Automatic control method for preventing primary air duct blockage in pulverized coal boilers of thermal power plants

Abstract

The present invention relates to an automatic control method for preventing the primary air duct from being blocked in a pulverized coal boiler in a thermal power plant. The method mainly solves the technical problem that the existing method of judging whether the primary air duct is blocked by the operator's experience has a hysteresis and is difficult to detect the blockage of the primary air duct in the initial stage. Step 1: Real-time monitoring of the primary air pressure value and its duration on the primary air duct of the powder feeder, the outlet air pressure value and its duration at the outlet of the powder discharger, and the operating status of the powder feeder; Step 2: Calculate the variation amplitude and average value of the primary air pressure value based on the obtained primary air pressure value; Step 3: Control the powder feeder based on the obtained primary air pressure value and its duration, the variation amplitude and average value of the primary air pressure value, the outlet air pressure value and its duration, and the operating status of the powder feeder to prevent the primary air duct from being blocked.

Description

Technical Field

[0001] The present invention relates to a control method and system for preventing air duct blockage, and in particular to an automatic control method for preventing primary air duct blockage of a pulverized coal boiler in a thermal power plant and a system for implementing the method. Background Art

[0002] In the boiler of a large coal-fired power generation unit that adopts an intermediate storage bin type exhaust gas pulverized coal feeding and pulverizing system, during normal operation, the pulverized coal in the pulverized coal bin is fed into the furnace through the primary air duct by the pulverizer feeder and the exhaust gas of the pulverizing system for combustion. Since the blockage of the primary air duct can easily cause the air duct to catch fire, which poses a great threat to the safe operation of the boiler unit, it is necessary to monitor the air pressure changes in the primary air duct to determine the amount of pulverized coal in the primary air duct and thus determine whether the primary air duct is blocked so that timely treatment can be carried out to prevent safety accidents.

[0003] The existing method of determining whether a primary air duct is blocked usually relies on the operator's experience, which has a lag and is difficult to detect in time at the initial stage of primary air duct blockage. Summary of the Invention

[0004] The purpose of the present invention is to solve the technical problem that the existing method of judging whether the primary air duct is blocked by relying on the operator's experience has a lag and is difficult to detect the blockage of the primary air duct in the initial stage in time, and to provide an automatic control method and system for preventing the blockage of the primary air duct of a pulverized coal boiler in a thermal power plant.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] An automatic control method for preventing blockage of a primary air duct of a pulverized coal boiler in a thermal power plant is characterized in that it comprises the following steps:

[0007] Step 1: Real-time monitoring of the primary air pressure value and its duration on the primary air duct of the powder feeder, the outlet air pressure value and its duration at the outlet of the powder discharger, and the operating status of the powder feeder;

[0008] Step 2: Calculate the variation amplitude and average value of the primary wind pressure value obtained;

[0009] Step 3: Based on the acquired primary wind pressure value and its duration, the change amplitude and average value of the primary wind pressure value, the outlet wind pressure value and its duration, and the powder feeder operating status, perform the following processing:

[0010] 1) The powder feeder is not in operation. If the obtained primary air pressure value is lower than the preset starting air pressure value, the powder feeder is prohibited from starting;

[0011] 2) After the powder feeder is started and in operation, if the obtained primary air pressure is within the preset fluctuation range, the powder feeder is kept in normal operation; otherwise, execute 3);

[0012] 3) If the obtained primary wind pressure value is less than the first preset wind pressure value and lasts for more than the first preset time; or if the obtained primary wind pressure value is greater than the second preset wind pressure value and lasts for more than the first preset time; the speed of the powder feeder is reduced to the preset speed, and the speed control of the powder feeder is adjusted to manual control, and an abnormal wind pressure alarm is issued at the same time;

[0013] If the obtained primary wind pressure value is less than the first preset wind pressure value and lasts for more than the second preset time; or the obtained primary wind pressure value is greater than the second preset wind pressure value and lasts for more than the second preset time; at the same time, the obtained outlet wind pressure value is greater than the third preset wind pressure value and lasts for more than the second preset time; the powder feeder will be shut down and an abnormal wind pressure alarm will be issued;

[0014] If the change amplitude of the acquired primary air pressure value within the first preset time is less than the preset change value, and the acquired outlet air pressure value is greater than the third preset air pressure value and lasts for more than the second preset time, the powder feeder will be shut down and an abnormal air pressure alarm will be issued;

[0015] If the average value of the primary air pressure obtained within the first preset time is less than the first preset average value, or the average value within the first preset time is greater than the second preset average value, the pulverized coal feeder is controlled to issue an abnormal primary air pressure alarm; thereby completing the automatic control of the pulverized coal boiler in the thermal power plant to prevent the primary air duct from being blocked.

