Secondary heat exchange system with self-cleaning function

Abstract

The utility model discloses a secondary heat exchange system with a self-cleaning function, and belongs to the field of flue gas treatment. The system comprises a heat storage chamber, denitration equipment, desulfurization equipment, smoke exhaust equipment, a first-stage heat exchanger and a second-stage heat exchanger, the first-stage heat exchanger is mounted between the denitration equipment and the desulfurization equipment, and the second-stage heat exchanger is mounted between the heat storage chamber and the denitration equipment; the first-stage heat exchanger receives smoke output by the heat storage chamber through the purging flue, and the desulfurization equipment receives smoke output by the first-stage heat exchanger through the backflow flue. According to the flue gas waste heat recovery device, flue gas waste heat recovery of the glass furnace can be achieved, meanwhile, the problem of element ash blocking caused by liquid ammonium bisulfate in the heat exchanger is solved, and the stability of flue gas treatment work is guaranteed.

Description

Technical Field

[0001] The utility model belongs to the field of flue gas treatment, and more specifically, relates to a secondary heat exchange system with self-cleaning. Background Technique

[0002] The high-temperature flue gas generated during the production process of glass furnaces is generally around 300°C to 500°C. This high-temperature flue gas has great recovery value. Using a heat exchanger for heat recovery to preheat air can achieve the goal of energy conservation and consumption reduction, and significantly reduce costs.

[0003] The exhaust gas temperature of the regenerator of the glass furnace is about 400°C, and this temperature shows an obvious upward trend with the increase in the production capacity of the glass furnace. The SCR denitration process window temperature is about 350°C, and then the flue gas enters the desulfurization tower, and the desulfurization process window temperature is about 250°C. It can be seen that there are two cooling links in the flue gas treatment process during the production of glass furnaces. One is from the outlet of the regenerator to the inlet of denitration, and the flue gas needs to be cooled by 50-100°C; the other is from the outlet of denitration to the inlet of desulfurization, and the temperature needs to be reduced by about 100°C.

[0004] In addition, during the operation of the denitration system, due to the incomplete reaction of ammonia, ammonia escape objectively exists. At the same time, during the denitration of flue gas, the active component - vanadium in the catalyst promotes the oxidation of SO2 in the flue gas into SO3 while catalytically reducing NOx. The conversion between the two is a function of temperature, and the conversion rate of SO2 increases with the increase in temperature. The escaped ammonia, SO3 and water in the flue gas will form a large amount of ammonium bisulfate. It is solid at room temperature, turns into a viscous liquid above 147°C, starts to boil at about 350°C, and the evaporation rate increases with the increase in temperature. After 350°C, the weight loss rate significantly accelerates. Ammonium bisulfate will not only corrode the cold-end heat transfer elements, but also the liquid ammonium bisulfate has extremely strong ability to capture fly ash, which is extremely easy to cause ash plugging of the cold-end layer elements, resulting in an increase in the operating resistance of the preheater and a decrease in the heat exchange effect.

[0005] For example, a patent document with a Chinese patent application number of: CN201911390881.1 and a publication date of: May 12, 2020 discloses a method for utilizing the waste heat of the flue gas from a glass furnace. The method includes: using the flue gas discharged from the glass furnace by the primary treatment module for preheating treatment to obtain flue gas at a temperature lower than 900 °C; using the flue gas at a temperature lower than 900 °C by the secondary treatment module for the first heat exchange treatment to obtain flue gas at a temperature lower than 300 °C; using the flue gas at a temperature lower than 300 °C by the tertiary treatment module for the second heat exchange treatment to obtain flue gas at a temperature of 150 - 200 °C; using the flue gas at a temperature of 150 - 200 °C by the quaternary treatment module for the third heat exchange treatment to obtain flue gas at a temperature of 100 - 150 °C; using the flue gas at a temperature of 100 - 150 °C by the quinary treatment module for the fourth heat exchange treatment to obtain flue gas at a temperature lower than 70 °C.

[0006] Another example is a patent document with a Chinese patent application number of: CN202122461037.2 and a publication date of: April 15, 2022, which discloses a comprehensive waste heat utilization system for a glass furnace, including a waste heat boiler, a steam power generation subsystem, and a flue gas recovery and discharge subsystem connected to the glass furnace. The steam power generation subsystem and the flue gas recovery and discharge subsystem are respectively connected to the waste heat boiler; on the one hand, the steam power generation subsystem utilizes waste heat to generate electricity, and on the other hand, steam is generated while generating electricity. The steam is further recovered and utilized and enters a lithium bromide heat exchange unit and a corrugated tube steam-water heat exchange unit for refrigeration and heating; the flue gas recovery and discharge subsystem further realizes heat supply by conducting the heat of the flue gas to the heat exchange working medium.

