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Development Status and Trend of Hydrogen Energy in Cement Industry under Background of Carbon Peaking and Carbon Neutrality
Collect
LI Huajun, YANG Huanying, MA Jiaomei, ZHAO Liang, WANG Jiashuo
Cement Technology, 2023, 1(3): 15-24.
doi:10.19698/j.cnki.1001-6171.20233015
Hydrogen energy has the characteristics of clean and pollution-free, high energy density per unit mass, etc., and is regarded as one of the most promising clean energy in the 21st century. Its application in cement, thermal power, automobile and other fields has become the focus of technical research in various countries. The development status of hydrogen energy in cement industry at home and abroad is mainly the direct combustion of hydrogen as fuel to generate energy and the combined use of hydrogen and carbon utilization technology (CCUS). The key of hydrogen direct combustion technology is to increase the substitution rate of alternative fuels to fossil fuels by adding hydrogen. The key to the combined use of hydrogen and CCUS lies in the capture of CO2 and the development of high efficiency catalyst for the hydrogenation of CO2 to methanol. Combined with the existing spontaneous combustion, early combustion, tempering, NOX emissions of hydrogen energy combustion in the hydrogen internal combustion engine, gas turbines and other industrial fields, the current development situation and future trend of hydrogen energy in our cement industry are analyzed.
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Technology and Engineering Application of Collaborative Treatment of Urban Dried Sludge with Cement Kiln
Collect
CHEN Ruizhang, TAO Congxi, ZHAO Bisheng, LIU Chao, LUO Hui
Cement Technology, 2023, 1(3): 25-31.
doi:10.19698/j.cnki.1001-6171.20233025
The Guangzhou Yuebao cement collaborative disposal of urban dried sludge project adopts the technical route of "drying in the sewage treatment plant+collaborative disposal in cement kilns". After the municipal sludge is deeply dehydrated and electrically dried by the sewage treatment plant, the final moisture content of the sludge decreases to below 40%. The dried sludge is then discharged, transported, crushed, fed, and dedusted and deodorized through a collaborative disposal system. The amount of urban dried sludge disposed reaches 600t/d, which is equivalent to approximately 1 800t/d of wet sludge. The technological advantage is obvious. Since the implementation and operation of the project, the emission of dioxins has been 0.037ng TEQ/m3, far below the national standard emission limit of 0.1ng TEQ/m3. The annual coal saving is about 44 000 tons, and the coal saving income is more than 37.5 million yuan. Based on the estimated CO2 emission of 2.0t per ton of bituminous coal, the annual CO2 emission can be reduced by about 88 000 tons.
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Analysis and Solution Measures on the Wear Mechanism of SCR Catalyst in Cement Kiln
Collect
PENG Xiaoping, WANG Yonggang, CHENG Zhaohuan, TANG Xinyu
Cement Technology, 2023, 1(3): 32-37.
doi:10.19698/j.cnki.1001-6171.20233032
During the operation of the SCR denitrification system in the cement kiln, the problem of rapid wear of catalyst apparent gradually. The main reasons for catalyst wear in the cement kiln SCR system include high dust content, irrational original design, uneven flow field caused by dust blockage, irrational blowing system, and poor wear resistance of the catalyst itself. Through theoretical analysis, the biggest influencing factor for catalyst wear is the flue gas flow rate, which is related to the cubic power of the flue gas flow rate. To alleviate the problem of rapid catalyst wear, it is usually solved by selecting a reasonable catalyst, increasing the resistance to wear performance of the catalyst itself, designing a reasonable reactor flow field by conducting numerical simulations, improving the catalyst service environment, and adopting a reasonable soot blowing system. This ensures the stability of the SCR system and meets the environmental requirements of ultra-low emissions.
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Design and Application of Dual DC Drive Speed Regulation System for Rotary Kiln
Collect
GU Wei
Cement Technology, 2023, 1(3): 38-43.
doi:10.19698/j.cnki.1001-6171.20233038
The reasonable design of the DC speed regulation system for cement rotary kiln is related to the stable operation of the rotary kiln. A 6 000 t/d clinker production line adopts a dual DC drive speed regulating system, which is equipped with a three winding rectifier transformer and two DC speed regulating devices. The primary winding of the rectifier transformer is connected in a triangle, one of the secondary winding is connected in a triangle, and the other is connected in a star. The two DC speed control devices directly supply power to the two DC motors. By calculating the capacity of the rectifier transformer and the starting armature current of the DC speed regulation device, the selection of equipment such as the DC speed regulation device and the main circuit breaker is carried out. The DCS control system is responsible for measuring, controlling, and protecting the dual DC speed regulation system. Since the operation of the dual DC speed regulation system, all assessment indicators are better than the contract requirements, and it is suitable for 5 000t/d and above clinker production lines.
