Heating furnace flue gas temperature control method

Abstract

The present invention discloses a method for controlling the temperature of furnace gas in a heating furnace, belonging to the technical field of metal smelting. The method is as follows: when the head end of the steel billet moves to a steel billet displacement detector, the controller receives the information detected by the corresponding temperature sensor and compares and judges it with the corresponding target temperature value preset therein. According to the judgment result, the openings of the gas flow valve and the air valve are controlled to increase or decrease. At the same time, according to the mathematical model established therein, the action time of these two valves is calculated. When the timing reaches this time, the temperature is compared again. If the values of the two are different, the process of judging the increase / decrease in temperature and controlling these two valves is cycled until the real-time temperature value is the same as the target temperature value, thereby controlling the temperature of the furnace gas in the heating furnace. The present invention can solve the problem that the existing temperature control of furnace gas in a heating furnace has a large temperature control error in manual operation, which affects the productivity, operation rate and quality of finished steel of the rolling mill.

Description

Technical Field

[0001] The present invention relates to the technical field of metal smelting, and in particular to a method for controlling the temperature of furnace gas in a heating furnace. Background Art

[0002] A heating furnace is a device used in the iron and steel industry to heat steel billets before rolling. The control of the furnace gas temperature in the heating furnace not only affects the productivity and operation rate of the rolling mill, but also directly affects the quality of the finished steel. The control of the heating furnace gas temperature is usually divided into three thermal zones along the length of the heating furnace in sequence: namely, the preheating zone, the heating zone, and the soaking zone; during production, multiple steel billets of the same or different specifications enter the heating furnace sequentially from the input channel of the heating furnace, and are output after being heated in the preheating zone, the heating zone, and the soaking zone. The current control of the heating furnace gas temperature is as follows: First, a combustion control model is formulated manually based on the empirical values of many years of process requirements for rolling steel billets, and the air-fuel ratio is set. Then, the gas flow control valve or air flow control valve of each stage of the heating furnace is manually adjusted to make the furnace gas temperature of each stage in the heating furnace reach the temperature required by the process. There are problems such as large temperature control errors and different heating qualities caused by different understandings of the production process and operation habits of the equipment by manual workers, which affect the productivity, operation rate of the rolling mill, and the quality of the finished steel. Summary of the Invention

[0003] The present invention provides a method for controlling the temperature of furnace gas in a heating furnace, which can solve the problem that the existing control of the temperature of furnace gas in a heating furnace has large manual operation temperature control errors, thus affecting the productivity, operation rate of the rolling mill, and the quality of the finished steel.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows: The method for controlling the temperature of the furnace gas of the heating furnace is as follows: A detector for detecting the specifications of the steel billet is set in the running track of the steel billet input into the heating furnace. Temperature sensors and steel billet displacement detectors are respectively set in each heat section of the heating furnace, and the target temperature of each specification of steel billet in each of the heat sections is preset in the controller. When the steel billet is input into the heating furnace, the detector detects the specification information of the steel billet in real time and transmits it to the controller. When the head end of the steel billet moves to the steel billet displacement detector in a heat section, the controller receives the real-time temperature value information detected by the corresponding temperature sensor and compares it with the preset corresponding target temperature value, and then makes a judgment on heating or cooling, and controls the opening of the gas flow valve and the air valve to increase or decrease according to the judgment result. At the same time, timing is started, and according to the mathematical model established therein, the time for the opening of the gas flow valve and the air valve to increase or decrease is calculated. This time value is T. When the timing reaches T, the real-time temperature value is compared with the target temperature value again. If the two values are different, the process of judging heating or cooling and controlling the opening of the gas flow valve and the air valve is cycled until the real-time temperature value is the same as the target temperature value, so as to control the temperature of the furnace gas of the heating furnace;

[0005] The established mathematical model is: T = T0 + d

[0006] Where: T0 is the minimum in-furnace time of the steel billet of this specification in the basic table of the heating furnace temperature control rhythm;

[0007] d is the difference between an actual maximum in-furnace time value and an actual minimum in-furnace time value among the actual in-furnace time values of all steel billets of the same specification in a time period.

[0008] In the above technical solution, a more specific technical solution may further be: The steel billet displacement detector includes a rangefinder and a plurality of photoelectric switches used in conjunction with the rangefinder. The rangefinder is set in the running track of the walking beam at the input end of the heating furnace, and the photoelectric switches are respectively set in the running track of the walking beam in each heat section of the heating furnace.

[0009] Further: The controller makes a judgment on heating or cooling with the thickness of the steel billet setting the priority, and the one with the smallest steel billet thickness value has the highest priority.

[0010] Further: When the steel billet is at the end of the previous heat section, the furnace gas temperature of the next heat section rises or falls to the corresponding target temperature of this heat section.

[0011] Due to adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0012] 1. Due to the method of this solution, by the controller continuously comparing the real-time temperature value of the heating furnace flue gas with the target temperature value and adjusting the opening size of the valve, not only is the temperature control accuracy high, reducing the fluctuation of the flue gas temperature, improving the productivity and operation rate of the rolling mill, ensuring the heating quality and the quality of the finished steel, but also real-time temperature compensation can be completed, avoiding the temperature of the billet being too high or too low and keeping it at a stable level all the time;

[0013] 2. Due to the adoption of the mathematical model T = T0 + d, to control the time for increasing or decreasing the opening of the gas flow valve and the air valve with T, the waste of gas consumption is reduced. Specific implementation manner

[0014] The present invention will be further described in detail below in conjunction with embodiments:

[0015] The method for controlling the temperature of the flue gas of this heating furnace is as follows: A detector is set in the running track of the billet input into the heating furnace, temperature sensors and billet displacement detectors are respectively set in each heating section of the heating furnace, and the target temperature of each specification of billet in each heating section is preset in the controller; the detector is used to detect the specification information of the billet in real time and transmit it to the controller; the billet displacement detector is used to detect the movement information of the billet in real time and transmit it to the controller. Among them, the billet displacement detector includes a rangefinder and a plurality of photoelectric switches used in conjunction with the rangefinder. The rangefinder is set in the running track of the walking beam at the input end of the heating furnace, and the photoelectric switches are respectively set in the running tracks of the walking beams in each heating section of the heating furnace; the temperature sensor is used to detect the temperature information in the corresponding heating section of the heating furnace in real time and transmit it to the controller;

[0016] When the billet is input into the heating furnace, the detector transmits the specification information of the billet detected in real time to the controller. When the head end of the billet moves to the billet displacement detector in a heating section, the controller receives the real-time temperature value information detected by the corresponding temperature sensor and compares it with the preset target temperature value of the corresponding specification to judge whether to increase or decrease the temperature. Then, according to the judgment result, it controls the opening of the gas flow valve and the opening of the air valve to increase or decrease. At the same time, it starts timing, and according to the mathematical model established therein, calculates the time for increasing or decreasing the opening of the valve, and this time value is T. When the timing reaches T, it compares the real-time temperature value with the target temperature value again. If the two values are different, it loops through the process of judging whether to increase or decrease the temperature and controlling the opening of the gas flow valve and the opening of the air valve until the real-time temperature value is the same as the target temperature value;

[0017] The established mathematical model is: T = T0 + d

[0018] Among them: T0 is the minimum in-furnace time in the heating furnace temperature control rhythm base table.

[0019] d is the difference between an actual maximum in-furnace time value and an actual minimum in-furnace time value among the actual in-furnace time values of all billets of the same specification within a period of time.

[0020] In this embodiment, d is 20 minutes.

[0021] The above controller's judgment on heating or cooling is as follows: when the real-time temperature value is greater than the target temperature value, it is judged as cooling, and the openings of the gas flow valve and the air valve are controlled to decrease; when the real-time temperature value is less than the target temperature value, it is judged as heating, and the openings of the gas flow valve and the air valve are controlled to increase.

[0022] This judgment sets priorities according to the thickness of the billet, with the billet having the smallest thickness value being the highest level; in this embodiment, the highest level is set as level 1, the secondary level as level 2, and so on; assuming the thickness is h, billets with h ≤ 2 mm are of level 1, billets with 2 < h ≤ 2.5 mm are of level 2, billets of unconventional specifications are of level 3, and billets with h > 2.5 mm are of level 4;

[0023] When the billet runs to the end of the previous heating section, the furnace gas temperature in the next heating section rises or falls to the corresponding target temperature of this heating section.

[0024] The present invention compares the real-time temperature value of the furnace gas in the heating furnace with the target temperature value through the controller in a loop, and adopts the mathematical model of T = T0 + d to control the time for the openings of the gas flow valve and the air valve to increase or decrease at time T. Not only is the temperature control accuracy high, the fluctuation of the furnace gas temperature is reduced, the productivity and operation rate of the rolling mill are improved, the heating quality and the quality of the finished steel are ensured, but also the temperature compensation can be completed in real time, avoiding the billet from being too hot or too cold and keeping it at a stable level all the time; at the same time, the consumption and waste of gas are reduced.

Claims

1. A method for controlling the temperature of the furnace gas in a heating furnace, characterized in that: A detector for detecting the specification of the steel billet is set in the running track of the steel billet input into the heating furnace. Temperature sensors and steel billet displacement detectors are respectively set in each heating section of the heating furnace, and the target temperature of each specification of steel billet in each of the heating sections is preset in the controller. When the steel billet is input into the heating furnace, the detector detects the specification information of the steel billet in real time and transmits it to the controller. When the head end of the steel billet moves to the steel billet displacement detector in a heating section, the controller receives the real-time temperature value information detected by the corresponding temperature sensor and compares it with the preset corresponding target temperature value, and then makes a judgment on heating or cooling, and controls the opening of the gas flow valve and the opening of the air valve to increase or decrease according to the judgment result. At the same time, timing is started. According to the mathematical model established therein, the time for the opening of the gas flow valve and the opening of the air valve to increase or decrease is calculated. This time value is T. When the timing reaches T, the real-time temperature value is compared with the target temperature value again. If the two values are different, the process of judging heating or cooling and controlling the opening of the gas flow valve and the opening of the air valve is cycled until the real-time temperature value is the same as the target temperature value, so as to control the furnace gas temperature of the heating furnace; The established mathematical model is: T = T0 + d Where: T0 is the minimum in-furnace time of the steel billet of this specification in the basic table of the heating furnace temperature control rhythm; d is the difference between an actual maximum in-furnace time value and an actual minimum in-furnace time value among the actual in-furnace time values of all steel billets of the same specification in a time period.

2. The method for controlling the temperature of the furnace gas of the heating furnace according to claim 1, characterized in that: The steel billet displacement detector includes a rangefinder and a plurality of photoelectric switches used in conjunction with the rangefinder. The rangefinder is set in the running track of the walking beam at the input end of the heating furnace, and the photoelectric switches are respectively set in the running track of the walking beam in each heating section of the heating furnace.

3. The method for controlling the temperature of the furnace gas of the heating furnace according to claim 1 or 2, characterized in that: The controller makes a judgment on heating or cooling with the thickness of the steel billet setting the priority, and the steel billet with the smallest thickness value has the highest priority.

4. The method for controlling the temperature of the furnace gas of the heating furnace according to claim 3, characterized in that: When the steel billet is at the end of the previous heating section, the furnace gas temperature in the next heating section rises or falls to the corresponding target temperature of this heating section.