Heating furnace temperature uniformity control method

Abstract

The invention provides a heating furnace temperature uniformity control method, and particularly relates to the field of heating furnace control, S1, flue gas is sucked into a first flue and a second flue through negative pressure by an induced draft fan, and the flue gas flow directions of the first flue and the second flue are the same; s2, air is fed into a first air duct and a second air duct between the first flue and the second flue through an air blower; the air flow directions of the first air duct and the second air duct are opposite to the flue gas flow directions of the first flue and the second flue; s3, fuel gas is fed into a fuel gas channel between the first air channel and the second air channel; s4, feeding fuel gas and air into a combustion chamber for ignition, and spraying out through a nozzle for heating of a heating furnace. The temperature uniformity of the heating furnace can be improved, and energy consumption is reduced.

Description

Technical Field

[0001] The invention belongs to the field of heating furnace control, and in particular relates to a method for controlling the temperature uniformity of a heating furnace. Background Art

[0002] Heating furnaces include continuous heating furnaces and chamber heating furnaces. Heating furnaces are equipment that heats materials or workpieces to rolling and forging temperatures. Heating furnaces are used in many industries such as petroleum, chemical industry, metallurgy, machinery, heat treatment, surface treatment, building materials, electronics, materials, light industry, daily chemicals, and pharmaceuticals. Heating furnaces are generally equipped with burners. In order to achieve continuous heating, the burners need to meet the requirements of temperature, energy, and flame. In order to meet the needs, existing heating furnaces generally use sub-high-speed burners for bottom heating. Such devices have high energy consumption, high flue gas emission temperatures, and excessively concentrated heat, resulting in poor temperature uniformity in the heating furnace.

[0003] The patent with application number CN201621235353.0 discloses a sub-high-speed burner device, in which a hot air channel and a gas channel are arranged in the burner body, and the hot air channel and the gas channel are connected to the hot air source and the gas source through the hot air inlet and the gas inlet arranged on the upper part of the burner body respectively. The lower end of the burner body is provided with a combustion chamber, and the combustion chamber is provided with a mixing zone, a reflow zone, an acceleration zone and an outlet from top to bottom, and an ignition device is arranged in the mixing zone. The device can shorten the heating time, reduce the exhaust temperature, reduce the flue gas loss, improve the temperature uniformity in the furnace, and shorten the temperature equalization time. However, the heating furnace generally needs to match more than 10 sub-high-speed burners for heating, which still cannot solve the problem of regional heat concentration, and the device has limited effect on improving the temperature uniformity in the furnace.

[0004] In view of the above shortcomings, a method for controlling the temperature uniformity of a heating furnace is now needed, which can improve the temperature uniformity of the heating furnace and reduce energy consumption. Summary of the invention

[0005] The purpose of the present invention is to provide a method for controlling the temperature uniformity of a heating furnace, which can improve the temperature uniformity of the heating furnace and reduce energy consumption.

[0006] The present invention provides the following technical solutions:

[0007] A method for controlling temperature uniformity of a heating furnace, comprising the following steps: S1, using an induced draft fan to suck flue gas into a first flue and a second flue through negative pressure, and the flue gas flows in the first flue and the second flue in the same direction;

[0008] S2, sending air into the first air duct and the second air duct between the first flue and the second flue by a blower; and the air flow direction of the first air duct and the second air duct is opposite to the flue gas flow direction of the first flue and the second flue;

[0009] S3, sending the fuel gas into the fuel gas channel between the first air duct and the second air duct;

[0010] S4. Fuel gas and air are sent into the combustion chamber to be ignited and sprayed out through the nozzle for heating in the heating furnace.

[0011] Preferably, the induced draft fan power is 75KW, and the velocity of the first flue and the second flue is 3 to 4 cubic meters per second;

[0012] Preferably, the blower power is 15KW, and the air velocity of the first air duct and the second air duct is 2 to 3 cubic meters per second.

