CN114777113A

CN114777113A - Fly ash recycling system of carbon-containing fluidized bed

Info

Publication number: CN114777113A
Application number: CN202210597519.7A
Authority: CN
Inventors: 潘峰; 蒋芹; 李耀拉; 胡伟; 马广苗
Original assignee: Keda Clean Energy Co Ltd
Current assignee: Keda Clean Energy Co Ltd
Priority date: 2022-05-30
Filing date: 2022-05-30
Publication date: 2022-07-22

Abstract

The invention discloses a fly ash recycling system of a carbon-containing fluidized bed, and belongs to the technical field of gasification furnace ignition systems. The fly ash pre-combustion device comprises a fluidized bed boiler and a pulverized coal bin, wherein the fluidized bed boiler comprises a secondary air reaction area in the middle and a fly ash pre-combustion area at the bottom, fly ash in the pulverized coal bin is input into the fly ash pre-combustion area, the fly ash pre-combustion area is an oxygen-rich area, secondary air is introduced into the secondary air reaction area, and a high-temperature gas-solid mixture formed after the combustion reaction of the fly ash in the fly ash pre-combustion area enters the secondary air reaction area for secondary reaction. Aiming at the problems in the prior art, the invention provides a fly ash recycling system of a carbon-containing fluidized bed, which adopts the cascade combustion technology and the cooperation of two-section reaction areas, greatly improves the recycling efficiency of the fly ash of the fluidized bed with low activity, can keep the self-sustaining combustion of the system without extra fuel, greatly reduces the energy consumption and improves the production benefit.

Description

Fly ash recycling system of carbon-containing fluidized bed

Technical Field

The invention relates to the technical field of fluidized beds, in particular to a fly ash recycling system of a carbon-containing fluidized bed.

Background

In the present industrial system, there are generally two ways to utilize coal: one is to utilize the heat generated by coal combustion in other ways after heat exchange; the other is by coal gasification to produce coal gas, which is used as fuel or chemical synthesis gas.

In the process of producing coal gas, because gasification reaction is carried out, fluidized bed fly ash with high carbon content and low volatile content is generated. The carbon in the fly ash of the fluidized bed can not be fully utilized, and the fly ash can cause resource waste and environmental pollution when being treated as solid waste. The treatment and the reutilization of the fluidized bed fly ash with low activity become a technical problem which needs to be solved urgently in the industry.

Through retrieval, the technology of treating and recycling the fly ash of the fluidized bed is disclosed in the industry, for example, chinese patent application No. 2016210946955, which discloses a combustion system of fly ash of fluidized bed containing carbon, the system includes: the device comprises a combustion device, a combustion-supporting device, an air conveying device, a heat recovery device and a flue gas treatment device, wherein the combustion-supporting device is used for providing an adjustable continuous fire source for the combustion device; the input end of the combustion device is respectively connected with the combustion-supporting device and the air conveying device, the output end of the combustion device is connected with the input end of the heat recovery device, and the output end of the heat recovery device is connected with the flue gas treatment device; and the heat recovery device is used for collecting the heat generated when the carbon-containing fly ash is combusted in the combustion device. However, the system needs to provide a combustion-supporting device with an adjustable continuous fire source, and other fuels are adopted in the process of treating the fluidized bed fly ash simultaneously, so that the aim of treating the fluidized bed fly ash in an environment-friendly way cannot be fulfilled.

Disclosure of Invention

1. Technical problems to be solved by the invention

Aiming at the problems in the prior art, the invention provides a fly ash recycling system of a carbon-containing fluidized bed, which adopts the cascade combustion technology and the cooperation of two-section reaction areas, greatly improves the recycling efficiency of the fly ash of the fluidized bed with low activity, can keep the self-sustaining combustion of the system without extra fuel, greatly reduces the energy consumption and improves the production benefit.

2. Technical scheme

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

the fly ash recycling system of the carbon-containing fluidized bed comprises a fluidized bed boiler and a pulverized coal bin, wherein the fluidized bed boiler comprises a secondary air reaction area in the middle and a fly ash pre-combustion area at the bottom, fly ash in the pulverized coal bin is input into the fly ash pre-combustion area, the fly ash pre-combustion area is an oxygen-rich area, secondary air is introduced into the secondary air reaction area, and a high-temperature gas-solid mixture formed after the fly ash is subjected to combustion reaction in the fly ash pre-combustion area enters the secondary air reaction area to perform secondary reaction.

