Method for utilizing waste heat of grate bed of chain grate machine in pelletizing plant

Abstract

The invention relates to a method for utilizing waste heat of a grate bed of a chain grate machine in a pelletizing plant, which comprises the following steps of: a, mounting a steel belt machine between the grate bed at the lower part of the chain grate machine and a furnace cover of the chain grate machine, arranging a feeding device on one side of the steel belt machine, and arranging a discharging device on the downstream side of the feeding device; b, the to-be-dried iron ore powder is conveyed to a lower-layer conveying steel belt of a steel belt machine through a feeding device, and the to-be-dried iron ore powder is conveyed to a drying area through rotation of the conveying steel belt; c, the iron ore powder in the drying area is dried through heat emitted by a grate bed on the lower portion of the chain grate machine; and d, the dried iron ore powder is conveyed to a discharging device through movement of a lower-layer conveying steel belt of the steel belt machine, and the iron ore powder is separated from the lower-layer conveying steel belt under the action of the discharging device. According to the method, the moisture of the iron ore powder on the steel belt is dried to 6%-8% by utilizing the waste heat of the grate bed, so that the waste heat of the grate bed is effectively utilized, heat energy required for drying the iron ore powder in the prior art is saved, the high-temperature environment around the grate bed is also improved, and the economic benefit is remarkable.

Description

Technical Field

[0001] The present invention relates to the technical field of energy conservation and emission reduction in pellet production, in particular to the drying of iron ore powder and the utilization of waste heat from a chain grate, and specifically to a method for utilizing waste heat from a grate bed of a pellet plant chain grate. Background Art

[0002] The chain grate-rotary kiln process is the dominant process for oxidation pellet production in my country. It primarily consists of a chain grate, a rotary kiln, and an annular cooler. The chain grate is primarily used for drying and preheating the pellets. The grate bed of the chain grate circulates in an alternating temperature field. The upper half of the grate bed is located within the upper furnace hood, while the lower half is fully exposed to the air for natural cooling.

[0003] During normal production, the grate bed exiting the preheating section of the chain grate machine reaches a temperature of approximately 500°C, and the heat removed by the grate bed accounts for approximately 23.89% of the total heat generated. Natural cooling of the grate bed from approximately 500°C in the air not only causes heat loss but also contributes to the elevated ambient temperature, posing a potential risk of heat damage.

[0004] To achieve a high pelletizing rate, pelletizing plants typically require iron ore fines to have a -200 mesh content greater than 85%. However, iron ore fines often fail to meet this requirement, necessitating damp grinding. To achieve optimal damp grinding efficiency, the moisture content of the iron ore fines must be controlled between 6% and 8%. However, the moisture content of iron ore fines entering the plant is typically around 10%, necessitating drying of the fines, which consumes a significant amount of heat. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides a method for utilizing waste heat of a grate bed of a pelletizing plant grate, which not only improves the waste heat utilization rate of the grate bed of the grate, but also realizes the drying of iron ore powder.

[0006] The present invention is achieved through the following technical solution, which provides a method for utilizing waste heat from a grate bed of a pelletizing plant grate, comprising the following steps: a. A steel belt conveyor is installed between the lower grate bed of the chain grate machine and the chain grate machine furnace cover. The length direction of the conveyor steel belt of the steel belt conveyor is consistent with the length direction of the lower grate bed of the chain grate machine. A feeding device adapted to the feeding end of the lower conveyor steel belt is provided on the side of the steel belt conveyor. A discharging device is provided on the downstream side of the feeding device. A drying area is formed between the feeding device and the discharging device. b. Use the feeding device to convey the iron ore powder to be dried to the lower conveyor belt of the steel belt conveyor, and through the rotation of the conveyor belt, the iron ore powder to be dried is conveyed to the drying area; c. Utilize the heat emitted by the lower grate bed of the chain grate to heat the lower conveyor belt of the steel belt conveyor, thereby drying the iron ore powder in the drying area; d. The dried iron ore powder is transported to the discharging device by utilizing the movement of the lower conveying steel belt of the steel belt conveyor. The iron ore powder is separated from the lower conveying steel belt under the action of the discharging device.

