Proceedings of the Institution of Mechanical Engineers,Part E: Journal of Process Mechanical Engineering

The President refers to his early career in teaching and research and outlines some of the benefits. He identifies his involvement in offshore engineering as one major turning point in his career. It was a great opportunity for real collaboration between industry and higher education; progress usually required a multi-disciplinary approach and commitment from engineers, scientists and managers alike. Having added subsequently to his direct experience of industry, commerce and government departments and to his contacts with other professions in engineering and science he offers a few of his own thoughts on the health of smaller manufacturing companies, on the environment and on waste, each a matter critical in its own way to our future, nationally and globally.

In short-cycle batch production processes difficulties are experienced in the direct measurement of temperature in high-viscosity fluid mixing environments. There is often a need to penetrate high shear flows with the sensor to ensure that measurements representative of bulk temperature are obtained. Significant measurement errors are experienced due to the temperature differential between the bulk of the fluid and the surface of the probe. The resulting strength requirements of probe supporting structures also contribute errors as a result of additional heat capacity and additional heat conduction paths from the sensors. This paper presents research towards the design of a multi-sensor probe integrated with computational algorithms devised to reduce these effects. Initial trials demonstrate that such schemes can be applied to reduce steady state errors and to improve response times over existing measuring devices.

In preparation for the coming into force of the Pressure Systems and Transportable Gas Containers Regulations (1989), two Seminars were sponsored in May and June 1990 by the Process Industries Division, North West Centre, and the Pressure Systems Group of the Institution of Mechanical Engineers.

New ground is broken in the Regulations in the primary duty of compliance being placed on the users of fixed pressurized systems.

Mr Towndrow's paper (Part 1) describes already proven engineering management and control procedures that meet the user's new responsibilities and outlines further changes required during the four year lead-in programme.

The scope of the legislation for gas cylinders has been greatly extended in variety, size and new technology. Dr Irani's paper (Part 2) traces the improvement in cylinders, and draws attention to new procedures on filling, rerating and repairs. He demonstrates the contribution of British Standards to gas cylinder development and anticipates the Regulations forming a valuable input to the proposed European Directive currently being drafted.

The Pressure Systems and Transportable Gas Containers Regulations (1989) provide a legal framework for many of the existing voluntary procedures in the process industries. The presentation outlines how ICI's inspection procedures have evolved in recent years, and how they will be able to meet the requirements of the new legislation. While designed primarily for an in-house inspection organization, they are also applicable where a third party inspectorate provides the inspection service to particular works.

The primary aim of this paper is to highlight the major areas where changes will take place in the realm of gas cylinders and the various steps taken by the gases industry to enable a smooth transition into the future as a result of the Pressure Systems and Transportable Gas Containers Regulations (1989) which came into force on 1 January 1991.

Transverse instability in four-high mills is controlled by the usual guiding methods which on occasions are inapplicable. Its main cause is tilting of the work rolls on their backing rolls. A simplified conception of the strain distribution yields a manageable relationship between asymmetry of load and the roll gap taper. The proximity change between the work and backing roll chocks due to tilting is large compared with the change by symmetrical load and is thus potentially suitable for a signal to control guiding. Transverse rigidity is considered.

The development of process machinery poses certain special problems which are additional to those normally encountered in engineering development. In industries as widely different as oil refining, textiles, or agriculture, the equipment suppliers must all link into a lengthy process chain, they must deal with the question of process material spoilt during experimental work and they have to resolve the problem of the ownership of design know-how arising from operating experience gained by the processor. These problems have a significant influence on the development strategies adopted in different industries. On technical matters it is usual to try to isolate the machine from the process chain by using specification parameters. Five levels of abstraction in defining the parameters are described. On the commercial side the relationship between the manufacturer of the machine and the company operating the process must be established in unambiguous terms at the outset. Depending on the degree to which the machine manufacturer can later accept responsibility for some processes matters, various arrangements can be agreed for the future development of the machine and process and for the running of plant trials.

Description of particle shape is of wide importance in the engineering industries. Although the theory of polygonal harmonic shape analysis has been presented previously as a method for characterizing rugged particles, detailed computer implementation has not yet been described. Particle and object images have been digitized using a video camera and personal computer, and their harmonic persistences determined. The harmonic persistences are shown to relate to computer generated Fourier shapes with zero phase angle, but not to relate to Fourier coefficients describing rugged silhouettes. A relationship between the second harmonic persistence and aspect ratio is demonstrated, and it is verified that polygonal harmonics, combined with a surface roughness index, provide a general scheme for particle shape description as has been previously suggested.

Reports on multi-flight screw metering of free flowing solid particles, with side entry feed, could not be found in the available literature. But since the author worked to investigate its applicability as a seed metering mechanism for grain drills, the present work was considered essential as the first step. For this purpose, samples of 15 different free flowing particulate materials were closely sized and a test rig designed and constructed. Nine rotors of three, four, and five slots or flights were considered at speeds of 20, 40, 60, 80, and 100 r/min as desired. All experimental runs were replicated three times and the average values of the volumetric flowrates for each material, speed, and rotor were found. At the end a total of 410 data points were considered for analysis of the data based on dimensional analysis. The variable dimensionless groups were selected and analysed in such an order to produce linear relations. The overall results can be represented by the following equation:

It was concluded that metering, as described by the above equation, was predictable within the limits considered for each dimensional group studied.