As a further improvement of the invention, the solid in the high-temperature gas-solid mixture after the secondary reaction is discharged from the bottom of the fluidized bed boiler in the form of slag, the flue gas in the high-temperature gas-solid mixture after the secondary reaction is discharged from the upper part of the fluidized bed boiler, the discharged flue gas is treated by the flue gas and then discharged to the atmosphere, and a small amount of fly ash in the flue gas is sent to the outside for use.

As a further improvement of the invention, the reaction temperature in the fly ash pre-combustion zone is 1200-1350 ℃; the reaction temperature in the secondary air reaction zone is 900-950 ℃.

As a further improvement of the invention, the fly ash in the fly ash bin is input into the fly ash pre-combustion zone through a fly ash conveying pipeline at the bottom, and the oxygen in the fly ash pre-combustion zone is supplied through an oxygen supply pipeline.

As a further improvement of the invention, an igniter is also arranged on the fly ash pre-combustion area, and the igniter is connected with a natural gas pipeline and an ignition fan.

As a further improvement of the invention, the secondary air in the secondary air reaction zone is supplied through a secondary air pipeline, and a secondary air fan is arranged on the secondary air pipeline.

As a further improvement of the invention, the flue gas discharged from the top of the fluidized bed boiler is treated by the pin removal unit, the bag-type dust remover and the desulfurizing tower in sequence and then discharged into the atmosphere, and a small amount of fly ash in the flue gas is sent to the outside for use by the bag-type dust remover.

As a further improvement of the invention, the upper part of the fluidized bed boiler is provided with a heat utilization area, boiler feed water enters the fluidized bed boiler and then reacts with hot flue gas generated in the fly ash pre-combustion area to generate high-temperature steam, and the pressure of the high-temperature steam is 1.6-9.9 Mpa.

As a further improvement of the invention, a boiler water supply pipeline is arranged at the top of the fluidized bed boiler, and an economizer water supply pipeline is arranged on the economizer.

As a further improvement of the invention, the upper part of the coal powder bin is provided with a powder feeding pipeline, and the bottom of the coal powder bin is provided with a powder feeder.

3. Advantageous effects

Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects:

(1) the flying ash recycling system of the carbon-containing fluidized bed adopts the cascade combustion technology, the lower part of the fluidized bed boiler is provided with an oxygen-enriched flying ash pre-combustion area, the reaction temperature is improved through the reaction of oxygen enrichment and flying ash, the activity of the flying ash is greatly increased, the flying ash of the fluidized bed is rapidly heated, and carbon in the flying ash of the fluidized bed is greatly reacted at the stage to form a high-temperature gas-solid mixture. The middle part of the fluidized bed boiler is provided with a secondary air reaction zone, the high-temperature gas-solid mixture carries out secondary reaction at the secondary air reaction zone, the smoke gas volume is increased, and the temperature of the gas-solid mixture is uniformly reduced.

(2) The fly ash recycling system of the carbon-containing fluidized bed has the advantages that the fly ash recycling efficiency of the fluidized bed with low activity is greatly improved by adopting the cascade combustion technology and the matching of two-section reaction areas, the self-sustaining combustion of the system can be kept without additional fuel, the energy consumption is greatly reduced, and the production benefit is improved. Meanwhile, the pneumatic conveying is adopted as a main conveying process, so that the ash leakage condition is avoided in the operation process of the system, and the field working environment is greatly improved.

(3) In the fly ash recycling system of the carbon-containing fluidized bed, the fly ash of the fluidized bed is the fly ash after one-time reaction, the fly ash has very low activity and is difficult to burn, and in order to ensure that the fly ash can be fully burnt, the reaction activity of the fly ash is improved by increasing the reaction temperature, so an oxygen-enriched fly ash pre-combustion area is required to be arranged at the lower part of a boiler, and the temperature is increased to 1200-1350 ℃. At this time, the reaction temperature is already above the melting point of the fly ash, and the fly ash is in a molten state. But when the temperature rises to 1200-1350 ℃, coking can occur in the furnace, so the chilling and reaction effects of the secondary air reaction zone are increased through the structure of a flow field, wherein the primary effect of the secondary air reaction zone is to further react the secondary air with unreacted fly ash again at 900-950 ℃ on the one hand to improve the conversion rate of carbon in the fly ash, and in addition, the excessive secondary air can produce the chilling effect on high-temperature flue gas to play a role in cooling, so that the high-temperature slag is changed into solid slag again, and the coking is prevented.

