underground Coal Gasification ◽

Gasification Process ◽

Isotopic Measurements

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Characteristics of Water Contaminants from Underground Coal Gasification (UCG) Process—Effect of Coal Properties and Gasification Pressure

Energies ◽

10.3390/en14206533 ◽

2021 ◽

Vol 14 (20) ◽

pp. 6533

Author(s):

Magdalena Pankiewicz-Sperka ◽

Krzysztof Kapusta ◽

Wioleta Basa ◽

Katarzyna Stolecka

Keyword(s):

Bituminous Coal ◽

Coal Gasification ◽

Strong Relationship ◽

Underground Coal Gasification ◽

Volatile Phenols ◽

Water Contaminants ◽

Physicochemical Composition ◽

Gasification Process ◽

Anthracite Coal ◽

Coal Properties

One of the most important issues during UCG process is wastewater production and treatment. Condensed gasification wastewater is contaminated by many hazardous compounds. The composition of the generated UCG-derived wastewater may vary depending on the type of gasified coal and conditions of the gasification process. The main purpose of this study was a qualitative and quantitative characterization of the UCG wastewater produced during four different UCG experiments. Experiments were conducted using semi-anthracite and bituminous coal samples at two distinct pressures, i.e., 20 and 40 bar. The conducted studies revealed significant relationships between the physicochemical composition of the wastewater and the coal properties as well as the gasification pressure. The strongest impact is noticeable in the case of organic pollutants, especially phenols, BTEX and PAH’s. The most abundant group of pollutants were phenols. Conducted studies showed significantly higher concentration levels for bituminous coal: 29.25–49.5 mg/L whereas for semi-anthracite effluents these concentrations were in much lower range 2.1–29.7 mg/L. The opposite situation occurs for BTEX, higher concentrations were in wastewater from semi-anthracite gasification: 5483.1–1496.7 µg/L, while in samples from bituminous coal gasification average BTEX concentrations were: 2514.3–1354.4 µg/L. A similar relationship occurs for the PAH’s concentrations. The higher values were in case of wastewater from semi-anthracite coal experiments and were in range 362–1658 µg/L while from bituminous coal gasification PAH’s values are in lower ranges 407–1090 µg/L. The studies conducted have shown that concentrations of phenols, BTEX and PAH’s decrease with increasing pressure. Pearson’s correlation analysis was performed to enhance the interpretation of the obtained experimental data and showed a very strong relationship between three parameters: phenols, volatile phenols and CODcr.

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