Steel slag waste heat recovery furnace with upper hearth and lower hearth

Abstract

A steel slag waste heat recovery furnace with an upper hearth and a lower hearth belongs to the technical field of waste heat recovery devices, aims to solve the problems of poor recovery efficiency and large occupied area of an existing steel slag waste heat recovery device, and comprises a lower air distribution plate, the lower hearth, the upper hearth, a separator, a material return pipe, a tail flue, an upper air distribution plate, an air supply unit and an air exhaust unit, the lower hearth is located at the air outlet end of the air supply unit, the upper hearth is located over the lower hearth, the separator is arranged on one side of the upper hearth, the feeding end of the separator is communicated with the upper portion of the upper hearth through a pipeline, the material return pipe is arranged at the bottom of the separator, and one end of the material return pipe is communicated with the discharging end of the separator. The other end of the material return pipe communicates with the lower portion of the upper hearth, the tail flue is arranged on one side of the separator, the smoke inlet end of the tail flue communicates with the smoke outlet end of the separator, the smoke exhaust end of the tail flue communicates with the air inlet end of the air exhaust unit, and the efficient steel slag waste heat recovery device is mainly used as the efficient steel slag waste heat recovery device.

Description

Technical Field

[0001] The invention belongs to the technical field of waste heat recovery devices, and in particular relates to an upper and lower double-hearth steel slag waste heat recovery furnace. Background Art

[0002] The temperature of high-temperature steel slag is about 1450℃, and the slag is usually discharged intermittently, so it is very difficult to recycle its heat energy. The common blast furnace water quenching treatment can only recycle 10% of the heat of the slag, and the remaining 90% of the heat can only be wasted. At present, the research on dry granulation of blast furnace slag at home and abroad has entered the pilot stage, and its methods are divided into two categories: ordinary type and fluidized bed type.

[0003] 1. Ordinary waste heat recovery. This method is to first pour the liquid blast furnace slag into an inclined slag ditch. When the liquid slag flows out at the end of the slag ditch, it contacts the high-speed air flow coming out from the bottom. The slag temperature drops from 1550℃ to 1000℃ and is granulated before entering the heat exchanger. The slag is then cooled to 300℃ in the heat exchanger and the heat is recovered. This method can recover 40%-45% of the heat. However, it is still lower than the fluidized bed method, and the slag particle size after treatment is uneven.

[0004] 2. Fluidized bed heat recovery. The fluidized bed uses air as the fluidizing gas. During the treatment process, the slag particles are fully in contact with the fluidizing gas, and the contact area is increased, so the heat exchange is relatively sufficient and the slag heat recovery rate is greatly improved. There are two types of fluidized bed recovery methods: conventional dry granulation method and molten blast furnace slag granulation method. The latter is more mature and the recovery rate can reach 70%. Its core equipment is the molten blast furnace slag granulation equipment, and the heat recovery process is: 1) The liquid blast furnace slag particles are thrown out from the cup, and through heat exchange with the air from the lower fluidized bed and the water-cooled wall, about 14% of the heat is recovered; 2) The blast furnace slag then hits the inner wall of the container and exchanges heat with the water-cooled wall, recovering about 23% of the heat; 3) The blast furnace slag particles rebounded from the inner wall enter the primary fluidized bed, and heat exchange and cool with the air passing through the fluidized bed and the heat exchange tubes located in the bed layer, recovering about 43% of the heat; 4) The primary fluidized bed expands rapidly due to heat, and the hot slag enters the secondary fluidized bed, energy-saving heat exchange, and recovers about 20% of the heat. This fluidized bed structure is complex and occupies a large area. Summary of the invention

[0005] The present invention aims to solve the problems of poor recovery efficiency and large footprint of existing steel slag waste heat recovery devices; and further provides an upper and lower double-hearth steel slag waste heat recovery furnace;

