Hot Blast Research Articles

The 1968 andesitic lateral blast eruption at Arenal volcano, Costa Rica

The magmatic andesitic eruption of Arenal volcano on July 29–31, 1968, after centuries of dormancy, produced three new fissural craters (A, B and C) on its western flank and a multilayered pyroclastic deposit emplaced by complex transport mechanisms. The explosions were initially triggered by a volatile oversaturated (4–7 wt.% H 2O) magma. Several lines of evidences suggest a small blast surge, where a wood-rich pyroclastic deposit was emplaced as a ground layer, followed by several units of coarse-grained (Md Φ between − 0.65 and − 5.40) tephra deposits (LU: lapilli units, DAU: double ash units). LU-1, -2, -3, DAU-1 and -2 consist of unconsolidated and well- to poorly sorted vesiculated bombs and lapilli of andesite, some blocks, ash and shredded wood. The individual units are possibly correlated with the major explosions of July 29. The thickness of the deposits decreases with the distance from the volcano from 5.6 m to a few centimeters. On average, 90% of the components are juvenile (10% dense andesite and 90% vesicular). These coarse-grained beds were deposited in rapid succession by a complex transport process, involving normal fallout, strong ballistic trajectories with a lateral hot (∼ 400 °C) blast surge (LU, equivalent to A 1). Ballistic and coarse tephra sprayed in a narrow (85°) area within about 5.5 km from the lowest crater, and a high (ca. 10 km) eruption column dispersed airfall fine lapilli-ash > 100 km from the volcano. Ash-cloud forming explosions, producing thin pyroclastic surge and muddy phreatomagmatic fallout deposits (FLAU, equivalent to A 2 and A 3), closed the blast surge sequence. The successive explosions on July 30–31 mainly produced block and ash flows, and widely dispersed ash fall. The total volume of pyroclastic material is calculated as 25.8 ± 5.5 × 10 6 m 3 (9.4 ± 2.0 × 10 6 m 3 DRE). A model is proposed to explain the peculiarities of the formation, transportation and emplacement of the blast deposits. The intrusion of the presumed andesitic cryptodome possibly happened through an active thrust fault, favoring not only the formation of the lowest crater A, but also the low-angle explosive events. Prior to the eruption, several minerals were settling to the bottom of the magma chamber as is suggested by the increase of incompatible elements towards the bottom of the stratigraphic section. The major elements indicate that some crystal redistribution occurred and the maximum concentration of Al 2O 3, and Eu, and Sr support plagioclase enrichment in early phases of the eruption (top of LU-1 and DAU-1). From the about 20 recognized prehistoric and historic blast deposits in the world, approximately half were produced by sector collapse of the volcano and the other half by sudden decompression of cryptodomes or lava-dome collapses. The recent blasts (1888–1990s) elsewhere have an apparent recurrence of one event/decade, compared to just a dozen described for the previous 50 ka. Therefore, the adequate recognizers of the blast facies in the cone-building lithofacies, especially for small stratocones as described here, can help in understanding other historic and prehistoric cases, and their related hazards.

Governing Processes of Gas and Oil Injection into the Blast Furnace

To enhance the blast furnace process, the practice of injecting reducing agents into the blast furnace is used. In a metallurgical plant of the voestalpine Stahl, so far the injection of oil is practiced. The availability of gases like coke oven gas (COG) makes it possible to substitute reducing agents like heavy oil. The injection of gas and oil, respectively, shows different reaction characteristics and therefore different reducing conditions are obtained.In this work, theoretical considerations are made about the different conversion characteristics of oil and gas. The calculations, done by using computational fluid dynamics (CFD), provide a detailed description of the oil and gas flow injected in the hot blast. For gas injection, the mixing of gas and blast and their conversion are considered in tuyere and raceway. For oil injection, additionally the evaporation of the oil droplets takes place.The injection of gas with one lance shows an inhomogeneous distribution in temperature and velocity due to the high injection velocity compared to oil injection. For the injection of oil, evaporation of the oil droplets takes place and the gas formed reacts with the hot blast. There, the distribution of temperature, velocity and concentrations is more homogeneous than for gas injection. A variation of the oil droplet size injected shows for larger droplets (400 µm and more) an incomplete evaporation and distributions similar as for the gas injection.

