Guidance method to use mixed coal in blending for coking

Based on the principle that the adaptation can be reflected by the overlap of reflectance distribution peaks,the effect of various types mixed coal for coking is analyzed.Based on the action of the vitrinite of different reflectance range and the adaptation,a new method for guidance blending coal is established.Through simulation,blending coal using the software of HD automatic microscope photometer,makes the synthetic blending coal reflectance distribution map to nothing notch wide single peak flat-shaped symmetrical distribution,blending coal random reflectance meets 1.1 - 1.2,the standard deviation meets 0.35 - 0.4.It is based on the conditions that active component in the blending is excessive.Using this method,the mixed coal can be used as much as possible and play a positive role.The problem about implementation process is discussed.

Speciation and thermal transformation of sulfur forms in high-sulfur coal and its utilization in coal-blending coking process:A review

The utilization of high-sulfur coal is becoming more urgent due to the excessive utilization of low-sulfur,high-quality coal resources,and sulfur removal from high-sulfur coal is the most important issue.This paper reviews the speciation,forms and distribution of sulfur in coal,the sulfur removal from raw coal,the thermal transformation of sulfur during coal pyrolysis,and the sulfur regulation during coal-blending coking of high organic-sulfur coals.It was suggested that the proper characterization of sulfur in coal cannot be obtained only by either chemical method or instrumental characterization,which raises the need of a combination of current or newly adopted characterization methods.Different from the removal of inorganic sulfur from coal,the organic sulfur can only be partly removed by chemical technologies;and the coal structure and property,particularly high-sulfur coking coals which have caking ability,may be altered and affected by the pretreatment processes.Based on the interactions among the sulfur radicals,sulfur-containing and hydrogen-containing fragments during coal pyrolysis and the reactions with minerals or nascent char,regulating the sulfur transformation behavior in the process of thermal conversion is the most effective way to utilize high organic-sulfur coals in the coke-making industry.An in-situ regulation approach of sulfur transformation during coal-blending coking has been suggested.That is,the high volatile coals with an appropriate releasing temperature range of CH4 overlapping well with that of H2 S from high organic-sulfur coals is blended with high organic-sulfur coals,and the C–S/C–C bonds in some sulfur forms are catalytically broken and immediately hydrogenated by the hydrogencontaining radicals generated from high volatile coals.Wherein,the effect of mass transfer on sulfur regulation during the coking process should be considered for the larger-scale coking tests through optimizing the ratios of different coals in the coal blend.

Combustion characteristics of high ash Indian thermal,heat affected coal and their blends

Onsite mine fire generates large volumes of heat-affected coal in Jharia coalfields,India.Direct utilization of such heat-affected coal in thermal utilities is not feasible as such coal does not have the desirable volatile matter required for combustion.In the present work,experimental studies have been carried out to investigate the possible utilization of such heat-affected coal in thermal utilities by blending with other coal.Heat-affected coal(31%ash and 5300 kcal/kg GCV)collected from Jharia coalfield were blended with thermal coal(28%ash and 5650 kcal/kg GCV)in different ratios of 90:10,80:20,70:30 and 60:40 to identify the desirable blend ratio for burning of blended coal in thermal utilities.Burning characteristics of all the coals were carried out using TGA.Various combustion parameters such as ignition temperature,peak temperature,burnout temperature,ignition index,burnout index,combustion performance index,rate and heat intensity index of the combustion process and activation energy were evaluated to analyse the combustion process.Experimental and theoretical analysis shows the blend ratio of 90:10 can be used in place of only thermal coal in utilities to reduce the fuel cost.

Prediction of ash content of unloaded coal based on a discrete element simulation

Based on analysis of regularity of stacking coal,discrete element simultaneous simulation is adopted to predict the process of unloading coal,which is proved to be effcient in the prediction of ash content.The results show that the altitude of new irregular coal is equal to the income coal volume divided by area of cabin.The distribution of infnitesimal flow velocity helps to induce the motion equation of infnitesimal element,which provides the mathematical model for computer simulation.Swarm,a computer programming language,is utilized in this study.Adaptive infnitesimal stacking algorithm helps settle the diffculties in attainment of infnitesimal elements.The result of simulation is similar to the actual situation,which can accurately predict the ash contents of current time and cumulative time.Coal movement in the cabin is a new project,the result of which can also be applied to other solid particles and the widespread of the result will be highly valued.

