Desulfurization wastewater bypass flue gas evaporation tower wet ash bin pump ash conveying control method and system

Abstract

The present application relates to the field of pneumatic conveying, and discloses a desulfurization wastewater bypass flue gas evaporation tower wet ash bin pump ash conveying control method and system. The system comprises an ash conveying bin pump, a bin pump pressure sensor, an inlet and outlet valve, a pulse valve, a boost valve and a controller, etc. The control method executes a first-stage purge after pressurized and fluidized conveying, then constructs a constant-volume one-way pressure relief verification state, the controller collects pressure data to calculate a pressure relief time constant and a normalized pressure relief characteristic quantity, and combines a closed pressure recovery verification calculation composite criterion to determine the wet ash retention degree. The present application can effectively eliminate the measurement disturbance caused by signal interference of the sensor, accurately identify the real emptying state inside the system, and trigger a hierarchical disposal action according to the determination result, so as to apply a low-pressure pulse airflow to the mild retention to avoid wet ash compaction and hardening, and open the boost valve to provide air supply thrust for the severe retention to strengthen the purge, thereby effectively dredging the retained wet ash and ensuring the stable operation of the ash conveying system.

Description

Technical Field

[0001] This invention relates to the field of pneumatic conveying, and more particularly to a method and system for controlling the ash conveying of a wet ash silo pump in a desulfurization wastewater bypass flue gas evaporation tower. Background Technology

[0002] During the evaporation treatment of flue gas bypassing desulfurization wastewater, the collected ash usually contains a certain amount of moisture and exhibits strong adhesion. When using a silo pump pneumatic conveying system to transport this type of wet ash, the wet ash easily adheres and remains on the inner wall of the silo pump and in the ash conveying pipeline. Existing silo pump ash conveying control methods have the following technical defects when dealing with wet ash conveying: Existing ash conveying systems typically rely on monitoring the pressure inside the silo pump to drop to a certain fixed threshold to determine whether the silo pump has been emptied. In actual operation, on the one hand, there are differences in the cavity volume of different silo pumps, and on the other hand, pressure sensors are easily affected by signal interference from the on-site working conditions, resulting in measurement disturbances. Relying solely on a single dynamic pressure relief data or a fixed pressure threshold cannot effectively eliminate the above interferences, making it difficult to accurately identify the true emptying status inside the system. It is easy to misjudge the pressure abnormality caused by increased exhaust resistance as the completion of emptying.

[0003] When mild wet ash retention and adhesion occur inside the silo pump, the existing cleaning methods often directly introduce high-pressure continuous airflow for purging. Since wet ash itself has an adhesive structure, the frontal impact of high-pressure continuous airflow will have a significant compaction effect on the wet ash retained inside the silo pump. This not only fails to effectively loosen the adhesion, but also easily causes the wet ash to harden inside the silo pump, increasing the difficulty of subsequent ash removal.

[0004] When severe wet ash retention occurs in the silo pump and ash conveying pipeline, the material adheres severely, and the conveying resistance in the pipeline increases significantly. The existing system mainly relies on the air intake at the front end of the silo pump for pressurized purging, and lacks effective intervention methods for the pipeline downstream of the discharge valve. The air intake at the front end alone cannot provide sufficient air supply thrust to the ash conveying pipeline, resulting in insufficient unblocking capacity. It is difficult to effectively solve the problem of conveying obstruction under severe adhesion, which affects the overall operational stability of the ash conveying system. Summary of the Invention

[0005] To overcome the above deficiencies, this invention provides a method and system for controlling the ash conveying of wet ash silo pumps in desulfurization wastewater bypass flue gas evaporation towers. The aim is to improve the existing wet ash silo pump ash conveying system, which suffers from problems such as inaccurate venting status identification due to interference, compaction and hardening of wet ash due to high-pressure purging when cleaning mild retention, and difficulty in effectively clearing the blockage due to lack of downstream air supply thrust when dealing with severe retention.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a wet ash silo pump ash conveying control method for desulfurization wastewater bypass flue gas evaporation tower, applied to a wet ash silo pump ash conveying system including an ash silo pump, a feed valve, an air inlet valve, a fluidizing valve, an exhaust valve, a discharge valve, and a silo pump pressure sensor, comprising: The system receives an ash conveying start command, controls the feed valve and exhaust valve to close, and controls the air inlet valve, fluidization valve and discharge valve to open, thereby pressurizing and fluidizing the wet ash in the ash conveying silo pump. The pressure of the silo pump is monitored by the silo pump pressure sensor. When the pressure drops to a preset first set pressure, the discharge valve, air inlet valve and fluidizing valve are controlled to remain open for a preset set time to perform a first-stage purging action. After the first-stage purging action is completed, the air inlet valve and fluidization valve are closed, the feed valve and exhaust valve are kept closed and the discharge valve is opened to construct a constant volume one-way pressure relief verification state; In this state, the first pressure at the first moment and the second pressure at the second moment are collected by the pressure sensor of the silo pump. The pressure relief time constant is calculated by combining the atmospheric pressure at the exhaust end of the system. The pressure relief time constant is calculated based on the time difference between the second moment and the first moment, and the negative value of the logarithm of the ratio of the difference between the second pressure and the atmospheric pressure to the difference between the first pressure and the atmospheric pressure. The normalized pressure relief characteristic quantity is calculated based on the pressure relief time constant and the preset reference pressure relief time constant. When the normalized pressure relief characteristic is less than or equal to the preset first grading threshold, the venting is determined to be normal; when it is greater than the first grading threshold, wet ash retention is determined and a grading treatment action is triggered.

