Carbon dioxide drying middle storage type pulverizing system

Abstract

The utility model belongs to the technical field of safety improvement and transformation of coal-fired thermal power generating units, and discloses a carbon dioxide drying middle storage type coal pulverizing system which comprises a hearth, a pulverized coal bunker, an air preheater, a carbon dioxide storage tank and a pulverized coal separation unit. The carbon dioxide storage tank is connected with an inlet of an air preheater, an outlet of the air preheater is connected with a plurality of coal mills, the coal mills are all connected with a pulverized coal separation unit, the pulverized coal separation unit is connected with a pulverized coal bin, and the pulverized coal bin is connected with a hearth. The inert gas carbon dioxide is adopted as a drying medium of the coal pulverizing system, the possibility of detonation of the coal pulverizing system is completely eradicated, the temperature of the medium entering the coal pulverizing system can be increased by fully utilizing the upper limit of the heat exchange capacity of the boiler air preheater, the range of coal types which a corresponding power plant boiler can adapt to is greatly widened, and the energy consumption is reduced. And the safety and reliability of power plant operation and the degree of freedom of coal purchasing are powerfully improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of safety improvement and transformation of coal-fired thermal power units, in particular to a carbon dioxide drying central storage type pulverizing system. Background Art

[0002] In recent years, the complex and changing global economic situation and the adjustment of energy structure have caused the price of power coal to continue to rise. For many thermal power companies that rely on coal as fuel, this trend has undoubtedly brought huge cost pressure. In order to maintain competitiveness and normal operations in such a market environment, most thermal power companies have adopted the strategy of adjusting coal procurement and blending economic coal to balance. In other words, in the current power coal market environment, most thermal power units cannot operate according to the designed coal type, and the volatile matter and moisture of the coal are seriously deviated from the design.

[0003] For boilers using a central storage pulverizing system, changes in coal blending can lead to two problems: On the one hand, when the moisture content of the incoming coal increases, it exceeds the designed drying capacity of the pulverizing system, resulting in a low outlet temperature of the pulverizer, a reduced output of the pulverizing system, and reduced production efficiency. In extreme cases, excessive moisture in the pulverized coal may cause internal agglomeration in the pulverizer, and in severe cases, the boiler may even be forced to operate at a limited output, thus affecting the power supply capacity of the entire power plant. On the other hand, when the dry ash-free volatile matter of the incoming coal is greater than 25%, the operational safety of the central storage pulverizing system will be greatly reduced, and the risk of explosion cannot be completely avoided. Summary of the invention

[0004] The utility model aims to provide a carbon dioxide drying intermediate storage type pulverizing system to solve the problem of reduced operation safety caused by changes in coal blending in the prior art.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A carbon dioxide drying intermediate storage type pulverizing system, comprising a furnace, a pulverized coal bin, an air preheater, a carbon dioxide storage tank and a pulverized coal separation unit;

[0007] The carbon dioxide storage tank is connected to the inlet of the air preheater, the outlet of the air preheater is connected to a plurality of coal mills, the plurality of coal mills are connected to a coal powder separation unit, the coal powder separation unit is connected to a coal powder bin, and the coal powder bin is connected to a furnace.

[0008] Furthermore, the pulverized coal separation unit includes a coarse powder separator and a fine powder separator, and the coarse powder separator is connected to the fine powder separator via a pulverized coal pipeline.

[0009] Furthermore, the coarse powder separator is connected to the outlet of the coal mill through a coal powder pipeline, and the fine powder separator is connected to the coal powder bin through a coal powder pipeline.

[0010] Furthermore, a wood chip separator is provided on the pipeline between the outlet of the coal mill and the coarse powder separator.

[0011] Furthermore, the coarse powder separator is connected to the inlet of the coal mill through a coal powder pipeline, and a counterweight type air lock is provided on the pipeline between the coarse powder separator and the inlet of the coal mill.

[0012] Furthermore, the inlet of the coal mill is connected to the raw coal bunker through a coal powder pipeline.

[0013] Furthermore, a booster fan is installed on the pipeline between the carbon dioxide storage tank and the air preheater.

