阅读说明：本技术 一种降低高钠煤沾污结焦及脱除重金属的锅炉系统和方法 (Boiler system and method for reducing contamination and coking of high-sodium coal and removing heavy metal ) 是由 张永生 郭磊 王家伟 汪涛 潘伟平 于 2019-10-29 设计创作，主要内容包括：本发明涉及燃煤发电技术领域,尤其涉及一种降低高钠煤沾污结焦及脱除重金属的锅炉系统和方法。该锅炉系统包括：锅炉,内部设置有喷射管道；除尘器,与所述锅炉连通；研磨机,一端与所述除尘器连通,另一端与所述喷射管道连通,所述研磨机被配置为将从所述除尘器中获取的飞灰进行研磨。本发明提供的锅炉系统通过将从除尘器中获取的飞灰进行研磨后,增加了飞灰的比表面积,产生了富含氧化铝和氧化硅的新鲜表面,研磨后的飞灰喷射到锅炉中后,促进氧化铝和氧化硅与高钠煤燃烧产生的含钠化合物反应生成硅铝酸钠等稳定物质；同时新鲜表面具有较高的表面能,能够进一步吸附烟气中的重金属,从而降低了烟气中含钠化合物和重金属的含量。(The invention relates to the technical field of coal-fired power generation, in particular to a boiler system and a method for reducing contamination and coking of high-sodium coal and removing heavy metals. The boiler system includes: a boiler, inside which an injection pipeline is arranged; a dust collector communicated with the boiler; a grinder having one end communicating with the dust collector and the other end communicating with the injection duct, the grinder being configured to grind the fly ash taken from the dust collector. According to the boiler system, after the fly ash obtained from the dust remover is ground, the specific surface area of the fly ash is increased, a fresh surface rich in alumina and silica is generated, and after the ground fly ash is sprayed into a boiler, the alumina and the silica are promoted to react with sodium-containing compounds generated by combustion of high-sodium coal to generate stable substances such as sodium aluminosilicate and the like; meanwhile, the fresh surface has higher surface energy, and can further adsorb heavy metal in the flue gas, thereby reducing the content of sodium compounds and heavy metal in the flue gas.)

1. A boiler system for reducing coking contamination and heavy metal removal of high-sodium coal is characterized by comprising:

a boiler (1) internally provided with an injection duct (11), said boiler (1) being configured to provide a site for combustion of high-sodium coal and to output fumes resulting from the combustion;

a dust separator (2) in communication with the boiler (1), the dust separator (2) configured to collect fly ash in the flue gas;

a grinder (3) communicating with the dust collector (2) at one end and with the injection duct (11) at the other end, the grinder (3) being configured to grind the fly ash taken from the dust collector (2) and to inject the ground fly ash into the boiler (1) through the injection duct (11).

2. The boiler system according to claim 1, further comprising an air preheater (4) arranged between the boiler (1) and the dust separator (2), wherein an air inlet pipe (41) and an induced draft fan (42) are arranged between the air preheater (4) and the grinding mill (3);

air enters from the air inlet pipeline (41), is heated by the air preheater (4), and is driven by the induced draft fan (42) to enter the grinding machine (3).

3. A boiler system according to claim 1, characterized in that an ash hopper (22) and a material conveyor (23) are arranged between the mill (3) and the dust separator (2), and fly ash taken from the dust separator (2) is fed into the mill (3) through the ash hopper (22) and the material conveyor (23) in turn.

4. The boiler system according to claim 1, wherein the fly ash is captured in an electric field (21) of the precipitator (2).

5. A boiler system according to claim 1, characterized in that a halogen additive is provided in the mill (3).

6. The boiler system according to any one of claims 1-5, further comprising:

a first water washing device (51) configured to wash the pulverized high-sodium coal with water;

a first drying device (52) connected to the first water washing device (51), the first drying device (52) being configured to dry the high-sodium coal after water washing;

a wastewater treatment device (53) connected with the first water washing device (51), the wastewater treatment device (53) being configured to treat the first high-sodium water discharged via the first water washing device (51).

7. The boiler system of claim 6, further comprising:

a second water washing device (61) configured to wash the fly ash taken from the dust separator (2);

a second drying device (62) connected to the second water washing device (61), the second drying device (62) being configured to dry the fly ash after washing;

the wastewater treatment device (53) is further connected with the second water washing device (62), and the wastewater treatment device (53) is configured to treat the second high-sodium water discharged through the second water washing device (61).

