Thermal power generating unit operation control method and device, electronic equipment and readable storage medium

Abstract

The invention provides a thermal power generating unit operation control method and device, electronic equipment and a readable storage medium, and belongs to the technical field of thermal power generation control. The method comprises the steps of obtaining a current operation load rate of a thermal power generating unit; based on the current operation load rate, according to a preset relation table or a preset relation curve, the high-alkali coal blending proportion is determined, and the preset relation table or the preset relation curve is used for representing the corresponding relation between different operation load rates and the high-alkali coal blending proportion; and on the basis of the high-alkali coal blending proportion, an in-furnace raw coal switching system of the thermal power generating unit is controlled to adjust the input amount of high-alkali coal powder and low-alkali coal powder input into the boiler. According to the operation load rate of the thermal power generating unit, the blending proportion of the high-alkali coal in the pulverized coal needed for boiler combustion is determined, normal work of the boiler can be guaranteed, the slag bonding amount can be reduced, the use amount of the high-alkali coal can be increased, and the power generation cost is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal power generation control, and in particular to a method for controlling the operation of a thermal power unit, a device for controlling the operation of a thermal power unit, an electronic device and a readable storage medium. Background Art

[0002] my country's current energy structure dominated by coal will not change. Even in the foreseeable future, coal will still be my country's main source of energy and chemical raw material.

[0003] High-alkali coal has the characteristics of "two lows and four highs": low ash, low sulfur, medium-high moisture, high volatile matter, medium-high calorific value, and high alkali metal content; it is easy to ignite, easy to burn out, and environmentally friendly, and is a high-quality thermal coal; compared with other high-quality thermal coals, high-alkali coal has a high alkali metal content and has serious contamination and slagging characteristics, which seriously affect the safety, stability and economy of boiler operation. When the high-alkali coal blending ratio of most active units exceeds a certain value, the boiler heating surface quickly develops varying degrees of slagging, so they are forced to shut down and clean the boiler. Therefore, it is of great significance to study how to increase the blending ratio of high-alkali coal under the premise of safe blending.

[0004] At present, the methods for increasing the proportion of high-alkali coal blending in boilers of existing units are:

[0005] (1) Blending with kaolin. In areas such as Zhundong and Hami, kaolin and other minerals associated with coal mines can be used as additives to solve the slagging and contamination problems of boilers burning high-alkali coal at a relatively low cost. However, in other areas, there is basically no low-cost additive such as kaolin available for blending, which limits the increase in the proportion of high-alkali coal blending.

[0006] (2) Unit transformation, including burner transformation, heating surface tube screen spacing transformation, etc. This route has a large investment cost and a wide range of changes. After the transformation is completed, other problems may arise. If the coal type is changed, other indicators are difficult to guarantee.

[0007] (3) Install a soot blower. This route is to install a soot blower to make it fully covered, but the alkali metal will be contaminated and slag will form a bridge on the heating surface tubes with relatively small spacing between the tube screens, which cannot be solved by the soot blower.

[0008] (4) Combustion optimization. The slagging problem can be alleviated to a certain extent by optimizing the coal powder fineness, secondary air distribution, etc., but it cannot fundamentally solve the problem and there is still a high risk of slagging. Summary of the invention

[0009] The purpose of the embodiments of the present invention is to provide a method, device, electronic device and readable storage medium for controlling the operation of a thermal power unit, so as to at least solve the problem of varying degrees of slagging rapidly occurring on the heating surface of the boiler when the high-alkali coal blending ratio of the above-mentioned existing units exceeds a certain value.

[0010] In order to achieve the above object, the present invention provides a first aspect of a thermal power unit operation control method, the method comprising:

[0011] Get the current operating load rate of the thermal power unit;

[0012] Based on the current operating load rate, the high-alkali coal blending ratio is determined according to a preset relationship table or a preset relationship curve, wherein the preset relationship table or the preset relationship curve is used to characterize the corresponding relationship between different operating load rates and the high-alkali coal blending ratio;

[0013] Based on the high-alkali coal blending ratio, the raw coal switching system of the thermal power unit is controlled to adjust the input amount of high-alkali coal powder and low-alkali coal powder into the boiler.

[0014] Optionally, the expression of the preset relationship curve is:

[0015] β=-aln(η)+b;

[0016] Among them, β is the blending ratio of high-alkali coal; η is the operating load rate; a and b are fitting coefficients.

