System and method for improving cooling capacity of silicon steel continuous annealing furnace

Abstract

The invention belongs to the technical field of heat resource utilization of silicon steel continuous annealing furnaces, and particularly relates to a system and method for improving the cooling capacity of a silicon steel continuous annealing furnace. The system comprises a silicon steel continuous annealing furnace and a refrigeration unit, the silicon steel continuous annealing furnace is used for carrying out continuous decarburization annealing treatment on steel and comprises a protective gas circulating cooling section; and the refrigeration unit is used for carrying out combustion heat exchange on nitrogen-hydrogen mixed gas discharged by the silicon steel continuous annealing furnace to prepare cold water, conveying the prepared cold water into the protective gas circulating cooling section, and cooling circulating protective gas in the protective gas circulating cooling section by using the cold water. The system fully utilizes hydrogen combustion heat and mixed gas sensible heat lost by diffusion of the silicon steel continuous annealing furnace end to solve the problem of insufficient cooling capacity of the cooling section after temperature rise and acceleration of the process section, has the advantages of energy conservation and consumption reduction, and plays a positive role in reducing the temperature of a discharged plate, reducing damage of a roller system behind the furnace, ensuring smooth production and reducing the dew point of the cooling section.

Description

Technical Field

[0001] The invention belongs to the technical field of heat resource utilization of a silicon steel continuous annealing furnace, and specifically relates to a system and method for improving the cooling capacity of a silicon steel continuous annealing furnace. Background Art

[0002] The silicon steel horizontal continuous annealing furnace is used for decarburization annealing of silicon steel strip after cold rolling. The furnace is a reducing atmosphere, and the protective gas used is a nitrogen-hydrogen mixed gas. The nitrogen-hydrogen mixed gas enters from the tail of the heating section of the silicon steel continuous annealing furnace. After decarburization, the excess high-temperature mixed gas is discharged from the furnace head vent, and the hydrogen is burned. The existing silicon steel continuous annealing furnace has no heat recovery device for the hydrogen combustion heat and the sensible heat of the mixed gas released from the furnace head. All the heat is dissipated in the workshop, which not only wastes a lot of energy, but also increases the workshop temperature and worsens the working environment.

[0003] Silicon steel continuous annealing furnace protective gas circulation jet cooler (RJC) is used to cool the strip after heating. It is usually composed of a controlled cooling section (SRJC) and a rapid cooling section (RRJC). The controlled cooling section is usually composed of 5 to 8 sections, and the rapid cooling section is usually composed of 7 to 18 sections. Figure 1 As shown, each section consists of a furnace shell, a spray box, a circulating air duct, a circulating fan and a heat exchanger. When working, driven by the circulating fan, the nitrogen in the RJC is sprayed on the surface of the strip, and after carrying away the heat, it enters the heat exchanger to exchange heat with the circulating cooling water, and finally the heat of the strip is taken away by the circulating cooling water. The controlled cooling section controls the cooling speed of the strip by adjusting the air volume, so that the strip is cooled according to the process speed; the air volume of the fast cooling section is not adjustable, and the maximum air volume is always used for circulating spray cooling of the strip, and it is quickly cooled to below 200°C. With the increasing demand for high-grade silicon steel, higher requirements are placed on the process temperature of the heating section and the process speed of the strip. Many continuous annealing furnaces have insufficient cooling capacity, resulting in excessively high strip temperature out of the furnace, damage to the roller system after the furnace, and affect the smooth production. It may even limit the upper limit of the temperature and speed of the process section, affect the coating process after the furnace, and have an adverse effect on the magnetic properties and surface quality of silicon steel.

[0004] The prior art "201620722143.8" discloses a waste heat utilization device for the furnace head of a continuous annealing furnace for oriented silicon steel. The waste heat utilization device is arranged inside the furnace head, and includes a heater and a heat preservation device arranged outside the heater. A fixing device is also provided outside the heat preservation device, which can fully absorb the heat generated by the combustion of hydrogen in the furnace head. The absorbed heat can be transported to the drying furnace through a pipeline and used for drying the steel strip after cleaning, replacing steam heating to dry the steel strip, thereby saving a lot of energy, reducing production costs, and reducing the workshop temperature and improving the working environment. This patent directly uses the heat generated by the combustion of hydrogen for the drying of the cleaning section steel strip, and does not mention how to improve the cooling capacity of the silicon steel continuous annealing furnace. Summary of the invention

[0005] The purpose of the present invention is to address the large amount of heat energy wasted by the silicon steel continuous annealing furnace in the prior art, and to urgently improve the cooling capacity of the silicon steel continuous annealing furnace. However, there is currently a lack of technology that effectively combines the heat energy generated by the silicon steel continuous annealing furnace with the cooling process of the silicon steel continuous annealing furnace, thereby proposing a system and method for improving the cooling capacity of the silicon steel continuous annealing furnace. The system includes a silicon steel continuous annealing furnace and a refrigeration unit, and the high-temperature nitrogen-hydrogen mixed gas discharged from the silicon steel continuous annealing furnace is transported to the refrigeration unit for heat exchange to prepare cold water, and the prepared cold water replaces the circulating cooling water of the protective gas circulating cooling section in the silicon steel continuous annealing furnace, and the prepared cold water is used to cool the circulating protective gas in the silicon steel continuous annealing furnace. The system of the present invention makes full use of the hydrogen combustion heat and the sensible heat of the mixed gas released by the silicon steel continuous annealing furnace head to solve the problem of insufficient cooling capacity of the cooling section after the process section is heated and accelerated, and has the advantages of energy saving and consumption reduction, and has a positive effect on reducing the temperature of the furnace-out board, reducing the damage to the roller system behind the furnace, ensuring smooth production, and reducing the dew point of the cooling section.

