A device and method for controlling the oxygen content of exhaust gas from a heating furnace drying process.

Abstract

This invention discloses a device and method for controlling the oxygen content of drying exhaust gas from a heating furnace, relating to the field of exhaust gas treatment technology. The device includes an insulated chamber containing a heating furnace and a drying chamber. A control device is located outside the insulated chamber, which also includes an exhaust pipe, a gas purification module, an exhaust pipe, and a fan. The control device incorporates an airflow regulation system to receive signals from an oxygen content monitor. This device, through a return pipe located at the exhaust port, mixes a portion of the low-temperature exhaust gas with fresh air and reintroduces it into the intake pipe. A return controller controls the return ratio, stabilizing the oxygen content of the drying hot air below 14%. Furthermore, the airflow regulation system receives signals from oxygen content monitors at the exhaust port and within the drying chamber, enabling real-time monitoring of the exhaust gas oxygen content and triggering a closed-loop control mechanism with the airflow regulation system.

Description

Technical Field

[0001] This invention relates to the field of waste gas treatment technology, specifically to a device and method for controlling the oxygen content of waste gas from a heating furnace drying process. Background Technology

[0002] As a key piece of equipment for material pretreatment in industrial production, heating furnaces are widely used in industries such as chemical, building materials, and food processing. Direct contact hot air drying has become the mainstream process choice due to its high heat transfer efficiency and simple operation. However, this process requires continuous hot air to be introduced to contact the material, which leads to a significant increase in the oxygen content coefficient in the exhaust gas, generally exceeding 18%.

[0003] The compliance of pollutant emissions from the drying process in heating furnaces faces a dual dilemma, primarily due to unclear definitions of applicable emission standards. Some enterprises confuse the relationship between "heating furnace equipment attributes" and "exhaust gas generation attributes," believing that heating furnaces belong to industrial furnaces and kilns, and therefore their exhaust emissions should comply with the "Emission Standard of Air Pollutants for Industrial Furnaces and Kilns" (GB 9078-1996). They ignore the essential difference between "fuel combustion flue gas" and "process drying exhaust gas." In reality, the exhaust gas from the drying process originates from the material drying process itself, not from the fuel combustion in the heating furnace, and should comply with the "Integrated Emission Standard of Air Pollutants" (GB 16297-1996), without the need for oxygen content conversion. This confusion regarding the application of standards leads to the compliance risk of "false exceedances."

[0004] Secondly, in order to ensure the uniformity of material drying, the direct contact drying process usually adopts an excessive air design, which leads to an excessively high oxygen content in the exhaust gas. According to the "Emission Standard of Air Pollutants for Industrial Furnaces and Kilns" and related local standards, the pollutant emission concentration of drying exhaust gas needs to be converted according to the benchmark oxygen content. However, traditional heating furnaces mostly use simple mechanical control and cannot dynamically adjust the air intake according to the material drying progress. The measured oxygen content of the flue gas often exceeds the standard, thus failing to meet the indicators of the "Emission Standard of Air Pollutants for Industrial Furnaces and Kilns".

[0005] Furthermore, some equipment lacks online oxygen content monitoring devices and targeted control methods. While existing technologies already include some solutions for controlling flue gas oxygen content, such as a patent that discloses a high-efficiency oxygen-controlled furnace that controls flue gas oxygen content by improving a conventional hot air furnace, and another patent that relates to a device and method for reducing the oxygen content of hot air used for drying coal slime in a gas oxidation furnace, these solutions primarily focus on oxygen content control itself and fail to systematically address the technical synergy between emission standard application disputes and oxygen content control. Another patent discloses a method for recycling waste heat from sintering flue gas, which preheats materials by mixing high-temperature flue gas and slowly cooled waste gas, but its application scenario is the sintering process and does not address emission standard compliance issues in the drying process. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention proposes the following technical solutions:

[0007] A device for controlling the oxygen content of exhaust gas from a heating furnace drying process includes an insulated chamber, in which a heating furnace and a drying chamber are installed. A control device is installed on the outside of the insulated chamber, and an exhaust pipe, a gas purification module, an exhaust pipe, and a fan are installed on the outside of the insulated chamber. The air volume regulation system in the control device is used to receive signals from an oxygen content monitor.

