Storage and transportation system and method for preventing spontaneous combustion of direct reduced iron

Abstract

The invention discloses a storage and transportation system and method for preventing spontaneous combustion of direct reduced iron, and the storage and transportation system comprises a discharge buffer tank, a passivation chamber and a storage bin. The storage and transportation method comprises the following steps: directly reduced iron (DRI) is discharged from the discharge buffer tank and enters the passivation chamber through the first guide pipe for gas phase passivation, and the passivated DRI is sent out of the passivation chamber along with the first conveyor belt and is sent into the storage bin through the second guide pipe; in the storage bin, heat is discharged in time through the gravity assisted heat pipe, the temperature, the oxygen concentration, the hydrogen concentration and the humidity of the storage bin are monitored in real time, and when the carbon monoxide concentration exceeds 24 ppm, the hydrogen concentration exceeds 10000 PPM, the temperature exceeds 65 DEG C or the air humidity exceeds 50%, the system automatically gives an alarm. According to the method, spraying passivation is firstly carried out on the DRI before storage, so that an oxide film can be formed on the surface of the DRI, oxidation in the storage process is reduced, heat can be dissipated in time during storage, various parameters can be monitored in real time, and storage safety is guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to a storage and transportation system and method for preventing spontaneous combustion of direct reduced iron (DRI). Background Technology

[0002] Hydrogen, as an emerging strategic clean reducing agent and energy carrier, boasts abundant resources, high thermal efficiency, and high energy density. Employing vertical shaft furnace reduction technology, using hydrogen instead of carbon-based reducing agents for pellet reduction, can address carbon emissions at their source and is a crucial pathway to achieving green steel production.

[0003] The gas-based shaft furnace reduction process involves reducing iron ore to metallic iron using gases and other reducing agents besides coke, below the iron ore's melting temperature. The reduction product is called direct reduced iron (DRI), which, due to its loss of oxygen and the formation of numerous microporous structures resembling a sponge, is also known as sponge iron. It is a high-quality raw material for short-process electric arc furnace steelmaking. However, DRI's inherent oxidation reaction makes it prone to secondary oxidation with oxygen-containing media such as air and water, releasing large amounts of latent chemical heat and hydrogen. This poses a certain risk of spontaneous combustion and explosion, which can severely compromise the safety of the entire production process.

[0004] Currently, in the production process of direct reduced iron (DRI), it is common practice to transport it to designated storage silos by truck. During this transportation, DRI is highly susceptible to exposure to the atmosphere, leading to re-oxidation and a significant decrease in metallization rate. Simultaneously, this process may involve the release of hazardous gases such as carbon monoxide (CO) and hydrogen (H2). Furthermore, when large quantities of DRI accumulate in storage silos, the heat generated by the material's own oxidation, which is difficult to dissipate, can easily cause a localized or overall temperature rise, significantly increasing the safety risk of spontaneous combustion or even explosion. Therefore, there is a need to provide an economical and convenient method for the storage and transportation of direct reduced iron to prevent spontaneous combustion accidents. Summary of the Invention

[0005] The purpose of this invention is to provide a storage and transportation system and method for preventing spontaneous combustion of direct reduced iron. The system combines in-plant transportation with passivation and timely heat dissipation during storage to prevent spontaneous combustion of direct reduced iron, while reducing on-site operations by staff during storage and transportation and ensuring personal safety.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: On one hand, this invention discloses a storage and transportation system for preventing spontaneous combustion of direct reduced iron, characterized in that: it includes a discharge buffer tank, a passivation chamber, and a storage silo; a first conveyor belt is provided in the passivation chamber, and a first guide pipe is provided between the discharge buffer tank and the inlet end of the first conveyor belt; passivation gas nozzles are evenly distributed above the first conveyor belt in the passivation chamber; the storage silo is divided into multiple material compartments by partition walls, and at least one gravity heat pipe is installed in each material compartment; carbon monoxide concentration detectors, hydrogen concentration detectors, thermocouples, humidity detectors, and level gauges are also installed on the partition walls of the material compartments; a material distribution and conveying device is provided in the storage silo, and a second guide pipe is provided between the outlet of the first conveyor belt and the inlet of the material distribution and conveying device.

[0007] Furthermore, the material distribution and conveying device includes a second conveyor belt that passes through multiple material compartment partitions, and a plow-type unloader is provided on the second conveyor belt at the position corresponding to each material compartment.

