焦化废水的絮凝处理

通过采用絮凝沉淀的方法对焦化废水进行预处理，将CODcr由3880mg．L^-1以上降低到1760mg．L^-1左右，再采用载银活性炭／过氧化氢进行催化氧化，实现对废水处理。通过预处理，可有效降低催化氧化过程所需的时间和药品用量。     

Self-propagating high-temperature synthesis of advanced ceramics MoSi2–HfB2–MoB

This study focuses on the investigation of the macrokinetic features of SHS (combustion synthesis) of elemental mixtures Mo–Hf–Si–B, in particular the mechanisms of structure and phase formation in the combustion front as well as the structure and properties of consolidated ceramics. Two routes for the fabrication of the composite SHS powder in system MoSi₂–HfB₂–MoB were used: (1) synthesis using Mo–Si–B and Hf–B mixtures followed by mixing of the combustion products and (2) synthesis using the four-component Mo–Hf–Si–B mixture. Dense ceramic samples with a homogeneous structure and low residual porosity (0.8–3.6%) were prepared by hot pressing of SHS powders. Although the particles size distribution and phase composition of SHS powders are similar for both synthesis routes, the structure and properties of both the composite SHS powders and hot-pressed ceramics differ considerably. Synthesis using the four-component Mo–Hf–Si–B mixture allows one to produce hierarchically ordered nanocomposite material with improved mechanical properties: hardness up to 17.6?GPa and fracture toughness up to 7.16?MPa?m^1/2.     

An Engineering Approach for Estimating the Formation of Nitric Oxide from Fuel‐Nitrogen

Explicit approximate equations for estimating the conversion factor of fuel‐nitrogen into nitric oxide are presented. They depend on the fuel‐nitrogen mole fraction, the initial nitric oxide mole fraction, and the kinetics‐equilibrium mole fraction of nitric oxide. This last parameter expresses a limiting value of fuel‐nitrogen conversion; it includes the complex nitrogen chemistry and depends thus on combustion conditions. Experimental results demonstrate that the kinetics‐equilibrium mole fraction for fuel‐lean and high‐temperature conditions can be well estimated by the chemical‐equilibrium mole fraction, but for lower temperatures the kinetics‐equilibrium mole fraction has to be described by other correlations.     

Combustion synthesis of B4C/Al2O3/C composite powders and their effects on properties of low carbon MgO-C refractories

To improve the dispersity and oxidation resistance of nano carbon black (CB) in low carbon MgO-C refractories, B₄C/Al₂O₃/C composite powders were prepared by a combustion synthesis method using B₂O₃, CB and Al powders as the raw materials. The phase compositions and microstructures of the synthesized products were characterized by X-ray diffraction (XRD), Raman spectroscopy, and a scanning electron microscopy/energy dispersive spectrometry (SEM/EDS). The results show that an 80 wt% excess of CB is the maximum amount of CB that can be added under the condition of a self-propagating combustion wave, and the phase compositions of the products are B₄C, α-Al₂O₃ and CB. B₄C particles with uniform sizes and cubic polyhedral structures are embedded in the Al₂O₃ matrix. The combustion-synthesized B₄C/Al₂O₃/C powders and mechanically mixed B₄C/Al₂O₃/C powders were added to the low carbon MgO-C refractories, and their corresponding properties were compared. The apparent porosity (AP) of the refractories with the synthesized powders (labelled as M3) is lower than those of the refractories with mechanically mixed powders (labelled as M2) and without composite powders (labelled as M1). The oxidation ratio and slag erosion depth of M3 were lower than those of M2 and M1. The thickness of the decarburized layer of M3 was 10.2% and 22.4% less than that of M2 and M1, respectively. The penetration depth of M3 was 12.0% and 27.9% less than that of M2 and M1, respectively. The thermal shock resistance of M3 was better than that of M2 and M1. The residual strength ratio of M3 was 15.8% and 17.2% more than that of M2 and M1, respectively. These results suggest that the combustion-synthesized B₄C/Al₂O₃/C composite powders can be used as new and promising additives for low carbon MgO-C refractories.     

