CN110906320A - Boiler staged combustion system and staged combustion method based on concentration and dilution separation of oxygen in air - Google Patents

Boiler staged combustion system and staged combustion method based on concentration and dilution separation of oxygen in air Download PDF

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Publication number
CN110906320A
CN110906320A CN201911237828.8A CN201911237828A CN110906320A CN 110906320 A CN110906320 A CN 110906320A CN 201911237828 A CN201911237828 A CN 201911237828A CN 110906320 A CN110906320 A CN 110906320A
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China
Prior art keywords
oxygen
boiler
coal
air
gas
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CN201911237828.8A
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Chinese (zh)
Inventor
张勇胜
贾永会
闫慧博
张万德
马登卿
刘文献
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State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Hebei Electric Power Co Ltd
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State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Hebei Electric Power Co Ltd
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Priority to CN201911237828.8A priority Critical patent/CN110906320A/en
Publication of CN110906320A publication Critical patent/CN110906320A/en
Pending legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C7/00—Combustion apparatus characterised by arrangements for air supply
    • F23C7/02—Disposition of air supply not passing through burner
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D1/00—Burners for combustion of pulverulent fuel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23K—FEEDING FUEL TO COMBUSTION APPARATUS
    • F23K1/00—Preparation of lump or pulverulent fuel in readiness for delivery to combustion apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23K—FEEDING FUEL TO COMBUSTION APPARATUS
    • F23K3/00—Feeding or distributing of lump or pulverulent fuel to combustion apparatus
    • F23K3/02—Pneumatic feeding arrangements, i.e. by air blast
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L7/00—Supplying non-combustible liquids or gases, other than air, to the fire, e.g. oxygen, steam
    • F23L7/007—Supplying oxygen or oxygen-enriched air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C2201/00—Staged combustion
    • F23C2201/10—Furnace staging
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23K—FEEDING FUEL TO COMBUSTION APPARATUS
    • F23K2201/00—Pretreatment of solid fuel
    • F23K2201/10—Pulverizing
    • F23K2201/103—Pulverizing with hot gas supply
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00—Combustion technologies with mitigation potential
    • Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Air Supply (AREA)

Abstract

The invention relates to a boiler staged combustion system and a staged combustion method based on oxygen concentration and dilution separation in air, wherein the system comprises a boiler, a coal mill and an oxygen separation device, an inlet of the boiler is communicated with a material outlet of the coal mill, the oxygen separation device comprises a concentrated oxygen concentration outlet and a diluted oxygen concentration outlet, the concentrated oxygen concentration outlet is communicated with the boiler, and the diluted oxygen concentration outlet is communicated with an inlet of the coal mill; the invention not only can effectively prevent the spontaneous combustion/explosion problem of the coal mill in the operation process, but also can improve the temperature of the air-powder mixture at the outlet of the coal mill, and is beneficial toThe stable combustion in the boiler improves the safety and the economy of the equipment operation; in addition, the oxygen content in the coal powder combustion process is participated in a grading way, which is beneficial to controlling NOXIs performed.

Description

Boiler staged combustion system and staged combustion method based on concentration and dilution separation of oxygen in air
Technical Field
The invention belongs to the technical field of coal-fired power generation, and particularly relates to a boiler staged combustion system and a staged combustion method based on oxygen concentration separation in air.
Background
At present, a power station boiler generally extracts air from an atmospheric environment, and the air is heated by an air preheater and then enters a boiler furnace to support combustion or enters a coal pulverizer to grind coal powder and then enters the furnace to burn with the coal powder. The generation of NOx in the furnace is suppressed by using a low NOx burner and air classification along the height direction of the furnace.
The outlet temperature of the coal mill is an important parameter for reflecting the drying output of the coal mill and preventing the explosion or explosion of the coal powder. From the standpoint of mill output and pulverized coal combustion, it is desirable to maintain the mill outlet temperature at the upper operating limit as much as possible. The outlet temperature of the coal mill is high, which is beneficial to improving the combustion condition of the boiler hearth and reducing the incomplete combustion loss; and the outlet temperature control value of the coal mill is high, the inlet temperature of the coal mill can be correspondingly maintained at a higher value, so that the running condition of the coal mill is favorably improved, the output of the coal mill is improved, and the running economy of a pulverizing system is further improved; however, under the condition of air combustion, the overhigh temperature of the outlet of the coal mill is limited by the danger of spontaneous combustion and explosion of pulverized coal, especially when lignite and bituminous coal with high volatile components are combusted, the possibility of releasing combustible gas in the coal milling process can be increased by increasing the operating temperature of the coal mill, the deflagration of a pulverizing system can be easily caused, the allowable working temperature of the coal mill is low, and the operating safety and the economical efficiency of a unit are reduced.
