KR102104555B1 - Apparatus for reducing emission of carbon dioxide, method for reducing emission of carbon dioxide and manufacturing apparatus of molten iron - Google Patents

Abstract

A carbon dioxide supply unit that supplies carbon dioxide by treating flue gas generated in the molten iron manufacturing process; A slag supply unit for crushing and drying molten slag containing calcium oxide and magnesium oxide to supply the crushed slag; A slag hydration unit for hydrating the crushed slag by reaction with a reaction gas containing steam to supply hydrated slag; And a slag carbonization unit for carbonizing the hydrated slag by reacting the hydrated slag with the carbon dioxide.

Description

Carbon dioxide emission reduction device, carbon dioxide emission reduction method and molten iron manufacturing device {APPARATUS FOR REDUCING EMISSION OF CARBON DIOXIDE, METHOD FOR REDUCING EMISSION OF CARBON DIOXIDE AND MANUFACTURING APPARATUS OF MOLTEN IRON}

The present invention relates to a carbon dioxide emission reduction device, a carbon dioxide emission reduction method, and a molten iron manufacturing device. More specifically, the present invention relates to a carbon dioxide emission reduction device, a carbon dioxide emission reduction method, and a molten iron manufacturing device capable of reducing the amount of carbon dioxide emitted to the atmosphere by combining carbon dioxide with slag from exhaust gas generated in the molten iron manufacturing process.

Currently, about 60% of the world's iron production is produced from the blast furnace method developed since the 14th century. The blast furnace method is a method of manufacturing molten iron by reducing iron ore to iron by adding coke, etc., made from iron ore and bituminous coal, which have undergone sintering, into a blast furnace and blowing oxygen. As described above, the blast furnace method, which forms a large part of the molten iron production facility, requires a raw material having a strength of a certain level or higher and a particle size capable of ensuring air permeability in the furnace. As described above, a carbon source used as a fuel and a reducing agent Furnace depends on coke processed with specific raw coal, and iron source mainly depends on sintered ore which has undergone a series of bulking processes.

Accordingly, in the current blast furnace method, raw material preliminary treatment facilities such as coke production facilities and sintering facilities are necessarily involved, so it is not only necessary to construct auxiliary facilities other than the blast furnace, but also the environment for various environmental pollutants generated in the auxiliary facilities. Due to the need to install pollution prevention equipment, there is a problem in that the manufacturing cost increases rapidly due to the large investment cost. In order to fundamentally solve the above problems of the blast furnace method using coke and sintered ore, steel mills around the world directly use ordinary coal as fuel and reducing agent, and as a source of iron, spectroscopy that occupies more than 80% of the world's ore production Many efforts have been made to develop a molten reduced iron manufacturing method for directly manufacturing molten iron.

The molten-reduction steel method can solve many of the problems of the blast furnace method in terms of raw materials and environment, but it is still relatively inferior to the existing blast furnace method in terms of technical maturity, energy efficiency, and production capacity, so continuous process and facility technology improvement need.

Molten-reduction iron process also uses coal as fuel, so it emits a large amount of CO ₂ in the molten iron manufacturing process, and has a high CO ₂ emission unit due to the high unit of fuel use due to low process efficiency compared to the blast furnace process. Due to global warming, a global environmental issue, the steel industry is under intense pressure to reduce CO ₂ emissions. In the near future, not only will the economic loss increase due to the regulation of CO ₂ emissions increase, but also the problem of the existence of some molten iron manufacturing facilities. It is expected to emerge. Therefore, in order to survive the above-mentioned molten reduced iron manufacturing process, not only a reduction in coal consumption by process improvement, but also a more aggressive means of reducing CO ₂ is required.

On the other hand, the molten-reduction steel process configured as described above uses pure oxygen, and furthermore, a CO ₂ removal device is already configured in the process, from which a gas containing a high concentration of CO _2, that is, tail gas is generated. Tail gas is currently mixed with flue gas from other places in the process and supplied as a by-product to a post-process of power plants.

The present invention provides a carbon dioxide emission reduction device, a carbon dioxide emission reduction method, and a molten iron manufacturing device capable of reducing the amount of carbon dioxide emitted to the atmosphere by combining carbon dioxide with slag from exhaust gas generated in the molten iron manufacturing process.

Carbon dioxide emission reduction apparatus according to an embodiment of the present invention is a carbon dioxide supply unit for supplying carbon dioxide by treating the exhaust gas generated in the molten iron manufacturing process; A slag supply unit for crushing and drying molten slag containing calcium oxide and magnesium oxide to supply the crushed slag; A slag hydration unit for hydrating the crushed slag by reaction with a reaction gas containing steam to supply hydrated slag; And a slag carbonation unit for carbonizing the hydrated slag by reacting the hydrated slag with the carbon dioxide.

The carbon dioxide supply unit may include a liquefier that liquefies carbon dioxide in the tail gas by cooling the tail gas separated from the exhaust gas; A gas-liquid separator that separates the liquid carbon dioxide from the tail gas and discharges residual gas to the outside; A vaporizer for vaporizing the liquid carbon dioxide; And a carbon dioxide feeder supplying the gaseous carbon dioxide to the slag carbonation unit.

The carbon dioxide supply unit includes a dryer that removes moisture in the tail gas supplied from the gas separator; A compressor for compressing the tail gas from which the moisture has been removed; And a filter for filtering the compressed tail gas. And a first heat exchanger that supplies heat from the filtered tail gas to the residual gas discharged to the outside, and supplies the filtered tail gas to the liquefier.

The carbon dioxide supply unit may include a rectifier rectifying the liquid carbon dioxide supplied from the gas-liquid separator; And a reservoir in which the rectified liquid carbon dioxide is stored and supplies the liquid carbon dioxide to the vaporizer.