[0006] The first aspect of the present invention proposes a system for improving the cooling capacity of a silicon steel continuous annealing furnace, the system comprising a silicon steel continuous annealing furnace and a refrigeration unit; the silicon steel continuous annealing furnace is used to perform continuous decarburization annealing treatment on steel, and the silicon steel continuous annealing furnace comprises a protective gas circulation cooling section; the refrigeration unit is used to burn and exchange heat between the nitrogen-hydrogen mixed gas discharged from the silicon steel continuous annealing furnace to produce cold water, and the produced cold water is transported to the protective gas circulation cooling section, and the circulating protective gas in the protective gas circulation cooling section is cooled by the cold water.

[0007] Preferably, the refrigeration unit has an outlet, an inlet and a smoke exhaust port; the outlet is used to transport the cold water produced by the refrigeration unit to the protective gas circulation cooling section through a connecting pipe; the inlet is used to transport the cold water used to cool the circulating protective gas in the protective gas circulation cooling section to the refrigeration unit through a connecting pipe; the smoke exhaust port is used to discharge the nitrogen-hydrogen mixed gas after combustion and heat exchange.

[0008] More preferably, the protective gas circulation cooling section includes a controlled cooling section and a rapid cooling section, and the heated steel is cooled in the controlled cooling section and the rapid cooling section in sequence, and the controlled cooling section and the rapid cooling section are both composed of a number of interconnected cooling units; the refrigeration unit transports the produced cold water to a part of the cooling units in the controlled cooling section and / or the rapid cooling section, and the circulating cooling water in a part of the cooling units in the controlled cooling section and / or the rapid cooling section is replaced by the input cold water.

[0009] Further preferably, before hydrogen is added to the drying furnace, the circulating cooling water replaced by cold water in a part of the cooling units of the controlled cooling section and / or the rapid cooling section continues to cool the circulating protective gas in a part of the cooling units of the controlled cooling section and / or the rapid cooling section, and another part of the cooling units of the controlled cooling section and / or the rapid cooling section cools the circulating protective gas with the circulating cooling water therein; after hydrogen is added to the drying furnace, the circulating protective gas in a part of the cooling units of the controlled cooling section and / or the rapid cooling section is cooled by the input cold water, and another part of the cooling units of the controlled cooling section and / or the rapid cooling section continues to cool the circulating protective gas with the circulating cooling water therein.

[0010] Further preferably, the system also includes a first cooling device, which is used to cool the circulating cooling water in another part of the cooling unit of the controlled cooling section and / or the fast cooling section, and continue to transport the cooled circulating cooling water to another part of the cooling unit of the controlled cooling section and / or the fast cooling section.

[0011] More preferably, the system further comprises a second cooling device, wherein the second cooling device is used for conveying cooling water to the refrigeration unit, and utilizing the cooling water to circulate and cool the refrigeration unit.

[0012] More preferably, the circulating cooling water replaced by cold water in a part of the cooling units of the controlled cooling section and / or the fast cooling section is transported to the first cooling device through a pipeline for cooling, and the cooled circulating cooling water replaced by cold water is further transported to the refrigeration unit, and the refrigeration unit is circulated and cooled by the cooled circulating cooling water replaced by cold water.

[0013] The second aspect of the present invention proposes a method for improving the cooling capacity of a silicon steel continuous annealing furnace according to the above-mentioned system, the method comprising: transporting the nitrogen-hydrogen mixed gas discharged from the silicon steel continuous annealing furnace to a refrigeration unit for combustion and heat exchange to produce cold water, transporting the cold water to the protective gas circulating cooling section of the silicon steel continuous annealing furnace, and using the cold water to replace the original circulating cooling water in the protective gas circulating cooling section to cool the circulating protective gas in the protective gas circulating cooling section.

[0014] Preferably, the cold water flow rate produced by the refrigeration unit is 0.8 to 1.2 times the sum of the original circulating cooling water flow rates in the cooling units replaced by the cold water in the protective gas circulating cooling section; the cooling capacity of the refrigeration unit is ≥ 1.3 times the sum of the cooling capacities required for cooling by the original circulating cooling water in the cooling units replaced by the cold water.

[0015] Preferably, the nitrogen-hydrogen mixed gas with a temperature ≥750°C discharged from the silicon steel continuous annealing furnace is transported to a refrigeration unit for combustion and heat exchange to produce cold water; the energy efficiency ratio of the refrigeration unit is ≥1.4; and the temperature of the flue gas discharged from the refrigeration unit is ≤250°C.