[0006] A steel slag waste heat recovery furnace with upper and lower double furnaces, the waste heat recovery furnace comprises a lower air distribution plate, a lower furnace, an upper furnace, a separator, a return pipe, a tail flue, an upper air distribution plate, an air supply unit and an exhaust unit, the lower furnace is located on the air outlet end of the air supply unit, and the lower furnace is connected with the air supply unit through the lower air distribution plate, the upper furnace is located directly above the lower furnace, and the upper furnace is connected with the lower furnace through the upper air distribution plate, the separator is arranged on one side of the upper furnace, and the feed end of the separator is connected with the upper part of the upper furnace through a pipeline, the return pipe is arranged at the bottom of the separator, and one end of the return pipe is connected with the discharge end of the separator, and the other end of the return pipe is connected with the lower part of the upper furnace, the tail flue is arranged on one side of the separator, and the smoke inlet end of the tail flue is connected with the smoke outlet end of the separator, and the smoke exhaust end of the tail flue is connected with the air inlet end of the exhaust unit;

[0007] Further, the air supply unit includes an air supply fan and an air chamber, the air supply fan is arranged on one side of the air chamber, and the air outlet end of the air supply fan is connected with the air inlet end of the air chamber through a pipeline, the lower furnace is located at the top of the air chamber, and the lower furnace is connected with the top air outlet end of the air chamber through a lower air distribution plate;

[0008] Furthermore, the waste heat recovery furnace further includes a connecting pipe, which is located below the return pipe, one end of which is connected to the upper part of the lower furnace, and the other end of which is connected to the lower part of the upper furnace;

[0009] Furthermore, a superheater and an economizer are connected in series in the tail flue along the flue gas flow direction;

[0010] Furthermore, the exhaust unit includes a dust collector and an induced draft fan, the smoke exhaust end of the tail flue is connected to the air inlet end of the dust collector, and the air outlet end of the dust collector is connected to the air inlet end of the induced draft fan through a pipeline;

[0011] Furthermore, the waste heat recovery furnace also includes a high-temperature steel slag feeding pipe, one end of which is inserted into the lower part of the upper furnace, and the high-temperature steel slag feeding pipe is connected to the upper furnace;

[0012] Furthermore, the waste heat recovery furnace also includes a low-temperature steel slag discharge pipe, one end of which is inserted into the upper part of the lower furnace, and the high-temperature steel slag feeding pipe is connected to the lower furnace;

[0013] Furthermore, the waste heat recovery furnace further comprises a boiler drum, a downcomer and a membrane water-cooled wall, the boiler drum is mounted on the outer top of the upper furnace, the membrane water-cooled wall is circumferentially arranged on the upper part of the upper furnace, and the liquid outlet end of the boiler drum is connected to the liquid inlet end of the membrane water-cooled wall through the downcomer, and the liquid outlet end of the membrane water-cooled wall is connected to the reflux end of the boiler drum through a pipeline;

[0014] Furthermore, the liquid outlet end of the economizer is connected to the liquid inlet end of the drum through a pipeline, the feed water is heated by the economizer and then fed to the drum, and the steam outlet end of the drum is connected to the superheater through a pipeline;

[0015] Furthermore, the arrangement position of the membrane water-cooled wall is higher than the connection position between the high-temperature slag feeding pipe and the upper furnace and the connection position between the return pipe and the upper furnace;

[0016] The beneficial effects of this application compared to the prior art are as follows:

[0017] The present application provides a steel slag waste heat recovery furnace with an upper and lower double furnace, which adopts a new arrangement method of the upper and lower double furnaces. The device is extended longitudinally by superimposing the furnaces, which greatly occupies horizontal space and saves the floor space when the device is arranged. This arrangement method, on the one hand, can make the incoming air be transported from low to high under the action of the fan, reduce the number of connecting pipes in the device, simplify the device structure, and save manufacturing costs. On the other hand, it can also make the device have a longer tail flue, providing sufficient installation space for the superheater and the economizer, so as to ensure that the steel slag waste heat can be fully utilized.

