Method for stable operation of an annular heating furnace

Abstract

The present application relates to the technical field of steel production, and particularly relates to a method for stable operation of a ring heating furnace, which comprises the following steps: a continuous heating mode: setting the heating area of the ring heating furnace as follows: the first area is a preheating area, the second area to the sixth area are heating areas, and the seventh area to the eighth area are soaking areas; heating the ingot to a first set temperature in the preheating area, continuously heating the ingot to a second set temperature according to a set temperature gradient from the second area to the sixth area in the heating area; cooling the ingot to a third set temperature according to a first set temperature gradient in the soaking area, the third set temperature being greater than the first set temperature; a shutdown standby mode: determining standby time; if the standby time is less than a first set time length, the temperature of each area of the ring heating furnace remains unchanged. The present application can effectively heat the ingot, save the use of fuel, and ensure the efficiency of heating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel production, and particularly relates to a method for stable operation of a ring heating furnace. BACKGROUND

[0002] The seamless steel pipe can be used as a gas cylinder accumulator pipe, an oil casing, an oil casing coupling, a low-medium pressure boiler pipe, a high pressure boiler pipe, a pipeline pipe (including an ocean oil and gas collection and transportation thick wall low temperature steel pipe), an oil cracking pipe, a seamless steel pipe for conveying fluid, a seamless steel pipe for structure, etc.

[0003] In the process of producing the seamless steel pipe, heating needs to be performed in a ring heating furnace, and then subsequent perforation and pipe rolling are performed. The control of the heating link is very important. In the heating process, the ingot is sequentially heated in eight heating zones. The heating temperature will affect the quality of subsequent processing, and when a sudden situation needs to be stopped for heating within a certain time, if the ring heating furnace is directly turned off, the subsequent production preparation time will be too long, and the processing efficiency will be low; if the heating state is still maintained, a large amount of fuel will be consumed.

[0004] Therefore, a method for stable operation of a ring heating furnace is needed to solve the above problems. SUMMARY

[0005] The present application aims to provide a method for stable operation of a ring heating furnace, which can effectively heat the ingot, ensure the quality of subsequent processing, and save the use of fuel, thereby ensuring the efficiency of heating.

[0006] To achieve this purpose, the present application adopts the following technical solutions:

[0007] The method for stable operation of the ring heating furnace comprises the following steps:

[0008] Continuous heating mode:

[0009] The heating zones of the ring heating furnace are set as follows: the first zone is a preheating zone, the second zone to the sixth zone are heating zones, and the seventh zone to the eighth zone are soaking zones;

[0010] The ingot is heated to a first set temperature in the preheating zone, and the ingot is continuously heated to a second set temperature according to a set temperature rising gradient from the second zone to the sixth zone in the heating zone;

[0011] The ingot is cooled to a third set temperature according to a first set temperature falling gradient in the soaking zone, and the third set temperature is greater than the first set temperature;

[0012] Shutdown standby mode:

[0013] A standby time is determined;

[0014] If the standby time is less than the first set time length, the temperature of each zone of the ring-shaped heating furnace remains unchanged.

[0015] If the standby time is not less than the first set time length and less than the second set time length, the temperature of the first zone to the fifth zone is lowered according to the second set temperature gradient, and the temperature of the sixth zone to the eighth zone remains unchanged.

[0016] If the standby time is not less than the second set time length, the ring-shaped heating furnace is shut down, and the steel ingot located in the soaking zone is withdrawn to the sixth zone.

[0017] Further, in the continuous heating mode, if the models of the steel ingots are different, the first set temperature, the second set temperature and the third set temperature are set according to the steel ingot of the lowest temperature.

[0018] Further, the third set temperature is the process required ring-shaped heating furnace delivery temperature.

[0019] Further, in the shutdown standby mode, the air flow into the ring-shaped heating furnace is first reduced.

[0020] Further, in the shutdown standby mode, when the standby time is less than the second set time length, the air excess coefficient is controlled to be 0.95-1.3.

