WO2018014148A1 - 梯级焙熔还原炼铁方法及设备 - Google Patents

梯级焙熔还原炼铁方法及设备 Download PDF

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WO2018014148A1
WO2018014148A1 PCT/CN2016/000406 CN2016000406W WO2018014148A1 WO 2018014148 A1 WO2018014148 A1 WO 2018014148A1 CN 2016000406 W CN2016000406 W CN 2016000406W WO 2018014148 A1 WO2018014148 A1 WO 2018014148A1
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unit
reduction unit
coal
heat exchange
hot air
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PCT/CN2016/000406
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English (en)
French (fr)
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夏忠仁
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夏忠仁
包桃芬
夏体娇
夏兰心
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Application filed by 夏忠仁, 包桃芬, 夏体娇, 夏兰心 filed Critical 夏忠仁
Priority to CN201680084856.9A priority Critical patent/CN109477152B/zh
Priority to PCT/CN2016/000406 priority patent/WO2018014148A1/zh
Publication of WO2018014148A1 publication Critical patent/WO2018014148A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B11/00—Making pig-iron other than in blast furnaces
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • This invention relates to the field of smelting reduction ironmaking.
  • it relates to a method for baking and reducing ironmaking by a composite carbon-containing pellet of a two-layer structure.
  • the invention is a new baking and reduction reduction iron making method developed on the basis of the patented technology of Chinese Patent No. 200710065973.3 "Baked and reduced iron making method and device and raw material" proposed by the applicant in 2007, also in the steel field Ironmaking energy consumption is the background technology.
  • the current large-scale blast furnace steel production is only a kind of replication and amplification in the structure of small and medium-sized blast furnace.
  • the total ironmaking process includes four factories, such as coking plant, sinter plant, pellet plant and ironworks, which adds waste gas for recycling.
  • a small thermal power plant The longer the chain of production links, the worse the reliability, safety and coordination of the equipment.
  • energy consumption the difference between 3000m 3 and 5000m 3 blast furnace is very small.
  • the increase of the column height increases the pressure on the lower part, and the quality requirement of coke is more demanding.
  • the blast resistance increased and the blast power consumption increased.
  • the blast furnace gas has low heat quality and can only be used to generate electricity by 30%, and 70% of pulverized coal. This is essentially the concept of small coal-fired power plants, which are low in energy conversion efficiency.
  • the two processes of coking and sintering are heat-consuming production operations and cause 80-90% of the entire plant pollution source.
  • any method of smelting molten iron should first be a system of integral sealing, and the chemical energy and thermal energy generated by coal combustion are completely recycled by itself.
  • the comparative premise of the various methods is that the same raw material and the same fuel are used, and the obtained product molten iron and by-product slag should take away the same heat, and only the gas energy of the exhaust gas outlet is the only method.
  • the blast furnace system is an open system.
  • the energy leakage has three links: coking, sintering and gas output. Finally, It is the exhaust gas outlet of the hot blast stove. Therefore, the blast furnace method cannot be said to be an advanced method.
  • All the iron making methods are from the position where the reducing tail gas outlet is in the reducing equipment.
  • the gas overflowing from the upper outlet is controlled by the indirect reduction of the chemical equilibrium gas phase inside the furnace.
  • the utilization rate of CO is less than 55%.
  • the hot gas from the top gas leaving the outlet can be reused for 30 to 35% of the remaining energy.
  • the gas is not used for power generation and can only be discharged into the atmosphere after useless combustion; the high temperature gas overflowing from the lower outlet of the reduction equipment provides direct reduction and heat loss for the slag and molten iron in the internal space of the furnace, and the temperature must be higher than the slag and The temperature of the molten iron, otherwise the melt will cool down. It is impossible to directly remove the dust from the airflow above 1450 °C.
  • the dust contained in the furnace is also a tiny bead in the molten state, which will immediately block the internal space of the conveying pipe and the precipitator, and then the heat-treating material of the heat-exchange device cannot be stored. Withstand such high temperatures.
  • the object of the present invention is to provide an iron making method for automatically recycling the energy energy of the coal into the furnace; and to provide a complete set of special equipment for the energy self-sealing circulation system of the method.
  • the first is the use of composite carbon-containing pellets as charge.
  • the preparation of the composite carbon-containing pellets first forms a carbon-containing iron oxide core, and then forms a pellet outer layer of the iron oxide raw material by means of secondary ball formation.
  • the remaining energy of the previous step flows into the lower cascade for direct utilization.
  • Three independent reduction unit units are connected in series in the direction of hot air main flow, and the three series of reduction units are connected at the bottom to form a common slag, molten iron and gas flow passage and a melt storage common space.
  • the three reduction units are relatively independent, each has a separate feeding system, and each of them completes the respective reduction and melting operation load quota.
  • the main flow direction is divided into a first step reduction unit, a second step reduction unit and a third step reduction unit.
  • the top of the third step reduction unit is directly connected to the hot precipitator outlet, and the lower dust outlet of the hot precipitator unit is connected with the furnace dust return passage to the upper internal space of the second step reduction unit, and the upper part of the precipitator unit is dedusted at a high temperature.
  • the exhaust gas outlet is connected to the high temperature heat exchange gas inlet of the hot air furnace heat exchange unit through the insulated pipe and the controlled gate valve system.
  • the hot air outlet of the hot air furnace heat exchange unit is connected to the hot air inlet of the top of the first step reduction unit through the insulated pipe and the controlled gate valve system.
  • the first step reduction unit, the second step reduction unit, the third step reduction unit, the hot precipitator unit and the hot air furnace top heat exchange unit are first and last seamlessly sealed to form a ring-shaped sealed circulation system;
  • the normal temperature air inlet of the hot air furnace heat exchange unit is connected with the blower unit through the switching gate valve and the pipeline, and the heat exchange exhaust gas outlet is passed through the switching gate valve and the pipeline.
  • the coal and the composite carbonaceous pellet drying unit are directly connected, so that the hot air furnace heat exchange unit is used as a node, and the seven units are again formed into a tie shape and seamlessly connected into a complete energy sealed circulation system device.
  • the whole energy sealing circulation system equipment may have multiple material inlets, and the outlet is only three outlets of the slag outlet at the lower part of the first step reduction unit, the two product outlets of the molten iron outlet, and the dry exhaust gas outlet at the drying unit.
  • the heat exchange waste gas is directly used for material drying, and the drying process of the material in the reduction unit furnace is moved to the outside of the furnace, and the heat is finally reused, and the charge can be hot-packed and brought back to the system again.
  • the third method is the charging method of the charging material.
  • the composite carbon-containing pellets are used as the charging method of the charging materials, and are divided into three ways to add three cascade reduction units, and the two ends of the respective load distribution are mainly supplemented by the middle: one road and the materials such as coal and flux are pressed.
  • the required proportion is mixed by the upper receiving hopper of the first reducing unit, the sealed feeding tank and the discharging tube into the top of the furnace chamber column of the reducing unit; the other is a single composite carbon-containing pellet charge, and the third step reducing unit
  • the upper receiving hopper, the sealing feeding tank and the discharging tube enter the top of the reduced furnace chamber column; the third road is fed with a small amount of quota as the regulating charge from the upper portion of the second step reducing unit to the unit furnace chamber.
  • the high temperature furnace dust and lime powder collected by the hot dust removal unit are transported by airflow into the furnace cavity space of the second step reduction unit.
