Converter steel slag waste heat recovery system

Abstract

The utility model provides a converter steel slag waste heat recovery system, and particularly relates to the technical field of solid waste treatment, the converter steel slag waste heat recovery system uses a phase change ball tank and a slag tank to respectively add phase change balls and the slag tank into a mixing stock bin, and the phase change balls and steel slag are mixed in the mixing stock bin; conveying and heat exchange are synchronously achieved in the rotary conveying device, phase-change core metal in the phase-change balls is gradually converted into a liquid state from a solid state, the steel slag is gradually reduced to the target temperature, then the steel slag and the phase-change balls are conveyed into the solid-solid separation device to be separated, and finally the phase-change balls enter the waste heat recovery device to conduct heat exchange with a medium to release heat. Meanwhile, the internal phase change core metal is gradually converted into a solid state from a liquid state and is conveyed into the mixing bin again through the conveyor, and due to the fact that the phase change balls have good stability, high energy storage density and high heat conductivity, a large amount of heat energy can be efficiently and stably stored; the problem that high-grade waste heat of converter steel slag cannot be efficiently and stably recycled is solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to solid waste treatment technical field especially relates to a converter steel slag waste heat recovery system. BACKGROUND

[0002] Converter steel slag is a waste slag produced in the converter steelmaking process. According to relevant statistical data, the production of converter steel slag in China in 2022 was about 980 million tons.

[0003] The temperature of converter steel slag often reaches 1500℃ or even higher. The tapping process of converter steel slag presents an intermittent characteristic, which is difficult to adapt to the continuous and stable industrial waste heat recovery process, greatly increasing the complexity and instability of the recovery operation. Its composition is complex and variable, covering a variety of metal oxides and other compounds, with significant differences in composition between different batches, making it difficult to develop a unified and efficient recovery strategy. The viscosity of converter steel slag is large, which not only affects its flowability in the treatment process, but also hinders heat transfer and recovery. In addition, the thermal conductivity of converter steel slag is low, meaning that the conduction speed of heat within the steel slag is extremely slow. From the microstructure, the complex mineral composition and crystal structure of converter steel slag lead to a large number of lattice defects, pores and different phase interfaces within it. These factors seriously hinder the heat transfer path, making it difficult for heat to rapidly diffuse from high-temperature areas to low-temperature areas. When trying to recover waste heat from the steel slag through external heat exchange devices, the slow migration of heat within the converter steel slag makes the overall temperature of the converter steel slag drop slowly, which in turn leads to low efficiency of the heat exchange process, making it impossible to extract and transfer a large amount of heat in a short period of time. This low thermal conductivity characteristic also causes local heat accumulation, forming a large temperature gradient within the converter steel slag, further affecting its physical and chemical stability, increasing energy loss and technical difficulty in the treatment process of converter steel slag, and becoming one of the important bottlenecks restricting the efficient recovery of converter steel slag waste heat.

[0004] The existing converter steel slag treatment processes have obvious limitations. The hot splashing method, water quenching method and air quenching method are relatively extensive in the treatment process, and open operation environment is adopted, so that a large amount of dust-containing steam is discharged to the surrounding environment in disorder, which not only causes serious environmental pollution, but also causes a large amount of recoverable heat energy to be wasted. The atmospheric tank type hot stew method realizes the treatment of the steel slag to a certain extent, but the process is time-consuming and long, a large amount of water resources are consumed, the overall treatment efficiency is extremely low, and it is difficult to meet the needs of large-scale industrial production. The roller method has made achievements in equipment and cleaning, and realizes the relative standardization of the treatment process, but the energy consumption is high in actual operation, and the problem of blockage is prone to occur, which seriously affects the continuous and stable operation of the equipment. The roller pressing crushing-pressure hot stew method is a relatively advanced process, which has improved the treatment efficiency compared with the atmospheric hot stew method, and can recover heat energy below 500 DEG C, but dust-containing steam is also generated in the operation process, and a special dust removal system must be provided, which undoubtedly increases the equipment investment and operation cost, and the process still has technical bottlenecks in the waste heat recovery of the high temperature section (1500-500 DEG C), and has not realized effective breakthrough.

