A mixed coal blending combustion method and system for mitigating boiler heating surface ash slagging

Abstract

The application discloses a mixed coal blending combustion method and system for relieving ash deposition and slagging of a boiler heating surface, and belongs to the technical field of mixed coal blending combustion, which focuses on the ash content, Na2O and K2O content data in the coal quality data of the coal type, constructs a calculation model of the maximum alkali metal oxide equivalent value of the combustion boiler and the actual alkali metal oxide equivalent value of the coal type, and designs the constraint condition of the mixed coal blending combustion method and system in the ash deposition and slagging of the coal-fired boiler, so that the acquisition and adjustment of the mixed coal blending ratio are accurately realized. The mixed coal blending combustion method and system are convenient and operable, can accurately realize the mixed coal blending combustion in the coal-fired boiler, improve the accuracy of the mixed coal blending combustion control, ensure the reliability of the fuel combustion in the coal-fired boiler, improve the ash deposition and slagging degree of the boiler heating surface, reduce the shutdown and maintenance frequency of the coal-fired boiler, ensure the reliability and stability of the coal-fired boiler operation, and reduce the operation and economic cost of the enterprise.

Description

Technical Field

[0001] This invention belongs to the field of coal blending technology, specifically relating to a method and system for coal blending that alleviates ash slagging on the heating surface of a boiler. Background Technology

[0002] As is well known, modern society still relies heavily on traditional fossil fuels. Statistics show that approximately 74% of global energy consumption comes from primary energy sources such as coal, oil, and natural gas. In recent years, my country's total consumption of coal, oil, natural gas, primary electricity, and other energy sources has exceeded 4 billion tons of standard coal equivalent; coal accounts for about 60% of total energy consumption. For a considerable period in the future, coal will continue to hold a very important and dominant position in energy consumption sectors such as power generation and the chemical industry.

[0003] In my country, power plant boilers and industrial boilers typically use coal as their primary fuel, and the type of coal used often deviates from the design coal type. Generally, the quality of coal used for power generation is poor, with high ash and sulfur content, which easily leads to fouling, ash accumulation, slagging, corrosion, and wear on the boiler's heating surfaces. Since coal often contains minerals, these minerals are converted into ash when the coal burns in the furnace. This coal ash gradually accumulates on various heating surfaces of the boiler, affecting its normal operation.

[0004] Ash accumulation and slagging on the heating surfaces of coal-fired boilers are common problems. If not properly addressed, they can reduce boiler efficiency, worsen combustion, and even lead to boiler shutdowns and maintenance. Research has found that coals with high alkalinity (Na, K, etc.) are more prone to severe ash accumulation and slagging during actual combustion, and the Na₂O and K₂O content in alkali metal oxides is often the primary factor contributing to ash accumulation and slagging in boilers. Therefore, alleviating ash accumulation and slagging in high-alkali coal is a pressing practical engineering problem that needs to be solved.

[0005] Coal blending is one of the important ways to solve the problem of tight fuel supply and complex and variable coal types in my country's coal-fired power plant boilers, and to improve the safety, economy and environmental protection of unit operation. However, at present, most power plants in my country mainly rely on experience to blend different coal types during operation, which has a large degree of randomness and uncertainty. In addition, the on-site operators have insufficient understanding of the combustion state in the furnace and cannot respond in time to the negative effects of unreasonable blending. When faced with complex and variable coal types, it is difficult to ensure that the boiler operates under the optimal combustion state, which not only wastes resources, but also easily leads to serious ash accumulation and slagging in the boiler. Summary of the Invention

[0006] In response to one or more of the above-mentioned defects or improvement needs of the prior art, the present invention provides a method and system for co-firing coal to alleviate ash slagging on the heating surface of a boiler, which can effectively alleviate ash slagging on the heating surface of the boiler, improve the combustion quality of coal, and ensure that the boiler operates under optimal combustion conditions.

