CONSTRUCTIVE DESIGN AND FEATURES OF THE PROCESSES IN THE ROASTING SHAFT FURNACES BY USING GASEOUS FUEL

The article analyzes shaft furnaces for lime production. According to the method of firing, shaft furnaces are of bulk type, semi-gas type, gaseous and liquid fuels. The disadvantages of the operation of the main modern kilns during lime burning have been established. The main aggregates for high-tonnage lime production are mine lime kilns, in which blast furnace coke or anthracite, or high-quality coals are used as fuel. Generally, lean fuels are used in industries where, together with the technological cycle, carbon dioxide is used, which are contained in flue gases with a concentration of 36−40%mass. The data on the operation of six furnaces on the territory of Ukraine at the enterprises showed that gas shaft furnaces of cylindrical and slotted type with a straight-lining profile were widely used. The parameters of such furnaces are productivity from 100 to 250 tons per day, shaft diameter from 3.2 to 5.4 m, and height 6−8 furnace diameters. Most often, they use heating systems with central and two rows of peripheral injection burners without protrusion. The most critical part of all furnaces is the distribution of gas flow rates over the cross-section of the furnace shaft and the depth of radial penetration of the gas flow into the material layer. Calculations of τ1 and τП were carried out in the following way: for τ1, the temperature range of the medium was chosen from 1300 to 250−300 °С, τox − the temperature range for the material was chosen from 1000 to 100 °С and the density of the product was taken into account at the degree of decomposition of limestone 98% (=1700 kg/m3). In the preheating zone, the limiting stage is the supply of heat from the gas to the lump material, and at the same time can be taken equal to ⁓400−450 kJ/(m2∙h∙К) and τ1 is estimated as 0.8÷1 hour. The total residence time of the material in the furnace (in the heating zone and in the firing zone) is estimated at 1.4÷1.5 hours. The average speed of material movement in the cylindrical part of the furnace is estimated as 0.004 m/s, which makes it possible to consider the filtering layer conditionally stationary. These characteristics affect the quality of limestone and the uniformity of limestone firing that was the basis for the design of roasting shaft kilns using gaseous fuel.

Raw material base for coking of the Coke Production of PJSC "ARCELORMITTAL KRYVYI RIH" in the period from 2017 to 2021.

RAW MATERIAL BASE FOR COKING OF THE COKING PRODUCTION OF PJSC "ARCELORMITTAL KRYVYI RIH" IN THE PERIOD FROM 2017 TO 2021 © N.V. Mukina (Coke-chemical production of PJSC "ArcelorMittal Kryvyi Rih", 50095, Dnepropetrovsk region, Kryvyi Rih, Krivorozhstal st., 1, Ukraine), D.V. Miroshnichenko, Doctor of Technical Sciences (NTU "Kharkiv Polytechnic Institute", 61002, Kharkiv, st. Kirpicheva, 2, Ukraine) The article presents the data on coal components that were used in the charge for coking coke oven batteries №№1-4 (bulk coal charge) and №№ 5, 6 (tamped coal charge) of the coke-chemical production of PJSC "ArcelorMittal Kryvyi Rih" in the period from 2017 to 2021, as well as averaged information on some quality indicators of the produced coke. In general, the coal raw material base of the enterprise for the last five years has been of a stable inter-basin nature with a predominance of coals from the USA, Kazakhstan, and the Russian Federation. It is shown that, as the tamping technology suggests, moisture content, bulk density and content of classes less than 0.16 and less than 3.0 mm in coal charges supplied to the coal waste plant. №№ 5, 6 are significantly higher than the values of similar indicators of coal charges supplied to the numbers 1-4. Along with this, due to the use of coals of a certain quality, ash content, total sulfur content and the thickness of the plastic layer in coal charges supplied to the coal bunker №№ 1-4, is slightly higher than similar indicators of coal charges supplied to the boiler №№ 5, 6. In total, during 2017-2021, the composition and quality indicators of the coal charge for the production of coke at the boiler plant №№ 1-4 practically did not change, while in the coal charge for the production of coke on coke oven batteries №№ 5, 6 there is a decrease in the share of highly volatile coals with a simultaneous increase in the content of medium-volatile and low-volatile components. The given values of the quality indicators of the obtained blast-furnace coke indicate that the use of tamping technology makes it possible to obtain blast-furnace coke of a higher quality than by using a traditional technology. In particular, the coke obtained at the oven batteries №№ 5, 6 are characterized by lower values of ash content, total sulfur content and abrasion (M10) with higher values of mechanical strength in terms of M25 and post-reaction strength (CSR). Keywords: coal, inter-basin raw material base, coking, charge tamping, coke quality. Corresponding author N.V. Mukina, е-mail: [email protected]

Development of rational technological parameters for heating of a coke battery with a stamped charging of coals.

