Automatic regulation and control method for boiler furnace negative pressure

Abstract

The application discloses a kind of automatic regulation control methods of boiler furnace negative pressure, first set the set range of multiple groups current damper baffle opening value and the set range of corresponding negative pressure deviation absolute value, the set range of each current damper baffle opening value and the set range of negative pressure deviation absolute value are corresponding to the corresponding damper baffle opening adjustment value, establish the judgment condition of multiple damper baffle opening adjustment value;Subsequently, according to the current damper opening value obtained and the deviation absolute value matched with the established damper baffle judgment condition are adjusted.It is characterized in that: control method implementation process is simple, control process is efficient, set new judgment condition and control logic in original boiler control system can realize furnace negative pressure automatic regulation, without increasing additional investment;Fully consider the influence of current damper baffle opening value on opening adjustment amount, reduce the furnace fluctuation in the adjustment process, help to stabilize boiler combustion.

Description

Technical fields:

[0001] This invention relates to the field of boiler automatic control, and in particular to an automatic adjustment and control method for boiler furnace negative pressure. Background technology:

[0002] During boiler combustion, the furnace must be maintained under negative pressure while meeting airflow requirements. The magnitude of the furnace negative pressure significantly impacts boiler energy efficiency and safe operation. Excessive negative pressure increases the amount of combustion heat carried away by the flue gas, while also increasing the load on the induced draft fan and flue gas heat loss, leading to increased boiler coal consumption. Conversely, excessively low or positive negative pressure can cause boiler backflow and fire spillage outside the furnace, seriously threatening equipment and personnel safety. Stable and reliable control of the boiler negative pressure directly affects boiler operational safety and economic efficiency.

[0003] Currently, boiler furnace negative pressure control mostly adopts PID control, and its control process is as follows: Figure 1 As shown, the control deviation is calculated based on the given value and actual output value of the furnace negative pressure. This deviation is then combined into a control quantity using proportional, integral, and derivative relationships to control the controlled object (furnace negative pressure regulating valve). This control method is linear. However, in actual production, boiler operating parameters exhibit nonlinear characteristics due to changes in coal quality and air volume. This causes the PID control logic of the regulating valve to fail to effectively track these changes. During PID automatic control operation, the damper opening changes drastically, leading to violent fluctuations in the furnace negative pressure. Therefore, manual adjustment by operators is required for extended periods. This adjustment process is lagging, highly arbitrary, and has unstable effects. Furthermore, frequent adjustments can severely impact stable combustion in the boiler, thereby affecting the unit's economy and safety. Summary of the Invention:

[0004] The purpose of this invention is to provide an automatic adjustment and control method for furnace negative pressure, which comprehensively considers the influence of the current damper opening and negative pressure deviation on the opening adjustment amount, and achieves precise control of furnace negative pressure by establishing an associated control loop.

[0005] This invention is implemented by the following technical solution: an automatic adjustment and control method for negative pressure in a boiler furnace, wherein a negative pressure sensor is installed in the furnace, and the negative pressure in the furnace is controlled by adjusting the opening of the damper; including the following steps:

[0006] S100: Set multiple sets of current damper opening value setting ranges and corresponding negative pressure deviation absolute value setting ranges. Each set of current damper opening value setting ranges and negative pressure deviation absolute value setting ranges correspond to the corresponding damper opening adjustment value. Establish multiple sets of damper opening adjustment value judgment conditions.

[0007] Set the setting range for the absolute value of the standard negative pressure deviation and the setting value for the furnace negative pressure;

[0008] S200: Obtain the current furnace negative pressure through the negative pressure sensor;

[0009] S300: Calculate the absolute value of the negative pressure deviation between the current furnace negative pressure and the furnace negative pressure set value obtained in step S200;

[0010] S400: Determine the absolute value of the negative pressure deviation in step S300. If the absolute value of the negative pressure deviation is within the set range of the standard negative pressure deviation absolute value, return to execute steps S200, S300 and S400. If the absolute value of the negative pressure deviation is not within the set range of the standard negative pressure deviation absolute value, obtain the current damper opening value.

[0011] S500: Based on the current damper opening value obtained in S400 and the absolute value of negative pressure deviation obtained in S300, match the judgment condition for damper opening adjustment value established in S100 to obtain the damper opening adjustment value; and obtain the negative pressure deviation value.

[0012] S600: The damper opening is adjusted using the damper opening adjustment value and negative pressure deviation value obtained in S500; when the negative pressure deviation value is positive, the damper opening is increased; when it is negative, the damper opening is decreased.

[0013] S700: After adjustment, the delay phase begins. During the delay phase, the damper does not move. After the delay ends, the cycle returns to step S200.

[0014] Preferably, in step S100, when the absolute value of the negative pressure deviation is set within the same range, the damper opening adjustment value is positively correlated with the current damper opening value.

