Structural properties of residual carbon in coal gasification fine slag and their influence on flotation separation and resource utilization:A review

Coal gasification fine slag(FS)is a typical solid waste generated in coal gasification.Its current disposal methods of stockpil-ing and landfilling have caused serious soil and ecological hazards.Separation recovery and the high-value utilization of residual carbon(RC)in FS are the keys to realizing the win-win situation of the coal chemical industry in terms of economic and environmental benefits.The structural properties,such as pore,surface functional group,and microcrystalline structures,of RC in FS(FS-RC)not only affect the flotation recovery efficiency of FS-RC but also form the basis for the high-value utilization of FS-RC.In this paper,the characteristics of FS-RC in terms of pore structure,surface functional groups,and microcrystalline structure are sorted out in accordance with gasification type and FS particle size.The reasons for the formation of the special structural properties of FS-RC are analyzed,and their influence on the flotation separation and high-value utilization of FS-RC is summarized.Separation methods based on the pore structural characterist-ics of FS-RC,such as ultrasonic pretreatment-pore-blocking flotation and pore breaking-flocculation flotation,are proposed to be the key development technologies for improving FS-RC recovery in the future.The design of low-cost,low-dose collectors containing polar bonds based on the surface and microcrystalline structures of FS-RC is proposed to be an important breakthrough point for strengthening the flotation efficiency of FS-RC in the future.The high-value utilization of FS should be based on the physicochemical structural proper-ties of FS-RC and should focus on the environmental impact of hazardous elements and the recyclability of chemical waste liquid to es-tablish an environmentally friendly utilization method.This review is of great theoretical importance for the comprehensive understand-ing of the unique structural properties of FS-RC,the breakthrough of the technological bottleneck in the efficient flotation separation of FS,and the expansion of the field of the high value-added utilization of FS-RC.

Progress in Research on 20 MWt Coal-fired MHD Slagging Combustor

In this paper a brief introduction on design features,process of hot-fire check out testsand typical testing results of a 20 MWt coal-fired MHD slagging combustor is presented.Onthe basis of the testing results we conclude that all the design requirements of the combustorare satisfied.Analysis on the experimental results is also made.The reasons that causeslower rate of slag rejection are discussed,and the ways of raising slag rejection rate are con-sidered.

Occurrence,leaching behavior,and detoxification of heavy metal Cr in coal gasification slag

Coal gasification slag(CGS)is a type of solid waste produced during coal gasification,in which heavy metals severely restrict its resource utilization.In this work,the mineral occurrence and distribution of typical heavy metal Cr in CGS is investigated.The leaching behavior of Cr under different conditions is studied in detail.Acid leaching-selective oxidation-coprecipitation method is proposed based on the characteristics of Cr in CGS.The detoxification of Cr in CGS is realized,and the detoxification mechanism is clarified.Results show that Cr is highly enriched in CGS.The speciation of Cr is mainly residual fraction(74.47%-86.12%),which is combined with amorphous aluminosilicate.Cr^(3+)and Cr^(6+)account for 90.93%-94.82%and 5.18%-9.07%of total Cr,respectively.High acid concentration and high liquid-solid ratio are beneficial to destroy the lattice structure of amorphous aluminosilicate,thus improving the leaching efficiency of Cr,which can reach 97.93%under the optimal conditions.Acid leaching-selective oxidation-coprecipitation method can realize the detoxification of Cr in CGS.Under the optimal conditions,the removal rates of Fe^(3+)and Cr^(3+)in the leaching solution are 80.99%-84.79%and 70.58%-71.69%,respectively,while the loss rate of Al^(3+)is only 1.10%-3.35%.Detoxification slag exists in the form of Fe-Cr coprecipitation(Fe_(1-x)Cr_xOOH),which can be used for smelting.The detoxification acid leaching solution can be used to prepare inorganic polymer composite coagulant poly-aluminum chloride(PAC).This study can provide theoretical and data guidance for detoxification of heavy metal Cr in CGS and achieve resource utilization of coal gasification solid waste.

Cause Analysis and Countermeasure of Gypsum Rain in Coal-fired Power Plants

Focusing on the phenomenon of gypsum rain while wet desulphurization(WFGD) were adopted in coal fired power plant without GGH, the paper studied and put forward the solutions : (1) desulfurization facilities related equipment modification;(2) optimal operation of existing desulfurization facilities.

