WO2019225256A1 - Facility for producing direct reduced iron and production method - Google Patents

Abstract

[Problem] With regard to a facility for producing direct reduced iron and production method, the present invention addresses the problem of solving the problem of impurities admixed from, e.g., iron ore powder, and toxic dissolved gases, and substantially reducing the water consumption without being governed by locational factors. [Solution] In a facility for producing direct reduced iron, gas containing large amounts of steam, e.g., the gas discharged from an externally heated reformer is cooled to recover the water fraction in the gas. In addition, a cooling water system is provided with a degasification facility to remove toxic dissolved gases, and is provided with a desalination function and a solids separation function to remove impurities contained in feed water and impurities admixed from, e.g., the iron ore powder, thereby functioning as a purifier. The requirement for make-up water is then either substantially reduced or is eliminated. Contaminated wastewater is also made unnecessary.

Description

Direct reduced iron production equipment and production method

The present invention relates to a directly reduced iron production facility and method, and more particularly to a directly reduced iron production facility and method capable of reducing water consumption.

As a method of reducing iron oxide such as calcined pellets using lump ore or iron ore powder and producing metallic iron in a vertical reduction furnace (shaft furnace), mainly direct reduction iron making in addition to blast furnace iron making method There is a method called law. In the direct reduction iron manufacturing method, as disclosed in Patent Document 1, typically, a reduction gas mainly composed of hydrogen and carbon monoxide is introduced into a vertical reduction furnace to reduce iron oxide, and oxidation Metal iron is produced by reducing iron in the solid phase.

This reducing gas is typically a steam alone or a hydrocarbon gas such as natural gas mainly containing methane (CH ₄ ) with water vapor and carbon dioxide (CO ₂ ) as an oxidant. It is produced by reacting with an oxidant at a high temperature by a reformer. This reducing gas introduced into the vertical reduction furnace reacts with iron oxide in the reduction furnace, and a part thereof becomes an oxidant of water vapor and carbon dioxide. The main components of the gas (top gas) discharged from the reduction furnace are these oxidizing agents and reducing gases of unreacted hydrogen and carbon monoxide. The top gas is dusted with a scrubber, cooled and then pressurized, introduced into a reformer along with new hydrocarbon gas, and recycled.

In addition, when the produced reduced iron (DRI) is cooled and discharged, a cooling zone is provided at the lower part of the reduction zone, and a cooling gas (cooling gas) is introduced into the reduction furnace to reduce the reduced iron (DRI). Is cooling. The cooling gas used for this cooling is discharged from the intermediate part of the furnace below the reducing gas introduction part of the reducing furnace, removed by a scrubber and cooled, and then pressurized and circulated.

In any of the above cases, since the heated gas (top gas, cooling gas) is circulated and used, dust is removed and cooled with water. For this reason, a large amount of water is required.

In addition, in direct reduced iron production facilities, a reformed gas cooler that cools a part of the reformed gas to control the temperature of the reformed gas, and a non-requirement necessary to prevent reoxidation of the reduced iron (DRI). The cooling water used for the seal gas cooler for cooling the combustion exhaust gas of the reformer necessary for producing the active gas (seal gas), as well as the equipment cooling water for cooling the equipment, are necessary. In order to recycle water, it is necessary to cool the circulating water. For this reason, usually, an open cooling tower is used to cool and circulate with the heat of evaporation.

In this case, in addition to the water loss due to evaporation, waste water (blow-down water) for managing the salt contained in the makeup water and the salt and other dissolved components mixed in from the raw materials such as iron ore powder below the specified value In addition, it is necessary to supplement moisture (slurry moisture) discharged together with the solid content.

The hydrocarbon gas (natural gas) required for direct reduction iron making is abundantly buried in desert areas such as the Middle East, and many direct reduction iron production facilities (plants) have been built in these areas. In these areas, there are many areas where fresh water cannot be supplied sufficiently or at low cost, and it has been desired to reduce water consumption.

US Patent Publication No. 3764123 JP 52-128820 A

Patent Document 2 proposes that a closed system that cools the dust removal water or cooling water necessary for the direct reduction iron making process with seawater is used to prevent evaporation loss and reduce water consumption.

However, in plants that are not located on the coast, there is a problem that the cost of seawater supply equipment and return water equipment for supplying seawater becomes enormous, and maintenance costs are also high, and the seawater cooling method is not adopted.

In addition, there are many areas where the temperature is high in the area where the direct reduction iron manufacturing method is adopted, and cooling the circulating water only with the air has the disadvantage that the cooling device becomes very large.

Therefore, consumes about 1.5m ³ of water from such still reduced iron is in the region (DRI) 1 per ton of 1m ^3.

In addition, even in coastal plants that use a closed water system that uses seawater, the water system of the reduced iron (DRI) manufacturing facility directly removes circulating ore from the iron ore powder in order to remove iron ore powder. As it comes into contact, impurities are mixed from other than makeup water. Particularly in recent direct reduced iron (DRI) production facilities, a calcium coating is applied to iron ore with calcium hydroxide or the like to improve productivity, and a lot of this calcium coating powder is mixed in water.

Therefore, even when a closed system cooling system using seawater is adopted, there remains a problem that requires a certain amount of blowdown to maintain the water quality for moving the equipment in a healthy state. This water quality management mainly uses impurities such as hardness, alkalinity, total amount of dissolved impurities, chloride ion concentration, and sulfate ion concentration as impurities, which are mixed or dissolved in water. To manage.

In addition, the reducing gas used for reduction contains a lot of hydrogen and carbon monoxide flammable gas or toxic gas, and seal gas is used for the purpose of preventing the reducing gas from leaking outside. . A gas mainly containing nitrogen and carbon dioxide or a gas mainly containing nitrogen is used as the seal gas. Since a part of the seal gas is mixed into the circulation gas for reforming or reduction, nitrogen is mixed into the circulation gas. By the reaction of nitrogen and hydrogen, ammonia is generated in the circulating gas in the process of reforming or reduction.

This ammonia easily dissolves in water. However, in a closed water system, this ammonia is concentrated, causing a problem of corrosion and damage to copper parts and equipment used in valves and the like. Therefore, in order to prevent this problem, it is necessary to deaerate ammonia with a device that evaporates water, such as a cooling tower, or to blow down so that the ammonia concentration is less than a specified value. It was left.

In Patent Document 2, in order to reduce the concentration of impurities in the makeup water, it is disclosed that water generated by hydrogen reduction at the time of reduction is recovered from the top gas, and the water is cooled and reused using seawater or air as a refrigerant. ing.

The reaction is shown below.
FeO _x + 1 / 2X · H ₂ = Fe + 1 / 2X · H ₂ O
Here, FeO _x represents iron oxide and includes Fe ₂ O ₃ and Fe ₃ O ₄ .

Further, it is disclosed that a CO ₂ gas that promotes adhesion and clogging is prevented from changing its solubility as a closed system.

However, in the reduced iron production facility, impurities are mixed from the iron ore powder and calcium coating powder in addition to the impurities contained in the makeup water. In the closed system, although the change in the concentration of CO _{2 in} the circulating water can be suppressed, the solubility of each component in the gas, for example, CO _{2 in} the circulating water is saturated or close to it. The problem of adhesion and clogging could not be solved by impurities from the powder and dissolved CO ₂ close to saturation. Moreover, the problem of corrosion accompanying the increase in the concentration of corrosive gas such as ammonia has occurred, and a certain amount of blow-down is required. As a result, a lot of makeup water is required.