[0017] Optionally, the method further includes:

[0018] Real-time acquisition of internal images of boilers of thermal power units;

[0019] Based on the internal image of the boiler, determining the slag thickness of the inner wall of the boiler and the amount of change in the slag thickness within a preset time length;

[0020] If the slag thickness is greater than a preset thickness threshold or the slag thickness change is greater than a preset change threshold, the soot blower of the thermal power unit is controlled to perform blowing according to a preset soot blowing flow rate and a preset soot blowing time;

[0021] From the moment when the soot blower is controlled to stop blowing, after a preset time, the slag thickness and slag thickness change of the boiler inner wall are obtained again. If the re-obtained slag thickness is greater than the preset thickness threshold or the re-obtained slag thickness change is greater than the preset change threshold, the high-alkali coal blending ratio is determined as the preset blending ratio.

[0022] Optionally, the method further includes:

[0023] Obtain the temperature values ​​of the horizontal flue and tail flue of the boiler of the thermal power unit in real time;

[0024] Based on the temperature values ​​of the horizontal flue and the tail flue, calculate the heat exchange ratio between the boiler semi-radiation heating surface and the convection heating surface;

[0025] If the heat exchange ratio is less than the corresponding preset ratio threshold, the soot blower of the thermal power unit is controlled to perform blowing according to the preset soot blowing flow rate and the preset soot blowing time;

[0026] At the moment when the self-controlled soot blower stops blowing, if the heat exchange ratio is still less than the corresponding preset ratio threshold, the blending ratio of the high-alkali coal is determined as the preset blending ratio.

[0027] Optionally, the method further includes:

[0028] Obtain the fly ash mass flow rate at the outlet of the electrostatic precipitator, the slag mass flow rate of the slag remover and the fly ash mass flow rate at the chimney outlet of the thermal power unit during a period of operation, and obtain the coal ash content data and coal consumption of the thermal power unit during a period of time;

[0029] The sum of the fly ash mass flow rate at the outlet of the electrostatic precipitator, the coal slag mass flow rate of the slag remover and the fly ash mass flow rate at the chimney outlet is taken as the actual ash mass;

[0030] Based on the coal ash content data and coal consumption, the theoretical ash and slag volume of the thermal power unit is calculated;

[0031] If the difference between the theoretical ash amount and the actual ash amount is greater than a preset difference, the blending ratio of the high-alkali coal is determined as the preset blending ratio.

[0032] Optionally, the method further includes:

[0033] When the blending ratio of high-alkali coal is determined as the preset blending ratio, an alarm signal is generated.

[0034] A second aspect of the present invention provides an operation control device for a thermal power unit, the device comprising:

[0035] The load rate acquisition module is used to obtain the current operating load rate of the thermal power unit;

[0036] A blending ratio determination module, used to determine the high-alkali coal blending ratio based on the current operating load rate according to a preset relationship table or a preset relationship curve, wherein the preset relationship table or the preset relationship curve is used to characterize the corresponding relationship between different operating load rates and the high-alkali coal blending ratio;

[0037] The control module is used to control the raw coal switching system of the thermal power unit to adjust the input amount of high-alkali coal powder and low-alkali coal powder into the boiler based on the high-alkali coal blending ratio.

[0038] Optionally, the expression of the preset relationship curve is:

[0039] β=-aln(η)+b;

[0040] Among them, β is the blending ratio of high-alkali coal; η is the operating load rate; a and b are fitting coefficients.

[0041] A third aspect of the present invention provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned thermal power unit operation control method when executing the computer program.

[0042] On the other hand, the present invention provides a readable storage medium having instructions stored thereon, the instructions being used to enable a machine to execute the above-mentioned method for controlling the operation of a thermal power unit.

[0043] This technical solution determines the blending ratio of high-alkali coal in the pulverized coal required for boiler combustion according to the operating load rate of the thermal power unit, which can not only ensure the normal operation of the boiler and reduce the amount of slagging, but also increase the use of high-alkali coal and effectively reduce the cost of power generation.

[0044] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0046] Figure 1 It is a flow chart of the thermal power unit operation control method provided by the present invention;

[0047] Figure 2 It is a structural schematic diagram of the thermal power unit operation control device provided by the present invention;

[0048] Figure 3 It is a schematic diagram of a preset relationship curve provided by the present invention.

