scholarly journals Investigation of ash deposit formation on heat transfer surfaces of boilers using coals and biomass

2019 ◽  
Vol 23 (Suppl. 5) ◽  
pp. 1575-1586
Author(s):  
Branislav Repic ◽  
Milica Mladenovic ◽  
Ana Marinkovic
Keyword(s):  
Low Rank ◽  
Biomass Combustion ◽  
Mineral Matter ◽  
Chemical Transformations ◽  
Low Rank Coal ◽  
Ash Deposit ◽  
Great Propensity ◽  
Working Parameters ◽  
Physical And Chemical ◽  
Wall Surface Temperature

Combustion of coals and biomass in boiler furnaces leads to formation of fireside deposits on irradiated and convective surfaces. This problem is not a new one, but it became one of the main operational problems in boilers using low rank coal and some sort of biomass. In the paper presented are the results of research of ash deposit processes in laboratory conditions. An experimental furnace was used for these purposes. The experiments were performed on a tubular experimental furnace which ensures appropriate temperature and mass transfer conditions for physical and chemical transformations of the mineral matter of fuel as in real conditions. The main working parameters can be varied in wide ranges. The influence of grinding fineness, excess air and wall surface temperature was analysed. Also, an ash related problems during coal and biomass combustion was considered. Key empirical correlations for slagging and fouling were tested. Two types of Serbian coals (Kolubara and Kosovo) and several biomasses were analysed. It was shown that many sorts of biomass and Kosovo coal have a great propensity to slagging and fouling.

scholarly journals Model Validation of Biomass-Coal Blends Co-Pyrolysis to Produce Hybrid Coal

2019 ◽  
Vol 2 (2) ◽  
pp. 111-117
Author(s):  
Aghietyas Choirun Az Zahra ◽  
Hendi Aviano Prasetyo ◽  
Jenny Rizkiana ◽  
Winny Wulandari ◽  
Dwiwahju Sasongko
Keyword(s):  
Model Simulation ◽  
Aspen Plus ◽  
Scaling Up ◽  
Low Rank ◽  
Biomass Combustion ◽  
Mass Composition ◽  
Constant Mass ◽  
Low Rank Coal ◽  
Biomass Blend ◽  
Steady State Simulation

Co-pyrolysis of coal and biomass blend to produce hybrid coal has recently been experimentally studied by some previous researchers. For similar generated energy, a newly developed hybrid coal is claimed to be more environmentally friendly compared to the coal only due to the release of neutral CO2. To acquire a better understanding of co-pyrolysis of coal and biomass blend, an experiment had been carried out in a tubular furnace reactor. For this purpose, the blends of constant mass composition of 20 wt% sawdust and 80 wt% low-rank coal were used throughout the study. It was found from the experiment that approximately 42.1% carbon, and 1.6% of ash were produced from the co-pyrolysis blend. Then, a steady state simulation of co-pyrolysis was developed using Aspen Plus v8.8 to predict the hybrid coal carbon content and required heat to perform the co-pyrolysis. The model simulation showed that hybrid coal yielded 44.0% carbon, which was at 4.5% deviation from the experimental study. The model had also been successfully used to estimate heat required to produce hybrid coal. It predicted that the equivalent heat of 336.2 kW was required to produce hybrid coal from 1,000 kg/h blend feed. The heat generated by the modeling of sawdust biomass combustion for fuel purposes was also estimated to supply heat for endothermic co-pyrolysis. It was found that 1,000 kg/h sawdust was predicted to be equivalent to 371.4 kW. This suggests that for scaling up purpose, ratio of sawdust fuel to blend feed of 1:1.1 is sufficient for this process. Keywords: co-pyrolysis, hybrid coal, low-rank coal, sawdust, Aspen Plus

scholarly journals Karakteristik Batubara Peringkat Rendah Formasi Bobong dan Implikasinya Terhadap Coal Liquefaction

