Steel slag granulation waste heat recovery system

Abstract

The steel slag granulation waste heat recovery system belongs to the technical field of steel smelting equipment. The existing steel slag waste heat recovery wastes a large amount of fresh water resources, produces toxic gas and pollutes the environment, and cannot efficiently recover waste heat. The steel slag granulation waste heat recovery system comprises a slag pool, a slag throwing mechanism and a waste heat recovery mechanism; the slag pool stores molten slag; the slag throwing mechanism is communicated with the slag pool and can throw the molten slag discharged from the slag pool to the surrounding, so that the thrown molten slag exchanges heat with the first heat exchange gas, and high-temperature waste gas and solid steel slag are obtained; the waste heat recovery mechanism is communicated with the slag throwing mechanism and is used for exchanging heat with the high-temperature waste gas and the solid steel slag, so as to recover the waste heat of the high-temperature waste gas and the solid steel slag. The present application is used for steel slag waste heat recovery.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of steel smelting equipment, and particularly relates to a steel slag granulation waste heat recovery system. BACKGROUND

[0002] In the process of blast furnace steelmaking production, slag (main components are CaO, SiO2, etc.) needs to be discharged from the blast furnace hearth to avoid the accumulation in the furnace affecting the smelting efficiency. The traditional slag treatment method is mostly water quenching or dry slag pit cooling. Among them, the water quenching method is widely used in industrial production due to its high efficiency, but this method also has many drawbacks: first, a large amount of high-quality waste heat resources is wasted, and most of the water is directly vaporized into the atmosphere at high temperature, and this part of heat cannot be recovered and utilized. Second, a large amount of fresh water resources is wasted, and the slag-water ratio is about 1:1, and the amount of new water consumed for treating each ton of high-temperature slag is large. Third, serious environmental pollution is caused, because water and slag are in direct contact, a large amount of toxic gases H2S and SO2 are generated. The dry slag pit cooling method pours the molten blast furnace slag into the dry slag pit for air cooling, which pollutes the underground water source, releases a large amount of water vapor during cooling, and releases a large amount of H2S and SO2 gas, which corrodes buildings, damages equipment and worsens the working environment. SUMMARY

[0003] Therefore, the present application provides a steel slag granulation waste heat recovery system which can recover the waste heat of steel slag in multiple stages to avoid waste of energy.

[0004] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0005] The steel slag granulation waste heat recovery system comprises:

[0006] A slag pool for storing molten slag;

[0007] A slag throwing mechanism connected to the slag pool and capable of throwing the molten slag discharged from the slag pool to the surrounding area to exchange heat between the thrown molten slag and the first heat exchange gas introduced to obtain high-temperature waste gas and solid steel slag;

[0008] A waste heat recovery mechanism connected to the slag throwing mechanism and used for exchanging heat with the high-temperature waste gas and the solid steel slag to recover the waste heat of the high-temperature waste gas and the solid steel slag.

[0009] Further, the slag throwing mechanism comprises at least one layer of slag throwing disc capable of throwing the molten slag; a plurality of circumferentially arranged slag throwing grooves are arranged on the slag throwing disc, and the slag throwing grooves are configured to apply force to the molten slag during the movement of the molten slag along the length direction of the slag throwing grooves under the centrifugal force to cut the molten slag into granular shape.

[0010] Further, a high-speed airflow ring is arranged outside each layer of slag throwing disc, the high-speed airflow ring is provided with an annular gas outlet in the circumferential direction, and the high-speed airflow ring discharges gas to circumcut the thrown molten slag.

[0011] Further, the waste heat recovery mechanism comprises a pulsating fluidized bed, a low-temperature economizer, a dust removal heat exchanger, a superheater and an evaporator, the pulsating fluidized bed is communicated with the slag throwing mechanism, the second heat exchange gas is introduced into the pulsating fluidized bed to exchange heat with the solid steel slag flowing into the pulsating fluidized bed, and the high-temperature gas is obtained; the high-temperature gas is introduced into the low-temperature economizer to exchange heat with the softened water introduced into the low-temperature economizer; the high-temperature exhaust gas flowing out of the slag throwing mechanism flows through the dust removal heat exchanger, the superheater and the evaporator in sequence, and the softened water flowing out of the low-temperature economizer flows through the dust removal heat exchanger, the evaporator and the superheater in sequence to exchange heat with the high-temperature exhaust gas step by step, and the superheated steam is obtained.

[0012] Further, the waste heat recovery mechanism comprises a pulsating fluidized bed, a low-temperature economizer, a dust removal heat exchanger, a superheater and an evaporator, the pulsating fluidized bed is communicated with the slag throwing mechanism, the second heat exchange gas is introduced into the pulsating fluidized bed to exchange heat with the solid steel slag flowing into the pulsating fluidized bed, and the high-temperature gas is obtained; the high-temperature gas is introduced into the low-temperature economizer to exchange heat with the softened water introduced into the low-temperature economizer; the high-temperature exhaust gas flowing out of the slag throwing mechanism flows through the dust removal heat exchanger, the superheater and the evaporator in sequence, and the softened water flowing out of the low-temperature economizer flows through the dust removal heat exchanger, the evaporator and the superheater in sequence to exchange heat with the high-temperature exhaust gas step by step, and the superheated steam is obtained.

