• Research progress on bio-fuel prepared from livestock manure by hydrothermal treatment

    ZHANG Shouyu;CHEN Xuyang;LIU Simeng;HAN Xiuyuan;ZHANG Xingjia;XU Zihang;HU Nan;WU Yuxin;School of Energy and Power Engineering,University of Shanghai for Science and Technology;School of Energy and Power Engineering,Changchun Institute of Technology;Department of Thermal Engineering,Tsinghua University;

    With large-scale and intensive development of livestock breeding industry, a large and concentrated amount of livestock manure is produced. Due to the lack of close integration between animal husbandry and agriculture in China, as well as the excessive content of heavy metals and antibiotics in livestock manure, it is difficult to return livestock manure to the field. The preparation of bio-fuel from livestock manure by hydrothermal treatment can achieve its energy and innocuous utilization. Represented by the largest production of swine manure, its components and physicochemical properties were summarized, and the shortcomings of traditional treatment methods were discussed. The yield, combustion characteristics, and dewatering characteristics of swine manure residue after hydrothermal treatment were analyzed and summarized. Finally, the development prospects of using hydrothermal residue as bio-fuel were discussed. Swine manure contains hemicellulose, cellulose, lignin, protein, lipid and other components, and is rich in nitrogen, phosphorus, potassium and other nutrients required for plant growth. After reasonable treatment, it can be used as a resource. Aerobic composting and anaerobic fermentation techniques are difficult to efficiently degrade antibiotics in swine manure, and high concentrations of heavy metals in swine manure can also have adverse effects on the composting and fermentation process. Hydrothermal treatment is a promising technology for treating high moisture content biomass such as livestock manure. Swine manure can be converted into hydrothermal residue and hydrothermal residual liquid through hydrothermal treatment. The performance of hydrothermal residue is equivalent to that of lignite, and the hydrothermal residual liquid can be used for irrigation after appropriate dilution. In addition, hydrothermal treatment can effectively solidify heavy metals and degrade antibiotics. The degradation and dissolution of organic matter during hydrothermal treatment results in a decreasing trend in the yield of swine manure hydrothermal residue with increasing hydrothermal temperature. In the paradigm diagram, the hydrothermal residue of swine manure can reach the area of lignite, and its volatile matter and higher heating value can also reach the level of lignite. A large amount of bound water is converted into free water during the hydrothermal treatment process, improving the dewatering and drying characteristics of swine manure hydrothermal residue. In addition, alkali metals are easily dissolved into the hydrothermal residual liquid during hydrothermal treatment process, reducing the risk of slagging during the combustion of hydrothermal residue. Heavy metals are enriched in hydrothermal residue after hydrothermal treatment, and their leaching rate and ecological toxicity have been reduced. The excellent combustion characteristics and grindability of swine manure hydrothermal residue make it have the potential to co-combustion with coal, but it is necessary to modify the coal powder furnace appropriately and control reasonable parameters such as excess air coefficient. The co-hydrothermal treatment of swine manure with agricultural and forestry waste can reduce the ash content of the hydrothermal residue, increase the fixed carbon content and higher heating value. The economic issue of the hydrothermal treatment process for livestock manure is the main reason limiting its industrial application. By optimizing process design and other means, it is helpful for the practical application of hydrothermal treatment technology in the treatment of livestock manure.

    2023 05 v.29;No.153 [Abstract][OnlineView][HTML全文][Download 9211K]

  • Biomass chemical looping gasification integrated with gas turbine and Organic Rankine Cycle for power generation

    MU Lin;HU Tiancai;WANG Zhen;HUANG Xiankun;ZHAO Liang;YIN Hongchao;School of Energy and Power Engineering,Dalian University of Technology;Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education;