[0007] To achieve the above objectives, one aspect of the present invention provides a method for co-firing coal to alleviate ash slagging on the heating surface of a boiler, comprising the following steps:

[0008] S1: Obtain the design characteristic parameters of the coal-fired boiler and the coal quality data of the design coal type; the coal quality data includes ash content, Na2O content and K2O content;

[0009] S2: Calculate the maximum permissible alkali metal oxide equivalent value for the coal type used in the coal-fired boiler based on the coal quality data of the designed coal type. The maximum alkali metal oxide equivalent value The value is obtained through the following formula (1):

[0010] (1)

[0011] In the formula, This represents the maximum equivalent value of alkali metal oxides. The maximum permissible safety factor for alkali metal oxides is 1 to 2. To determine the percentage content of Na2O in the ash of the designed coal type; The percentage content of K2O in the coal ash of the designed coal type; 0.66 is the molar equivalent ratio of Na2O to K2O; The ash content of the coal type is designed; The maximum allowable safety margin for alkali metal oxides is between -20 and 20.

[0012] S3: Obtain coal quality data of the main coal used in actual use of the coal-fired boiler; at the same time, select at least one blending coal type with the potential to be blended with the main coal type, and obtain coal quality data of each blending coal type.

[0013] Calculate the actual alkali metal oxide equivalent value of the corresponding coal type using coal quality data. J The calculation process is shown in the following formula (2):

[0014] (2)

[0015] In the formula, This represents the actual alkali metal oxide equivalent value for coal type X; The percentage content of Na2O in the coal ash of coal type X; The percentage content of K2O in the coal ash of coal type X; The ash content of coal type X;

[0016] S4: Determine the blending data of the main combustion coal and the blended coal based on the actual alkali metal oxide equivalent values ​​of the main combustion coal and the blended coal, and blend the main combustion coal with several blended coals in front of the furnace according to the blending data to form mixed coal;

[0017] S5: Obtain coal quality data for the mixed coal and calculate the actual alkali metal oxide equivalent value of the mixed coal according to formula (2). Then, based on the calculation results, the relevant operating conditions for blended coal combustion are guided and adjusted to complete the blended coal combustion process.

[0018] As a further improvement of the present invention, in step S4, the blending ratio of each coal type is calculated by the following formula (3):

[0019] (3)

[0020] In the formula, The actual alkali metal oxide equivalent value of the main type of coal used for combustion; , … Let y be the actual alkali metal oxide equivalent value of the first, second, ..., yth blended coal types, where y is an integer not less than 1; The blending ratio of the main type of coal is between 0.4 and 1.0. , , The blending ratios of the first, second, ..., yth coal types are given, and each blending ratio is less than [a certain value]. And it is between 0 and 0.4, and .

[0021] As a further improvement of the present invention, after obtaining the coal quality data of the mixed coal in step S5, the maximum alkali metal oxide equivalent value of the coal-fired boiler is used as the basis for further improvement. Actual alkali metal oxide equivalent values ​​of mixed coal The difference To determine the suitability level of the mixed coal for a coal-fired boiler; among which, The determination method is as follows:

[0022] when When the temperature is >30, the degree of ash accumulation and slagging in the coal-fired boiler is very slight, and it is recorded as R1 level;

[0023] When 0 < When the temperature is ≤30℃, the degree of ash accumulation and slagging in coal-fired boilers is moderate, and it is recorded as R2 grade;

[0024] When -30 < When the ash accumulation and slagging of the coal-fired boiler is ≤0, it is classified as R3 level.

[0025] when When the temperature is below -30°C, the ash accumulation and slagging of coal-fired boilers is very severe, and it is classified as R4 level.

[0026] As a further improvement of the present invention, in step S5, the applicable grade of the mixed coal equivalent to a coal-fired boiler is adjusted to R1 or R2.

[0027] In another aspect, the present invention provides a coal blending and combustion system, which completes the coal blending and combustion within the boiler according to the coal blending and combustion method for alleviating ash slag formation on the boiler heating surface.

[0028] The coal blending and combustion system includes:

[0029] A primary combustion coal storage silo is used to store the primary combustion coal for the boiler.

[0030] At least one blending coal storage silo is used to store blending coals that have the potential to be blended with the main combustion coal.

[0031] A coal-fired boiler is used for the combustion of mixed coal.

[0032] A coal mixing device is installed on one side of the coal-fired boiler and connected to it by a conveying device, so that the mixed coal can be transported to the coal-fired boiler by the conveying device; and the coal mixing device is connected to the main coal storage bin and the at least one blended coal storage bin, respectively, for feeding the main coal and the corresponding blended coal separately.

[0033] A mixed coal quality testing device is provided corresponding to the conveying device, and is used to obtain mixed coal from the conveying device and test the coal quality data of the mixed coal.

