Fuel control method for coal mill of pulverized coal furnace generator set

Abstract

The invention relates to the technical field of automatic control, in particular to a fuel control method for a coal mill of a pulverized coal furnace generator set. The method comprises the following steps that S1, the total air volume of an outlet of a primary fan is adjusted; s2, calculating a total primary air volume automatic instruction; s3, according to the total primary air volume control, the air volume deviation of each mill and the pressure of a main pipe are adjusted; and S4, after the coal type of unit fire coal is recovered, the control of the primary fan and the hot air door of the mill is recovered. According to the fuel control method for the coal mills of the pulverized coal furnace generator set, the total outlet air volume of the primary air fan is controlled, the total pulverized coal amount requirement that all the coal mills carry pulverized coal to participate in combustion is met, and the requirement for rapid peak and frequency regulation of machine-furnace coordinated control of the pulverized coal furnace generator set is met; therefore, the coordination control variable load capacity of the unit is integrally improved, the peak regulation and frequency modulation requirements of a current novel power system under the vigorous development of new energy are met, and meanwhile the adaptability and economical efficiency of the pulverized coal furnace generator set running under various coal-fired blending combustion working conditions are improved.

Description

Technical Field

[0001] The present invention relates to the field of automatic control technology, and in particular to a fuel control method for a coal mill of a pulverized coal furnace generator set. Background Art

[0002] In recent years, the supply and demand relationship in the domestic power industry has undergone major changes, and the power supply is facing a shortage. Traditional thermal power plants have taken advantage of the opportunity of the recovery of the annual power generation rate of the units to increase power generation, but are faced with the dilemma of rising coal prices and shortages. Therefore, thermal power plants have tried their best to blend low-priced coal, and many areas mainly blend lignite.

[0003] Blended coal combustion is often not the designed operating condition for thermal power units, resulting in slow load regulation, impacting the grid's peak and frequency regulation, and drawing scrutiny from dispatching authorities. Analysis revealed that the primary damper regulating the pulverizers was largely open due to the high moisture content and impurities in the blended coal. This caused the original design, which relied on mill hot air volume to control the amount of pulverized coal entering the furnace, to lose control. Consequently, the coordinated control of the mill and boiler, which regulates the unit's load, failed to operate properly and reliably, severely impacting the unit's load regulation capabilities.

[0004] For example, patent (CN111142377B) discloses a fuel quantity feedforward control method for a coordinated control system taking into account the operating status of the coal mill, which includes: for all coal mills with automatic coal feeding, respectively selecting a representative value of the ratio of each coal mill current to the coal mill feeding amount, a representative value of the ratio of the primary air pressure to the coal mill feeding amount, and a representative value of the coal mill feeding amount; wherein, selecting a representative value of the ratio of each coal mill current to the coal mill feeding amount is specifically: selecting the representative value of the ratio of each coal mill current to the coal mill feeding amount The second largest value of the ratio of the primary air pressure to the coal feeding amount of each coal mill is selected as the representative value; the representative value of the ratio of the primary air pressure to the coal feeding amount of each coal mill is selected, specifically: the second largest value of the coal feeding amount of each coal mill is selected as the representative value; the inertia time of the actual differential control effect of the AGC instruction corresponding to each of the above representative values ​​on the fuel amount feedforward link is calculated respectively, and the maximum value among them is selected as the inertia time of the final actual differential link time; after obtaining the inertia time of the actual differential link, it also includes the following process: the inertia time of the pulverizing system is divided by the inertia time of the actual differential link and then subtracted from 1 to obtain an intermediate coefficient; the actual AGC command signal of the unit is divided by the value of the static gain of the fuel amount to the power generation power to obtain a static fuel amount feedforward signal; the static fuel amount feedforward signal is subtracted from the static fuel amount feedforward signal through the inertia time set as the signal output by the first-order inertia module of the differential link inertia time, and then multiplied by the intermediate coefficient to obtain a value plus the static fuel amount feedforward signal to obtain the AGC command feedforward signal of the fuel amount. The fuel amount feedforward control method of the coordinated control system taking into account the operating status of the coal mill of the present invention is particularly suitable for thermal power units with complex coal quality and frequent fluctuations in AGC commands. The control system can coordinate the contradiction between the control quality of the steam pressure before the turbine and the operating safety of the pulverizing system during the load change process, maximize the ultimate performance of the equipment, and ensure that the best control effect is obtained under the premise that the pulverizing system does not fail.

[0005] There is an urgent need to study a solution to the problem of the unit coordination control not being able to be put into normal use caused by co-firing, so as to meet the current higher requirements of deep peak regulation and rapid frequency regulation of thermal power units and absorb more new energy power generation construction status.