Among the methods proposed in Patent Document 2, even in a plant that employs a closed water system that cools with seawater that can most reduce the amount of water consumption, it is one of the general open-system plants for the above reasons. About 2 to 1/3 of replenishing water was required.

The present invention has been made to solve the above-described problems, and provides a directly reduced iron manufacturing facility and a manufacturing method capable of significantly reducing water consumption without being affected by location conditions. With the goal.

Specifically, the present invention provides a process that can further reduce water consumption in the process of cooling water in seawater or air, and a process that reduces water consumption without using seawater cooling.

Further, the present invention provides a process capable of reducing water consumption by degassing harmful dissolved gases such as carbon dioxide (CO ₂ ), carbon monoxide (CO), and ammonia (NH ₃ ).

In addition, the blow-down water is treated and purified, and then returned to circulating water, and the concentrated wastewater concentrated by the treatment is purified and effectively used to achieve stable operation of the plant and reduce water consumption. At the same time, we will provide a means to reduce polluted waste water (factory waste liquid) discharged from the plant and contribute to environmental conservation.

In the system that separates and recovers the water generated in the reduction process shown in Patent Document 2 from the top gas, which is exhaust gas from the top of the reduction furnace, and indirectly cools it with seawater etc., it is mixed from iron ore powder and calcium coating powder. In order to control the concentration of impurities to be generated and to control the concentration of dissolved harmful components such as carbon dioxide, carbon monoxide, and ammonia from the circulating gas within a specified value, blowdown is necessary. This blowdown water did not provide a sufficient water consumption reduction effect. Accordingly, the present invention not only collects water generated in the reduction process, but also cools a gas containing a large amount of water vapor such as combustion exhaust gas generated by combustion of a combustion device used for heating a reformer, and clean water in the gas. The first feature is to separate and recover.

In addition, the present invention improves the recovered water amount and recovery efficiency by cooling by mixing a high oxygen-containing gas such as pure oxygen with the combustion oxidizing gas used to heat the reformer and raising the water vapor partial pressure in the exhaust gas. The second feature is to make it.

Furthermore, the third aspect of the present invention is to provide a demineralization function and a solid content separation function in the directly reduced iron production facility, and to provide a purification function to remove impurities mixed in from the feed water and iron ore powder. It is characterized by. In other words, blowdown water necessary to discharge the mixed impurities out of the system in an appropriate amount is sprayed on the reformer's exhaust gas or the exhaust gas during the production of calcined pellets, and cooled after removing salt and solids with a dry dust collector Clean water is collected, or blow-down water is used as calcium coating water for the fired pellets, spray water for cooling the fired pellets, spray water for cooling the DRI, or for adjusting the furnace top temperature or for the raw material. A third feature is that it is used as water for clogging elimination in a hopper to separate clean water from salt and solids.

Furthermore, the present invention has a fourth feature that the circulating water line has a degassing function in order to lower the concentration of harmful dissolved gas dissolved in water after indirectly cooling the return water containing the recovered water. To do.

More specifically, the present invention has the following configuration.

The present invention is a direct reduced iron production facility for directly producing reduced iron by bringing a raw material and a reducing gas into contact with each other in a reduction furnace. This direct reduced iron production facility directly cools the combustion exhaust gas containing the externally heated reformer that produces the reducing gas that reduces the raw material and the steam discharged from the reformer, and condenses and recovers the moisture in the combustion exhaust gas. A water-cooled cooler.

In the directly reduced iron production facility of the preferred embodiment, the combustion oxidizing gas supplied to the reformer is a high oxygen-containing gas adjusted to a higher concentration than the oxygen concentration in the atmosphere.

In another preferred embodiment, the directly reduced iron production facility includes an evaporator for spraying water containing impurities and a dry dust collector for removing impurities on the upstream side of the water-cooled cooler.

In another preferred embodiment, the directly reduced iron manufacturing facility further includes a cooling heat exchanger that indirectly cools the return water of the water-cooled cooler other than the circulating water that is circulated and used in the manufacturing facility.

In the directly reduced iron production facility of a more preferred embodiment, at least a part of the gas cooled by the water-cooled cooler is used as the refrigerant of the cooling heat exchanger.

The directly reduced iron production facility of a further preferred embodiment further includes a precooler between the reformer and the water-cooled cooler for precooling the combustion exhaust gas with at least a part of the gas cooled by the water-cooled cooler. Prepare.

Further, in the directly reduced iron production facility of a more preferred embodiment, the refrigerant cooled in the cooling heat exchanger is selectively used or mixed with the gas cooled by the water-cooled cooler and the atmosphere.

The directly reduced iron production facility of a further preferred embodiment further includes a degassing device for degassing the return water of the water-cooled cooler. The deaeration device is provided on the downstream side of the cooling heat exchanger.

Another embodiment of the present invention is a production facility for directly reduced iron in which a raw material and a reducing gas are brought into contact with each other in a reduction furnace to directly produce reduced iron, and the directly reduced iron is briquetted hot. This direct reduced iron production facility includes a hot briquette machine that produces hot briquette iron from high temperature direct reduced iron, a briquette quench conveyor that conveys the produced hot briquette iron, and a hot briquette on the briquette quench conveyor. A steam-containing gas containing water vapor that is generated when water is sprayed onto iron to cool it is sucked and indirectly cooled to condense and recover moisture in the steam-containing gas, and discharged from the cooling condenser. And a water-cooled cooler that condenses and recovers moisture in the gas discharged from the cooling condenser.

In a directly reduced iron production facility according to a preferred embodiment, water in which an alkali component is concentrated to a concentration higher than the concentration of make-up water is used as water sprayed on hot briquette iron.

In another preferred embodiment, the directly reduced iron manufacturing facility further includes a cooling heat exchanger that indirectly cools the return water of the water-cooled cooler other than the circulating water that is circulated and used in the manufacturing facility.

In the directly reduced iron production facility of a more preferred embodiment, at least a part of the gas cooled by the water-cooled cooler is used as the refrigerant of the cooling heat exchanger.

Further, in the directly reduced iron production facility of a more preferred embodiment, the refrigerant cooled in the cooling heat exchanger is selectively used or mixed with the gas cooled by the water-cooled cooler and the atmosphere.

Also, the present invention is a method for producing directly reduced iron, in which raw material and reducing gas are brought into contact with each other in a reducing furnace to produce directly reduced iron. The direct reduced iron manufacturing method includes a cooling process in which combustion exhaust gas containing water vapor discharged from an externally heated reformer that produces a reducing gas for reducing raw materials is directly cooled with a water-cooled cooler, and a water-cooled cooler. And a recovery step of condensing and recovering moisture in the cooled gas.

In the directly reduced iron production method of the preferred embodiment, the combustion oxidizing gas supplied to the reformer is a high oxygen-containing gas adjusted to a higher concentration than the oxygen concentration in the atmosphere.

Another preferred embodiment of the method for producing directly reduced iron further includes a spraying step of spraying water containing impurities on the flue gas before the direct cooling step, and a removing step of removing impurities after the spraying step. Prepare.

The method for producing directly reduced iron according to another preferred embodiment further includes an indirect water cooling step of indirectly cooling the return water of the water cooled cooler. In the indirect water cooling process, water other than circulating water that is circulated and used in the production facility of directly reduced iron is used as a refrigerant.

In the directly reduced iron production method of the more preferred embodiment, in the water indirect cooling step, at least a part of the gas cooled by the water-cooled cooler is used as the refrigerant.