Characterization of bio-coal briquettes blended from low quality coal and biomass waste treated by Garant■bio-activator and its application for fuel combustion

Experimental research was carried out on the manufacturing of bio-coal briquettes from a blend of two different types of low-quality coal and biomass waste in the absence of coal carbonization,where the third blend of the material was fermented by adding a bio-activator solution before pressurizing the components into briquettes.The coal samples from Caringin-Garut Regency(BB-Garut)had a low calorific value and a high sulfur content(6.57 wt%),whereas the coal samples from Bayah-Lebak Regency(BB-Bayah)had a higher calorific value and a lower sulfur content(0.51 wt%).The biomass added to the coal blend is in the form of fermented cow dung(Bio-Kohe),and it had a calorific value of 4192 kcal/kg and a total sulfur content of 1.56 wt%.The main objective of this study is to determine the total decrease in the sulfur content in a blend of coal and biomass in which a fennentation process was carried out using a bio-activator for 24 h.The used bio-activator was made from Garant■(1:40)+molasses 1 wt%/vol,and its used amount was 0.2 L/kg.Also,the total sulfur content in the blend was 1.00 wt%-1.14 wt%,which fulfills the necessary quality requirements for non-carbonized bio-coal briquettes.The pyritic and sulfate content in the raw coal was dominant,and the organic sulfur,when fermented with Garant■,was found to be less in the produced bio-coal briquettes by 38%-58%.

Effect of Blending Ratio on the Sodium Release Behaviors,Ash Slagging Characteristics and Char Gasification Performances during Co-gasification of Zhundong Coal with Wuhai Coal

Some ash related problems,such as slagging at furnace bottom and fouling at the air pre-heater surface,are frequently encountered during circulating fluidized bed gasification(CFBG)of Zhundong coal.Low ash fusion temperatures(AFTs)and intense sodium release should be responsible for those problems.In industry,coal blending is deemed to be a feasible method to both improve AFTs and control sodium release.In this work,Wuhai coal was selected as blending coal.The ratio is varied from 0%to 40%by mass with 10%interval.The mixed samples were gasified by steam at 950°C in a lab-scale furnace.Some key indices,such as sodium release behaviors,ash slagging characteristics and char gasification performances,were investigated by ICP-OES,AFTs,XRD and TG analyzers,respectively.The results indicated that coal blending could significantly decrease sodium release behaviors.For ash slagging characteristics,it is surprised to find that three out of four AFTs(deformation temperature,softening temperature,hemispherical temperature)show an U-shaped correlation with blending ratio,indicating that a low ratio possibly causes more severe ash slagging problem.It is ascribed to the formation of substantial percentage of fusible Na-containing silicates and aluminosilicates.In addition,coal blending greatly increases ST-DT,implying that the ability of resistance to bed temperature fluctuation is markedly enhanced.Due to the high level of alkali and alkaline species,the synergistic effect is clearly observed during co-gasification.Taking all key indices into consideration,30%blending ratio of Wuhai coal is recommended.

Migration and transformation of Pb,Cu,and Zn during co-combustion of high-chlorine-alkaline coal and Si/Al dominated coal

Shaerhu(SEH)coal is abundant in Xinjiang,China.The utilization of SEH suffers from severe ash deposition,slagging,and fouling problems due to its high-chlorine-alkaline characteristics.The co-combustion of high-alkaline coal and other type coals containing high Si/Al oxides has been proven to be a simple and effective method that will alleviate ash-related problems,but the risk of heavy metals(HMs)contamination in this process is nonnegligible.Hence,the volatilization rates and chemical speciation of Pb,Cu,and Zn in co-combusting SEH and a high Si/Al oxides coal,i.e.,Yuanbaoshan(YBS)coal were investigated in this study.The results showed that the addition of SEH increased the volatilization rates of Pb,Cu,and Zn during the co-combustion at 800℃from 23.70%,23.97%,and 34.98%to 82.31%,30.01%,and 44.03%,respectively,and promoted the extractable state of Cu and Zn.In addition,the interaction between SEH and YBS inhibited the formation of the Pb residue state.SEM-EDS mapping results showed that compared to Zn and Cu,the signal intensity of Pb was extremely weak in regions where some of the Si and Al signal distributions overlap.The DFT results indicated that the O atoms of the metakaolin(Al_(2)O_(3)·2SiO_(2))(001)surface were better bound to the Zn and Cu than Pb atoms after adsorption of the chlorinated HMs.These results contribute to a better understanding of the effects of high-alkaline coal blending combustion on Pb,Cu,and Zn migration and transformation.

