A method for controlling the feeding of limestone slurry in a desulfurization island

Abstract

This invention discloses a method for controlling the feeding of limestone slurry to a desulfurization island, comprising the following steps: S1: setting a preset value for SO2 outlet concentration, an upper limit setting value for SO2 outlet concentration, and a lower limit setting value for SO2 outlet concentration; S2: collecting the SO2 outlet concentration value at the desulfurization island outlet in real time; S3: comparing the SO2 outlet concentration value obtained in S2 with the preset value for SO2 outlet concentration set in S1, and adjusting the opening and closing of the pneumatic regulating valve and the frequency of the feeder's inverter in real time; S4: ensuring that the hourly average value of the SO2 outlet concentration value collected in S2 is below the upper limit setting value for SO2 outlet concentration set in S1. After the SO2 outlet concentration value and the preset value for SO2 outlet concentration reach the corresponding difference, the opening of the pneumatic regulating valve and the start and stop of the feeder are adjusted according to the actual difference to stabilize the hourly average value of the desulfurization island outlet concentration value within ±5 of the set value, thereby achieving automatic control of SO2 outlet concentration, reducing the risk of exceeding environmental protection parameters, and reducing the occurrence of over-desulfurization.

Description

Technical fields:

[0001] This invention relates to the field of flue gas treatment, and more specifically to a method for controlling the feeding of limestone slurry to a desulfurization island. Background technology:

[0002] A desulfurization island, also known as a flue gas desulfurization process system, is generally divided into the following subsystems: flue gas system, limestone slurry preparation system, absorption tower system, process water and wastewater discharge system, and compressed air system. In flue gas treatment, the limestone slurry preparation system generates limestone slurry by uniformly mixing and stirring water and limestone powder. This slurry is then transported to the absorption tower through corresponding pipelines, providing the absorbent. Sulfur-containing flue gas from the flue gas system enters the absorption tower through flue gas pipelines, where acidic components such as SO2, SO3, HCl, and HF are removed, yielding the corresponding desulfurization products. Simultaneously, relatively clean flue gas is emitted into the atmosphere.

[0003] Currently, limestone slurry feeding is automated using a pneumatic regulating valve and a feeder, based on multiple parameters such as the SO2 outlet concentration, SO2 inlet concentration, and hourly average SO2 concentration of the desulfurization island. However, in actual production, the SO2 inlet concentration of the desulfurization island fluctuates in real time according to production conditions. To ensure that the SO2 outlet concentration of the desulfurization island meets environmental protection requirements, operators need to continuously adjust the opening of the pneumatic regulating valve and the frequency of the feeder to control the limestone slurry feeding amount. When the SO2 inlet concentration of the desulfurization island is stable, operators need to operate 30 to 40 times per hour; when the SO2 at the flue gas inlet is unstable, they need to operate 50 to 60 times per hour. Frequent operation can easily lead to operational errors, which not only causes SO2 emissions to fail to meet environmental protection requirements but also wastes limestone slurry, reducing the economic benefits of desulfurization and increasing production costs. Summary of the Invention:

[0004] The purpose of this invention is to provide a method for controlling the feeding of limestone slurry in a desulfurization island.

[0005] This invention is implemented by the following technical solution:

[0006] A method for controlling the feeding of limestone slurry in a desulfurization island includes the following steps:

[0007] S1: Set the preset value of SO2 outlet concentration, the upper limit setting value of SO2 outlet concentration, and the lower limit setting value of SO2 outlet concentration;

[0008] S2: Real-time collection of SO2 outlet concentration at the desulfurization island outlet;

[0009] S3: Compare the SO2 outlet concentration value obtained from S2 with the preset SO2 outlet concentration value set in S1, and adjust the opening and closing of the pneumatic regulating valve and the frequency of the feeder's inverter in real time, thereby adjusting the limestone slurry feeding amount.

[0010] S4: Ensures that the hourly average value of the SO2 outlet concentration collected by S2 is below the upper limit setting of the SO2 outlet concentration set by S1.

[0011] Preferably, during the comparison process in S3, if the SO2 outlet concentration value collected in S2 is less than the lower limit setting value of SO2 outlet concentration set in S1, the pneumatic regulating valve is closed, the feeder is stopped, and the feeding of limestone slurry into the desulfurization island is stopped.

