Non-oxidation furnace pressure stability control method and device

Abstract

The invention provides a furnace pressure stability control method and device for a non-oxidation furnace, and the method comprises the steps: calculating the actual flue gas amount according to the obtained air flow, gas flow and furnace temperature; according to the actual flue gas amount and the preset relation between the actual flue gas amount and the baffle opening degree, the baffle opening degree reference value is determined; according to the variable quantity of the baffle opening reference value, the baffle opening set value is made to change smoothly; mapping the opening degree of the cold air mixing regulating valve into the fan rotating speed compensation amount; according to the furnace pressure set value and the obtained furnace pressure feedback value, a fan rotating speed output value is obtained through closed-loop control; superposing the fan rotating speed output value and the fan rotating speed compensation amount to obtain a fan rotating speed set value; and the baffle opening degree and the fan rotating speed are controlled according to the baffle opening degree set value and the fan rotating speed set value correspondingly. According to the invention, stable and rapid control of the furnace pressure of the non-oxidation furnace is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial heating furnace control, and particularly relates to a method and device for stable control of the pressure in a non-oxidizing furnace. Background Art

[0002] Generally, the furnace pressure is determined by the balance between the intake air volume and the exhaust air volume. The baffle opening adjusts the exhaust air volume, while the speed of the exhaust fan affects the power of exhaust. When the baffle opening is large, the exhaust air volume increases and the furnace pressure decreases; vice versa. When the fan speed increases, the exhaust capacity increases, which also reduces the furnace pressure. In the prior art, for the pressure control of a non-oxidizing furnace, a single actuator is mostly used (such as only adjusting the baffle opening or the fan speed to adjust the furnace pressure, and the other actuator is manually adjusted), or the two are independently controlled (the baffle only adjusts the opening according to the furnace section load or the total air flow, and the fan speed adjusts the furnace pressure), which has the following defects: The adjustment of the baffle opening is unstable or manually adjusted. When the opening is too small, the fan speed is too high, increasing energy consumption; when the opening is too large, the fan speed is low when the intake air volume is small, and it is easy to surge; Slow response speed: When the furnace condition changes sharply, it is extremely easy to cause negative pressure in the furnace, inhale air and cause strip oxidation, or damage the equipment due to high pressure in the furnace; when the flue gas temperature is too high and the cold air mixing regulating valve is opened, it cannot respond in time to the furnace pressure fluctuation caused by the change in the cold air mixing volume; Poor anti-interference ability: Sudden disturbances such as combustion fluctuations and the acceleration and deceleration of the strip in the furnace are likely to cause violent pressure oscillations; Low energy efficiency: The dynamic change of the flue gas volume is not considered, and the baffle and the fan cannot be coordinated and optimized; Large disturbance: The adjustment of the baffle and the fan affects each other, resulting in control disturbances. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for stable control of the pressure in a non-oxidizing furnace to achieve rapid and stable adjustment of the furnace pressure during the production process.

[0004] To solve the above technical problems, the present invention provides a method for stable control of the pressure in a non-oxidizing furnace, including: S1. Calculate the actual flue gas volume according to the obtained air flow rate, gas flow rate, and furnace temperature; S2. Determine the reference value of the baffle opening according to the actual flue gas volume and the preset relationship between the actual flue gas volume and the baffle opening; S3. Make the set value of the baffle opening change smoothly according to the change amount of the reference value of the baffle opening; S4. Map the opening of the cold air mixing regulating valve to the fan speed compensation amount; S5. Obtain the fan speed output value through closed-loop control according to the furnace pressure set value and the obtained furnace pressure feedback value; S6. Superimpose the output value of the fan speed and the fan speed compensation amount to obtain the fan speed set value; S7. Control the baffle opening and the fan speed respectively according to the baffle opening set value and the fan speed set value.

