A U T O M A T I O N ON M E T A L L U R G I C A L P L A N T S

AND THE FEDERAL REPUBLIC OF G E R M A N Y

G. D. S u r g u c h e v

IN A U S T R I A

In 1966, Austria and the Federal Republic of Germany (FGP0 produced 2.2 and 25.4 mil l ion tons of pig iron, 3.2 and 35.3 mil l ion tons of steel, and 2.3 and 24.2 mill ion tons of rolled stock, respectively. In comparison with

1965, the production level remained the same or was slightly decreased. However, the economic recession of in- dustry in these countries did not prevent a number of firms from pursuing and developing activities directed to

automation of metal lurgical plants.

In 1966, an IBM 1140 computer had been installed at No. 7 blast furnace on the Ruhrort plant of the firm

August Thyssen in Duisburg (FGR) to calculate thermal balance of the furnace and, on its basis, the specific heat

per ton of pig iron. On the basis of a correlation interdependence between specific heat and silicon content, the

computer signallizes the need for a change in the hot blast temperature. The use of the computing system made it possible to raise the hot blast temperature to ?0~

The gas analyzing system is of interest; it has been developed jointly with IRSID (France) and installed on the plant by the firm Trindel, jointly with Hartman and Braun. The system employs standard gas analyzers "Uras* and "Kaldos" of an absolute accuracy brought by special measures up to 0.01%, owing primarily to thermostatic tempera-

ture control of the transmitting element. The system has been installed in an air-condit ioned room. The tempera-

ture in the cases where the transmitting elements are located changes within the limits of + 1~ and that inside the

e lement changes within • 0.1~ The sampling system is blown through and the zero point of the transmitting e le-

ments is adjusted automat ical ly every 4 or 8 hours. Standard mixtures in gas bottles are used for this purpose. The

system notes the indicat ion of the transmitting e lement every 10 sec, works out a calculat ion every minute, and

makes a recording every 30 min. The computer operates 85% of all heats; 15% of heats fall out on account of poor

working conditions of the furnace. According to statements by representatives of the firm, no t ime is wasted on ac-

count of the electronic part. The computer is operated by five persons. The system has already paid for itseIf, ow-

ing to the rise in hot blast temperature (approx. 1 mil l ion Marks FGR).* Besides that, pig iron of a more homo- geneous composition as to the silicon content was obtained.

The oxygen converter process is being thoroughly studied as an object of automatic inspection and control. On converters of the Austrian firm Voest and on all other converters in Austria and the FGR, the measurements of

steel temperature are conducted using exchangeable tips with a cardboard mouthpiece (developed by the American

firm Leeds and Northrop). The simplici ty and rel iabil i ty of the arrangement make it possibIe to dispense with a special worker. The cost of one measurement amounts to 20 Austrian shillings.I"

An experimental laboratory 5-ton converter applied to studies of new technology is operated by the firm

Voest. In particular, tests were conducted with a new shielding cap, ~Thermoterm ", for continuous measurement

of metal temperature. The caps manufactured at the Plansee plant in Tirol are based on cermets and exhibit a

melt ing point of approx. 2200~ The cap is of the single-layer type so that the dynamic error of measurement is reduced. It stands 17 heats. Studies are also being conducted on the converter to set up a mathemat ical model of

a converter heat. The mode1 is based on material balance equations, and makes use also of continuous information on the metal temperature.

In the development of a system for continuous temperature control of molten metal in a converter conducted

by the Max Planck Institute in Dusseldorf (FGR), no task such as to obtain a shielding tip which would stand several tens of heats is pursued,since this would unavoidably bring about an increase in tip thickness and in the dynamic er- rors of measurement. One of the tasks of the research is to improve the stability of the stone in which the thermo- couple is contained so far that it would stand 300-400 heats (at present, it stands 80 heats).

*The exchange rate on March t, 1968 was 100 Marks FGR to 22.50 rubles. J'The exchange rate on March 1, 1968 was 100 A. shillings to 3.48 rubles.

Translated from Metallurg, No. 8, pp. 36-37, August, 1968.

439

5

.=~ ,7

~m6

o

0

3

~2 Ore, 3 "Ca~7

I g I C~f,.#~ _

r / 2

Fig. 1. Lance position control based on converter noise information: 1) noise intensity; 2) lance

height, m; 3) lance hoisted up.

In the development of automatic control systems for

oxygen converter processes, the leading post in the FGRis

held by the firm Fried. Krupp. The Central Scientific Re-

search Institute of the firm in Essen, together with the firm Siemens, are conducting studies on the automation problem

using a 8-ton laboratory converter specially equipped for

this purpose. The converter is installed in a hall of a 2200- m 2 floor space, where there are a cupola, an electric arc

furnace, and a 3-ton revolving barrel furnace for melting pig iron. The converter runs about 200 experimental heats

annually. In addition to the usual indicating and control instruments, the converter is equipped with Siemens-Halske

automatic gas analyzers, a device for continuous tempera-

ture measurement of the molten metal, a system of thermo-

couples for controlling the temperature of exhaust gases, devices for measuring the elecLric conductivity of the bath,

the intensity of flame radiation, and the converter noise, and a computer system for calculating the inspection and

control criteria of a converter heat.

