Impacts of the Application of Computer Technology in Process Industries

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IMPACTS OF THE APPLICATION OF COMPUTER TECHNOLOGY IN PROCESS INDUSTRIES L. S. Andersen, T III' I 'l\lil ll ll

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Abstract. In this paper the results of theoretical and empirical investigatlons on the application of computer technology in the production processes of the process industry are presented. A methodology for studying the evolution of technology in general is described. It enables us, in this context, to study various technical and social aspects of the utilization of computers in the production process. This methodology is applied to different parts of a fertilizer plant in a comparative study of new and old technology with a discussion of the incentives for introduction of new technology and the consequences thereof. Also the possibilities of using the methodology in connection with prediction of technological development - as a part of technology assessment in general - is discussed. Keywords. ment. 1.

Computer applications; human factors; economy; technology assess-

INTRODUCTION

ter 2. In this context it is used especially for examining the introduction of computers in the production process. This methodology enables us to investigate the motives and barriers for the utilization of computers in the production process, explaining some of the changes in the organization of work, and the effects on the working conditions.

Since the Second World War we have seen a rapid technological and industrial development. One element in this development has been increased usage of system-oriented and mathematical methods, such as production planning, production control and process control, as parts of a more operational utilization of the production means. Computers have been a tool for the implementation, and the reduction of computer price and dimensions together with improved performance will make this tool still more important in the future.

The methodology has been applied in an empirical study [1] of a fertilizer factory in Fredericia, Denmark, which is presented in chapter 3. There we have made comparative studies of an old plant with conventional process control and a new one with a computerized process control system. These studies concern the economical and technical conditions for this change of technology, the modifications of the organization of work as well as the impacts for the workers. The studies are presented in chapter 4. In chapter 5 another part of the factory, where a new computer control system now is introduced is studied in order to show the objectives behind the actual change and its economical background.

The nature of this technical development and its structural and economical aspects are, however, not very extensively studied from a combined enoineerina and socio-economic point of view. I~ this p~per we will present some results from theoretical and empirical investigations on the application of computer technology in control of production processes in the process industry. The ai m of the paper is to try to point out some directions in the technological development and show their consequences. The research work presented is part of a la r ger project, with its ultimate goal to make an as sessment of the computer technology i n i ndu strial proces ses vi a an i nvestigation of its im plementati ons and effects on various bra nc he s of th e Dan is h i ndustry, thereby crea t in g a backg round fo r un derstanding and, possi bl y , cont rollin g th i s technological ev oluti on.

Chapter 6, finally, contains a summary and discussion of the presented theoretical and empirical investigations, together with some att ~m pts to generalize the results and assess f Ui ure de velopment. 2.

A methodology for studyi ng th e evo l ut i on of technology in general i s pre sented i n chap -

THEORY AND METHODOLOGY

'T he pur pose of technology assessment is not only t o interfere with or check certain tech~)

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L.S. Andersen e t a L.

nologies, but also to predict and judge the consequences in such a way that the societal best possible technology can be chosen and supported: [2 ) Technolooy assessment in this sense assumes that technological develop~ent to a certain extent is predictable and that this development is controllable in some way. In thi s chapter , we will ma lnly discuss the predictability of the process of technological development by outlining its main forces and by sketching the methods we use for relating this theory to emp i rica l stud ies. Frequ en t l y such predictions are chiefly based on studies of existing and future technologies, whereas our point of view concerning the dynamics of technolog ical development is, that its main trend in a market-based economy i s determined by eco nom ical factors and intermed iated by the competi tion between single firms . Clear ly , t he supp ly of technology puts li mits to this development and thus have to form a part of the investigation. Technol ogica l development i s also influenced by ' subject i ve factors' suc h as e.g. the opposition of labou rs towards a new te ch nology. However, in this paper we primarily discuss the ec onomic incentives for technological development. Our theory on techno l og i ca l development is described in [3) and [4), the most i mportant points being that every firm permanently has to seek to reduce it s total costs of production. Cost price reduction i s the motivation for development of technology, and no single firm can in the long run avoid technological development without being eliminated from the market. Technological development is a sys tem-immanent demand in a mar ket-based economy. The demand for cost price reductions can in principle be fulfilled in three different ways: By economy of labour, i.e. reduction of labour costs per product. Fundamentally, this can be done by - introducing machinery requiring less manpower - division of labour so that the total manpower required is reduced or so that the manpower requires less skills and hence is cheaper - increasing the intensity of work by increasing the speed of work or by reducing non-productive time of manpower. By economy of machinery, i.e. reduction of machine costs per product, for example by - exploiting machinery day and night, i.e. introducing work shifts - reducing machine stop time - using better quality, new or additional raw materials to increase machine speeds. By economy of raw materials, e.g. - substitution with cheaper raw materials - better exploitation of raw materials and reduction of production waste