[0008] Furthermore, the exhaust pipe is used to receive the exhaust gas discharged from the drying chamber. A heat exchanger is provided between the exhaust pipe and the gas purification module. The heat exchanger is used to absorb and transfer the heat in the exhaust gas to other locations. The exhaust gas after passing through the heat exchanger enters the gas purification module for drying exhaust gas treatment. The drying exhaust gas treatment methods in the gas purification module include multiple treatment methods such as HEPA filter to remove dust, activated carbon adsorption of VOCs, hot air desorption, and catalytic combustion degradation. The exhaust pipe is connected to the exhaust port of the gas purification module, and the filtered exhaust gas in the gas purification module is discharged through the exhaust pipe.

[0009] Furthermore, a mixing chamber is fixedly installed at one end of the exhaust pipe, and a fan is installed on the connecting pipe between the exhaust pipe and the mixing chamber. The fan is used to drive external gas into the mixing chamber. An air inlet pipe is fixedly installed at the other end of the mixing chamber. The heat exchanger transfers heat to the air inlet pipe. After the gas in the mixing chamber is preheated by the heat exchanger in the air inlet pipe, the hot air enters the heating furnace in the insulated chamber and mixes with the combustibles for combustion.

[0010] Furthermore, the exhaust pipe includes a main exhaust pipe and a return pipe. One end of the main exhaust pipe is connected to the outlet of the gas purification module, and the other end of the main exhaust pipe is fixedly equipped with an exhaust port. The main exhaust pipe and the return pipe are fixedly connected, forming a three-way connecting pipe. The return pipe is the connecting pipe between the exhaust pipe and the mixing box, and its fan is fixed outside the return pipe. The outlet of the fan is located in the middle of the return pipe.

[0011] Furthermore, an oxygen content monitor is installed inside the exhaust port, and the oxygen content monitor is also installed in the drying chamber. A reflux valve motor is installed at the connection between the reflux pipe and the main exhaust pipe. A reflux valve plate is rotatably mounted on the reflux valve motor, and the reflux valve plate rotates within a range of 85 degrees on the reflux valve motor.

[0012] Furthermore, the return valve plate is located inside the main exhaust pipe. When the return valve plate is in contact with the inner wall of the main exhaust pipe (parallel to the inner wall of the main exhaust pipe), it can be considered to be in a closed state. At this time, the return valve plate will block one end of the return pipe. After the return valve plate rotates, it opens the connection channel between the return pipe and the main exhaust pipe, and can be considered to be in an open state. At this time, some of the exhaust gas in the main exhaust pipe will enter the return pipe. The larger the rotation angle of the return valve plate, the more exhaust gas enters the return pipe from the main exhaust pipe. The return valve plate is driven by the return valve motor to rotate at a fixed angle.

[0013] Furthermore, the heat exchanger includes a medium liquid, a hot gas box, and a heating tube core. Multiple main heat exchange tubes and multiple auxiliary heat exchange tubes are arranged inside the hot gas box. A liquid exchange chamber is provided inside the hot gas box. One end of each of the main and auxiliary heat exchange tubes is located within the liquid exchange chamber. An inlet chamber is located at the end of the hot gas box furthest from the liquid exchange chamber. One end of each auxiliary heat exchange tube is located within the inlet chamber. An outlet chamber is located between the hot gas box and the liquid exchange chamber. One end of each main heat exchange tube is located within the outlet chamber.

[0014] Furthermore, the heating element is disposed on the inner wall of the air inlet pipe, and the heating element is composed of multiple corrugated pipes. The medium liquid flows inside the corrugated pipes, and the gas passing through the air inlet pipe flows outside the corrugated pipes.

[0015] Furthermore, a liquid outlet pipe is fixedly installed at one end of the heating tube core, and one end of the liquid outlet pipe is connected to the liquid inlet chamber. A liquid inlet pipe is fixedly installed at the other end of the heating tube core, and the liquid inlet pipe is fixedly connected to the liquid outlet chamber. A liquid exchange pump is installed on the liquid inlet pipe, and the liquid exchange pump is used to drive the medium liquid in the heat exchanger to circulate.