The slag supply unit includes a converter that converts and supplies molten slag generated in the molten iron manufacturing process to cooling slag; A first hopper in which the cooling slag is stored; A crusher for crushing the cooling slag supplied from the first hopper; A classifier for sorting the crushed slag having a certain particle size or less from the crushed slag; A slag dryer for drying the selected crushed slag; And a transfer line supplying the dried crushed slag to the slag hydration unit.

The slag hydration unit comprises: a first reactor in which hydrated slag is generated by reaction of the crushed slag and a reaction gas containing steam; A second hopper for quantitatively discharging the crushed slag into the first reactor; "I may include a; reaction gas line for supplying the reaction gas to the first reactor.

The slag hydration unit includes a second heat exchanger that recovers waste heat from exhaust gas discharged from the first reactor; A heat circulation line communicating the second heat exchanger with the reaction gas line to transfer heat supplied from the second heat exchanger to the reaction gas line; And an exhaust gas cleaner for cooling and cleaning the exhaust gas.

The slag carbonation unit includes a second reactor in which carbonation slag is generated by reaction of the hydrated slag and the carbon dioxide; A supply line connected to the first reactor and moving the hydrated slag to the second reactor; And a carbon dioxide line through which the carbon dioxide is supplied to the second reactor.

The slag carbonation unit includes a collector for collecting steam and unused carbon dioxide generated from the second reactor; And a steam circulation line connecting the collector and the reaction gas line to deliver the steam supplied from the collector to the reaction gas line.

The slag carbonation unit comprises: a carbon dioxide cleaner for cleaning the unused carbon dioxide; And a carbon dioxide circulation line connecting the carbon dioxide scrubber and the carbon dioxide line to deliver the unused carbon dioxide supplied from the carbon dioxide scrubber to the carbon dioxide line.

The slag carbonation unit may further include an on-off valve installed on the supply line, and the second reactor may be located below the first reactor.

Carbon dioxide emission reduction method according to an embodiment of the present invention comprises the steps of producing carbon dioxide by treating the exhaust gas generated in the molten iron manufacturing process; Crushing and drying the molten slag containing calcium oxide and magnesium oxide to prepare a crushed slag; Preparing the hydrated slag by hydrating the crushed slag by reaction with a reaction gas containing steam; And preparing the carbonated slag by reacting the hydrated slag with the carbon dioxide.

The manufacturing of the crushed slag may include converting molten slag generated in the molten iron manufacturing process into cooling slag; Crushing the cooling slag; Separating the crushed slag having a particle size of 8 mm or less from the crushed slag; And drying the selected crushed slag.

The step of manufacturing the crushed slag, after the step of sorting the crushed slag, crushing slag having a particle size exceeding 8 mm may be further crushed together with the cooling slag.

In the step of preparing the hydrated slag, a reaction including the following Reaction Scheme 1 and Reaction Scheme 2 may be performed in a first reactor having a space therein.

[Scheme 1] CaO + H ₂ O = Ca (OH) ₂

[Scheme 2] MgO + H ₂ O = Mg (OH) ₂

The first reactor is composed of a flow path, the gas hole tip speed in the flow path is 0.6 to 0.8m / sec, and the residence time of the crushed slag in the flow path may be 50 to 70 minutes.

The pressure in the first reactor may be 3 to 4 atmospheres.

The steam (H ₂ O) supplied to the first reactor for calcium oxide (CaO) in the crushed slag may be in a molar ratio (CaO: H ₂ O), and may be 1: 4 to 1: 5.

In the step of preparing the carbonation slag, a reaction including the following Reaction Scheme 3 and Reaction Scheme 4 may be performed in a second reactor having a space therein.

[Scheme 3] Ca (OH) ₂ + CO ₂ = CaCO ₃ + H ₂ O

[Reaction Scheme 4] Mg (OH) ₂ + CO ₂ = MgCO ₃ + H ₂ O

The second reactor is composed of a flow path, the gas tip velocity in the flow path is 0.6 to 0.8m / sec, and the residence time of the hydrated slag in the flow path may be 50 to 70 minutes.

The pressure in the second reactor may be 3.2 to 4.4 atmospheres.

Carbon dioxide (CO ₂ ) supplied to the second reactor relative to the sum of calcium oxide (CaO) and calcium hydroxide (Ca (OH) ₂ ) in the hydrated slag is a molar ratio (CaO + Ca (OH) ₂ : CO ₂ ), 1: 4 to 1: 5.

An apparatus for manufacturing molten iron according to an embodiment of the present invention includes a molten gasification furnace in which molten iron and carbon materials are charged to manufacture molten iron; A flow reduction furnace for supplying reduced iron produced using the reducing gas discharged from the molten gasifier to the molten gasifier; A gas separation unit separating tail gas from exhaust gas discharged from the flow reduction furnace; A carbon dioxide supply unit that extracts and supplies carbon dioxide from the tail gas discharged from the gas separation unit; A slag supply unit for crushing and drying molten slag including calcium oxide and magnesium oxide discharged from the molten gasifier to supply crushed slag; A slag hydration unit that supplies the hydrated slag by hydrating the crushed slag; And a slag carbonation unit for carbonizing the hydrated slag by reacting the hydrated slag with the carbon dioxide.

According to the carbon dioxide emission reduction apparatus according to an embodiment of the present invention, carbon dioxide emitted from the exhaust gas generated in the molten iron manufacturing process may be combined with slag to reduce the amount of carbon dioxide emitted to the atmosphere.

Accordingly, it is possible to respond flexibly to the regulation of carbon dioxide emission, which is expected to be strongly imposed on the steel industry in the future, and economical operation is also possible under these regulations.