[0034] As a further improvement of the present invention, a coal type and coal quality testing device is also included;

[0035] The coal type and quality testing device is set up for each coal type storage silo and is used to obtain the corresponding coal type from each coal type storage silo and test its coal quality data.

[0036] As a further improvement of the present invention, the coal type and coal quality testing device and the mixed coal quality testing device are the same testing device.

[0037] As a further improvement of the present invention, it also includes a human interaction device;

[0038] The manual interaction device is connected to the coal mixing device, each coal quality testing device, and each coal type storage silo respectively; and the manual interaction device is equipped with a coal quality data processing module that can execute steps S2 and S3, which is used to obtain the actual alkali metal oxide equivalent value of each coal type and the mixed coal and to complete the blending and combustion of each coal type.

[0039] As a further improvement of the present invention, the conveying device is a belt conveyor mechanism;

[0040] and / or

[0041] The coal mixing device is a stirring coal mixing device.

[0042] The aforementioned improved technical features can be combined with each other as long as they do not conflict with each other.

[0043] In summary, the beneficial effects of the above-described technical solutions conceived by this invention compared with the prior art include:

[0044] (1) The method of coal blending for reducing ash slagging on the heating surface of the boiler of the present invention, through specially designed coal blending steps of coal-fired boiler, focuses on the ash, Na2O and K2O content data in coal type and coal quality data, constructs a calculation model of the maximum alkali metal oxide equivalent value of the boiler and the actual alkali metal oxide equivalent value of the coal type, and designs the constraint conditions in the ash slagging of the coal-fired boiler, accurately realizes the acquisition and adjustment of the coal blending ratio, effectively solves the problem of ash slagging in coal-fired boiler, reduces the shutdown and maintenance of coal-fired boiler, fully ensures the reliability and stability of coal-fired boiler operation and use, and reduces the operating economic cost of enterprises.

[0045] (2) The method for reducing ash slag buildup on the boiler heating surface of the present invention is achieved by designing a corresponding blending ratio design method and by using the maximum alkali metal oxide equivalent value. J max Actual alkali metal oxide equivalent values ​​of mixed coal J mix The data were obtained separately, and based on this, the applicability level of mixed coal relative to coal-fired boilers was constructed, providing a reliable basis for the design and use of mixed coal, and further improving the efficiency and reliability of mixed coal co-firing design.

[0046] (3) The coal blending and co-firing system of the present invention for alleviating ash slag on the heating surface of the boiler has a simple system composition and convenient control. It can accurately realize the coal blending and co-firing design of the coal-fired boiler, reliably execute the coal blending and co-firing method for alleviating ash slag on the heating surface of the boiler, and ensure the accuracy of coal blending and co-firing of the coal-fired boiler. It does not require major modification to the structure of the coal-fired boiler itself, is easy to set up, and is especially suitable for modification of existing coal-fired boilers. It has excellent economic efficiency and practical value.

[0047] (4) The method of coal blending for reducing ash slag on the heating surface of the boiler of the present invention is convenient and highly operable. It can accurately realize coal blending in coal-fired boilers, improve the accuracy of coal blending control, ensure the reliability of fuel combustion in coal-fired boilers, improve the degree of ash slag accumulation on the heating surface of the boiler, reduce the number of shutdowns for maintenance of coal-fired boilers, ensure the reliability and stability of coal-fired boiler operation, extend the service life of coal-fired boilers, and reduce the operating costs of enterprises. It is especially suitable for the renovation of existing coal-fired boilers and has good application value and promotion prospects. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a schematic flowchart of a method for reducing ash slag buildup on the boiler heating surface in an embodiment of the present invention.

[0050] Figure 2 This is a schematic diagram of the structure of the coal blending system for alleviating ash slag buildup on the boiler heating surface in an embodiment of the present invention. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the 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 merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0052] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0053] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0054] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0055] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0056] Example:

[0057] One aspect of the present invention provides a method for blending coal to alleviate ash slagging on the heating surface of a boiler. The method aims to determine the design scheme for blending coal by acquiring and analyzing relevant parameters of the designed coal type and the coal type actually used, and to test the coal quality data of the blended coal, and on this basis determine the grade of the coal type, and then determine whether the blended coal type meets the application requirements of the corresponding coal-fired boiler.

