Coal blocking prevention method for pulverized coal boiler

Abstract

This application discloses a method for preventing coal blockage in a pulverized coal boiler, including collecting various parameters of the pulverized coal boiler; when the fluctuations of the main steam flow and main steam pressure within a preset fluctuation threshold within a preset collection period, and the coal feeder is in operation, and the target flow value has not changed, and the instantaneous flow value is lower than the target flow value by a first preset deviation threshold for a continuous preset time threshold, or the instantaneous flow value is lower than the previous collection period by a second preset deviation threshold, a coal blockage alarm is triggered until the triggering condition disappears; when a coal blockage alarm is triggered, the coal bunker is vibrated; when the mill outlet temperature is higher than a preset temperature threshold, the opening of the hot air valve is reduced and the opening of the cold air valve is increased until coal blockage is resolved, at which point the opening is restored to its initial value. This method allows for early detection and intervention before coal blockage occurs, effectively preventing coal blockage and reducing the frequency of manual intervention, thus improving the operational stability and safety of the pulverized coal boiler.

Description

Technical Field

[0001] This invention belongs to the field of boiler control technology, and in particular relates to a method for preventing coal blockage in pulverized coal boilers. Background Technology

[0002] The upper part of the raw coal bunker is cylindrical, while the lower part is a hyperbolic cone, with a larger upper opening and a smaller lower opening. The raw coal falls from top to bottom under its own weight. As the raw coal flows downwards within the conical bunker, its surface area gradually decreases, creating greater compressive force on the coal itself. This increases the external force and probability of fine coal dust adhering to the inner wall of the bunker. Since the raw coal flows from the inner wall towards the central chute, it does not exert a significant scouring force on the inner wall. Therefore, under natural conditions, fine coal dust easily adheres to the inner wall of the bunker. Once the coal dust adheres to the inner wall, its friction coefficient... The number of particles will increase rapidly, causing raw coal powder to accumulate layer by layer on the inner wall of the coal bunker. The increased friction coefficient of the conical coal bunker is the main cause of blockage. In addition, some coals have a high moisture content, fine coal powder, and are subject to temperature changes in winter and summer. They are stored in the coal bunker for a long time. Some coals also have a high proportion of coal slurry. The friction coefficient between the inner wall of the coal bunker and the coal powder, as well as the structure of the gate valve, can all cause poor coal flow, coal sloshing, or coal interruption. All of these will affect the safe and normal operation of the boiler. Therefore, when coal blockage occurs, it is necessary to dredge and clean the coal chute and coal bunker in a timely manner.

[0003] In existing technologies, instruments can be used to weigh or detect chain breaks at the coal feeder to determine if coal blockage has occurred, but these typically only provide alarms. However, due to the harsh environment near the coal feeder and the high conductivity of dust, these instruments frequently make false judgments and are often abandoned after long-term use. Currently, coal blockage is mostly diagnosed manually, followed by on-site intervention. Specifically, manual intervention involves switching the coal feeder and performing vibration and purging, but this does not guarantee production stability and requires a high level of experience and responsibility from the operators. Failure to detect blockage in time can lead to excessively high coal bunker temperatures and a risk of spontaneous combustion. To mitigate this risk, excessive cold air is often added manually, resulting in significant boiler heat loss. Other methods involve programmed intervention after a blockage occurs, such as adjusting the inlet airflow and reducing the coal feed rate. However, these are mostly emergency measures after an accident, and diagnostic errors reduce the timeliness and accuracy of emergency responses. Sometimes, misjudgments can even disrupt normal on-site operations. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for preventing coal blockage in pulverized coal boilers. This method can detect coal blockage before it occurs, allowing for more timely intervention and resolution, effectively preventing coal blockage and reducing the frequency of manual intervention, thereby improving the operational stability and safety of pulverized coal boilers.

[0005] The present invention provides a method for preventing coal blockage in a pulverized coal boiler, comprising:

[0006] Collect the main steam flow rate and pressure of the pulverized coal boiler, the operating status of the coal feeder, the target flow rate and the instantaneous flow rate, and the outlet temperature of the mill;

[0007] If the fluctuations of the main steam flow rate and the main steam pressure are within a preset fluctuation threshold within a preset acquisition period, and the coal feeder is in operation, and the target flow rate has not changed, and the instantaneous flow rate is lower than the target flow rate by a first preset deviation threshold for a preset time threshold, or the instantaneous flow rate is lower than the previous acquisition period by a second preset deviation threshold, then a coal blockage alarm will be triggered until the triggering conditions disappear and the alarm will stop.

