In order to utilize municipal solid waste (MSW) in blast furnace ironmaking to realize synergistic reduction of pollution and carbon emissions, a novel method for pulverization of MSW by low temperature heat treatment and crushing, and evaluation of the properties of pulverized product for blast furnace injection were performed. In the present research work, residual waste obtained from MSW classification under the conditions of most Chinese cities was used as the representative raw material. The crushing performance of MSW can be improved by heat treatment. Considering the weight loss ratio, pulverization effect and density of heated MSW at different temperatures and durations, the optimal heat treatment parameters can be set as 300 degrees C and 20 min. The volatile content, fixed carbon content, ash content, S content, lower heating value of the pulverized product were 61.56 wt%, 19.02 wt%, 19.42 wt%, 0.39 wt% and 25.47 kJ/g, respectively. The pulverized product had worse fluidity and similar jet flow compared to industrial injection coal. Its decomposition heat for injection was 1732 kJ/kg. The initial combustion temperature and burnout temperature of the mixed fuel gradually decreased with the increasing of added pulverized product due to its much better combustion property. About 0.163 kg CO2 can be reduced if 1 kg of raw MSW was injected into blast furnace. The experimental results demonstrates that the obtained pulverized MSW could be used for blast furnace ironmaking to some extent as an environmentally friendly, low-carbon, and economically substitute of fossil fuel.
The utilization of a high pellet ratio in blast furnace smelting represents a pivotal strategy for achieving green and low-carbon ironmaking, which can improve raw material quality, reduce energy consumption, and decrease CO2 emissions. In this study, the impact of pellet proportion and charging sequence on the burden distribution was investigated using the discrete element method. The results revealed that the pellet mass fraction and the porosity of the ore layer gradually increase from the furnace wall toward the center under different pellet proportion conditions. As the pellet proportion increases, the radial segregation index of the pellets decreases and the porosity of the ore layer slightly increases. Furthermore, alternating charging can reduce pellet rolling, thereby lowering the flowability of the burden. The research outcomes can offer valuable insights for optimizing blast furnace charging operations when using a high pellet ratio, contributing to an improved smelting efficiency.
A series of novel NaGdGeO4: Tm3+, Dy3+ phosphors are prepared by a facile high-temperature solid-state method. By continuously adjusting the Dy/Tm ion concentrations, the white light emission with adjustable color temperature and color coordinate is achieved excited by the wavelength of 354 nm. The energy transfer mechanism between sensitized ions and activated ions is discussed with the help of fluorescence spectra and decay curve in details. Notably, different from other phosphors based on this host material, these prepared phosphors exhibit typical anomalous thermal quenching. It is very favorable for the devices working at high temperature. And this phenomenon may benefit from the high energy transfer efficiency at higher temperatures. The tunable white light and anomalous thermal quenching indicate that the studied material is a promising solid-state emitting phosphor for the white light-emitting diodes.
Studying the thermodynamic properties of soft rocks is critical for geothermal energy extraction, as it elucidates their temperature-dependent mechanical behaviors and heat transfer mechanisms, thereby optimizing reservoir stimulation, enhancing extraction efficiency, and ensuring long-term operational stability. Owing to the intricate geothermal settings and interconnected physicochemical processes, the thermodynamic properties exhibit pronounced spatial heterogeneity and interdependencies. Concurrently, constraints imposed by technical and economic limitations result in scarce practical field survey and experimental data on these properties, severely hampering comprehensive assessments of geothermal energy potential and exploitation feasibility. To evaluate the spatial variability of thermodynamic properties for heterogeneous soft rock using limited data, the thermal conductivity (TC), heat capacity (HC), and thermal diffusivity (TD) were measured. A new Copula statistical method is used to analyze thermodynamic properties under limited measurement data. Spatial variability in heterogeneous soft rocks is quantified using random field theory. The methodology’s reliability is confirmed through cross-validation against theoretical predictions, empirical measurements, and simulation outputs. The analysis framework of thermodynamic variability characteristics has been presented by stability point analysis and linear regression analysis processes. The variance reduction function, scale of fluctuation, autocorrelation distances, and autocorrelation structure of thermodynamic properties for heterogeneous soft rock are analyzed and discussed. This study can provide scientific data for thermal energy analysis and geothermal reservoir modification specifically applicable to soft rock formations with diagenetic and tectonic histories similar to those investigated in the Weishan Lake area.
Oxygen blast furnace is an important transformation method for the low-carbon and green development of traditional blast furnaces. This paper establishes a multi-zone mass and heat balance model and computational fluid dynamics model to study the influence of different hydrogen-rich gas composition on the smelting parameters, raceway state and combustion behavior of oxygen blast furnaces. The results show that the higher gas injection temperature can increase its physical heat, thereby reducing the coke ratio and improving the gas utilization rate. Furthermore, the injection amount of CH4 and H2 increases, resulting in lower raceway temperature and the direct reduction degree in the furnace, which can still meet the smelting requirements at lower raceway temperatures in actual production. Meanwhile, due to the oxygen competition relationship between coal and hydrogen-rich gas, as the proportion of CH4 and H2 injection increases, the coal burnout rate decreases. This research provides a theoretical basis for the regulation of low-carbon and high-efficiency oxygen blast furnace gas injection components.