[0049] Description of Reference Numerals

[0050] 10- load rate acquisition module; 20- blending ratio determination module; 30- control module. DETAILED DESCRIPTION

[0051] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0052] Figure 1It is a flow chart of the thermal power unit operation control method provided by the present invention; Figure 2 It is a structural schematic diagram of the thermal power unit operation control device provided by the present invention; Figure 3 It is a schematic diagram of a preset relationship curve provided by the present invention.

[0053] During the combustion process of the boiler, due to the high content of sodium oxide in the high-alkali coal, sodium oxide-type high-temperature fouling is prone to occur. The reaction process is as follows: in the furnace environment of 700-800℃, Na2O sublimates into sodium oxide gas, condenses on the heating surface with lower wall temperature, and then chemically reacts with SO2 components in the flue gas, Al2O3 and Fe2O3 in the ash, etc., to successively react and form a bonding precipitation layer containing sodium sulfate, compound sodium sulfate and sodium pyrosulfate. The bonding ash is viscous and molten at high temperatures of 700-800℃. On the one hand, it captures a large amount of fly ash in the flue gas in the outer layer of the ash, and adheres it to the wall, which is not easy to remove. On the other hand, it continues to react in the center of the ash to form a bonding material. The comprehensive effect is that the fouling layer continues to thicken.

[0054] Research on high-alkali coal blending found that contamination is controllable when the high-alkali coal blending ratio is within a reasonable range. At the same temperature, as the high-alkali coal blending ratio decreases, the contamination of the heating surface decreases rapidly. This is because low-alkali coal contains a lot of aluminosilicates such as SiO2 and Al2O3. During the combustion process, part of the Na in the coal reacts with aluminosilicates at high temperatures to form sodium-containing aluminosilicates. The less sodium is released in the gas phase, the more controllable the high-temperature heating surface contamination is. However, when the high-alkali coal is blended to a certain ratio, as the high-alkali coal blending ratio increases, the contamination does not show a linear increase relationship with the blending ratio, but an exponential relationship.

[0055] Therefore, the embodiment of the present invention provides a method for controlling the operation of a thermal power unit, such as Figure 1 As shown, the method includes:

[0056] Step 1: Obtain the current operating load rate of the thermal power unit;

[0057] Step 2: Based on the current operating load rate, determine the high-alkali coal blending ratio according to a preset relationship table or a preset relationship curve, wherein the preset relationship table or the preset relationship curve is used to characterize the corresponding relationship between different operating load rates and the high-alkali coal blending ratio;

[0058] Step three: based on the high-alkali coal blending ratio, control the raw coal switching system of the thermal power unit to adjust the input amount of high-alkali coal powder and low-alkali coal powder into the boiler.

[0059] Specifically, since the theoretical power generation of the thermal power unit at full load is known, the current operating load rate can be calculated after the current operating load is obtained. In addition, the amount of pulverized coal input into the boiler is different under different loads. In order to ensure that the input pulverized coal can meet the operation of the boiler and reduce the risk of slagging and increase the use of high-alkali coal; the current operating load rate is used as input, and the high-alkali coal blending ratio can be obtained through analysis through a preset relationship table or preset relationship curve; then, according to the obtained high-alkali coal blending ratio, the raw coal switching system is controlled to adjust the amount of high-alkali coal pulverized coal and low-alkali coal pulverized coal input into the boiler, so that the high-alkali coal pulverized coal is the calculated high-alkali coal blending ratio.

[0060] The preset relationship table or preset relationship curve is obtained after comprehensive analysis based on the slagging degree of the boiler after combustion at different historical operating load rates with different high-alkali coal blending ratios.

[0061] In addition, the raw coal switching system for the furnace is to install a partition of a certain height in a certain area of ​​the raw coal bin along the belt direction, dividing the interior of the raw coal bin into two parts, one of which is high-alkali coal and the other is low-alkali coal. By controlling the two-way shut-off valve installed above the coal feeder inlet, the type of coal entering the furnace and the proportion of blending can be flexibly switched according to the operating load and the contamination and coking of the heating surface in the furnace. The two-way doors can even be opened at the same time, and the coal blending method is changed from blending in the separate grinding and pulverizing furnace to mixing in the double-belt bunker. When there is an uncontrollable trend of slagging and contamination, it is timely switched to low-alkali coal and the proportion of high-alkali coal is reduced to avoid the deterioration of slagging.

[0062] Further, in this embodiment, if Figure 3 As shown, it is a schematic diagram of the preset relationship curve, and the expression of the preset relationship curve is:

[0063] β=-aln(η)+b;

[0064] Among them, β is the blending ratio of high-alkali coal; η is the operating load rate; a and b are fitting coefficients.

