Environment-friendly multi-stage heat exchange device for casting waste gas waste heat recovery

Abstract

The invention relates to the technical field of waste heat recovery, in particular to an environment-friendly multi-stage heat exchange device for casting waste gas waste heat recovery, which comprises a smelting furnace, an ingot casting machine, a conveying belt, a waste heat boiler, a gravity settling chamber, a bag-type dust collector and a heat exchanger, the device further comprises a gas collecting hood, a throwing assembly, a desulfurization assembly and a reset assembly, the gravity settling chamber, the desulfurization assembly, the bag-type dust collector and the heat exchanger are sequentially installed at the rear end of the waste heat boiler, the throwing assembly is fixedly installed at the upper end of the ingot casting machine, and when the smelting furnace pours the ingot casting machine, the throwing assembly is driven to drive sulfur powder to move right above the ingot casting machine. Meanwhile, the desulfurization assembly is driven to rotate to increase the desulfurizer spraying aperture, the reset assembly slowly drives the desulfurization assembly to reset after pouring is finished, and the problem that the concentration of SO2 in casting waste gas exceeds the standard is solved in the mode that the throwing assembly is driven to throw sulfur powder during pouring of the smelting furnace and the desulfurization assembly is driven to increase the desulfurizer spraying aperture.

Description

Technical Field

[0001] The present invention relates to the technical field of waste heat recovery, and particularly to an environment-friendly multi-stage heat exchange device for waste heat recovery of casting waste gas. Background Art

[0002] Casting waste gas refers to the mixed gas pollutants released during the casting process from melting, molding, pouring, cooling to cleaning in metal casting production. Its composition is complex, including particulate matter, organic / inorganic gases, heavy metal vapors, etc., and it is one of the main environmental pollution sources in the casting industry.

[0003] A large amount of high-temperature waste gas is generated during the casting process, containing rich heat energy. Through waste heat recovery, this heat energy can be converted into electric energy, heat energy, etc. for production, reducing the dependence on traditional energy and lowering the energy procurement cost. However, a large amount of harmful gases are contained in the casting waste gas, such as trace pollutants like VOCs (styrene, formaldehyde, etc.), SO2, HCl, Hg, and dioxins.

[0004] The existing energy-saving heat exchange device directly enters the radiation-type waste heat boiler with casting waste gas (such as melting flue gas, pouring waste gas) at a high temperature of 800 - 1100°C. At high temperature, VOCs (styrene, formaldehyde, etc.) are completely decomposed into CO2 and H2O. At the same time, the high-pressure steam generated by the flue gas passing through the boiler is used to drive a steam turbine to generate electricity; the flue gas at the outlet of the waste heat boiler (400 - 500°C) will enter the catalytic oxidation reactor, and precious metal catalysts (Pt / Pd) are used to oxidize CO and residual VOCs into harmless substances, and SO2 and HCl are simultaneously removed in the range of 200 - 300°C by continuously injecting Ca(OH)2 plus bag dust removal. At the same time, the heat released by the reaction is used to preheat the combustion-supporting air or process water during the casting process through a plate heat exchanger; finally, the low-temperature waste heat (50 - 150°C) is heated to 80 - 120°C by an absorption heat pump, and after adsorbing trace pollutants such as Hg and dioxins with modified activated carbon (such as doped with MnOx), it is used for heating and hot water supply, realizing the removal of harmful substances while recovering the waste heat of the casting waste gas.

[0005] However, in the ingot casting process of certain specific metals, a large amount of sulfur powder needs to be sprinkled. For example, during the pouring process of Mg liquid, a violent oxidation reaction is likely to occur. To prevent this violent oxidation reaction, sulfur powder is sprinkled during the ingot casting process to form a MgS protective film on the surface of the Mg liquid. This not only isolates oxygen and prevents combustion but also makes the surface of the ingot smooth and dense, improving the subsequent processing performance. However, this will cause the concentration of SO2 in the casting waste gas to increase instantaneously after sprinkling sulfur powder, quickly depleting the Ca(OH)2 used for desulfurization, and then resulting in the excessive concentration of SO2 in the discharged casting waste gas. Spraying more Ca(OH)2 easily causes it to form a paste with the H2O generated by the complete decomposition of VOCs and adsorb on the surface of the cloth bag, reducing the filtration efficiency of the cloth bag filter.

[0006] In the prior art, an emergency spray tower is added after dry desulfurization, and an alkaline solution (such as NaOH solution, limestone slurry, etc.) is sprayed to react with SO2 in the air to prevent the excessive concentration of SO2. However, when spraying the alkaline solution, the moisture in the solution will absorb the heat in the waste gas, resulting in a reduction in the heat energy recovery efficiency.

