A system for recovering and utilizing waste heat from a float glass annealing lehr

Abstract

This invention discloses a waste heat recovery system for float glass annealing furnaces in the field of float glass production technology. The system includes an annealing furnace and a waste heat boiler. The annealing furnace is divided into zones A, B, and C. An exhaust pipe is connected at the beginning of zone C, and an inlet pipe is connected at the end of zone C. The exhaust pipe and inlet pipe are connected through the waste heat boiler. The waste heat boiler includes a first boiler drum, a second boiler drum, and a pipe bundle. A first flue is provided on the outer wall of the first boiler drum, and a second flue is provided at the pipe bundle. The exhaust pipe and inlet pipe are connected through the first flue. A heat insulation plate is installed inside the first boiler drum. The heat insulation plate changes the heat absorption efficiency of the first flue by altering its distance from the water-cooled wall of the first boiler drum. The circulating airflow in the first flue contacts the cooling wall of the first boiler drum and exchanges heat with the cooling liquid in the first boiler drum through the cooling wall, thereby completing waste heat recovery. This reduces the amount of waste gas emitted in the entire circulation system and increases the waste heat recovery efficiency.

Description

Technical Field

[0001] This invention relates to the field of float glass production technology, specifically to a waste heat recovery and utilization system for float glass annealing furnaces. Background Technology

[0002] In the float glass production process, the annealing furnace is a key piece of equipment for eliminating internal stress and stabilizing the internal structure of the glass ribbon after it has been formed. The annealing furnace is usually divided into Zone A (pre-annealing zone), Zone B (annealing zone), and Zone C (cooling zone). Each zone maintains a specific temperature regime through a hot air circulation system to ensure the annealing quality of the glass ribbon.

[0003] In the annealing furnace, zones A and B primarily rely on heat dissipation from the furnace wall, with internal airflow circulation ensuring temperature balance. Zone C is a forced cooling zone, which, due to process requirements, requires the continuous introduction of external cooling airflow to replace the high-temperature gas inside the chamber. This achieves rapid cooling of the glass ribbon and reduces humidity within the chamber, preventing localized sudden cooling of the glass and inaccurate temperature detection caused by a high-humidity environment. The aforementioned gas replacement process causes a large amount of high-temperature waste gas (typically between 300°C and 450°C) to be continuously discharged from zone C, resulting in significant waste of thermal energy and exacerbating thermal pollution in the factory area and surrounding environment.

[0004] Currently, the industry generally uses waste heat recovery to treat this high-temperature exhaust gas, which involves passing the high-temperature exhaust gas discharged from Zone C into a separate waste heat recovery device. Although this method can recover some heat from the exhaust gas and reduce the exhaust gas emission temperature, it cannot reduce the overall exhaust gas emission volume. The lower the final exhaust gas emission temperature, the higher the technological difficulty and equipment operating cost of waste heat recovery. Since the existing solution cannot reduce the exhaust gas emission volume, it is difficult to further improve the overall recovery efficiency of the waste heat recovery system. The industry urgently needs a technical solution that can simultaneously optimize the exhaust gas emission volume and waste heat utilization rate. Summary of the Invention

[0005] The purpose of this invention is to provide a waste heat recovery and utilization system for float glass annealing furnaces to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a waste heat recovery and utilization system for a float glass annealing furnace, comprising an annealing furnace and a waste heat boiler. The annealing furnace is divided into zone A, zone B, and zone C from the inlet to the outlet. An exhaust pipe is connected to the beginning of zone C; an air inlet pipe is connected to the end of zone C, and the air inlet pipe is connected to a cold air injection unit; the exhaust pipe and the air inlet pipe are connected through the waste heat boiler. The waste heat boiler includes a boiler drum 1, a boiler drum 2, and a pipe bundle connecting the two. A flue 1 is provided on the outer wall of the boiler drum 1, and a flue 2 is provided at the pipe bundle. The exhaust pipe and the intake pipe are connected through a flue, and the outer wall of the boiler drum is used as a water-cooled wall. The exhaust pipe is connected to a waste gas emission unit, which is connected to flue 2 via an external pipe, and flue 2 is used as the waste gas emission pipe. The boiler drum is equipped with a heat insulation plate. The heat insulation plate changes the heat absorption efficiency of the flue by changing the distance between itself and the water-cooled wall of the boiler drum.