[0065] Specifically, the blending ratio of high-alkali coal is obtained through the above-mentioned preset relationship curve, and the calculation result is accurate, which can reduce the slagging risk and increase the usage of high-alkali coal.

[0066] In one embodiment, a high-alkali coal blending contamination experiment is conducted for different blending ratios of high-alkali coal. A plurality of condensation tubes are placed in different temperature sections at the tail of reactors such as a high-temperature fixed bed and a settling furnace. The condensation characteristics of fly ash and alkali metals at different temperatures are mastered, and the existing contamination and slagging indexes are comprehensively compared. A contamination and slagging tendency criterion applicable to high-alkali coal ash is proposed, which provides the temperature value when more than 90% of the alkali metals are condensed for subsequent experimental research, that is, the smoke temperature value for controlling the switching of coal types. Although all boilers are equipped with soot blowers, the soot blowing coverage is different. Therefore, a full-size combustion boiler simulation model is established, and numerical simulation is carried out to study the flue gas temperature distribution and the slagging distribution of each heating surface under different high-alkali coal blending ratios. According to the numerical simulation results, an online visualization monitoring system for slagging in the furnace is installed in the key positions of the furnace, screen pass and last pass to monitor the slagging situation in the furnace online, guide the operation of the operating personnel and improve the soot blowing system. In high-temperature areas and areas with severe slagging and contamination, the soot blowing range and density are expanded as much as possible to ensure that the coked and contaminated ash can be blown down when the slagging and contamination of the boiler are within a controllable range.

[0067] Therefore, in order to ensure the safe operation of the boiler, the method further comprises:

[0068] Real-time acquisition of internal images of boilers of thermal power units;

[0069] Based on the internal image of the boiler, determining the slag thickness of the inner wall of the boiler and the amount of change in the slag thickness within a preset time length;

[0070] If the slag thickness is greater than a preset thickness threshold or the slag thickness change is greater than a preset change threshold, the soot blower of the thermal power unit is controlled to perform blowing according to a preset soot blowing flow rate and a preset soot blowing time;

[0071] From the moment when the soot blower is controlled to stop blowing, after a preset time, the slag thickness and slag thickness change of the boiler inner wall are obtained again. If the re-obtained slag thickness is greater than the preset thickness threshold or the re-obtained slag thickness change is greater than the preset change threshold, the high-alkali coal blending ratio is determined as the preset blending ratio.

[0072] Specifically, based on the internal image of the boiler, the slag thickness and the change in slag thickness of the inner wall of the boiler can be determined by using an image recognition algorithm; in addition, a labeled training data set can be obtained in advance (the training data set includes historical images and the slag thickness in the historical images, and the change in slag thickness in the continuous images), and the neural network model is trained by the training data set to obtain a slag thickness and slag thickness change determination model, and then the continuous images collected in real time are input into the model to obtain the slag thickness and the change in slag thickness. The preset time length can be composed of continuous sampling moments.

[0073] In one embodiment, the radiation or semi-radiation heating surface of the boiler is usually arranged along the direction of flue gas flow with a platen superheater, a final superheater, and finally a final reheater; the platen superheater and the final superheater have large tube-plate spacing, high flue gas temperature flowing through the heating surface, a large number of soot blowers, and slag contamination can be effectively purged, and the installation of a monitoring system can easily realize real-time visual monitoring of slag; while the final reheater has small tube-plate spacing, low flue gas temperature flowing through the heating surface, few soot blowers, and slag bridging, which is difficult to clean, and it is difficult to realize real-time visual monitoring of slag. Therefore, combined with the contamination mechanism and the special arrangement of the heating surface, it is proposed to timely adjust the proportion of high-alkali coal entering the furnace according to the distribution of flue gas temperature, so that the proportion of high-alkali coal blending can be maximized under the premise of safe and stable operation of the boiler, so that most of the slag contamination can be controlled on the heating surface before the final reheater, and the slag contamination on the final and subsequent heating surfaces can be controlled.

