Desulfurizing agent feeding system and control method

Abstract

The invention relates to a desulfurizing agent feeding system and a control method, and belongs to the technical field of desulfurization. The control method comprises the following steps: step 1, collecting an SO2 outlet concentration value at an outlet of the desulfurization system in real time through the flue gas online monitoring device; 2, setting an expected SO2 outlet concentration value at an outlet of the desulfurization system; 3, calculating the concentration difference delta N between the SO2 outlet concentration expected value at the outlet of the desulfurization system and the collected SO2 outlet concentration value at the desulfurization outlet; 4, starting conditions and delay time of the first variable-frequency feeder and the second variable-frequency feeder are set; and 5, before the feeding system is started, the first feeding manual valve and the second feeding manual valve are opened. The screw feeder is started; and through the change of the concentration difference delta N, the first variable-frequency feeder and the second variable-frequency feeder automatically adjust the feeding frequency and the start-stop state. According to the invention, faults and accidents caused by frequent manual operation are avoided, the consumption of the desulfurizer is reduced, and the desulfurization effect is improved.

Description

Technical Field

[0001] The invention relates to a desulfurizing agent feeding system and a control method, belonging to the technical field of desulfurization. Background Art

[0002] CFB-FGD desulfurization system is generally composed of the following subsystems: flue gas system, absorption tower system, bag filter system, process water system, absorbent preparation and supply system, material circulation system, desulfurization product treatment system, etc. Flue gas enters the circulating fluidized bed reactor from the bottom of the circulating fluidized bed, and dry Ca(OH)2 is input into the reaction tower through the desulfurizer supply system. Fluidized materials and acidic gases such as sulfur dioxide in the flue gas react chemically in the reaction tower to remove most of the pollutants such as sulfur dioxide in the flue gas. Then the flue gas is discharged from the top of the reaction tower and passes through the bag filter to remove fine ash. Most of the fine ash removed by the dust collector and the incompletely reacted desulfurizer are sent to the desulfurization tower for recycling through the pneumatic conveyor. Part of the fine ash is regularly discharged to the desulfurization ash storage by the ash discharge system at the bottom of the dust collector. The treated flue gas is discharged into the chimney through the induced draft fan.

[0003] At present, the desulfurization agent is fed automatically by a feeder based on multiple parameters such as the desulfurization SO2 outlet concentration, the desulfurization island SO2 inlet concentration and the hourly average value of SO2. However, in actual production, the desulfurization island SO2 inlet concentration changes at any time with the production situation. To ensure that the desulfurization SO2 outlet concentration meets environmental protection requirements, the operator needs to constantly adjust the frequency conversion frequency of the feeder to control the desulfurization agent feeding amount to control the SO2 outlet concentration. When the desulfurization SO2 inlet concentration is stable, the operator needs to operate 50 to 60 times an hour. When the flue gas inlet SO2 is unstable, the operator needs to operate hundreds of times an hour. The operator is prone to operating errors under frequent operation, which will not only cause SO2 emissions to fail to meet environmental protection requirements, but also cause waste of desulfurizers, resulting in reduced economic benefits of desulfurization and increased production costs. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a desulfurizer feeding system and control method for the above-mentioned prior art, so as to realize real-time feeding of desulfurizer, avoid mistakes and accidents caused by frequent manual operation, reduce the consumption of desulfurizer, and improve the desulfurization effect.

[0005] The technical solution adopted by the present invention to solve the above-mentioned problem is: a desulfurizer feeding system, including a desulfurizer storage bin, a screw conveyor is provided under the desulfurizer storage bin, the bottom of the desulfurizer storage bin is connected to a first feeding pipe and a second feeding pipe, the outlets of the first feeding pipe and the second feeding pipe are facing the screw conveyor, the first feeding pipe is provided with a first feeding control unit, the second feeding pipe is provided with a second feeding control unit, the outlet of the screw conveyor is connected to a reaction tower, and a flue gas online monitoring device is provided at the outlet of the desulfurization system, and the flue gas online monitoring device is used to detect the SO2 outlet concentration value at the outlet of the desulfurization system.