[0015] Preferably, in step S100, a furnace pressure limit value is preset. Between steps S200 and S300, the following step is also included: determining whether the current furnace negative pressure in S200 has reached or exceeded the preset furnace pressure limit value. If it has reached or exceeded the preset furnace pressure limit value, the automatic control is switched to manual control and an alarm is issued.

[0016] Preferably, in step S100, a preset damper opening deviation value is set, and during the delay phase of step S700, the following steps are also included: obtaining the actual opening of the damper on site, and calculating the deviation value between the theoretical opening of the damper after adjustment and the actual opening of the damper on site. When the deviation value exceeds the preset damper opening deviation value, the automatic control is exited and an alarm is issued.

[0017] Advantages of this invention: The control method is simple to implement and highly efficient. Automatic furnace negative pressure adjustment can be achieved by setting new judgment conditions and control logic in the original boiler control system, without additional investment. Multiple judgment conditions for damper opening adjustment values ​​are established in the original control system. The dampers automatically execute corresponding adjustment control based on the monitored furnace negative pressure deviation value. Relying on multiple judgment conditions and automatic control, the boiler furnace negative pressure deviation value can be kept within the set range of the standard negative pressure deviation absolute value, solving the problem that traditional PID cannot track and adjust in real time. Furthermore, this automatic control process reduces manual operation and lowers the workload of operators. When establishing judgment conditions, the influence of the current damper opening value on the opening adjustment amount is fully considered. When the current damper opening is small, the corresponding damper opening adjustment amount is small, reducing furnace fluctuations during the adjustment process, which helps stabilize boiler combustion and improves the economy and safety of boiler operation. A time delay is set after adjustment to provide sufficient reaction time for the boiler system, helping the boiler to restore stable combustion. Attached image description:

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This refers to the existing PID control process.

[0020] Figure 2 This is a flowchart illustrating an automatic adjustment and control method for negative pressure in a boiler furnace according to the present invention. Detailed implementation method:

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] like Figure 2 The present invention discloses an automatic adjustment and control method for negative pressure in a boiler furnace. A negative pressure sensor is installed in the furnace to monitor the negative pressure in the furnace. Typically, there is more than one negative pressure sensor. The average value of the negative pressure in the furnace monitored by multiple negative pressure sensors is used as the current negative pressure value in the furnace. The negative pressure in the furnace is controlled by adjusting the opening of the damper.

[0023] Specifically, the automatic adjustment and control method of the present invention includes the following steps:

[0024] S100: Set the setting range of multiple sets of current damper opening values ​​and the corresponding setting range of negative pressure deviation absolute values. Each set of current damper opening value setting range and negative pressure deviation absolute value setting range corresponds to the corresponding damper opening adjustment value. Establish the judgment conditions for multiple sets of damper opening adjustment values; and set the setting range of standard negative pressure deviation absolute value, furnace negative pressure setting value, and furnace pressure limit value.

[0025] Taking a certain boiler operating condition as an example, the judgment conditions for the multiple sets of damper opening adjustment values ​​are as follows:

[0026] Judgment condition A: If the current damper opening value is less than 30% and the absolute value of the negative pressure deviation is between 100 and 300 Pa, then the corresponding damper opening adjustment value is 1%.

[0027] Judgment condition B: If the current damper opening value is less than 30% and the absolute value of the negative pressure deviation is >300Pa, then the corresponding damper opening adjustment value is 3%.

[0028] Judgment condition C: If the current damper opening value is 30-45% and the absolute value of the negative pressure deviation is 100-300Pa, then the corresponding damper opening adjustment value is 2%.

[0029] Judgment condition D: If the current damper opening value is 30-45% and the absolute value of the negative pressure deviation is >300Pa, then the corresponding damper opening adjustment value is 6%.

[0030] Judgment condition E: If the current damper opening value is >45% and the absolute value of the negative pressure deviation is between 100 and 300 Pa, then the corresponding damper opening adjustment value is 3%.

[0031] Judgment condition F: If the current damper opening value is >45% and the absolute value of the negative pressure deviation is >300Pa, then the corresponding damper opening adjustment value is 10%.

[0032] In traditional PID control, the negative pressure deviation is calculated using the PID system and converted into the damper opening. A larger negative pressure deviation results in a larger damper opening, and vice versa. Compared to traditional PID control, this approach considers the influence of the current damper opening. Different damper openings result in different ranges of furnace negative pressure variation. For the same 1% action, a smaller damper opening leads to a larger furnace negative pressure change, and vice versa. Therefore, the automatic control loop formed here can effectively reduce furnace fluctuations during the adjustment process.

[0033] After establishing the judgment conditions for the above-mentioned damper switch adjustment values, the established judgment conditions are used to automatically adjust and control the furnace negative pressure. That is,

[0034] S200: Obtain the current furnace negative pressure through the negative pressure sensor; and determine whether the current furnace negative pressure has reached or exceeded the preset furnace pressure limit value. If the current furnace negative pressure has not reached or exceeded the preset furnace pressure limit value, proceed to step S300.