[0074] Temperature probe monitoring systems are installed in the horizontal flue (high-temperature reheater inlet) and tail flue (low reheater / low-pass inlet and outlet, economizer outlet) to measure the flue gas temperatures at the inlet and outlet of the semi-radiation, semi-convective and convection heating surfaces. The heat exchange ratio of each section of the heating surface can be calculated and analyzed to determine the operating status of the heating surface. If the heating surface is obviously slagging or contaminated, its own heat exchange ratio will decrease, and the heat exchange ratio of other related heating surfaces will also change. By monitoring the heat exchange ratio of the heating surface, the slagging and contamination conditions in the furnace can be judged in a timely manner. This can be used as the basis for the high-alkali coal blending ratio, furnace soot blowing and coal type switching.

[0075] Therefore, in order to ensure the safe operation of the boiler, the method further comprises:

[0076] Obtain the temperature values ​​of the horizontal flue and tail flue of the boiler of the thermal power unit in real time;

[0077] Based on the temperature values ​​of the horizontal flue and the tail flue, calculate the heat exchange ratio between the boiler semi-radiation heating surface and the convection heating surface;

[0078] If the heat exchange ratio is less than the corresponding preset ratio threshold, the soot blower of the thermal power unit is controlled to perform blowing according to the preset soot blowing flow rate and the preset soot blowing time;

[0079] At the moment when the self-controlled soot blower stops blowing, if the heat exchange ratio is still less than the corresponding preset ratio threshold, the blending ratio of the high-alkali coal is determined as the preset blending ratio.

[0080] Among them, calculating the heat exchange ratio between the semi-radiant heating surface and the convection heating surface of the boiler based on the temperature values ​​of the horizontal flue and the tail flue is an existing technology known to those skilled in the art, and therefore, it will not be described here in detail.

[0081] In one embodiment, when the boiler is burning normally, the amount of coal powder input (coal consumption) and the amount of coal slag and fly ash generated after combustion are basically the same. Therefore, by comparing the amount of coal powder input to the boiler and the amount of coal slag and fly ash generated, the slagging situation inside the boiler can be preliminarily judged.

[0082] Therefore, in order to ensure the safe operation of the boiler, the method further comprises:

[0083] Obtain the fly ash mass flow rate at the outlet of the electrostatic precipitator, the slag mass flow rate of the slag remover and the fly ash mass flow rate at the chimney outlet of the thermal power unit during a period of operation, and obtain the coal ash content data and coal consumption of the thermal power unit during a period of time;

[0084] The sum of the fly ash mass flow rate at the outlet of the electrostatic precipitator, the coal slag mass flow rate of the slag remover and the fly ash mass flow rate at the chimney outlet is taken as the actual ash mass;

[0085] Based on the coal ash content data and coal consumption, the theoretical ash and slag volume of the thermal power unit is calculated;

[0086] If the difference between the theoretical ash amount and the actual ash amount is greater than a preset difference, the blending ratio of the high-alkali coal is determined as the preset blending ratio.

[0087] The coal ash content data include: the received ash content of coal, the percentage of ash in slag to the total ash content of coal, the combustible content in slag, the percentage of ash in fly ash to the total ash content of coal, and the combustible content of fly ash;

[0088] Based on the coal ash data and coal consumption, the theoretical ash and slag volume of the thermal power unit is calculated, including:

[0089] The theoretical ash volume of the thermal power unit is calculated using the following formula:

[0090] Q = Qlz + Qfh;

[0091]

[0092] Among them, Q is the theoretical ash amount of the thermal power unit; Qlz is the theoretical slag production; Qfh is the theoretical fly ash production; B is the coal consumption; A is the received basis ash content of coal; Xlz is the percentage of ash in the slag to the total ash content of the coal; Clz is the combustible content in the slag; Xfh is the percentage of ash in the fly ash to the total ash content of the coal; Cfh is the combustible content of the fly ash.

[0093] Specifically, the preset blending ratio can be zero (i.e., no high-alkali coal is input into the boiler, only low-alkali coal is input); the preset blending ratio can also be set to a value close to zero. The theoretical ash amount of the thermal power unit is calculated using the above calculation formula, and the calculation result is accurate, which can ensure the safe operation of the thermal power unit.

[0094] Furthermore, the method further comprises:

[0095] When the blending ratio of high-alkali coal is determined as the preset blending ratio, an alarm signal is generated.

[0096] Specifically, in this embodiment, after the blending ratio of high-alkali coal is determined as the preset blending ratio, the thermal power unit will blend the high-alkali coal according to the preset blending ratio to achieve combustion. However, since the slag thickness in the boiler is greater than the preset thickness threshold or the re-acquired slag thickness change is greater than the preset change threshold or the heat exchange ratio is less than the corresponding preset ratio threshold or the difference between the theoretical ash amount and the actual ash amount is greater than the preset difference, the unit is not in a completely safe operating state and there are certain safety hazards. Therefore, an alarm signal is generated to remind the operator to perform maintenance or operation adjustments.

