阅读说明：本技术 一种锅炉飞灰复燃装置及方法 (Boiler fly ash reburning device and method ) 是由 赵树平 *** 胡忠 张贞元 田晓飞 汪飞 郝广利 王继胜 周涛 于 2019-11-14 设计创作，主要内容包括：本发明公开了一种锅炉飞灰复燃装置,涉及锅炉技术领域,锅炉上端与旋风分离器相连通,旋风分离器与锅炉的辅助受热面相连接,辅助受热面下端与静电除尘器相连通,静电除尘器与飞灰装置相连通,飞灰装置与返料箱相连接,返料箱的料腿与锅炉炉膛相连接,返料器与返料风机相连接。本发明主要是把静电除尘器收集下来的锅炉飞灰通过飞灰装置回送到锅炉的返料器料腿,随返料灰一起进入炉膛参加燃烧,这样就增加了炉膛中的循环灰量,降低了床温,提高了炉膛差压,也提高了炉膛出口温度,降低了飞灰含碳量,增大了锅炉对煤种的适应范围；通过控制飞灰返灰量达到了氨水的温度反应区间使氨水与烟气中的氮氧化物充分反应,减少了氨逃逸。(The invention discloses a boiler fly ash reburning device, which relates to the technical field of boilers, wherein the upper end of a boiler is communicated with a cyclone separator, the cyclone separator is connected with an auxiliary heating surface of the boiler, the lower end of the auxiliary heating surface is communicated with an electrostatic dust collector, the electrostatic dust collector is communicated with a fly ash device, the fly ash device is connected with a material returning box, a material leg of the material returning box is connected with a boiler furnace, and a material returning device is connected with a material returning fan. The boiler fly ash collected by the electrostatic dust collector is returned to a charge leg of a material returning device of the boiler through the fly ash device and enters a hearth to be combusted along with the returned ash, so that the circulating ash amount in the hearth is increased, the bed temperature is reduced, the differential pressure of the hearth is improved, the outlet temperature of the hearth is also improved, the carbon content of the fly ash is reduced, and the application range of the boiler to coal is enlarged; the temperature reaction interval of the ammonia water is reached by controlling the ash return amount of the fly ash, so that the ammonia water and the nitrogen oxide in the flue gas are fully reacted, and the ammonia escape is reduced.)

1. A boiler fly ash reburning device is characterized in that: the device comprises a boiler (5), wherein the upper end of the boiler (5) is communicated with a cyclone separator (7), the air outlet end of the cyclone separator (7) is connected with an auxiliary heating surface of the boiler (5), the lower end of the auxiliary heating surface is communicated with an electrostatic dust collector (1), the ash outlet end of the electrostatic dust collector (1) is communicated with a fly ash device, the fly ash device is connected with an ash storage room, the fly ash device is also connected with a dipleg of a return box, the dipleg of the return box is connected with a hearth of the boiler (5), and the lower end of a return feeder is connected with a return fan (9).

2. The boiler fly ash afterburning apparatus of claim 1, wherein: the auxiliary heating surface comprises a superheater (2), an economizer (3) and an air preheater (4), the superheater (2), the economizer (3) and the air preheater (4) are sequentially connected, the superheater (2) is communicated with a cyclone separator (7), and the air preheater (4) is communicated with the electrostatic dust collector (1).

3. The boiler fly ash afterburning apparatus of claim 1, wherein: the fly ash device comprises a powder pump (8), an ash conveying fan (10) and an ash conveying pipeline, wherein an inlet of the powder pump (8) is connected with an ash outlet end of the electrostatic dust collector (1), an outlet of the powder pump (8) is communicated with the ash conveying pipeline, and the front end of the ash conveying pipeline is communicated with the ash conveying fan (10).

4. The boiler fly ash afterburning apparatus of claim 1, wherein: the ash conveying fan (10) and the material returning fan (9) are both Roots fans.

5. The boiler fly ash afterburning apparatus of claim 1, wherein: the two return boxes (8) and the two cyclone separators (7) are arranged.

6. The boiler fly ash afterburning apparatus of claim 1, wherein: the flying ash device is provided with two.

7. A method for reburning boiler fly ash is characterized in that: the method for reburning the boiler fly ash comprises the following steps: boiler (5) furnace export exhaust have the flue gas of granule to get into cyclone (7), separate out the cigarette ash of great granule under centrifugal force in cyclone (7), the cigarette ash of great granule of separating gets into to get back to furnace through the effect of returning to material fan (9) in the returning charge ware and burns again, and play the effect of control bed temperature, in addition, the partial granule cigarette ash that collects electrostatic precipitator (1) passes through the flying dust device and returns back to the returning charge ware of boiler (5), get into furnace along with separating out the cigarette ash of great granule and participate in the burning together.

8. The boiler fly ash afterburning method of claim 7, wherein: the residual small-particle soot collected by the electrostatic precipitator (1) enters a soot storage room through another fly ash device for temporary storage.

Technical Field

The invention relates to the technical field of boilers, in particular to a device and a method for reburning boiler fly ash.

