A Lost Foam Casting Exhaust Gas Purification Module

Abstract

This utility model discloses a lost foam casting exhaust gas purification module, including a module body and an air inlet pipe and an exhaust pipe respectively connected to both sides of the module body. A guide fan is provided inside the exhaust pipe. A water mist spraying device is provided at the top and bottom of the module body, each water mist spraying device including a pressure water storage tank and a fine atomizing nozzle. A dielectric barrier discharge reactor is provided on the side of the water mist spraying device near the exhaust pipe. The dielectric barrier discharge reactor includes electrode connection blocks respectively disposed at the top and bottom, and electrodes connected to the electrode connection blocks. A packed bed is provided between the two electrode connection blocks and coupled to the electrodes. This design utilizes the dielectric barrier discharge reactor and water mist spraying device within the module. A strong electric field is formed on the surface of the dielectric medium in the packed bed between the two electrodes within the reactor, ionizing gas molecules. These molecules then combine with hydroxyl radicals provided by the water mist to enhance the dielectric barrier discharge reactor's effect on the cracking of benzene compounds in the exhaust gas.

Description

Technical Field

[0001] This utility model relates to the technical field of lost foam casting equipment, and in particular to a module for purifying exhaust gas from lost foam casting. Background Technology

[0002] Lost foam casting uses foam plastic models instead of traditional wooden or metal molds. After being coated with a refractory coating, the model is buried in dry sand, and molten metal is poured in under negative pressure. The model vaporizes and disappears, and the molten metal occupies its space to form the casting. Lost foam casting is suitable for producing castings with complex structures and high precision requirements, mainly in fields such as automobile manufacturing, construction machinery, and rail transportation.

[0003] During the lost foam casting process, high-temperature molten metal (typically >1500℃) comes into contact with the foam model, causing the foam model to undergo a "zipper-like decomposition" at high temperatures. This generates a large amount of small-molecule organic gases. The refractory coating on the model surface (containing organic binders) decomposes at high temperatures, releasing volatile organic compounds (VOCs). These VOCs, along with pollutants such as fumes and SO2 generated during the smelting process, are also released into the waste gas. The composition of this waste gas is complex, mainly including benzene compounds, carbon black, and other inorganic particulate matter. High concentrations of benzene compounds can cause acute poisoning, and benzene is a Group 1 carcinogen, posing a significant threat to the health of workers. Furthermore, direct emissions of this waste gas also have a considerable impact on the environment and ecosystem.

[0004] In existing technologies, the waste gas treatment methods for lost foam casting typically include activated carbon adsorption, UV photolysis oxidation, and plasma methods. These methods all have room for improvement in waste gas removal rates, and their operating costs and energy consumption are relatively high. Therefore, there is a need for a module for purifying lost foam casting waste gas to more effectively remove harmful substances from the waste gas and reduce operating energy consumption. Utility Model Content

[0005] This utility model addresses the technical problem of difficulty in improving the removal efficiency of harmful substances in the exhaust gas generated by lost foam casting. It provides a lost foam casting exhaust gas purification module, including a module body and an air inlet pipe and an exhaust pipe respectively connected to both sides of the module body. The exhaust pipe is provided with a guide fan on its inner side. A water mist spraying device is provided at the top and bottom of the module body. The water mist spraying device includes a pressure water storage tank and a fine atomizing nozzle. The pressure water storage tank is fixedly connected to the inner wall of the module body.

[0006] On the side of the water mist spraying device near the exhaust pipe, a dielectric barrier discharge reactor is provided. The dielectric barrier discharge reactor includes electrode connection blocks respectively disposed at the top and bottom, and electrodes connected to the electrode connection blocks. A packed bed is provided between the two electrode connection blocks and coupled to the electrodes.

[0007] Preferably, in the above technical solution, the electrodes are serrated and uniformly distributed in an array, with the distance between the serrated tips being less than 1 mm.

[0008] Preferably, in the above technical solution, the upper part of the electrode is covered with a dielectric material, and the thickness of the dielectric material is 0.5–1 mm.

[0009] Preferably, in the above technical solution, the interior of the filling bed is provided with a plurality of quartz beads, and the plurality of quartz beads are stacked to form a porous structure.

[0010] Preferably, in the above technical solution, the diameter of the quartz beads is 4mm.

[0011] Preferably, in the above technical solution, a partition is further provided at the bottom of the module body, the partition is located on the side close to the air inlet pipe, and the partition and the inner wall of the module body form a water tank.

[0012] Preferably, in the above technical solution, a ceramic filter plate is connected to the top of the partition, and the pore size of the ceramic filter plate is 5–10 μm.

[0013] Preferably, in the above technical solution, a drain pipe is connected to the bottom of the module body, the drain pipe is located in the center of the water tank and is connected to the water tank, and a drain valve is provided on the drain pipe.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] This invention features a dielectric barrier discharge reactor within a module. A strong electric field is formed on the surface of the dielectric bed between the two electrodes inside the reactor, ionizing gas molecules and generating high-energy electrons. Under the action of a high-voltage electric field and high-frequency alternating current, these high-energy electrons collide with benzene molecules in the exhaust gas and transfer energy, causing them to decompose into CO2 and H2O.