Drawings

FIG. 1 is a schematic structural view of a fly ash recycling system of a carbon-containing fluidized bed according to the present invention.

The reference numerals in the schematic drawings illustrate:

100. a pulverized coal bunker; 101. a powder feeding pipeline; 110. feeding a powder machine; 111. a fly ash conveying pipeline; 120. a powder feeding fan; 130. a dust remover; 131. a compressed air conduit;

200. a fluidized bed boiler; 201. an oxygen supply conduit; 202. a secondary air duct; 203. a boiler feed water line; 204. a secondary air fan; 210. a secondary air reaction zone; 220. a fly ash pre-combustion zone; 230. a pin removal unit; 240. a coal economizer; 241. an economizer feed water line; 250. an igniter; 251. an ignition fan; 260. a natural gas pipeline;

300. a bag-type dust collector; 400. a desulfurizing tower; 500. and (4) a chimney.

Detailed Description

For a further understanding of the invention, reference is made to the following detailed description taken in conjunction with the accompanying drawings.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

The present invention will be further described with reference to the following examples.

In view of the problems in the prior art, the present invention is intended to provide a fly ash recycling system for a carbon-containing fluidized bed, example 1

As shown in fig. 1, a fly ash recycling system of a carbon-containing fluidized bed of the present embodiment includes a fluidized bed boiler 200 and a pulverized coal bunker 100, wherein the fluidized bed boiler 200 includes a secondary air reaction zone 210 at the middle part and a fly ash pre-combustion zone 220 at the bottom part, the fly ash in the pulverized coal bunker 100 is input into the fly ash pre-combustion zone 220, and the fly ash pre-combustion zone 220 is an oxygen-rich region, the secondary air reaction zone 210 is filled with secondary air, specifically, the fly ash in the pulverized coal bunker 100 is input into the fly ash pre-combustion zone 220 through a fly ash conveying pipe 111 at the bottom part, and oxygen in the fly ash pre-combustion zone 220 is supplied through an oxygen supply pipe 201, so that the secondary air reaction zone 210 becomes an oxygen-rich environment. The secondary air in the secondary air reaction zone 210 is supplied through a secondary air pipeline 202, and a secondary air fan 204 is arranged on the secondary air pipeline 202. Wherein, the high-temperature gas-solid mixture formed after the fly ash is combusted and reacted in the fly ash pre-combustion zone 220 enters the secondary air reaction zone 210 to carry out secondary reaction. The fluidized bed boiler 200 of the present embodiment adopts a cascade combustion technology, an oxygen-rich fly ash pre-combustion area 220 is disposed at the lower part of the fluidized bed boiler 200, the reaction activity of the fluidized bed fly ash is improved by the reaction of oxygen-rich and fly ash, and the fluidized bed fly ash is rapidly heated up, and a large amount of carbon in the fluidized bed fly ash is reacted at this stage to form a high-temperature gas-solid mixture. The middle part of the fluidized bed boiler 200 is provided with a secondary air reaction zone 210, the high-temperature gas-solid mixture carries out secondary reaction at the secondary air reaction zone 210, the smoke gas amount is increased, and the temperature of the gas-solid mixture is reduced.

Wherein the solid in the high-temperature gas-solid mixture after the secondary reaction collides and adheres with the furnace wall in the secondary air reaction zone 210 to form large-particle slag, the large-particle slag is discharged from the bottom of the fluidized bed boiler 200 in the form of slag, the flue gas in the high-temperature gas-solid mixture after the secondary reaction is discharged from the upper part of the fluidized bed boiler 200, the discharged flue gas is discharged to the atmosphere after being treated by the flue gas, and a small amount of fly ash in the flue gas is sent to the outside for use. In the embodiment, the cascade combustion technology is adopted, the two-section reaction region is matched, the reutilization efficiency of the fluidized bed fly ash with low activity is greatly improved, the self-sustaining combustion of the system can be kept without extra fuel, the energy consumption is greatly reduced, and the production benefit is improved. Meanwhile, the pneumatic conveying is adopted as a main conveying process, so that the ash leakage condition cannot be generated in the operation process of the system, and the field working environment is greatly improved.

