Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B5/00—Making pig-iron in the blast furnace
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B5/00—Making pig-iron in the blast furnace
  • C21B5/001—Injecting additional fuel or reducing agents
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B11/00—Making pig-iron other than in blast furnaces
  • C21B11/02—Making pig-iron other than in blast furnaces in low shaft furnaces or shaft furnaces
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B1/00—Shaft or like vertical or substantially vertical furnaces
  • F27B1/10—Details, accessories or equipment specially adapted for furnaces of these types
  • F27B1/16—Arrangements of tuyeres
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B1/00—Shaft or like vertical or substantially vertical furnaces
  • F27B1/10—Details, accessories or equipment specially adapted for furnaces of these types
  • F27B1/26—Arrangements of controlling devices
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D19/00—Arrangements of controlling devices

Definitions

• the invention relates to a method for operating a shaft furnace, in which an upper region of the shaft furnace is charged with raw materials which sink under the influence of gravity in the furnace, wherein a part of the raw materials is melted and / or reduced under the influence of the atmosphere prevailing inside the shaft furnace , and in a lower portion of the shaft furnace, a treatment gas is introduced which at least partially affects the atmosphere prevailing inside the shaft furnace and a shaft furnace suitable for the application of this method, such as blast furnace, cupola furnace or incinerator.
• Such a method, or the shaft furnace is basically known.
• the shaft furnace can work on the countercurrent principle.
• Raw materials such as Möller and coke are charged at the top of the shaft furnace of the gout and sink down in the shaft furnace.
• a treatment gas (so-called wind with 800 - 10 000 m 3 / tRE depending on the size of the furnace) is blow-blown into the furnace.
• the wind which is usually air heated in advance to about 1000 to 1300 ° C.
• substitute reducing agents of, for example, 100-170 kg / tRE (eg, coal dust, oil or natural gas) are usually blown into the furnace, which promotes the generation of carbon monoxide.
• the raw materials melt due to the heat generated by the chemical processes occurring in the shaft furnace.
• the temperature distribution over the cross section of the shaft furnace is uneven.
• the so-called "dead man” is formed, while the relevant processes such as gasification (reaction of oxygen with coke or substitute reducing agents to carbon monoxide and carbon dioxide) takes place essentially only in the so-called vortex zone, which is an area is before a blow mold, that is with respect to the cross-section of the furnace is located only in an edge region.
• the vortex zone has a depth to the center of the furnace of about 1 m and a volume m of about 1.5. 3 are usually arranged in the tuyere several blow molding circumferentially such in that the vortex zone formed before each blow mold overlaps with the vortex zones formed on the left and on the right so that the active area is essentially provided by an annular area.
• the hot blast can usually be enriched with oxygen in order to intensify the processes just described (gasification in the vortex zone, reduction of the iron ore), which leads to an increase in the performance of the shaft furnace.
• the hot blast can be enriched prior to introduction with oxygen, or pure oxygen can be supplied separately, wherein for separate feeding a so-called lance can be provided, i. a tube which is e.g. within the blow mold, which is also a tubular part, extends and opens into the furnace within a mouth region of the blow mold.
• a so-called lance can be provided, i. a tube which is e.g. within the blow mold, which is also a tubular part, extends and opens into the furnace within a mouth region of the blow mold.
• the hot blast is correspondingly highly enriched with oxygen.
• the addition of oxygen increases the production costs, so that the efficiency of a modern shaft furnace can not be increased simply by a correspondingly increased oxygen concentration.
• the efficiency ie the efficiency of a modern shaft furnace is correlated with the so-called gasification in the shaft furnace.
• An indication of better gasification is about the lowest possible pressure loss in the oven.
• the object is achieved by a method with the features of claim 1 and by a shaft furnace with the features of claim 1. 1
• this object is achieved by a method of the type described above, in which the introduction of the treatment gas is dynamically modulated.
• Treatment gas takes place in such a way that the operating variables pressure p and / or volume flow V is varied within a time period of less than or equal to 40 s.
• the change in the pressure and / or the volumetric flow takes place in particular within a period of less than or equal to 20 s, preferably less than or equal to 5 s and particularly preferably less than or equal to 1 s. It has been found that a significantly better gasification and thus an increase in performance and efficiency is achieved when the treatment gas is not introduced evenly in time in the oven, but is varied at short intervals.