    Biomass chemical looping gasification(BCLG) is a promising biomass utilization and carbon capture technology, while Organic Rankine Cycle(ORC) is an energy conversion technology that can achieve a higher energy grade. A new type of power system of BCLG coupled with the gas turbine(GT) and ORC was proposed to achieve the high-value utilization of biomass energy. This system achieved the graded utilization of different grades of energy through the material/energy exchange between subsystems. Aspen Plus software was used to simulate the effect of oxygen/biomass ratio(λ) and compressor pressure ratio(P_R) on the power generation efficiency of the BCLG-GT system when corn straw, rice straw, and wheat straw were used as gasification fuels, respectively. The simulation results show that straw is the optimal gasification fuel for the BCLG-GT system among the three types of biomass, and the optimal simulation conditions are λ = 0.05 and P_R = 13. Based on the optimal operating conditions of the BCLG-GT subsystem, coupled with the ORC subsystem, the effects of the four organic fluids(R245fa, R134a, HCFC-123, and R-404A) and regenerative devices on the ORC system were further studied. The simulation results reveal that R245fa has higher practical value and better environmental friendliness, compared with R134a, HCFC-123, and R-404A. The net power output of the ORC system is increased by 13.37% after adding the regenerative device, and the net energy efficiency of the new BCLG-GT-ORC power system with the regenerative device reachs 35.48%. This study provids ideas and theoretical guidance for the design and optimization of BCLG units on an industrial scale.

    2023 05 v.29;No.153 [Abstract][OnlineView][HTML全文][Download 22692K]

  • Effect of acid-leached modification on the structure of USY zeolite and catalytic pyrolysis performance of coal

    WU Zhuozhuo;YANG Zhiyuan;JU Xiaoqian;LI Yinyan;DUAN Xinbo;ZHOU Anning;College of Chemistry and Chemical Engineering,Xi′an University of Science and Technology;Key Laboratory of Coal Resources Exploration and Comprehensive Utilization,Ministry of Natural Resources;

    Light aromatics(such as benzene, toluene, xylene, etc.) obtained from coal pyrolysis have significance for clean and efficient production of coal chemical industry. Based on commercial USY zeolite as the parent, this work investigates the types of acid, acid concentration on the influence of USY zeolite structure and coal catalytic pyrolysis performance. The texture and morphology of the modified zeolites were characterized by X-ray diffraction, scanning electron microscopy and N_(2 )adsorption-desorption, and the effect of acid treatment on the pore structure of USY zeolite was studied. The catalytic cracking effect of the modified USY zeolite catalysts on the Shenfu coal was studied by Py-GC/MS. The results show that the crystallinity of USY zeolites decreases gradually with the increase of acid concentration. Under the condition of maintaining the skeleton integrity of the USY zeolites, the biggest impregnated HCl concentration is 0.4 mol/L, H_2SO_4 and H_3PO_4 is 0.2 mol/L. HCl modification can improve the average pore diameter and mesoporous volume of USY zeolite. The acid-leached USY zeolites are favorable for the formation of light aromatics, especially naphthalenes, in coal pyrolysis. HCl-USY-0.4 has the best catalytic effect, and the relative contents of benzenes, toluene, xylene and naphthalenes are 11.39%, 9.36%, 11.68% and 31.27%, respectively.

    2023 05 v.29;No.153 [Abstract][OnlineView][HTML全文][Download 24511K]

  • Co/Ni/ZSM-5 catalytic reforming of pyrolysis gas and coal tar and its mechanism

    LIU Qianqian;ZHANG Yu;WANG Yufei;YAN Long;LI Jian;ZHANG Yating;College of Chemistry and Chemical Engineering,Yulin University;Shaanxi Key Laboratory of Low Metamorphic Coal Clean Utilization;School of Chemistry and Chemical Engineering, Xi′an University of Science and Technology;