[0018] The present application provides a waste heat recovery furnace for steel slag with upper and lower double furnaces. By fluidizing the hot steel slag, a part of the hot steel slag rises in the center of the furnace and then returns to the upper furnace distribution plate along the water-cooled walls around the upper furnace to form an internal circulation, and the other part of the hot steel slag is sent to the separator and effectively classified. For the light hot steel slag, it is allowed to enter the tail flue with the flue gas, and then passes through the superheater and economizer in turn, and finally passes through the dust collector to obtain clean flue gas discharge. For the heavy hot steel slag, it returns to the upper furnace through the return pipe to form an external circulation. Through the continuous internal and external circulation of the hot steel slag, its high-temperature waste heat can be fully and effectively recovered. The use of this device to recover waste heat from hot steel slag can recover 80%-85% of the heat, which is much higher than the existing waste heat recovery equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of the upper and lower double-hearth steel slag waste heat recovery furnace described in this application;

[0020] In the figure, 1 is a blower, 2 is an air chamber, 3 is a lower air distribution plate, 4 is a lower furnace, 5 is an upper furnace, 6 is a separator, 7 is a return pipe, 8 is a tail flue, 9 is a superheater, 10 is an economizer, 11 is a dust collector, 12 is an induced draft fan, 13 is a high-temperature slag feeding pipe, 14 is a boiler drum, 15 is a downcomer, 16 is a membrane water-cooled wall, 17 is a low-temperature slag discharge pipe, 18 is a connecting pipe and 19 is an upper air distribution plate. DETAILED DESCRIPTION

[0021] Specific implementation method 1: Combination Figure 1The present embodiment is described. In the present embodiment, a steel slag waste heat recovery furnace with an upper and lower double furnace is provided, which is characterized in that the waste heat recovery furnace comprises a lower air distribution plate 3, a lower furnace 4, an upper furnace 5, a separator 6, a return pipe 7, a tail flue 8, an upper air distribution plate 19, an air supply unit and an exhaust unit. The lower furnace 4 is located on the air outlet end of the air supply unit, and the lower furnace 4 is connected to the air supply unit through the lower air distribution plate 3. The upper furnace 5 is located directly above the lower furnace 4, and the upper furnace 5 is connected to the lower furnace 4 through the upper air distribution plate 19. The separator 6 is arranged on one side of the upper furnace 5, and the feeding end of the separator 6 is connected with the upper part of the upper furnace 5 through a pipeline, the return pipe 7 is arranged at the bottom of the separator 6, and one end of the return pipe 7 is connected with the discharging end of the separator 6, and the other end of the return pipe 7 is connected with the lower part of the upper furnace 5, the tail flue 8 is arranged on one side of the separator 6, and the smoke inlet end of the tail flue 8 is connected with the smoke outlet end of the separator 6, and the smoke exhaust end of the tail flue 8 is connected with the air inlet end of the exhaust unit.

[0022] In the present embodiment, the upper furnace and the lower furnace are stacked in an arrangement to reduce the arrangement space of the device, greatly saving the floor space occupied when the device is arranged. The return pipe 7 is inserted downwardly at an angle at the lower part of the upper furnace 5. Such an arrangement can ensure that the reflux slag can smoothly enter the upper furnace 5, avoiding jamming at the connection between the discharge end of the return pipe 7 and the upper furnace 5.

[0023] Specific implementation method 2: Combination Figure 1 This embodiment is described. The difference between this embodiment and the first embodiment is that the air supply unit includes an air blower 1 and an air chamber 2. The air blower 1 is arranged at one side of the air chamber 2, and the air outlet of the air blower 1 is connected to the air inlet of the air chamber 2 through a pipeline. The lower furnace 4 is located at the top of the air chamber 2, and the lower furnace 4 is connected to the top air outlet of the air chamber 2 through a lower air distribution plate 3. Other components and connection methods are the same as those of the first embodiment.

[0024] Specific implementation method three: Combination Figure 1 This embodiment is described. The difference between this embodiment and the second embodiment is that the waste heat recovery furnace further includes a connecting pipe 18, which is located below the return pipe 7, one end of the connecting pipe 18 is connected to the upper part of the lower furnace 4, and the other end of the connecting pipe 18 is connected to the lower part of the upper furnace 5. Other components and connection methods are the same as those of the second embodiment.

