Elucidation of the Degradation of Poly Aromatic Hydrocarbon (PAH) in Coals During Pyrolysis

In this paper, we explore the use of high resolution transmission electron microscopy (HRTEM) in the degradation of the poly aromatic hydrocarbon (PAH) in coals of different ranks subjected to chemical plus heat treatment. The crystallite diameter on peak (10) approximations, La (10), of 37.6 Å for the high rank coal char at 700 oC fell within the HRTEM’s range of minimum-maximum length boundary of 11 x 11 aromatic aromatic fringes (28 – 44 Å). The La (10), 30.5 Å for the low rank lignite chars fell nearly on the minimum-maximum length range of 7 x 7 aromatic fringes (17 – 28 Å).The HRTEM results showed that the high rank anthracite chars at 700 oC comprised a higher distribution of larger distribution of larger aromatic fringes (11 x 11 parallelogram catenations). The mechanism for the similarity between coal chars of different ranks was the greater transition occurring in the low rank coals (lignite and sub-bituminous) to match the more resistant medium and high rank coals (bituminous – anthracite). This emphasized that the transitions in the properties of the low rank coals were more thermally accelerated than those of the high rank coals. The total PAHs detected in the coals of different ranks during pyrolysis are dominated by two- and three- ring PAHs. The amount of PAHs increase and then decrease with increase in pyrolysis temperature.

Download Full-text

Effect of the Pyrolysis Temperature on the Grindability of Semi-cokes Produced by Two Kinds of Low-Rank Coals

Energy & Fuels ◽

10.1021/acs.energyfuels.7b03285 ◽

2018 ◽

Vol 32 (2) ◽

pp. 1297-1308 ◽

Cited By ~ 3

Author(s):

Yumeng Yang ◽

Jianzhong Liu ◽

Jie Wang ◽

Jun Cheng ◽

Zhihua Wang ◽

...

Keyword(s):

Pyrolysis Temperature ◽

Low Rank ◽

Low Rank Coals

Download Full-text

The influence of steam drying process on combustion behavior of Indonesian low-rank coals

Indonesian Mining Journal ◽

10.30556/imj.vol23.no2.2020.1105 ◽

2020 ◽

Vol 23 (2) ◽

pp. 105-115

Author(s):

Datin Umar ◽

◽

Suganal Suganal ◽

Ika Monika ◽

Gandhi Hudaya ◽

...

Keyword(s):

Ignition Temperature ◽

Calorific Value ◽

High Rank ◽

Low Rank ◽

Drying Process ◽

Combustion Behavior ◽

East Kalimantan ◽

Steam Drying ◽

Low Rank Coals

Steam drying process of the Low Rank Coals (LRCs) has been conducted to produce coal which is comparable with the High Rank Coal (HRC). Characterization of the raw and dried coals was carried out through proximate, ultimate, calorific value, Fourier Transform Infrared (FTIR) spectroscopy and Thermo Gravimetry-Differential Thermal Analysis (TG-DTA) to study the combustion behavior of the coals. This study used Indonesian low rank coals coming from Tabang (TKK coal) and Samurangau (SP coal), East Kalimantan. The results indicate that the calorific value of the dried coals increases significantly due to the decrease in moisture content of the coal. The FTIR spectrums show that the methylene-ethylene (RCH3/CH2) and aromaticity-aliphaticity ratios (Rar/al) of the dried coals increased while the ratio of RCO/ar decreased which reflect that the rank of the coals increased equivalent to the high rank coal (bituminous). Meanwhile, the TG-DTA indicates that the ignition temperature (Tig) and combustion rate (Rmax) of the dried coals increased. This analysis expresses that the dried coals produced by steam drying process have better combustion behavior due to the higher calorific value than those of the raw coals.

Download Full-text

Evaluation of Acid-Leached Fly Ash as a Pozzolan

MRS Proceedings ◽

10.1557/proc-136-141 ◽

1988 ◽

Vol 136 ◽

Cited By ~ 6

Author(s):

R. T. Hemmings ◽

E. E. Berry ◽

B. J. Cornelius ◽

D. M. Golden

Keyword(s):

Fly Ash ◽

Large Scale ◽

Magnetic Particles ◽

Acid Leaching ◽

High Rank ◽

Low Rank ◽

Metals Recovery ◽

Coal Ashes ◽

Si Content ◽

Low Rank Coals

ABSTRACTDirect acid leaching (DAL) with HCl to recover Al and other metal values from fly ash has been examined extensively by the Electric Power Research Institute (EPRI) under RP2422. Large scale utilization of the solid residues from the DAL-process (DAL-residues) could significantly influence the economics of resource recovery. This paper describes a study of the potential use of DAL-residue as a pozzolan in the concrete industry.Samples of six ashes from a range of coal types were beneficiated to remove magnetic particles and particles larger than 45 gim. The beneficiated fractions were leached with 6M HCl at 105°C to determine metals recovery for Al, Fe, Ca, Mg, Na, K, and Ti. The corresponding DALresidues were characterized by chemical composition, morphology and mineralogical content, and examined as potential concrete pozzolans by standard ASTM tests. One DAL-residue from a highrank coal was examined more extensively in Portland cement mortars.The greatest yields of Al were from low-rank coal ashes, but were obtained at the ‘cost’ of substantial salt-cake production and high acid consumption. The DAL-residues from all ash types showed high-Si content: those from high-rank coals being spherical pseudomorphs of the original ash particles, and those from low-rank coals containing substantial quantities of gel-like materials.All of the residues were pozzolanic, but those from low-rank coals caused an unfavorable increase in water demand in mortars. DAL-residues from beneficiated high-rank coal ashes are enhanced pozzolans conforming to standard specification requirements with pozzolanic indices in excess of 100%.

Download Full-text

Application of NMR in Coal Reservoir Characterization

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.765-767.2168 ◽

2013 ◽

Vol 765-767 ◽

pp. 2168-2171 ◽

Cited By ~ 1

Author(s):

Zi Yang ◽

Xiao Hua Pan ◽

Sheng Qiang Yuan ◽

Zhi Feng Ji

Keyword(s):

Nuclear Magnetic Resonance ◽

Reservoir Characterization ◽

High Rank ◽

Low Rank ◽

Main Peak ◽

Low Rank Coal ◽

Trimodal Distribution ◽

Porosity And Permeability ◽

Coal Reservoir ◽

Low Rank Coals

Nuclear Magnetic Resonance (NMR) can provide information about pore and fracture structures, porosity and permeability of reservoirs. It can deep into materials without destroying samples, with advantages such as rapid, accurate and high resolution. This paper introduced the experimental principles and carried out a series of NMR experiments based on high rank coal and low rank coal samples. Results show that: the T2 spectra of high rank coal samples have an independent trimodal distribution with the main peak located at the low T2 value section, indicating that high rank coal is dominated by micropores and transition pores; while the T2 spectrum of low rank coal samples show a continuous trimodal distribution with the main peak located at the high T2 value section, demonstrating the dominance of macropores, mesopores and fractures. The pore and fracture structures of low rank coals are significantly favorable than those of high rank coals.

Download Full-text