A waste heat recovery and utilization system for heat treatment furnaces

Abstract

This invention belongs to the field of heat treatment, specifically a waste heat recovery and utilization system for heat treatment furnaces. It addresses the problem that heat is dissipated from the furnace opening, and heat from the workpiece cooling process is also released into the air, resulting in significant heat loss, rapid heating and cooling of the furnace lining, reduced furnace lifespan, and negative impacts on the working environment and comfort. The proposed solution includes a heat treatment furnace containing workpieces. The furnace is connected to a heat exchanger, a first electric valve, and a third electric valve. The heat exchanger is connected to a molten salt pump, which is connected to a molten salt storage tank. During the cooling phase of the heat treatment furnace, heat is stored in the molten salt storage tank. When the workpiece needs heating, the heat from the molten salt storage tank can be used to preheat it, shortening the time required to heat the workpiece to the specified temperature, thereby reducing the power consumption of the furnace's electric heating and achieving energy savings.

Description

Technical Field

[0001] This invention relates to the field of heat treatment technology, and in particular to a waste heat recovery and utilization system for fully recovering, storing and utilizing the waste heat of a heat treatment furnace. Background Technology

[0002] Heat treatment furnaces widely used in industries such as machinery and metallurgy are generally divided into two types: fuel-fired furnaces and resistance furnaces. Resistance furnaces utilize electric current to heat heating elements, which then heat the materials inside the furnace through heat transfer. Their operation can be divided into preheating, heating, holding, and cooling stages, depending on the process. When materials are being processed, the furnace door must be kept open for an extended period after the holding stage to allow cooling to the outlet temperature before unloading. Heat dissipates from the furnace opening, and heat from the workpiece cooling process is also released into the air, resulting in significant heat loss. This also causes rapid heating and cooling of the furnace lining, affecting the lifespan of the resistance furnace. Furthermore, the heat released into the air negatively impacts the working environment and comfort in the workshop. Recovering this waste heat for preheating workpieces or for winter heating in production workshops or offices is of profound significance for improving production efficiency and reducing production costs for enterprises. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies, such as heat loss from the furnace opening and heat dissipation into the air during the workpiece cooling process, resulting in significant heat loss, rapid heating and cooling of the furnace lining, impacting the lifespan of the resistance furnace, and negatively affecting the working environment and comfort in the workshop. Therefore, this invention proposes a waste heat recovery and utilization system for heat treatment furnaces.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A waste heat recovery and utilization system for a heat treatment furnace includes a heat treatment furnace, in which a workpiece is placed. The heat treatment furnace is connected to a heat exchanger, a first electric valve, and a third electric valve. The heat exchanger is connected to a molten salt pump, and the molten salt pump is connected to a molten salt storage tank. The heat exchanger is connected to a second electric valve and an exhaust valve, and the second electric valve and the first electric valve are connected to the same blower.

[0006] Preferably, the heat treatment furnace is provided with a first air outlet and a second air outlet, and the first air outlet is connected to a heat exchanger, while the second air outlet is connected to a first electric valve and a third electric valve.

[0007] Preferably, the molten salt storage tank is equipped with a second temperature sensor and an electric heater.

[0008] Preferably, the molten salt storage tank is connected to a heat exchanger.

[0009] Preferably, a first temperature sensor is provided on the second air vent.

[0010] Compared with the prior art, the beneficial effects of the present invention are:

[0011] This invention mainly consists of a blower, a molten salt storage tank, and a heat exchanger. During the cooling stage of the heat treatment furnace, the blower is activated to send cold air into the furnace to exchange heat with the workpiece. The workpiece is cooled, and the cold air, heated by the workpiece's heat, is then sent to the molten salt storage tank to heat the molten salt liquid inside, thus storing the heat. When the workpiece needs heating, the heat in the molten salt storage tank can be used to preheat it, shortening the time required to heat the workpiece to the specified temperature, thereby reducing the power consumption of the furnace's electric heating and achieving energy savings. The heat in the molten salt storage tank can also be combined with ducted air conditioning systems, heating systems, etc., using blowers to deliver the heat to production workshops or offices for winter heating. Furthermore, off-peak electricity prices at night can be used as an energy source for heating the molten salt, storing heat at night and releasing it during peak daytime electricity consumption, further saving on electricity costs. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the heat storage process of a waste heat recovery and utilization system for a heat treatment furnace proposed in this invention.