[0007] Therefore, an environmentally friendly multi-stage heat exchange device for recovering the waste heat of casting waste gas is proposed. Summary of the Invention

[0008] The purpose of the present invention is to provide an environmentally friendly multi-stage heat exchange device for recovering the waste heat of casting waste gas, which solves the problem that the concentration of SO2 in the casting waste gas exceeds the standard due to the instantaneous increase in the concentration of SO2 in the casting waste gas caused by sprinkling sulfur powder during the pouring process of Mg liquid. By driving the sprinkling component to sprinkle sulfur powder when the melting furnace is tilted and driving the desulfurization component to increase the aperture of the sprayed desulfurizer, the excessive concentration of SO2 in the casting waste gas is avoided. After a period of time, the desulfurization component is driven to reset by the reset component, achieving the purpose of avoiding the excessive concentration of SO2 in the casting waste gas and reducing the reduction in the heat energy recovery efficiency at the same time.

[0009] To achieve the above purpose, the present invention provides the following technical solutions:

[0010] An environmentally friendly multi-stage heat exchange device for recovering the waste heat of casting waste gas includes a melting furnace, an ingot casting machine, a conveyor belt, a waste heat boiler, a gravity settling chamber, a bag filter, and a heat exchanger; it also includes a gas collecting hood, a sprinkling component, a desulfurization component, and a reset component. The ingot casting machine and the conveyor belt are sequentially installed on the right side of the melting furnace from left to right. The gas collecting hood is fixedly installed on the upper end of the melting furnace. The waste heat boiler is installed on the right side of the gas collecting hood and is connected to the gas collecting hood. The gravity settling chamber, the desulfurization component, the bag filter, and the heat exchanger are sequentially installed at the rear end of the waste heat boiler from front to back and are interconnected. The sprinkling component is fixedly installed on the upper end of the ingot casting machine;

[0011] When the smelting furnace pours molten magnesium into the ingot casting machine, it drives the sprinkling assembly to move directly above the ingot casting machine. During the movement of the sprinkling assembly, it drives the desulfurization assembly to rotate, increasing the aperture of the desulfurizing agent spray. The reset assembly slowly drives the desulfurization assembly to reset after the pouring is completed.

[0012] Preferably, the sprinkling assembly includes a connecting rod, a sprinkling plate, a mounting plate, a storage bin, and a fixing rod. The connecting rod is rotatably installed on the side of the smelting furnace close to the ingot casting machine. The sprinkling plate is rotatably installed at the other end of the connecting rod. The mounting plate is fixedly installed at the upper end of the ingot casting machine. The sprinkling plate is slidably installed on the mounting plate. The fixing rod is fixedly installed above the ingot casting machine. The storage bin is rotatably installed on the fixing rod. A pushing plate is installed at one end of the sprinkling plate, and a mating plate is installed at the lower end of the storage bin. The right side of the pushing plate is in contact with the left side of the mating plate.

[0013] In the above solution, when the smelting furnace is tilted, the right end of the smelting furnace will push the connecting rod forward. At this time, it will drive the sprinkling plate to move to the right. At this time, the pushing plate installed at the rear end of the sprinkling plate will push the mating plate at the lower end of the storage bin. At this time, since the storage bin is fixed on the fixing rod, the storage bin will rotate around the fixing rod, causing the sulfur powder in the storage bin to fall onto the sprinkling plate. When the smelting furnace returns, the pushing plate will move the sulfur powder poured on the sprinkling plate upward above the ingot casting machine and enter the ingot casting machine through the gaps on the sprinkling plate. Through this solution, it can replace the process of manually sprinkling sulfur powder into the ingot casting machine in the prior art and prevent the risk of a large amount of SO2 generated when sprinkling sulfur powder from being inhaled by the staff.

[0014] Preferably, the desulfurization assembly includes a powder bin, a spraying chamber, a spray head, an air inlet pipe, and a desulfurization chamber. One end of the desulfurization chamber is connected to the gravity settling chamber, and the other end of the desulfurization chamber is connected to the bag filter. The spraying chamber is fixedly installed inside the desulfurization chamber. The powder bin is rotatably connected to one side of the spraying chamber. A plurality of air inlet pipes are circumferentially arrayed and communicated to the inside of the spraying chamber. The air inlet pipes penetrate through the desulfurization chamber. A plurality of spray heads are circumferentially arrayed inside the spraying chamber, and the positions of the spray heads and the air inlet pipes are on the same axis. An outlet hole is opened on the adjacent side of the powder bin and the spraying chamber, and the outlet hole communicates the powder bin with the spraying chamber.

[0015] In the above solution, by introducing high-pressure gas into the air inlet pipe and spraying it out from the spray head, during this process, when the high-pressure air flow passes through the powder bin, it will drive the internal desulfurizing agent into the spraying chamber through the outlet hole and be sprayed into the desulfurization chamber together with the high-pressure air flow from the spraying chamber to react with SO2 in the waste gas, realizing the purification of the waste gas. And the outlet hole between the powder bin and the spraying chamber is not in a completely matching state when sulfur powder is not sprinkled, that is, the aperture does not reach the maximum value. Through this solution, dry desulfurization can be achieved, ensuring the removal of SO2 while avoiding heat loss caused by the absorption of heat in the waste gas by the moisture in the solution in the traditional method of spraying alkaline solution.