Analysis on Material and Energy Balances of Ironmaking Systems on Blast Furnace Operations with Metallic Charging, Top Gas Recycling and Natural Gas Injection

The iron and steelmaking industry has been receiving social pressure to reduce energy consumption and environmental load as recent increase in the social awareness on environmental and resource problems. The ironmaking system consumes more than a half of overall energy input to the steelwork and its improvement is expected as a countermeasure for such problems. Numerous attempts through improving the blast furnace operation have been made. This paper analyzes material and energy balances of ironmaking system that consists of hot stove, coke oven, CDQ, sintering and blast furnace. The operation statuses of the blast furnace with natural gas injection, metallic charging and top gas recycling that have been obtained by the kinetic-based numerical simulations are applied to this analysis. The results suggested that the metallic charging to blast furnace decreases both energy input and CO2 emission. The natural gas injection operation decreases the CO2 emission from the iron making system while the decrease in the energy input is small. The top gas recycling operation increases the CO2 emission due to the scrubbed CO2 from the recycled top gas.

Hot electrons blast wave generated by femtosecond laser pulses on thin Au(1 1 1) crystal, monitored by subpicosecond X-ray diffraction

Femtosecond time-resolved X-ray diffraction is used to probe reversible lattice changes of a 150-nm Au(1 1 1) crystal on mica heated with 100-femtosecond laser pulses with fluence below the damage and melting threshold. The lattice strain generated throughout the crystal is larger than estimated from the inhomogeneous lattice temperature distribution and acoustic wave produced by nonequilibrium heating. The broadening and shift of the rocking curve observed across the depth of the crystal support the presence of an additional ‘blast’ wave arising from hot electron gas temperature gradient, which is observed experimentally for the first time.

Long term high performance operation at Kwangyang blast furnaces

Kwangyang has been operating five large size blast furnaces and K-1 BF was relined in March 2002 after finishing 15 years of operation successfully. To secure enough cast pig iron as one of countermeasures to a low HMR at the steelmaking process during the relining period, four other blast furnaces came to increase their productivity in advance, before the start of the K-1 BF long stoppage. Particularly, during the ultra-high productivity operation period from March to June, K-3 BF marked a new POSCO productivity record and a new silicon record simultaneously on May in spite of unstable sinter consumption due to the width extension of No. 1 & No. 3 sintering strands and 13 years furnace life. It was 2.76 t/daym3/IV in productivity and 0.15% in silicon level in pig iron. These remarkable records were based on some advanced Kwangyang BF know-how and recent developments like higher facilities reliability, optimum allotment of hot blast and oxygen, high sophisticated burden distribution control and special screening equipment of raw materials.

Computer Simulation of Heat Transfer in Regenerative Chambers of Self-preheating Hot Blast Stoves

Heat transfer in chambers of self-preheating hot blast stoves in Anshan Iron and Steel Co., China, has been numerically simulated with a three-dimensional unsteady heat conduction equation and an energy conservation equation for fluid flowing through channels in the chambers. The blast temperature and air preheating temperature in the numerical simulation study are in good agreement with those in measurement. The numerical results show that hot blast temperature can reach 1 200°C by using a self-preheating process and low calorific blast furnace gas under the studied operational conditions. Amount of heat exchange between the checkerwork and the fluids and usable heat increase in the middle and low parts of the chambers of the hot blast stoves due to the application of the self-preheating process.