DEVELOPMENT OF RATIONAL TECHNOLOGICAL PARAMETERS FOR HEATING OF A COKE BATTERY WITH A STAMPED CHARGING OF COALS © V.I. Goncharov, I.I. Sikan, Ya.I. Dyachuk, N.V. Mukina (Coke production of PJSC «ArcelorMittal Kryvyi Rih», 50095, Dnipropetrovsk region, Kryvyi Rih, Kryvorizhstal str., 1, Ukraine), I.V. Shulga, PhD in technical sciences (State Enterprise "Ukrainian State Research Coal Chemical Institute (UHIN)", 61023, Kharkov, Vesnina st., 7, Ukraine) The article is devoted to the introduction at the PJSC «ArcelorMittal Kryvyi Rih» coke plant of a promising technology for compaction of a coal charge, which allows obtaining blast furnace coke of high mechanical and "hot" strength from charges characterized by an increased content of lean components of various stages of metamorphism. Under the present circumstances, this is of great importance for increasing the economic indicators of the production of blast furnace coke and the operation of blast furnaces. The start-up of coke oven battery No. 6, designed for the application of this technology, necessitated the determination of rational technological parameters of heating: the temperature level in the control verticals and the location of the burners for supplying coke oven gas in the vertical along the heating wall. The article presents the calculations, the results of which confirm the expediency of rationalizing the actual starting (design) distribution of burners on coke oven battery No. 6. First of all, attention is drawn to the insufficient diameters of the holes in the burners for the extreme and pre-extreme verticals. This, according to the authors, caused underheating of the head zones and resin spills, which were observed during start-up operations on the battery. The replacement of burners at the edges of the walls by large diameters, carried out by the personnel of the coke shop of the coke plant PJSC “ArcelorMittal Kryvyi Rih” and LLC “Koksokhimstanciya”, combined with the full opening of the recirculation windows in these zones, improved the heating of the charge and significantly reduced the intensity of spills. The experience gained was taken into account when locating the control devices at coke oven battery No. 5, which was put into operation later. The article also formulates recommendations for adjusting the temperature regime of coking, depending on the grade and component composition, as well as the technological properties of coal charges. Keywords: coke oven battery, stumping of coal charge, temperature in control verticals, location of burners along the length of the heating wall. Corresponding author Ya.I. Dyachuk, е-mail: [email protected]

DISTRIBUTION OF CALORIFIC VALUE BY COKE SIZE CLASS

As is known, the specificity of the layered coking process causes the development of fracturing, which determines the formation of the granulometric composition of the coke. The article presents and analyzes data on the physicochemical properties of coke of various size classes. The expediency of studying the values of the calorific value for different classes of the size of blast furnace coke has been substantiated. For this purpose, ramp coke was taken from batteries that were significantly different in size. In particular, coke oven battery I has almost twice the useful volume of coking chambers and, accordingly, the design capacity than coke oven battery II. In addition, the height of the chambers of coke oven battery I is 7000 mm, and that of coke oven battery II is 4300 mm. The above circumstances must be taken into account when evaluating the heat of combustion of various size classes of blast furnace coke. The composition of the investigated charge consisted of classic grades of coals, which are characterized by their inherent set of quality indicators. The charge for battery I was characterized by a lower burst pressure. It is shown that the value of the highest calorific value of wet quenching blast furnace coke undergoes significant changes depending on the size. Size classes less than 25 mm are characterized by maximum values of the gross calorific value, which reach 33.0 MJ/kg and more. The level of "readiness" of coke, expressed by the value of the yield of volatile substances and the actual density of the coke, significantly affects the value of the highest calorific value. Less "finished" blast furnace coke is characterized by higher values of the gross calorific value for all particle sizes. It is concluded that the value of the highest calorific value of blast furnace coke can serve as a criterion (in addition to those already available) for assessing the degree of "readiness" of blast furnace coke. Keywords: coal, coke, coke size classes, degree of readiness, heat of combustion. Corresponding author Miroshnichenko I.V., e-mail: [email protected]

Estimation of the suitability of the coal charge for producing blast-furnace coke of the given quality using the tamping technology.

