Clean Coal Technology

2019年01期目次

Research progress of the effects of Ca-based sorbents on the NO_x reaction in circulating fluidized bed boilers
KE Xiwei;CAI Runxia;LYU Junfu;ZHANG Man;WU Yuxin;YANG Hairui;ZHANG Hai;Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,Tsinghua University;
Circulating fluidized bed( CFB) boilers face sever challenges due to the ultra-low emission rules proposed in recent years in China.In order to decouple the contradiction between high efficiency desulfurization and de-NO_x combustion,it is necessary to deeply understand the impacts of Ca-based sorbents on nitrogen reaction.Most research shows that the limestone desulfurization and NO_x emission are closely related due to the mutual conversion among different calcium compounds and the selective catalytic relativity to several nitrogen reactions.Any affecting factor of these processes may also have significant effects on the NO_x emission.The basic nitrogen reactions under CFB combustion conditions,the mutual conversion rules of calcium compounds,the nitrogenous selective catalytic reactions,and some other factors of these processes such as flue gas composition,temperature,air distribution,etc.were reviewed,thus the influence of calcium-based desulfurization on NO_x emission were thoroughly discussed.Normally,the use of limestone leads to higher NO_x emission and lower N_2 O emission.It can be explained by many factors.For example,the Ca O particles can obviously catalyze the oxidation of volatile nitrogen to NO,the oxidation of CO which weakens the reducing atmosphere,and the decomposition of N_2 O.Nevertheless,some calcium compounds can also significantly catalyze the NO reduction,such as Ca SO_4 and Ca S.It is proved in practice that the simultaneous desulfurization and denitrification( SDD) based on limestone and SNCR or SCR is effective in CFB boilers.It is necessary to further investigate the interaction between limestone desulfurization and NO_x emission quantitatively in the future,and further develop the new generation of SDD technology,so that the simultaneous ultra-low NO_x -SO_2 emission for CFB boilers can be realized.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 698K]

Research progress on the briquette prepared from pretreated biomss
CAO Zhongyao;ZHANG Shouyu;HUANG Xiaohe;SONG Xiaobing;WU Yuanmo;School of Energy and Power Engineering,University of Shanghai for Science and Technology;
Biomass energy is characteristic of CO_2 zero emission,easy obtaining and low cost. Biomass briquetting favors its long distance transportation and long period store.The cell wall of biomass consists of macromolecule polymers,which are physical and chemical antidegradation barriers to the further improvement of the quality of biomass briquettes.Therefore,the pretreatment process is necessary for the efficient utilization of the biomass energy. The main biomass pretreatment techniques can be classified into physical,physicochemical,chemical or biological processes.The different effects of the various pretreatment process on the proportion of chemical components and the structure of the biomass lead to the differences in the physical properties and combustion characteristics of the resulted biomass briquettes.In this article,the structural characteristics of the main chemical components( celluloses,hemicelluloses and lignins) presenting in the biomass feedstock and their influences on the biomass briquetting process were introduced.Steam explosion pretreatment,low temperature pyrolysis pretreatment and hydrothermal pretreatment has been used and researched for the improvement of the physical properties and combustion characteristics of the resulted biomass briquettes and the research progress of the three kinds of the pretreatment techniques was summarized.In general,hydrothermal process is an outstanding pretreatment technology to overall enhance biomass feedstock into high-quality biomass briquettes with excellent heating value,energy density,durability and mechanical strength.However,hydrothermal process with high costs maybe has a bad impact on the environment.Therefore,the further research and development of the energy-efficient pretreatment process should be carried out to meet the requirement of the large-scale and flexible biomass briquette production techniques with high fuel quality and low operating costs,low pollutant emissions. Moreover,the high level of the system integration and parameter matching between the biomass briquetting and pretreatment processes should be accomplished.Laboratory of clean carbon-based fuel conversion,USST has been engaged in high-strength biomass briquette and charcoal briquette preparation from hydrothermal pretreated biomass for nearly ten years and a green biomass utilization technology with multi-products including biomass briquette,charcoal briquette and wood vinegar has been developed.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 1778K]

Feed coal reactivity evaluation,process intensification and environmental impact of entrained-flow coal gasification
HUANG Yuyi;LIANG Dingcheng;XIE Qiang;School of Chemical and Environmental Engineering,China University of Mining & Technology( Beijing);
China's fossil fuel reserves can be characterized as rich in coal but deficient in oil and natural gas.Thus,it is understandable that there will exist an interdependence and complementarity between coal chemical industry and petrochemical industry in China for a long time,because development and application of modern coal chemical technology is an important way to cut down the dependence on imported oil and to guarantee the energy security of China.In this paper a literature survey on evaluation methods of coal reactivity was firstly presented,in which special attention was paid to the changes of composition,structure and properties of coal under high temperature and pressure in entrained-flow gasifier.Then the potential pollution issues caused by intensification of coal gasification process were discussed in depth.The results show that the existing approaches to assessment of coal reactivity are not capable of predict accurately whether the feed coal properties match the demand of entrained-flow gasification technology.As a result,before a suitable evaluation method of feed coal reactivity is established,it is necessary to find a way or provide an apparatus to simulate the production conditions in the commercial entrained-flow gasifier.It is not limitless as concerned as intensification of gasification process,because the economical aspect is not always enhanced with the increase of extent of process intensification,so the process enhancement should be directed to balance the technological and economic indices.Under high temperature and pressure conditions of entrained-flow gasification,almost all macromolecular organic compounds in coal are decomposed,resulting in the great decrease of the content of phenols,tar,COD,BOD and other traditional pollutants.Meanwhile,some trace hazardous elements in coal are volatile and easy to be activated under high temperature and pressure,which may give rise to potential environmental issues for this hazardous trace elements will accumulate in environment upon the consumption of coal on a large scale in modern chemical industry. Among them,Hg,As and other trace elements are mostly harmful to the environment.Therefore,searching for a practicable and more accurate evaluation method of feed coal for entrained-flow gasification process,exploring the limits of process enhancement,as well as investigating the environmental impact of harmful trace elements in coal and establishing possible prevention methods,are the bottlenecks that must be solved in the further development of modern coal chemical industry.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 1231K]