[0016] Furthermore, the mixing chamber includes a mixing cylinder and an agitator rod. The agitator rod is fixed at one end of the mixing cylinder connected to the exhaust pipe. The agitator rod is provided with multiple mixing blades. The bottom of the mixing cylinder is provided with an airflow guiding arc surface. After the gas driven by the fan and the exhaust gas in the exhaust pipe enter the mixing chamber, they collide with the agitator rod to mix the gas.

[0017] Furthermore, this invention also proposes a method for controlling the oxygen content of drying exhaust gas from a heating furnace, comprising the following steps:

[0018] S1. The oxygen content of the exhaust gas is monitored by the oxygen content monitor at the exhaust port and the oxygen content monitor in the drying chamber. The oxygen content data obtained by the two oxygen content monitors is transmitted to the air volume regulation system.

[0019] S2. When the oxygen content data measured by the oxygen content monitor exceeds the limit, the air volume regulation system starts the return valve motor.

[0020] S3. The motor controls and drives the return valve plate to control the proportion of exhaust gas return. The exhaust gas and the gas driven by the fan are mixed in the mixing box and then enter the intake pipe.

[0021] S4. The heat exchanger in the intake pipe preheats the mixed gas, and the preheated gas enters the heating furnace to mix with the fuel gas.

[0022] S5. The high-temperature exhaust gas generated in the heating furnace enters the drying chamber, and then the drying exhaust gas enters the heat exchanger and gas purification module in sequence for heat recovery and gas treatment.

[0023] S6. The exhaust gas is then discharged from this device through the exhaust port, and the oxygen content monitor at the exhaust port monitors the oxygen content to check whether the oxygen content of the discharged exhaust gas is between 13% and 14%.

[0024] S6. If the oxygen content monitored by the oxygen content monitor in the drying chamber in step 5 exceeds 14%, then repeat step S2.

[0025] S7. Once the two oxygen content monitors at the exhaust port and inside the drying chamber are qualified, the air volume regulation system can operate stably.

[0026] The advantages of this invention compared to the prior art are:

[0027] (1) This device, through the reflux pipe set at the exhaust port, mixes part of the low-temperature waste gas with fresh air and then re-introduces it into the intake pipe. The reflux ratio is controlled by the reflux controller to keep the oxygen content of the drying hot air stable below 14%.

[0028] (2) This application uses an air volume regulation system to receive signals from the oxygen content monitors at the exhaust port and the drying chamber, monitors the oxygen content of the exhaust gas in real time, and links the air volume regulation system to achieve closed-loop control.

[0029] (3) This application collects the residual heat in the exhaust gas and uses it to preheat fresh air through a medium transfer method, thereby reducing heating energy consumption by 10% to 15%. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall operation of the present invention.

[0031] Figure 2 This is a schematic diagram of the insulation chamber structure of the present invention.

[0032] Figure 3 This is a schematic diagram of the air outlet pipe structure of the present invention.

[0033] Figure 4 This is a schematic diagram of the intake pipe structure of the present invention.

[0034] Figure 5 This is a cross-sectional structural diagram of the outlet pipe, heat exchanger, exhaust pipe, mixing box, and inlet pipe of the present invention.

[0035] Figure 6 for Figure 5 Enlarged view of a portion of point A in the middle.

[0036] Figure 7 This is a cross-sectional structural diagram of the heat exchanger, mixing box, and inlet pipe of the present invention.

[0037] Figure 8 This is a cross-sectional structural diagram of the intake pipe and mixing chamber of the present invention.

[0038] Figure 9 This is a schematic diagram of the heat exchanger structure of the present invention.

[0039] Figure reference numerals: 10-Insulation chamber; 20-Control device; 31-Outlet pipe; 32-Heat exchanger; 321-Hot gas box; 322-Main heat exchange tube; 323-Secondary heat exchange tube; 324-Liquid exchange chamber; 325-Outlet chamber; 326-Liquid exchange pump; 327-Inlet pipe; 328-Heating core; 329-Outlet pipe; 330-Inlet chamber; 33-Gas purification module; 34-Exhaust pipe; 341-Main exhaust pipe; 342-Return valve motor; 343-Return valve plate; 344-Exhaust port; 345-Return pipe; 35-Fan; 36-Mixing box; 361-Mixing cylinder; 362-Agitator rod; 37-Inlet pipe. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for explaining the invention and are not intended to limit the invention.

