Flue gas waste heat utilization device of drying box and using method of flue gas waste heat utilization device
By designing the device of the flue gas trap and heat exchanger, the smoke gas of the drying box is captured and the remaining heat is used for heating water, the problem of failure to effectively utilize the waste heat of the flue gas is achieved, and the cascade utilization and environmental protection of energy are achieved Target.
Patent Information
- Application Number
- CN202411695146.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-25
- Publication Date
- 2025-02-07
AI Technical Summary
During operation, the drying box emits a large amount of heat-rich flue gas, resulting in energy waste and environmental thermal pollution. It is difficult for the prior art to effectively capture and utilize these waste heat.
Design a flue gas waste heat utilization device, including a flue gas trap, heat exchanger and air induced fan, to capture high-temperature flue gas through negative pressure, and heat cold water to above 50°C by using a heat exchanger to achieve thermal energy regeneration use.
Effectively recover waste heat from flue gas in the drying box, reduce dependence on external energy, improve energy utilization efficiency, reduce production costs, and achieve energy conservation and emission reduction, and promote the industry's green and low-carbon transformation.
Smart Images
Figure CN119394082A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of energy conservation and emission reduction, and more specifically to a fume waste heat utilization device of a drying box and a use method thereof. Background Art
[0002] Faced with the increasingly severe challenges of energy conservation and emission reduction and the dual pressure of production cost control, we need to actively explore new ways to efficiently utilize resources. At present, the drying box, as a key link in the production line, will discharge a large amount of flue gas rich in heat energy during its operation. If it is discharged directly, it will not only waste precious energy resources, but also may cause thermal pollution to the environment.
[0003] In view of this, the waste heat in the flue gas can be effectively captured and converted into reusable heat energy to achieve cascade utilization of energy and circular economy. This not only reduces the energy consumption and production costs of enterprises, but also achieves energy conservation and emission reduction, which is of great significance to promoting the green and low-carbon transformation of the industry. Summary of the invention
[0004] In view of the deficiencies in the prior art, the present invention provides a device and method for utilizing waste heat from flue gas in a drying box, which can effectively capture the high-temperature flue gas generated in the drying box and use the waste heat to heat water.
[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a device for utilizing waste heat from flue gas in a drying box, comprising a flue gas collector arranged at the outlet of the drying box, the end of the flue gas collector is connected to a heat exchanger, the end of the heat exchanger is connected to an induced draft fan, the end of the induced draft fan is connected to an external exhaust port, the heat exchanger comprises a heat exchange chamber and a hot water exchange pipe passing through the heat exchange chamber, the beginning and end of the hot water exchange pipe are respectively connected to an external cold water tank and an insulating water tank, the flue gas collector comprises a collection chamber located in the drying box, a plurality of air suction ports are arranged in the collection chamber, the plurality of air suction ports are all connected to a main air intake port, and the main air intake port is connected to the heat exchange chamber.
[0006] The present invention further provides a method for using a flue gas waste heat utilization device of a drying box, comprising the following steps:
[0007] A. Pre-preparation: Check the connection and sealing status between the components. When the sealing status is confirmed, start the induced draft fan to check whether the negative pressure in the collection chamber is normal; start the water pump to check whether the water temperature is normal;
[0008] B. Start-up of the device: The induced draft fan generates negative pressure when it is started, and the smoke collector captures the high-temperature smoke generated by the drying box, and guides the smoke into the heat exchanger. The water pump starts, and the water in the cold water tank exchanges heat with the high-temperature smoke through the flat plate of the heat exchange pipe. The obtained hot water is passed into the insulation water tank for storage. The cold water continuously passes through the heat exchanger to continuously generate hot water. The hot water in the insulation water tank can be connected to an external pipeline for washing the plate and strip after drying, etc.