The directly reduced iron manufacturing method of a further preferred embodiment further includes a precooling step of precooling the combustion exhaust gas with at least a part of the gas cooled by the water-cooled cooler before the direct cooling step.

In a further preferred embodiment of the method for producing directly reduced iron, in the water indirect cooling step, the gas cooled by the water-cooled cooler and the atmosphere are selectively used or mixed as the refrigerant.

The method for producing directly reduced iron according to a more preferred embodiment further includes a deaeration step of degassing the return water of the water-cooled cooler after the water indirect cooling step.

Another embodiment of the present invention is a method for producing directly reduced iron, in which raw material and reducing gas are brought into contact with each other in a reduction furnace to produce directly reduced iron, and the directly reduced iron is briquetted hot. This method for producing directly reduced iron is a steam containing steam generated when sprayed with hot briquette iron produced from high-temperature directly reduced iron and sprayed with water in which the alkali component is concentrated to a concentration higher than the makeup water concentration. A gas indirect cooling process in which the contained gas is indirectly cooled with a cooling condenser, a direct cooling process in which the gas cooled in the gas indirect cooling process is further directly cooled with a water-cooled cooler, and a gas cooled in the water-cooled cooler. A recovery step of condensing and recovering the moisture therein.

The method for producing directly reduced iron according to a preferred embodiment further includes an indirect water cooling step of indirectly cooling the return water of the water cooled cooler. In the indirect water cooling process, water other than circulating water that is circulated and used in the production facility of directly reduced iron is used as a refrigerant.

In the directly reduced iron production method of the more preferred embodiment, in the water indirect cooling step, at least a part of the gas cooled by the water-cooled cooler is used as the refrigerant.

In a further preferred embodiment of the method for producing directly reduced iron, in the water indirect cooling step, the gas cooled by the water-cooled cooler and the atmosphere are selectively used or mixed as the refrigerant.

By adopting the directly reduced iron production facility and method of the present invention, water consumption can be greatly reduced even in regions where it is difficult to use seawater cooling and in regions where the temperature is high.

In addition, in areas where seawater cooling can be used and in seasons and areas where the temperature is low, surplus clean water can be generated. There is an advantage that it is possible to supply cooling water from a steelmaking facility that is a facility.

Furthermore, when blowdown water is sprayed on the reformer's combustion exhaust gas, salt and solids are removed with a dry dust collector, and then cooled and recovered with clean water, the quality of the supplied water Even in poor areas, there is an advantage that the plant can be operated soundly without the need for pre-water treatment facilities.

It is a whole flowchart of the conventional general direct reduction iron manufacturing equipment. It is a whole flow figure of the production equipment (equipment which collects water using a reformer exhaust gas scrubber) in direct reduction iron in Embodiment 1 of the present invention. It is a partial flow figure of the manufacturing apparatus (equipment which controls the ratio of hydrogen and carbon monoxide of reformed gas using a boiler) directly reduced iron production equipment in Embodiment 2 of the present invention. It is a whole flow figure of the manufacturing equipment (equipment which installs a desalination apparatus and collects water from a desalination apparatus) of direct reduction iron in Embodiment 3 of the present invention. It is a partial flow figure of the manufacturing equipment (equipment which installs an evaporator and a dry dust collector, and collects clean water from blowdown water) in direct reduced iron in Embodiment 4 of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The present invention is a direct reduction iron production facility that directly produces reduced iron by bringing a raw material and a reducing gas into contact with each other in a reduction furnace, and direct reduction by bringing the raw material and the reduction gas into contact with each other in the reduction furnace using the production facility. It is a manufacturing method of direct reduction iron which manufactures iron.

First, a conventional general direct reduced iron production facility 40 and production method will be described with reference to FIG. In the directly reduced iron production facility 40, hydrocarbon gas such as natural gas is reformed, and the reformed gas (reduced gas) is brought into contact with the raw material made of iron ore or calcined pellets in the reducing furnace 2 to reduce the raw material. This is a facility for directly producing reduced iron (DRI).

A general direct reduction iron manufacturing facility 40 manufactures a vertical reduction furnace (reduction furnace) 2 for reducing raw materials, a raw material charging conveyor 1 for charging raw materials into the reduction furnace 2, and a reducing gas for reducing raw materials. And an externally heated reformer 6 for supplying to the reduction furnace 2. In addition, the directly reduced iron production facility 40 removes and cools the top gas discharged from the top of the reduction furnace 2 to the top gas scrubber 4, the reformed gas cooler 8 that cools the reformed gas, and the reduction furnace 2. A cooling gas circulation system that circulates and supplies gas, a seal gas cooler 11 that cools the combustion exhaust gas discharged from the reformer 6, and a preheater that preheats or cools the combustion exhaust gas are provided. Furthermore, the directly reduced iron manufacturing facility 40 includes a clarifier 18 that removes solids mixed in water circulated and used in the manufacturing facility 40, a hot water sump 19 that stores water, and a cooling tower 20 that cools water. I have. In the directly reduced iron production facility 40 of FIG. 1, the preheater is composed of a combustion air preheater 14, a primary process gas preheater 15, and a secondary process gas preheater 16.

The raw material consisting of iron ore or calcined pellets is input from the upper part of the vertical reduction furnace 2 via the raw material input conveyor 1, and is reduced by the reducing gas supplied from the reformer 6 at the upper part. A vertical reduction furnace cooling zone (cooling zone) 3 is disposed below the reduction furnace 2. The cooling zone 3 is provided with a cooling gas circulation system including a cooling gas scrubber 9 and a cooling gas compressor 10. In the cooling gas circulation system, the gas discharged from the cooling zone 3 is dust-removed and cooled by the cooling gas scrubber 9, the pressure is raised by the cooling gas compressor 10, and the cooling gas (cooling gas) is supplied to the cooling zone 3. It is circulating. Directly reduced iron (DRI), which is a product, is discharged after being cooled with a cooling gas supplied from a cooling gas circulation system.

By not installing the cooling gas circulation system or stopping the circulation of the cooling gas, the reduced iron (DRI) can be directly discharged and used as hot DRI (HDR) without being cooled. . The direct reduced iron manufacturing facility 40 includes a hot briquette machine 13 that manufactures hot briquette iron from high-temperature direct reduced iron. The HDRI is fed into the hot briquette machine 13 to manufacture hot briquette iron (HBI). It is also possible to do.

The reduced gas (top gas) discharged from the top of the reduction furnace 2 is dedusted and cooled by the top gas scrubber 4, and a part is used as fuel for the combustion device (burner) 7 of the reformer 6. In addition, the other part of the top gas removed and cooled by the top gas scrubber 4 is pressurized by the process gas compressor 5 and mixed with a hydrocarbon gas such as natural gas (not shown). Preheated by the preheater 15 and the secondary process gas preheater 16, reformed by the reformer 6, and again introduced into the reduction furnace 2. The temperature of the gas charged into the reduction furnace 2 is adjusted by cooling a part of the reformed gas reformed by the reformer 6 with the reformed gas cooler 8 and returning it to the mainstream.

The reformer 6 is provided with a heating burner 7, and a part of the flue gas discharged by the combustion of the burner 7 is cooled by a seal gas cooler 11, and after being pressurized by a seal gas compressor 12, is inert. It is supplied to each use point not shown in the figure as a proper seal gas.

Most of the combustion exhaust gas of the reformer 6 is cooled and recovered by the combustion air preheater 14, the primary process gas preheater 15, and the secondary process gas preheater 16, and then is returned to the atmosphere via the ejector stack 17. Released.