[0007] As a further description of the above technical solution: After determining the presence of wet ash retention and before triggering the corresponding graded treatment actions, the process also includes a step of verifying the recovery of the closed pressure: The discharge valve is closed to create a completely enclosed volume within the ash conveying silo pump and maintain this enclosed state for a preset time. Record the initial pressure corresponding to the closing time of the discharge valve as measured by the pressure sensor of the silo pump, and the ending pressure corresponding to the end time of the closing time as measured by the pressure sensor of the silo pump. Calculate the difference between the ending pressure and the initial pressure to obtain the pressure recovery amount. A composite criterion is calculated and determined based on the normalized pressure relief characteristic, the pressure recovery amount, the preset first weighting coefficient, the preset second weighting coefficient, and the preset reference pressure. The composite criterion is obtained by summing the product of the normalized pressure relief characteristic and the first weighting coefficient, and the product of the ratio of the pressure recovery amount to the preset reference pressure multiplied by the second weighting coefficient. When the composite criterion is less than or equal to the set threshold, it is determined that the current pressure data abnormality is caused by measurement disturbance and the current ash conveying cycle ends. When the composite criterion is greater than the set threshold, it is confirmed that wet ash retention has occurred inside the ash conveying silo pump and the graded treatment action is performed.

[0008] As a further description of the above technical solution: When the wet ash silo pump conveying system further includes a pulse valve connected to the pump cone of the ash silo, the graded treatment action includes treatment for mild wet ash retention, and the specific steps are as follows: When the normalized pressure relief characteristic is greater than the first classification threshold and less than or equal to the preset second classification threshold, it is determined that there is slight wet ash retention inside the ash conveying silo pump. The pulse valve is controlled to open and close according to a preset pulse width and frequency, and a low-pressure pulse airflow is applied to the cone of the ash conveying silo pump to perform a low-pressure pulse loosening action. The pulse pressure value of the low-pressure pulse airflow is lower than the working pressure value of the ash conveying silo pump when it is pressurized and fluidized. After the low-pressure pulse loosening action is completed, the discharge valve, the air inlet valve and the fluidization valve are opened to perform a secondary purging action. After the secondary purging action is completed, the process returns to the step of performing the construction constant volume one-way pressure relief verification state.

[0009] As a further description of the above technical solution: In the case where the wet ash silo pump conveying system also includes an ash conveying pipeline and a booster valve connected to the ash conveying pipeline, and the ash conveying pipeline is connected downstream of the discharge valve, the grading treatment action includes treatment for severely retained wet ash, and the specific steps are as follows: When the normalized pressure relief characteristic is greater than the preset second classification threshold, it is determined that there is severe wet ash retention inside the ash conveying silo pump. The discharge valve, the air inlet valve, and the fluidization valve are opened synchronously, and the booster valve is opened to provide supplementary air thrust into the ash conveying pipeline to perform a secondary enhanced purging action; After the secondary enhanced purging action is completed, return to the step of performing the construction constant volume unidirectional pressure relief verification state.

[0010] As a further description of the above technical solution: If the wet ash silo pump conveying system also includes an air source pressure sensor, the control method further includes: Before receiving the ash conveying start command, or before performing the corresponding graded treatment action, the gas source pressure data is obtained through the gas source pressure sensor. When it is determined that the gas source pressure data deviates from the preset normal working range, the corresponding action is prohibited and a prompt signal is output. Record the number of cycles in which the step of constructing the constant-volume one-way pressure relief verification state is executed. When it is determined that the number of cycles has reached the preset upper limit and the composite criterion obtained in the current cycle is greater than the set threshold, stop all purging actions and output an alarm signal.

[0011] As a further description of the above technical solution: A wet ash silo pump conveying system for the desulfurization wastewater bypass flue gas evaporator, comprising a method for controlling the ash conveying of the wet ash silo pump in the desulfurization wastewater bypass flue gas evaporator, including: An evaporator ash hopper, with an ash outlet at the bottom; and an ash conveying pump, with a feed inlet and an exhaust outlet at the top and a discharge outlet at the bottom. A feed valve is installed on the ash discharge pipe connecting the ash outlet and the feed inlet; An exhaust valve is provided on the exhaust pipe connected to the exhaust port; A discharge valve is installed on the discharge pipe connected to the discharge port; An ash conveying pipe, one end of which is connected to the discharge pipe; A pressure sensor for the ash conveying silo pump is installed on top of the ash conveying silo pump and is used to detect the pressure inside the ash conveying silo pump; The first air supply branch pipe is used to pressurize and supply air into the ash conveying silo pump, and the air inlet valve is disposed on the first air supply branch pipe; The third air supply branch is used to provide fluidizing air to the ash conveying silo pump. The fluidizing valve is disposed on the third air supply branch. A controller is electrically connected to the feed valve, the exhaust valve, the discharge valve, the silo pump pressure sensor, the air inlet valve, and the fluidizing valve, respectively. The controller is configured to execute the control method.