Application of molecular dynamics simulation in coal structure and related fields
WANG Shanbiao;QIN Zhihong;ZHOU Jinglan;LIAN Lulu;YANG Xiaoqin;LIN Zhe;School of Chemical Engineering and Technology,China University of Mining and Technology;
With the further development of computer technologies and the application of different types of molecular dynamics simulation software,more and more coal scientists have devoted themselves into the field of dynamics simulation calculation for coal macromolecules.The deep information of the coal aggregation system were studied and their dynamic behavior characteristics were clarified in various aspects of structural characteristics,pore size distribution,thermodynamics characteristics and adsorption characteristics based on pore size distribution,etc.Therefore,the dynamics simulation calculation can effectively solve some problems that cannot be solved in the laboratory and provide more basic theoretical support for the efficient and comprehensive utilization of coal.In this paper,the progress of molecular dynamics simulation techniques in the studies of coal macromolecular structure,coal adsorption properties and kerogen molecular structure of oil shale were discussed.The related research results were briefly introduced and the disadvantage of using computer technologies to study coal structure,its function and mechanism were pointed out.This disadvantage is caused by inadequate analysis of complex coal structures instead of computational techniques such as molecular dynamics simulation.Combined with the new theory of coal embedded structure model that was established through the coal all-component separation method by extraction and reverse extraction,the detailed molecular structure,thermal change behavior and property evolution of coal group components can be studied intensively by the molecular dynamics simulation technologies.This will not only be able to verify the correctness of relevant theories and complete the work that cannot be done by experiments,but also be possible to push forward the research of coal structure and coal reactivity mechanism.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 1217K]

Research on plasma gasification technology of coal
GONG Zeru;WANG Xiaona;LYU Junfu;ZHANG Ji;Department of Energy and Power Engineering,Tsinghua University;Yantai Long Yuan Power Technology Co.,Ltd.;Electric Power Research Institute of State Grid Liaoning Electric Power Co.,Ltd.;
Plasma gasification of coal is a novel technology which can make ultra-clean use of coal come true.It has great and potential application prospect.The basic principle and three typical techniques of plasma coal gasification technology are introduced,which include steam plasma coal gasification,plasma jet aid coal gasification and CO_2 plasma coal gasification. The carbon conversion of steam plasma coal gasification is 93%-94%,whose concentration of gasification syngas conventional is 10% higher than convention.Nitrogen and argon are used in plasma jet aid coal gasification,which can realize the separation of gasification agent and working gas and the separation of generator and reactor.CO_2 plasma coal gasification is proved to be an effective method for the clean utilization of coal and resource utilization of CO_2.Besides,the latest achievements of interdisciplinary research are discussed which include the application in the ignition and nitrogen oxides reduction of power plant pulverized boiler.In terms of boiler ignition: Compared with conventional plasma ignition technology,economic benefits of plasma coal gasification technology are significant which can save thousands of tons of fuel per year.In terms of nitrogen oxide reduction: The combination of plasma jet aid coal gasification and low NO_x combustion technology is adopted by Yantai Longyuan Power Technology Co.,Ltd,in order to achieve deep reduction of nitrogen oxides and solve the problems of low coal handling capacity and high energy consumption.The test results of Longyuan show that the coal of 5 t/h could be disposed by the 60 k W plasma generator,and the low-energy plasma jet aid coal gasification could be realized. According to preliminary estimate,its initial investment is slightly less than SCR denitrification technology while its operating costs are only half of SCR.Therefore,it is suggested to introduce the internal combustion technology based on plasma ignition into the plasma coal gasification technology.In this way,the coal processing scale can be greatly increased and energy consumption can be greatly reduced.Combined the plasma gasification technology of coal with low NO_x combustion technology to industrialize,which will promote the rapid development in the field of power plant pulverized boiler. It will become a clean and efficient coal utilization method with great application prospect.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 2017K]

Precise separation and resource utilization of coal gasification fly ash
ZHAO Xu;ZHANG Yixin;MIAO Zekai;GUO Zhenkun;ZHOU Lu;LIU Kunji;WU Jianjun;School of Chemical Engineering and Technology,China University of Mining and Technology;Chinese National Engineering Research Center of Coal Preparation and Purification,China University of Mining and Technology;
Coal gasification technology plays an extremely important role in China 's economic development. But it will generate a large amount of fly ash which is consisted of unreacted pulverized coal and slag brought by synthesis gas.After preliminary flocculation,the moisture content of fly ash collected by spraying is 55%-60%,and the rest of the ash is mixture of residual carbon and glass particles.It is necessary to have a better understanding of the structural characteristics,water holding properties and the interaction between water and solid particles of fly ash so that the ash can be fully utilized.In this paper,the significance of dehydration and decarburization,the characteristics of water holding capacity,the technology of water removal and the scheme of comprehensive utilization of fly ash were discussed in order to seek the scientific separation and resource utilization technology of fly ash.At last,prospects for precise separation and resource utilization of coal gasification fly ash was forecasted.Previous experiments show that fly ash-based zeolite has high surface area,unique pore characteristics and excellent ion exchange ability,which can be used to remove heavy metals in soil and wastewater,and as adsorbent to fix pollutants in soil.The chemical composition of fly ash is similar to clay.The reserves of traditional ceramic raw materials are decreasing day by day.Some studies at home and abroad have confirmed that it is feasible to prepare ceramic floor tiles with fly ash.Foreign scholars used fly ash to replace quartz in traditional ceramics.At a certain sintering temperature,the effects of fly ash on the properties of sample ceramics were studied through the changes of flexural strength,water absorption,shrinkage,weight loss rate and so on.It was concluded that the properties of ceramics with fly ash were better than those of traditional ceramics.The gasification fly ash particles were separated by foam flotation method,and the carbon and vitreous of gasification fly ash were obtained respectively. The separated carbon residue was used as the carbon source for catalytic graphitization. The catalyst was then treated by adding graphitization in the process of high temperature heat treatment,so as to explore the feasibility of preparing the graphitized material by gasification fly ash.Ordered graphitization materials with similar properties to commercial graphite were obtained under catalytic conditions. Gasification fly ash and power plant fly ash both have high content of silicon and aluminium,which makes gasified fly ash a potential important source of porous materials such as zeolite molecular sieves.The preparation of zeolite is also the most efficient way to recycle fly ash.This process not only reduces the environmental burden of ash waste,but also applies to catalysis,separation and adsorption. In the future,the occurrence of water in fly ash and its interaction mechanism with fly ash particles should be studied in depth.At the same time,the interface model of ash-water interaction should be constructed.On this basis,new technology of fly ash dewatering should be sought to further reduce the water content of fly ash.The carbon-vitreous separation technology with low energy consumption,high efficiency and less pollution should be studied to reduce the impurity content of the separation products,and new fields of resource utilization of sorted charcoal and vitreous body should be studied to maximize the value of gasified fly ash.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 1208K]