    ZSM-5 zeolite catalysts were modified with different proportion Ni and Co prepared by excessive impregnation method and characterized by XRD, SEM-EDS, BET and NH_3-TPD. The effect of different proportions Ni/Co/ZSM-5 catalysts, the pyrolysis temperature and the catalyst dosages on the component of pyrolysis gas and coal tar of Shenfu coal were investigated. The results show that the total content of pyrolysis gas with Ni3Co5Z catalyst can be increased by 11.69 percentage points compared to raw coal, and the content of H_2 and CH_4 can be increased by 4.25 percentage points and 5.37 percentage points, respectively. The 650 ℃ is the best pyrolysis temperature, and the content of H_(2 )and CH_(4 )can be increased by 6.77 percentage points and 0.50 percentage points, respectively. However, the dosages of catalyst have little influence on the pyrolysis gas. Moreover, when the catalyst is Co_3Ni_5Z, the amount of catalyst added is 0.3 g, and the pyrolysis temperature is 600 ℃, the yields of aromatic hydrocarbons and phenols in coal tar are 5.91 percentage points and 3.35 percentage points higher than those in raw coal respectively. The acid amount of Ni/Co/ZSM-5 catalyst has close relation with the catalytic performance, a certain degree of acid amounts can promote the coal pyrolysis, increase the effective gas composition of the gas production and improve the quality of the coal pyrolysis oil.

    2023 05 v.29;No.153 [Abstract][OnlineView][HTML全文][Download 58183K]

  • Distribution and hydropyrolysis of the covalent bonds in oil shales

    ZHOU Bin;ZHAO Xiaosheng;LI Zhe;ZHOU You;WANG Yifei;ZHAO Lulu;New Energy Technology Development Center,National Institute of Clean and-Low-Carbon Energy;College of Chemistry and Chemical Engineering,Cangzhou Normal University;

    The utilization of oil shales earns popularity due to the shortage of petroleum of China. However, the clean and efficient conversion of oil shales is limited due to the complexity of the organic matters in oil shales. To understand the structure-reactivity relationship of oil shales in a micro-level, this work studied the distribution characteristics of the covalent bonds of 8 oil shales, and used Artificial Neural Network(ANN) to precisely quantify the relationship between bond distributions, reaction temperature, reaction time and the abundance of free radicals that were generated in pyrolysis and then captured by H from hydrogen-donor solvent. From the sensitivity analysis, the C_(al)—C_(al), C_(al)—C_(ar), C_(ar)—C_(ar), C_(al)—O, C_(ar)—O and ■ in oil shales could facilitate the generation and hydrogenation of free radicals in hydropyrolysis. While the C_(al)· and C_(ar)· generated from the breakage of C_(al)—H and C_(ar)—H in oil shales tend to take part in the coupling and condensation reactions. Meanwhile, H· from the breakage of C_(al)—H and C_(ar)—H can capture free radicals, decreasing the hydrogenation effect of hydrogen-donor solvent. And the breakage of O—H of oil shales in the reaction is of low-possibility. The above results to some degrees highlight the mild thermal-conversion technologies of oil shales, coals and biomass.

    2023 05 v.29;No.153 [Abstract][OnlineView][HTML全文][Download 13655K]

  • Material composition and asphalt modification effect of coal based superhard asphalt

    SHEN Quanjun;WEI Hui;YANG Yaohui;FAN Liang;WEI Jianming;Shandong High-speed Group Innovation Research Institute;Shandong Transportation Institute;National Institute of Clean and-Low-Carbon Energy;

    In order to ensure the application effect of coal based super hard bitumen(SHA) in asphalt modification, the phase composition of SHA was detected by means of X ray diffraction, infrared spectrum and chemical composition analysis. The performance indexes of SHA modified asphalt were tested by means of penetration test, softening point, viscosity and aging test method. Combined with the previous research, SHA was compared with 3 kinds of naturalasphalt, and the characteristics of SHA phase composition and asphaltene structure parameters were discussed. The advantages and disadvantages of SHA as asphalt modifier were analyzed, and the relationship between SHA material composition and performance index of modified asphalt was summarized. The results show that SHA has the same four components as asphalt and natural asphalt, and the asphaltene content is low(19.7%), and the content of gum is high(23.1%). The unsaturated degree of SHA molecular structure is much higher than that of petroleum pitch, and its polarity is large. Its asphaltene has high aromatization degree and is an aromatic structure with high condensation degree. The aromatic layer spacing and saturated part spacing of asphaltene are basically the same as those of petroleum asphalt and natural asphalt. When SHA is used as asphalt modifier, the performance of asphalt modified asphalt is more consistent with that of natural asphalt modified asphalt. With the increase of the amount of SHA modifier, the penetration rate of modified asphalt decreases, the softening point increases, the ductility decreases, the temperature sensitivity of asphalt decreases, but the aging resistance of modified asphalt is improved. The asphalt modification effect is closely related to the four component content and insoluble content of the modifier.