• the introduction of the treatment gas also varies in conventional methods whenever the furnace is started or shut down when different operating parameters are set for a new load of raw materials, or if only the oxygen concentration of the hot blast is changed to a higher value to increase the power.
• these changes in time are only one-time changes that take place on a time scale of several hours.
• the dynamic modulation of the introduction of the treatment gas according to the invention takes place on time scales of less than one minute, which is related to the fact that the mean residence time of the gas in the shaft furnace is only 5 to 10 s.
• temporal changes in the operating parameters at a distance of more than one minute have a comparatively short time span during which the operating parameters are not static.
• the time span between two changes in the operating parameters, in which the operating parameters are substantially constant, that is static, is greater than the time required to reach the substantially stationary state.
• such changes are essentially static and are therefore referred to as "quasi-static modulation.”
• the time period with transient conditions in the shaft furnace is greater than the time period with substantially stationary states. Dynamic modulation disturbs dead-flow zones in the vortex zone, which increases the overall turbulence in the vortex zone; This results in an improved gasification in the vortex zone, which in turn leads to improved gasification in the shaft.
• the modulation is particularly advantageously carried out quasi-periodically, in particular periodically, the period being T 40 s or less, preferably 20 s or less, in particular 5 s or less.
• a quasi-periodic modulation should also be understood as one in which g (t) is a continuous, but random function, which undoubtedly distorts the structure of the continuous function f (t) unevenly, although the underlying periodic structure is still recognizable remains.
• a periodic modulation can be addressed by addressing an equally periodic process that takes place in the vortex zone, resulting in a further improvement of the gasification.
• the period T is expedient for the period T to be 60 ms or more, preferably 100 ms or more, in particular 0.5 s or more.
• the residence time of the treatment gas in the vortex zone is extremely low, satisfactory venting can be achieved with period durations in these ranges, with the generation of modulations with even shorter period duration entailing increased technical complexity.
• T For the period T, 40 s> T> 60 ms, preferably 20 s> T> 100 ms, particularly preferably 10 s> T> 7 s and more preferably 5 s> T> 0.5 s.
• T is chosen such that the treatment gases in the shaft furnace form a turbulent flow and substantially avoid laminar regions.
• the modulation is pulsation-like.
• the pulses themselves can be rectangular pulses, triangular pulses, gaussian pulses (spread mathematical ⁇ -pulse) or have similar pulse shapes, the exact pulse shape has less characterizing effect as the pulse width ⁇ , which is the pulse width at half pulse height (FWHM).
• a meaningful tuning of the pulse width results when ⁇ is 5 s or less, preferably 2 s or less, in particular 1 s or less.
• the pulse width ⁇ is 1 ms or more, preferably 10 ms or more, in particular 0.1 s or more. Very small pulse widths are more difficult to produce, on the other hand, with them an influence on processes that take place in the vortex zone with correspondingly short reaction times succeeds.
• periodic pulsations have a ratio of pulse width to period duration ⁇ : T of 0.5 or less, preferably 0.2 or less, in particular 0.1 or less.
• T 0.5 or less
• ⁇ preferably 0.2 or less
• the ratio ⁇ : T is 10 -4 or greater, preferably 10 -3 or greater, in particular 10 -2 or greater, so that a combination effect can be achieved in the processes which occur periodically in the vortex zones and at certain temperatures Response times are coupled to be addressed.
• the amplitude of the modulation with respect to a basic value is 5% or more, preferably 10% or more, in particular 20% or more. It has been found that even small differences in amplitude allow a satisfactory für gasung.
• the amplitude of the modulation with respect to the base value is 100% or less, preferably 80% or less, in particular 50% or less. In particular, harmonic modulations below these limits can be easily realized in terms of the method.
• the pulse height of a pulse exceeds the substantially unmodulated value between two pulses by a factor of 2 or more, preferably 5 or more, in particular 10 or more.
• the shock effect of the modulation can be increased, and the disturbance of the Totströmungszonen be amplified in the vortex zone, which eventually leads to a better gasification in the furnace.
• the factor is 200 or less, preferably 100 or less, in particular 50 or less.
• a modulation of the introduction of the treatment gas can take place in a variety of ways.
• the modulation is expediently via setting at least one in particular the introduction of the treatment gas controlling operating size done.
• a modulation of the pressure of the hot blast can accelerate the gasification in the vortex zone and thus improve the gasification in the shaft.
• pressure peaks of 300 bar may occur during pressure modulation.