In this embodiment, the reaction temperature in the fly ash pre-combustion zone 220 is 1200-1350 ℃; the reaction temperature in the secondary air reaction zone 210 is 900 ℃ to 950 ℃. Specifically, the reaction temperature in the fly ash pre-combustion zone 220 in this embodiment is 1200 ℃; the reaction temperature in the secondary air reaction zone 210 is 900 ℃. Since the fluidized bed fly ash is the fly ash after one-time reaction, the activity of the fly ash is very low and difficult to burn, and in order to make the fly ash burn sufficiently, the reaction activity of the fly ash is improved by increasing the reaction temperature, so that an oxygen-rich fly ash pre-combustion zone 220 is required to be arranged at the lower part of the boiler, and the temperature is increased to 1200 ℃ to 1350 ℃. At this time, the reaction temperature is already above the melting point of the fly ash, and the fly ash is in a molten state. However, when the temperature rises to 1200 ℃ to 1350 ℃, coking can occur in the furnace, so that the chilling and reaction effects of the secondary air reaction zone 210 are increased through the structure of a flow field, wherein the primary effect of the secondary air reaction zone 210 is to further react the secondary air with unreacted fly ash again at 900 ℃ to 950 ℃ so as to improve the conversion rate of carbon in the fly ash, and in addition, the excessive secondary air can produce chilling effect on high-temperature flue gas to play a role in cooling, so that the high-temperature molten slag is changed into solid slag again, and coking is prevented.

In this embodiment, the fly ash pre-combustion area 220 is further provided with an igniter 250, the igniter 250 is connected with a natural gas pipeline 260 and an ignition fan 251, the natural gas pipeline 260 provides ignition fuel gas for ignition, the ignition is used when the boiler is started, and after the ignition is successful, fly ash and pure oxygen are sequentially introduced into the boiler, so that high temperature is generated above the fly ash pre-combustion area 220, carbon in the fly ash is reacted in a large amount, and then the combustion can be kept without fuel, thereby greatly saving energy consumption. In this embodiment, a powder feeding duct 101 is disposed at the upper portion of the coal powder bin 100, and a powder feeder 110 is disposed at the bottom of the coal powder bin 100. The pulverized coal bunker 100 is a circular bunker, and a dust collector 130 is installed at the upper part of the bunker, and a compressed air pipeline 131 is arranged on the dust collector 130 for purifying the exhaust gas of the conveying gas. The lower part of the pulverized coal bin 100 is a hyperbolic cone, so that smooth blanking can be ensured. Under normal operating conditions, the fluidized bed fly ash from coal gasification or other processes is pneumatically transported to the coal dust silo 100. The amount of powder fed is adjusted by the rotation speed of the powder feeder 110. The fluidized bed fly ash falling from the powder feeder 110 is sent to the fly ash pre-combustion area 220 at the lower part of the fluidized bed boiler 200 through the fly ash conveying pipe 111 by the roots powder feeding fan 120 for combustion treatment.

In this embodiment, the flue gas discharged from the top of the fluidized bed boiler 200 is sequentially treated by the denitration unit 230, the bag-type dust collector 300 and the desulfurizing tower 400, and then discharged into the chimney 500 and then discharged into the atmosphere, so as to ensure that the discharged tail gas meets the national standard; and a small amount of fly ash in the flue gas is sent to the outside for use through the bag-type dust collector 300 and can be sent to a rotary cement kiln for use as cement. The fluidized bed boiler 200 is provided with a boiler water feed pipe 203 at the top thereof, and an economizer water feed pipe 241 is provided on the economizer 240. The upper portion of the fluidized bed boiler 200 is provided with a heat utilization area, boiler feed water enters the fluidized bed boiler 200 and then reacts with hot flue gas generated in the fly ash pre-combustion area 220 to generate high-temperature steam, the pressure of the high-temperature steam is 1.6 Mpa-9.9 Mpa, and specifically, the pressure of the high-temperature steam in the embodiment is 1.6 Mpa. The heat value of the fluidized bed fly ash as the raw material needs to be 3500-6000 Kcal/kg, and the fluidized bed fly ash has high carbon content, so that if the fluidized bed fly ash is treated as solid waste by a conventional method, the environment is polluted, and meanwhile, great economic loss is caused.

Example 2

The structure of the fly ash recycling system of the carbon-containing fluidized bed is basically the same as that of the embodiment 1, and the difference is that the reaction temperature in the fly ash pre-combustion area 220 in the embodiment is 1350 ℃; the reaction temperature in the secondary air reaction zone 210 is 950 ℃.

In this embodiment, the boiler feed water enters the fluidized bed boiler 200 and then reacts with the hot flue gas generated in the secondary air reaction zone 210 to generate high-temperature steam, and the pressure of the high-temperature steam is 4.9 Mpa.

