Interrelationships between welding parameters of hot‐gas welded polypropylene

In case of hot‐gas welding, the parameters of welding influence the strength of the welded joint. A welding portal was designed and built to make the welding parameters of manual hot‐gas welding controllable and independent of human factors. Large series of experiments were performed with the automatic welding station to explore the effect of welding parameters (welding temperature, flow rate, welding speed, and welding force). The strength of the welded joints was determined in a standard tensile test carried out according to ISO 527–3. Using two‐way analysis of variance it was concluded that all four parameters influence the strength of the welded joint significantly, and the strength of the welded joint exhibits a complex dependence on all four parameters. Based on a thermodynamic approach the welding energy was determined. The measured tensile strength values were plotted against the welding energy and the welding force and it was found that the results can be approximated by a quadratic surface function well. POLYM. ENG. SCI. 46:1173–1181, 2006. © 2006 Society of Plastics Engineers.     

Interrelationships between selected mechanical properties of individually-tested polymeric fibers

Although fibers are subject to complex deformations during processing and end use, most research has concentrated on tensile properties. We have extended our studies to include the ultimate torsional properties, i.e., the breaking twist angle (BTA), and the flexural fatigue life of single fibers. We now have sufficient data on diverse fiber types that we may compare their mechanical properties. Thus, in this paper we report the mechanical properties of the different starting, untreated, fibers, tested under fiducial conditions. We then develop and consider some interrelationships between these selected single fiber physical properties.     

Correlations between pyrolysis mass spectra of Rocky Mountain coals and conventional coal parameters

Correlations between Curie-point pyrolysis m.s. data on 102 coal samples from the US Rocky Mountain coal province and a set of 25 conventional parameters, including ultimate, proximate, petrographic and mineralogic measurements, obtained from the Penn State Coal Data Bank were investigated using computerized multivariate statistical analysis techniques. Strong correlations were found between both data sets with regard to rank-related parameters as well as sulphur parameters, whereas moderately strong correlations exist with regard to petrographic and mineralogical parameters as well as nitrogen content. Independent factor analysis of both data matrices provides factor score plots showing remarkably similar relations between samples from different coal regions, fields and seams. In fact, up to 80% of common variance is found in the conventional and pyrolysis m.s. data sets. The large proportion of variance common to both data sets permits the calculation of numerical models which enable direct prediction of technologically important parameters such as rank, calorific value and, possibly, aromaticity from pyrolysis m.s. patterns.     

Relations between Rock-Eval Tmax and other parameters in a sedimentologically homogeneous coal series

A new rank parameter, Rock-Eval T_max is proposed for the first steps of coalification. The technique is based on selective detection of hydrocarbon compounds produced by pyrolysis under standardized conditions of organic matter contained in the sediments.     

A general relationship between the kinetic parameters for the gasification of coal chars with CO2 and coal type

A general relationship between the kinetic parameters for gasification of coal char with CO₂ and coal properties is presented. Based on the analysis of the reason why there is no relationship between the kinetic parameters and coal type in previous investigations, a new idea for gasification kinetics has been put forward, and experiments showed that the gasification kinetic parameters for C+CO₂→2CO really exhibit a unified relationship with coal type.     

‘Solubility parameters’ in coal and coal liquefaction products

‘Solubility parameter’ spectra have been used in polymer research to determine the characteristics of cross-linked polymer systems. Cross-linked systems are not soluble in any solvent. Instead, solvent is imbibed by the cross-linked polymer and causes it to swell. The ‘solubility parameter’ of the solvent which causes maximum swelling is identified as that of the cross-linked material. Coal can be thought of as having some characteristics of a cross-linked system^1,2. That is, when immersed in a solvent with which it interacts, it will swell. In addition, coal contains extractable material. If coal is regarded as a ‘multipolymer’, this extractable matter can be thought of as the uncross-linked portion of the coal. Swelling spectra have been taken for untreated coal and coal from which some extractable matter has been removed, which partly suppresses swelling. This extractable matter can be thought of as similar to the uncross-linked coal molecule. Its structure can therefore be used to model the coal matrix itself, to determine the coal structure without using destructive chemical methods to break the coal apart. Dissolution spectra for both the coal extract and the coal liquefaction products from the PAMCO and Synthoil processes were taken. A set of mixed solvents with effective ‘solubility parameters’ ranging from 14.3 to 47.9 MPa^1/2 (7.0 to 23.4 hildebrands) was used. The behaviours of the coal extract and coal liquid products show striking similarities, leading us to believe that molecules similar to those found in liquefaction products already exist in the virgin coal and that hydrogenation products reflect the properties of the starting material.     