A review on co-pyrolysis of coal and oil shale to produce coke

It has become the top priority for coking industry to rationally use and enlarge coking coal resources because of the shortage of the resources.This review focuses on the potential utilization of oil shale(OS)as a feedstock for coal-blending coking,in which the initial and basic step is pyrolysis.However,OS has a high ash content.If such OS is directly used for coal-blending coking,the coke product will not meet market demand.Therefore,this review firstly summarizes separation and beneficiation techniques for organic matter in OS,and provides an overview on coal and OS pyrolysis through several viewpoints(e.g.,pyrolysis process,phenomena,and products).Then the exploratory studies on co-pyrolysis of coal with OS,including co-pyrolysis phenom-ena and process mechanism,are discussed.Finally,co-pyrolysis of different ranks of coals with OS in terms of coal-blending coking,where further research deserves to be performed,is suggested.

NO_(x) and H_(2)S formation in the reductive zone of air-staged combustion of pulverized blended coals

Low NO_(x) combustion of blended coals is widely used in coal-fired boilers in China to control NO_(x) emission;thus,it is necessary to understand the formation mechanism of NO_(x) and H2S during the combustion of blended coals.This paper focused on the investigation of reductive gases in the formation of NO_(x) and H2S in the reductive zone of blended coals during combustion.Experiments with Zhundong(ZD)and Commercial(GE)coal and their blends with different mixing ratios were conducted in a drop tube furnace at 1200℃–1400℃with an excessive air ratio of 0.6–1.2.The coal conversion and formation characteristics of CO,H_(2)S,and NO_(x) in the fuelrich zone were carefully studied under different experimental conditions for different blend ratios.Blending ZD into GE was found to increase not only the coal conversion but also the concentrations of CO and H2S as NO reduction accelerated.Both the CO and H2S concentrations inblended coal combustion increase with an increase in the combustion temperature and a decrease in the excessive air ratio.Based on accumulated experimental data,one interesting finding was that NO and H2S from blended coal combustion were almost directly dependent on the CO concentration,and the CO concentration of the blended coal combustion depended on the single char gasification conversion.Thus,CO,NO_(x),and H2S formation characteristics from blended coal combustion can be well predicted by single char gasification kinetics.

Generation of Polycyclic Aromatic Hydrocarbons During Coking

The generation of polycyclic aromatic hydrocarbons （PAHs） during coking was studied and the contents of sixteen PAHs were measured by the devices of ultrasonic abstraction and high performance liquid chromatography for single coal coking and blended coal coking. The results indicated that the amount of generated PAHs during the first 1--4 h of coking is the most. Among these PAHs, the tetranuclear PAHs have a major portion and the Benzo[a]pyrene which can cause cancer, and teratogenesis and mutation is generated for a larger concentration more than emission standard value. Two PAHs are the main pollutants of PAHs pollution.

Kinetic study on co-combustion of pulverized anthracite and bituminite for blast furnace injection

Combustion behavior of single pulverized coals(PCs)and co-combustion characteristics of anthracite(AT)and bituminite(BT)blends with 20 wt.%volatile were studied by thermogravimetric experiments.The results indicated that reaction characteristics of PCs were closely related to their functional group structure and consequently,the pyrolysis of PCs with highly active functional groups initiated at lower temperatures.It was also noticed that the discrepancy of functional group structures between AT and BT might impair their interaction during combustion.The early exhaust of BT at low temperatures would possibly lead to an independent combustion of volatile and residual carbon and eventually the inefficient combustion of their blend.However,the mixing of AT and BT with similar functional group structures was more likely to achieve blends with superior combustion property.Simultaneously,non-isothermal kinetic analysis mani-fested that the combustion of blends followed random pore model(RPM),and therefore,the parameters calculated by RPM were more accurate to describe their combustion behavior.The kinetic calculation results showed that the activation energy required for decomposition of blends in early combustion stage was much lower owing to the excellent activity of volatile,while residual carbon with stable aromatic hydrocarbon demanded more energy to initiate its combustion.