Resin sand continuous thermal regeneration roasting furnace and system

Abstract

A resin sand continuous heat regeneration roasting furnace and system, the roasting furnace includes a furnace chamber and a furnace cylinder, an air inlet and a feed inlet are arranged at the upper part of the furnace chamber, the feed inlet is located below the air inlet, a furnace cylinder is arranged below the furnace chamber, hot air furnace pipes are arranged in layers along the axial direction in the furnace chamber, the hot air furnace pipes of each layer are connected by regeneration bellows at both ends, a burner is installed in the lowest regeneration bellows, and a temperature regulating air duct is connected between the burner and the air inlet at the upper part of the furnace chamber; the system includes the above-mentioned roasting furnace, a screening and drying drum, a magnetic separation device, a raw material bucket elevator, a sand rubbing machine and a new sand adding belt conveyor. The present invention uses the hot air generated by the roasting furnace to dry the waste sand core, so that the heat energy is fully utilized, and the regeneration efficiency of the whole system is 30% higher than that of the current equipment. The volatile matter that is not fully burned in the roasting furnace is injected into the burner with the hot air flow, so that the volatile components are fully burned and decomposed, so that the system has no VOCs emissions.

Description

Technical Field

[0001] The invention relates to a roasting furnace for regenerating and reusing resin sand used in a casting process and a system using the roasting furnace, belonging to the technical field of resin sand regeneration. Background Art

[0002] The preparation of sand cores and sand molds is an important link in the foundry industry. With the strict control of resources, the mining of raw sand is limited, and the price of foundry sand has increased year by year, reaching more than 400 yuan / ton. The cost of sand recycled from waste sand cores is less than 140 yuan / ton, and the emission of hazardous waste is effectively reduced. Therefore, the recycling of waste sand cores is imperative.

[0003] The current resin sand regeneration equipment has low thermal efficiency, occupies a large area, and has VOCs emission problems, causing air pollution.

[0004] The "A resin sand regeneration production line for casting" disclosed in CN106623770A, the "Fully automatic resin sand regeneration production line for casting" disclosed in CN102909315A, and the "A resin sand regeneration system" disclosed in CN102886491A all have the above-mentioned problems, and have complex structures and low regeneration efficiency. Summary of the invention

[0005] Aiming at the shortcomings of the existing waste sand core sand regeneration technology in the casting process, the present invention provides a resin sand continuous thermal regeneration roasting furnace with good regeneration effect and no secondary pollution, and a regeneration system using the thermal roasting furnace.

[0006] The resin sand continuous thermal regeneration roasting furnace of the present invention adopts the following technical scheme:

[0007] The roasting furnace comprises a furnace chamber and a furnace cylinder. An air inlet and a material inlet are arranged at the upper part of the furnace chamber, the material inlet is located below the air inlet, a furnace cylinder is arranged below the furnace chamber, hot blast furnace pipes are arranged in layers along the axial direction in the furnace chamber, the hot blast furnace pipes of each layer are connected in a circuitous manner by regeneration wind boxes at both ends, a burner is installed in the lowest regeneration wind box, and a temperature regulating air duct is connected between the burner and the air inlet at the upper part of the furnace chamber.

[0008] The furnace chamber has a rectangular cross section.

[0009] The last regeneration bellows at the upper part of the furnace chamber is provided with a hot air outlet, which is connected to the drying bellows below the screening and drying drum through a hot air duct, so as to remove the moisture, mud, ash and powder in the waste sand core, thereby making full use of the heat energy.

[0010] A dust collector is arranged at the upper part of the furnace chamber between the air inlet and the feed inlet.

[0011] The hot blast furnace pipe rises in a circuitous manner along the axial direction of the furnace chamber, with multiple circuits per meter in height, which increases the effective height of the furnace chamber by several times, thereby greatly increasing the travel of the hot blast in the sand.

[0012] The hot blast furnace pipe is a socket-and-spigot pipe, which is connected to the regeneration wind box by a socket-and-spigot connection, and a socket-and-spigot gap is provided, so that hot blast can overflow and ignite combustibles in the resin sand to accelerate the decomposition of the resin film.

