Centrifugal granulation device, waste heat recovery system and waste heat recovery method

Abstract

The invention discloses a centrifugal granulation device, a waste heat recovery system and a waste heat recovery method.The centrifugal granulation device comprises a granulation bin, a powder feeder, a conveying channel and a heat storage device, and the granulation bin is provided with a slag inlet pipe and a granulator located under the slag inlet pipe; a powder feeder for spreading slag powder to the inner wall of the granulation bin to form a powder layer wall surface is arranged on the side wall of the granulation bin, the initial position of the powder layer wall surface is not lower than the top surface of the granulator, the bottom of the granulation bin is communicated with a conveying channel, and the conveying channel comprises a high-temperature slag particle feeding channel, a normal-temperature slag particle feeding channel, a mixing cavity and a mixed slag particle discharging channel; the mixing cavity is communicated with the high-temperature slag particle feeding channel and the normal-temperature slag particle feeding channel, one end of the mixed slag particle discharging channel is communicated with the mixing cavity, and the other end of the mixed slag particle discharging channel is communicated with an inlet of the heat storage device. Through heat exchange between the wall surface of the powder layer and the liquid slag and heat exchange between the high-temperature slag and the normal-temperature slag, slag liquid drops are rapidly cooled, bonding is avoided, and meanwhile the grade of recycled waste heat is considered.

Description

Technical Field

[0001] The present invention relates to the technical field of heat recovery from centrifugal granulation of slag, and in particular to a centrifugal granulation device, a waste heat recovery system and a waste heat recovery method. Background Art

[0002] The steel industry is one of the most energy-intensive industries in China and has played an irreplaceable role in the process of industrial modernization in my country. Liquid blast furnace slag, as the main by-product of blast furnace ironmaking, contains a large amount of waste heat resources. When rapidly cooled, it can form glassy slag with high potential hydration activity, which can be used as cement clinker and has high economic value.

[0003] At present, the widely used treatment method for blast furnace slag at home and abroad is water quenching, that is, the liquid blast furnace slag is in direct contact with water, and the blast furnace slag forms slag particles with a glassy structure in this process. However, the water quenching method has many disadvantages, such as consuming a large amount of water resources, generating sulfide gas to pollute the air during the process, and wasting a large amount of high-grade waste heat. In order to more efficiently realize the recovery and resource utilization of blast furnace slag waste heat, the inventor knows that scholars at home and abroad have proposed a variety of dry granulation waste heat recovery technologies and have carried out a lot of research work. Since the heat exchange capacity of gas is far less than that of liquid water, in order to quickly cool the blast furnace slag, the high-temperature liquid blast furnace slag must be granulated into small droplets, thereby increasing the heat exchange ratio area. According to different granulation methods, the dry recovery process can be divided into drum method, wind quenching method, mechanical stirring method and centrifugal granulation method. Among them, centrifugal granulation waste heat recovery technology is the most feasible solution to solve these problems among many dry treatment technologies because of its advantages such as low energy consumption, good granulation effect and device stability. However, this technology has long faced unresolved bottlenecks, such as the high temperature molten slag droplets are still at high temperature when they hit the wall of the granulation bin, and cannot be quickly cooled on the wall, which is not conducive to the formation of solid slag with high glass content and is easy to stick during transportation. In addition, the intermittently recovered hot air and soda-water mixture is difficult to store and continuously utilize.

[0004] Therefore, there is an urgent need for a centrifugal granulation device, a waste heat recovery system and a waste heat recovery method that can quickly cool the slag droplets on the wall to avoid sticking, while taking into account the recovery of waste heat. Summary of the invention

[0005] The purpose of the present invention is to provide a centrifugal granulation device, a waste heat recovery system and a waste heat recovery method to address the defects and shortcomings in the prior art, so that the slag droplets on the wall of the granulation bin can be quickly cooled to avoid sticking, while taking into account the recovery of waste heat quality.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] The present invention provides a centrifugal granulation device, comprising a granulation bin, a powder feeder, a transport channel and a heat storage device with a heat preservation function, wherein the granulation bin has a slag feed pipe connected to the outside and a rotatable granulator, and the granulator is located directly below the slag feed pipe;