[0005] According to the above solution, step S1 includes: S101. Obtain the first coefficient of the flue gas volume according to the air flow rate, the gas type coefficient, and the gas flow rate; the gas type coefficient is determined according to the type of gas; S102. Obtain the second coefficient of the flue gas volume according to the furnace temperature and the set temperature value; S103. Determine the actual flue gas volume according to the first coefficient of the flue gas volume, the second coefficient of the flue gas volume, and the set combustion efficiency correction coefficient.

[0006] According to the above solution, step S2 includes: S201. Determine the calculated value of the baffle opening according to the actual flue gas volume and the set rated flue gas volume; S202. Obtain the baffle opening reference value corresponding to the calculated value of the baffle opening according to the preset comparison table of the calculated value of the baffle opening and the baffle opening reference value.

[0007] According to the above solution, the baffle opening reference value in the comparison table has 20 gears, and the smallest gear is not less than 5%.

[0008] According to the above solution, step S3 includes: S301. Determine the baffle opening change amount according to the current baffle opening reference value, the previous baffle opening reference value, the counter value, and the gradient time constant; the counter value is obtained by counting with a counter, and the gradient time constant is a preset value; S302. Determine the baffle opening set value according to the previous baffle opening reference value and the baffle opening change amount.

[0009] According to the above solution, step S5 adopts PID closed-loop control.

[0010] The present invention also provides a non-oxidizing furnace furnace pressure stable control device, including: An actual flue gas volume calculation module, configured to calculate the actual flue gas volume according to the obtained air flow rate, gas flow rate, and furnace temperature; A baffle opening reference value calculation module, configured to determine the baffle opening reference value according to the actual flue gas volume and the preset relationship between the actual flue gas volume and the baffle opening; A baffle opening set value smoothing control module, configured to make the baffle opening set value change smoothly according to the change amount of the baffle opening reference value; A fan speed compensation amount calculation module, configured to map the opening degree of the cold air mixing regulating valve to the fan speed compensation amount; The fan closed-loop control module is used to closed-loop control the obtained fan speed output value according to the furnace pressure set value and the obtained furnace pressure feedback value; The fan speed set value calculation module is used to superimpose the fan speed output value and the fan speed compensation amount to obtain the fan speed set value.

[0011] According to the above solution, the actual flue gas volume calculation module executes the following steps: Obtain the first coefficient of the flue gas volume according to the air flow rate, the gas type coefficient, and the gas flow rate; the gas type coefficient is determined according to the type of the gas; Obtain the second coefficient of the flue gas volume according to the furnace temperature and the set temperature value; Determine the actual flue gas volume according to the first coefficient of the flue gas volume, the second coefficient of the flue gas volume, and the set combustion efficiency correction coefficient.

[0012] According to the above solution, the baffle opening reference value calculation module executes the following steps: Determine the baffle opening calculation value according to the actual flue gas volume and the set rated flue gas volume; Obtain the baffle opening reference value corresponding to the baffle opening calculation value according to the preset comparison table of the baffle opening calculation value and the baffle opening reference value.

[0013] According to the above solution, the baffle opening set value smoothing control module executes the following steps: Determine the baffle opening change amount according to the current baffle opening reference value, the previous baffle opening reference value, the counter value, and the gradual change time constant; the counter value is obtained by counting with a counter, and the gradual change time constant is a preset value; Determine the baffle opening set value according to the previous baffle opening reference value and the baffle opening change amount.

[0014] Beneficial effects In the present invention, by making the baffle opening set value smoothly change according to the change of the baffle opening reference value, the furnace pressure fluctuation caused by the drastic change of the baffle opening set value is avoided; by mapping the opening degree of the cold air mixing valve to the fan speed compensation amount and superimposing the fan speed compensation amount on the final fan speed set value, the furnace pressure control adopted takes into account the fan speed compensation amount, making the furnace pressure control more in line with the actual production conditions.