• the treatment gas to be introduced has distinguishable components. However, this includes not only the self-evident division of a gas into its components (eg nitrogen, oxygen, etc.), but also different gas phases whose distinctness is due to the fact that they are introduced separately at least at a stage of initiation become. For example, here is the separate oxygen supply by lances, valves or diaphragm to call.
• the effects achieved in the method according to the invention are significantly enhanced if, together with the treatment gas and / or in addition to the treatment gas, replacement reducing agents are introduced into the shaft furnace.
• the substitute reducing agent may be pulverized coal produced in particular from anthracite coal, other metallurgical dusts and small granular materials, oil, fats, tars with natural gas or other hydrocarbon carriers, which are converted to CO 2 and CO due to the oxygen, and in particular present as nano-particles. Because of the modulation according to the invention, namely, a higher degree of implementation of the injected replacement reducing agent can be achieved. This applies in particular to pulsation-like modulation, as the reaction is intensified by the pulses.
• the aforementioned increase in total turbulence in the vortex zone prolongs the very short residence time of the replacement reductants in the vortex zone from only about 0.03 seconds to about 0.05 seconds, which can also increase the reductant conversion. Furthermore, a better implementation of the replacement reducing agent leads to a lower proportion of unburned particles, which promotes the gasification in the "birdsnesf" area and thus allows an additional increase in the injection rate.
• pressure and / or volume flow of at least one of the distinguishable fractions of the treatment gas and / or pressure and / or mass flow of the replacement reducing agent to be introduced are dynamically modulated. Better intuitivegasung in the shaft is thus also achieved if z. B. the treatment gas, an additional oxygen content is pulsed. Otherwise, or in combination, the pressure at which replacement reductant is injected or its mass flow can be dynamically modulated.
• the mass flow is identical to the volumetric flow, but on the other hand, the mean density of the substitute reducing agent could be dynamically modulated even with constant volumetric flow. It can also be at least temporarily blown in whole or in part inert gas, for example, unwanted To regulate temperature peaks or to cool the supply lines or arranged in the supply lines valves.
• the operating variable is particularly advantageously the absolute amount of one of the distinguishable fractions of the treatment gas to be introduced, and / or the relative proportion of one of the distinguishable fractions with respect to a further fraction or the entire treatment gas.
• the absolute oxygen quantity or the relative oxygen concentration are modulated dynamically, although the main load, namely the hot wind itself does not have to be modulated.
• This is particularly easy to implement, when pure oxygen or a gas phase with air-increased oxygen concentration is supplied separately at least during part of the introduction. If this happens pulsating, the implementation of the substitute reducing agent can be further intensified, with the further intensified effects already mentioned.
• the amplitude of the extra oxygen volume flow with respect to that of the background wind in the range 0.25 - 20%, preferably 0.5 - 10%, in particular 1 - 6%.
• the treatment gas is introduced into the shaft furnace in at least two different ways, and a first operating variable for the control of the portion to be introduced along the first path is dynamically modulated as a second operating variable for controlling the portion of the treatment gas introduced along the second path.
• first and second operating variables may also be the same operating variable, but their modulation may also be different modulations.
• a further advantageous method embodiment provides that the first and the second operating variable are periodically modulated with the same period T, wherein their relative phase is shifted by one value. The phase is thus a time shift related to the period T. If the relative time shift is, for example, T / 2, the two operating variables are anticyclically modulated relative to one another.
• oxygen pulsations may be slightly retarded in relation to corresponding pulsation-like increases in the amount of substitute reducing agent, that is, for example, shifted by 0 ⁇ ⁇ / 2.
• the inverse period T "1 is set to an autofequency of a subsystem of the atmosphere within the shaft furnace, whereby a subsystem of the atmosphere is firstly understood to mean a spatial subsystem, which here is given by the vortex zones; This refers to the frequency of a linear excitation in the radial direction (from the tuyere to the middle of the furnace) or vortex excitations in the vortex zone of a single blow mold, but also around a vortex-zone vortex excitation in the circumferential direction of the shaft furnace, wherein the standing in the spatial center of this excitation "dead man" for such a vortex oscillation topologically represents a hole.
• the modulation takes place, for example, in terms of pulse duration, pulse frequency or pulse strength such that a standing wave results in the shaft furnace. Additionally or alternatively, the modulation takes place in such a way that the raw materials sink uniformly in the shaft furnace, in particular in the form of a plug flow. For this purpose, the modulation can be regulated as a function of measured process variables.