[0008] Furthermore, a high-definition camera is installed on the upper part of the partition wall of the material compartment.

[0009] Furthermore, multiple thermocouples are provided and installed at different heights on the material compartment partition wall.

[0010] Furthermore, electric sealing caps are installed at the outlets of the first and second feed tubes.

[0011] Furthermore, a forced exhaust fan is also installed on top of the material compartment.

[0012] Furthermore, an oxygen concentration detector is installed in the passivation chamber and / or the material cell.

[0013] On the other hand, the present invention also discloses a storage and transportation method for preventing spontaneous combustion of direct reduced iron based on the above-mentioned storage and transportation system, comprising the following steps: (1) Direct reduced iron is discharged from the discharge buffer tank, the first conveyor belt in the passivation chamber is started, and at the same time the gas nozzle in the passivation chamber is opened to introduce oxygen-nitrogen mixture with an oxygen concentration of 3%-5% for blowing. (2) When the foremost direct reduced iron moves to the exit end of the first conveyor belt, the first conveyor belt stops rotating; the direct reduced iron remains on the first conveyor belt for passivation; (3) When the preset passivation time is reached, the first conveyor belt starts and sends out the passivated direct reduced iron, which is then sent into the storage bin through the second guide pipe and distributed to each material compartment by the material distribution and conveying device. (4) In the storage silo, heat is discharged in time through gravity heat pipes, and the carbon monoxide concentration, hydrogen concentration, temperature and air humidity of the storage silo are monitored in real time. When the carbon monoxide concentration exceeds 24ppm, the hydrogen concentration exceeds 10000PPM, the temperature exceeds 65℃ or the air humidity exceeds 50%, the system will automatically alarm.

[0014] Furthermore, in step (3), if there is still a passivation production plan after all the direct reduced iron in the passivation chamber has been sent out, then the process will return to step (1) for execution.

[0015] Furthermore, in step (4), when the system automatically alarms, it automatically turns on the forced exhaust fan set on top of the material grid for ventilation and notifies manual intervention.

[0016] Compared with existing technologies, the advantages of this invention are: A passivation chamber is constructed to passivate the direct reduced iron before storage through vapor-phase passivation during transport, enabling the formation of an oxide film on its surface and reducing oxidation during subsequent storage. In the storage chamber, gravity heat pipes promptly dissipate heat and monitor various parameters such as carbon monoxide concentration, hydrogen concentration, temperature, and air humidity in real time, ensuring storage safety.

[0017] Specifically, a heat pipe working mechanism is used to promptly remove heat from the direct reduced iron (DRI) pile within the silo, preventing heat accumulation that could lead to spontaneous combustion. Simultaneously, it reduces oxygen infiltration caused by air cooling, which can exacerbate re-oxidation. Multi-point monitoring of temperature, oxygen concentration, and hydrogen concentration, linked with forced draft fans, enables intelligent control in emergency situations, reducing on-site operations by staff during storage and transportation, and ensuring the safe and stable storage and transportation of DRI. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the system of the present invention.

[0020] Figure 2 This is a schematic diagram of the discharge buffer tank in this invention.

[0021] Figure 3 This is a schematic diagram of the passivation chamber in this invention.

[0022] Figure 4 This is a schematic diagram of the storage silo in this invention. Detailed Implementation

[0023] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0024] like Figure 1-4 As shown, this invention discloses a storage and transportation system for preventing spontaneous combustion of direct reduced iron, comprising a discharge buffer tank 1, a passivation chamber 2, and a storage silo 3. A first conveyor belt 21 is installed within the passivation chamber 2, and a first guide pipe 22 is provided between the discharge buffer tank 1 and the inlet end of the first conveyor belt 21. Passivation gas nozzles 23 and oxygen concentration detectors 24 are evenly distributed above the first conveyor belt 21 within the passivation chamber. The oxygen concentration detector 24 is used to detect the oxygen concentration during the passivation process; when the oxygen concentration exceeds 5%, the system alarms, requiring manual intervention.