1 is a view showing a carbon dioxide emission reduction apparatus and molten iron manufacturing apparatus according to an embodiment of the present invention.
2 is a view showing a carbon dioxide supply unit of the carbon dioxide emission reduction site according to an embodiment of the present invention.
3 is a view showing a slag supply unit of the carbon dioxide emission reduction device according to an embodiment of the present invention.
4 is a view showing a slag hydration unit and a slag carbonation unit of the carbon dioxide emission reduction device according to an embodiment of the present invention.
5 is a view showing a block diagram by simulating a method for reducing carbon dioxide emissions according to an embodiment of the present invention.

Terms such as first, second and third are used to describe various parts, components, regions, layers and / or sections, but are not limited thereto. These terms are only used to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first portion, component, region, layer or section described below may be referred to as a second portion, component, region, layer or section without departing from the scope of the present invention.

The terminology used herein is only to refer to a specific embodiment and is not intended to limit the invention. The singular forms used herein also include plural forms unless the phrases clearly indicate the opposite. As used herein, the meaning of “comprising” embodies a particular characteristic, region, integer, step, action, element, and / or component, and the presence or presence of another characteristic, region, integer, step, action, element, and / or component. It does not exclude addition.

When referring to a part being "on" or "on" another part, it may be directly on or on the other part, or another part may be involved therebetween. In contrast, if one part is referred to as being “just above” another part, no other part is interposed therebetween.

Although not defined differently, all terms including technical terms and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present invention pertains. Commonly used dictionary-defined terms are further interpreted as having meanings consistent with related technical documents and currently disclosed contents, and are not interpreted as ideal or very formal meanings unless defined.

In addition, unless otherwise specified,% means weight%, and 1 ppm is 0.0001% by weight.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art to which the present invention pertains can easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein.

Carbon dioxide emission reduction device

Hereinafter, a carbon dioxide emission reduction apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4.

The carbon dioxide emission reduction device according to an embodiment of the present invention is a carbon dioxide emission reduction device provided in a molten iron manufacturing facility, and includes a carbon dioxide supply unit 100 for supplying carbon dioxide separated from the exhaust gas, molten slag including calcium oxide and magnesium oxide. The slag supply unit 200 for supplying the crushed slag by crushing and drying, the slag hydration unit 300 for supplying the hydrated slag by hydrating the crushed slag with a reaction gas containing steam, and reacting the hydrated slag with carbon dioxide It includes a slag carbonation unit 400 to carbonize the hydrated slag.

As shown in FIG. 2, the carbon dioxide supply unit 100 manufactures high concentration carbon dioxide of 99.99% by weight% from tail gas separated from exhaust gas generated in the molten iron manufacturing process. The flue gas may be a gas generated from the flow reduction furnace 20 that reduces spectroscopy to reduced iron in the molten iron manufacturing apparatus. In the gas separation unit 30 connected through the flow reduction channel 20 and the exhaust gas discharge line, the tail gas can be separated from the exhaust gas. The separated tail gas is supplied to the carbon dioxide supply unit 100, and the tail gas is separated and the remaining exhaust gas is combined with the reducing gas discharged from the molten gasifier 10 of the molten iron manufacturing apparatus to be supplied again to the flow reduction reactor 20. Can be.

Specifically, the carbon dioxide supply unit 100 cools the tail gas separated from the exhaust gas generated in the molten iron manufacturing process to liquefy the carbon dioxide in the tail gas, separates the liquid carbon dioxide from the tail gas, and residual gas May include a gas-liquid separator 120 that discharges to the outside, a vaporizer 130 that vaporizes liquid carbon dioxide, and a carbon dioxide supplier that supplies gaseous carbon dioxide to the slag carbonation unit 400.

The liquefier 110 liquefies the tail gas separated from the exhaust gas through a refrigerator. Accordingly, carbon dioxide can be liquefied and changed into a liquid phase. The tail gas may be separated from the exhaust gas discharged from the flow reduction furnace 20. Carbon dioxide, carbon monoxide, hydrogen, nitrogen, oxygen, methane, and moisture. The concentration of carbon monoxide may be 60 to 70% by volume. Through the liquefier 110, carbon dioxide may be cooled to -30 ° C or less.

The gas-liquid separator 120 is connected to the liquefier 110, separates carbon dioxide in the liquid phase, and discharges residual gas to the outside. The residual gas may consist of carbon monoxide, hydrogen, nitrogen and oxygen.

The vaporizer 130 is connected to the gas-liquid separator 120 and can convert liquid carbon dioxide back to gaseous carbon dioxide. Accordingly, carbon dioxide at a concentration of 99.99% or more in volume% may be supplied to the slag carbonation unit 400 through a carbon dioxide supply.

More specifically, the carbon dioxide supply unit 100 is a dryer 140 for removing moisture in the tail gas received from the gas separator, a compressor 150 for compressing the tail gas from which the moisture is removed, and for filtering the compressed tail gas. The filter 160 may further include a first heat exchanger 170 that supplies heat to the residual gas discharged from the filtered tail gas to the outside, and supplies the filtered tail gas to the liquefier 110.

The dryer 140 is connected to a gas separator, and can condense the moisture in the tail gas at a low temperature of about 5 ° C or less to remove the moisture content to 0.01% by weight or less. The compressor 150 is connected to the dryer 140 and can compress the tail gas from which moisture is removed at 20 atmospheres or more.