[0016] The system and method for improving the cooling capacity of a silicon steel continuous annealing furnace according to the present invention have at least the following beneficial effects:

[0017] (1) The system of the present invention makes full use of the heat energy lost by the mixed gas released by the silicon steel continuous annealing furnace, transports the high-temperature nitrogen-hydrogen mixed gas discharged from the silicon steel continuous annealing furnace to the refrigeration unit for heat exchange to prepare cold water, and uses the prepared cold water to replace the original circulating cooling water in the protective gas circulating cooling section of the silicon steel continuous annealing furnace, and uses the prepared cold water to cool the circulating protective gas in the silicon steel continuous annealing furnace. The system has a significant energy-saving effect, solves the problem that the cooling capacity of the cooling section is insufficient after the temperature of the silicon steel continuous annealing furnace process section is increased, reduces the temperature of the strip out of the furnace, reduces the damage to the roller system after the furnace, and ensures smooth production. It has beneficial effects on reducing the dew point of the cooling section, ensuring the heating temperature and speed of the process section meet the standards, stabilizing the coating process after the furnace, and ensuring the performance and surface quality of silicon steel;

[0018] (2) In the present invention, the existing circulating cooling water system capacity of the protective gas circulating cooling section in the silicon steel continuous annealing furnace is fully utilized, and the cooling water for circulating cooling in the refrigeration unit is supplemented by the original circulating cooling water in the protective gas circulating cooling section replaced by the cold water produced by the refrigeration unit, thereby reducing the land occupation and construction cost of the circulating cooling water system of the newly built refrigeration unit; at the same time, the cold water produced by the refrigeration unit enters and exits the refrigeration unit through the circulating cooling water branch pipe of the replaced section of the protective gas circulating cooling section, thereby making the best use of the existing equipment conditions and reducing the transformation investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a silicon steel continuous annealing furnace in the prior art;

[0020] Figure 2 It is a structural schematic diagram of the system for improving the cooling capacity of a silicon steel continuous annealing furnace in the present invention.

[0021] Reference numerals

[0022] 1. Silicon steel continuous annealing furnace; 2. Refrigeration unit; 3. Protective gas circulation cooling section; 4. Exit; 5. Inlet; 6. Controlled cooling section; 7. Quick cooling section; 8. First cooling device; 9. Second cooling device; 10. Heating section; 11. Vent; 12. Air cooling section; 13. Cooling unit; 14. Smoke exhaust port. DETAILED DESCRIPTION

[0023] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0024] The first aspect of the present invention provides a system for improving the cooling capacity of a silicon steel continuous annealing furnace, such as Figure 2 As shown, the system includes a silicon steel continuous annealing furnace 1 and a refrigeration unit 2; the silicon steel continuous annealing furnace 1 is used to perform continuous decarburization annealing treatment on steel, and the silicon steel continuous annealing furnace 1 includes a protective gas circulating cooling section 3; the refrigeration unit 2 is used to burn and exchange heat with the nitrogen-hydrogen mixed gas discharged from the silicon steel continuous annealing furnace 1 to produce cold water, and the produced cold water is transported to the protective gas circulating cooling section 3, and the circulating protective gas in the protective gas circulating cooling section 3 is cooled by the cold water (replacing the original circulating cooling water in the protective gas circulating cooling section 3).

[0025] In a specific embodiment of the system of the present invention, the silicon steel continuous annealing furnace 1 has a heating section 10, an air cooling section 12 and a protective gas circulating cooling section 3. In a specific implementation process, the heating section 10 is used to heat the cold-rolled steel to the temperature required for decarburization annealing. After the decarburization reaction is completed, the air cooling section uses cooling air to spray on the surface of the steel for preliminary cooling, and then the steel after preliminary cooling is cooled again in the protective gas circulating cooling section 3 by using protective gas spray. The circulating cooling water in the protective gas circulating cooling section 3 cools the protective gas; the cooling rate of the air cooling section 12 is lower than the cooling rate of the protective gas circulating cooling section 3; the purpose of the air cooling section 12 and the protective gas circulating cooling section 3 is to optimize the annealing process and ensure the quality and performance of the steel.

[0026] In a specific embodiment of the system of the present invention, a vent 11 is provided at the furnace head of the silicon steel continuous annealing furnace, i.e., the heating section 10, and the nitrogen-hydrogen mixed gas is discharged from the vent 11. The refrigeration unit 2 is used for exchanging heat with the nitrogen-hydrogen mixed gas discharged from the vent 11 to produce cold water.

[0027] In a specific embodiment of the system of the present invention, the refrigeration unit 2 is a direct-fired bromide refrigerator, and the nitrogen-hydrogen mixed gas discharged from the silicon steel continuous annealing furnace 1 is heat exchanged in the regenerator of the direct-fired bromide refrigerator to produce cold water. The regenerator of the direct-fired bromide refrigerator has a smoke exhaust port 14. Specifically, the exhaust temperature of the regenerator is ≤250°C.