[0058] Specifically, the coal blending and combustion method in the preferred embodiment includes the following steps:

[0059] S1: Obtain the design characteristic parameters of the coal-fired boiler and the coal quality data of the design coal type;

[0060] In a preferred embodiment, the aforementioned coal quality data includes ash content, Na2O content, and K2O content;

[0061] S2: Calculate the maximum permissible alkali metal oxide equivalent value for the coal type used in the coal-fired boiler based on the coal quality data of the designed coal type. Jmax ;

[0062] Specifically, in the preferred embodiment, the maximum alkali metal oxide equivalent value J The maximum value is obtained using the following formula (1):

[0063] (1)

[0064] In the formula, This represents the maximum equivalent value of alkali metal oxides. The maximum permissible safety factor for alkali metal oxides is 1 to 2. To determine the percentage content of Na2O in the ash of the designed coal type; The percentage content of K2O in the coal ash of the designed coal type; 0.66 is the molar equivalent ratio of Na2O to K2O; The ash content of the coal type is designed; The maximum allowable safety margin for alkali metal oxides is between -20 and 20.

[0065] in addition, , The value of is related to the design characteristic parameters of a uniformly heated coal-fired boiler.

[0066] S3: Obtain coal quality data of the main coal used in actual use of the coal-fired boiler; at the same time, select at least one blending coal type with the potential to be blended with the main coal type, and obtain coal quality data of each blending coal type.

[0067] In actual design, the selection of blended coal types can be made by comprehensively considering factors such as market price and supply and demand. At the same time, the coal quality data of each coal type mainly includes data such as ash content, Na2O and K2O content.

[0068] In practical design, it is preferable to utilize the actual alkali metal oxide equivalent value of the coal type. J To determine the degree of ash accumulation and slagging in coal-fired boilers. In a preferred embodiment, the actual alkali metal oxide equivalent value... J The preferred method is to calculate using the following formula (2):

[0069] (2)

[0070] In the formula, This represents the actual alkali metal oxide equivalent value for coal type X; The percentage content of Na2O in the coal ash of coal type X; The percentage content of K2O in the coal ash of coal type X; The ash content is for coal type X.

[0071] It is not difficult to understand that, under actual conditions, the actual alkali metal oxide equivalent value of the corresponding coal combustion J The smaller the value, the less likely the coal type is to cause ash and slag buildup in the boiler. J The higher the value, the more likely the coal type is to cause ash accumulation and slagging in the combustion boiler.

[0072] S4: Determine the blending data of the main combustion coal and the blended coal based on the actual alkali metal oxide equivalent values ​​of the main combustion coal and the blended coal, and blend the main combustion coal with several blended coals in front of the furnace according to the blending data to form mixed coal;

[0073] It is understandable that, for the actual blended coal used, its actual alkali metal oxide equivalent value... J It should be less than the maximum permissible alkali metal oxide equivalent value for the type of coal used in the boiler. J max .

[0074] Therefore, in the preferred embodiment, the proportion of each coal type blended is preferably calculated by the following formula (3):

[0075] (3)

[0076] In the formula, The actual alkali metal oxide equivalent value of the main type of coal used for combustion; , … Let y be the actual alkali metal oxide equivalent value of the first, second, ..., yth blended coal types, where y is an integer not less than 1; The blending ratio of the main type of coal is between 0.4 and 1.0. , , The blending ratios of the first, second, ..., yth coal types are given, and each blending ratio is less than [a certain value]. And it is between 0 and 0.4, and .

[0077] By adjusting the blending ratios, the blending ratio of the mixed coal can be obtained, thereby guiding the blending of the mixed coal.

[0078] S5: Analyze the coal quality data of the blended coal and calculate the actual alkali metal oxide equivalent value of the blended coal. The calculation results will guide and adjust the relevant operating conditions for blended coal combustion.

[0079] S6: Based on the maximum alkali metal oxide equivalent value of coal-fired boilers Actual alkali metal oxide equivalent values ​​of mixed coal The difference To determine the suitability level of the mixed coal for a coal-fired boiler; among which,

[0080]

[0081] In the formula, The maximum permissible alkali metal oxide equivalent value for the type of coal used in combustion boilers; This represents the actual alkali metal oxide equivalent value of the mixed coal.