[0007] The method of this scheme utilizes the heat carried by the chain grate to dry the iron ore powder on the lower conveyor steel belt, which not only reduces the water content of the iron ore powder, but also realizes the utilization of the waste heat of the chain grate. It has a simple structure, does not require the structure of the chain grate to be changed, and has low operating costs.

[0008] As an optimization, the lower conveyor belt of the steel belt conveyor is located directly above the lower grate bed of the chain grate, and the distance between the lower conveyor belt and the lower grate bed of the chain grate does not exceed 5 cm. This optimization solution improves the utilization rate of heat dissipated by the chain grate and also improves the heating efficiency of the iron ore fines.

[0009] As an optimization, the feeding device includes a first belt conveyor and a pendulum distributor positioned between the upper and lower conveyor belts of the steel belt conveyor. The discharge end of the first belt conveyor is adapted to the feed end of the pendulum distributor, which in turn is adapted to the feed position of the lower conveyor belt. This optimized feeding device has a simple structure and is easy to set up. The first belt conveyor transports the iron ore powder to be dried to the pendulum distributor, which then spreads the iron ore powder onto the lower conveyor belt. This improves the consistency of the iron ore powder's thickness and contributes to improved drying efficiency.

[0010] As an optimization, the discharging device includes a second belt conveyor and a fixed baffle, wherein the baffle is located between the upper conveying steel belt of the steel belt conveyor and the lower conveying steel belt, the distance between the lower edge of the baffle and the lower conveying steel belt is less than the particle size of the iron ore powder, and the angle between the length direction of the baffle and the moving direction of the lower conveying steel belt is less than 90 degrees; along the moving direction of the lower conveying steel belt, the front end of the baffle extends out of the steel belt conveyor, and the place where the baffle extends out of the steel belt conveyor forms a discharging position of the lower conveying steel belt, and the feed end of the second belt conveyor is adapted to the discharging position. The discharging device of this optimization scheme has a simple structure. When the lower conveying steel belt conveys the dried iron ore powder forward, the baffle is used to block the iron ore powder, and the baffle is used to guide the iron ore powder to the discharging position. The iron ore powder flows out of the lower conveying steel belt from the discharging position and finally falls to the feed end of the second belt conveyor, and the dried iron ore powder is output by the second belt conveyor.

[0011] As an optimization, a fixed sliding plate is also included. The upper end of the sliding plate extends below the discharge position, and the lower end of the sliding plate extends downwardly and tilts upward to the feed end of the second belt conveyor. This optimization solution installs a sliding plate between the discharge position of the lower conveyor steel belt and the second belt conveyor. Iron ore powder falling from the discharge position slides along the sliding plate to the second belt conveyor, reducing splashing of the iron ore powder when it falls.

[0012] As an optimization, a spill prevention plate is fixed to the side of the baffle plate facing the iron ore fines. The distance between the lower edge of the spill prevention plate and the underlying conveyor belt is less than the particle size of the iron ore fines. The length of the spill prevention plate aligns with the movement direction of the underlying conveyor belt, and the spill prevention plate is located on the side of the iron ore fines away from the discharge point. This optimization solution prevents the iron ore fines from overflowing from the side away from the discharge point, further ensuring that the iron ore fines move along the baffle plate toward the discharge point.

[0013] As an optimization, the conveyor belt of the steel belt conveyor rotates in the same direction as the grate bed of the chain grate. This optimization solution sets the conveyor belt's rotation direction to be consistent with the grate bed of the chain grate. This allows the high-temperature section of the grate bed corresponding to the drying zone to pass through the area corresponding to the iron ore fines with higher moisture content first, thereby improving drying efficiency.

[0014] As an optimization, in step c, when the temperature of the grate bed exiting the grate furnace hood is greater than or equal to 500°C, the lower conveyor belt moves continuously, drying the iron ore powder while conveying it to the discharge device. When the temperature of the grate bed exiting the grate furnace hood is greater than 450°C but less than 500°C, the lower conveyor belt moves intermittently. When the drying area is filled with iron ore powder, the lower conveyor belt stops moving. After drying for 20 to 25 seconds, the lower conveyor belt moves to convey the dried iron ore powder to the discharge device. At the same time, the drying area is filled with material to be dried. This optimization scheme controls the movement state of the steel belt conveyor according to the grate bed temperature. When the grate bed temperature is high, the steel belt conveyor's conveyor belt operates continuously, drying the iron ore powder while conveying it forward, improving the drying efficiency. When the temperature is low, the steel belt conveyor starts intermittently, leaving sufficient time for drying and ensuring the drying effect.