[0013] Figure 2 This is a schematic diagram of the heat release process of a waste heat recovery and utilization system for a heat treatment furnace proposed in this invention.

[0014] In the diagram: 1. Heat treatment furnace, 2. Workpiece, 3. First air outlet, 4. Second air outlet, 5. First electric valve, 6. Second electric valve, 7. Exhaust valve, 8. Third electric valve, 9. Blower, 10. Heat exchanger, 11. Molten salt pump, 12. Molten salt storage tank, 13. First temperature sensor, 14. Second temperature sensor, 15. Electric heater. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0016] Reference Figure 1-2 A waste heat recovery and utilization system for a heat treatment furnace includes a heat treatment furnace 1, a workpiece 2 disposed inside the heat treatment furnace 1, a heat exchanger 10, a first electric valve 5 and a third electric valve 8 connected to the heat treatment furnace 1, a molten salt pump 11 connected to the heat exchanger 10 and a molten salt storage tank 12 connected to the molten salt pump 11, a second electric valve 6 and an exhaust valve 7 connected to the heat exchanger 10, and the second electric valve 6 and the first electric valve 5 are connected to the same blower 9.

[0017] In this invention, the heat treatment furnace 1 is provided with a first air outlet 3 and a second air outlet 4, and the first air outlet 3 is connected to a heat exchanger 10, and the second air outlet 4 is connected to a first electric valve 5 and a third electric valve 8.

[0018] In this invention, a second temperature sensor 14 and an electric heater 15 are installed inside the molten salt storage tank 12.

[0019] In this invention, the molten salt storage tank 12 is connected to the heat exchanger 10.

[0020] In this invention, a first temperature sensor 13 is provided on the second air vent 4.

[0021] In this invention, the first step is the heat storage process:

[0022] When workpiece 2 enters the cooling stage after the heating and holding stage is completed, the waste heat recovery and utilization system is started and put into operation to perform the heat storage process:

[0023] 1. Blower 9 is running, molten salt pump 11 is starting, first electric valve 5 and second electric valve 6 are opening, and exhaust valve 7 and third electric valve 8 remain closed;

[0024] 2. The cold air from the outlet of blower 9 enters the heat treatment furnace 1 through the second air inlet 4, where it exchanges heat with the high-temperature gas and high-temperature workpiece 2 inside the furnace. The workpiece 2 is cooled, and the cold air is heated into hot air by the heat inside the furnace.

[0025] 3. The high-temperature hot air after absorbing heat is sent to the molten salt-air heat exchanger 10 through the first air outlet 3, and exchanges heat with the low-temperature molten salt pumped from the molten salt storage tank 12 via the molten salt pump 11 in the heat exchanger 10, transferring the heat to the low-temperature molten salt.

[0026] 4. After the hot air heats the low-temperature molten salt, the temperature decreases, but it still has a relatively high temperature. Therefore, it is sent back to the outlet header of the blower 9 through the second electric valve 6 and mixed with the cold air. The opening of the second electric valve 6 is automatically adjusted by the temperature signal of the first temperature sensor 13, thereby adjusting the temperature of the cold air entering the furnace. This can further improve the thermal efficiency of the entire system and also prevent the workpiece 2 from cooling too quickly, which would affect the product quality.

[0027] 5. After the low-temperature molten salt is heated into high-temperature molten salt by hot air, it returns to the molten salt storage tank 12 for storage, thereby storing the heat in the molten salt storage tank 12, thus completing the heat storage process of the waste heat recovery and utilization system of the heat treatment furnace.

[0028] II. Exothermic process:

[0029] Before workpiece 2 is placed in the furnace for preheating, the waste heat recovery system is started and put into operation to perform the heat release process:

[0030] 1. When blower 9 is running, molten salt pump 11 is started, second electric valve 6 and first electric valve 5 are automatically opened, and exhaust valve 7 remains closed. When heating is needed in winter or there are other heating needs, third electric valve 8 can also be manually opened through the control panel.

[0031] 2. Cold air enters the molten salt-air heat exchanger 10 through the blower 9 and the second electric valve 6, and exchanges heat with the high-temperature molten salt from the molten salt storage tank 12. The cold air absorbs the heat from the high-temperature molten salt and is heated into hot air.

[0032] 3. The high-temperature hot air after absorbing heat enters the heat treatment furnace 1 through the first air inlet 3, and transfers the heat to the workpiece 2 in the furnace to preheat the workpiece 2.