[0014] Furthermore, a shut-off door and an adjusting door are provided on the pipeline between the outlet of the air preheater and the inlet of the coal mill.

[0015] Furthermore, the furnace is connected to the fine powder separator via a coal powder pipeline, a coal powder exhaust fan is provided on the coal powder pipeline between the furnace and the fine powder separator, and an inlet and an outlet of the coal powder exhaust fan are both provided with regulating doors.

[0016] Furthermore, the inlet of the coal mill, the outlet of the coal mill and the pulverized coal bin are all provided with temperature monitors and explosion-proof doors.

[0017] Compared with the prior art, the utility model has the following beneficial effects:

[0018] The utility model provides a carbon dioxide drying intermediate storage type pulverizing system, which is connected to an air preheater through a carbon dioxide storage tank, and the air preheater is connected to several coal mills. The carbon dioxide in the carbon dioxide storage tank enters the air preheater to be heated, and then enters the coal mill tank to mix with the raw coal and exchange heat. As the raw coal is crushed into coal powder, the moisture in the coal is also dried by the hot carbon dioxide gas. The coal mill is connected to the coal powder bin through a coal powder separation unit, and the coal powder bin is connected to the furnace. The coal powder and carbon dioxide gas mixture formed by pulverizing enters the coal powder bin after screening. The drying medium of the pulverizing system of the utility model adopts carbon dioxide, an inert gas. Compared with the existing pulverizing system that uses air as the drying medium, the possibility of explosion in the pulverizing system is completely eliminated. By using the carbon dioxide circulation inerting pulverizing system, the safe operating temperature of the pulverizing system is no longer limited by the volatile matter and explosion index of the coal type, and the upper limit of the heat exchange capacity of the boiler air preheater can be fully utilized to increase the medium temperature entering the pulverizing system. The utility model adopts a carbon dioxide drying central storage type pulverizing system, the drying output and explosion-proof capability of which are greatly improved, and the range of coal types that can be adapted to the corresponding power plant boiler is greatly broadened, which effectively improves the safety and reliability of power plant operation and the freedom of coal procurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a schematic structural diagram of the central storage type powder making system for carbon dioxide drying of the utility model.

[0021] Among them: 1-furnace, 2-pulverizer, 3-coarse powder separator, 4-fine powder separator, 5-coal powder bin, 6-powder exhaust fan, 7-boosting fan, 8-air preheater, 9-carbon dioxide storage tank. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0025] In the description of the embodiments of the present utility model, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the utility model product is usually placed when in use, it is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply 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 on the present utility model. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0026] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0027] In the description of the embodiments of the present utility model, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0028] The utility model is further described in detail below with reference to the accompanying drawings:

[0029] See also Figure 1The utility model is a carbon dioxide drying intermediate storage type pulverizing system, comprising a furnace 1, a coal mill 2, a coarse powder separator 3, a fine powder separator 4, a pulverized coal bin 5, a pulverized coal exhaust fan 6, a booster fan 7, an air preheater 8 and a carbon dioxide storage tank 9. The carbon dioxide storage tank 9 is connected to the inlet of the air preheater 8 through a pipeline, and the outlet of the air preheater 8 is connected to a plurality of coal mills 2 through pipelines, and the plurality of coal mills 2 are all connected to the coarse powder separator 3, the coarse powder separator 3 is connected to the fine powder separator 4 through a pulverized coal pipeline, the fine powder separator 4 is connected to the pulverized coal bin 5 through a pulverized coal pipeline, and the pulverized coal bin 5 is connected to the furnace 1 through a pulverized coal pipeline.

