Drying furnace for coating magnesium oxide coating on silicon steel

Abstract

The utility model relates to a drying furnace for coating magnesium oxide on silicon steel, which comprises a magnesium oxide coating drying device for drying magnesium oxide coated on silicon steel; the fuel gas system comprises a main fuel gas device, an air-fuel ratio adjusting device and a combustion-supporting air device; the drying control system comprises a PLC (Programmable Logic Controller) control cabinet, an ignition transformer, a combustion controller, a heat exchange device and a heating cover shrinking mechanism; the drying furnace base comprises a middle supporting roller, a furnace body frame, an outlet rolling shaft rotating disc and a magnesium oxide filter, and the magnesium oxide coating drying device adopts an infrared radiation heater to dry magnesium oxide coated on silicon steel; and an air purging device is mounted at the rear section of the magnesium oxide coating drying device to purge and remove residual moisture of the silicon steel coating magnesium oxide. The drying furnace for the silicon steel coated magnesium oxide coating is convenient to mount, energy-saving, high in magnesium oxide coating drying efficiency and suitable for industrial batch production of the silicon steel coated magnesium oxide coating.

Description

Technical Field

[0001] The invention relates to the technical field of silicon steel production post-processing, and more specifically, to a drying furnace for silicon steel coated with magnesium oxide. Background Art

[0002] The uniform coating of magnesium oxide coating on silicon steel in the decarburization annealing unit has multiple functions. First, it prevents the interlayer adhesion of the rolled steel strip during high-temperature annealing. Second, when the high-temperature annealing temperature rises to about 1000℃, magnesium oxide reacts chemically with the SiO2 oxide film on the surface of the steel strip to form a glassy magnesium silicate bottom layer. The quality of this bottom layer has an important influence on the adhesion and insulation of the stress coating on the surface of silicon steel, and also affects the surface appearance quality of the finished product. Third, magnesium oxide reacts with sulfur to purify the steel during high-temperature insulation. Therefore, the coating of magnesium oxide isolation layer is of great significance to production. The coating liquid is mainly prepared by adding pure water to magnesium oxide, titanium dioxide, etc. In order to avoid excessive water, which makes the coating liquid easy to be scratched by the subsequent roller system, and to avoid water from being brought in to cause oxidation of the steel plate during high-temperature annealing, the free water needs to be dried in time after coating.

[0003] The existing coating liquid drying device is an open flame burner drying furnace. Since the silicon steel strip has a slightly boat-shaped characteristic, the quality of the laterally distributed magnesium oxide coating liquid is different, and the drying uniformity is affected by the burner distribution, making it difficult to dry the coating liquid. In addition, the thermal efficiency of the open flame burner drying furnace is low. To improve the efficiency, the temperature needs to be increased or the drying time needs to be increased. However, if the temperature is too high, the surface of the steel plate is easily oxidized by water; increasing the time requires reducing the unit speed, which also reduces production capacity; and the low thermal efficiency also increases energy waste. Therefore, there is an urgent need for a new device for drying silicon steel coated with magnesium oxide coating to improve the thermal efficiency of drying the magnesium oxide coating and shorten the drying cycle. Summary of the invention

[0004] In view of the above defects, the present invention adopts an infrared radiation heater to replace the open flame burner drying furnace. The use of natural gas is conducive to reducing electricity costs. The infrared radiation heater heats and dries the steel plate in a radiation heat exchange manner, which has higher thermal efficiency than the open flame burner heating, shortening the drying cycle. At the same time, the air purge device is installed in the rear section of the magnesium oxide coating drying device to purge the silicon steel coated with magnesium oxide to remove residual moisture, which also improves the drying efficiency of the magnesium oxide coating.