[0082] The specific determination method is as follows:

[0083] when When the temperature is >30, the degree of ash accumulation and slagging in the coal-fired boiler is very slight, and it is recorded as R1 level;

[0084] When 0 < When the temperature is ≤30℃, the degree of ash accumulation and slagging in coal-fired boilers is moderate, and it is recorded as R2 grade;

[0085] When -30 < When the ash accumulation and slagging of the coal-fired boiler is ≤0, it is classified as R3 level.

[0086] when When the temperature is below -30°C, the ash accumulation and slagging of coal-fired boilers is very severe, and it is classified as R4 level.

[0087] Under normal circumstances, in order to ensure the stability and service life of coal-fired boilers, the applicable grade of blended coal needs to be adjusted to R1 or R2.

[0088] As another specific embodiment of the present invention, a corresponding coal blending system is provided for the aforementioned method of mitigating ash slag formation on the boiler heating surface, for executing the aforementioned coal blending method, such as... Figure 2 As shown in the image.

[0089] Specifically, the coal blending system in the preferred embodiment includes a main coal storage silo, at least one blending coal storage silo, a coal blending device, a conveying device, a coal quality testing device, a manual interaction device, and a coal-fired boiler.

[0090] The primary combustion coal storage silo stores the primary combustion coal used in coal-fired boilers. Typically, the quality of this primary combustion coal is poor, which can easily lead to ash accumulation and slagging in the boiler. Meanwhile, there are one or more blending coal storage silos, used to store coals with the potential for blending with the primary combustion coal (alkali metal oxide equivalent value). Less than the alkali metal oxide equivalent value of the main combustion coal type And less than the maximum alkali metal oxide equivalent value of coal-fired boilers. ) types of coal to be blended.

[0091] Meanwhile, a coal blending device is installed on one side of the coal-fired boiler, and the two are connected by a conveying device. This device is used to blend the main type of coal and the selected blended coal at a selected blending ratio to form mixed coal. Accordingly, the mixed coal can be conveyed to the coal-fired boiler by the conveying device.

[0092] More specifically, in the preferred embodiment, the coal mixing device is preferably a stirring coal mixing device, such as an industrial mixer, which can mix multiple types of coal by stirring. Meanwhile, in the preferred embodiment, the conveying device is preferably a belt conveyor mechanism, which can accurately convey the mixed coal.

[0093] Furthermore, in the preferred embodiment, the mixed coal quality testing device is configured to correspond to the conveying device, so that it can collect mixed coal samples from the conveying device and thereby obtain the coal quality data of the mixed coal.

[0094] More specifically, each coal type storage silo is equipped with at least one coal type and coal quality testing device, which is set up for at least one coal type storage silo. In the preferred embodiment, it is connected to each coal type storage silo respectively, and can obtain the original coal type from each coal type storage silo and test its coal type data accordingly.

[0095] In addition, in actual setup, the coal type and quality testing device can be further preferred to be shared with the mixed coal quality testing device, that is, only one coal quality testing device needs to be set up in the mixed coal co-firing system.

[0096] Accordingly, in the preferred embodiment, the manual interaction device is connected to the coal mixing device, the coal quality testing device, and the storage bins for each type of coal. The manual interaction device is equipped with a coal quality data processing module that can execute steps S2 and S3. Through this module, the coal quality data of each type of coal and the mixed coal can be obtained, and the corresponding alkali metal oxide equivalent value can be calculated based on the aforementioned coal quality data. This allows the blending ratio of the main combustion coal and the corresponding blended coal to be obtained, thereby controlling or adjusting the coal output of the corresponding coal storage bin. This enables the blending and combustion of each type of coal and the adjustment of the blending ratio of each type of coal in the mixed coal, thus achieving dynamic adjustment of the mixed coal.

[0097] To better illustrate the technical solutions of this invention, the following description uses the design process of a specific embodiment to illustrate the technical solutions of this invention.

[0098] Taking the actual renovation of a power plant as an example, the power plant is equipped with a coal-fired steam turbine generator set with a rated power (TRL) of 630MW. The coal-fired boiler is a subcritical controlled circulating drum boiler produced by Harbin Boiler Factory. The rated evaporation capacity of the boiler is 2030t / h, the boiler efficiency is 93.3%, the flue gas temperature is about 132.9℃, the coal consumption is about 361.25±41t / h, and the minimum stable combustion load without oil injection is 30%. The ash content of the designed coal is 39.84%, and the Na2O and K2O contents are 0.25% and 1.07%, respectively. Based on the design characteristic parameters of the coal-fired boiler, the maximum allowable alkali metal oxide equivalent value of the coal type used in the boiler is calculated according to formula (1). It is 57.14.