[0097] The embodiment of the present invention provides an operation control device for a thermal power unit, such as Figure 2 As shown, the device comprises:

[0098] The load rate acquisition module 10 is used to obtain the current operating load rate of the thermal power unit;

[0099] A blending ratio determination module 20 is used to determine the high-alkali coal blending ratio based on the current operating load rate according to a preset relationship table or a preset relationship curve, wherein the preset relationship table or the preset relationship curve is used to characterize the corresponding relationship between different operating load rates and the high-alkali coal blending ratio;

[0100] The control module 30 is used to control the raw coal switching system of the thermal power unit to adjust the input amount of high-alkali coal powder and low-alkali coal powder input into the boiler based on the high-alkali coal blending ratio.

[0101] Furthermore, the expression of the preset relationship curve is:

[0102] β=-aln(η)+b;

[0103] Among them, β is the blending ratio of high-alkali coal; η is the operating load rate; a and b are fitting coefficients.

[0104] An embodiment of the present invention further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned thermal power unit operation control method when executing the computer program.

[0105] An embodiment of the present invention further provides a machine-readable storage medium, on which instructions are stored, and the instructions are used to enable a machine to execute the above-mentioned thermal power unit operation control method.

[0106] In summary:

[0107] In this scheme, the flue gas temperature at the controlled coal type switching is compared with the flue gas temperature at the high temperature reheater inlet. When the flue gas temperature at the final reheater inlet is lower than the flue gas temperature at the controlled coal type switching, the boiler coking and fouling is basically controlled on the heating surface before the final reheater, and the risk of alkali metal fouling on the final and subsequent heating surfaces is relatively small. If the slagging on the heating surface before the final reheater is controllable, the proportion of high alkali coal blending can be increased until the flue gas temperature at the final reheater inlet approaches the flue gas temperature at the controlled coal type switching, or the slagging on the heating surface before the final reheater is uncontrollable. Under high load, the flue gas temperature at the final reheater inlet may be higher than the flue gas temperature at the controlled coal type switching, and two situations may occur:

[0108] (1) There is no need to switch the coal type to low-alkali coal. At this time, the boiler is under normal soot blowing conditions. The monitoring system does not find any slagging tendency, the heat exchange ratio of each heating surface remains unchanged, and the theoretical ash volume is basically equivalent to the mass flow rate of the electrostatic precipitator ash, the mass flow rate of the slag removal machine slag, and the mass flow rate of the ash discharged into the atmosphere. This is because the proportion of high-alkali coal blending is small, the sodium released in the coal is small, and the total amount of alkali metal slagging contamination of the unit is small and within a controllable range, which is basically the same as ordinary slagging contamination.

[0109] (2) The type of coal entering the furnace must be switched to low-alkali coal. At this time, under normal soot blowing conditions, the boiler may find through the monitoring system that there is a tendency to slagging, or the heat exchange ratio of each heating surface changes, or the theoretical ash volume is greater than the mass flow rate of the electrostatic precipitator ash, the mass flow rate of the slag removal machine slag, and the sum of the mass flow rates of the ash discharged into the atmosphere. This is because the high-alkali coal blending ratio is large, and more sodium is released in the coal. The condensation of sodium occurs on the last or even subsequent heating surfaces, leading to the above changes. At this time, it is immediately switched to low-alkali coal and soot blowing is strengthened. In addition to this situation where the inlet coal type must be switched to low-alkali coal, in the following three situations, regardless of whether the inlet flue gas temperature of the last reheater or the flue gas temperature of the control coal type switching is larger or smaller, the inlet coal rapid switching system must be used to switch the high-alkali coal entering the furnace to low-alkali coal to ensure safe and stable operation of the boiler.

[0110] 1. When there is a tendency of slagging and contamination (such as the change in slagging thickness is greater than 10cm / h), the corresponding soot blower is put into use in time, but the slagging and contamination cannot be alleviated after blowing, and there is a tendency to become more serious.

[0111] 2. The heat exchange ratio of the heating surface decreases, and the heat exchange ratios of other related heating surfaces also change, but the corresponding soot blowers are still not put into use to alleviate the problem.