OWEN GLENDOWER'S CREST AND THE SCOTTISH CAMPAIGN OF 1384-1385

A striking glimpse of Owen Glendower occurs in the work of Ernest Jacob, who refers to the young warrior 'on the Scottish expedition of 1385, during the course of which Iolo Goch describes him while at Berwick wearing in his helmet the scarlet feather of a flamingo'.1 Of Glendower's service at Berwick we now know more. As early as 1 March 1384 'howeyn Glyndourde' is listed amongst men-at-arms of Sir Degory or Gregory Sais (mentioned in Iolo's poem).2 But the detail of his crest remains intriguing. One wonders why Glendower wore this feather and how it reached him from southern Europe or beyond (where flamingos live). The puzzlement increases on consulting OED, which shows flamingo unattested in English before 1565. The poetic source for this (by Owen's contemporary Iolo Goch) clearly needs another look.Jacob took the detail from Sir John Lloyd, who (paraphrasing Iolo's poem) describes 'the valour of the young warrior at Berwick, where he wore in his helmet the scarlet feather of a flamingo, unhorsed his opponent, fought with a mere fragment of his broken lance and drove the Scots like wild goats before him. The grass and the corn withered after the hot blast of his devastating onset.'3Lloyd is careful to give the line of poetry ('Adain rudd o edn yr Aifft') which he translates 'scarlet feather of a flamingo'. But the literal meaning here is 'Red wing of the bird of Egypt', or 'Red feather of the bird of Egypt' (like Latin penna, Welsh adain means both 'wing' and 'feather'). It is clear that Owen's crest did not represent the entire bird. Early editions of the poem make no reference to flamingos. Editors leave the line without comment.4 'Flamingo' must be Lloyd's own interpretation, where he was followed without hesitation by Gwyn A. Williams (famous for his Marxist interpretations of Welsh history).5 Yet others are more cautious. The great University of Wales dictionary translates 'edn yr Aifft' as '?flamingo'. Professor Johnston of Swansea, in his exemplary edition of Iolo's poems, merely notes this as a suggestion.6Flamingos live in most subtropical and tropical lands, including Spain, southern France, and Egypt. A drawing of a flamingo in an uncial manuscript (now in Barcelona) of St Gregory's Homiliae in Evangelia, which contains corrections by an eighth-century English scribe, shows these birds were known to the Anglo-Saxons.7Yet direct references to them in medieval English sources are rare. If, further, we seek 'Egyptian bird' in English dictionaries we find nothing. What we do find is 'Arabian bird'. This points to a solution. The Arabian bird was the phoenix, described in classical and medieval tradition as living in the Arabian Desert and sacrificing itself every 500 years in the temple at Heliopolis, near Cairo. The Arabian Desert is in Egypt, between the Nile and the Red Sea; Cairo is Egypt's capital; the 'bird of Egypt' is hence, surely, the phoenix. At Berwick in 1384-5 Owen Glendower would thus have worn on his helmet not a flamingo's feather, but the image of a phoenix. If critics ask why Iolo alludes here to Egypt and not Arabia, we may note that 'edn yr Aifft' rhymes usefully with 'nen iawnraifft' ('fine-plumed lord') in the previous line (it also alliterates, in the way characteristic of Welsh bardic verse, with the d, n, and r earlier in the line). This perhaps explains why 'edn yr AifFt' occurs in this one poem by Iolo and nowhere else. We may also note that (as a referee of this paper points out) the interpretation 'phoenix' suits Iolo's images of heat and fire at this point of his poem.If Iolo Goch's 'edn yr Aifft' ('bird of Egypt') was a phoenix, we can correct a minute error in the Oxford history of England. But we shall also have material from early Britain more significant than might at first appear. The history of the phoenix legend is more than an essay in antiquarianism, since the question as to why Glendower bore this emblem may tell us something of both his mentality and that of his age. …

Choice of technological regimes of a blast furnace operation with injection of hot reducing gases

Injection rate of fossil fuels is limited because of drop in the flame temperature in the raceway and problems in the deadman region and the cohesive zone. The next step for obtaining a considerable coke saving, a better operation in the deadman as an well as increase in blast furnace productivity and minimizing the environmental impact due to a decrease in carbon dioxide emmision would be injection by tuyeres of hot reducing gases (HRG) which are produced by low grade coal gasification or top gas regenerating. Use of HRG in combination with high pulverized coal inyection PCI rate and oxigen enrichment in the blast could allow to keep and to increase the competitiveness of the blast furnace process. Calculations using a mathematical model show that the HRG injection in combination with pulverized coal (PC) and enriching blast with oxigen can provide an increase in PC rate up to 300-400 kg/tHM and a rise in the furnace productivity by 40-50 %. Blast furnace operation with full oxigen blast (100 % of process oxigen with the exception for the hot blast) is possible when HRG is injected.