[0013] Further, the low-temperature economizer is communicated with the power generation mechanism, and the superheated steam is introduced into the power generation mechanism to generate power.

[0014] Further, the dust removal heat exchanger comprises a dust removal shell, a separation cone, a flow guide pipe, a dust collection box and a high-temperature economizer, the separation cone and the flow guide pipe are sequentially arranged in the dust removal shell from top to bottom, the dust collection box is arranged at the bottom of the dust removal shell, and the high-temperature economizer is sleeved outside the dust collection box; the high-temperature exhaust gas flows into the dust removal shell tangentially to separate the high-temperature gas and the steel slag particles, the separation cone separates the high-temperature gas and the steel slag particles to make the steel slag particles fall into the dust collection box; the flow guide pipe and the inner wall of the dust removal shell form an annular air channel communicated with the inside of the flow guide pipe, the separated high-temperature gas flows into the superheater through the flow guide pipe and the annular air channel in sequence; and the softened water discharged from the low-temperature economizer is introduced into the high-temperature economizer to exchange heat with the steel slag particles.

[0015] Further, at least two levels of anti-condensation baffles are arranged in the slag pool in an up-down staggered manner along the feeding direction.

[0016] Further, the discharge port of the slag pool is provided with a flow control valve for controlling the slag discharge amount of the slag pool.

[0017] Further, the flow control valve comprises a linear driving part, a connecting rod and a valve core, the cross section of the valve core is trapezoidal, the valve core is inserted into the discharge port of the slag pool, one end of the connecting rod is connected with the valve core, and the other end is drivingly connected with the linear driving part.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] 1、The present application first utilizes cooling air as heat exchange medium to exchange heat with molten slag, and the air after heat exchange exchanges heat with softened water, avoiding the generation of toxic gas caused by direct heat exchange between cooling water and molten slag. The softened water is used in a closed loop, on the one hand avoiding the waste of fresh water resources, and on the other hand improving the water inlet temperature of the waste heat recovery mechanism, further avoiding the waste of energy.

[0020] 2、The present application designs two-stage anti-condensation baffles in the slag pool, which can sequentially disturb the flow of the feed, preventing the molten slag from prematurely solidifying or splashing during pouring, and ensuring effective separation of molten steel and slag.

[0021] 3、The present application can realize three-stage cutting of molten slag, the first stage is the design of overflow pipe and slag discharge port at the discharge port of the first discharge pipe, which divides large molten slag into small molten slag; the second stage is the slag throwing groove of the slag throwing disc, which divides small molten slag into granular molten slag; the third stage is the air flow ring cutting, which divides the granular molten slag into smaller and more uniform steel slag particles. Thus, the molten slag can be fully exchanged with the cooling air, improving the heat exchange efficiency. At the same time, compared with the traditional process, the slag throwing mechanism of the present application can omit the crushing and drying steps of molten slag, and directly generate fine particles (the diameter of the particles can reach 0.1-5mm), saving intermediate processes, reducing power consumption and equipment maintenance cost. Moreover, the generated steel slag particles have high activity and can be directly used as cement admixture or roadbed material, reducing the downstream grinding energy consumption (traditional process needs additional grinding to a specific surface area of ≥400m² / kg). The centrifugal granulation dry process does not require a large amount of cooling water, reducing water pump energy consumption and water treatment cost.

[0022] 4、The waste heat recovery mechanism of the present application is provided with a multi-stage heat exchange structure, the high-temperature exhaust gas discharged by the slag throwing mechanism is multi-stage exchanged with cooling water to achieve the purpose of full heat exchange and improve the energy utilization rate.

[0023] 5、The superheated steam discharged by the waste heat recovery mechanism is sent to the power generation mechanism to generate electricity, and the steam after power generation is condensed into condensed water and sent to the waste heat recovery mechanism, realizing a closed loop and avoiding the waste of water resources and energy. BRIEF DESCRIPTION OF DRAWINGS

[0024] The accompanying drawings are part of the present application and serve to provide a further understanding of the present application.

[0025] Figure 1 is a structural schematic diagram of the steel slag granulation waste heat recovery system of the present application.

[0026] Figure 2 is a structural schematic diagram of the slag pool and the slag throwing mechanism.

[0027] Figure 3 is a structural schematic diagram of the slag pool.

[0028] Figure 4 Structure diagram of slag pool matched with flow control valve.

[0029] Figure 5 Structure diagram of slag throwing mechanism.

[0030] Figure 6 Sectional view diagram of slag throwing mechanism.

[0031] Figure 7 Exploded view diagram of slag throwing mechanism.

[0032] Figure 8 Structure diagram of pulsating fluidized bed.

[0033] Figure 9 Structure diagram of dust removal heat exchanger Figure 1 .

[0034] Figure 10 Structure diagram of dust removal heat exchanger Figure 2 .

[0035] Figure 11 Sectional view diagram of dust removal heat exchanger.