[0008] The side wall of the granulation bin is provided with the powder feeder which can spread slag powder to the inner wall of the granulation bin to form a powder layer wall, and the starting position of the powder layer wall is not lower than the top surface of the granulator, and the bottom of the granulation bin is connected with the transport channel, and the transport channel includes a high-temperature slag particle feeding channel connected with the granulation bin, a normal-temperature slag particle feeding channel for conveying normal-temperature slag particles, a mixing chamber for contact and heat exchange between high-temperature slag particles and normal-temperature slag particles, and a mixed slag particle discharging channel for transporting mixed slag particles, the mixing chamber is respectively connected with the high-temperature slag particle feeding channel and the normal-temperature slag particle feeding channel, one end of the mixed slag particle discharging channel is connected with the mixing chamber, and the other end is connected with the inlet of the heat storage device.

[0009] Preferably, an agitator is provided inside the mixing chamber, and the agitator is located in a region close to the mixed slag particle discharge channel.

[0010] Preferably, the powder feeder comprises a feeding chamber, a spiral feeder disposed in the feeding chamber, a slag powder feeding channel for introducing slag powder, and a slag powder discharging channel for spreading the slag powder on the inner wall of the granulation bin, the slag powder feeding channel is connected to the feeding chamber, one end of the slag powder discharging channel is connected to the feeding chamber, and the other end is connected to the granulation bin, and the slag powder discharging channel is arranged in a circle along the circumference of the granulation bin.

[0011] Preferably, the screw feeder is arranged transversely, and the screw feeder is also arranged in a circle along the circumference of the granulating bin.

[0012] Preferably, the inner wall of the granulation bin is an inclined surface, and the diameter of the granulation bin at one end close to the slag inlet pipe is larger than the diameter of the granulation bin at one end close to the transport channel.

[0013] Preferably, the heat storage device is a movable heat storage device.

[0014] The present invention also provides a waste heat recovery system, comprising the centrifugal granulation device and the heat exchanger, the outlet of the heat storage device is connected to the slag inlet of the heat exchanger, a heat exchange pipe is provided in the heat exchanger, a heat exchange medium is provided in the heat exchange pipe, and the falling path of the introduced slag intersects with the heat exchange pipe to realize heat exchange between the slag and the heat exchange medium.

[0015] Preferably, a curved and folded heat exchange pipe is provided in the heat exchanger.

[0016] Preferably, the slag outlet of the heat exchanger is connected to a particle size screening device.

[0017] The present invention also provides a waste heat recovery method, which uses the waste heat recovery system and includes the following contents:

[0018] S1. Liquid blast furnace slag is introduced into the granulation bin, and the liquid blast furnace slag falls onto the top surface of the granulator. The granulator rotates to throw the liquid blast furnace slag onto the inner wall of the granulation bin; and slag powder is spread onto the inner wall of the granulation bin, so that the liquid blast furnace slag droplets thrown onto the inner wall of the granulation bin fuse with the slag powder to form high-temperature slag particles;

[0019] S2. introducing room temperature slag particles into the mixing chamber so that the room temperature slag particles are in contact with the high temperature slag particles for heat exchange to form mixed slag particles;

[0020] S3. The mixed slag particles are passed into the heat storage device for storage;

[0021] S4. The outlet of the heat storage device storing the mixed slag particles is connected to the slag inlet of the heat exchanger, and the mixed slag particles are introduced into the heat exchanger to exchange heat between the mixed slag particles and the heat exchange medium in the heat exchanger;

[0022] S5. The mixed slag particles after heat exchange are passed into the particle size screening device, and the small-sized slag particles screened out are used to supplement the slag powder falling from the powder feeder, and the large-sized slag particles screened out are passed into the mixing chamber for heat exchange with the high-temperature slag particles.

