Unpublished paper.

S F Bush with E P B Jongen.

Summary

The paper describes the analysis and computation carried out to model a manufacturing and marketing complex spread over several countries. Without loss of generality the model has been specifically applied to a polymeric materials business encompassing chemical and prepolymer precursors.

The model has been designed to have a variable structure so that changes to the nature and shape of the complex can be read in as data in the same way that parameters such as costs and efficiencies usually are. Because of this facility, the model provides a ready tool not only for optimisation, but also for assessing the strategic effects of possible future conversion technologies and for setting technological targets in the light of likely movements in resources and labour costs, costs of capital, changes in exchange rates and end-use demand.

The model has been designed to support both the planning and budgeting functions. While advantageous in itself, this dual objective was also necessitated by the practical circumstances in which the model was constructed, namely the large quantitities of data which have to be assembled and reconciled if the results from the model are to carry conviction. Accordingly the model output can provide reports on material flows, grade costs, and annual budgets for all or any part of the complex.

An example of the results obtained from optimisation of the full complex (with product details suppressed) is given and compared with the results from the standard sub-optimisation procedures in force. A number of the problems inherent in such procedures – transfer and coproduct pricing, overhead and capital allocation – are highlighted to show where conventional procedures can lead significantly away from global optimisation.

See also the section on Mathematics & Computation.

Systems Technology Report, ICI Europa

S F Bush with D Pauwels.

Summary

The MDI Flowpack I model exists in 2 versions – one relevant to the M2 plant at Rozenburg, the other relevant to the loop reactor modification of the M1 plant at Burnhall. These models are operational at Rozenburg and Runcorn.

Flowpack II equivalents of both versions have been constructed. The loop reactor M1 version works well, but problems still remain with the Flowpack II version of the standard M2 plant. These problems centre on the representation of multiphase R1 and its associated temperature control. Temperature control cannot be represented in the same way as in Flowpack I, owing to the absence at the time of writing of a specific temperature actuated flow control subroutine in Flowpack II. Results for all cases tried are summarised in this report, together with recommendations for use and improvement.

Systems Technology Technical Note, ICI Europa.

S F Bush with I M King.

Summary

Following on earlier versions, the treatment of dispersion and mixing in the reactors has been considerably elaborated. In particular finite rates of turbulent and molecular diffusion are allowed for. In this interim account, predictions of the urea formation from this model applied to the conditions of the Blackley Laboratory rig are compared with the experimental results which were reported after the model predictions. A simplified treatment of the effect of agitation and injection on the side reactions (notably to urea) is appended.

Paper, Systems Technology Group, ICI Europa

S F Bush

Summary

Systems Technology is of growing importance to industry because of the increasing emphasis on performance. The performance of a business, works or process, is rarely the sum of its parts separately determined. The need has therefore arisen to manage the complexity arising from the large number of factors which determine the whole. Meeting this need is the function of Systems Technology.

Section 1 of the paper outlines basic concepts which have been shown in real life to meet this criterion. Sections 2 and 3 illustrate their current and potential value by describing briefly some of the resulting methods developed, and applications made, over a number of years to unit operations, particularly chemical reactors, processes, polymer processing, factory control, and business planning. Examples are taken from the chemicals, fibres and plastics fields.

While not universally appropriate, a contribution common to most of the projects and fields tackled has been to perceive a common structure to two or more disparate problems and thus to decompose optimally otherwise very intractable problems. This opens up what seems to be a fruitful and systematic mode of technology transfer which is only at the beginning of its development. Examples are highlighted in sections 2 and 3.

A common need in many projects is to determine the boundary of the system considered and the appropriate level of theoretical and experimental or observational detail within it. A systematic procedure has been evolved for this, which while in many cases can be regarded as only common sense, has a clear relevance both to the conduct of a particular research project and to judging its likely cost and benefit.

Systems Technology Group paper, ICI Europa

S F Bush, revised 1st June 1978 and again on 31st January 1979.