[0028] In a specific embodiment of the system of the present invention, the refrigeration unit 2 has an outlet 4 and an inlet 5; the outlet 4 is used to transport the cold water produced by the refrigeration unit 2 to the protective gas circulation cooling section 3 through a connecting pipe; the inlet 5 is used to transport the cold water after cooling the circulating protective gas in the protective gas circulation cooling section 3 to the refrigeration unit 2 through a connecting pipe, and the cold water circulates in the refrigeration unit 2 and the protective gas circulation cooling section 3.

[0029] In a specific embodiment of the system of the present invention, the straight-line distance between the refrigeration unit 2 and the protective gas circulation cooling section 3 does not exceed 150 m, so as to minimize the heat loss of the produced cold water transported through the pipeline.

[0030] In a specific embodiment of the system of the present invention, the protective gas circulation cooling section 3 includes a controlled cooling section 6 and a rapid cooling section 7, the heated steel is cooled in the controlled cooling section 6 and the rapid cooling section 7 in turn, the controlled cooling section 6 and the rapid cooling section 7 are both composed of a plurality of connected cooling units 13, the refrigeration unit 2 transports the produced cold water to a part of the cooling units 13 of the controlled cooling section 6 and / or the rapid cooling section 7, and the circulating cooling water in a part of the cooling units 13 of the controlled cooling section 6 and / or the rapid cooling section 7 is replaced by the input cold water; in actual operation, to which parts is the cold water produced by the refrigeration unit 2 transported? In the cooling unit 13 of the section, the circulating protective gas is cooled by replacing the original circulating cooling water in the cooling unit 13. The specific position of the replaced cooling unit 13 is determined according to the requirements of the strip cooling process. Specifically, for example, if the annealing process requires the strip to be cooled quickly after heating, and the cooling capacity of the cooling unit at the front end of the controlled cooling section is insufficient, the prepared cold water can replace the circulating cooling water of the cooling unit at the front end of the controlled cooling section; if only the outlet temperature of the strip needs to be ensured, and the cooling capacity of the cooling unit at the rear end of the rapid cooling section cannot meet the requirements, the prepared cold water can replace the circulating cooling water of the cooling unit at the rear end of the rapid cooling section.

[0031] In a specific embodiment of the system described in the present invention, the original pipeline of the replaced circulating cooling water in the protective gas circulating cooling section 3 is fully retained. Before hydrogen is added to the drying furnace, the circulating cooling water replaced by cold water in a part of the cooling units 13 of the controlled cooling section 6 and / or the rapid cooling section 7 continues to cool the circulating protective gas in a part of the cooling units 13 of the controlled cooling section 6 and / or the rapid cooling section 7, and another part of the cooling units 13 of the controlled cooling section 6 and / or the rapid cooling section 7 uses the circulating cooling water therein to cool the circulating protective gas; after hydrogen is added to the drying furnace, the circulating protective gas in a part of the cooling units 13 of the controlled cooling section 6 and / or the rapid cooling section 7 is cooled by the input cold water, and another part of the cooling units 13 of the controlled cooling section 6 and / or the rapid cooling section 7 continues to cool the circulating protective gas with the circulating cooling water therein. In this article, "hydrogen addition to the drying furnace" means that before the continuous annealing furnace is officially put into production, the drying furnace needs to be slowly heated up, and hydrogen can be added to the furnace only when the furnace temperature reaches a certain requirement. In actual operation, the bromide refrigeration machine needs to burn exhaust gas to produce cooling water. If there is no hydrogen combustion before hydrogen is added, cooling water cannot be produced. Only after hydrogen is added can cooling water be produced.

[0032] In a specific embodiment of the system of the present invention, the system also includes a first cooling device 8, which is used to cool the circulating cooling water in another part of the cooling unit 13 of the controlled cooling section 6 and / or the fast cooling section 7, and continue to transport the cooled circulating cooling water to another part of the cooling unit 13 of the controlled cooling section 6 and / or the fast cooling section 7. Specifically, the first cooling device 8 is a cooling tower.

[0033] In a specific embodiment of the system of the present invention, the system also includes a second cooling device 9, which is used to transport cooling water to the refrigeration unit 2, use the cooling water to circulate and cool the refrigeration unit 2, and then transport the cooling water after circulating and cooling the refrigeration unit 2 to the second cooling device 9 for cooling. Specifically, the second cooling device 9 is a cooling tower, and the second cooling device 9 is the cooling system of the refrigeration unit 2.

[0034] In a preferred embodiment of the system of the present invention, the circulating cooling water replaced by cold water in a part of the cooling units 13 of the controlled cooling section 6 and / or the fast cooling section 7 is transported to the first cooling device 8 through a pipeline for cooling, and the cooled circulating cooling water replaced by cold water is further transported to the refrigeration unit 2, and the refrigeration unit 2 is circulated and cooled by the cooled circulating cooling water replaced by cold water, so that the cooled circulating cooling water replaced by cold water serves as a supplement to the cooling water in the second cooling device 9.