8. A method for reducing coking contamination and removing heavy metals from high-sodium coal, using the boiler system of any one of claims 1-7, the method comprising the steps of:

obtaining part of fly ash in the dust remover (2);

the fly ash is ground and then injected into the boiler (1).

9. The method according to claim 8, wherein said injecting said fly ash into the boiler (1) after grinding comprises:

and mixing the air heated by the air preheater (4) with the ground fly ash, and then injecting the mixture into the boiler (1).

10. The method according to claim 8, wherein injecting the fly ash into the boiler (1) after the step of grinding further comprises:

mixing and grinding the halogen additive and the fly ash together, and then spraying the mixture into the boiler (1) together.

Technical Field

The invention relates to the technical field of coal-fired power generation, in particular to a boiler system and a method for reducing contamination and coking of high-sodium coal and removing heavy metals.

Background

The high-sodium coal refers to a special coal with high content of alkali metal compounds in the coal, and sodium-based compounds are more in various alkali metal compounds, so the high-sodium coal is called as the high-sodium coal. At present, high-sodium coal in China is mainly concentrated in the eastern quasi-east coal fields of the eastern part of the Sinkiang quasi-Pascal basin, and the high-sodium coal can be seriously stained and coked in the practical application process, so that the high-sodium coal becomes a main problem which troubles the safe operation of a power plant, and the burning of the high-sodium coal is seriously restricted. The main reason for the contamination and coking of the high-sodium coal is that during the combustion process, the melting point of sodium-containing compounds in the flue gas is low (except sodium aluminosilicate), gasification can occur at the normal combustion temperature of the boiler, and the temperature reduction and condensation of the gasified sodium-containing compounds are the main reasons for causing the contamination and coking.

Among the existing technologies for controlling the coking of the sticky dirt of the high-sodium coal, for example, a method (CN102759117A) for alleviating the boiler slagging by utilizing the fly ash circulation discloses that the detection of different SiO of the fly ash of the burning coal is based on₂/Al₂O₃The ratio of (a) to (b) is used to determine whether fly ash is incorporated into the raw coal. The method provides a thought for mixing the fly ash into the coal powder for combustion, but the fly ash formed after the combustion of the coal is a closed spheroid, the specific surface area of the closed spheroid is very small, and the reaction of the fly ash and sodium is difficult to occur.

For another example, a method (CN105154168A) for alleviating the slag formation of high-sodium coal by using sodium-removed fly ash produced by a boiler as an additive is disclosed, which comprises washing the fly ash in multiple stages with water or solution, dissolving and removing the soluble sodium component in the fly ash, and then mixing the sodium-removed fly ash with raw coal according to Na in a mixed coal sample₂And determining the addition proportion by taking the standard that the mass percent of O is less than 2% and the softening temperature of the mixed ash sample is more than 1250 ℃, and feeding the mixture into a hearth to participate in combustion. Although the method can remove the sodium element in the high-sodium coal with higher efficiency, the operation is complex, the system is complicated, and the initial stage isThe investment and operation costs are high.

In addition, in the coal combustion process, heavy metal pollutants such As mercury (Hg), arsenic (As), lead (Pb), cadmium (Cd), chromium (Cr) and the like are also generated in the flue gas, so that it is necessary to reduce the heavy metals in the flue gas.

In view of the foregoing, there is a need for a boiler system for burning high sodium coal and a method of operating the same to solve the above problems.

Disclosure of Invention

The embodiment of the invention provides a boiler system and a method for reducing contamination and coking of high-sodium coal and removing heavy metals, so as to reduce the content of sodium-containing compounds and heavy metals in flue gas.

The invention provides a boiler system for reducing contamination and coking of high-sodium coal and removing heavy metal, which comprises:

a boiler having an injection duct disposed therein, the boiler being configured to provide a location for combustion of high-sodium coal and to output flue gas resulting from the combustion;

a dust separator in communication with the boiler, the dust separator configured to collect fly ash in the flue gas;

a grinder having one end communicating with the dust collector and the other end communicating with the injection duct, the grinder being configured to grind the fly ash taken from the dust collector and inject the ground fly ash into the boiler through the injection duct.

Optionally, the system further comprises an air preheater arranged between the boiler and the dust remover, and an air inlet pipeline and an induced draft fan are arranged between the air preheater and the grinding mill;

air enters from the air inlet pipeline, is heated by the air preheater and then is driven by the draught fan to enter the grinding machine.

Optionally, an ash hopper and a material conveyor are arranged between the grinding mill and the dust remover, and the fly ash obtained from the dust remover is sent into the grinding mill through the ash hopper and the material conveyor in sequence.

Optionally, the fly ash is captured as fly ash in an electric field of the precipitator.