[0036] Explanation of reference signs:

[0037] 1 - slag pool; 11 - first discharge pipe; 111 - overflow pipe; 112 - discharge gap; 12 - anti-condensation baffle; 13 - flow control valve; 131 - connecting rod; 132 - valve core; 2 - slag throwing mechanism; 21 - slag throwing shell; 212 - second discharge pipe; 22 - sleeve; 23 - slag throwing motor; 231 - motor shaft; 24 - support base; 25 - slag throwing disc; 251 - slag throwing groove; 26 - high-speed airflow ring; 27 - long screw rod; 3 - waste heat recovery mechanism; 31 - pulsating fluidized bed; 311 - air inlet pipe; 32 - low-temperature economizer; 33 - dust removal heat exchanger; 331 - dust removal shell; 3311 - air inlet pipe; 3312 - air outlet pipe; 332 - separation cone; 333 - flow guide pipe; 3331 - air outlet hole; 334 - dust collection box; 335 - high-temperature economizer; 336 - planetary feeder; 337 - annular air duct; 34 - superheater; 35 - evaporator; 4 - power generation mechanism. DETAILED DESCRIPTION

[0038] The present application will be described in detail below in conjunction with the drawings and specific examples.

[0039] Figure 1 A structure diagram of a steel slag granulation waste heat recovery system of the embodiment is shown, as Figure 1As shown, the steel slag granulation waste heat recovery system comprises a slag pool 1, a slag throwing mechanism 2, a waste heat recovery mechanism 3 and a power generation mechanism 4. The slag pool 1 is used to store the steel slag discharged from the blast furnace. At this time, the temperature of the steel slag is about 1400 degrees, so it is in a liquid state and has a certain viscosity. The slag pool 1 is above the slag throwing mechanism 2 and communicates with the slag throwing mechanism 2. The molten slag is discharged onto the slag throwing mechanism 2 by gravity. The slag throwing mechanism 2 can throw the molten slag to the surrounding area to disperse the large pieces of molten slag, and at the same time, cooling air is introduced into the slag throwing mechanism 2 as the first heat exchange gas to exchange heat with the molten slag. The first heat exchange gas after heat exchange forms high-temperature waste gas, and the molten slag after heat exchange becomes granular solid steel slag due to the decrease in temperature. At this time, the temperature of the solid steel slag is about 850 degrees. The slag throwing mechanism 2 communicates with the waste heat recovery mechanism 3, and the high-temperature waste gas and the solid steel slag are introduced into the waste heat recovery mechanism 3. The high-temperature waste gas and the solid steel slag exchange heat with the softened water in the waste heat recovery mechanism 3, and the softened water is used to recover the waste heat of the high-temperature waste gas and the solid steel slag. The waste heat recovery mechanism 3 converts the softened water after heat exchange into superheated steam and introduces it into the power generation mechanism 4 to do work and generate electricity. The softened water formed after the superheated steam does work continues to be introduced into the waste heat recovery mechanism 3 to exchange heat with the high-temperature waste gas and the solid steel slag, realizing a closed loop. In this way, the waste heat of the molten slag is recovered, avoiding waste of energy. At the same time, the embodiment first uses cooling air as a heat exchange medium to exchange heat with the molten slag, and the air after heat exchange exchanges heat with the softened water, avoiding the generation of toxic gas caused by direct heat exchange between cooling water and molten slag. And the closed loop use of softened water, on the one hand, avoids the waste of fresh water resources, and on the other hand, improves the inlet water temperature of the waste heat recovery mechanism 3, further avoiding the waste of energy.