[0009] C. System control: dynamically adjust the power of the induced draft fan to keep the negative pressure in the collection chamber within -5 to 0Pa; dynamically adjust the water temperature to control the water temperature between 50-55℃; the dynamic water temperature control includes adjusting according to the outlet water temperature or the flue gas outlet temperature or both temperatures at the same time;
[0010] D. Safety protection: Pressure detection and temperature detection are carried out in real time. When abnormal conditions such as overpressure and overtemperature occur, the power of the water pump and fan is increased in time to quickly reduce the internal pressure and temperature of the system. At the same time, the alarm information is fed back and the operation of the front-end drying box is checked in time;
[0011] E. Maintenance of the device: After the operation is completed, the condensed water and pollutants in the flue gas remaining on the surface of the flat plate are scraped from top to bottom by the lifting scraper, and then scraped into the concave cavity of the closing plate. Then the closing plate is removed, the residue in the concave cavity is cleaned, and finally the closing plate is replaced.
[0012] In summary, the present invention has the following beneficial effects:
[0013] The present invention effectively recovers waste heat from the fume of the drying box, and can heat cold water (normal temperature water) to above 50°C. The hot water can be used for other needs of the factory, thereby reducing dependence on external energy, realizing cascade utilization of energy, and improving energy utilization efficiency.
[0014] In the upper and lower sealing plates of the present invention, the lower sealing plate is a rigid wear-resistant sealing plate, which has a certain lifting effect on the plate belt, and the upper sealing plate is a flexible sealing plate to adapt to the disturbance during the movement of the plate belt and play a sealing role to reduce the air leakage rate.
[0015] The suction port of the present invention is arranged at the upper and lower parts of the collection chamber, and a plurality of suction ports are arranged according to the width of the drying box. To ensure uniform suction, the diameter of the suction port is 25-50 mm, and the spacing is 300-500 mm / port. At the same time, generally, the closer to the main air intake port, the stronger the suction force will be. To improve the problems of unevenness and loss of flow, in order to make the air volume of the suction port uniform, the suction port is increased by 2-5% of the openings on the side surface from near to far according to the distance from the main air intake port, so as to achieve uniform suction volume at each position by increasing the suction area.
[0016] The present invention also adjusts the operating power of the induced draft fan according to the negative pressure measured at the outlet of the drying box. The negative pressure is controlled within -5 to 0 Pa. If the pressure is lower than this, the operating power of the fan is reduced, and if the pressure is higher than this, the operating power is increased to achieve 100% capture of the flue gas. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a simplified diagram of the overall process of this device.
[0018] Figure 2 This is a simplified diagram of the drying box and collection chamber structure.
[0019] Figure 3 It is a schematic diagram of the structure of the main air intake port, the air exhaust port and the side air exhaust port.
[0020] Figure 4 Schematic diagram of the structure of the flat plate inside the heat exchange chamber.
[0021] Figure 5 Schematic diagram of the structure of the lifting scraper and closing plate.
[0022] Figure numerals: 01, drying box; 02, plate belt; 1, smoke collector; 101, collection chamber; 102, exhaust port; 1021, side exhaust port; 103, main air intake port; 2, heat exchanger; 201, heat exchange chamber; 202, hot water exchange pipe; 3, induced draft fan; 41, upper sealing plate; 42, lower sealing plate; 5, flat plate; 6, opening; 601, closing plate; 602, concave cavity; 7, lifting scraper; 701, crossbeam; 8, heat exchanger temperature detection device; 9, negative pressure detection device; 10, cold water tank; 11, thermal insulation water tank. DETAILED DESCRIPTION
[0023] The present invention is further described in detail below in conjunction with the accompanying drawings.