[0016] Preferably, a driven wheel is fixedly installed outside the powder bin, a driving wheel is installed at the right end of the storage bin, and the upper end surface of the driving wheel is in contact with the lower end surface of the driven wheel.

[0017] In the above solution, when the storage bin rotates around the fixed rod, the driving wheel installed at the right end of the storage bin will push the driven wheel to rotate. At this time, since the powder bin rotates while the spraying cavity remains unchanged, the aperture of the discharge hole between the powder bin and the spraying cavity will increase. At this time, more desulfurizing agent will be ejected, ensuring the complete removal of SO2 in the waste gas. Through this solution, it can be realized that when sprinkling sulfur powder, the dosage of the sprinkled desulfurizing agent is automatically increased without manual monitoring, greatly increasing the convenience of waste gas recovery.

[0018] Preferably, the reset assembly includes a pressing rod, a spring, a one-way air valve, and a fixed shell. The pressing rod is fixedly installed on one side of the driven wheel, the fixed shell is fixedly installed at the lower end of the powder bin, the pressing rod is slidably installed inside the fixed shell, one end of the spring is installed at the bottom end of the fixed shell, the other end of the spring is connected to the pressing rod, the one-way air valve is installed outside the fixed shell, and a tiny air hole is opened at the bottom end of the fixed shell.

[0019] In the above solution, by fixing the outer fixed shell, when the driving wheel installed at the right end of the storage bin pushes the driven wheel to rotate, the driven wheel squeezes the gas inside the fixed shell through the pressing rod, and the gas is discharged from the inside of the fixed shell through the one-way air valve. When the driving wheel stops pushing, due to the low air pressure inside the fixed shell, it will continuously suck air inward through the tiny air hole. At the same time, the spring slowly pushes the pressing rod to move outward. In this way, the reset time of the powder bin can be slowed down, ensuring that there is enough desulfurizing agent entering the desulfurization cavity to react with SO2 in the waste gas during this process. Through this solution, it can be realized that there is no need to manually monitor the SO2 concentration in the waste gas in real time to switch the emergency spray tower to ensure that the SO2 in the waste gas does not exceed the standard, saving human resources.

[0020] Preferably, a rotating shaft is rotatably installed in the desulfurization cavity, and a fan blade is fixedly installed on the rotating shaft.

[0021] In the above solution, by installing a rotating shaft and a fan blade in the desulfurization cavity, since the entire waste heat recovery device is a closed space, through this solution, a negative pressure can be formed in the entire waste heat recovery device to ensure that there is no waste gas leakage when absorbing foundry waste gas. At the same time, the airflow driven by the fan blade makes the unreacted desulfurizing agent powder continuously flow in the desulfurization cavity, ensuring its full reaction with SO2 in the waste gas and preventing it from accumulating at the bottom end of the desulfurization cavity without sufficient reaction.

[0022] Preferably, a dust baffle is connected between the rotating shaft and the desulfurization cavity.

[0023] In the above solution, by setting the dust baffle, a part of the solid powder after the reaction of the desulfurizer can be blocked from accumulating outside the filter bag of the bag filter, preventing the moisture generated by the reaction in the waste heat boiler and the moisture generated by the desulfurization of the desulfurizer from forming a paste with these fixed powders and sticking to the surface of the filter bag, thereby reducing its filtration speed.

[0024] Preferably, a screw rod is fixed at the central position of the powder bin, an adjusting table is installed at the end of the screw rod, the adjusting table is matched with the screw rod, an installation ring is rotatably installed outside the adjusting table, an installation block is installed at the bottom end of the fan blade, and the installation block is slidably installed on the installation ring.

[0025] In the above solution, by setting the screw rod and the adjusting table, when the powder bin rotates, the position of the installation ring cooperating with the installation block at the bottom end of the fan can be changed through the screw rod, so as to change the length of the fan extending out, and the wind pressure brought by the fan can be reduced by changing the fan blade diameter, so as to increase the residence time of the forging waste gas in the desulfurization chamber, so that the SO2 therein reacts fully with the desulfurizer and prevent the SO2 from exceeding the standard.

[0026] The beneficial effects of the present invention are as follows:

[0027] 1. By setting the sprinkling component in the present invention, in cooperation with the melting furnace, when the melting furnace is tilted, the sprinkling plate is driven to move to the right, so that the sulfur powder in the storage bin is poured onto the sprinkling plate, and the sulfur powder is sprinkled by the return stroke of the melting furnace; and by installing a driving wheel outside the powder bin, in cooperation with the powder bin, when sprinkling the sulfur powder, it can drive the desulfurization component to change the aperture of the desulfurized agent sprinkled, so that more desulfurized agent can be sprayed within a certain time, ensuring that the desulfurized agent reacts fully with SO2 in the waste gas and ensuring that the SO2 in the waste gas does not exceed the standard.