[0015] Furthermore, by mapping the baffle opening calculation value to the corresponding baffle opening reference value according to the preset comparison table, when the baffle opening calculation value oscillates in a small range, the baffle opening reference value remains relatively stable, thereby ensuring the stability of the baffle opening set value and realizing the stable control of the furnace pressure. Description of the drawings

[0016] Figure 1 It is a flow chart of the non-oxidizing furnace furnace pressure stable control method according to Embodiment 1 of the present invention; Figure 2 Schematic diagram of baffle control for the first embodiment of the present invention; Figure 3 Schematic diagram of fan speed control for the first embodiment of the present invention. Specific embodiments

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present disclosure. Apparently, the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0018] Embodiment 1: Refer to Figures 1 to 3 , this embodiment discloses a method for controlling the stability of the pressure in a non-oxidizing furnace, including: S1. Calculate the actual flue gas volume based on the obtained air flow rate, gas flow rate, and furnace temperature; S2. Determine the reference value of the baffle opening based on the actual flue gas volume and the preset relationship between the actual flue gas volume and the baffle opening; S3. Smoothly change the set value of the baffle opening according to the change amount of the reference value of the baffle opening; S4. Map the opening of the cold air mixing regulating valve to the fan speed compensation amount; S5. Obtain the fan speed output value through closed-loop control based on the set value of the furnace pressure and the obtained furnace pressure feedback value; S6. Superimpose the fan speed output value and the fan speed compensation amount to obtain the fan speed set value; S7. Control the baffle opening and the fan speed respectively according to the set value of the baffle opening and the set value of the fan speed.

[0019] Further, step S1 includes: S101. Obtain the first coefficient of the flue gas volume based on the air flow rate, the gas type coefficient, and the gas flow rate; the gas type coefficient is determined according to the type of the gas; S102. Obtain the second coefficient of the flue gas volume based on the furnace temperature and the set temperature value; S103. Determine the actual flue gas volume based on the first coefficient of the flue gas volume, the second coefficient of the flue gas volume, and the set combustion efficiency correction coefficient; Specifically, the actual flue gas volume is expressed as: ; wherein, is the actual flue gas volume (unit: m 3 / h), is the air flow rate (unit: Nm 3 / h), k is the gas type coefficient, is the gas flow rate, is the furnace temperature (unit: °C), is the combustion efficiency correction coefficient (in this embodiment, the default value is 0.95 - 0.98); When the gas types are natural gas (CH4), coke oven gas (CO + H2), and mixed gas respectively, the corresponding values of the gas type coefficient k are 10.5, 4.2, and 1.5 - 3.0.

[0020] Furthermore, step S2 includes: S201. Determine the calculated value of the baffle opening according to the actual flue gas volume and the set rated flue gas volume; S202. Obtain the baffle opening reference value corresponding to the calculated value of the baffle opening according to the preset comparison table of the calculated value of the baffle opening and the baffle opening reference value; Specifically, the calculated value of the baffle opening is expressed as:

[0021] where is the set rated flue gas volume, is the calculated value of the baffle opening.

[0022] Furthermore, there are 20 gears for the baffle opening reference value in the comparison table, and the smallest gear is not less than 5% (to maintain the minimum smoke exhaust capacity); The baffle opening reference value is expressed as , and in this embodiment, the comparison table is: .

[0023] Furthermore, step S3 includes: S301. Determine the change amount of the baffle opening according to the current baffle opening reference value, the previous baffle opening reference value, the counter value, and the gradient time constant; the counter value is obtained by counting with a counter, and the gradient time constant is a preset value; S302. Determine the set value of the baffle opening according to the previous baffle opening reference value and the change amount of the baffle opening; Specifically, the set value of the baffle opening is expressed as:

[0024] where is the previous baffle opening reference value, is the current baffle opening reference value, t is the timer value (range: 0 - T), and T is the gradient time constant (set to 10 seconds in this embodiment).