[0024] This embodiment discloses a device for utilizing waste heat from flue gas in a drying box. Figure 1-5As shown, it includes a smoke collector 1 arranged at the outlet of the drying box 01, the end of the smoke collector 1 is connected to the heat exchanger 2, the end of the heat exchanger 2 is connected to the induced draft fan 3, the end of the induced draft fan 3 is connected to the external exhaust port, the heat exchanger 2 includes a heat exchange chamber 201 and a hot water exchange pipe 202 passing through the heat exchange chamber 201, the beginning and end of the hot water exchange pipe 202 are respectively connected to the external cold water tank 10 and the insulation water tank 11, the smoke collector 1 includes a collection chamber 101 located in the drying box 01, and a plurality of air suction ports 102 are arranged in the collection chamber 101, and the plurality of air suction ports 102 are all connected to the main air suction port 103, and the main air suction port 103 is connected to the heat exchange chamber 201. Through the above structure, during the operation of the device, the temperature of the smoke at the outlet of the drying box 01 is about 120°C, and the smoke is effectively collected under the negative pressure generated by the induced draft fan 3. Subsequently, the flue gases will pass through the heat exchanger 2 for heat exchange. In this process, the heat exchanger plays a key role. It uses the heat of the flue gases to heat cold water (the cold water in this embodiment is relative to the heated hot water, which can be understood as water at room temperature), thereby generating hot water above 50°C for other factory needs. After the flue gases pass through the hot water exchanger, their temperature has been reduced to 60-70°C, and they will be discharged outdoors through the chimney through the action of the induced draft fan, which can ensure the safety of the environment. At the same time, the induced draft fan is arranged at the rear end of the heat exchanger, which can reduce the airflow disturbance at the exhaust port, basically relying on natural capture by negative pressure, and secondly, the temperature is reduced through the heat exchanger 2, which is not easy to cause damage to the induced draft fan.
[0025] To give a further example, the device can be applied to a degreased plate drying box. The drying box is used to dry degreased cold-rolled plates. The hot water generated by the waste heat utilization device can be used to rinse the degreased cold-rolled plates, reducing the extra energy consumption. The operation process of the entire system embodies the concept of high efficiency and environmental protection. First, the flue gas is collected through the negative pressure of the induced draft fan to avoid the diffusion of the flue gas, thereby reducing the risk of environmental pollution. Secondly, the heat in the flue gas is recovered by a hot water exchanger, which realizes the reuse of thermal energy and reduces energy consumption. Finally, the heated hot water is used to rinse the processed strip 02, which not only ensures the cleanliness of the plate, but also reduces the energy consumption during the rinsing process.
[0026] Furthermore, considering the fluid dynamics principle of flue gas, the layout and cross-sectional design of the air extraction port are optimized to achieve precise control and efficient collection of flue gas emission, so as to cope with the problem of complex air flow field dispersion generated during the drying process. A number of air extraction ports 102 are arranged up and down, and the air extraction ports 102 are arranged along the width direction of the collection chamber 101, the air extraction port spacing is set to 300-500mm, the diameter of the air extraction port 102 is set to 25-50mm, and the air extraction port 102 is provided with a side air extraction port 1021 on the side wall, and the side air extraction port 1021 increases the openings by 2-5% from near to far according to the distance from the main air intake port 103. Because generally, the closer to the main air intake port, the stronger the suction force will be. In order to improve the problems of unevenness and loss of flow, the air extraction port 102 increases the openings by 2-5% from near to far on the side surface according to the distance from the main air intake port, and the uniform air extraction volume at each position is achieved by increasing the air suction area of the side air extraction port 1021.
[0027] Furthermore, a sealing door is provided at the outlet of the collection chamber 101; the sealing door comprises an upper sealing plate 41 and a lower sealing plate 42 which are abutted against each other, the upper sealing plate 41 is made of a flexible material, and the lower sealing plate 42 is made of a rigid material. The rigid wear-resistant sealing plate on the lower side has a certain lifting effect on the plate belt 02, and the flexible sealing plate on the upper side can adapt to the disturbance during the movement of the plate belt 02 and play a sealing role to reduce the air leakage rate.
[0028] Furthermore, the temperature of the flue gas at 120°C after drying is lower than that of the traditional heat exchange device. Therefore, although it can heat a certain amount of hot water to above 50°C after being captured and used for heat exchange treatment, the heat utilization efficiency is relatively low. Therefore, in this embodiment, the portion of the hot water pipe 202 passing through the heat exchange chamber 201 is set as a flat plate 5 with a flat structure, and the flat plates 5 are arranged in an array in the heat exchange chamber 201 at intervals. The flue gas passes through the intervals between the flat plates 5, and the hot water pipe 202 enters from the side, and then bends and forms a vertical flat plate 5. The flat plate is made of a metal material with good thermal conductivity, such as copper. When the water flows through the flat plate 5, according to the principle of thermodynamics, heat will be transferred from the high temperature side to the low temperature side, thereby increasing the temperature of the water flow. The flat structure also makes the contact area between water and flue gas relatively large, and the heat exchange efficiency is good. At the same time, fins can be added to the heat exchange water pipe to further improve the heat transfer efficiency; then the flat plate 5 is bent and leaves the heat exchange cavity from the side, and the hot water after heating is discharged smoothly and stored in the heat preservation water tank 11 for use. If necessary, if the temperature in the heat preservation water tank 11 drops significantly, the heat preservation water tank 11 can be circulated back to the cold water tank 10 for reheating.