[0028] 2. By setting the desulfurization component in cooperation with the reset component in the present invention, when the sulfur powder is just sprinkled, the aperture between the powder bin and the spraying chamber is increased to increase the spraying amount of the desulfurized agent, and the reset component ensures a slow reset, ensuring that enough desulfurized agent enters the desulfurization chamber to react with SO2 in the waste gas during this process. In this way, it is realized that there is no need to manually monitor the SO2 concentration in the waste gas in real time to switch the emergency spray tower to ensure that the SO2 in the waste gas does not exceed the standard, saving human resources.

[0029] 3. By combining the desulfurization component with the rotating shaft and the fan blade in the present invention, the wind pressure in the waste heat recovery device is changed by changing the length of the extended blade diameter of the fan blade by using the rotation of the powder bin. After sprinkling the sulfur powder, the flow rate of the gas in the device is reduced, so as to extend the residence time of the forging waste gas in the desulfurization chamber, further enabling the SO2 therein to react fully with the desulfurizer and preventing the SO2 in the waste gas from exceeding the standard. And installing the rotating shaft and the fan blade in the desulfurization chamber can prevent the unreacted desulfurizer from accumulating at the bottom end of the desulfurization chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0031] Now, the above and other aspects of the present invention will be described by way of example only with reference to the accompanying drawings, in which:

[0032] Figure 1 is an isometric structure schematic diagram of the whole of the present invention;

[0033] Figure 2 is an isometric structure schematic diagram of the casting part of the present invention;

[0034] Figure 3 is the present invention Figure 2 a magnified schematic diagram of part A therein;

[0035] Figure 4 is a front view of the whole of the present invention;

[0036] Figure 5 is a front view of the desulfurization component of the present invention;

[0037] Figure 6 is the present invention Figure 5 an isometric sectional view of part B thereof;

[0038] Figure 7 is a sectional view of the reset component of the present invention;

[0039] Figure 8 is a schematic diagram of the waste gas flow direction of the present invention.

[0040] In the figure: 1, melting furnace; 2, ingot casting machine; 3, conveyor belt; 4, waste heat boiler; 5, gravity settling chamber; 6, bag filter; 7, heat exchanger; 8, gas collection hood; 9, sprinkling component; 91, connecting rod; 92, sprinkling plate; 921, pushing plate; 93, mounting plate; 94, storage bin; 941, mating plate; 942, driving wheel; 95, fixed rod; 10, desulfurization component; 101, powder bin; 1011, discharge hole; 1012, driven wheel; 1013, screw; 1014, adjusting table; 1015, mounting ring; 102, spraying chamber; 103, spray head; 104, intake pipe; 105, desulfurization chamber; 1051, rotating shaft; 1052, fan blade; 1053, dust baffle; 1054, mounting block; 11, reset component; 111, pressing rod; 112, spring; 113, one-way air valve; 114, fixed shell; 1141, micro air holes. Detailed implementation manners

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0042] Please refer to Figures 1 to 8 , the present invention provides an environment-friendly multi-stage heat exchange device for recovering waste heat from casting exhaust gas, and the technical solution is as follows:

[0043] An environment-friendly multi-stage heat exchange device for recovering waste heat from casting exhaust gas, comprising a melting furnace 1, an ingot casting machine 2, a conveyor belt 3, a waste heat boiler 4, a gravity settling chamber 5, a bag filter 6 and a heat exchanger 7; further comprising a gas collecting hood 8, a sprinkling assembly 9, a desulfurization assembly 10 and a reset assembly 11. The ingot casting machine 2 and the conveyor belt 3 are sequentially installed on the right side of the melting furnace 1 from left to right. The gas collecting hood 8 is installed above the melting furnace 1. When the melting furnace 1 and the ingot casting machine 2 generate casting exhaust gas, it will be sucked into the gas collecting hood 8. The waste heat boiler 4 is installed on the right side of the gas collecting hood 8 and is communicated with the gas collecting hood 8. The gravity settling chamber 5, the desulfurization assembly 10, the bag filter 6 and the heat exchanger 7 are sequentially installed at the rear end of the waste heat boiler 4 and are communicated with each other. After the casting exhaust gas enters the gas collecting hood 8, it will first pass through the waste heat boiler 4. At high temperature, VOCs (styrene, formaldehyde, etc.) in the casting exhaust gas are completely decomposed into CO2 and H2O. Then, part of the solid particles are settled through the gravity settling chamber 5. After removing SO2 through the desulfurization assembly 10, the remaining solid particles and the solid components generated during desulfurization are removed by the bag filter 6. The sprinkling assembly 9 is fixedly installed at the upper end of the ingot casting machine 2; and is connected to the melting furnace 1. When the melting furnace 1 pours molten magnesium into the ingot casting machine 2, it drives the sprinkling assembly 9 to move directly above the ingot casting machine 2 and sprinkle sulfur powder into the ingot casting machine 2. At this time, a large amount of SO2 will be generated. At the same time, the sprinkling assembly 9 will drive the desulfurization assembly 10 to rotate to increase the aperture of the desulfurization agent sprayed in the desulfurization assembly 10. The reset assembly 11 will slowly drive the desulfurization assembly 10 to reset after the pouring of the melting furnace 1 is completed, and restore the aperture of the desulfurization agent sprayed in the desulfurization assembly 10.