[0023] Compared with the prior art, the present invention has achieved the following technical effects:

[0024] On the one hand, the present invention spreads room temperature blast furnace slag powder on the inner wall surface of the granulation bin, so that the granulated droplets contact the slag powder layer when colliding with the inner wall surface of the granulation bin and are embedded in the blast furnace slag powder, effectively increasing the heat exchange area of ​​the molten slag droplets formed after the liquid blast furnace slag collides, and at the same time, due to the significant temperature difference between the two, the cooling effect of the molten slag droplets is further enhanced. On the other hand, by introducing room temperature slag into the mixing chamber of the transport channel, the room temperature slag is heat exchanged with the mixture of high temperature slag and slag powder discharged from the granulation bin, and after the room temperature slag and the mixture of high temperature slag and slag powder are introduced into the heat storage device, the room temperature slag and the high temperature slag can continuously exchange heat in the heat storage device, so that the high temperature slag is cooled to about 700°C, at which time the glass phase content of the blast furnace slag no longer changes, and the mixture of high temperature slag particles and slag powder as a heat storage material is easy to store and can achieve the effect of efficient use of waste heat, achieving a balance between glass phase content and waste heat recovery quality.

[0025] In summary, the present invention can accelerate the cooling rate of molten slag droplets, prevent the droplets from sticking during the collision with the wall, transportation and cooling process, and increase the glass phase content of the treated blast furnace slag, thereby improving the economic value of the blast furnace slag, while taking into account the recovery of waste heat quality, so that intermittent waste heat can be stored and efficiently utilized. This innovative method has a wide range of application prospects, and is particularly suitable for improving the treatment efficiency and economic utilization rate of blast furnace slag, and can be regarded as an effective blast furnace slag treatment technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 It is a structural schematic diagram of a centrifugal granulation device disclosed in a specific embodiment of the present invention;

[0028] Figure 2 It is a schematic structural diagram of a waste heat recovery system disclosed in a specific embodiment of the present invention.

[0029] Among them, 1. granulation bin; 11. slag inlet pipe; 12. powder layer wall; 13. granulator;

[0030] 2. Powder feeder; 21. Slag powder feeding channel; 22. Screw feeder; 23. Slag powder discharging channel;

[0031] 3. Transport channel; 31. Normal temperature slag feeding channel; 32. Agitator; 33. High temperature slag feeding channel; 34. Mixing chamber; 35. Mixed slag discharging channel;

[0032] 4. Mobile heat storage device; 41. Heat storage device; 42. Trailer;

[0033] 5. Heat exchanger; 51. Slag inlet; 52. Heat exchange pipe; 53. Slag outlet. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] like Figure 1 As shown, the present invention provides a centrifugal granulation device, including a granulation bin 1, a powder feeder 2, a transport channel 3 and a heat storage device 41 with a heat preservation function, the granulation bin 1 has a slag feeding pipe 11 connected to the outside and a rotatable granulator 13, and the granulator 13 is located directly below the slag feeding pipe 11; if the slag feeding pipe 11 and the granulator 13 are located at a position deviated from the center of the granulation bin 1, a part of the high-temperature slag may not be thrown to the inner wall surface of the granulation bin 1, so in one embodiment, the slag feeding pipe 11 and the granulator 13 are both located at the center of the granulation bin 1.

[0037] The side wall of the granulation bin 1 is provided with a powder feeder 2 which can spread slag powder to the inner wall of the granulation bin 1 to form a powder layer wall 12, and the starting position of the powder layer wall 12 is not lower than the top surface of the granulator 13. The bottom of the granulation bin 1 is connected with the transport channel 3, and the transport channel 3 includes a high-temperature slag particle feeding channel 33 connected with the granulation bin 1, a normal temperature slag particle feeding channel 31 for conveying normal temperature slag particles, a mixing chamber 34 for contact heat exchange between high-temperature slag particles and normal temperature slag particles, and a mixed slag particle discharging channel 35 for transporting the mixed slag particles. The mixing chamber 34 is respectively connected with the high-temperature slag particle feeding channel 33 and the normal temperature slag particle feeding channel 31, and one end of the mixed slag particle discharging channel 35 is connected with the mixing chamber 34, and the other end is connected with the entrance of the heat storage device 41.