[0035] If the current furnace negative pressure reaches or exceeds the preset furnace pressure limit, a delay is performed. After the delay ends, it is determined again whether the current furnace negative pressure reaches or exceeds the preset furnace pressure limit. If the current furnace negative pressure after the delay does not reach or exceed the preset furnace pressure limit, step S300 is performed. If the current furnace negative pressure after the delay still reaches or exceeds the preset furnace pressure limit, automatic control is exited and an alarm is issued.

[0036] Taking a certain boiler operating condition as an example, the preset furnace pressure limit values ​​are 1000Pa and -2000Pa respectively. If, after a delay, the current furnace negative pressure still reaches or exceeds 1000Pa, or reaches or falls below -2000Pa, then the automatic control will be exited and an alarm will be issued.

[0037] S300: Calculate the absolute value of the negative pressure deviation between the current furnace negative pressure and the furnace negative pressure set value obtained in step S200;

[0038] S400: Determine the absolute value of the negative pressure deviation in step S300. If the absolute value of the negative pressure deviation is within the set range of the standard negative pressure deviation absolute value, return to execute steps S200-S400; if the absolute value of the negative pressure deviation is not within the set range of the standard negative pressure deviation absolute value, obtain the current damper opening value.

[0039] S500: Based on the current damper opening value obtained in S400 and the absolute value of negative pressure deviation obtained in S300, match the judgment condition for damper opening adjustment value established in S100 to obtain the damper opening adjustment value; and obtain the negative pressure deviation value.

[0040] S600: The damper opening is adjusted using the damper opening adjustment value and negative pressure deviation value obtained in S500. When the negative pressure deviation value is positive, the damper opening is increased; when the negative pressure deviation value is negative, the damper opening is decreased.

[0041] S700: After adjustment, the delay phase begins. During the delay phase, the damper does not move. After the delay ends, the cycle returns to step S200.

[0042] In addition, in step S100, the damper opening deviation value can be preset, and accordingly, the following operations are performed during the delay phase of step S700: obtain the actual opening of the damper on site, and calculate the deviation value between the theoretical opening of the damper after adjustment and the actual opening on site. When the deviation value exceeds the preset damper opening deviation value, it indicates that the damper on site cannot be controlled synchronously, so the automatic control is exited and an alarm is issued.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An automatic adjustment and control method for negative pressure in a boiler furnace, comprising a negative pressure sensor installed in the furnace, and controlling the negative pressure in the furnace by adjusting the opening of the damper; characterized in that, Includes the following steps: S100: Set multiple sets of current damper opening value setting ranges and corresponding negative pressure deviation absolute value setting ranges. Each set of current damper opening value setting ranges and negative pressure deviation absolute value setting ranges correspond to the corresponding damper opening adjustment value. Establish multiple sets of damper opening adjustment value judgment conditions. Set the setting range for the absolute value of the standard negative pressure deviation and the setting value for the furnace negative pressure; When the absolute value of the negative pressure deviation is set within the same range, the damper opening adjustment value is positively correlated with the current damper opening value; S200: Obtain the current furnace negative pressure through the negative pressure sensor; S300: Calculate the absolute value of the negative pressure deviation between the current furnace negative pressure and the furnace negative pressure set value obtained in step S200; S400: Determine the absolute value of the negative pressure deviation in step S300. If the absolute value of the negative pressure deviation is within the set range of the standard negative pressure deviation absolute value, return to execute steps S200, S300 and S400. If the absolute value of the negative pressure deviation is not within the set range of the standard negative pressure deviation absolute value, obtain the current damper opening value. S500: Based on the current damper opening value obtained in S400 and the absolute value of negative pressure deviation obtained in S300, match the judgment condition for damper opening adjustment value established in S100 to obtain the damper opening adjustment value; and obtain the negative pressure deviation value. S600: The damper opening is adjusted using the damper opening adjustment value and negative pressure deviation value obtained in S500; when the negative pressure deviation value is positive, the damper opening is increased; when it is negative, the damper opening is decreased. S700: After adjustment, the delay phase begins. During the delay phase, the damper does not move. After the delay ends, the cycle returns to step S200.

2. The automatic adjustment and control method for negative pressure in a boiler furnace according to claim 1, characterized in that, In step S100, a furnace pressure limit value is preset. Between steps S200 and S300, the following steps are also included: determining whether the current furnace negative pressure in S200 has reached or exceeded the preset furnace pressure limit value. If it has reached or exceeded the preset furnace pressure limit value, the automatic control will be switched to manual control and an alarm will be issued.

3. The automatic adjustment and control method for negative pressure in a boiler furnace according to any one of claims 1-2, characterized in that, In step S100, a preset damper opening deviation value is set, and during the delay phase of step S700, the following steps are also included: The system obtains the actual opening degree of the damper on site and calculates the deviation between the theoretical opening degree of the damper after adjustment and the actual opening degree of the damper on site. When the deviation exceeds the preset damper opening degree deviation value, the system exits automatic control and issues an alarm.

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