[0012] If the SO2 outlet concentration value collected by S2 is between the upper limit setting value and the lower limit setting value of SO2 outlet concentration set by S1, adjust the opening of the pneumatic regulating valve, stop the feeder, and inject limestone slurry into the desulfurization island through the pneumatic regulating valve.

[0013] If the SO2 outlet concentration value collected by S2 is higher than the upper limit setting value of SO2 outlet concentration set by S1, adjust the pneumatic regulating valve to be fully open and the frequency of the feeder's inverter to be adjusted, and then feed limestone slurry into the desulfurization island together through the pneumatic regulating valve and the feeder.

[0014] Preferably, when the SO2 outlet concentration value collected by S2 is between the upper limit setting value and the lower limit setting value of SO2 outlet concentration set by S1, if the difference between the SO2 outlet concentration value collected by S2 and the preset value of SO2 outlet concentration set by S2 is 0 and < 5 mg / m³ 3 Adjust the opening of the pneumatic regulating valve to 35%;

[0015] If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S2 is ≥5 mg / m³ 3 and <10mg / m 3 Adjust the opening of the pneumatic regulating valve to 50%;

[0016] If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S2 is ≥10 mg / m³ 3 and <15mg / m 3 Adjust the opening of the pneumatic regulating valve to 70%;

[0017] If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S2 is ≥15mg / m³ 3 and <20mg / m 3 Adjust the opening of the pneumatic regulating valve to 90%;

[0018] If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S2 is ≥20 mg / m³ 3 Adjust the pneumatic regulating valve to full open.

[0019] Preferably, when the SO2 outlet concentration value collected by S2 is greater than the upper limit setting value of SO2 outlet concentration set by S1, if the difference between the SO2 outlet concentration value collected by S2 and the preset value of SO2 outlet concentration set by S1 is >25 mg / m³ 3 and ≤35mg / m 3 Adjust the frequency of the feeder's inverter to 30% of the maximum rated power frequency;

[0020] If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S1 is >35 mg / m³ 3 and ≤45mg / m 3 Adjust the frequency of the feeder's inverter to 70% of the maximum rated power frequency;

[0021] If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S1 is > 45 mg / m³ 3 Adjust the frequency of the feeder's inverter to the maximum rated power frequency.

[0022] Preferably, it also includes collecting the SO2 inlet concentration and flue gas flow rate at the inlet of the desulfurization island at S2.

[0023] Preferably, the initial coefficient is set based on the SO2 inlet concentration at the desulfurization island inlet, the flue gas flow rate at the desulfurization island inlet, and the set initial coefficient to obtain an initial set value, and the opening of the pneumatic regulating valve is adjusted according to the initial set value.

[0024] Initial setting value = SO2 inlet concentration value · flue gas flow rate at the inlet of the desulfurization island · initial coefficient.

[0025] Preferably, the SO2 inlet concentration change rate is set such that the SO2 outlet concentration at the desulfurization island outlet is less than 50 mg / m³. 3 If the rate of change of SO2 inlet concentration at the desulfurization island inlet is greater than the set value of SO2 inlet concentration change rate, the frequency of the feeder's frequency converter will be adjusted to 30% of the maximum rated power frequency within 3 seconds, and the start-up time will be preset. After the preset time, the feeder will be shut down.

[0026] The advantages of this invention are as follows: After the SO2 outlet concentration value reaches the corresponding difference from the preset SO2 outlet concentration value, the opening of the pneumatic regulating gate and the start and stop of the feeder are adjusted according to the actual difference, so that the hourly average value of the desulfurization island outlet concentration value is stabilized within ±5 of the set value, thereby realizing automatic control of SO2 outlet concentration, reducing the risk of exceeding environmental protection parameters, reducing the occurrence of over-desulfurization, avoiding the waste of limestone slurry, and improving the desulfurization effect of the desulfurization island. Attached image description:

[0027] Figure 1 This is the control principle diagram of the present invention. Detailed implementation method:

[0028] like Figure 1 As shown, a method for controlling the feeding of limestone slurry in a desulfurization island includes the following steps:

[0029] S1: Set the preset value of SO2 outlet concentration, the upper limit setting value of SO2 outlet concentration, and the lower limit setting value of SO2 outlet concentration;

[0030] S2: Real-time collection of SO2 outlet concentration at the desulfurization island outlet, SO2 inlet concentration at the desulfurization island inlet, and flue gas flow rate at the desulfurization island inlet;

[0031] S3: Compare the SO2 outlet concentration value obtained in S2 with the preset SO2 outlet concentration value set in S1, and adjust the opening and closing of the pneumatic regulating valve and the frequency of the feeder's frequency converter in real time, thereby adjusting the limestone slurry feeding amount. The specific adjustment process is as follows:

[0032] The initial coefficient is set based on the SO2 inlet concentration at the desulfurization island inlet, the flue gas flow rate at the desulfurization island inlet, and the initial coefficient. The initial setting value is then used to adjust the opening of the pneumatic regulating valve.

[0033] Initial setpoint = SO2 inlet concentration value · flue gas flow rate at the desulfurization island inlet · initial coefficient;

[0034] The initial pneumatic regulating valve opening is set using the initial set value to ensure sufficient limestone slurry for desulfurization in the early stages of flue gas treatment;

[0035] If the SO2 outlet concentration value collected by S2 is less than the lower limit setting value of SO2 outlet concentration set by S1, adjust the pneumatic regulating valve to close, stop the feeder, and stop feeding limestone slurry into the desulfurization island.

[0036] If the SO2 outlet concentration value collected by S2 is between the upper limit setting value and the lower limit setting value of SO2 outlet concentration set by S1, adjust the opening of the pneumatic regulating valve, stop the feeder, and inject limestone slurry into the desulfurization island through the pneumatic regulating valve.

[0037] When the SO2 outlet concentration value collected by S2 is between the upper limit setting value and the lower limit setting value of SO2 outlet concentration set by S1, if the difference between the SO2 outlet concentration value collected by S2 and the preset value of SO2 outlet concentration set by S2 is 0 and < 5 mg / m³ 3 Adjust the opening of the pneumatic regulating valve to 35%;

[0038] If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S2 is ≥5 mg / m³ 3 and <10mg / m 3 Adjust the opening of the pneumatic regulating valve to 50%;

[0039] If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S2 is ≥10 mg / m³ 3 and <15mg / m 3 Adjust the opening of the pneumatic regulating valve to 70%;

[0040] If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S2 is ≥15mg / m³ 3 and <20mg / m 3 Adjust the opening of the pneumatic regulating valve to 90%;

[0041] If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S2 is ≥20 mg / m³ 3 Adjust the pneumatic regulating valve to full open;

[0042] If the SO2 outlet concentration value collected by S2 is higher than the upper limit setting value of SO2 outlet concentration set by S1, adjust the pneumatic regulating valve to be fully open and the frequency of the feeder's inverter to be adjusted, and then feed limestone slurry into the desulfurization island together through the pneumatic regulating valve and the feeder.

[0043] When the SO2 outlet concentration value collected by S2 is greater than the upper limit of the SO2 outlet concentration set by S1, if the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S1 is >25 mg / m³ 3 and ≤35mg / m 3 Adjust the frequency of the feeder's inverter to 30% of the maximum rated power frequency;

[0044] If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S1 is >35 mg / m³ 3 and ≤45mg / m 3 Adjust the frequency of the feeder's inverter to 70% of the maximum rated power frequency;

[0045] If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S1 is > 45 mg / m³ 3 Adjust the frequency of the feeder's inverter to the maximum rated power frequency;

[0046] Set the SO2 inlet concentration change rate setpoint so that, under special operating conditions, the SO2 outlet concentration at the desulfurization island outlet is less than 50 mg / m³. 3 If the rate of change of SO2 inlet concentration at the desulfurization island inlet is greater than the set value of SO2 inlet concentration change rate, the frequency of the feeder's frequency converter will be adjusted to 30% of the maximum rated power frequency for 3 seconds, and the start time will be preset. After the preset time, the feeder will be turned off.

[0047] S4: Ensures that the hourly average value of the SO2 outlet concentration collected by S2 is below the upper limit setting of the SO2 outlet concentration set by S1.