Research progress on volatiles and sulfur removal during low temperature pyrolysis of coal
YANG Fengling;REN Lei;JIA Yangjie;WU Haibing;DI Zichen;CHENG fangqin;Collaborative Innovation Center of High Value-added Utilization of Coal-related Wastes,State Environmental Protection Key Laboratory of Efficient Utilization Technology of Coal Waste Resources,Shanxi University;Shanxi Rui En Ze Technology Co.,Ltd.;
Aiming at the problem of serious air pollution caused by poor quality of coal and inability to centralize the treatment of pollutants in China's civil combustion at present,effects of atmosphere,additives and heating rate on coal pyrolysis was analyzed based on the principle of coal pyrolysis and the occurrence form of sulfur.The relatively mature dry distillation process of pulverized coal at home and abroad was discussed,the advantages and disadvantages of dry distillation of pulverized coal and lump coal were analyzed,and the technological thinking of briquette pyrolysis of pulverized coal was put forward.The pyrolysis process route of anthracite-carbonized briquette jointly developed by Shanxi University and Shanxi Lingjun Heavy Industry Group was introduced. Clean coal clean combustion multi-production process system was proposed.The dry distillation process of pulverized coal takes pulverized coal and granular coal as raw materials,which is easy to cause dust deposition and blockage,and can't be separated efficiently.Lump coal can improve the separation efficiency of tar and oil,but non-sticky coal will be pulverized in the pyrolysis process,and the efficiency is not high.Using semi-coke as heat carrier will reduce the utilization efficiency of semi-coke and produce a large number of coke powder. Civil combustion of coke powder needs to be shaped,and it is difficult to bond.In view of this,the idea of coal blending forming pyrolysis is put forward.The briquette of semi-coke powder after pyrolysis can increase the yield of oil and gas,and has good strength.It can be separated from tar efficiently,and its products can be controlled for civil use according to the process.Coal briquette produced by coal briquetting pyrolysis combined with anthracite-carbonized briquette jointly has a high overall utilization rate.The pollutants produced can be extracted into high value-added by-products,which can effectively control dust pollution and improve the quality and value of coal.The volatile matter and calorific value of smokeless carbon are higher than those of anthracite coal,and the intensity of smokeless carbon is high.The smokeless carbon used in civil combustion fully conforms to the national standards.Clean coal clean combustion multi-production process system combines circulating fluidized bed power generation,clean coal production and fly ash ceramsite production.It can effectively use preheating of power plant as heat source,and use dry distillation gas produced by dry distillation briquette as gas source for ceramsite sintering to obtain clean briquette products,realizing comprehensive utilization of solid waste and clean combustion.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 2754K]

Technical progress and industrialization status of coal to fuel oil in China
HU Fating;YAN Bingfeng;WANG Guangyao;GU Xiaohui;CHANG Qiulian;Coal Chemistry Branch of China Coal Research Institute;State Key Laboratory of Coal Mining and Clean Utilization;National Energy Technology and Equipment Laboratory of Coal Utilization and Emission Control;
China is rich in coal and poor in oil and gas,it is of great significance to produce clean fuel oil by using coal as raw material.In order to realize healthy and orderly development of China's coal to fuel oil industry,The definition,principle and technological process of direct coal liquefaction,indirect coal liquefaction and coal-oil co-processing were introduced.The development course,technology research and industrial application of coal to fuel oil technology in China were reviewed.The existing technical problems and industrial application of three kinds of coal to fuel oil were summarized,and the technical difficulties and application prospects of the three kinds of coal to fuel oil were discussed and prospected.Industrial demonstration projects have been completed for these three types of coal to fuel oil technologies,and have entered the stage of commercial development.Because of the particularity of technology and raw materials,the direct coal liquefaction and coal-oil co-processing have now only built a set of industrial demonstration units. There are about 10 indirect coal liquefaction projects in China that have been put into production or tested successfully,with a total capacity of nearly 10 million tons.It provides an important reference for the long-term planning and policy-making of coal to fuel oil industry in China.Direct coal liquefaction technology with low coal consumption and low investment and operation cost should focus on improving the quality and quantity of circulating solvents in the future.The technology of indirect coal liquefaction is mature,and it is a key popularized technology.The development trend of indirect coal liquefaction technology in the future is to expand the product category and increase the added value of the product. Enterprises with coal and heavy oil resources suitable for liquefaction are suitable for the development of coal-oil co-processing industry.The government should increase investment in research and development of coal to oil,focusing on solving the existing problems of high water consumption,energy consumption,carbon emissions,etc.The government should give policy support to the coal to oil industry,promote the rapid development of the coal oil industry and ensure the national energy security.It is a new pattern and new trend of development for the coal industry to actively and steadily develop the coal to fuel oil industry under the guidance of planning.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 1398K]