[0035] The specific operation process of the system for improving the cooling capacity of the silicon steel continuous annealing furnace described in the present invention is as follows: the cold-rolled steel is heated to the temperature required for decarburization annealing in the heating section 10 and the decarburization reaction is completed. After decarburization, the excess high-temperature nitrogen-hydrogen mixed gas is discharged from the vent 11, and the nitrogen-hydrogen mixed gas discharged from the vent 11 is transported to the refrigeration unit 2. The nitrogen-hydrogen mixed gas is heat-exchanged in the regenerator of the refrigeration unit 2 to produce cold water. The protective gas circulation cooling section 3 includes a controlled cooling section 6 and a rapid cooling section 7. The controlled cooling section 6 and the rapid cooling section 7 are both composed of a number of connected cooling units 13. The cold water produced in the regenerator of the refrigeration unit 2 is transported to the controlled cooling section 6 and / or the rapid cooling section 7 through the outlet 4 and the connecting pipeline. The specific number of cooling units 13 to which the cold water is transported is determined according to the requirements of the strip cooling process, so as to transport it to The cold water in the cooling unit 13 replaces the original circulating cooling water in the controlled cooling section 6 and the fast cooling section 7 to cool the protective gas. The cold water after cooling the protective gas is transported to the refrigeration unit 2 through the inlet 5 and the connecting pipe. The cooling units 13 in the controlled cooling section 6 and the fast cooling section 7 that do not transport cold water continue to cool the protective gas with the original circulating cooling water, and transport the original circulating cooling water after cooling the protective gas to the first cooling device 8 for cooling. Then, the cooled original circulating cooling water continues to be transported to the cooling units 13 that are not replaced by cold water. The original circulating cooling water in the cooling units 13 replaced by cold water is transported from the first cooling device 8 to the refrigeration unit 2, and the refrigeration unit 2 is circulated and cooled using the original circulating cooling water replaced by cold water.

[0036] The second aspect of the present invention proposes a method for improving the cooling capacity of a silicon steel continuous annealing furnace according to the above-mentioned system, the method comprising: transporting the nitrogen-hydrogen mixed gas discharged from the silicon steel continuous annealing furnace 1 to a refrigeration unit 2 for combustion and heat exchange to produce cold water, transporting the cold water to the protective gas circulating cooling section 3 of the silicon steel continuous annealing furnace 1, and using the cold water to replace the original circulating cooling water in the protective gas circulating cooling section 3 to cool the circulating protective gas in the protective gas circulating cooling section 3.

[0037] In a specific implementation of the method of the present invention, the flow rate of cold water produced by the refrigeration unit 2 is 0.8 to 1.2 times the sum of the flow rates of the original circulating cooling water in the cooling unit 13 replaced by the cold water in the protective gas circulating cooling section 3. If it is less than 0.8 times, the heat exchange of the evaporator of the bromide refrigerator will be insufficient, affecting the refrigeration capacity of the bromide refrigerator. If it is greater than 1.2 times, the temperature of the produced cold water will increase, affecting the cooling capacity of the protective gas circulating cooling section and increasing the energy consumption of the cold water pump group.

[0038] In a specific implementation of the method of the present invention, the cooling capacity of the refrigeration unit 2 is ≥ 1.3 times the sum of the cooling capacities required for cooling the original circulating cooling water in the cooling unit 13 replaced by the cold water. If it is less than 1.3 times, the effect of improving the cooling capacity of the cooling section will not be obvious.

[0039] In a specific embodiment of the method of the present invention, the temperature discharged from the silicon steel continuous annealing furnace 1 is

[0040] The nitrogen-hydrogen mixed gas with a temperature of ≥750°C is transported to the refrigeration unit 2 for heat exchange to produce cold water. The nitrogen-hydrogen mixed gas with a temperature of <750°C discharged from the silicon steel continuous annealing furnace 1 is transported to the refrigeration unit 2 for heat exchange to produce cold water, which will reduce the input heat of the bromide refrigerator driving heat source and affect the cooling capacity of the bromide refrigerator.

[0041] In a specific implementation manner of the method of the present invention, the energy efficiency ratio of the refrigeration unit 2 is ≥1.4. If the energy efficiency ratio of the refrigeration unit 2 is <1.4, the refrigeration capacity of the bromide refrigerator will be reduced.

[0042] In a specific implementation of the method of the present invention, the temperature of the flue gas discharged from the refrigeration unit 2 is ≤250°C.