In addition, the filter 160 is connected to the compressor 150, it is possible to remove impurities by filtering the compressed tail gas. The first heat exchanger 170 may be disposed between the filter 160 and the liquefier 110 to supply the filtered tail gas to the liquefier 110. In addition, heat of the filtered tail gas may be transferred to the residual gas by being connected to the gas-liquid separator 120 that discharges the residual gas to the outside. Accordingly, the residual gas may be heated to 25 ° C or higher and used in other processes.

More specifically, the carbon dioxide supply unit 100 stores the rectifier 180 for rectifying the liquid carbon dioxide supplied from the gas-liquid separator 120 and the rectified liquid carbon dioxide, and supplies the liquid carbon dioxide to the vaporizer 130. A reservoir 190 may be further included.

The rectifier 180 is connected to the gas-liquid separator 120 and may be rectified to increase the purity of the liquid carbon dioxide supplied from the gas-liquid separator 120. The reservoir 190 may supply liquid carbon dioxide stored and disposed between the rectifier 180 and the vaporizer 130 to the vaporizer 130.

As shown in FIG. 3, the slag supply unit 200 crushes and dries the molten slag discharged from the molten gasifier 10 of the molten iron manufacturing apparatus, and then supplies the crushed slag. The molten slag includes calcium oxide and magnesium oxide, and may further include iron oxide, silicon oxide, and alumina. Calcium oxide may be 30% to 40% by weight, and magnesium oxide may be 10 to 20%.

Specifically, the slag supply unit 200 converts and supplies molten slag generated in the molten iron manufacturing process to cooling slag, from the first hopper 220 and the first hopper 220 in which the cooling slag is stored. Crusher 230 to crush the supplied cooling slag, classifier 240 to select a certain particle size or less among the crushed slag, slag dryer 250 to dry the selected crushed slag, and the dried crushed slag to the slag hydration unit 300 ) May be included.

The converter 210 is connected to the molten gasifier 10 and may cool the molten slag to supply the cooled slag. The first hopper 220 is connected to the converter 210, and cooling slag in a cooled state may be stored. The crushing machine 230 may be connected to the first hopper 220 to receive the cooling slag from the first hopper 220 to crush the slag.

In addition, the classifier 240 is connected to the shredder 230, and can receive the shredded slag from the shredder 230 to classify the shredded slag according to the particle size. Specifically, classifying that the particle size of the crushing slag is 8 mm or less, and exceeding 8 mm may be circulated to the crusher 230 again to crush the particle size to be 8 mm or less. This is because if the particle size of the crushed slag is excessively large, the reaction efficiency may decrease.

The slag dryer 250 is connected to the classifier 240, and may serve to dry the selected crushed slag supplied from the classifier 240. The transfer line may be connected to the slag dryer 250 to supply the dried crushed slag to the slag hydration unit 300.

As shown in FIG. 4, the slag hydration unit 300 hydrates the crushed slag by reaction with a reaction gas containing steam, as shown in Reaction Schemes 1 and 2 below, the calcium oxide and magnesium oxide contained in the crushed slag are calcium hydroxide and Hydrate with magnesium hydroxide.

[Scheme 1] CaO + H ₂ O = Ca (OH) ₂

[Scheme 2] MgO + H ₂ O = Mg (OH) ₂

As described above, by hydrating the included calcium oxide and magnesium oxide with calcium hydroxide and magnesium hydroxide to activate the surface, the reaction efficiency of the slag carbonation unit 400 with carbon dioxide can be increased.

Specifically, the slag hydration unit 300 is reacted with a reaction gas containing crushed slag and steam, a first reactor 310 in which hydrated slag is generated, and a second reactor for quantitatively discharging the crushed slag to the first reactor 310 It may include a reaction gas line 330 for supplying the reaction gas to the hopper 320 and the first reactor (310).

The first reactor 310 is connected to the slag supply unit 200 and receives crushed slag to allow reaction with a reaction gas containing steam in an internal space. Accordingly, the hydration reaction of the crushed slag including Reaction Scheme 1 and Reaction Scheme 2 may proceed to generate hydrated slag. The first reactor 310 may be configured as a flow path.

The second hopper 320 is connected to communicate with the interior of the first reactor 310, and can quantitatively discharge the crushed slag supplied through the transfer line from the slag supply unit 200 to the first reactor 310.

The reaction gas line 330 is connected to communicate with the interior of the first reactor 310 and may supply a reaction gas containing steam to the interior of the first reactor 310.

More specifically, the slag hydration unit 300 includes a second heat exchanger 340, a second heat exchanger 340 and a reaction gas line 330 for recovering waste heat from exhaust gas discharged from the first reactor 310. It may further include a heat circulation line 350 for communicating the heat supplied from the second heat exchanger 340 to the reaction gas line 330 and the exhaust gas scrubber 360 for cooling and cleaning the exhaust gas.

The second heat exchanger 340 is connected to the first reactor 310, and after the reaction of the reaction gas including the crushed slag and steam inside the first reactor 310, the exhaust gas supplied is supplied to the exhaust gas. You can recover the donations you want. The heat circulation line 350 connects the second heat exchanger 340 and the reaction gas line 330, transfers the collected heat recovered from the second heat exchanger 340 to the reaction gas line 330, and the reaction gas line The reaction gas passing through the 330 may be preheated to 100 ° C or more by receiving heat.

Accordingly, condensation of the steam contained in the reaction gas is prevented, and the efficiency of the hydration reaction with the crushed slag can be increased.

The exhaust gas scrubber 360 may be connected to the second heat exchanger 340 to cool the exhaust gas and then clean it to discharge it.

As shown in FIG. 4, the slag carbonation unit 400 carbonizes the hydrated slag to carbonate the calcium hydroxide and magnesium hydroxide contained in the hydrated slag with calcium carbonate and magnesium carbonate, as shown in Reaction Schemes 3 and 4 below.