[0041] Example 1:

[0042] This embodiment discloses a device for controlling the oxygen content of drying exhaust gas from a heating furnace, specifically as follows: Figures 1 to 5 As shown, it includes an insulated chamber 10, which is equipped with a heating furnace and a drying chamber. The heating furnace is used to provide high-temperature gas to the drying chamber. In use, the gas that has been burned in the heating furnace is directly transported to the drying chamber. A control device 20 is provided on the outside of the insulated chamber 10, and an exhaust gas oxygen content control device is provided on the outside of the insulated chamber 10.

[0043] The waste gas oxygen content control device includes an outlet pipe 31, a gas purification module 33, an exhaust pipe 34, and a fan 35. The outlet pipe 31 is connected to the drying chamber and is used to receive the waste gas discharged from the drying chamber. A heat exchanger 32 is installed between the outlet pipe 31 and the gas purification module 33. The heat exchanger 32 is used to absorb heat from the waste gas and transfer it to other locations. The waste gas after passing through the heat exchanger 32 enters the gas purification module 33 for drying waste gas treatment. The drying waste gas treatment methods in the gas purification module 33 include multiple treatment methods such as HEPA filter dust removal, activated carbon adsorption of VOCs, hot air desorption, and catalytic combustion degradation. In this configuration, the exhaust pipe 34 is connected to the outlet of the gas purification module 33. The filtered exhaust gas in the gas purification module 33 is discharged through the exhaust pipe 34. A mixing chamber 36 is fixedly installed at one end of the exhaust pipe 34. A fan 35 is installed on the connecting pipe between the exhaust pipe 34 and the mixing chamber 36. The fan 35 is used to drive external gas into the mixing chamber 36. An inlet pipe 37 is fixedly installed at the other end of the mixing chamber 36. The heat exchanger 32 transfers heat to the inlet pipe 37. After the gas in the mixing chamber 36 is preheated by the heat exchanger 32 in the inlet pipe 37, the hot air enters the heating furnace in the insulated chamber 10 and mixes with the combustible material for combustion.

[0044] Example 2:

[0045] This embodiment further elaborates on the heat exchanger 32 based on Embodiment 1, specifically as follows: Figures 1 to 9 As shown, the heat exchanger 32 includes a medium liquid, a hot gas box 321, and a heating tube core 328. Multiple main heat exchange tubes 322 and multiple auxiliary heat exchange tubes 323 are arranged inside the hot gas box 321. The main heat exchange tubes 322 and auxiliary heat exchange tubes 323 are distributed with a fixed gap. A liquid exchange chamber 324 is provided inside the hot gas box 321. One end of each of the main heat exchange tubes 322 and auxiliary heat exchange tubes 323 is located within the liquid exchange chamber 324. A liquid inlet chamber 330 is provided at the end of the hot gas box 321 away from the liquid exchange chamber 324. One end of each auxiliary heat exchange tube 323 is located within the liquid inlet chamber 330. A liquid outlet chamber 325 is provided between the hot gas box 321 and the liquid exchange chamber 324. One end of each main heat exchange tube 322 is located within the liquid outlet chamber 325.

[0046] The heating element 328 is disposed on the inner wall of the air inlet pipe 37. The heating element 328 is used to heat the gas passing through the air inlet pipe 37. The heating element 328 is composed of multiple corrugated pipes. The medium liquid flows inside the corrugated pipes, while the gas passing through the air inlet pipe 37 flows outside the corrugated pipes. One end of the heating element 328 is fixedly installed with an outlet pipe 329, one end of which is connected to the liquid inlet chamber 330. The other end of the heating element 328 is fixedly installed with an inlet pipe 327, which is fixedly connected to the liquid outlet chamber 325. A liquid exchange pump 326 is disposed on the inlet pipe 327. The liquid exchange pump 326 is used to drive the medium liquid in the heat exchanger 32 to circulate. The liquid exchange pump 326 is driven to rotate by an external circulation motor.