[0007] Preferably, the water-cooled wall of the boiler drum is provided with a plurality of heat exchange sections protruding into the flue.

[0008] Preferably, the heat insulation plate can isolate the communication between the heat exchange section and the inner cavity of the boiler drum.

[0009] Preferably, the inner cavity of the boiler drum is provided with a driving unit and multiple heat insulation plates, the heat insulation plates being parallel to the water-cooled wall; the driving unit is connected to the heat insulation plates in a transmission manner and is used to drive the heat insulation plates to change the distance between them and the water-cooled wall of the boiler drum.

[0010] Preferably, the heat insulation plate includes a main body and raised portions on both sides of the main body.

[0011] Preferably, the boiler drum is a double-layered U-shaped sleeve sealed at both ends, which includes an inner sleeve, an outer sleeve and a sealing part located at both ends of the boiler drum, and the flue is composed of the side wall of the inner sleeve of the boiler drum.

[0012] Preferably, the waste heat boiler further includes an external cooling water supply component, which is connected to the boiler drum.

[0013] Preferably, the exhaust port of the second flue is connected to the cooling water replenishment component.

[0014] Compared with the prior art, the beneficial effects of the present invention are: In flue gas duct 1, the circulating airflow comes into contact with the cooling wall of boiler drum 1 and exchanges heat with the coolant in boiler drum 1 through the cooling wall, thereby completing the waste heat recovery. In this way, the injection of cooling airflow and the emission of high-temperature exhaust gas to maintain the total heat balance of the circulating airflow are reduced or eliminated throughout the entire circulation process. This greatly reduces the amount of exhaust gas emitted in the entire circulation system, thereby reducing the heat carried away by the exhaust gas and effectively increasing the waste heat recovery efficiency.

[0015] By controlling the distance between the heat insulation plate and the cooling wall, the difficulty of bubbles generated by liquid evaporation detaching from the cooling wall surface is changed, thereby controlling the thickness and density of the bubble film on the cooling wall surface. This controls the heat exchange efficiency between the circulating airflow and the coolant, and thus controls the proportion of cooling airflow added to the circulating airflow, preventing the humidity of the circulating airflow from increasing too quickly.

[0016] When the system detects that the humidity has increased to the predetermined warning value, it directly controls the heat insulation plate to adhere to the cooling wall, thus isolating the cooling wall from the coolant. This significantly reduces the rate at which the temperature of the circulating airflow decreases in the flue, thereby greatly increasing the amount of cooling airflow added to the circulating airflow and rapidly reducing the humidity in the circulating airflow to maintain the humidity within the predetermined range. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the airflow circulation principle in a traditional annealing kiln. Figure 3 This is a schematic diagram of the airflow circulation principle of the annealing furnace of the present invention; Figure 4 This is a schematic diagram of the front section structure of the present invention; Figure 5 This is a schematic diagram of the side cross-section structure of the present invention; Figure 6 This is a schematic diagram of the insulation board.

[0018] The attached diagram lists the components represented by each number as follows: Annealing kiln 1, Area A 11, Area B 12, Area C 13, Exhaust pipe 2, Inlet pipe 3, Cold air injection unit 4, Waste heat boiler 5, Boiler drum 1 51, Flue 1 511, Boiler drum 2 52, Pipe bundle 53, Flue 2 531, Exhaust gas emission unit 6, Heat insulation plate 7, Main body 71, Raised part 72, Drive unit 8. Detailed Implementation

