scholarly journals Influences of Ash-Existing Environments and Coal Structures on CO2 Gasification Characteristics of Tri-High Coal

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1367
Author(s):  
Lang Liu ◽  
Qingrui Jiao ◽  
Jian Yang ◽  
Bowen Kong ◽  
Shan Ren ◽  
...  
Keyword(s):  
Functional Group ◽  
Elevated Temperatures ◽  
Group Structure ◽  
Low Rank ◽  
Mineral Matter ◽  
Microcrystalline Structure ◽  
Co2 Gasification ◽  
Gasification Reactivity ◽  
Structural Framework ◽  
Coal Particles

Two kinds of tri-high coals were selected to determine the influences of ash-existing environments and coal structures on CO2 gasification characteristics. The TGA results showed that the gasification of ash-free coal (AFC) chars was more efficient than that of corresponding raw coal (RC) chars. To uncover the reasons, the structures of RCs and AFCs, and their char samples prepared at elevated temperatures were investigated with SEM, BET, XRD, Raman and FTIR. The BET, SEM and XRD results showed that the Ash/mineral matter is associated with coal, carbon forms the main structural framework and mineral matters are found embedded in the coal structure in the low-rank tri-high coal. The Raman and FTIR results show that the ash can hinder volatile matters from exposing to the coal particles. Those results indicate that the surface of AFC chars has more free active carbon sites than raw coal chars, which are favorable for mass transfer between C and CO2, thereby improving reactivity of the AFC chars. However, the gasification reactivity was dominated by pore structure at elevated gasification temperatures, even though the microcrystalline structure, functional group structure, and increase in the disorder carbon were improved by acid pickling.

Structure and CO2 Gasification Reactivity of Char Derived through Pressured Hydropyrolysis from Low-Rank Coal

2019 ◽  
Vol 33 (9) ◽  
pp. 8032-8039
Author(s):  
Weijie Guo ◽  
Yonggang Wang ◽  
Xiongchao Lin ◽  
Guanyu Wang ◽  
Panpan Zheng ◽  
...  
Keyword(s):  
Low Rank ◽  
Low Rank Coal ◽  
Co2 Gasification ◽  
Gasification Reactivity ◽  
Co2 Gasification Reactivity

scholarly journals Surface Chemical Heterogeneity of Low Rank Coal Characterized by Micro-FTIR and Its Correlation with Hydrophobicity

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 239
Author(s):  
Wei Wang ◽  
Long Liang ◽  
Yaoli Peng ◽  
Maria Holuszko
Keyword(s):  
Surface Chemistry ◽  
Functional Group ◽  
Group Composition ◽  
Contact Angles ◽  
Low Rank ◽  
Surface Chemical ◽  
Carbonyl Groups ◽  
Low Rank Coal ◽  
Different Types ◽  
Aliphatic Carbon

Micro-Fourier transform infrared (micro-FTIR) spectroscopy was used to correlate the surface chemistry of low rank coal with hydrophobicity. Six square areas without mineral impurities on low rank coal surfaces were selected as testing areas. A specially-designed methodology was applied to conduct micro-FTIR measurements and contact angle tests on the same testing area. A series of semi-quantitative functional group ratios derived from micro-FTIR spectra were correlated with contact angles, and the determination coefficients of linear regression were calculated and compared in order to identify the structure of the functional group ratios. Finally, two semi-quantitative ratios composed of aliphatic carbon hydrogen, aromatic carbon hydrogen and two different types of carbonyl groups were proposed as indicators of low rank coal hydrophobicity. This work provided a rapid way to predict low rank coal hydrophobicity through its functional group composition and helped us understand the hydrophobicity heterogeneity of low rank coal from the perspective of its surface chemistry.

Evaluation of CO2 Gasification Reactivity of Different Coal Rank Chars by Physicochemical Properties

2013 ◽  
Vol 27 (12) ◽  
pp. 7287-7293 ◽  
Author(s):  
Xuliang Jing ◽  
Zhiqing Wang ◽  
Qian Zhang ◽  
Zhongliang Yu ◽  
Chunyu Li ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Coal Rank ◽  
Co2 Gasification ◽  
Gasification Reactivity ◽  
Co2 Gasification Reactivity

Attachment interactions between low-rank coal particles and air/oily bubbles in a microflotation cell

2018 ◽  
Vol 41 (10) ◽  
pp. 1209-1215
Author(s):  
You Zhou ◽  
Boris Albijanic ◽  
Shiwei Wang ◽  
Guosheng Li ◽  
Xiangnan Zhu
Keyword(s):  
Low Rank ◽  
Low Rank Coal ◽  
Coal Particles

scholarly journals Fish functional groups in a tropical wetland of the Yucatan Peninsula, Mexico