[0021] Further, after the shutdown standby mode ends and the temperature is raised again, the air flow is first increased, and then the fuel flow is increased.

[0022] Further, the air flow and the fuel flow are adjusted according to the set air-fuel ratio.

[0023] Further, the temperature is raised by no more than 15℃ each time.

[0024] Further, after the temperature is raised to the corresponding temperature each time, the air flow and the fuel flow are adjusted again after a set time length.

[0025] Further, in the shutdown standby mode, the residual oxygen content of the flue gas is controlled to be 3%-8%.

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

[0027] The method for stable operation of the ring heating furnace provided by the application is divided into continuous heating mode and shutdown standby mode according to actual production conditions in the process of heating the steel ingot. In the continuous heating mode, the steel ingot is heated to a first set temperature in the preheating zone, continuously heated to a second set temperature according to a set temperature rising gradient from the second zone to the sixth zone in the heating zone, and cooled to a third set temperature according to a first set temperature falling gradient in the soaking zone. The steel ingot is preheated, continuously heated, and finally cooled to a certain extent in the soaking zone, meeting the requirements of furnace discharge. The temperature of the steel ingot can be reasonably controlled to avoid rapid cooling and heating, ensuring the uniformity of the steel ingot heating. In the shutdown standby mode, the standby time is first determined, and the temperature of each zone of the ring heating furnace is controlled according to different standby time. When the time is short, the original temperature is maintained to facilitate subsequent rapid switching to continuous heating mode. When the time is in the first set time and the second set time, the temperature of the first zone to the fifth zone is reduced, and the temperature of the sixth zone to the eighth zone is kept unchanged, so that the steel ingot in the sixth zone and the eighth zone can continue to be heated. If the standby time is long, the ring heating furnace is closed, the hottest sixth zone is used to heat the steel ingot in the soaking zone and slowly cool it down, thereby avoiding the waste of the steel ingot. Through the above-mentioned mode, the use of fuel can be saved, the efficiency of heating can be ensured, and the quality of subsequent processing can be ensured. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a flowchart of the method for stable operation of the ring heating furnace. DETAILED DESCRIPTION

[0029] The technical solutions of the application will be further described below in combination with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the application, not to limit the application. In addition, it should be noted that only the parts related to the application are shown in the drawings for convenience of description.

[0030] In the description of the application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection" and "connection" should be understood broadly, for example, it can be fixed connection or detachable connection, it can be mechanical connection or electrical connection, it can be direct connection or indirect connection through intermediate medium, and it can be the communication inside two elements. For ordinary skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0031] In the present application, unless otherwise explicitly specified and limited, "on" or "under" of a first feature to a second feature can include that the first and second features are in direct contact, or can include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, "on", "above" and "over" of a first feature to a second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. "Under", "below" and "underneath" of a first feature to a second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is lower in horizontal height than the second feature.

[0032] In the process of seamless steel pipe production, heating needs to be carried out in the annular heating furnace, and then subsequent piercing and pipe rolling are carried out. The control of the heating link is very important. In the heating process, the ingot is heated in eight heating zones in turn. The heating temperature will affect the quality of subsequent processing, and in the face of sudden situations that need to stop heating within a certain time, if the annular heating furnace is directly turned off, it will lead to too long preparation time for subsequent production and low processing efficiency; if it is still maintained in the heating state, it will lead to a large amount of fuel consumption.