[0047] The medium liquid in the heat exchanger 32 is used to transfer heat from the hot gas box 321 to the inlet pipe 37. The medium liquid in the heat exchanger 32 is driven by the liquid exchange pump 326 to first enter the heating tube core 328. At this time, the medium liquid entering the heating tube core 328 through the liquid inlet pipe 327 carries heat. After the medium liquid exchanges heat with the gas in the inlet pipe 37 through the heating tube core 328, it enters the liquid outlet pipe 329. Then the medium liquid flows out through the liquid outlet pipe 329. The medium liquid enters the inlet chamber 330 and then enters the liquid exchange chamber 324 through the auxiliary heat exchange tube 323. After that, the medium liquid in the liquid exchange chamber 324 enters the outlet chamber 325 through the main heat exchange tube 322. When the medium liquid moves in the main heat exchange tube 322 and the auxiliary heat exchange tube 323, the medium liquid will raise its own temperature through the high temperature exhaust gas in the hot gas box 321, and then be transported to the heating tube core 328 by the liquid exchange pump 326.

[0048] Example 3:

[0049] This embodiment further elaborates on the exhaust pipe 34 based on Embodiment 1, specifically as follows: Figures 4 to 6 As shown, the exhaust pipe 34 includes a main exhaust pipe 341 and a return pipe 345. One end of the main exhaust pipe 341 is connected to the outlet of the gas purification module 33, and the other end of the main exhaust pipe 341 is fixedly installed with an exhaust port 344. The main exhaust pipe 341 and the return pipe 345 are fixedly connected, and the main exhaust pipe 341 and the return pipe 345 form a three-way connecting pipe. The exhaust gas flowing out of the main exhaust pipe 341 is directly discharged to the outside of this device through the exhaust port 344, while the exhaust gas flowing out of the main exhaust pipe 341 enters the mixing box 36 for reuse through the return pipe 345. The return pipe 345 is the connecting pipe between the exhaust pipe 34 and the mixing box 36. Its fan 35 is fixed on the outside of the return pipe 345, and the outlet of the fan 35 is located in the middle of the return pipe 345.

[0050] An oxygen content monitor is installed inside the exhaust port 344. The oxygen content monitor is also installed inside the drying chamber. A reflux valve motor 342 is installed at the connection between the reflux pipe 345 and the main exhaust pipe 341. A reflux valve plate 343 is rotatably mounted on the reflux valve motor 342. The reflux valve plate 343 rotates 85 degrees on the reflux valve motor 342. The reflux valve plate 343 is located inside the main exhaust pipe 341. When the reflux valve plate 343 is in contact with the inner wall of the main exhaust pipe 341 (parallel to the inner wall of the main exhaust pipe 341), it can be considered as a reflux valve plate 343. When the return valve plate 343 is in the closed state, it will block one end of the return pipe 345. After the return valve plate 343 rotates, it opens the connection channel between the return pipe 345 and the main exhaust pipe 341. At this time, the return valve plate 343 can be regarded as being in the open state. At this time, some of the exhaust gas in the main exhaust pipe 341 will enter the return pipe 345. The larger the rotation angle of the return valve plate 343, the more exhaust gas enters the return pipe 345 from the main exhaust pipe 341. The return valve plate 343 is driven by the return valve motor 342 to rotate at a fixed angle.

[0051] During use, the exhaust gas, after being filtered by the gas purification module 33, enters the main exhaust pipe 341. If the channel between the return pipe 345 and the main exhaust pipe 341 is not open, the exhaust gas will be discharged directly from the device through the main exhaust pipe 341 and the exhaust port 344. If the return valve plate 343 is driven to rotate by the return pipe 345, the channel between the return pipe 345 and the main exhaust pipe 341 will be opened, and some of the exhaust gas will enter the mixing box 36 through the return pipe 345. The amount of exhaust gas entering the return pipe 345 is determined by the rotation angle of the return valve plate 343.

