With the increasingly stringent national environmental protection policies,the ultra-low emission transformation of industrial coal-fired grate boilers and the highly efficient utilization of biomass resources or wast...With the increasingly stringent national environmental protection policies,the ultra-low emission transformation of industrial coal-fired grate boilers and the highly efficient utilization of biomass resources or wastes are becoming increasingly urgent in China.This study first proposes a novel and simple configuration for industrial grate boilers to integrate the decoupling combustion and flue gas recirculation or co-firing technologies,so as to reduce pollutant emission but improve thermal efficiency.Burning coal briquettes in the novel grate boiler,the original NO_(x) emissions can be remarkably decreased to as low as 56 mg· m^(-3),corresponding to the reduction efficiency of 82.8% in comparison with the average value in traditional coal-fired grate boilers.Co-firing coal briquettes with straw pellets in the novel grate boiler,the strongest synergistic effect of NO_(x) reduction is observed at the blending mass fraction of 50%,in which the NOxemissions can be further mitigated by at most 16.0% on top of the already reduced amount by decoupling combustion to reach less than about 165 mg· m^(-3).The novel grate boiler allows co-firing Chinese medicine residue with high water content at the blending mass fraction of up to 30% on the premise of low NO_(x) and CO emissions.All experimental results in this study demonstrated the obvious superiorities of the novel grate boiler in reducing NO_(x) and CO emissions and mitigating both slagging tendency and slag carbon content,which can be attributed to either the cumulative effects of decoupling combustion with flue gas recirculation or the synergistic effects of cofiring coal-biomass blends.The newly-developed travelling-grate decoupling combustion technology can be expected to provide an economical and convenient measure for the ultra-low NO_(x) emission transformation of industrial coal-fired grate boilers as well as the clean and highly efficient consumption of biomass wastes with high water content or difficulty to burn in China.展开更多
In this paper, cold simulation experiments and numerical calculations are conducted to predict 3 D flow field aerodynamics for an oil furnace after being retrofitted due to its fuel variation. K ε model and SIMPLE ...In this paper, cold simulation experiments and numerical calculations are conducted to predict 3 D flow field aerodynamics for an oil furnace after being retrofitted due to its fuel variation. K ε model and SIMPLE program under body fit coordination (BFC) system, in which TTM non orthogonal method is used to control the irregular geometric boundary, are adopted to solve the control equations. Model tests are conducted to check the calculation results, showing that they are in agreement with each other. Three different alternatives with different side window locations are also calculated to optimize the designs. The field retrofitting results show that the combination of cold tests with numerical calculations has prosperous application in retrofitting or renewing medium and small boilers.展开更多
The tangentially fired utility boiler furnace is divided into several sections. The dynamic mathematical models for each section are presented. In the combustion zone, three dimensional model is used, while for the up...The tangentially fired utility boiler furnace is divided into several sections. The dynamic mathematical models for each section are presented. In the combustion zone, three dimensional model is used, while for the upper sections, lumped parameter model is used instead. With the combination of different models, we can get detailed distributions of gas velocity, temperature, chemical species, heat flux, etc. in the furnace, but with less CPU time. The radiation through the interfaces of each section is cons...展开更多
Based on the porosity method and the improved non uniform QUICK scheme, this paper describes a three dimensional computer simulation to predict the flow characteristics in a tangentially fired boiler. The model is ap...Based on the porosity method and the improved non uniform QUICK scheme, this paper describes a three dimensional computer simulation to predict the flow characteristics in a tangentially fired boiler. The model is applied to a 600?MW boiler modeling under different operating conditions of reverse swirl of secondary air. The numerical results achieve reasonable agreement with experimental data. The calculated results of flow field, the pressure distribution, the relative diameter of tangential circle, angular momentum flux in furnace and the velocity distribution index in horizontal gas pass are analyzed in detail. And then the effects of the reverse swirl of secondary air on flue gas imbalance are discussed. Finally a reasonable operating condition of the reverse swirl of secondary air is presented.展开更多
The feasibility of using an ANN method to predict the mercury emission and speciation in the flue gas of a power station under un-tested combustion/operational conditions is evaluated. Based on existing field testing ...The feasibility of using an ANN method to predict the mercury emission and speciation in the flue gas of a power station under un-tested combustion/operational conditions is evaluated. Based on existing field testing datasets for the emissions of three utility boilers, a 3-layer back-propagation network is applied to predict the mercury speciation at the stack. The whole prediction procedure includes： collection of data, structuring an artificial neural network （ANN） model, training process and error evaluation. A total of 59 parameters of coal and ash analyses and power plant operating conditions are treated as input variables, and the actual mercury emissions and their speciation data are used to supervise the training process and verify the performance of prediction modeling. The precision of model prediction （ root- mean-square error is 0. 8 μg/Nm3 for elemental mercury and 0. 9 μg/Nm3 for total mercury） is acceptable since the spikes of semi- mercury continuous emission monitor （SCEM） with wet conversion modules are taken into consideration.展开更多