[0044] As an implementation manner of the present invention, refer to Figures 1 to 4, the sprinkling component 9 includes a connecting rod 91, a sprinkling plate 92, a mounting plate 93, a storage bin 94 and a fixing rod 95. One end of the connecting rod 91 is rotatably connected to one side of the melting furnace 1 close to the ingot casting machine 2. The sprinkling plate 92 is rotatably mounted at the other end of the connecting rod 91. The mounting plate 93 is fixedly mounted above the ingot casting machine 2, and the sprinkling plate 92 is slidably mounted on the mounting plate 93. The fixing rod 95 is fixedly mounted above the ingot casting machine 2. The storage bin 94 is rotatably mounted on the fixing rod 95. A push plate 921 is mounted at one end of the sprinkling plate 92, and a mating plate 941 is mounted at the lower end of the storage bin 94. The right side of the push plate 921 is in contact with the left side of the mating plate 941. When the melting furnace 1 is tilted, the right end of the melting furnace 1 will push the connecting rod 91 to move forward. At this time, it will drive the sprinkling plate 92 to move to the right. At this time, the push plate 921 mounted at the rear end of the sprinkling plate 92 will push the mating plate 941 at the lower end of the storage bin 94. At this time, since the storage bin 94 is fixed on the fixing rod 95, the storage bin 94 will rotate around the fixing rod 95 as the center, so that the sulfur powder in the storage bin 94 falls onto the sprinkling plate 92. When the melting furnace 1 returns, since the storage bin 94 is not stressed, it returns to its original position. The push plate 921 will drive the sulfur powder poured on the sprinkling plate 92 to move above the ingot casting machine 2 and sprinkle the sulfur powder into the ingot casting machine 2 through the gaps on the sprinkling plate 92. Through this solution, the process of manually sprinkling sulfur powder into the ingot casting machine 2 in the prior art can be replaced, preventing a large amount of SO2 generated when sprinkling sulfur powder from being inhaled by the staff, and in this way, the sulfur powder can be evenly sprinkled into the ingot casting machine 2, so that a MgS film is generated on its surface faster, improving the quality of Mg ingots.

[0045] As an implementation manner of the present invention, refer to Figures 5 to 6, the desulfurization component 10 includes a powder bin 101, a spraying chamber 102, a spray head 103, an air inlet pipe 104, and a desulfurization chamber 105. One end of the desulfurization chamber 105 is communicated with the gravity settling chamber 5, and the other end of the desulfurization chamber 105 is communicated with the bag filter 6. The spraying chamber 102 is fixedly installed inside the desulfurization chamber 105. The powder bin 101 is rotatably connected to one side of the spraying chamber 102. A plurality of the air inlet pipes 104 penetrate through the desulfurization chamber 105 in a circumferential array and are communicated to the inside of the spraying chamber 102, and the air inlet pipe 104 penetrates through the desulfurization chamber 105. A plurality of the spray heads 103 are arranged in a circumferential array inside the spraying chamber 102, and the positions of the spray heads 103 and the air inlet pipes 104 are on the same axis. An outlet hole 1011 is opened on the adjacent side of the powder bin 101 and the spraying chamber 102, and the outlet hole 1011 communicates the powder bin 101 and the spraying chamber 102. By introducing high-pressure gas into the air inlet pipe 104 and spraying it out from the spray head 103, during this process, when the high-pressure air flow passes through the powder bin 101, it will drive the desulfurizing agent inside through the outlet hole 1011 into the spraying chamber 102, and be sprayed into the desulfurization chamber 105 together with the high-pressure air flow from the spraying chamber 102 to react with SO2 in the waste gas, realizing the purification of the waste gas. And when the powder bin 101 and the spraying chamber 102 do not sprinkle sulfur powder, the outlet hole 1011 is not in a completely matching state, that is, the aperture does not reach the maximum value. Through this solution, dry desulfurization can be realized. While ensuring the removal of SO2, it can avoid the heat loss caused by the absorption of the heat in the waste gas by the moisture in the solution due to the traditional method of spraying alkaline solution.