[0015] The beneficial effects of the present invention are as follows: utilizing the characteristics that the space between the lower grate bed of the chain grate machine and the bottom of the chain grate machine furnace cover is relatively large and the temperature of the grate bed coming out of the chain grate machine head is relatively high, a steel belt machine and corresponding feeding device and discharging device are installed between the lower grate bed of the chain grate machine and the bottom of the chain grate machine furnace cover, and the waste heat of the grate bed is utilized to dry the moisture of the iron ore powder on the steel belt to 6% to 8%. The waste heat of the grate bed is effectively utilized, saving the heat energy required for drying the iron ore powder using the existing process, and also improving the high-temperature environment around the grate bed, with significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a top view schematic diagram of the present invention; As shown in the figure: 1. Grate bed, 2. Support roller, 3. Steel belt conveyor, 4. Second belt conveyor, 5. Slide plate, 6. Swing feeder, 7. First belt conveyor, 8. Iron ore powder, 9. Baffle plate, 10. Conveyor steel belt. DETAILED DESCRIPTION

[0017] In order to clearly illustrate the technical features of this solution, this solution is described below through specific implementation methods.

[0018] The purpose of this embodiment is to achieve comprehensive utilization of the heat carried by the grate bed of the chain grate in the pelletizing plant. By utilizing the structural characteristics of the chain grate itself and the requirement for drying the iron ore powder in the pelletizing plant, a method for utilizing the waste heat of the grate bed of the chain grate in the pelletizing plant is provided, which has the characteristics of reasonable design, energy saving, and cost reduction.

[0019] The belt conveyor, steel belt conveyor, swing type distributor and chain grate conveyor involved in this embodiment are all existing equipment, and their specific structures are not described in detail. Figure 1 As shown, the steel belt conveyor 3 includes a circumferentially closed conveyor belt 10 and four rollers located inside the conveyor belt 10. The four rollers are arranged in a rectangular shape and are driven by a motor to rotate the rollers, which in turn drive the conveyor belt. The upper and lower conveyor belts are arranged horizontally, with sufficient space between them to accommodate the discharge end of the first belt conveyor and the pendulum distributor. The steel belt conveyor's tail is movable to facilitate tensioning of the steel belt as it lengthens.

[0020] The chain grate comprises a circumferentially closed annular grate bed 1 and a chain grate furnace cover arranged on the outside of the upper grate bed. The upper grate bed and the lower grate bed are both arranged horizontally and supported by support rollers 2 respectively. The lower conveyor steel belt and the lower grate bed both move from back to front.

[0021] The present embodiment provides a method for utilizing waste heat from a grate bed of a pelletizing plant chain grate, comprising the following steps: a. Install a steel belt conveyor between the lower grate bed of the chain grate machine and the chain grate machine furnace cover. The length direction of the conveyor steel belt of the steel belt conveyor is consistent with the length direction of the lower grate bed of the chain grate machine. The lower conveyor steel belt of the steel belt conveyor is located directly above the lower grate bed of the chain grate machine, and the distance between the lower conveyor steel belt and the lower grate bed of the chain grate machine does not exceed 5 cm. Reduce the distance between the lower conveyor steel belt and the lower grate bed of the chain grate machine to improve the heat utilization effect.

[0022] A feeding device adapted to the feeding end of the lower conveying steel belt is arranged on the side of the steel belt conveyor, and a discharging device is arranged on the downstream side of the feeding device, and a drying area is formed between the feeding device and the discharging device.

[0023] b. Use the feeding device to transport the iron ore powder to be dried to the lower conveyor belt of the steel belt conveyor. Through the rotation of the conveyor belt, the iron ore powder to be dried is transported to the drying area.

[0024] c. The rotation direction of the conveyor belt of the steel belt conveyor is consistent with the rotation direction of the grate bed of the chain grate machine. The heat emitted by the lower grate bed of the chain grate machine is used to heat the lower conveyor belt of the steel belt conveyor, thereby drying the iron ore powder in the drying area.

