Blast furnace measurement and control techniques have made a great advancement on the basis of remarkable developments in recent electronics, optics and computer technology so that they can meet the requirements for the blast furnace operation. The resulted measurement and control techniques, however, are not always satisfactory from the viewpoint of the final target of the author, “the comprehensive overall operation control system that enables automatic control of the blast furnace.”
Thus, the current level of measurement instruments and control models are made clear, and their problems and future elements to be provided are discussed from the viewpoint of blast furnace operators.

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Gas distribution control has remarkably contributed to the stabilization of blast furnace operation and the improvement in efficiency. In Kawasaki Steel Corporation sensors for gas distribution control and their quantification have been developed.
In this report the following items are described.
1) Survey of the sensors for gas distribution control.
2) Quantification of gas temperature distribution and gas component distribution by use of discriminant function analysis.
3) Three types of burden profile meter newly developed by Kawasaki Steel Corporation.
4) Their correspondence to actual blast furnace operation both macroscopically and microscopically.
Above mentioned sensors were used effectively in actual blast furnace operation. Efficient and stable operation of blast furnaces have been kept in Kawasaki Steel Corporation.

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At No. 2 blast furnace of Sakai Works, effort is being made to develop and practically apply new types of sensors (magnetometer, and gas flow meter) and probes (shaft diameter probe, shaft wall probe, etc.) for accurate measurement of gas flow distribution and burden behavior in the lumpy zone. Mathematical models for estimation of the state of lumpy zone and the outer profile of cohesive zone in the furnace have been developed. The cohesive zone model is composed of simultaneous ordinary differential equations including heat transfer equations and material balance equations, and the Runge-Kutta-Gill method is employed to obtain numerical solution for this model. By using the information from these new probes and models several new findings have been obtained.

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For the successful control of the hot metal temperature of the blast furnace, it is necessary to measure accurately the operational data such as blast conditions, charge conditions, and top gas compositions which are to be input to the control model. By the use of the mathematical simulation model of the blast furnace, the required accuracies of measurements for the control of the hot metal temperature are investigated. It was found that the measurement accuracies of the N₂ content and the CO₂ content of the top gas, the Fe content of burden and the blast flow rate were not enough.
The followings were carried out in order to improve the accuracies of the calculations of the material and heat balances and the accuracies of the prediction of hot metal temperature.
1) Development of the highly accurate gas-chromatography 2) Development of the sinter property tracking system 3) Check of the measurement accuracy of the blast flow rate 4) Improvement of the measurement timing of the hot metal temperature
Owing to these improvements, the automatic computer control system of the hot metal temperature could be applied to Kokura No. 2 BF for 2.5 years until the blow out of the furnace and this system had contributed to the stable and low cost operations.

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A probe for detecting alkalies in the ascending gas in a blast furnace by an optical fiber cord connected with a spectrometer was developed and tested in the 29th operation of an experimental blast furnace in August 1981. The absorption spectra of Na and K were detected at a region in the vicinity of a raceway, where observed temperatures were 1300-1400°C. The concentrations of Na and K were roughly estimated to be 0.001% and 0.015%, by extrapolating calibration curves obtained experimentally at 1000-1200°C to an assumed temperature.

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A new fine multiple thermocouple sensor (FMT sensor) for the measurement of refractory lining erosion of a blast furnace is presented. In the newly developed sensor, the temperature sensing parts of several sheathed thermocouples are arranged longitudinally parallel. They are accommodated in an external sheathing tube in such a manner that these thermocouples are prevented from coming into mutual contact by means of insulating refractory materials. The sensor can simultaneously measure the temperature variations at several positions in the refractory lining.
A method of analyzing the FMT signals (The Trigger Response Method) has also been developed for calculating the remaining thickness of refractory lining in the shaft of a blast furnace by analyzing the time-delay occurring in the propagation of temperature variations in the lining. By applying this method to 19 months of field testing in the shaft of No. 1 Blast Furnace of Kobe Works, it was possible to estimate the extent of erosion of the refractory lining within an error tolerance of less than 5%.
A method of analyzing the temperature distribution in the lining (The Profile Coefficient Method) has also been developed for estimating the profile of lining erosion in the hearth by introducing the Profile Coefficient defined by the solution of the finite element method in which the boundary conditions are determined indirectly by using measured temperatures in the lining. This method was applied in the No. 1 Blast Furnace of Kakogawa
Works and its practicability was confirmed when its estimation corresponded to those taken by the dissection studies.

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Observations were made of the raceway of Kimitsu No. 3 BF for the purpose of clarifying the coke behaviour in the raceway and for further understanding of the conditions at the periphery of the raceway. Observations were made by means of an endoscope inserted in a tuyere probe and a 16mm cinecamera capable of photographing at a speed of 3000 frames per second. The results of observation revealed that the quantity of coke flowing into the raceway increases as the blast volume becomes larger. More specifically, the quantity of coke reaches as much as 272 pieces at a blast volume of 6200Nm3/min. It was also found that the higher the blast velocity and the smaller the coke particle size, the greater the flying speed of coke.
From the study based on the observation results, it was found that the change in particle diameter due to breakage of coke in the furnace is slight, coke circulates in the tuyere zone, there exist two kinds of coke; bright and dark, there is a strong possibility of dark coke having been supplied from the root of the cohesive zone to the raceway, and further, it is most probable that an oxidizing atmosphere remains outside the coke circulating zone.

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