[0007] In the above two solutions, waste heat recovery is carried out for the flue gas generated by the glass furnace. However, neither of them has a good solution to the problem that the liquid ammonium bisulfate mentioned above will capture fly ash, causing ash blockage of the cold-end layer components, resulting in an increase in the operating resistance of the preheater and a decrease in the heat exchange effect. Summary of the Invention

[0008] 1. Problems to be Solved

[0009] Aiming at the problem that it is difficult to solve the ash blockage of components in the heat exchanger when the existing flue gas treatment system exchanges heat for the flue gas of the glass furnace, the present utility model provides a secondary heat exchange system with self-cleaning, which can solve the problem of ash blockage of components caused by liquid ammonium bisulfate in the heat exchanger while realizing the waste heat recovery of the flue gas of the glass furnace, and ensure the stability of the flue gas treatment work.

[0010] 2. Technical Solution

[0011] To solve the above problems, the present utility model adopts the following technical solutions.

[0012] A secondary heat exchange system with self-cleaning function, comprising a regenerator, a denitration device, a desulfurization device and a smoke exhaust device connected in sequence, as well as a primary heat exchanger and a secondary heat exchanger; the primary heat exchanger is installed between the denitration device and the desulfurization device, and the secondary heat exchanger is installed between the regenerator and the denitration device; the primary heat exchanger receives the flue gas output from the regenerator through a purge flue, and the desulfurization device receives the flue gas output from the primary heat exchanger through a reflux flue.

[0013] As a further improvement of the technical solution, a heat exchange unit is provided in the primary heat exchanger. The heat exchange unit has an air inlet, an air outlet, a flue gas inlet and a flue gas outlet. The air inlet and the air outlet are connected by a pipeline, and the flue gas inlet and the flue gas outlet are connected by a pipeline.

[0014] As a further improvement of the technical solution, a three-way valve is installed at the flue gas inlet. The three-way valve is respectively connected to the purge flue and the smoke exhaust port of the denitration device through pipelines; a three-way valve is installed at the flue gas outlet. The three-way valve is respectively connected to the reflux flue and the flue gas inlet of the desulfurization device through pipelines.

[0015] As a further improvement of the technical solution, there are multiple heat exchange units, which are arranged at intervals in the primary heat exchanger.

[0016] As a further improvement of the technical solution, the pipeline between the air inlet and the air outlet is of a spiral coil structure.

[0017] As a further improvement of the technical solution, the pipeline between the flue gas inlet and the flue gas outlet is of a spiral coil structure.

[0018] As a further improvement of the technical solution, a shock wave soot blower is also installed on the heat exchange unit.

[0019] As a further improvement of the technical solution, the secondary heat exchanger receives the air output from the primary heat exchanger through an air connection pipe.

[0020] As a further improvement of the technical solution, a dust collector is installed between the desulfurization device and the smoke exhaust device.

[0021] 3. Beneficial effects

[0022] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0023] (1) The present utility model relates to a secondary heat exchange system with self-cleaning function. By conveying the high-temperature flue gas output from the regenerator to the primary heat exchanger along the purging flue, the surface temperature of the primary heat exchanger elements can reach the decomposition temperature of ammonium bisulfate in the fouling. After the decomposition of ammonium bisulfate, the gaseous products are precipitated, making the fouling loose, thus solving the problem of ash blockage in the elements of the primary heat exchanger. At the same time, the high-temperature flue gas returns to the denitration equipment through the reflux flue, ensuring that all flue gas passes through denitration and meeting the environmental protection requirements.

[0024] (2) The present utility model relates to a secondary heat exchange system with self-cleaning function, which uses the high-temperature flue gas generated by the system itself as the self-cleaning energy source, without external energy and equipment, achieving the maximum utilization of resources in the whole system and effectively saving the cleaning cost.

[0025] (3) The present utility model relates to a secondary heat exchange system with self-cleaning function. By setting multiple heat exchange units, when a single heat exchange unit is performing self-cleaning, other heat exchange units can ensure the normal operation of the whole system. Multiple units take turns to carry out the cleaning work, achieving self-cleaning while ensuring the heat exchange efficiency and avoiding affecting the normal operation of the system.