[0052] Example 4:

[0053] This embodiment further elaborates on the mixing chamber 36 based on Embodiment 1, specifically as follows: Figure 4 , Figure 5 , Figure 7 , Figure 8 As shown, the mixing chamber 36 includes a mixing cylinder 361 and an agitator 362. The agitator 362 is fixed at one end of the mixing cylinder 361 connected to the exhaust pipe 34. The agitator 362 is provided with multiple mixing blades. The bottom of the mixing cylinder 361 is provided with an airflow guiding arc surface. The gas driven by the fan 35 and the exhaust gas in the exhaust pipe 34 enter the mixing chamber 36 and collide with the agitator 362 to mix the gas. After being guided by the mixing blades on the agitator 362, the gas forms a cyclone in the mixing cylinder 361. The mixed gas then flows from the airflow guiding arc surface at the bottom of the mixing cylinder 361 to the inlet pipe 37. After being heated by the heat exchanger 32 in the inlet pipe 37, it enters the heating furnace to mix with the fuel gas for combustion.

[0054] The control device 20 is used to control and adjust the oxygen content control device of the exhaust gas. The air volume adjustment system in the control device 20 is used to receive the signal from the oxygen content monitor. Then, the air volume adjustment system is used to synchronously control the start and stop of the fan 35 and the return valve motor 342. The air volume adjustment system can also be linked to control the combustion pipe valve in the heating furnace.

[0055] This invention also proposes a method for controlling the oxygen content of drying exhaust gas from a heating furnace, comprising the following steps:

[0056] S1. The oxygen content of the exhaust gas is monitored by the oxygen content monitor at the exhaust port 344 and the oxygen content monitor in the drying room. The oxygen content data obtained by the two oxygen content monitors is transmitted to the air volume regulation system.

[0057] S2. When the oxygen content data measured by the oxygen content monitor exceeds the limit data, the air volume regulation system starts the return valve motor 342.

[0058] S3. The return valve motor 342 controls and drives the return valve plate 343 to control the proportion of exhaust gas return. The exhaust gas and the gas driven by the fan 35 are mixed in the mixing box 36 and then enter the intake pipe 37.

[0059] S4. The heat exchanger 32 in the inlet pipe 37 preheats the mixed gas, and the preheated gas enters the heating furnace to mix with the fuel gas.

[0060] S5. The high-temperature exhaust gas generated in the heating furnace enters the drying chamber, and then the drying exhaust gas enters the heat exchanger 32 and the gas purification module 33 in sequence for heat recovery and gas treatment.

[0061] S6. The exhaust gas is then discharged from this device through exhaust port 344. The oxygen content monitor at exhaust port 344 monitors the oxygen content to check whether the oxygen content of the discharged exhaust gas is between 13% and 14%.

[0062] S6. If the oxygen content monitored by the oxygen content monitor in the drying chamber in step 5 exceeds 14%, then repeat step S2.

[0063] S7. Once the oxygen content monitors at the exhaust port 344 and the two oxygen content monitors inside the drying chamber are qualified, the air volume regulation system can operate stably.