The cooling water is divided into an equipment cooling water system (not shown) and a direct water system in direct contact with gas and dust. The direct water is returned to the clarifier 18 after the gas is cooled in each of the coolers 8 and 11 and after the gas is removed and cooled in each of the scrubbers 4 and 9. Thereafter, most of the direct water is removed by the clarifier 18 and is temporarily stored in the hot water sump 19. The hot water stored in the hot water sump 19 is cooled by the cooling tower 20 and supplied again to the top gas scrubber 4, the reformed gas cooler 8, the cooling gas scrubber 9, and the seal gas cooler 11.

Next, a directly reduced iron production facility 40a and a production method according to Embodiment 1 of the present invention will be described with reference to FIG. The direct reduced iron manufacturing facility 40a of the first embodiment includes the configuration of the general direct reduced iron manufacturing facility 40 described above and functions in the same manner. That is, the directly reduced iron production equipment 40a includes a raw material charging conveyor 1, a vertical reduction furnace 2, a vertical reduction furnace cooling zone 3, a top gas scrubber 4, a process gas compressor 5, a reformer 6, a burner 7, and a reformed gas cooler. 8, Cooling gas scrubber 9, Cooling gas compressor 10, Seal gas cooler 11, Seal gas compressor 12, Hot briquette machine 13, Combustion air preheater 14, Primary process gas preheater 15, Secondary process gas preheater 16, Clari A fire 18, a hot water sump 19, and a cooling tower 20 are provided.

In addition, the directly reduced iron production facility 40a of the first embodiment directly cools the combustion exhaust gas containing water vapor discharged from the reformer 6, condenses and recovers the moisture in the combustion exhaust gas, A deaerator 27 for degassing the return water of the water cooler 22, a cooling heat exchanger 24 for indirectly cooling the return water of the water cooler 22, and a precooler 21 for precooling the combustion exhaust gas I have. In the first embodiment, the water-cooled cooler 22 is configured as a reformer exhaust gas scrubber (wet scrubber) 22. The cooling heat exchanger 24 is configured as a clean water cooling heat exchanger 24. Moreover, the deaeration device 27 is configured as a cooling tower, a decompression vessel, or a decompression pump. The precooler 21 is configured as a reformer exhaust gas cooling heat exchanger 21. Furthermore, the directly reduced iron production facility 40a of Embodiment 1 is provided with a desulfurization tower 25 for desulfurizing the reformer fuel.

The precooler 21 is located upstream of the water-cooled cooler 22 (reformer exhaust gas scrubber 22), specifically, between the reformer 6 and the reformer exhaust gas scrubber 22 in the flow of combustion exhaust gas discharged from the reformer 6. Are arranged to be. The deaeration device is disposed downstream of the cooling heat exchanger 24 (clean water cooling heat exchanger 24) in the flow of water (return water) discharged from the water-cooled cooler 22.

In the first embodiment, combustion exhaust gas containing water vapor discharged from the reformer 6 that has been directly released to the atmosphere is preliminarily cooled by the reformer exhaust gas cooling heat exchanger 21 (preliminary cooling step), and then passed through the reformer exhaust gas scrubber 22. The reformer exhaust gas scrubber 22 directly contacts the combustion exhaust gas with water to directly cool the combustion exhaust gas (direct cooling process), and the reformer exhaust gas scrubber 22 condenses the moisture in the cooled gas to reduce the moisture in the gas. Collect (collection process).

The water (return water) discharged from the reformer exhaust gas scrubber 22 is introduced into the clean water cooling heat exchanger 24 and indirectly cooled in the clean water cooling heat exchanger 24 (water indirect cooling step). Thereafter, the return water is stored in the water sump 38, introduced into the deaerator 27, and deaerated (deaeration step). Thereafter, when further cooling is required to circulate and use the return water, the auxiliary cooling tower 26 can be used to assist the cooling.

The gas cooled by the reformer exhaust gas scrubber 22 is introduced into the reformer exhaust gas cooling heat exchanger 21 and the clean water cooling heat exchanger 24 by the exhaust gas suction fan 23. As a result, the gas cooled by the reformer exhaust gas scrubber 22 is used for preliminary cooling of the combustion exhaust gas in the reformer exhaust gas cooling heat exchanger 21 and is discharged from the reformer exhaust gas scrubber 22 in the clean water cooling heat exchanger 24. Used to cool return water. Further, the gas discharged from the clean water cooling heat exchanger 24 joins with the gas introduced into the reformer exhaust gas cooling heat exchanger 21 via the exhaust gas suction fan 23 and is introduced into the reformer exhaust gas cooling heat exchanger 21. Thereafter, the reformer exhaust gas cooling heat exchanger 21 cools the combustion exhaust gas to exchange heat, and then is released to the atmosphere.

In the directly reduced iron manufacturing facility 40a and the manufacturing method according to the first embodiment, the coolant of the clean water cooling heat exchanger 24 uses water other than circulating water that is circulated and used in the directly reduced iron manufacturing facility 40a. The circulating water is the water that is collected in the hot water sump 19 and the water sump 38 and cooled as necessary, and then supplied to each part of the production facility 40a (each scrubber 4, 9, 22, each cooler 8, 11). It is. Specifically, a gas or seawater not shown can be used as the refrigerant. In addition, at least a part of the gas cooled by the water-cooled cooler and the atmosphere are used as the refrigerant of the clean water cooling heat exchanger 24. Note that it is optional to use the gas and air cooled by the water-cooled cooler 22 as the refrigerant of the clean water cooling heat exchanger 24, and when the gas and air cooled by the water-cooled cooler 22 are used. In addition, the gas cooled by the water-cooled cooler 22 and the atmosphere can be selectively used or mixed.

Further, in the directly reduced iron production facility 40a of the first embodiment, the combustion oxidizing gas used for the combustion of the burner 7 of the reformer 6 uses a high oxygen-containing gas adjusted to a higher concentration than the oxygen concentration in the atmosphere. Is preferred. Further, in the directly reduced iron production facility 40a of the first embodiment, the direct water discharged from the coolers 8 and 11 is returned to the water sump 38, and the direct water discharged from the scrubbers 4 and 9 is clarifier. 18 is returned to the hot water sump 19.

As described above, in the first embodiment, the sensible heat of the combustion exhaust gas is reduced by first preliminarily cooling the combustion exhaust gas from the reformer 6 with the reformer exhaust gas cooling heat exchanger 21. Thereafter, most of the moisture is recovered by the reformer exhaust gas scrubber 22. Conventionally, as shown in FIG. 1, the combustion exhaust gas from the reformer 6 is directly discharged from the ejector stack 17 to the atmosphere after heat recovery, or is sucked by a suction fan (not shown) and released to the atmosphere. In this case, the amount of flue gas in the reduced iron per tonne of 1500 Nm ³ ~ 2000 Nm ^3, owns about 20% moisture. In other words, it has a 0.24m ³ ~ 0.32m ³ about of moisture per reduced iron one ton. However, in the first embodiment, by having the above configuration, most of the water of about 0.24 m ³ to 0.32 Nm ³ per ton of reduced iron contained in the combustion exhaust gas can be recovered and recycled by the reformer exhaust gas scrubber 22. .

In the first embodiment, the return water of the reformer exhaust gas scrubber 22 including the collected condensed water is indirectly cooled by the clean water cooling heat exchanger 24. Since the return water is heated by the sensible heat of the flue gas and the latent heat due to condensation of water, the amount of recovered water is equal to the amount of heat that cools the sensible heat of the flue gas even if the return water is directly cooled and circulated by a cooling tower etc. More water is consumed by evaporation. However, since the first embodiment has the above-described configuration, it is possible to separate and recover clean water without consuming water by evaporation during cooling necessary for circulating and using water. .

