Kaolin blending system for high-alkali coal burning boiler

Abstract

The utility model relates to a kaolin blending system for a boiler burning high-alkali coal. Comprising a coal bunker, a coal conveying belt, a coal mill, a kaolin bunker, a kaolin conveying belt, a kaolin mill, a primary fan, a coal conveying air pipe, a coal conveying air valve, a coal air powder pipeline, a Venturi injection device, a burner, a kaolin conveying air pipe, a kaolin conveying air valve, a gas mixing chamber, a temperature sensor, a circulating fan, a circulating flue gas pipeline, a circulating flue gas valve, a kaolin air powder pipeline and a boiler. The utility model relates to a high-efficiency and high-efficiency gas-phase alkali metal trapping device, which comprises a first-layer combustor, a second-layer combustor, a platen superheater, a superheater, a reheater, a coal economizer, an SCR catalyst layer and an air preheater, and is characterized in that kaolin is independently ground, so that the particle size of the kaolin is reduced, the specific surface area of the kaolin is increased, and the gas-phase alkali metal trapping efficiency is improved; the combustion condition of the boiler is prevented from being influenced during lower-layer doping and the kaolin reaction is not complete during upper-layer doping, and meanwhile, the kaolin is heated by circulating flue gas, so that the stable combustion of the boiler is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of optimized operation of boilers, and particularly relates to a system for blending kaolin in a boiler burning high-alkali coal. Background Technique

[0002] At present, coal is the main fuel for power station boilers in China. The proven reserves in the Zhundong coalfield in Xinjiang reach 390 billion tons, which is the largest integrated coalfield in China and one of the key energy bases for future development in China. However, the sodium content in Zhundong coal is relatively high, and the Na2O content in its ash composition mostly exceeds 5%, far higher than the Na2O content level in the ash of ordinary coal types (usually less than 1%). The water-soluble sodium and acid-soluble sodium in coal are easily vaporized in the high-temperature environment during the combustion process. When the flue gas temperature decreases, some gaseous sodium compounds will condense on the heat transfer surface tube wall to form a molten liquid film, which will then adhere to other solid ash particles, causing serious slagging; and some will condense on the surface of the ash particles to form a molten film on the surface of the ash particles, and these ash particles can directly adhere to the heat transfer surface or the sediment surface, causing slagging.

[0003] In order to alleviate the serious slagging problem during the combustion of high-sodium coal, the commonly used method is to add a silicon-aluminum-based high-melting-point additive during the coal combustion process. Limited by the local mineral resource distribution, the currently used additive is mainly kaolin. Kaolin can undergo physical and chemical reactions with gaseous alkali metals in the flue gas under high-temperature conditions, reducing the concentration of gaseous alkali metals in the flue gas, thereby effectively alleviating the slagging problem of Zhundong coal.

[0004] However, there are the following problems in adding kaolin during the combustion of high-sodium coal at present: during the addition of kaolin, kaolin and raw coal are usually sent into the raw coal bunker together, and then sent into the coal mill for grinding together. However, due to the large difference in the grindability coefficients of kaolin minerals and coal, the particle sizes of the pulverized coal and kaolin sent into the boiler after grinding are not consistent. And after kaolin participates in combustion, only a layer of alkali metal compounds condenses on its surface, and no reaction occurs with gaseous alkali metals inside. Therefore, only by controlling the ratio of kaolin to pulverized coal when entering the coal bunker, the proportion of kaolin participating in combustion cannot be accurately controlled. When the content of kaolin is small, it cannot play a role in alleviating slagging, while when the content of kaolin is too large, it will bring greater sensible heat loss of ash slag and more serious pipeline wear problems to the boiler. Content of the Utility Model

[0005] In order to solve the problems existing in adding kaolin during the combustion of existing high-sodium coal, the purpose of the utility model is to provide a system for blending kaolin in a boiler burning high-alkali coal.