[0030] The carbon dioxide storage tank 9 is set at the zero-meter coal mill 2 area of ​​the boiler. The capacity of the carbon dioxide storage tank 9 can meet the operation requirements of the pulverizing system for one cycle, and it also has the conditions for online air replenishment. A booster fan 7 is installed on the pipeline between the carbon dioxide storage tank 9 and the air preheater 8. The carbon dioxide gas provided by the carbon dioxide storage tank 9 enters the air preheater 8 to be heated after the pressure is increased by the booster fan 7. The outlet of the air preheater 8 is connected to the inlet of the coal mill 2, and the inlet of the coal mill 2 is connected to the raw coal bin through the coal powder pipeline. The heated carbon dioxide gas enters the tank of the coal mill 2 to mix with the raw coal and exchange heat. As the raw coal is crushed into coal powder, the moisture in the coal is also dried by the hot carbon dioxide gas. A remotely operable shut-off door and a regulating door are set on the pipeline between the outlet of the air preheater 8 and the inlet of the coal mill 2 to adjust the flow of carbon dioxide gas entering the coal mill 2. The outlet of the coal mill 2 is connected to the coarse powder separator 3 through a coal powder pipeline, and the coarse powder separator 3 is connected to the fine powder separator 4 through a coal powder pipeline. A wood chip separator is provided on the pipeline between the outlet of the coal mill 2 and the coarse powder separator 3. The coal powder and carbon dioxide gas mixture formed by pulverizing leaves the outlet of the coal mill 2 and is screened by the coarse powder separator 3 and the fine powder separator 4 in turn. The coarse powder separator 3 is connected to the inlet of the coal mill 2 through a coal powder pipeline, and a counterweight air lock is provided on the pipeline between the coarse powder separator 3 and the inlet of the coal mill 2, which periodically returns the coarse powder coal particles to the inlet of the coal mill 2. The fine powder separator 4 is connected to the coal powder bin 5 through a coal powder pipeline, and the coal powder that meets the combustion fineness requirements finally enters the coal powder bin 5. The furnace 1 is connected to the fine powder separator 4 through a coal powder pipeline, and a powder exhaust fan 6 is provided on the coal powder pipeline between the furnace 1 and the fine powder separator 4, and the inlet and outlet of the powder exhaust fan 6 are both provided with regulating doors. The pulverizing exhaust gas containing a small amount of coal powder at the outlet of the subdividing separator 4 is pressurized by the pulverizing fan 6 and enters the furnace 1 through the exhaust gas burner nozzle to participate in the combustion reaction. The inlet and outlet of the coal mill 2 and the coal powder bin 5 are all equipped with temperature monitors and explosion-proof doors to relieve pressure and prevent serious accidents when abnormal leakage and explosion occur in the system, so as to protect the safety of personnel and equipment.

[0031] The pulverizing medium carbon dioxide of the utility model is provided by a carbon dioxide storage tank 9, and flows through a booster fan 7, an air preheater 8, a coal mill 2, a coarse powder separator 3, a fine powder separator 4 and a powder exhaust fan 6 in sequence, and finally enters the furnace 1. The raw coal is dried and ground in the coal mill 2 to produce pulverized coal, which, under the influence of carbon dioxide, passes through the coal mill 2, the coarse powder separator 3, the fine powder separator 4 in sequence, and finally enters the pulverized coal bin 5.

[0032] In some specific embodiments of the utility model, for one power plant boiler, there are 3 to 6 coal mills 2, and each coal mill 2 corresponds to one set of coarse powder separator 3, one set of fine powder separator 4, one coal powder bin 5 and one coal powder exhaust fan 6.

[0033] In a specific embodiment of the utility model, the carbon dioxide storage tank 9, the booster fan 7, the air preheater 8 and the coal mill 2 are connected through an air duct or an air pipe, and the coal mill 2, the coarse powder separator 3, the fine powder separator 4, the powder exhaust fan 6 and the furnace 1 are connected through a coal powder pipeline.

