Clean Coal Technology

2019年06期目次

Study on the emission characteristics of volatile organic compounds(VOCs)from coal-based ammonia plant
LIU Dan;ZHANG Xin;ZHANG Fenglian;SUN Yonggang;WANG Lu;HAO Zhengping;Caofeidian District Branch,Tangshan Bureau of Ecological Environment;National Engineering Laboratory for VOCs Pollution Control Material & Technology,University of Chinese Academy of Sciences;Research Center for Environmental Material and Pollution Control Technology,University of Chinese Academy of Sciences;State Key Laboratory of High-efficiency Coal Utilization and Green Chemical Engineering,Ningxia University;CNPC Fuel Oil C
It lays a foundation for finding out the VOCs emission sources in the production process of synthetic ammonia industry and accounting the industrial emissions. In this paper,the emission characteristics of synthetic ammonia industrial in coal chemical industry were studied. The research included the organized emission in the production process,the workshop emission and the unorganized emission in the plant boundary. The emission was estimated by the emission factors. The results show that the aromatics and oxygen-containing organics are the main emissions of synthetic ammonia. 36,19,26,21 and 20 VOCs species are detected in the sulfur recovery process,urea synthesis process,CO_2 flash gas in low-temperature methanol washing process,the exhaust gas of CO_2 flash and washing tower,respectively.Benzyl chloride,isopropanol and 2-butanone are the characteristic pollutants of VOCs emission in synthetic ammonia. A large amount ofbenzyl chloride produced in the production process may be converted from aromatic compounds with α-hydrogen side bond. the unorgan-ized emission characteristics of synthetic ammonia workshop are consistent with the emission characteristics of the corresponding productionprocess. 19,32 and 15 VOCs species are detected in gasifier workshop,urea packaging workshop and phenol Ammonia Recovery Workshoprespectively. The VOCs discharged from the gasifier workshop are mainly benzyl chloride,accounting for 23.16%,the urea packaging work-shop is mainly 2-butanone,ethyl acetate,1,2,4-trimethylbenzene,accounting for 49.58%,the phenol ammonia recovery workshop ismainly vinyl acetate,accounting for 56.60%,which is related to the auxiliary solvent used in the process of phenol ammonia recovery. Thecharacteristics of VOCs at unorganized monitoring points in the plant boundary of synthetic ammonia are:aromatic hydrocarbon > halogena-ted hydrocarbon > oxygenated organic matter > alkane,which is consistent with the emission characteristics of production process corre-sponding to each monitoring point.The total emission factors of synthetic ammonia process calculated by emission factor method are 75.02 g/tsynthetic ammonia,13.66 g/t synthetic ammonia with sulfur recovery,14.45 g/t synthetic ammonia with urea synthesis,21.42 g/t syntheticammonia with CO_2 flash gas,13.01 g/t synthetic ammonia with CO_2 flash exhaust gas and 12.49 g/t synthetic ammonia with tail gas scrub-ber vent gas. According to this emission factor,the VOCs emission of a typical coal based synthetic ammonia production process in InnerMongolia was about 22.51 t in 2015.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 5072K]

Analysis and accounting of VOCs emission sources in modern coal chemical plants
ZHANG Kai;LIU Shuyu;XIANG Shan;ZHANG Yanbin;CHEN Mengyuan;School of Chemistry & Environmental Engineering,China University of Mining and Technology(Beijing);CNN Energy;
VOCs emission accounting is the basis of VOCs Pollution Prevention and control. At present,no relevant accounting guideline and specification has been issued in the field of coal chemical industry. Referring to "Guidelines for VOCs Pollution Source Investigation in Petrochemical Industry",in this paper,the VOCs emission source of a coal-to-olefin project in Northeast China was identified and cal-/formula and experience factor. The similarities and differences of accounting results between coal chemical industry and petrochemical industry were compared.The contribution rate of VOCs emission from different sources and the internal emission of sources were quantified and analyzed. The purpose of this paper is to provide theoretical and practical basis for VOCs emission accounting and source term analysis of modern coal chemical industry,and provide reference for the follow-up VOCs management and control. The results indicate that there/a. The contributions of VOCs emission sources in the coal-to-olefin project are listed as follows: wastewater collection and treatment 29. 46%,circulating cooling water 27.30%,tank 17.52%,equipment leak 16.66%,stationary combustion 5.53%,process vents 3.13%,loading0.39%. Compared with the traditional petrochemical industry and the coal chemical industry,the largest pollution source of the former is usually the storage tank,while the main pollution source of the latter is wastewater collection and treatment and circulating cooling water,in which the wastewater collection process accounts for 94.67% of the wastewater collection and treatment. Olefin separation unit and 2-PH unit are the main VOCs leakage devices,and one end of the open valve or pipeline is the main leakage sealing point. Methanol tank area is the key leakage area of tanks.Coal chemical enterprises should strengthen the closed control of the two key source items of wastewater collection and treatment and circulating cooling water,and set up waste gas collection and centralized treatment devices for targeted treatment of different characteristics of pollution.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 2051K]

Research on on-line monitoring system standard of VOCs emission in modern coal chemical industry
WANG Jianbing;GUO Dongzhi;ZHOU Hao;ZHANG Yanbin;JIA Jianli;ZHU Tao;ZHANG Liping;School of Chemical and Environmental Engineering,China University of Mining and Technology(Beijing);
With the rapid growth of modern coal chemical industry,a large number of volatile organic compounds(VOCs) emitted from its production processes will pose multiple environmental effects on the currentair quality. At present,the knowledge about the emission of VOCs from the production process of modern coal chemical projects is not enough to meet the management and decision-making needs of VOCs pollution control. To overcome this difficulty,the method of pollution source intensity calculation was adopted to compare and analyze the difference of the VOCs emission characteristics between modern coal chemical industry and petrochemical industry. Also the literature analysis and field research was conducted to analyze the weak links of VOCs prevention and control in modern coal chemical enterprises and explore the methods to overcome the main obstacles of pollution prevention and control based on the mature experience of VOCs pollution control obtained in petrochemical industry. It is found that the VOCs emission during gathering,transportation and treatment of waste water is the biggest emission source in modern coal chemical enterprise,which is obviously different with the VOCs emission characteristics of petrochemical enterprise. Unclear emission base is the main obstacle of VOCs pollution control in modern coal chemical industry. It is helpful to improve the VOCs pollution control level of modern coal chemical industry by establishing performance specification of VOCs continuous emission monitoring system to guide the on-line monitoring for VOCs emission from stationary pollution source. Based on the VOCs monitoring technologies at home and abroad,and the technical specifications of China's on-line monitoring of fixed pollution source emissions,an on-line monitoring technology system of fixed pollution source VOCs emissions in China's modern coal chemical industry was studied and established,and the requirements for system component and structure,technical performance,monitoring station,installation,debugging and test for technical indicator,acceptance,daily operation management,quality assurance,data auditing and treatment and other aspects of the system were elaborated. The study of the system standard provided a reference for the establishment of VOCs emission monitoring system in China's coal chemical industry.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 184K]

Research progress on VOCs emission characteristics and control technology in coking industry
HU Jiangliang;ZHAO Yong;WANG Jiancheng;MIAO Maoqian;Key Laboratory of Coal Science and Technology,Ministry of Education and Shanxi Province,Taiyuan University of Technology;Shanxi Keling Catalytic Purification Technology Development Co.,Ltd.;
Volatile organic compounds(VOCs) are important precursors of air pollutants,especially PM2.5 and O3,which not only damage the environment,but also threaten human health. China is the largest country of producing coke and the coke output reached 438 million tons in 2018. Great attention has been paid to the treatment of pollutants produced in this production process. And after comprehensive treatment in recent years,the treatment of pollutants has gradually transitioned from conventional pollutants to unconventional pollutants,and from organized emissions(sulfur,nitrogen compounds) to unorganized emissions(VOCs,NH3). Therefore,as a typical representative of unconventional pollutants in the coking industry,it is great significant to study the integration characteristics of their emission characteristics and treatment of VOCs. In this paper,the VOCs emission nodes in coking process were described in detail,and it was pointed out that the chemical recovery and tar processing are the key processes of VOCs emission. According to the principle of production and the form of emission,the emission modes of VOCs were classified. The exhaust gas properties and total emission calculation methods of each section were further summarized and compared,and the four characteristics of VOCs emission in coking industry were clarified:many emission nodes,great difference,complex components,heavy odor. Based on the study of emission characteristics,the possibility and development trend of application of various treatment technologies in coking industry were analyzed from two aspects of with/without organization,and the basis for selecting the best applicable technology for pollution control was given. Finally,taking the VOCs treatment technologies of TISCO coking and Shaanxi Heimao coking as examples,the two application of VOCs treatment technologies in coking plant were introduced and the VOCs emission characteristics of coking industry in depth were analyzed,which provided scientific and reliable technical support for the formulation of VOCs control strategy of coking industry based on improving air quality.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 2823K]