[0025] When the temperature of the grate bed coming out of the chain grate furnace cover is greater than or equal to 500℃, the lower conveyor steel belt continues to move. While drying the iron ore powder, the lower conveyor steel belt transports the iron ore powder to the discharging device. When the temperature of the grate bed coming out of the chain grate furnace cover is greater than 450℃ and less than 500℃, the lower conveyor steel belt moves intermittently. When the drying area is full of iron ore powder, the lower conveyor steel belt stops moving. After drying for 20s~25s, the lower conveyor steel belt moves forward to transport the dried iron ore powder to the discharging device. At the same time, the drying area is full of materials to be dried. The working state of the steel belt conveyor is controlled again according to the grate bed temperature, and the operation is repeated in this way.

[0026] d. The dried iron ore powder is transported to the discharging device by utilizing the movement of the lower conveying steel belt of the steel belt conveyor. The iron ore powder is separated from the lower conveying steel belt under the action of the discharging device.

[0027] The feeding device of this embodiment includes a first belt conveyor 7, and a swing-type distributor 6 located between the upper conveyor steel belt and the lower conveyor steel belt of the steel belt machine. The discharge end of the first belt conveyor is adapted to the feed end of the swing-type distributor 6, and the discharge end of the swing-type distributor is adapted to the feed position of the lower conveyor steel belt. The iron ore powder 8 flowing out from the discharge end of the first belt conveyor falls to the feed end of the swing-type distributor, and the iron ore powder 8 is laid on the lower conveyor steel belt by using the swing-type distributor. The edge of the material belt formed by the iron ore powder is 10 cm to 30 cm away from the edge of the lower conveyor steel belt, which increases the area of ​​the iron ore powder and improves the consistency of the thickness of the iron ore powder, thereby helping to improve the drying efficiency.

[0028] like Figure 2 As shown in , the discharging device includes a second belt conveyor 4 and a fixed baffle plate 9, which is located between the upper conveyor steel belt of the steel belt machine and the lower conveyor steel belt. The distance between the lower edge of the baffle plate and the lower conveyor steel belt is less than the particle size of the iron ore powder to prevent the iron ore powder from passing between the baffle plate and the lower conveyor steel belt. The angle between the length direction of the baffle plate and the moving direction of the lower conveyor steel belt is less than 90 degrees. Along the moving direction of the lower conveyor steel belt, the front end of the baffle plate extends out of the steel belt machine, and the place where the baffle plate extends out of the steel belt machine forms a discharging position of the lower conveyor steel belt. The feed end of the second belt conveyor is adapted to the discharging position. The iron ore powder flowing out of the discharging position of the lower conveyor steel belt is transported to the lubrication and grinding process via the second belt conveyor.

[0029] This embodiment also includes a fixed sliding plate 5, which is tilted, with its upper end extending below the discharge position and its lower end extending downwardly and tilted above the feed end of the second belt conveyor. The iron ore powder flowing out of the discharge position slides along the sliding plate onto the second belt conveyor, reducing the splashing of the iron ore powder.

[0030] An anti-overflow plate is fixedly provided on the side of the baffle plate facing the iron ore powder. The distance between the lower edge of the anti-overflow plate and the lower conveyor steel belt is smaller than the particle size of the iron ore powder. The length direction of the anti-overflow plate is consistent with the moving direction of the lower conveyor steel belt, and the anti-overflow plate is located on the side of the iron ore powder away from the discharge position.

[0031] The waste heat utilization method of this embodiment uses the waste heat from the grate to dry the moisture content of mixed iron ore fines on the steel belt to 6% to 8%. This effectively utilizes the waste heat from the grate, saving the heat energy required for drying the iron ore fines using existing processes and improving the high-temperature environment around the grate, resulting in significant economic benefits. After application in a pelletizing plant, this method can dry the moisture content of the iron ore fines from 10% to 6% to 8%, reducing heat energy consumption by 1.8 million to 2.4 million yuan per year for a 1.2 million ton pelletizing plant.