[0025] Storage bin 3 is as follows Figure 4 As shown, the material is divided into five compartments 32 by a partition wall 31, and each compartment is equipped with eight gravity heat pipes 33. The lower half of the gravity heat pipe is the evaporation section, used to absorb the heat generated by oxidation in the DRI stack; the upper half is the condensation section, used to release the heat transferred from the lower end, and is also equipped with fins for heat dissipation. The gravity heat pipes are off-the-shelf products, and their application in the material compartments can promptly dissipate the heat generated by oxidation in the direct reduction iron stack.

[0026] The storage compartment walls are equipped with carbon monoxide detectors, hydrogen detectors, thermocouples, humidity detectors, and level gauges. The level gauges are positioned in the middle of the compartment walls, at a height corresponding to the evaporation section of the gravity heat pipes, ensuring timely heat dissipation of the DRI during storage. Multiple thermocouples are installed at intervals on the wall below the level gauges to monitor the temperature at different heights during storage. The carbon monoxide, hydrogen, and humidity detectors monitor the carbon monoxide, hydrogen, and humidity concentrations in real time to ensure a normal storage environment for the DRI. Additionally, each compartment can have an independent access door for easy relocation of the DRI. An oxygen detector can also be installed inside the compartments to monitor the oxygen concentration. An alarm is triggered when the oxygen concentration falls below 19.5%, prohibiting entry and ensuring operational safety.

[0027] A material distribution and conveying device is also installed inside the storage silo 3. A second guide pipe 25 is provided between the discharge port of the first conveyor belt 21 and the inlet of the material distribution and conveying device. Specifically, the material distribution and conveying device includes a second conveyor belt 34 that runs through multiple material compartment partitions, and a plow-type unloader 35 is installed on the second conveyor belt at the position corresponding to each material compartment. The plow-type unloader adopts an existing structure. When direct reduced iron needs to be stored in a certain material compartment, the plow blade of the corresponding plow-type unloader 35 falls down to block the material and guide it to fall to both sides. When it is not necessary to feed material into that material compartment, the plow blade of the plow-type unloader 35 is raised.

[0028] Furthermore, a high-definition camera is installed on the upper part of the partition wall of the material compartment 32 for remote observation of the situation inside the material compartment.

[0029] Electric sealing caps are installed at the outlets of the first guide pipe 22 and the second guide pipe 25. Each electric sealing cap includes a mating cap movably mounted on the outlet of the guide pipe and a push rod motor mounted on the guide pipe body. The push rod motor can open or close the sealing cap. When material needs to be discharged from the first and second guide pipes, the sealing caps open; after discharge is completed, they close.

[0030] Preferably, a forced exhaust fan is also installed on the top of the material compartment for timely heat dissipation and ventilation.

[0031] On the other hand, the present invention also discloses a storage and transportation method for preventing spontaneous combustion of direct reduced iron based on the above-mentioned storage and transportation system, comprising the following steps: (1) The first conveyor belt in the passivation chamber is started, and at the same time, the gas nozzle in the passivation chamber is opened to introduce oxygen-nitrogen mixture with an oxygen concentration of 3%-5% for blowing. The produced direct reduced iron is discharged from the discharge buffer tank and falls onto the first conveyor belt through the first guide pipe for forward conveying.

[0032] (2) When the foremost direct reduced iron moves to the exit end of the first conveyor belt, the first conveyor belt stops rotating; the direct reduced iron remains on the first conveyor belt for passivation. Under normal circumstances, the passivation time is 48 hours. In addition, during the passivation process, the oxygen concentration can be detected by the oxygen concentration detector 24. When the oxygen concentration exceeds 5%, the system alarms and manual intervention is required.

[0033] (3) When the direct reduced iron stays in the passivation chamber for 48 hours, the first conveyor belt is started, which moves the direct reduced iron forward and discharges it from the outlet of the first conveyor belt. It is then sent into the storage bin through the second guide pipe and distributed to each material compartment by the material distribution and conveying device. In actual production, if there is still a passivation production plan after all the direct reduced iron in the passivation chamber has been sent out, the process will continue to return to step (1).

[0034] (4) Heat is promptly dissipated from the storage silo via gravity heat pipes, and the carbon monoxide concentration, hydrogen concentration, temperature, and air humidity are monitored in real time. The system automatically alarms when the carbon monoxide concentration exceeds 24 ppm, the hydrogen concentration exceeds 10,000 PPM, the temperature exceeds 65°C, or the air humidity exceeds 50%. In other words, the system will automatically alarm when any of the parameters of carbon monoxide concentration, hydrogen concentration, temperature, or air humidity is abnormal, ensuring that the storage environment meets the requirements.