    2023 05 v.29;No.153 [Abstract][OnlineView][HTML全文][Download 14206K]

  • Performance of Mo_2C/Cu co-loaded TiO_2 photocatalytic CO_2 reduction

    LI Yang;YU Huijian;JIN Lijun;YANG He;LI Dekang;HU Haoquan;Institute of Coal Chenical Engineering,School of Chemical Engineering,Dalian University of Technology;

    Light-driven CO_2 reduction technology is expected to reduce CO_2 emissions and provides high-value chemical fuels at the same time to alleviate the pressure during energy transition. Among them, the development of highly active photocatalysts is the key to realize the application of this technology. Loading noble metals is an effective way to improve their photocatalytic efficiency. However, the high cost and scarce reserves of noble metals limit their large-scale use. Therefore, the development of precious metal substitutes is great significance for photocatalytic CO_2 reduction. Mo_2C is a transition metal carbide with an electronic structure similar to that of noble metal. Mo_2C and Cu co-loaded TiO_2 photocatalysts were prepared by urea reduction. Their photocatalytic activity under UV light was evaluated by combining physical and chemical properties analysis. The results show that after loading Mo_2C on TiO_2,the production of H_2 and CH_4 is significantly promoted in the process of CO_2 catalytic conversion, while Mo_2C and Cu coprecipitation can inhibit the production of H_2 and promote the further conversion of CO_2 to CH_4. After four hours of illumination, its cumulative CH_4 production reaches 76.1 μmol/g, which is 5.6 times that of pure TiO_2. Cu deposition can promote CO_2 adsorption and inhibit water vapor adsorption, thereby reducing H_2 generation. The co-deposition of Mo_2C and Cu can effectively reduce the bandgap width of TiO_2,inhibit the recombination of photo generated electrons and hole pairs, and promote the separation and transfer of photogenerated charges on the catalyst surface, thereby improving its photocatalytic activity.

    2023 05 v.29;No.153 [Abstract][OnlineView][HTML全文][Download 54232K]

  • Design of combined heat and power supply system based on coal gas SOFC(IGFC-CHP) system

    LUO Liqi;XIE Guangyuan;WANG Shaorong;School of Chemical Engineering, China University of Mining and Technology;

    Coal is still the main energy resources in our country before the realization of the "carbon peak and carbon neutrality targets". Therefore, it is vital to improve the efficiency of energy utilization. Solid oxide fuel cell(SOFC) is a kind of highly efficient energy conversion device. Coal based SOFC would make the maximum utilization of coal resources and contribute to the smooth transition of energy from fossil to the renewable ones. However, the coal produced by the traditional gasification plant contains ash, sulfur and other impurities, which can not be used as the fuel of SOFC directly. This work designs and simulates the gasification and purification process of coal which is suitable to supply to SOFC, as well as the fuel cell power generation and exhaust heat recovery system. The modules of coal cracking, coal gasification, coal purification, gas cooling and heat recovery, SOFC power generation, tail gas combustion, and hot water supplying are modeled by Aspen Plus software. The electrochemical processes of SOFC power generation and gasification processes are simulated by the Fortran module of software. As results, a suitable gas gasification module with 70.1% gasification efficiency is obtained which can be directly connected to SOFC for power generation. The gas mainly contains 58% CO and 32% H_2. It is found that the overall energy utilization ratio of the simulation system can reach 78.58% with 37.54% net power generation efficiency of SOFC and 35.11% hot water efficiency under the proposed working conditions. Through sensitivity analysis, it is found that the use of appropriate fuel utilization rate and fuel flow can effectively reduce the operating cost of the system, and the air excess ratio is as big as possible within the selectable range. The whole process of combined heat and power supply system(IGFC-CHP) based on coal gas SOFC power generation technology is modeled and studied in this work, which is significant to the realization of IGFC-CHP technology.