[0019] Please see Figure 1-6 This invention provides a technical solution: a waste heat recovery and utilization system for a float glass annealing furnace, comprising an annealing furnace 1 and a waste heat boiler 5. The annealing furnace 1 is divided into zone A 11, zone B 12 and zone C 13 from the inlet to the outlet. An exhaust pipe 2 is connected to the beginning of zone C 13; an air inlet pipe 3 is connected to the end of zone C 13, and the air inlet pipe 3 is connected to a cold air injection unit 4; the exhaust pipe 2 and the air inlet pipe 3 are connected through the waste heat boiler 5. The waste heat boiler 5 includes a first boiler drum 51, a second boiler drum 52, and a pipe bundle 53 connecting the two. A first flue 511 is provided on the outer wall of the first boiler drum 51, and a second flue 531 is provided at the pipe bundle 53. The exhaust pipe 2 and the intake pipe 3 are connected through the flue 511, and the outer wall of the boiler drum 51 is used as a water-cooled wall. The exhaust pipe 2 is connected to the exhaust gas emission unit 6, which is connected to the flue 2 531 through an external pipe, and the flue 2 531 is used as the exhaust gas emission pipe. A heat insulation plate 7 is installed inside the boiler drum 51. The heat insulation plate 7 changes the heat absorption efficiency of the flue 511 by changing the distance between itself and the water-cooled wall of the boiler drum 51.

[0020] like Figure 3 During the operation of annealing furnace 1, a circulating airflow is formed in the air inlet pipe 3, zone C 13, exhaust pipe 2 and flue 511 (the power source of the airflow is not shown). This circulating airflow travels from the end to the beginning of zone C 13, continuously carrying away the heat in zone C 13 to achieve the purpose of cooling the glass. During the circulation process, the cold air injection unit 4 adds a cooler airflow at a lower temperature to the circulating airflow at the end of zone C 13 (at the air inlet pipe 3) to reduce the temperature of the circulating airflow entering zone C 13 and dilute the airflow humidity, so that when the circulating airflow, which has already carried away heat and moisture by zone C 13, re-enters zone C 13, its temperature and humidity can meet the system's predetermined values. Furthermore, at the beginning of zone C13 (at exhaust pipe 2), high-temperature exhaust gas is discharged into flue 2 531 through exhaust gas emission unit 6 to maintain the balance of total gas volume, total heat and humidity of the circulating airflow. During this process, the temperature, pressure and other values ​​in the intake pipe 3, C zone 13, exhaust pipe 2 and flue 511 are measured in real time, and the measured values ​​are fed back to the cold air injection unit 4 and the exhaust gas emission unit 6 in real time. The two are linked to control the injection volume and injection temperature of the cooling airflow and the emission volume of high temperature exhaust gas, so that the total amount of gas, total heat and humidity of the circulating airflow are kept in dynamic balance. Among them, the high-temperature exhaust gas emitted by exhaust gas emission unit 6 into flue 2 531 passes through pipe bundle 53 in flue 2 531 and is discharged after absorbing waste heat through pipe bundle 53. Compared to traditional solutions, in this invention, the circulating airflow returns from the exhaust pipe 2 to the intake pipe 3 through the flue 511, completing the circulation. In the flue 511, the circulating airflow contacts the cooling wall of the boiler drum 51 and exchanges heat with the coolant of the boiler drum 51 through the cooling wall, thereby completing waste heat recovery. In this way, the injection of cooling airflow and the emission of high-temperature exhaust gas are reduced or eliminated in order to maintain the total heat balance of the circulating airflow during the entire circulation process (the heat recovered by the waste heat boiler 5 is finally discharged from the waste heat boiler 5 in the form of steam and transferred to the equipment to be used. The corresponding technology is relatively common and is not the focus of this invention, so the corresponding features are not shown). The injection of cooling airflow and the discharge of high-temperature exhaust gas are mainly used to maintain the humidity of the circulating airflow below the threshold, which greatly reduces the amount of exhaust gas emissions in the entire circulation system, thereby reducing the heat carried away by the exhaust gas and correspondingly increasing the waste heat recovery efficiency. The process of maintaining the humidity of the circulating airflow involves controlling the distance between the heat insulation plate 7 and the cooling wall, thereby changing the difficulty for bubbles generated by liquid evaporation to detach from the surface of the cooling wall. This, in turn, controls the thickness and density of the bubble film on the surface of the cooling wall, thus controlling the heat exchange efficiency between the circulating airflow and the coolant. This prevents the humidity of the circulating airflow from increasing too quickly (the higher the heat exchange efficiency, the less cooling airflow is added to the circulating airflow, and the faster the humidity increases). When the system detects that the humidity has increased to a predetermined warning value, it directly controls the heat insulation plate 7 to adhere to the cooling wall, thus isolating the cooling wall from the coolant. This significantly reduces the rate at which the temperature of the circulating airflow decreases in the flue 511, thereby significantly increasing the amount of cooling airflow added to the circulating airflow and rapidly reducing the humidity in the circulating airflow to maintain the humidity of the circulating airflow within a predetermined range.