[Scheme 3] Ca (OH) ₂ + CO ₂ = CaCO ₃ + H ₂ O

[Reaction Scheme 4] Mg (OH) ₂ + CO ₂ = MgCO ₃ + H ₂ O

In addition, magnesium oxide which is not hydrated in the hydrated slag can be carbonized as shown in Reaction Scheme 5 below.

[Scheme 5] MgO + CO ₂ = MgCO ₃

As described above, it is possible to respond to the regulation of carbon dioxide emission because it is possible to reduce the amount of carbon dioxide emitted to the outside by combining carbon dioxide by using slag generated in the molten iron manufacturing process.

Specifically, the slag carbonation unit 400 is connected to the second reactor 410 and the first reactor 310 where the carbonized slag is formed by the reaction of the hydrated slag and carbon dioxide, and the movement of the hydrated slag to the second reactor 410 This may include a supply line 420 and a carbon dioxide line 430 through which carbon dioxide is supplied to the second reactor 410.

The second reactor 410 is connected to the carbon dioxide supply unit 100 and the slag hydration unit 300, receives carbon dioxide, and receives the hydrated slag to allow reaction of carbon dioxide and hydrated slag in an internal space. Accordingly, the carbonation reaction of the hydrated slag including Reaction Schemes 3 to 5 may proceed to generate carbonation slag. The second reactor 410 may be configured as a flow path.

The supply line 420 connects the first reactor 310 and the second reactor 410 of the slag hydration unit 300 to communicate, so that the hydrated slag generated from the first reactor 310 is second reactor 410. Can be moved to

The carbon dioxide line 430 can connect the carbon dioxide supply unit of the carbon dioxide supply unit 100 and the second reactor 410 to communicate, thereby supplying the high concentration of carbon dioxide generated from the carbon dioxide supply unit 100 to the second reactor 410. have.

More specifically, the slag carbonation unit 400 further includes an on-off valve installed on the supply line 420, and the second reactor 410 may be located below the first reactor 310.

Through the on-off valve, it is possible to adjust the supply amount of the hydrated slag, and by positioning the second reactor 410 below the first reactor 310, it is possible to enable smooth transfer by the weight of the hydrated slag.

More specifically, the slag carbonation unit 400 connects the collector 440 to collect steam and unused carbon dioxide generated from the second reactor 410, and the collector 440 to connect the reaction gas line 330 to the collector 440. It may further include a steam circulation line 450 for delivering the steam supplied from the reaction gas line 330.

The collector 440 is connected to the second reactor 410, and after the reaction of the carbon dioxide and hydrated slag inside the second reactor 410, the exhausted steam and unused carbon dioxide can be collected. The steam circulation line 450 communicates the reaction gas line 330 of the collector 440 and the slag hydration unit 300, thereby transferring the steam supplied from the collector 440 to the reaction gas line 330, thereby allowing reuse of steam. You can make it possible.

More specifically, the slag carbonation unit 400 connects the carbon dioxide washer 460 and the carbon dioxide washer 460 to clean the unused carbon dioxide and the carbon dioxide line 430 to connect the unused carbon dioxide supplied from the carbon dioxide cleaner 460 to the carbon dioxide line. The carbon dioxide circulation line 470 delivered to the 430 may be further included.

The carbon dioxide cleaner 460 is connected to the collector 440 and may clean unused carbon dioxide supplied from the collector 440. The carbon dioxide circulation line 470 connects the carbon dioxide cleaner 460 and the carbon dioxide line 430 to supply unused carbon dioxide collected through the carbon dioxide line 430 to the second reactor 410 so that unused carbon dioxide can be reused. can do.

CO2 emissions Reduction method

The method for reducing carbon dioxide emission according to an embodiment of the present invention is a step of preparing carbon dioxide by treating flue gas generated in a molten iron manufacturing process, and crushing and drying molten slag containing calcium oxide and magnesium oxide to produce crushed slag , Hydrating the crushed slag by reaction with a reaction gas containing steam to produce hydrated slag, and reacting the hydrated slag with carbon dioxide to produce carbonated slag.

First, in the step of manufacturing carbon dioxide, carbon dioxide is produced by treating flue gas generated in the molten iron manufacturing process. Specifically, flue gas may be discharged in the process of reducing the spectroscopy to reduced iron in a flow reduction furnace, and liquefied tail gas separated from the flue gas to extract liquid carbon dioxide and vaporize it again to produce high concentration of carbon dioxide. have.

Next, in the step of manufacturing the crushed slag, the crushed slag is prepared by crushing and drying the molten slag containing calcium oxide and magnesium oxide.

Specifically, the step of manufacturing the crushed slag includes the steps of converting molten slag generated in the molten iron manufacturing process into cooling slag, crushing the cooling slag, selecting a crushed slag having a particle size of 8 mm or less among the crushed slag, and selected crushing And drying the slag.

More specifically, the step of preparing the crushed slag may further include a step of crushing the crushed slag having a particle size exceeding 8 mm again with the phase-cooled slag after selecting the crushed slag. This is because if the particle size of the crushed slag is excessively large, the reaction efficiency may decrease.

Next, in the step of preparing the hydrated slag, the crushed slag is hydrated by reaction with a reaction gas containing steam to hydrate the calcium oxide and magnesium oxide contained in the crushed slag with calcium hydroxide and magnesium hydroxide. In the step of preparing the hydrated slag, a reaction including Reaction Scheme 1 and Reaction Scheme 2 may be performed in a first reactor having a space therein.

On the other hand, the first reactor is composed of a flow path, the gas tip velocity in the flow path is 0.6 to 0.8 m / sec, and the residence time of the crushed slag in the flow path may be 50 to 70 minutes.