2020 ◽  
Vol 8 (1) ◽  
pp. 17-24
Author(s):  
Supardin Nompo ◽  
Bambang Sardi ◽  
Muhammad Arif
Keyword(s):  
Reaction Time ◽  
Raw Material ◽  
Coal Liquefaction ◽  
Low Rank ◽  
Hydroxyl Group ◽  
Low Rank Coal ◽  
Catalyst Temperature ◽  
Liquefaction Process ◽  
Time Variables ◽  
Physical And Chemical

This research was conducted on the Bobong Formation coal in the form of geochemical analysis. The Bobong Formation is geologically located in the Banggai Sula Basin, Pulau Taliabu Regency, North Maluku Province. The study focused on low rank coal on the liquefaction process. Sampling locations are carried out in each coal outcrop near the river channel north of Taliabu Island. Sampling is done by the ply by ply method. Sampling is done at several points of observation in the form of a station. Coal sample analysis is carried out in the form of proximate and ultimate. The coal liquefaction experiment through the pyrolysis method with assisted microwave was carried out with raw material in the form of 300 g of 20 mesh coal, 3 g active carbon catalyst, temperature of 600 C, vacuum pressure (-3 mmHg) and 600 watt microwave power. These problems are focused on the influence of low rank coal geochemistry of the Bobong Formation in the Banggai Sula Basin on coal liquefaction and the behavior of coal liquefaction on changes in time variables. The physical and chemical characteristics of coal in coal content are ash (16.36%) adb, inherent humidity (8.19%) adb, volatile substances (22.21)%) adb and fixed carbon (48.60% ) adb, hydrogen (4.55% adb), oxygen (25.94% adb), carbon (65.33% adb), sulfur (2.54% adb) and nitrogen (1.64% adb). The optimal coal liquefaction yield with a reaction time of 60 minutes is 49%. The results of coal liquefaction did not change at the reaction time of 70 minutes and 80 minutes, respectively 49.01% and 49.02%. Coal with more lignite is more easily liquefied than sub-bituminous because coal has a higher hydroxyl group.

INVESTIGATING A LINK BETWEEN LOW-RANK COAL BEARING CARRIZO-WILCOX AQUIFER WATER AND KIDNEY DISEASE IN EAST TEXAS

2018 ◽  
Author(s):  
Jayeeta Chakraborty ◽  
◽  
Robert B. Finkelman ◽  
William H. Orem ◽  
Matthew S. Varonka ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Low Rank ◽  
East Texas ◽  
Low Rank Coal

scholarly journals Investigation of Ash Deposition Dynamic Process in an Industrial Biomass CFB Boiler Burning High-Alkali and Low-Chlorine Fuel

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1092
Author(s):  
Hengli Zhang ◽  
Chunjiang Yu ◽  
Zhongyang Luo ◽  
Yu’an Li
Keyword(s):  
Gas Flow ◽  
Circulating Fluidized Bed ◽  
Deposition Process ◽  
Biomass Combustion ◽  
Ash Deposition ◽  
Biomass Ash ◽  
Cfb Boiler ◽  
Third Stage ◽  
Ash Deposit ◽  
High Alkali

The circulating fluidized bed (CFB) boiler is a mainstream technology of biomass combustion generation in China. The high flue gas flow rate and relatively low combustion temperature of CFB make the deposition process different from that of a grate furnace. The dynamic deposition process of biomass ash needs further research, especially in industrial CFB boilers. In this study, a temperature-controlled ash deposit probe was used to sample the deposits in a 12 MW CFB boiler. Through the analysis of multiple deposit samples with different deposition times, the changes in micromorphology and chemical composition of the deposits in each deposition stage can be observed more distinctively. The initial deposits mainly consist of particles smaller than 2 μm, caused by thermophoretic deposition. The second stage is the condensation of alkali metal. Different from the condensation of KCl reported by most previous literatures, KOH is found in deposits in place of KCl. Then, it reacts with SO2, O2 and H2O to form K2SO4. In the third stage, the higher outer layer temperature of deposits reduces the condensation rate of KOH significantly. Meanwhile, the rougher surface of deposits allowed more calcium salts in fly ash to deposit through inertial impact. Thus, the elemental composition of deposits surface shows an overall trend of K decreasing and Ca increasing.

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.

Sign in / Sign up

Export Citation Format

Share Document