[0008] When a coal blockage alarm is triggered, the coal bunker should be vibrated until the alarm stops.

[0009] When the outlet temperature of the mill is higher than the preset temperature threshold, the opening of the hot air valve is reduced and the opening of the cold air valve is increased until the coal blockage is resolved and the initial opening is restored.

[0010] Preferably, the above-mentioned method for preventing coal blockage in pulverized coal boilers further includes:

[0011] When the coal blockage alarm is ineffective, manual intervention is required.

[0012] Preferably, the above-mentioned method for preventing coal blockage in pulverized coal boilers further includes:

[0013] When manual intervention is ineffective, the coal feeder is switched.

[0014] Preferably, in the above-mentioned method for preventing coal blockage in pulverized coal boilers, the step of vibrating the coal bunker includes:

[0015] A single vibration lasts for a first time, followed by a second time interval, and this vibration cycle continues for a third time.

[0016] If coal blockage persists, restart the rapping cycle.

[0017] Preferably, in the above-mentioned method for preventing coal blockage in pulverized coal boilers, the first time is 0.5 seconds to 1 second, the second time is 0.5 seconds to 1 second, and the third time is 3 seconds to 5 seconds.

[0018] Preferably, in the above-mentioned method for preventing coal blockage in pulverized coal boilers, the preset acquisition period is 20 to 40 seconds, and the preset fluctuation threshold is 0.5% to 1.5%.

[0019] Preferably, in the above-mentioned method for preventing coal blockage in pulverized coal boilers, the first preset deviation threshold is 25% to 50% of the target flow rate, and the preset time threshold is 5 to 10 seconds.

[0020] Preferably, in the above-mentioned method for preventing coal blockage in pulverized coal boilers, the second preset deviation threshold is 25% to 50% of the target flow rate.

[0021] Preferably, in the above-mentioned method for preventing coal blockage in pulverized coal boilers, the preset temperature threshold is 70°C to 75°C.

[0022] Preferably, in the above-mentioned method for preventing coal blockage in pulverized coal boilers, a vibrating motor located below the coal bunker is used to vibrate the coal bunker.

[0023] As described above, the coal blockage prevention method for pulverized coal boilers provided by the present invention includes collecting the main steam flow rate and main steam pressure of the pulverized coal boiler, the operating status of the coal feeder, the target flow rate and instantaneous flow rate, and the mill outlet temperature; when the fluctuations of the main steam flow rate and the main steam pressure are within a preset fluctuation threshold within a preset collection period, and the coal feeder is in operation, and the target flow rate has not changed, and the instantaneous flow rate is lower than the target flow rate by a first preset deviation threshold for a preset time threshold, or the instantaneous flow rate... If the coal blockage alarm is triggered when the temperature drops below the second preset deviation threshold compared to the previous data collection cycle, the alarm will stop when the triggering condition disappears. When a coal blockage alarm is triggered, the coal bunker will be vibrated until the alarm stops. When the outlet temperature of the mill is higher than the preset temperature threshold, the opening of the hot air valve will be reduced and the opening of the cold air valve will be increased until the coal blockage is resolved and the valve returns to its initial opening. Therefore, it is possible to make a judgment in advance before the coal blockage occurs, and to intervene and resolve the problem more promptly. This effectively prevents coal blockage and reduces the frequency of manual intervention, thereby improving the operational stability and safety of the pulverized coal boiler. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of an embodiment of a coal-blocking prevention method for a pulverized coal boiler provided by the present invention. Detailed Implementation

[0026] The core of this invention is to provide a method for preventing coal blockage in pulverized coal boilers. This method can detect coal blockage before it occurs, allowing for more timely intervention and resolution, effectively preventing coal blockage and reducing the frequency of manual intervention, thereby improving the operational stability and safety of pulverized coal boilers.

[0027] 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.