[0005] The present invention provides a silicon steel coating magnesium oxide coating drying furnace, comprising: a magnesium oxide coating drying device, which dries the silicon steel coated magnesium oxide; a fuel gas system, which comprises a main fuel gas device, an air-fuel ratio adjustment device, and a combustion-supporting air device; a drying control system, which comprises a PLC control cabinet, an ignition transformer, a combustion controller, a heat exchange device, and a heating cover retraction mechanism; and

[0006] The drying furnace base includes an intermediate support roller, a furnace frame, an exit roller turntable, and a magnesium oxide filter. The magnesium oxide coating drying device uses an infrared radiation heater to dry the magnesium oxide coated on the silicon steel. An air purge device is installed at the rear section of the magnesium oxide coating drying device to purge the magnesium oxide coated on the silicon steel to remove residual moisture.

[0007] According to an embodiment of the present invention, the temperature of the silicon steel coil before drying is 10-20°C, and the outlet temperature is 130-160°C.

[0008] According to an embodiment of the present invention, the infrared radiation heater is composed of a plurality of combined radiation modules.

[0009] According to an embodiment of the present invention, the combined radiation module comprises a rotary combustion unit, which performs infrared surface combustion of gas.

[0010] According to an embodiment of the present invention, the plurality of combined radiation modules matches the width of the silicon steel coil.

[0011] According to an embodiment of the present invention, the power of the infrared radiation heater is 3000kw - 4000kw.

[0012] According to an embodiment of the present invention, the air pressure of the air purge device is 2-4 gf / cm.

[0013] According to an embodiment of the present invention, the magnesium oxide coating on silicon steel is prepared by adding magnesium oxide, titanium dioxide and the like into pure water.

[0014] According to an embodiment of the present invention, the gas system heats the infrared radiation heater.

[0015] The present invention also provides a method for drying the silicon steel coated magnesium oxide coating by using the silicon steel coated magnesium oxide coating drying furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a drying furnace for silicon steel coated with magnesium oxide.

[0017] Figure 2 It is a partial schematic diagram of the air purge device of the drying furnace for silicon steel coated with magnesium oxide.

[0018] Figure 3 It is a schematic diagram of the structure of the magnesium oxide filter of the drying furnace for silicon steel coated with magnesium oxide.

[0019] Description of symbols

[0020] 1- Silicon steel coated magnesium oxide coating drying furnace; 11- Magnesium oxide coating drying device; 111- Infrared radiation heater; 112- Air purge device; 12- Gas system; 121- Main gas device; 122- Air-fuel ratio adjustment device; 123- Combustion-supporting air device; 13- Drying control system; 131- PLC control cabinet; 132- Ignition transformer; 133- Combustion controller; 134- Heat exchange device; 135- Heating hood retraction mechanism; 14- Drying furnace base; 141- Middle support roller; 142- Furnace frame; 143- Export roller turntable; 144- Magnesium oxide filter. Implementation

[0021] The following will be combined with the drawings in the specific embodiments of the present invention to clearly and completely describe the technical solutions in the specific embodiments of the present invention. Obviously, the specific embodiment described is only one specific embodiment of the present invention, not all specific embodiments. Based on the specific embodiments of the present invention, all other specific embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The reason for setting an air purge device in the drying furnace for coating magnesium oxide on silicon steel of the present invention is now explained. The method for forming a uniform glassy magnesium silicate bottom layer on the surface of an oriented silicon steel sheet is to selectively oxidize the silicon steel sheet during the decarburization annealing process so that the silicon on its surface generates silicon dioxide flakes. Then, the magnesium oxide slurry is uniformly coated on the surface of the steel sheet, and after drying, it is finally treated in a high-temperature annealing furnace so that the magnesium oxide reacts with the silicon dioxide flakes on the surface of the steel sheet to form a glassy insulating film, i.e., the magnesium silicate bottom layer. After the magnesium oxide slurry coated on the surface of the steel sheet is dried in the drying furnace, the free water is basically eliminated, but the chemical water Mg(OH) 2 But it is brought into the bell-type furnace. When the furnace is heated, moisture will be released. In order to fully remove the moisture in the furnace, it is necessary to keep it warm for a long time at a lower temperature, which prolongs the operation cycle and increases energy consumption. If the moisture is not removed at a low temperature, the steel plate will oxidize and cannot form a good bottom layer, or "dew crystals" or "speckled faces" will appear. The fluctuation or high moisture content of magnesium oxide will cause the moisture brought into the bell-type furnace to fluctuate or increase. Under high temperature conditions, the uneven evaporation of chemical water or the increase in evaporation will lead to uneven accumulation of moisture in the narrow gaps of steel sheets, blocking the normal circulation of gas in the furnace, causing local excessive oxidation or uneven vaporization of steel sheets, and ultimately hindering the formation of glassy insulating films, thereby weakening the mechanical properties and magnetic conductivity of silicon steel coils. An air purge device is set at the rear section of the magnesium oxide coating drying device to remove moisture from the magnesium oxide slurry after drying through air power. Embodiment 1