[0112] 3. When the theoretical ash volume is significantly greater than the sum of the mass flow of the electrostatic precipitator ash, the mass flow of the slag scoop machine slag and the mass flow of the ash discharged into the atmosphere.

[0113] When all the above risks are eliminated, that is, the above situation does not exist, the boiler can be controlled to burn high-alkali coal in any proportion within the maximum blending ratio of high-alkali coal under the current load.

[0114] In a specific implementation, the target object is a 600MW supercritical unit boiler, with a single furnace, balanced ventilation, solid slag removal, full steel frame, full suspension structure, π-type layout, and the boiler is designed to use low-ash melting point Shenhua coal. Along the flue gas flow direction, the screen-type heating surface is arranged with screen-type superheaters, final superheaters, and final reheaters in order. The unit boiler is designed with 30 low NOX axial swirl burners (LNASB), with front and rear wall arrangement and counter combustion, and 6 HP963 medium-speed coal mills with positive pressure direct blowing pulverizing systems. Due to coal market reasons, the boiler needs to burn a large amount of high-alkali coal (Na≈5%), but due to the lack of blending means and methods, the proportion of high-alkali coal blending cannot be increased.

[0115] Through the above method, the study concluded that the smoke temperature value for controlling coal type switching is 795℃. According to the temperature probe monitoring system, it was found that when the load was below 55%, 795 degrees Celsius was higher than the smoke temperature at the inlet of the last stage reheater, and when the load was 55% or above, it was lower than the smoke temperature at the inlet of the last stage reheater. There are two situations:

[0116] Case 1: For loads of 55% or less:

[0117] At 30% load rate (minimum load), the proportion of high-alkali coal blending is within 75%, and the slagging and contamination of the heating surface is controllable. When the proportion is increased further, it is found that the last stage superheater has a slagging tendency, and it is difficult to clean the slagging and contamination by strengthening soot blowing and other methods.

[0118] At 55% load, the blending ratio of high-alkali coal is within 45%, and the slagging and contamination of the heating surface is controllable. When the ratio is increased further, it is found that the slagging tendency of the final superheater becomes rapid and serious, and it is difficult to clean the slagging and contamination by strengthening soot blowing and other methods. However, if any of the following three situations occurs, the coal type must be immediately switched to low-alkali coal according to the rapid switching system of the raw coal entering the furnace.

[0119] (1) When the slag monitoring system in the furnace finds that there is a tendency of slag contamination, the corresponding soot blower is put into use in time. However, the slag contamination cannot be alleviated after blowing and tends to become more serious.

[0120] (2) The heat absorption of the last and subsequent heating surfaces decreases, while the heat absorption of other related heating surfaces does not increase. The problem cannot be alleviated even if the corresponding soot blowers are put into use.

[0121] (3) The theoretical ash volume is significantly greater than the sum of the mass flow of the electrostatic precipitator ash, the mass flow of the slag scoop machine slag, and the mass flow of the ash discharged into the atmosphere.

[0122] The second situation: when the load is above 55%, according to the criterion of ash contamination and slagging tendency, the mixed coal with a high-alkali coal blending ratio of 15% or less is a low slagging contamination tendency coal, and the boiler slagging contamination is completely controllable at this time. The ratio of 15%-35% is a medium slagging contamination tendency coal, 55%-75% load, slagging contamination is controllable, and when the ratio exceeds 30%, the final reheater has a slagging tendency and the coal type needs to be switched immediately; the ratio of 15%-20% is a medium slagging contamination tendency coal, 75%-100% load, slagging contamination is controllable, and when the ratio exceeds 20%, the final reheater has a slagging tendency and the coal type needs to be switched immediately.

[0123] Finally, it was concluded that the maximum blending ratio of high-alkali coal at 30% load is 75%, the maximum blending ratio of high-alkali coal at 55% load is 45%, the maximum blending ratio of high-alkali coal at 75% load is 30%, and the maximum blending ratio of high-alkali coal at 100% load is 20%.

[0124] Those skilled in the art will understand that all or part of the steps in the method for implementing the above-mentioned embodiments can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including several instructions for making a single-chip microcomputer, a chip or a processor (processor) perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0125] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention.

[0126] The optional embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the technical concept of the embodiments of the present invention, the technical scheme of the embodiments of the present invention can be subjected to a variety of simple modifications, and these simple modifications all belong to the protection scope of the embodiments of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0127] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed in the embodiments of the present invention.