[0013] A discharger is arranged at the bottom of the furnace, and a speed-adjustable continuous discharger is adopted.

[0014] The burner is connected to a combustion-supporting air duct, which is connected to a heat exchanger, which is located in the furnace and penetrates the furnace shell to be connected to a combustion-supporting air fan. In this way, the combustion-supporting air output by the blower passes through the heat exchanger in the furnace, cools the hot sand and brings the heat back to the burner, effectively improving the thermal efficiency.

[0015] Burners are installed at both ends of the lowermost regeneration wind box.

[0016] The waste sand core enters the furnace cavity from the feed port through the bucket elevator. The gas and combustion-supporting air of a certain pressure enter the burner through the gas pipe and the combustion-supporting air pipe respectively and ignite. At the same time, the temperature-adjusting fan installed on the top of the furnace sends the temperature-adjusting air into the burner. The high-temperature hot air flow generated by the two temperature-adjusting burners enters from both ends of the No. 1 regeneration wind box at the bottom of the furnace cavity. The hot air flow rises layer by layer through the hot air furnace pipe and the wind boxes on both sides, so that the heat exchange time between the hot air flow and the resin sand is fully extended, so that a higher thermal efficiency can be obtained. The waste sand runs from top to bottom in the furnace cavity, is heated and baked, and is cooled down layer by layer in the furnace cylinder and discharged. The induced draft fan guides the exhaust gas to the burner for combustion, achieving zero VOCs emissions.

[0017] A resin sand continuous thermal regeneration system comprises a roasting furnace of the above structure, and also comprises a screening and drying drum, a magnetic separation device, a raw material bucket elevator, a sand rubbing machine and a new sand adding belt conveyor. The screening and drying drum is connected to the hot air outlet at the end of the roasting furnace through a hot air duct. The magnetic separation device is arranged below the screening and drying drum. The feed port and the discharge port of the raw material bucket elevator are respectively connected to the discharge port of the magnetic separation device and the feed port of the roasting furnace. The sand rubbing machine is arranged below the sand unloading port of the roasting furnace, and the discharge end of the new sand adding belt conveyor is connected to the sand rubbing machine.

[0018] The screening and drying drum is connected to the waste sand core feeding hopper through a conveyor, a collecting hopper is arranged at the bottom of the screening and drying drum, and the magnetic separation device is arranged below the collecting hopper.

[0019] A dust collecting hood is arranged outside the screening and drying drum, and a dust collector is connected to the top of the collecting hood.

[0020] The magnetic separation device comprises a primary magnetic separation belt conveyor and a secondary magnetic separation belt conveyor which are connected in sequence, and the lower parts of the primary magnetic separation belt conveyor and the secondary magnetic separation belt conveyor are connected to a residual iron receiving bucket through a residual iron receiving guide groove.

[0021] The sand rubbing machine is provided with a dust removal cover.

[0022] A cold air box is arranged below the sand rubbing machine to cool down the hot sand.

[0023] The waste sand cores first enter the screening and drying drum, and the hot air generated by the roasting furnace enters the screening and drying drum to dry the waste sand cores during the screening process and remove the moisture, mud, and ash in the waste sand cores; the waste sand core bulk materials after screening and drying enter the magnetic separation device to remove the residual iron slag in the waste sand core bulk materials; the waste sand core bulk materials after magnetic separation enter the roasting furnace through the raw material bucket elevator for heating and regeneration, and the regenerated sand and new sand are added to the new sand transported by the belt conveyor and enter the sand rubbing machine for mixing and enter the finished sand bin together.