[0006] The first feeding control unit includes a first feeding manual valve and a first variable frequency feeder, and the first variable frequency feeder is arranged at the outlet side of the first feeding manual valve.

[0007] The second feeding control unit includes a second feeding manual valve and a second variable frequency feeder, and the second variable frequency feeder is arranged at the outlet side of the second feeding manual valve.

[0008] A control method for a desulfurizing agent feeding system, the control method comprising the following steps: Step 1: Collect the SO2 outlet concentration value at the outlet of the desulfurization system in real time through the flue gas online monitoring device; Step 2: Set the expected value of SO2 outlet concentration at the outlet of the desulfurization system; Step 3: Calculate the concentration difference between the expected value of SO2 outlet concentration at the outlet of the desulfurization system and the collected SO2 outlet concentration value at the outlet of the desulfurization system as ΔN; Step 4: Set the start conditions and delay time of the first variable frequency feeder and the second variable frequency feeder; Step 5: Before starting the feeding system, open the first feeding manual valve and the second feeding manual valve. The screw feeder starts; through the change of concentration difference ΔN, the first variable frequency feeder and the second variable frequency feeder automatically adjust the feeding frequency and start and stop status to ensure that the hourly average value of the SO2 outlet concentration value is below the SO2 outlet concentration limit value required by environmental protection.

[0009] The expected SO2 outlet concentration is 5-35 mg / m 3 .

[0010] When ΔN<20mg / m 3 When the preset time is reached, the first variable frequency feeder is started, and the speed of the first variable frequency feeder automatically runs as follows: When 15mg / m 3 <ΔN≤20mg / m 3 When the frequency of the first variable frequency feeder is 30% of the normal working frequency; When 10mg / m 3<ΔN≤15mg / m 3 When the frequency of the first variable frequency feeder is 50% of the normal working frequency; When 5mg / m 3 <ΔN≤10mg / m 3 When the frequency of the first variable frequency feeder is 70% of the normal working frequency; When ΔN≤5mg / m 3 When , the frequency of the first variable frequency feeder is 100% of the normal working frequency; When ΔN>20mg / m 3 When the frequency of the first variable frequency feeder is 20% of the normal working frequency; When ΔN>25mg / m 3 When the preset time is reached, the first variable frequency feeder stops working.

[0011] The preset time of the first variable frequency feeder is 0~180s.

[0012] When the concentration difference ΔN is less than 10 mg / m 3 When the preset time is reached, the second variable frequency feeder is started and the speed of the second variable frequency feeder automatically runs as follows: When 5mg / m 3 <ΔN≤10mg / m 3 When the frequency of the second variable frequency feeder is 30% of the normal working frequency; When 0mg / m 3 <ΔN≤5mg / m 3 When the frequency of the second variable frequency feeder is 50% of the normal working frequency; When -5mg / m 3 <ΔN≤0mg / m 3 When the frequency of the second variable frequency feeder is 70% of the normal working frequency; When ΔN≤-5mg / m 3 When the frequency of the second variable frequency feeder is 100% of the normal working frequency; When the concentration difference ΔN>10mg / m 3 At 3:00, the frequency of the second variable frequency feeder is 20% of the normal working frequency; When ΔN>15mg / m 3 When the preset time is reached, the second variable frequency feeder stops working.

[0013] The preset time of the second variable frequency feeder is 0~180s.

[0014] The delay time of the first variable frequency feeder and the second variable frequency feeder are respectively 0-180s.