Also, the temperature of the exhaust gas sucked through the reformer exhaust gas scrubber 22 depends on the amount of water supplied to the reformer exhaust gas scrubber 22 and the water temperature regardless of the outside air temperature, and therefore has a constant cooling capacity regardless of the region and season. Therefore, it is particularly effective in high temperature areas and high temperature seasons.

In addition, the clean water cooling heat exchanger 24 can introduce the atmosphere in addition to introducing the gas cooled by the reformer exhaust gas scrubber 22 as shown in FIG. As a result, in an area where the atmospheric temperature is lower than the temperature of the gas at the outlet of the reformer exhaust gas scrubber 22 or in winter, the return water of the reformer exhaust gas scrubber 22 can be cooled more efficiently by sucking the atmosphere, and a large amount of clean water can be obtained. It can be recovered.

In general, in the directly reduced iron production facility 40, a part of the top gas from the reduction furnace 2 is used as the fuel for the reformer 6, and the circulating gas containing the top gas prevents carbon deposition on the reformer 6 catalyst. Therefore, the hydrogen sulfide (H ₂ S) concentration is controlled to be constant. Therefore, sulfur oxide (SO _x ) is contained in the combustion exhaust gas. Therefore, when this combustion exhaust gas is cooled below the acid dew point, it leads to corrosion of equipment such as a heat exchanger.

However, in the first embodiment, a line directly introducing the gas at the outlet of the reformer exhaust gas scrubber 22 and a gas heated by the clean water cooling heat exchanger 24 are mixed, and the gas on the surface of the reformer exhaust gas cooling heat exchanger 21 is mixed. It is possible to adjust the temperature so as not to condense the acid. Therefore, the problem of corrosion on the surface of the reformer exhaust gas cooling heat exchanger 21 can be solved.

In addition, in order to prevent this corrosion problem, if the fuel of the reformer 6 is preheated by a preheater (not shown) and then desulfurized by the desulfurization tower 25, it can be cooled to a lower temperature and more water can be recovered. Is possible.

In addition, a combustion oxygen gas in the burner 7 is mixed with a high oxygen-containing gas whose oxygen concentration is higher than the atmospheric oxygen concentration, for example, pure oxygen or a nitrogen-containing gas with a high oxygen concentration equivalent thereto (not shown), and combustion oxygen The water vapor partial pressure in the combustion exhaust gas can be increased by increasing the oxygen concentration of the contained gas. By cooling the combustion exhaust gas having a high water vapor partial pressure with the reformer exhaust gas scrubber 22, the recovery efficiency of moisture from the combustion exhaust gas is increased, and the moisture in the combustion exhaust gas can be separated and recovered more efficiently.

Moreover, in this Embodiment 1, the water of the reformed gas cooler 8, the seal gas cooler 11, and the reformer exhaust gas scrubber 22 that is not in direct contact with the iron ore powder or the calcium coating powder is used as the top gas scrubber 4, the cool link gas. The clean water system is made independent from the water system that is in direct contact with the iron ore powder or calcium coating powder such as the scrubber 9 and the wet dust collector not shown.

Therefore, the water quality of this clean water system is very good, and the surplus water can be used not only as supplementary water for the water system in direct contact with iron ore powder or calcium coating powder, but also as other clean water in the factory .

In the case of cooling with seawater and in a region and period where the atmospheric temperature is low, when the clean water system becomes a completely sealed system, the dissolved gas in the reformed gas cooler 8, the seal gas cooler 11, and the reformer exhaust gas scrubber 22, especially CO, The dissolved amount of CO ₂ increases, leading to a decrease in PH and an increase in CO concentration in the pit, which may lead to corrosion and CO accidents. However, the pH of this clean water system is adjusted with chemicals and the like, and a deaeration device 27 is provided, and a part of the return water is deaerated by a cooling tower 27 which is one of the deaeration devices 27 or the deaeration device 27. By evacuating the dissolved gas by depressurizing with a decompression vessel or a decompression pump, which is another one, even a semi-closed system can be circulated and used without any problem. In this case, by installing the degassing device 27 downstream of the flow of the return water of the clean water cooling heat exchanger 24, the water temperature in the degassing device 27 is lowered, and corrosive or harmful gases such as CO and CO _2. Can be efficiently degassed and the water consumption by evaporation can be reduced.

In the first embodiment, the directly reduced iron production facility 40a includes the preliminary cooler 21, the cooling heat exchanger 24, the desulfurization tower 25, the auxiliary cooling tower 26, and the deaeration device 27. The cooling heat exchanger 24, the desulfurization tower 25, the auxiliary cooling tower 26, and the deaeration device 27 are not essential components, and may be provided as necessary.

Moreover, in the said Embodiment 1, although the manufacturing method of direct reduced iron is equipped with the preliminary cooling process, the water indirect cooling process, and the deaeration process, the preliminary cooling process, the water indirect cooling process, and the deaeration process are essential processes. Instead, it is only necessary to provide necessary steps as necessary.

In the first embodiment, the method of cooling the return water of the reformer exhaust gas scrubber 22 has been described. However, the same effect can be obtained by cooling the return water of the reformed gas cooler 8 and the seal gas cooler 11 in the same manner.

In the cooling, the type of heat exchanger is not selected, and a normal shell and tube heat exchanger may be installed, or fins are attached to the piping to increase the heat transfer area and cool the system. .

In addition, when indirectly cooling the equipment cooling water of the closed system not shown here with this clean water (clean water) system cooling water, there is no problem of adhesion such as salinity in the heat exchanger for cooling the equipment cooling water, The effect of reducing maintenance load such as cleaning can also be obtained.

Next, a directly reduced iron manufacturing facility 40b and a manufacturing method according to Embodiment 2 of the present invention will be described with reference to FIG. In the second embodiment, a part of the directly reduced iron production facility 40a of the first embodiment is changed. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. Note that FIG. 3 shows only points that are different from FIG. 2 showing the first embodiment, and illustration of other configurations is omitted. That is, in FIG. 3, the raw material charging conveyor 1, the reduction furnace 2, the cooling zone 3, the top gas scrubber 4, the reformed gas cooler 8, the cooling gas scrubber 9, the cooling gas compressor 10, the seal gas cooler 11, and the seal shown in FIG. The configuration of the gas compressor 12, the hot briquette machine 13, the clarifier 18, the hot water sump 19, the cooling tower 20, and the desulfurization tower 25 is omitted.

In a general direct reduction iron production method, in order to keep the ratio of hydrogen and carbon monoxide (H ₂ / CO ratio) of the reducing gas at a predetermined ratio, the circulating gas is in a water saturated state at a predetermined temperature. The water content in the circulating gas is controlled. At this time, when a rotary lob blower was used, the gas state on the outlet side had to be maintained at a water saturation state of about 80 ° C. For this reason, it is necessary to cool the gas from the gas temperature rising due to adiabatic compression accompanying the pressure increase of the circulating gas to the saturation temperature, leading to an increase in the heat load on the water system.

However, in the second embodiment, the process gas compressor 5 is not a water-sealed / cooled rotary lob blower but a dry turbo blower. In the case of using a dry-type turbo blower, water for sealing and cooling is not sprayed, so the energy at the time of adiabatic compression is used for increasing the temperature of the gas, and the energy can be used efficiently.