By controlling the gas ball tip speed in the flow path within the above range, it is possible to uniformly flow while minimizing scattering of the crushed slag. In addition, the residence time of the crushed slag in the flow path is taken into account the hydration reaction time of the crushed slag.

By maintaining the pressure in the first reactor at 3 to 4 atmospheres, it is possible to make the hydration reaction of the crushed slag more efficient.

The steam (H ₂ O) supplied to the first reactor for calcium oxide (CaO) in the crushed slag may be 1: 4 to 1: 5 in a molar ratio (CaO: H ₂ O). Accordingly, the reaction efficiency can be increased, and it is possible to prevent overheating of the first heater by heat generated by the hydration reaction.

Next, in the step of preparing the carbonated slag, the hydrated slag is carbonized to carbonate the calcium hydroxide and magnesium hydroxide contained in the hydrated slag with calcium carbonate and magnesium carbonate. In the step of preparing the carbonized slag, a reaction including the above Reaction Scheme 3 and Reaction Scheme 4 may be performed in a second reactor having a space therein.

On the other hand, the second reactor is composed of a flow path, the gas tip velocity in the flow path is 0.6 to 0.8 m / sec, and the residence time of the hydrated slag in the flow path may be 50 to 70 minutes.

By controlling the gas ball tip speed in the flow path within the above range, it is possible to uniformly flow while minimizing scattering of the hydrated slag. In addition, the residence time of the hydrated slag in the flow path is taken into consideration of the carbonation reaction time of the hydrated slag.

By maintaining the pressure in the second reactor at 3.2 to 4.4 atmospheres, the carbonization reaction of the hydrated slag can be achieved more efficiently, and the hydrated slag is removed from the first reactor by maintaining 0.2 to 0.4 atmospheres higher than the pressure in the first reactor. It can be smoothly moved to the two reactors.

Specifically, maintaining the second reactor pressure high is such that a certain amount of gas is formed in an upward flow from the second reactor to the first reactor through a stand pipe connected to the first reactor, so that the second reactor is the second. Aeration of the hydrated slag downward to the reactor can facilitate the flow of hydrated slag in the standpipe.

Carbon dioxide (CO ₂ ) supplied to the second reactor relative to the sum of calcium oxide (CaO) and calcium hydroxide (Ca (OH) ₂ ) in the hydrated slag is in a molar ratio (CaO + Ca (OH) ₂ : CO ₂ ), 1: 4 to 1: 5. Accordingly, the reaction efficiency can be increased, and it is possible to prevent the second heater from being overheated by heat generated by the carbonation reaction.

Molten iron manufacturing equipment

Hereinafter, an apparatus for manufacturing molten iron according to an embodiment of the present invention will be described with reference to FIG. 1.

The apparatus for manufacturing molten iron according to an embodiment of the present invention is a molten gasification furnace using a reducing gas discharged from a molten gasifier (10), a molten gasifier (10) to manufacture molten iron by loading reduced iron and carbon materials into a molten gasifier (10) the flow reduction reactor 20, the gas separation unit 30 for separating the tail gas from the exhaust gas discharged from the flow reduction reactor 20, the carbon dioxide from the tail gas discharged from the gas separation unit 30 The carbon dioxide supply unit 100 to extract and supply, the slag supply unit 200 to supply the crushed slag by crushing and drying the molten slag including calcium oxide and magnesium oxide discharged from the molten gasifier 10, the crushed slag It includes a slag hydration unit 300 for hydration by supplying hydrated slag by reaction with a reaction gas containing steam, and a slag carbonation unit 400 for carbonizing hydrated slag by reacting hydrated slag with carbon dioxide.

In the molten gasifier 10, molten iron is manufactured using reduced iron and carbon materials charged therein. In the flow reduction reactor 20, the reducing gas discharged from the molten gasifier 10 is supplied to reduce the spectroscopy to reduced iron, and flue gas is generated in this process. The reducing gas line 11 through which the reducing gas moves may connect the molten gasification furnace 10 and the flow reduction furnace 20. A high temperature cyclone 12 is disposed on the reducing gas line 11 to separate dust from the reducing gas. The separated dust may be supplied to the molten gasifier 10 again.

Part of the reducing gas that has passed through the high temperature cyclone 12 is collected through the wet dust collector 13 and then discharged to the outside air discharge line 40. Accordingly, the pressure of the molten gasifier 10 can be adjusted. In addition, a part of the reducing gas that has passed through the wet dust collector 13 is supplied to the molten gasifier 10 again to control the temperature of the molten gasifier 10.

The gas separation unit 30 is connected to the flow reduction furnace 20 to separate the tail gas containing carbon dioxide from the exhaust gas. The exhaust gas line 21 through which the exhaust gas moves may heat the flow reduction furnace 20 and the gas separation unit 30. A dust collector 22 is installed on the exhaust gas line 21 to collect exhaust gas discharged from the flow reduction channel 20. The off-gas line may be branched and connected to the outside air discharge line 40.

Through the gas separation unit 30, the separated tail gas is supplied to the carbon dioxide supply unit 100, and the tail gas from which the tail gas is separated is moved to the reducing gas line and combined with the reducing gas, and then the flow reduction channel 20 Can be supplied with.

In addition, the description of the carbon dioxide supply unit 100, the slag supply unit 200, the slag hydration unit 300 and the slag carbonation unit 400 will be replaced by the description of the carbon dioxide emission reduction device described above.

Hereinafter, specific examples of the present invention will be described. However, the following examples are only specific examples of the present invention, and the present invention is not limited to the following examples.