[0029] Furthermore, under long-term working conditions, a small amount of pollutants such as SO2 and NOx in the low-temperature flue gas will cause corrosion on the heat exchange surface, and the water vapor in the low-temperature flue gas is prone to condensation on the outer surface of the flat plate 5, and the condensed water will absorb the pollutants in the flue gas and form acid corrosion. Therefore, it is necessary to regularly treat the condensed water to prevent corrosion. To this end, the bottom of the heat exchange chamber 201 of this embodiment is provided with an opening 6 corresponding to the gap between a number of flat plates 5, and the bottom of the heat exchange chamber 201 is provided with a detachable closing plate 601 with a sealing strip on the side, and a concave cavity 602 is provided in the closing plate 601. The concave cavity 602 at the bottom is used to accommodate the condensed water left by gravity, and a water outlet with a valve can also be provided at the bottom of the concave cavity 602, and the condensed water can be discharged regularly. When it is completely treated, it is only necessary to remove the closing plate 601, and then the acid-corrosive condensed water in the concave cavity 602 can be thoroughly poured out.
[0030] Furthermore, after the device is used, some pollutants and condensed water will still adhere to the surface of the flat plate 5. In this embodiment, a lifting scraper 7 is arranged in the heat exchange chamber 201. The lifting scraper 7 is arranged in the gap between the flat plates 5. The lifting scraper 7 is arranged in an inverted V-shaped structure and the edge is arranged against the flat plate 5. Figure 4-5 As shown, the lifting scraper can be driven by a screw rod for lifting, and the lifting frame has a beam 701 corresponding to the gap between the flat plates 5. The lifting scraper 7 is installed on the beam 701. By descending, the pollutants and condensed water on the surface can be completely scraped into the cavity, and then the closing plate 601 can be removed to complete the cleaning. There is no need to manually clean the flat plates with very small gaps, which is more convenient.
[0031] Furthermore, the present embodiment also includes a control device, which includes a heat exchanger temperature detection device 8, a negative pressure detection device 9, a draft fan frequency conversion device, and a water pump control device. The heat exchanger temperature detection device 8 is arranged at the water outlet of the hot water exchange pipe 202 or at the air outlet of the heat exchange chamber 201 or at both places. The negative pressure detection device 9 is arranged in the collection chamber 101, the draft fan frequency conversion device is arranged on the draft fan 3, and the water pump control device is arranged on the water pump between the cold water tank and the hot water exchange pipe.
[0032] On the basis of the above embodiment, a method for using the flue gas waste heat utilization device of a drying box is further provided, comprising the following steps:
[0033] A. Preliminary preparation: Check the connection and sealing status between the components. When the sealing status is confirmed, start the induced draft fan to check whether the negative pressure in the collection chamber is normal; start the water pump to check whether the water temperature is normal; this step ensures the reliable use of the device and will not cause leakage and other problems.
[0034] B. Start-up of the device: The induced draft fan generates negative pressure when it is started, and the smoke collector captures the high-temperature smoke generated by the drying box, and guides the smoke into the heat exchanger. The water pump starts, and the water in the cold water tank exchanges heat with the high-temperature smoke through the flat plate of the heat exchange pipe. The obtained hot water is passed into the insulation water tank for storage. The cold water continuously passes through the heat exchanger to continuously generate hot water. The hot water in the insulation water tank can be connected to an external pipeline for washing the plate and strip after drying, etc.