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Measurement Analysis and Repair Method of Tire Deflection
Collect
HU Tao, HE Zhenghui, LIU Gang, WANG Wei, SHE Xiangzhong
Cement Technology, 2023, 1(3): 44-49.
doi:10.19698/j.cnki.1001-6171.20233044
The tire produces a certain degree of deflection during movement, which affects the stable operation of the rotary kiln. By using the laser rangefinder to measure the belt deflection, it divides a rotation cycle of the kiln shell into 32 equal parts, takes the average value of each distance in a circle, and calculates the belt deflection using the minimum dichotomy method. Based on the calculation results, it analyzes the causes of tire deflection, monitors the temperature changes of the cylinder and uneven wear of the tire/supporting wheel, replaces the cylinder at the tire and adjusts the online grinding of the tire to restore normal tire deflection and ensures long-term stable operation of the rotary kiln.
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Energy Saving and Consumption Reducing Modification for Pulverized Coal VRM Grinding
Collect
LIU Di, DU Xin, WU Xiao, LIU Chang
Cement Technology, 2023, 1(3): 50-55.
doi:10.19698/j.cnki.1001-6171.20233050
According to raw coal characteristics, in order to solve the problems of pulverized coal grinding system of high resistance, low separator efficiency, high system power consumption and insufficient capacity of supporting kiln, a new moving blade and static blade, sealing structure and VRM pressurization rod are developed and designed. After modification, pulverized coal cyclic load inside VRM is reduced and obtain 500~1 000Pa low for system resistance. Those effects make the system power consumption reduced by 2.0~4.0 kW·h/t, and the mill output increased by 10%~20%, ensuring kiln higher efficient operation.
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Upgrade of ATOX50 Raw Meal Roller Mill for Energy Saving and Consumption Reduction
Collect
WANG Hai, HU Xiaodong, XU Han, WANG Shuangjun
Cement Technology, 2023, 1(3): 56-60.
doi:10.19698/j.cnki.1001-6171.20233056
When ATOX50 Raw Meal Roller Mill for a 5 000t/d cement clinker production line was running at the initial stage, the output could not meet the design requirements, the roller liner was seriously worn, and the power consumption of grinding reached 22kW·h/t, therefore the normal production of rotary kiln is restricted seriously. By replacing the ceramic bushing to prolong the service life of the grinding roller, using the material seal bin combined with the air lock feeder of the runner, increasing the air lock device of the slag discharge port to reduce the air leakage of the system, upgrading the original powder separator to LZT type powder separator, optimizing the ash return line of the powder selecting machine, reducing the inner circulation of the material mill, improving the scraper plate and the dust collector lifting valve cylinder to raise the running efficiency of the Mill, strengthening the process operation, and reducing the vibration of the mill, the power consumption of raw meal grinding system is reduced to 17kW·h/t. It optimizes the grinding pressure and the particle size of raw material.
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Renovation Practice of Energy Saving and Consumption Reduction for a 6 000t/d Cement Clinker Production Line
Collect
BIE Jianmin, WANG Hui, WANG Lijun, GUO Yongqiang
Cement Technology, 2023, 1(3): 61-66.
doi:10.19698/j.cnki.1001-6171.20233061
A 6 000t/d cement clinker production line in China implemented a series of transformation practices such as preheater resistance reduction, calciner volume expansion, staged combustion and overall replacement with a fourth-generation intermediate roller crusher cooler. After the renovation, all the operating indexes of the kiln system were significantly improved, and the graded combustion combined with SNCR denitrification system achieved the ultra-low emission of NOX<50mg/Nm3, and the amount of denitrification ammonia (concentration 20%) was about 3.6kg/t, which achieved the expected effect.