[0012] As a further description of the above technical solution: The lower part of the ash conveying silo pump is conical to form a cone. The system also includes a pulse valve, which is disposed on a second air supply branch pipe connected to the cone. The pulse valve is electrically connected to the controller and is configured to be controlled by the controller to apply a low-pressure pulsed airflow.

[0013] As a further description of the above technical solution: The bottom of the ash conveying silo pump is equipped with a fluidizing chamber, and the top of the fluidizing chamber is equipped with a fluidizing perforated plate. The third gas supply branch pipe is connected to the fluidizing chamber through the fluidizing valve, and the gas supplied into the fluidizing chamber can penetrate upward through the fluidizing perforated plate.

[0014] As a further description of the above technical solution: The system also includes a booster valve; the booster valve is configured on the fourth air supply branch pipe of the ash conveying pipe connected downstream of the discharge valve; the booster valve is electrically connected to the controller.

[0015] As a further description of the above technical solution: The system also includes a compressed air source and an air source pressure sensor. The compressed air source is connected to an outlet main pipe, and the air source pressure sensor is disposed on the outlet main pipe. The outlet main pipe branches off at least a first air supply branch pipe and a third air supply branch pipe. The air source pressure sensor is electrically connected to the controller.

[0016] The present invention has the following beneficial effects: 1. The present invention uses a controller based on the first time t1, the first pressure P1, the second time t2, the second pressure P2, and the atmospheric pressure P. atm Calculate the pressure relief time constant τ, and calculate the normalized pressure relief characteristic quantity K based on the pressure relief time constant τ and the reference pressure relief time constant τ0 pre-stored in the controller. τ This method can eliminate the background difference caused by the volume of the ash conveying silo pump itself. At the same time, by combining the calculated composite criterion R with the exhaust resistance data during the dynamic depressurization process and the pressure recovery data under closed state, it can be used to verify the state, eliminate the measurement disturbance caused by signal interference of the silo pump pressure sensor, and thus accurately identify the true venting state inside the system.

[0017] 2. For mild retention conditions, this invention controls the pulse valve to open and close according to a preset pulse width and frequency, so that the pulse valve applies pulsed airflow to the cone of the ash conveying silo pump. Since the pulse pressure of the pulsed airflow is lower than the working pressure of the ash conveying silo pump under normal conveying conditions, it can destroy the bonding structure inside the wet ash, causing the attached wet ash to loosen and fall off. The system uses pulsed airflow at a lower pressure than the working pressure under normal conveying conditions, avoiding the compaction effect of high-pressure continuous airflow on the wet ash retained inside the ash conveying silo pump, and preventing the wet ash from hardening inside the ash conveying silo pump.

[0018] 3. For severe retention conditions, this invention controls the discharge valve, air inlet valve, and fluidizing valve to open synchronously via a controller to purge the ash conveying silo pump and ash conveying pipeline. At the same time, the controller controls the booster valve to open, and compressed air supplied by the compressed air source enters the ash conveying pipeline downstream of the discharge valve through the fourth air supply branch pipe and the booster valve. This coordinated operation can provide supplementary air thrust to the ash conveying pipeline to clear the retained wet ash, effectively solving the problem of conveying obstruction under severe adhesion conditions and ensuring the stable operation of the ash conveying system. Attached Figure Description

[0019] Figure 1This is a schematic diagram of the wet ash silo pump conveying system of the desulfurization wastewater bypass flue gas evaporator tower of the present invention; Figure 2 This is a schematic diagram of the ash conveying control process of the wet ash silo pump in the desulfurization wastewater bypass flue gas evaporation tower according to the present invention.

[0020] Legend: 1. Evaporation tower ash hopper; 2. Feed valve; 3. Ash conveying silo pump; 4. Exhaust valve; 5. Silo pump pressure sensor; 6. Discharge valve; 7. Ash conveying pipeline; 8. Pipeline pressure sensor; 9. Ash storage silo; 10. Compressed air source; 11. Air source pressure sensor; 12. Inlet valve; 13. Pulse valve; 14. Fluidizing valve; 15. Boosting valve; 16. Controller. Detailed Implementation

[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] Reference Figure 1 - Figure 2 The invention provides a wet ash silo pump conveying system for a desulfurization wastewater bypass flue gas evaporator, including an evaporator ash hopper 1, a feed valve 2, an ash conveying silo pump 3, an exhaust valve 4, a silo pump pressure sensor 5, a discharge valve 6, an ash conveying pipeline 7, a pipeline pressure sensor 8, an ash storage silo 9, a compressed air source 10, an air source pressure sensor 11, an inlet valve 12, a pulse valve 13, a fluidizing valve 14, a booster valve 15, and a controller 16.

[0023] An evaporator ash hopper 1 is located at the bottom of the bypass flue gas evaporator. An ash outlet is located at the bottom of the evaporator ash hopper 1. An inlet is located at the top of the ash conveying silo pump 3. The ash outlet is connected to the inlet via an ash discharge pipe, and an inlet valve 2 is installed on the ash discharge pipe. An exhaust port is located at the top of the ash conveying silo pump 3. An exhaust pipe is connected to the exhaust port, and an exhaust valve 4 is installed on the exhaust pipe. A silo pump pressure sensor 5 is also installed at the top of the ash conveying silo pump 3. The silo pump pressure sensor 5 is used to detect the pressure inside the ash conveying silo pump 3.