[0035] C. System control: dynamically adjust the power of the induced draft fan to keep the negative pressure in the collection chamber within -5 to 0Pa; dynamically adjust the water temperature to control the water temperature between 50-55℃; wherein, the dynamic adjustment of the water temperature includes adjustment according to the outlet water temperature or adjustment according to the flue gas outlet temperature or adjustment according to the temperatures of both; specifically, the negative pressure is controlled within -5 to 0Pa. If the pressure is lower than this, the operating power of the induced draft fan is reduced, and if the pressure is higher than this, the operating power is increased to achieve 100% capture of flue gas; temperature control relies on two methods. First, it is adjusted according to the outlet water temperature. The outlet water temperature is controlled at 50-55℃. When it is higher than this temperature, the water intake is increased, and when it is lower than this temperature, the water intake is reduced; second, it is adjusted according to the flue gas outlet temperature. The flue gas outlet temperature is controlled at 55-60℃. When it is higher than this temperature, the water intake is increased. When it is lower than this temperature, if the outlet water temperature is normal, it is maintained unchanged. If the outlet water temperature is low, the water intake is reduced, and if the outlet water temperature is high, the water intake is increased. Because the capture of disordered flue gas is unstable and volatile, and the running speed of the strip may fluctuate intermittently during drying, the coordinated control of temperature and pressure in this device plays a vital role. Dynamically regulating negative pressure ensures efficient collection of flue gas, and coordinating with water temperature control, these deviations are corrected by adjusting the power of the induced draft fan and water pump to ensure efficient collection and treatment of flue gas. This process not only reduces energy waste, but also significantly improves the operating efficiency and stability of the system.
[0036] D. Safety protection: refer to Figure 1 In the figure, T represents the temperature detection device, and P represents the pressure detection device. In addition to the detection position for system control, the device also sets temperature detection devices at the drying box, smoke inlet, cold water inlet, etc., thereby cooperating with the detection device for system control, pressure detection and temperature detection are carried out in real time. When abnormal conditions such as overpressure and overtemperature occur, the power of the water pump and the fan is increased in time to quickly reduce the internal pressure and temperature of the system. At the same time, the alarm information is fed back to promptly notify the staff to check the operation of the front-end drying box to ensure the safe operation of the device.
[0037] E. Device maintenance: After the operation is completed, the device can scrape the condensed water and pollutants in the flue gas remaining on the surface of the flat plate from top to bottom through the lifting scraper, scrape them into the concave cavity of the closing plate, and then remove the closing plate to clean the residue in the concave cavity, which is very convenient. Finally, put the closing plate back to re-enter the standby state.
[0038] Based on energy consumption and cost analysis, this device has demonstrated significant economic benefits and high efficiency characteristics. Specifically, through electric heating, the electricity required to raise the temperature of one ton of water from 20°C to 50°C is about 50 degrees; it is designed to provide 8 tons of hot water per hour, which is equivalent to 7,900 hours of effective working time based on the annual operating days of 330 days. It can be calculated that 3.16 million degrees of electricity can be saved annually. Therefore, this device has a strong application prospect.
[0039] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the design concept of the present invention should be included in the protection scope of the present invention.
Claims
1. A device for utilizing waste heat from flue gas of a drying box, characterized in that: The invention comprises a smoke collector (1) arranged at the outlet of a drying box (01), the end of the smoke collector (1) is connected to a heat exchanger (2), the end of the heat exchanger (2) is connected to an induced draft fan (3), the end of the induced draft fan (3) is connected to an external exhaust port, the heat exchanger (2) comprises a heat exchange chamber (201) and a hot water exchange pipe (202) passing through the heat exchange chamber (201), the beginning and end ends of the hot water exchange pipe (202) are respectively connected to an external cold water tank and an insulation water tank, the smoke collector (1) comprises a collection chamber (101) located in the drying box (01), a plurality of air suction ports (102) are arranged in the collection chamber (101), the plurality of air suction ports (102) are all connected to a main air intake port (103), and the main air intake port (103) is communicated with the heat exchange chamber (201).
2. The device for utilizing waste heat from flue gas of a drying box according to claim 1, characterized in that: A plurality of the air suction ports (102) are arranged vertically, and the air suction ports (102) are arranged along the width direction of the collection chamber (101), and the distance between the air suction ports is set to 300-500 mm.
3. The device for utilizing waste heat from flue gas of a drying box according to claim 1, characterized in that: The diameter of the air suction port (102) is set to 25-50 mm.