Research progress on flue gas water recovery technology in wet FGD
MA Shuangchen;BIE Xuan;SUN Yao;GONG Chunqin;QU Baozhong;Department of Environmental Science and Engineering,North China Electric Power University;
The wet limestone gypsum method is currently the most widely used flue gas desulfurization method,but the water problems involved are not negligible.Environmental problems such as haze,white plume and gypsum rain are all related to water problems.At the same time,the water content in the flue gas is large,and the realization of flue gas water recovery is of great significance for water saving in power plants.The sources of water in the flue gas and water recycling technology were overviewed,and the principles,advantages and disadvantages,current research and application situation of flue gas water recovery technologies were analyzed.The methods to achieve water recovery includes condensation,membrane and absorption methods.The water quality of water recovery technology using condensation is poor and corrosive,but it has the large amount of water.The system of water recovery technology using absorption is relatively simple,and the water quality is also good,but it has the risk to bring absorption solutions with flue gas together.While the water recycling technology using membrane has good water quality and no pollutant emissions,which is a promising technology,but its recovery water amount still has room for improvement.Cleaning,reducing or even preventing fouling is the key to limiting the development of the technology.Power plants should select specific condensation technology according to the actual situation.Membrane technology can be given priority with stable operation and good defogging effect,and condensation method can be given priority with demand for waste heat recovery in power plants.It is pointed out that the fundamental solution to the water problem is to change the flue gas desulfurization method.Dry desulfurization is one of the most promising methods because of no account of wastewater,no increase in water vapor content in flue gas and avoiding corrosion.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 1785K]

Research progress on biodegradation technology of residual agents in mineral processing wastewater
ZHANG Dongchen;WANG Fanglue;DONG Jingshen;ZHENG Jing;QIN Huayu;CHENG Juan;FU Peng;College of Material Science and Engineering,Anhui University of Science and Technology;
Beneficiation agents usually regulate the physical and chemical properties of selected minerals and flodation media,which can expand the hydrophilic-to-hydrophobic differences between valuable minerals and gangue minerals and then achieve the best separation effect.There are many kinds of beneficiation agents and the direct discharge of mineral processing wastewater which contains residual chemicals will cause serious pollution to the environment.As a new biochemical treatment method,biodegradation has many advantages,such as low lost,low energy consumption and no secondary pollution.Therefore,it is of practical significance to study high efficiency biodegradation of residual agents in mineral processing wastewater.In this paper the current biodegradable research progress of mineral processing agents,such as xanthate,aerofloat,hydroxamic acid and pine oil were reviewed.The main factors affecting the degradation and biodegradation problems of beneficiation agents were analyzed and the future research work were also forecasted.The results show that the initial concentration,p H,temperature,shaking rate,time,C/N ratio,nitrogen source and metal ions are the main factors affecting the biodegradation of xanthate.External carbon sources can promote the degradation of xanthate.CS2,ROCSSH and mono-thiocarbonate are the main degradation products of alkyl-xanthate,accompanied by a few oil droplets of double-xanthate,which belongs to the first-order enzymatic degradation kinetics.The intermediate product of xanthate decomposition is xanthate peroxide.The analysis concluded that additional carbon sourses can promote the degradation of aniline aerofloat.Hydroxamic acid collectors are a first-order reaction kinetics.Besides,factors influencing the degradation of pine oil include p H,inoculation amount,temperature,shaking speed,initial concentration,time,etc.In view of the main problems about biodegradation of mineral processing agents,the future work should imitate the biotechnological means of similar fields to screen highly efficient degradation strains.The research on degradation mechanism should be deeply studied and new biodegradable strains should be constructed by genetic engineering at the molecular level.Meanwhile,the development of biodegradation equipment should be accelerated.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 1982K]

Synergistic adsorption of inorganic salt and surfactants on the surface of low rank coal
WANG Mengxia;CHE Xiaoyu;LYU Mengxuan;LI Lin;ZHANG Qingjian;School of Chemistry and Environmental Engineering,Shandong University of Science and Technology;Inspection and Quarantine Technology Center,Shandong Entry-Exit Inspection and Quarantine Bureau;
The Low rank coal surface with oxygen-containing functional groups was strong hydrophilicity and poor floatation. This study used the non-ionic surfactant nonylphenol polyoxyethylene ether( NP-10) and inorganic salt( Na Cl,Ca Cl_2,Al Cl_3) to adsorb and modify the surface of low rank coal,and further to investigate the synergistic modification behavior.Adsorption experiments show that the equilibrium adsorption capacity of low rank coal slime on NP-10 gradually increases with the increased of its concentration,after that it tends to be stable when it reaches a certain value.The adsorption is in accordance with Langmuir adsorption model.Gibbs free energy( ΔG) and standard adsorption enthalpy( ΔH) with negative value show that the adsorption process is spontaneous exothermic.ΔG gradually decreases with the increase of temperature,indicating that increasing temperature can promote adsorption.Adsorption kinetics results show that quasi-second order kinetic adsorption mode is suitable for the adsorption of NP-10 on low rank coal surfactants.The addition of Na~+,Ca~(2+),Al~(3+)can promote the adsorption of NP-10 on the low rank coal slime,among which the promotion effect of Al~(3+)is the best,followed by Ca~(2+),and finally Na~+.X-ray photoelectron spectroscopy( XPS) results show that the content of carbon element on coal surface significantly increases after adsorption,while the content of oxygen element significantly decreases. It reveals that the hydrophilic group of NP-10 is combined with the oxygen-containing functional groups on the surface of low rank coal,which effectively covers the coal surface and improves the hydrophobicity of coal slime.Due to addition of Na~+,Ca~(2+)and Al~(3+),the content of oxygen element on the surface of coal after adsorption are reduced by 5.79%,6.77% and 7.42%,respectively. The contents of oxygen-containing functional groups on the surface of the low-rank coal also decrease,especially C—O functional groups.All the three cations could promote the adsorption of NP-10 on the surface of lowrank coal slime,the promotion efficiency of three cations is Al~(3+)>Ca~(2+)>Na~+.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 3668K]