[0015] Compared with the prior art, the advantages of the present invention are: a desulfurizer feeding system and control method, which uses two variable frequency feeders to simultaneously control the real-time feeding of the desulfurizer, overcomes the phenomenon that a single feeder has a slow response time or the feeder is too large, causing a large amount of desulfurizer waste, etc., and through the coordinated control of the two feeders, when the SO2 outlet concentration of the flue gas fluctuation desulfurization system rises rapidly, the SO2 outlet concentration value of the desulfurization system can be quickly reduced, and the consumption of the desulfurizer can be effectively reduced, thereby reducing production costs. The present application ensures that the hourly average value of the SO2 outlet concentration value of the desulfurization system is below the SO2 outlet concentration limit required by environmental protection requirements in real time, so that the flue gas meets the environmental protection emission standards, avoids frequent manual operations and waste of desulfurizers, and improves the desulfurization effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of a desulfurizing agent feeding system according to an embodiment of the present invention; Figure 2 The following is a flow chart and control principle diagram of a control method of a desulfurizing agent feeding system according to an embodiment of the present invention; In the figure, 1 is a desulfurizer storage bin, 2 is a first feeding pipe, 3 is a first feeding manual valve, 4 is a first variable frequency feeder, 5 is a screw conveyor, 6 is a second feeding pipe, 7 is a second feeding manual valve, 8 is a second variable frequency feeder, and 9 is a reaction tower. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below with reference to the accompanying drawings.

[0018] like Figure 1 As shown, a desulfurizer feeding system in this embodiment includes a desulfurizer storage bin 1, a screw conveyor 5 is provided below the desulfurizer storage bin 1, a first feeding pipe 2 and a second feeding pipe 6 are connected to the bottom of the desulfurizer storage bin 1, the outlets of the first feeding pipe 2 and the second feeding pipe 6 face the screw conveyor 5, and the first feeding pipe 2 is provided with a first feeding manual valve 3 and a first variable frequency feeder 4, and the first variable frequency feeder 4 is arranged on the outlet side of the first feeding manual valve 3. The second feeding pipe 6 is provided with a second feeding manual valve 7 and a second variable frequency feeder 8, and the second variable frequency feeder 8 is arranged on the outlet side of the second feeding manual valve 7. The outlet of the screw conveyor 5 is connected to a reaction tower 9, and a flue gas online monitoring device is provided at the outlet of the desulfurization system, and the flue gas online monitoring device is used to detect the outlet concentration value of SO2 at the outlet of the desulfurization system. Open the first manual feeding valve 3, start the first variable frequency feeder 8 and the screw conveyor 5, so that the desulfurizer in the desulfurizer storage bin 1 flows to the screw conveyor 5 through the first feeding pipe 2, and then is transported to the reaction tower 9; or open the second manual feeding valve 7, start the second variable frequency feeder 8, so that the desulfurizer in the desulfurizer storage bin 1 flows to the screw conveyor 5 through the second feeding pipe 6, and then is transported to the reaction tower 9.

[0019] like Figure 2 As shown, a control method for a desulfurizing agent feeding system comprises the following steps: Step 1: Collect the SO2 outlet concentration value at the outlet of the desulfurization system in real time through the flue gas online monitoring device.

[0020] Step 2: Set the expected SO2 outlet concentration at the outlet of the desulfurization system; set it according to environmental protection requirements, and the current emission standard is not higher than 35mg / m 3 The actual operating SO2 outlet concentration is expected to be 5~35mg / m 3 .

[0021] Step 3: Calculate the concentration difference ΔN between the expected SO2 outlet concentration at the outlet of the desulfurization system and the collected SO2 outlet concentration at the outlet of the desulfurization system through the PLC controller.

[0022] Step 4: Set the start-up conditions and delay time of the first variable frequency feeder and the second variable frequency feeder; the delay time range of the first variable frequency feeder and the second variable frequency feeder can be set according to the time operation situation, generally set within the range of 0~180s.