The calibration of NIR reflectance spectrometer for the determination of diverse compositional parameters

Near Infrared Reflectance Spectroscopy (NIRS) has been used to analyze a variety of agricultural commodities. Many times the success or lack of it has been due to inadequate computational capabilities or asking more of the instrument than its capabilities. This study showed that for the development of multiple analytical methods by Near Infrared Reflectance Spectroscopy (NIRS) a sophisticated instrument computer software system can perform multiple analyses and that different data treatments were required for each constituent. In this case a scanning monochromator with a digital mini computer and the USDA/Pennsylvania State University software system could easily be calibrated to determine simultaneously the percentages of moisture, protein and residual oil in cottonseed meal. High RSQ (.98–.99 for all constituents) and low standard errors of prediction (SEP) (0.18 moisture, 0.1 oil and 0.34 protein) were obtained. Success was due to the acquisition of sufficient data for all three analyses (via the monochromator) and the use of sufficient computing power to obtain an optimized calibration where each constituent required a different mathematical data treatment.     

煤粉工业锅炉运行数据与供料参数的相关性研究

供料参数的定量测量是锅炉实现自动调节的重要前提。目前直接测量设备受浓度测量范围、成本等因素影响,对工业锅炉适用性有限,而锅炉现有各传感器的部分数据与供料系统关系密切。为了探究根据传感器数据计算供料参数的可行性,以1 Hz频率收集了天津华苑1台58 MW锅炉的传感器数据,在控制其他变量的条件下筛选中间仓重量、一次风总压、锁气阀转速、炉膛压力、烟气氧含量等与供料相关的数据,通过最小二乘法、决定系数等分析方法,定量计算变量绝对值、标准差与供料参数的关系。结果表明,当中间仓进料阀关闭时,可通过中间仓称重以高准确度计算供料器300 s内的平均供料量;使用供料锁气阀转速计算供料量,基于锁气阀填充率和填充密度为定值的假设,低转速下供料曲线符合该假设。但随着锁气阀转速提高,供料量随转速的增长速率以二次曲线规律边际递减,且递减规律存在个体差异;一次风总压计算供料量属于差压法,用于计算供料量时,调整后的决定系数RAdj2>0.98,具有较高的准确性,但需要根据每台设备的累计运行数据计算系数k;炉膛负压波动可较好反映供料波动,但准确性低于使用一次风总压,取样时间为30 s时,供料量标准差-炉膛压力标准差RAdj2达到最大值,为0.890 1;供料量-耗氧量的RAdj2在取样时间200 s时达到最大值0.296 1,供料量标准差-耗氧量标准差RAdj2在取样时间10 s时达到最大值0.640 8,说明耗氧量用于推断供料波动的可靠性中等,推断供料量的可靠性较差,这可能与该锅炉煤粉的掺混比例不稳定使单位质量煤粉热值波动较大有关。     

Structural parameters of Donetsk and Lvov-Volynsk coal

The parameters ??, B, f _a , and cA calculated from the elementary composition of Donetsk and Lvov-Volynsk coal of different metamorphic stages characterize not so much the structure of the organic mass as the relative rates of chemical reactions determining the carbon, hydrogen, and oxygen content in two successive coalification periods: specifically, the rate of decarboxylation in the first period; and the rates of dehydrogenation and dehydration in the second.     

Evaluation of kinetic parameters of coal ignition

A method is presented of evaluating the kinetic parameters for the ignition reaction of coal based on the Semenov's thermal ignition theory adopted to coal particle ignition. The evaluated apparent activation energy, E, for bituminous coal, anthracite and bituminous coal char are in the range 46–103 kJ mol^?1. A verification was made by comparing the measured induction periods for the coal particles with those calculated numerically. The oxidation rate is controlled by diffusion into pores.     

Interrelationships between P-V-T and flow behavior of linear and nonlinear hydrocarbons

The aim of this work is to determine the branching effect on the flow behavior of alkanes. For this purpose, the zero-shear viscosity, η₀, was analyzed in terms of the Simha-Somcynsky equation of state, SS-EOS, using the hole fraction, h = h(P, T) computed from it. For the analysis, η₀-data of the linear and three-branch alkanes measured in a wide range of temperature and pressure, were used. For the linear species, Utracki proposed a relation, viz. ln η₀ = a₀ + a₁/(h + a₂), where a₁ = 0.79 and a₂ = 0.07 are the universal parameters for linear hydrocarbons and their mixtures. In this work, this relation was found to be valid for the linear but not for the branched alkanes.     

