scholarly journals Effects of temperature and additives on ash transformation and melting of high-alkali-chlorine coal

2020 ◽  
Vol 24 (6 Part A) ◽  
pp. 3501-3510
Author(s):  
Jingbin Zi ◽  
Daoyang Ma ◽  
Zia Rahman ◽  
Xuebin Wang ◽  
Hao Li ◽  
...  
Keyword(s):  
Coal Ash ◽  
Ash Deposition ◽  
High Sodium ◽  
Melting Characteristics ◽  
Ash Melting ◽  
Calcium Magnesium ◽  
Effects Of Temperature ◽  
High Alkali ◽  
Main Component ◽  
High Aluminum

The high contents of sodium and chlorine in Shaerhu coal aggravate severe slag-ging ash deposition and corrosion in boilers. Adding proper additives is an effec-tive way to reduce slagging ash deposition and corrosion. Based on the experi-mental study, this paper investigated the effect of combustion temperature, types of additives, and its amount on the ash transformation and melting of high sodium chloride Shaerhu coal. The ash melting characteristics, elemental compositions and mineral compositions of the ash produced under different conditions were characterized. Results showed that the contents of calcium, magnesium, and sul-phur in the coal ash varied slightly with the temperature increasing. Chlorine and sodium released rapidly from coal at 550-815?C and 550-700?C, respectively. At 1050?C, calcium silicate was observed as the main component of the ash. The addition of different additives had no significant effect on chlorine and sodium capture. The addition of silicon species lowered the ash fusion temperatures, while the aluminum had an opposite effect. To prevent the furnace from slagging, a high aluminum additive is proposed to be adopted.

scholarly journals Experimental Investigation of Ash Deposit Behavior during Co-Combustion of Bituminous Coal with Wood Pellets and Empty Fruit Bunches

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2087 ◽  
Author(s):  
Tae-Yong Jeong ◽  
Lkhagvadorj Sh ◽  
Jong-Ho Kim ◽  
Byoung-Hwa Lee ◽  
Chung-Hwan Jeon
Keyword(s):  
Melting Temperature ◽  
Power Plants ◽  
Bituminous Coal ◽  
Coal Ash ◽  
Milling Process ◽  
Drop Tube ◽  
Ash Deposition ◽  
Wood Pellets ◽  
Empty Fruit Bunches ◽  
Ash Melting

In Korea, oil-palm empty fruit bunches (EFBs), which are byproducts of the crude palm-oil milling process, are among the most promising potential energy sources for power plants. However, the slagging and fouling characteristics of EFBs during combustion have not yet been fully studied. Accordingly, in this study, we investigated the fundamental ash behavior of EFBs in comparison to that of wood pellets (WPs) using a thermomechanical analyzer (TMA) and a drop-tube furnace (DTF). Ash melting and the deposition of ash particles were investigated with traditional prediction indices at several biomass blending ratios. The results demonstrated that, as the ratio of WPs to EFBs increases, the melting temperature decreases and the slagging propensity increases because of the increased biomass alkali content. Moreover, the penetration derived using the TMA shows a higher melting peak at which rapid melting occurs, and the melting temperature distribution is decreased with increased biomass blending. Conversely, the DTF results show different phenomena for ash deposition under the same blending conditions. Blend ratios approaching 10% WP and 15% EFB result in gradual decreases in ash deposition tendencies because of the lower ash contents of the co-combusted mass compared to that of the single coal ash. Further biomass addition increases ash deposition, which is attributable to ash agglomeration from the biomass. Thus, this study demonstrates that blending ratios of 10% WP and 15% EFB provide optimal conditions for co-combustion with the selected bituminous coal. In addition, it is shown that the slagging propensity of EFB is higher than that of WP owing to its ash content and simultaneous agglomeration.