[0024] The present invention uses the hot air generated by the roasting furnace to dry the waste sand cores in the crushing and screening process, so as to remove the moisture, mud and ash in the waste sand cores, so that the heat energy can be fully utilized, and the regeneration efficiency of the entire system is increased by 30-50% compared with the current equipment. In the roasting furnace, the volatile components that are not fully burned are injected into the burner with the hot air flow, so that the volatile components are fully burned and decomposed, so that the system has no VOCs emissions. In addition, the system of the present invention occupies a small area and does not need to build a special factory building; it can be inserted in the existing core making area to form a low-energy and low-emission cyclic production process of core making, casting, waste sand core regeneration, and core making. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the resin sand continuous thermal regeneration system of the present invention.

[0026] Figure 2 yes Figure 1 Left view of the middle roasting furnace.

[0027] Figure 3 It is a schematic diagram of the plan layout of the resin sand continuous thermal regeneration system of the present invention.

[0028] Among them: 1. Waste sand core feeding hopper, 2. Collection hopper, 3. Receiving port, 4. Screening and drying drum, 5. Dust removal pipe interface, 6. Primary magnetic separation belt conveyor, 7. Secondary magnetic separation belt conveyor, 8. Drying bellows, 9. Hot air duct, 10. Raw material bucket elevator, 11. Roasting furnace, 12. Bag dust collector, 13. Temperature control air duct, 14. Temperature control burner, 15. Gas pipe, 16. Close-packed tube heat exchanger, 17 .Cold air box, 18. Sand rubbing machine, 19. New sand adding belt conveyor, 20. Dust removal hood, 21. Draft fan, 22. Finished product bucket elevator, 23. Finished product sand bin, 24. Regeneration air box, 25. Hot air furnace pipe, 26. Grille discharger, 27. Insulation layer, 28. Hot air outlet, 29. Combustion-supporting fan, 30. Scrap iron receiving guide trough, 31. Scrap iron receiving bucket, 32. Bag dust collector, 33. Chimney. DETAILED DESCRIPTION

[0029] like Figure 1 and Figure 3 As shown, the resin sand continuous thermal regeneration system of the present invention includes a screening and drying drum 4, a magnetic separation device, a raw material bucket elevator 10, a roasting furnace 11, a sand rubbing machine 18, a new sand adding belt conveyor 19 and a finished product bucket elevator 22.

[0030] The receiving port 3 of the screening and drying drum 4 is connected to the waste sand core feeding hopper 1 through a conveyor. The bottom of the screening and drying drum 4 is provided with a collecting hopper 2 and a drying air box 8. The collecting hopper 2 is located on one side of the drying air box 8. The drying air box 8 is connected to the upper part of the furnace chamber of the roasting furnace 11 through a hot air duct 9. The top surface of the drying air box 8 is inclined toward the collecting hopper 2. The inclined top surface supports the drum screen and is provided with fish scale holes. The hot air flow blows the scattered resin sand into the collecting hopper 2 through the fish scale holes. A dust removal pipe interface 5 is provided on the top of the screening and drying drum 4. Figure 3 The dust removal pipe interface 5 is connected to the bag dust collector 32 through a pipeline, and the tail end of the bag dust collector 32 is connected to the chimney 33. A magnetic separation device is arranged below the collecting hopper 2, and the magnetic separation device includes a primary magnetic separation belt conveyor 6 and a secondary magnetic separation belt conveyor 7 connected in sequence. Figure 2 The first-stage magnetic separation belt conveyor 6 and the second-stage magnetic separation belt conveyor 7 are connected to the residual iron receiving bucket 31 through the residual iron receiving guide groove 30. The end of the magnetic separation device is connected to the upper inlet of the roasting furnace 11 through the raw material bucket elevator 10. A sand rubbing machine 18 is arranged below the roasting furnace 11, and a dust removal cover 20 is arranged above the outlet of the sand rubbing machine 18. A cold air box 17 is arranged below the sand rubbing machine 18, and a new sand adding belt conveyor 19 is connected to the feed port of the sand rubbing machine 18. The sand rubbing machine 18 is a prior art and is used to remove the adhesion on the surface of the sand particles. At the same time, the new sand and the regenerated sand are mixed in the sand rubbing machine 18. The discharge port of the sand rubbing machine 18 is connected to the feed port of the finished product bucket elevator 22, and the discharge port of the finished product bucket elevator 22 is connected to the finished sand bin 23.