[0033] In order to solve the above problems, the ingot can be effectively heated, the quality of subsequent processing is guaranteed, and the use of fuel is saved, and the heating efficiency is guaranteed, as shown in Figure 1 The present application provides a method for stable operation of an annular heating furnace. The method for stable operation of the annular heating furnace comprises the following steps:

[0034] Continuous heating mode:

[0035] The heating zones of the annular heating furnace are set as the first zone being a preheating zone, the second zone to the sixth zone being heating zones, and the seventh zone to the eighth zone being soaking zones;

[0036] The ingot is heated to a first set temperature in the preheating zone, and the ingot is continuously heated to a second set temperature according to a set temperature rising gradient from the second zone to the sixth zone in the heating zone;

[0037] The ingot is cooled to a third set temperature according to a first set temperature falling gradient in the soaking zone, and the third set temperature is greater than the first set temperature;

[0038] Shutdown standby mode:

[0039] The standby time is determined;

[0040] If the standby time is less than a first set time length, the temperature of each zone of the annular heating furnace remains unchanged;

[0041] If the standby time is not less than the first set duration and less than the second set duration, the temperature of the first zone to the fifth zone is lowered according to the second set temperature gradient, and the temperature of the sixth zone to the eighth zone is kept unchanged;

[0042] If the standby time is not less than the second set duration, the annular heating furnace is shut down, and the ingot located in the soaking zone is withdrawn to the sixth zone.

[0043] In the process of heating the ingot, according to the actual production situation, it is divided into continuous heating mode and shutdown standby mode. In the continuous heating mode, the ingot is heated to the first set temperature in the preheating zone, and is continuously heated to the second set temperature from the second zone to the sixth zone in the heating zone according to the set temperature gradient. In the soaking zone, the ingot is cooled to the third set temperature according to the first set temperature gradient. By preheating, continuous heating and finally entering the soaking zone for a certain degree of cooling, the requirements for out of furnace are met. The temperature of the ingot can be reasonably controlled to avoid rapid cooling and heating, and the uniformity of ingot heating is ensured. In the shutdown standby mode, the standby time is first determined, and the temperature of each zone of the annular heating furnace is controlled according to different standby time. When the time is short, the original temperature is kept to facilitate subsequent rapid switching to continuous heating mode. When the time is in the first set duration and the second set duration, the temperature of the first zone to the fifth zone is lowered, and the temperature of the sixth zone to the eighth zone is kept unchanged, so that the ingot in the sixth zone and the eighth zone can continue to be heated. If the standby time is long, the annular heating furnace is closed, and the hottest sixth zone is used to heat and slowly cool the ingot in the soaking zone, so as to avoid the waste of the ingot. Through the above-mentioned mode, the use of fuel can be saved, the efficiency of heating can be ensured, and the quality of subsequent processing can be ensured.

[0044] Further, in the continuous heating mode, if the models of the ingots are different, the first set temperature, the second set temperature and the third set temperature are set according to the lowest temperature model of the ingot. By setting the first set temperature, the second set temperature and the third set temperature according to the lowest temperature model of the ingot, over-heating of the lowest temperature model of the ingot can be avoided, so as to ensure that the lowest temperature model of the ingot meets the requirements of subsequent processing.

[0045] Further, the third set temperature is the process required annular heating furnace out of furnace temperature. Through the above-mentioned mode, the ingot in the soaking zone can be smoothly out of furnace, and the requirements of subsequent processing can be met.

[0046] Further, in the shutdown standby mode, the air flow into the annular heating furnace is first reduced. By reducing the air flow, the amount of oxygen required for combustion can be reduced, thereby reducing the temperature.

[0047] Further, in the stop standby mode, when the standby time is less than the second set time length, the air excess coefficient is controlled to be 0.95-1.3. By controlling the air excess coefficient, the combustion of the fuel in the annular heating furnace can be adjusted, so as to achieve the purpose of adjusting the temperature in the annular heating furnace.

[0048] Further, after the stop standby mode ends and the rolling is restarted, the air flow is first increased, and then the fuel flow is increased. By controlling the air flow to be first increased and then the fuel flow to be increased, sufficient oxygen can be ensured when the fuel is burned, so as to ensure that the fuel can be fully burned, thereby improving the fuel utilization rate and ensuring that the temperature of the annular heating furnace can be effectively increased.

[0049] Further, the air flow and the fuel flow are adjusted according to the set air-fuel ratio. By setting the air-fuel ratio, the temperature rise of the annular heating furnace can be accurately controlled, so as to ensure that the temperature rise process of the annular heating furnace is stable.