Research on deep treatment and control of VOCs in coking industry
LI Bing;HE Shuo;ZHU Wenxiang;HONG Xiaowei;CHEN Jianjun;PENG Yue;MA Yongliang;LI Junhua;Jiangsu Zhongchuang Qingyuan Technology Co.,Ltd.;National Engineering Laboratory for Flue Gas Pollutants Control Technology and Equipment,Tsinghua University;Shanghai Environmental Protection Co.,Ltd.;
Coking industry,as an important part of coal chemical industry,plays an important role in metallurgy,chemical industry and other fields. With the continuous and indepth promotion of VOCs emission reduction action in China,it has become an inevitable trend for the deep comprehensive treatment of VOCs in coking industry. In this paper,the source and composition of VOCs in coking industrywas briefly described. The applicable treatment technology of waste gas from coking production and coking sewage treatment system was discussedin the form ofcase study. The following process route was clarified:the "oil washing + water washing + steam heating + coke oven combustion" treatment of waste gas in cold drum,desulfurization,ammonium sulfate sections of the chemical production area,the "negative pressure recovery" treatment of waste gas in crude benzene section,the "cryogenic condensation recovery + activated carbon adsorption vacuum desorption + loading steam balance" recycling technology for gas exhausted from benzene storage tank size breathing and loading,and the "acid washing + alkaline washing + biofilter + coke adsorption" treatment of waste gas from sewage treatment system.It is of great significance for improving the level of air pollution prevention and improving the quality of regional atmospheric environment by the deep comprehensive treatment of coking VOCs.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 3951K]

Study on odorous VOCs treatment from wastewater treatment plant for coal liquefaction enterprises
WANG Yongyi;ZHANG Mingxiang;SU Bingjie;Qingdao Goldhisun Environment Protection Equipment Co.,Ltd.;
In order to control odorous VOCs air emission from wastewater treatment plant for coal liquefaction project,the sewage tanks with high concentration at each openingsuch asthe oil separator,floatation tank,coal gasification wastewater pretreantment tank,equalization tank,hydrolysis-acidification tank,Intermediate sedimentation tank were sealed. According to the conditions of each treatment tank,the FRP arched plateand framed structure membrane coverwere adopted. Thewastegaswas collected and transported with PRP ventilation pipeline,and treated through prewashing-biotrickling filter-granular activated carbon adsorption in sequenceand finally discharged through15 m high exhaust funnel. The results show that after treatment the offgas meets the design requirements and the national air pollutant emission standard.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 592K]

Research progress on the effect of low-NO_x combustion on furnace sulfur fixation in the CFB boiler
HAO Yanhong;MENG Jiangtao;WANG Jing;YANG Fengling;CHENG Fangqin;Shanxi 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;
With the constantimproving requisition of flue gas pollutants emission in thermal power plants, the low-nitrogen( low-NO_x) combustion technology is used in circulating fluidized bed(CFB) boilers to reduce the generation of NOx during the combustion phase. However,withthe use of the low-NOx combustion technology,the oxygen content in the local atmosphere especially in the dense phase zone decreases by 1% to 4%,and the reducing atmosphere such as CO increases by 1% to 2%. Desulfurizationreaction can show different reaction paths under different oxygen concentrations and reducing atmosphere conditions,which will affect the rate of overall sulfurfixing rate and the generation of different sulfur-fixing products,leading to the difference of the final sulfur fixation rate. Therefore,the low nitrogen combustion condition in the furnace definitively willimpact the process of calcium basedsulfur fixation.In order to clarify the influence of the low-NOxcondition on the calcium-based sulfur fixation in furnace and decrease the SO_2 and NOx emission at the same time,thus realize the coupling of low-NOxcombustion technology and calcium-based sulfur-fixing technology in CFB boiler,The influence of low nitrogen combustion reaction conditions on the calcium based sulfur fixation process in CFB boiler was reviewed in this paper.. The effects of reducing atmosphere and oxidation-reduction alternating atmosphere conditions on the calcination of sulfur-fixing agent,desulfurization and the decomposition and transformation of sulfur-fixing products were described respectively. The results show that thechange of CO_2 concentration has anadverse effect on the calcination of CaCO_3. The partial pressure of CO_2 in the atmosphere will directly weaken the degree of calcination reaction. However,there are no reports about the influence of the O_2 and CO concentration change on the CaCO_3 calcination.Theoretically,it could be inferred that it scarcely has effect on the calcination,but it needs further experimental proof. The current researchresults show that the process of sulfur fixation in the furnace is complicated under the oxidation-reduction alternating atmosphere.As the oxygen disappearing,the sulfur fixation rate decreases by about 20%. With the increase of CO concentration in the reducing atmosphere,the sulfur fixation rate further decreases.With the enhancement of reducing atmospheres such as CO content,the stability and decomposition temperature of the sulfur-fixing product CaSO_4 decreases,while the stability of CaS increases. When the atmosphere and temperature conditions are reasonably controlled to form sulfur-fixing products with CaS as the core and CaSO_4 as the shell,the calcium utilization rate and sulfur-fixing efficiency can be improved. In conclusion,the influence of the low-NOx condition on the desulfurization process is not deterministic. Meanwhile,due to the complexity of sulfurization reaction and the instability of sulfur fixing products,so far,there is no optimum operation condition suggestion about the best matching of different sulfur fixation agents with reaction temperature and reaction atmosphere. Therefore,it is necessary to further explore the sulfur fixation reaction mechanism of calcium based sulfur fixation agents such as limestone and carbide slag in different oxygen concentration atmosphere and reducing atmosphere to clarify the influence of low nitrogen combustion conditions on calcium based sulfur fixation process,and finally the ideal operating suggestion for the combination of low-NOx combustion and calcium-based sulfur fixation in furnace is obtained,which would provide a reliable theoretical basis for actual production.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 547K]

