Robust optimal operation of continuous catalytic reforming process under feedstock uncertainty

The continuous catalytic regenerative (CCR) reforming process is one of the most significant sources of hydrogen production in the petroleum refining process. However, the fluctuations in feedstock composition and flow rate could significantly affect both product distribution and energy consumption. In this study, a robust deviation criterion based multi-objective optimization approach is proposed to perform the optimal operation of CCR reformer under feedstock uncertainty, with simultaneous maximization of product yields and minimization of energy consumption. Minimax approach is adopted to handle these uncertain objectives, and the Latin hypercube sampling method is then used to calculate these robust deviation criteria. Multi-objective surrogate-based optimization methods are next introduced to effectively solve the robust operational problem with high computational cost. The level diagram method is finally utilized to assist in multi-criteria decision-making. Two robust operational optimization problems with different objectives are solved to demonstrate the effectiveness of the proposed method for robust optimal operation of the CCR reforming process under feedstock uncertainty.     

Progress in additive manufacturing on new materials: A review

Recent efforts and advances in additive manufacturing (AM) on different types of new materials are presented and reviewed. Special attention is paid to the material design of cladding layers, the choice of feedstock materials, the metallurgical behavior and synthesis principle during the AM process, and the resulted microstructures and properties, as well as the relationship between these factors. Thereafter, the trend of development in the future is forecasted, including: Effects of the particles size and size distribution of powders; Approaches for producing fine microstructures; Opportunities for creating new materials by AM; Wide applications in reconditioning of damaged components; Challenges for deep understanding and applications of the AMed new materials. The idea of “Develop Materials” or “Create Materials” by AM is highlighted, but a series of scientific, technological and engineering problems remain to be solved in future.     

JX-300XP系统在艾萨炉备料系统中的应用

结合艾萨炉备料系统的生产工艺,针对JX-300XP DCS的特点,介绍了该控制系统的总体设计方案、硬件配置、软件实现和网络通信,并对自定义模块、联锁控制等在系统中的应用以及JX-300XP系统与三菱FX 2NPLC、西门子S7-300PLC的通讯方式进行了讨论.该DCS系统投入生产以来,运行正常,提高了生产效率.     

Yield,water use efficiency and economic analysis of energy sorghum in South Texas

Yields, water use efficiency and economic returns (net farm revenues) of biomass sorghum [Sorghum bicolor (L.) Moench] were investigated over two years (2012 and 2014) under limited water resource conditions. Energy sorghum was grown under four water supply regimes: rain-fed (or dry-land, level 1), 50% (level 2), 75% (level 3) and 100% (level 4) of crop evapotranspiration rates (% ET_c). Biomass yields ranged from 5.8 to 16.6 Mg ha⁻¹ (dry weight) after 126 days of growth. Average water use efficiencies ranged from 3.95 kg m⁻³ to 23.4 kg m⁻³. Net return was approximately 410 $ ha⁻¹ with water depths above 400 ha-mm. These results suggest that it is possible to obtain more than 60 Mg ha⁻¹ of sorghum biomass (wet basis) with at least 425 mm of water. While biomass yield under irrigation was greater than rain-fed conditions, there were no significant differences among irrigation treatments. Biomass chemical composition did not differ significantly among water treatments suggesting that biofuel quality would not be affected by water deficits.     

Influence of feedstock preparation on ceramic injection molding and microstructural features of zirconia toughened alumina

Feedstocks for ceramic injection molding of ZTA containing 90 vol.% of sub-μm alumina and 10 vol.% of zirconia nanopowder were prepared by different processing techniques. Feedstocks were prepared by mixing in a sigma-blade kneader and subsequent homogenizing by twin-screw extrusion or shear roll compaction. Two other feedstocks were previously bead milled and subsequently processed by the same procedure. Compounding technology strongly influences the injection molding behavior and microstructures of the final product. Despite higher energy input of the shear roll compactor, powder agglomerates cannot be completely avoided. Pre-milling is effective to disperse and deagglomerate ceramic powders. Injection pressures of feedstocks from pre-milled powders were about 200 bar lower compared to pressures needed for non-milled feedstocks. Present feedstock preparation methods are feasible to produce homogeneous feedstocks, which strongly influence microstructures. In order to produce high solid loaded sub-μm/nm feedstocks, processing methods, pre-treatment and solid content have to be carefully chosen.     

Determination of suitable storage conditions to preserve fermentable sugars in raw thick beet juice for ethanol production

New long-term storage techniques are necessary to preserve fermentable sugars from sugar beet (Beta vulgaris L.) varieties which may qualify as advanced biofuel feedstocks in the United States. The focus of this study was to evaluate the combined effect of pH and refractometric dissolved solids (RDS) content on fermentable sugar preservation in raw thick beet juice stored for 24 wk at 23 ± 1 °C. Response surface methodology was applied to model the change in fermentable sugars in raw thick juice stored under controlled acidic (2 ≤ pH ≤ 5) and alkaline (8 ≤ pH ≤ 11) conditions in combination with RDS weight fractions in the range of 60–69%. Combinations of pH ≤ 3.5 or pH ≥ 9.5 with RDS ≥ 64.5% were effective in preserving up to 99% of fermentable sugars in stored raw thick juice. Following storage, yeast fermentation of acidic treatments achieved efficiencies of up to 82% relative to raw juice, whereas yeast fermentation was hindered in alkaline treatments resulting in efficiencies of up to 54%.     

浅析贵州省硫酸生产原料路线

从原料来源条件，工艺技术水平和经济分析等几方面比较了硫酸生产的几种主要原料，供我省硫酸生产企业及有关部门参考。     

Catalytic conversion of low-density polyethylene using a continuous screw kiln reactor

Both thermal and catalytic cracking of low-density polyethylene (LDPE) have been investigated using a screw kiln reactor. Thermal degradation gives rise to a broad product distribution, whereas catalytic cracking over Al-MCM-41 leads mainly to hydrocarbons within the gasoline range (C₅–C₁₂) with selectivities up to 80%. The increase of the screw speed between 3 and 15 rpm in the catalytic experiments allows the plastic feed rate to be varied in the range 20–41 g h⁻¹. The changes observed in the TOF values when varying the screw speed point out a decrease of the activity per site with increasing residence times, which may be due to the catalyst deactivation or to a contribution of the degradative extrusion at higher screw speeds. Likewise, a certain increase in the selectivity towards the gasoline fraction is observed at short residence times. On the other hand, PIONA analyses indicate that, regardless of the screw speed, the main components of the gasoline are olefins (50%) and isoparaffins (20%), whereas the aromatic content is always below 6%, with a proportion of benzene lower than 0.1%.     

Thin film silicon solar cells on upgraded metallurgical silicon substrates prepared by liquid phase epitaxy

Thin layers of about 30 μm thickness were grown on upgraded metallurgical (UMG) silicon substrates by liquid phase epitaxy (LPE) from an indium solvent. Instead of adding electronic grade silicon to the solution, a melt back step was carried out before each growth process to supply silicon to the melt from the UMG-Si wafers. We present an LPE technology which is capable to be directly scaled up to a few hundred layers per run. Solar cells have been fabricated based on phosphorous paste diffusion with efficiencies up to η=10.0%.