[0032] Of course, the above description is not limited to the above examples. Technical features not described in the present invention can be achieved by or by adopting existing technologies, which will not be described here. The above embodiments and drawings are only used to illustrate the technical solutions of the present invention and are not limitations of the present invention. The present invention is described in detail with reference to the preferred implementation methods. Ordinary technicians in this field should understand that changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention do not depart from the purpose of the present invention and should also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for utilizing waste heat from a grate bed of a pelletizing plant, characterized in that: The following steps are involved: a. A steel belt conveyor is installed between the lower grate bed of the chain grate machine and the chain grate machine furnace cover. The length direction of the conveyor steel belt of the steel belt conveyor is consistent with the length direction of the lower grate bed of the chain grate machine. A feeding device adapted to the feeding end of the lower conveyor steel belt is provided on the side of the steel belt conveyor. A discharging device is provided on the downstream side of the feeding device. A drying area is formed between the feeding device and the discharging device. b. Use the feeding device to convey the iron ore powder to be dried to the lower conveyor belt of the steel belt conveyor, and through the rotation of the conveyor belt, the iron ore powder to be dried is conveyed to the drying area; c. Utilize the heat emitted by the lower grate bed of the chain grate to heat the lower conveyor belt of the steel belt conveyor, thereby drying the iron ore powder in the drying area; d. The dried iron ore powder is transported to the discharging device by utilizing the movement of the lower conveying steel belt of the steel belt conveyor. The iron ore powder is separated from the lower conveying steel belt under the action of the discharging device.

2. The method for utilizing waste heat from a grate bed of a pelletizing plant according to claim 1, wherein: The lower conveying steel belt of the steel belt machine is located directly above the lower grate bed of the chain grate machine, and the distance between the lower conveying steel belt and the lower grate bed of the chain grate machine does not exceed 5 cm.

3. The method for utilizing waste heat from a grate bed of a pelletizing plant according to claim 1, wherein: The feeding device includes a first belt conveyor and a swing-type distributor located between the upper conveyor steel belt and the lower conveyor steel belt of the steel belt machine. The discharge end of the first belt conveyor is adapted to the feed end of the swing-type distributor, and the discharge end of the swing-type distributor is adapted to the feed position of the lower conveyor steel belt.

4. The method for utilizing waste heat from a grate bed of a pelletizing plant according to claim 1, wherein: The discharging device includes a second belt conveyor and a fixed baffle plate, wherein the baffle plate is located between the upper conveying steel belt and the lower conveying steel belt of the steel belt conveyor, the distance between the lower edge of the baffle plate and the lower conveying steel belt is less than the particle size of the iron ore powder, and the angle between the length direction of the baffle plate and the moving direction of the lower conveying steel belt is less than 90 degrees; Along the moving direction of the lower conveyor steel belt, the front end of the baffle plate extends out of the steel belt machine, and the place where the baffle plate extends out of the steel belt machine forms a discharge position for the lower conveyor steel belt, and the feed end of the second belt conveyor is adapted to the discharge position.

5. The method for utilizing waste heat from a grate bed of a pelletizing plant according to claim 4, wherein: It also includes a fixed sliding plate, the upper end of the sliding plate extends below the discharge position, and the lower end of the sliding plate extends downwardly and tilted to above the feed end of the second belt conveyor.

6. The method for utilizing waste heat from a grate bed of a pelletizing plant according to claim 4, wherein: An anti-overflow plate is fixedly provided on the side of the baffle plate facing the iron ore powder. The distance between the lower edge of the anti-overflow plate and the lower conveyor steel belt is smaller than the particle size of the iron ore powder. The length direction of the anti-overflow plate is consistent with the moving direction of the lower conveyor steel belt, and the anti-overflow plate is located on the side of the iron ore powder away from the discharge position.

7. The method for utilizing waste heat from a grate bed of a pelletizing plant according to claim 1, wherein: The rotation direction of the conveyor belt of the steel belt conveyor is consistent with the rotation direction of the grate bed of the chain grate machine.

8. The method for utilizing waste heat from a grate bed of a pelletizing plant according to claim 7, wherein: In step c, when the temperature of the grate bed coming out of the chain grate furnace cover is greater than or equal to 500°C, the lower conveyor steel belt continues to move. While drying the iron ore powder, the lower conveyor steel belt transports the iron ore powder to the discharging device. When the temperature of the grate bed coming out of the chain grate furnace cover is greater than 450°C and less than 500°C, the lower conveyor steel belt moves intermittently. When the drying area is full of iron ore powder, the lower conveyor steel belt stops moving. After drying for 20s to 25s, the lower conveyor steel belt moves to transport the dried iron ore powder to the discharging device. At the same time, the drying area is full of material to be dried.

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