Effect of High-Efficiency Flux on the Melting Characteristics of Coal Ash

2013 ◽  
Vol 295-298 ◽  
pp. 3094-3097 ◽  
Author(s):  
Han Xu Li ◽  
Zi Li Zhang ◽  
Yong Xin Tang
Keyword(s):  
Melting Temperature ◽  
Coal Gasification ◽  
High Efficiency ◽  
Coal Ash ◽  
Fusion Temperature ◽  
Gasification Process ◽  
Ash Fusion Temperature ◽  
Melting Characteristics ◽  
Temperature Detector ◽  
Ash Melting

High-efficiency flux was developed to lower the ash fusion temperature of coal LQ and reduce the addition content in coal gasification process. The effect of high-efficiency flux on the coal ash melting temperature and mineral transformation were studied by ash fusion temperature detector and XRD (X-ray diffractometer) respectively in reducing atmosphere. Compared with limestone flux, the high-efficiency flux can decrease the coal ash melting temperature effectively with half addition content. The ash flow temperature (FT) of coal LQ can be lowered to less than 1350°C with the addition of 3% high-efficiency flux ,while limestone flux need to add more than 8% to reach to this temperature. With the high-efficiency flux added, cordierite, anorthite and Mg-Fe-Al oxide were formed at high temperature, which is the main reason to sharply decrease the ash fusion temperature.

Effect of CaO mineral change on coal ash melting characteristics

2020 ◽  
Vol 93 (2) ◽  
pp. 642-648 ◽  
Author(s):  
Wang Liang ◽  
Guang-wei Wang ◽  
Xiao-jun Ning ◽  
Jian-liang Zhang ◽  
Yan-jiang Li ◽  
...  
Keyword(s):  
Coal Ash ◽  
Melting Characteristics ◽  
Ash Melting

Ash Melting Behavior of Blended Coal With Chinese Xinjiang High-Alkali Coal

2017 ◽  
Author(s):  
Xiaojiang Wu ◽  
Jianwen Zhang ◽  
Xiang Zhang ◽  
Nan Chen ◽  
Kai Yan
Keyword(s):  
Melting Temperature ◽  
Ternary Phase Diagram ◽  
Combustion Process ◽  
Coal Ash ◽  
Melting Behavior ◽  
Blended Coal ◽  
Initial Melting ◽  
Ash Melting ◽  
Ash Melting Behavior ◽  
High Alkali

This paper is aimed to clarify the ash deposition/slagging behavior of blended coal with Xinjiang High-Alkali coal (HA coal) during the combustion process in boiler. One typical Xinjiang coal (HA coal) and another low-alkali coal (LA coal) have been mixed to study the ash melting behavior as a function of coal blending ratio, through the use of AFTs test, XRD, SEM-EDX characterization of ash samples and 3MW pilot-scale test. The results indicate that, the trend of AFTs is not linearly related to the blending ratio of coal mixtures. Instead, it is highly linked with the changes on the liquidus temperature from the ternary phase diagram systems. The initial melting temperature of HA coal ash is approximately 275°C lower than that of LA coal ash due to the existence of alkali and alkaline earth metals, although it has relative higher ash fusion temperature. The mixing of LA coal is not only beneficial to reduce the amount of vaporized sodium, but it also increases the initial melting temperature of blended ash due to the physical and chemical reactions between alkali and silica particles. The higher content of Na gas was formed during HA coal combustion process due to the promoted effect of the existence of Cl in HA coal. Some low melting minerals, such as Na2SO4, Na3Fe(SO4), NaS2O7, were found as the dominate minerals in its deposit ash on heat transfer tubes in the temperature range 650∼1000°C when combustion HA coal. When blended with other LA coal, the amount of deposit ash was decreased and the shape of it became looser due to some high melting minerals were found in its deposit ash, such as quartz and mullite etc. The optimum blending ratio of LA coal is 20% for its safe operation for HA coal.