[0016] This invention features a water mist spraying device installed before the dielectric barrier discharge reactor. This device uses a pressurized water storage tank to spray a certain amount of water mist from a fine atomizing nozzle, thereby providing more hydroxyl radicals to the dielectric barrier discharge reactor during operation and improving the reactor's ability to crack benzene compounds in the waste gas.

[0017] The ceramic filter plate and water tank at the front end of the module of this utility model filter out particulate matter such as smoke and carbon black generated during the lost foam casting process. Larger smoke particles are blocked by the ceramic filter plate and fall into the water tank, preventing them from affecting the purification process. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of a lost foam casting exhaust gas purification module according to the present invention;

[0019] Figure 2 This is a schematic diagram of the internal structure of a lost foam casting exhaust gas purification module according to the present invention;

[0020] Figure 3 This is a schematic diagram of the electrode and dielectric structure in a lost foam casting exhaust gas purification module of this utility model;

[0021] Figure 4 This is a schematic diagram of the internal structure of the filling bed in a lost foam casting waste gas purification module of this utility model.

[0022] Explanation of key figure labels:

[0023] 1-Module body, 2-Ceramic filter plate, 3-Water mist spraying device, 4-Water tank, 5-Guide fan, 6-Dielectric barrier discharge reactor, 11-Air inlet pipe, 12-Exhaust pipe, 13-Drain pipe, 14-Baffle, 31-Pressure water storage tank, 32-Fine atomizing nozzle, 61-Electrode connection block, 62-Electrode, 63-Dielectric, 65-Burnt bed, 131-Drain valve, 651-Quartz bead. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0025] like Figures 1-4As shown, this utility model discloses a lost foam casting exhaust gas purification module, comprising a module body 1 and an air inlet pipe 11 and an exhaust pipe 12 respectively connected to both sides of the module body 1. Both the air inlet pipe 11 and the exhaust pipe 12 have installation interfaces on their outer sides, allowing the purification module to be directly installed on an exhaust gas collection pipe for secondary treatment. A guide fan 5 is provided on the inner side of the exhaust pipe 12. A water mist spraying device 3 is provided at the top and bottom of the module body 1. The water mist spraying device 3 includes a pressure water storage tank 31 and a fine atomizing nozzle 32. The pressure water storage tank 31 is fixedly connected to the inner wall of the module body 1. The atomization angle of the fine atomizing nozzle 32 is <45°, and the water mist particle size formed by the fine atomizing nozzle 32 is 60-80μm. On the side of the water mist spraying device 3 near the exhaust pipe 12, a dielectric barrier discharge reactor 6 is provided. The dielectric barrier discharge reactor 6 includes electrode connecting blocks 61 respectively disposed at the top and bottom, and electrodes 62 connected to the electrode connecting blocks 61. A packed bed 65 is provided between the two electrode connecting blocks 61 and coupled to the electrodes 62. The electrodes 62 are serrated and uniformly distributed in an array, with the distance between the serrated tips less than 1 mm. The upper part of the electrodes 62 is covered with a dielectric 63, the thickness of which is 0.5–1 mm. The serrated electrodes 62 can accumulate charge at the tips by utilizing the radius of curvature effect, thereby increasing the intensity of the local electric field. The smaller the gap between the electrodes 62, the higher the electric field intensity at the same voltage. Reducing the gap between the electrodes 62 can reduce the magnitude of the input voltage while ensuring the electric field strength. A 0.5–1 mm thick dielectric 63 is applied to electrode 62 to enhance the local electric field and reduce voltage division, concentrating more electric field energy in the gas gaps, thereby improving the electric field strength and the cracking effect on benzene compounds in the waste gas. The packed bed 65 contains multiple quartz beads 651, which are stacked to form a porous structure. Each quartz bead 651 has a diameter of 4 mm. The porous structure of the packed bed 65, formed by multiple 4 mm quartz beads 651, significantly increases the contact area between the gas and active particles. The glass beads act as a dielectric barrier layer, inducing a micro-discharge effect under the high-voltage electric field generated by the dielectric barrier discharge reactor 6, creating a strong local electric field in the gaps between the beads to accelerate gas ionization. The porous structure tortuouss the waste gas flow path, increasing the residence time of the gas in the packed bed 65, increasing the probability of reaction between benzene compounds and active free radicals, and thus improving the waste gas removal efficiency. The guide fan 5 installed inside the exhaust pipe 12 can accelerate the gas flow rate in the purification module, allowing the water mist particles generated by the water mist spraying device 3 to enter the packed bed 65 more smoothly. This provides more hydroxyl radicals when the dielectric barrier discharge reactor is working and increases the collision rate of the gas in the packed bed 65, thereby improving the cracking effect of the dielectric barrier discharge reactor on benzene series compounds in the exhaust gas.Its working principle is as follows: The dielectric barrier discharge reactor 6 can form a high-voltage electric field (20kV) and a high-frequency alternating current (10kHz). The gas molecules (such as O2, N2, H2O) between them are ionized, generating high-energy electrons. The high-energy electrons act as "reaction initiators", which collide with benzene molecules (C6H6) and transfer energy, causing their chemical bonds to break. Active free radicals and small molecule fragments undergo a chain reaction to generate intermediate products such as formic acid and carbon monoxide (CO). These intermediate products combine with the active sites on the surface of quartz beads 651, adsorbing free radicals and benzene fragments, reducing the reaction activation energy, and accelerating the oxidation process.