Further, the directly reduced iron manufacturing apparatus 40b of the second embodiment includes a boiler 29 and a boiler supply water heat exchanger 28. The boiler 29 is arranged so that the combustion exhaust gas discharged from the reformer 6 can be effectively recovered from the combustion exhaust gas until the combustion exhaust gas is introduced into the reformer exhaust gas scrubber 22. Boiler supply water to be supplied to the boiler 29 is preheated with return water from the reformer exhaust gas scrubber 22 in the boiler supply water heat exchanger 28. And steam is manufactured from the boiler feed water preheated with the boiler 29 installed in the off gas, and the steam is mixed with the circulating top gas (process gas) whose pressure is increased on the outlet side of the primary process gas preheater 15. The amount of water at the entrance of the reformer 6 is controlled. This makes it possible to effectively utilize the energy of adiabatic compression in the process gas compressor and adjust the water content.

In the second embodiment, even if the process gas compressor 5 has the same capacity, there is no need to adjust the amount of water at the inlet of the compressor 5, and the temperature of the top gas scrubber 4 is lowered as much as possible to reduce the saturated water vapor component. As a result, 5% or more of reformed gas can be produced and heated to about 200 ° C. by adiabatic compression, which leads to an improvement in total thermal efficiency.

Further, since no extra cooling water is required for saturation and preheating is performed with the return water of the reformer exhaust gas scrubber 22 and heat recovery is performed with the newly installed boiler 29, the heat of the return water of the reformer exhaust gas scrubber 22 is obtained. The load is reduced, leading to an increase in the amount of recovered water from off-gas.

In the second embodiment, the boiler 29 is installed for moisture control, and steam is generated and controlled by the input amount. However, the return water of the reformer exhaust gas scrubber 22 is sprayed on the outlet side of the primary process gas preheater 15. You may control.

Next, a directly reduced iron production facility 40c according to Embodiment 3 of the present invention will be described with reference to FIG. Embodiment 3 is a directly reduced iron production facility and method of the present invention, particularly a directly reduced iron production facility and method for briquetting directly reduced iron. Embodiment 3 has shown the case where the water vapor containing gas containing the vapor | steam which generate | occur | produces when water is sprayed on hot briquette iron (HBI) as a gas source containing water vapor | steam, and HBI is cooled is processed. In the third embodiment, a part of the directly reduced iron production facility 40a of the first embodiment is extracted and changed. That is, in FIG. 4, the top gas scrubber 4, the reformer 6, the burner 7, and the exhaust gas treatment equipment, the reformed gas cooler 8, the seal gas cooler 11, the seal gas compressor 12, and the desulfurization tower 25 shown in FIG. It is omitted. Moreover, about the structure with which the manufacturing equipment 40c of the direct reduction iron of Embodiment 3 is provided, about the part of the structure demonstrated in the said Embodiment 1 and 2, the description is abbreviate | omitted by attaching | subjecting the same code | symbol in FIG.

The direct reduced iron manufacturing facility 40c of Embodiment 3 includes a reduction furnace 2 for reducing raw materials, a raw material charging conveyor 1 for charging raw materials into the reduction furnace 2, and hot briquettes for manufacturing hot briquette iron from high-temperature direct reduced iron. The machine 13 and the briquette quench conveyor 33 which conveys the manufactured hot briquette iron are provided. Further, the directly reduced iron production facility 40c indirectly cools by sucking a steam-containing gas containing water vapor generated when water is sprayed on the briquette quench conveyor 33 to cool the hot briquette iron. A cooling condenser 34 that condenses and recovers moisture, and a water-cooled cooler that further directly cools the gas discharged from the cooling condenser 34 and condenses and recovers moisture in the gas discharged from the cooling condenser 34. (Wet scrubber) 22.

In Embodiment 3, as water sprayed on HBI, that is, spray water used for cooling HBI, water in which alkaline components such as calcium (Ca) and magnesium (Mg) are concentrated more than the concentration in the supplementary water, that is, a reverse osmosis membrane, etc. The desalinization waste water in which impurities are concentrated when impurities such as salinity are removed from the blow-down water using the desalting apparatus 32 is used.

Although part of the illustration is omitted in FIG. 4, the directly reduced iron production facility 40 c includes the top gas scrubber 4, the reformed gas cooler 8, and the seal gas cooler 11 as in the first embodiment of FIG. 2. The top gas scrubber 4 and the return water (direct contact water) 30 from the wet dust collector provided at the dust generation location in the facility (not shown) and the clean water system shown in Embodiment 1 (FIG. 2) are separate systems. Otherwise, the return water 30 from the reformed gas cooler 8 and the seal gas cooler 11 is returned to the clarifier 18. Here, a chemical such as an aggregating agent is added, and the solid content is separated by settling. The water after the sedimentation process is collected in a hot water sump 19 and cooled by an indirect cooler such as a cooling tower 20 or a seawater heat exchanger (not shown). Thereafter, the water is supplied to the top gas scrubber 4 and the cooling gas scrubber 9 in the same manner as in the first embodiment (FIG. 2) for circulation.

Here, in the water circulating directly in the reduced iron production facility 40c, impurities such as salt are mixed not only from makeup water but also from iron ore powder or calcium coating powder. Therefore, even if the consumption of water due to evaporation is prevented, a certain amount of blow-down is required, resulting in the need for a large amount of makeup water, and it has been difficult to significantly reduce the consumption of water.

However, in the third embodiment, the blowdown water can be treated and the water can be purified and recovered. Specifically, water cooled by the cooling tower 20 or a seawater heat exchanger (not shown) is circulated and used, but a part thereof is blown down.

The circulating water necessary for the blowdown is passed through the filter 31 and the treated water treated by the filter 31 is put into a desalination treatment device 32 such as a reverse osmosis membrane. The filtered water supplied to the desalting apparatus 32 is separated into desalted water that does not contain impurities and desalted waste water that is concentrated with impurities.

At this time, the amount of water consumed during filtration can be eliminated by returning the filtered wastewater to the clarifier 18. Further, the makeup water can be reduced by returning the desalinated water to the cold water sump 35.

In Embodiment 3, the desalinization waste water with concentrated impurities is sprayed on the hot compression briquette (HBI) on the briquette quench conveyor 33 to cool the HBI. This eliminates the need for normal HBI spray water and reduces water consumption.

Also, since this HBI is gradually cooled by the heat of evaporation of water, impurities adhere to the HBI, and mainly water evaporates.

The main components of impurities in this desalination treatment wastewater are alkaline components such as calcium (Ca), magnesium (Mg), and sodium (Na), and these are in the electric melting furnace, which is the next step of the production method of directly reduced iron. Since it is also an additive, it contributes to the reduction of the additive in electric furnace melting | dissolving by making it adhere to HBI of a product. Therefore, the manufacturing method of Embodiment 3 has an advantage that impurities in water can be effectively used as valuable resources.

On the other hand, the water vapor-containing gas containing the water vapor evaporated by the briquette quench conveyor 33 is introduced into the cooling condenser 34. In this cooling condenser 34, the water vapor-containing gas is indirectly cooled with a refrigerant other than circulating water such as air or seawater (gas indirect cooling step), condensed, and recovered as clean water. By providing a mist removing device (not shown) on the outlet side of the cooling condenser 34, the clean water can be recovered more effectively. Clean water recovered by the cooling condenser 34 is stored in a water sump 38.