Study on the separation technology for high efficiency power coal
CUI Guangwen;SUI Wenhao;College of Chemical Environmental Engineering,Shandong University of Science and Technology;
During the separation process of power coal,the clean coal usually re-mixed into the blended coal due to the dewatering of below2 mm coal slurry.The process of Gaojialiang power coal preparation plant was investigated by analyzing the coal quality.Coal slime under 2 mm desliming screen was re-sorted into the triple-cone angle cyclone.By changing the structural parameters and operational parameters of the triangle angle cyclone,the optimal separation results were obtained,and the separation effect and economic benefits were analyzed.According to the test results of the separation of coarse slime,the ash fraction is 8% with the yield of 30. 91%,the tailings yield of 17. 41%,the ash content of 48. 34%,and the fine slime yield of 51. 68%.After increasing triangle angle cyclone,a part of coarse coal slime can be separated to get clean coal.154 100 tons of high calorific clean coal can be produced per year.The price of clean coal is 298 yuan per ton with ash content of 8%.The yield is 1.05% after removing other products from the final coal system,and the ash content is 48. 34% with total benefit at 16. 646 3 million yuan.As a new type of high efficient crude slime separation equipment,triangle angle water medium separation cyclone has the advantages of simple structure,small occupancy space,wide feed size range,strong adaptability,high separation accuracy and high stability and reliability.Triangle angle cyclone is used to separate coarse slime in power coal preparation plant,which improves the process flow of power coal preparation plant and maximizes the benefit of coal preparation.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 1488K]

Effects of Ca and occurrence forms on transformation behavior of nitrogen during coal pyrolysis
PAN Fengping;LUO Jia;ZHANG Yufeng;XIAO Li;HUANG Weijian;XU Yishu;Guangdong Diankeyuan Energy Technology Co.,Ltd.;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology;
NO_x roles as one of those important atmospheric pollutants and the formation of NO_x during coal combustion is related to the occurrence of N in coal and their behavior in the pyrolysis and combustion process. Coal powder with Ca in different occurrence forms was prepared by physical mixing and impregnation,and effect of Ca in different occurrence forms on nitrogen conversion characteristics was researched during pyrolysis on a tube furnace. Results show that Ca in inorganic form can increase coke nitrogen content during pyrolysis,while Ca in organic form tends to decrease coke nitrogen content. The excluded type mineral Ca( OH)2 reduces the formaction of NH_3.Adding calcium acetate,both in excluded and included type,reduce the formation of NH_3 while improves the yield of HCN,which indicates that organic Ca would promote the partitioning of nitrogen in coal into HCN.What's more,the effects of calcium acetate in the excluded type is more remarkable than that in included the type.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 2362K]

CO₂ gasification properties of coal chars and fine chars from fluidized bed gasification of Shenmu coal
FAN Hongli;LI Fenghai;HUANG Jiejie;School of Chemistry and Chemical Engineering,Heze University;Institute of Coal Chemistry,Chinese Academy of Sciences;
To investigate the CO_2 gasification properties of coal chars and fine chars from fluidized bed gasification,the influences of gasification temperature and CO_2 partial pressure on Shenmu coal chars and fine chars were analyzed by thermogravimetric analyzer.The results show that increase in gasification temperature with constant CO_2 partial pressure or increase in CO_2 partial pressure with constant temperature could all accelerate the gasification reaction,thus shortenes the required reaction time of a certain conversion rate.With increasing carbon conversion rate,the carbon reaction rates of Shenmu coal chars and fine chars increase quickly and then decrease slowly after reaching the maximum value.The gasification reaction activation energy of Shenmu coal chars and fine chars with CO_2 are all increased with increasing carbon conversion rate,the reaction activation energy of fine chars is higher than that of coal chars at the same carbon conversion rate.Shenmu coal char has higher CO_2 reactivity than Shenmu fine chars.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 1076K]

Effect mechanism of calcium-bearing and iron-bearing minerals on slag blockage of pulverized coal gasification
LI Hanxu;MAO Lirui;TAO Ran;HU Xia;HUA Guiyi;School of Chemical Engineering,Anhui University of Science & Technology;Zhongan United Coal Chemical Co.,Ltd.;
In order to study the mechanism of slag blockage of pulverized coal gasification,the industrial slag samples( normal slag samples and unnormal slag samples) taken from coal gasification unit and the XZ coal ash slag samples( experimental slag samples) obtained from bench scale tube furnace in different temperature and reducing atmosphere were investigated.The ash chemical composition,crystal mineral composition,microscopic morphology and chemical composition of the micro-zone of slag samples were studied by X-ray Fluorescence( XRF),X-ray diffractometer( XRD) and Scanning Electronic Microscopy combined with energy Dispersive X-ray Spectrometer( SEMEDX) respectively.The results show that the main reasons of slag blockage of coal gasification is the formation of anorthite and iron precipation in slag samples.The iron precipation in slag under reducing atmosphere is caused by the formation Fe-O-S eutectic,which is converted by Fe O,Fe Sxand Fe S.The temperature fluctuations of gasifier operation is likely to lead to the formation of anorthite,and the massive formation of anorthite in slag is intrinsically linked to the enrichment of iron minerals and the precipitation of elemental iron.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 2916K]