- recycling of waste. It is management's task to find projects complying with these demands. However, a project might very well meet severa l of these goals, being one of the reasons why this way of thinking is not operational to management. However, the reason why we use these concepts is that the type of economy is strongly related to the business cycle. Some of the types of economy are opposed to each other, so e.g. reducing machine stop time and the use of cheap raw materials. Thus, depending on the market conditions, prices, supply of labour etc. one or the other type of economy is preferable. Generally, it can be observed that in the periods of prosperity and unemployment following recessions the work intensifying measures dominate, whereas the tendency to introduce labour-saving machinery is rather weak. In periods of prosperity and full employment introduction of labour-saving machinery is however the most common method to reduce cost prices. In times of recession economy of raw materials is prevalent, in industrial branches struck by th e crisis as well as in branches doing better. Technological development aimed at reducing energy expenses, reducing consumption of raw materials, recycling of raw materials and reduction of waste s will predominate. Industrial branches in crisis will usually have a productive overcapacity. In these branches economy of machinery as well as economy of labour through labour-saving machinery will as a rule not be very attractive since an improved exploitation of machinery only will increase overcapacity. However, all branches are not necessarily hit by failing demand at the same time, implying that technological development in recessions is not re stricted to projects aimed at reducing raw material costs. Prediction of technological development The above outlined connections between economy and technological development can, in combination with studies of the supply of technology give some vague ideas of the trends of technological development. To be able to give more specific forecasts on this development and its consequences, this has to be supplemented with studies of the economic conditions and relations of an industrial branch and with investigations on the level of the individual firms to see where in the production processes the physical barriers to cost price reductions are. Systems sciences as technology The systems sciences (OR, MS etc.) are utilized in all levels of the firm: in production

Impa c t of Computers in Proc es s Industries

planning, in production control, and in process control. In this context systems sciences are to be regarded as technology, since the purpose of using systems sciences in production is to reduce cost prices, as is the purpose of any other technology. Process control systems can physically be described as technology performing control, correction or supervision of an industrial process. Economically, process control can be used according to different demands - by its character process control take over activities formerly accomplished by man, hence economy of labour is an important motive for introducing process control - process control can give better performance of processes - higher yields and less wastes mean economy of raw materials, reduction of machine stop time economy of machinery. At present especially the capacity to reduce raw material costs and in particular retrenchments on energy expenses predominate. 3.

SUPERFOS AND ITS PRODUCTION

The Fredericia fertilizer factory is part of SUPERFOS A/S, one of the largest companies, counted in total turnover, in Denmark. The total number of persons employed is 4700, 640 of which are working at the actual main fertilizer factory in Fredericia. The main product areas of the company are agrochemical, and the fertilizing part of the total turnover is about 30%. The company, which today is the only Danish producer of fertilizing products, covers about 2/3 of the Danish market [5]. The products that are manufactured include superphosphate, PK- and NPK-fertilizers (P phosphorus, K - potassium and N - nitrogen) and acids which mainly are used in later steps in the production. Large parts of the production are exported, especially to the Far and Middle East, Africa and South America. Impor tant secondary products are some flourine salts used f or water treatment and energy which is used for local heating. The production of fertilizers in the actual plant started in 1918 with superphosphate production. The PK-fertilizer was introduced in the midfifties. A new PK plant was built in 19 73 and is now in turn for a major revision. The NPK -fertilizer, which was introduced as a substitute for PK + liquid ammo-

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nia, and which now is the dominating product, is produced in two different plants. The first of these was start~d in 1966 and the other in 1980. Via an ionexchange the NPK-fertilizer can be dechlorinated in a cheap way since the ionexchange makes it unnecessary to use expensive minerals with low ch 1ori ne content as raw ma teri al. The ma rket for NPK-fertilizers in general as well as for this special kind of NPK is growing. 4.