[0033] 4. After the hot air preheats the workpiece 2, the temperature decreases and it is discharged from the second air outlet 4. At this time, the hot air still has a high temperature. Therefore, it is sent back to the outlet header of the blower 9 through the first electric valve 5 to mix with the cold air and increase the air temperature before entering the heat exchanger 10, which can further improve the thermal efficiency of the entire system.

[0034] 5. After the high-temperature molten salt transfers heat to the cold air, it becomes low-temperature molten salt and returns to the molten salt storage tank 12 for storage. This completes the heat release process of the waste heat recovery and utilization system of the heat treatment furnace.

[0035] III. Peak shifting and valley filling process:

[0036] During off-peak electricity pricing periods at night, a peak-shaving and valley-filling process is implemented:

[0037] 1. During off-peak electricity hours at night, the electric heater 15 inside the molten salt storage tank 12 is activated to heat the molten salt inside the tank 12 into high-temperature molten salt, thus achieving heat storage at night within the molten salt tank 12. The second temperature sensor 14 monitors the molten salt temperature, and the electric heater 15 stops operating when the temperature reaches the preset value.

[0038] 2. During peak electricity consumption periods during the day, the system is started and a heat release process is executed. The heat stored in the molten salt storage tank 12 is used to preheat the workpiece 2, thereby reducing the energy consumption of electric heating in the heat treatment furnace 1 and realizing peak shifting and valley filling of electricity.

[0039] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A waste heat recovery and utilization system for a heat treatment furnace, wherein a workpiece (2) is disposed inside the heat treatment furnace (1), characterized in that, The heat treatment furnace (1) is connected to a heat exchanger (10), a first electric valve (5) and a third electric valve (8). The heat exchanger (10) is connected to a molten salt pump (11), and the molten salt pump (11) is connected to a molten salt storage tank (12). The heat exchanger (10) is connected to a second electric valve (6) and an exhaust valve (7), and the second electric valve (6) and the first electric valve (5) are connected to the same blower (9). When performing the thermal storage process: First, the blower (9) runs, the molten salt pump (11) starts, the first electric valve (5) and the second electric valve (6) open, and the exhaust valve (7) and the third electric valve (8) remain closed. The cold air from the outlet of the blower (9) enters the heat treatment furnace (1) through the second air inlet (4). The high-temperature hot air after absorbing heat is sent to the heat exchanger (10) through the first air inlet (3). After the hot air heats the low-temperature molten salt, the temperature decreases. It is sent back to the outlet main pipe of the blower (9) through the second electric valve (6) and mixed with the cold air. The opening of the second electric valve (6) is automatically adjusted by the temperature signal of the first temperature sensor (13), thereby adjusting the temperature of the cold air entering the furnace. After the low-temperature molten salt is heated into high-temperature molten salt by hot air, it is returned to the molten salt storage tank (12) for storage; When performing an exothermic process: When the blower (9) is running, the molten salt pump (11) is started, the second electric valve (6) and the first electric valve (5) are automatically opened, and the exhaust valve (7) remains closed. When heating is needed in winter or there are other heating needs, the third electric valve (8) can also be manually opened through the control panel. Cold air enters the heat exchanger (10) through the blower (9) and the second electric valve (6) to exchange heat with the high-temperature molten salt from the molten salt storage tank (12); After absorbing heat, the high-temperature hot air enters the heat treatment furnace (1) through the first air inlet (3), preheats the workpiece (2), and is discharged from the second air inlet (4). It is then sent back to the outlet main pipe of the blower (9) through the first electric valve (5) and mixed with the cold air. After the high-temperature molten salt transfers heat to the cold air, it returns to the molten salt storage tank (12) for storage.

2. The waste heat recovery and utilization system for a heat treatment furnace according to claim 1, characterized in that, The heat treatment furnace (1) is provided with a first air outlet (3) and a second air outlet (4), and the first air outlet (3) is connected to a heat exchanger (10), and the second air outlet (4) is connected to a first electric valve (5) and a third electric valve (8).

3. The waste heat recovery and utilization system for a heat treatment furnace according to claim 1, characterized in that, The molten salt storage tank (12) is equipped with a second temperature sensor (14) and an electric heater (15).

4. The waste heat recovery and utilization system for a heat treatment furnace according to claim 1, characterized in that, The molten salt storage tank (12) is connected to the heat exchanger (10).

5. A waste heat recovery and utilization system for a heat treatment furnace according to claim 2, characterized in that, The second air vent (4) is equipped with a first temperature sensor (13).

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