[0021] Preferably, the boiler drum 51 is a double-layered U-shaped sleeve sealed at both ends, which includes an inner sleeve, an outer sleeve and a sealing part located at both ends of the boiler drum 51, and the flue 511 is composed of the side wall of the inner sleeve of the boiler drum 51.

[0022] By setting the boiler drum 51 in a U-shape with double-layer sleeves, the flue 511 is directly composed of the boiler drum wall of the boiler drum 51, thus making the entire side wall of the flue 511 a cooling wall, effectively increasing the heat exchange area of ​​the flue 511 and improving the waste heat recovery efficiency of the system.

[0023] Preferably, the inner cavity of the boiler drum 51 is provided with a driving unit 8 and multiple heat insulation plates 7. The multiple heat insulation plates 7 are arranged around the inner sleeve of the boiler drum 51, and the heat insulation plates 7 are parallel to the wall of the inner sleeve. The driving unit 8 is connected to the heat insulation plates 7 and is used to drive the heat insulation plates 7 to change the distance between them and the water-cooled wall of the boiler drum 51.

[0024] By setting multiple heat insulation plates 7, the water vapor generated on the water-cooled wall can escape from the gap between the water-cooled wall and the heat insulation plates 7 through the gaps between the heat insulation plates 7, thus preventing all the kinetic energy generated when the liquid vaporizes from impacting the water-cooled wall and the heat insulation plates 7. This maintains the stability of the components and ensures the normal operation of the system.

[0025] Preferably, the heat insulation plate 7 includes a main body 71 and raised portions 72 on both sides of the main body 71.

[0026] The raised portion 72 is provided so that the air bubbles located in the gap between two adjacent heat insulation plates 7 can be surrounded by the raised portion 72. When the heat insulation plate 7 is attached to the cooling wall, the presence of air bubbles in the gap can isolate the cooling wall from the coolant. In addition, the raised portion 72 also has the function of guiding and collecting, collecting the air bubbles generated on the cooling wall and discharging them between adjacent raised portions 72, thereby increasing the disturbance intensity of the air bubbles on the coolant, improving the mixing function of the air bubbles on the coolant, and increasing the temperature uniformity of the coolant.

[0027] Preferably, the waste heat boiler 5 further includes an external cooling water supply component, which is connected to the boiler drum 52.

[0028] Cooling water is supplied from boiler drum 2 52 to waste heat boiler 5. The supplied cooling water is then supplied to boiler drum 1 51 through pipe bundle 53. In this way, during the heat recovery process, the exhaust gas in flue 2 531 heats the cooling water in pipe bundle 53. The heated cooling water in pipe bundle 53 then enters boiler drum 1 51 to cool the circulating airflow. During this process, the cooling water temperature in the pipe bundle 53 is lower than the cooling water temperature in the boiler drum 51. The pipe bundle 53, which has a lower temperature, is used to absorb the final heat of the exhaust gas that is about to leave the circulation system, while the boiler drum 51, which has a higher temperature, is used to continuously absorb heat from the circulating airflow that is repeatedly circulated. This increases the temperature difference for the exhaust gas to recover waste heat, thereby increasing the recovery efficiency of the exhaust gas waste heat. The circulating airflow needs to be repeatedly heated and cooled to serve as a temperature transfer point between zone C 13 and boiler drum 51, and the required heat exchange rate when it is cooled in flue 511 is reduced.

[0029] Preferably, the exhaust port of the second flue 531 is connected to the cooling water replenishment component.

[0030] The exhaust gas after waste heat recovery in flue 2 531 is reintroduced into the cooling water replenishment component to preheat the cooling water, further improving the overall heat recovery efficiency of the system.

[0031] Preferably, the inner sleeve is provided with multiple heat exchange sections protruding into the flue 511.

