回收WC制备硬质合金过程中的碳量控制

通过化学成分分析和扫描电镜研究锌熔法回收的WC与钨粉碳化后的原生WC粉在化学成分、颗粒形貌和费氏粒度等方面的不同。以锌熔法回收的WC粉和Co粉为原料,经过调碳,制备不同含碳量的YG8混合料,再经相同的压制、真空烧结制度制得YG8合金,研究碳含量对该合金组织及力学性能的影响,并重点探讨在真空烧结过程中的控碳问题。研究表明,对回收碳化钨进行适当的碳量调配,并通过工艺控制,可以生产出综合性能良好的硬质合金制品。

WC/Co纳米复合粉原料制备硬质合金细晶粒顶锤的方法研究

采用流态化制备方法生产的WC/Co纳米复合粉作原料,研究制备硬质合金细晶粒Φ175顶锤的生产方法。WC/Co纳米复合粉中加入微量抑制剂,配制成含钴量为10%的细晶粒合金配方,经搅拌球磨、喷雾干燥、冷等静压、低压烧结后检测其合金特性值。生产合格Φ175顶锤,进行使用效果验证。研究结果表明:WC/Co纳米复合粉可应用于搅拌球磨制备硬质合金细晶粒大顶锤,这种顶锤在使用中表现出卸压回弹性小的特点,可解决大顶锤在合成保压后卸压瞬间易发生裂纹失效的难题。

Strategic deliberation on development of low-carbon energy system in China

In recent years, there have been considerable developments in energy provision with the growing improvements in energy supply security and support systems in China. However, China's energy system continues to retain a high-carbon feature where coal dominates energy production and consumption, which has led to the rapid growth of greenhouse gas emissions and associated serious environmental pollution. It has therefore become an important task for China to consider how to promote the low-carbon development of energy system. This paper summarized the basic trends and challenges for development of low-carbon energy system in China and studied the primary energy consumption and carbon emissions in different scenarios at 10-year intervals between 2010 and 2050. The analysis showed that controlling coal consumption will have an important influence on the control of total carbon emissions and of carbon emission peaking; promotion of non-fossil fuel energies will offer a growing contribution to a low-carbon transition in the medium and long term; the development of carbon capture, utilization, and storage will play a key role in realizing a deep decarbonization pathway, particularly after 2030; and the establishment of a low-carbon power system is crucial for the achievement of low-carbon energy transition. Finally, the strategic considerations and policy suggestions on the development of low-carbon energy systems in China are explored.

Reduction mechanism of Fe2O3-Cr2O3-NiO system by carbon

Isothermal experiments on the reduction of Fe_2O_3-Cr_2O_3-NiO(molar ratio of Fe-to-Cr-to-Ni is 3:2:2)by graphite were carried out at 1350–1550°C,and effects of various factors on reduction degree were studied.The results show that the reaction rate of the Fe_2O_3-Cr_2O_3-NiO system is fast during the initial period(reduction degree,α<38%),and then the rate decreases until the end of the reduction.Factors such as temperature,carbon content,sample size have a more significant effect during the final stage(α>38%).The metallic product formed at the initial stage(a Fe-Ni alloy)greatly promotes the reduction of Cr2O3 at the final stage.Further,during the reduction of Fe_2O_3-Cr_2O_3-NiO by carbon,interfacial reaction is the rate-controlling step and g(α)=1-(1-α)0.5 is the reaction mechanism for the initial stage,whereas two-dimensional diffusion is the rate-controlling step and f(α)=α+(1-α)ln(1-α)is the reaction mechanism for the final stage.The apparent activation energies are 55.43 k J/mol and 174.54 k J/mol for the initial and the final stages,respectively.