    2023 05 v.29;No.153 [Abstract][OnlineView][HTML全文][Download 22777K]

  • Experiment of co-combustion characteristics of different biomass and pulverized coal at high blending ratio

    LI Meijun;Beijing Tiandi Rongchuang Technology Co.,Ltd.;National Energy Technology &Equipment Laboratory of Coal Utilization and Emission Control;

    Biomass, as a renewable energy source, has the advantages of abundant content, easy ignition and low pollutant emission, but has the disadvantages of low energy density and high moisture. Coal powder has the advantages of high energy density and disadvantages of difficult ignition and high pollutant emission. Combining firing carbon neutral energy biomass to pulverized coal at a high blending ratio(the mass ratio of biomass to coal is greater than 5∶5) can effectively solve the problems of the low utilization rate and low energy density of biomass, and the difficult ignition and high pollutant emissions of coal, improve energy utilization rate, achieve the goal of energy conservation and emission reduction, which has become a new energy utilization technology. At present, scholars merely investigate the co-combustion characteristics at low blending ratio(less than 5∶5), deeper insight into the co-combustion characteristics of biomass and coal at high blending ratio is required. The combustion characteristics and kinetic characteristics of coal powder and different biomasses(corn stalk, rice stalk, corn cob, cotton and poplar sawdust) at distinct blending ratios(0∶10, 5∶5, 6∶4, 7∶3, 8∶2 and 10∶0) were studied by thermogravimetric analysis. The effects of biomass species and blending ratio on fuel heat loss characteristics, characteristic temperature, reaction kinetics, burnout characteristics and combustion characteristic index of mixed samples were analyzed, and the optimal blending ratio of different biomass was determined. The results show that the weight loss curve of the mixing samples show three stages: water-loss stage, volatile-combustion stage and fixed carbon-combustion stage. The maximum weight-loss rate decreases in the first stage and increases in the second stage, and the combustion process advances. The ignition temperature and burnout temperature decrease by about 100 ℃ and 40 ℃, respectively, compared with that of pulverized coal. Under the synergistic effect of promotion and inhibition, the ignition temperature of poplar sawdust increases gradually with the increase of mixing proportion. Corn straw, rice stalk and cotton decrease firstly and then increase, and the minimum is at 7∶3,while corn cob gradually decreases. And the burnout temperature of all species decreases. The activation energy of single biomass is lower than that of pulverized coal. In the first stage, the rankingis rice stalk, poplar sawdust, corn stalk, cotton and corn cob from the largest to the smallest, while in the second stage, the ranking is poplar sawdust, cotton, corn cob, rice stalk and corn stalk. With the increase of blending ratio, cotton and poplar sawdust increases first and then decreasesin the first stage, while corn cob and rice stalk decrease gradually, and both of them are minimum at 8∶2. Corn stalk decreases first and then increases after blending, and the minimum is at 6∶4. In the second stage, corn cob, poplar sawdust and cotton gradually decrease, and the minimum at is 8∶2. Corn straw and rice stalk decrease first and then increase, and the minimum value is at 6∶4 and 7∶3, respectively. The changes of burnout characteristic index are different. Cotton has the strongest inhibition effect at 7∶3, while corn straw, rice stalk, corn cob and poplar sawdust have the strongest promotion effect at 8∶2, 6∶4, 6∶4 and 8∶2, respectively. The comprehensive combustion characteristic indexes of single biomass from the largest to the smallest are corn cob, cotton, corn stalk, rice stalk and poplar sawdust, which are about 10.0 times, 7.7 times, 7.0 times, 6.5 times and 6.2 times of coal powder. Corn cob and cotton reach the maximum value at 8∶2, and rice stalk and corn straw reach the maximum value at 7∶3. The combustion characteristic index has almost no change when the mixing proportion is changed in a small scope.