THE NPK-FERTILIZER PLANTS

The NPK-fertilizers are produced as outlined in Figure 1 in both of the NPK-fertilizer plants. The raw materials are transported to the plants through pipes and conveyor belts. The most important raw materials are: phosphate rock, potassium salts, ammonia and sulphuric acid. These raw materials are mixed in a system of reactors, where the chemical reactions take place. The aqueous product of this process is called slurry. It is transported to a spherodizer through a buffer tank. In the spherodizer the slurry is airheated, dehydrated and pelletized. The pellets are continuously led to a system of screens. Pellets larger than 4 mm are crushed and returned to the spherodizer together with pellets smaller than 2 mm. Pellets with correct size are coated to prevent moisture absorption and clogging and after that finally transported to a storage. Brief historical view During the seventies the demand for NPK-fertilizers increased, which in turn resulted in a sequence of extensions of the existing production capacity. In 1978, however, it was decided to enlarge the capacity by building a new plant (NPK 11). There are many sorts of NPK-fertilizers with different composition of N, P and K and the NPK II-fertilizer plant was planned with smaller capacity than the NKP I plant and was supposed to produce the minor series. A computer control system and an extensive alarm system were introduced at the NPK 11 plant. The most important aim of the computer control system was to make it possible to change the setpoint for the transport of all the raw materials into the system in one single operation, thereby achieving a more efficient production.

The NPK-fertilizer plants

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L.S. Andersen e t al .

The control system at the plants The two ~PK-fertilizer plants both produce fertilizer continuously. The capacity of the NPK I plant is three times larger than that of the NPK 11 plant. The technology of the plants is the same except for the control systems. All the control loops of the NPK I plant are of analogue type with setpoint adjustment in the control room. When the production capacity has to be chan~ed, all the setpoints have to be changed separately. Some of the control variables can only be manipulated manually in the plant. Most of the process variables are, however, displayed and can be controlled from the control room. The computer at the NPK 11 plant carries out the same single-loop controls as is done with analogue equipment at the NPK I plant. There are,however, a few more loops at the spherodizer control. As at NPK I only PID control strategies are used. The computer control is active during normal production periods. Start-up and close-down procedures are done manually but changes of product composition are usually done during normal operation. The alarms for almost all process variables are handled by the computer. The computer furthermore ma kes datalogging possible, and the computer reports are used in the production planning. Finally, the communication with the computer is done via visual display units, such as a mimic board, and keyboard. The main qualitative change in the actual process control introduced by the computer thus is the abovementioned improvement in the procedure when changes in the production capacity is desired, leading to faster and more precise changes. The main affect of the computer control system can be seen as an attempt to economize with the machinery, since the improvement of the process performance at production shifts leads to an increase of the overall capacity. The use of manpower at the NPK-fertilizer plants An engineer, a foreman and an assistant are in charge of the day-to-day management at each of the plants. The process workers supervise the production and each of them take care of a certain area of the production. The assistant and the process workers work in shifts, as the plant runs 24 hours a day the whole week. At each plant a number of helpers are associated, two at the NPK 11 plant and seven at the NPK I plant. They do the cleaning-up jobs and any odd jobs. The repair staff takes care of repair and maintenance of the plant. At th~ NPK 11 plant five skilled workers are doing the repairs, whereas there are eight associated at the NPK I. Our investigation on working conditions are directed towards the process workers. There are three process workers associated with the NPK 11 plant compared to eight process

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Working conditions at the plants The workers' tasks at both of the plants are composed of work in the control room and in the plant. The main part of the work is done in the control room where the process is supervised and, if necessary, corrected. In the plant the job aims at reestablishing normal drift conditions after errors that were not possible to correct from the control room. The process workers also take part in the quality control procedures by taking samples from the production. Hence the introduction of computer control has not changed the substance of the work at the NPK 11 plant very much compared to that at the NPK I plant. There are, however, important qualitative changes due to the improved overview of the process at NPK 11 and the alarm system offered by the computer system. Both make it possible to have a more annotated view of the status of the process. This makes more precise and earlier interventions in the process possible before more fatal defects might have occurred. On the other hand this means that the process workers' job is more orientated to the control room, and more of the interventions in the process are done via the keyboard and not directly at the process. This can be seen as an increased abstractification of the working situation. The process workers' nonactive time in the control room is not, as it is often seen [6), used for e.g. cleaning-up or maintenance. The reason for this is that the response time in alert situations, when a fast reaction is needed, might increase, and hence the risk for production stops. This is highly undesirable. The situation can be interpreted as a desire to economize with the machinery instead of taking the risk it might be to use the process workers in other situations, i.e. economy of labour. At the factory, the growing size of the machinery has led to an increased attention on the maintenance and repair work, resulting in a new organization of this work. It has been systemized and split up so that e.g. lubrication is more systematically done and put on a firm scheme, instead of being done more occasionally. Furthermore, skilled workers are employed to fulfil these jobs. As a whole, this means that the machinery continuously can operate on a higher level and the risk for production stops is further decreased. Hence, these changes of organization can be seen as another aspect of the economy Jf machinery instead of trying to economize with labour by using more compressed working schemes or less skilled workers.