Differences between mineral coal and extracted coal

A distinction is proposed between mineral coal and extracted coal. Mineral coal is a complex natural composite that is found in underground beds, while extracted coal is created from mineral coal in working those beds. It is important to keep in mind that mineral coal is created by natural processes, whereas extracted coal is produced by human activity.     

Evaluation of intrinsic kinetic parameters of coal combustion

A method for evaluating the intrinsic kinetic parameters of coal combustion is presented. The method is based on the theory of diffusion and chemical reactions in porous particles. The intrinsic activation energies evaluated for bituminous coal and chars are in the range 137–204 kJ mol^?1.     

Effects of brown coal quality and process parameters on the hydroliquefaction of brown coal

During the development of the HVB process the influence of different parameters on the process have been investigated. In this Paper the influence of the properties of the brown coal on the process is reported. It is shown that: (1) the petrographical composition of Rhenish brown coal has virtually no effect on the HVB process; (2) the problems of sedimentation caused by the ash composition of the brown coal can be overcome by a particular thermal pretreatment of the coal; and (3) the moisture content of the brown coal is of minor importance for the technical realization of the HVB process.     

Distributed kinetic parameters for methane evolution during coal pyrolysis

The disparity between reported kinetic parameters for overall coal decomposition as well as volatile species evolution has been attributed to differences in the type of coal being studied as well as in the experimental technique employed. In this study, data reported for methane evolution in fluidized beds are considered and are found to be largely insensitive to coal type. Additionally, distributed kinetic parameters obtained using the heated grid, entrained flow and slow heating techniques are found to represent the fluidized bed data for both pulverized and large coal particles, provided that the transport mechanisms are also taken into account.     

原煤性质对跳汰机工作参数的影响

针对济三选煤厂跳汰工艺无法满足原煤分选要求,分选精度和数量效率明显下降,精煤质量不稳定,精煤产率低等问题,对原煤进行筛分试验和小浮沉试验,说明原生煤泥含量较低为7.30%,中煤含量偏高为20.17%,原煤可选性为难选。分析了原煤粒度、水分、矸石量和中煤斗式提升机排放物对跳汰机工作参数的影响,结果表明：块煤量小时,应将跳汰机入选量降至最低,减小用风,增大频率,减小排气;块煤量多时,应采取大水小风的操作方法,增加水量,加快床层水平运动速度,增加中煤排放,减少用风量。原煤水分较高时,应增加给煤量8%～15%。矸石增多时,应降低一段床层厚度,增大一段碎矸透筛,减轻中煤段压力。中煤斗式提升机内块煤量大时,应增加二段床层厚度,减少二段排料和二段用风量;中煤斗式提升机内有较大颗粒矸石时,应减少带煤量,增大二段排料,加大二段用风,降低二段床层厚度。     

煤样破碎级和自然级浮沉产率差别

分析了原煤破碎级对浮沉试验结果的影响,说明随着煤样最大标称粒度的减小,煤样精煤产率变化很大,煤样破碎的粒级越小,对精煤产率的影响越大,精煤产率也就越高。万峰原煤不同最大粒度浮沉试验表明:对于最大标称粒度不大于50 mm的煤样,煤样经破碎后,浮沉试验精煤产率提高了16.41%,中煤、矸石产率分别降低了9.43%和1.16%;说明煤样经破碎后得到了进一步解离,精煤产率增加明显,结算时,公司需要额外支付多余的贷款。对于最大标称粒度大于50 mm的煤样,原煤筛分、浮沉试验结果显示,实际+0.5 mm原煤浮沉精煤产率为42.75%,若按汽车采样机所采煤样50～0.5 mm精煤产率55.25%上报,则精煤产率增加了29.24%,公司要多支付实际上不存在的这部分精煤产率的价格,损失重大;因此,必须将汽车采样机所采煤样的浮沉试验结果与+50 mm煤样浮沉产率结合修正后,才能得出煤样的真实浮沉试验结果。     

Interrelationships in fatty acid processing

Examples are presented of the effect of each processing step on the quality, yield and throughput in the fatty acid processing scheme. These examples serve to illustrate the importance of seemingly unimportant process variables upon the economic involved in fatty acid processing.