Summary

The paper describes ideas of a mathematical nature which have been developed and applied to the fundamental design of process systems, the emphasis being on those in which there is combined flow and chemical or physical state changes. The development has been designed specifically for digital computation and allows the structure of any particular model, especially its geometry and the basic processes of physical or chemical change to be as accessible to alteration as individual parameter values commonly are. The structure is designed to simulate real systems directly rather than their differential equations and in this way avoids or mitigates some important problems of a numerical-mathematical character. Examples are given. The structure is designed also to facilitate the elucidation of experimental data, particularly its scale-dependency. The overall development is exemplified by the experimental and computational analysis of chemical kinetics problems treated in Bush and Dyer (1976).

Systems Technology Group paper, ICI Europa

S F Bush

Objectives

1) To recall earlier Company work on the prediction of flammability characteristics, illustrating in particular two features:

• the dependence of the results on the physical as well as the chemical parameters of the burning situation;
• flame speeds increase with the scale of the installation.

 
2) To suggest follow-up steps should it be decided to pursue the approach in the plastics field.

Systems Technology Group paper, ICI Europa

S F Bush

Introduction

No general case can be made covering all types of investment. Most, of not all, of ICI’s investment in the last 10 years has gone into maintaining rather than expanding the size of its profits in real terms (even in 1974, see Appendix).

The most powerful argument for continuing to invest in the CEEC is to maintain the value of the existing assets represented by a trained work force and developed sites. This would set the future investment split between the UK and the CEEC as broadly equal to the existing split.

On its own, the argument of proximity to the market is hardly borne out by experience, i.e. exports from the UK have been consistently more profitable than local manufacture. The interface the customer presumably needs is an effective locally based technical service and it should not be necessary to build a plant to achieve this.

In more detail, some arguments for and against, seen from a UK point of view, can be set out.

Systems Technology Group paper, ICI Europa.

S F Bush

Objectives

The principal obstacles to getting appropriate polyester fibres quality have been:

• lack of clarity about and quantification of quality and
• problems of selecting appropriate means to control the process against the product objectives.

Very considerable and successful efforts have been made in recent years in all parts of the ICI Group to remove both obstacles. This paper is designed to summarize the results of the ICI Europa Systems Technology Group work in the last 3 years, it being understood that much of it has been done in close collaboration with factories in Europa territory, the UK and ICI Fibres RTD. For pressing commercial reasons results have been directed at improvements to the appearance of piece-dyed fabrics. However, the basic understanding developed has always been seen to have application to other polymer products, to the design of unit operations, and to the evaluation of technological strategy.

Systems Technology Group Technical Note, ICI Europa.

S F Bush with S Baillie-Strong.

Summary and Conclusions

1. Major variations in texturised yarn dye-uptake were observed which correlate strongly with time at spinning and clearly moved in sympathy with pack pressure and Draw Tension Integrator date at spinning.
2. The most likely cause of these variations was differences in moisture content of the polymer fed to the driers causing hydrolysis and molecular weight changes in the spun yarn.
3. These variations caused about 20% of the total package-to-package variability with shifts of almost 2 dye-shades in mean level in about 36 hours. These magnitudes are for Turquoise CG dye at pressure – a typical continental customer requirement. The recommended quality control dyestuff, Navy D2G, probably underestimates these variations.
4. The cause of gross variations in polymer moisture content should be eliminated. However, since the polymer transport system (Tote Bins) cannot be hermetically sealed and since the chip moisture content is below atmospheric humidity, some variations will always be present. A drying control strategy to deal with these variations with the aid of a drying model should be developed.
5. The same magnitudes of changes in initial water content and yarn i.v. have been obtained by other investigators on 167 f30 at various times from January 1974 to the present.
6. The calculated i.v. to water content sensitivities agree closely with measured values.

Process Technology Dept Technical Note, ICI Europa

S F Bush

Summary

The adaptation of the fibre drawing model to the spin draw model requires an estimate of the heat transfer from the individual filaments in the quench system following the spinnerette. An estimate is made of the growth of the boundary layer surrounding each filament in a typical 44 filament bundle, and the corresponding heat transfer coefficients.

See also the section on Applications to Existing Products and Processes.