INTRODUCTION TO INCONEL ALLOY 740: AN ALLOY DESIGNED FOR SUPERHEATER TUBING IN COAL-FIRED ULTRA SUPERCRITICAL BOILERS

Chinese utilities as well as those worldwide are facing increased demand for additional electricity, reduced plant emissions and greater efficiency. To meet this challenge will require increasing boiler temperature, pressure and coal ash corrosion resistance of the materials of boiler construction of future coal-fired boilers. A new nickel-based tube alloy, INCONEL^R alloy 740, is described aiming at meeting this challenge. Emphasis will be on describing the alloy＇ s mechanical properties, coal-ash and steam corrosion resistance. Microstructural stability as a function of temperature and time is addressed as well as some of the early methodology em- ployed to arrive at the current chemical composition.

Mercury Emission From Coal-fired Power Plants in China

燃煤是最大的人为汞排放源之一，燃煤电厂的汞排放控制问题也越来越为人们所关注。该文将目前公布的中国电厂的汞排放数据进行筛选汇总，得到18个电厂的汞排放数据，通过对比和分析，总结出了符合我国燃煤电厂特点的一般性汞排放规律。结果表明：与美国煤种相比，我国的燃煤具有低氯、高灰的特性，这不利于汞的排放控制；循环流化床燃烧可能会因燃尽率的不同而较煤粉炉燃烧易获得较高的Hgp；空气污染控制设备的使用能够有效地减少汞排放，选择性催化还原＋静电除尘器／布袋除尘器＋石灰石-石膏湿法脱硫（SCR＋ESP／FF＋WFGD）组合的平均脱汞率可达71．48％；SCR的大规模应用可能会将汞大量转移到飞灰和脱硫石膏中，带来二次污染的问题。

Progress and prospects of innovative coal-fired power plants within the energy internet

The development of electrical engineering and electronic, communications, smart power grid, and ultra-high voltage transmission technologies have driven the energy system revolution to the next generation: the energy internet. Progressive penetration of intermittent renewable energy sources into the energy system has led to unprecedented challenges to the currently wide use of coal-fired power generation technologies. Here, the applications and prospects of advanced coal-fired power generation technologies are analyzed. These technologies can be summarized into three categories:(1) large-scale and higher parameters coal-fired power generation technologies, including 620/650/700 oC ultra-supercritical thermal power and double reheat ultra-supercritical coal-fired power generation technologies;(2) system innovation and specific, highefficiency thermal cycles, which consist of renewable energy-aided coal-fired power generation technologies, a supercritical CO_2 Brayton cycle for coal-fired power plants, large-scale air-cooling coal-fired power plant technologies, and innovative layouts for waste heat utilization and enhanced energy cascade utilization;(3) coal-fired power generation combined with poly-generation technologies, which are represented by integrated gasification combined cycle(IGCC) and integrated gasification fuel cell(IGFC) technologies. Concerning the existing coal-fired power units, which are responsible for peak shaving, possible strategies for enhancing flexibility and operational stability are discussed. Furthermore, future trends for coal-fired power plants coupled with cyber-physical system(CPS) technologies are introduced. The development of advanced, coal-fired power generation technologies demonstrates the progress of science and is suitable for the sustainable development of human society.

Feasibility Analysis on the Integrated Application of Solar Energy, Biogas, Coal-fired Boiler and Radiant Floor Heating for Rural Residence

The feasibility of adopting a balanced energy mix mode (domestic solar energy, biogas, coal-fired boiler and radiant floor heating) was proposed. Taking a typical rural residence in Zhengzhou City for example, the study through theoretical analysis and calculation showed that such a balanced energy mix is an economic way and efficient in saving energy and reducing air pollution, and elaborated the theoretical feasibility of popularizing such a heat supply mode in rural areas.

Optimization of an Existing Coal-fired Power Plant with CO²Capture

Nowadays, the worsening environmental issue caused by CO2 emission is greatly aggravated by human activity. Many CO2 reduction technologies are under fast development. Among these, monoethanolamine (MEA) based CO2 capture technology has been paid great attention. However, when connecting the CO2 capture process with a coal-fired power plant, the huge energy and efficiency penalty caused by CO2 capture has become a serious problem for its application. Thus, it is of great significance to reduce the related energy consumption. Based on an existing coal-fired power plant, this paper proposes a new way for the decarburized retrofitting of the coal-fired power plant, which helps to improve the overall efficiency of the power plant with less energy and efficiency penalty. The decarburized retrofitting scheme proposed will provide a new route for the CO2 capture process in China.