  • the reducing agent of FeO in the second step reducing unit slag and the pulverized coal required for carburizing are fed into the common bottom molten iron from the lower portion of the third step reducing unit by air flow or spiral conveying.
  • the fourth is the way of the main airflow operation.
  • the normal temperature air is driven by the blower unit, and the whole set of energy sealing circulation system formed by the seven units of the second technical measure runs through the coal and composite carbonaceous pellets.
  • the unit drying exhaust gas outlet is discharged.
  • the three steps of the three-stage reduction unit can be seen as a whole reduction unit when they are connected in series. Different from the prior art, the hot air inlet and the reduced exhaust gas outlet are all on the top of the furnace.
  • the main airflow looks like the top of the furnace. , flowing through three different reduction areas inside.
  • the melting, reduction endotherm and preheating endotherm interception of the third step reduction unit utilizes heat in the gas stream in the range of 1500 ° C to 1100 ° C.
  • the temperature of the reduced off-gas exiting the top outlet of the third step reduction unit is suitable for hot dust removal and heat exchange. If there is still a small amount of residual CO in the reducing exhaust gas, the hot air of the other hot blast stove can be diverted into a small portion and passed into the top of the hot blast stove to be combed or burned.
  • the fifth is the heat and temperature regulation of each unit.
  • the other units can be separately equipped with a small fuel or gas fuel.
  • the high-temperature combustion gas is directly injected into the furnace to accurately measure the heat and temperature of each unit. Adjustment and heat supplement adjustment.
  • Another temperature adjustment measure is to set a temperature adjustment furnace feed inlet at the top of the second step reduction unit.
  • the unit furnace chamber temperature is higher than 1550 ° C, a small amount of composite carbonaceous pellets are directly involved in the reduction melting endotherm, and the temperature is set. Controlled at 1450 ° C ⁇ 1500 ° C.
  • Fig. 1 is a schematic view of a dedicated device for a complete energy sealed circulation system of the present invention, and is also a drawing of the specification and a drawing of the abstract.
  • FIG. 2 is a schematic flow chart of a gas flow operation of a complete energy sealed circulation system according to an embodiment of the present invention.
  • the unit volume m 3 indicated is a standard volume m 3 (0 ° C, 760 mm Hg).
  • the furnace material of the step reduction unit has been shown in Table 4, so it is indicated by a blank arrow.
  • Table 1 is a table of feature sequences identified by the reference numerals of Figure 1.
  • Table 2 is a table of the composition and chemical composition of iron ore fines and coal used in the examples.
  • Table 3 is a composite carbon-containing pelletizing ingredient list.
  • Table 4 is a feed table for the three-stage reduction unit.
  • Table 5 is a balance sheet per ton of molten iron material in the examples.
  • Table 6 is a table of sources of slagging components of the examples.
  • Table 7 is a heat balance table of the third step reduction unit of the embodiment.
  • the special equipment shown in Figure 1 is seamlessly connected in series by 8 independent units such as (1)(2)(3)(4)(5)(6)(7)(8), where (5)( 6)
  • the two units are a unit of unit, essentially only seven units.
  • Each unit has its own functional system, including working components, powertrain, operational control systems, and actuators, not shown in Figure 1, included within each unit.
  • the smelting reduction technology is the only alternative to blast furnace technology.
  • the present invention is a modification for the former and an inheritance for the latter.
  • the use of coal in blast furnace technology starts from the coking plant.
  • the sinter plant uses coke powder, pellet plant gas, pyrolysis plant coke block and injection pulverized coal, and then pulls out an inefficient small thermal power plant, any A supporting factory must consume energy.
  • the process of coking, sintering, pelletizing and iron making of the invention completes the operation in a set of equipment of energy sealing cycle in one process, and the energy is used in downstream steps.
  • the coal starts from the inside of the pellet, and is coked with other coals to form volatiles after being charged into the furnace.
  • the combustion of the volatiles and the secondary combustion of CO in the reducing product gas support the reduction and melting heat demand.
  • the invention has low transformation cost and low production operation cost.
  • the invention can achieve and break through the minimum coal consumption of the smelting reduction technology.
  • the bulk iron ore fines have an iron grade of 58.270%. Iron ore fines of 1716 kg are required per ton of iron.
  • the iron content distribution ratio of the iron ore in the ball core material and the outer layer material is 50% to 50%, but considering the carbon particles on the surface of the core of the contact interface between the core and the outer layer, the iron oxide of the outer layer of the inner and outer layers is also oxidized.
  • the material produces a direct reduction effect, and a part of the iron ore powder near the outer interface is divided into the core fraction.
  • the ingredients were 45% to 55%.
  • the outer iron ore fines can be used to increase the thickness of the outer layer of the pellets by using iron ore fines with a slightly lower iron grade, thereby increasing the distance of the nuclear product gas diffusion in the outer layer and the time of indirect reduction, and also increasing the end of the reduction. Reoxidation resistance of metal pellets.
  • the fixed carbon of the batch coal is less than 80%, which is 79.120%.
  • the carbon content of the core is calculated according to the fixed carbon, 320kg carbon/ton iron is added, and the iron content of the core is 50%, and the iron content is calculated. With a total share of 45%.
  • the carbon content of the composite carbon-containing pellets used in the composite carbon-containing pellets and the third-stage reduction unit of the first step reduction unit may be different, and the latter is added with a certain excess amount to facilitate the infiltration of the product iron after the reduction. Carbon, increasing liquidity.
  • Table 3 is a table showing the composition of two composite carbon-containing pellet cores and outer layers.
  • the composite carbon-containing pellets are made by forming a ball into a ball, which can be used to cause the core on the first ball forming machine, rolled into the second pelletizer and into the spherical disk while feeding the outer layer into a ball. Process. It can also be completed on a ball-making machine.
  • the ball-forming disc of this ball-making machine is adjustable in angle and tilted, and the angle of the ball-making disc is adjusted until the pellets do not roll out of the disc.
  • the ball core is formed into a spherical core, and then the outer layer material is fed into a second ball to form an outer layer of the ball, and then the water is dried and rolled to make the composite carbon-containing pellet enter a strong period of making the ball, and a small amount of dry powder is added to adjust the water. The portion retains 8 to 10% of water.
  • the finished ball is discharged once and turned into a ball plate and transported away by the belt conveyor. The dome is reset for the next cycle.
  • Practice has proved that the method has precise ingredients and easy control of water.
  • the strength of the sphere is higher than that of the former and ordinary ordinary pellets, and fully meets the requirements of transshipment and furnace conditions.
  • the bulk coal volatiles were 9.926%, and the flammable groups C, H and S in the volatiles were 3.856%, 3.323% and 0.503%, respectively, which were the basis for calculating the calorific value.
  • the calorific value of calorific value per kg of coal is 6.035 MJ, which requires 1.228 m 3 of air to assist combustion; the ash content of coal is 10.660%, and the fraction of SiO 2 and CaO in the ash is incorporated into the ore to calculate the CaO addition amount to adjust the pH of the slag.
  • the charging method of the composite carbon-containing pellets is such that the first portion is divided into three portions according to the share, and the first portion is mixed with the coal and the solvent in a desired ratio, and the hopper (10) of the first reduction unit and the sealed feeding series tank ( 11), preheating the feeding tube (12) enters the top of the packed bed column of the unit; the second part is the feeding hopper (16) of the single composite carbonaceous pellet passing through the third step reducing unit, and the sealed feeding series tank (17)
  • the feed pipe (18) enters the top of the packed bed column of the reduction unit; the third portion is a small amount of the adjusted temperature share entered by the temperature-regulating composite carbon-containing pellet charge inlet (38) of the second step reduction unit
  • the space inside the unit furnace, if appropriate, the third part can not be used.