Impact of Computers 1n Process Industries

Fig. 2. 5.

The PK-fertilizer plant

THE PK PLANT

PK-fertilizer is produced in a continuous process roughly as outlined in Figure 2. The raw materials are superphosphate made in another part of the factory, potassium salt and some micro nutrients. The granulation drum is filled from one end with the raw materials. The filling is automatically controlled by band weights to ensure the correct composition and a constant flow. Water and steam are added while the drum rotates so that pellets are formed. From the other end of the drum the pellets are transported to the drying drum and afterwards they are cooled and screened. Pellets bigger than 4 mm are crushed and returned to the granulation drum together with the pellets smaller than 2 mm. Those with correct size are transported to the storage and eventually filled into sa cks before delivery. Three process workers run the process. One of them fills the storages with raw materials. Another mainl y sits by the granulation drum and controls the addition of stea m and water in order to run the process, so that the greatest possible number of pellets are of correct size. The third worker controls the t otal pro ces s from a control room with instruments , alarms and a visual display unit. He control s e .g. the raw material supply acccrd ing to t he des ired composition of the product and the maxi mum production ca~acity . He al so wo rk s outside the control ro~- i~ case of mech an ical problems and C~E:!r"'. ~~~ - ... J .

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energy consumption is to reduce the returns from the screen. Normally about 40% of the pellets are recycled, thus the process in the granulation drum is crucial. Until 1981 the granulation process was operated manually. The worker can look into the drum from the upper open end and his observations form the basis of his operations. Together with measurements of primarily the energy consumption to turn the drum and analysis of samples from the screen he controls the water and steam addition. This result of manual control is very dependent of the workers watchfullness and experience. His job is complicated by the time constants of the process. After a control action it takes 3-4 minutes before he can observe the effect in the drum and fully 45 minutes before it can be registered on a sample from the screen. In 1981 the process variables were analysed in order to automatize the control of the granulation drum. It was found that a control strategy based on measurements of the energy consumption to turn the drum and,as a first attempt controlling the water addition would give reasonable results. Other necessary inputs are the amount of raw materials and steam - both are kept constant. The company decided to invest 40000 $ in a micro computer and other hardware. The software should be developed at the factory. It is supposed that there will be the following profits : 1. Cost price will decrease by 6000 $ with a 1% decrease in returned pellets from the screen because of lesser energy expenses. 2. The capacity of the plant will increase by about 4000 tons produced fertilizer per year for every 1% decrease in returned pellets - corresponding to a profit of 50000 S. Thus, with just little success the invested mo ney will be back in a short time.

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\,iorkers .

Co nse quen ces pointed out the purpose of the automatic control i n t he PK plant is economy of raw materials (e ner gy) , but it will highly influ~r ~e the wo r ki ng conditions.

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Pro ces s control The granul at io n of fertili zer (e~~j(E: ~ 1:: of energy mai nl y because of the drjin~ ~it h warm air before screen i ng. {-,s a result of the increa s ing energy pr i ces the oi l e/penses made up abou t 5 0 ~ of t he cost pr ice in 1920 , the second largest expen se being el ect r icity and wages the third. A way to r edu ce the

is no in t ent ion to reduce the working staff . However , some manual activities will be ta~en over by the computer. At present the comp ut er only co nt rols the process in norma l si tuat ions and not when the produc~he re

L.S. Andersen et al .

518

tion is started, stopped or the product composition is changed. Hence the worker will still have some control functions at the granulation drum but as the automatic control is improved there will be fewer manual interactions with the process. Instead the worker will get other j obs . The idea is that he should be used for raising the cleaning standard in the plant and more frequent inspection of the machinery to lower the risk of production stops. During the introductory part of the computer control, the control of the granulation will alternately be done automatically and manually. The management hope s that a consequence of this will be that the working staff will work harder to prove, that they are better than the computer. In this case the production will increase even if the automatic co ntrol does not succeed. Thus, although the primary motive for the introduction of the control system is reduction of energy costs, substant ial gains will be obtained by economy of machines and economy of labour. 6.