Influence of coal ash on potassium retention and ash melting characteristics during gasification of corn stalk coke

2018 ◽  
Vol 270 ◽  
pp. 416-421 ◽  
Author(s):  
Heng Zhang ◽  
Junguo Li ◽  
Xin Yang ◽  
Shuai Guo ◽  
Haijuan Zhan ◽  
...  
Keyword(s):  
Coal Ash ◽  
Corn Stalk ◽  
Melting Characteristics ◽  
Ash Melting ◽  
Potassium Retention

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 Nutritional factors in milk from Brazilian mothers delivering small for gestational age neonates

1993 ◽  
Vol 27 (6) ◽  
pp. 455-462 ◽  
Author(s):  
Anete S. Grumach ◽  
Solange E.I. Jerônimo ◽  
Marcia Hage ◽  
Magda M.S. Carneiro-Sampaio
Keyword(s):  
Breast Milk ◽  
Low Birthweight ◽  
Total Proteins ◽  
Sodium Potassium ◽  
Nutritional Factors ◽  
High Sodium ◽  
Milk Samples ◽  
Calcium Magnesium ◽  
Preterm Babies ◽  
Calcium And Magnesium

The composition of breast milk from brazilian mothers delivering low birthweight infants and its adequacy as a source of nutrients for this group has not yet been fully elucidated. A total of 209 milk samples from 66 women were analysed. The mothers were divided into three groups: G1, mothers delivering term babies of low birthweight (TSGA, n=16); G2, mothers delivering preterm babies of appropriate birthweight (PTAGA, n=20); G3, mothers delivering term babies of appropriate birthweight (TAGA, n=30). The following factors were analysed: osmolarity, total proteins and protein fractions, creamatocrit, sodium, potassium, calcium and magnesium. Milk samples were collected 48 h and 7, 15, 30 and 60 days after delivery. The groups did not differ significantly in terms of osmolarity, total proteins and fractions, creamatocrit, calcium, magnesium or potassium throughout the study period. Sodium levels were higher in all samples from mothers of TSGA infants and in samples from mothers of PTAGA infants on the 7th, 15th and 30th days than in milk from the TAGA group. The authors consider the needs of the low birthweight and TAGA infants and that these high sodium levels may be necessary for growth of low birthweight infants.

scholarly journals Markov Chain Simulation of Coal Ash Melting Point and Stochastic Optimization of Operation Temperature for Entrained Flow Coal Gasification

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4245
Author(s):  
Zhang ◽  
Guan ◽  
Hou ◽  
Zhang ◽  
Li ◽  
...  
Keyword(s):  
Markov Chain ◽  
Melting Point ◽  
Stochastic Programming ◽  
Optimization Model ◽  
Coal Gasification ◽  
Coal Ash ◽  
Entrained Flow ◽  
Sample Data ◽  
Ash Melting ◽  
Mc Simulation

In the entrained flow coal gasification process, the gas production is critically affected by the operating temperature (OT) and coal ash melting point (AMP), and the AMP is one of key factors for the determinations of OT. Considering the fact that coal is a typical nonhomogeneous substance and the coal ash composition varies from batch to batch, this paper proposes the application of the Markov Chain (MC) method in simulation of the random AMP series and the stochastic optimization of OT based on MC simulation for entrained flow coal gasification. The purpose of this paper is to provide a more accurate optimal OT decision method for entrained flow coal gasification practice. In this paper, the AMP was regarded as a random variable, and the random process method, Markov Chain, was used to describe the random AMP series of feed coal. Firstly, the MC simulation model about AMP was founded according to an actual sample data, 200 sets of AMP data from an industrial gasification plant under three simulation schemes (the sample data were individually divided into 16, eight and four state groups,). The comparisons between the simulation results and the actual values show that the founded MC simulation model descries the AMP series very well. Then, a stochastic programming model based on MC simulation for OT optimization was developed. Finally, this stochastic programming optimization model was optimized by genetic algorithm (GA). Comparing with the conventional OT optimization method, the proposed stochastic OT optimization model integrated MC simulation can ascertain a more accurate OT for guiding the coal gasification practice.

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