[0028] An example implementation of the anti-coal blockage method for a pulverized coal boiler provided by this invention. Figure 1 As shown, Figure 1 This is a schematic diagram of an embodiment of a method for preventing coal blockage in a pulverized coal boiler provided by the present invention. The method may include the following steps:

[0029] S1: Collect the main steam flow and pressure of the pulverized coal boiler, the operating status of the coal feeder, the target flow value and instantaneous flow value, and the outlet temperature of the mill;

[0030] It should be noted that pulverized coal is transported to the mill by the coal feeder, ground by the mill, and then blown into the pulverized coal boiler by the primary air fan for combustion. Before coal blockage occurs, the above parameters will change, which can provide a precursory basis for predicting coal blockage. Taking measures when coal blockage is about to occur but has not yet occurred can avoid adverse consequences.

[0031] S2: When the fluctuations of the main steam flow and main steam pressure within the preset fluctuation threshold within the preset acquisition period, and the coal feeder is in operation, and the target flow value has not changed, and the instantaneous flow value is lower than the target flow value by the first preset deviation threshold for a continuous preset time threshold, or the instantaneous flow value is lower than the previous acquisition period by the second preset deviation threshold, then a coal blockage alarm will be triggered until the triggering condition disappears and the alarm will stop.

[0032] It should be noted that when most parameters are stable, a sudden drop in the instantaneous flow rate indicates coal accumulation in some areas. This foreshadows an impending coal blockage if no action is taken. Therefore, issuing a coal blockage alarm to alert operators is a cost-effective and proactive approach that avoids adverse consequences, making it safer and more efficient than the previous method of taking action only after a blockage occurs. The preset data acquisition period is preferably 20 to 40 seconds, more preferably 30 seconds, and the preset fluctuation threshold is preferably 0.5% to 1.5%, more preferably 1%. Furthermore, the first preset deviation threshold is 25% to 50% of the target flow rate, the preset time threshold is 5 to 10 seconds, and the second preset deviation threshold is preferably 25% to 50% of the target flow rate. Of course, these parameters can be adjusted according to actual needs, and are not limited here.

[0033] S3: When a coal blockage alarm is triggered, the coal bunker will be vibrated until the alarm stops.

[0034] It should be noted that vibrating the coal bunker can dislodge the coal adhering to the inner wall, thereby restoring the instantaneous flow of coal and stopping the alarm. Preferably, the vibration motor below the coal bunker can be used to vibrate it, achieving automatic vibration without manual intervention and saving labor costs. Of course, other vibration methods can be selected according to actual needs; there are no restrictions here.

[0035] S4: When the outlet temperature of the mill is higher than the preset temperature threshold, reduce the opening of the hot air valve and increase the opening of the cold air valve until the coal blockage is stopped, and then restore it to the initial opening.

[0036] It should be noted that if a coal blockage occurs, the mill outlet temperature will rise. When it reaches the preset temperature threshold, intervention is required. Specifically, after a coal blockage alarm is triggered, an interlock signal is activated. The program controls the hot air valve to rapidly decrease its opening (DV1) and the cold air valve to increase its opening (DV2), correspondingly reducing the air intake and lowering the hot air density in advance. Simultaneously, the temperature and airflow are automatically monitored and adjusted. Once the coal blockage is resolved, the openings of the hot and cold air valves are reduced to their initial values ​​and automatically adjusted. The preset temperature threshold can preferably be between 70℃ and 75℃, but other temperature thresholds can be selected based on actual needs; there are no restrictions here.

[0037] As described above, in the embodiments of the anti-coal blockage method for pulverized coal boilers provided by the present invention, the method includes collecting the main steam flow rate and pressure of the pulverized coal boiler, the operating status of the coal feeder, the target flow rate and instantaneous flow rate, and the outlet temperature of the mill. When the fluctuations in the main steam flow rate and pressure are within a preset fluctuation threshold within a preset collection period, and the coal feeder is in operation, the target flow rate has not changed, and the instantaneous flow rate is lower than the target flow rate by a first preset deviation threshold for a continuous preset time threshold, or the instantaneous flow rate is lower than the previous collection period by a second preset deviation threshold, a coal blockage alarm is triggered until the triggering condition disappears and the alarm stops. During a coal blockage alarm, the coal bunker is vibrated until the alarm stops. When the outlet temperature of the mill is higher than a preset temperature threshold, the opening of the hot air valve is reduced and the opening of the cold air valve is increased until coal blockage ceases and the opening is restored to its initial value. Therefore, the method can make early judgments before coal blockage occurs, allowing for more timely intervention and resolution, effectively preventing coal blockage, reducing the frequency of manual intervention, and improving the operational stability and safety of the pulverized coal boiler.