Numerical simulation and analysis of reductive atmosphere in air staged pulverized coal combustion
CHEN Denggao;LI Zhenshan;CAI Ningsheng;Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,Tsinghua University;
Air staged pulverized coal combustion is a widely used low NO_x combustion technology.Numerical simulation method has been used to help improving the combustion inside the furnace in order to further reduce the pollutants during combustion process.The prediction of reductive atmosphere is the foundation for accurate prediction of NO_x emission,H_2 S erosion,and so on.The main purpose of the paper is to propose a route for reasonable numerical simulation of air staged combustion.And apply the proposed methods on the simulation of actual boilers and analysis the effect of the prediction accuracy of the reductive atmosphere.The main content includes: ① The characteristics of pulverized coal air staged combustion was discussed.A research routine for the development of numerical simulation models and its application was developed.This includes the model development and validation based on air staged combustion drop tube furnace experiments,and application of the developed model on commercial CFD simulation platform for numerical simulation of air staged combustion. ② A drop tube furnace experiment platform was built to form a temperature and species field that is similar to actual boiler.The combustion stability of the system was quantified by online measured coal feeding rate and gas species concentrations. Experiments under different conditions were designed and conducted to obtain key results,for example the concentration of CO,H_2 and coal conversion. Thirdly,a coal reaction model that can simulate both oxidation and gasification reaction was developed and coupled into commercial CFD platform.The developed models were applied on the simulation of a 600 MWe super critical wall fired furnace.③ The simulated results with consideration of char gasification and without that were compared in terms of the distribution of reductive gases,NO_x distribution and emission,and coal conversion.The results showed that the proposed routine gave a good prediction of the air staged combustion process,especially the reductive atmosphere.It was found that without the consideration of char gasification,the formation of reductive gases,NO_x emission and char conversion cannot be reasonably predicted.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 5435K]

Effect of flue gas physical properties on convective heat transfer of coal-fired boiler in O₂/CO₂ atmosphere
ZHANG Tian;YAN Kai;WU Xiaojiang;HAN Zhijiang;ZHOU Yuegui;School of Mechanical and Power Engineering,Shanghai Jiao Tong University;Shanghai Boiler Works Co.,Ltd.;
As a kind of high alkali metal coal with broad prospect of exploitation and utilization,Zhundong coal in Xinjiang is easy for slagging,which greatly limits its efficient utilization. Much research work has been done on its conventional combustion,but the research on combustion and heat transfer characteristics in O_2/CO_2 atmosphere is still insufficient.In order to study the effect of burning Zhundong coal in O_2/CO_2 atmosphere on alkali metal release and heat transfer performance of heat exchanger,the chemical process analysis software Aspen Plus was used to establish the combustion process flow model of Zhundong coal under the atmosphere of air and O_2/CO_2 for reaction simulation.By controlling the constant O_2/fuel ratio and adjusting the ratio of O_2/CO_2,the adiabatic flame temperature of burning Zhundong coal in O_2/CO_2 is close to that in the air atmosphere.There is a similar temperature distribution in the boiler under these two working conditions.By Gibbs reactor,the product components and state parameters were obtained under the conditions of phase equilibrium and chemical equilibrium,and the occurrence and transformation of Na elements were obtained,which provided a reference for predicting the release form of Na.Due to the high concentration of CO_2 and water vapor content in the oxy-coal combustion flue gas,the heat transfer characteristics of the coal-fired flue gas under the oxy-coal combustion mode will be significantly different.The PR-BM physical property method was used to estimate the physical properties of the flue gas produced by burning Zhundong coal in air and O_2/CO_2 atmosphere,and the density and specific heat capacity of flue gas in different atmosphere were compared and analyzed.The variation of thermal conductivity and viscosity with temperature provides more accurate parameters for analyzing the difference of heat convection characteristics of coal combustion flue gas in air and O_2/CO_2 atmosphere.The heat transfer performance of boiler convection heating surface was analyzed by combining heat transfer theory calculation with CFD analysis.With the decrease of smoke temperature,the existing form of Na gradually changed from Na Cl and Na OH to Na2 SO_4.Oxygen-enriched/flue gas recirculation combustion increases the fouling and slagging of high alkali coal ash.Due to the increase of CO_2 and H_2 O concentration in oxy-coal combustion flue gas,the convection heat transfer performance is enhanced,and the heat transfer coefficients of each convective heating surface increases respectively.The heat transfer coefficient of each convection heating surface is about 1.24-1.27 times of that of conventional working conditions.The convective heat transfer coefficient of the high temperature reheater increases by 24.8 W/( m~2·K) and the steam temperature at the outlet of each pipe nearly increases by 11.32 K under the condition of oxy-coal combustion.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 4630K]

Operation performance and economic benefit on chemical agglomeration of fine particles from a 300 MW coal-fired power plant boiler
QIN Zhanfeng;ZHU Baoyu;GUO Yiquan;ZHAO Yongchun;LI Gaolei;ZHANG Junying;Fengcheng Power Generation Co.,Ltd.,China Guodian Corporation;State Key Lab of Coal Combustion,School of Energy and Power Engineering,Huazhong University of Science and Technology;
To achieve ultra-low emission of coal-fired power plants,the industrial application trials of fine particle chemical agglomeration enhanced dust removal system from a 300 MW coal-fired boiler plant boiler was studied in this paper.The effect of chemical agglomeration system on removal efficiency of fly ash fine particles and operational parameters of coal-fired power plant were studied,as well as the economic benefit of chemical agglomeration enhanced dust removal technique.The whole year operating data of the unit showes that the particle concentration after WFGD decreases to 3.7 mg/m~3,which is decreased by 44.7% with the chemical agglomeration enhanced dust removal system.As for a 300 MW coal-fired boiler,the initial investment for chemical agglomeration technique is only about 6 million yuan,less than half of the cost for the wet electrostatic precipitation,which shows a better economy.The average SO_2 concentration after ESP and WFGD decrease.The average O_2 concentration increases by 0.5%.Besides,the flue gas temperature after ESP decreases by 3-8 ℃.The fine particle chemical agglomeration enhanced dust removal system helpes to improve the removal efficiency of fly ash fine particles.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 2218K]