[0031] The roasting furnace 11 includes a furnace shell, an insulation layer is arranged on the outer periphery of the furnace shell, and the furnace shell includes three sections from top to bottom, namely, a furnace throat, a furnace cavity and a furnace cylinder. A feed port is arranged at the furnace throat (the upper part of the furnace cavity), a bag filter 12 is arranged above the feed port, and a high-pressure induced draft fan 21 is arranged above the bag filter 12 on the outer side of the furnace shell. The furnace throat has a certain height to ensure that the overflow wind of the hot blast furnace pipe 25 in the furnace cavity will not be blown out from the feed port, and the furnace throat is also a furnace charge preheating section.

[0032] The furnace chamber is the regeneration section, and its cross section is rectangular. The furnace chamber is layered with closely packed hot air furnace pipes 25 made of silicon carbide material. The hot air furnace pipes 25 of each layer are connected to the regeneration wind boxes 24 at both ends in a circuitous way. The hot air furnace pipes 25 are socket pipes, which are connected to the regeneration wind boxes 24 in a socket-and-spigot manner, and a socket-and-spigot gap is provided, so that the hot air can overflow and ignite the combustibles in the resin sand to accelerate the decomposition of the resin film. Figure 2 As shown, a number of regeneration wind boxes 24 are arranged on both sides of the furnace chamber from bottom to top, namely No. 1 regeneration wind box, No. 2 regeneration wind box, No. 3 regeneration wind box, No. 4 regeneration wind box, No. 5 regeneration wind box, etc. A temperature regulating burner 14 is arranged at each end of the No. 1 regeneration wind box at the bottom of the bottom layer (see Figure 3 ), the high-temperature hot air flow generated by the two temperature-adjusting burners 14 enters from the two ends of the No. 1 regeneration wind box at the bottom of the furnace chamber, passes through the bottom hot blast furnace pipe 25 to reach the No. 2 regeneration wind box, the No. 2 regeneration wind box and the No. 3 regeneration wind box are on the same side and communicate with each other, and the hot air then passes through the closely arranged furnace pipes from the No. 3 regeneration wind box to reach the No. 4 regeneration wind box and the No. 5 regeneration wind box... In this way, the hot air flow rises through the hot blast furnace pipe 25 layer by layer, and the heat exchange time between the hot air flow and the resin sand is fully extended, so that a higher thermal efficiency can be obtained. The hot blast furnace pipe 25 has three detours per meter of height, so that the hot air (furnace gas) travels 2x3=6 meters per meter of height. If the height of the heating section of the hot blast furnace pipe 25 is 5 meters, the corresponding travel of the hot air is 30 meters. The hot air outlet 28 of the last regeneration bellows 24 at the top of the furnace chamber is connected to the drying bellows 8 under the screening and drying drum 4 through the hot air duct 9, so as to remove the moisture, mud and ash in the waste sand core, so that the heat energy can be fully utilized. The regeneration efficiency of the whole system is 30% higher than that of the current equipment.

[0033] The induced draft fan 21 is connected to the temperature-adjusting burner 14 through the temperature-adjusting air duct 13. The induced draft fan 21 filters the furnace gas containing VOCS and CO at the top of the furnace chamber through the bag filter and then blows it into the temperature-adjusting burner 14 at 1200 degrees through the temperature-adjusting air duct 13, so that the harmful gas is burned and decomposed. At the same time, the temperature-adjusting air output by the temperature-adjusting burner 14 drops to 900-1000°C and enters the No. 1 regeneration wind box, and begins to rise through the hot blast furnace pipe 25 as described above. The resin sand added from the feed port at the top of the furnace chamber slowly descends outside the hot blast furnace pipe 25 (less than 1mm / s), and the temperature rises layer by layer. When it reaches the high-temperature area of ​​the No. 1-4 regeneration wind boxes at the bottom, the sand temperature can reach 600-800°C, which is enough to decompose the resin film.