• a further advantage of the stated method lies in influencing the vortex zone geometry, so that the area in which the main coal conversion takes place is increased. It can therefore be increased without additional energy or material expense, the performance of the shaft furnace, so an improved efficiency can be achieved.
• Another aspect of the invention relates to a method of the type described above, wherein in a first phase of operation at least one of the operating variables is dynamically modulated setting a parameter, the effect of the modulation of the at least one operating variable is registered to at least one characteristic of the shaft furnace, then the Parameters after one predetermined system is varied and the varied parameter is set for the modulation, wherein after each variation and readjustment of their effect on the characteristic is registered, then selected from the variable parameters corresponding to the registered values of the characteristic according to predetermined selection criteria a characteristic value with the associated parameter value and, in a second phase of operation, dynamically modulating the at least one operating variable with the selected parameter value.
• an optimal parameter value (eg, an optimal period duration) is selected based on which the dynamic (eg periodic) modulation takes place.
• this optimization method can be carried out for further parameters, so that overall an optimum group of parameters can result, on the basis of which the dynamic modulation takes place.
• the invention also relates to a shaft furnace, which can be operated by the method according to the invention.
• the shaft furnace is in particular as explained above with reference to the method according to the invention and further developed.
• the means for introducing the treatment gas on a first and a second tubular part wherein in addition to a main line over which a portion of the treatment gas is introduced, via the first tubular part, an oxidizing agent and the second tubular part Spare reducing agent is inflatable.
• an oxidizing agent such as.
• oxygen or oxygen-enriched air as well as substitute reducing agent can be introduced separately into the shaft furnace, which allows an independent and structurally easy to implement dynamic modulation of the discharges.
• a control device is set in such a way that within a
• the operating variables pressure p and / or volumetric flow V can be varied.
• first and second tubular part are at least partially connected to a double tube lance, wherein the tubular parts may be arranged concentrically or eccentrically to each other.
• the functional requirements of the tubular parts can be combined with a space-saving arrangement.
• the first and the second tubular part are spatially separate lances, wherein at least one exit angle of one of the tubular parts is adjustable with respect to a horizontal and / or vertical plane of the shaft furnace, in particular the exit angle of both tubular Parts are independently adjustable.
• the injection direction of about additional oxygen or the reducing agents with respect to the vortex zone geometry can be varied.
• it can also be thought to also dynamically modulate the exit angle according to the above explanations when the shaft furnace is operated.
• ceramic valves in particular disk valves or piston magnet valves, are provided in the supply lines to the shaft furnace, so that the valves are resistant to high temperatures and to high temperatures.
• the valves therefore have a particularly low thermal expansion and can therefore be operated without difficulty even at the particularly high temperatures occurring during operation.
• the device for introducing the treatment gas is connected to at least two storage containers, wherein the storage containers are loaded in particular swelling.
• the storage containers have, in particular, a different volume and / or a different pressure, so that a specific storage container can be connected as needed to achieve a specific modulation. It can also be connected to a plurality of similar storage container so that when emptying the respective storage container, the pressure in the storage tank drops only slightly and sufficient time is available to replenish the storage tank to its original state while the other storage tank is connected.
• the means for introducing the treatment gas comprises a first set of valves and a second redundant set of valves. This makes it possible to operate the individual sets alternately, so that the valves can cool down.
• the cooling can be further improved by the not required for the supply of the treatment gas valves by means of a gas, in particular Intertgases be cooled.
• a method for operating a shaft furnace is specified, which is characterized in particular in addition to the already described method features in that acting on the prevailing in the upper region of the shaft furnace atmosphere from the upper portion of the shaft furnace in a dynamically modulated manner ,
• the above-described effect of dynamic modulations on an area of the atmosphere restricted to the vortex zones can be reduced to one wider range, namely by B.
• B. is located in the upper region of the shaft furnace blast furnace gas is dynamically modulated.
• additional gas can be introduced into the upper region of the shaft furnace and / or the top gas pressure can be modulated by suitable control of valves provided in a top gas discharge.
• the dynamic modulations can advantageously be matched with respect to, for example, period and amplitude such that a direct further resonance excitation becomes possible, or the excitation of a subsystem of the atmosphere prevailing in the shaft furnace only comes about through a coupling effect of the external excitations.