With the rapid development and technical progress of national economy, the demand of industry for oxygen is increasing day by day, the application field is continuously expanded, and a large amount of oxygen is needed in the industries of metallurgy, chemical industry, environmental protection, machinery, medicine, glass and the like. This need has prompted the advancement of industrial gases in the technical quality and efficiency of the processing industry. Over the past 20 years, various oxygen production technologies have been developed, with the most efficient method of producing oxygen being to separate air. The basic principle of the technology of oxygen production by separating air is to separate oxygen and nitrogen in the air to form two air flows with different oxygen concentrations. The currently common air separation oxygen generation technology in industry mainly comprises a cryogenic process, a pressure swing adsorption process and a membrane separation process, the polymer membrane separation oxygen generation technology becomes one of six emerging technology industries with development prospects in the 21 st century, and in addition, the electromagnetic oxygen generation technology is gradually mature and gradually enters an industrial application stage.
Disclosure of Invention
The invention aims to provide a boiler staged combustion system and a staged combustion method based on oxygen content concentration separation in air, which not only can realize flexible arrangement of boiler air staged combustion, but also greatly improve the safe and economic operation performance of a coal mill.
The technical scheme adopted by the invention is as follows:
the utility model provides a boiler staged combustion system based on thick or light separation of oxygen content in air, it includes boiler, coal pulverizer and oxygen separator, the entry of boiler and the material export intercommunication of coal pulverizer, oxygen separator includes that thick oxygen volume exports and the export of light oxygen volume, and the export of thick oxygen volume communicates with the boiler, and the export of light oxygen volume communicates with the entry of coal pulverizer.
Furthermore, the oxygen concentration of the concentrated oxygen outlet is higher than that of the air, and the oxygen concentration of the dilute oxygen outlet is lower than that of the air.
Further, the oxygen concentration at the dilute oxygen outlet is lower than the critical value of the oxygen concentration in the gas when the deflagration of the pulverized coal and/or combustible gas in the coal mill is caused.
Further, the inlet of the oxygen separation device is communicated with the atmosphere through a primary air fan.
Further, still include gas heater, gas heater includes the gas heater flue gas side passageway of entry and the export intercommunication of boiler and is located the heating pipeline in gas heater flue gas side passageway, and the air that enters into in the boiler heats through heating pipeline.
Furthermore, the heating pipeline comprises a light oxygen amount primary air preheating pipeline and a concentrated oxygen amount primary air preheating pipeline, gas discharged from the concentrated oxygen amount outlet enters the boiler after being heated by the concentrated oxygen amount primary air preheating pipeline, and gas discharged from the light oxygen amount outlet enters the boiler after being heated by the light oxygen amount primary air preheating pipeline.
Furthermore, the position of the gas discharged from the concentrated oxygen outlet entering the boiler can be adjusted according to different burners of the boiler.
Furthermore, the heating pipeline also comprises a secondary air preheating pipeline, the inlet of the secondary air preheating pipeline is communicated with the secondary fan, and the outlet of the secondary air preheating pipeline is communicated with the inlet of the boiler.
Furthermore, bypass pipelines are arranged at two ends of the dilute oxygen primary air preheating pipeline, and control valves are arranged on the bypass pipelines.
Furthermore, the coal pulverizer also comprises a sealing fan, wherein an inlet of the sealing fan is communicated with a light oxygen content outlet of the oxygen separation device, and an outlet of the sealing fan is communicated with the coal pulverizer.
A boiler staged combustion method based on oxygen concentration and dilution separation in air comprises the following steps:
the primary air passing through the oxygen separation device is divided into primary air with concentrated oxygen and primary air with diluted oxygen; the fresh oxygen primary air enters a coal mill;
controlling the temperature of the gas entering the coal mill so that the temperature of the gas entering the coal mill is favorable for the economic operation of the coal mill;
controlling the oxygen concentration in the gas entering the coal mill to be lower than the oxygen concentration in the air and lower than the critical value of the oxygen concentration in the gas when the deflagration of the pulverized coal and/or combustible gas in the coal mill is caused;
the gas from the coal mill and the pulverized coal enter the boiler together for combustion;
and (3) feeding primary air with a concentrated oxygen amount into the boiler to supplement oxygen required by combustion of gas and pulverized coal from the coal mill.