Optionally, a halogen additive is provided within the mill.

Optionally, the method further comprises:

a first water washing device configured to wash the pulverized high-sodium coal with water;

a first drying device connected with the first water washing device, wherein the first drying device is configured to dry the washed high-sodium coal;

a wastewater treatment device connected with the first water washing device, the wastewater treatment device configured to treat the first high-sodium water discharged via the first water washing device.

Optionally, the method further comprises:

a second water washing device configured to wash the fly ash obtained from the dust collector with water;

a second drying device connected to the second water washing device, the second drying device being configured to dry the fly ash after washing;

the wastewater treatment facility is also connected to the second water wash facility, the wastewater treatment facility being configured to treat second high sodium water discharged via the second water wash facility.

The second aspect of the invention also provides a method for reducing the contamination coking and removing the heavy metal of the high-sodium coal, which adopts the boiler system for reducing the contamination coking and removing the heavy metal of the high-sodium coal, and comprises the following steps:

obtaining part of fly ash in a dust remover;

and grinding the fly ash, and spraying the ground fly ash into a boiler.

Optionally, the step of spraying the pulverized ash into the boiler after grinding comprises:

and mixing the air heated by the air preheater with the ground fly ash, and then spraying the mixture into the boiler together.

Optionally, the injecting the pulverized ash into the boiler after the grinding further comprises:

and mixing and grinding the halogen additive and the fly ash together, and then spraying the mixture into the boiler together.

Has the advantages that:

according to the boiler system, after the fly ash obtained from the dust remover is ground, the specific surface area of the fly ash is increased, a fresh surface rich in alumina and silica is generated, and after the ground fly ash is sprayed into a boiler, the alumina, the silica and sodium-containing compounds generated by combustion of high-sodium coal are promoted to react to generate stable substances such as sodium aluminosilicate and the like, so that the proportion of gas-phase sodium is reduced, the proportion of sodium in ash is increased, and the serious fouling and coking of a heat exchange surface of the boiler caused by combustion of the high-sodium coal are reduced; meanwhile, the fresh surface has higher surface energy, and can further adsorb heavy metal in the flue gas, thereby reducing the content of sodium compounds and heavy metal in the flue gas.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

Drawings

FIG. 1 is a schematic diagram of a boiler system provided by an embodiment of the present invention;

FIG. 2 is a schematic diagram of the high sodium coal and fly ash pretreatment provided by an embodiment of the present invention.

Reference numerals:

1-a boiler;

11-an injection conduit;

12-a burner;

2-a dust remover;

21-an electric field;

22-ash bucket;

23-a material conveyor;

3-a grinder;

4-an air preheater;

41-an air inlet pipeline;

42-a draught fan;

51-a first water washing device;

52-first drying means;

53-wastewater treatment equipment;

61-a second water washing device;

62-a second drying device;

7-a desulfurizing tower;

8-chimney.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In the description of the present invention, unless explicitly stated or limited otherwise, the terms "first", "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; the term "plurality" means two or more unless specified or indicated otherwise; the terms "connected," "fixed," and the like are to be construed broadly and may, for example, be fixedly connected, detachably connected, integrally connected, or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the description of the present invention, it should be understood that the terms "upper" and "lower" as used in the description of the embodiments of the present invention are used in the angle shown in the drawings, and should not be construed as limiting the embodiments of the present invention. In addition, in this context, it will also be understood that when an element is referred to as being "on" or "under" another element, it can be directly on "or" under "the other element or be indirectly on" or "under" the other element via an intermediate element.

FIG. 1 is a schematic diagram of a boiler system for reducing coking contamination and removing heavy metals from high-sodium coal according to an embodiment of the present invention. The boiler system comprises at least a boiler 1, a dust separator 2 and a grinding mill 3, wherein:

the inside of the boiler 1 is provided with an injection pipeline 11, and the boiler 1 is configured to provide a place for high-sodium coal combustion and output flue gas generated by the combustion; the dust remover 2 is communicated with the boiler 1, and the dust remover 2 is configured to collect fly ash in the flue gas; one end of the grinding mill 3 communicates with the dust collector 2 and the other end communicates with the injection duct 11, and the grinding mill 3 is configured to grind the fly ash taken from the dust collector 2 and inject the ground fly ash into the boiler 1 through the injection duct 11. According to the boiler system for burning the high-sodium coal, provided by the invention, after the fly ash obtained from the dust remover 2 is ground, the specific surface area of the fly ash is increased, a fresh surface rich in alumina and silica is generated, and after the ground fly ash is injected into the boiler 1, the alumina and the silica are promoted to react with sodium-containing compounds generated by burning the high-sodium coal to generate stable substances such as sodium aluminosilicate and the like, so that the proportion of gas-phase sodium is reduced, the proportion of sodium in ash is increased, and the serious sticky coking of a heat exchange surface of the boiler caused by burning the high-sodium coal is reduced; meanwhile, the fresh surface has higher surface energy, and can further adsorb heavy metal in the flue gas, thereby reducing the content of sodium compounds and heavy metal in the flue gas.