[0064] Working Principle: At the start of operation, the blower 35 provides oxygen for combustion in the heating furnace. The blower 35 directly draws gas from the environment and inputs it into the mixing box 36. The gas then enters the heating furnace through the inlet pipe 37. In the heating furnace, the gas mixes with fuel gas (generally natural gas) and burns. The resulting gas is high-temperature exhaust gas, which is directly used for heating in the drying chamber. The drying exhaust gas, after being used in the drying chamber, then enters the exhaust gas oxygen content control device through the outlet pipe 31. The drying exhaust gas first passes through… The gas is cooled by heat exchanger 32, which also transfers heat from the drying exhaust gas to the inlet pipe 37 to preheat the newly added gas. After passing through heat exchanger 32, the exhaust gas is filtered by gas purification module 33 before entering exhaust pipe 34. Initially, the exhaust gas entering exhaust pipe 34 is discharged directly through exhaust port 344. When the exhaust gas is detected by an oxygen content monitor at exhaust port 344, if the oxygen content in the exhaust gas does not meet the "Emission Standard of Air Pollutants for Industrial Furnaces and Kilns," then... The flow regulation system activates the return valve motor 342, calculating based on the specific oxygen content and the intake specific gravity of the blower 35. Then, the return valve motor 342 drives the return valve plate 343 to rotate by the calculated angle. After the return valve plate 343 rotates 85 degrees, it reaches the maximum waste gas recovery state of the device. In this state, 60%–85% of the waste gas entering the exhaust pipe 34 is recovered and mixed in the mixing chamber 36. The recovered waste gas then mixes with the fresh gas from the blower 35 through the mixing chamber 36. The mixed gas then carries… Some of the exhaust gas enters the heating furnace, and then the exhaust gas flowing out of the heating furnace and drying chamber will pass through the heat exchanger 32 and the gas purification module 33 before entering the exhaust pipe 34. When the oxygen content of the gas discharged from the exhaust pipe 34 is detected by the oxygen content monitor, the oxygen content of the exhaust gas will be reduced, so that the exhaust gas meets the national standard. As the rotation angle of the return valve plate 343 is larger, the oxygen content of the exhaust gas discharged from the exhaust pipe 34 is lower. However, it is necessary to pay attention to whether there is enough oxygen for the combustion in the combustion chamber during use.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. A device for controlling the oxygen content of exhaust gas from a heating furnace drying process, comprising an insulated chamber (10), wherein a heating furnace and a drying chamber are disposed within the insulated chamber (10), characterized in that: A control device (20) is provided on the outside of the insulated room (10), and the air volume regulation system in the control device (20) is used to receive the signal from the oxygen content monitor; It also includes an exhaust pipe (31), a gas purification module (33), an exhaust pipe (34), and a fan (35) installed outside the insulation chamber (10). The exhaust pipe (31) is used to receive the exhaust gas discharged from the drying chamber. A heat exchanger (32) is installed between the exhaust pipe (31) and the gas purification module (33). The exhaust gas after passing through the heat exchanger (32) enters the gas purification module (33) for drying exhaust gas treatment. The exhaust pipe (34) is connected to the exhaust port of the gas purification module (33). The exhaust gas filtered in the gas purification module (33) is discharged through the exhaust pipe (34). One end of the exhaust pipe (34) is fixedly installed with a mixing box (36), and the fan (35) is set on the connecting pipe between the exhaust pipe (34) and the mixing box (36). The other end of the mixing box (36) is fixedly installed with an air inlet pipe (37). The heat exchanger (32) delivers heat to the air inlet pipe (37). After the gas in the mixing box (36) is preheated by the heat exchanger (32) in the air inlet pipe (37), the hot air enters the heating furnace in the insulated chamber (10) and mixes with the combustibles for combustion.

2. The method for controlling the oxygen content of drying exhaust gas in a heating furnace according to claim 1, characterized in that: The exhaust pipe (34) includes a main exhaust pipe (341) and a return pipe (345). One end of the main exhaust pipe (341) is connected to the outlet of the gas purification module (33), and the other end of the main exhaust pipe (341) is fixedly installed with an exhaust port (344). The main exhaust pipe (341) and the return pipe (345) are fixedly connected. The main exhaust pipe (341) and the return pipe (345) form a three-way connecting pipe. The return pipe (345) is the connecting pipe between the exhaust pipe (34) and the mixing box (36). An oxygen content monitor is installed inside the exhaust port (344). The oxygen content monitor is also installed in the drying chamber. A reflux valve motor (342) is installed at the connection between the reflux pipe (345) and the main exhaust pipe (341). A reflux valve plate (343) is rotatably mounted on the reflux valve motor (342). The reflux valve plate (343) rotates within 85 degrees on the reflux valve motor (342).

3. The method for controlling the oxygen content of drying exhaust gas in a heating furnace according to claim 2, characterized in that: The return valve plate (343) is located inside the main exhaust pipe (341). When the return valve plate (343) is in contact with the inner wall of the main exhaust pipe (341), it will block one end of the return pipe (345). After the return valve plate (343) rotates, it opens the connection channel between the return pipe (345) and the main exhaust pipe (341). The greater the rotation angle of the return valve plate (343), the more exhaust gas enters the return pipe (345) from the main exhaust pipe (341). The return valve plate (343) is driven by the return valve motor (342) to rotate at a fixed angle.