[0005] In summary, the existing converter steel slag treatment processes jointly face two key pain points: first, in the field of waste heat recovery in the high temperature section (1500-500 DEG C), the heat energy of the steel slag in this temperature range is not fully utilized, resulting in serious waste of energy; second, steel blocks are often left in the converter steel slag, and the treatment method of directly contacting water with high-temperature converter steel slag has safety hazards, which may cause explosion accidents at any time in industrial production.

[0006] In view of the above serious deficiencies in the current converter steel slag treatment process, in order to realize the sustainable development of the steel industry, improve the energy utilization efficiency and reduce environmental pollution, it is urgent to develop a new and innovative waste heat recovery technology. This technology should be able to overcome the drawbacks of the existing process, effectively fill the gap in the waste heat recovery of the high temperature section, and ensure that the high-grade waste heat resources of the converter steel slag can be efficiently, safely and stably recovered and reused. Practical new type content

[0007] In order to solve the problem that the high-grade waste heat of the steel slag cannot be efficiently and stably recovered, the utility model provides a converter steel slag waste heat recovery system.

[0008] The utility model realizes the following technical schemes:

[0009] The utility model provides a converter steel slag waste heat recovery system, which comprises a phase change ball tank, a slag tank, a mixing bin, a revolving conveying device, a solid-solid separation device, a conveyor and a waste heat recovery device, wherein:

[0010] The phase change ball tank and the slag tank are respectively filled with phase change balls and converter steel slag, the mixing bin is internally provided with a stirring shaft for mixing the phase change balls and the converter steel slag, the inlet at one end of the rotary conveying device is connected to the mixing bin, the outlet at the other end is communicated with the solid-solid separation device, the bottom outlet of the solid-solid separation device is connected to the waste heat recovery device, and the conveyor is arranged at the bottom of the waste heat recovery device.

[0011] The phase change ball tank and the slag tank are respectively filled with phase change balls and converter steel slag, the mixing bin is internally provided with a stirring shaft for mixing the phase change balls and the converter steel slag, the inlet at one end of the rotary conveying device is connected to the mixing bin, the outlet at the other end is communicated with the solid-solid separation device, the bottom outlet of the solid-solid separation device is connected to the waste heat recovery device, and the conveyor is arranged at the bottom of the waste heat recovery device.

[0012] Further, the phase change ball is a multi-layer composite structure, which is composed of a phase change core metal, an anticorrosion layer, a support layer and a metal plating layer.

[0013] Further, the phase change core metal is one of gallium, indium, tin, bismuth, lead, zinc, copper and aluminum or a multi-element alloy.

[0014] Further, the support layer of the phase change ball is iron, the anticorrosion layer is ceramic, and the metal plating layer is a chromium plating layer.

[0015] Further, when the processed converter steel slag is roller-pressed converter steel slag, the solid-solid separation device separates the steel slag and the phase change balls by centrifugal force, and the solid-solid separation device is provided with a steel slag outlet at one side of the top.

[0016] Further, when the processed converter steel slag is granulated converter steel slag, the solid-solid separation device separates the steel slag and the phase change balls by a screen.

[0017] Further, the rotary conveying device includes a shaftless inner spiral roller, and the inner wall of the roller is provided with spiral fins, and the rotary conveying device is used for conveying and intensively mixing the converter steel slag and the phase change balls.

[0018] Further, the waste heat recovery device includes a medium inlet arranged at the bottom of one side and a medium outlet arranged at the top of the other side.

[0019] Further, the conveyor is a screw elevator or a scale conveyor.