Heat (mass) transfer in serpentine flow passage with rectangular cross-section

Combustion efficiencies of pulverized coal in blowpipes and tuyeres under various operational conditions are numerically predicted to recognize the performance of pulverized coal injection in a blast furnace. A variety of parameters including the injection pattern of the pulverized coal, oxygen content in the hot blast, inlet temperature of the hot blast and mass flow rate of coal carrier gas are taken into consideration. The effect of installing a ceramic sleeve around the tuyere on pulverized coal combustion is also evaluated. The predictions indicate that pulverized coal combustion is highly related to the injection pattern, hot blast temperature, mass flow rate of the carrier gas and installation of the ceramic sleeve, whereas it is insensitive to the oxygen concentration. The present study is conducted based on the practical operational conditions of the blast furnace at the China Steel Corporation. Consequently, the obtained results have provided a useful insight into the operation of pulverized coal injection, and they enable us to further improve the blast furnace performance in the future.

Relining of the Sidmar blast furnace B in 2001

A certain number of changes have been made on the occasion of the relining of blast furnace B at Ghent. They oncern the design of the furnace and the improvement of its cooling system, the repair of the hot blast stoves, the replacement of part of the control equipment and the installation of new measuring devices. Environmental controls and improved working conditions were also at the origin of some changes. The result of this operation is a fine new furnace equipped with the latest measuring and control systems.

Model-based control of a thermal regenerator. Part 2: control and estimation

This paper describes the model-based control and estimation techniques implemented on the hot blast stoves for the number 7 blast furnace at the Ispat Inland Steel facility in East Chicago, IN. The process model is a detailed heat transfer model of this thermal regenerator system used as part of a predictive control scheme to determine the minimum amount of fuel necessary to achieve the energy requirements. Batch nonlinear least squares estimation is used to update the predicted temperature profile and heat transfer coefficients. These estimated parameters are then used by the model-based controller to determine the minimum fuel required for the subsequent regenerative cycle.

Model-based control of a thermal regenerator. Part 1: dynamic model

This paper describes the dynamic process model and solution technique developed for the hot blast stoves used with the No. 7 blast furnace at the Ispat Inland Steel facility in East Chicago, IN, USA. A detailed, distributed parameter, heat transfer model of this thermal regenerator system is developed and verified using plant data. The model is capable of predicting accurately the temperature and energy content of the stoves during the thermal regenerative cycles. It was developed for a predictive controller that determines the minimum amount of fuel necessary to achieve the energy requirements from the system.

98/04111 Smelting process with direct reduction of iron ore for manufacture of cast iron melt in two-chamber vertical furnace

A simple model is presented to assess thermal performance of blast furnace (BF) for efficient utilization of energy with an integrated view to improving the productivity of the plant. The model is developed using the mass, energy and availability balance equations and is applied to an existing Iron and Steel industry in India. A comparison of the actual operation of the BF is made with that of the model prediction. The model provides a reasonable agreement with the real time (on-site) data of the BF operation. The predicted values of BF coke rate and blast rate are 8.6% and 5.11% higher than that of the actual values, respectively. The First and Second law efficiencies of the BF operating system were found to be 77.3% and 39.13%, respectively. Irreversibility of the actual operation of BF was found to be 18.9%, which included the irreversibility due to the transformation of chemical energy and promotion of reduction reactions. The main cause of the irreversibility in the process was the conversion of chemical energy of the fuel (coke) to thermal energy. The effect of the changing operating parameters on the plant productivity is also investigated. This study suggests that the plant productivity can be improved by increasing the hot air blast temperature, reducing hot metal silicon level, reducing coke ash level and increasing sinter volume in the charge.