[0023] The magnesium oxide coating drying device 11 in the magnesium oxide coating drying furnace 1 for silicon steel of the present invention adopts 18 infrared radiation heaters 111, each burner has a power of 210kw, each infrared radiation heater 111 includes 20 combined radiation modules, and each combined radiation module has a power of 3780kw. The air pressure of the air purge device 112 is 2.4gf / cm. The temperature of the silicon steel coil before drying is 15°C.

[0024] The gas system 12 is turned on, and the main gas device 121 is ignited to heat the infrared radiation heater 111. At the same time, the air-fuel ratio adjustment device 122 is turned on to adjust the air-fuel ratio to 11:1 according to the power of the infrared radiation heater 111, and the combustion air device 123 uses oxygen. The PLC control cabinet 131 controls the start and shut down of the magnesium oxide coating drying device 11 and the gas system 12. The ignition transformer 132 ignites the gas in the main gas device 121, and then the controller controls the heat exchange device 134 and the heating cover retraction mechanism 135 to provide drying assistance to the magnesium oxide coating drying device 11. After the drying starts, the middle support roller 141 of the drying furnace base 14 and the exit roller turntable start to rotate to drive the silicon steel coil, and a silicon steel coil with a length of 500 meters and a ton is selected to enter the magnesium oxide coating drying device 11. Since the magnesium oxide coating on silicon steel is prepared by adding pure water to magnesium oxide, titanium dioxide, etc., when the silicon steel coil first enters the magnesium oxide coating drying device 11, the magnesium oxide coating on the surface of the silicon steel is in a mud state, and the gas system 12 starts to heat the infrared radiation heater 111, and the infrared radiation heater 111 radiates and dries the magnesium oxide coating on the silicon steel in a mud state, and the temperature of the silicon steel coil gradually rises. At the same time, the magnesium oxide filter 144 is started to filter and dry the magnesium oxide powder emitted by the magnesium oxide coating on the silicon steel. The air purge device 112 set in the rear section of the magnesium oxide coating drying device 11 starts to purge the silicon steel coil to remove the evaporated water. After the silicon steel coil rotates in the magnesium oxide coating drying furnace 1 for 1 hour, the outlet temperature of the silicon steel coil is 135°C, and the magnesium oxide filtered by the magnesium oxide filter 144 is 5 kg. Under the same conditions, the magnesium oxide filtered by the magnesium oxide filter 144 in the open flame burner drying furnace is 3.8 kg.

[0025] Compared with the open flame burner drying furnace of the prior art, the heating temperature rise rate of the present invention is 12% higher; under the same gas consumption, the drying / heating capacity is increased by 10%; and the drying surface temperature of the silicon steel coil is uniform. Embodiment 2

[0026] The magnesium oxide coating drying device 11 in the magnesium oxide coating drying furnace 1 for silicon steel of the present invention adopts 18 infrared radiation heaters 111, each burner has a power of 210kw, each infrared radiation heater 111 includes 5 combined radiation modules, and each combined radiation module has a power of 3780kw. The air pressure of the air purge device 112 is 3.2gf / cm. The temperature of the silicon steel coil before drying is 16°C.