[0020] Further, a converter steel slag waste heat recovery method includes the following steps:

[0021] S1. After the roller pressing or granulation treatment, the solid high-temperature steel slag above 1000 DEG C and the phase change ball are added into a mixing bin in a preset ratio and mixed fully;

[0022] S2. The mixed steel slag and phase change ball are transported through a rotary conveying device and heat exchanged fully until the temperature of the steel slag is reduced to 300-500 DEG and the phase change core metal in the phase change ball absorbs heat and gradually changes from solid to liquid;

[0023] S3. The steel slag and phase change ball are discharged from the rotary conveying device and fall into a solid-solid separation device,

[0024] When the treated converter steel slag is the converter steel slag, the phase change ball is separated from the bottom into the waste heat recovery device by the centrifugal force, and the converter steel slag is discharged from the top side of the steel slag outlet for stewing or sludge drying treatment;

[0025] When the treated converter steel slag is the granulated steel slag, the converter steel slag and the phase change ball are separated by the screening method, the converter steel slag leaks out from the screen hole and is discharged from the bottom to be sent for stewing or sludge drying treatment; the phase change ball rolls over the screen and falls into the waste heat recovery device through the discharge port;

[0026] S4. Compressed air is blown into the bottom of the waste heat boiler to blow off the steel slag powder attached to the surface of the phase change ball, which is discharged from the top as combustion-supporting air, then deionized water is introduced at a certain speed, fully exchanges heat with the phase change ball, and is converted into steam which is discharged from the medium outlet, and the phase change core metal in the phase change ball releases heat and changes from liquid to solid;

[0027] S5. The cooled phase change ball is discharged from the bottom of the waste heat boiler and is re-conveyed to the mixing bin by a conveyor and waits for the next cycle.

[0028] The utility model discloses the beneficial effects of:

[0029] 1. The method of direct contact heat extraction of the medium-temperature zone phase change ball, the heat extraction medium and the converter steel slag are in full contact, and the heat exchange surface is constantly updated, which breaks through the limitations of the existing waste heat recovery technology, realizes the efficient recovery of the high-temperature section waste heat of the converter steel slag, and fills the gap in the prior art.

[0030] 2. The new heat extraction system based on the rotary conveying device and the solid-solid separation method based on the density difference / size difference realize the efficient mixing, conveying and separation of the phase change ball and the converter steel slag; and the relatively sealed structure reduces dust pollution.

[0031] 3. Compared with the existing water process, the phase change material acts as an indirect medium and exchanges heat with the converter steel slag and water respectively, which avoids the safety hazard of explosion and completely eliminates the generation of dust-containing steam.

[0032] 4. The specific technical means is used to control the phase change ball to release heat uniformly, and the difficulty of mismatching between intermittent slagging and continuous stable production is solved. BRIEF DESCRIPTION OF DRAWINGS

[0033] Fig. 1 It is a structure diagram of the converter steel slag waste heat recovery system of the utility model;

[0034] Fig. 2 It is a flow of the converter steel slag waste heat recovery method of the utility model;

[0035] In the figure: phase change ball tank 1, slag tank 2, mixed material bin 3, revolving conveying device 4, solid-solid separation device 5, waste heat recovery device 6, conveyor 7, phase change ball 8, converter steel slag 9;

[0036] The utility model is for the purpose of realizing, functional characteristics and advantages will be further explained in conjunction with the embodiment, referring to the drawings. DETAILED DESCRIPTION

[0037] In order to more clearly and completely explain the technical scheme of the utility model, the utility model will be further explained in conjunction with the drawings.

[0038] Please refer to Figs. 1-2 The utility model discloses a converter steel slag waste heat recovery system including phase change ball tank 1, slag tank 2, mixed material bin 3, revolving conveying device 4, solid-solid separation device 5, conveyor 7 and waste heat recovery device 6, wherein:

[0039] Phase change ball tank 1 and slag tank 2 are respectively equipped with phase change ball 8 and converter steel slag 9, mixed material bin 3 is internally provided with the stirring shaft for mixing phase change ball 8 and converter steel slag 9, the inlet of one end of revolving conveying device 4 is connected mixed material bin 3, the outlet of the other end is communicated solid-solid separation device 5, the bottom outlet of solid-solid separation device 5 is connected with waste heat recovery device 6, and conveyor 7 is arranged at the bottom of waste heat recovery device 6.