[0046] As an implementation manner of the present invention, referring to Figures 3 to 4 , a driven wheel 1012 is fixedly installed on the outer side of the powder bin 101. A driving wheel 942 is installed at the right end of the storage bin 94. The upper end surface of the driving wheel 942 is in contact with the lower end surface of the driven wheel 1012. When the storage bin 94 rotates around the fixed rod 95, the driving wheel 942 installed at the right end of the storage bin 94 will push the driven wheel 1012 to rotate. At this time, since the powder bin 101 rotates while the spraying chamber 102 remains unchanged, the aperture of the outlet hole 1011 between the powder bin 101 and the spraying chamber 102 will increase. At this time, the sprayed desulfurizing agent will increase, ensuring the complete removal of SO2 in the waste gas. Through this solution, it can be realized that the dosage of the sprayed desulfurizing agent is automatically increased when sprinkling sulfur powder, without manual monitoring, greatly increasing the convenience of waste gas recovery.

[0047] As an implementation manner of the present invention, referring to Figure 7, the reset assembly 11 includes a pressing rod 111, a spring 112, a one-way air valve 113, and a fixed housing 114. The pressing rod 111 is fixedly installed on one side of the driven wheel 1012, the fixed housing 114 is fixedly installed at the lower end of the powder bin 101, the pressing rod 111 is slidably installed inside the fixed housing 114, one end of the spring 112 is installed at the bottom end of the fixed housing 114, the other end of the spring is connected to the pressing rod 111, the one-way air valve 113 is fixedly installed on the outside of the fixed housing 114, and a micro air hole 1141 is opened at the bottom end of the fixed housing 114. By fixing the outer fixed housing 114, when the driving wheel 942 installed at the right end of the storage bin 94 pushes the driven wheel 1012 to rotate, the driven wheel 1012 squeezes the gas inside the fixed housing 114 inward through the pressing rod 111, so that the gas is discharged from the inside of the fixed housing 114 through the one-way air valve 113. When the driving wheel 942 stops pushing, due to the low air pressure inside the fixed housing 114, it will continuously suck air inward through the micro air hole 1141. At the same time, the spring 112 slowly pushes the pressing rod 111 to move outward. In this way, the reset time of the powder bin 101 can be slowed down, ensuring that enough desulfurizer enters the desulfurization chamber 105 to react with SO2 in the waste gas during this process. Through this solution, it is possible to achieve that there is no need for manual real-time monitoring of the SO2 concentration in the waste gas to switch the emergency spray tower to ensure that the SO2 in the waste gas does not exceed the standard, saving human resources.

[0048] As an implementation manner of the present invention, referring to Figure 6 , a rotating shaft 1051 is rotatably installed in the desulfurization chamber 105, and a fan blade 1052 is fixedly installed on the rotating shaft 1051. By installing the rotating shaft 1051 and the fan blade 1052 in the desulfurization chamber 105, since the entire waste heat recovery device is a closed space, a negative pressure can be formed in the entire waste heat recovery device through this solution, ensuring that there is no waste gas leakage when absorbing the foundry waste gas. At the same time, the airflow driven by the fan blade 1052 makes the unreacted desulfurizer powder continuously flow in the desulfurization chamber 105, ensuring its full reaction with SO2 in the waste gas and preventing it from accumulating at the bottom end of the desulfurization chamber 105 without sufficient reaction.

[0049] As an implementation manner of the present invention, referring to Figure 6 , a dust baffle 1053 is connected between the rotating shaft 1051 and the desulfurization chamber 105. By setting the dust baffle 1053, a part of the solid powder after the desulfurizer reaction can be blocked from accumulating outside the cloth bag of the bag filter 6, preventing the moisture generated by the reaction in the waste heat boiler 4 and the moisture generated by the desulfurizer desulfurization from forming a paste with these fixed powders and sticking to the cloth bag surface, reducing its filtration speed.

[0050] As an implementation manner of the present invention, referring to Figures 6 to 8, a screw rod 1013 is fixed at the central position of the powder bin 101. An adjusting table 1014 is installed at the end of the screw rod 1013. The adjusting table 1014 is matched with the screw rod 1013. When the screw rod 1013 rotates, the adjusting table 1014 moves up and down. An installation ring 1015 is rotatably installed outside the adjusting table 1014. An installation block 1054 is installed at the bottom end of the fan blade 1052. The installation block 1054 is slidably installed on the installation ring 1015. By arranging the screw rod 1013 and the adjusting table 1014, when the powder bin 101 rotates, the position of the cooperation between the installation ring 1015 and the installation block 1054 at the bottom end of the fan can be changed through the screw rod 1013, so as to change the length of the fan extending out. By changing the diameter of the fan blade 1052, the wind pressure brought by the fan is reduced, so as to increase the residence time of the forging waste gas in the desulfurization chamber 105, make the SO2 therein fully react with the desulfurizer, and prevent the SO2 from exceeding the standard.