[0048] Example

[0049] The following is a detailed explanation using actual production conditions as an example:

[0050] S1: Set the preset SO2 outlet concentration to 25 mg / m³ 3 The upper limit for SO2 outlet concentration is set at 40 mg / m³. 3 The lower limit for SO2 outlet concentration is set at 24 mg / m³. 3 ;

[0051] S2: Collect SO2 outlet concentration at the desulfurization island outlet, SO2 inlet concentration at the desulfurization island inlet, and flue gas flow rate at the desulfurization island inlet;

[0052] S3: In the initial stage of flue gas treatment, set the initial coefficient to 1.80. Combine the SO2 inlet concentration value and the flue gas flow rate value at the desulfurization island inlet to obtain the initial set value. The initial coefficient is obtained based on the test results of the sulfur content of coal. The initial set value = SO2 inlet concentration value · flue gas flow rate at the desulfurization island inlet · initial coefficient. Add the initial set value to the preset SO2 outlet concentration value set in S1. Compare the resulting value with the preset SO2 outlet concentration value set in S1 and adjust the initial opening of the pneumatic regulating valve.

[0053] If the SO2 outlet concentration value collected by S2 is less than 24 mg / m³ 3 Adjust the pneumatic regulating valve to close and stop the feeder to stop feeding limestone slurry into the desulfurization island;

[0054] If the SO2 outlet concentration value collected by S2 is between 25-30 mg / m³ 3 Between these points, adjust the opening of the pneumatic regulating valve to 35%;

[0055] If the SO2 outlet concentration value collected by S2 is between 30-35 mg / m³ 3 Between these points, adjust the opening of the pneumatic regulating valve to 50%;

[0056] If the SO2 outlet concentration value collected by S2 is between 35-40 mg / m³ 3 Between these points, adjust the opening of the pneumatic regulating valve to 70%;

[0057] If the SO2 outlet concentration value collected by S2 is between 40-45 mg / m³ 3 Between these points, adjust the opening of the pneumatic regulating valve to 90%;

[0058] If the SO2 outlet concentration value collected by S2 is greater than or equal to 45 mg / m³ 3 Adjust the pneumatic regulating valve to full open;

[0059] If the SO2 outlet concentration value collected by S2 is between 50-60 mg / m³ 3 Between these times, adjust the frequency of the feeder's inverter to 30% of the maximum rated power frequency;

[0060] If the SO2 outlet concentration value collected by S2 is between 60-70 mg / m³ 3 Between these times, adjust the frequency of the feeder's inverter to 70% of its maximum rated power frequency;

[0061] If the SO2 outlet concentration value collected by S2 is greater than 70 mg / m³ 3 Adjust the frequency of the feeder's inverter to the maximum rated power frequency;

[0062] Set a set value for the SO2 inlet concentration change rate. Under special operating conditions, such as coal feeder interruption or blockage, the SO2 outlet concentration at the desulfurization island outlet should be less than 50 mg / m³. 3 If the rate of change of SO2 inlet concentration at the desulfurization island inlet is greater than the set value of SO2 inlet concentration change rate by 3s, adjust the frequency of the feeder's frequency converter to 30% of the maximum rated power frequency, and preset the start time. After the preset time, shut down the feeder.

[0063] If the SO2 outlet concentration is greater than 15 mg / m³ 3 Furthermore, the feeder downtime is equal to the feeder interval time setting value. The frequency of the feeder's frequency converter is adjusted to 25% of the maximum rated power frequency, and the start-up time is preset to ensure that enough limestone slurry is sent to the desulfurization island and to avoid the overflow of sulfur-containing gas caused by insufficient limestone slurry.

[0064] S4: Ensures that the hourly average value of the SO2 outlet concentration collected by S2 is below the upper limit of the SO2 outlet concentration set by S1, so that the flue gas meets the environmental emission standards. It also enables the addition of corresponding limestone slurry based on the actual sulfur content of the flue gas, avoiding waste of limestone slurry and improving the desulfurization effect of the desulfurization island.

