Gradient recycling device for blast furnace slag granulation waste heat

Abstract

The invention belongs to the technical field of blast furnace slag resource utilization, and particularly relates to a blast furnace slag granulation waste heat gradient recycling device. According to the device, waste heat resources contained in the blast furnace slag can be recycled in a stepped mode through the slag runner coated with the eutectic aluminum-silicon alloy energy storage plate, the molten slag cooling and granulating unit, the slag car and the medium-low temperature thermoelectric conversion unit. Waste heat resources contained in the blast furnace slag can be reserved to the maximum extent while the molten blast furnace slag is quenched and granulated, and the recycling efficiency of the blast furnace slag is improved.

Description

Technical Field

[0001] The invention relates to a device for cascade recovery and utilization of waste heat from granulation of blast furnace molten slag, belonging to the technical field of resource utilization of blast furnace slag. Background Art

[0002] The development level of the steel industry is still one of the important indicators to measure the level of industrialization and modernization of a country. With the rapid development of my country's economy, my country's steel production has ranked first in the world, and a large amount of blast furnace slag has been produced, which contains a huge amount of material resources and waste heat resources. The iron-slag ratio of each ironmaking in the blast furnace is about 3:1, and the discharge temperature is about 1380℃; the heat contained in 1t of blast furnace slag is equivalent to the calorific value of about 58kg of standard coal. In 2021, my country's crude steel output was 1.033 billion tons, corresponding to a total amount of blast furnace slag of 355 million tons, and the waste heat resources were equivalent to more than 13 million tons of standard coal. If all of them are recovered, they can generate an output value of more than 10 billion yuan. That is, for every 1 million tons of crude steel produced, the economic value of blast furnace slag waste heat resources is 10 million yuan; at the same time, 34,000 tons of carbon dioxide emissions can be reduced. Therefore, realizing the recovery of high-temperature waste heat from blast furnace slag and large-scale integrated utilization of material resources to meet the strategic needs of the country's "industrial green development" is of great significance to the achievement of "carbon peak and carbon neutrality" in my country's steel industry.

[0003] At present, the liquid blast furnace slag produced in the ironmaking process is generally granulated and cooled by water quenching to produce blast furnace slag suitable for large-scale cement production. In the water quenching process, 8 to 12 tons of slag water with a temperature of about 75°C are produced for every ton of blast furnace slag. Except for some steel enterprises in the north that use a small amount of slag water for heating in winter, a large amount of heat contained in it is lost in vain. The current improvement of the water quenching method mainly starts from improving the utilization rate of circulating water and recovering the low-temperature (80°C) waste heat of the quenching slag water, which cannot fundamentally improve the problem of low thermal utilization rate of the water quenching method. For this reason, based on the principle of water absorbing a large amount of heat to rapidly cool the granulated slag, the traditional water quenching method is abandoned, and a blast furnace slag granulation waste heat cascade recovery and utilization device is proposed to make full use of the waste heat resources contained in the blast furnace slag. Summary of the invention

[0004] 1. Key issues to be addressed

[0005] The purpose of the present invention is to improve the water quenching method in the prior art and propose a blast furnace slag granulation waste heat cascade recovery and utilization device to fully utilize the waste heat resources contained in the blast furnace slag. The device can rapidly cool and granulate the molten blast furnace slag while retaining and utilizing the waste heat resources contained in the blast furnace slag to the maximum extent.

[0006] 2. Technical solution

[0007] The technical scheme of the present invention is as follows: a blast furnace slag granulation waste heat cascade recovery and utilization device comprises a slag ditch coated with a eutectic aluminum-silicon alloy energy storage plate, an intermediate slag tank, a granulation unit, a slag car, a slag water inlet, and a thermal energy utilization unit, wherein the water mist nozzle of the slag cooling and granulation unit is coaxial with the slag water inlet and is in a circular array at a certain inclination angle, and the slag cooling and granulation unit is provided with air supply equipment, water supply equipment water mist nozzle, exhaust duct, auxiliary granulator, water inlet pipe, and air inlet pipe; the exhaust duct first gradually expands from bottom to top, and then gradually contracts from bottom to top; the auxiliary granulator is a hollow cone fixed under the slag water inlet, which is used for preliminary crushing and diverting blast furnace slag; eutectic aluminum-silicon alloy energy storage plates and heat exchange plates are arranged around the slag car; a thermoelectric conversion plate and a molten salt phase change energy storage wall are arranged in the thermal energy utilization unit, and a cooling water pipe is arranged inside the molten salt phase change energy storage wall, which can be connected in series with the slag car.