[0026] (4) The present utility model relates to a secondary heat exchange system with self-cleaning function. The heat exchange unit is also equipped with a shock wave soot blower, which can purge the loose fouling on the surface of the primary heat exchanger elements after the fouling is loosened, improving the cleaning effect of the heat exchanger. Description of the Drawings

[0027] Figure 1 is the installation flow chart of the whole system;

[0028] Figure 2 is the structural schematic diagram of the primary heat exchanger;

[0029] In the figure: 1, primary heat exchanger; 11, heat exchange unit; 111, air inlet; 112, air outlet; 113, flue gas inlet; 114, flue gas outlet; 115, shock wave soot blower; 2, purging flue; 3, reflux flue; 4, secondary heat exchanger; 5, air connection pipe; 6, regenerator; 7, denitration equipment; 8, desulfurization equipment; 9, smoke exhaust equipment; 10, dust collector. Detailed Embodiment

[0030] The exemplary embodiments of the present utility model are described in detail below. Although these exemplary embodiments are described in sufficient detail to enable those skilled in the art to implement the present utility model, it should be understood that other embodiments can be achieved and various changes can be made to the present utility model without departing from the spirit and scope of the present utility model. The following more detailed description of the embodiments of the present utility model is not intended to limit the scope of the claimed present utility model, but is merely for illustrative purposes and does not limit the description of the features and characteristics of the present utility model, to present the best mode of implementing the present utility model, and to be sufficient to enable those skilled in the art to implement the present utility model. Therefore, the scope of the present utility model is only defined by the appended claims.

[0031] Embodiment 1

[0032] A two-stage heat exchange system with self-cleaning, belonging to a system for cooling, denitrifying, and desulfurizing the flue gas generated in the regenerator during the production of glass furnaces. The specific structure and technical effects are described in detail below.

[0033] As Figure 1 and Figure 2 shown, the system includes a glass furnace regenerator 6, a two-stage heat exchanger 4, a denitrification device 7, a primary heat exchanger 1, a desulfurization device 8, a dust collector 10, and an exhaust gas device 9 connected in sequence along the normal flue gas transmission route. In this embodiment, the heat exchanger can be a heat pipe heat exchanger or a shell and tube heat exchanger. The flue gas and air in the heat exchanger are both arranged in countercurrent to obtain higher heat exchange efficiency.

[0034] Among them, the primary heat exchanger 1 receives the flue gas output from the regenerator 6 through a purge flue 2, the desulfurization device 8 receives the flue gas output from the primary heat exchanger 1 through a reflux flue 3, and the two-stage heat exchanger 4 receives the air output from the primary heat exchanger 1 through an air connection pipe 5. During the flue gas transmission process, the primary heat exchanger 1 recovers the heat of the denitrified flue gas, reducing its temperature from 350 °C to 250 °C and preheating the air temperature from room temperature to 160 °C. The two-stage heat exchanger 4 recovers the heat of the flue gas from the regenerator 6 to before denitrification, reducing its temperature from 420 °C to 360 °C and further preheating the air to 280 °C.

[0035] The primary heat exchanger 1 is provided with a heat exchange unit 11. The heat exchange unit 11 has an air inlet 111, an air outlet 112, a flue gas inlet 113, and a flue gas outlet 114. The air inlet 111 and the air outlet 112 are connected by a pipeline, and the flue gas inlet 113 and the flue gas outlet 114 are connected by a pipeline.

[0036] More specifically, the flue gas inlet 111 is equipped with a three-way valve, which is connected to the purge flue 2 and the exhaust port of the denitrification equipment 7 through pipelines. The flue gas outlet 114 is equipped with a three-way valve, which is connected to the return flue 3 and the smoke inlet of the desulfurization equipment 8 through pipelines.

[0037] By transporting the high-temperature flue gas output from the heat storage chamber 6 to the primary heat exchanger 1 along the purge flue 2, the surface of the components of the primary heat exchanger 1 can reach the decomposition temperature of ammonium bisulfate in the dirt. After the decomposition of ammonium bisulfate, the gas phase product is precipitated to loosen the dirt, thereby solving the problem of ash blockage of the components in the primary heat exchanger 1. At the same time, the high-temperature flue gas returns to the denitrification equipment 7 through the return flue 3, which can ensure that all the flue gas is denitrified and meets environmental protection requirements. In addition, this embodiment uses the high-temperature flue gas of the system itself as a self-cleaning energy source, without the need for external energy and equipment, to maximize the utilization of resources of the entire system and effectively save cleaning costs.