[0043] The experimental methods or test methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0044] Example 1

[0045] A system for improving the cooling capacity of a silicon steel continuous annealing furnace, such as Figure 2As shown, the system includes a silicon steel continuous annealing furnace 1, a refrigeration unit 2 (a direct-fired bromide refrigeration machine), a first cooling device 8 (a cooling tower) and a second cooling device 9 (a cooling tower). The silicon steel continuous annealing furnace 1 includes a heating section 10, an air cooling section 12 and a protective gas circulation cooling section 3 which are connected in sequence. The protective gas circulation cooling section 3 includes a controlled cooling section 6 and a rapid cooling section 7 which are connected in sequence. The cold-rolled steel material passes through the heating section 10, the air cooling section 12, the controlled cooling section 6 and the rapid cooling section 7 in sequence to complete the continuous decarburization annealing treatment. The controlled cooling section 6 is composed of 5 connected cooling units 13, and the rapid cooling section 7 is composed of 7 connected cooling units. 13, the heating section 10 has a vent 11, the vent 11 is connected to the refrigeration unit 2 through a connecting pipe, the refrigeration unit 2 has an outlet 4, an inlet 5 and a smoke exhaust port 14, the outlet 4 and the inlet 5 are respectively connected to the 6th and 7th cooling units 13 of the fast cooling section 7, the first cooling device 8 is connected to each cooling unit 13 in the cooling control section 6, the first cooling device 8 is connected to the 1st, 2nd, 3rd, 4th and 5th cooling units 13 in the fast cooling section 7, the first cooling device 8 is connected to the refrigeration unit 2, and the second cooling device 9 is connected to the refrigeration unit 2.

[0046] A method for improving the cooling capacity of a silicon steel continuous annealing furnace comprises the following steps:

[0047] Step 1: The high-temperature nitrogen-hydrogen mixed gas (hydrogen flow rate is 310m 3 / h, nitrogen flow rate is 1400m 3 / h, temperature is 800℃, exhaust temperature is 200℃) enters the direct-fired bromide refrigeration machine regenerator through the insulation pipe for combustion heat exchange, and the high-temperature nitrogen-hydrogen mixed gas provides 5349583kJ / h of heat for the direct-fired bromide refrigeration machine regenerator, and drives the direct-fired bromide refrigeration machine (energy efficiency ratio is 1.6) to produce cold water, with a cooling capacity of 8559332kJ / h;

[0048] The original circulating cooling water flow rates of the 6th and 7th sections of the rapid cooling section 7 are 50m 3 / h, the temperature out of the quick cooling section 7 is 47°C and 45°C respectively, and is cooled to ≤35°C by the first cooling device 8 (cooling tower). The total refrigeration capacity required is 4620000 kJ / h, and the refrigeration capacity of the direct-fired bromide refrigeration machine is 1.85 times that of the first cooling device 8 (cooling tower). Therefore, the refrigerating water of the direct-fired bromide refrigeration machine is used to replace the original circulating cooling water of the 6th and 7th sections of the quick cooling section 7, and the flow rate of the cold water remains unchanged. The original circulating cooling water of the 6th and 7th sections of the quick cooling section 7 enters and exits the heat exchanger through the original branch pipes of the original circulating cooling water of the 6th and 7th sections of the quick cooling section 7, and the internal circulating nitrogen of the quick cooling section 7 is cooled;

[0049] Step 2: The cooling water system of the direct-fired bromide refrigeration machine is partially supplemented with the original circulating cooling water of the 6th and 7th sections of the quick cooling section 7 to reduce the land occupation and construction cost of the cooling water system of the direct-fired bromide refrigeration machine.

[0050] After the above steps are implemented, the operating parameters of 0.5mm×1200mm strip steel in the process section are: the inlet temperature of the rapid cooling section 7 is 600℃, and the outlet plate temperature of each section and the inlet and outlet temperatures of the cooling water after entering the rapid cooling section 7 are shown in Table 1; the out-of-furnace plate temperature is 166℃.

[0051] Example 2

[0052] A method for improving the cooling capacity of a silicon steel continuous annealing furnace is implemented according to the system of Example 1, comprising the following steps:

[0053] Step 1: The high-temperature nitrogen-hydrogen mixed gas (hydrogen flow rate is 310m 3 / h, nitrogen flow rate is 1400m 3 / h, temperature is 800℃, exhaust temperature is 200℃) enters the direct-fired bromide refrigeration machine regenerator through the insulation pipe for combustion heat exchange, the high-temperature nitrogen-hydrogen mixed gas provides 5349583kJ / h of heat for the direct-fired bromide refrigeration machine regenerator, and drives the direct-fired bromide refrigeration machine (energy efficiency ratio is 1.4) to produce cold water, with a cooling capacity of 7489416kJ / h;

[0054] The original circulating cooling water flow rates of the 6th and 7th sections of the rapid cooling section 7 are 50m 3 / h, the temperature out of the quick cooling section 7 is 47°C and 45°C respectively, and is cooled to ≤35°C by the first cooling device 8 (cooling tower). The total refrigeration capacity required is 4620000 kJ / h, and the refrigeration capacity of the direct-fired bromide refrigeration machine is 1.62 times that of the first cooling device 8 (cooling tower). Therefore, the refrigerating water of the direct-fired bromide refrigeration machine is used to replace the original circulating cooling water of the 6th and 7th sections of the quick cooling section 7, and the flow rate of the cold water remains unchanged. The original circulating cooling water of the 6th and 7th sections of the quick cooling section 7 enters and exits the heat exchanger through the original branch pipes of the original circulating cooling water of the 6th and 7th sections of the quick cooling section 7, and the internal circulating nitrogen of the quick cooling section 7 is cooled;

[0055] Step 2: The cooling water system of the direct-fired bromide refrigeration machine is partially supplemented with the original circulating cooling water of the 6th and 7th sections of the quick cooling section 7 to reduce the land occupation and construction cost of the cooling water system of the direct-fired bromide refrigeration machine.