[0038] In a specific embodiment of the above-mentioned method for preventing coal blockage in pulverized coal boilers, the following steps may also be included:

[0039] When the coal blockage alarm is ineffective, manual intervention is required.

[0040] Specifically, if the abnormal handling fails multiple times, manual intervention can be initiated. The hot and cold air valves will maintain the target opening degree after interlocking, and the operation authority will be handed over to manual processing.

[0041] In another specific embodiment of the above-mentioned method for preventing coal blockage in pulverized coal boilers, the following steps may also be included:

[0042] When manual intervention is ineffective, the coal feeder is switched. This replaces the coal feeder that has become clogged with a coal feeder that is not clogged, thus resolving the coal blockage problem.

[0043] In another specific embodiment of the above-mentioned method for preventing coal blockage in pulverized coal boilers, vibrating the coal bunker may include the following steps:

[0044] A single vibration lasts for a first time, followed by a second time interval, and this vibration cycle continues for a third time.

[0045] If coal blockage persists, restart the rapping cycle.

[0046] Specifically, the first time interval can be preferably 0.5 to 1 second, the second time interval can be preferably 0.5 to 1 second, and the third time interval can be preferably 3 to 5 seconds. In one example, when dealing with coal blockage, high-frequency vibration is used, with a single vibration time of 1 second, a vibration interval of 0.5 seconds, and a duration of 3 seconds. Then, it is determined whether the coal blockage still exists. If the coal blockage condition still exists, the vibration is restarted. After vibration 3 times, the operator can be reminded to deal with it in time.

[0047] In summary, the above-mentioned methods for preventing coal blockage in pulverized coal boilers have the following advantages: high reliability of judgment, more accurate than traditional mechanical flow switches and other instruments, and does not rely on complete coal cut-off as the basis for judgment, thus providing a certain advantage in advance judgment; safe and reliable abnormal handling methods, employing high-frequency and multiple control methods, which can effectively solve coal blockage and reduce the risk of equipment falling off due to vibration; effective emergency handling methods, reducing air volume and hot air blending ratio when coal blockage occurs, which can effectively prevent excessive temperature caused by coal blockage; and high degree of automation, which can effectively reduce the frequency of manual intervention and improve the stability of boiler operation.

[0048] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preventing coal blockage in a pulverized coal boiler, characterized in that, include: Collect the main steam flow rate and pressure of the pulverized coal boiler, the operating status of the coal feeder, the target flow rate and the instantaneous flow rate, and the outlet temperature of the mill; When the fluctuations of the main steam flow rate and the main steam pressure are within a preset fluctuation threshold within a preset acquisition period, and the coal feeder is in operation, and the target flow rate has not changed, and the instantaneous flow rate is lower than the target flow rate by a first preset deviation threshold for a preset time threshold, or the instantaneous flow rate is lower than the previous acquisition period by a second preset deviation threshold, a coal blockage alarm is triggered until the triggering conditions disappear. The preset acquisition period is 20 to 40 seconds, the preset fluctuation threshold is 0.5% to 1.5%, the first preset deviation threshold is 25% to 50% of the target flow rate, the preset time threshold is 5 to 10 seconds, and the second preset deviation threshold is 25% to 50% of the target flow rate. When a coal blockage alarm is triggered, the rapping motor below the coal bunker is used to vibrate the coal bunker until the alarm stops. When the outlet temperature of the mill is higher than the preset temperature threshold, the opening of the hot air valve is reduced and the opening of the cold air valve is increased until the coal blockage is stopped, and then the initial opening is restored. The preset temperature threshold is 70°C to 75°C.

2. The method for preventing coal blockage in a pulverized coal boiler according to claim 1, characterized in that, Also includes: When the coal blockage alarm is ineffective, manual intervention is required.

3. The method for preventing coal blockage in a pulverized coal boiler according to claim 2, characterized in that, Also includes: When manual intervention is ineffective, the coal feeder is switched.

4. The method for preventing coal blockage in a pulverized coal boiler according to claim 3, characterized in that, The vibration of the coal bunker includes: A single vibration lasts for a first time, followed by a second time interval, and this vibration cycle continues for a third time. If coal blockage persists, restart the rapping cycle.

5. The method for preventing coal blockage in a pulverized coal boiler according to claim 4, characterized in that, The first time is 0.5 seconds to 1 second, the second time is 0.5 seconds to 1 second, and the third time is 3 seconds to 5 seconds.

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