Denitration mechanism and engineering application progress of gas fuel reburning
WANG Pengtao;WANG Naiji;LIANG Xing;NIU Fang;China Coal Research Institute Company of Energy Conservation;State Key Laboratory of High Efficient Mining and Clean Utilization of Coal Resources;National Energy Technology & Equipment Laboratory of Coal Utilization and Emission Control;
Gaseous fuel reburning denitrificationtechnology can effectively reduce the initial nitrogen oxide emission of the boiler. In this paper,aiming at NO_x reduction mechanism of gaseous fuel reburning and its application status in Engineering,the effects of five factors on the reburning effect were analyzed. The typical demonstration projects and their operation effects of gaseous fuel reburning technology in boiler retrofit were summarized. The research at home and abroad shows that the essence of denitrification by gaseous fuel reburning is that hydrocarbons decompose by heat to produce related groups,which collide with NO_x to generate corresponding nitrogen-containing intermediates. At the last,the nitrogen-containing intermediates react with reducing groups to convert part of NO_x into N_2. Specifically,CH_3 intermediate is mainly generated in the process of methane reburning,and the reduction reaction between CH_3 and NO is the key to denitrification,while HCCO intermediate is generated in the process of multi carbon hydrocarbon fuel reburning,and the reduction reaction with NO is the core of reburning. The results show that there are proper ranges of reburning zone residence time,excess air coefficient and temperature during reburning. What′s more,the reburning fuel composition and the mixing characteristics of reburning fuel and NO_x also have a significant effect on the reburning effect. Increasing the residence time of reburning fuel in reburning zone is not only conducive to NO_x reduction,but also conducive to the burnout of reburning fuel. However,the too long residence time in reburning zone will not increase the NO_x reduction rate,but will reduce the combustion efficiency of fuel. The best residence time of reburning zone is 0.6-1.1 s,and the further increase of residence time will not increase denitrification efficiency.The excess air coefficient in the reburning zone has a significant effect on the reburning reduction efficiency and burnout characteristics. The best excess air coefficient in reburning zone is 0.85-0.90.The high temperature of reburning zone is conducive to improving the denitrification efficiency of reburning fuel,and the optimal denitrification temperature in reburning zone is 1 000-1 100 ℃.The composition of reburning fuel is different,and the reduction effect of NO_x is different.The reburning denitrification of hydrocarbon is closely related to its thermal decomposition. Under the same reburning condition,the reburning denitrification performance is completely related to its heating classification rate. The research shows that the presence of multi carbon hydrocarbon can significantly enhance the reduction effect of reburning gas mixture,and the presence of tar and coal char can have obvious catalysis effect on the NO reduction. In addition,the denitrification process of gas fuel reburning is not only affected by the difficulty of chemical reaction,but also related to the diffusion process of reburning fuel in the high NO_x concentration area. Strengthening the mixing characteristics of reburning fuel and NO_x in the reburning area is also conducive to improving the denitrification efficiency.The United States,European Union,Japan and other countries started earlier and achieved remarkable results in the research and engineering demonstration projects of power plant boiler reburning and denitrification. The demonstration projects of natural gas reburning technology transformation of Sichuan Jiangyou Power Plant also proved the feasibility and economy of reburning and denitrification.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 520K]

Status and prospect of coal chemical industry standardization in China
WANG Qinzhuo;YANG Yongzhong;Shaanxi Coal Chemical Industry Technology Research Institute Co.,Ltd.;
There is abundant coal resource in China.Modern coal chemical technology is vital for energy security in our country.The traditional coal chemical industry is dominated by coking and synthetic ammonia. The modern coal chemical industry takes coal gasification and coal liquefaction as the core,including coal to natural gas,coal to oil,coal to olefins,and coal to aromatics and so on. The perfect standardization system is conducive to the further development of coal chemical industry.In this paper,the research on the standardization of coal chemical industry was introduced and the existing and upcoming national and branch standards were reviewed.The current standardization of some important fields in modern coal chemical industry was introduced in 9 main fields including coal gasification,coal indirect liquefaction,coal direct liquefaction,coal to natural gas,coal to methanol,coal to olefin,coal to aromatics,coal to glycol,and coal to dimethyl ether. Moreover,in this paper,some suggestions were put forward for the development of some new standards. The standard system of coal chemical industry consists of four categories:basic standards,management standards,product standards and testing standards. As of January 2019,according to incomplete statistics,the 229 national and branch standards including 5 basic standards have been issued in coal chemical industry. In the traditional coal chemical industry,154 standards have been issued and 3 standards will be implemented after January 2019. In the modern coal chemical industry,70 standards have been issued and 12 standards will be implemented after January 2019. It is found that in the traditional coal chemical industry,standards cover a wide range of areas. However,the revision and update of the standards should be accelerated to speed up the elimination of backward technologies and help resolve overcapacity. Although the standard work of modern coal chemical industry has made great progress in recent years,the main problem lies in that the issued and implemented standards mainly focus on inspection and detection methods,while the standards of coal-based products are less and only cover a few major products in the industrial chain,and there are many blank standards for environmental protection,operating procedures,technical equipment,engineering construction,etc. in the coal chemical industry. At the present stage,the task of standardization is still dominated by the research and development of new standards,which should be guided by the overall development of coal chemical industry and relevant national policies. Accelerate the formulation and revision of energy conservation and environmental protection standards such as energy consumption quota,water intake quota,three wastes discharge and treatment,clean production and equipment technology standards,and guide the green and healthy development of the industry through the establishment of standards.On the other hand,while the establishment of relevant technical standards for clean and efficient utilization of coal is being promoted,attention should be focused on strengthening the relationship between coal chemical industry and power generation,oil and gas chemical industry,steel,building materials and other industries and establishing relevant technical standards.In the future,under the support of the new standard system led by the government and coordinated by enterprises and groups and the guidance of the "One Belt and One Road" strategy,the advanced and perfect standardization system will better facilitate the development of the coal chemical industry.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 812K]

Research progress on coal in-situ pyrolysis
ZHANG Yu;MA Mingming;SUN Ming;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;School of Chemical Engineering,Northwest University;
Coal pyrolysis is the initial and necessary stage in the thermal transformation and utilization of coal. The coal gas,tar,and semi-coke products is produced by thermal decomposition of coal. It is an important source of chemical industrial feedstocks and energy fuels in China,so it is of great significance to study the pyrolysis characteristics of coal for the directional control of coal conversion process. Primary pyrolysis is one of the important steps in the coal pyrolysis process,most of the coal pyrolysis products originate directly or indirectly from the primary pyrolysis,and the yield and properties of the primary pyrolysis products directly affect the targeted regulation of the secondary pyrolysis on the target products,so the secondary regulation has certain limitations in improving the yield of coal pyrolysis products.The concept of coal in situ pyrolysis was proposed in the paper,in order to improve the yield of coal pyrolysis products. From the perspective of directly affecting the primary pyrolysis of coal,the different pretreatment methods for coal,including thermal pretreatment and hydrothermal pretreatment,solvent swelling pretreatment,ionic liquid pretreatment,and swelling simultaneous loading metal ion pretreatment were summarized,and the process parameters such as temperature,pressure,pyrolysis atmosphere,residence time,and particle size were reviewed on the in-situ pyrolysis of coal. Finally,the future development trend of coal pyrolysis technology was prospected. On the basis of continuing to explore the mechanism of coal pyrolysis,how to combine the advantages of different coal pretreatment methods and different process parameters is a question. The corresponding coal pyrolysis technology is developed to increase the yield of coal in situ pyrolysis and reduce environmental pollution.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 346K]

Research progress on the recovery of methane from coalbed methane by pressure swing adsorption
ZHANG Jinhua;QU Sijian;WANG Peng;LI Xuefei;LI Lanting;CHE Yongfang;LI Xiaoliang;School of Chemical and Environmental Engineering,China University of Mining&Technology(Beijing);Coal Chemistry Branch of China Coal Research Institute;Beijing Key Lab of Coal Based Energy Conservation and Enviroment Protective Carbon Material;State Key Laboratory of Coal Mining and Clean Utilization;
The direct emission of low-concentration coal bed methane not only causes energy waste,but also brings serious environmentalharm such as greenhouse effect.The purification of low concentration coalbed methane by PSA is an effective way to solve the emission of coalbed methane.In this paper,the research on separation of methane from CH_4/N_2 system in coalbed methane using the technology ofpressure swing adsorption was summarized,including separation mechanism and the corresponding pressure swing adsorption purificationtechnology;the advantages and disadvantages of two kinds of technology were analyzed,and the research progress and existing problems ofCH_4/N_2 adsorption separation effect on porous adsorption materials were discussed such as activated carbon,carbon molecular sieve,zeo-lite molecular sieve and metal organic skeleton materials.Pressure swing adsorption technology based on equilibrium effect separation hasencountered a bottleneck in the practical application of CH_4/N_2 system separation since the equilibrium separation coefficient of existingadsorbents is too small and the concentration enhancement is limited.Secondly,CH4 is preferentially adsorbed as a strong adsorption com-ponent in the equilibrium effect. The product gas must be obtained by vacuum desorption,and multistage compression and additional dis-placement steps must be taken,so the energy consumption is relatively high. The enriched product gas with pressure can be directly ob-tained at the top of the towerbased on the separation of dynamic effect,meanwhile,the energy consumption of multi-stage compression isavoided,and it has a significant advantage comparing with the equilibrium effect separation. However,since the first stage is required to bepressurized,there are some safety risks in the treatment of coal-bed methane near the explosion limit concentration.Activated carbon is atypical equilibrium separation adsorbent with large adsorption capacity,strong processing capacity,and low price,but the separation coeffi-cient is low,and activated carbonhas the disadvantages of large gas circulation volume,low efficiency,and narrow concentration range. Howto improve the equilibrium separation coefficient of activated carbon through pore size control and surface modification will be the focus offuture research.Currently,carbon molecular sieves have been reported to be the main kinetic adsorbents with good results. However,due totheir high price and limited industrial promotion,it will be an important direction for pressure swing adsorption to separate CH_4/N_2 in thefuture by selecting appropriate and cheap raw materials,changing the current intermittent production process,and further developing effi-cient and cheap kinetic selective adsorbents.Zeolites preferentially adsorb methane,in contrast to kinetic effects which preferentially adsorbnitrogen,which reduce the separation selectivity of CH_4/N_2.Therefore,Si-Al zeolites/Ti-Si zeolites mostly perform well in the separationof natural gas and oilfield gas with high concentration of CH_4,while it is rarely applied in the purification of CH_4 with low concentration ofCBM,and there is no industrial application report.The emergence of metal-organic framework materials provides a new development idea,but there arethe few research on CH_4/N_2 adsorption balance and kinetics as well as pressure swing adsorption separation,which need to befurther studied. Therefore,the solution of stable forming and amplification of materials is still a technical bottleneck to be broken through.The author believes that the future pressure swing adsorption purification process will be a combination of equilibrium effect and kineticeffect,and the development of separation process under low pressure will have better economy and safety.The development of low cost,high capacity and high selectivity adsorbent is still the key development direction of adsorbent in the future. The adsorbent life and regener-ation performance need to be further studied.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 584K]