[0025] In this embodiment, the fan speed compensation amount in step S4 is expressed as:

[0026] In the above formula, is the fan speed compensation amount, is the opening degree of the cold air mixing regulating valve (the range is 0~100%), is the maximum value of the set feedforward correction output (the initial value is 10%) Further, step S5 adopts PID closed-loop control; Specifically, the fan speed output value is expressed as , which is obtained from the furnace pressure set value SP and the furnace pressure feedback to PV.

[0027] In this embodiment, the fan speed set value in step S6 is expressed as:

[0028] Among them, is the fan speed set value, and the range of this value is 0~100%.

[0029] Embodiment 2: The principle of this embodiment is basically the same as that of Embodiment 1. On the basis of Embodiment 1, this embodiment discloses a non-oxidizing furnace pressure stability control device, including: An actual flue gas volume calculation module, which is used to calculate the actual flue gas volume according to the obtained air flow rate, gas flow rate, and furnace temperature; A baffle opening reference value calculation module, which is used to determine the baffle opening reference value according to the actual flue gas volume and the preset relationship between the actual flue gas volume and the baffle opening; A baffle opening set value smoothing control module, which is used to make the baffle opening set value change smoothly according to the change amount of the baffle opening reference value; A fan speed compensation amount calculation module, which is used to map the opening degree of the cold air mixing regulating valve to the fan speed compensation amount; A fan closed-loop control module, which is used to obtain the fan speed output value through closed-loop control according to the furnace pressure set value and the obtained furnace pressure feedback value; A fan speed set value calculation module, which is used to superimpose the fan speed output value and the fan speed compensation amount to obtain the fan speed set value.

[0030] Further, the actual flue gas volume calculation module executes the following steps: Obtain the first coefficient of the flue gas volume according to the air flow rate, gas type coefficient, and gas flow rate; the gas type coefficient is determined according to the type of gas; Obtain the second coefficient of the flue gas volume according to the furnace temperature and the set temperature value; Determine the actual flue gas volume according to the first coefficient of flue gas volume, the second coefficient of flue gas volume, and the set combustion efficiency correction coefficient.

[0031] Furthermore, the baffle opening reference value calculation module performs the following steps: Determine the calculated value of the baffle opening according to the actual flue gas volume and the set rated flue gas volume; Obtain the baffle opening reference value corresponding to the calculated value of the baffle opening according to the preset comparison table of the calculated value of the baffle opening and the baffle opening reference value.

[0032] Furthermore, the baffle opening set value smoothing control module performs the following steps: Determine the change amount of the baffle opening according to the current baffle opening reference value, the previous baffle opening reference value, the counter value, and the gradual change time constant; the counter value is obtained by counting with a counter, and the gradual change time constant is a preset value; Determine the baffle opening set value according to the previous baffle opening reference value and the change amount of the baffle opening.

[0033] It should be noted that according to the needs of implementation, each step / component described in this application can be split into more steps / components, or two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0034] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for stable control of the furnace pressure of an oxidation-free furnace, characterized in that, Including: S1. Calculate the actual flue gas volume according to the obtained air flow rate, gas flow rate, and furnace temperature; S2. Determine the reference value of the baffle opening according to the actual flue gas volume and the preset relationship between the actual flue gas volume and the baffle opening; S3. Smoothly change the set value of the baffle opening according to the change amount of the reference value of the baffle opening; S4. Map the opening of the cold air mixing regulating valve to the fan speed compensation amount; S5. Obtain the fan speed output value through closed-loop control according to the set value of the furnace pressure and the obtained furnace pressure feedback value; S6. Superimpose the fan speed output value and the fan speed compensation amount to obtain the fan speed set value; S7. Control the baffle opening and the fan speed respectively according to the set value of the baffle opening and the fan speed set value.