SU~1t'1ARY

AND DISCUSSION

A crucial point in technology assessment projects is the prediction of the direction and the speed of future technological development. We have argued that this cannot be done on the basis of knowledge of the supply of technology alone, but that economic conditions internally in the firm and overall economic conditions influen ces technological development. From SUPERFOS we have presented some examples of this dependence - the change from batch to continuous production of the PK plant in 1973 caused a reduction of the staff from 10 to 3, and thus illustrates the fact that in times of prosperity and scarcity of labour, economy of labour is predominating the purpose of the introduction of a computer based control system at the PK plant in 1981 was mainly to reduce energy costs crisis and economy of raw materials corre late strongly the construction of the NPK 11 plant with its computer based control system in 1978 i s an example of economy of machinery . Due to increasing demand of fertilizers this seems to have been a profitable investment in defiance of a general economic recession. Although these examples are retrospective, they illustrate some forces in technological development that must be taken into account in technology assessment projects. Supply of technology In the first years of computerized process control, a substantial amount of work was done to find a methodology aimed at con-

structing a globally optimal on-line computer system, integrating the different levels of planning and control in the firm. However, it was perceived that the idea was unrealistic, and since then the development of smaller, cheaper and more efficient computers has lead to a fast evolution of algorithms and methods for local control systems . Current ly, a development towards an integration of control systems can be observed. This implies that the local control systems gradually are connected, thereby establishing a subopt imal realization of the total network and a possibility of a larger degree of combination with higher levels of production planni ng and control. Once such a distributed system of computers i s in sta lled, the flexibility of the total system towards outside and inside fluctuations and disturbances greatly increases, making further economizations in the production process easily implementable. Working conditions Our investigation s at SUPERFOS have shown that evaluating the consequences of the introduction of computer technology for labour is rather ambiguous and rather depends on the economic objective for the change of technology than the technical details in its realization. Thus we found, that the computer control installation at the NPK 11 plant only changed the s ubstance of work marginally, and that at the PK plant some control activities formerly accomplished by a process worker was taken over by the computer control system without, however, having any direct effect on manpower consumption. St ill, this cannot be genera lized. Introductio n of computer control in other industrial branches has i.e. in the Danish breweries led to more radical transformations of the quantity and quality of work. The reason why the effec~ of SUPERFOS are relatively sma ll may be ascribed partly to the fact that the production is very capital intensive and partly to the nature of the fertilizer production which even in closed loop - with the present state of technology - is very sensitive to disturbances requiring a rather large amount of human interference. On the long view technological development will probably tend to stabilize the process, making possible cost price reductions due to reduced manpower requirements and in particular reduced machine costs per product based on increased efficiency. On t he short view efforts of reducing raw material costs will probably continue to characterize the technological development.

Impact of Computers in Process Industries

Further research Seen as a technology assessment project our activities up till now are insufficient. To complete this a thorough investigation of alternative future technoloaies as well as a study of the limits to the control of technological development and the authorities to execute this control would be necessary. Immediately, our plans are to extend the analysis to other levels of utilization of systems sciences in industry - production planning and control - and to enlarge the empirical basis with continued investigations in the fertilizer, the brewery and the slaughtering industries. AC KNOWL EDG EMENT We are most grateful to SUPERFOS, Fredericia, especially L. Kj~rgaard Rasmussen, J. Holler Birkeb~k and A. Stottrup, for their kind hospitality and for the possibility to make this empirical investigation at the ferti1i zer factory. REFERENCES [1]

Lars S. Andersen and Ulrik Larsen: Procesregulering i industrien. (Process Control in Industry). In Danish. IMSOR, Lyngby 1981.

[2]

Teknologivurdering i Danmark. (Technology Assessment in Denmark). Report from a committee appointed by the Council of Technology U1inistry of Industry). In Danish with a summary in English. Copenhagen 1980.

[3]

Henrik K. Jacobsen and Per H. Jespersen: An Approach to the Assessment of Automation Technology. IFAC 3rd Conference on Systems Approach for Development, Rabat, Morocco, 1980. The approach is mainly based on

[4]

JUrgen H. Mendner: Technologische Entwicklung und Arbeitsprozess. In German. Fischer Verlag, Frankfurt a.~1.,1975.

[5 ]

Annual Reports from SUPERFOS A/S.

[6]

O. Mickler and others: Technik, Arbeitsoraanisation und Arbeit. In German.- Aspekte, Frankfurt a.M., 1976.

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