[0008] The high-temperature slag from the blast furnace enters the intermediate slag pot through the slag groove covered by the eutectic aluminum-silicon alloy energy storage plate, and the waste heat of the high-temperature slag above 1380°C is recovered in this process. Then the slag enters the slag cooling and granulation unit from the slag water inlet of the intermediate slag pot. In the slag cooling and granulation unit, the high-temperature slag is fully contacted with the water mist under the joint action of the auxiliary granulator and the water mist nozzle and is cooled into fine particles with a temperature of about 750°C. The 300°C water vapor formed by the slag in the water mist granulation process is discharged from the exhaust duct at the top and can enter the waste heat boiler for heat exchange later. The cooled fine particles fall into the slag car below and are transported out. Eutectic aluminum-silicon alloy energy storage plates are set around the slag car, which continuously exchanges heat with the slag particles through heat exchange plates to recover the waste heat of blast furnace slag at 750°C to 600°C. At the same time, the blast furnace slag particles are transported to the heat energy utilization unit by the slag car via tracks. A cooling water pipe is provided inside the eutectic aluminum-silicon alloy energy storage plate. Multiple slag trucks can be connected through a docking device, and their cooling water pipes can be connected in series through quick connectors.

[0009] The heat energy utilization unit is a heat exchange workshop surrounded by molten salt phase change energy storage walls and equipped with thermoelectric conversion plates on the top. The molten salt phase change energy storage wall is equipped with cooling water pipes inside, which can be connected in series with the slag car. In the heat energy utilization unit, the thermoelectric conversion plate recovers the waste heat of blast furnace slag below 600°C for power generation; the molten salt phase change energy storage wall recovers the waste heat of blast furnace slag with a temperature of 560°C to 220°C, captures and integrates the heat lost to the space; after all the slag cars have entered, the water pipelines are connected, and the cooling water first enters the molten salt phase change energy storage wall from the water inlet, absorbs the captured heat, and forms low-temperature steam as preheating. Then the low-temperature steam is exchanged through the eutectic aluminum-silicon alloy energy storage plate inside the series-connected slag car. After multiple heatings, high-temperature steam is finally formed and passed into the waste heat boiler for use.

[0010] The present invention aims to solve the problem that the water quenching method in the prior art cannot recover the waste heat of slag. On the basis of the water quenching method, the present invention makes improvements and proposes a blast furnace slag granulation waste heat cascade recovery and utilization device to fully utilize the waste heat resources contained in the blast furnace slag. The waste heat resources in the blast furnace slag are recycled and utilized in four temperature intervals by energy storage materials respectively arranged in different links: the eutectic aluminum-silicon alloy energy storage plate on the slag groove recovers the waste heat lost in the high temperature section; the steam formed in the water mist granulation process recovers the waste heat in the high temperature section; the aluminum-silicon alloy energy storage plate in the slag car recovers the waste heat in the medium temperature section; and finally, the thermoelectric conversion and molten salt energy storage wall recover the waste heat in the low temperature section. Thereby, the purpose of rapidly cooling and granulating the molten blast furnace slag while retaining the waste heat resources contained in the blast furnace slag to the maximum extent and increasing the efficiency of blast furnace slag resource recycling is achieved. Therefore, the technical scheme of the present invention can be further improved:

[0011] Preferably, eutectic aluminum-silicon alloy energy storage plates and heat exchange fins are provided around the slag car.

[0012] As a preferred arrangement, the heat energy utilization unit is arranged as follows: Figure 3 As shown, you can also design it according to the actual situation.

[0013] Preferably, the inclination angle and spray range of the water mist nozzle in the granulation unit can be adjusted automatically.

[0014] Preferably, in order to achieve a better granulation effect, the auxiliary granulator is a hollow cone fixed below the slag nozzle, which is used for preliminary crushing and diversion of blast furnace slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of the device;

[0016] Figure 2 The internal structure of the granulation unit for slag cooling;

[0017] Figure 3 It is the internal structure of the heat energy utilization unit;

[0018] Figure 4 A structure of a slag car;

[0019] Figure 5 The connection method for the slag truck;

[0020] Figure 6 A structure for the auxiliary granulator;

[0021] Figure 7 This is the internal structure of the water mist nozzle.

[0022] The markings of the components in the accompanying drawings are as follows:

[0023] 1: Slag cooling and granulation unit;

[0024] 2: Air supply equipment;

[0025] 3: Water supply equipment;

[0026] 4: Water mist nozzle;

[0027] 5: Exhaust duct;

[0028] 6: Intermediate slag tank;

[0029] 7: Slag nozzle;

[0030] 8: Auxiliary granulator;

[0031] 9: Water inlet pipe;

[0032] 10: Air inlet duct;

[0033] 11: Slag truck;

[0034] 12: Heat energy utilization unit;

[0035] 13: Thermoelectric conversion plate;

[0036] 14: Molten salt phase change energy storage wall;

[0037] 15: Slag ditch covered with eutectic aluminum-silicon alloy energy storage plate. DETAILED DESCRIPTION

[0038] The present invention is described in detail below in conjunction with the accompanying drawings through specific implementation cases so that the advantages and features of the present invention can be more easily understood by those skilled in the art. It should be noted that the description of these implementation methods is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0039] Examples