Research progress and application in microbial degradation of coal to produce humic acid
HENG Xitong;CHENG Juan;HE Huan;CAO Qinghe;LI Chengguo;School of Chemical Engineering and Technology,China University of Mining and Technology;Xuzhou Academy of Agricultural Sciences;Xuzhou Kuaibang Biotechnology Co.,Ltd.;
Humic acid exists in nature widely,which is a kind of natural organic polymer compounds,and humic acid is abundant in the low rank coal such as lignite and weathering coal. In this paper,the resource reserve,regional distribution,species and properties of ore-humic acid was introducedin China. The traditional physical and chemical processing method of humic acid was compared with the microbiological method.Based on the research of microbial treatment of low rank coal in recent years,the microbial species(mainly actinomycetes,bacteria and fungi) and co-culture germs which can degrade low rank coal to produce humic acid were summarized. In addition,the extensive application of ore-humic acidwas described. As a kind of soil improver,humic acid can fix the heavy metal ions in the soil,absorb and promote the degradation of pesticides,polycyclic aromatic hydrocarbons and other organic matters,and reduce the enrichment and toxic effect of heavy metals in plants,and relieve the pollution of soil.As an organic biological fertilizer,humic acid also plays a role in agricultural production.It plays a great role in promoting crop growth,enhancing crop stress resistance,improving the quality of agricultural products,boosting the utilization rate of chemical fertilizer,increasing the structure of cultivated soil,and regulating the water,fertilizer,gas and heat conditions of the soil,promoting the root system development of crops,and increasing crop yield and achieving sustainable agricultural development.In the field of medicine and petroleum industry,ore-humic acid is also widely used. Natural humic acid has the functions of hemostasis,promoting blood circulation,antibacterial,antiviral,improving microcirculation,regulating endocrine,improving immunity,etc. Humic acid drilling fluid products are also gradually welcomed by petroleum enterprises because of their non-environmental pollution,resistances of high temperature and scale.Ore-humic acid has been applied in many kinds of production practices with good effect,but the basic products of humic acid are few,and the influence of source in different areas and treatment technology on the quality of products is quite different,so it is necessary to strengthen the comprehensive analysis of the processing technology of ore-humic acid,the physical and chemical characteristics of products,the effect on soil and biological effect and so on. The regional development and compound utilization of humic acid need to be vigorously promoted,especially medical application. The production of humic acid from low rank coal resources by microbial transformation has many advantagesthat the traditional physical and chemical treatment technology cannot compare,such as simple technology,low energy consumption,pollution-free and the like,but at the same time,there are also some problems for instance long growth cycle and low production efficiency. It is an important research direction to further research the mechanism and regulation way of humic acid produced by microbial action on low rank coal.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 278K]

Influence factors and technical progress of CWS performance
ZHANG Xiaoyu;HE Guofeng;LI Lei;CHEN Hao;China Coal Research Institute;China Coal Technology & Engineering Group Clean Energy Company Limited Department;
Coal water slurry technology is an important branch in the development of clean coal technology in China. It is of great significance to improve the utilization efficiency of coal resources in China,reduce the pollution generated in the process of coal utilization,and realize the high value utilization of coal. It is the inevitable choice for the long-term and stable development of China's energy,which conforms to the national policy guidance and environmental protection requirements. With the expansion of coal water slurry,especially gasification slurry consumption and the improvement of energy conservation and environmental protection requirements,the quality of coal water slurry requirements are higher and higher in chemical plants. However,there are many common problems such as low concentration,poor rheological property and unsatisfactory gasification effect in gasification CWS in China,which reduce the efficiency of CWS gasifier and are not conducive to reducing cost,increasing efficiency and stabilizing production.Based on the evaluation index of CWS performance,in this paper,the measurement method of CWS performance index was introduced,and the significance of CWS concentration,viscosity,stability,flow pattern and rheology to actual production were explained.The effects of coal quality,additives,gradation and particle morphology on the performance of CWS were introduced in this paper,the direction for improving the performance of CWS was pointed out,and the significance of improving the concentration,flow pattern and fluidity of CWS with particle size gradation was emphasized.The research progress in the field of coal water slurry pulping in recent years was listed,including the compound of coal used for pulping,the research and development of new coal water slurry additives,and the introduction of the new pulping process of "breaking for grinding".The development trend of CWS technology was prospected,including the development of new pulping process and core equipment,the development of high-efficiency and economical low-order CWS additives,the treatment of chemical sludge and gasification slag and other wastes,as well as the research on the law of interaction between CWS particles and particle morphology.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 4550K]

Study on the characteristic of pressurized hydrogen-rich pyrolysis and semi-coke gasification of coal
AN Bin;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;
In order to study the reaction between the pyrolysis zone and the gasification zone in the pressurized fixed bed gasificationprocess,the pyrolysis and semi-coke gasification process of the fixed bed hydrogen-rich atmosphere was simulated,and the influence ofpressure,heating temperature and hydrogen-rich ratio on coal pyrolysis were investigated by the pressurized hydrogen-rich pyrolysis de-vice. The mechanism of the influence of various factors on pyrolysis was analyzed. The pyrolysis of semi-coke in hydrogen-rich atmospherewas used as raw material. The experimental study was carried out by pressurized thermogravimetric analyzer. The change of carbon conver-sion rate and CO_2 reaction rate with time under different temperature and different pyrolysis raw materials and the effect of hydrogen-richratio on gasification reaction activity were analyzed. The results show that in the atmospheric pressure hydrogen-rich atmosphere pyrolysistest,with the proportion of hydrogen rich increasing,a large amount of H are provided and the concentration of H is increased. During the pyrolysis process,the free radicals will continuously combine with H to form stable components. Including a large number of small mole-cules of volatiles and some tar precipitation,the volatiles in the semi-coke decrease by 0.69%,the semi-coke yield decreases by 4.8%.The semi-coke yield under the pressurized conditions is higher. The semi-coke yield with the increase of pressureis not obvious law. Thevolatile matter gradually decreases,but the change is small. With the increasing of the final temperature,the volatile yield gradually increa-ses in the hydrogen-rich atmosphere. H in hydrogen rich atmospherewill combine with free radicals to form a small molecular structure andescape,and the semi-coke yield and volatile matter will gradually decrease. Increasing the proportion of hydrogen richcan increase the ma-turity of the semi-coke,the proportion of hydrogen rich increases from 0 to 35%,and the concentration of H increases. Small molecules canbe rapidly hydrogenated to form volatiles,while the macromolecules will also hydrogenate into a stable structure,the semi-coke volatilesdecreases by 1.46%,the semi-coke yield decreases by 2.50%. Hydrogen-rich pyrolysis can significantly promote CO and CH_4 productionat 35% H_2,reaching 91.2 mL/g and 63.8 mL/g. From the experimental study of gasification characteristics,it can be known that increas-ing the gasification reaction temperature can improve the gasification reaction activity of hydrogen-rich semi-coke and CO_2. The gasifica-tion activity of pyrolysis char in hydrogen rich atmosphere is similar to that in inert atmosphere,which shows that hydrogenation pyrolys-iscan improve tar yield,tar quality and gas quality,and has little effect on the gasification activity of semi-coke.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 962K]