[0038] During operation, the liquid blast furnace slag at up to 1500°C produced by the blast furnace flows into the granulation bin 1 through the slag inlet pipe 11, falls on the high-speed rotating granulator 13, and is dispersed into molten droplets under the action of centrifugal force, etc. The droplets fly and hit the wall surface 12 of the powder layer. During the collision process, the droplets spread, retract, rebound, deposit, splash and break, forming droplets with smaller particle size. At the same time, the slag powder is embedded in the droplets to cool them quickly. The broken droplets are transported with the slag powder. In this process, the droplets not only continue to contact and exchange heat with the slag powder, but also radiate and convect heat with the surrounding environment of the granulation bin 1, gradually solidify to form high-temperature slag particles, and the high-temperature slag particles and slag powder are discharged into the transport channel 3 together. Room-temperature slag particles are introduced into the mixing chamber 34 from the room-temperature slag particle feeding channel 31, and the room-temperature slag particles are mixed with the mixture of high-temperature slag particles and slag powder discharged from the granulation bin 1 for contact heat exchange. Then the mixed slag particles enter the heat storage device 41 for storage. In the heat storage device 41, due to the temperature difference, the mixture of high-temperature slag particles and slag powder will absorb heat by the room-temperature slag particles, so that the high-temperature slag particles are further cooled to about 700°C, and the glass phase content of the slag particles no longer changes.

[0039] An agitator 32 is arranged inside the mixing chamber 34. The agitator 32 is located in a region close to the mixed slag particle discharge channel 35. The agitator 32 may adopt an existing structure. The mixing uniformity of the high-temperature slag particles and the normal-temperature slag particles can be improved through stirring, and the temperature of the high-temperature slag particles can be further reduced.

[0040] The powder feeder 2 includes a feeding chamber, a spiral feeder 22 placed in the feeding chamber, a slag powder feeding channel 21 for introducing slag powder, and a slag powder discharging channel 23 for spreading the slag powder on the inner wall of the granulation bin 1. The slag powder feeding channel 21 is connected to the feeding chamber, and one end of the slag powder discharging channel 23 is connected to the feeding chamber and the other end is connected to the granulation bin 1. The slag powder discharging channel 23 is arranged in a circle along the circumference of the granulation bin 1 to spread the slag powder to various parts of the inner wall of the granulation bin 1. Figure 1 It can be seen that a slit is provided on the bottom surface of the feeding cavity, and the slit is the slag powder discharge channel 23 .

[0041] The screw feeder 22 can be arranged in the vertical direction or in the horizontal direction. If the screw feeder 22 is arranged in the vertical direction, multiple powder feeders 2 need to be evenly arranged in the circumference of the granulation bin 1 to ensure that the slag powder discharge channel 23 can cover the entire inner circumference of the granulation bin 1. In one embodiment, the screw feeder 22 is arranged in the horizontal direction, and the auger of the screw feeder 22 is arranged in a circle along the circumference of the granulation bin 1 to evenly spread the slag powder on the inner wall of the granulation bin 1. The specific screw feeder 22 is a flexible annular screw feeder.

[0042] The inner wall of the granulation bin 1 is an inclined surface, and the diameter of the granulation bin 1 near the slag inlet pipe 11 is larger than the diameter of the granulation bin 1 near the transport channel 3, so as to collect high-temperature slag particles and transport them to the mixing chamber 34 of the transport channel 3.

[0043] Furthermore, the heat storage device 41 is configured as a movable heat storage device 4. The heat storage device 41 can be moved by providing wheels / a transportation vehicle with wheels at the bottom of the heat storage device 41, or by providing a slider at the bottom of the heat storage device 41 and providing a slide rail compatible with the slider, etc. In one embodiment, a trailer 42 is provided at the bottom of the heat storage device 41.