2. The method for stabilizing the furnace pressure of the non-oxidation furnace according to claim 1, characterized in that, Step S1 includes: S101. Obtain the first coefficient of the flue gas volume according to the air flow rate, gas type coefficient, and gas flow rate; the gas type coefficient is determined according to the type of gas; S102. Obtain the second coefficient of the flue gas volume according to the furnace temperature and the set temperature value; S103. Determine the actual flue gas volume according to the first coefficient of the flue gas volume, the second coefficient of the flue gas volume, and the set combustion efficiency correction coefficient.

3. The method for stably controlling the furnace pressure of the non-oxidation furnace according to claim 1, characterized in that, Step S2 includes: S201. Determine the calculated value of the baffle opening according to the actual flue gas volume and the set rated flue gas volume; S202. Obtain the reference value of the baffle opening corresponding to the calculated value of the baffle opening according to the preset comparison table of the calculated value of the baffle opening and the reference value of the baffle opening.

4. The method for stabilizing the furnace pressure of the non-oxidation furnace according to claim 3, characterized in that The reference value of the baffle opening in the comparison table has 20 gears, and the smallest gear is not less than 5%.

5. The method for stabilizing the furnace pressure of the non-oxidizing furnace according to claim 1, characterized in that, Step S3 includes: S301. Determine the change amount of the baffle opening according to the current reference value of the baffle opening, the previous reference value of the baffle opening, the counter value, and the gradual change time constant; the counter value is obtained by counting with a counter, and the gradual change time constant is a preset value; S302. Determine the set value of the baffle opening according to the previous reference value of the baffle opening and the change amount of the baffle opening.

6. The method for stabilizing the furnace pressure of the non-oxidizing furnace according to claim 1, characterized in that, Step S5 adopts PID closed-loop control.

7. A device for stably controlling the furnace pressure of an oxidation-free furnace, characterized in that, Including: Actual flue gas volume calculation module, which is used to calculate the actual flue gas volume according to the obtained air flow rate, gas flow rate, and furnace temperature; Baffle opening reference value calculation module, which is used to determine the reference value of the baffle opening according to the actual flue gas volume and the preset relationship between the actual flue gas volume and the baffle opening; Baffle opening set value smooth control module, which is used to smoothly change the set value of the baffle opening according to the change amount of the reference value of the baffle opening; Fan speed compensation amount calculation module, which is used to map the opening of the cold air mixing regulating valve to the fan speed compensation amount; Fan closed-loop control module, which is used to obtain the fan speed output value through closed-loop control according to the set value of the furnace pressure and the obtained furnace pressure feedback value; Fan speed set value calculation module, which is used to superimpose the fan speed output value and the fan speed compensation amount to obtain the fan speed set value.

8. The oxidation-free furnace pressure stability control device according to claim 7, characterized in that, The actual flue gas volume calculation module executes the following steps: Obtain the first coefficient of the flue gas volume according to the air flow rate, gas type coefficient, and gas flow rate; the gas type coefficient is determined according to the type of gas; Obtain the second coefficient of the flue gas volume according to the furnace temperature and the set temperature value; Determine the actual flue gas volume according to the first coefficient of the flue gas volume, the second coefficient of the flue gas volume, and the set combustion efficiency correction coefficient.

9. The method for stabilizing the furnace pressure of the non-oxidizing furnace according to claim 7, wherein, The baffle opening reference value calculation module executes the following steps: Determine the calculated value of the baffle opening according to the actual flue gas volume and the set rated flue gas volume; Obtain the baffle opening reference value corresponding to the calculated value of the baffle opening according to the comparison table of the preset calculated value of the baffle opening and the baffle opening reference value.

10. The method for stabilizing the furnace pressure of the non-oxidizing furnace according to claim 7, characterized in that The baffle opening set value smoothing control module executes the following steps: Determine the baffle opening change amount according to the current baffle opening reference value, the previous baffle opening reference value, the counter value, and the gradient time constant; the counter value is obtained by counting with a counter, and the gradient time constant is a preset value; Determine the baffle opening set value according to the previous baffle opening reference value and the baffle opening change amount.

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