[0016] Further, in step three: the preset starting wind pressure value is 0.1kPa~0.2kPa, the first preset wind pressure value is 0.2kPa~0.3kPa, the first preset time is 15 seconds~25 seconds, the second preset wind pressure value is 1.5kPa~2.5kPa, the preset speed is 200r / min~400r / min, the second preset time is 25 seconds~35 seconds, the third preset wind pressure value is 0.3kPa~0.4kPa, the preset fluctuation range is 0.9kPa~1.3kPa, the preset change value is 0.09kPa~0.13kPa, the first preset average value is 0.6kPa~0.9kPa, and the second preset average value is 1.3kPa~1.8kPa.

[0017] Further, in step three: the preset starting wind pressure value is 0.1kPa, the first preset wind pressure value is 0.2kPa, the first preset time is 20 seconds, the second preset wind pressure value is 2kPa, the preset speed is 300r / min, the second preset time is 30 seconds, the third preset wind pressure value is 0.35kPa, the preset change value is 0.1kPa, the first preset average value is 0.75kPa, and the second preset average value is 1.5kPa.

[0018] At the same time, the present invention also provides an automatic control system for preventing primary air duct blockage of a pulverized coal boiler in a thermal power plant, which is used to implement an automatic control method for preventing primary air duct blockage of a pulverized coal boiler in a thermal power plant, comprising multiple air pressure testers and a processor;

[0019] The plurality of wind pressure testers are respectively arranged at the primary air duct of the powder feeder and the air outlet of the powder discharger to monitor the primary air pressure value on the primary air duct of the powder feeder and the outlet air pressure value at the outlet of the powder discharger in real time;

[0020] The plurality of wind pressure testers are electrically connected to a processor respectively, and the processor is electrically connected to the powder feeder for controlling the start and stop of the powder feeder, speed change, primary wind pressure abnormality alarm and speed regulation mode switching.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention monitors the air pressure values ​​at the primary air duct of the powder feeder and the outlet of the powder discharger in real time, monitors the size, duration, and variation range of the air pressure value of the primary air duct, and the size and duration of the air pressure value at the outlet, and automatically determines whether the primary air duct is blocked in combination with the operating state of the powder feeder, the size, duration, and variation range of the air pressure value of the primary air duct and / or the size and duration of the air pressure value at the outlet, and automatically controls the start and stop of the powder feeder, speed change, primary air pressure abnormality alarm, and speed adjustment mode switching, so that blockage of the primary air duct can be discovered in time in the initial stage, solving the problem of serious blockage of the primary air duct caused by lag in manual judgment, which easily leads to safety accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the logic of step 3 of the embodiment of the automatic control method for preventing the primary air duct from being blocked in a pulverized coal boiler of a thermal power plant of the present invention. Figure 1 ;

[0024] Figure 2 This is the logic of step 3 of the embodiment of the automatic control method for preventing the primary air duct from being blocked in a pulverized coal boiler of a thermal power plant of the present invention. Figure 2 ;

[0025] Figure 3This is the logic of step 3 of the embodiment of the automatic control method for preventing the primary air duct from being blocked in a pulverized coal boiler of a thermal power plant of the present invention. Figure 3 . DETAILED DESCRIPTION

[0026] In order to make the purpose, advantages and features of the present invention clearer, the following is a further detailed description of the automatic control method and system for preventing the blockage of the primary air duct of a pulverized coal boiler in a thermal power plant proposed by the present invention in combination with the accompanying drawings and specific embodiments. According to the following specific embodiments, the advantages and features of the present invention will become clearer. It should be noted that: the drawings are all in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention; secondly, the structures shown in the drawings are often part of the actual structure.