Evolution law of typical minerals in coal under high temperature
SHAO Xun;ZHANG Ningning;MA Dong;Ding Hua;Coal Chemistry Branch of China Coal Research Institute;State Key Laboratory of Coal Mining and Clean Utilization;
Typical minerals in coal can be divided into six types:clay mineral,sulfide,phosphate,carbonate,sulfate and other minerals. The evolution process of minerals in coal under the temperature increasing process has big effect on viscosity-temperature characteristics of coal ash,therefore,the minerals constitution has certain effect on application range and utilization path of coal. Through analyzing the main minerals constitution in coal and variation low of different minerals groups under the temperature increasing process,the reference of gasification raw coal selection and viscosity-temperature characteristics adjustment of gasification coal ashcould be provided.In this paper,the conversion processof main minerals in coal under high temperature and the main product of process were demonstrated. 8 kinds of minerals such as kaolinite,illite and pyrite were divided into 3 groups according to their mineral characteristics,The simulation study was carried outrespectively by utilizing the FactSage software in the temperature range of 1 000～1 600 ℃. The inert atmosphere was selected in calculation process,and the calculation was done once every 100 ℃,and every mineral was calculated as amount of 1 mol. When a new mineral appeared,or an old mineral disappeared,the minerals constitution at this temperature was calculated as well. The results show that,in the system which is composed of kaolinite and illite,the mullite still exists under the temperature of 1 600 ℃,the sanidine disappears at 1 145℃,and the leucite is generated in 1 145-1 286 ℃. Hercynite generated in the system which is composed of pyrite,apatite,calcite,siderite,gypsum and quartz disappears at 1 106 ℃,the hydroxyapatite disappears at 1 455 ℃. When these 8 kinds of mineralsallcoexist,the hydroxyapatite generated disappears at 1 285 ℃,the mullite disappears at 1 118 ℃. After 1 448 ℃,most of solid entersinto the slag. Mullite is a typical refractory mineral in coal,and when the low melting mineral in coal ash becomes the slag,it can react with mullite to generate the low temperature eutectic,and the solid matter content can be reduced,which is good at improving the viscosity-temperature characteristics.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 929K]

NO_x emissions characteristics of a novel low-NO_x swirl burner
GONG Yanhao;XU Xinwei;WANG Denghui;WANG Xuebin;TAN Houzhang;NIU Yanqing;HUI Shien;LI Zairang;LIU Yuanwu;State Key Laboratory of Multiphase Flow in Power Engineering,School of Energy and Power Engineering,Xi′an Jiaotong University;Taishan Group Co.,Ltd.;Xi′an Jiaoda Siyuan Technology Co.,Ltd.;
Aiming at increasingly stringent emission standards of coal-fired industrial boilers,a novel low-NO_x swirl burner was proposedin this paper. The pulverized coal preheating was coupled with the air staging of burner and furnace,and the pulverized coal preheating combustion state was adjusted by changing the air distribution of the combustion system. The effects of primary air rate,inner and outersecondary air rate,outer secondary air injection method,recirculating flue gas rate and over fire air(OFA) rate on NO_x emissions werestudied. The results show that with the increase of primary air rate from 15.4% to 28.7% in the experimental conditions,the oxygen con-centration in the preheating chamber increases,and N which is present in nitrogen-containing compounds HCN,NH_3,etc. in the vola-tile matter from the pyrolysis of pulverized coal is directly oxidized to NO by the oxygen carried by primary air,resulting in increasing NO_x formation from 284.4 mg/m~3 to 326.7 mg/m~3. When the ratio of internal and external secondary air increases from 0.46 to 1.4,the NO_x emission concentration decreases first and then increases. The inner secondary air volume affects the excess air ratio and turbulence inten-sity in the preheating chamber,and the outer secondary air volume affects the turbulence intensity of pulverized coal combustion reaction inthe primary combustion zone inside the furnace. Due to the combined effects of changes in secondary air distribution,the lowest NO_x emission value is 211.2 mg/m~3 when the ratio of inner and outer secondary air is 1.0. As the ratio of the air volume injected from the inside ofthe preheating chamber to injected from the end face of the preheating chamber of the outer secondary air increases from 0 to 4.56,the NO_x formation concentration reduces first and then increases. The outer secondary air injected from the end face of the preheating chamber has alonger injection boundary,which makes the primary combustion zone relatively larger and the overall combustion is relatively uniform.Whereas,the outer secondary air injected from the inside of the preheating chamber promotes the mixing of preheating products at the outletof the precombustion chamber with combustion air in the furnace. When the inside/end face injection air ratio of the outer secondary air is 0.25,the turbulence intensity of pulverized coal in the outlet area of the preheating chamber is improved,and the NO_x formation has a minimum value of 230.9 mg/m~3 in a partially reducing atmosphere. As the recirculating flue gas rate increases from 0 to 30.6%,the oxy-gen concentration in the inner and outer secondary air decreases,which makes the reducing atmosphere in the preheating chamber and theprimary combustion zone enhanced. The probability that N which is present in nitrogen-containing compounds HCN,NH3,etc. in the volatile matter reacts to form N_2 increases,and NO_x emission gradually decreases from 250.7 mg/m~3 to 221.1 mg/m~3. As the OFA rate increa-ses from 0 to 29%,the NO_x emission value decreases first and then increases. With the increase of the OFA rate,the secondary air rate de-creases,and the turbulence diffusion capacity of the inner and outer secondary air is weakened,meanwhile,the reducing atmosphere in theprimary combustion zone is enhanced. The further increase of the OFA rate makes the oxygen content in the primary combustion zone insuf-ficient,and the oxidizing atmosphere in the burnout zone is strong. At this time,a large amount of coke and nitrogen-containing compoundsundergo oxidation reactions in the burnout zone,resulting in the increase in the NO_x formation. When the OFA rate is 19.6%,the lowest NO_x emission value is 253.5 mg/m~3. Overall,When the primary air rate is 17%-19%,the inner and outer secondary air ratio is 0.8-1.0,the outer secondary air is injected from the end face of the preheating chamber,the recirculating flue gas rate is 15%-20%,and the OFArate is 19%-22%,the NO_x emission value is 212-231 mg/m~3,which is 29%-35% lower than the maximum NO_x emissions in the experi-mental conditions.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 990K]