[0044] like Figure 2As shown, the present invention also provides a waste heat recovery system, including a centrifugal granulation device and a heat exchanger 5, the outlet of the heat storage device 41 is connected to the slag inlet 51 of the heat exchanger 5, a heat exchange pipe 52 is provided in the heat exchanger 5, a heat exchange medium is provided in the heat exchanger 5, and the falling path of the slag intersects with the heat exchange pipe 52 to achieve heat exchange between the slag and the heat exchange medium. In order to further improve the heat exchange efficiency, a curved and folded heat exchange pipe 52 is provided in the heat exchanger 5. Furthermore, the heat exchange medium in the heat exchange pipe 52 is water. Since the temperature of the slag particles in the heat storage device 41 is about 700°C, when necessary, the slag particles in the heat storage device 41 are transported to the heat exchanger 5, and the waste heat of the slag particles is used to exchange heat with water to produce high-temperature steam for peak load regulation of thermal power units, thereby fully utilizing the heat in the slag particles.

[0045] The slag outlet 53 of the heat exchanger 5 is connected to the particle size screening device. The small-sized slag particles screened by the particle size screening device are sent to the slag powder feeding channel 21 to replenish the slag powder to the powder feeder 2, and the large-sized slag particles screened are sent to the normal temperature slag particle feeding channel 31 for recycling. Figure 2 The arrows disposed at both ends of the heat exchange pipe 52 are used to indicate the flow direction of the heat exchange medium.

[0046] The present invention also provides a waste heat recovery method, which uses the above waste heat recovery system and includes the following contents:

[0047] S1. Liquid blast furnace slag is introduced into the granulation bin 1, and the liquid blast furnace slag falls into the top surface of the granulator 13. The granulator 13 rotates to throw the liquid blast furnace slag to the inner wall of the granulation bin 1; and slag powder is spread on the inner wall of the granulation bin 1, so that the liquid blast furnace slag droplets thrown to the inner wall of the granulation bin 1 merge with the slag powder to form high-temperature slag particles;

[0048] When in use, slag powder is first spread on the inner wall of the granulation bin 1, and then liquid blast furnace slag is introduced.

[0049] S2. Introduce room temperature slag particles into the mixing chamber 34, so that the room temperature slag particles are in contact with the high temperature slag particles for heat exchange to form mixed slag particles;

[0050] At this time, the mixing chamber 34 contains a mixture of high-temperature slag particles, slag powder, and room-temperature slag particles;

[0051] S3. The mixed slag particles are passed into the heat storage device 41 for storage;

[0052] The high-temperature slag particles fully exchange heat with the room-temperature slag particles in the heat storage device 41, and finally the temperature of the high-temperature slag particles is reduced to below the glass transition temperature, achieving a balance between the glass phase content and the quality of waste heat recovery. Moreover, compared with the by-product high-temperature steam formed by cooling the high-temperature slag particles by cooling air and cooling water, the cooled slag particles are easier to store.

[0053] S4. The outlet of the heat storage device 41 storing the mixed slag particles is connected to the slag inlet 51 of the heat exchanger 5, and the mixed slag particles are introduced into the heat exchanger 5, so that the mixed slag particles and the heat exchange medium in the heat exchanger 5 can exchange heat, so as to fully utilize the stored waste heat.

[0054] S5. The mixed slag particles after heat exchange are passed into the particle size screening device, and the small-sized slag particles screened out are used to supplement the slag powder falling from the powder feeder 2, and the large-sized slag particles screened out are passed into the mixing chamber 34 for heat exchange with the high-temperature slag particles, thereby realizing the reuse of resources.

[0055] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any figure mark in the claims should not be regarded as limiting the claims involved.