[0006] Therefore, a fuel control method for a coal mill of a pulverized coal furnace generator set is designed to provide a technical solution to the above technical problems. Summary of the Invention

[0007] Based on this, it is necessary to provide a fuel control method for the pulverized coal furnace generator set pulverizer in response to the above technical problems, which is used to solve the design operating condition deviation that occurs after the current pulverized coal furnace generator set is mixed and burned, and the hot primary air damper of the pulverizer cannot follow the fuel control system to quickly adjust the combustion rate of the boiler near the fully open position, which seriously affects the automatic control and commissioning of the unit boiler load.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions: A fuel control method for a coal mill of a pulverized coal furnace generator set comprises the following steps: S1: Adjust the total air volume at the outlet of the primary fan; S2: Automatic instruction to calculate total primary air volume; S3: According to the total primary air volume control, adjust the air volume deviation of each mill and the main pipe pressure; S4: After the coal type of the unit is restored, the control of the hot air door of the primary fan and mill is restored.

[0009] As a preferred embodiment of the fuel control method for a pulverized coal furnace generator set provided by the present invention, in step S1, the total air volume at the outlet of the primary fan is adjusted as follows: Through the distribution control of the primary fan of the unit, the general PID module is used to realize the follow-up coal quantity instruction control of the total primary air volume of the pulverizer. The expression is: ; in, is the final set value of the total primary air volume, is the total primary air volume, It is the deviation input value of air volume PID; ; in, It is the total primary air volume automatic instruction. It is the set value of total primary air volume offset.

[0010] As a preferred embodiment of the fuel control method for a pulverized coal furnace generator set provided by the present invention, in step S2, the total primary air volume automatic instruction is calculated, and the expression is as follows: ; in, is the number of coal mill systems included in the unit; The operating status of coal feeder i, the operating value is 1, and the non-operating value is 0; is the coal feeding quantity instruction of coal feeder i; The coal feeding instruction of mill i-the primary air volume function curve of mill i.

[0011] As a preferred embodiment of the fuel control method for a pulverized coal furnace generator set provided by the present invention, in step S3, the air volume deviation of each mill and the main pipe pressure are adjusted according to the total primary air volume control, and the steps are as follows: When the total primary air volume control is put into operation, the primary air volume control of each coal mill is cut off simultaneously; The operator shall fine-tune the air volume deviation of the corresponding mill through the hot air door of the mill; The operating personnel will fine-tune the main pipe pressure of the primary air through the hot air door of the corresponding mill.

[0012] As a preferred implementation of the fuel control method for a pulverized coal furnace generator set provided by the present invention, in step S4, after the coal type of the unit returns to the designed operating conditions, the hot air door control of the primary fan and the mill is restored to the original designed automatic control mode.

[0013] It can be seen without a doubt that the above-mentioned technical solution of this application can definitely solve the technical problem to be solved by this application.

[0014] At the same time, through the above technical solutions, the present invention has at least the following beneficial effects: 1. The present invention provides a fuel control method for a coal mill of a pulverized coal furnace generator set, which controls the total outlet air volume of the primary fan to meet the total coal powder amount required for each coal mill to carry coal powder for combustion, thereby realizing the requirements of rapid peak and frequency regulation of the coordinated control of the machine and boiler of the pulverized coal furnace generator set.

[0015] 2. The present invention can adjust the total air volume at the outlet of the primary fan to meet the proportional following fuel instruction of the pulverized coal carried by the primary air into the furnace, thereby improving the speed and linearity of the boiler combustion response, thereby improving the overall coordinated control and variable load capacity of the unit, meeting the peak and frequency regulation needs of the current new power system under the vigorous development of new energy, and at the same time improving the adaptability and economy of the pulverized coal furnace generator set operating under various coal-blended combustion conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is a block diagram of the total primary air volume instruction calculation of the present invention; Figure 2 This is the total primary air volume PID control block diagram of the present invention; Figure 3 This is the primary air volume switching control block diagram of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0020] As described in the background technology, there is an urgent need to study a method to solve the problem of the unit coordination control not being able to be put into normal use due to co-firing, so as to meet the current higher requirements of deep peak regulation and rapid frequency regulation of thermal power units and absorb more new energy power generation construction status.

[0021] In order to solve this technical problem, the present invention provides a fuel control method for a coal mill of a pulverized coal furnace generator set.

[0022] Specifically, please refer to Figure 1-Figure 3 , the fuel control method, the steps are as follows: S1: Adjust the total air volume at the outlet of the primary fan; S2: Automatic instruction to calculate total primary air volume; S3: According to the total primary air volume control, adjust the air volume deviation of each mill and the main pipe pressure; S4: After the coal type of the unit is restored, the control of the hot air door of the primary fan and mill is restored.

[0023] The present invention provides a fuel control method for a pulverized coal furnace generator set pulverizer, which controls the total outlet air volume of the primary fan to meet the total pulverized coal amount demand of each pulverizer for carrying pulverized coal to participate in combustion, and realizes the requirements of rapid peak-shaving and frequency regulation of the coordinated control of the machine and boiler of the pulverized coal furnace generator set. The total outlet air volume of the primary fan can be adjusted to meet the proportional follow-up fuel instruction of the pulverized coal carried by the primary air into the furnace, thereby improving the speed and linearity of the boiler combustion response, thereby improving the overall coordinated control variable load capacity of the unit, meeting the peak-shaving and frequency regulation requirements of the current new power system under the vigorous development of new energy, and at the same time improving the adaptability and economy of the pulverized coal furnace generator set operating in various coal-blended combustion conditions.