Example

The composition of the tail gas separated using the gas separator from the exhaust gas discharged from the flow reduction furnace is shown in Table 1 below.

division CO ₂ CO H ₂ CH ₄ N ₂ H ₂ O Content (% by volume) 21.1 67.5 4.7 1.5 3.6 1.7

The tail gas having the above composition was cooled to 5 ° C. or less to remove moisture to 0.1% or less, and then compressed to about 20 atmospheres, and the fine particles were removed through filtration, and then cooled to −30 ° C. or less.

By separating only the liquid carbon dioxide prepared through this and vaporizing it again, carbon dioxide was produced at a concentration of 99.99% or more by volume.

On the other hand, the composition of the molten slag discharged from the melt gasifier is shown in Table 2 below.

division FeO SiO ₂ CaO Al ₂ O ₃ MgO Content (mass%) 0.50 31.91 38.31 16.95 12.32

The molten slag having the above composition was cooled and crushed to a particle size of 8 mm or less. The crushing slag having a particle size exceeding 8 mm was again supplied to the crushing machine to crush it so that the particle size was 8 mm or less to prepare a crushing slag.

The crushed slag was supplied to the first reactor in the form of a flow path, and reacted by supplying a reaction gas containing air and steam into the first reactor. At this time, the gas hole tip speed in the flow path was about 0.7 m / sec, and the residence time of the crushed slag in the flow path was about 60 minutes. The pressure in the flow path was about 3.5 atmospheres.

The hydrated slag thus prepared was supplied to a second reactor in the form of a flow path, and carbon dioxide having a concentration of 99.99% or more was supplied to the second reactor to react. At this time, the gas hole tip speed in the flow path was about 0.7 m / sec, and the residence time of the crushed slag in the flow path was about 60 minutes. The pressure in the flow path was controlled to be about 0.3 atmospheres lower than the first reactor at about 3.2 atmospheres.

As shown in FIG. 5, after the above-described process, about 6 tons (tons) of carbon dioxide could be solidified using 20 tons per hour of crushed slag. This is an amount corresponding to about 20% of the total carbon dioxide contained in the tail gas, and an amount corresponding to about 10% of the total carbon dioxide generated in the molten iron manufacturing process.

The present invention is not limited to the above embodiments and / or embodiments, but may be manufactured in various different forms, and those skilled in the art to which the present invention pertains may change the technical spirit or essential features of the present invention. It will be understood that it may be practiced in other specific forms without. Therefore, it should be understood that the above-described embodiments and / or embodiments are illustrative in all respects and not restrictive.

10: molten gas furnace 11: reducing gas line
12: high temperature cyclone 13: wet dust collector
20: flow reduction path 21: flue gas line
22: dust collector 30: gas separation unit
40: outside air discharge line
100: carbon dioxide supply unit 110: liquefier
120: gas-liquid separator 130: vaporizer
140: dryer 150: compressor
160: filter 170: first heat exchanger
180: rectifier 190: storage
200: slag supply unit 210: converter
220: first hopper 230: crusher
240: classifier 250: slag dryer
300: slag hydration unit 310: first reactor
320: second hopper 330: reaction gas line
340: second heat exchanger 350: heat circulation line
360: exhaust gas scrubber 400: slag carbonation unit
410: second reactor 420: supply line
430: carbon dioxide line 440: collector
450: steam circulation line 460: carbon dioxide scrubber
470: carbon dioxide circulation line

Claims (23)