Claims

1. A centrifugal granulation device, characterized in that: It includes a granulation bin, a powder feeder, a transport channel and a heat storage device with a heat preservation function. The granulation bin has a slag feeding pipe connected to the outside and a rotatable granulator, and the granulator is located directly below the slag feeding pipe; The side wall of the granulation bin is provided with the powder feeder which can spread slag powder to the inner wall of the granulation bin to form a powder layer wall, and the starting position of the powder layer wall is not lower than the top surface of the granulator, and the bottom of the granulation bin is connected with the transport channel, and the transport channel includes a high-temperature slag particle feeding channel connected with the granulation bin, a normal-temperature slag particle feeding channel for conveying normal-temperature slag particles, a mixing chamber for contact and heat exchange between high-temperature slag particles and normal-temperature slag particles, and a mixed slag particle discharging channel for transporting mixed slag particles, the mixing chamber is respectively connected with the high-temperature slag particle feeding channel and the normal-temperature slag particle feeding channel, one end of the mixed slag particle discharging channel is connected with the mixing chamber, and the other end is connected with the inlet of the heat storage device.

2. The centrifugal granulation device according to claim 1, characterized in that: An agitator is provided inside the mixing chamber, and the agitator is located in a region close to the mixed slag particle discharge channel.

3. The centrifugal granulation device according to claim 1, characterized in that: The powder feeder includes a feeding chamber, a spiral feeder disposed in the feeding chamber, a slag powder feeding channel for introducing slag powder, and a slag powder discharging channel for spreading the slag powder on the inner wall of the granulation bin, the slag powder feeding channel is connected to the feeding chamber, one end of the slag powder discharging channel is connected to the feeding chamber, and the other end is connected to the granulation bin, and the slag powder discharging channel is arranged in a circle along the circumference of the granulation bin.

4. The centrifugal granulation device according to claim 3, characterized in that: The screw feeder is arranged transversely, and the screw feeder is also arranged in a circle along the circumference of the granulating bin.

5. The centrifugal granulation device according to claim 1, characterized in that: The inner wall of the granulation bin is an inclined surface, and the diameter of the granulation bin at one end close to the slag inlet pipe is larger than the diameter of the granulation bin at one end close to the transport channel.

6. The centrifugal granulation device according to claim 1, characterized in that: The heat storage device is a movable heat storage device.

7. A waste heat recovery system, characterized in that: It comprises the centrifugal granulation device and the heat exchanger according to any one of claims 1 to 6, the outlet of the heat storage device is connected with the slag inlet of the heat exchanger, the heat exchanger is provided with a heat exchange pipe, the heat exchange pipe is provided with a heat exchange medium, and the falling path of the introduced slag intersects with the heat exchange pipe to realize heat exchange between the slag and the heat exchange medium.

8. The waste heat recovery system according to claim 7, characterized in that: The heat exchanger is provided with a bent and folded heat exchange pipe.

9. The waste heat recovery system according to claim 8, characterized in that: The slag outlet of the heat exchanger is connected to the particle size screening device.

10. A waste heat recovery method, using the waste heat recovery system according to any one of claims 7 to 9, comprising the following contents: S1. Liquid blast furnace slag is introduced into the granulation bin, and the liquid blast furnace slag falls onto the top surface of the granulator. The granulator rotates to throw the liquid blast furnace slag onto the inner wall of the granulation bin; and slag powder is spread onto the inner wall of the granulation bin, so that the liquid blast furnace slag droplets thrown onto the inner wall of the granulation bin fuse with the slag powder to form high-temperature slag particles; S2. introducing room temperature slag particles into the mixing chamber so that the room temperature slag particles are in contact with the high temperature slag particles for heat exchange to form mixed slag particles; S3. The mixed slag particles are passed into the heat storage device for storage; S4. The outlet of the heat storage device storing the mixed slag particles is connected to the slag inlet of the heat exchanger, and the mixed slag particles are introduced into the heat exchanger to exchange heat between the mixed slag particles and the heat exchange medium in the heat exchanger; S5. The mixed slag particles after heat exchange are passed into the particle size screening device, and the small-sized slag particles screened out are used to supplement the slag powder falling from the powder feeder, and the large-sized slag particles screened out are passed into the mixing chamber for heat exchange with the high-temperature slag particles.

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