[0034] The working principle of the carbon dioxide drying intermediate storage type powder making system of the utility model is:

[0035] When the system is running, the carbon dioxide gas provided by the carbon dioxide storage tank 9 is pressurized to 2-4 kPa by the booster fan 7, then enters the air preheater 8 to be heated to 300-380°C, and then enters the tank body of the coal mill 2 to mix with the raw coal and exchange heat. As the raw coal is crushed into coal powder, the moisture in the coal is also dried by the hot carbon dioxide gas. Subsequently, the coal powder and carbon dioxide gas mixture formed by pulverizing leaves the outlet of the coal mill 2 with a temperature ≥200°C, and is screened by the coarse powder separator 3 and the fine powder separator 4 in turn, and the coarse coal powder particles are returned to the cylinder of the coal mill 2. The coal powder that meets the combustion fineness requirements finally enters the coal powder bin 5. The pulverizing exhaust gas containing a small amount of coal powder at the outlet of the fine powder separator 4 is pressurized by the powder exhaust fan 6, and enters the furnace 1 through the exhaust gas burner nozzle arranged on the furnace 1 to participate in the combustion reaction.

[0036] The drying medium of the pulverizing system in this utility model adopts carbon dioxide, which improves the upper limit of the operating temperature of the coal mill and the explosion-proof performance, and broadens the coal adaptability of the power plant boiler. The technology is simple to construct, and most of the equipment of the central storage pulverizing system can be retained. Only a new carbon dioxide storage tank and its affiliated pipelines are needed to achieve the technical goal, completely avoiding the risk of explosion. At the same time, the drying output of the pulverizing system is greatly improved. It has no impact on the existing operating equipment and has positive significance for the safe and reliable operation of the boiler unit.

[0037] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be subject to various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A carbon dioxide drying intermediate storage type powder making system, characterized in that: It comprises a furnace (1), a pulverized coal bin (5), an air preheater (8), a carbon dioxide storage tank (9) and a pulverized coal separation unit; The carbon dioxide storage tank (9) is connected to the inlet of the air preheater (8), the outlet of the air preheater (8) is connected to a plurality of coal mills (2), the plurality of coal mills (2) are connected to a coal powder separation unit, the coal powder separation unit is connected to a coal powder bin (5), and the coal powder bin (5) is connected to the furnace (1).

2. A carbon dioxide drying intermediate storage type powder making system according to claim 1, characterized in that: The coal powder separation unit comprises a coarse powder separator (3) and a fine powder separator (4), and the coarse powder separator (3) is connected to the fine powder separator (4) via a coal powder pipeline.

3. A carbon dioxide drying intermediate storage type powder making system according to claim 2, characterized in that: The coarse powder separator (3) is connected to the outlet of the coal mill (2) through a coal powder pipeline, and the fine powder separator (4) is connected to the coal powder bin (5) through a coal powder pipeline.

4. A carbon dioxide drying intermediate storage type powder making system according to claim 3, characterized in that: A wood chip separator is provided on the pipeline between the outlet of the coal mill (2) and the coarse powder separator (3).

5. A carbon dioxide drying intermediate storage type powder making system according to any one of claims 2 to 4, characterized in that: The coarse powder separator (3) is connected to the inlet of the coal mill (2) through a coal powder pipeline, and a counterweight type air lock is provided on the pipeline between the coarse powder separator (3) and the inlet of the coal mill (2).

6. The carbon dioxide drying intermediate storage type powder making system according to claim 1, characterized in that: The inlet of the coal mill (2) is connected to the raw coal bunker via a pulverized coal pipeline.

7. The carbon dioxide drying intermediate storage type powder making system according to claim 1, characterized in that: A booster fan (7) is installed on the pipeline between the carbon dioxide storage tank (9) and the air preheater (8).

8. The carbon dioxide drying intermediate storage type powder making system according to claim 1, characterized in that: A shutoff valve and an adjusting valve are arranged on the pipeline between the outlet of the air preheater (8) and the inlet of the coal mill (2).

9. The carbon dioxide drying intermediate storage type powder making system according to claim 1, characterized in that: The furnace (1) is connected to the fine powder separator (4) via a coal powder pipeline, and a coal powder exhaust fan (6) is provided on the coal powder pipeline between the furnace (1) and the fine powder separator (4), and an inlet and an outlet of the coal powder exhaust fan (6) are both provided with regulating doors.

10. The carbon dioxide drying intermediate storage type powder making system according to claim 1, characterized in that: The inlet of the coal mill (2), the outlet of the coal mill (2) and the pulverized coal bin (5) are all provided with temperature monitoring instruments and explosion-proof doors.

Images