Example 3

The present embodiment is a fly ash recycling system of a carbon-containing fluidized bed, which has a structure substantially the same as that of embodiment 1, and is different in that the reaction temperature in the fly ash pre-combustion zone 220 in the present embodiment is 1300 ℃; the reaction temperature in the secondary air reaction zone 210 is 920 ℃.

In this embodiment, the boiler feed water enters the fluidized bed boiler 200 and then reacts with the hot flue gas generated in the secondary air reaction zone 210 to generate high-temperature steam, and the pressure of the high-temperature steam is 9.9 Mpa.

The present invention and its embodiments have been described above schematically, and the description is not intended to be limiting, and what is shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. Therefore, if the person skilled in the art receives the teaching, without departing from the spirit of the invention, the person skilled in the art shall not inventively design the similar structural modes and embodiments to the technical solution, but shall fall within the scope of the invention.

Claims

1. A fly ash recycling system of a carbon-containing fluidized bed is characterized in that: the fly ash pre-combustion device comprises a fluidized bed boiler (200) and a pulverized coal bunker (100), wherein the fluidized bed boiler (200) comprises a secondary air reaction zone (210) at the middle part and a fly ash pre-combustion zone (220) at the bottom part, fly ash in the pulverized coal bunker (100) is input into the fly ash pre-combustion zone (220), the fly ash pre-combustion zone (220) is an oxygen-enriched zone, secondary air is introduced into the secondary air reaction zone (210), and a high-temperature gas-solid mixture formed after the combustion reaction of the fly ash in the fly ash pre-combustion zone (220) enters the secondary air reaction zone (210) to carry out secondary reaction.

2. The fly ash recycling system of the carbon-containing fluidized bed according to claim 1, wherein: and solid in the high-temperature gas-solid mixture after the secondary reaction is discharged from the bottom of the fluidized bed boiler (200) in the form of slag, smoke in the high-temperature gas-solid mixture after the secondary reaction is discharged from the upper part of the fluidized bed boiler (200), the discharged smoke is treated and then discharged to the atmosphere, and a small amount of fly ash in the smoke is sent to the outside for use.

3. A fly ash recycling system for carbonaceous fluidized beds as claimed in claim 2, wherein: the reaction temperature in the fly ash pre-combustion area (220) is 1200-1350 ℃; the reaction temperature in the secondary air reaction zone (210) is 900-950 ℃.

4. A fly ash recycling system of carbon-containing fluidized bed according to claim 3, characterized in that: the fly ash in the pulverized coal bunker (100) is input into a fly ash pre-combustion area (220) through a fly ash conveying pipeline (111) at the bottom, and oxygen in the fly ash pre-combustion area (220) is supplied through an oxygen supply pipeline (201).

5. The fly ash recycling system of the carbon-containing fluidized bed according to claim 4, wherein: an igniter (250) is further arranged on the fly ash pre-combustion area (220), and the igniter (250) is connected with a natural gas pipeline (260) and an ignition fan (251).

6. The fly ash recycling system of the carbon-containing fluidized bed according to claim 5, wherein: the secondary air in the secondary air reaction zone (210) is supplied through a secondary air pipeline (202), and a secondary air fan (204) is arranged on the secondary air pipeline (202).

7. The fly ash recycling system of the carbon-containing fluidized bed according to claim 6, wherein: the flue gas discharged from the top of the fluidized bed boiler (200) is discharged into the atmosphere after being sequentially treated by the pin removal unit (230), the bag-type dust collector (300) and the desulfurizing tower (400), and a small amount of fly ash in the flue gas is sent to the outside for use by the bag-type dust collector (300).

8. A fly ash recycling system of carbonaceous fluidized bed according to any one of claims 1 to 7, characterized in that: the upper part of the fluidized bed boiler (200) is provided with a heat utilization area, boiler feed water enters the fluidized bed boiler (200) and then reacts with hot flue gas generated in the fly ash pre-combustion area (220) to generate high-temperature steam, and the pressure of the high-temperature steam is 1.6-9.9 MPa.

9. The fly ash recycling system of a carbon-containing fluidized bed according to claim 8, wherein: a boiler water feeding pipeline (203) is arranged at the top of the fluidized bed boiler (200), and an economizer water feeding pipeline (241) is arranged on the economizer (240).

10. The fly ash recycling system of a carbon-containing fluidized bed according to claim 1, wherein: the upper part of the pulverized coal bunker (100) is provided with a powder feeding pipeline (101), and the bottom of the pulverized coal bunker (100) is provided with a powder feeder (110).