[0026] It should be further explained that a partition 14 is also provided at the bottom of the module body 1. The partition 14 is located on the side near the air inlet pipe 11, and the partition 14 and the inner wall of the module body 1 form a water tank 4. A ceramic filter plate 2 is connected to the top of the partition 14, and the pore size of the ceramic filter plate 2 is 5–10 μm. A drain pipe 13 is connected to the bottom of the module body 1. The drain pipe 13 is located in the center of the water tank 4 and is connected to the water tank 4. A drain valve 131 is provided on the drain pipe 13. The ceramic filter plate 2 can filter out particulate impurities such as soot and carbon black in the exhaust gas. Larger particulate impurities enter the water tank 4 under the action of gravity, dissolve in water, and are collected and treated uniformly through the drain pipe 13. This prevents particulate impurities such as soot and carbon black in the exhaust gas from entering the gaps in the packed bed 65, causing blockage of the packed bed 65, which would make it difficult for decomposable substances in the exhaust gas to be decomposed smoothly, thereby affecting the removal efficiency of pollutants such as benzene series compounds.

[0027] This invention utilizes a dielectric barrier discharge reactor within a module. This reactor creates a strong electric field on the surface of the packed bed medium between the two electrodes, ionizing gas molecules and generating high-energy electrons. Under the influence of a high-voltage electric field and high-frequency alternating current, these high-energy electrons collide with benzene molecules in the waste gas, transferring energy and causing them to decompose into CO2 and H2O. A water mist spraying device at the front end of the dielectric barrier discharge reactor uses a pressurized water storage tank to spray a certain amount of water mist from fine atomizing nozzles. This provides more hydroxyl radicals to the dielectric barrier discharge reactor during operation, enhancing its decomposition effect on benzene compounds in the waste gas. A ceramic filter plate and water tank at the front end of the module filter out particulate matter such as smoke and carbon black generated during lost foam casting. Larger smoke particles are blocked by the ceramic filter plate and fall into the water tank, preventing them from affecting the purification process. The combined use of the dielectric barrier discharge reactor and water mist spraying device significantly improves the removal efficiency of harmful substances in the waste gas generated during lost foam casting. Compared to traditional activated carbon adsorption or RTO incineration methods, this invention eliminates the risk of secondary pollution.

[0028] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A module for purifying exhaust gas from lost foam casting, characterized in that: The module includes a main body (1) and an air inlet pipe (11) and an exhaust pipe (12) respectively connected to both sides of the main body (1). The exhaust pipe (12) is provided with a guide fan (5) on its inner side. A water mist spraying device (3) is provided at the top and bottom of the main body (1). The water mist spraying device (3) includes a pressure water storage tank (31) and a fine atomizing nozzle (32). The pressure water storage tank (31) is fixedly connected to the inner wall of the main body (1). On the side of the water mist spraying device (3) near the exhaust pipe (12), there is a dielectric barrier discharge reactor (6). The dielectric barrier discharge reactor (6) includes electrode connecting blocks (61) respectively set at the top and bottom, and electrodes (62) connected to the electrode connecting blocks (61). A packed bed (65) is provided between the two electrode connecting blocks (61) and coupled to the electrodes (62).

2. The lost foam gas exhaust purification module of claim 1, wherein: The electrodes (62) are serrated and evenly distributed in an array, with the distance between the serrated tips being less than 1 mm.

3. The lost foam gas exhaust purification module of claim 2, wherein: The upper part of the electrode (62) is covered with a dielectric (63) with a thickness of 0.5–1 mm.

4. The lost foam gas exhaust purification module of claim 1, wherein: The interior of the packed bed (65) is provided with a plurality of quartz beads (651), and the plurality of quartz beads (651) are stacked to form a porous structure.

5. The lost foam gas exhaust purification module of claim 4, wherein: The diameter of the quartz beads (651) is 4 mm.

6. The lost foam gas exhaust purification module of claim 1, wherein: The bottom of the module body (1) is also provided with a partition (14), which is located on the side close to the air inlet pipe (11). The partition (14) and the inner wall of the module body (1) form a water tank (4).

7. The lost foam vent gas purification module of claim 6, wherein: The top of the partition (14) is connected to a ceramic filter plate (2), the pore size of which is 5–10 μm.

8. The lost foam gas exhaust purification module of claim 6, wherein: The bottom of the module body (1) is connected to a drain pipe (13). The drain pipe (13) is located in the center of the water tank (4) and is connected to the water tank (4). A drain valve (131) is provided on the drain pipe (13).

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