Effect of composite catalyst of nano-scale CaO supported ferrocene on combustion characteristics of bituminous coal
YAN Xiaochuan;ZHANG Baojun;WANG Tiaoni;FAN Xibing;Department of Biochemical Engineering,Pingliang Vocational and Technical College;Pingliang Environmental Monitoring Station;
In the field of coal catalysis,the inorganic iron catalysts are toxic and the dispersion of CaO is poor. In order to improve the catalytic efficiency,it is urgent to find a new organic-inorganic composite coal catalyst. In this study,the load rate of nanometer calcium oxide supported ferrocene composite catalyst(CaO-Fe(Cp)_2) was 85.46%,and(CaO-Fe(Cp)_2) was prepared by calcined calcium oxide at high temperature and impregnated with carbon dichloride solution. The catalytic properties of bituminous coal in Huating donghua town coal mine, such as burning loss rate,heat value release rate,sulfur release rate,ash content and ash melting property were studied.The catalytic performance of nanometer CaO-Fe(Cp)_2 composite catalyst was better than that of CaO and ferrocene alone. When burning at 500 ℃ for 2.5 h,the combustion loss rate of the coal sample with the addition of nanometer CaO-Fe(Cp)_2 composite catalyst is 24.95%higher than that of the raw coal,which is 13.20% higher than that with the addition of 1% nano CaO,and 6.95% higher than that with the addition of 1% ferrocene. The calorific value release rate of the coal sample with nano-cao-Fe(Cp)_2 composite catalyst increases by27.16% compared with that of raw coal,9.63% compared with that of coal with 1% nano CaO and 4.75% compared with that of coal with1% ferrocene. The sulfur release rate of CaO-Fe(Cp)_2 composite catalyst is 5.87% lower than that of raw coal,3.98% higher than that of CaO with 1% nanometer,and 9.92% lower than that of ferrocene with 1%. The ash content of the coal sample with the addition of nanometer CaO-Fe(Cp)_2 composite catalyst is10.58% lower than that of raw coal,13.50% lower than that of coal samples with 1% nano CaO and4.28% higher than that of coal samples with 1% ferrocene. The results show that nanometer CaO-Fe(Cp)_2 composite catalyst is evenly distributed in coal,which increases the contact area with coal molecules,increases the reaction reactivity,accelerates combustion rate,promotes the sulfur release,reduces the ash content,and releases Fe_2O_3 slowly at the initial stage of catalysis to avoid catalyst poisoning. As a new type of high efficiency coal burning catalyst,it has a broad application prospect.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 465K]

Combustion and slagging characteristics of Zhundong coal and blended coals
BAI Yang;ZHAO Yonggang;XU Huijun;ZHU Chuan;Shenhua Guoshen Technical Research Institute;CHN Energy Co.,Ltd.;Coal Chemistry Branch of China Coal Research Institute;
Zhundong coalfield is the largest integrated basin in China. Combined with the characteristics of medium and high water content,medium and high volatile matter,low contents of sulfur,trace element,and low cost mining,medium calorific value and good reaction activity,which is a large-scale coal chemical industry and coal electrical co production high-quality raw material.However,the high content of Na and Ca in Zhundong coal affects the normal operation of the boiler,which limits the combustion and utilization of Zhundong high sodium coal. To investigate the combustion and slagging characteristics of Zhundong coal and its mixture,two raw coal called Zhundong coal(ZD) and Wudong coal(WD) were collected from Wuhuaiwan power plant. The combustion characteristics of ZD coal and mixed coals were studied using thermogravimetric analyzer,and the change rule of coal ash characteristics under response ratio was analyzed.The results show that there are two characteristic peaks for blendings of Zhundong and Wudong coals. With the increase of ZD coal blending ratio,TD-DTG curves of blended coal combustion move to the low temperature area,and the characteristic peak of DTG curve is more obvious.The characteristic temperature and the ash fusion temperature of blended coals gradually decrease,while the maximum combustion rate and comprehensive combustion characteristic index first decrease and then increase,and the fusion temperature of blended coal ash gradually decreases.ZD coal has higher alkali oxide and lower acid oxide content than WD coal,and blending with high ratio zhundong coal has high contents of SO_3,CaO and Na_2O and more serious ash-related problems;However,some indexes can not accurately predict the slagging strength,such as Zhundong coal silicon aluminum ratio is 1.67,and Wudong coal silicon aluminum ratio is 3.02.Judging slagging tendency based on silicon aluminum ratio is not consistent with the fact;In addition,when the CaO content in coal is more than 30%,the ash melting temperature will increase,which is the reason why Zhundong coal has higher ash melting temperature than Wudong coal.With the increase of the proportion of Zhundong coal,the melting temperature of blended coal ash decreased obviously. The indexes of combustion slagging and fouling tendency are mainly based on the composition of coal ash and the melting temperature of coal ash.Based on the test results of the former prediction indexes of slagging and fouling,it is concluded that the alkali acid ratio based on the ash composition and the characteristic temperature difference(FT-DT) based on the ash melting temperature are the ideal indexes for judging the slagging and fouling tendency of Zhundong coal and its blended coal.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 846K]

Operation optimization study on the wet desulphurization system of a 1 000MW ultra-supercritical coal-fired power plant
LIU Jun;LUO Xiaoyu;LIAO Yihan;WANG Weishu;XU Kai;School of Electic Power,North China University of Water Resources and Electric Power;Suzhou Branch,Xi'an Thermal Power Research Institute Co.,Ltd.;
In view of the technical problems of large energy consumption and high cost in the operation of the wet desulfurization system ina 1 000 MW ultra-supercritical boiler,the SO_2 and O_2 concentration on the inlet and outlet of the flue gas desulfurization system was meas-ured timely by using a NGA2000-MLT3 type flue gas analyzer,the desulfurization efficiency of the system was obtained,and the operation-costs including limestone,SO_2 discharge fee and the main equipment power consumption of desulfurization system during the test were cal-culated or tested. According to the test results,the effect of the slurry circulating pump combination mode,pH value of the slurry liquid and the liquid level of absorber on the desulfurization efficiency were studied respectively. The desulfurization cost was calculated according tothe operation condition of the unit during the test period,and the optimum operation mode of the desulfurization system was obtained. Theresults indicate that during the operation process,when slurry circulating pump combination of BD is used,the SO_2 concentration at outletof the chimney is low,but the power consumption of slurry circulating pump is high under 1 000 MW load. When choosing the slurry circu-lating pump combination of BC,the costs are moderate,the desulfurization efficiency of absorption tower can reach 97.06%,and there is a margin of SO_2 concentration at outlet of the chimney at the same time,therefore the optimal choice of slurry circulating pump combinationunder 1 000 MW is BC. A high pH value of slurry in the absorption tower is not conducive to the dissolution of limestone,while when thepH value is too low,the SO_2 absorption rate decreases. The test results show that the best pH value of slurry is in the range of 5.50-5.60 under 1 000 MW and the slurry circulating pump combination of BC. As the pH value is further reduced,SO_2 emissions will exceed thelimit of power plant emissions. The level of the absorption tower has an important influence on the costs of desulfurization system. The riseof the absorption tower level can improve the desulfurization efficiency of the system,but the power consumption of the oxidation fan will beincreased. The effect of absorption tower level on the total operation cost of the desulphurization system was experimentally studied by con-tinuously adjusting the absorption tower level. The results show that the best liquid level of absorber is from 8.00 m to 9.00 m with the bestslurry circulating pump combinations and the pH value. The total cost of the desulfurization system decreases from 2 010.45 yuan/h to1 916.65 yuan/h,which is 9.64% reduction,as the absorption tower level is reduced from 9.53 m to 9.01 m.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 559K]

Experimental study on flue gas denitration performance of a new non-toxic catalyst for 630 MW unit
XIAO Guozhen;Guohua Taicang Power Generation Co.,Ltd.;
In the SCR system,the denitration efficiency is greatly affected by the performance of the catalyst. The V_2O_5-WO_3/TiO_3 cata-lyst which is widely used is not only expensive,but also the vanadium oxide in the catalyst after deactivation will cause serious pollution tothe environment. Therefore,traditional catalysts need to be improved. The new non-toxic catalyst uses rare earth metal oxide as the ac-tive component,which can greatly reduce the degree of environmental pollution. In order to study the application effect of the new non-tox-ic catalyst in practical engineering,and taking unit 8 of the power plant as an example,the denitration efficiency,ammonia escape rate,and SO_2/SO_3 conversion rate of the SCR denitration system of the unit were tested. Three operating loads of 360,500,and 600 MW weretested,and sampling inspection was carried out on both sides of A and B under each operating condition. The test results show that the av-erage denitration efficiency of the SCR denitration system under 3 operating loads is 82.31%,76.81%,and 81.58% respectively,and thedenitration efficiency of the single-layernon-toxic denitration catalyst is 52.34%,55.34%,and 57.14% respectively,which are all greaterthan guaranteed value of 45%.Under the test load of 600 MW,the average SO_2/SO_3 conversion rate of the newnon-toxic catalyst is 0.38%,which is less than the guaranteed value of 1%,and the resistance of the first-layer catalyst under the three loads is 96,117.5 and 153 Parespectively,which are both less than the guaranteed value of 200 Pa.The average ammonia escape concentrations are 1.26×10~(-6),1.46×10~(-6),and 0.52×10~(-6) respectively,which are less than the guaranteed value of 2.5×10~(-6). The NOxconcentrations at the sides of the denitration system A and B at 360 MW are 38 and 46 mg/m~3.The NOx concentrations at the sides of the denitration system A and B at 500 MW are 21 and 28 mg/m~3. At 600 MW,the denitration system A,B The NOx concentrations at the outlets on both sides of B were 27 and31 mg/m~3,respectively. Under all operating conditions,the NOx concentration in the flue gas on both sides of outlet A and B of the denitra-tion system is lower than the requirements of ultra-low emission standards,and the new non-toxic denitration catalyst can meet the re-quirements of industrial applications.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 6231K]