Further, by passing the gas exiting the cooling condenser 34 through the wet scrubber 22, the gas is further directly cooled by the wet scrubber 22 (direct cooling step), and moisture in the cooled gas is condensed and recovered (recovery step). ). Thereby, the water | moisture content in gas can be collect | recovered to the saturated water vapor pressure of the temperature substantially the same as the water temperature sprayed with the wet scrubber 22. FIG.

Also, in the third embodiment, similarly to the first embodiment, the cooling of the gas containing water vapor in the cooling condenser 34 can be used by mixing the atmosphere and the gas cooled by the wet scrubber 22.

As a result, the air can be condensed more efficiently by introducing a large amount of gas cooled by the wet scrubber 22 when the atmospheric temperature is low such as in winter and when the atmospheric temperature is high such as in summer. ing.

Further, in the directly reduced iron manufacturing facility 40c and the manufacturing method of the third embodiment, the return water of the wet scrubber 22 is used as the clean water cooling heat exchanger 24 in the same manner as the direct reduced iron manufacturing facility 40a and the manufacturing method of the first embodiment. Indirect cooling with. As a result, in the same way as in the first embodiment, when cooling is necessary for circulating and using water, water is not consumed by evaporation, and clean water can be separated and recovered. The return water cooled by the clean water cooling heat exchanger 24 is stored in the water sump 38.

Further, by passing a refrigerant such as air through the cooling condenser 34 through the clean water cooling heat exchanger 24, the total heat recovery amount can be increased, and the water consumption can be more effectively reduced. Is possible.

When the gas cooled by the wet scrubber 22 is not used in the cooling condenser 34 and the clean water cooling heat exchanger 24, it is released to the atmosphere. The gas supplied from the clean water cooling heat exchanger 24 to the cooling condenser 34 is discharged into the atmosphere after heat exchange is performed by cooling the gas containing water vapor in the cooling condenser 34.

Embodiment 3 shows the case where the desalinization wastewater is sprayed on the HBI. However, a part of the desalination wastewater may be added from the top of the furnace together with the raw iron ore and fired pellets. In this case, moisture evaporates in the upper part of the reduction furnace 2, and impurities adhere to the raw material and are discharged together with the product.

The evaporated water is collected as clean water by the top gas scrubber 4 (not shown), and the same effect as water spray on the HBI is obtained.

Impurities adhering to raw materials such as iron ore or calcined pellets are the main components of alkaline components and valuable materials for melting in electric furnaces, and Ca and Mg, which have a high melting temperature, are the main components. It can be reduced at high temperatures and contributes to the improvement of productivity.

In the third embodiment, the case where the desalinization wastewater is introduced into the reduction furnace 2 together with the cooling of the HBI and the raw material is described. However, the present invention is not limited to this, and the mixed water for the slaked lime slurry used when applying the calcium coating may be used. good.

Moreover, when the pellet plant is adjacent, it may be sprayed on the pellet on the outlet side of the pellet cooler. Even in this case, since the surface of the raw material adheres Ca or Mg to the pellet surface, high-temperature operation during reduction is possible, and evaporated water vapor can be recovered as clean water.

Next, a directly reduced iron production facility 40d according to Embodiment 4 of the present invention will be described with reference to FIG. In the fourth embodiment, a part of the directly reduced iron production facility 40a of the first embodiment is changed. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In FIG. 5, only the points that are changed from FIG. 2 showing the first embodiment are shown, and illustration of other configurations is omitted. That is, in FIG. 5, the raw material charging conveyor 1, the reduction furnace 2, the cooling zone 3, the top gas scrubber 4, the reformed gas cooler 8, the cooling gas scrubber 9, the cooling gas compressor 10, the seal gas cooler 11, and the seal shown in FIG. The configuration of the gas compressor 12, the hot briquette machine 13, the clarifier 18, the hot water sump 19, the cooling tower 20, and the desulfurization tower 25 is omitted.

In the fourth embodiment, in the flow of combustion exhaust gas from the reformer 6, water containing impurities between the precooler (reformer exhaust gas cooling heat exchanger) 21 and the water-cooled cooler (reformer exhaust gas scrubber) 22 ( An evaporator 36 for spraying blowdown water) and a dry dust collector 37 for removing impurities are provided. Then, blowdown water is sprayed on the combustion exhaust gas in the evaporator 36 (spraying process), and after the blowdown water is evaporated, impurities are removed (removal process) by the dry dust remover 37. Thereafter, the water is passed through a wet reformer exhaust gas scrubber 22, and the water contained in the combustion exhaust gas is cleaned together with the water in the blow-down water, and then recovered.

The combustion exhaust gas of the reformer 6 has a heat quantity of about 200 ° C. to 400 ° C. even after preheating of the combustion oxidizing gas and fuel. Using this excess heat amount, the blow-down water is evaporated by the evaporator 36 and then passed through the dry dust collector 37 to separate and remove impurities such as solids and salt in the blow-down water.

By cooling the combustion exhaust gas from which the salt and solids have been removed by the reformer exhaust gas scrubber 22, the moisture in the blowdown water can be recovered in addition to the water originally contained in the combustion exhaust gas.

In this directly reduced iron manufacturing method, the heat balance of the reformer exhaust gas scrubber 22 including the sprayed water sprayed on the evaporator 36 is the same as when the spray is not sprayed on the evaporator 36. It is extremely effective.

The blow-down water may be a further concentrated desalted water after the desalination treatment facility, or may be directly used blow-down water from the circulating water without providing a desalination treatment facility.

Further, the type of dry dust collector 37 is not selected, and for example, a cyclone dust collector, an electric dust collector, a filter cloth dust collector, or the like may be used.

Further, by passing the recovered water through the deaeration device 27, toxic and dissolved components such as CO, CO ₂ and ammonia can be removed and recovered as completely clean water.

Further, the arrangement of the preheaters 14, 15, 16 and the reformer exhaust gas cooling heat exchanger 21 is not limited to FIG. 5. For example, the reformer exhaust gas cooling heat exchanger 21 may be arranged downstream of the dry dust collector 37. good. In this case, oxidation in dry precipitator inlet 37 side calcium-calcium hydroxide, by blowing a material containing an alkali metal such as calcium carbonate, it is possible to remove reacted with an acid such as SO _x in the exhaust gas. As a result, the acid dew point of the exhaust gas can be lowered, so that the corrosion on the surface of the heat exchanger 21 described above can be prevented and the heat can be recovered to a low temperature.

The first to fourth embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

For example, in Embodiments 1, 2, and 4 described above, an example in which moisture is recovered from the combustion exhaust gas of the reformer 6 is shown. However, the present invention is not limited to this example. The water can be recovered and purified by spraying and recovering water containing impurities such as alkali components and solids on the exhaust gas while recovering.

By combining the above Embodiments 1, 2, and 4 with a conventional method of cooling circulating water with seawater or the like, direct reduced iron production equipment (ironworks), or a pellet plant and direct reduced iron production equipment It is possible to operate a steelworks that does not require supply water in the integrated steelworks that it has. Therefore, it is particularly effective in areas where it is difficult to supply good quality water.

In addition, when water that contains a large amount of salt or impurities that cannot normally be used as industrial water is supplied in excess of the required amount of water at steelworks, the surplus can be supplied as clean water. It can also be used as a water purification process.

Specific examples of water reduction are shown below. When Embodiment 1 and Embodiment 3 are combined, the return water from the reformer exhaust gas scrubber 22 is cooled with a mixed gas of the gas discharged from the reformer exhaust gas scrubber 22 and the atmosphere, and a degassing device 27 is provided in the line. in, it can be recovered from the direct reduction iron per ton of about 0.2m ³ salinity of 0.3m ^3, as clean water that does not contain solids.