    2023 05 v.29;No.153 [Abstract][OnlineView][HTML全文][Download 16398K]

  • Mechanism of SO_2 removal by Mn-Ce high-content iron ash

    TAN Yuyao;ZHENG Xianrong;TIAN Guangyuan;LI Yongjia;College of Electrical and Power Engineering,Taiyuan University of Technology;

    Mn-Ce high-content iron ash desulfurizer was prepared by hydration impregnation method and used to remove SO_2 from the simulated flue gas. The role of metal components in desulfurization, and the effects of desulfurization temperature and atmosphere on the SO_2 removal performance were systematically studied. The results show that Mn-Ce/5FACa has good SO_2 removal performance at 300 ℃ in the simulated flue gas(5% O_2,500 mg/m~3 SO_2,167 mg/m~3 NO and N_2 balance),with the breakthrough time of 241 min and sulfur capacity of 108.45 mg/g. The SO_2 removal by Mn-Ce/5FACa is the result of the combined effect of adsorption removal and chemical reaction with proportion of 30% and 70%,respectively. The results of adsorption kinetics reveal that chemisorption plays a main role in the adsorption removal of SO_2 by adsorption of Mn-Ce/5FACa, and the kinetics of adsorption reaction follows the quasi-second-order kinetic equation model. The addition of Mn and Ce improves the oxygen storage and redox ability of Mn-Ce/5FACa. The combined action of Mn, Ce and high-content iron ash is conducive to the formation of K_2FeO_4 and MnAl_2O_5. Fe(VI) in K_2FeO_4 provides oxidation sites in the surface of Mn-Ce/5FACa and promotes the oxidation reaction of SO_2. The chemisorption is mainly affected by the desulfurization temperature, and the desulfurization capacity of Mn-Ce/5FACa for SO_2 increases firstly and then decreases with the increasing temperature. O_2 plays a key role in the chemical reaction desulfurization, and the oxidation ability of K_2FeO_4 is affected by the content of O_2. NO may promote the chemical reaction between Mn-Ce/5FACa and SO_2,and the desulfurization ability increases with the increase of NO concentration.

    2023 05 v.29;No.153 [Abstract][OnlineView][HTML全文][Download 17899K]

  • Analysis of pollutant emissions from 660 MWe pulverized coal boiler combustion coupled with biomass gas

    WANG Aijun;HAN Weizhe;WU Yichao;LIU Haoming;ZHANG Xiaotao;College of Energy and Power Engineening,North China University of Water Resources and Electric Power;

    In order to analyze the influence of a pulverized coal furnace co-firing with biomass gas on the operation performance of the coupled boiler, a biomass gasification coupled coal-fired boiler system model was built based on a 660 MWe coal-fired boiler and a 30 t/h biomass gasifier. At rated working conditions, three types of biomass, namely pine wood, wood chips, and sludge, were selected for gasification process research. The biomass gases obtained on the optimal gasification condition were fed into the boiler for mixed combustion, the influence law on boiler operation and combustion products generation from different biomass gases co-firing was researched. The results show that the gasification heat efficiency of biomass can reach more than 90% at the best air-fuel ratio. Compared to the pure coal combustion conditions, the furnace combustion temperature of the coupled system decreases, with a highest drop value of 9.43 ℃. The combustion mixed with biomass gas makes the boiler efficiency slightly decrease, but the biomass utilization efficiency of the coupled boiler system can still reach 84% above. In addition, the multi-fuel combustion can reduce CO_2 emissions, and the CO_2 cut from co-combustion with pine-gas is the largest of all three material, with the value of 2.62×10~5 t/a. The amount of NO_x reduced in the coupled system is significantly related to the furnace combustion temperature and the CH_4 concentration in biomass gas, with a maximum drop value of 167.16 mg/m~3 from blending a wood chip gas. The SO_x mass concentration is relevant to the composition of biomass gas and the lowest value is from co-firing a pine gas, with a drop value of 330.22 mg/m~3, compared to the pure coal combustion.