[0013] Preferably, the fuel gas is natural gas, and the flow rate of the natural gas is 1 to 2 cubic meters per second;

[0014] Preferably, the nozzle flame spray speed is 100 to 150 m / s, and the nozzle spray angle is 6 to 12 degrees;

[0015] Preferably, the nozzle flame spray speed is 120m / s and the nozzle spray angle is 10 degrees

[0016] Preferably, the flue gas preheats the air to a temperature of 450 to 550 degrees Celsius;

[0017] Preferably, the flue gas preheats the air to a temperature of 500 degrees Celsius;

[0018] Preferably, the combustion control of the burner is as follows:

[0019] S1. Set the heating temperature curve on the human-machine interface, and the PLC module receives the heating temperature curve data;

[0020] S2, PID calculation temperature curve setting data; PLC output module transmits PID calculation data to the electric regulating valves of air and fuel gas; controls the electric regulating valves to adjust gas flow;

[0021] S3, the thermocouple in the heating furnace collects temperature and transmits the temperature collection signal back to the PLC module; the collected temperature is compared with the set temperature, and the control signal is output to the electric control valve through PID to realize the control of the electric control valve.

[0022] S4. Repeat the above operations to realize the combustion control of the burner.

[0023] Beneficial effects of the present invention:

[0024] 1. The present invention recycles the waste flue gas, which can reduce the heat required to be provided by the heating furnace body and greatly reduce energy consumption;

[0025] 2. The present invention preheats the air and sprays it out through an inclined burner, which can ensure that the airflow refluxes in the heating furnace, improves the uniform distribution of the furnace temperature, and avoids the problem of uneven furnace temperature due to concentrated heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0027] Figure 1 It is a schematic diagram of the flue gas flow direction of the present invention. DETAILED DESCRIPTION

[0028] Example 1

[0029] A method for controlling the temperature uniformity of a heating furnace comprises the following steps: S1, sucking the flue gas into the first flue and the second flue through negative pressure through an induced draft fan, and the flue gas directions of the first flue and the second flue are the same; the induced draft fan power is 75KW, and the speed of the first flue and the second flue is 3 cubic meters per second; S2, sending air into the first air duct and the second air duct between the first flue and the second flue through a blower; and the air flow directions of the first air duct and the second air duct are opposite to the flue gas directions of the first flue and the second flue; the blower power is 15KW, and the air speed of the first air duct and the second air duct is 2 cubic meters per second; the flue gas preheats the air to a temperature of 450 degrees Celsius; the waste flue gas transfers heat through countercurrent in the opposite direction of the air flow to preheat the air, and the waste flue gas is recycled, which can reduce the heat required to be provided by the heating furnace body and can greatly reduce and reduce energy consumption; in order to improve the heat conduction efficiency, as shown in the attached Figure 1 The heat transfer wall of the structure can be set to a curve to increase the heat transfer area; S3, send the fuel gas into the fuel gas channel between the first air duct and the second air duct; the fuel gas is natural gas, and the natural gas flow rate is 1 cubic meter / second; S4, the fuel gas and air are sent into the combustion chamber to be ignited, and sprayed out through the nozzle for heating in the heating furnace; the nozzle flame spray speed is 100m / s, and the nozzle spray angle is 6 degrees. The setting of the nozzle can be set to two rows, upper and lower, and the number of each row can be determined according to actual needs; the combustion control of the burner is as follows: set the heating temperature curve on the human-machine interface, and the PLC module receives the heating temperature curve data; PID calculates the temperature curve setting data; the PLC output module transmits the PID calculation data to the electric control valve of the air and fuel gas; controls the electric control valve to adjust the gas flow; the thermocouple in the heating furnace collects temperature, and the temperature collection signal is sent back to the PLC module; the collected temperature is compared with the set temperature, and the control signal is output to the electric control valve through PID to realize the control of the electric control valve, and the above operations are repeated to realize the combustion control of the burner.