[0040] The high-temperature slag from the blast furnace enters the intermediate slag pot (6) through the slag groove (15) covered by the eutectic aluminum-silicon alloy energy storage plate. In this process, the waste heat of the high-temperature slag above 1380°C is recovered. Then the slag enters the slag cooling and granulation unit (1) from the slag water inlet (7) of the intermediate slag pot. In the slag cooling and granulation unit (1), the high-temperature slag hits the auxiliary granulator (10) and is divided into multiple streams. The streams are fully contacted with the water mist and air jets sprayed by the water mist nozzle (4). Under the combined action of the water mist and air jets, the slag is rapidly cooled and granulated into fine particles with a temperature of about 750°C. The 300°C water vapor formed by the slag during the water mist granulation process is discharged from the exhaust duct (5) at the top and can subsequently enter the waste heat boiler for heat exchange. The cooled fine particles fall into the slag car (11) below for transportation. Eutectic aluminum-silicon alloy energy storage plates are arranged around the slag car to continuously contact and exchange heat with the slag particles, and recover the waste heat of blast furnace slag at 750°C to 600°C. At the same time, the blast furnace slag particles are transported by the slag car (11) to the heat energy utilization unit (12). The heat energy utilization unit (12) is a heat exchange workshop surrounded by molten salt phase change energy storage walls (14) and provided with a thermoelectric conversion plate (13) on the top. The thermoelectric conversion plate (13) recovers the waste heat of blast furnace slag below 600°C for power generation; the molten salt phase change energy storage wall (14) recovers the waste heat of blast furnace slag at a temperature of 560°C to 220°C, and captures and integrates the heat dissipated into the space. At the same time, the blast furnace slag particles are transported by the slag car (11) to the heat energy utilization unit (12) via rails. A cooling water pipe is arranged inside the eutectic aluminum-silicon alloy energy storage plate, and multiple slag cars (11) can be connected by a docking device, and their cooling water pipes can be connected in series through a quick connector.

[0041] The heat energy utilization unit (12) is a heat exchange workshop surrounded by a molten salt phase change energy storage wall (14) and provided with a thermoelectric conversion plate (13) on the top. A cooling water pipe is provided inside the molten salt phase change energy storage wall (14) and can be connected in series with a slag car. In the heat energy utilization unit (12), the thermoelectric conversion plate (13) recovers the waste heat of blast furnace slag below 600°C to generate electricity; the molten salt phase change energy storage wall (14) recovers the waste heat of blast furnace slag with a temperature of 560°C to 220°C, and captures and integrates the heat lost to the space; after all the slag cars (11) have entered, the water pipeline is connected, and the cooling water first enters the molten salt phase change energy storage wall (14) from the water inlet, absorbs the captured heat, and forms low-temperature steam for preheating, and then the low-temperature steam is exchanged in the eutectic aluminum-silicon alloy energy storage plate inside the series-connected slag car (11), and finally forms high-temperature steam after multiple heating, which is passed into the waste heat boiler for use.

[0042] In addition, the inner wall of the shell of the slag cooling and granulation unit and the surface of the auxiliary granulator have a wear-resistant coating. The inner wall of the shell and the auxiliary granulator will be worn during the discharge of blast furnace slag particles, and both need to be made of wear-resistant materials; the eutectic aluminum-silicon alloy energy storage plates and the internal cooling water pipes inside the slag car are coated with 5 corrosion-resistant ceramic coatings, because the molten aluminum-silicon alloy is corrosive to the container.

[0043] The above is only an embodiment of the present invention with better effects, and is not intended to limit the scope of the present invention. Any simple deformation or equivalent transformation made by any technician based on the content of the present invention, or directly or indirectly applied in other related technical fields, is included in the scope of the present invention.

Claims

1. A blast furnace slag granulation waste heat cascade recovery and utilization device, characterized in that: It comprises a slag cooling and granulating unit (1), a heat energy utilization unit (12), an intermediate slag pot (6), a slag ditch (15) coated with a eutectic aluminum-silicon alloy energy storage plate, and a slag car (11). The slag cooling and granulating unit (1) is provided with an air supply device (2), a water supply device (3), a water mist nozzle (4), a slag water inlet (7), an exhaust duct (5), an auxiliary granulator (8), a water inlet pipe (9), and an air inlet pipe (10). A thermoelectric conversion plate is provided on the top of the heat energy utilization unit (12), and a molten salt phase change energy storage wall (14) is coated around it (13). A cooling water pipe is provided inside the molten salt phase change energy storage wall (14), which can be connected in series with the slag car through a quick connector.

2. The device for recycling waste heat from blast furnace slag granulation according to claim 1, characterized in that: The water mist nozzle (4) of the slag cooling and granulating unit (1) is coaxial with the slag water inlet (7) and forms a circular array at a certain tilt angle.

3. The device for recycling waste heat from blast furnace slag granulation according to claim 1, characterized in that: The slag car (11) is provided with eutectic aluminum-silicon alloy energy storage plates and heat exchange plates around it, and cooling water pipes are provided inside the eutectic aluminum-silicon alloy energy storage plates. Multiple slag cars can be connected by a docking device, and their cooling water pipes can be connected in series by quick connectors.

4. The device for recycling waste heat from blast furnace slag granulation according to claim 1, characterized in that: In order to suppress the turbulence occurring during the slag flow process and maintain the stability of the slag discharge from the slag outlet (7), a streamlined design is adopted at the connection between the bottom of the intermediate slag pot (6) and the slag outlet (7).

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