[0040] Figure 3 and Figure 4 The structure diagram of the slag pool 1 of the embodiment is shown. In combination with the description of the waste heat recovery system of the molten slag, the slag pool 1 is used to store the molten slag discharged from the blast furnace. The slag pool 1 is above the slag throwing mechanism 2 and communicates with the slag throwing mechanism 2. The molten slag is discharged onto the slag throwing mechanism 2 by gravity. The slag throwing mechanism 2 can throw the molten slag to the surrounding area to disperse the large pieces of molten slag, and at the same time, cooling air is introduced into the slag throwing mechanism 2 as the first heat exchange gas to exchange heat with the molten slag. The first heat exchange gas after heat exchange forms high-temperature waste gas, and the molten slag after heat exchange becomes granular solid steel slag due to the decrease in temperature. At this time, the temperature of the solid steel slag is about 850 degrees. The slag throwing mechanism 2 communicates with the waste heat recovery mechanism 3, and the high-temperature waste gas and the solid steel slag are introduced into the waste heat recovery mechanism 3. The high-temperature waste gas and the solid steel slag exchange heat with the softened water in the waste heat recovery mechanism 3, and the softened water is used to recover the waste heat of the high-temperature waste gas and the solid steel slag. The waste heat recovery mechanism 3 converts the softened water after heat exchange into superheated steam and introduces it into the power generation mechanism 4 to do work and generate electricity. The softened water formed after the superheated steam does work continues to be introduced into the waste heat recovery mechanism 3 to exchange heat with the high-temperature waste gas and the solid steel slag, realizing a closed loop. In this way, the waste heat of the molten slag is recovered, avoiding waste of energy. At the same time, the embodiment first uses cooling air as a heat exchange medium to exchange heat with the molten slag, and the air after heat exchange exchanges heat with the softened water, avoiding the generation of toxic gas caused by direct heat exchange between cooling water and molten slag. And the closed loop use of softened water, on the one hand, avoids the waste of fresh water resources, and on the other hand, improves the inlet water temperature of the waste heat recovery mechanism 3, further avoiding the waste of energy. Figure 2 , Figure 3 and Figure 4The slag pool 1 of the embodiment is inverted trapezoidal, the bottom of the slag pool 1 is provided with a discharge port, and the bottom of the slag pool 1 is provided with a first discharge pipe 11, the upper pipe opening of the first discharge pipe 11 is communicated with the discharge port at the bottom of the slag pool 1, and the lower pipe opening is communicated with the slag throwing mechanism 2. The two-stage anti-condensation baffle 12 is arranged in the slag pool 1 between the inlet and the discharge port, the anti-condensation baffle 12 close to the inlet is higher than the anti-condensation baffle 12 close to the discharge port, so that the two-stage anti-condensation baffle 12 can disturb the flow of the feed in sequence, prevent the molten slag from solidifying too early or splashing during pouring, and ensure the effective separation of molten steel and slag. The anti-condensation baffle 12 can also be designed with a specific angle or be designed with a hole to form a directional vortex of the molten slag and avoid the local static area from solidifying due to rapid heat dissipation (such as inclined baffle induced natural convection). That is, the anti-condensation baffle 12 of the embodiment is based on the optimization of the thermodynamic and fluid dynamic environment inside the slag pool 1 to delay or prevent the solidification of the molten slag. The anti-condensation baffle 12 can also be designed to be inclined or arc-shaped, and the molten slag is naturally returned to the bottom of the ladle by gravity, while the molten steel flows out from the other side, realizing the separation of molten slag and molten steel. In addition, the anti-condensation baffle 12 is usually made of refractory material, such as high alumina and magnesia carbon, which can withstand high temperature and reduce the direct contact of the molten slag with cold air or the inner wall of the slag pool 1, thereby reducing the cooling speed of the molten slag and preventing premature solidification.

[0041] As shown in Figure 4 , the discharge port of the slag pool 1 of the embodiment is also provided with a flow control valve 13 for controlling the slag discharge amount of the slag pool 1. The flow control valve 13 includes a linear drive part (not shown in the figure), a connecting rod 131 and a valve core 132, the cross section of the valve core 132 is inverted trapezoidal, and the valve core 132 is inserted into the discharge port of the slag pool 1 and the upper pipe opening of the first discharge pipe 11. In combination with Figure 4 , the upper pipe opening of the first discharge pipe 11 is inverted conical, so that the annular discharge channel is formed between the valve core 132 and the upper pipe opening of the first discharge pipe 11. One end of the connecting rod 131 is connected with the valve core 132, and the other end is drivingly connected with the linear drive part. When the linear drive part drives the valve core 132 to move upward through the connecting rod 131, the inner diameter of the annular discharge channel becomes larger, and the molten slag discharge amount in the slag pool 1 increases; when the linear drive part drives the valve core 132 to move downward through the connecting rod 131, the inner diameter of the annular discharge channel becomes smaller, and the molten slag discharge amount in the slag pool 1 decreases, thereby realizing the adjustment of the slag discharge amount. The connecting rod 131 can also be provided with a scale dial on the side, the connecting rod 131 is connected with a scale pointer, and the connecting rod 131 moves upward and downward to drive the scale pointer to move synchronously, and the slag discharge amount is determined by the scale line indicated by the scale pointer.

[0042] Figure 5 、 Figure 6 and Figure 7 shows the structure schematic diagram of the slag throwing mechanism 2, in combination with Figure 5 、 Figure 6 and Figure 7The slag throwing mechanism 2 of the embodiment comprises a slag throwing shell 21, a sleeve 22, a slag throwing motor 23, a supporting base 24 and a slag throwing disc 25. The bottom of the slag throwing shell 21 is provided with an air inlet through which cooling air enters the slag throwing shell 21 to exchange heat with the molten slag. The sleeve 22 penetrates the bottom of the slag throwing shell 21 and is inserted into the slag throwing shell 21, and the supporting base 24 is installed at the upper pipe opening of the sleeve 22. The slag throwing disc 25 is provided with three layers from top to bottom and is above the supporting base 24. The slag throwing motor 23 is arranged outside the slag throwing shell 21, the motor shaft 231 of the slag throwing motor 23 is inserted into the sleeve 22 and extends upward, the shaft end of the motor shaft 231 penetrates the supporting base 24 and is fixedly connected with the third layer of the slag throwing disc 25 through a coupling, and the upper and lower layers of the slag throwing disc 25 are connected to the third layer of the slag throwing disc 25 through a long screw rod 27, so as to realize the fixation of the three layers of the slag throwing disc 25, and the three layers of the slag throwing disc 25 can be synchronously driven to rotate by the slag throwing motor 23, so that the slag throwing disc 25 can throw the molten slag flowing onto the disc surface. The center positions of the upper and lower layers of the slag throwing disc 25 are provided with insertion openings, the lower pipe opening of the first discharge pipe 11 penetrates the insertion openings of the upper and lower layers of the slag throwing disc 25 and extends to the upper disc surface of the third layer of the slag throwing disc 25. The first discharge pipe 11 is provided with a plurality of overflow pipes 111 corresponding to the positions of the upper and lower layers of the slag throwing disc 25, the plurality of overflow pipes 111 are uniformly arranged in the circumferential direction, and the lower pipe opening of the first discharge pipe 11 is provided with a plurality of discharge openings 112 in the circumferential direction, the plurality of discharge openings 112 form the discharge openings 112 with the disc surface of the third layer of the slag throwing disc 25. The molten slag in the slag pool 1 flows through the first discharge pipe 11 and is discharged to the corresponding slag throwing disc 25 from each overflow pipe 111 and discharge port, and the molten slag is changed from large slag bodies to small slag bodies, so as to realize the first cutting of the molten slag.