4. The method for controlling the oxygen content of drying exhaust gas in a heating furnace according to claim 1, characterized in that: The heat exchanger (32) includes a medium liquid, a hot gas box (321), and a heating tube core (328). The hot gas box (321) is provided with multiple main heat exchange tubes (322) and multiple auxiliary heat exchange tubes (323). The hot gas box (321) is provided with a liquid exchange chamber (324). One end of each of the main heat exchange tubes (322) and auxiliary heat exchange tubes (323) is located in the liquid exchange chamber (324). The end of the hot gas box (321) away from the liquid exchange chamber (324) is provided with a liquid inlet chamber (330). One end of each auxiliary heat exchange tube (323) is located in the liquid inlet chamber (330). A liquid outlet chamber (325) is provided between the hot gas box (321) and the liquid exchange chamber (324). One end of each main heat exchange tube (322) is located in the liquid outlet chamber (325).

5. The method for controlling the oxygen content of drying exhaust gas in a heating furnace according to claim 1, characterized in that: The heating core (328) is disposed on the inner wall of the air inlet pipe (37). The heating core (328) is composed of multiple corrugated pipes. The medium liquid flows inside the corrugated pipes, and the gas passing through the air inlet pipe (37) flows outside the corrugated pipes.

6. The method for controlling the oxygen content of drying exhaust gas in a heating furnace according to claim 1, characterized in that: One end of the heating core (328) is fixedly installed with an outlet pipe (329), one end of the outlet pipe (329) is connected to the inlet chamber (330), and the other end of the heating core (328) is fixedly installed with an inlet pipe (327), the inlet pipe (327) is fixedly connected to the outlet chamber (325), and a liquid exchange pump (326) is provided on the inlet pipe (327), the liquid exchange pump (326) is used to drive the medium liquid in the heat exchanger (32) to circulate.

7. The method for controlling the oxygen content of drying exhaust gas in a heating furnace according to claim 1, characterized in that: The mixing chamber (36) includes a mixing cylinder (361) and an agitator (362). The agitator (362) is fixed at one end of the mixing cylinder (361) connected to the exhaust pipe (34). The agitator (362) is provided with multiple mixing blades. The bottom of the mixing cylinder (361) is provided with an airflow guiding arc surface. After the gas driven by the fan (35) and the exhaust gas in the exhaust pipe (34) enter the mixing chamber (36), they collide with the agitator (362) to mix the gas.

8. A method for controlling the oxygen content of drying exhaust gas from a heating furnace according to any one of claims 1-7, characterized in that, Includes the following steps: S1. The oxygen content of the exhaust gas is monitored by the oxygen content monitor at the exhaust port (344) and the oxygen content monitor in the drying room. The oxygen content data obtained by the two oxygen content monitors is transmitted to the air volume regulation system. S2. When the oxygen content data measured by the oxygen content monitor exceeds the limit data, the air volume regulation system starts the return valve motor (342). S3, the return valve motor (342) controls and drives the return valve plate (343) to control the proportion of exhaust gas return. The exhaust gas and the gas driven by the fan (35) are mixed in the mixing box (36) and then enter the intake pipe (37). S4. The heat exchanger (32) in the inlet pipe (37) preheats the mixed gas, and the preheated gas enters the heating furnace to mix with the fuel gas. S5. The high-temperature exhaust gas generated in the heating furnace enters the drying chamber, and then the drying exhaust gas is sequentially entered into the heat exchanger (32) and the gas purification module (33) for heat recovery and gas treatment. S6. The exhaust gas is discharged from this device through the exhaust port (344), and the oxygen content monitor at the exhaust port (344) monitors the oxygen content to check whether the oxygen content of the discharged exhaust gas is between 13% and 14%. S6. If the oxygen content monitored by the oxygen content monitor in the drying chamber in step 5 exceeds 14%, then repeat step S2. S7. Once the two oxygen content monitors at the exhaust port (344) and inside the drying chamber are qualified, the air volume regulation system can operate stably.

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