It will be appreciated that the mill 3 may be any type of mill, such as a horizontal mill, a vertical mill, an air mill, etc., as long as it is ensured that the fly ash can be milled to a smaller particle size, so that the specific surface area of the fly ash is increased, and a fresh surface rich in alumina and silica is created, which can simultaneously react with and adsorb the sodium-containing compounds and heavy metals in the flue gas, thereby reducing the content of the sodium-containing compounds and heavy metals.

In the working process of the grinder 3, the grinding time is a factor influencing the fly ash removal effect, and the best fly ash removal effect cannot be achieved by too short grinding time or too long grinding time. Preferably, the grinding time may be 10min to 30min, so that not only too much electric energy is not wasted (since the grinder 3 is driven by electric energy), but also the excellent fly ash removal effect is ensured. The grinding time is the time when the fly ash is in the grinder 3 in operation, so that each batch of fly ash can be sent to the grinder 3 for grinding, or each batch of fly ash can be continuously sent to the grinder 3 for grinding, and in the latter operation mode, the time difference between the fly ash entering the grinder 3 and the fly ash leaving the grinder 3 is ensured to be 10min-30 min.

In addition, the injection duct 11 is inserted into the boiler from the wall of the boiler 1, the injection duct 11 includes a plurality of nozzles arranged uniformly, and the injection range of the plurality of nozzles can be larger than the cross-sectional area of the furnace to improve the contact probability of the injected fly ash and the sodium-containing compound. The boiler 1 is also provided with a burner 12, and the injection pipe 11 can be positioned above the burner 12, and the longitudinal distance between the two cannot be too close or too far, because too close or too far cannot sufficiently ensure sufficient contact between the high-sodium coal and the injected fly ash.

Further, the boiler system further comprises an air preheater 4 arranged between the boiler 1 and the dust remover 2, an air inlet pipeline 41 and an induced draft fan 42 are arranged between the air preheater 4 and the grinding machine 3, air enters from the air inlet pipeline 41, and is heated by the air preheater 4 and then enters the grinding machine 3 through the induced draft fan 42. In the embodiment, the high-temperature air is used as a carrier to convey the ground fly ash, so that the ground fly ash has a certain temperature (usually 50-80 ℃) when entering a hearth, the temperature difference of the fly ash and the high-sodium coal can be reduced, and the uniform mixing of the fly ash and the high-sodium coal and the heat energy loss of combustion are further ensured.

Further, an ash hopper 22 and a material conveyor 23 are provided between the grinding mill 3 and the dust collector 2, and the fly ash taken from the dust collector 2 is fed into the grinding mill 3 through the ash hopper 22 and the material conveyor 23 in this order. Alternatively, the material conveyor 23 includes a screw feeder and a variable frequency feeder, so that the fly ash in the ash hopper 22 is continuously fed into the grinding mill 3 conveniently and quickly.

Further, the obtained fly ash is fly ash in an electric field 21 of the dust collector 2. Generally, the dust collector 2 has four electric fields, the fly ash in the flue gas gradually becomes smaller in particle size along the directions of the electric fields 21 to four, and the fly ash with larger particle size is best ground, i.e. is most easily damaged to generate a fresh surface.

It can be understood that the amount of the injected fly ash is also a factor that affects the fly ash removal performance, and the optimum fly ash removal performance cannot be achieved by too little or too much injected fly ash. Preferably, the ratio of the silicon content in the amount of added fly ash to the sodium content in the high sodium coal is between 1 and 3, so that an approximate amount of fly ash addition can be determined.

Further, a halogen additive, such as chloride, bromide, etc., is provided in the mill 3, so that Hg can be added by using chloride or bromide ions⁰Oxidation to Hg²⁺Thereby ensuring that the fly ash can further adsorb heavy metals (such as mercury) in the flue gas. This is because: oxidized mercury (Hg)²⁺) A part of the fly ash particles is attached to fly ash particles and thus removed by the dust removing equipment, and the water-soluble property of the fly ash particles makes it possible to remove a part of the fly ash particles in wet desulfurization; and elemental mercury (Hg)⁰) The physical and chemical properties of the compound are the most stable and the compound is the most difficult to remove by the existing atmospheric pollution control equipment.