[0051] Working process: When the melting furnace 1 and the ingot casting machine 2 generate casting waste gas, it will be sucked into the air collecting hood 8. After the casting waste gas enters the air collecting hood 8, it will first pass through the waste heat boiler 4. At high temperature, the VOCs in the casting waste gas are completely decomposed into CO2 and H2O. Then, part of the solid particles are settled through the gravity settling chamber 5. After the SO2 is removed by the desulfurization component 10, the remaining solid particles and the solid components generated during desulfurization are removed by the bag filter 6. When the melting furnace 1 tilts towards the ingot casting machine 2, the driving and sprinkling component 9 drives the sulfur powder to move above the ingot casting machine 2 and sprinkle the sulfur powder into the ingot casting machine 2. At this time, a large amount of SO2 will be generated. At the same time, the driving and sprinkling component 9 will drive the desulfurization component 10 to rotate to increase the aperture of the desulfurizer sprayed in the desulfurization component 10. The reset component 11 will slowly drive the desulfurization component 10 to reset after the melting furnace 1 finishes tilting until a large amount of generated SO2 is reacted, and then the aperture of the desulfurizer sprayed in the desulfurization component 10 is restored.

[0052] Sprinkling process: When the melting furnace 1 tilts, the right end of the melting furnace 1 will push the connecting rod 91 to move forward. At this time, it will drive the sprinkling plate 92 to move to the right. At this time, the pushing plate 921 installed at the rear end of the sprinkling plate 92 will push the matching plate 941 at the lower end of the storage bin 94. At this time, since the storage bin 94 is fixed on the fixed rod 95, the storage bin 94 will rotate around the fixed rod 95, so that the sulfur powder in the storage bin 94 falls onto the sprinkling plate 92. When the melting furnace 1 returns, the storage bin 94 will return to its original position due to the lack of force. The pushing plate 921 will drive the sulfur powder poured on the sprinkling plate 92 to move above the ingot casting machine 2 and sprinkle the sulfur powder into the ingot casting machine 2 through the gaps on the sprinkling plate 92.

[0053] Process of injecting desulfurizing agent: High-pressure gas is introduced into the intake pipe 104 and sprayed out from the nozzle 103. During this process, when the high-pressure gas flow passes through the powder bin 101, it will drive the internal desulfurizing agent into the spraying chamber 102 through the discharge hole 1011, and then be sprayed into the desulfurization chamber 105 together with the high-pressure gas flow from the spraying chamber 102.

[0054] Process of aperture increase: When the storage bin 94 rotates around the fixed rod 95, the driving wheel 942 installed at the right end of the storage bin 94 will push the driven wheel 1012 to rotate. At this time, since the powder bin 101 rotates while the spraying chamber 102 remains unchanged, the aperture of the discharge hole 1011 between the powder bin 101 and the spraying chamber 102 will increase.

[0055] Reset process: When the driving wheel 942 installed at the right end of the storage bin 94 pushes the driven wheel 1012 to rotate, the driven wheel 1012 squeezes the gas inside the fixed shell 114 inward through the pressing rod 111, and the gas is discharged from the inside of the fixed shell 114 through the one-way air valve 113. When the driving wheel 942 stops pushing, due to the low air pressure inside the fixed shell 114, it will continuously suck air inward through the micro-holes 1141. At the same time, the spring 112 slowly pushes the pressing rod 111 to move outward. By using the small aperture of the micro-holes 1141 and slow air intake, the reset speed of the powder bin 101 is slowed down, so as to ensure that the spraying chamber 102 sprays enough desulfurizing agent to remove SO2 in the waste gas within a certain period of time.

[0056] Process of blade diameter increase: When the powder bin 101 rotates, it drives the screw 1013 to rotate. At this time, the adjusting table 1014 moves along the screw 1013. Since the fan blade 1052 is installed on the adjusting table 1014 through the mounting ring 1015, when the adjusting table 1014 moves, the mounting ring 1015 moves with the adjusting table 1014. The mounting block 1054 at the lower end of the fan blade 1052 penetrates the rotating shaft 1051. At this time, the fan blade 1052 moves vertically and telescopically along with the adjusting table 1014, thereby changing the blade diameter of the fan blade 1052.

[0057] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly multi-stage heat exchange device for recovering waste heat from casting waste gas, comprising a smelting furnace (1), an ingot casting machine (2), a conveyor belt (3), a waste heat boiler (4), a gravity settling chamber (5), a bag filter (6) and a heat exchanger (7); characterized in that: The invention also comprises an air collecting hood (8), a throwing assembly (9), a desulfurization assembly (10) and a reset assembly (11). The ingot casting machine (2) and the conveyor belt (3) are sequentially installed on the right side of the smelting furnace (1) from left to right. The air collecting hood (8) is installed on the upper end of the smelting furnace (1). The waste heat boiler (4) is installed on the right side of the air collecting hood (8) and is connected to the air collecting hood (8). The gravity settling chamber (5), the desulfurization assembly (10), the bag filter (6) and the heat exchanger (7) are sequentially installed on the rear end of the waste heat boiler (4) from front to back and are connected to each other. The throwing assembly (9) is fixedly installed on the upper end of the ingot casting machine (2). When the smelting furnace (1) pours magnesium liquid into the ingot casting machine (2), the throwing assembly (9) is driven to move directly above the ingot casting machine (2). During the movement of the throwing assembly (9), the desulfurization assembly (10) is driven to rotate to increase the aperture of the sprayed desulfurizer. After the pouring is completed, the reset assembly (11) slowly drives the desulfurization assembly (10) to reset.