[0024] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features and technical solutions therein may be combined with each other.

[0025] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition or explanation in subsequent drawings.

[0026] Example 1 Reference Figure 1-Figure 3 , a fuel control method for a coal mill of a pulverized coal furnace generator set.

[0027] The pulverized coal furnace generator set uses a primary fan to control the total primary air volume entering the pulverizer to meet the total primary air volume instruction setting requirements, replacing the control failure of the pulverizer primary air volume control damper close to the fully open position caused by the blending of non-design coal types. The resulting large inertia and large delay characteristics of the unit's fuel control are significantly enhanced, affecting the unit's coordinated control and inability to be put into high-quality use.

[0028] The implementation steps are as follows: S1: Through the distribution control of the primary fan of the unit, the general PID module is used to realize the follow-up coal quantity instruction control of the total primary air volume of the pulverizer. The expression is: ; in, is the final set value of the total primary air volume, is the total primary air volume, It is the deviation input value of air volume PID; ; in, It is the total primary air volume automatic instruction. It is the total primary air volume offset setting value; S2: The calculation expression of the total primary air volume automatic instruction is: ; in, is the number of coal mill systems included in the unit; The operating status of coal feeder i, the operating value is 1, and the non-operating value is 0; is the coal feeding quantity instruction of coal feeder i; The coal feeding instruction of mill i is the primary air volume function curve of mill i; S3: When the total primary air volume control is activated, the original primary air volume control of each coal mill is cut off. The air volume deviation of each mill is fine-tuned by the operator through the hot air door of the mill, and the main pipe pressure of the primary air is also fine-tuned by the operator through the hot air door of each mill; S4: After the unit's coal type returns to the designed operating conditions, the hot air door control of the primary fan and mill can be restored to the original designed automatic control mode.

[0029] The specific working principle of the fuel control method for a pulverized coal furnace generator set provided by the present invention is as follows: When in use, firstly, through the distribution control of the primary air fan of the unit, the universal PID module is used to realize the follow-up coal volume instruction control of the total primary air volume of the coal mill, and the total primary air volume automatic instruction is calculated. At the same time, after the calculation is completed, while the total primary air volume control is put into operation, the original primary air volume control of each coal mill is cut off, and the air volume deviation of each mill is fine-tuned by the operating personnel through the hot air door of the mill, and the main pipe pressure of the primary air is fine-tuned by the operating personnel through the hot air door of each mill; then after the coal type of the unit is restored to the designed operating conditions, the hot air door control of the primary fan and the mill can be restored to the original designed automatic control mode.

[0030] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A fuel control method for a coal mill of a pulverized coal furnace generator set, characterized in that: Here are the steps: S1: Adjust the total air volume at the outlet of the primary fan; S2: Automatic instruction to calculate total primary air volume; S3: According to the total primary air volume control, adjust the air volume deviation of each mill and the main pipe pressure; S4: After the coal type of the unit is restored, the control of the hot air door of the primary fan and mill is restored.

2. The fuel control method for a coal mill of a pulverized coal furnace generator set according to claim 1, characterized in that: In step S1, adjust the total air volume at the primary fan outlet as follows: Through the distribution control of the primary fan of the unit, the general PID module is used to realize the follow-up coal quantity instruction control of the total primary air volume of the pulverizer. The expression is: ； in, is the final set value of the total primary air volume, is the total primary air volume, It is the deviation input value of air volume PID; ； in, It is the total primary air volume automatic instruction. It is the set value of total primary air volume offset.

3. The fuel control method for a coal mill of a pulverized coal furnace generator set according to claim 1, characterized in that: In step S2, the total primary air volume automatic instruction is calculated, and the expression is as follows: ； in, is the number of coal mill systems included in the unit; The operating status of coal feeder i, the operating value is 1, and the non-operating value is 0; is the coal feeding quantity instruction of coal feeder i; The coal feeding instruction of mill i-the primary air volume function curve of mill i.

4. The fuel control method for a coal mill of a pulverized coal furnace generator set according to claim 1, characterized in that: In step S3, the air volume deviation of each mill and the main pipe pressure are adjusted according to the total primary air volume control. The steps are as follows: When the total primary air volume control is put into operation, the primary air volume control of each coal mill is cut off simultaneously; The operator shall fine-tune the air volume deviation of the corresponding mill through the hot air door of the mill; The operating personnel will fine-tune the main pipe pressure of the primary air through the hot air door of the corresponding mill.

5. The fuel control method for a coal mill of a pulverized coal furnace generator set according to claim 1, characterized in that: In step S4, after the coal type of the unit returns to the designed operating conditions, the hot air door control of the primary fan and the mill returns to the original designed automatic control mode.

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