    2023 05 v.29;No.153 [Abstract][OnlineView][HTML全文][Download 4931K]

  • Characteristic of waste heat flash desulphurization wastewater of 330 MW unit under variable load

    WANG Fei;LIU Fengrui;YANG Fengling;YANG Wensheng;LIU Huijun;State Environmental Protection Key Laboratory of Efficient Utilization Technology of Coal Waste Resources,Shanxi University;Shanxi Huarentong Electric Power Technology Co.,Ltd.;

    At present, zero discharge of high salinity desulphurization wastewater has become a bottleneck problem to be solved urgently in power plant, and flash-condensing-crystallization-curing of high salinity wastewater by using low temperature waste heat of unit is one of the key technologies to achieve zero discharge of desulphurization wastewater. In view of the problems caused by the unstable water quality condition, treatment capacity and heat source of desulphurization wastewater caused by variable load operation of the unit after the current grid-connected renewable energy such as wind and light, low efficiency of low-temperature residual heat flash concentration of desulphurization wastewater and easy scaling, etc., effects of low temperature negative pressure steam flow rate, wastewater treatment capacity, concentrated liquid ratio, wastewater recovery rate and other factors on the treatment of desulfurization wastewater by three-effect evaporator in the process of 60% to 100% variable load of the power plant was studied. According to the data analysis, the buffer tank should be set in front of the three-effect evaporation system to avoid system damage caused by excessive flow rate, and the wastewater recovery rate can reach 80%~90% when the system water intake is not more than 200 t/d. Low-temperature negative pressure steam flow fluctuates between 700 and 1 000 kg/h, so the flowmeter should be installed at the first condensate tank, and the low-temperature negative pressure steam production should be adjusted according to the water intake of the system, so as to avoid the waste of heat source caused by excessive low-temperature negative pressure steam production; in strict accordance with the density meter at the outlet of the three-effect evaporation system, the concentrated liquid is discharged immediately when the density reaches 1.35 g/mL. By the analysis of the condensate water generated during the stable operation of the three-effect evaporation system, the content of chloride ions reaches 1.56 mg/L, which can be used as the circulating supply water of the power plant. Besides, the daily power consumption of the system is 4 000 kWh. Without considering the personnel cost, depreciation cost, maintenance cost and other expenses, the cost of the three-effect evaporation system for treating 1 m~3 of wastewater is 5-10 yuan.

    2023 05 v.29;No.153 [Abstract][OnlineView][HTML全文][Download 14462K]

  • Prediction of inner wear of 410 t/h CFB boiler blended with petroleum coke oven

    LU Song;YAN Rui;LOU Bo;School of Electric Power,South China University of Technology;

    Circulating fluidized bed(CFB) boiler is a highly efficient and clean combustion technology with a wide range of applications, but the wear problem has always plagued the long-term operation of the CFB boiler. At present, the wear conditions in different areas are mostly master through operational survey experience or by using numerical simulations to obtain velocity and concentration fields, few scholars have studied quantitatively the wear conditions of different areas in the boiler through theoretical methods. The wear is mainly affected by the velocity and concentration of dust airflow. An attempt was made to obtain the velocity and concentration of fly ash particles in the vicinity of the water-cooled wall heating surface under 50 sets of operating conditions using hydrodynamic software simulations in this study, the relative wear prediction model of GA-BP neural network with the structure of 5-13-12 was established by BP neural network and genetic algorithm(GA) for the CFB boiler mixed with petroleum coke in a petrochemical plant. In turn, the effects of five operating parameters, namely the air volume of the air distribution plate, the primary air volume, the secondary air volume, the fuel volume, and the blending ratio, on the wear in different areas of the furnace chamber were analyzed. The results show that the prediction results of the test set are in good agreement with the wear conditions surveyed on-site, which verifies the feasibility of using GA-BP neural network to establish a wear prediction model and can guide the anti-wear operation, under the condition of ensuring the normal operation of the boiler, appropriately reducing a certain amount of fluidized air of the air distribution plate, reducing the amount of primary and secondary air and fuel in the dense phase area, and appropriately increasing the petroleum coke blending ratio, which can reduce the wear of the heated surface in the furnace.