[0006] To achieve the above object, the utility model adopts the following technical solutions: A system for blending kaolin in a boiler burning high-alkali coal, comprising a coal bunker 1, a coal conveyor belt 2, a coal mill 3, a kaolin bunker 4, a kaolin conveyor belt 5, a kaolin mill 6, a primary air fan 7, a coal conveying air duct 8, a coal conveying air valve 9, a coal-air-powder pipeline 10, a Venturi injection device 11, a burner 12, a kaolin conveying air duct 13, a kaolin conveying air valve 14, a mixing chamber 15, a temperature sensor 16, a circulation fan 17, a circulating flue gas pipeline 18, a circulating flue gas valve 19, a kaolin-air-powder pipeline 20, a boiler 21, a platen superheater 22, a superheater 23, a reheater 24, an economizer 25, an SCR catalyst layer 26, and an air preheater 27.

[0007] The coal in the coal bunker 1 is fed into the coal mill 3 through the coal conveyor belt 2.

[0008] The kaolin in the kaolin bunker 4 is fed into the kaolin mill 6 through the kaolin conveyor belt 5.

[0009] The boiler 21 includes a burner 12, a platen superheater 22, a superheater 23, a reheater 24, an economizer 25, an SCR catalyst layer 26, and an air preheater 27.

[0010] The primary air fan 4 extracts air and enters the air preheater 27. The preheated air is divided into two streams. One stream enters the coal mill 3 through the coal conveying air duct 8 and the coal conveying air valve 9, then carries pulverized coal into the coal-air-powder pipeline 10 and is divided into four paths leading to the burner 12 of the boiler 21. A Venturi injection device 11 is provided on the coal-air-powder pipeline 10 corresponding to the second-layer burner 12; the other stream enters the mixing chamber 15 through the kaolin conveying air duct 13 and the kaolin conveying air valve 14, and a temperature sensor 16 is installed on the outlet pipeline of the mixing chamber 15.

[0011] The Venturi injection device 11 is made of wear-resistant material.

[0012] The circulation fan 17 extracts the flue gas at the inlet of the economizer 25, mixes it with the primary air in the kaolin conveying air duct 13 in the mixing chamber 15 through the circulating flue gas pipeline 18 and the circulating flue gas valve 19. The mixed gas is introduced into the kaolin mill 6 and carries kaolin powder into the Venturi injection device 11 through the kaolin-air-powder pipeline 20.

[0013] Compared with the existing method for blending kaolin in a boiler burning high-alkali coal, the utility model has the following advantages.

[0014] 1. For the system for blending kaolin in a boiler burning high-alkali coal of the utility model, by separately grinding kaolin, the particle size of kaolin is reduced, the specific surface area of kaolin is increased, and the capture efficiency of gaseous alkali metals is improved.

[0015] 2. The system for blending kaolin in a boiler burning high-alkali coal according to the present utility model adds kaolin to the nozzle of the second burner through a Venturi ejector device, avoiding affecting the combustion condition of the boiler when adding to the lower layer and incomplete reaction of kaolin when adding to the upper layer.

[0016] 3. The system for blending kaolin in a boiler burning high-alkali coal according to the present utility model uses recycled flue gas to heat kaolin, increasing the temperature of kaolin when it enters the furnace and avoiding affecting the coal powder combustion condition due to too low temperature of kaolin. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the overall structure diagram of the system for blending kaolin in a boiler burning high-alkali coal according to the present utility model.

[0018] Figure 2 It is the connection schematic diagram of the Venturi ejector device of the system for blending kaolin in a boiler burning high-alkali coal according to the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0020] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "top", "bottom", "one side", "the other side", "front", "rear", "middle part", "inside", "top end", "bottom end", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present utility model; the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; in addition, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0021] Next, the present utility model will be further described in detail with reference to the accompanying drawings.

[0022] AsFigure 1 As shown in the figure, the utility model provides a system for blending kaolin in a boiler burning high-alkali coal, which includes a coal bunker 1, a coal conveyor belt 2, a coal mill 3, a kaolin bunker 4, a kaolin conveyor belt 5, a kaolin mill 6, a primary air fan 7, a coal conveying air duct 8, a coal conveying air valve 9, a coal-air-powder pipeline 10, a Venturi injection device 11, a burner 12, a kaolin conveying air duct 13, a kaolin conveying air valve 14, a mixing chamber 15, a temperature sensor 16, a circulating fan 17, a circulating flue gas pipeline 18, a circulating flue gas valve 19, a kaolin-air-powder pipeline 20, a boiler 21, a platen superheater 22, a superheater 23, a reheater 24, a economizer 25, an SCR catalyst layer 26, and an air preheater 27.