ESTIMATION OF THE SUITABILITY OF THE COAL CHARGE FOR PRODUCING BLAST-FURNACE COKE OF THE GIVEN QUALITY USING THE TAMPING TECHNOLOGY © E.T. Kovalev, Doctor of Technical Sciences, A.L. Borisenko, PhD in technical sciences, I.V. Shulga, PhD in technical sciences, N.A. Desna, PhD in technical sciences (State Enterprise "Ukrainian State Research Coal Chemical Institute (UKHIN)", 61023, Kharkіv, Vesnina st., 7, Ukraine) The article shows the relevance of technologies that implement the possibility of expanding the raw material base of coking with the help of special methods for preparing the charge, among which tamping is currently taking the leading place in the world and in Ukraine. It is shown that when considering the issue of introducing the technology of coking the tamped charge, a previous link of the available raw material base with the planning of the main structural parameters of the coke oven is necessary. It will provide on the basis of global low-caking coals the production of coal coke with characteristics that are as close as possible to the requirements of the world's leading iron producers. On a general example, the developed complex and the procedure for performing the corresponding assessment are presented, the following includes: – a comprehensive analysis of the properties of bituminous coals intended to be used as components of the raw material base (technical, petrographic and other analysis); – drawing up on their basis model charges, taking into account the restrictions on ash content (≤ 9-10 %), burst pressure (≤ 7 kPa), thickness of the plastic layer (≤ 15 mm.); – laboratory determination of indicators of tamping capacity of model charges – density of rammed briquettes (γ, g/cm3 ) and their shear strength (σss, kPa); – laboratory coking of tamped model mixtures with subsequent determination and comparison of the properties of the obtained cokes; – based on the data on the tamping capacity of the model charges, which showed optimal results in terms of the formation of coke of the best quality and the parameters of the known (mastered) designs of furnaces and charge, the calculated determination of the value of the maximum height of the coking chamber for the studied composition and properties of the charge. Keywords: coking, tamping of coal charge, preliminary assessment, analysis of coals, model charge, tamping indicators, coking, coke properties, coking chamber height. Corresponding author E.T. Kovalev, e-mail: [email protected]

Use of Alternative Raw Materials in Coke-Making: New Insights in the Use of Lignites for Blast Furnace Coke Production

This paper presents the results of studies on the possibility of using lignite to produce blast furnace coke. The aim of the investigation was to evaluate the influence of lignite addition (direct addition or incorporated into briquettes) on the textural, structural and quality parameters (NSC-CRI and CSR) of blast furnace coke. It was found that the introduction of lignite in briquettes (4.5% addition) allows coke to be produced that is characterized by equally high NSC parameters as for coke obtained without lignite addition for standard top-charged operation.

Effect of the natural gas hydrogen on variation of the heat and reducing processes along the blast furnace radius

The expenses for the blast furnace coke are one of most significant part of the hot metal cost. To save the coke, various technologies are used, capable to replace the coke by cheaper additional fuel (AF), in particular by natural gas (NG). The injection of considerable volumes of NG results in an increase of hydrogen share in the blast furnace gases and in a significant variation in the blast furnace technology. Study of peculiarities of such variations is necessary to use the NG more effectively. Based on the mathematical model of the blast furnace process, estimation of the effect of natural gas hydrogen on changes in the heat and reducing processes along the blast furnace radius was accomplished. A formula was elaborated, confirmed by practice, for calculating the degree of hydrogen usage ηН2 along the radius of the furnace. It was determined, that the reducing action of hydrogen along the furnace radius takes place unevenly –decreasing from the periphery to the axial zone of the blast furnace. To estimate the quantitative relations of the reducing action of hydrogen, parameters of the PAO “MMK” and PAO “ArcelorMittal Krivoy Rog” blast furnaces for a long period of operation were analyzed. It was determined, that in the axial and intermediate zones of a blast furnace, values of criterion RН2, designating the oxygen share in the burden removed by hydrogen, are in the range of 0.11–0.16 and weakly depend on the NG consumption. In the peripheral zone near the walls, the value of R Н 2 sharply increases to 0.22–0.27. In this zone of the blast furnace the quantity the burden oxygen, removed by hydrogen, accounts for 80–85%. Therefore, hydrogen accomplished the heat and reducing processes mainly in the peripheral zone of the furnace. At the NG consumption increase, the ore load should be increased for the peripheral zone, near the walls individually accounting hydrogen action along the furnace radius. This will make possible to increase the degree of hydrogen usage and decrease the coke consumption.

Enhancement of the productivity of non-recovery stamp charge coke oven plant at JSPL Raigarh

In recent past, Jindal Steel & Power Limited, Raigarh unit, has increased the hot metal production capacity by the renovation of the existing blast furnaces. Therefore, the blast furnace coke demand has increased. This excess demand for metallurgical coke production from the existing non-recovery stamp charge coke oven plant was a very tough challenge, because the coke oven plant was already running at rated production capacity. Therefore, to fulfill the requirement of excess coke and to deliver more value to the customers, several initiatives have been taken by the Coke Oven and Technical Services Department within the existing setup. Few approaches had been adopted to increase the productivity of coke by ∼20% without deteriorating the resultant coke quality. This paper describes in details the steps taken to enhance the productivity of non-recovery stamp charge coke oven plant.