Papers by Keyword: Supercritical

Abstract: The supercritical turbine, changed low pressure rotor’s blade in site, bear vibration over-proof seriously because of unbalance, reached rated speed after dynamic balance in site. The vibration of low pressure Ⅱshaft’s bear was still over-proof. And the bear vibration phase was anti-phase with the shaft vibration not only anti-phase but also in-phase. It was found that the bear vibration was highly related with the anti-phase component of shaft vibration after running date analysis. And the bear vibration was reduced obviously after the anti-phase component of shaft’s residual unbalanced mass reduced by dynamic balance in site.

Abstract: An optimal condition of supercritical fluid extraction (SFE) for genistein in extruded soybean was developed. Optimal conditions through quadratic orthogonal rotation design were verified. The results from SC – CO2 showed that all five experiment factors tested have significant effects on the yield of genistein. The mathematical model set had close agreements with experimental values. It was found that there were 32 optimal extract conditions under which genistein yield higher than 0.092% were gotten through simulate compute. The optimal extracting conditions were stable and recurrable. SC–CO2 had a potential in the extraction of genistein from extruded soybean products.

Abstract: The paper introduces the characters of coordinated control system which belongs to 2×350MW supercritical air cooling heating units in a power plant. Meanwhile this article analyzes the control strategyies and the characters of main control circuits of boiler units and steam turbines respectively. The request of supercritical units running steadily and reacting quickly is satisfied by employing the technique of static feed-forward and so on.

Abstract: The cleanness of 30Cr2Ni4MoV steel was researched by chemical analysis, SEM and electrolytic experiment. The results show that the large-sized inclusions in the casting is the direct reason for the product to scrap. It found that there is a increase trend of large-sized inclusions and oxygen content from VD to pouring process with a cleanness detection of smelting process. It have achieved a good effect by adopting some measures to improve steel cleanliness which includes controlling the carbon content of EAF tapping reasonablly, low melting point controlling of inclusions, extending soft blow time and optimizing the flow field of tundish. The quantity of inclusions has reduced from 38.8 per square millimeter to 16.0 per square millimeter. The oxygen content has reduced from 58 × 10-6 to 32 × 10-6, and the nitrogen contents has reduced from 85 × 10-6 to 70 × 10-6 after process improvment.

Abstract: The objective of the work was to optimize the extraction of Hovenia dulcis Thunb. seed oil (HSO) by means of supercritical fluid extraction (SFE). Effects of pressure, temperature, time and CO2 flow rate on extract abilities of HSO were studied in this paper. Basis on the signal factor test, the orthogonal design was used to optimize the extraction conditions. Results showed that following conditions were optimal: pressure 40Mpa, temperature 40°C, time 120min, CO2 flow rate 9 kg/h. Extraction yield of HSO were 8.92%. Supercritical CO2 technology was a good extraction method for its higher yield and shorter time.

Abstract: Introduced the supercritical unit boiler feed-water supply system of once-through boiler’s structure and characteristics, and the feed-water supply system control principle and control strategy. Analysis of the system all controlled object and based on the interaction between the mid-point in the feed-water supply system enthalpy control of the regulatory process and problems, and put forward the corresponding optimization measures, and simulation research, the simulation results show that the feed-water supply system to improve the quality of the feed-water supply system adjustment, the main adjust the parameter of good quality, safety and economy got the reliable guarantee.

Abstract: Supercritical heat transfer correlations are obtained under the certain experimental conditions.The experimental parameters and its application scope is different under different experimental conditions, such as pressure, mass flow density, heat flux, tube diameter, temperature and so on. Supercritical heat transfer correlations are generally chosen in line with the correlation experimental conditions. However, some parameters are calculated under some conditions, under which we can not achieve good results, and at the same time it is prone to increase the deviation. We can choose the best experimental correlation of different experimental conditions based on the fuzzy nearness principles. The existent similarity degree mathematical model is limitated when calculating some similarity parameters.Using new mathematical calculation model resolves this problem, and we can get better experimental correlation for different supercritical heat transfer conditions with the relational selection.

Abstract: Various composite materials have been developed, but in many cases problems arise due to the combined materials such as fabrication becoming difficult because of the significant increase in viscosity, and transparency of the polymer is sacrificed. These issues can be overcome by controlling the nanointerface; however, this is considered as a difficult task since nanoparticles (NPs) easily aggregate in polymer matrices because of their high surface energy. Organic functionalization of inorganic NPs is required to increase affinity between NPs and polymers. For fabricating multi-functional materials, we proposed a new method to synthesize organic modified NPs by using supercritical water. Because organic molecules and metal salt aqueous solutions are miscible in supercritical water and water molecules serve as acid/base catalysts for the reactions, hybrid organic/inorganic NPs can be synthesized under the supercritical condition. The hybrid NPs show high affinity for the organic solvent and the polymer matrix, which leads to the fabrication of these super hybrid NPs. How to release the heat from the devices is the bottle neck of developing the future power devices, and thus nanohybrid materials of polymer and ceramics are required to achieve both high thermal conductivity and easy thin film flexible fabrication, namely trade-off functions. Surface modification of the BN particles via supercritical hydrothermal synthesis improves the affinity between BN and the polymers. This increases the BN loading ratio in the polymers, thus resulting in high thermal conductivity. Transparent dispersion of high refractive index NPs, such as TiO₂ and ZrO₂, in the polymers is required to fabricate optical materials. By adjusting the affinity between NPs and the polymers, we could fabricate super hybrid nanomaterials, which have flexiblility and high refractive index and transparency.

Abstract: TiO2-SBA-15 surface (TSS) composites were prepared by the supercritical pretreatment and then sol-gel process with using paraffin used as a clogging agent. The as-grown materials were characterized by using X-ray diffraction, UV-VIS spectroscopy and nitrogen absorption. The photocatalytic activities of TSS were evaluated by quantifying the degradation of methylene blue solution under UV light. Compared with TiO2-SBA-15 (TS) composites prepared only by the sol–gel method, TSS composites remain in mesostructure with high surface areas due to clogging effect of paraffin on SBA-15 cavity. Additionally, the small crystalline size of TiO2 in TSS is attributed to the fact that silica support baffles the agglomeration ofTiO2 nanoparticles. In comparison of TS composites and pure TiO2, higher photocatalytic activity of TSS is obtained and mainly attributed to larger surface areas and greater band-gap energy.

Abstract: The liposome particle entrapping atractylone extracted from Atractylodes macrocephala Koidz.was prepared and characterized. The liposome suspension of atractylone was formed by supercritical carbon dioxide (SC-CO2) expansion process and was dried by vacuum freezing. The physicochemical properties of the liposome particle including microstructure, size, entrapment efficiency and drug loading content were measured. The liposome formation could be controlled by adjusting the processing conditions such as pressure, temperature of SC-CO2 and mole fraction of ethanol in SC-CO2 [ x (CH3CH2OH)]. The entrapment efficiency, loading content, and average size of liposome particle were 83.1％, 5.1％ and 506.5nm respectively under the optimum conditions of 30MPa，338K and x (CH3CH2OH) = 15％.The liposome particle presented good performance of redispersion to liposomal suspension. The physicochemical properties of liposome particle including entrapment efficiency, dissolution rate and stability complied with the provisions of Chinese pharmacopoeia. The results show the liposome particle can be used as an solid immediate for hepatic target of drugs.