[0032] By setting up multiple heat exchange sections protruding into the flue 511, the heat exchange area of ​​the flue 511 can be effectively increased, thereby significantly improving the maximum heat exchange efficiency of the flue 511 and enhancing the applicability of the system.

[0033] Preferably, the heat exchange section corresponds one-to-one with the heat insulation plate 7, and the heat insulation plate 7 can isolate the heat exchange section from the inner cavity of the boiler drum 51.

[0034] When it is necessary to reduce the heat exchange efficiency of flue 511, the heat insulation plate 7 moves towards the connection between the heat exchange section and the inner cavity of the boiler drum 51, reducing the size of the connection gap between the heat exchange section and the inner cavity of the boiler drum 51, until the heat insulation plate 7 is about to completely separate the heat exchange section from the inner cavity of the boiler drum 51. It should be noted that by setting the shape of the heat insulation plate 7 and controlling the movement parameters of the heat insulation plate 7, a certain connection gap is always maintained between the heat exchange section and the inner cavity of the boiler drum 51, so that the bubbles generated in the heat exchange section can enter the boiler drum 51.

Claims

1. A waste heat recovery and utilization system for a float glass annealing furnace, comprising an annealing furnace (1) and a waste heat boiler (5), wherein the annealing furnace (1) is divided into zone A (11), zone B (12) and zone C (13) from the inlet to the outlet, and an exhaust pipe (2) is connected to the beginning of zone C (13); an air inlet pipe (3) is connected to the end of zone C (13), and the air inlet pipe (3) is connected to a cold air injection unit (4); characterized in that: The exhaust pipe (2) and the intake pipe (3) are connected through the waste heat boiler (5); The waste heat boiler (5) includes a first boiler drum (51), a second boiler drum (52), and a pipe bundle (53) connecting the two. A first flue (511) is provided on the outer wall of the first boiler drum (51), and a second flue (531) is provided at the pipe bundle (53). The exhaust pipe (2) and the intake pipe (3) are connected through flue 1 (511) and the outer wall of boiler drum 1 (51) is used as a water-cooled wall. The exhaust pipe (2) is connected to the exhaust gas emission unit (6), which is connected to the second flue (531) through an external pipe, and the second flue (531) is used as the exhaust gas emission pipe. The boiler drum (51) is equipped with a heat insulation plate (7). The heat insulation plate (7) changes the heat absorption efficiency of the flue (511) by changing the distance between itself and the water-cooled wall of the boiler drum (51).

2. The waste heat recovery and utilization system for a float glass annealing furnace according to claim 1, characterized in that: The water-cooled wall of the boiler drum (51) is provided with multiple heat exchange sections that protrude into the flue (511).

3. The waste heat recovery and utilization system for a float glass annealing furnace according to claim 2, characterized in that: The heat insulation plate (7) can isolate the heat exchange section from the inner cavity of the boiler drum (51).

4. The waste heat recovery and utilization system for a float glass annealing furnace according to claim 1, characterized in that: The inner cavity of the first boiler drum (51) is provided with a driving unit (8) and multiple heat insulation plates (7), the heat insulation plates (7) being parallel to the water-cooled wall; the driving unit (8) is connected to the heat insulation plates (7) and is used to drive the heat insulation plates (7) to change the distance between them and the water-cooled wall of the first boiler drum (51).

5. A waste heat recovery and utilization system for a float glass annealing furnace according to claim 4, characterized in that: The heat insulation plate (7) includes a main body (71) and raised portions (72) on both sides of the main body (71).

6. The waste heat recovery and utilization system for a float glass annealing furnace according to claim 1, characterized in that: The boiler drum (51) is a double-layered sleeve with sealed ends, including an inner sleeve, an outer sleeve and a closed part located at both ends of the boiler drum (51). The flue (511) is composed of the side wall of the inner sleeve of the boiler drum (51).

7. The waste heat recovery and utilization system for a float glass annealing furnace according to claim 1, characterized in that: The waste heat boiler (5) also includes an external cooling water supply component, which is connected to the boiler drum (52).

8. A waste heat recovery and utilization system for a float glass annealing furnace according to claim 7, characterized in that: The exhaust port of the second flue (531) is connected to the cooling water replenishment component.

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