  • the normal temperature blast switching gate valve and the piping system (2) are switched by the hot air furnace heat exchange unit (5) and (6) the blast air temperature air inlet (33). And (34) the lower space of the unit, the heat of the heat storage refractory material is carried away by the bottom-up convection.
  • the blast temperature after heat exchange rises to about 900 °C, and the high temperature gas inlet and hot air outlet common ports (25) and (26) of the upper part of (5) and (6) are switched by the high temperature hot air switching gate valve and the insulated pipe system (35).
  • the high temperature air inlet (9) to the top of the first step reduction unit (1) enters the furnace space above the top of the column of the unit, and the high temperature hot air is split into one air flow and two roads above the top of the unit column. Divided airflow.
  • the main gas stream is in the same direction as the charge, preheating the charge and burning the unit (1) all the volatiles generated by the coking of the coal and the CO gas remaining in the composite carbonaceous pellet reduction product gas and the supplementary fuel granules to provide a reaction Heat absorption and melting of the required heat of slag and iron, the formed high-temperature gas carries the residual heat directly into the bottom of the second reduction unit (2), and merges with the split second hot air to re-burn the reduction unit (2) into the molten iron.
  • the pulverized coal directly reduces the product gas and volatile matter of the iron oxide in the slag, and the heat loss required for the reduction unit (2) is directly passed through the bottom space into the bottom passage of the third step reduction unit (3), and is provided upstream.
  • the unit melts heat loss, and once again merges with the third-way split hot air to completely burn the remaining CO gas in the composite carbon-containing pellet product gas and the volatiles of the coal coking in the pellet core.
  • the final reduced exhaust gas is a high-temperature gas that is completely burned below 1100 ° C.
  • the high-temperature gas overflowing from the top outlet of the third step reduction unit (3) directly enters the interior of the hot-dust remover unit (4), and the high-temperature gas after dust removal From the high-temperature gas switching gate valve and the insulated pipe system (24) and the hot air staggered period, the high-temperature gas inlet and the heat exchange high-temperature air outlet of the hot-air stove heat exchange unit (5) and (6) (25) and (26) enter the inside of the hot blast stove, and the temperature of the heat exchange exhaust gas after heating the heat storage material inside the hot blast stove drops below 300 ° C, and the heat exchange exhaust gas outlets of the hot air furnace heat exchange units (5) and (6) 28) and (29) through the heat exchange exhaust gas switching gate valve and piping system (27) directly into the coal and combined carbonaceous pellet drying unit (8) heat exchange exhaust gas inlet (30), used for drying the dry exhaust gas temperature again After falling below 100 °C, the water vapor with the same temperature is dedusted again and discharged into the atmosphere, where the energy-sealing
  • the second step reduction unit is not added to the composite carbon-containing pellets, and the reduction unit at both ends is in a balanced and suitable state, and the deviation is accurately adjusted in the production.
  • the composite carbonaceous pellet used in the invention is an acid charge, and the gangue has a high melting temperature, and plays a certain skeleton action and a growth reduction temperature interval in the lower part of the third step reduction unit, and also increases the gas permeability and the metal ball. Group protection and anti-reoxidation.
  • the lime powder added by the three material inlet common port (14) of the second step reduction unit is heated by the high temperature furnace gas and is fed into the bottom of the third step reduction unit column to contact the unmelted bottommost pellet, CaO and pellet gangue. Both SiO 2 are in the vicinity of their respective melting temperatures, and mineralization rapidly melts the metal pellets to form a liquid phase.
  • the reducing agent action of the coal into the furnace of the invention consists of three parts, the direct reduction and indirect reduction of the internal fixed carbon and iron oxidation of the composite carbon-containing pellet, the direct reduction and the slag-gold interface when the molten slag flows through the solid carbon block Melting reduction of carbon in molten iron and FeO in slag.
  • the direct reduction of solid carbon occurs only in the first step reduction unit.
  • the heating effect of the coal into the furnace is also composed of three ways. The first is the combustion of the volatiles generated by the thermal coking of all the coals including the carbon coal, the carburized coal and the direct reduced carbon-consuming coal added to the pellet core. The second is the secondary combustion of CO in the product gas of the reduction reaction, and the third is the direct combustion of the supplemental heat into the furnace coal. These three combustions are fully combustible for oxygen supply in the present invention.
  • the first step reduction unit of the three-step baking reduction technology of the invention is the starting point and the source of the energy sealing cycle of the coal into the furnace. From Table 4, it is shown that 70% of the total coal is added from the first step reduction unit, except for the heat expenditure of the unit. After that, the remaining energy flows to the next step reduction unit.
  • the composite carbonaceous pellets and coal of the first step reduction unit are added together with lime to form a neutral charge.
  • the melting point of the slag is about 1250 ° C, and the flowability is also good when the molten iron is carburized at 1250 ° C.
  • the furnace gas at 1300 ° C is good. Temperature is more suitable.
  • the output gas temperature of the second step reduction unit is 1472 ° C, which is in the temperature range of the refractory material, and the temperature of the gas, slag and molten iron after melting the metal pellet at the bottom of the third step reduction unit is 1400 ° C, which is the slag
  • the iron countercurrent reverses the heat return of the heat of the former unit, and the upper side supports the direct reduction endothermic heat and heat of the composite carbon-containing pellet core.
  • test data indicates that the reduction time does not exceed 5 min. The shorter the time from the preheating, reduction and melting of the composite carbonaceous pellets in the furnace, the smaller the required height of the column, and the lower the pressure of the lower soft layer of the column, and the lower the blast resistance.
  • the inventors also used carbon dioxide gas protection automatic welding technology in the manufacture of the furnace structure of the baking reduction plant. This is the most direct and most common practice evidence. Another is that N 2 , which accounts for 79% of the original air volume fraction in the high-temperature flue gas, remains in it. The difference between the CO 2 concentration in the flue gas and the CO 2 gas concentration used in the protective welding is similar to the difference between pure oxygen and air. Air is not an alternative to pure oxygen as an oxidant for cutting steel plates. The role of nitrogen barrier oxidation cannot be ignored.
  • the dust of the 20kg dust/ton of molten iron and the 44kg of lime powder/ton of molten iron added by the second step reduction unit in the present invention is carried by the high temperature flue gas into the bottom of the composite carbonaceous pellet column for the molten iron and
  • the surface covering and shielding of the molten iron is as follows: the blast furnace tapping field covers the surface of the molten iron in the iron gutter with dry slag, and the oxidation of the surface of the molten iron by oxygen in the air is isolated.
  • the core technology of the baking reduction is to use the composite carbon-containing pellets as the charging of the furnace-like oxidized pellets, the reduction in the oxidizing atmosphere, and the reduction of the pellets to be melted into the final reduction zone in situ, so it is named as the baking reduction.
  • the product gas is forced to migrate toward the surface of the pellet under the driving of the pressure inside the pellet, and the outer layer of the pellet hinders the protection, preventing the oxidizing gas in the ambient gas phase from entering the inside of the pellet, so the third step of the present invention
  • the split high temperature air inlets (19) and (20) of the reduction unit are arranged at the column reduction zone. At the end of the reduction, the combined results of the three factors result in a shorter melting process.
  • the second aspect is the direct action of the lime powder sprayed into the slagging heat to supplement the hedging heat
  • the third aspect is the slag component CaO and SiO 2 acid.