98/01504 Numerical modelling of pulverized coal combustion in an oxygen-coal combustor for blast furnace: Gue, Y. et al. Ranshao Kexue Yu Jishu, 1997, 3, (3), 297–302. (in Chinese)

The aim of this paper is, first of all, to examine a coupled arrangement in which turbine waste gas is used as the oxygen carrier for combustion of the fuel gas in hot blast stoves and preheaters of a blast furnace; in their turn, the blast furnace gas and the turbine waste gas are preheated by the combustion of blast furnace gas, in order to achieve the necessary combustion temperatures. The arrangement makes provision also for utilization of external thermal energy. The coupled process is compared with a hot blast stove system and a gas turbine plant without waste thermal energy recovery, which operate separately. The paper uses the concept of usable exergy, a previously defined parameter, to compare the two configurations and reverses some of the results obtained by a first-law analysis.

A second-law analysis of the “hot blast stove/gas turbine” combination by applying the parameter “usable exergy”

The aim of this paper is, first of all, to examine a coupled arrangement in which turbine waste gas is used as the oxygen carrier for combustion of the fuel gas in hot blast stoves and preheaters of a blast furnace; in their turn, the blast furnace gas and the turbine waste gas are preheated by the combustion of blast furnace gas, in order to achieve the necessary combustion temperatures. The arrangement makes provision also for utilization of external thermal energy. The coupled process is compared with a hot blast stove system and a gas turbine plant without waste thermal energy recovery, which operate separately. The paper uses the concept of usable exergy, a previously defined parameter, to compare the two configurations and reverses some of the results obtained by a first-law analysis.

Development of mathematical model and optimal control system of internal temperatures of hot-blast stove process in staggered parallel operation

A mathematical model and an optimal control system of hot-blast stove process are described. A precise mathematical simulation model of the hot-blast stove was developed and the accuracy of the model has been confirmed. An optimal control system of the thermal conditions of the hot-blast stoves in staggered parallel operation was also developed. By the use of the multivariable optimal regulator and the feedforward compensations for the change of the aimed blast temperature and blast volume, the system is able to control the hot blast temperature and the brick temperature efficiently.The system has been applied to Kashima works. The variations of the blast temperature and the silica brick temperature have been decreased. The ultimate low heat level operations have been realized and the thermal efficiency furthermore has been raised by about 1%.

Under the Stars: Essays on Labor Relations in Arts and Entertainment ed. by Lois S. Gray, Ronald L. Seeber