[0056] After the above steps are implemented, the operating parameters of 0.5mm×1200mm strip steel in the process section are: the inlet temperature of the rapid cooling section 7 is 600℃, and the outlet plate temperature of each section and the inlet and outlet temperatures of cooling water after entering the rapid cooling section 7 are shown in Table 1; the out-of-furnace plate temperature is 177℃.

[0057] Example 3

[0058] A method for improving the cooling capacity of a silicon steel continuous annealing furnace is implemented according to the system of Example 1, comprising the following steps:

[0059] Step 1: The high-temperature nitrogen-hydrogen mixed gas (hydrogen flow rate is 240m3 / h, nitrogen flow rate is 1400m 3 / h, temperature is 800℃, exhaust temperature is 200℃) enters the direct-fired bromide refrigeration machine regenerator through the insulation pipe for combustion heat exchange, the high-temperature nitrogen-hydrogen mixed gas provides 4400503kJ / h of heat for the direct-fired bromide refrigeration machine regenerator, and drives the direct-fired bromide refrigeration machine (energy efficiency ratio is 1.4) to produce cold water, with a cooling capacity of 6160704kJ / h;

[0060] The original circulating cooling water flow rates of the 6th and 7th sections of the rapid cooling section 7 are 50m 3 / h, the temperatures out of the quick cooling section 7 are 47°C and 45°C respectively, and are cooled to ≤35°C by the first cooling device 8 (cooling tower). The required refrigeration capacity is 4620000 kJ / h, and the refrigeration capacity of the direct-fired bromide refrigeration machine is 1.33 times that of the first cooling device 8 (cooling tower). Therefore, the refrigerating water of the direct-fired bromide refrigeration machine is used to replace the original circulating cooling water of the 6th and 7th sections of the quick cooling section 7, and the flow rate of the cold water remains unchanged. The original circulating cooling water of the 6th and 7th sections of the quick cooling section 7 enters and exits the heat exchanger through the original branch pipes of the original circulating cooling water of the 6th and 7th sections of the quick cooling section 7, and the internal circulating nitrogen of the quick cooling section 7 is cooled;

[0061] Step 2: The cooling water system of the direct-fired bromide refrigeration machine is partially supplemented with the original circulating cooling water of the 6th and 7th sections of the quick cooling section 7 to reduce the land occupation and construction cost of the cooling water system of the direct-fired bromide refrigeration machine.

[0062] After the above steps are implemented, the operating parameters of 0.5mm×1200mm strip steel in the process section are: the inlet temperature of the rapid cooling section 7 is 600℃, and the outlet plate temperature of each section and the inlet and outlet temperatures of cooling water after entering the rapid cooling section 7 are shown in Table 1; the out-of-furnace plate temperature is 184℃.

[0063] Comparative Example 1

[0064] The method of Example 1 is followed, except that the internal circulating nitrogen of the rapid cooling section 7 is directly cooled by using the original circulating cooling water of the 6th and 7th sections of the rapid cooling section 7. After the process section is heated and accelerated, the operating parameters of the 0.5mm×1200mm specification strip steel in the process section are as follows: the inlet temperature of the rapid cooling section 7 is 600°C, and the outlet plate temperature of each section after entering the rapid cooling section 7 and the inlet and outlet temperatures of the cooling water are as shown in Table 1; the temperature of the plate out of the furnace is 207°C.

[0065] Table 1: Plate temperature and water temperature at the outlet of each section of the rapid cooling section in Examples 1-3 and Comparative Example 1

[0066]

[0067]

[0068] According to the results of Examples 1 to 3 and Comparative Example 1, it can be seen that the use of the system of the present invention to carry out decarburization annealing treatment on steel can fully absorb the heat generated by the combustion of hydrogen at the furnace head, thereby saving a large amount of energy and reducing production costs. At the same time, it can reduce the furnace plate temperature and the cooling water outlet temperature, which is beneficial to ensuring the performance and surface quality of silicon steel.

[0069] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A system for improving the cooling capacity of a silicon steel continuous annealing furnace, characterized in that: The system comprises a silicon steel continuous annealing furnace (1) and a refrigeration unit (2); The silicon steel continuous annealing furnace (1) is used to perform continuous decarburization annealing treatment on steel, and the silicon steel continuous annealing furnace (1) comprises a protective gas circulation cooling section (3); The refrigeration unit (2) is used to produce cold water by burning and exchanging heat with the nitrogen-hydrogen mixed gas discharged from the silicon steel continuous annealing furnace (1), and to transport the produced cold water to the protective gas circulation cooling section (3), so as to use the cold water to cool the circulating protective gas in the protective gas circulation cooling section (3).