    2023 05 v.29;No.153 [Abstract][OnlineView][HTML全文][Download 38845K]

  • Experimental study on centrifugal separation and calcination of coal-derived kaolin by Design Expert

    DU Pengtao;ZHAO Shiyong;LIANG Xiao;School of Chemistry and Chemical Engineering,Xi′an University of Science and Technology;Xi′an Northwest Research Institute of Non-ferrous Geology Co.,Ltd.;

    The kaolin content of gangue in the Heidaigou ming area is as high as 70%. Herein, from the perspective of comprehensive utilization of coal resources, in order to improve the calcination whiteness of coal-derived kaolin, a method of centrifugal for separation was used to remove the chromogenic impurities with high-density. To achieve this, this work performed orthogonal design by Design Expert and adopted the Box-Behnken model. Consequently, the influence of centrifugal speed, feeding rate, feeding concentration and feeding time on the calcination whiteness and concentrate yield was explored and the quadratic equation relationship model was fitted. Further, the response surface plots of calcination whiteness and concentrate yield with significant factors were given. It was found that the whiteness of calcination was mainly affected by the centrifugal speed. With the increase of the rotation speed of the drum, the whiteness of the calcination first increased and then decreased. The yield of concentrate was mainly affected by the feeding time. With the extension of feeding time, the yield of concentrate increased linearly. Finally, combined with the simulation results of Design Expert, the optimal centrifugal separation conditions were analyzed and explored. When the centrifugal speed is 800 r/min, feeding rate is 8.4 L/min, feeding concentration is 20%, and feeding time is 100 s, the optimal calcination whiteness(78.80%) and concentrate yield(86.31%) of kaolin can be obtained.

    2023 05 v.29;No.153 [Abstract][OnlineView][HTML全文][Download 6663K]

  • Current situation and development trend of coal water slurry preparation technology

    ZHANG Guoqing;DU Shanzhou;HUANG Yongbo;ZHANG Daixin;WEI Lubin;HUANG Zhong;Department of Energy and Power Engineering,Tsinghua University;School of Chemistry and Environmental Engineering,China University of Mining and Technology-Beijing;Shenhua Zhungeer Energy Co.,Ltd.;

    Preparation process is an important factor to determine the properties of coal water slurry, and then affect its storage, transportation and use. The latest research progress in the preparation process of coal water slurry was reviewed in recent years, including the preparation processes of different types of coal water slurry and the use of traditional Chinese medicine agent systems and particle size grading methods in the preparation process. Coal water slurry is divided into traditional coal water slurry and environmentally friendly coal water slurry according to the different raw materials used for slurry production. Traditional coal water slurry refers to the coal based components that are the main raw materials for slurry production, such as clean coal coal water slurry, low rank coal water coal slurry, and coal slurry water coal slurry. Environmentally friendly coal water slurry is a new way of resource utilization and comprehensive utilization of waste by blending raw materials such as biomass, industrial waste liquid, and solid waste, which can fully utilize the heat value contained in the waste and reduce disposal costs. The performance requirements of coal water slurry in application scenarios such as conventional boilers, circulating fluidized bed boilers, and gasifiers were analyzed and compared. Conventional boilers require low viscosity and fine particle size of coal water slurry, and the preparation process usually adopts a single stage grinding process. Circulating fluidized bed boilers, due to their unique suspended fluidized bed combustion method, relax the requirements for the particle size and viscosity of coal water slurry, which can reduce the consumption of high-density bed materials through non slag discharge operation, improve the inclusivity of ash content and ash melting point of raw coal for slurry production. Gasification requires higher performance of coal water slurry than combustion. The gasification furnace requires high slurry concentration and good reaction activity of coal water slurry, and to ensure good atomization effect, and the gasification of coal water slurry requires fine particle size and low slurry viscosity of coal water slurry particles. The development trend of coal water slurry preparation technology was prospected, and technical directions such as exploring low rank coal modification and upgrading methods, the influence of ultrafine particles on slurry properties, and expanding the types of slurry waste that can be mixed were proposed.

    2023 05 v.29;No.153 [Abstract][OnlineView][HTML全文][Download 14309K]
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