Advanced Materials Research Vols. 524-527

Abstract: The control strategy for hoist system based on PLC was proposed in this paper to mend the control shortcomings in the traditional system applying relay logic control circuits. In this paper the hoist structure was analyzed, and the PLC control system realization in hardware and software was introduced too. The control method improves the maintainability and the flexibility of the elevator, extending the using life, and the ideal control effect can be attained. The Practical application showed that this control system has high efficiency, better maintainability and reliability, at the same time, reduce mine hoist system cost .it can be easier to complete more complicate tasks which the traditional control system can not achieve.

Abstract: Considering the fact that the forms of asphalt pavement potholes, subsidence and cement pavement potholes (collectively defined as pavement pothole-subsidence) are similar and they can influence traffic flow significantly, we put forward to use indexes such as Tangential Diameter Length, Normal Diameter Length, Depth, Lateral distance, etc to describe the characteristics of pothole-subsidence, and we also adopt AutoScope-2004 video detection system aided by artificial judging to investigate in the surveyed road section. According to different wheel paths, driving modes was classified into three types, influences of various pothole-subsidence on driving mode and speed was analyzed. We came up with conclusions as follows: one is that pothole-subsidence significantly influenced the variation of vehicle trajectory, 78.5% vehicles altered their driving direction, and the average rate of speed descent is over 20%.

Abstract: Based on ANSYS software, second development language of ANSYS software (APDL, UIDL), the simulation scheme of series traction mechanism of heavy machinery was proposed. Based on this scheme, its simulation platform was developed, which includes parameter computing module, parameter optimization module and reliability analysis module. with this simulation platform, its parameter optimization and reliability analysis can be done. The study in the paper provides the simulation platform to predict its performance.

Abstract: The computing method of non-uniform structure was study. The FEM format based on non-uniform equivalent beam was proposed. And the stiffness matrix based on FEM format was deduced. Moreover, through comparing with the results of FEM, the maximum error between them was about 11.1% so as to verify the accuracy of FEM format proposed. The study in the paper provides a new computing method and basis for design and calculation of similar non-uniform mechanical structures.

Abstract: The Characteristic of Coal Hydrogasification Was Carried Out in a Fixed Bed Reactor by Using Chars of Datong Bituminous, Spain Lignite and Pingdingshan Bituminous. it Was Investigated that the Effects of Reaction Temperature (973-1123K), Reaction Pressure (3-7Mpa), the Char Preparation Temperature (973-1073K) and Catalyst (CaO) on CH₄ Yield. the Three Stages Model Was Provided to Explain the Coal Hydrogasification Process. the CH₄ Yield Increases Rapidly in the First Stage which Is Dominated by the Reaction of Active Groups (-O-CH₃,-COOH,-CH₂OH,-CH₃) and H₂. the CH₄ Yield Keeps Constant in the Second Stage. the Releasing Rate of C-O-(C) and C-O-(H) Active Groups Dominates the CH₄ Yield Rate. the CH4 Yield Decreases in the Third Stage which Is Dominated by the Reaction Rate of Carbon and Hydrogen. there Is Higher CH₄ Yield under Higher Pressure which Is Related to the Higher Reaction Rate of Graphite and H₂ under Higher Pressure. the Structure of Raw Coals and Chars Was Identified by FTIR. in Additional, the Influences of Char Structure and Catalyst on the CH₄ Yield Are Discussed in the Paper.

Abstract: This paper describes the products characteristic derived from the conventional pyrolysis (CP) and microwave-assisted pyrolysis (MWP) of low metamorphic coal. GC/MS were used to analyze the volatile fractions of tar obtained by pyrolysis at different temperature and microwave power. It was found that microwave treatment produces more gas and oil than conventional pyrolysis at 800w and 800°C. In addition, the gas from the microwave has much higher syngas (H₂ + CO) contents (up to 55 vol. %) than those obtained by conventional hydrolysis (up to 42 vol. %). The tar from the microwave is mainly composed of aromatic pyrolysis and phenolic compounds, and the content is 47.398% and 13.831% respectively as the microwave power is 800w. Meanwhile, the tar component content of C₅-C₁₀ from microwave pyrolysis is up to 5 fold than conventional pyrolysis. By contrast, the microwave-assisted pyrolysis is beneficial to the tar conversion to light fraction.

Abstract: Two catalysts, SO₄^2-/activated clay (SAC) and SO₄^2-/Fe₂O₃ activated clay (SFAC) were obtained by activated clay with or without Fe₂O₃ loading then treated with H₂SO₄. The acidity of the catalysts were measured by temperature-programmed desorption of ammonia (NH₃-TPD), and the results confirm that the SFAC catalyst has higher acid strength than SAC catalyst. Other techniques such as X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and energy dispersive X-ray spectroscopy (EDXS) were also employed to characterize the structure of catalysts. Its catalytic properties in desulfurization reaction from the simulated coking benzene by alkylation method was also investigated under mild conditions (353 K and atmospheric pressure), the thiophene removal efficiency can reach 42% for SAC catalyst and 99% for SFAC catalyst, respectively.

Abstract: Temperature-programmed pyrolysis of SL-lignite from Xilinhaote was investigated. The solid and gaseous pyrolysates were analyzed by means of gas chromatography(GC) and X-ray diffraction(XRD). The weight percents of surface moisture, ash, C, H and S increase with increasing the pyrolysis temperature in solid pyrolysates, while the volatile matter is contrary. The cracking reaction occurs before 600°C, the consolidation reaction happens between 600°C and 650°C, while the polycondensation or secondary reaction appears after 650°C. Calcium sulfide is formed by the process of decomposition of calcium sulphates at 900°C. The solid pyrolysates become more graphitic with increasing the pyrolysis temperature.

Abstract: Lignite samples, Huolinhe(HLH) and Xiaolongtan(XLT) lignites were used for experiments. Mild pyrolysis experiments were carried out by final temperature 150～450°C. Physical and chemical properties have been investigated using thermogravimetric, FTIR analysis, nitrogen adsorption and oxygen-functional group analysis. Besides, the changes of the surface properties during upgrading were characterized in detail. The results show that specific surface area and moisture-holding capacity have the trend of first decreases and then increases in the upgrading temperature range. Furthermore, the decomposition of the oxygen-bearing functional groups on the coal surface which reduced the moisture-holding capacity. Oxygen absorption experiments indicate that thermal upgrading could decrease the tendency of lignite to spontaneous combustion.

Abstract: It is very important to the combustion processes of coal pyrolysis, so the effects of all reaction condition on the brown coal (Yunnan,China) were investigated by using the fixed bed reactor in detail. Through the new method of part-hydrogenation of the pyrolysis, it can be increased the content of coal tar at the same time reduced H₂ consumption.