[0030] Example 2

[0031] A method for controlling the temperature uniformity of a heating furnace, the steps are as follows: S1, using an induced draft fan to suck smoke into a first flue and a second flue through negative pressure, and the smoke flows in the first flue and the second flue are the same; the induced draft fan power is 75KW, and the flow rate of the first flue and the second flue is 3.5 cubic meters per second; S2, using a blower to send air into the first air duct and the second air duct between the first flue and the second flue; and the air flow directions of the first air duct and the second air duct are opposite to the smoke flow directions of the first flue and the second flue; the blower power is 15KW, and the air flow rates of the first air duct and the second air duct are 2.5 cubic meters per second; the smoke preheats the air to a temperature of 500 degrees Celsius; the waste smoke transfers heat through countercurrent in the opposite direction of the air flow to preheat the air, and the waste smoke is recycled, which can reduce the heat required to be provided by the heating furnace body and can greatly reduce and reduce energy consumption; in order to improve the heat conduction efficiency, as shown in the attached Figure 1 The structural heat transfer wall can be set to a curve to increase the heat transfer area; S3, the fuel gas is sent into the fuel gas channel between the first air duct and the second air duct; the fuel gas is natural gas, and the natural gas flow rate is 1.5 cubic meters per second; S4, the fuel gas and air are sent into the combustion chamber to be ignited, and then sprayed out through the nozzle for heating in the heating furnace; the nozzle flame spray speed is 120m / s, and the nozzle spray angle is 10 degrees; the nozzle setting can be set to two rows, upper and lower, and the number of each row can be determined according to actual needs; the combustion control of the burner is as follows: the heating temperature curve is set on the human-machine interface, and the PLC module receives the heating temperature curve data; PID calculates the temperature curve setting data; the PLC output module transmits the PID calculation data to the electric control valve of the air and fuel gas; the electric control valve is controlled to adjust the gas flow; the thermocouple in the heating furnace collects temperature, and the temperature collection signal is sent back to the PLC module; the collected temperature is compared with the set temperature, and the control signal is output to the electric control valve through PID to realize the control of the electric control valve, and the above operations are repeated to realize the combustion control of the burner.

[0032] Example 3

[0033] A method for controlling the temperature uniformity of a heating furnace comprises the following steps: S1, sucking the flue gas into the first flue and the second flue through negative pressure through an induced draft fan, and the flue gas directions of the first flue and the second flue are the same; the induced draft fan power is 75KW, and the speed of the first flue and the second flue is 3.7 cubic meters per second; S2, sending air into the first air duct and the second air duct between the first flue and the second flue through a blower; and the air flow directions of the first air duct and the second air duct are opposite to the flue gas directions of the first flue and the second flue; the blower power is 15KW, and the air speed of the first air duct and the second air duct is 2.7 cubic meters per second; the flue gas preheats the air to a temperature of 520 degrees Celsius; the waste flue gas transfers heat through countercurrent in the opposite direction of the air flow to preheat the air, and the waste flue gas is recycled, which can reduce the heat required to be provided by the heating furnace body and can greatly reduce and reduce energy consumption; in order to improve the heat conduction efficiency, as shown in the attached Figure 1 The structural heat transfer wall can be set to a curve to increase the heat transfer area; S3, the fuel gas is sent into the fuel gas channel between the first air duct and the second air duct; the fuel gas is natural gas, and the natural gas flow rate is 1.7 cubic meters per second; S4, the fuel gas and air are sent into the combustion chamber to be ignited, and then sprayed out through the nozzle for heating in the heating furnace; the nozzle flame injection speed is 130m / s, and the nozzle injection angle is 11 degrees; the nozzle setting can be set to two rows, upper and lower, and the number of each row can be determined according to actual needs; the combustion control of the burner is as follows: the heating temperature curve is set on the human-machine interface, and the PLC module receives the heating temperature curve data; PID calculates the temperature curve setting data; the PLC output module transmits the PID calculation data to the electric control valve of the air and fuel gas; the electric control valve is controlled to adjust the gas flow; the thermocouple in the heating furnace collects temperature, and the temperature collection signal is transmitted back to the PLC module; the collected temperature is compared with the set temperature, and the control signal is output to the electric control valve through PID to realize the control of the electric control valve, and the above operations are repeated to realize the combustion control of the burner.