[0024] The bottom of the ash conveying silo pump 3 is provided with a discharge port, which is connected to the ash conveying pipeline 7 through a discharge pipe. A discharge valve 6 is provided on the discharge pipe. The end of the ash conveying pipeline 7 is connected to the ash storage silo 9. The top of the ash storage silo 9 is open to the atmosphere. A pipeline pressure sensor 8 is provided on the ash conveying pipeline 7 downstream of the discharge valve 6. The pipeline pressure sensor 8 is used to monitor the pressure change of the ash conveying pipeline 7 during the conveying process.

[0025] Compressed air source 10 is connected to an outlet main pipe, on which an air source pressure sensor 11 is installed. The outlet main pipe branches into four supply branches: the first supply branch is connected to the top of the ash conveying silo pump 3 via an inlet valve 12, for pressurizing the ash conveying silo pump 3; the lower part of the ash conveying silo pump 3 is conical to form a cone, the second supply branch is connected to the cone of the ash conveying silo pump 3 via a pulse valve 13, for applying low-pressure pulsed airflow into the ash conveying silo pump 3; a fluidizing chamber is provided at the bottom of the ash conveying silo pump 3, and a fluidizing perforated plate is provided at the top of the fluidizing chamber, the third supply branch is connected to the fluidizing chamber via a fluidizing valve 14, for providing fluidizing air to the ash conveying silo pump 3; the fourth supply branch is connected to the ash conveying pipe 7 downstream of the discharge valve 6 via a booster valve 15, for boosting and supplementing air into the ash conveying pipe 7.

[0026] The controller 16 is electrically connected to the feed valve 2, exhaust valve 4, silo pump pressure sensor 5, discharge valve 6, pipeline pressure sensor 8, air source pressure sensor 11, air inlet valve 12, pulse valve 13, fluidizing valve 14, and booster valve 15, respectively. The controller 16 is used to collect the detection signals from the silo pump pressure sensor 5, pipeline pressure sensor 8, and air source pressure sensor 11, and control the opening and closing states of the feed valve 2, exhaust valve 4, discharge valve 6, air inlet valve 12, pulse valve 13, fluidizing valve 14, and booster valve 15 according to the detection signals. The controller 16 is a PLC control unit or a DCS control unit; the pulse valve 13 is an electromagnetic pulse valve; and the air inlet valve 12, fluidizing valve 14, and booster valve 15 are electromagnetic valves or pneumatic regulating valves.

[0027] Based on the above-mentioned desulfurization wastewater bypass flue gas evaporator wet ash silo pump ash conveying system, controller 16 executes the desulfurization wastewater bypass flue gas evaporator wet ash silo pump ash conveying control process. For ease of explanation, all pressure values ​​involved in this embodiment are gauge pressure (i.e., atmospheric pressure). Furthermore, the controller 16 has the following parameters pre-set as the basis for execution in specific embodiments. It should be understood that the following parameters are merely examples of a preferred embodiment of the present invention and are not intended to absolutely limit the scope of protection of the present invention: the normal operating range is, for example, First set pressure For example, Set time For example, Pressure relief verification window For example, Reference decompression time constant For example, , grading threshold For example, take and For example, take Set time For example, Weighting coefficient For example, take and For example, take Reference pressure For example, Set threshold For example, Maximum number of times For example, Second-rate.

[0028] Before ash conveying begins, the controller 16 acquires the air source pressure data detected by the air source pressure sensor 11. When the controller 16 determines that the air source pressure data is within the normal operating range, it generates an ash conveying start command. When the controller 16 determines that the air source pressure data is below the lower limit of the normal operating range, it stops the start operation and outputs a prompt signal to terminate the current ash conveying cycle.

[0029] When the controller 16 generates the ash conveying start command, it controls the feed valve 2 and the exhaust valve 4 to close, so as to cut off the connection between the evaporator ash hopper 1 and the ash conveying silo pump 3, and cut off the connection between the ash conveying silo pump 3 and the atmosphere; at the same time, the controller 16 controls the discharge valve 6, the air inlet valve 12 and the fluidization valve 14 to open.

[0030] At this time, the compressed air provided by the compressed air source 10 is divided into two paths: one path enters the interior of the ash conveying silo pump 3 through the first air supply branch pipe and the air inlet valve 12, applying downward pressure to the wet ash in the ash conveying silo pump 3; the other path enters the fluidization chamber at the bottom of the ash conveying silo pump 3 through the third air supply branch pipe and the fluidization valve 14, and penetrates upward through the fluidization perforated plate set at the top of the fluidization chamber, uniformly entering the wet ash layer in the ash conveying silo pump 3, changing the physical morphology of the wet ash layer, and making the wet ash present a fluidized state. Under the above-mentioned pressurization and fluidization action, the wet ash enters the discharge pipe through the discharge port at the bottom of the ash conveying silo pump 3, and passes through the discharge valve 6 into the ash conveying pipeline 7. The wet ash in the ash conveying pipeline 7 moves towards the ash storage silo 9 under the push of the airflow.

[0031] During the wet ash conveying process, the silo pump pressure sensor 5 monitors the pressure data inside the ash conveying silo pump 3 in real time and generates the silo pump pressure. The controller 16 reads the pressure of the chamber pump at a preset sampling frequency. As wet ash in the ash conveying silo pump 3 is discharged into the ash conveying pipe 7, the wet ash level in the ash conveying silo pump 3 gradually decreases, the free volume occupied by gas increases, and the silo pump pressure sensor 5 detects the silo pump pressure. It is showing a downward trend.