The system for lance position and oxygen supply control, developed by the firm, assumes that these param-

eters are controlled on the basis of a calculated quantity characteristic for the oxygen distribution between meta l and slag, and also in dependence on the rate of carbon removal and the heat flow of the exhaust gas. The quantity

that characterizes the osygen distribution is responded to in the system by changing the lance position; the two other

quantities bring about changes in oxygen supply.

Satisfactory results of the research work on the g-ton converter made it possible for the firm to start assembling a system in a converter shop at the Rheinhausen plant in Duisburg. There are four 60- to 90-ton oxygen converters

there, three of them in operation. The shop treats high-phosphorus pig iron, employing the practice of skimming off

the first slag. The fourth converter is supposed to be used as an experimental uni t where the assembled system is to

be applied. Instead of industrial gas analyzers, a GD 150 mass spectrometer developed by the firm Fried. Krupp Mess- und Analysentechnik in Gremen was used for elements of molecular weights from 2 to 300 in order to in-

crease the accuracy and rel iabi l i ty of the gas analyzing system, the application of which has constituted the main

difficulty. The mass spectrometer provides for analyses of the exhaust gases for CO, CO D N 2, and Oz.

The information on the converter noise intensity, which can be obtained with a microphone at a frequency of

650 • 200 Hz (Fig. 1), is used at the plant for controlling the lance position. The lance position is adjusted manu- ally, and provides for an increased rate of slag formation and a longer service life of the lance. Manual adjustment

of the lance position on the basis of information on noise intensity is being implemented in a number of other piants

in the FGR.

At the Rheinhausen plant, an analog computer installed in the workshop is used to calculate cooling additions

in the second period of the heat. The developed algorithm is the same for all three converters, and provides the

basis for thermal and material balance. The carbon and phosphorus contents, the temperature at the end of the first

blowing period, the weights of molten steel and lime in the second period, and the assigned metal temperature are

fed as an input information into the computer. The device calculates the amount of oxygen for blowing and the

weight of iron ore in the second period. According to an announcement by plant representatives, the device works reliably and the operators like using it. For 90% of all heats, the error in tapping temperature of the metal consti-

tutes i 15~

There is an automatic blooming mil l in operation at the same plant, For rolling of various steel grades, 20

strict programs were worked out and one of these is then selected to suit the order. Changes in ini t ia l conditions of

rolling, e .g. , in ingot temperature, are not taken into account.

An interest in the problem of automation of oxygen converters is also displayed in the Bochumer Verein plant

owned by the same firm. According to plant calculations, the cost of additional blowing with coke or ferromangan- ese on account of insufficient bath temperature represented an additional expense of 6.8 Mark (FGR) per ton steel. An investigation carried out at the plant aimed at the objective of working out a computation method for determin- ing the amount of cooling additions and the blowing time. The final C content and temperature, the changes in pig iron composition, and the amounts of l ime and fluorspar in the charge were used as an ini t ia l information. For heats where C ~ 0.28%, the end of blowing is determined from the character of the flame, and the problem is re-

440

duced only to ca lcula t ing the cooling additions; however, both parameters are ca lcula ted for heats where C = 0.8-

0.8% (comprising 80% of a l l production). The results of the investigation are summarized as nomograms. The error

in ca lcula t ing the blowing t ime constituted :t 18 sec when the pract ice of skimming off the slag in the hot meta l

mixer or the torpedo ladle was employed. The appl ica t ion of the ca lcula t ion method is par t icular ly effect ive ,~hen working without the hot metal mixer.

On the plant, however, i t is not intended to install the com~uting system in the workshop as it is not expected that an essential improvement of the production and economic parameters would be achieved, as compared to the appl ica t ion of the nomogram-char ted results. It is interesting to note that the firm Fried. Krupp, in spite of diff i- culties concerning capi ta l investment resources, is strongly pursuing automat ion act ivi t ies .

At the Huckingen plant of the firm Mannesman A. G. in Duisburg as weli as in Paderwerk Bentler in Padder- born, there are au tomat ic balances in operat ion for weighing the meta l in teeming ladles. The indicators are loca- ted on the crane trol ley and a d igi ta l indicator is in l ine with the cabin. According to firm representatives, the sys- tem works rel iably.

At the Sa]zgit ter plant, where there is one 70-ton oxygen converter; the information on the converter noise

intensity is used to control the heat parameters. A system of au tomat ic oxygen supply and lance position control is mounted in the oxygen converter. The information on the carbon removal rate, as obtained in ca lcula t ing the ma- ter ia l ba lance , is stored in the memory of the system. In 1968, a broad sheet roll ing mil l comprising a hot and a cold rolling train for sheet up to 2000 mm broad and up to 0.4 mm thick started operation at the plant. The mi l l production is l imi ted by the throughput of the soaking pit, and attains 200 tons/h. The hot - ro l l ing train is au toma-

t ized complete ly . A looped roll ing mil l controller serves to equal ize the speeds between individual stands. The sheet thickness is measured on the basis of x- ray indications, and a control command is t ransmitted to the rolls of the fourth stand, th.en to the third, etc. The temperature of the finishing end (about 900~ is mainta ined constant by increasing the rolling speed in relat ion to band cooling.

A number of firms (Voest, Austria; Mannesman, FOR) are conducting intensive studies on setting up systems of

operat ional planning and management of compl ica ted production complexes (workshop, plant, firm) with the use of computers. Within the scope of these act ivi t ies , the firms at present pract ice logging and processing of industrial data. Representatives of the firms foresee great prospects for the introduction of these systems.

44-1