Comparative and research on on-line measurement of CO in flue gas of thermal power unit
HAO Jian;ZHOU Peili;PENG Zhimin;DING Yanjun;Sanhe Power Co.,Ltd.;Department of Energy and Power Engineering,Tsinghua University;
At present,oxygen content is generally used as the reference quantity for combustion efficiency monitoring in thermal power units. However,oxygen content can′t accurately reflect the mixing situation of wind coal inthe combustion process,and the oxygen measurement in flue gas is greatly affected by the oxygen in air. Therefore,on the basis of oxygen measurement,and combined with the CO concentration measurement of incomplete combustion,the reliability of combustion efficiency monitoring can be improved.A comparative study of two kinds of CO measuring instruments was carried out,which were realized based on NDIR technology with sampling mode and TDLAS technology with in-suit mode,respectively. The sampling probe rod of NDIR-based with sampling mode instrument was installed in the flue behind the economizer,and the sample gas entered the analyzer for NDIR measurement after the pretreatments which included multistage filtration and condensation and water removal. The measurement chamber of TDLAS-based with in-situ mode instrument was installed in the flue after the economizer,and the flue gas entered the chamber to realize TDLAS measurement after passing through the filter which was installed on the chamber front end. The measurement results show that CO concentration in the flue gas of thermal power units has the characteristics of large variation range and fast change speed. The NDIR-based with sampling mode instrument has a long-time delay due to the sampling path,and it has the shortcoming of large maintenance because of the complex pretreatment such as multi-stage filtration,condensation and water removal,at the same time,the measurement results are easy to be untrue due to the adsorption or reaction characteristics of the gas during the sampling process. The TDLAS-based with in-suit mode instrument is able to respond to the instantaneous change of CO concentration in time due to the short sampling path and fast response speed when the measurement chamber is installed in the flue,and the instrument adopts the integrated structure design,which has high system stability and small maintenance,at the same time,the instrument can realize the high fidelity measurement because the measurement chamber is installed in the flue which can ensure that the measurement environment is consistent with the flue environment.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 1951K]

Simulation and optimization study of low temperature economizer and flue flow field of 1 000 MW unit
DENG Xiaochuan;HU Longbin;LI Bin;FANG Fang;Beijing Guodian Futong Science and Technology Development Co.,Ltd.;
The complex structure of double inlet gas flue has a significant influence on gas flow field distribution in a 1 000 MW coal-firedboiler′s low temperature economizer. In order to optimize gas flow field of the low temperature economizer with double inlet gas flues andensure the heat exchange efficiency and reduce its failure rate,based on the computational fluid dynamics(CFD) numerical simulationtechnology and the standardk-εmodel,the porous medium model was used to replace the fin heat exchanger with complex structure.Theflow field distribution in the low-temperature economizer and its double inlet flue of a 1 000 MW coal-fired unit is studied by numericalsimulation and structural optimization. In order to ensure that the simulation results were closer to actual situation,the numerical simula-tion model was verified by comparing measured values with calculated values of flue gas pressure loss at the corresponding sampling pointof low temperature economizer under different working conditions,then the reliable boundary parameters of the model were obtained.Thedeviation between the measured value and the pressure loss value corresponding to the numerical simulation before the optimization of thelow-temperature economizer flue structure was controlled at-23-31 PA,which verified the accuracy of the numerical model. After optimi-zing the structure of the low-temperature economizer and its flue,the established model was used to simulate the flow field. In differentboiler load conditions corresponding to the gas flue inlet velocity of 3.7,6.1,8.5,9.7,12.2 m/s,the numerical simulations had been maderespectively before and after optimizing structure of the low temperature economizer's inlet gas flue. The evaluation results show that gasflow field distribution in low temperature economizer has been worse and worse,when the velocity of flue gas at the flue inlet is more than5.3 m/s,before optimizing structure of the low temperature economizer's inlet gas flue and with the increase of boiler load,the air flowuniformity of the section becomes worse and with the increase of boiler load,the air flow uniformity of the section becomes worse.Afterstructural optimization,with the increase of flue gas velocity,the gas flow field distribution in low temperature economizer becomes worse,but within the excellent flow field distribution range(10%) and the uniformity of air flow distribution in the entrance section of the heat ex-change area is obviously improved.The results of numerical simulation show that the main reasons for uneven distribution of flow field ineconomizer and its inlet gas flues are unequal diameter of flue elbow and straight flue,unreasonable setting of guide plate and diffusion flueelbow. After making structural optimization of the low temperature economizer such as equalizing elbow to the straight flue diameter andsetting the guide plate reasonably,the gas flow deviation inside the vertical flue of the low-temperature economizer is obviously weakened,the air flow at the top of the elbow on the vertical flue is too small,and the air flow velocity at the bottom is too fast,so the air flow uniform-ity at the inlet of the heat exchange area of the low-temperature economizer is obviously improved. The analysis shows that the elbow withthe same diameter as the straight flue is beneficial to improve the uniformity of air distribution in the flue. When it is necessary to connectthe diffusion flue after the flue turns,the flue should be connected to the diffusion flue after a certain distance of equal diameter turning,which is conducive to improving the uniformity of air distribution in the flue.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 1387K]

Study on the removal effect of ozone catalytic oxidation on COD from the steam ammonia dephenolic wastewater in fixed bed
ZHANG Chao;WANG Jikun;WANG Hongyi;LI Hongwei;WANG Liguo;DU Song;HUANG Rongfa;Shandong Huanneng Environmental Protection Technology Co.,Ltd.;China Coal Research Institute;General Prospecting Institute China National Administration of Coal Geology;Pingxiang Coal Science Environmental Protection Technology Co.,Ltd.;
In order to obtain the best process parameters of ozone catalytic oxidation,the impact of ozone ventilation,ozone concentrationand catalyst dosage on COD removal was studied by using single factor and orthogonal test method in 1 t/h ozone catalytic oxidation device-and the primary and secondary order of process conditions and the best process parameters were determined.Finally,the best process pa-rameters were tested continuously for 80 hours,and the removal effect of COD under the best process parameters was further investigated. Itis concluded that the three process conditions(i.e. ozone concentration,ozone ventilation capacity and catalyst dosage) have a great influ-ence on COD removal rate.Through single factor experiment,it is found that with the increase of ozone ventilation,ozone and catalyst dos-age,the COD removal rate will increase under the same conditions,but the treatment cost will increase. Considering COD removal rate andozone ventilation cost,the ozone ventilation rate is 1.5 m~3/h≤ozone ventilation rate≤2.5 m~3/h;the ozone concentration is 150 mg/L≤ozone concentration≤250 mg/L;the catalyst dosage is selected as 20 kg/t≤catalyst dosage≤30 kg/t.Through the orthogonal experiment,it is found that the primary and secondary order of the influence of three ozone oxidation conditions on COD removal rate is ozone concen-tration > ventilation > catalyst dosage,which confirms the above single factor test results. The best process parameters are obtained:ozoneventilation 2.0 m~3/h,ozone concentration 250 mg/L,catalyst dosage 30 kg/t.Finally,1 t/h ozonation device was used to carry out continu-ous ozonation test on the wastewater after phenol removal and ammonia evaporation for 80 h under the optimal process parameters and theremoval rate of COD was stable at about 43.5%,and the biodegradability(B/C) after reaction was stable above 0.4,which reduced the loadand difficulty of subsequent biochemical treatment. It is proved that the ozone oxidation process has a good practical application effect.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 857K]