[0038] In this embodiment, each flue and pipeline is equipped with a separate control valve. When the heat exchange unit 11 of the primary heat exchanger 1 needs to be purged and cleaned with high-temperature flue gas, the inlet and outlet pipe valves of the denitrification flue gas in the heat exchange unit 11 are closed, and the valves of the purge flue 2 and the return flue 4 are opened. The high-temperature flue gas enters the heat exchange unit 11 through the purge flue 2. While completing the cleaning work in the heat exchange unit 11, it exchanges heat with the air in the normally opened air channel in the heat exchange unit 11, and then is transported to the denitrification equipment through the return flue 4 for denitrification. In order to further ensure the cleaning effect, the heat exchange unit 11 is also equipped with a shock wave soot blower 115 in this embodiment. The shock wave soot blower 115 can blow the loose dirt after the dirt on the surface of the heat exchange unit 11 element is loosened, thereby improving the cleaning effect of the heat exchanger.

[0039] In this embodiment, in order to improve the heat exchange effect, the pipe between the air inlet 111 and the air outlet 112 and the pipe between the smoke inlet 113 and the smoke outlet 114 are set to a spiral coil structure, which increases the heat exchange time and the heat exchange efficiency by increasing the gas circulation time.

[0040] It is worth mentioning that there are multiple heat exchange units 11, which are arranged at intervals in the primary heat exchanger 1. In this embodiment, there are three heat exchange units 11. By setting multiple heat exchange units 11, when a single heat exchange unit 11 is performing self-cleaning, other heat exchange units 11 can ensure the normal operation of the entire system. Multiple heat exchange units 11 perform cleaning work in turn, which can achieve self-cleaning to ensure heat exchange efficiency while avoiding affecting the normal operation of the system.

[0041] In summary, the self-cleaning secondary heat exchange system of this embodiment can recover the waste heat of the flue gas of the glass furnace while solving the problem of component clogging caused by liquid ammonium bisulfate in the heat exchanger, thereby ensuring the stability of the flue gas treatment work.

Claims

1. A two-stage heat exchange system with self-cleaning function, comprising a heat storage chamber (6), a denitrification device (7), a desulfurization device (8) and a smoke exhaust device (9) connected in sequence, characterized in that: It also comprises a primary heat exchanger (1) and a secondary heat exchanger (4); the primary heat exchanger (1) is installed between the denitration equipment (7) and the desulfurization equipment (8), and the secondary heat exchanger (4) is installed between the heat storage chamber (6) and the denitration equipment (7); the primary heat exchanger (1) receives the flue gas output from the heat storage chamber (6) through the purge flue (2), and the desulfurization equipment (8) receives the flue gas output from the primary heat exchanger (1) through the return flue (3).

2. A two-stage heat exchange system with self-cleaning according to claim 1, characterized in that: The primary heat exchanger (1) is provided with a heat exchange unit (11), the heat exchange unit (11) having an air inlet (111), an air outlet (112), a smoke inlet (113) and a smoke outlet (114), the air inlet (111) and the air outlet (112) being connected via a pipeline, and the smoke inlet (113) and the smoke outlet (114) being connected via a pipeline.

3. A two-stage heat exchange system with self-cleaning according to claim 2, characterized in that: The flue gas inlet (113) is equipped with a three-way valve, which is connected to the purge flue (2) and the smoke exhaust port of the denitrification equipment (7) through pipelines, and the pipeline is equipped with a valve; the flue gas outlet (114) is equipped with a three-way valve, which is connected to the return flue (3) and the smoke inlet of the desulfurization equipment (8) through pipelines.

4. A two-stage heat exchange system with self-cleaning according to claim 3, characterized in that: The heat exchange units (11) are in plurality and are arranged at intervals in the primary heat exchanger (1).

5. A two-stage heat exchange system with self-cleaning according to any one of claims 2, 3 or 4, characterized in that: The pipeline between the air inlet (111) and the air outlet (112) is a spiral coil structure.

6. A two-stage heat exchange system with self-cleaning according to any one of claims 2, 3 or 4, characterized in that: The pipe between the smoke inlet (113) and the smoke outlet (114) is a spiral coil structure.

7. A two-stage heat exchange system with self-cleaning according to any one of claims 2, 3 or 4, characterized in that: The heat exchange unit (11) is also equipped with a shock wave soot blower (115).

8. A two-stage heat exchange system with self-cleaning according to any one of claims 1 to 4, characterized in that: The secondary heat exchanger (4) receives the air output by the primary heat exchanger (1) through the air connecting pipe (5).

9. A two-stage heat exchange system with self-cleaning according to any one of claims 2 to 4, characterized in that: A dust collector (10) is installed between the desulfurization equipment (8) and the smoke exhaust equipment (9).

Images