Steel charging and heating process based on three-pass heating furnace

Abstract

The present application belongs to the field of metallurgical industry, and discloses a kind of steel loading heating process based on three-pass heating furnace, which comprises the following steps: S1, first, cold billets are added to the first or third pass of the heating furnace, and then hot billets are added to the remaining two passes of the heating furnace; S2, repeating S1 until the heating furnace is full of billets; S3, the cold billets and the hot billets are sequentially preheated, heated and soaked in the heating furnace, and then discharged to obtain steel products. The process can save energy and reduce energy consumption on the basis of reasonable combustion of the heating furnace, and improve production efficiency. The present application is suitable for the steel loading heating process of the heating furnace in continuous steel production.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical industry and relates to a steel charging heating process, specifically a steel charging heating process based on a three-stage heating furnace. Background Technology

[0002] The key to continuous steel production is to achieve continuous casting-rolling process. The heating furnace, as a high-energy-consuming equipment in the production process, plays a vital role in connecting the casting machine and the rolling mill.

[0003] In actual production, to achieve continuous production between casting and rolling mills, the rolling mill's capacity is generally required to be about 10% higher than that of the casting mill. Meanwhile, depending on different process requirements and production scheduling plans, some hot billets from the casting machine are directly fed into the heating furnace for heating before entering the rolling mill; others are stored in a billet warehouse and taken out for heating when needed. Often, both hot and cold billets enter the heating furnace. When hot and cold billets enter the heating furnace together in the same pass, the cold billets lower the temperature of the hot billets, requiring them to remain in the furnace for an extended period, thus reducing the overall production line efficiency and increasing energy consumption.

[0004] Therefore, how to save energy, reduce energy consumption, and improve production efficiency while ensuring proper combustion in the heating furnace is a problem that needs to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention aims to provide a steel charging heating process based on a three-stage heating furnace, thereby achieving energy conservation, reduced energy consumption, and improved production efficiency while ensuring proper combustion in the furnace.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A steel charging heating process based on a three-stage heating furnace includes the following steps performed sequentially:

[0008] S1. First, add the cooled billet to the first or third pass of the heating furnace, and then add the hot billet to the remaining two passes of the heating furnace.

[0009] S2. Repeat S1 until the furnace is full of billets.

[0010] S3. Both the cold billet and the hot billet pass through the preheating section, the heating section and the soaking section in the heating furnace in sequence before exiting the furnace to obtain steel.

[0011] The remaining two passes are two adjacent passes.

[0012] The temperature of the cooled blank is lower than the temperature of the hot blank.

[0013] The heating furnace is a three-pass, push-type steel heating furnace.

[0014] As a limitation of the present invention, the ratio of the number of cooled blanks to heated blanks is 1:2-3.

[0015] As a further limitation of the present invention, the thickness of the hot blank is 200-230mm, the width of the hot blank is 1400-1600mm, and the length of the hot blank is 1700-2430mm.

[0016] The thickness of the cooled blank is 200-230mm, the width of the cooled blank is 1400-1600mm, and the length of the cooled blank is 1700-2430mm.

[0017] As a further limitation of the present invention, the total mass fraction of alloying elements in the cooled blank is less than 3.5%, and the total mass fraction of alloying elements in the heated and cooled blank is less than 3.5%.

[0018] As a further limitation of the present invention, the temperature of the hot billet is 600-900°C, and the temperature of the cooled billet is not higher than 450°C.

[0019] As a further limitation of the present invention, the gas flow rate of the heating furnace is 35,000-45,000 m³ / h. 3 / h, the air-fuel ratio of the heating furnace is 0.71-0.75, and the calorific value of the gas in the heating furnace is 5200-5300KJ / Nm.

[0020] As a further limitation of the present invention, the preheating temperature of the preheating section of the heating furnace is 850-950°C, the heating temperature of the heating section of the heating furnace is 1220-1270°C, and the homogenization temperature of the homogenization section of the heating furnace is 1210-1260°C.