[0023] The coal in the coal bunker 1 is sent into the coal mill 3 through the coal conveyor belt 2.

[0024] The kaolin in the kaolin bunker 4 is sent into the kaolin mill 6 through the kaolin conveyor belt 5.

[0025] The boiler 21 includes a burner 12, a platen superheater 22, a superheater 23, a reheater 24, an economizer 25, an SCR catalyst layer 26, and an air preheater 27.

[0026] The primary air fan 4 extracts air and sends it into the air preheater 27. The preheated air is divided into two streams. One stream enters the coal mill 3 through the coal conveying air duct 8 and the coal conveying air valve 9, then carries the pulverized coal into the coal-air-powder pipeline 10 and is divided into four paths leading to the burner 12 of the boiler 21. A Venturi injection device 11 is provided on the coal-air-powder pipeline 10 corresponding to the second-layer burner 12. The other stream enters the mixing chamber 15 through the kaolin conveying air duct 13 and the kaolin conveying air valve 14, and a temperature sensor 16 is installed on the outlet pipeline of the mixing chamber 15.

[0027] The Venturi injection device 11 is made of wear-resistant material.

[0028] The circulating fan 17 extracts the flue gas at the inlet of the economizer 25, mixes it with the primary air in the kaolin conveying air duct 13 in the mixing chamber 15 through the circulating flue gas pipeline 18 and the circulating flue gas valve 19. The mixed gas is sent into the kaolin mill 6, and carries the kaolin powder into the Venturi injection device 11 through the kaolin-air-powder pipeline 20.

[0029] For those skilled in the art, it is obvious that the present utility model is not limited to the details of the above-described exemplary embodiments, and the present utility model can be implemented in other specific forms without departing from the spirit or basic characteristics of the present utility model. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present utility model is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present utility model. Any reference signs in the claims should not be construed as limiting the claims involved.

[0030] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A system for blending kaolin in a boiler burning high-alkali coal, comprising a coal bunker (1), a coal conveyor belt (2), a coal mill (3), a kaolin bunker (4), a kaolin conveyor belt (5), a kaolin mill (6), a primary air fan (7), a coal conveying air duct (8), a coal conveying air valve (9), a coal-air-powder pipeline (10), a Venturi ejector device (11), a burner (12), a kaolin conveying air duct (13), a kaolin conveying air valve (14), a mixing chamber (15), a temperature sensor (16), a circulation fan (17), a circulating flue gas pipeline (18), a circulating flue gas valve (19), a kaolin-air-powder pipeline (20), a boiler (21), a platen superheater (22), a superheater (23), a reheater (24), an economizer (25), an SCR catalyst layer (26), and an air preheater (27). The coal in the coal bunker (1) is fed into the coal mill (3) through the coal conveyor belt (2). The kaolin in the kaolin bunker (4) is fed into the kaolin mill (6) through the kaolin conveyor belt (5). The boiler (21) includes a burner (12), a platen superheater (22), a superheater (23), a reheater (24), an economizer (25), an SCR catalyst layer (26), and an air preheater (27). The primary air fan (7) extracts air and enters the air preheater (27). The preheated air is divided into two streams. One stream enters the coal mill (3) through the coal conveying air duct (8) and the coal conveying air valve (9), then carries pulverized coal into the coal-air-powder pipeline (10) and is divided into four paths leading to the burner (12) of the boiler (21). A Venturi ejector device (11) is provided on the coal-air-powder pipeline (10) corresponding to the second-layer burner (12). The other stream enters the mixing chamber (15) through the kaolin conveying air duct (13) and the kaolin conveying air valve (14). A temperature sensor (16) is installed on the outlet pipeline of the mixing chamber (15). The circulation fan (17) extracts the flue gas at the inlet of the economizer (25), mixes it with the primary air in the kaolin conveying air duct (13) in the mixing chamber (15) through the circulating flue gas pipeline (18) and the circulating flue gas valve (19), and the mixture is fed into the kaolin mill (6), carries kaolin powder and enters the Venturi ejector device (11) through the kaolin-air-powder pipeline (20).

2. The system for blending kaolin in a boiler burning high-alkali coal according to claim 1, characterized in that The Venturi ejector device (11) is made of wear-resistant material.

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