Major pathways for used oil disposal and recycling. Part 2

One of the main concerns with lubricating oil relates to used oil management for both industrial and engine oils, although the environmental impact of gasoline and diesel engine oils is the most critical. Provided that efficient management systems are in place, most used oil should not reach the environment, so, the major question is ‘how should we dispose of collected used oil?’ The first option lies in burning it as a fuel, the second in recycling (re‐claiming, reprocessing, re‐refining). The latter allows recovery of mineral base oils, which are valuable constituents of crude oil. In the first part of this paper, the author looked at the problems associated with used oil, its use as a fuel, and simple recycling. He went on to look at major re‐refining processes, starting with hydrogenation (KTI, Mohawk, BERC/NIPER, and PROP technologies). In Part 2 he covers other processes, including Safety Kleen, IFP/Snamprogetti, UOP Hylube, and vacuum distillation and clay treatment technologies.     

The continuous flow stirred tank reactor (CFSTR) model and used oil volume corrections in condition monitoring

The continuous flow stirred tank reactor model has been applied to the analyses of lubricating oil as a major contributor to the condition monitoring of i/c engines. The need for a volume correction to account for the dilution effect of added, fresh, lubricant is demonstrated for the model and then developed for two examples. It is demonstrated that application of the volume correction/dilution model allows the oil analysis data base to be transformed from relative to absolute values. The ‘absolute wear’, the ‘current wear rate’ and the ‘change in the wear rate’ can then be simply calculated at any time as a fitted, smoothed, function of the analytical parameters with sample service time, its first and second derivatives, respectively. Implications for diagnosis and prediction from the corrected data base are considered.     

石化用高压阀门阀体和阀盖连接形式的研究

分析了高压阀门阀体和阀盖的连接形式及其相关标准的规定。提出了石油化工用阀门阀体和阀盖采用压力自紧密封结构连接形式应注意的问题和避免阀门泄漏的辅助措施。     

砂浆车专用减速机的设计与制造

文中主要介绍了一种搅拌优质砂浆的新方法,以及砂浆车搅拌罐上所用的砂浆车专用减速机。阐述了该减速机的设计步骤与方法,以及结构设计的成功之处。对从事减速机设计的工程技术人员具有一定的参考价值。     

Selections of working conditions for creep feed grinding. Part(II): workpiece temperature and critical grinding energy for burning

In this study, the workpiece temperature is predicted by the thermal model presented in the previous paper. Also, the grinding energy when the fluid begins to cause boiling is defined as the critical grinding energy for the workpiece burning. Thus, a sequence of experiments are performed. The results show that the predicted workpiece temperatures have great agreement with experimental and published data. Hence, the validity of the thermal model is proved. From the measured signals of grinding force and workpiece temperature, the occurrence of workpiece burning is accompanied with the abrupt rise of both signals. At the moment, the experimental grinding energy is also greater than the critical grinding energy. Thus, the workpiece burning can be predicted or evaluated so as to avoid the working conditions of burning occurrence.     

Effects of oil inlet pressure and inlet position of axially grooved infinitely long journal bearings. Part I: Analytical solutions and static performance

This paper presents analytical expressions for the dynamic pressure and dynamic fluid force in axially grooved long journal bearings with consideration of oil inlet pressure and inlet position. The effects of oil inlet pressure (in the range of , where the dimensionless oil inlet pressure ) and oil inlet position (in the range of 0Θ_i90°) on the static oil film configuration, pressure distribution, and steady state journal position in axially grooved journal bearings are discussed. In this paper, Reynolds–Floberg–Jakobsson boundary conditions are assumed to account for the appropriate starting position of the cavitation, the reformation of oil film at the end of caviation, and the effect of oil inlet pressure and inlet position.     

重油催化主风机组汽轮机振动原因分析及解决措施

某炼油厂检修中发现重油催化裂化装置主风机组中汽轮机轴瓦异常振动,从轴承的承载能力及流 体动力学方面予以分析,故障诊断为转子油膜失稳造成的油膜涡动和机组对中不良所引起的.最后通过提高轴瓦的承载能力,堵塞轴瓦上多余小孔,消除机组对中误差等措施,成功解决了汽轮机轴瓦异常振动故障,确保了机组平稳运行.     