Development of 600 MW Class Coal Fired Boilers in China

This article introduces the present status anddevelopment of 600 MW class boilers in China. The statisticaldata indicate that most 600 MW generating units experiencedrelatively length" growing up" period. In this period, unitscould not operate stably , their unplanned outage times weremany and durations long, and availabilities low. On the basis oftesting and research and the summing-up of practice, it wasindicated slagging in the furnace, deviation of tine gas energy atthe exit of furnace, and overheating bursting of superheater andreheater etc, endangering the safety and economics ofoperation,main problems could be completely alleviated oravoided through design and type selection of boiler furnace andburners, coal characteristics and coal handling management,and optimization management of operation conditions etc.

The Effects of SO_3 in Flue Gas on the Operation of Coalfired Units and Countermeasures

There exists a certain amount of SO_3 in flue gas discharged from coal-fired power plants. With the operation of the selective catalystic reduction( SCR) denitrification system,SO_3 concentration in the flue gas increases,which will lead to fouling,erosion and plugging of downstream equipment. In this study,the main effects of SO_3 on the safety,stability and efficiency of units were analyzed,and measures to control SO_3 were proposed.

The flue dust emission of the coal fired power plants in Zhejiang Province attains target

According to statistics, the average dust collection efficiency of flue gas emission in the large and medium- sized power plants in Zhejiang Province at present has attained higher than 97% which surpasses the 95% standard as stipulated by the Ministry of Electric Power. The dust collection efficiency of the Beilungang Power Plant has already attained 99.92%. In recent years, Zhejiang Electric Power Corporation has stipulated that all the newly constructed generating units shall be equipped with high efficiency electrostatic precipitator (ESP) while the existing power plants shall speed up their renovation work for their dust collectors. In combination with the fourth stage project of the Taizhou Power Plant, the improvement work of the dust

OVERVIEW OF ENVIRONMENTAL ASSESSMENT FOR CHINANUCLEAR POWER INDUSTRY AND COAL－FIRED POWER INDUSTRY

ＯＶＥＲＶＩＥＷＯＦＥＮＶＩＲＯＮＭＥＮＴＡＬＡＳＳＥＳＳＭＥＮＴＦＯＲＣＨＩＮＡＮＵＣＬＥＡＲＰＯＷＥＲＩＮＤＵＳＴＲＹＡＮＤＣＯＡＬ－ＦＩＲＥＤＰＯＷＥＲＩＮＤＵＳＴＲＹＺｈａｎｇＳｈａｏｄｏｎｇ（张少东）；ＰａｎＺｉｑｉａｎｇ（潘自强）ａｎｄＺ...

Development of Carbon Dioxide Capture Technologies in Coal-Fired Power Plants

With a particular reference to China Huaneng Group's practices in CO_2 capture, this article presents a brief ing on the current development of CO_2 capture technologies in coal-fired power plants both in China and abroad. Sooner or later, the integration of CO_2 capture and storage (CCS) facility with coal-fired power plant will be inevitably put on the agenda of developers.

System Performance and Pollution Emission of Biomass Gas Co-Firing in a Coal-Fired Boiler

To reduce greenhouse gases emission and increase the renewable energy utilization portion in the world, the biomass gasification coupled with a coal-fired boiler power generation system is studied. It is a challenge to achieve optimum performance for the coupled system. The models of biomass gasification coupled with co-firing of coal in a boiler have been established. A comparative study of three kinds of biomass (Food Rubbish, Straw and Wood Pellets) has been done. The syngas produced in a 10 t/h gasifier is fed to a 330 MWe coal-fired boiler for co-combustion, and the co-firing performances have been compared with pure coal combustion case under the conditions of constant boiler load. Results show that co-firing decreases the furnace combustion temperature and raises the flue gas temperature for Food Rubbish and Straw, while, flue gases temperature decrease in case of Wood Pellets. At the same time NOx and SOx emissions have reduced. The system efficiencies at constant load for Food Rubbish, Straw and Wood Pellets are 83.25%, 83.88% and 82.56% when the optimum conditions of gasification and co-firing process are guaranteed.

Study on CO_2 Emission Reduction from Chinese Coal-Fired Power Plants Between 1993 and 2010

Based on the Chinese thermal coal and power generation data,such as ultimate analysis,proximate analysis,low heat value(LHV)on as received basis,power generation volume,thermal coal consumption volume and net coal consumption rate,several mathematical models for calculating CO 2 reduction by Chinese coal-fired power plants are established.Calculations of the CO 2 emission factor(CEF),the CO 2 emission volume and reduction volume are made according to these models.The calculation results reveal that between 1993 and 2010,the CO 2 emission volume reached 31.069 Gt,reduced by 0.439 Gt,averaging 28.83 Mt each year.