  • the neutralization of the base changes from the respective high melting point to the low melting point of the neutral slag.
  • the liquid melt quickly drops or flows into the lower common melt storage space, the slag is on, the molten iron is under, and the reoxidation of the product iron is difficult to occur.
  • the layered technical measures of the present invention ensure reliable and antegrade stages of the melting stage.
  • reaction formula (6) and the reaction formula (8) are a pair of reversible reactions.
  • the reoxidation reaction formula (8) will occur.
  • the special contribution of the baking reduction technology to science lies in the following explanation:
  • the direct reduction reaction formulas (6) and (2) occur in the internal sealed environment of the composite carbon-containing pellets, and the product gas is discharged to the outside by self-pressure. Kinetically limited spontaneous gas-solid reaction.
  • the reaction formula (8) is a reaction between a gas phase and a liquid phase surface in an external gas phase environment.
  • the reaction rate of the reaction formula (8) is controlled by the reaction kinetic restriction.
  • the reaction formula (6) and the reaction formula (8) are separated into two different regions for the present invention.
  • Another feature is that the reaction time reserved for the reaction formula (8) is only a few tenths of the reaction formula (6), and the yield of the reaction product is proportional to the reaction rate and time.
  • the present invention has a reason not to consider the high temperature flue gas to the molten iron. The effect of slight reoxidation, like the steelmaking converter dumping molten steel, does not consider the reoxidation of molten steel by air.
  • the second step reduction unit may be a reverberatory furnace structure.
  • the heat expenditure of the second step reduction unit is shown to be 0.456 GJ from the heat balance of Table 3, accounting for 13.776% of the heat income 3.31 GJ, and the thermal efficiency in the reverberating furnace (15-30) %) covered. This is also a possible guarantee for the embodiment of the present invention.
  • Thickness of Slag Layer The present invention uses a thin slag layer operation, that is, reduces the distance of iron oxide migration from the slag to the slag-gold interface and reduces the thermal resistance of heat transfer.
  • the furnace body of the first reduction unit of the invention can be regarded as a coal-fired shaft furnace, and the charge material is in the same direction as the gas flow, and the difference in the moving speed between the two is large, and the heat is substantially opposite to the convection.
  • Part of the hot air is forced to flow from the top of the column to the lower part, and a part of the hot air is blown from the different positions to the inner peripheral side through the internal vertical passage and the lateral passage of the lining refractory to ensure the reduction.
  • Complete combustion of gases, volatiles and supplemental coal Complete combustion of gases, volatiles and supplemental coal.
  • the hot air passing through the internal passage of the refractory material is at 900-1000 ° C, and the temperature difference from the working surface of the lining refractory material causes a cooling effect, and the heat of the hot air is further brought back into the furnace.
  • the block coke after coking with high-temperature coking with the carbon-containing pellets forms a central conical column at the bottom of the column similar to the lower part of the blast furnace. This conical column is directly consumed by the infiltration process of the slag and molten iron.
  • the hot metal carburizing consumption and the continuous supplement of the upper part always exist, and the weight of the supporting material column floating in the slag and the molten iron, the tapered carbon material column at this time not only plays the role of skeleton, reducing agent and carburizing of molten iron, but also plays a role.
  • the fourth role the filtering effect, the solid slag is not reduced in the slag flowing through the second step reduction unit and the third step reduction unit for direct reduction of solid carbon, and the reduction behavior is for the third step reduction unit furnace
  • the composite carbon-containing pellet is the fourth tail-reduction after direct reduction of the core, indirect reduction of the outer layer and final reduction, and the recovery rate of the iron into the furnace is at a higher position.
  • the three cascade reduction units connected in series form an overall reduction cycle device, and the operation of the air flow enters the top inlet of the first reduction unit, and is output from the top outlet of the third step reduction unit, and the outlet air flow temperature is below 1100 ° C, and is imported.
  • the temperature of the airflow is 900-1000 ° C, and the temperature difference between the two is 100-200 ° C.
  • the temperature difference that naturally forms heat exchange is suitable for the condition. If the imported hot air needs to be increased by 1100 ° C or slightly higher, the hot air furnace of the heat exchange unit is idled with a set of gas burning equipment, which is activated at any time, and the air temperature in the hot air furnace is increased to adjust the temperature of the gas and the temperature of the heat storage material.
  • the airflow operating temperature below 1100 °C is that the carried dust will not cause condensation and clogging to block the pipeline and the inner chamber of the precipitator and the gate valve spool; the second is that the temperature is below the refractory temperature of any common refractory material, and the pipeline insulation material, There are no special requirements for hot blast furnace lining and heat storage materials.
  • the valve seat and valve core of the switching gate valve can be processed and manufactured with heat-resistant alloy material, and water cooling is not required to work in red hot state.
  • the high temperature gas and the high temperature hot air enter and exit a common pipe, an inlet and outlet, an upper furnace top collecting and dispersing cavity and a lower bottom collecting cavity and a heat storage material air flow passage. Similar to the respiration and the internal dust collecting action of the hot blast stove, the fly ash in the high-temperature airflow that escapes from the dust collector of the precipitator is brought back to the reduction unit system.
  • the theoretical combustion temperature of the blast furnace gas is only about 900 °C, and the upper temperature effect of the furnace at 1100 °C is required.
  • a heating and heat exchange furnace outside the combustion system is provided. That is, the accessory hot blast stove system outside the hot blast stove.