Claims

1. A method for controlling the operation of a thermal power unit, characterized in that: The method comprises: Get the current operating load rate of the thermal power unit; Based on the current operating load rate, the high-alkali coal blending ratio is determined according to a preset relationship table or a preset relationship curve, wherein the preset relationship table or the preset relationship curve is used to characterize the corresponding relationship between different operating load rates and the high-alkali coal blending ratio; Based on the high-alkali coal blending ratio, the raw coal switching system of the thermal power unit is controlled to adjust the input amount of high-alkali coal powder and low-alkali coal powder into the boiler.

2. The method for controlling the operation of a thermal power unit according to claim 1, characterized in that: The expression of the preset relationship curve is: ； in, is the blending ratio of high-alkali coal; is the operating load rate; and is the fitting coefficient.

3. The operation control method of a thermal power unit according to claim 1, characterized in that: The method further comprises: Real-time acquisition of internal images of boilers of thermal power units; Based on the internal image of the boiler, determining the slag thickness of the inner wall of the boiler and the amount of change in the slag thickness within a preset time length; If the slag thickness is greater than a preset thickness threshold or the slag thickness change is greater than a preset change threshold, the soot blower of the thermal power unit is controlled to perform blowing according to a preset soot blowing flow rate and a preset soot blowing time; From the moment when the soot blower is controlled to stop blowing, after a preset time, the slag thickness and slag thickness change of the boiler inner wall are obtained again. If the re-obtained slag thickness is greater than the preset thickness threshold or the re-obtained slag thickness change is greater than the preset change threshold, the high-alkali coal blending ratio is determined as the preset blending ratio.

4. The operation control method of a thermal power unit according to claim 1, characterized in that: The method further comprises: Obtain the temperature values ​​of the horizontal flue and tail flue of the boiler of the thermal power unit in real time; Based on the temperature values ​​of the horizontal flue and the tail flue, calculate the heat exchange ratio between the boiler semi-radiation heating surface and the convection heating surface; If the heat exchange ratio is less than the corresponding preset ratio threshold, the soot blower of the thermal power unit is controlled to perform blowing according to the preset soot blowing flow rate and the preset soot blowing time; At the moment when the self-controlled soot blower stops blowing, if the heat exchange ratio is still less than the corresponding preset ratio threshold, the blending ratio of the high-alkali coal is determined as the preset blending ratio.

5. The operation control method of a thermal power unit according to claim 1, characterized in that: The method further comprises: Obtain the fly ash mass flow rate at the outlet of the electrostatic precipitator, the slag mass flow rate of the slag remover and the fly ash mass flow rate at the chimney outlet of the thermal power unit during a period of operation, and obtain the coal ash content data and coal consumption of the thermal power unit during a period of time; The sum of the fly ash mass flow rate at the outlet of the electrostatic precipitator, the coal slag mass flow rate of the slag remover and the fly ash mass flow rate at the chimney outlet is taken as the actual ash mass; Based on the coal ash content data and coal consumption, the theoretical ash and slag volume of the thermal power unit is calculated; If the difference between the theoretical ash amount and the actual ash amount is greater than a preset difference, the blending ratio of the high-alkali coal is determined as the preset blending ratio.

6. The method for controlling the operation of a thermal power unit according to any one of claims 3 to 5, characterized in that: The method further comprises: When the blending ratio of high-alkali coal is determined as the preset blending ratio, an alarm signal is generated.

7. A thermal power unit operation control device, characterized in that: The device comprises: The load rate acquisition module is used to obtain the current operating load rate of the thermal power unit; A blending ratio determination module, used to determine the high-alkali coal blending ratio based on the current operating load rate according to a preset relationship table or a preset relationship curve, wherein the preset relationship table or the preset relationship curve is used to characterize the corresponding relationship between different operating load rates and the high-alkali coal blending ratio; The control module is used to control the raw coal switching system of the thermal power unit to adjust the input amount of high-alkali coal powder and low-alkali coal powder into the boiler based on the high-alkali coal blending ratio.

8. The thermal power unit operation control device according to claim 7, characterized in that: The expression of the preset relationship curve is: ； in, is the blending ratio of high-alkali coal; is the operating load rate; and is the fitting coefficient.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the thermal power unit operation control method described in any one of claims 1 to 6 is implemented.

10. A readable storage medium having instructions stored thereon, the instructions being used to enable a machine to execute the thermal power unit operation control method according to any one of claims 1 to 6.

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