[0099] Before the modification using the method in the preferred embodiment of the present invention, the actual coal type used by the boiler was designated as coal type 1, wherein the ash content, Na2O, and K2O content of coal type 1 were 23.05%, 3.76%, and 2.35%, respectively. When using coal type 1, the unit would be shut down for maintenance every two months on average due to ash accumulation and slagging on the boiler heating surface, and the ash accumulation and slagging situation on the boiler heating surface was very serious. According to the calculation of formula (3), it can be found that when using coal type 1, the actual alkali metal oxide equivalent value J of coal type 1 is 122.42, which is far higher than the maximum allowable alkali metal oxide equivalent value of 57.14 for the coal type used by the boiler, belonging to R4 level.

[0100] After modification using the method in the preferred embodiment of the present invention, the main coal type used in the boiler remains coal type 1, and coal type 2 is added for blending with coal type 1. The ash, Na2O, and K2O contents of coal type 2 are 3.29%, 0.78%, and 0.16%, respectively. If only coal type 2 is used, the alkali metal oxide equivalent value J of coal type 2, calculated using formula (3), is 2.91, which is far lower than the maximum permissible alkali metal oxide equivalent value of 57.14 for the coal type used in the boiler, belonging to the R1 grade.

[0101] However, considering factors such as market price and supply and demand, it is not feasible to use only coal type 2. By employing the coal blending system provided in the preferred embodiment of this invention and following the steps of the coal blending method, when the blending ratio of coal type 1 to coal type 2 is 2:1, the test results from the coal quality testing device show that the ash content, Na2O, and K2O content of the blended coal are 14.95%, 2.54%, and 1.46%, respectively, and the alkali metal oxide equivalent value of the blended coal is... J The value is 52.38, which falls under the R2 category.

[0102] Through the implementation of this invention, the equivalent value of alkali metal oxides in the coal used in boilers is increased. JThe ash concentration decreased from 122.42 to 52.38, reducing the boiler's ash accumulation and slagging level from the very severe R4 to the moderate R2. Since the upgrade, the boiler has not required any shutdowns for maintenance due to ash accumulation on the heating surface during a 180-day continuous operation period, effectively alleviating the boiler ash accumulation and slagging problem and saving the company significant operating costs.

[0103] The method for reducing ash and slag buildup on boiler heating surfaces in this invention is convenient, highly operable, and can accurately achieve coal blending in coal-fired boilers. It improves the accuracy of coal blending control, ensures reliable fuel combustion, reduces ash and slag buildup on boiler heating surfaces, decreases the frequency of boiler shutdowns for maintenance, ensures the reliability and stability of boiler operation, extends the service life of coal-fired boilers, and lowers the operating costs for enterprises. It is particularly suitable for the retrofitting of existing coal-fired boilers and has good application value and promising prospects for widespread adoption.

[0104] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for co-firing coal to alleviate ash slagging on the heating surface of a boiler, characterized in that, Includes the following steps: S1: Obtain the design characteristic parameters of the coal-fired boiler and the coal quality data of the design coal type; the coal quality data includes ash content, Na2O content and K2O content; S2: Calculate the maximum permissible alkali metal oxide equivalent value for the coal type used in the coal-fired boiler based on the coal quality data of the designed coal type. The maximum alkali metal oxide equivalent value The value is obtained through the following formula (1): （1） In the formula, This represents the maximum equivalent value of alkali metal oxides. The maximum permissible safety factor for alkali metal oxides is 1 to 2. To determine the percentage content of Na2O in the ash of the designed coal type; The percentage content of K2O in the coal ash of the designed coal type; 0.66 is the molar equivalent ratio of Na2O to K2O; The ash content of the coal type is designed; The maximum allowable safety margin for alkali metal oxides is between -20 and 20. S3: Obtain coal quality data of the main coal used in actual use of the coal-fired boiler; at the same time, select at least one blending coal type with the potential to be blended with the main coal type, and obtain coal quality data of each blending coal type. Calculate the actual alkali metal oxide equivalent value of the corresponding coal type using coal quality data. J The calculation process is shown in equation (2) below: （2） In the formula, This represents the actual alkali metal oxide equivalent value for coal type X; The percentage content of Na2O in the coal ash of coal type X; The percentage content of K2O in the coal ash of coal type X; The ash content of coal type X; S4: Determine the blending data of the main combustion coal and the blended coal based on the actual alkali metal oxide equivalent values ​​of the main combustion coal and the blended coal, and blend the main combustion coal with several blended coals in front of the furnace according to the blending data to form mixed coal; S5: Obtain coal quality data for the mixed coal and calculate the actual alkali metal oxide equivalent value of the mixed coal according to formula (2). Then, based on the calculation results, the relevant operating conditions for blended coal combustion are guided and adjusted to complete the blended coal combustion process.