The invention has the positive effects that: the invention not only can effectively prevent the spontaneous combustion/explosion problem of the coal mill in the operation process, but also can improve the temperature of the air-powder mixture at the outlet of the coal mill, is beneficial to the stable combustion of a boiler and improves the safety and the economical efficiency of the operation of equipment; in addition, the oxygen content in the coal powder combustion process is participated in a grading way, which is beneficial to controlling NOXIs performed.
The invention ensures that the oxygen concentration in the gas entering the coal mill is lower than the critical value of the oxygen concentration in the gas when the deflagration of the coal dust and/or combustible gas in the coal mill is caused, so that the problem of the spontaneous combustion or deflagration of the coal dust in the coal mill can not be caused even if the operating temperature of the coal mill is increased.
The control valve controls the fresh oxygen amount primary air volume which enters the coal mill and is not heated by the fresh oxygen amount primary air preheating pipeline, so that the temperature of the gas entering the coal mill is adjusted. When the air current was great in the bypass pipeline promptly, the gas that preheats the pipeline through light oxygen volume primary air was less, and the gas temperature that gets into in the coal pulverizer just can reduce, and when closing the bypass pipeline, gas just can enter into the coal pulverizer after preheating the pipeline through light oxygen volume primary air completely, and gas is whole to be heated this moment, and the gas temperature that gets into the coal pulverizer just can be higher.
The temperature of the gas entering the coal mill is adjusted, so that the temperature of the gas entering the coal mill is beneficial to safe and economic operation of the coal mill, and the adaptability and adjustability of the coal mill to the coal quality of the fuel coal are realized.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic view of the structure of the present invention.
In the drawings:
1: a boiler;
2: a gas preheater;
3: a secondary air preheating pipeline;
4: a primary air preheating pipeline with concentrated oxygen;
5: a fresh oxygen primary air preheating pipeline;
6: a secondary air fan;
7: a primary air fan;
8: an oxygen separation device;
9: a control valve;
10: sealing the fan;
11: provided is a coal mill.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the application, its application, or uses. 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 application.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
Example 1
As shown in the attached figure 1, the boiler staged combustion system of the present invention comprises a boiler 1, a coal mill 11 and an oxygen separation device 9, wherein the inlet of the boiler 1 is communicated with the outlet of the coal mill 11, and the outlet of the oxygen separation device 8 is respectively communicated with the inlet of the coal mill 11 and the boiler 1.
The oxygen separation device 8 comprises a concentrated oxygen outlet and a diluted oxygen outlet, the concentrated oxygen outlet is communicated with the boiler 1, the diluted oxygen outlet is communicated with the coal mill 11, the oxygen concentration of the gas entering the coal mill 11 is lower than the oxygen concentration of the air, and the temperature of the gas entering the coal mill 11 is higher than the conventional operation temperature of the coal mill 11. The oxygen concentration in part of gas entering the boiler 1 is higher than that in air, and the specific position of the gas entering the boiler 1 is determined according to the requirement of controlling NOx production in the pulverized coal combustion process of a hearth of the boiler 1.
In the prior art, in order to prevent spontaneous combustion or deflagration of a coal mill, a method for controlling the operation temperature of the coal mill is generally adopted, the operation economy of a unit is influenced due to the fact that cold air is doped, the ignition characteristic of pulverized coal can also be influenced due to the fact that the temperature of an air-powder mixture at the outlet of the coal mill is low, however, potential safety hazards can be brought due to the fact that the coal mill operates under the condition of high oxygen content and the operation temperature is increased. In this regard, the present invention reduces the oxygen content of the coal pulverizer 11 gas, and in particular, the oxygen concentration of the gas entering the coal pulverizer 11 is made lower than the threshold value of the oxygen concentration of the gas that would cause deflagration of the pulverized coal and/or combustible gases in the coal pulverizer 11, so that even if the operating temperature of the coal pulverizer 11 is increased, the problem of spontaneous combustion or deflagration of the pulverized coal in the coal pulverizer 11 is not caused.
The inlet of the oxygen separation device 8 is communicated with the atmosphere through a primary air fan 7, oxygen in the air is separated to form two gas of concentrated oxygen and dilute oxygen, and the oxygen concentration in the dilute oxygen is adjusted according to the coal quality of the coal used for boiler combustion and is lower than the safety concentration causing spontaneous combustion of coal powder in the coal mill 11.