[0027] The gas system 12 is turned on, and the main gas device 121 is ignited to heat the infrared radiation heater 111. At the same time, the air-fuel ratio adjustment device 122 is turned on to adjust the air-fuel ratio to 11:1.3 according to the power of the infrared radiation heater 111, and the combustion air device 123 uses oxygen. The PLC control cabinet 131 controls the start and shut down of the magnesium oxide coating drying device 11 and the gas system 12. The ignition transformer 132 ignites the gas in the main gas device 121, and then the controller controls the heat exchange device 134 and the heating cover retraction mechanism 135 to provide drying assistance to the magnesium oxide coating drying device 11. After the drying starts, the middle support roller 141 of the drying furnace base 14 and the exit roller turntable start to rotate to drive the silicon steel coil, and the silicon steel coil with a length of 1000 meters and 2.1 tons is selected to enter the magnesium oxide coating drying device 11. Since the magnesium oxide coating on silicon steel is prepared by adding pure water to magnesium oxide, titanium dioxide, etc., when the silicon steel coil first enters the magnesium oxide coating drying device 11, the magnesium oxide coating on the surface of the silicon steel is in a mud state, and the gas system 12 starts to heat the infrared radiation heater 111, and the infrared radiation heater 111 radiates and dries the magnesium oxide coating on the silicon steel in a mud state, and the temperature of the silicon steel coil gradually rises. At the same time, the magnesium oxide filter 144 is started to filter and dry the magnesium oxide powder emitted by the magnesium oxide coating on the silicon steel. The air purge device 112 set in the rear section of the magnesium oxide coating drying device 11 starts to purge the silicon steel coil to remove the evaporated water. After the silicon steel coil rotates in the magnesium oxide coating drying furnace 1 for 1 hour, the outlet temperature of the silicon steel coil is 135°C, and the magnesium oxide filtered by the magnesium oxide filter 144 is 7.3 kg. Under the same conditions, the magnesium oxide filtered by the magnesium oxide filter 144 in the open flame burner drying furnace is 5.9 kg.

[0028] Compared with the open flame burner drying furnace of the prior art, the heating temperature rise rate of the present invention is 14% higher; under the same gas consumption, the drying / heating capacity is increased by 11%; and the drying surface temperature of the silicon steel coil is uniform. Embodiment 3

[0029] The magnesium oxide coating drying device 11 in the magnesium oxide coating drying furnace 1 for silicon steel of the present invention adopts 18 infrared radiation heaters 111, each burner has a power of 210kw, each infrared radiation heater 111 includes 5 combined radiation modules, and each combined radiation module has a power of 3780kw. The air pressure of the air purge device 112 is 3.9gf / cm. The temperature of the silicon steel coil before drying is 18°C.