2. The method for co-firing coal to alleviate ash slag buildup on the boiler heating surface according to claim 1, characterized in that, In step S4, the blending ratio of each coal type is calculated using the following formula (3): （3） In the formula, The actual alkali metal oxide equivalent value of the main type of coal used for combustion; , … Let y be the actual alkali metal oxide equivalent value of the first, second, ..., yth blended coal types, where y is an integer not less than 1; The blending ratio of the main type of coal is between 0.4 and 1.

0. , , The blending ratios of the first, second, ..., yth coal types are given, and each blending ratio is less than [a certain value]. And it is between 0 and 0.4, and .

3. The method for co-firing coal to alleviate ash slagging on the boiler heating surface according to claim 1 or 2, characterized in that, After obtaining the coal quality data of the mixed coal in step S5, the maximum alkali metal oxide equivalent value of the coal-fired boiler is used as the basis for further analysis. Actual alkali metal oxide equivalent values ​​of mixed coal The difference To determine the suitability level of the mixed coal for a coal-fired boiler; among which, The determination method is as follows: when When the temperature is >30, the degree of ash accumulation and slagging in the coal-fired boiler is very slight, which is recorded as R1 level; When 0 < When the temperature is ≤30℃, the degree of ash accumulation and slagging in coal-fired boilers is moderate, and it is recorded as R2 grade; When -30 < When the ash accumulation and slagging of the coal-fired boiler is ≤0, it is classified as R3 level. when When the temperature is below -30°C, the ash accumulation and slagging of coal-fired boilers is very severe, and it is classified as R4 level.

4. The method for co-firing coal to alleviate ash slag buildup on the boiler heating surface according to claim 3, characterized in that, In step S5, the applicable grade of the mixed coal equivalent to a coal-fired boiler is adjusted to R1 or R2.

5. A coal blending and combustion system, characterized in that, The coal blending system completes the coal blending in the boiler according to any one of claims 1 to 4, which is a coal blending method for alleviating ash slag formation on the boiler heating surface. The coal blending and combustion system includes: A primary combustion coal storage silo is used to store the primary combustion coal for the boiler. At least one blending coal storage silo is used to store blending coals that have the potential to be blended with the main combustion coal. A coal-fired boiler is used for the combustion of mixed coal. A coal mixing device is installed on one side of the coal-fired boiler and connected to it by a conveying device, so that the mixed coal can be transported to the coal-fired boiler by the conveying device; and the coal mixing device is connected to the main coal storage bin and the at least one blended coal storage bin, respectively, for feeding the main coal and the corresponding blended coal separately. A mixed coal quality testing device is provided corresponding to the conveying device, and is used to obtain mixed coal from the conveying device and test the coal quality data of the mixed coal.

6. The coal blending and combustion system according to claim 5, characterized in that, It also includes coal type and coal quality testing equipment; The coal type and quality testing device is set up for each coal type storage silo and is used to obtain the corresponding coal type from each coal type storage silo and test its coal quality data.

7. The coal blending and combustion system according to claim 6, characterized in that, The coal type and coal quality testing device and the mixed coal quality testing device are the same testing device.

8. The coal blending system according to claim 6 or 7, characterized in that, It also includes human-computer interaction devices; The manual interaction device is connected to the coal mixing device, each coal quality testing device, and each coal type storage silo respectively; and the manual interaction device is equipped with a coal quality data processing module that can execute steps S2 and S3, which is used to obtain the actual alkali metal oxide equivalent value of each coal type and the mixed coal and to complete the blending and combustion of each coal type.

9. The coal blending system according to any one of claims 5 to 7, characterized in that, The conveying device is a belt conveyor mechanism; and / or The coal mixing device is a stirring coal mixing device.

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