[0032] As ash conveying proceeds, when controller 16 determines the pressure of the silo pump... Reduced to the first set pressure When the system determines that the main body of wet ash in the ash conveying silo pump 3 has been conveyed, the system enters the initial endpoint determination state; wherein, the first set pressure The constant pressure threshold parameter is pre-stored in the controller 16.

[0033] After the system enters the initial endpoint judgment state, the controller 16 controls the discharge valve 6 to remain open, and controls the air inlet valve 12 and fluidization valve 14 to remain open, continuing to supply compressed air to the ash conveying pump 3 and fluidization chamber for the set time. Compressed air at the set time The ash enters the ash conveying pipe 7 through the ash conveying silo pump 3, and performs a first-level purging action on the wet ash remaining in the ash conveying pipe 7. The continuous airflow propels the wet ash remaining in the ash conveying pipe 7 into the ash storage silo 9.

[0034] After the first-stage purging action is completed, the controller 16 controls the inlet valve 12 and the fluidizing valve 14 to close, thereby cutting off the power supply air circuit to the ash conveying silo pump 3. At the same time, the controller 16 controls the exhaust valve 4 to remain closed and the discharge valve 6 to remain open. When the inlet valve 12, fluidizing valve 14, and exhaust valve 4 are closed and the discharge valve 6 is open, there is no longer an external air source input to the ash conveying silo pump 3. The residual pressurized gas in the ash conveying silo pump 3 is discharged unidirectionally to the ash storage silo 9 through the discharge valve 6 and the ash conveying pipeline 7. Since the ash storage silo 9 is connected to the atmosphere, the back pressure at the exhaust end of the system is a constant atmospheric pressure. At this point, the system enters the pressure relief verification window. .

[0035] In the pressure relief verification window Inside, the ash conveying silo pump 3 and the ash conveying pipeline 7 together constitute a constant-volume unidirectional venting system. Since the material level is fixed, the free volume occupied by the gas in the ash conveying silo pump 3 is considered to be a constant value. The process of residual gas being discharged to the ash storage silo 9 is subject to the resistance of the exhaust path. The equivalent exhaust conductance of the exhaust path is defined as the ratio of the gas flow rate to the pressure difference at both ends of the exhaust channel, which is used to characterize the channel's ability to conduct gas. When wet ash adheres and remains in the cone of the ash conveying silo pump 3, the discharge valve 6, or the ash conveying pipeline 7, the effective flow cross-sectional area of ​​the gas discharge is limited, and the equivalent exhaust conductance of the exhaust path decreases.

[0036] During this period, the pressure sensor 5 continuously collects the pressure inside the ash conveying silo pump 3, and the pressure sensor 5 collects the pressure at the first moment. The corresponding first pressure and the second moment of data collection The corresponding second pressure ; where, the first moment and the second moment Satisfy the first pressure Greater than the second pressure And the second pressure Greater than the atmospheric pressure conditions.

[0037] Controller 16 based on the first moment The first pressure The second moment The second pressure and the atmospheric pressure Calculate the pressure relief time constant The pressure relief time constant The calculation formula is:

[0038] Under the condition that the free volume inside the ash conveying silo pump 3 remains constant, the pressure relief time constant is... The value of this constant is inversely proportional to the equivalent exhaust conductance of the exhaust path. When wet ash retention occurs inside the exhaust path, causing a decrease in the equivalent exhaust conductance, the calculated pressure relief time constant... Increase.

[0039] Controller 16 according to the pressure relief time constant and the reference pressure relief time constant pre-stored in controller 16 Calculate the normalized pressure relief characteristic quantity To eliminate the background difference caused by the volume of the ash conveying silo pump 3 itself; wherein, the reference pressure relief time constant The normalized pressure relief characteristic quantity is the pressure relief time constant measured and pre-stored in the controller 16 under the condition that the system is in a venting state with no wet ash retention. The calculation formula is:

[0040] The controller 16 will calculate the generated normalized pressure relief characteristic. As a parameter characterizing the relative rate of change of the flow resistance in the exhaust path, it provides a basis for subsequent identification of whether there is a "false exhaust" phenomenon.

[0041] Subsequently, the controller 16 determines the normalized pressure relief characteristic quantity. Is it greater than the classification threshold? When the controller 16 determines the normalized pressure relief characteristic quantity Less than or equal to the grading threshold When the ash conveying silo pump 3 is emptied normally, the current ash conveying cycle ends; when the controller 16 determines the normalized pressure relief characteristic quantity... Greater than the grading threshold At that time, the control system performs a closed-pressure recovery verification.

[0042] During the closed pressure recovery verification, the controller 16 controls the discharge valve 6 to close. At this time, the feed valve 2, exhaust valve 4, air inlet valve 12, fluidization valve 14, and discharge valve 6 are all closed, and the internal space of the ash conveying silo pump 3 forms a completely closed volume. The controller 16 records the silo pump pressure corresponding to the moment the discharge valve 6 closes. And control the ash conveying silo pump 3 to remain in a closed state for the set time. Subsequently, the set time is measured by the pressure sensor 5 of the silo pump. The pressure of the silo pump at the end of the time .