Research on removal of elemental mercury by fulvic acid carbon-based sorbents loaded with silver
LIU Xinqiang;ZHANG Huawei;Shanxi Coking Co.,Ltd.;Chemical and Environmental Engineering College,Shandong University of Science and Technology;
Mercury is one of the harmful trace elements in coal,and it has strong volatility.Almost all mercury is released into the atmosphere during coal combustion,which has an impact on the environment and human health.In the process of methanation of coke oven gas to produce liquefied natural gas,in order to reduce the pollution of elemental mercury,Hg~0 is usually removed before liquefaction.In view of the process requirements,this paper taked advantage of the advantages of low-cost fulvic acid,abundant reserves,carbon content not less than 40%,hydrophilicity and weak acidity,and ion exchange reaction with metal ions to form complexes.The fulvic acid was selected as a template and a carbon source,and the rich surface functional groups in the molecular structure were easily chelated with silver ions. The nano-silver-loaded carbon-based adsorbent Ag/FA was synthesized in situ by freeze-drying and high-temperature carbonization to remove elemental mercury( Hg~0) in the reducing gas at a low temperature.The synthesized material was analyzed and characterized,and the effects of operating temperature,space velocity and H_2 S on the performance and life of the adsorbent were investigated.XRD characterization results show that there are four sharp diffraction peaks in elemental silver corresponding to different cubic crystal planes of elemental silver,which indicates that nano-sized elemental silver particles are successfully loaded into carbon materials in a highly dispersed form,and silver particles are calculated.The average particle size is about 12 nm.The evaluation results of the adsorbent show that the adsorbent has good mercury removal performance when the reaction temperature is 30-60 ℃ and the space velocity is less than 60 000 h~(-1).The mercury removal efficiency can be maintained above 99% and has anti-H_2 S poisoning performance.When the penetration rate is 5%,the adsorbent can adsorb mercury up to 650 μg/g.The Ag/FA adsorbent can maintain the mercury removal efficiency of more than 95% after 4 times of regeneration,and the adsorption amount of Hg~0 after adsorption for 50 h is 552 μg/g.Hg-TPD characterization results show that the silver nanoparticles loaded on the adsorbent surface are active sites for mercury adsorption.Gaseous mercury first diffuses to the adsorbent surface,and then reactes with the silver particles loaded on the adsorbent to form Ag-Hg alloy.In this paper,humic acid can be used to chelate the characteristics of silver ions.A new gaseous mercury adsorption material based on humic acid Ag/FA can remove elemental mercury from coke oven gas methanation gas effectively,and has excellent adsorption efficiency and capacity.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 2270K]

Study on conversion process by mild supercritical thermal extraction coupled with carbonization technology of Datong coal
LUO Huafeng;QIAO Yuandong;XU Qingyun;YANG Lei;ZHAO Luheng;LI Can;Coal Engineering College,Shanxi Datong University;
In order to achieve the high efficient and upgrading utilization of low-rank coal,the thermal extraction oil and high specific surface area activated carbon were prepared by mild supercritical thermal extraction coupled with carbonization technology using Datong coal.The activated carbon were analyzed by scanning electron microscope( SEM),X-ray diffraction( XRD) and Fourier transform infrared spectroscopy( FT-IR).The adsorption properties were tested by methylene blue.The results show that thermal extraction rate of coal reaches 26.23%,and carbon material yield of thermal extraction residue and Datong coal are 45.95% and 46.87% respectively.The maximum adsorption amount of thermal extraction residue based carbon material reaches 1 340 mg/g,and the removal rate of methylene blue reaches95.7%,while,maximum adsorption amount of Datong raw coal based carbon material is only 1 040 mg/g,and the removal rate of methylene blue is 74.3%.It is found that Datong coal not only produces a certain number of thermal extraction oil,but the thermal extraction residue is also converted into high specific surface area activated carbon under the condition of mild-low-temperature activation. The adsorption properties of the activated carbon on methylene blue are better than common active carbon.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 2012K]

Electrochemical performance of hierarchical porous carbons prepared from coal based humic acid
LIU Yingbin;HUANG Guangxu;LI Yuanyuan;ZHANG Fengmei;WANG Qianqian;XING Baolin;ZHANG Chuanxiang;CHEN Lunjian;College of Materials Science and Engineering,Henan Polytechnic University;
In order to improve coal utilization efficiency,hierarchical porous carbon electrode materials( HPCs) for double-layer capacitors was prepared from humic acids by KOH activation at 700 ℃ for 1 hour and lower KOH/carbon ratios( below 1).The oxygen content and pore structure characteristics of as-prepared carbons were performed by elemental analyzer and N_2 adsorption apparatus.The electrochemical performances were monitored by galvanostatic charge-discharge,cyclic voltammetry and leak current in a two-electrode system with 3 mol/L KOH solution as the electrolyte,respectively.The results show that the four carbons possess high oxygen content( above 20%) and hierarchical pore size distribution mainly including the micropores from 0.5 nm to 2.0 nm and the mesopores from 3.5 nm to 4.6 nm.With the KOH/carbon ratios increasing,the oxygen content,specific surface area,total pore volume,micropore volume and mesoporosity of the carbons all increase,and can reach at 26.67%,878 m~2/g,0.66 cm~3/g,0.407 cm~3/g and 62.1%,respectively. The micropores are mainly generated from the release and decomposition of volatile and oxygen-containing functional groups during the activation and pyrolysis of humic acid.And the high mesoporosity is mainly due to the pore reaming effect of potassium.The four carbon materials exhibit good charge/discharge reversibility and typical double layer capacitive characteristics,and the specific capacitance and capacity retention ratio can reach up to 256 F/g and 84% with a low leak current less than 0.015 m A.All carbon materials have reasonable pore size distribution and rich oxygen-containing functional groups,which is beneficial to shorten the diffusion path of electrolyte ions in the electrode material,improve the wettability of electrode material and electrolyte and reduce the diffusion resistance,which suggesting that the hierarchical porous carbons are ideal electrode materials for electrochemical capacitors.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 2032K]