Example 2
As shown in fig. 1, this embodiment includes all the technical features of embodiment 1, that is, the boiler staged combustion system of the present invention includes a boiler 1, a coal mill 11 and an oxygen separation device 9, wherein an inlet of the boiler 1 is communicated with an outlet of the coal mill 11, and an outlet of the oxygen separation device 8 is respectively communicated with the inlet of the coal mill 11 and the boiler 1.
The oxygen separation device 8 comprises a concentrated oxygen outlet and a diluted oxygen outlet, the concentrated oxygen outlet is communicated with the boiler 1, the diluted oxygen outlet is communicated with the coal mill 11, the oxygen concentration of the gas entering the coal mill 11 is lower than the oxygen concentration of the air, and the temperature of the gas entering the coal mill 11 is higher than the conventional operation temperature of the coal mill 11. The oxygen concentration in part of gas entering the boiler 1 is higher than that in air, and the specific position of the gas entering the boiler 1 is determined according to the requirement of controlling NOx production in the pulverized coal combustion process of a hearth of the boiler 1.
In the prior art, in order to prevent spontaneous combustion or deflagration of a coal mill, a method for controlling the operation temperature of the coal mill is generally adopted, the operation economy of a unit is influenced due to the fact that cold air is doped, the ignition characteristic of pulverized coal can also be influenced due to the fact that the temperature of an air-powder mixture at the outlet of the coal mill is low, however, potential safety hazards can be brought due to the fact that the coal mill operates under the condition of high oxygen content and the operation temperature is increased. In this regard, the present invention reduces the oxygen content of the coal pulverizer 11 gas, and in particular, the oxygen concentration of the gas entering the coal pulverizer 11 is made lower than the threshold value of the oxygen concentration of the gas that would cause deflagration of the pulverized coal and/or combustible gases in the coal pulverizer 11, so that even if the operating temperature of the coal pulverizer 11 is increased, the problem of spontaneous combustion or deflagration of the pulverized coal in the coal pulverizer 11 is not caused.
The inlet of the oxygen separation device 8 is communicated with the atmosphere through a primary air fan 7, oxygen in the air is separated to form two gas of concentrated oxygen and dilute oxygen, and the oxygen concentration in the dilute oxygen is adjusted according to the coal quality of the coal used for boiler combustion and is lower than the safety concentration causing spontaneous combustion of coal powder in the coal mill 11.
Still include gas preheater 2 in this embodiment, it includes gas preheater flue gas side passageway and is located the heating pipeline in the gas preheater flue gas side passageway, the entry of gas preheater flue gas side passageway with the export intercommunication of boiler 1.
The heating pipeline in the flue gas side channel of the gas preheater comprises a concentrated oxygen primary air preheating pipeline 4, a diluted oxygen primary air preheating pipeline 5 and a secondary air preheating pipeline 3, wherein an inlet of the concentrated oxygen primary air preheating pipeline 4 is communicated with a concentrated oxygen outlet of an oxygen separation device 8, an outlet of the concentrated oxygen primary air preheating pipeline 4 is communicated with a boiler 1, an inlet of the diluted oxygen primary air preheating pipeline 5 is communicated with a diluted oxygen outlet of the oxygen separation device 8, an outlet of the diluted oxygen primary air preheating pipeline 5 is communicated with an inlet of a coal mill 11, an outlet of the secondary air preheating pipeline 3 is communicated with the boiler 1, and an inlet of the secondary air preheating pipeline 3 is communicated with the atmosphere through a secondary fan 6.
Example 3
In this embodiment, a temperature adjustment device is added to embodiment 2, and all the technical features of embodiment 2 are included.
In the present embodiment, the system of the present invention comprises a boiler 1, a coal mill 11 and an oxygen separation device 9, wherein an inlet of the boiler 1 is communicated with an outlet of the coal mill 11, and an outlet of the oxygen separation device 8 is respectively communicated with the inlet of the coal mill 11 and the boiler 1.
The oxygen separation device 8 comprises a concentrated oxygen outlet and a diluted oxygen outlet, the concentrated oxygen outlet is communicated with the boiler 1, the diluted oxygen outlet is communicated with the coal mill 11, the oxygen concentration of the gas entering the coal mill 11 is lower than the oxygen concentration of the air, and the temperature of the gas entering the coal mill 11 is higher than the conventional operation temperature of the coal mill 11. The oxygen concentration in part of gas entering the boiler 1 is higher than that in air, and the specific position of the gas entering the boiler 1 is determined according to the requirement of controlling NOx production in the pulverized coal combustion process of a hearth of the boiler 1.