[0043] The wet ash retained inside the ash silo pump 3 is pressurized during the pressurized conveying stage, forming a porous wet ash layer. Pressurized gas enters the pores of this porous wet ash layer, forming a sealed gas, which is then released during the previous pressure relief verification window. Inside the ash conveying silo pump 3, the pressure in the free volume space drops rapidly, causing a pressure difference to form between the pressure of the closed gas inside the pores of the porous wet ash layer and the pressure in the free volume space. This pressure difference occurs during a set time when the ash conveying silo pump 3 is in a closed state. Driven by the aforementioned pressure difference, the closed gas inside the porous wet ash layer overcomes the wet ash resistance and is slowly released into the free volume space of the ash conveying silo pump 3. The continuous release of gas inside the porous wet ash layer causes the pressure inside the ash conveying silo pump 3 to rise.

[0044] Controller 16 calculates the pressure of the chamber pump. With the pressure of the chamber pump The difference yields the pressure recovery amount. When the ash conveying silo pump 3 is emptied normally, there is no porous wet ash layer inside the ash conveying silo pump 3. The internal pressure of the ash conveying silo pump 3 remains constant when it is in a closed state. The pressure rise measured by the silo pump pressure sensor 5 is... Approaching zero, the pressure recovery amount The value reflects the severity of wet ash retention inside the ash conveying silo pump 3.

[0045] The controller 16 determines the normalized pressure relief characteristic based on the normalized pressure relief characteristic. The pressure recovery amount The preset weighting coefficients The preset weighting coefficients and the preset reference pressure Calculate the composite criterion The composite criterion The calculation formula is:

[0046] The composite criterion The exhaust resistance data during the dynamic depressurization process is correlated with the pressure recovery data under closed conditions to verify the status and eliminate measurement disturbances caused by signal interference in the chamber pump pressure sensor 5.

[0047] The controller 16 will calculate the generated composite criterion. With the set threshold A numerical comparison is performed, and the controller 16 determines the composite criterion. Less than or equal to the set threshold When the current pressure data anomaly is determined to be caused by a measurement disturbance, the current ash conveying cycle is terminated directly; when the controller 16 determines the composite criterion... Greater than the set threshold At that time, it was confirmed that wet ash was trapped inside the ash conveying silo pump 3, and based on the normalized pressure relief characteristic value... The specific numerical range triggers the corresponding graded handling action.

[0048] Specifically, for mild stagnation conditions, when the controller 16 determines the normalized pressure relief characteristic quantity... Greater than the grading threshold And less than or equal to the grading threshold At that time, it was determined that there was slight wet ash retention inside the ash conveying silo pump 3.

[0049] At this time, the controller 16 acquires the air source pressure data detected by the air source pressure sensor 11. When the controller 16 determines that the air source pressure data is within the normal operating range, the control system executes the low-pressure pulse loosening action. When the controller 16 determines that the air source pressure data deviates from the normal operating range, the system is prohibited from executing the low-pressure pulse loosening action, and a prompt signal is output.

[0050] When performing the low-pressure pulse loosening action, the controller 16 controls the pulse valve 13 to open and close according to a preset pulse width and frequency, so that the pulse valve 13 applies a pulsed airflow to the cone section of the ash conveying pump 3; wherein, as a preferred embodiment, the pulse pressure value of the pulsed airflow is, for example, to The pulse width is, for example, to The pulse frequency is, for example, to The duration is, for example, to The pulse pressure value of the pulsed airflow is lower than the working pressure value of the ash conveying silo pump 3 under normal conveying conditions.

[0051] The pulsed airflow creates alternating stress inside the ash conveying silo pump 3. This alternating stress acts on the wet ash adhering to the inner wall of the cone of the ash conveying silo pump 3, destroying the internal bonding structure of the wet ash, causing the adhering wet ash to loosen and fall off. The system uses the pulsed airflow at a lower pressure than the normal conveying operating pressure, which avoids the high-pressure continuous airflow from compacting the wet ash retained inside the ash conveying silo pump 3 and prevents the wet ash from hardening inside the ash conveying silo pump 3.

[0052] After the low-pressure pulse loosening action ends, the controller 16 controls the discharge valve 6 to open, and controls the air inlet valve 12 and fluidization valve 14 to open to perform a secondary purging action. During the secondary purging action, the discharge valve 6 remains open, and the compressed air introduced through the air inlet valve 12 and fluidization valve 14 provides a continuous airflow to discharge the loosened and detached wet ash into the ash conveying pipe 7. After the secondary purging action ends, the controller 16 controls the system to return to the operation of constructing the pressure relief verification window. The steps are to recalculate the normalized pressure relief characteristic. Verify the venting status inside the ash conveying silo pump 3.

[0053] On the other hand, for severe retention conditions, when the controller 16 determines the normalized pressure relief characteristic quantity... Greater than the grading threshold At that time, it was determined that there was severe wet ash retention inside the ash conveying silo pump 3.

[0054] At this time, the controller 16 acquires the air source pressure data detected by the air source pressure sensor 11. When the controller 16 determines that the air source pressure data is within the normal operating range, the control system executes the secondary enhanced purging action. When the controller 16 determines that the air source pressure data deviates from the normal operating range, the system is prohibited from executing the secondary enhanced purging action, and a prompt signal is output.