[0021] As a further limitation of the present invention, the steel is an alloy steel with a total mass fraction of alloying elements of less than 3.5%.

[0022] By adopting the above-described technical solution, the beneficial effects achieved by this invention compared to the prior art are as follows:

[0023] (1) In this invention, the cold billet is first added to the heating furnace in the 1st or 3rd pass, and then the hot billet is added to the two adjacent passes of the heating furnace. This combination of cold and hot feeding passes can effectively improve the heating efficiency of the heating furnace and at the same time improve the heating efficiency of the cold billet. Changing the feeding pass of the cold billet or changing the feeding order of the cold and hot billets will affect the heating efficiency of the cold billet and reduce the heating efficiency of the heating furnace.

[0024] (2) The reasonable ratio of cold billet to hot billet in this invention can effectively reduce the time of cold billet and hot billet in the furnace on the basis of the maximum number of cold billet and hot billet, improve the production efficiency of the heating furnace, and thus reduce the energy consumption of the heating furnace, so as to meet different process requirements and production scheduling plans.

[0025] (3) The air-fuel ratio of 0.71-0.75 in the heating furnace in this invention can make full and reasonable use of the combustion utilization rate of the heating furnace, save energy, reduce energy consumption, and at the same time maintain the heating efficiency of the heating furnace at an ideal level.

[0026] (4) This invention effectively combines the cold and hot billet feeding in separate stages with parameters such as air-fuel ratio, preheating temperature, heating temperature, and homogenization temperature of the heating furnace, so as to reduce the billet time in the furnace and improve production efficiency on the basis of reasonable combustion in the heating furnace, thereby achieving the purpose of saving energy and reducing energy consumption, while meeting different process requirements and production scheduling plans. Detailed Implementation

[0027] The present invention will be further described in detail below through specific embodiments. It should be understood that the described embodiments are only used to explain the present invention and do not limit the present invention.

[0028] Example 1: A steel charging heating process based on a three-stage heating furnace

[0029] The experimental parameters for the heating furnace in this embodiment are as follows:

[0030] The gas flow rate is 40,000-45,000 m³ / h. 3 / h, air-fuel ratio of 0.72-0.73, calorific value of gas of 5200-5300KJ / Nm, preheating temperature of preheating section of 850-950℃, heating temperature of heating section of 1220-1270℃, and averaging temperature of 1210-1260℃.

[0031] The hot blank used in this embodiment is prepared as follows:

[0032] The molten steel from the steelmaking furnace is processed by the steelmaking plate continuous casting machine to obtain slabs with a thickness of 220mm and a width of 1600mm. The slabs are then cut to obtain hot billets with a thickness of 220mm, a width of 1600mm, and a length of 2430mm. The temperature of the hot billets is 800-900℃.

[0033] The cooled blank used in this embodiment was stored at room temperature, with a thickness of 220mm, a width of 1600mm, a length of 2430mm, and a cooling temperature of 25℃.

[0034] The specific steps of a steel charging heating process based on a three-stage heating furnace are as follows:

[0035] S1. Push 6 cold billets to the heating furnace in the first pass by the pusher, and push 18 hot billets to the heating furnace in the second and third passes by the pusher in sequence.

[0036] S2. Repeat S1 to add cold billets and hot billets until the furnace is full of billets.

[0037] S3. When the thermocouple shows that the billet has been heated to the target temperature in the heating furnace, it is pushed forward by the pusher and passes through the preheating section, heating section and soaking section in sequence. When both the hot billet and the cold billet enter the soaking section, they are discharged from the furnace and steel is obtained.

[0038] According to the timing, in this embodiment, the time the billet is in the furnace from the time it enters the furnace to the time it exits the furnace is 130 minutes.

[0039] Example 2-18: A steel charging heating process based on a three-stage heating furnace

[0040] Examples 2-18 are steel charging heating processes based on a three-stage heating furnace. The specific methods are basically the same as those in Example 1, except for the parameter settings. The specific differences are shown in Table 1-2.