[0065] 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. A method for controlling the feeding of limestone slurry in a desulfurization island, characterized in that, Includes the following steps: S1: Set the preset value of SO2 outlet concentration, the upper limit setting value of SO2 outlet concentration, and the lower limit setting value of SO2 outlet concentration; S2: Real-time collection of SO2 outlet concentration at the desulfurization island outlet; S3: Compare the SO2 outlet concentration value obtained from S2 with the preset SO2 outlet concentration value set in S1, and adjust the opening and closing of the pneumatic regulating valve and the frequency of the feeder's inverter in real time, thereby adjusting the limestone slurry feeding amount. During the comparison process in S3, if the SO2 outlet concentration value collected by S2 is less than the lower limit setting value of SO2 outlet concentration set in S1, adjust the pneumatic regulating valve to close, stop the feeder, and stop feeding limestone slurry into the desulfurization island. If the SO2 outlet concentration value collected by S2 is between the upper limit setting value and the lower limit setting value of SO2 outlet concentration set by S1, adjust the opening of the pneumatic regulating valve, stop the feeder, and inject limestone slurry into the desulfurization island through the pneumatic regulating valve. If the SO2 outlet concentration value collected by S2 is higher than the upper limit setting value of SO2 outlet concentration set by S1, adjust the pneumatic regulating valve to be fully open and the frequency of the feeder's inverter to be adjusted, and then feed limestone slurry into the desulfurization island together through the pneumatic regulating valve and the feeder. When the SO2 outlet concentration value collected by S2 is between the upper limit setting value and the lower limit setting value of SO2 outlet concentration set by S1, if the difference between the SO2 outlet concentration value collected by S2 and the preset value of SO2 outlet concentration set by S2 is ≥0 and <5mg / m³, 3 Adjust the opening of the pneumatic regulating valve to 35%; If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S2 is ≥5 mg / m³ 3 and <10mg / m 3 Adjust the opening of the pneumatic regulating valve to 50%; If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S2 is ≥10 mg / m³ 3 and <15mg / m 3 Adjust the opening of the pneumatic regulating valve to 70%; If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S2 is ≥15 mg / m³ 3 and <20mg / m 3 Adjust the opening of the pneumatic regulating valve to 90%; If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S2 is ≥20 mg / m³ 3 Adjust the pneumatic regulating valve to full open; If the SO2 outlet concentration value collected by S2 is greater than the upper limit of the SO2 outlet concentration set by S1, and the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S1 is greater than 25 mg / m³, then... 3 and ≤35mg / m 3 Adjust the frequency of the feeder's inverter to 30% of its maximum rated power frequency; If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S1 is > 35 mg / m³ 3 and ≤45mg / m 3 Adjust the frequency of the feeder's inverter to 70% of its maximum rated power frequency; If the difference between the SO2 outlet concentration value collected by S2 and the preset SO2 outlet concentration value set by S1 is > 45 mg / m³ 3 Adjust the frequency of the feeder's inverter to the maximum rated power frequency; S4: Ensures that the hourly average value of the SO2 outlet concentration collected by S2 is below the upper limit setting of the SO2 outlet concentration set by S1.

2. The method for controlling the feeding of limestone slurry in a desulfurization island according to claim 1, characterized in that, It also includes collecting the SO2 inlet concentration and flue gas flow rate at the inlet of the desulfurization island at S2.

3. The method for controlling the feeding of limestone slurry in a desulfurization island according to claim 2, characterized in that, The initial coefficient is set based on the SO2 inlet concentration at the desulfurization island inlet, the flue gas flow rate at the desulfurization island inlet, and the initial coefficient. The initial setting value is then used to adjust the opening of the pneumatic regulating valve. Initial setting value = SO2 inlet concentration value · flue gas flow rate at the inlet of the desulfurization island · initial coefficient.

4. The method for controlling the feeding of limestone slurry in a desulfurization island according to claim 3, characterized in that, Set the SO2 inlet concentration change rate setpoint so that the SO2 outlet concentration at the desulfurization island is less than 50 mg / m³. 3 If the rate of change of SO2 inlet concentration at the desulfurization island inlet is greater than the set value of SO2 inlet concentration change rate by 3 seconds, adjust the frequency of the feeder's frequency converter to 30% of the maximum rated power frequency, and preset the start time. After the preset time, shut down the feeder.

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