Abstract

一种梯级焙熔还原炼铁方法及整套能量密封循环系统设备，包括第一梯级还原单元(1)、第二梯级还原单元(2)、第三梯级还原单元(3)、热除尘器单元(4)、热风炉换热单元(5、6)、鼓风机单元(7)、煤及复合含碳球团干燥单元 (8)、高温燃气切换闸阀及保温管道系统(24)、换热废气切换闸阀及管道系统(27)、常温鼓风切换闸阀及管道系统(32)、高温热风切换闸阀及保温管道系统(35)；上一梯级单元剩余的能量流入下一梯级单元直接利用，使得入炉煤能量能最大程度自身循环利用。

Description

梯级焙熔还原炼铁方法及设备 技术领域
本发明涉及熔融还原炼铁领域。特别涉及一种双层结构的复合含碳球团焙熔还原炼铁的方法。
背景技术
本发明是在2007年本申请人提出的中国专利号200710065973.3《焙熔还原炼铁方法及装置与原料》专利技术的基础上发展的一种新的焙熔还原炼铁方法，同样以钢铁领域的炼铁能耗为背景技术。
近年来，随着社会发展的进程，人类大规模地消耗着大量的化石能源。对煤资源的消耗，钢铁领域仅次于火力发电。十年来全世界共生产不少于65亿吨生铁，用掉了不少于50亿吨的洗精炼焦煤，从地壳内部掏空不少于100亿吨炼焦煤原煤资源，向大气排放了不少于150亿吨二氧化碳温室气体。从源头减少钢铁生产的一次能源煤的消耗是很有必要的。
钢铁生产中，煤的消耗全部压在炼铁总工序。现在的大型高炉钢铁生产在结构上以小中型高炉生产只是一种复制放大，炼铁总工序包括焦化厂、烧结厂、球团厂和炼铁厂等四个厂，为回收多余的煤气加了一个小火力发电厂。生产环节链条越长，设备的可靠性、安全性、协调性越差。在能耗上，3000m3与5000m3的高炉区别甚小，相反料柱增高对下部的压力增大，对焦炭的质量要求更苛刻。鼓风阻力增加，鼓风电力消耗增加。高炉煤气热质低，用来发电只能掺烧30％，还要外加70％的煤粉，这实质上是以烧煤为主的小火力发电厂的概念，能量转化效率低是事实。焦化和烧结两个环节是耗热生产操作，并且造成了80～90％的全厂污染源。
炼一吨焦要消耗1.3～1.4吨干洗精炼焦煤，每吨烧结矿要加入50～65kg焦粉燃烧烧结。
几十年来，人们都在坚持不懈地研发各种非高炉炼铁技术，替代现有的高炉技术生产，作出了很大的技术积累和成果。
从能量守恒定理的观点出发，任何一种冶炼铁水的方法，首先应该是一个整体密封的系统，煤燃烧产生的化学能和热能完全自身循环利用。各种方法的比较前提是使用同一种原料、同一种燃料，得到的产品铁水和副产品熔渣带走的热量应该是一样的，只有比较废气出口的气体能量是唯一的方法。
高炉系统是一个开放的系统，能量的泄漏有焦化、烧结和煤气输出等三个环节，最后 才是热风炉的废气出口。所以高炉方法不能说是一种先进的方法。
现在运用和研发报导的各种炼铁方法中没有一种方法能够达到还原尾气能量的自身利用，都要处理多余煤气，掉入小火电低效率、高运行成本、而且联网难的尴尬处境。
所有炼铁方法从还原尾气出口处于还原设备的位置来看，只有两种，一种是在炉体的上部叫炉顶煤气出口，一种位于炉体下部叫高温燃气出口。上部出口溢出的煤气受炉子内部间接还原化学平衡气相的控制，CO的利用率不到55％，离开出口的炉顶煤气热风燃烧回热又只能再利用剩余能量的30～35％，再剩余的煤气没有发电利用的只能无用燃烧后排入大气；从还原设备下部出口溢出的高温燃气在炉体内部空间是为熔渣和铁水提供直接还原和熔化热耗，温度必须高于熔渣和铁水温度，否则熔体将降温。1450℃以上的气流直接除尘是不可能的，所携带的炉尘也是熔融状态微小珠粒，会马上粘结堵死输送管道和除尘器内部空间，再则热换热设备蓄热耐火材料也无法承受这么高的温度。
发明目的
本发明的目的是提供一种入炉煤能量能最大程度自身循环利用的炼铁方法；提供一种所述方法的能量自身密封循环系统整套专用设备。
发明内容
为了达到上述目的，本发明采用的技术措施是这样的：
第一是使用复合含碳球团为炉料。复合含碳球团的制作先形成含碳的铁氧化物球核，再用二次成球的方式形成铁氧化物原料的球团外层。
第二，类似于江河阶梯水力发电，上一梯级剩余的能量流入下梯级直接利用。在热风主气流流动的方向上无缝连接串联三个独立的还原设备单元，这三个串联的还原单元底部相通形成共同的渣水、铁水和气流通道与熔体储存公共空间。同时三个还原单元相对独立，各自有单独的进料系统，各自完成各自的还原、熔化作业负载配额。以主气流流动方向分为第一梯级还原单位、第二梯级还原单元和第三梯级还原单元。在第三梯级还原单元的炉顶还原尾气出口直接连接热除尘器单元，热除尘器单元下部炉尘排出口与炉尘返回通道相连接第二梯级还原单元上部内部空间，除尘器单元上部高温除尘尾气出口通过保温管道和受控闸阀系统与热风炉换热单元高温换热燃气进口相连接。热风炉换热单元的热风出口再通过保温管道和受控闸阀系统与第一梯级还原单元炉顶热风进口相连接。第一梯级还原单元、第二梯级还原单元、第三梯级还原单元、热除尘器单元和热风炉顶换热单元等五个单元首尾相衔无缝密封连接首先形成一个圆环形状密封循环系统；热风炉换热单元的常温空气进口与鼓风机单元通过切换闸阀和管道相连接，换热废气出口再通过切换闸阀和管道与 煤及复合含碳球团烘干单元直接相连接，这样以热风炉换热单元为结点，七个单元再次形成领带形状无缝连接成整套能量密封循环系统设备。这个整套能量密封循环系统设备物料进口可以有多个，出口只有位于第一梯级还原单元下部的渣口、铁水口两个产品出口和位于烘干单元的烘干废气出口等三个出口。换热废气直接用于物料烘干，把还原单元炉内的物料干燥过程移到炉外，进行了热量的最后再次利用，炉料可以现烘热装，把所含热量再次带回系统。
第三是炉料加料的方法，复合含碳球团作为炉料的入炉方式，分为三路加入三个梯级还原单元，按各自负载分配两头为主中间为辅：一路与煤和熔剂等材料按所需比例混合由第一还原单元的上部受料斗、密封加料罐和下料管进入该还原单元的炉腔料柱顶部；另一路是单一的复合含碳球团炉料，由第三梯级还原单元的上部受料斗、密封加料罐和下料管进入该还原的炉腔料柱顶部；第三路是与少量配额作为调节炉料由第二梯级还原单元上部调温炉料进口进该单元炉腔。热除尘单元收集的高温炉尘和石灰粉通过气流输送进入第二梯级还原单元的炉腔空间。第二梯级还原单元渣中FeO的还原剂及渗碳所需的煤粉由气流输送或者螺旋输送的方式由第三梯级还原单元下部进入公共底部铁水中。
第四是主气流运行的方式，常温空气经鼓风单元压缩驱动，贯穿所述第二项技术措施七个单元形成的整套能量密封循环系统，一般气流运行到底，从煤及复合含碳球团单元烘干废气出口排出。三个梯级还原单元底部无缝连接串联后可以看作为一个整体还原单元，有别于现有技术的是热风进口和还原尾气出口都在炉顶，主气流在外观上看炉顶进炉顶出，在内部流经三个不同的还原区域。第三梯级还原单元的熔化、还原吸热和预热吸热截留利用了气流中1500℃-1100℃区间的热量。从第三梯级还原单元炉顶出口排出的还原尾气温度适合热除尘和热交换的要求。如果还原尾气中还有少量剩余CO，另一座热风炉的热风可分流少量部分通入该座热风炉炉顶扫尾燃烧或者叫完全燃烧。