2016 ◽  
Vol 14 (2) ◽  
Author(s):  
Fernando Córdova-Tapia ◽  
Luis Zambrano
Keyword(s):  
Functional Groups ◽  
Functional Group ◽  
Group Structure ◽  
Environmental Filtering ◽  
Dry Season ◽  
Freshwater Wetland ◽  
Wet Season ◽  
Major Step ◽  
Natural Habitats ◽  
Niche Complementarity

ABSTRACT The characterization of species' functional traits is a major step in the understanding and description of communities in natural habitats. The classification of species into functional groups is a useful tool to identify redundancy and uniqueness. We studied the fish community of a pristine freshwater wetland in the Sian Ka'an Biosphere Reserve by analysing two multidimensional functions: food acquisition and locomotion. We investigated changes in the functional group structure between habitats (permanent and temporary pools) and seasons (dry and wet). Six functional groups with different ecological characteristics were detected, two of which had high functional redundancy and three of them were represented by single species with unique ecological functions. In permanent pools during the dry season, functional group richness and diversity were lower, while evenness was higher. During the wet season, all functional groups were detected and similar functional group structure was found between habitats. These results suggest an effect of environmental filtering during the dry season and niche complementarity during the wet season.

The chemical nature of supercritical gas extracts from low-rank U. K. coals

1981 ◽  
Vol 300 (1453) ◽  
pp. 183-192 ◽  
Keyword(s):  
Spectroscopic Analysis ◽  
Chemical Nature ◽  
Development Programme ◽  
Low Rank ◽  
Mineral Matter ◽  
Gas Extraction ◽  
Chemical Structures ◽  
Aromatic Clusters ◽  
Methylene Ether ◽  
Average Structures

Two processes are being developed by the National Coal Board for producing liquids from coal. Both involve extraction of the coal to produce an extract, freed from mineral matter, which is then catalytically hydrocracked. This approach is particularly suitable for producing transport fuels and chemical feedstocks. One process uses as solvent a process-derived liquid. The other uses a compressed supercritical gas to extract the more hydrogen-rich parts of the coal, leaving a reactive char which can provide the necessary hydrogen, heat and power for the process. As part of the development programme, extracts have been prepared by gas extraction over a range of conditions, and their chemical structures investigated by elemental and spectroscopic analysis. The average structures so derived consist of small aromatic clusters joined by methylene, ether and diphenyl linkages. Extracts produced by the liquid solvent route contain larger aromatic clusters.

scholarly journals Determination of a Complete Conversion Model for Gasification of Lignite Char

2020 ◽  
Vol 10 (6) ◽  
pp. 1916
Author(s):  
Christian Heinze ◽  
Eric Langner ◽  
Jan May ◽  
Bernd Epple
Keyword(s):  
Fluidized Bed ◽  
Carbon Capture ◽  
Full Range ◽  
Reaction Model ◽  
Low Rank ◽  
Coefficient Of Determination ◽  
Co2 Gasification ◽  
Conversion Model ◽  
Char Gasification ◽  
Pre Treatment

The conversion of solid fuels via gasification is a viable method to produce valuable fuels and chemicals or electricity while also offering the option of carbon capture. Fluidized bed gasifiers are most suitable for abundantly available low-rank coal. The design of these gasifiers requires well-developed kinetic models of gasification. Numerous studies deal with single aspects of char gasification, like influence of gas compositions or pre-treatment. Nevertheless, no unified theory for the gasification mechanisms exists that is able to explain the reaction rate over the full range of possible temperatures, gas compositions, carbon conversion, etc. This study aims to demonstrate a rigorous methodology to provide a complete char gasification model for all conditions in a fluidized bed gasifier for one specific fuel. The non-isothermal thermogravimetric method was applied to steam and CO2 gasification from 500 °C to 1100 °C. The inhibiting effect of product gases H2 and CO was taken into account. All measurements were evaluated for their accuracy with the Allan variance. Two reaction models (i.e., Arrhenius and Langmuir–Hinshelwood) and four conversion models (i.e., volumetric model, grain model, random pore model and Johnson model) were fitted to the measurement results and assessed depending on their coefficient of determination. The results for the chosen char show that the Langmuir–Hinshelwood reaction model together with the Johnson conversion model is most suitable to describe the char conversion for both steam and CO2 gasification of the tested lignite. The coefficient of determination is 98% and 95%, respectively.

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