A carbon dioxide supply unit that supplies carbon dioxide by treating flue gas generated in the molten iron manufacturing process;
A slag supply unit for crushing and drying molten slag containing calcium oxide and magnesium oxide to supply the crushed slag;
A slag hydration unit for hydrating the crushed slag by reaction with a reaction gas containing steam to supply hydrated slag; And
Includes; a slag carbonation unit for carbonizing the hydrated slag by reacting the hydrated slag with the carbon dioxide,
The carbon dioxide supply unit,
A liquefier that liquefies carbon dioxide in the tail gas by cooling the tail gas separated from the exhaust gas;
A gas-liquid separator for separating liquid carbon dioxide from the tail gas and discharging residual gas to the outside;
A vaporizer for vaporizing liquid carbon dioxide; And
Carbon dioxide emission reduction device comprising a; carbon dioxide supply to supply carbon dioxide in the gas phase to the slag carbonation unit. delete According to claim 1,
The carbon dioxide supply unit,
A gas separator separating the tail gas from the exhaust gas,
A dryer that removes moisture in the tail gas supplied from the gas separator;
A compressor for compressing the tail gas from which the moisture has been removed; And
A filter for filtering the compressed tail gas; And
And a first heat exchanger for supplying heat from the filtered tail gas to the residual gas discharged to the outside, and supplying the filtered tail gas to the liquefier. According to claim 1,
The carbon dioxide supply unit,
A rectifier for rectifying the liquid carbon dioxide supplied from the gas-liquid separator; And
The rectified liquid carbon dioxide is stored, a reservoir for supplying the liquid carbon dioxide to the vaporizer; further comprising a carbon dioxide emission reduction device. According to claim 1,
The slag supply unit,
A converter for converting and supplying molten slag generated in the molten iron manufacturing process to cooling slag;
A first hopper in which the cooling slag is stored;
A crusher for crushing the cooling slag supplied from the first hopper;
A classifier for sorting the crushed slag having a certain particle size or less from the crushed slag;
A slag dryer for drying the selected crushed slag; And
A carbon dioxide emission reduction device comprising; a transfer line for supplying the dried crushed slag to the slag hydration unit. According to claim 1,
The slag hydration unit,
A first reactor in which hydrated slag is generated by reaction of the crushed slag and the reaction gas;
A second hopper for quantitatively discharging the crushed slag into the first reactor;
Carbon dioxide emission reduction apparatus comprising a; reaction gas line for supplying the reaction gas to the first reactor. The method of claim 6,
The slag hydration unit,
A second heat exchanger that recovers waste heat from exhaust gas discharged from the first reactor;
A heat circulation line communicating the second heat exchanger with the reaction gas line to transfer heat supplied from the second heat exchanger to the reaction gas line; And
And an exhaust gas scrubber for cooling and cleaning the exhaust gas. The method of claim 6,
The slag carbonation unit,
A second reactor in which carbonation slag is produced by reaction of the hydrated slag and the carbon dioxide;
A supply line connected to the first reactor and moving the hydrated slag to the second reactor; And
Carbon dioxide emission reduction device comprising a; carbon dioxide line is supplied to the second reactor. The method of claim 8,
The slag carbonation unit,
A collector for collecting steam and unused carbon dioxide generated from the second reactor; And
The carbon dioxide emission reduction apparatus further comprising; a steam circulation line connecting the collector and the reaction gas line to deliver the steam supplied from the collector to the reaction gas line. The method of claim 9,
The slag carbonation unit,
A carbon dioxide cleaner that cleans the unused carbon dioxide; And
And a carbon dioxide circulation line connecting the carbon dioxide scrubber and the carbon dioxide line to deliver the unused carbon dioxide supplied from the carbon dioxide scrubber to the carbon dioxide line. The method of claim 8,
The slag carbonation unit,
Further comprising; an on-off valve installed on the supply line,
The second reactor is a carbon dioxide emission reduction device located below the first reactor. Producing carbon dioxide by treating flue gas generated in the molten iron manufacturing process;
Crushing and drying the molten slag containing calcium oxide and magnesium oxide to prepare a crushed slag;
Preparing the hydrated slag by hydrating the crushed slag by reaction with a reaction gas containing steam; And
Including the step of preparing the carbonated slag by reacting the hydrated slag with the carbon dioxide,
In the step of preparing the hydrated slag,
A method for reducing carbon dioxide emission in which a reaction including the following Reaction Schemes 1 and 2 is performed in a first reactor having space therein.
[Scheme 1] CaO + H ₂ O = Ca (OH) ₂
[Scheme 2] MgO + H ₂ O = Mg (OH) ₂ The method of claim 12,
The step of manufacturing the crushed slag,
Converting molten slag generated in the molten iron manufacturing process into cooling slag;
Crushing the cooling slag;
Separating the crushed slag having a particle size of 8 mm or less from the crushed slag; And
Drying the selected crushed slag; CO2 emission reduction method comprising a. The method of claim 13,
The step of manufacturing the crushed slag,
After the step of sorting the crushing slag, crushing slag having a particle size of more than 8mm is crushed again with the cooling slag; further comprising a carbon dioxide emission reduction method. delete The method of claim 12,
The first reactor is composed of a flow path, the gas hole tip speed in the flow path is 0.6 to 0.8m / sec, and the residence time of the crushed slag in the flow path is 50 to 70 minutes. The method of claim 12,
The pressure in the first reactor is 3 to 4 atmospheres CO2 emission reduction method. The method of claim 12,
Steam (H ₂ O) supplied to the first reactor for the calcium oxide (CaO) in the crushed slag in a molar ratio (CaO: H ₂ O), 1: 4 to 1: 5 carbon dioxide emission reduction method. The method of claim 12,
In the step of preparing the carbonation slag,
A method for reducing carbon dioxide emissions in which a reaction including the following Reaction Schemes 3 and 4 is performed in a second reactor having a space therein.
[Scheme 3] Ca (OH) ₂ + CO ₂ = CaCO ₃ + H ₂ O
[Reaction Scheme 4] Mg (OH) ₂ + CO ₂ = MgCO ₃ + H ₂ O The method of claim 19,
The second reactor is composed of a flow path, the gas hole tip speed in the flow path is 0.6 to 0.8m / sec, and the residence time of the hydration slag in the flow path is 50 to 70 minutes. The method of claim 19,
The pressure in the second reactor is 3.2 to 4.4 atmospheres of carbon dioxide emission reduction method. The method of claim 19,
Carbon dioxide (CO ₂ ) supplied to the second reactor relative to the sum of calcium oxide (CaO) and calcium hydroxide (Ca (OH) ₂ ) in the hydrated slag is a molar ratio (CaO + Ca (OH) ₂ : CO ₂ ), A method for reducing carbon dioxide emissions of 1: 4 to 1: 5. A molten gasification furnace in which molten iron and carbon materials are charged to manufacture molten iron;
A flow reduction furnace for supplying reduced iron produced using the reducing gas discharged from the molten gasifier to the molten gasifier;
A gas separation unit separating tail gas from exhaust gas discharged from the flow reduction furnace;
A carbon dioxide supply unit that extracts and supplies carbon dioxide from the tail gas discharged from the gas separation unit;
A slag supply unit for crushing and drying molten slag including calcium oxide and magnesium oxide discharged from the molten gasifier to supply crushed slag;
A slag hydration unit for hydrating the crushed slag by reaction with a reaction gas containing steam to supply hydrated slag; And
Includes; a slag carbonation unit for carbonizing the hydrated slag by reacting the hydrated slag with the carbon dioxide,
The carbon dioxide supply unit,
A liquefier that liquefies carbon dioxide in the tail gas by cooling the tail gas separated from the exhaust gas;
A gas-liquid separator for separating liquid carbon dioxide from the tail gas and discharging residual gas to the outside;
A vaporizer for vaporizing liquid carbon dioxide; And
A molten iron manufacturing apparatus comprising a; carbon dioxide supply for supplying gaseous carbon dioxide to the slag carbonation unit.

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