[0035] Specifically, when the system automatically alarms, it will automatically turn on the forced exhaust fan set on top of the material compartment for ventilation and notify manual intervention.

[0036] The system and method of this invention enable real-time monitoring of the DRI (Drug-Induced Refrigerant) transport and storage process. Information such as oxygen concentration, carbon monoxide concentration, hydrogen concentration, air humidity, stockpile temperature, and altitude are consistently monitored during storage and transportation, ensuring the safety of the DRI storage and transportation process and the personal safety of personnel.

[0037] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A storage and transportation system for preventing spontaneous combustion of direct reduced iron, characterized in that: Includes discharge buffer tank, passivation chamber and storage silo; The passivation chamber is equipped with a first conveyor belt, and a first guide pipe is provided between the discharge buffer tank and the inlet end of the first conveyor belt; passivation gas nozzles are evenly distributed above the first conveyor belt in the passivation chamber. The storage silo is divided into multiple compartments by partition walls, and each compartment is equipped with at least one gravity heat pipe; the compartment partition walls are also equipped with carbon monoxide concentration detectors, hydrogen concentration detectors, thermocouples, humidity detectors and level gauges; The storage silo is equipped with a material distribution and conveying device, and a second guide pipe is provided between the discharge port of the first conveyor belt and the inlet of the material distribution and conveying device.

2. The storage and transportation system for preventing spontaneous combustion of direct reduced iron according to claim 1, characterized in that: The material distribution and conveying device includes a second conveyor belt that runs through multiple material compartment partitions, and a plow-type unloader is installed on the second conveyor belt at the position corresponding to each material compartment.

3. The storage and transportation system for preventing spontaneous combustion of direct reduced iron according to claim 1, characterized in that: A high-definition camera is installed on the upper part of the partition wall of the material compartment.

4. The storage and transportation system for preventing spontaneous combustion of direct reduced iron according to claim 1, characterized in that: Multiple thermocouples are provided and are installed at different heights on the material compartment partition wall.

5. The storage and transportation system for preventing spontaneous combustion of direct reduced iron according to claim 1, characterized in that: Electric sealing caps are installed at the outlets of the first and second feed pipes.

6. The storage and transportation system for preventing spontaneous combustion of direct reduced iron according to claim 1, characterized in that: A forced exhaust fan is also installed on the top of the material compartment.

7. The storage and transportation system for preventing spontaneous combustion of direct reduced iron according to claims 1-6, characterized in that: An oxygen concentration detector is installed in the passivation chamber and / or the material compartment.

8. A method for preventing spontaneous combustion of direct reduced iron based on the storage and transportation system of any one of claims 1-7, comprising the following steps: (1) The first conveyor belt in the passivation chamber is started, and at the same time the gas nozzle in the passivation chamber is opened to introduce oxygen-nitrogen mixture with an oxygen concentration of 3%-5% for blowing. The direct reduced iron is discharged from the discharge buffer tank and falls onto the first conveyor belt through the first guide pipe and is conveyed forward. (2) When the foremost direct reduced iron moves to the exit end of the first conveyor belt, the first conveyor belt stops rotating; the direct reduced iron remains on the first conveyor belt for passivation; (3) When the preset passivation time is reached, the first conveyor belt starts and sends out the passivated direct reduced iron, which is then sent into the storage bin through the second guide pipe and distributed to each material compartment by the material distribution and conveying device. (4) In the storage silo, heat is discharged in time through gravity heat pipes, and the carbon monoxide concentration, hydrogen concentration, temperature and air humidity of the storage silo are monitored in real time. When the carbon monoxide concentration exceeds 24ppm, the hydrogen concentration exceeds 10000PPM, the temperature exceeds 65℃ or the air humidity exceeds 50%, the system will automatically alarm.

9. The storage and transportation system for preventing spontaneous combustion of direct reduced iron according to claim 8, characterized in that: In step (3), if there is still a passivation production plan after all the direct reduced iron in the passivation chamber has been sent out, then return to step (1) to continue execution.

10. The storage and transportation system for preventing spontaneous combustion of direct reduced iron according to claim 8, characterized in that: In step (4), when the system automatically alarms, it automatically turns on the forced exhaust fan set on top of the material grid for ventilation and notifies manual intervention.

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