Catalytic Combustion Of Pulverized Coal And Its Industrial Test In Cement Kiln

In recent years,a large amount of coal is consumed by industry,which exacerbates environmental problems such as acid rain and smog.Coal consumption in the cement industy was 195 million tons in 2019.How to reduce coal consumption in the cement industry and utilize coal resources with high efficiency is a problem that needs to be solved urgently.Existing studies have shown that catalyst can promote the release of volatile matter in coal,reduce the activation energy of the combustion reaction of fixed carbon,and increase the burnout rate of coal significantly.However,the existing coal-burning catalysts are mostly designed for power industry,they are not suitable for the cement industry.In order to enhance the applicability of coal-burning catalysts and improve the combustion performance of coal used in the cement industry,the relationships between coal quality and coal ignition temperature,maximum weight loss rate,combustion intensity and burnout temperature were discussed,the effects of metal ions on coal used in the cement industry were studied,and the catalyst formulation of typical coal was optimized.The catalytic mechanism was revealed through the analysis of coal organic structure and combustion kinetic,and the industrial test of coal catalytic combustion was conducted.The research significances are summarized in detail as follows:The influences of coal volatile content and ash content on coal combustion characteristic values was discussed through coal quality analysis and Thermogravimetry/Differential Scanning Calorimetry?TG-DSC?test of coal used in cement industry.The ignition temperature,maximum weight loss rate,combustion intensity and burnout time of coal was mainly related to the volatile matterof coal.The linear regression equations are T_i=-5.76V_ad+590.92,?dw/dt?_max=-0.14V_ad+9.75,I=-0.05V_ad+2.76 and?t=0.40V_ad+8.10.The regular relationship between the ash content of coal and the characteristic values of coal combustion were not observed.But after removing the minerals in bituminous coal,ignition temperatures were increased by 3-10?,the maximum weight loss rates were increased by 2.1-2.6%/min,and the combustion intensities were increased by 0.4-1.1m W·mg^-1·min^-1,the burnout temperature was reduced by 25-35?.The TG-DSC test was used to study the effects of metals on coal combustion performance and reaction kinetic parameters,and infrared spectra analysis was used to analyze the effect of metal ions on the organic structure of coal.The catalytic effects on coal combustion aere different among the metal ions.For bituminous coal,significant reduction in ignition temperatures?reduction max to 23.9??and burnout temperatures?reduction max to 33.7??)was caused by Cu²⁺,and significant increase in maximum weight loss rates?increase ratio max to 16.99%?and combustion intensities?increase ratio max to 37.39%?was caused by Pb²⁺.Cu²⁺can significantly improve the combustion performance of anthracite.For WYM-1,Cu2⁺can reduce the ignition temperature?reduction 32.1??and burnout temperature?reduction 28.8??,increase the maximum weight loss rate?increase ratio 37.40%?and combustion intensity?increase ratio 254.72%?.Under the experimental conditions,the optimal catalyst formulation of YM-1 was 0.6wt%Cu?NO₃?₂,0.6wt%Li NO₃ and 0.4wt%Zn?NO₃?₂,and the optimal catalyst formulation of WYM-1 was 0.6wt%Cu?NO₃?₂,0.4wt%Al?NO₃?₃,0.4wt%Pb?NO₃?₂ and 0.2wt%Zn?NO₃?₂.Metal ions can break the bridging hydrogen bonds of the organic structure,which promotes the generation and escape of volatile gases in coal and reduces the ignition temperature of coal.They can reduce the activation energy of coal combustion reaction and promote coal combustion.The synergistic catalysis of various metal salts on the coal combustion was studied through the TG-DSC test,and the industrial test was carried out at Longyan,Fujian Province.The synergistic catalytic effect of multiple metal salts on the coal combustion was better than a single type of metal salt.The use of catalyst can reduce the standard coal consumption per ton of clinker by 4.2kg/t,with a reduction of 3.8%,and the reduction of coal consumption per day can reach 12600kg.In addition,it was shown that the use of the catalysts will not reduce the basic properties of the clinker by characterizing the three-day flexural strength,compressive strength and stability indicators of the maturity.The catalysts can improve the combustion performance of pulverized coal effectively,increase the efficiency of coal heat conversion,and reduce the production cost of the cement industry,and have significant economic,social and environmental benefits.