[0023] When ΔN<20mg / m 3 When the preset time is reached, the first variable frequency feeder is started and the speed of the first variable frequency feeder automatically runs as follows: a. 15 mg / m 3 <ΔN≤20mg / m 3 When the frequency of the first variable frequency feeder is 30% of the normal working frequency; b. 10 mg / m 3 <ΔN≤15mg / m 3 When the frequency of the first variable frequency feeder is 50% of the normal working frequency; c. 5mg / m 3 <ΔN≤10mg / m 3 When the frequency of the first variable frequency feeder is 70% of the normal working frequency; d. ΔN≤5mg / m 3 When , the frequency of the first variable frequency feeder is 100% of the normal working frequency; e. ΔN>20mg / m 3 When the frequency of the first variable frequency feeder is 20% of the normal working frequency; f. ΔN>25mg / m 3 When the preset time is reached, the first variable frequency feeder stops working.

[0024] When ΔN<10mg / m 3When the preset time is reached, the second variable frequency feeder is started and the speed of the second variable frequency feeder automatically runs as follows: a. 5mg / m 3 <ΔN≤10mg / m 3 When the frequency of the second variable frequency feeder is 30% of the normal working frequency; b. 0mg / m 3 <ΔN≤5mg / m 3 When the frequency of the second variable frequency feeder is 50% of the normal working frequency; c. -5mg / m 3 <ΔN≤0mg / m 3 When the SO2 outlet concentration is lower than the expected SO2 outlet concentration, the low flow rate feeder is maintained for a period of time to make the system run more stable and prevent large fluctuations in the data. d. ΔN≤-5mg / m 3 When the frequency of the second variable frequency feeder is 100% of the normal working frequency, it means that the emission value is exceeded and the feeding amount needs to be increased; e. ΔN>10mg / m 3 When the frequency of the second variable frequency feeder is 20% of the normal working frequency; f、ΔN>15mg / m 3 When the preset time is reached, the second variable frequency feeder stops working.

[0025] Step 5: Before starting the feeding system, open the first feeding manual valve and the second feeding manual valve, start the screw feeder, and automatically adjust the feeding frequency and start and stop status of the first variable frequency feeder and the second variable frequency feeder through the change of the concentration difference ΔN to ensure that the hourly average value of the SO2 outlet concentration is below the SO2 outlet concentration limit required by environmental protection.

[0026] The preset time of the first variable frequency feeder and the second variable frequency feeder is 0~180s.

[0027] The normal operating frequency of the frequency converters of the first variable frequency feeder and the second variable frequency feeder is 50 Hz.

[0028] The operating conditions of the two feeders are relatively independent, in order to overcome the problem of a single feeder feeding too much or too little.

[0029] The present application uses two variable frequency feeders to simultaneously control the real-time feeding of the desulfurizer, overcoming the phenomenon that a single feeder has a slow response time or the feeder is too large, resulting in a large amount of waste of desulfurizer. Through the coordinated control of the two feeders, when the SO2 outlet concentration of the flue gas fluctuation desulfurization system rises rapidly, the SO2 outlet concentration value of the desulfurization system can be quickly reduced, and the consumption of the desulfurizer can be effectively reduced, thereby reducing production costs. The present application ensures that the hourly average value of the SO2 outlet concentration value of the desulfurization system is in real time below the SO2 outlet concentration limit required by environmental protection, so that the flue gas meets the environmental protection emission standards, avoids frequent manual operations and waste of desulfurizers, and improves the desulfurization effect.

[0030] In addition to the above embodiments, the present invention also includes other implementation modes. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the protection scope of the claims of the present invention.

Claims

1. A desulfurizing agent feeding system, characterized in that: It includes a desulfurizer storage bin, a screw conveyor is provided below the desulfurizer storage bin, a first feeding pipe and a second feeding pipe are connected to the bottom of the desulfurizer storage bin, the outlets of the first feeding pipe and the second feeding pipe face the screw conveyor, a first feeding control unit is provided on the first feeding pipe, a second feeding control unit is provided on the second feeding pipe, the outlet of the screw conveyor is connected to a reaction tower, and a flue gas online monitoring device is provided at the outlet of the desulfurization system, and the flue gas online monitoring device is used to detect the outlet concentration value of SO2 at the outlet of the desulfurization system.