[0043] In combination Figure 7 The slag throwing disc 25 of the embodiment is provided with a plurality of circumferentially arranged slag throwing grooves 251, each of which is arranged along the radial direction of the slag throwing disc 25, and the depth of the slag throwing groove 251 gradually increases from the shaft center to the edge. When the molten slag falls onto the slag throwing disc 25 from the first discharge pipe 11, the molten slag flows into the slag throwing groove 251 due to the molten state of the molten slag. With the rotation of the slag throwing disc 25, the molten slag gradually moves from the shaft center to the edge of the slag throwing disc 25 along the length direction of the slag throwing groove 251 under the centrifugal force, and the molten slag forms a spiral motion track in the slag throwing disc 25, thereby prolonging the time for the molten slag to stay on the slag throwing disc 25 and uniformly accelerating the molten slag in the slag throwing groove 251. At the same time, since the centrifugal force of the slag throwing disc 25 increases with the increase of the radius, the groove edge of the slag throwing groove 251 can apply force to the molten slag, and the applied force gradually increases with the movement of the molten slag in the slag throwing groove 251, so as to gradually cut the molten slag from small slag bodies into uniform granular shapes, realize the second cutting of the molten slag, avoid the accumulation of the molten slag, and improve the heat exchange efficiency between the molten slag and the heat exchange gas.

[0044] In combinationFigure 5 and Figure 6 In this embodiment, each slag-throwing disc 25 is surrounded by a high-speed airflow ring 26, resulting in a total of three high-speed airflow rings 26. Counting from top to bottom, the first and second high-speed airflow rings 26 are fixedly connected, with the second high-speed airflow ring 26 mounted on the support base 24 via a support rod. The outer diameter of the third high-speed airflow ring 26 is smaller than that of the first and second high-speed airflow rings 26, and it is also fixedly mounted on the support base 24. Each high-speed airflow ring 26 has an annular air outlet along its circumference, which is connected to the three high-speed airflow rings 26 via air pipes (not shown in the figure) to supply air to the high-speed airflow rings 26. After the molten slag is thrown out by the slag-throwing disc 25, the slag particles diffuse outward. The high-speed airflow rings 26 spray high-speed cold air, which can perform ring cutting on the thrown molten slag, making the slag particle size smaller and the slag particle size more uniform, thus achieving three-stage cutting of the molten slag. In this way, the cooling air can accelerate heat exchange after contacting the smaller molten slag particles, resulting in high-temperature exhaust gas. Furthermore, after exchanging heat with the cooling air, the molten slag changes from a molten state to solid particles. The high-speed cooling air impacts the granular slag, reducing its outward velocity and causing it to fall to the bottom of the slag-throwing shell 21 under its own gravity. This prevents the granular slag from impacting the inner wall of the shell 21 and affecting its service life. At this time, the temperature of the solid particles drops from 1400°C to approximately 850°C, and they are gradually dried during the slag-throwing process.

[0045] Therefore, the slag-throwing mechanism 2 in this embodiment, compared to the traditional process, can omit the crushing and drying steps of molten slag and directly granulate it into fine particles (particle diameter can reach 0.1~5mm), eliminating intermediate processes and reducing power consumption and equipment maintenance costs. Furthermore, the steel slag particles generated in this embodiment have high activity and can be directly used as cement admixtures or roadbed materials, reducing downstream grinding energy consumption (traditional processes require additional grinding to a specific surface area ≥400m² / kg). Dry processes such as centrifugal granulation do not require large amounts of cooling water, reducing pump energy consumption and water treatment costs, resulting in an overall energy consumption reduction of 30%~50%.