[0041] Table 1. Parameters and furnace time for Examples 2-9

[0042]

[0043]

[0044] Table 2 Parameters and Furnace Time for Examples 10-18

[0045]

[0046]

[0047] As shown in Table 1-2, the results of Examples 1-3 and 10-14 indicate that the billet time in the furnace increases with the increase of billet thickness. The results of Examples 1, 4-9 and 15-18 indicate that changing the gas flow rate, air-fuel ratio, preheating section temperature, heating section temperature, soaking section temperature, hot billet temperature, cool billet temperature, and the number of cool and hot billet pieces, at a ratio of 1:2-3 between the number of cool and hot billets, the length and width of the billet have virtually no effect on the billet time in the furnace.

[0048] Comparative Example 1: A steel loading heating process

[0049] The only difference between this comparative example and Example 1 is the experimental parameters of the heating furnace; the gas flow rate is 40,000-45,000 m³ / h. 3 / h, air-fuel ratio is 0.72-0.73, calorific value of gas is 5200-5300KJ / Nm, preheating temperature of preheating section is 800-850℃, heating temperature of heating section is 1230-1280℃, and homogenization temperature of homogenization section is 1220-1270℃.

[0050] According to the timing, in this embodiment, the time the billet is in the furnace from the time it enters the furnace to the time it exits the furnace is 144 minutes.

[0051] Comparative Example 2: A Steel Loading Heating Process

[0052] The only difference between this comparative example and Example 1 is the experimental parameters of the heating furnace; the gas flow rate is 40,000-45,000 m³ / h. 3 / h, air-fuel ratio is 0.72-0.73, calorific value of gas is 5200-5300KJ / Nm, preheating temperature of preheating section is 900-1000℃, heating temperature of heating section is 1200-1250℃, and homogenization temperature of homogenization section is 1200-1240℃.

[0053] According to the timing, in this embodiment, the time the billet is in the furnace from the time it enters the furnace to the time it exits the furnace is 144 minutes.

[0054] Comparative Example 3: A Steel Loading Heating Process

[0055] The only difference between this comparative example and Example 1 is that the experimental parameters for the heating furnace are an air-fuel ratio of 0.75-0.76.

[0056] According to the timing, in this comparative example, the time the billet was in the furnace from the first billet entering the furnace to the last billet exiting the furnace was 138 minutes.

[0057] Comparative Example 4: A Steel Loading Heating Process

[0058] The only difference between this comparative example and Example 1 is that the experimental parameters for the heating furnace are an air-fuel ratio of 0.70-0.71.

[0059] According to the timing, in this comparative example, the time the billet was in the furnace from the first billet entering the furnace to the last billet exiting the furnace was 144 minutes.

[0060] Comparative Example 5: A Steel Loading Heating Process

[0061] The only difference between this comparative example and Example 1 is that:

[0062] The specific steps of a steel charging heating process based on a three-stage heating furnace are as follows:

[0063] S1. Six cold billets are pushed sequentially to the heating furnace in passes 1, 2, and 3 by the pusher, and 18 hot billets are pushed sequentially to the heating furnace in passes 1, 2, and 3 by the pusher.

[0064] S2. Repeat S1 to add cold billets and hot billets until the furnace is full of billets.

[0065] S3. When the thermocouple shows that the billet has been heated to the target temperature in the heating furnace, it is pushed forward by the pusher and passes through the preheating section, heating section and soaking section in sequence. When both the hot billet and the cold billet enter the soaking section, they are discharged from the furnace and steel is obtained.

[0066] According to the timing, in this comparative example, the time the billet was in the furnace from the first billet entering the furnace to the last billet exiting the furnace was 168 minutes.