When the capacity of the filtration device 31 and the desalination treatment device 32 described in Embodiment 3 is about 0.3 m ³ per ton of directly reduced iron, a blow down of 0.3 m ³ per ton of directly reduced iron is performed. As a result, it is possible to maintain good water quality even if impurities are mixed in from iron ore powder or calcium coating powder.

At this time, since the treated water recovered from the desalting treatment apparatus 32 is clean water, the treated water can be used as clean water containing no salt and solids as described above.

Further, when the waste water from the desalination treatment device 32 is sprayed on the HBI to cool the HBI and the generated steam is recovered by indirect cooling, or sprayed on the exhaust gas, the dry dust collector 37 collects the salt and solids. When the water is recovered by cooling after removing the water, the total required water amount is about 1/4 or less.

In addition to this, for example, if the return water from the top gas scrubber 4 is indirectly cooled with seawater or air, it is possible not only to supply makeup water but also to supply surplus clean water. It will be a facility for producing directly reduced iron that can contribute to environmental conservation without the need for wastewater.

1 Raw material loading conveyor 2 Vertical reduction furnace 3 Vertical reduction furnace cooling zone (cooling zone)
4 Top Gas Scrubber 5 Process Gas Compressor 6 Reformer 7 Burner 8 Reforming Gas Cooler 9 Cooling Gas Scrubber 10 Cooling Gas Compressor 11 Seal Gas Cooler 12 Seal Gas Compressor 13 Hot Briquette Machine 14 Combustion Air Preheater 15 Primary Process Gas Preheater 16 Secondary process gas preheater 17 Ejector stack 18 Clarifier 19 Hot water sump 20 Cooling tower 21 Precooler (reformer exhaust gas cooling heat exchanger)
22 Water-cooled cooler (reformer exhaust gas scrubber, wet scrubber)
23 Exhaust gas suction fan 24 Cooling heat exchanger (clean water cooling heat exchanger)
25 Desulfurization tower 26 Auxiliary cooling tower 27 Deaerator (cooling tower, decompressor, decompression vessel, decompression pump)
28 Boiler supply water heat exchanger 29 Boiler 30 Return water 31 Filter 32 Desalination processing device 33 Briquette quench conveyor 34 Cooling condenser 35 Cold water sump 36 Evaporator 37 Dry dust collector 38 Water sump 40, 40a, 40b, 40c, 40d Direct Production facilities for reduced iron

Claims (19)

A direct reduced iron production facility that directly produces reduced iron by bringing a raw material and a reducing gas into contact with each other in a reduction furnace,
An externally heated reformer that produces a reducing gas to reduce the raw material;
And a water-cooled cooler that directly cools the combustion exhaust gas containing water vapor discharged from the reformer and condenses and recovers the moisture in the combustion exhaust gas. The facility for producing directly reduced iron according to claim 1, wherein the oxidizing gas for combustion supplied to the reformer is a high oxygen-containing gas adjusted to a higher concentration than the atmospheric oxygen concentration. The precooler which preliminarily cools the combustion exhaust gas with at least a part of the gas cooled by the watercooled cooler is further provided between the reformer and the watercooled cooler. The facility for producing directly reduced iron according to 2. Directly reduced iron is produced by bringing a raw material and a reducing gas into contact with each other in a reducing furnace, and directly briquetting the directly reduced iron,
A hot briquette machine that produces hot briquette iron from high temperature direct reduced iron,
A briquette quench conveyor that conveys the manufactured hot briquette iron;
Cooling condensation that sucks and contains water vapor-containing gas containing water vapor generated when water is sprayed and cooled on hot briquette iron on the briquette quench conveyor to condense and recover water in the water-containing gas. And
A water-cooled cooler that further directly cools the gas discharged from the cooling condenser and condenses and recovers moisture in the gas discharged from the cooling condenser. production equipment. 5. The directly reduced iron production facility according to claim 4, wherein the water sprayed on the hot briquette iron is water in which an alkali component is concentrated to a concentration equal to or higher than the makeup water concentration. The direct according to any one of claims 1 to 3, further comprising an evaporator for spraying water containing impurities and a dry dust collector for removing impurities upstream of the water-cooled cooler. Production facilities for reduced iron. The cooling heat exchanger according to any one of claims 1 to 6, further comprising a cooling heat exchanger that indirectly cools the return water of the water-cooled cooler other than circulating water that is circulated and used in the manufacturing facility. Direct reduction iron production facility. The direct reduced iron production facility according to claim 7, wherein at least a part of the gas cooled by the water-cooled cooler is used as the refrigerant of the cooling heat exchanger. A degassing device for degassing the return water of the water-cooled cooler;
The said deaeration apparatus is provided in the downstream of the said cooling heat exchanger, The manufacturing apparatus of the direct reduced iron of Claim 7 or 8 characterized by the above-mentioned. 10. The refrigerant of the cooling heat exchanger is used by selectively using or mixing the gas cooled by the water-cooled cooler and the atmosphere. Equipment for manufacturing directly reduced iron as described. A method for producing directly reduced iron in which raw material and reducing gas are brought into contact with each other in a reduction furnace to produce directly reduced iron,
A direct cooling process in which combustion exhaust gas containing water vapor discharged from an externally heated reformer that produces a reducing gas for reducing the raw material is directly cooled by a water-cooled cooler;
A method for producing directly reduced iron, characterized in that the water-cooled cooler comprises a recovery step of condensing and recovering moisture in the cooled gas. The method for producing directly reduced iron according to claim 11, wherein the oxidizing gas for combustion supplied to the reformer is a high oxygen-containing gas adjusted to a higher concentration than the oxygen concentration in the atmosphere. The direct cooling process according to claim 11 or 12, further comprising a pre-cooling step of pre-cooling the combustion exhaust gas with at least a part of the gas cooled by the water-cooled cooler before the direct cooling step. A method for producing reduced iron. Directly reduced iron is produced by bringing a raw material and a reducing gas into contact with each other in a reduction furnace, and the directly reduced iron is briquetted hot.
Indirect cooling of steam-containing gas, including water vapor, generated when spraying and cooling hot briquette iron produced from high-temperature direct reduced iron with water whose alkali components are concentrated to a concentration higher than the makeup water concentration. Gas indirect cooling process to
A direct cooling step of directly cooling the gas cooled in the gas indirect cooling step with a water-cooled cooler;
A method for producing directly reduced iron, characterized in that the water-cooled cooler comprises a recovery step of condensing and recovering moisture in the cooled gas. Before the direct cooling step, spraying water containing impurities to the combustion exhaust gas,
The method for producing directly reduced iron according to any one of claims 11 to 13, further comprising a removing step of removing impurities after the spraying step. A water indirect cooling step of indirectly cooling the return water of the water-cooled cooler;
The method for producing directly reduced iron according to any one of claims 11 to 15, wherein, in the indirect water cooling step, water other than circulating water that is circulated and used in the directly reduced iron production facility is used as a refrigerant. . The method for producing directly reduced iron according to claim 16, wherein in the indirect water cooling step, at least a part of the gas cooled by the water-cooled cooler is used as a refrigerant. The method for producing directly reduced iron according to claim 16 or 17, further comprising a degassing step of degassing the return water of the water-cooled cooler after the water indirect cooling step. 19. The water indirect cooling step, wherein the gas cooled by the water-cooled cooler and the atmosphere are selectively used or mixed for use as a refrigerant. Of direct reduced iron production.

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