Combustion and emission characteristics of converging group-hole nozzle under lean engine operating conditions

This paper describes the combustion and emission characteristics of converging group-hole nozzles and compares the results to those of a single hole nozzle with the same overall nozzle exit hole area. Engine experiments were performed using a single-cylinder diesel engine operating under overall lean conditions (i.e., equivalence ratio 0.45). The considered nozzle configurations in the experiments included a converging group-hole nozzle (cGHN) with 3° converging angle, 0.090 mm hole diameter, and a single hole nozzle (SHN) of 0.128 mm hole diameter. The CFD calculations used the KIVA engine simulation code integrated with a Gasjet superposition model. Using the validated calculation models, the test conditions were also expanded to consider wider converging angle cGHNs (up to 12°). The results show that the evaporation of sprays from the cGHN-3° nozzle is more delayed than that of the SHN case and the cGHNs entrain more ambient gas due to smaller droplet sizes in the outer spray periphery. In addition, an increase in the converging angle of the cGHNs promotes fuel evaporation and produces a more homogeneous fuel–air mixture.     

A review of diamond synthesis by CVD processes

Diamond has some of the most extreme mechanical, physical and chemical properties of all materials. Within the last 50 years, a wide variety of manufacturing methods have been developed to deposit diamond layers under various conditions. The most common process for diamond growth is the chemical vapor deposition (CVD). Starting from the first publications until the latest results today, a range of different developments can be seen. Comparing the basic conditions and the process parameters of the CVD techniques, the technical limitations are shown. Processes with increased pressure, flow rate and applied power are the general tendency.     

Combustion synthesis of doped nanocrystalline ZnO powders for varistors applications

Doped nanocrystalline ZnO powders in the size range between 15 and 250 nm were synthesized by chemical combustion method. The powders were characterized for their physical, structural and chemical properties by BET, X-ray diffraction, FESEM, TEM and XPS. These powders were consolidated into dense varistors discs by compaction, sintering and evaluated for their I-V characteristics. Post-calcinations of these powders were found to have great influence on the green density and sinterability. The formations of phases after sintering were confirmed by XRD analysis and EDX. The varistor properties have been studied for different calcination temperatures and compositions. Breakdown voltage as high as 9.5 kV/cm and coefficient of nonlinearity 134 were obtained. Leakage current density was found to be ∼1.29 μA/cm² for a specific composition and condition. These studies demonstrate the feasibility of one step synthesis of doped ZnO nanopowder and their consolidation into ZnO fine grain varistor exhibiting improved performance.     

Combustion synthesis and characterization of Cu-Sm co-doped CeO2 electrolytes

Nano-sized CSO (Ce_0.80Sm_0.20O_2−δ) and CSCO (Ce_0.79Sm_0.20Cu_0.01O_2−δ) were synthesized by the PVA assisted combustion method, and then characterized by the structure of PVA-cation complexes and nano-powders, as well as mechanical and electrical performance after sintering. The results indicate that the PVA-cation complexes (PVA-(Ce³⁺,Sm³⁺) and PVA-(Ce³⁺,Sm³⁺,Cu²⁺)) were formed by coordinating metal cations to hydroxyl groups, as well as the COO⁻¹ group derived from the oxidation of PVA with NO₃⁻¹. Low temperatures (around 200 °C) caused intense combustion reactions, resulting in the direct crystallization of cubic fluorite nano-CSO (10-20 nm) and nano-CSCO (10-15 nm) crystals with homogeneous element distribution. This slight compositional modification of CSO by co-doping with 1 mol% CuO resulted in a significantly lowered densification temperature, as well as enhanced mechanical and electrical property. The strength improvement can be ascribed to the dense and fine-grained microstructure without normal grain coarsening, resulting in a transgranular-dominant fracture mode during strength testing.     

我国独立焦化厂的发展战略

介绍了我国焦化工业的现状和高炉大型化对焦炭质量的要求,分析了我国独立焦化厂发展面临的积极因素和不利因素,提出了独立焦化厂与上游煤矿联合,向下游钢铁企业延伸的发展战略。独立焦化厂应严格管理,降低成本,节能减排,对焦炉煤气进行综合利用,提高经济效益。     

焦炉煤气制氢工艺及问题讨论

变压吸附技术能从焦炉煤气中分离出高纯度氢气,该技术因工艺简单、投资少、操作方便而成为焦炉煤气分离氢气的主导技术。介绍了焦炉煤气吸附制氢的生产过程及工作原理,对装置特点进行了评述,并对运行中出现的问题进行了分析,同时提出了相应的处理措施。