[0050] Further, the temperature rise amplitude is not more than 15 DEG C each time. By controlling the air-fuel ratio, the temperature rise amplitude after adjusting the air-fuel ratio each time can be controlled, so as to avoid that the temperature in the annular heating furnace rises rapidly, which leads to insufficient combustion of the fuel, thereby leading to unstable temperature rise of the annular heating furnace.

[0051] Further, after the temperature is adjusted to the corresponding temperature each time, a set time length is continued, and then the air flow and the fuel flow are adjusted. In the temperature rise process, by continuing the set time length, it can be ensured that after the temperature rises, the temperature is in a stable state, and then the adjustment is continued until the temperature completely meets the set required temperature of the corresponding region.

[0052] Further, in the stop standby mode, the flue gas residual oxygen amount is controlled to be 3%-8%. By detecting the residual oxygen amount after combustion, whether the combustion is sufficient can be obtained. By controlling the flue gas residual oxygen amount to be 3%-8%, it can be ensured that the fuel supplied to the annular heating furnace is fully burned, and waste of fuel is avoided.

[0053] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the implementation modes of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the implementation modes are not enumerated. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. Method for stable operation of a ring furnace, characterized in that The method comprises the following steps: Continuous heating mode: The heating zones of the ring heating furnace are set as follows: the first zone is a preheating zone, the second to sixth zones are heating zones, and the seventh to eighth zones are soaking zones; In the preheating zone, the ingot is heated to a first set temperature, and in the heating zones from the second to sixth zones, the ingot is continuously heated to a second set temperature at a set temperature rising gradient; In the soaking zones, the ingot is cooled to a third set temperature at a first set temperature falling gradient, and the third set temperature is greater than the first set temperature; Shutdown standby mode: Determine standby time; If the standby time is less than a first set time length, the temperatures of the zones of the ring heating furnace remain unchanged; If the standby time is not less than the first set time length and less than a second set time length, the temperatures of the first to fifth zones are lowered at a second set temperature falling gradient, and the temperatures of the sixth to eighth zones remain unchanged; If the standby time is not less than the second set time length, the ring heating furnace is shut down, and the ingot in the soaking zone is withdrawn to the sixth zone; the ingot in the soaking zone is heated and slowly cooled in the hottest sixth zone to avoid waste of the ingot.

2. The method for stable operation of a ring furnace according to claim 1, characterized in that, In the continuous heating mode, if the models of the ingots are different, the first set temperature, the second set temperature and the third set temperature are set according to the ingot of the lowest temperature model.

3. The method for stable operation of a ring furnace according to claim 1, characterized in that, The third set temperature is the process required ring heating furnace discharge temperature.

4. The method for stable operation of a ring furnace according to claim 1, characterized in that, In the shutdown standby mode, the air flow rate into the ring heating furnace is first lowered.

5. The method for stable operation of a ring furnace as claimed in claim 1, wherein, In the shutdown standby mode, when the standby time is less than the second set time length, the air excess coefficient is controlled to be 0.95-1.

3.

6. The method for stable operation of a ring furnace as claimed in claim 1, wherein, After the shutdown standby mode ends and the rolling is restarted, the air flow rate is first increased, and then the fuel flow rate is increased.

7. The method for stable operation of a ring furnace according to claim 6, characterized in that The air flow rate and the fuel flow rate are adjusted according to the set air-fuel ratio.

8. The method for stable operation of a ring furnace according to claim 7, characterized in that, The temperature rising amplitude is not more than 15℃ each time.

9. The method for stable operation of a ring furnace according to claim 8, characterized in that, After the temperature is raised to the corresponding temperature each time, the air flow rate and the fuel flow rate are adjusted for a set time length.

10. The method for stable operation of a ring furnace as claimed in claim 1, wherein, In the shutdown standby mode, the residual oxygen content of the flue gas is controlled to be 3%-8%.

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