[0034] Example 4

[0035] A method for controlling the temperature uniformity of a heating furnace comprises the following steps: S1, sucking the flue gas into the first flue and the second flue through negative pressure through an induced draft fan, and the flue gas directions of the first flue and the second flue are the same; the induced draft fan power is 75KW, and the speed of the first flue and the second flue is 4 cubic meters per second; S2, sending air into the first air duct and the second air duct between the first flue and the second flue through a blower; and the air flow directions of the first air duct and the second air duct are opposite to the flue gas directions of the first flue and the second flue; the blower power is 15KW, and the air speed of the first air duct and the second air duct is 3 cubic meters per second; the flue gas preheats the air to a temperature of 550 degrees Celsius; the waste flue gas transfers heat through countercurrent in the opposite direction of the air flow to preheat the air, and the waste flue gas is recycled, which can reduce the heat required to be provided by the heating furnace body and can greatly reduce and reduce energy consumption; in order to improve the heat conduction efficiency, as shown in the attached Figure 1 The structural heat transfer wall can be set to a curve to increase the heat transfer area; S3, the fuel gas is sent into the fuel gas channel between the first air duct and the second air duct; the fuel gas is natural gas, and the natural gas flow rate is 2 cubic meters per second; S4, the fuel gas and air are sent into the combustion chamber to be ignited, and then sprayed out through the nozzle for heating in the heating furnace; the nozzle flame spray speed is 150m / s, and the nozzle spray angle is 12 degrees; the nozzle setting can be set to two rows, upper and lower, and the number of each row can be determined according to actual needs; the combustion control of the burner is as follows: the heating temperature curve is set on the human-machine interface, and the PLC module receives the heating temperature curve data; PID calculates the temperature curve setting data; the PLC output module transmits the PID calculation data to the electric control valve of the air and fuel gas; the electric control valve is controlled to adjust the gas flow; the thermocouple in the heating furnace collects temperature, and the temperature collection signal is sent back to the PLC module; the collected temperature is compared with the set temperature, and the control signal is output to the electric control valve through PID to realize the control of the electric control valve, and the above operations are repeated to realize the combustion control of the burner.

[0036] Experimental data:

[0037] The conventional method was used as the control group, and 85 tons of 17CrNiMo6 were heated in a single furnace to the required standard; Examples 1-4 were used to heat 85 tons of 17CrNiMo6 in a single furnace, and the specific data are as follows:

[0038]

[0039] The temperature uniformity of the temperature of Examples 1-4 and the control group was tested respectively. The temperature of Examples 1-3 was generally uniform, and there was no problem of excessive concentration of the temperature of the forged steel; while the control group using the traditional heating method had the problem of excessive concentration of the temperature of the forged steel. And from the above table, it can be seen that the natural gas consumption of Examples 1-4 is significantly less than that of the control group.

[0040] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for controlling the temperature uniformity of a heating furnace, characterized in that: The steps are as follows: S1, using an induced draft fan to suck smoke into a first smoke duct and a second smoke duct through negative pressure, and the smoke flows in the first smoke duct and the second smoke duct have the same direction; S2, sending air into the first air duct and the second air duct between the first flue and the second flue by a blower; and the air flow direction of the first air duct and the second air duct is opposite to the flue gas flow direction of the first flue and the second flue; S3, sending the fuel gas into the fuel gas channel between the first air duct and the second air duct; S4. Fuel gas and air are sent into the combustion chamber to be ignited and sprayed out through the nozzle for heating in the heating furnace.

2. The method for controlling the temperature uniformity of a heating furnace according to claim 1, characterized in that: The combustion control of the burner is as follows: the heating temperature curve is set on the human-machine interface, and the PLC module receives the heating temperature curve data; PID calculates the temperature curve setting data; The PLC output module transmits PID calculation data to the electric regulating valves of air and fuel gas; controls the electric regulating valves to adjust the gas flow; The thermocouple in the heating furnace collects temperature and transmits the temperature collection signal back to the PLC module; The collected temperature is compared with the set temperature, and a control signal is output to the electric regulating valve through PID to control the electric regulating valve. The above operation is repeated to realize the combustion control of the burner.

3. The method for controlling the temperature uniformity of a heating furnace according to claim 1, characterized in that: The induced draft fan power is 75KW, and the velocity of the first and second flue is 3 to 4 cubic meters per second.

4. The method for controlling the temperature uniformity of a heating furnace according to claim 1, characterized in that: The blower power is 15KW, and the air velocity of the first air duct and the second air duct is 2 to 3 cubic meters per second.

5. The method for controlling the temperature uniformity of a heating furnace according to claim 1, characterized in that: The fuel gas is natural gas, and the flow rate of natural gas is 1 to 2 cubic meters per second.

6. The method for controlling the temperature uniformity of a heating furnace according to claim 1, characterized in that: The nozzle flame spray speed is 100 to 150 m / s, and the nozzle spray angle is 6 to 12 degrees.

7. A method for controlling temperature uniformity of a heating furnace according to claim 6, characterized in that: The nozzle flame jet speed is 120m / s and the nozzle jet angle is 10 degrees.

8. The method for controlling the temperature uniformity of a heating furnace according to claim 1, characterized in that: The flue gas preheats the air to a temperature of 450 to 550 degrees Celsius.

9. A method for controlling temperature uniformity of a heating furnace according to claim 8, characterized in that: The flue gas preheats the air to a temperature of 500 degrees Celsius.

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