2. The system for improving the cooling capacity of a silicon steel continuous annealing furnace according to claim 1, characterized in that: The refrigeration unit (2) has an outlet (4), an inlet (5) and a smoke exhaust port (14); The outlet (4) is used to transport the cold water produced by the refrigeration unit (2) to the protective gas circulation cooling section (3) through a connecting pipeline; The inlet (5) is used to transport the cold water used to cool the circulating protective gas in the protective gas circulating cooling section (3) to the refrigeration unit (2) through a connecting pipeline; The smoke exhaust port (14) is used to discharge the nitrogen-hydrogen mixed gas after combustion and heat exchange.

3. The system for improving the cooling capacity of a silicon steel continuous annealing furnace according to claim 2, characterized in that: The protective gas circulation cooling section (3) comprises a controlled cooling section (6) and a rapid cooling section (7), and the heated steel is cooled in the controlled cooling section (6) and the rapid cooling section (7) in sequence, and the controlled cooling section (6) and the rapid cooling section (7) are both composed of a plurality of connected cooling units (13); The refrigeration unit (2) transports the produced cold water to a portion of the cooling units (13) in the controlled cooling section (6) and / or the rapid cooling section (7), and the circulating cooling water in a portion of the cooling units (13) in the controlled cooling section (6) and / or the rapid cooling section (7) is replaced by the input cold water.

4. The system for improving the cooling capacity of a silicon steel continuous annealing furnace according to claim 3, characterized in that: Before hydrogen is added to the drying furnace, the circulating cooling water replaced by cold water in a part of the cooling units (13) of the controlled cooling section (6) and / or the rapid cooling section (7) continues to cool the circulating protective gas in a part of the cooling units (13) of the controlled cooling section (6) and / or the rapid cooling section (7), and the other part of the cooling units (13) of the controlled cooling section (6) and / or the rapid cooling section (7) cools the circulating protective gas with the circulating cooling water therein; After hydrogen is added to the drying furnace, the circulating protective gas in a part of the cooling units (13) of the controlled cooling section (6) and / or the rapid cooling section (7) is cooled by the input cold water, and another part of the cooling units (13) of the controlled cooling section (6) and / or the rapid cooling section (7) continues to cool the circulating protective gas with the circulating cooling water therein.

5. The system for improving the cooling capacity of a silicon steel continuous annealing furnace according to claim 4, characterized in that: The system further comprises a first cooling device (8), which is used to cool the circulating cooling water in another part of the cooling unit (13) of the controlled cooling section (6) and / or the fast cooling section (7), and to further transport the cooled circulating cooling water to another part of the cooling unit (13) of the controlled cooling section (6) and / or the fast cooling section (7).

6. The system for improving the cooling capacity of a silicon steel continuous annealing furnace according to claim 5, characterized in that: The system further comprises a second cooling device (9), wherein the second cooling device (9) is used to transport cooling water to the refrigeration unit (2), and utilize the cooling water to circulate and cool the refrigeration unit (2).

7. The system for improving the cooling capacity of a silicon steel continuous annealing furnace according to claim 6, characterized in that: The circulating cooling water replaced by cold water in a part of the cooling units (13) of the controlled cooling section (6) and / or the fast cooling section (7) is transported to the first cooling device (8) through a pipeline for cooling, and the cooled circulating cooling water replaced by cold water is further transported to the refrigeration unit (2), and the refrigeration unit (2) is circulated and cooled using the cooled circulating cooling water replaced by cold water.

8. A method for improving the cooling capacity of a silicon steel continuous annealing furnace according to the system of any one of claims 1 to 7, characterized in that: The method comprises: conveying the nitrogen-hydrogen mixed gas discharged from a silicon steel continuous annealing furnace (1) to a refrigeration unit (2) for combustion and heat exchange to produce cold water, conveying the cold water to a protective gas circulating cooling section (3) of the silicon steel continuous annealing furnace (1), and using the cold water to replace the original circulating cooling water in the protective gas circulating cooling section (3) to cool the circulating protective gas in the protective gas circulating cooling section (3).

9. The method for improving the cooling capacity of a silicon steel continuous annealing furnace according to claim 8, characterized in that: The flow rate of cold water produced by the refrigeration unit (2) is 0.8 to 1.2 times the sum of the original flow rates of circulating cooling water in the cooling unit (13) replaced by the cold water in the protective gas circulating cooling section (3); The refrigeration capacity of the refrigeration unit (2) is ≥ 1.3 times the total refrigeration capacity required for cooling by the original circulating cooling water in the cooling unit (13) replaced by the cold water.

10. The method for improving the cooling capacity of a silicon steel continuous annealing furnace according to claim 8, characterized in that: The nitrogen-hydrogen mixed gas with a temperature of ≥750° C. discharged from the silicon steel continuous annealing furnace (1) is transported to a refrigeration unit (2) for combustion and heat exchange to produce cold water; The energy efficiency ratio of the refrigeration unit (2) is ≥1.4; The temperature of the flue gas discharged from the refrigeration unit (2) is ≤250°C.

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