[0067] Comparative Example 6: A Steel Loading Heating Process

[0068] The only difference between this comparative example and Example 1 is that:

[0069] The specific steps of a steel charging heating process based on a three-stage heating furnace are as follows:

[0070] S1. The 18 hot billets are pushed sequentially to the heating furnace in passes 2 and 3 by the pusher, and the 6 cold billets are pushed to the heating furnace in pass 1 by the pusher.

[0071] S2. Repeat S1 to add cold billets and hot billets until the furnace is full of billets.

[0072] S3. When the thermocouple shows that the billet has been heated to the target temperature in the heating furnace, it is pushed forward by the pusher and passes through the preheating section, heating section and soaking section in sequence. When both the hot billet and the cold billet enter the soaking section, they are discharged from the furnace and steel is obtained.

[0073] According to the timing, in this embodiment, the time the billet is in the furnace from the time it enters the furnace to the time it exits the furnace is 137 minutes.

[0074] Comparative Example 7: A Steel Loading Heating Process

[0075] The only difference between this comparative example and Example 1 is that:

[0076] The specific steps of a steel charging heating process based on a three-stage heating furnace are as follows:

[0077] S1. Push 6 cold billets to the heating furnace 2nd pass by the pusher, and push 18 hot billets to the heating furnace 1st and 3rd pass in sequence by the pusher.

[0078] S2. Repeat S1 to add cold billets and hot billets until the furnace is full of billets.

[0079] S3. When the thermocouple shows that the billet has been heated to the target temperature in the heating furnace, it is pushed forward by the pusher and passes through the preheating section, heating section and soaking section in sequence. When both the hot billet and the cold billet enter the soaking section, they are discharged from the furnace and steel is obtained.

[0080] According to the timing, in this embodiment, the time the billet is in the furnace from the time it enters the furnace to the time it exits the furnace is 174 minutes.

[0081] Results Analysis

[0082] The results of Example 1 and Comparative Examples 1-2 show that when the temperatures of the preheating section, heating section, and soaking section are changed, the billet's time in the furnace increases. The results of Example 1 and Comparative Examples 3-4 show that when the air-fuel ratio of the heating furnace exceeds 0.71-0.75, the billet's time in the furnace increases. The results of Example 1 and Comparative Examples 5-7 show that when the feeding sequence of hot and cold billets is changed, or when cold billets are fed in 2 passes and hot billets are fed in 1 or 3 passes, the billet's time in the furnace increases.

[0083] It should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A steel charging heating process based on a three-stage heating furnace, characterized in that, This includes the following steps performed sequentially: S1. First, add the cooled billet to the first or third pass of the heating furnace, and then add the hot billet to the remaining two passes of the heating furnace; S2. Repeat S1 until the furnace is full of billets; S3. Both the cold billet and the hot billet pass through the preheating section, the heating section and the soaking section in the heating furnace in sequence, and then exit the furnace to obtain steel. The temperature of the cooled billet is lower than the temperature of the hot billet; The heating furnace is a three-pass, push-type steel heating furnace; The gas flow rate of the heating furnace is 35,000-45,000 m³ / h, the air-fuel ratio of the heating furnace is 0.71-0.75, and the calorific value of the gas in the heating furnace is 5,200-5,300 KJ / Nm³. The preheating temperature of the preheating section of the heating furnace is 850-950℃, the heating temperature of the heating section of the heating furnace is 1220-1270℃, and the homogenization temperature of the homogenization section of the heating furnace is 1210-1260℃. The ratio of the number of cooled blanks to the number of heated blanks is 1:2-3; The thickness of the hot blank is 200-230mm, the width of the hot blank is 1400-1600mm, and the length of the hot blank is 1700-2430mm. The thickness of the cooled blank is 200-230mm, the width of the cooled blank is 1400-1600mm, and the length of the cooled blank is 1700-2430mm. The total mass fraction of alloying elements in the cooled blank is less than 3.5%; The temperature of the hot billet is 600-900℃, and the temperature of the cooled billet is not higher than 450℃.

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