[0046] Figure 1 A schematic diagram of the waste heat recovery mechanism 3 is shown, combined with... Figure 1 In this embodiment, the waste heat recovery mechanism 3 includes a pulsating fluidized bed 31, a low-temperature economizer 32, a dust removal heat exchanger 33, a superheater 34, and an evaporator 35. A second discharge pipe 212 is provided at the bottom of the slag-throwing shell 21, which connects to the pulsating fluidized bed 31 to guide the solid steel slag falling from the slag-throwing shell 21 to the gas equalization plate within the pulsating fluidized bed 31. Combined with... Figure 8The bottom of the pulsating fluidized bed 31 is provided with an air inlet pipe 311, through which the second heat exchange gas, which is cooling air, is introduced into the pulsating fluidized bed 31 to fluidize the solid steel slag flowing through the gas distribution plate. The solid steel slag gradually jumps from one end of the pulsating fluidized bed 31 to the other end and fully contacts and exchanges heat with the introduced cooling air to obtain high-temperature gas. The gas outlet of the pulsating fluidized bed 31 is connected to the gas inlet of the low-temperature economizer 32, and softening water is introduced into the low-temperature economizer 32. The high-temperature gas is introduced into the low-temperature economizer 32 to exchange heat with the softening water introduced into the low-temperature economizer 32, and at this time the softening water is heated to about 100℃. The water outlet of the low-temperature economizer 32 is connected to the water inlet of the dust removal heat exchanger 33 to introduce the heat-exchanged softening water into the dust removal heat exchanger 33. The gas outlet of the slag throwing shell 21 is connected to the gas inlet of the dust removal heat exchanger 33 and exchanges heat with the softening water to further increase the temperature of the softening water (at this time the temperature of the softening water is about 150℃), and at the same time the dust removal heat exchanger 33 is used for dust removal to ensure that the gas introduced into the atmosphere meets the emission requirements. The gas outlet of the dust removal heat exchanger 33 is connected to the gas inlet of the superheater 34, the gas outlet of the superheater 34 is connected to the gas inlet of the evaporator 35, the water outlet of the dust removal heat exchanger 33 is connected to the water inlet of the evaporator 35, and the steam outlet of the evaporator 35 is connected to the steam inlet of the superheater 34. After the softening water enters the evaporator 35, it is heated by the high-temperature waste gas flowing into the evaporator 35, and the softening water evaporates into saturated steam and is introduced into the superheater 34. The high-temperature waste gas further heats the saturated steam to form superheated steam (at this time the temperature of the superheated steam is about 850℃), which is introduced into the power generation mechanism 4 to do work. As can be seen, the high-temperature waste gas and solid steel slag discharged by the slag throwing mechanism 2 in the present embodiment can be multi-stage ladder heat-exchanged with the softening water in the waste heat recovery mechanism 3, thereby realizing full recovery of the waste heat of molten slag and avoiding waste of energy.

[0047] Figure 1 The structure of the power generation mechanism 4 is shown, and in combination with Figure 1 , the power generation mechanism 4 of the present embodiment is a steam turbine. The superheated steam is introduced into the steam turbine to drive the rotor of the steam turbine to do work and generate electricity. The steam after doing work enters the condenser to become condensed water. The drain outlet of the condenser is connected to the low-temperature economizer 32 to introduce the condensed water into the low-temperature economizer 32, thereby realizing a closed loop of the water circuit.

[0048] Therefore, the arrangement of the waste heat recovery mechanism 3 of the present embodiment makes the energy loss of the entire heat exchange process small, thereby improving the power generation capacity of the power generation mechanism 4. Also, the arrangement avoids waste of water resources and energy. Compared with the dry process, there is no wastewater discharge, and the energy consumption and pollution of the dewatering treatment of water-quenched slag are avoided.

[0049] Figure 9 、 Figure 10 and Figure 11The structure of the dust removal heat exchanger 33 is shown in the structural diagram, combined with Figure 9 、 Figure 10 and Figure 11 , the dust removal heat exchanger 33 of the embodiment comprises a dust removal shell 331, a separation cone 332, a flow guide pipe 333, a dust collection box 334, a high-temperature economizer 335 and a planetary feeder 336, the separation cone 332 and the flow guide pipe 333 are sequentially arranged in the dust removal shell 331 from top to bottom, the dust collection box 334 and the planetary feeder 336 are sequentially arranged at the bottom of the dust removal shell 331 from top to bottom, and the high-temperature economizer 335 is sleeved outside the dust collection box 334. Combined with Figure 10 , an air inlet pipe 3311 is arranged on the outer wall of the top end of the dust removal shell 331, the high-temperature waste gas entering the air inlet pipe 3311 can flow tangentially into the dust removal shell 331 and rotate at high speed along the inner wall surface of the dust removal shell 331. Since the high-temperature waste gas contains small steel slag particles in addition to high-temperature air, the high-temperature waste gas generates centrifugal force when rotating at high speed, the centrifugal force acting on the steel slag particles is much greater than the gravity and the inertial force, and the centrifugal forces acting on the steel slag particles and the gas are different in size, the steel slag particles impact the inner wall of the dust removal shell 331 and fall down, while the high-speed gas flow continues to spiral downward along the inner wall of the dust removal shell 331, so that the small steel slag particles can be separated from the gas flow with high separation efficiency, thereby realizing dust removal of the high-temperature waste gas.