[0034] The temperature-adjusting burner 14 is connected to the gas pipe 15, and the temperature-adjusting burner 14 is connected to the outlet of the heat exchanger 16. The heat exchanger 16 adopts a tubular heat exchanger, especially a close-packed tube heat exchanger. The heat exchanger 16 is arranged in the furnace cylinder 27, and the furnace cylinder 27 is a regenerated sand cooling section. The heat exchanger 16 passes through the furnace shell (the middle part of the heat exchanger 16 is inside the furnace shell), and is heated by the heat in the furnace cavity to achieve heat exchange. The inlet of the heat exchanger 16 is connected to the combustion-supporting fan 29. The combustion-supporting fan 29 is connected to the temperature-adjusting burner 14 through the heat exchanger 16, and introduces external air into the heat exchanger 16. Through the heat exchange in the furnace shell, the air in the close-packed tubes in the heat exchanger 16 is preheated to form a higher temperature combustion-supporting wind. The high-pressure combustion-supporting wind of the temperature-adjusting burner 14 enters from the heat exchanger 16 passing through the furnace shell, which can cool the hot sand at the bottom of the furnace cavity while increasing the burner flame temperature, which can further improve the thermal efficiency. The bottom of the furnace is provided with a grid discharger 26, which is a speed-adjustable continuous discharger. The operation process of the roasting furnace 11 is as follows.

[0035] The waste sand core bulk material after magnetic separation enters the furnace cavity through the raw material bucket elevator 10, and the gas is introduced into the temperature-adjusting burner 14 through the gas pipe 15 and ignited. The combustion-supporting fan 29 introduces the external air into the heat exchanger 16, and the combustion-supporting air that performs heat exchange in the furnace shell enters the temperature-adjusting burner 14 to assist combustion. The hot air rises layer by layer from the regeneration wind box 24 and the hot air furnace pipe 25, and the waste sand core bulk material is added layer by layer and heated layer by layer during the descent process, and the resin is decomposed in the high-temperature section at the lower part of the furnace cavity. After the resin is decomposed, it is cooled layer by layer in the furnace cylinder. The tail gas from the terminal regeneration wind box 24 enters the screening and drying drum 4. The dust generated during the baking process is removed by the bag filter 12. The exhaust fan 21 introduces the exhaust gas generated by the bag filter 12 into the temperature-adjusting burner 14 through the temperature-adjusting air pipe 13, and further burns and decomposes to achieve zero VOCs emission. The sand particles that burn off the impurities enter the sand rubbing machine 18 for further dispersion. There must be a certain continuous material unloading speed in the furnace shell to ensure that the charge does not sinter and get stuck.

[0036] The equipment not mentioned in detail, such as the screening and drying drum 4, the magnetic separation belt conveyor, the bucket elevator, the bag dust collector, the temperature regulating burner 14, the sand rubbing machine 18, the belt conveyor 19, the grid discharger 26, etc., are all prior art.

[0037] The process of regenerating the waste sand core by the above system is as follows.

[0038] The waste sand cores in the waste sand core feeding hopper 1 enter the screening and drying drum 4 through the conveyor to crush and screen the resin sand. The hot air generated by the roasting furnace 11 enters the drying bellows 8 through the hot air duct 9, and then enters the screening and drying drum 4 through the drying bellows 8 to dry the waste sand cores in the screening process. During the screening process, the moisture, mud and ash powder in the waste sand cores are removed, and the generated dust and waste gas enter the bag dust collector 32 for treatment through the dust removal pipe interface 5, and the waste gas is discharged from the chimney 33. The waste sand core bulk material after screening and drying is discharged from the collecting hopper 2 and enters the magnetic separation device. The magnetic separation device removes the residual iron slag in the waste sand core bulk material and collects it through the residual iron receiving bucket 31. The waste sand core bulk material after magnetic separation enters the roasting furnace 11 through the raw material bucket elevator 10 for heating and regeneration, burns the non-sand components in the waste sand core bulk material, and then falls into the sand rubbing machine 18, and the cold air box 17 blows cold air into the sand rubbing machine 18 to cool the heated sand. The regenerated sand is discharged from the furnace bottom grid discharger 26 into the sand rubbing machine 18, and 30% of the original sand is added through the new sand adding belt conveyor 19. Because the temperature of the regenerated sand coming out of the furnace bottom is above 300°C, the moisture in the original sand will automatically evaporate, and it also plays a role in cooling. The mixed finished sand is transported to the finished sand bin 23 by the finished product bucket elevator 22.