Background

The design of the circulating fluidized bed boiler of the existing thermal power plant is generally a novel domestic boiler type with low bed temperature, low bed pressure and low nitrogen combustion, and the original discharge amount of nitrogen oxides is 70-160mg/m³The Nox emission standard executed 10 months before 2017 is less than or equal to 200mg/m³. In the period, the flue gas emission requirement can be met without adopting a SNCR ammonia water feeding denitration mode. After 10 months in 2017, environmental protection departments in many regions implement ultra-low emission standards, and the emission standard of Nox is less than or equal to 50mg/m³(ii) a In order to achieve standard emission, the boiler adopts an SNCR (selective non-catalytic reduction) denitration mode, and a denitration agent is generally ammonia water or urea. The consumption of designed ammonia water is generally 0.3-0.5 ton/h, and needs to be adjusted according to the original discharge amount of oxynitride of a boiler; the original discharge amount is different according to the temperature of the hearth and the outlet temperature of the hearth, and the reaction temperature is controlled to be between 850 ℃ and 930 ℃ in general. In order to ensure the sulfur dioxide to reach the standard, the sulfur content in the raw coal needs to be controlled at a lower level (below 0.8%). In actual operation, the using amount of the ammonia water reaches 0.5-0.8 ton/h, which is obviously larger than the design value, and the carbon content of the fly ash reaches more than 12% at most; for the situation, the research and analysis are earnestly carried out; there are two main reasons for agreement: firstly, the bed temperature of the boiler is higher, and reaches over 980 ℃ under high load, so that oxynitride is sharply increased at the temperature, and the used ammonia water is increased; secondly, the temperature of the outlet of the hearth is low, the load is difficult to be lifted, and the low differential pressure of the hearth is determined to be the main reason through careful analysis, and is closely related to the circulating ash of the boilerTherefore, it is urgent to increase the circulating ash amount while performing operation adjustment.

Disclosure of Invention

The invention aims to provide a boiler fly ash reburning device and a boiler fly ash reburning method, which are used for solving the problem of improving the circulating ash amount in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme:

the boiler fly ash reburning device comprises a boiler, wherein the upper end of the boiler is communicated with a cyclone separator, the air outlet end of the cyclone separator is connected with an auxiliary heating surface of the boiler, the lower end of the auxiliary heating surface is communicated with an electrostatic dust collector, the ash outlet end of the electrostatic dust collector is communicated with a fly ash device, the fly ash device is connected with an ash storage room, the fly ash device is also connected with a material leg of a return box, the material leg of the return box is connected with a boiler hearth, and the lower end of a return feeder is connected with a return fan.

Further, the auxiliary heating surface comprises a superheater, an economizer and an air preheater, the superheater, the economizer and the air preheater are sequentially connected, the superheater is communicated with the cyclone separator, and the air preheater is communicated with the electrostatic dust collector.

Furthermore, the fly ash device comprises a powder pump, an ash conveying fan and an ash conveying pipeline, wherein an inlet of the powder pump is connected with an ash outlet end of the electrostatic dust collector, an outlet of the powder pump is communicated with the ash conveying pipeline, and the front end of the ash conveying pipeline is communicated with the ash conveying fan.

Furthermore, the ash conveying fan and the material returning fan are both Roots fans.

Furthermore, the material return box and the cyclone separator are both provided with two.

Further, the flying ash device is provided with two flying ash devices.

A method for reburning boiler fly ash comprises the following steps: boiler furnace export exhaust has the flue gas of tiny granule to get into cyclone, separate out the cigarette ash of great granule under the centrifugal force effect in cyclone, the cigarette ash of great granule of separating gets back to furnace through the effect of returning the material fan in getting into the returning charge ware and burns once more, and play the effect of control bed temperature, in addition return the returning charge ware of boiler through the fly ash device to the part tiny granule cigarette ash that electrostatic precipitator collected, get into furnace along with separating out the cigarette ash of great granule and participate in the burning together.

Further, the residual small particle soot collected by the electrostatic precipitator is fed to a soot storage room through another fly ash device for temporary storage.

Compared with the prior art, the invention has the beneficial effects that: the invention mainly returns the boiler fly ash collected by the electrostatic precipitator to the return feeder leg of the boiler through the fly ash device, and enters the hearth to burn along with the return ash, thus increasing the circulating ash amount in the hearth, reducing the bed temperature, improving the hearth differential pressure and improving the hearth outlet temperature, and the fly ash return ash amount is controlled to reach the temperature reaction interval (800-; and because the fly ash is re-combusted again, the carbon content of the fly ash is also reduced, and simultaneously, the load-lifting capacity of the boiler is greatly enhanced due to the improvement of the circulating ash content. Meanwhile, the ash content requirement of the purchased coal can be properly reduced, the calorific value of the purchased coal is improved, and the transportation and use cost is reduced. The coal ash which becomes solid waste is conveyed back to the boiler and enters the circulating fluidized system again, so that the ash content is increased, and the fly ash returning amount is controlled by adjusting the ash feeding amount of the feeder. The pneumatic ash conveying system sets the material level to ensure the supply amount of the returned fly ash.

Drawings

Fig. 1 is a schematic view of the overall structure of the present invention.

In the figure: 1 electrostatic precipitator, 2 superheater, 3 economizer, 4 air preheater, 5 boiler, 6 cyclone separator, 7 return box, 8 powder pump, 9 return fan and 10 ash conveying fan.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.