[0040] Phase change ball tank 1 and slag tank 2 add phase change ball 8 and slag tank 2 to mixed material bin 3 respectively, phase change ball 8 and converter steel slag 9 are mixed in mixed material bin 3, heat is changed in revolving conveying device 4, the phase change core metal in phase change ball 8 gradually changes from solid to liquid, enters solid-solid separation device 5 to separate converter steel slag 9 and phase change ball 8, finally phase change ball 8 enters waste heat recovery device 6 and exchanges heat with medium, and the phase change core metal in the inside changes from liquid to solid, and is re-conveyed to mixed material bin 3 by conveyor 7.

[0041] In the specific embodiment, the mixing bin 3 mixes the phase change balls 8, the rotary conveying device 4 is a shaftless inner spiral roller, the rotary conveying device 4 rotates slowly, the relative position and contact surface of the converter steel slag 9 and the phase change balls 8 change constantly during the conveying process, so that the phase change core metal absorbs heat, the converter steel slag 9 is rapidly cooled, and the rotary conveying device can also rotate, when the temperature is too high, the rotary conveying device is reversed, so that the phase change balls 8 and the converter steel slag 9 are fully heat exchanged and then conveyed to the solid-solid separation device 5, the solid-solid separation device 5 is used to separate the converter steel slag 9 and the phase change balls, the waste heat recovery device 6 is a waste heat boiler and can also be other devices, the waste heat recovery device 6 recovers the heat of the phase change balls 8, the conveyor 7 conveys the heat-exchanged phase change balls 8 back to the mixing bin 3 for reuse, and the metal in the phase change balls 8 changes from solid to liquid after heat exchange. Similarly, the metal in the phase change balls 8 changes from liquid to solid after heat release. Due to the better stability, higher energy storage density and higher thermal conductivity of the phase change balls, a large amount of heat energy can be stored more efficiently and stably, and the problem of high-grade waste heat of the converter steel slag 9 cannot be efficiently and stably recovered is solved.

[0042] Further, the phase change balls 8 are multi-element composite structures, which are composed of a phase change core metal, an anticorrosion layer, a support layer and a metal plating layer in sequence, the material of the phase change core metal is a single element or a multi-element alloy of gallium, indium, tin, bismuth, lead, zinc, copper or aluminum, the support layer of the phase change balls 8 is made of iron, the anticorrosion layer is made of ceramic material, and the metal plating layer is a chromium plating layer.

[0043] In the specific embodiment, the support layer of the phase change balls 8 can be made of iron or other materials with high thermal conductivity, melting point and no deformation when in contact with high-temperature steel slag, and the material of the phase change core metal needs to be selected as a metal single element or a multi-element alloy material with a melting point of 150-500°C. The phase change core metal inside the phase change balls 8 changes to liquid and solid, has strong thermal stability, can efficiently store a large amount of heat energy, and greatly improves the heat exchange efficiency.

[0044] In one embodiment, at high temperature, intermetallic corrosion is serious, so the middle temperature zone metal-based phase change material is selected, which can greatly delay the corrosion problem, and a ceramic layer is wrapped outside the phase change core, in the related technical field, such as the application of copper-based phase change capsules, the intermetallic high-temperature corrosion problem has been a key factor restricting its performance and service life, and the ceramic layer in the utility model effectively solves this problem, relying on its excellent chemical stability and high-temperature corrosion resistance, it can reliably block the iron shell and the phase change core metal in the medium temperature environment, and the durability and reliability of the material in the steel slag working condition are improved; In order to overcome the inherent defects of ceramic material, such as brittleness and fragility, an iron shell structure is further arranged outside the ceramic layer, which can maintain good mechanical strength under high temperature conditions, and provide a solid support framework for the whole material, effectively resist external impact force and stress caused by temperature change, prevent the material from being damaged, so that the material can always maintain complete structure and stable performance in complex and severe steel slag treatment environment; The outermost layer of the material is treated by chromium plating process, the steel slag treatment process often accompanies strong friction and wear and high-temperature oxidation, the existence of chromium plating layer makes the material surface have excellent wear resistance, which can effectively reduce the material loss caused by long-term friction with steel slag, and the high-temperature oxidation resistance ensures that the material surface can still maintain good integrity and chemical stability under long-term high-temperature working conditions, greatly prolongs the service life of the material, and reduces the maintenance cost and replacement frequency.