Claims

1. A resin sand continuous thermal regeneration roasting furnace, characterized in that: The furnace shell includes three sections from top to bottom: a furnace throat, a furnace cavity and a furnace cylinder. An air inlet and a feed inlet are arranged at the upper part of the furnace cavity. The feed inlet is arranged at the furnace throat. The furnace throat is a furnace charge preheating section. The feed inlet is located below the air inlet. A furnace cylinder is arranged below the furnace cavity. Hot blast furnace pipes are arranged in layers along the axial direction in the furnace cavity. The hot blast furnace pipes of each layer are connected by regeneration wind boxes at both ends. A burner is installed in the regeneration wind box at the bottom. A temperature regulating air duct is connected between the burner and the air inlet at the upper part of the furnace cavity. The last regeneration wind box at the upper part of the furnace chamber is provided with a hot air outlet; The hot blast furnace pipe is a spigot-and-socket pipe, which is spigot-and-socket connected to the regeneration wind box, and a spigot-and-socket gap is provided; The waste sand core enters the furnace cavity from the feed port, and the high-temperature hot air flow enters from both ends of the regeneration wind box at the bottom of the furnace cavity. The hot air flow rises layer by layer through the hot air furnace tube and the regeneration air boxes on both sides, so that the heat exchange time between the hot air flow and the resin sand is fully extended. The waste sand runs from top to bottom in the furnace cavity, is heated and baked, and is cooled down layer by layer in the furnace cylinder and discharged.

2. The resin sand continuous thermal regeneration roasting furnace according to claim 1 is characterized in that: The hot blast furnace pipe rises in a circuitous manner along the axial direction of the furnace cavity.

3. A resin sand continuous thermal regeneration system, characterized by: The roasting furnace comprises the roasting furnace as claimed in any one of claims 1 and 2, and further comprises a screening and drying drum, a magnetic separation device, a raw material bucket elevator, a sand rubbing machine and a new sand adding belt conveyor, the screening and drying drum is connected to the hot air outlet of the roasting furnace through a hot air duct, a magnetic separation device is arranged below the screening and drying drum, the feed port and the discharge port of the raw material bucket elevator are respectively connected to the discharge port of the magnetic separation device and the feed port of the roasting furnace, a sand rubbing machine is arranged below the roasting furnace, and the discharge end of the new sand adding belt conveyor is connected to the sand rubbing machine; The waste sand cores first enter the screening and drying drum, and the hot air generated by the roasting furnace enters the screening and drying drum to dry the waste sand cores during the screening process and remove the moisture, mud, and ash in the waste sand cores; the waste sand core bulk materials after screening and drying enter the magnetic separation device to remove the residual iron slag in the waste sand core bulk materials; the waste sand core bulk materials after magnetic separation enter the roasting furnace through the raw material bucket elevator for heating and regeneration, and the regenerated sand and new sand are added to the new sand transported by the belt conveyor and enter the sand rubbing machine for mixing and enter the finished sand bin together.

4. The resin sand continuous thermal regeneration system according to claim 3 is characterized in that: The screening and drying drum is connected to the waste sand core feeding hopper through a conveyor, a collecting hopper is arranged at the bottom of the screening and drying drum, and the magnetic separation device is arranged below the collecting hopper.

5. The resin sand continuous thermal regeneration system according to claim 3 is characterized in that: A cold air box is arranged below the sand rubbing machine.

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