[0050] Combined with Figure 11 , the separation cone 332 is provided with two levels, and a gap is left between each separation cone 332 and the inner wall of the dust removal shell 331, wherein the radius of the upper separation cone 332 is smaller than that of the lower separation cone 332. When the steel slag particles are separated from the high-speed gas flow, the steel slag particles flow downward along the inner wall surface of the dust removal shell 331, the steel slag particles pass through the gap between the separation cone 332 and the dust removal shell 331 and flow into the dust collection box 334 through the flow guide pipe 333, and the high-speed gas flow is separated by the separation cone 332. In this way, the design can effectively prevent the settled steel slag particles from being lifted up by the gas flow, thereby improving the separation efficiency, especially for steel slag particles below 10 μm, the separation effect is more significant.

[0051] Combined with Figure 11The annular air passage 337 is formed between the guide pipe 333 and the inner wall of the dust removal shell 331, and the inner wall of the guide pipe 333 is provided with an array of exhaust holes 3331, so that the inside of the guide pipe 333 is communicated with the annular air passage 337, and the middle section of the dust removal shell 331 is provided with an exhaust pipe 3312 communicated with the annular air passage 337, and the filtered high-temperature waste gas flows from the exhaust holes 3331 of the guide pipe 333 to the annular air passage 337, and then is discharged from the exhaust pipe 3312. In this way, the clean gas can enter the rear flue heat exchange, and the large amount of particulate matters in the flue gas can be prevented from accelerating the wear of the heating surface. The outlet of the low-temperature economizer 32 is communicated with the inlet of the high-temperature economizer 335, so that the softened water entering the high-temperature economizer 335 can exchange heat with the steel slag particles in the dust collecting box 334, and the outlet of the high-temperature economizer 335 is connected with the inlet of the evaporator 35, so that the heat-exchanged softened water can enter the evaporator 35. When a certain amount of steel slag particles are stored in the dust collecting box 334, the planetary feeder 336 is started to discharge the stored steel slag particles.

[0052] The working principle and working process of the steel slag granulation waste heat recovery system will be described in detail below. Figures 1 to 11 The working principle and working process of the steel slag granulation waste heat recovery system will be described in detail below.

[0053] Step 1, determine the amount of slag discharged from the slag pool 1: the linear drive part drives the valve core 132 to move through the connecting rod 131, the inner diameter of the annular discharge channel changes, and the amount of molten slag discharged from the slag pool 1 can be adjusted according to the demand.

[0054] Step 2, spin the slag disc 25: the molten slag in the slag pool 1 flows through the first discharge pipe 11, the overflow pipe 111 and the discharge gap 112, and then flows onto the three-layered slag disc 25. With the rotation of the slag disc 25, the molten slag gradually moves from the center of the disc to the edge of the slag disc 25 along the length direction of the slag disc groove 251 under the centrifugal force. The molten slag forms a spiral motion track in the slag disc 25, and the groove edge of the slag disc groove 251 exerts force on the molten slag, and the force gradually increases with the movement of the molten slag in the slag disc groove 251, so that the molten slag is gradually cut into uniform particles from small slag bodies.

[0055] Step 3, air flow ring cutting: after the molten slag is spun out by the slag disc 25, the molten slag particles spread outward, and at the same time, the high-speed air flow ring 26 sprays high-speed cold air, which cuts the spun-out molten slag, so that the particle size of the molten slag becomes smaller, and the particle size of the discharged slag is more uniform. At this time, high-temperature waste gas and solid steel slag are obtained.

[0056] Step 4, steel slag heat exchange: solid steel slag is introduced onto the gas distribution plate in the pulsating fluidized bed 31, and a second heat exchange gas, which is cooling air, is introduced into the pulsating fluidized bed 31 through the air inlet pipe 311 to fluidize the solid steel slag flowing through the gas distribution plate, the solid steel slag gradually jumps from one end of the pulsating fluidized bed 31 to the other end, and fully contacts and exchanges heat with the introduced cooling air to obtain high-temperature gas; the high-temperature gas is introduced into the low-temperature economizer 32 to exchange heat with the softened water introduced into the low-temperature economizer 32, at this time the softened water is heated to about 100℃.

[0057] Step 5, high-temperature waste gas dust removal: the high-temperature waste gas flows tangentially into the dust removal heat exchanger 33, and rotates at high speed along the inner wall surface of the dust removal shell 331, the high-temperature waste gas generates centrifugal force when rotating at high speed, the centrifugal force on the steel slag particles is much greater than the gravity and inertial force, and the centrifugal forces on the steel slag particles and the gas are different in size, the steel slag particles impact the inner side wall of the dust removal shell 331 and fall, while the high-speed gas continues to spiral downward along the inner wall of the dust removal shell 331, so that the small steel slag particles can be separated from the gas flow; the steel slag particles flow downward along the inner wall surface of the dust removal shell 331, the steel slag particles pass through the gap between the separation cone 332 and the dust removal shell 331, and flow into the dust collection box 334 through the flow guide pipe 333, while the high-speed gas is separated by the separation cone 332, thereby achieving dust removal. The filtered high-temperature waste gas is discharged from the exhaust hole 3331 of the flow guide pipe 333, the annular air duct 337 and the exhaust pipe 3312, flows into the superheater 34, and then flows into the evaporator 35 from the superheater 34.