[0025] This arrangement is to allow large particles of slag at the upper furnace air distribution plate to return to the lower furnace 4 through the connecting pipe 18 for further heat exchange, and then the cold slag is discharged out of the furnace through the cold slag discharge port 17.

[0026] Specific implementation method four: Combination Figure 1This embodiment is described. The difference between this embodiment and the third embodiment is that a superheater 9 and an economizer 10 are sequentially connected in series along the flue gas flow direction on the tail flue 8. The other components and connection methods are the same as those of the third embodiment.

[0027] Specific implementation method five: Combination Figure 1 This embodiment is described. The difference between this embodiment and the fourth embodiment is that the exhaust unit includes a dust collector 11 and an induced draft fan 12. The exhaust end of the tail flue 8 is connected to the air inlet end of the dust collector 11, and the air outlet end of the dust collector 11 is connected to the air inlet end of the induced draft fan 12 through a pipeline. Other components and connection methods are the same as those of the fourth embodiment.

[0028] With such arrangement, the dust collector 11 is used to remove dust from the flue gas after heat recovery, thereby ensuring that the exhaust flue gas is clean and will not cause significant pollution to the environment.

[0029] Specific implementation method six: Combination Figure 1 This embodiment is described. The difference between this embodiment and the fifth embodiment is that the waste heat recovery furnace further includes a high-temperature slag feeding pipe 13, one end of which is inserted into the lower part of the upper furnace 5, and the high-temperature slag feeding pipe 13 is connected to the upper furnace 5. Other components and connection methods are the same as those of the fifth embodiment.

[0030] Specific implementation method seven: Combination Figure 1 This embodiment is described. The difference between this embodiment and the sixth embodiment is that the waste heat recovery furnace further includes a low-temperature slag discharge pipe 17, one end of which is inserted into the upper part of the lower furnace 4, and the high-temperature slag feeding pipe 13 is connected to the lower furnace 4. Other components and connection methods are the same as those of the sixth embodiment.

[0031] In combination with the description of specific implementation methods six and seven, the high-temperature steel slag feeding pipe 13 is used to inject high-temperature steel slag into the waste heat recovery furnace, and the low-temperature steel slag discharge pipe 17 is used to discharge the low-temperature steel slag after waste heat recovery, wherein the high-temperature steel slag feeding pipe 13 is inserted into the upper furnace 5 at an angle downward to avoid feed blockage, and the low-temperature steel slag discharge pipe 17 is inserted into the lower furnace 4 at an angle upward to ensure smooth slag discharge.

[0032] Specific implementation method eight: Combination Figure 1This embodiment is described. The difference between this embodiment and the seventh embodiment is that the waste heat recovery furnace further includes a drum 14, a downcomer 15 and a membrane water-cooled wall 16. The drum 14 is installed on the outer top of the upper furnace 5. The membrane water-cooled wall 16 is arranged circumferentially on the upper part of the upper furnace 5. The liquid outlet end of the drum 14 is connected to the liquid inlet end of the membrane water-cooled wall 16 through the downcomer 15, and the liquid outlet end of the membrane water-cooled wall 16 is connected to the reflux end of the drum 14 through a pipeline. Other components and connection methods are the same as those of the seventh embodiment.

[0033] Specific implementation method nine: Combination Figure 1 This embodiment is described. The difference between this embodiment and the eighth embodiment is that the liquid outlet of the economizer 10 is connected to the liquid inlet of the drum 14 through a pipeline, the feed water is heated by the economizer 10 and then fed to the drum 14, and the steam outlet of the drum 14 is connected to the superheater 9 through a pipeline. Other components and connection methods are the same as those of the eighth embodiment.