A comparison of fire-resistant hydraulic fluids for hazardous industrial environments. Part I. Fire resistance and lubrication properties

Fire-resistant hydraulic fluids have been developed since the Second World War. In addition to phosphate esters, there are various other fluids (e.g. oil-in-water emulsions, water glycols) available. This paper provides a technical comparison of the different fluid types, in terms of fire resistance, lubricating properties, and viscosity. The second part of the study examines the corrosion properties, thermal and oxidative stability, shear stability, materials compatibility, and other physical properties.     

Capacitive measuring system for two-phase flow monitoring. Part 1: Hardware design and evaluation

Two-phase flows are commonly found in many industrial applications, such as oil and gas production. The monitoring of such flows is performed either in field applications or in pilot plant studies. In both cases, simple and robust measuring techniques are required. Capacitive probes have been applied for void fraction measurement in pipes in research and industry. However, capacitive measuring systems applied so far are tailored for specific applications and may not be easily adaptable. In addition, more and more soft-computing methods are applied for advanced data processing and parameter extraction which requires more computational power of sensor systems for online data processing. We develop a capacitive system provided with a microcontroller in which necessary routines for data processing may be embedded. System design is detailed explained and system's performance is evaluated, showing appropriate accuracy and time response for the investigation of two-phase flows.     

A comparison of fire-resistant hydraulic fluids for hazardous industrial environments. Part II. Stability,fluid life,and environment

Fire-resistant hydraulic fluids have been developed since the Second World War. In addition to phosphate esters, there are various other fluids (e.g. oil-in-water emulsions, water glycols) available. This paper provides a technical comparison of the different fluid types, in terms of fire resistance, lubricating properties, and viscosity. The second part of the study examines the corrosion properties, thermal and oxidative stability, shear stability, materials compatibility, and other physical properties.     

A novel parallel-kinematics mechanisms for integrated, multi-axis nanopositioning: Part 1. Kinematics and design for fabrication

Multi-axis micro and nanopositioning systems are increasingly used in much of the metrology and process equipment related to the field of nanotechnology. This, the first of a two-part series of papers on a novel piezo-driven, parallel-kinematics XYZ nanopositioning (PKXYZNP) stage, concentrates on the development of a viable scheme to achieve pure spatial translation. First, the mechanism is shown to admit closed-form solutions to both; the forward and reverse kinematic problems. The Jacobian and the dynamics of the system indicate that the mechanical structure produces a relatively large work volume, and is capable of high bandwidth and uniform performance across it. The fabrication of the system is described along with some basic testing of its Jacobian and its modal frequencies. Using capacitive gages, the stage is capable of about 85 μm of motion along each axis with a resolution of about 2–4 nm. The controls, testing and performance are discussed in detail in the companion paper [Dong J, Yao Q, Ferreira PM. A novel parallel-kinematics mechanism for integrated, multi-axis nanopositioning. Part 2. Dynamics, control and performance analysis. Precis Eng].     

Real-Time Prediction of Workpiece Errors for a CNC Turning Centre, Part 1. Measurement and Identification

This paper analyses the error sources of the workpiece in bar turning, which mainly derive from the geometric error of machine tools, i.e. the thermally induced error, the error arising from machine–workpiece–tool system deflection induced by the cutting forces. A simple and low-cost compact measuring system combining a fine touch sensor and Q-setter of machine tools (FTS FQ) is developed, and applied to measure the workpiece dimensions. An identification method for workpiece errors is also presented. The workpiece errors which are composed of the geometric error, thermal error, and cutting force error can be identified according to the measurement results of each step. The model of the geometric error of a two-axis CNC turning centre is established rapidly based on the measurement results by using an FTSFQ setter and coordinate measuring machine (CMM). Experimental results show that the geometric error can be compensated by modified NC commands in bar turning.     

A method for assessing geometrical errors in layered manufacturing. Part 1: Error interaction and transfer mechanisms

Geometric accuracy of components is one of the most important quality characteristics in layered manufacturing processes on which most rapid prototyping (RP) techniques are based. Layered manufacturing is an approximate fabricating process in which the final geometric error of the physical part is affected, not only by the approximation technique used, but also by the fabrication process. Errors that occur in one layer could propagate and transfer to other layers causing an accumulated error effect in the process. In this paper, a concept of disturbance error is introduced to describe the effect of accumulated errors in the fabrication process. A physical model is presented to describe error interactions and error transfer mechanisms in the layered manufacturing process. A geometrical model is developed using surface approximation techniques to describe the relationships of the geometrical errors. It is shown that although the complexity of the part geometry is not directly related to the manufacturing process, it will affect the geometrical errors of the part produced.     