Further, the boiler system also comprises an electric control device which can be electrically connected with the induced draft fan 42, the material conveyor 23 and the grinding mill 3 so as to realize the automation and continuous operation of the whole boiler system. The boiler system also comprises a desulfurizing tower 7 and a chimney 8, so that flue gas generated by combustion is discharged after being desulfurized.

Fig. 2 is a schematic diagram illustrating the principle of high-sodium coal and fly ash pretreatment according to an embodiment of the present invention. The boiler system further comprises a device for pretreating the high-sodium coal, and specifically may comprise a first water washing device 51, a first drying device 52 and a wastewater treatment device 53, wherein:

the first washing device 51 is configured to wash the pulverized high-sodium coal with water, the first drying device 52 is connected to the first washing device 51, the first drying device 52 is configured to dry the washed high-sodium coal, the wastewater treatment device 53 is connected to the first washing device 51, and the wastewater treatment device 53 is configured to treat the first high-sodium water discharged through the first washing device 51. The first water washing device 51 removes water-soluble sodium in the high-sodium coal to obtain low-sodium coal (only sodium in the high-sodium coal is less, but sodium in the common coal is still more) and first high-sodium water, the wet low-sodium coal is dried by the first drying device 52 and then sent to the hearth, meanwhile, the first high-sodium water is sent to the wastewater treatment device 53 to obtain low-sodium water and sodium salt byproducts, and the obtained low-sodium water can be recycled to the first water washing device 51 for continuous use, so that the water is recycled.

Further, the boiler system further includes a device for pretreating fly ash, and specifically may include a second water washing device 61, a second drying device 62 and a wastewater treatment device 53, wherein:

the second water washing device 61 is configured to wash the fly ash obtained from the dust collector 2, the second drying device 62 is connected to the second water washing device 61, the second drying device 62 is configured to dry the washed fly ash, the wastewater treatment device 53 is further connected to the second water washing device 62, and the wastewater treatment device 53 is configured to treat the second high-sodium water discharged through the second water washing device 61. The second water washing device 61 removes water-soluble sodium in the fly ash to obtain low sodium ash and second high sodium water, then the wet low sodium ash is dried by the second drying device 62 and sent to the grinding mill 3, meanwhile, the second high sodium water is sent to the wastewater treatment device 53 to obtain low sodium water and sodium salt byproducts, and the obtained low sodium water can be recycled to the second water washing device 61 for continuous use, thus realizing the recycling of water.

The invention also provides a method for reducing the contamination coking and removing the heavy metal of the high-sodium coal, which adopts the boiler system for reducing the contamination coking and removing the heavy metal of the high-sodium coal, and comprises the following steps:

s1, obtaining part of fly ash in the dust collector 2;

specifically, a part of the fly ash of an electric field 21 of the dust collector 2 is collected and collected into an ash hopper 22 located below the electric field 21.

S2, grinding the fly ash and then spraying the ground fly ash into the boiler 1;

specifically, the collected fly ash is ground by the grinder 3 for 10min to 30min and then is uniformly sprayed into the boiler 1 through the spray pipe 11.

S21, mixing the air heated by the air preheater 4 with the ground fly ash, and then injecting the mixture into the boiler 1;

specifically, an air inlet pipeline 41 and an induced draft fan 42 are arranged between the air preheater 4 and the grinding mill 3, air enters from the air inlet pipeline 41, and is heated by the air preheater 4 and then enters the grinding mill 3 under the drive of the induced draft fan 42.

S22, mixing and grinding the halogen additive and the fly ash together, and then injecting the mixture into the boiler 1 together.

According to the method for reducing the contamination coking of the high-sodium coal and removing the heavy metals, provided by the invention, the fly ash obtained from the dust remover 2 is ground, the specific surface area of the fly ash is increased, a fresh surface rich in alumina and silica is generated, and the ground fly ash is sprayed into the boiler 1 to promote the reaction of the alumina and the silica and sodium-containing compounds generated by the combustion of the high-sodium coal to generate stable substances such as sodium aluminosilicate and the like, so that the proportion of gas-phase sodium is reduced, the proportion of sodium in ash is increased, and the serious contamination coking of a heat exchange surface of the boiler caused by the combustion of the high-sodium coal is reduced; meanwhile, the fresh surface has higher surface energy, and can further adsorb heavy metal in the flue gas, thereby reducing the content of sodium compounds and heavy metal in the flue gas.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.