基金supported by the Strategic Priority Research Programs of Chinese Academy of Sciences (XDA29020401)the Fund of State Key Laboratory of Mesoscience and Engineering (Meso-23-A02)。
文摘With the increasingly stringent national environmental protection policies,the ultra-low emission transformation of industrial coal-fired grate boilers and the highly efficient utilization of biomass resources or wastes are becoming increasingly urgent in China.This study first proposes a novel and simple configuration for industrial grate boilers to integrate the decoupling combustion and flue gas recirculation or co-firing technologies,so as to reduce pollutant emission but improve thermal efficiency.Burning coal briquettes in the novel grate boiler,the original NO_(x) emissions can be remarkably decreased to as low as 56 mg· m^(-3),corresponding to the reduction efficiency of 82.8% in comparison with the average value in traditional coal-fired grate boilers.Co-firing coal briquettes with straw pellets in the novel grate boiler,the strongest synergistic effect of NO_(x) reduction is observed at the blending mass fraction of 50%,in which the NOxemissions can be further mitigated by at most 16.0% on top of the already reduced amount by decoupling combustion to reach less than about 165 mg· m^(-3).The novel grate boiler allows co-firing Chinese medicine residue with high water content at the blending mass fraction of up to 30% on the premise of low NO_(x) and CO emissions.All experimental results in this study demonstrated the obvious superiorities of the novel grate boiler in reducing NO_(x) and CO emissions and mitigating both slagging tendency and slag carbon content,which can be attributed to either the cumulative effects of decoupling combustion with flue gas recirculation or the synergistic effects of cofiring coal-biomass blends.The newly-developed travelling-grate decoupling combustion technology can be expected to provide an economical and convenient measure for the ultra-low NO_(x) emission transformation of industrial coal-fired grate boilers as well as the clean and highly efficient consumption of biomass wastes with high water content or difficulty to burn in China.
文摘In this paper, cold simulation experiments and numerical calculations are conducted to predict 3 D flow field aerodynamics for an oil furnace after being retrofitted due to its fuel variation. K ε model and SIMPLE program under body fit coordination (BFC) system, in which TTM non orthogonal method is used to control the irregular geometric boundary, are adopted to solve the control equations. Model tests are conducted to check the calculation results, showing that they are in agreement with each other. Three different alternatives with different side window locations are also calculated to optimize the designs. The field retrofitting results show that the combination of cold tests with numerical calculations has prosperous application in retrofitting or renewing medium and small boilers.
文摘The tangentially fired utility boiler furnace is divided into several sections. The dynamic mathematical models for each section are presented. In the combustion zone, three dimensional model is used, while for the upper sections, lumped parameter model is used instead. With the combination of different models, we can get detailed distributions of gas velocity, temperature, chemical species, heat flux, etc. in the furnace, but with less CPU time. The radiation through the interfaces of each section is cons...
文摘Based on the porosity method and the improved non uniform QUICK scheme, this paper describes a three dimensional computer simulation to predict the flow characteristics in a tangentially fired boiler. The model is applied to a 600?MW boiler modeling under different operating conditions of reverse swirl of secondary air. The numerical results achieve reasonable agreement with experimental data. The calculated results of flow field, the pressure distribution, the relative diameter of tangential circle, angular momentum flux in furnace and the velocity distribution index in horizontal gas pass are analyzed in detail. And then the effects of the reverse swirl of secondary air on flue gas imbalance are discussed. Finally a reasonable operating condition of the reverse swirl of secondary air is presented.
基金The National Basic Research Program of China (973Program) (No.2006CB200302)the Natural Science Foundation of JiangsuProvince (No.BK2007224).
文摘The feasibility of using an ANN method to predict the mercury emission and speciation in the flue gas of a power station under un-tested combustion/operational conditions is evaluated. Based on existing field testing datasets for the emissions of three utility boilers, a 3-layer back-propagation network is applied to predict the mercury speciation at the stack. The whole prediction procedure includes： collection of data, structuring an artificial neural network （ANN） model, training process and error evaluation. A total of 59 parameters of coal and ash analyses and power plant operating conditions are treated as input variables, and the actual mercury emissions and their speciation data are used to supervise the training process and verify the performance of prediction modeling. The precision of model prediction （ root- mean-square error is 0. 8 μg/Nm3 for elemental mercury and 0. 9 μg/Nm3 for total mercury） is acceptable since the spikes of semi- mercury continuous emission monitor （SCEM） with wet conversion modules are taken into consideration.