[0030] The gas system 12 is turned on, and the main gas device 121 is ignited to heat the infrared radiation heater 111. At the same time, the air-fuel ratio adjustment device 122 is turned on to adjust the air-fuel ratio to 11:1.7 according to the power of the infrared radiation heater 111, and the combustion air device 123 uses oxygen. The PLC control cabinet 131 controls the start and shut down of the magnesium oxide coating drying device 11 and the gas system 12. The ignition transformer 132 ignites the gas in the main gas device 121, and then the controller controls the heat exchange device 134 and the heating cover retraction mechanism 135 to provide drying assistance to the magnesium oxide coating drying device 11. After the drying starts, the middle support roller 141 of the drying furnace base 14 and the exit roller turntable start to rotate to drive the silicon steel coil, and the silicon steel coil with a length of 1500 meters and 3.4 tons is selected to enter the magnesium oxide coating drying device 11. Since the magnesium oxide coating on silicon steel is prepared by adding pure water to magnesium oxide, titanium dioxide, etc., when the silicon steel coil first enters the magnesium oxide coating drying device 11, the magnesium oxide coating on the surface of the silicon steel is in a mud state, and the gas system 12 starts to heat the infrared radiation heater 111, and the infrared radiation heater 111 radiates and dries the magnesium oxide coating on the silicon steel in a mud state, and the temperature of the silicon steel coil gradually rises. At the same time, the magnesium oxide filter 144 is started to filter and dry the magnesium oxide powder emitted by the magnesium oxide coating on the silicon steel. The air purge device 112 set in the rear section of the magnesium oxide coating drying device 11 starts to purge the silicon steel coil to remove the evaporated water. After the silicon steel coil rotates in the magnesium oxide coating drying furnace 1 for 1 hour, the outlet temperature of the silicon steel coil is 135°C, and the magnesium oxide filtered by the magnesium oxide filter 144 is 9.5 kg. Under the same conditions, the magnesium oxide filtered by the magnesium oxide filter 144 in the open flame burner drying furnace is 7.9 kg.

[0031] Compared with the open flame burner drying furnace of the prior art, the heating temperature rise rate of the present invention is 13% higher; under the same gas consumption, the drying / heating capacity is increased by 13%; and the drying surface temperature of the silicon steel coil is uniform.

[0032] After the transformation, the average natural gas consumption of the silicon steel magnesium oxide coating drying furnace 1 of the present invention is reduced by 40 cubic meters per hour. Calculated based on 7,000 working hours per year, 280,000 cubic meters of natural gas can be saved per year, which is equivalent to saving 372 tons of standard coal per year.

[0033] The above disclosure is only a preferred embodiment of the present invention, and certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention. Although the specific embodiments of the present invention have been shown and described, it is understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these specific embodiments without departing from the principles and spirit of the invention, and the scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A drying furnace for coating silicon steel with magnesium oxide, comprising: A magnesium oxide coating drying device, wherein the magnesium oxide coating drying device dries the magnesium oxide coating on the silicon steel; A gas system, the gas system comprising a main gas device, an air-fuel ratio adjustment device, and a combustion-supporting air device; A drying control system, the drying control system comprising a PLC control cabinet, an ignition transformer, a combustion controller, a heat exchange device, and a heating cover retraction mechanism; and The drying furnace base includes an intermediate support roller, a furnace frame, an outlet roller turntable, and a magnesium oxide filter, and is characterized in that: The magnesium oxide coating drying device uses an infrared radiation heater to dry the magnesium oxide coated on the silicon steel, and an air purge device is installed at the rear section of the magnesium oxide coating drying device to purge the magnesium oxide coated on the silicon steel to remove residual moisture.

2. The drying furnace for coating silicon steel with magnesium oxide according to claim 1, characterized in that: The temperature of silicon steel coil before drying is 10-20℃, and the outlet temperature is 130-160℃.

3. The drying furnace for coating silicon steel with magnesium oxide according to claim 1, characterized in that: The infrared radiation heater is composed of a plurality of combined radiation modules.

4. The drying furnace for coating silicon steel with magnesium oxide according to claim 3, characterized in that: The combined radiation module comprises a rotary combustion unit, which performs infrared surface combustion of gas.

5. The drying furnace for coating silicon steel with magnesium oxide according to claim 3, characterized in that: The plurality of combined radiation modules match the width of the silicon steel coil.

6. The drying furnace for coating silicon steel with magnesium oxide according to claim 1, characterized in that: The power of the infrared radiation heater is 3000kw-4000kw.

7. The drying furnace for coating silicon steel with magnesium oxide according to claim 1, characterized in that: The air pressure of the air purge device is 2-4 gf / cm.

8. The drying furnace for coating silicon steel with magnesium oxide according to claim 1, characterized in that: The gas system heats the infrared radiation heater.

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