第五是各单元热量和温度调节方式，除热除尘器单元，其余各单元可以单独设置固体燃料或气体燃料的小型燃烧装置，燃烧的高温燃气直接喷入炉内进行各单元热量和温度的精准调节和热量补充调节。
另外一种调节温度措施是在第二梯级还原单元的炉顶设置调温炉料加入口，当该单元炉腔温度高于1550℃时投入少量复合含碳球团直接参与还原熔化吸热，将温度控制在1450℃～1500℃。
说明书附图说明及表格说明
图1是本发明整套能量密封循环系统专用设备简图，也是说明书附图及摘要附图。
图2是本发明具体实施例的整套能量密封循环系统气流运行流程示意图。所标单位体积m3为标准体积m3(0℃，760毫米汞柱)。在图中(1)、(2)、(3)梯级还原单元的入炉物料已在表4中示出，所以用空箭头表示。
表1是图1引用标记所标识的特征序列表格。
表2是实施例所使用的铁矿粉和煤的组份及化学成分表。
表3是复合含碳球团造球配料表。
表4是三梯级还原单元入炉料加料表。
表5是实施例每吨铁水物料平衡表。
表6是实施例造渣组分来源表。
表7是实施例三梯级还原单元的热平衡表。
图1所示的专用设备，由(1)(2)(3)(4)(5)(6)(7)(8)等8个独立单元顺流串联无缝连接，其中(5)(6)两单元是一个联合体单元，实质只有7个单元。每个单元有各自的功能体系，包括工作部件、动力系统、操作控制系统和执行机构，在图1中都没有示出，包括在各个单元之内。
图1所示简图中(5)和(6)双联热风炉换热单元，可以根据需要拓展为三联或者四联结构，效果为等同，简图中不再示出。
与现有技术比较
在现有冶炼铁水的技术领域中，传统高炉技术发展到极限完善节能发展空间已经不大。熔融还原技术是高炉技术的唯一替代技术。本发明对前者来说是改造，对于后者而言是继承发扬。
1.高炉技术使用煤是从焦化厂开始，烧结厂用焦粉、球团厂用燃气、炼铁厂用焦块和喷吹煤粉，后面又拖出一个低效率的小火力发电厂，任何一个配套厂都要耗能。本发明集焦化、烧结、球团和炼铁等工序为一道工序在一套能量密封循环的设备中完成作业，能量顺流梯级利用。煤从加入球团内部开始，入炉后与其它用途的煤一起焦化析出挥发分，挥发分的燃烧和还原产物气体中CO的二次燃烧支撑补充还原、熔化热量需求。
2.现有传统高炉炼铁技术，本发明对其改造成本低和生产运行成本低。
3.熔融还原技术的初衷是用321.4kg碳冶炼1吨铁，加上每吨铁水渗碳43kg碳：321.4+43＝364.4kgC，按固定碳80％的煤参与还原熔分和渗碳：364.4÷0.8＝455.5kg煤，这就是现在研发中熔融还原技术的最低用煤极限。本发明可以达到和突破熔融还原技术的最低煤耗。
具体实施例
以下本发明以具体实施例作进一步说明
实施例使用的铁矿粉和煤组分及化学成分如表2
表2
Figure PCTCN2016000406-appb-000001
该实施例该批量铁矿粉含铁品位为58.270％。每吨铁需要铁矿粉1716kg。
球核料与外层料中的铁矿石中铁量分配比例为50％对50％，但是考虑球核与外层的接触界面球核表面的碳颗粒也会对内外层界面外层的铁氧化物产生直接还原作用，把外层界面附近一部分铁矿粉划入球核份额。实施例中配料为45％对55％。另外也可以外层铁矿粉使用含铁品位稍低的铁矿粉增加球团外层料的厚度，从而增加球核产物气体在外层扩散的路程和间接还原的时间，同时也增加还原结束时金属球团的再氧化抵抗能力。
该批量煤的固定碳不足80％，为79.120％，球核配碳量按固定碳计算，320kg碳/吨铁量配入，球核铁量还是50％份额计算配碳量，铁矿粉实际配入总份额45％。第一梯级还原单元使用的复合含碳球团和第三梯级还原单元使用的复合含碳球团的球核配碳量可以不同，后者加配一定过剩量，以利于还原结束后产物铁的渗碳，增加流动性。
表3为实施例两种复合含碳球团球核和外层配料表。
复合含碳球团的造球采用成球盘造球，可以采用在第一台成球机上造成球核，滚入第二台造球机成球盘内同时给入外层料二次成球工艺。也可以在一台成球机上完成，这台成球机的成球盘是可调角度和翻倾的，成球盘角度调到球粒不滚出盘外。给入球核料形成球核，再给入外层料完成二次成球形成球体外层，然后断水干滚，使复合含碳球团进入造球坚强期，同时加入少量干料粉调节水份保持水份8～10％。坚强期结束，翻倾成球盘一次性卸出成品球料，由皮带机运走。球盘复位进行下一周期作业。实践证明该方法配料精确、水份容易控制，球体强度高于前者和一般普通球团，完全达到转运和入炉条件的要求。
该批量煤挥发份为9.926％，挥发分中可燃基C挥、H和S分别为3.856％、3.323％和0.503％是计算挥发分热值的依据。每kg煤的挥发分热值为6.035MJ，需要1.228m3空气助 燃；煤中灰分为10.660％，灰分中SiO2、CaO份额并入矿石计算CaO加入量调节渣酸碱度。
复合含碳球团的入炉方式是这样的，按照份额分为三份，第一份与煤和溶剂按所需比例混合后由第一还原单元的加料斗(10)、密封加料串联罐(11)、预热下料管(12)进入该单元填充床料柱顶部；第二份是单一复合含碳球团经第三梯级还原单元的加料受料斗(16)、密封加料串联罐(17)、下料管(18)进入该还原单元的填充床料柱顶部；第三份是少量数量的调节温度份额由第二梯级还原单元的调温复合含碳球团炉料进口(38)进入该单元炉内空间，如果适合情况下，第三份可以不使用。
常温空气经鼓风机单元(7)压缩后，由常温鼓风切换闸阀及管道系统(2)切换操作分时间段由热风炉换热单元(5)和(6)的鼓风常温空气进口(33)和(34)该单元下部空间，由下而上对流带走蓄热耐材的热量。换热后的鼓风温度上升到900℃左右，由(5)和(6)的上部的高温燃气进口及热风出口共用口(25)和(26)经高温热风切换闸阀及保温管道系统(35)到第一梯级还原单元(1)炉顶的高温空气进口(9)进入该单元的料柱顶部以上炉内空间，在该单元料柱顶部以上空间，高温热风空气分流为一路气流和两路分气流。主气流与炉料同向而下，预热炉料并燃烧该单元(1)所有入炉煤焦化产生的挥发分和复合含碳球团还原产物气体中剩余的CO气体以及补充燃料粒煤，提供反应吸热和熔化渣、铁的所需热量，形成的高温燃气携带剩余热量直接进入第二还原单元(2)的底部，与分流的第二路热风汇合再次燃烧本还原单元(2)加入铁水中的煤粉直接还原熔渣中氧化铁的产物气体和挥发分，扣除该还原单元(2)所需热耗贯穿底部空间直接进入第三梯级还原单元(3)的炉底通道，逆流而上提供该单元熔化热耗，又再一次与第三路分流热风汇合完全燃烧复合含碳球团产物气体中的剩余CO气体和球团球核中煤焦化折出的挥发分。最后的还原尾气是低于1100℃完全燃烧的高温燃气，从第三梯级还原单元(3)炉顶还原尾气出口溢出的高温燃气直接进入热除尘器单元(4)的内部，除尘后的高温燃气由除尘高温燃气出口(23)通过高温燃气切换闸阀及保温管道系统(24)与热风错开时段，由热风炉换热单元(5)和(6)的高温燃气进口及换热高温空气出口共用口(25)和(26)进入热风炉内部，加热热风炉内部蓄热材料后的换热废气温度降到300℃以下，由热风炉换热单元(5)和(6)的换热废气出口(28)和(29)通过换热废气切换闸阀及管道系统(27)直接进入煤及复合含碳球团干燥单元(8)的换热废气进口(30)，用于干燥作用的干燥废气温度再次降到100℃以下，携同样温度的水蒸汽再次除尘后排入大气环境，到这里整个入炉煤的能量密封循环利用过程全部完成。