4. The device for utilizing waste heat from flue gas of a drying box according to claim 1, characterized in that: The air suction port (102) is provided with a side air suction port (1021) on the side wall, and the openings of the side air suction port (1021) are increased by 2-5% from near to far according to the distance from the main air suction port (103).
5. The device for utilizing waste heat from flue gas of a drying box according to claim 1, characterized in that: A sealing door is provided at the outlet of the collection chamber (101); the sealing door comprises an upper sealing plate (41) and a lower sealing plate (42) which abut against each other, the upper sealing plate (41) is made of a flexible material, and the lower sealing plate (42) is made of a rigid material.
6. The device for utilizing waste heat from flue gas of a drying box according to claim 1, characterized in that: The portion of the heat exchange water pipe (202) passing through the heat exchange cavity (201) is arranged as a flat plate (5) with a flat structure, and the flat plates (5) are arranged in an array at intervals in the heat exchange cavity (201).
7. The device for utilizing waste heat from flue gas of a drying box according to claim 6, characterized in that: An opening (6) is provided at the bottom of the heat exchange cavity (201) corresponding to the gap between the plurality of flat plates (5), and a detachable closing plate (601) with a sealing strip on the circumference is provided at the bottom of the heat exchange cavity (201), and a concave cavity (602) is provided in the closing plate (601).
8. The device for utilizing waste heat from flue gas of a drying box according to claim 7, characterized in that: A lifting scraper (7) is arranged in the heat exchange cavity (201), and the lifting scraper (7) is arranged in the gap between a plurality of flat plates (5). The lifting scraper (7) is arranged in an inverted V-shaped structure, and the edge of the lifting scraper (7) is arranged against the flat plate (5).
9. The device for utilizing waste heat from flue gas of a drying box according to claim 1, characterized in that: The invention also comprises a control device, the control device comprising a heat exchanger temperature detection device (8), a negative pressure detection device (9), an induced draft fan frequency conversion device, and a water pump control device. The heat exchanger temperature detection device (8) is arranged at the water outlet of the heat exchange water pipe (202) or at the air outlet of the heat exchange chamber (201) or at both places. The negative pressure detection device (9) is arranged in the collection chamber (101). The induced draft fan frequency conversion device is arranged on the induced draft fan (3). The water pump control device is arranged on the water pump between the cold water tank and the heat exchange water pipe.
10. A method for using the flue gas waste heat utilization device of a drying box as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: A. Pre-preparation: Check the connection and sealing status between the components. When the sealing status is confirmed, start the induced draft fan and check whether the negative pressure in the collection chamber is normal; Start the water pump and check whether the water temperature is normal; B. Startup of the device: The induced draft fan generates negative pressure when it is started, and the smoke collector captures the high-temperature smoke generated by the drying box, and guides the smoke into the heat exchanger. The water pump starts, and the water in the cold water tank exchanges heat with the high-temperature smoke through the flat plate of the heat exchange pipe. The obtained hot water is passed into the insulation water tank for storage. The cold water continuously passes through the heat exchanger to continuously generate hot water. The hot water in the insulation water tank can be connected to the external pipeline for washing the drying plate and strip, etc. C. System control: dynamically adjust the power of the induced draft fan to keep the negative pressure in the collection chamber within -5 to 0Pa; dynamically adjust the water temperature to control the water temperature between 50-55℃; the dynamic water temperature control includes adjusting according to the outlet water temperature or the flue gas outlet temperature or both temperatures at the same time; D. Safety protection: Pressure detection and temperature detection are carried out in real time. When abnormal conditions such as overpressure and overtemperature occur, the power of the water pump and fan is increased in time to quickly reduce the internal pressure and temperature of the system. At the same time, the alarm information is fed back and the operation of the front-end drying box is checked in time; E. Maintenance of the device: After the operation is completed, the condensed water and pollutants in the flue gas remaining on the surface of the flat plate are scraped from top to bottom by the lifting scraper, and then scraped into the concave cavity of the closing plate, and then the closing plate is removed, the residue in the concave cavity is cleaned, and finally the closing plate is replaced.