[0045] Further, when the treated converter slag is granulated steel slag, the solid-solid separation device 5 separates the converter slag 9 and the phase change ball 8 by using a screen;

[0046] When the treated converter slag is roller-pressed converter slag, the solid-solid separation device 5 is provided with a slag outlet on one side of the top, and the solid-solid separation device 5 separates the converter slag 9 and the phase change ball 8 by using centrifugal force.

[0047] In the specific embodiment, the density of the phase change ball 8 is generally greater than 7g / cm 3 , and the density of the converter slag 9 is about 2-3g / cm 3 , so that the phase change ball 8 and the converter slag 9 can be separated by using gravity and centrifugal force, the phase change ball 8 sinks into the waste heat recovery device 6 under the action of centrifugal force and gravity, and the converter slag 9 with relatively small density is discharged from the converter slag outlet, and the solid-solid separation device 5 can also use a screen to separate, for example, the average particle size of the granulated converter slag 9 is 1.6mm, and the size of the phase change ball 8 is generally set to be more than 10mm, so that the two can be separated by using a simple screen, and the processing and manufacturing and quality control are more convenient.

[0048] Further, the rotary conveying device 4 comprises an axis-free inner spiral roller, and helical blades are arranged on the inner wall of the roller. The rotary conveying device 4 is used for conveying and intensively mixing the converter steel slag 9 and the phase-change balls 8.

[0049] In the specific embodiment, when the converter steel slag 9 and the phase-change balls 8 are in rolling contact in the rotary conveying device 4, the heat exchange interface is constantly renewed, and the phase-change balls 8 are in full contact with the converter steel slag 9, thereby solving the problem that the converter steel slag 9 has low thermal conductivity and internal heat is not easy to export.

[0050] Further, the waste heat recovery device 6 comprises a medium inlet arranged at the bottom of one side and a medium outlet arranged at the top of the other side.

[0051] In the specific embodiment, the phase-change balls 8 enter the waste heat recovery device 6, and then deionized purified water and air are introduced. After absorbing heat energy, the deionized purified water and air are converted into steam and combustion-supporting air to recover heat energy.

[0052] Further, the conveyor 7 adopts a spiral elevator or a scale conveyor 7.

[0053] In the specific embodiment, the conveyor 7 conveys the phase-change balls 8 after complete cooling. The phase-change balls 8 are directly conveyed to the mixing bin 3 by the conveyor 7 or are conveyed to the mixing bin 3 by cooperating with the phase-change ball tank 1 for repeated use. The conveyor 7 can also select other equipment.

[0054] Further,

[0055] S1. The solid high-temperature steel slag at a temperature of 1000°C or above after rolling or granulation treatment and the phase-change balls are added to the mixing bin in a preset ratio for full mixing;

[0056] S2. The mixed steel slag and phase-change balls are conveyed and fully heat-exchanged by the rotary conveying device until the temperature of the steel slag is reduced to 300-500°, and the phase-change core metal in the phase-change balls gradually changes from solid to liquid by absorbing heat;

[0057] S3. The steel slag and phase-change balls are discharged from the rotary conveying device and fall into the solid-solid separation device,

[0058] When the treated steel slag is converter steel slag, the phase-change balls enter the waste heat recovery device from the bottom by using centrifugal force, and the steel slag is discharged from the steel slag outlet at the top of one side for stewing or sludge drying treatment;

[0059] When the treated steel slag is granulated converter steel slag, the steel slag and the phase-change balls are separated by using a screening method. The steel slag leaks out of the screen holes and is discharged from the bottom to be sent for stewing or sludge drying treatment. The phase-change balls roll over the screen and fall into the waste heat recovery device through the discharge port.