[0034] Specific implementation method ten: Combination Figure 1 This embodiment is described. The difference between this embodiment and the eighth embodiment is that the arrangement position of the membrane water-cooled wall 16 is higher than the connection position between the high-temperature slag feeding pipe 13 and the upper furnace 5 and the connection position between the return pipe 7 and the upper furnace 5. The other components and connection methods are the same as those of the ninth embodiment.

[0035] In combination with the description of specific embodiments eight to ten, the boiler drum 14, the downcomer 15 and the membrane water-cooled wall 16 constitute a heat exchange system. The feed water is heated by the economizer 10 and then supplied to the boiler drum 14. The boiler drum 14 distributes the feed water to the water-cooled wall through the downcomer 15. The feed water rises through the membrane water-cooled wall 16 and exchanges heat with the high-temperature flue gas and hot slag while rising to form a steam-water mixture. The steam-water mixture is separated in the boiler drum 14, and the hot steam enters the superheater 9, while the liquid continues to circulate. With this arrangement, the waste heat of the hot slag and the high-temperature flue gas can be further recovered, so that the heat recovery is more sufficient and the waste of heat is avoided.

[0036] The present invention has been disclosed as above with preferred implementation cases, but it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent implementation cases with equivalent changes by using the above-disclosed structures and technical contents without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above implementation cases based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

[0037] How it works

[0038] The high-temperature slag is fed into the upper furnace 5 through the charging port 13, and enters the fluidized state under the action of the high-pressure fluidizing air in the air hood of the air distribution plate 3. After a part of the hot slag rises and passes through the separator 6, the light hot slag enters the tail flue 8 with the hot flue gas. The high-temperature flue gas containing some light slag passes through the superheater 9 and the economizer 10 in turn, and then passes through the dust collector 11, and the clean flue gas is discharged. The heavy hot slag returns to the upper furnace 5 through the return valve 7 to form an external circulation; after a part of the hot slag rises in the center of the furnace, it returns to the upper furnace distribution plate along the water-cooled walls around the upper furnace to form an internal circulation.

[0039] The large particles of slag at the upper furnace air distribution plate return to the lower furnace 4 through the connecting pipe 18 for further heat exchange, and the cold slag is discharged out of the furnace through the cold slag discharge port 17.

[0040] Qualified feed water is heated by economizer 10 and then fed to boiler drum 14. Boiler drum 14 distributes feed water to the inlet of membrane water-cooled wall 16 of lower furnace through downcomer 15. Water rises through membrane water-cooled wall 16 and undergoes heat exchange with high-temperature flue gas and hot slag during the rising process to become steam-water mixture. The high-temperature steam-water mixture enters boiler drum 14, steam and water are separated inside boiler drum 14, water returns to downcomer 15 to continue circulating and absorbing heat, steam enters superheater 10 to continue absorbing heat and is used after reaching the designed temperature and pressure.

[0041] The air is sent into the air chamber 2 by the blower 1, passes through the lower air distribution plate 3, enters the lower furnace 4, passes through the high-temperature slag to become hot flue gas, and then passes through the upper air distribution plate 19 to enter the upper furnace 5. The high-temperature flue gas carries the slag through the separator 6. Most of the slag returns to the upper furnace. A very small amount of fine high slag and high-temperature flue gas enter the tail flue 8 and the superheater 9 and economizer 10. After heat exchange, the low-temperature flue gas passes through the dust collector 11, and the clean low-temperature smoke is discharged through the induced draft fan 12.

Claims

1. An upper and lower double-hearth steel slag waste heat recovery furnace, characterized in that: The waste heat recovery furnace comprises a lower air distribution plate (3), a lower furnace (4), an upper furnace (5), a separator (6), a return pipe (7), a tail flue (8), an upper air distribution plate (19), an air supply unit and an exhaust unit. The lower furnace (4) is located on the air outlet end of the air supply unit, and the lower furnace (4) is connected to the air supply unit through the lower air distribution plate (3). The upper furnace (5) is located directly above the lower furnace (4), and the upper furnace (5) is connected to the lower furnace (4) through the upper air distribution plate (19). The separator (6) is arranged on the upper furnace (5). The separator (6) is provided at one side thereof, and the feed end of the separator (6) is connected to the upper part of the upper furnace (5) through a pipeline; the return pipe (7) is provided at the bottom of the separator (6), and one end of the return pipe (7) is connected to the discharge end of the separator (6), and the other end of the return pipe (7) is connected to the lower part of the upper furnace (5); the tail flue (8) is provided at one side of the separator (6), and the smoke inlet end of the tail flue (8) is connected to the smoke outlet end of the separator (6), and the smoke exhaust end of the tail flue (8) is connected to the air inlet end of the exhaust unit.