2. A desulfurizing agent feeding system according to claim 1, characterized in that: The first feeding control unit includes a first feeding manual valve and a first variable frequency feeder, and the first variable frequency feeder is arranged at the outlet side of the first feeding manual valve.

3. A desulfurizing agent feeding system according to claim 1, characterized in that: The second feeding control unit includes a second feeding manual valve and a second variable frequency feeder, and the second variable frequency feeder is arranged at the outlet side of the second feeding manual valve.

4. A control method for a desulfurizing agent feeding system according to any one of claims 1 to 3, characterized in that: The control method comprises the following steps: Step 1: Collect the SO2 outlet concentration value at the outlet of the desulfurization system in real time through the flue gas online monitoring device; Step 2: Set the expected value of SO2 outlet concentration at the outlet of the desulfurization system; Step 3: Calculate the concentration difference between the expected value of SO2 outlet concentration at the outlet of the desulfurization system and the collected SO2 outlet concentration value at the outlet of the desulfurization system as ΔN; Step 4: Set the start conditions and delay time of the first variable frequency feeder and the second variable frequency feeder; Step 5: Before starting the feeding system, open the first feeding manual valve and the second feeding manual valve. The screw feeder starts; through the change of concentration difference ΔN, the first variable frequency feeder and the second variable frequency feeder automatically adjust the feeding frequency and start and stop status to ensure that the hourly average value of the SO2 outlet concentration value is below the SO2 outlet concentration limit value required by environmental protection.

5. The control method of a desulfurizing agent feeding system according to claim 4, characterized in that: The expected SO2 outlet concentration is 5-35 mg / m 3 .

6. The control method of a desulfurizing agent feeding system according to claim 4, characterized in that: When ΔN<20mg / m 3 When the preset time is reached, the first variable frequency feeder is started, and the speed of the first variable frequency feeder automatically runs as follows: a. When 15mg / m 3 <ΔN≤20mg / m 3 When the frequency of the first variable frequency feeder is 30% of the normal working frequency; b. When 10mg / m 3 <ΔN≤15mg / m 3 When the frequency of the first variable frequency feeder is 50% of the normal working frequency; c. When 5mg / m 3 <ΔN≤10mg / m 3 When the frequency of the first variable frequency feeder is 70% of the normal working frequency; d. When ΔN≤5mg / m 3 When , the frequency of the first variable frequency feeder is 100% of the normal working frequency; e. When ΔN>20mg / m 3 When the frequency of the first variable frequency feeder is 20% of the normal working frequency; f. When ΔN>25mg / m 3 When the preset time is reached, the first variable frequency feeder stops working.

7. The control method of a desulfurizing agent feeding system according to claim 6, characterized in that: The preset time of the first variable frequency feeder is 0~180s.

8. The control method of a desulfurizing agent feeding system according to claim 4, characterized in that: When the concentration difference ΔN is less than 10 mg / m 3 When the preset time is reached, the second variable frequency feeder is started and the speed of the second variable frequency feeder automatically runs as follows: a. When 5mg / m 3 <ΔN≤10mg / m 3 When the frequency of the second variable frequency feeder is 30% of the normal working frequency; b. When 0mg / m 3 <ΔN≤5mg / m 3 When the frequency of the second variable frequency feeder is 50% of the normal working frequency; c. When -5mg / m 3 <ΔN≤0mg / m 3 When the frequency of the second variable frequency feeder is 70% of the normal working frequency; d. When ΔN≤-5mg / m 3 When the frequency of the second variable frequency feeder is 100% of the normal working frequency; e. When the concentration difference ΔN>10mg / m 3 When the frequency of the second variable frequency feeder is 20% of the normal working frequency; f. When ΔN>15mg / m 3 When the preset time is reached, the second variable frequency feeder stops working.

9. The control method of a desulfurizing agent feeding system according to claim 8, characterized in that: The preset time of the second variable frequency feeder is 0~180s.

10. The control method of a desulfurizing agent feeding system according to claim 4, characterized in that: The delay time of the first variable frequency feeder and the second variable frequency feeder are respectively 0-180s.

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