[0027] The present invention discloses an automatic control system for preventing blockage of a primary air duct of a pulverized coal boiler in a thermal power plant, comprising a plurality of air pressure testers and a processor; the plurality of air pressure testers are respectively used to be arranged at the primary air duct of a pulverized coal feeder and the air outlet of a pulverized coal discharger, and to monitor in real time the primary air pressure value on the primary air duct of the pulverized coal feeder and the outlet air pressure value at the outlet of the pulverized coal discharger; the plurality of air pressure testers are respectively electrically connected to the processor, and the processor is electrically connected to the pulverized coal feeder, and is used to obtain the operating status of the pulverized coal feeder, and at the same time, control the start and stop of the pulverized coal feeder, the speed change, the primary air pressure abnormality alarm and / or the speed adjustment mode switching according to the primary air pressure value and / or the outlet air pressure value measured by the air pressure tester.

[0028] Based on the above-mentioned automatic control system for preventing primary air duct blockage of a pulverized coal boiler in a thermal power plant, this embodiment provides an automatic control method for preventing primary air duct blockage of a pulverized coal boiler in a thermal power plant, including the following steps:

[0029] Step 1: Real-time monitoring of the primary air pressure value and its duration on the primary air duct of the powder feeder, the outlet air pressure value and its duration at the outlet of the powder discharger, and the operating status of the powder feeder;

[0030] Step 2: Calculate the variation amplitude and average value of the primary wind pressure value obtained;

[0031] Step 3: Based on the acquired primary wind pressure value and its duration, the change amplitude and average value of the primary wind pressure value, the outlet wind pressure value and its duration, and the powder feeder operating status, perform the following processing:

[0032] 1) If Figure 1 As shown, the powder feeder is in a non-operating state. If the acquired primary air pressure value is less than the preset starting air pressure value, the processor prohibits starting the powder feeder. The preset starting air pressure value range is 0.1 kPa to 0.2 kPa. In this embodiment, it is preferably 0.1 kPa.

[0033] 2) The powder feeder is in operation. If the acquired primary air pressure value is within a preset fluctuation range, which in this embodiment is 0.9 to 1.3 kPa, the processor maintains the normal operation of the powder feeder; otherwise, the process proceeds to 3);

[0034] 3) If the acquired primary wind pressure value is less than the first preset wind pressure value and lasts for more than the first preset time, the first preset wind pressure value is 0.2kPa to 0.3kPa, the first preset time is 15 seconds to 25 seconds, and in this embodiment, the first preset wind pressure value is preferably 0.2kPa, and the first preset time is 20 seconds; or the acquired primary wind pressure value is greater than the second preset wind pressure value and lasts for more than the first preset time, the second preset wind pressure value is 1.5kPa to 2.5kPa, and in this embodiment, the second preset wind pressure value is preferably 2kPa; the processor automatically reduces the speed of the powder feeder to the preset speed, the preset speed is 200r / min to 400r / min, and in this embodiment, the preset speed is preferably 300r / min, and the speed control of the powder feeder is adjusted to manual control, and an abnormal wind pressure alarm is issued at the same time;

[0035] like Figure 2 As shown, if the obtained primary wind pressure value is less than the first preset wind pressure value and lasts for more than the second preset time, the second preset time is 25 seconds to 35 seconds, and in this embodiment, the second preset time is preferably 30 seconds; or the obtained primary wind pressure value is greater than the second preset wind pressure value and lasts for more than the second preset time; and the obtained outlet wind pressure value is greater than the third preset wind pressure value, the third preset wind pressure value is 0.3kPa to 0.4kPa, and in this embodiment, the third preset wind pressure value is preferably 0.35kPa, and lasts for more than the second preset time; then the processor will shut down the powder feeder and issue a primary wind pressure abnormality alarm;

[0036] like Figure 3 As shown, if the change amplitude of the acquired primary air pressure value within the first preset time is less than the preset change value, the preset change value is 0.09kPa to 0.13kPa, and in this embodiment, it is preferably 0.1kPa, and the acquired outlet air pressure value is greater than the third preset air pressure value and lasts for more than the second preset time, the processor shuts down the powder feeder and issues a primary air pressure abnormality alarm;