Study on adsorption characteristics of diethyldithiocarbamate in mineral processing wastewater by coal
BIAN Yue;SU Xin;HE Hongxing;DU Liwei;ZHANG Jing;China Coal Research Institute Company of Energy Conservation;National Coal Water Mixture Engineering Technology Research Center;State Key Laboratory of Coal Mining and Clean Utilization;National Energy Technology and Equipment Laboratory of Coal Utilization and Emission Control;School of Chemical Engineering and Technology,China University of Mining and Technology;
In order to explore the adsorption process of coal powder for organic pollutants on the wastewater from mineral processing,coal powder was used as an adsorbent to adsorb diethyldithiocarbamate in mineral processing wastewater. The physical and chemical properties of coal powder were investigated,and the adsorption conditions such as dosage and adsorption time on the adsorption process were explored through the preparation of simulated wastewater containing ethinyl sulfide nitrogen pollutant. In addition,the adsorption isotherms and adsorption rate control process of the adsorption of diethyldithiocarbamate by coal powder were emphatically studied. The results show that coal powder is a natural adsorbent with complex surface structure,abundant pore structure and oxygen-containing functional groups.The addition amount of coal powder and adsorption time are important factors affecting the adsorption effect. With the increase of the amount of coal powder,the removal rate of diethyldithiocarbamate in the solution first increases,then stabilizes,and the adsorption amount decreases continuously. With the increase of adsorption time,the removal rate and adsorption amount increase rapidly at the beginning,and/g respectively L and adsorption time 30 min. What is more,the Langmuir and Freundlich isotherm adsorption models are used to fit the adsorption behavior of pulverized coal to ethionine,and the Freundlich isotherm adsorption model is more consistent with the adsorption process,indicating that the adsorption behavior was multilayer adsorption based on surface. The adsorption kinetics is studied by using the quasi first order kinetic equation,the quasi second order kinetic equation and the particle internal diffusion model. The adsorption of diethyldithiocarbamate by coal powder is better in accordance with the Pseudo-second-order kinetic model. The control steps of the adsorption rate included external liquid film diffusion,surface diffusion and particle diffusion,but surface diffusion is the dominant factor.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 3945K]

Mechanism and control method of fouling and slagging in circulating fluidized bed garbage incinerator
YUAN Ye;ZHENG Yan;MA Fengming;CHI Xiaoxu;SHI Zhenghai;SU Xianbin;GAO Hongpei;XIAO Ping;State Key Laboratory of Coal Based Clean Energy,Huaneng Clean Energy Research Institute;Beijing Guodian Longyuan Environmental Engineering Co.,Ltd.;Huaneng Baishan Gangue Power Generation Co.,Ltd.;Fujian Southeast Electrochemical Co.,Ltd.;
With the rapid economy development and the improvement of people's material living standard in China,there are more and more living and industrial waste. The fouling and slagging problems of incinerators caused by the characteristics of domestic garbage seriously affect the continuous incinerator operation,thermal efficiency and power generation. Therefore,it is necessary to study the fouling and slag-/h circulating fluidized bed incineration were studied. Through the field investigation and sampling,fuel and fly ash composition and chemical analysis and theoretical calculations,the amount of combustibles in air preheater could be determined. Then,the main reasons for high and low temperature ash deposition were further studied. Finally,the control measures of fuel adjustment,boiler operation and equipment transformation were put forward. When the preheater begins to reburn,there are at least about 3 t combustibles in the entire air preheater and at the same time the fouling ash has reduced the half inner diameter of the central tube of separator.The multi waste fuel is hard to burnout completely due to its higher particle size and lower density. According to the TGA test,it can be seen that the decomposition rate is much slower below 300 ℃. It is easy to form the tar organics due to the unburned fuel during cooling process and the viscosity of the organic matter in the low temperature ambient is the main reasons for the ash low temperature fouling in the air preheater. Meanwhile,the low temperature eutectic formed between the alkali and alkaline earth metals(Na,K,Ca,etc.) and Cl,S,O is the main cause of ash slagging in the central tube. In addition,the speed variation and secondary reflow produced by the stiffener of the central tube will increase the possibility of particles hitting the tube surface,which is likely to be one of the key factors to induce slagging at the initial stage. According to the above two problems a series of control strategies based on fuel adjustment,boiler operation and equipment modification are proposed.It mainly includes:improving the waste fuel feeding system,strengthening steam soot-blower,adding pulse soot-blowers and inert gas protection system in the air preheater,controlling the blending ratio of waste fuel,adjusting the temperature of the separator,increasing the flue gas flow rate,adding MgO,Fe2 O3 powder or kaolin;a good mix of air and fuel can avoid the formation of a reducing atmosphere at the fouling and slagging location.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 1035K]

Research on waste derived fuel incineration technology
ZHANG Shixin;XU Yanfei;LYU Yong;LIU Haifeng;DENG Lei;State Key Laboratory of Multiphase Flow in Power Engineering,Xi′an Jiaotong University;Huaneng Clean Energy Research Institute;Fujian Huadian Yongan Power Co.,Ltd.;
Refuse derived fuel is widely used in drying engineering,cement manufacturing,heating engineering and power generation engi-neering. The mechanical grate incinerator has the problems of high investment cost,high maintenance cost,large floor area and large heatloss.The gasification incineration technology is still in the laboratory or semi industrial stage,which can not realize the industrial applica-tion.The rotary kiln incineration requires high waste heat value,and the slag index is easy to exceed the standard,so it is rarely used in in-dustry.Therefore,in view of the characteristics of fluidized bed boiler,such as large furnace heat capacity,intense mixed combustion in thefurnace and strong fuel adaptability,it is necessary to study the incineration process of waste derived fuel,biomass and solid waste. Startingfrom the aspects of combustion mechanism,material preparation and transportation,the research and development of key technologies,process optimization and core component design of direct mixed combustion of garbage in CFB boiler were completed through theoretical re-search,numerical simulation,combustion test,equipment research and field test,and the application of this technology in large-scale CFBboiler was verified. The results show that the complete and stable combustion of MSW and the decomposition of dioxin can be promoted by ensuring the incinerator temperature and residence time(more than 2 s) and increasing the turbulence degree(Re>5 000) in the incinera-tor. In order to reduce the content of combustibles brought to the tail flue,it is necessary to improve the burn out of garbage fuel during op-eration,so as to avoid the accumulation of ash and secondary combustion caused by the condensation of incompletely burned organic mole-cules at the position of air preheater. Through theoretical analysis and test,the final choice is to use pneumatic conveying system to sendthe crushed biomass and solid waste into the furnace,and the boiler interface is arranged at the outlet of the feeder to meet the needs of bi-omass and solid waste combustion time,temperature,mixing,burnout,etc. The practical operation results show that the 300 MW CFB boil-er can simultaneously treat 200 t/d biomass,400 t/d solid waste,200 t/d sludge and 50 t/d RDF. The emission concentration of dioxin inthe flue gas is lower than 0.001 3 ng/m~3(standard,11% O_2),the emission of SO_2 is lower than 12 mg/m~3,and the emission of NO_x is lower than 50 mg/m~3,which meets the relevant standards. The system can burn 120 000 tons of solid waste in one year,which can saveenergy equivalent to 85 500 tons of standard coal,and reduce emissions of 237 000 tons of CO_2,726.8 tons of SO_2,632.7 tons of NOx and33 500 tons of ash. It can dispose a lot of solid waste in a short time,and solve the important problems such as direct burning of straw inthe field,siege of sludge and garbage.
2019 06 v.25;No.124 [Abstract][OnlineView][HTML全文][Download 1102K]

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2019年06期目次

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Research on waste derived fuel incineration technology