Study on the preparation of polyaluminium chloride from coal gasification residue
HU Wenhao;ZHANG Jianbo;LI Shaopeng;LI Zhanbing;SUN Zhigang;LI Huiquan;Key Laboratory of Green Process and Engineering,Institute of Process Engineering,Chinese Academy of Science;National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology;University of Chinese Academy of Science;Sinopec Ningbo Technology Research Institute Co.,Ltd.;
In china,the production of coal gasification residue( CGR) is huge while comprehensive utilization is very low.Storage and landfill are main ways to dispose CGR,which has been a threat to environment and throws burdens onto economy.The demand of large-scale treatment and resource conversion of CGR is urgent.The purpose of this paper is to use leach acid of CGR to produce polyaluminium chloride.The influence of calcium aluminate dosage,polymerization temperature,polymerization time and cycle number of acid leaching on the performance of production were highly investigated.Results suggest that,the concentration of Al~(3+)in the acid leach solution can reach 28 g/L and the content of aluminum oxide can be 5.28% when cycle number of acid leaching reaches 4.Using aluminum-rich acid solution as raw material to product polyaluminium-chloride,the optimal polymerization conditions are reaction temperature 80 ℃,reaction time 120 min,and 12.50 g calcium aluminate powder per 50 m L the leach acid solution.Under these conditions,as-prepared polyaluminium-chloride contains 10%-11% Al2 O_3 with basicity of 44%-50% and the content of heavy metal,such as Pb,Cr,As,is very low.The final product can reach the requirement of GB/T 22627—2014 for the preparation of water treatment agent.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 2614K]

Study on advanced treatment of coking wastewater by coke powder adsorption
YAN Bohua;LI Xilong;JIANG Qing;XU Long;MA Xiaoxun;International Scientific and Technological Cooperation Base for Clean Utilization of Hydrocarbon Resources;Chemical Engineering Research Center of the Ministry of Education for Advance Use Technology of Shanbei Energy;Collaborative Innovation Center for Development of Energy and Chemical Industry in Northern Shaanxi;Shaanxi Research Center of Engineering Technology for Clean Coal Conversion;Xi'an Engineering Laboratory for Energy Efficient Clean
In order to solve the unqualified discharge standard of coking plant wastewater after conventional biochemical treatment,the coke powder produced by the coking plant was used in the advanced treatment of biochemical effluent in the wastewater treatment process of coking plant.The effects of coke powder dosage,solution p H value,particle size,and adsorption time on the removal rates of COD and chroma in coking wastewater were investigated.The optimal process plan was obtained by orthogonal experimental design,and the morphology and surface element distribution of coke powder before and after use were analyzed by SEM-EDX. The results show that the removal rates of COD and chroma increases significantly when the coke powder dosage increases from 40 g/L to 120 g/L.To further increase the coke powder dosage,the increase of the removal rates of both COD and chroma are slow down and then remained stable when the dosage of coke powder is more than 200 g/L.When the size of coke powder exceeds 5-6 mm,the removal rates of COD and chroma are stable,and the removal rates of both reach the maximum with solution p H value of 8. Besides,the removal rates of COD and chroma improve remarkably when the adsorption time prolonges from 0.5 h to 2.5 h and then will be stable as the adsorption time further increased.The optimum design of dosage of coke powder,the diameter of coke powder,the p H value and the adsorption time are 200 g/L,5 mm,8 and 3 h,respectively,based on the L18( 37) orthogonal design.The results of several parallel experiments in the optimized conditions show that the average removal rates of COD and chroma are 66.8%,and 71.2%,respectively.The SEM-EDX characterization results show that the pore size of coke powder is large,and there are large cracks on the surface before adsorption.While the pore size and cracks are obviously reduced due to the adhesion of abundant substances to the surface and pore channel of coke powder after adsorption.The relative contents of carbon,oxygen,sulfur,and nitrogen on the surface of coke powder increase greatly,indicating the good performance of coke powder on adsorption organic matter and part of sulfur and nitrogen-containing substances in coking wastewater.
2019 01 v.25;No.119 [Abstract][OnlineView][HTML全文][Download 2809K]

2019 01 v.25;No.119 [Abstract][OnlineView][Download 75K]

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2019年01期目次

Research progress of the effects of Ca-based sorbents on the NO_x reaction in circulating fluidized bed boilers

Research progress on the briquette prepared from pretreated biomss

Feed coal reactivity evaluation,process intensification and environmental impact of entrained-flow coal gasification

Application of molecular dynamics simulation in coal structure and related fields

Research on plasma gasification technology of coal

Precise separation and resource utilization of coal gasification fly ash

Research progress on volatiles and sulfur removal during low temperature pyrolysis of coal

Technical progress and industrialization status of coal to fuel oil in China

Research progress on flue gas water recovery technology in wet FGD

Research progress on biodegradation technology of residual agents in mineral processing wastewater

Synergistic adsorption of inorganic salt and surfactants on the surface of low rank coal

Study on the separation technology for high efficiency power coal

Effects of Ca and occurrence forms on transformation behavior of nitrogen during coal pyrolysis

CO₂ gasification properties of coal chars and fine chars from fluidized bed gasification of Shenmu coal

Effect mechanism of calcium-bearing and iron-bearing minerals on slag blockage of pulverized coal gasification

Numerical simulation and analysis of reductive atmosphere in air staged pulverized coal combustion

Effect of flue gas physical properties on convective heat transfer of coal-fired boiler in O₂/CO₂ atmosphere

Operation performance and economic benefit on chemical agglomeration of fine particles from a 300 MW coal-fired power plant boiler

Research on removal of elemental mercury by fulvic acid carbon-based sorbents loaded with silver

Study on conversion process by mild supercritical thermal extraction coupled with carbonization technology of Datong coal

Electrochemical performance of hierarchical porous carbons prepared from coal based humic acid

Study on the preparation of polyaluminium chloride from coal gasification residue

Study on advanced treatment of coking wastewater by coke powder adsorption