[0037] like Figure 3As shown, if the average value of the primary wind pressure value obtained within the first preset time is less than the first preset average value, the first preset average value is 0.6kPa~0.9kPa, in this embodiment, the first preset average value is preferably 0.75kPa, or the average value of the primary wind pressure within the first preset time is greater than the second preset average value, the second preset average value is 1.3kPa~1.8kPa, in this embodiment, the second preset average value is preferably 1.5kPa, then the processor controls the powder feeder to issue a primary wind pressure abnormality alarm; thereby completing the automatic control of the pulverized coal boiler in the thermal power plant to prevent the primary air duct from being blocked.

Claims

1. An automatic control method for preventing primary air duct blockage in a pulverized coal boiler in a thermal power plant, characterized in that: The following steps are involved: Step 1: Real-time monitoring of the primary air pressure value and its duration on the primary air duct of the powder feeder, the outlet air pressure value and its duration at the outlet of the powder discharger, and the operating status of the powder feeder; Step 2: Calculate the variation amplitude and average value of the primary wind pressure value obtained; Step 3: Based on the acquired primary wind pressure value and its duration, change amplitude and average value, outlet wind pressure value and its duration, and powder feeder operating status, perform the following processing: (1) The powder feeder is not in operation. If the obtained primary air pressure value is less than the preset starting air pressure value, the powder feeder is prohibited from starting; the preset starting air pressure value is 0.1kPa to 0.2kPa; (2) After the powder feeder is started, it is in the running state. If the obtained primary wind pressure is within the preset fluctuation range, the powder feeder is kept in normal operation, otherwise step (3) is executed; the preset fluctuation range is 0.9 kPa to 1.3 kPa; (3) If the obtained primary wind pressure value is less than the first preset wind pressure value and lasts for more than the first preset time; or if the obtained primary wind pressure value is greater than the second preset wind pressure value and lasts for more than the first preset time; then the speed of the powder feeder is reduced to the preset speed, the speed control of the powder feeder is adjusted to manual control, and an abnormal wind pressure alarm is issued at the same time; the first preset wind pressure value is 0.2kPa to 0.3kPa, the first preset time is 15 seconds to 25 seconds, the second preset wind pressure value is 1.5kPa to 2.5kPa, and the preset speed is 200r / min to 400r / min; If the primary wind pressure value obtained is less than the first preset wind pressure value and lasts for more than the second preset time, and the outlet wind pressure value obtained is greater than the third preset wind pressure value and lasts for more than the second preset time; or the primary wind pressure value obtained is greater than the second preset wind pressure value and lasts for more than the second preset time, and the outlet wind pressure value obtained is greater than the third preset wind pressure value and lasts for more than the second preset time; the powder feeder will be shut down and an abnormal wind pressure alarm will be issued; the second preset time is 25 seconds to 35 seconds, and the third preset wind pressure value is 0.3kPa to 0.4kPa; If the change amplitude of the primary air pressure value obtained within the first preset time is less than the preset change value, and the outlet air pressure value obtained is greater than the third preset air pressure value and lasts for more than the second preset time, the powder feeder will be shut down and an abnormal air pressure alarm will be issued; the preset change value is 0.09kPa to 0.13kPa; If the average value of the primary wind pressure obtained within the first preset time is less than the first preset average value, or the average value within the first preset time is greater than the second preset average value, the powder feeder is controlled to issue an abnormal primary wind pressure alarm; thereby completing the automatic control of the pulverized coal boiler in the thermal power plant to prevent the primary air duct from being blocked; the first preset average value is 0.6kPa~0.9kPa, and the second preset average value is 1.3kPa~1.8kPa.

2. The automatic control method for preventing primary air duct blockage of a pulverized coal boiler in a thermal power plant according to claim 1, characterized in that: In step three: The preset starting wind pressure value is 0.1kPa, the first preset wind pressure value is 0.2kPa, the first preset time is 20 seconds, the second preset wind pressure value is 2kPa, the preset speed is 300r / min, the second preset time is 30 seconds, the third preset wind pressure value is 0.35kPa, the preset change value is 0.1kPa, the first preset average value is 0.75kPa, and the second preset average value is 1.5kPa.

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