2. The environmentally friendly multi-stage heat exchange device for recovering waste heat from casting exhaust gas according to claim 1, characterized in that: The sprinkling assembly (9) comprises a connecting rod (91), a sprinkling plate (92), a mounting plate (93), a storage bin (94) and a fixed rod (95), wherein one end of the connecting rod (91) is rotatably mounted on a side of the smelting furnace (1) close to the ingot casting machine (2), the sprinkling plate (92) is rotatably mounted on the other end of the connecting rod (91), the mounting plate (93) is fixedly mounted on the upper end of the ingot casting machine (2), the sprinkling plate (92) is slidably mounted on the mounting plate (93), the fixed rod (95) is fixedly mounted above the ingot casting machine (2), the storage bin (94) is rotatably mounted on the fixed rod (95), a pushing plate (921) is mounted on one end of the sprinkling plate (92), a matching plate (941) is mounted on the lower end of the storage bin (94), and the right side of the pushing plate (921) is in contact with the left side of the matching plate (941).

3. The environmentally friendly multi-stage heat exchange device for recovering waste heat from casting exhaust gas according to claim 1 is characterized in that: The desulfurization assembly (10) comprises a powder bin (101), a spraying chamber (102), a nozzle (103), an air inlet pipe (104) and a desulfurization chamber (105). One end of the desulfurization chamber (105) is connected to a gravity settling chamber (5), and the other end of the desulfurization chamber (105) is connected to a bag filter (6). The spraying chamber (102) is fixedly installed inside the desulfurization chamber (105). The powder bin (101) is rotatably connected to one side of the spraying chamber (102). The circular array (104) is connected to the inside of the spraying chamber (102), and the air inlet pipe (104) passes through the desulfurization chamber (105). The plurality of nozzles (103) are arranged in a circular array inside the spraying chamber (102), and the positions of the nozzles (103) and the air inlet pipe (104) are on the same axis. A discharge hole (1011) is provided on the adjacent side of the powder bin (101) and the spraying chamber (102), and the discharge hole (1011) connects the powder bin (101) and the spraying chamber (102).

4. The environmentally friendly multi-stage heat exchange device for recovering waste heat from casting exhaust gas according to claim 3 is characterized in that: A driven wheel (1012) is fixedly mounted on the outside of the powder bin (101), and a driving wheel (942) is mounted on the right end of the material storage bin (94), wherein the upper end surface of the driving wheel (942) contacts the lower end surface of the driven wheel (1012).

5. The environmentally friendly multi-stage heat exchange device for recovering waste heat from casting exhaust gas according to claim 4 is characterized in that: The reset assembly (11) comprises a pressing rod (111), a spring (112), a one-way air valve (113) and a fixed shell (114); the pressing rod (111) is fixedly mounted on one side of the driven wheel (1012); the fixed shell (114) is fixedly mounted on the lower end of the powder bin (101); the pressing rod (111) is slidably mounted on the inner side of the fixed shell (114); one end of the spring (112) is mounted on the bottom end of the fixed shell (114); the other end of the spring (112) is connected to the pressing rod (111); the one-way air valve (113) is mounted on the outer side of the fixed shell (114); and a tiny air hole (1141) is provided at the bottom end of the fixed shell (114).

6. The environmentally friendly multi-stage heat exchange device for recovering waste heat from casting exhaust gas according to claim 3 is characterized by: A rotating shaft (1051) is rotatably mounted in the desulfurization chamber (105), and a fan blade (1052) is fixedly mounted on the rotating shaft (1051).

7. The environmentally friendly multi-stage heat exchange device for recovering waste heat from casting exhaust gas according to claim 6, characterized in that: A dust shield (1053) is connected between the rotating shaft (1051) and the desulfurization chamber (105).

8. The environmentally friendly multi-stage heat exchange device for recovering waste heat from casting exhaust gas according to claim 6, characterized in that: A screw rod (1013) is fixed at the center of the powder bin (101), an adjustment platform (1014) is installed at the end of the screw rod (1013), the adjustment platform (1014) cooperates with the screw rod (1013), a mounting ring (1015) is rotatably installed on the outer side of the adjustment platform (1014), a mounting block (1054) is installed at the bottom end of the fan blade (1052), and the mounting block (1054) is slidably installed on the mounting ring (1015).

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