986 Book Reviews TECHNOLOGY AND CULTURE the wealthy slaveholders and their allies who originally conceived Alabama’s leading industrial city in the 1850s continued even after the Civil War to prefer low-paid and poorly motivated black labor to a free labor system. Despite all the problems alienated black workers presented, including absenteeism and lackadaisical performance on the job, southern managers considered them more tractable, and above all less strike-prone, than free white workers, especially when the latter came from the North. Had Birmingham’s postwar entre­ preneurs been able to use both skilled and unskilled black workers, they would gladly have done so. Experienced black puddlers, molders , and rolling mill operatives, however, had not been needed in the prewar period, when slaves ran the charcoal-fired blast furnaces to which Alabama’s early iron industry was almost exclusively lim­ ited. Not until the late 1850s had the state even begun to experience the impact of technological changes, such as the switch from char­ coal to mineral coal and coke, the hot blast, and the introduction of puddling, that had affected northern ironmaking at an earlier date. As a result, no black workers familiar with such technologies were available in the postwar period. The fact that Birmingham’s industrialists would have preferred to employ skilled African-Americans, had that been possible, is the real reason why skilled white workers suspected that local boosters would ultimately back away from the promises they had made in the 1870s—as indeed they did. McKiven’s book would therefore benefit from a somewhat sharper focus. But it is excellent even as it stands, and its fundamental thesis is sound. W. David Lewis Dr. Lewis is Distinguished University Professor at Auburn University. His most recent book, Sloss Furnaces and the Rise of the Birmingham, District: An Industrial Epic (Tuscaloosa: University ofAlabama Press, 1994), deals with the distinctively southern nuances ofBirmingham’s industrial evolution and its grounding in antebellum plan­ tation slavery. Under the Stars: Essays on Labor Relations in Arts and Entertainment. Ed­ ited by Lois S. Gray and Ronald L. Seeber. Ithaca, N.Y.: Cornell University Press, 1996. Pp. xv+207; notes, bibliography, index. $38.00 (cloth); $16.95 (paper). The mass media in the United States have undergone rapid changes in recentyears. A number ofscholarlyworks have examined technical changes, but all from the corporate point of view. Under the Stars: Essays on Labor Relations in Arts and Entertainment takes up the effects for workers. The contributors to this six-part anthology systematically examine the challenges posed for labor and their unions and significantly add to a literature that can be described as thin at best. TECHNOLOGY AND CULTURE Book Reviews 987 The “arts and entertainment” in the book’s subtitle mean live performing arts, musical recordings, movies, television, and radio. Employing about one million persons, this set of industries is still heavily unionized, although its union structure has been changing in recent years. “Above the line” (for example, performers’ and di­ rectors’) unions have been growing while membership in “below the line” (for example, technicians’) unions has been shrinking. This transformation of labor relations, according to Under the Stars, reflects both workers’ attempts to deal with technological displace­ ment and corporations’ desires to lower costs. Thus, not unexpect­ edly, the arts and entertainment industries have recently been racked with far more labor strife than almost any other sector of the U.S. economy. The editors of this volume are both professors of industrial rela­ tions at Cornell University. Their six contributors are also scholars, save a single outsider, Les Brown, a trade journalist and longtime industry critic. The catalyst for the book seems to have been the wellpublicized strike by the Writers Guild against TV and movie produc­ ers in 1988. While Under the Stars is overtly about labor relations in only one set of industries, its six contributors suggest over and over again that understanding the arts and entertainment industry expe­ riences offers useful insights into labor relations in other rapidly evolving service industries. Since, importantly for these applied la­ bor economists, the arts and entertainment industries are still highly unionized, there exists much data in the public record about labormanagement...

The application of simultaneous TG-DTA to the determination of the fate of injected coal in a pilot-scale blast furnace simulation rig

Abstract Coal injection is an important technique for increasing the efficiency of blast furnaces, although the required optimum properties of injectant coals have not yet been fully identified. The Single-Tuyere Coal Injection Investigation Rig at the British Steel Teesside Technology Centre is a pilot-scale blast furnace simulation operated without iron ore so that the combustion (and gasification) of the injected coal can be studied in isolation. About two tonnes of coke are used to create a realistic simulation of the blast furnace raceway. Coal is injected into the hot air blast, and changes in the raceway conditions observed. Carryover fines from the waste gas are collected during the trial, and at the end of the trial, the coke bed is cooled, and coke samples dug out. These solid materials are analysed for traces of the injected coal, in order to assess the efficiency with which the injected coal is combusted. The determination of the proportion of injected coal char present in these samples was originally carried out by point-counting particles using optical microscopy. This technique is labour-intensive and subjective. An alternative technique has therefore been devised, employing simultaneous thermogravimetry-differential thermal analysis (TG-DTA). The technique gives good agreement with optical microscopy, whilst being considerably faster and less subjective.

Energy recovery from molten slag and exploitation of the recovered energy

A considerable amount of exergy is contained in the liquid slag tapped from blast furnaces. Relatively new processes for heat recovery from these slags are described in this paper. The slags yield a useful, dry granulated product with a glass content that depends on the process employed. Exergy in liquid and solid slags can be exploited to produce both steam and heated air. The steam may be used to generate electricity, while hot air is employed to preheat the combustion air for the blast furnace. Using a second law analysis, it is proved that the second alternative is preferred for blast-furnace slag when heated air is used for combustion in the hot blast stoves of the blast furnace.

Advanced blast furnace operation with hot blast flow control valves

Hot blast flow control valves which can control the flow rate of hot blast at each tuyere and their control system have been developed and applied to Keihin No. 1 BF. These technologies contribute to stable and rational operation compared with conventional ones. This presentation describes the technology of hot blast flow control valves and its implications on the control of heat load at the lower part, the removal of scab, and the control of tapping conditions.