2. The upper and lower double-hearth slag waste heat recovery furnace according to claim 1, characterized in that: The air supply unit comprises an air supply fan (1) and an air chamber (2); the air supply fan (1) is arranged on one side of the air chamber (2), and the air outlet end of the air supply fan (1) is connected to the air inlet end of the air chamber (2) through a pipeline; the lower furnace (4) is located at the top of the air chamber (2), and the lower furnace (4) is connected to the top air outlet end of the air chamber (2) through a lower air distribution plate (3).

3. The upper and lower double-hearth slag waste heat recovery furnace according to claim 2, characterized in that: The waste heat recovery furnace also includes a connecting pipe (18), which is located below the return pipe (7), one end of the connecting pipe (18) is connected to the upper part of the lower furnace (4), and the other end of the connecting pipe (18) is connected to the lower part of the upper furnace (5).

4. The upper and lower double-hearth slag waste heat recovery furnace according to claim 3, characterized in that: A superheater (9) and an economizer (10) are sequentially connected in series on the tail flue (8) along the flue gas flow direction.

5. The upper and lower double-hearth steel slag waste heat recovery furnace according to claim 4, characterized in that: The exhaust unit comprises a dust collector (11) and an induced draft fan (12); the smoke exhaust end of the tail flue (8) is connected to the air inlet end of the dust collector (11); and the air outlet end of the dust collector (11) is connected to the air inlet end of the induced draft fan (12) through a pipeline.

6. The upper and lower double-hearth steel slag waste heat recovery furnace according to claim 5, characterized in that: The waste heat recovery furnace also includes a high-temperature slag feeding pipe (13), one end of which is inserted into the lower part of the upper furnace (5), and the high-temperature slag feeding pipe (13) is connected to the upper furnace (5).

7. The upper and lower double-hearth steel slag waste heat recovery furnace according to claim 6, characterized in that: The waste heat recovery furnace also includes a low-temperature slag discharge pipe (17), one end of which is inserted into the upper part of the lower furnace (4), and the high-temperature slag feeding pipe (13) is connected to the lower furnace (4).

8. The upper and lower double-hearth steel slag waste heat recovery furnace according to claim 1, characterized in that: The waste heat recovery furnace also includes a boiler drum (14), a downcomer (15) and a membrane water-cooled wall (16); the boiler drum (14) is installed on the outer top of the upper furnace (5); the membrane water-cooled wall (16) is arranged circumferentially on the upper part of the upper furnace (5); the liquid outlet end of the boiler drum (14) is connected to the liquid inlet end of the membrane water-cooled wall (16) through the downcomer (15); and the liquid outlet end of the membrane water-cooled wall (16) is connected to the reflux end of the boiler drum (14) through a pipeline.

9. The upper and lower double-hearth steel slag waste heat recovery furnace according to claim 8, characterized in that: The liquid outlet end of the economizer (10) is connected to the liquid inlet end of the boiler drum (14) through a pipeline, and the feed water is heated by the economizer (10) and then supplied to the boiler drum (14). The steam outlet end of the boiler drum (14) is connected to the superheater (9) through a pipeline.

10. The upper and lower double-hearth steel slag waste heat recovery furnace according to claim 9, characterized in that: The arrangement position of the membrane water-cooled wall (16) is higher than the connection position between the high-temperature slag feeding pipe (13) and the upper furnace (5) and the connection position between the return pipe (7) and the upper furnace (5).

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