[0060] S4. From the bottom of the waste heat boiler, compressed air is blown to blow off the steel slag powder attached to the surface of the phase change ball, which is discharged from the top and used as combustion air, then deionized water is introduced at a certain speed, and the phase change ball is fully heat exchanged to convert into steam from the medium outlet, and the phase change core metal in the phase change ball releases heat and changes from liquid to solid;

[0061] S5. The cooled phase change ball is discharged from the bottom of the waste heat boiler and is re-conveyed to the mixing bin by the conveyor and waits for the next cycle.

[0062] In the specific embodiment, the phase change ball 8 and the converter steel slag 9 are generally added to the mixing bin 3 at a ratio of 1:1, the rotary conveying device 4 conveys the converter steel slag 9 and the phase change ball 8, when the temperature of the side temperature at the outlet is higher than 500 DEG C, the rotary conveying device 4 is reversed to continue heat exchange until it is reduced to below 500 DEG C, then enters the solid-solid separation device 5 to separate the converter steel slag 9 and the phase change ball 8, the cooled converter steel slag 9 is sent to the hot pot by the crane, and the hot pot is used for further treatment by using the converter steel slag 9, or the converter steel slag 9 is used for sludge drying to complete further waste heat recovery of the converter steel slag 9, and the phase change ball 8 enters the waste heat recovery device 6, and a small amount of converter steel slag 9 is easily attached to the phase change ball 8, so that the cleanliness is ensured when the phase change ball 8 is put into the waste heat recovery device 6, compressed air can be used for blowing, and the heated air is used as combustion air, and the phase change ball 8 still has a certain waste heat after taking heat, and deionized pure water is used for heat exchange to cool the phase change ball 8 to below 50 DEG C, and the spiral elevator or the scale plate conveyor 7 is used for sending back to the mixing bin 3 for standby, and waiting for the next standby.

[0063] Of course, the present application also has other various embodiments, and other embodiments obtained by those skilled in the art based on the present embodiment without any creative labor belong to the scope of protection of the present application.

Claims

1. A converter steel slag waste heat recovery system, characterized by, The application relates to a waste heat recovery device for converter steel slag, which comprises a phase-change ball tank, a slag tank, a mixing bin, a rotary conveying device, a solid-solid separation device, a conveyor and a waste heat recovery device. The phase-change ball tank and the slag tank are respectively filled with phase-change balls and converter steel slag, the mixing bin is internally provided with a stirring shaft for mixing the phase-change balls and the converter steel slag, one end of the rotary conveying device is connected with the mixing bin, the other end of the rotary conveying device is connected with the solid-solid separation device, the bottom of the solid-solid separation device is connected with the waste heat recovery device, and the conveyor is arranged at the bottom of the waste heat recovery device.

2. The converter steel slag waste heat recovery system according to claim 1, characterized in that, The phase-change ball comprises a phase-change core metal, an anticorrosion layer, a support layer and a metal plating layer.

3. The converter steel slag waste heat recovery system according to claim 2, characterized in that, The phase-change core metal is made of one of gallium, indium, tin, bismuth, lead, zinc, copper and aluminum.

4. The converter steel slag waste heat recovery system according to claim 2, characterized in that, The support layer of the phase-change ball is made of iron, the anticorrosion layer is made of ceramic, and the metal plating layer is a chromium plating layer.

5. The converter steel slag heat recovery system according to claim 1, characterized in that, When the treated converter steel slag is roller-pressed converter steel slag, a slag outlet is arranged on one side of the top of the solid-solid separation device, and the solid-solid separation device separates the converter steel slag and the phase-change balls through centrifugal force.

6. The converter steel slag heat recovery system according to claim 1, characterized in that, When the treated converter steel slag is granulated converter steel slag, the solid-solid separation device separates the converter steel slag and the phase-change balls through a screen.

7. The converter steel slag heat recovery system according to claim 1, characterized in that, The rotary conveying device comprises a shaftless inner spiral roller, and spiral fins are arranged on the inner wall of the roller.

8. The converter steel slag heat recovery system according to claim 1, characterized in that, The waste heat recovery device comprises a medium inlet arranged at the bottom of one side and a medium outlet arranged at the top of the other side.

9. The converter steel slag heat recovery system according to claim 1, characterized in that, The conveyor is a screw elevator or a scale conveyor.

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