[0055] When performing the secondary enhanced purging action, the controller 16 controls the discharge valve 6, the air inlet valve 12 and the fluidizing valve 14 to open synchronously to purge the ash conveying silo pump 3 and the ash conveying pipeline 7; at the same time, the controller 16 controls the booster valve 15 to open, and the compressed air provided by the compressed air source 10 enters the ash conveying pipeline 7 downstream of the discharge valve 6 through the fourth air supply branch pipe and the booster valve 15, providing supplementary air thrust to the ash conveying pipeline 7 to clear the stagnant wet ash.

[0056] After the secondary enhanced purging action is completed, controller 16 controls the system to return to the execution of constructing the pressure relief verification window. The steps are to recalculate the normalized pressure relief characteristic. To verify the evacuation status inside the ash silo pump 3, the loop variable built into the controller 16 is used. The recording system returns to the constructed pressure relief verification window. The number of times the step is executed, and each time the system returns to execute the construction of the pressure relief verification window. During the step, controller 16 controls the loop variable. Add 1.

[0057] When controller 16 determines the loop variable The maximum number of times reached And the composite criterion obtained within the current cycle. Greater than the set threshold When this occurs, controller 16 stops all purging actions and outputs an alarm signal to prompt manual inspection and handling, in order to prevent the wet ash inside the ash conveying silo pump 3 and ash conveying pipeline 7 from being deeply compacted due to continuous cyclic pressurized purging.

[0058] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. 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 ash conveying of a wet ash silo pump in a desulfurization wastewater bypass flue gas evaporator, applied to a wet ash silo pump ash conveying system including an ash silo pump (3), a feed valve (2), an air inlet valve (12), a fluidizing valve (14), an exhaust valve (4), a discharge valve (6), and a silo pump pressure sensor (5), characterized in that, include: Obtain the ash conveying start command, control the feed valve (2) and exhaust valve (4) to close, and control the air inlet valve (12), fluidization valve (14) and discharge valve (6) to open, pressurize and fluidize the wet ash in the ash conveying silo pump (3); The pressure of the silo pump is monitored by the silo pump pressure sensor (5). When the pressure drops to the preset first set pressure, the discharge valve (6), air inlet valve (12) and fluidizing valve (14) are controlled to remain open for a preset set time to perform the first-level purging action. After the first-stage purging action is completed, the air inlet valve (12) and fluidization valve (14) are closed, the feed valve (2) and exhaust valve (4) are kept closed and the discharge valve (6) is opened, thus constructing a constant volume one-way pressure relief verification state; In this state, the first pressure at the first moment and the second pressure at the second moment are collected by the pressure sensor (5) of the silo pump. The pressure relief time constant is calculated by combining the atmospheric pressure at the exhaust end of the system. The pressure relief time constant is calculated based on the time difference between the second moment and the first moment, and the negative value of the logarithm of the ratio of the difference between the second pressure and the atmospheric pressure to the difference between the first pressure and the atmospheric pressure. The normalized pressure relief characteristic quantity is calculated based on the pressure relief time constant and the preset reference pressure relief time constant. When the normalized pressure relief characteristic is less than or equal to the preset first grading threshold, the venting is determined to be normal; when it is greater than the first grading threshold, wet ash retention is determined and a grading treatment action is triggered.

2. The ash conveying control method for the wet ash silo pump of the desulfurization wastewater bypass flue gas evaporator as described in claim 1, characterized in that, After determining the presence of wet ash retention and before triggering the corresponding graded treatment actions, the process also includes a step of verifying the recovery of the closed pressure: Control the discharge valve (6) to close, so that the internal space of the ash conveying silo pump (3) forms a completely closed volume state and maintains the closed state for a preset time; Record the initial pressure corresponding to the closing time of the discharge valve (6) measured by the pressure sensor (5) of the silo pump, and the ending pressure corresponding to the end time of the closing time measured by the pressure sensor (5) of the silo pump, and calculate the pressure recovery amount by the difference between the ending pressure and the initial pressure. A composite criterion is calculated and determined based on the normalized pressure relief characteristic, the pressure recovery amount, the preset first weighting coefficient, the preset second weighting coefficient, and the preset reference pressure. The composite criterion is obtained by summing the product of the normalized pressure relief characteristic and the first weighting coefficient, and the product of the ratio of the pressure recovery amount to the preset reference pressure multiplied by the second weighting coefficient. When the composite criterion is less than or equal to the set threshold, it is determined that the current pressure data abnormality is caused by measurement disturbance and the current ash conveying cycle ends. When the composite criterion is greater than the set threshold, it is confirmed that wet ash stagnation has occurred inside the ash conveying silo pump (3) and the graded treatment action is performed.

3. The ash conveying control method for the wet ash silo pump of the desulfurization wastewater bypass flue gas evaporator tower according to claim 2, characterized in that, In the case where the wet ash silo pump conveying system also includes a pulse valve (13) connected to the cone of the ash conveying silo pump (3), the graded treatment action includes treatment for mild wet ash retention, and the specific steps are as follows: When the normalized pressure relief characteristic is greater than the first grading threshold and less than or equal to the preset second grading threshold, it is determined that there is slight wet ash retention inside the ash conveying silo pump (3); The pulse valve (13) is controlled to open and close according to the preset pulse width and frequency, and a low-pressure pulse airflow is applied to the cone of the ash conveying silo pump (3) to perform a low-pressure pulse loosening action. The pulse pressure value of the low-pressure pulse airflow is lower than the working pressure value of the ash conveying silo pump (3) when it is pressurized and fluidized. After the low-pressure pulse loosening action is completed, the discharge valve (6), the air inlet valve (12) and the fluidization valve (14) are controlled to open to perform a secondary purging action. After the secondary purging action is completed, the process returns to the step of performing the construction constant volume one-way pressure relief verification state.