In the prior art, in order to prevent spontaneous combustion or deflagration of a coal mill, a method for controlling the operation temperature of the coal mill is generally adopted, the operation economy of a unit is influenced due to the fact that cold air is doped, the ignition characteristic of pulverized coal can also be influenced due to the fact that the temperature of an air-powder mixture at the outlet of the coal mill is low, however, potential safety hazards can be brought due to the fact that the coal mill operates under the condition of high oxygen content and the operation temperature is increased. In this regard, the present invention reduces the oxygen content of the coal pulverizer 11 gas, and in particular, the oxygen concentration of the gas entering the coal pulverizer 11 is made lower than the threshold value of the oxygen concentration of the gas that would cause deflagration of the pulverized coal and/or combustible gases in the coal pulverizer 11, so that even if the operating temperature of the coal pulverizer 11 is increased, the problem of spontaneous combustion or deflagration of the pulverized coal in the coal pulverizer 11 is not caused.
The inlet of the oxygen separation device 8 is communicated with the atmosphere through a primary air fan 7, oxygen in the air is separated to form two gas of concentrated oxygen and dilute oxygen, and the oxygen concentration in the dilute oxygen is adjusted according to the coal quality of the coal used for boiler combustion and is lower than the safety concentration causing spontaneous combustion of coal powder in the coal mill 11.
Still include gas preheater 2 in this embodiment, it includes gas preheater flue gas side passageway and is located the heating pipeline in the gas preheater flue gas side passageway, the entry of gas preheater flue gas side passageway with the export intercommunication of boiler 1.
The heating pipeline in the flue gas side channel of the gas preheater comprises a concentrated oxygen primary air preheating pipeline 4, a diluted oxygen primary air preheating pipeline 5 and a secondary air preheating pipeline 3, wherein an inlet of the concentrated oxygen primary air preheating pipeline 4 is communicated with a concentrated oxygen outlet of an oxygen separation device 8, an outlet of the concentrated oxygen primary air preheating pipeline 4 is communicated with a boiler 1, an inlet of the diluted oxygen primary air preheating pipeline 5 is communicated with a diluted oxygen outlet of the oxygen separation device 8, an outlet of the diluted oxygen primary air preheating pipeline 5 is communicated with an inlet of a coal mill 11, an outlet of the secondary air preheating pipeline 3 is communicated with the boiler 1, and an inlet of the secondary air preheating pipeline 3 is communicated with the atmosphere through a secondary fan 6.
The temperature adjusting device of the embodiment comprises a bypass pipeline which is communicated with an inlet pipeline of the dilute oxygen primary air preheating pipeline 5 and an outlet pipeline of the dilute oxygen primary air preheating pipeline 5, a control valve 9 is arranged on the bypass pipeline, and an outlet of the dilute oxygen primary air preheating pipeline 5 is communicated with an inlet of a coal mill 11 through an outlet pipeline of the dilute oxygen primary air preheating pipeline 5.
The control valve 9 controls the temperature of the gas entering the coal mill 11 by controlling the amount of the dilute oxygen primary air which is not heated by the dilute oxygen primary air preheating pipeline 5. That is, when the air current is great in the bypass pipeline, the gas that preheats the pipeline 5 through the light oxygen volume primary air is less, and the gas temperature that gets into in the coal pulverizer 11 just can reduce, and when closing the bypass pipeline, the gas just can get into the coal pulverizer 11 after preheating the pipeline 5 through the light oxygen volume primary air completely, and gas is whole to be heated this moment, and the gas temperature that gets into the coal pulverizer 11 just can be higher.
The temperature adjusting device is used for adjusting the temperature of the gas entering the coal mill 11, so that the temperature of the gas entering the coal mill 11 is beneficial to safe and economic operation of the coal mill, and the adaptability and adjustability of the coal mill 11 to the coal quality of the coal-fired coal are realized.
Preferably, the invention further comprises a sealing fan 10, wherein the inlet of the sealing fan 10 is communicated with the dilute oxygen outlet of the oxygen separation device 8, and the other end of the sealing fan is communicated with a coal mill 11.
Example 4
This example includes all the technical features of example 3 by changing the position of the outlet of the oxygen separation device communicating with the boiler based on example 3.
In the present embodiment, the system of the present invention comprises a boiler 1, a coal mill 11 and an oxygen separation device 9, wherein an inlet of the boiler 1 is communicated with an outlet of the coal mill 11, and an outlet of the oxygen separation device 8 is respectively communicated with the inlet of the coal mill 11 and the boiler 1.