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Renovation of the Drive System of Rotary Kiln on 10 000t/d Cement Production Line
Collect
WANG Kexue, JI Liang, WANG Mingqian
Cement Technology, 2023, 1(3): 67-70.
doi:10.19698/j.cnki.1001-6171.20233067
The original drive system of ?6m×90m rotary kiln equipment of 10 000t/d cement production Line used in Xuzhou CUCC could no longer meet the requirement of company's cost reduction and efficiency demand, energy conservation and emission reduction. Based on this problem, the rotary kiln will have a maximum speed of 5r/min by reselecting the gearbox, while maximum keeping the installation size of drive system consistent. Through the optimization design of the lubricating oil station, the problems of insufficient cooling and lubrication of gearbox and high oil temperature can be solved. Furthermore, the problem of abnormal vibration under leaning load can be solved by readjusting shrink disc, torque arm and universal joint coupling. After solving above problems, the rotary kiln equipment runs stably and meets the requirements of system to increase production and speed.
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Analysis of Abnormal Cement Setting Time Caused by Desulfurized Gypsum
Collect
ZHONG Yu, ZENG Rong, LAO Lilin
Cement Technology, 2023, 1(3): 73-78.
doi:10.19698/j.cnki.1001-6171.20233073
Desulfuration gypsum is a commonly used cement retarder, and accidents with abnormal cement setting time caused by the use of desulfuration gypsum often occur. By using experimental methods such as XRD, XRF, dissolution characteristic analysis, and DSC TG, the cause of abnormal cement setting time caused by the use of desulfurization gypsum in a certain enterprise was analyzed. The analysis results show that the presence of an appropriate amount of impurity ions in desulfuration gypsum has a certain improvement effect on the retarding effect of cement; desulfuration gypsum containing a large amount of hemihydrate gypsum has high activity, fast dissolution, high solubility, and fast retarder effect. Before using industrial by-product desulfurization gypsum in cement enterprises, relevant physical and chemical analysis should be conducted to optimize the addition ratio of desulfurization gypsum and stabilize cement quality.
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Application of Neutron Activation Online Analyzer in Cement Raw Meal Batching
Collect
LU Guoqiang, JIANG Peng
Cement Technology, 2023, 1(3): 79-86.
doi:10.19698/j.cnki.1001-6171.20233079
The quality of cement raw meal ingredients directly affects the quality, output and energy consumption of clinker, at present, most of the raw material proportioning control of domestic cement production lines adopts the quality control system based on laboratory X-ray fluorescence analyzer, and this paper analyzes the analysis lag, poor sample representativeness, human factor error and other problems of this quality control system. The neutron activation online analyzer adopts instantaneous γ neutron activation analysis technology, which can identify the types and contents of material elements by detecting the energy and intensity of characteristic γ rays, so as to realize online real-time quality control of cement raw meal batching, and can perform 60 raw meal proportioning analysis calculations and adjustments per hour. After the application of neutron activation on-line analyzer to cement production, the static calibration and dynamic operation calibration results show that the neutron activation online analyzer has stable performance, high detection accuracy, and improved the qualification rate and stability of raw meal and clinker rate values.
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Research Progress of Magnesium Phosphate Cement
Collect
LIU Ruinan, WANG Liyan
Cement Technology, 2023, 1(3): 87-90.
doi:10.19698/j.cnki.1001-6171.20233087
Magnesium phosphate cement has a short setting time and high early strength, and has broad prospects in civil buildings such as airport runways, tunnels, mines, and emergency repairs of national defense projects. However, magnesium phosphate cement hydrates very quickly and has a very short setting time, resulting in the inability to carry out engineering construction. This article summarizes the new achievements in the influence of factors such as raw materials, retarders, and admixtures on the setting time of magnesium phosphate cement at present, as well as new measures to improve the compactness, adhesion, and frost resistance of magnesium phosphate cement. It also looks forward to the development prospects of magnesium phosphate cement.
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Research Progress on Effect of Fluoride Containing Sludge on Setting Time of Clinker
Collect
FENG Yun, LI Zhen, ZHANG Wentao, LI Jia, ZHAO Feng
Cement Technology, 2023, 1(3): 91-96.
doi:10.19698/j.cnki.1001-6171.20233091
The setting time of the cement produced by the proportioning of fluoride containing sludge will be prolonged in the use process. The use case and relevant test results in the precalciner kiln show that the setting time of the clinker can be effectively improved by properly adjusting the three ratio value of clinker and the amount of fluoride containing sludge in the production process of clinker, reasonably controlling the content of Fe2O3, F- and CaSO4 in the raw meal, and controlling the mineral composition of the clinker. If fluoride sludge is stably used in cement kiln for collaborative disposal and production of clinker, about 72 million tons of fluoride sludge can be disposed annually according to the current actual cement production capacity, with significant energy saving and emission reduction effect.
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