[0058] Step 6, high-temperature waste gas heat exchange: the softened water flowing out of the low-temperature economizer 32 flows into the high-temperature economizer 335, and exchanges heat with the steel slag particles in the dust collection box 334, at this time the temperature of the softened water rises to about 150°. The softened water flowing out of the high-temperature economizer 335 is introduced into the evaporator 35, and heated by the high-temperature waste gas flowing into the evaporator 35, the softened water evaporates into saturated steam and is introduced into the superheater 34, the high-temperature waste gas further heats the saturated steam to form superheated steam, at this time the temperature of the superheated steam is about 850℃.

[0059] Step 7, power generation: the superheated steam is introduced into the turbine to drive the rotor of the turbine to do work and generate electricity, the steam after doing work enters the condenser to become condensed water, and the condensed water is introduced into the low-temperature economizer 32 to realize the closed loop of the water circuit.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A waste heat recovery system for steel slag granulation, characterized in that, include: Slag pool, which stores molten slag; The slag-throwing mechanism, connected to the slag pool, can throw the molten slag discharged from the slag pool to the surrounding area, so that the thrown molten slag can exchange heat with the first heat exchange gas introduced to obtain high-temperature exhaust gas and solid steel slag. The waste heat recovery mechanism, connected to the slag removal mechanism, is used to exchange heat with high-temperature waste gas and solid steel slag to recover the waste heat from the high-temperature waste gas and solid steel slag. The slag-throwing mechanism includes an upper slag-throwing disc, a middle slag-throwing disc, and a bottom slag-throwing disc for throwing molten slag. Each slag-throwing disc has multiple circumferentially arranged slag-throwing grooves, the depth of which gradually increases from the axis to the edge. The slag-throwing grooves are configured to apply force to the molten slag as it moves along the length of the slag-throwing groove under centrifugal force, thereby cutting the molten slag into granular form. Each slag-throwing disc is surrounded by a fixed high-speed airflow ring, which has an annular air outlet along its circumference. The high-speed airflow ring discharges air to perform circumferential cutting on the thrown molten slag. The slag pool is connected to the slag throwing mechanism through the first discharge pipe. The first discharge pipe is provided with multiple overflow pipes corresponding to the positions of the upper and middle slag throwing plates. The lower pipe opening of the first discharge pipe is provided with multiple discharge slots along the circumferential direction that form with the surface of the bottom slag throwing plate.

2. The steel slag granulation waste heat recovery system according to claim 1, characterized in that, The waste heat recovery mechanism includes a pulsating fluidized bed, a low-temperature economizer, a dust removal heat exchanger, a superheater, and an evaporator. The pulsating fluidized bed is connected to the slag removal mechanism. A second heat exchange gas is introduced into the pulsating fluidized bed to exchange heat with the solid steel slag flowing into the pulsating fluidized bed, resulting in high-temperature gas. The high-temperature gas is introduced into the low-temperature economizer to exchange heat with the softened water introduced into the low-temperature economizer. The high-temperature waste gas flowing out of the slag removal mechanism flows sequentially through the dust removal heat exchanger, the superheater, and the evaporator. The softened water flowing out of the low-temperature economizer flows sequentially through the dust removal heat exchanger, the evaporator, and the superheater to exchange heat with the high-temperature waste gas in stages, resulting in superheated steam.

3. The steel slag granulation waste heat recovery system according to claim 2, characterized in that, It also includes a power generation mechanism connected to the superheater, through which superheated steam is introduced to generate electricity.

4. The steel slag granulation waste heat recovery system according to claim 3, characterized in that, The power generation unit is connected to a low-temperature economizer so that the softened water after it has done work can be fed into the low-temperature economizer.

5. The steel slag granulation waste heat recovery system according to claim 2, characterized in that, The dust removal heat exchanger includes a dust removal shell, a separation cone, a guide pipe, a dust collection box, and a high-temperature economizer. The separation cone and guide pipe are arranged sequentially from top to bottom inside the dust removal shell, the dust collection box is located at the bottom of the dust removal shell, and the high-temperature economizer is fitted outside the dust collection box. High-temperature exhaust gas flows tangentially into the dust removal shell to separate the high-temperature gas from the steel slag particles. The separation cone isolates the high-temperature gas and steel slag particles so that the steel slag particles fall into the dust collection box. An annular air passage is formed between the guide pipe and the inner wall of the dust removal shell, communicating with the inside of the guide pipe. The separated high-temperature gas flows sequentially through the guide pipe and the annular air passage into the superheater. Softened water discharged from the low-temperature economizer is introduced into the high-temperature economizer to exchange heat with the steel slag particles.

6. The steel slag granulation waste heat recovery system according to claim 1, characterized in that, The slag pool is equipped with at least two levels of anti-condensation baffles arranged vertically and vertically along the feeding direction.

7. The steel slag granulation waste heat recovery system according to claim 1, characterized in that, The discharge port of the slag pool is equipped with a flow control valve to control the amount of slag discharged from the slag pool.

8. The steel slag granulation waste heat recovery system according to claim 7, characterized in that, The flow control valve includes a linear drive unit, a connecting rod, and a valve core. The valve core has a trapezoidal cross-section and is inserted into the discharge port of the slag pool. One end of the connecting rod is connected to the valve core, and the other end is connected to the linear drive unit for driving.

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