Development of novel sustainable neat-oil metal working fluids for stainless steel and titanium alloy machining. Part 1. Formulation development

This paper introduces and describes the development and application of methodologies for the formulation of novel sustainable neat-oil metal removal fluids. A further paper will describe the methodologies being employed and the results of the performance benchmarking of the final fluid formulations for stainless steel and aerospace-grade titanium alloy materials. In this paper, a stepwise approach to the development of novel sustainable neat-oil metal removal formulations is described with a detailed discussion and analysis of the approach taken and the methodologies developed and applied. Two target applications were identified for cutting stainless steel and aerospace-grade titanium alloys. The key required properties of the fluids for these applications were combined with targets identified for cost, low temperature properties, kinetic viscosity (KV) and oxidative stability. Samples of base oils were obtained and characterised. The oils ranged from commodity commercial and specialist natural vegetable oils to chemically modified vegetable-oil-derived fatty acid esters and polyols. The selected oils were used to create blends which were screened for their key properties. From this work, four blends of base oils were identified for being taken forwards to the formulation screening stage. These blends represented a range of natural and modified oils blended in such a way as to achieve all of the required key properties of cost, KV, melt/pour points and oxidative stability. To determine if the oils were likely to also perform well as metal cutting fluids, they were subjected to a range of tests with and without the addition of certain additives, and their performances were benchmarked against a range of mineral oil and polyol-ester-based commercial fluids currently supplied to the target applications areas. The tests employed were: SRV, microtap and oxidation stability. The issues involved in the extrapolation of results from tribological testing to the prediction of fluid cutting performance are highlighted and discussed. From this work, one base oil blend for each of the two target applications was identified and the best performing mineral and polyol ester benchmark fluids were selected. Full-scale drilling and rigid torque tapping tests were used to refine formulations and to screen other additives identified in parallel microtap tests. The durability, oxidation stability, machine tool compatibility and misting potentials of the final formulations were also benchmarked using a range of standard and novel methodologies—this work will be described in a later paper.     

Characteristics of hydrostatic bearing/seal parts for water hydraulic pumps and motors. Part 1: Experiment and theory

In this paper, the load-carrying capacity, power losses and stiffness of disk-type hydrostatic thrust bearings including the case of eccentric loading are discussed theoretically. The numerical analysis method is established based on a two-dimensional elastohydrostatic problem with an elastic deformation model, which is extended to adapt it for a non-axisymmetric load acting on the thrust bearing. The bearing is made of a combination of stainless steel/stainless steel and stainless steel/plastics. For the elastic materials, the maximum stiffness derived from, i.e., minimum film thickness is, larger than that of the rigid material in the range of a large ratio of pocket pressure and a hydrostatic balance ratio of over unity, which is defined as the ratio of the load to the maximum hydrostatic load-carrying capacity. The maximum load-carrying capacity and minimum power loss can exist in the domain of the hydrostatic balance ratio over unity for the case of the bearing consisting of elastic/rigid materials, in comparison with that composed of the same rigid materials. For the case of water, the power loss due to leakage flow is slightly larger but that due to frictional torque is much smaller than that in the case of hydraulic oil. Then, the total power loss is much smaller than that of hydraulic oil.     

<Emphasis Type="Italic">Development of a Tissue Engineering Scaffold Structure Library for Rapid Prototyping. Part 1: Investigation and Classification</Emphasis>

In tissue engineering (TE), a porous scaffold structure may be required as a template to guide the proliferation, growth and development of cells appropriately in three dimensions. Although TE scaffolds can be created using one of many conventional techniques available, most will suffer from a lack of mechanical strength and/or uniformity in pore distribution and sizes. This study is focused on creating scaffolds using rapid prototyping (RP) techniques. Utilising these novel techniques, a computer-aided design (CAD) of the scaffold structure must first be modelled. The scaffold structure is then fabricated directly from CAD data using a RP system. The objective of this research is to (1) investigate and select various polyhedral shapes suitable for scaffold modelling, (2) classify the selected unit cells, (3) create a parametric library of scaffold structures and (4) verify by building the CAD models using the selective laser sintering process. The first two objectives are covered in Part 1 of this two-part paper. The remaining objectives will be described and discussed in Part 2. ID="A1"Correspondance and offprint requests to: Dr C. K. Chua, School of Mechanical and Production Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798. E-mail: mckchua@ntu.edu.sg