在表4入炉料加料表中，第二梯级还原单位没有加入复合含碳球团是两端还原单元处 于平衡和适合状态，生产中出现偏差时再精准调节。本发明使用的复合含碳球团是酸性炉料，脉石熔化温度高，在第三梯级还原单元的料柱下部起一定的骨架作用和增长还原温度区间作用，还有增加透气作用和对金属球团保护和抗再氧化作用。第二梯级还原单元的三物料进口共用口(14)加入的石灰粉由高温炉气加热携带输入第三梯级还原单元料柱底部与未熔化的最底层球团接触，CaO和球团脉石中SiO2都处于临近各自熔化温度，矿化作用迅速熔化金属球团形成液相。
本发明入炉煤的还原剂作用由三部分构成，复合含碳球团内部固定碳与铁氧化的直接还原和间接还原、熔化后熔渣流经固体碳块粒时的直接还原和渣金界面铁水中碳与渣中FeO的熔融还原。其中固体碳直接还原只发生在第一梯级还原单元。入炉煤的供热作用也由三个途径构成，第一是包括加入球团球核的配碳煤、渗碳煤和直接还原耗碳煤等全部入炉煤受热焦化产生的挥发分的燃烧，第二是还原反应的产物气体中CO的二次燃烧，第三是直接对补充热量入炉煤的燃烧。这三种燃烧对于本发明是在供氧充足的完全燃烧。
本发明三梯级焙熔还原技术第一梯级还原单元是入炉煤能量密封循环的起点和源头，从表4表明，总量70％的煤从第一梯级还原单元加入，除供应本单元热支出后，剩余能量向下一梯级还原单元流动。第一梯级还原单元的复合含碳球团及煤是和石灰一起加入形成中性炉料，炉渣熔点在1250℃左右，加之铁水渗碳饱合1250℃时流动性也很好，1300℃的炉气温度是比较适合的。第二梯级还原单元的输出燃气温度为1472℃，既在耐火材料承受温度范围，对第三梯级还原单元底部的金属球团溶化后气、渣、铁水温度还有1400℃，这对下是渣铁逆流对前单元热支出的热量反回流，对上是支撑复合含碳球团球核直接还原吸热和升温热。在1350℃时，有试验资料表明还原时间不超过5min。复合含碳球团在炉内从预热、还原和熔化的时间越短说明料柱的需要高度越小，既而对料柱的下部软融层压力降低，对鼓风阻力的也降低。
高温烟气熔化还原结束的复合含碳球团形成的金属球团的过程是关心和关注焙熔还原技术的人们所担心的问题，担心生成的金属铁会被二氧化碳再氧化为氧化铁。二氧化碳对熔融状态铁和铁水的氧化势与纯氧相比相差很大。在现代钢结构制造业中大量使用一种成熟的技术叫“二氧化碳气体保护焊”的焊接工艺。高浓度的二氧化碳气体直接喷吹在焊缝高温铁水周围，隔开空气保护铁水不与空气中氧气的接触，如果发生CO2和铁水的氧化又如何保证焊缝质量。本发明人在制造焙熔还原工厂的炉体结构时采用的也是二氧化碳气体保护自动焊接技术。这是一个最直接最普遍的实践佐证。再一个是高温烟气中占原空气体积分数的79％的N2仍留在其中，烟气中CO2的浓度与保护焊中使用的CO2气体浓度的差 别是类似纯氧与空气的差别，空气是不可能替代纯氧当做切割钢板的氧化剂，氮气阻挡氧化的作用是不能忽视的。还有一个保护效果是本发明中第二梯级还原单元加入的20kg炉尘/吨铁水和44kg石灰粉/吨铁水的粉尘物料由高温烟气携带进入复合含碳球团料柱底部对熔融铁和铁水进行表面覆盖与屏蔽，方法如同高炉出铁场用干渣覆盖在铁水沟中的铁水表面，隔绝空气中氧对铁水表面的氧化。焙熔还原的核心技术是采用复合含碳球团为炉料类似氧化球团的焙烧、在氧化气氛中焙烧还原、还原结束球团就地随即熔化进入终还原区域，所以命名为焙熔还原。在还原阶段，产物气体在球团内部压力指向的驱动下向球团表面强制迁移行为和球团外层阻碍保护作用，阻止了环境气相中的氧化气体进入球团内部，所以本发明第三梯级还原单元的分流高温空气进口(19)和(20)布置在料柱还原带位置。还原结束，三个方面的因素综合结果使熔化过程时间较短。一方面还原吸热停止球团温度很快上升到熔化温度，二方面是石灰粉的喷入造渣热的直接作用升温补充对冲熔化热，第三方面是熔渣组分CaO和SiO2的酸碱中和作用由各自的高熔点自行改变为中性炉渣的低熔点。溶化后，液态熔体快速滴落或流入下部公共熔体储存空间，渣在上，铁水在下，产物铁的再氧化很难发生。本发明层层技术措施保障了熔化阶段的可靠进行与顺行。从热力学讲，直接还原中，FeO+CO＝Fe+CO2——(6)，CO2+C＝2CO——(2)，Fe+CO2＝FeO+CO——(8)，反应式(6)和反应式(8)是一对可逆反应。再氧化反应式(8)会发生。焙熔还原技术对于科学的特殊贡献在于如下解释：直接还原反应式(6)和(2)是发生在复合含碳球团的内部密封环境，产物气体靠自身压力向外排是一种没有反应动力学限制的自发气固反应。反应式(8)是处于外部气相环境中气相和液相表面之间的反应。反应式(8)的反应速率受控于反应动力学限制环节。反应式(6)和反应式(8)对于本发明被分隔在两个不同的区域。再一个特征是留给反应式(8)的反应时间只是反应式(6)的几十分之一，反应产物的产量是正比于反应速度和时间，本发明有理由不考虑高温烟气对铁水的轻微再氧化作用的影响，如同炼钢转炉倾倒钢水时可以不考虑空气对钢水的再氧化。
第二梯级还原单元可以是一个反射炉结构，从表3热平衡中示出第二梯级还原单元的热支出本身消耗为0.456GJ，占热收入3.31GJ的13.776％，在反射炉热效率(15～30％)覆盖之内。这也是本发明实施例的可行保障。渣层的厚度本发明采用薄渣层操作，即减少渣中氧化铁向渣金界面迁移的路程又减少热量传递的热阻。
本发明的第一还原单元的炉体可以看作是一个燃煤的竖炉，炉料与气流同向，两者运动速度的差异较大，实质上还是相对对流传热。热空气一部分从料柱顶面向下强制流动，一部分通过炉衬耐火材料内部垂直通道和横向通道从不同位置向内周围侧吹，保障还原产 物气体、挥发份和补充煤的完全燃烧。穿过耐火材料内部通道的热空气在900～1000℃，相对炉衬耐火材料的工作面温差造成冷却作用，又把热空气再升温的热量反带回炉内。随复合含碳球团加入的块煤在高温焦化后的块状焦炭，在料柱底部形成类似高炉下部的中心锥形呆料柱，这个锥形料柱随渣、铁水渗透过程的直接还原消耗铁水渗碳消耗和上部的不断补充始终存在，浮在渣、铁水中支承料柱的重量，此时的锥形炭料柱不仅起到骨架作用、还原剂作用和铁水渗碳作用，还起到第四种作用：过滤作用，对第二梯级还原单元和第三梯级还原单元流过的渣中还没还原干净FeO截留进行固体碳直接还原，这次的还原行为对于第三梯级还原单元炉中的复合含碳球团而言是球核直接还原、外层间接还原和终还原后的第四次扫尾还原，保障入炉铁的回收率在一个较高的位置。