4. The ash conveying control method for the wet ash silo pump of the desulfurization wastewater bypass flue gas evaporator tower according to claim 2, characterized in that, In the case where the wet ash silo pump conveying system also includes an ash conveying pipe (7) and a booster valve (15) connected to the ash conveying pipe (7), and the ash conveying pipe (7) is connected downstream of the discharge valve (6), the graded treatment action includes treatment for severe wet ash retention, and the specific steps are as follows: When the normalized pressure relief characteristic is greater than the preset second classification threshold, it is determined that there is severe wet ash retention inside the ash conveying silo pump (3); The discharge valve (6), the air inlet valve (12) and the fluidization valve (14) are opened synchronously, and the booster valve (15) is opened to provide supplementary air thrust into the ash conveying pipe (7) to perform a secondary enhanced purging action; After the secondary enhanced purging action is completed, return to the step of performing the construction constant volume unidirectional pressure relief verification state.

5. The method for controlling ash conveying of the wet ash silo pump in the desulfurization wastewater bypass flue gas evaporator according to any one of claims 2 to 4, characterized in that, If the wet ash silo pump conveying system also includes an air source pressure sensor (11), the control method further includes: Before receiving the ash conveying start command, or before performing the corresponding graded treatment action, the gas source pressure data is obtained through the gas source pressure sensor (11). When it is determined that the gas source pressure data deviates from the preset normal working range, the corresponding action is prohibited and a prompt signal is output. Record the number of cycles in which the step of constructing the constant-volume one-way pressure relief verification state is executed. When it is determined that the number of cycles has reached the preset upper limit and the composite criterion obtained in the current cycle is greater than the set threshold, stop all purging actions and output an alarm signal.

6. A wet ash silo pump conveying system for a desulfurization wastewater bypass flue gas evaporator, used to implement the wet ash silo pump conveying control method for a desulfurization wastewater bypass flue gas evaporator as described in any one of claims 1 to 5, characterized in that, include: Evaporation tower ash hopper (1), the bottom of the evaporation tower ash hopper (1) is provided with an ash outlet; Ash conveying silo pump (3), the top of the ash conveying silo pump (3) is provided with a feed inlet and an exhaust outlet, and the bottom is provided with a discharge outlet; Feed valve (2) is installed on the ash discharge pipe connecting the ash outlet and the feed inlet; An exhaust valve (4) is provided on an exhaust pipe connected to the exhaust port; A discharge valve (6) is provided on the discharge pipe connected to the discharge port; Ash conveying pipe (7), one end of which is connected to the discharge pipe; A pressure sensor (5) for the ash conveying silo pump is installed on the top of the ash conveying silo pump (3) and is used to detect the pressure inside the ash conveying silo pump (3); The first air supply branch pipe is used to pressurize the ash conveying silo pump (3) and the air inlet valve (12) is disposed on the first air supply branch pipe; The third air supply branch is used to provide fluidizing air to the ash conveying silo pump (3). The fluidizing valve (14) is disposed on the third air supply branch. The controller (16) is electrically connected to the feed valve (2), the exhaust valve (4), the discharge valve (6), the silo pump pressure sensor (5), the air inlet valve (12), and the fluidizing valve (14), respectively. The controller (16) is configured to execute the control method.

7. The ash conveying system for the wet ash silo pump of the desulfurization wastewater bypass flue gas evaporator tower according to claim 6, characterized in that, The lower part of the ash conveying pump (3) is conical to form a cone. The system also includes a pulse valve (13), which is disposed on a second air supply branch pipe connected to the cone. The pulse valve (13) is electrically connected to the controller (16) and is configured to apply a low-pressure pulse airflow under the control of the controller (16).

8. The desulfurization wastewater bypass flue gas evaporator wet ash silo pump conveying system according to claim 6, characterized in that, The bottom of the ash conveying silo pump (3) is equipped with a fluidizing chamber, and the top of the fluidizing chamber is equipped with a fluidizing perforated plate. The third gas supply branch pipe is connected to the fluidizing chamber through the fluidizing valve (14), and the gas supplied into the fluidizing chamber can penetrate the fluidizing perforated plate upward.

9. The desulfurization wastewater bypass flue gas evaporator wet ash silo pump conveying system according to claim 6, characterized in that, The system also includes a booster valve (15); the booster valve (15) is configured on the fourth air supply branch pipe of the ash conveying pipe (7) connected downstream of the discharge valve (6); the booster valve (15) is electrically connected to the controller (16).

10. The desulfurization wastewater bypass flue gas evaporator wet ash silo pump conveying system according to claim 6, characterized in that, The system also includes a compressed air source (10) and an air source pressure sensor (11). The compressed air source (10) is connected to an air outlet main pipe. The air source pressure sensor (11) is installed on the air outlet main pipe. The air outlet main pipe branches out at least a first air supply branch pipe and a third air supply branch pipe. The air source pressure sensor (11) is electrically connected to the controller (16).

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