Carbon Dioxide Control-Technology for the Future

The world is experiencing global climate change, and most scientists attribute it to the accumulation in the atmosphere of carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons. Because of its enormous emission rate, carbon dioxide （CO2） is the main culprit. Almost all the anthropogenic CO2 emissions come from the burning of fossil fuels for electricity, heat, and transportation. Emissions of COg can be reduced by conservation, increased use of renewable energy sources, and increased efficiencies in both the production of electrical power and the transportation sector. Capture of CO2 can be accomplished with wet scrubbing, dry sorption, or biogenic fixation. After CO2 is captured, it must be transported either as a liquid or a supercritical fluid, which realistically can only be accomplished by pipeline or ship. Final disposal of CO2 will either be to underground reservoirs or to the ocean; at present, the underground option seems to be the only viable one. Various strategies and technologies involved with reduction of CO2 emissions and carbon capture and sequestration （CCS） are briefly reviewed in this paper.

Optimization and control of a reactive distillation process for the synthesis of dimethyl carbonate

Dimethyl carbonate is an environmentally benign and biodegradable chemical.Based on integration of reactive distillation and pressure-swing distillation technologies,a novel process for synthesis of dimethyl carbonate through transesterification with propylene carbonate and methanol has been developed by Huang et al.In this work,the optimization of this process was performed by minimizing the total TAC.The results show that the optimal design flowsheet can save energy consumption by 18.6% with the propylene carbonate conversion of 99.9%.Then,an effective plant-wide control structure for the process was developed.Dynamic simulation results demonstrate that the temperature/flow rate cascade control plus with simple temperature control can keep not only product purity but also the conversion of the reactant at their desired values in the face of the disturbance in reactant feed flow rate and feed composition.

Carbon Dioxide Emission Control Measures in Coal-Fired Power Plant

CO2 （carbon dioxide） emission reduction, especially removal from coal-fired power plants has become the highest priority in measures to combat global warming. In China, coal-fired power is the main generating electricity style; more than 2,000 millions tons coal has been consumed in coal-fired power plants in China. In order to control CO2 emission, three technologies has been introduced, CCS （carbon capture and storage）, oxy-combusion, and IGCC （integrated gasification combined cycle）. CCS and IGCC technologies are expensive and need too many facilities; besides, there are some concrete problems need to resolve on the oxy-combustion technology. The energy saving work is the other pattern of CO2 emission control.

硬质合金制造与使用过程中矛盾运动的探讨

用矛盾论的观点与方法 ,分析论述了硬质合金制造与使用过程中的矛盾运动。指出硬质相与粘结相的对立统一是硬质合金中贯穿始终的基本矛盾 ,碳量控制则是硬质合金生产的主要矛盾 ,抗弯强度是各种矛盾因素综合作用的产物。如何利用矛盾规律来指导硬质合金的科研与生产 ,是值得探讨的一个问题。

Biotic effects dominate the inter-annual variability in ecosystem carbon exchange in a Tibetan alpine meadow

The alpine meadow ecosystem in Tibet is fragile and sensitive,and its carbon sink function with respect to climate change has become a matter of widespread concern.Therefore,this study aims to clarify the inter-annual variations(IAVs)in the carbon fluxes in an alpine meadow and to further quantify the contributions of the driving factors to the IAVs.Based on 7 years of flux data(2012-2018)and the corresponding climatic and biotic data,a set of look-up tables was used to separate and quantify the IAV sources.Furthermore,linear perturbation analyses were employed to quantify the contributions of each key factor.During 2012-2018,the net ecosystem productivity(NEP),gross primary productivity(GPP)and ecosystem respiration(Re)of this alpine meadow were 3.31±26.90,210.18±48.35 and 206.88±28.45 g C m^(-2) y^(-1),respectively,which indicated relatively large IAVs.When the contributions of climatic and biotic effects were distinguished and quantified,the dominant effects of biotic factors emerged.Additionally,negative interactions between climatic and biotic effects were detected.Among the climatic factors,only soil water content contributed relatively more to the IAVs and played a role in regulating the interactions between climatic and biotic effects.These results suggest that biotic effects must be carefully considered to reduce the uncertainties associated with future carbon flux estimates.