本发明串联的三个梯级还原单元形成一个整体还原循环装置，气流的运行，以第一还原单元炉顶进口进入，从第三梯级还原单元炉顶出口输出，出口气流温度在1100℃以下，进口气流温900～1000℃，两者温差100～200℃，自然形成换热的温差适合条件。如果进口热风需要提高1100℃或者略高，换热单元的热风炉各闲置一套气体燃烧设备，随时启用，在热风炉膛内混风提高燃气温度及蓄热材料温度进行调节。1100℃以下的气流运行温度，是携带的灰尘不会造成凝结粘结堵塞管道和除尘器内腔及闸阀阀芯；二是此温度在任何普通耐火材料的耐火温之下，对管道保温材料、热风炉炉衬及蓄热材料无特殊要求；三是切换闸阀的阀座和阀芯可以考虑用耐热合金材料加工制造，不设水冷在红热状态下工作。热风炉换热单元中高温燃气和高温热风空气的进出共用一截管道、一个进出口、一个上部炉顶集散空腔和下部炉底集散空腔以及蓄热材料气流通道。类似呼吸作用和热风炉内部集尘作用，把逃逸出除尘器除尘单元的高温气流中的飞灰重新带回还原单元系统。
比较传统高炉的换热回热，高炉煤气的理论燃烧温度只有900℃左右，要达到1100℃的炉内上部温度效果，比本发明多出一套煤气和助燃空气的加热换热炉外燃烧系统，也就是热风炉外的附属热风炉系统。
表1
Figure PCTCN2016000406-appb-000002
表3
Figure PCTCN2016000406-appb-000003
表4
Figure PCTCN2016000406-appb-000004
表5
Figure PCTCN2016000406-appb-000005
表6
Figure PCTCN2016000406-appb-000006
表7三梯级还原单元热平衡
Figure PCTCN2016000406-appb-000007

Claims (6)

  1. 一种以煤为燃料和还原剂、以复合含碳球团为炉料的焙熔还原炼铁方法，其特征在于：
    [1]用复合含碳球团作为炉料；
    [2]用煤作为燃料和还原剂；
    [3]类似江河梯级水力发电，上一梯级单元剩余的能量流入下一梯级单元直接利用，由鼓风机单元——热风炉换热单元——第一梯级还原单元——第二梯级还原单元——第三梯级还原单元——热除尘器单元——热风炉换热单元——煤及复合含碳球团烘干单元等七个单元无缝连接形成一个整套能量密封循环运行系统；
    [4]复合含碳球团的入炉方式分为三路，一路与煤和溶剂按所需比例混合后经第一级还原单元的受料斗、密封加料串联罐和炉顶内部下料管进入该还原单元填充床料柱顶部，第二路是单一复合含碳球团经第三梯级还原单元的受料斗、密封加料串联罐和炉顶内部下料管进入该还原单元填充床料柱顶部，第三路以少量数量单一复合含碳球团作为调节温度作用由第二梯级还原单元的炉顶密封加料装置进入该还原单元炉内空间；
    [5]从热风炉换热单元热风出口出来的热风，经热风保温管道和热风切换闸阀引到第一还原单元分流为一路主要气流和两路分流气流，主气流由第一梯级还原单元炉顶进气口进入炉内，与炉料同向而下，预热炉料并燃烧该单元所有入炉煤焦化产生的挥发分和复合含碳球团还原产物气体中剩余的CO气体以及补充燃料粒煤，提供反应吸热和熔化渣、铁的所需热量，形成的高温燃气携带剩余热量直接进入第二级还原单元底部，与分流的第二路热风汇合再次燃烧本单元加入铁水中的煤粉直接还原熔渣中氧化铁的产物气体和挥发分，扣除该还原单元所需热耗贯穿底部空间直接进入第三级还原单元炉底通道，逆流而上提供该单元熔化热耗，又再一次与第三路分流热风汇合完全燃烧复合含碳球团产物气体中的剩余CO气体和球团球核中煤焦化折出的挥发分，最后的还原尾气以低于1100℃的温度从第三梯级还原单元的炉顶还原尾气出口排出直接进入热除尘器单元除尘后通过保温管道和热风切换闸阀流入热风炉换热单元与鼓风机鼓入的常温空气交换热量，从热风炉底部出口排出的换热废气还具有300℃以下温度，直接进入煤及复合含碳球团烘干单元用于干燥后的干燥废气和水蒸汽温度都在100℃以下，再次除尘后排入大气环境，从而完成整个入炉煤能量密封循环利用过程。
  2. 一种权利要求1所述梯级焙熔还原炼铁方法的专用整套能量密封循环系统设备，包括第一梯级还原单元(1)、第二梯级还原单元(2)、第三梯级还原单元(3)、热除尘器单元(4)、热风炉换热单元(5)和(6)、鼓风机单元(7)、煤及复合含碳球团干燥单元 (8)、高温燃气切换闸阀及保温管道系统(24)、换热废气切换闸阀及管道系统(27)、常温鼓风切换闸阀及管道系统(32)、高温热风切换闸阀及保温管道系统(35)其特征在于：
    A.所述第一梯级还原单元(1)具有：高温空气进口(9)、高温空气分流出口(13)、燃料和复合含碳球团及溶剂加料受料斗(10)、密封加料串联罐(11)、预热下料管(12)、渣出口(36)、铁水出口(37)；
    B.所述第二梯级还原单元(2)具有：分流高温空气进口及石灰粉和炉尘进口(14)、分流高温空气流调节阀(15)、调温复合含碳球团炉料进口(38)；
    C.所述第三梯级还原单元(3)具有：复合含碳球团加料受料斗(16)、密封加料串联罐(17)、下料管(18)、分流高温空气进口(19)和(20)、输入铁水中煤粉进口(21)；
    D.所述热除尘器单元(4)具有：炉尘排出口(22)、除尘高温燃气出口(23)；
    E.所述热风炉换热单元(5)和(6)具有：高温燃气进口及换热高温空气出口共用口(25)和(26)、换热废气出口(28)和(29)、鼓风常温空气进口(33)和(34)；
    F.所述煤及复合含碳球团烘干单元(8)具有：换热废气进口(30)、干燥废气和水蒸汽出口(31)。
  3. 根据权利要求2所述专用整套能量密封循环系统设备，其特征在于：所述第一梯级还原单元(1)、所述第二梯级还原单元(2)和所述第三梯级还原单元(3)沿主气流方向底部相通串联无缝连接。
  4. 根据权利要求2所述专用整套能量密封循环系统设备，其特征在于：所述热除尘器单元(4)高温燃气进口与所述第三梯级还原单元(3)上部高温还原尾气出口无缝连接，除尘高温燃气出口(23)通过所述高温燃气切换闸阀及保温管道系统(24)与所述热风炉换热单元高温气流进出共用口(25)和(26)无缝连接。
  5. 根据权利要求2所述专用整套能量密封循环系统设备，其特征在于：所述煤及复合含碳球团干燥单元换热废气进口(30)通过所述换热废气切换闸阀及保温管道系统(27)与所述热风炉换热单元(5)和(6)的换热废气出口(28)和(29)无缝连接。
  6. 根据权利要求2所述专用整套能量密封循环系统设备，其特征在于：所述热风炉换热单元(5)和(6)常温空气进口(33)和(34)通过所述常温鼓风切换闸阀及管道系统(32)与鼓风机(7)无缝连接，热风出口(25)和(26)通过切换闸阀及保温管道系统(35)与所述第一还原单元(1)上部高温空气进口(9)无缝连接。
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