• Fig. 1 shows a time-pressure diagram
• Fig. 2 shows another time-pressure diagram
• Fig. 3 shows a time-concentration diagram
• Fig. 4 shows a time-mass flow diagram
• Fig. 5 shows a combined time-mass / volumetric flow diagram.
• Fig. 1 it is shown how the pressure of, for example, the treatment gas to be introduced into the shaft furnace can be dynamically modulated.
• the base pressure p 0 in this example is 2.4 bar.
• the pressure amplitude 2 ⁇ p in this example is 1.2 bar, ie 50% of the basic pressure value p 0 .
• FIG. 2 shows a pulsation-type modulation of the pressure of a portion of the treatment gas to be introduced into the shaft furnace.
• the pulse height p max is 50 bar, which means a pulsation with an amplitude factor of 20 compared to, for example, 2.5 bar ambient pressure of the introduced hot blast.
• the pulses have a pulse width ⁇ of about 0.4 s, so that a ratio of pulse width to period duration of about 0.1 results.
• a dynamic modulation of the oxygen concentration of the treatment gas is exemplified. This is achieved as follows: A self-unmodulated hot blast of the treatment gas provides a constant base concentration n 0 , which corresponds to the natural oxygen concentration in air (the hot blast here consists of hot air). In addition to the hot blast, two more portions of the treatment gas are now introduced. A first fraction, which consists either of pure oxygen or of an oxygen-containing gas phase with oxygen concentration n ', is pulsed periodically introduced with a period Ti of 2 s. The amount of pure oxygen or the concentration n'i is chosen so that the oxygen concentration is increased with respect to the total treatment gas by a concentration difference ni.
• / n 0 is about 60%.
• This phase-shifted pulse-like second gas component leads to an increase in the oxygen concentration with respect to the total treatment gas from n 0 to no + n 2 , as shown in FIG. 3 can be seen.
• the ratio n 2 / n 0 is about 40%, so the second gas phase effectively supplies less oxygen to the treatment gas than the first. It can be clearly seen in FIG.
• the phase shift ⁇ is approximately ⁇ / 2.
• FIG. 4 shows the temporal modulation of the injection rate of substitute reducing agents, which may be coal dust, for example, or, respectively, their mass flow m / dt.
• substitute reducing agents which may be coal dust, for example, or, respectively, their mass flow m / dt.
• the pulse width ⁇ here is relatively large and is approximately T / 4.
• FIG. 5 shows the simultaneous temporal modulation on the one hand of the mass flow m / dt of a substitute reducing agent and on the other hand of a volumetric flow V / dt of oxygen.
• the temporal modulation of the oxygen volume flow V / dt which also occurs periodically with T, can be generated, for example, by a proportion Vo / dt caused by the natural oxygen volume flow of the introduced hot air, and is periodically increased by additionally supplied oxygen pulses. As can be seen from FIG.
• a blast furnace is provided as shaft furnace, which has a pressure of about 2 to 4 bar in its interior.
• the treatment gas can be injected at a continuous pressure of about 10 bar.
• a storage container which has a pressure of, for example, 20 bar, can be temporarily switched on via a valve.
• a short-term pulse can be generated with an increased by 1, 5 to 2.5 bar pressure, that is, the pressure of the treatment gas has a pressure of about 12 bar during the pulse.
• a burst of energy is generated within the blast furnace by the treatment gas, which melts encrustations and slags on the surface of the reaction zone and / or perforates the layer in the encrustations and slags. Since oxygen is transported into the slag layer of the reaction zone by the energy collision, oxidation reactions take place with the slag layer. The resulting dissolved slag allows better flow through the entire blast furnace.
• the formation of slag can at least be reduced if very small coal particles are mixed in the treatment gas, so that the reaction in the reaction zone results in less unburned constituents that might otherwise settle in the slag.
• the effects of the modulated blown treatment gas can be enhanced by providing multiple injection sites along the circumference and / or along the height of the blast furnace.
• a shaft furnace designed, for example, as a cupola can, in principle, be designed and operated as described above with reference to the blast furnace.
• a cupola is operated at a lower pressure, for example 300 mbar.
• the treatment gas can be injected continuously at a pressure of 5 bar, wherein the switchable storage container can have a pressure of 12 bar.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Vertical, Hearth, Or Arc Furnaces (AREA)
• Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
• Manufacture Of Iron (AREA)
• Furnace Details (AREA)
• Gasification And Melting Of Waste (AREA)
• Blast Furnaces (AREA)
• Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
• Heat Treatment Of Articles (AREA)

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