The oxygen separation device 8 comprises a concentrated oxygen outlet and a diluted oxygen outlet, the concentrated oxygen outlet is communicated with the boiler 1, and the diluted oxygen outlet is respectively communicated with the coal mill 11 and the boiler 1. The oxygen concentration in the gas entering the coal mill 11 is made lower than the oxygen concentration in the air, and the temperature of the gas entering the coal mill 11 is made higher than the normal operating temperature of the coal mill 11. The oxygen concentration in part of gas entering the boiler 1 is higher than the oxygen concentration in the air, the oxygen concentration in part of gas is lower than the oxygen concentration in the air, and the specific position of the gas entering the boiler 1 is determined according to the requirement of controlling NOx production in the pulverized coal combustion process of a hearth of the boiler 1.
In the prior art, in order to prevent spontaneous combustion or deflagration of a coal mill, a method for controlling the operation temperature of the coal mill is generally adopted, the operation economy of a unit is influenced due to the fact that cold air is doped, the ignition characteristic of pulverized coal can also be influenced due to the fact that the temperature of an air-powder mixture at the outlet of the coal mill is low, however, potential safety hazards can be brought due to the fact that the coal mill operates under the condition of high oxygen content and the operation temperature is increased. In this regard, the present invention reduces the oxygen content of the coal pulverizer 11 gas, and in particular, the oxygen concentration of the gas entering the coal pulverizer 11 is made lower than the threshold value of the oxygen concentration of the gas that would cause deflagration of the pulverized coal and/or combustible gases in the coal pulverizer 11, so that even if the operating temperature of the coal pulverizer 11 is increased, the problem of spontaneous combustion or deflagration of the pulverized coal in the coal pulverizer 11 is not caused.
The inlet of the oxygen separation device 8 is communicated with the atmosphere through a primary air fan 7, oxygen in the air is separated to form two gas of concentrated oxygen and dilute oxygen, and the oxygen concentration in the dilute oxygen is adjusted according to the coal quality of the coal used for boiler combustion and is lower than the safety concentration causing spontaneous combustion of coal powder in the coal mill 11.
Still include gas preheater 2 in this embodiment, it includes gas preheater flue gas side passageway and is located the heating pipeline in the gas preheater flue gas side passageway, the entry of gas preheater flue gas side passageway with the export intercommunication of boiler 1.
The heating pipeline in the flue gas side channel of the gas preheater comprises a concentrated oxygen primary air preheating pipeline 4, a diluted oxygen primary air preheating pipeline 5 and a secondary air preheating pipeline 3, wherein an inlet of the concentrated oxygen primary air preheating pipeline 4 is communicated with a concentrated oxygen outlet of an oxygen separation device 8, an outlet of the concentrated oxygen primary air preheating pipeline 4 is communicated with a boiler 1, an inlet of the diluted oxygen primary air preheating pipeline 5 is communicated with a diluted oxygen outlet of the oxygen separation device 8, an outlet of the diluted oxygen primary air preheating pipeline 5 is respectively communicated with an inlet of a coal mill 11 and the boiler 1, an outlet of the secondary air preheating pipeline 3 is communicated with the boiler 1, and an inlet of the secondary air preheating pipeline 3 is communicated with the atmosphere through a secondary fan 6.
The temperature adjusting device of the embodiment comprises a bypass pipeline which is communicated with an inlet pipeline of the dilute oxygen primary air preheating pipeline 5 and an outlet pipeline of the dilute oxygen primary air preheating pipeline 5, a control valve 9 is arranged on the bypass pipeline, and an outlet of the dilute oxygen primary air preheating pipeline 5 is communicated with an inlet of a coal mill 11 through an outlet pipeline of the dilute oxygen primary air preheating pipeline 5.
The control valve 9 controls the temperature of the gas entering the coal mill 11 by controlling the amount of the dilute oxygen primary air which is not heated by the dilute oxygen primary air preheating pipeline 5. That is, when the air current is great in the bypass pipeline, the gas that preheats the pipeline 5 through the light oxygen volume primary air is less, and the gas temperature that gets into in the coal pulverizer 11 just can reduce, and when closing the bypass pipeline, the gas just can get into the coal pulverizer 11 after preheating the pipeline 5 through the light oxygen volume primary air completely, and gas is whole to be heated this moment, and the gas temperature that gets into the coal pulverizer 11 just can be higher.
The temperature adjusting device is used for adjusting the temperature of the gas entering the coal mill 11, so that the temperature of the gas entering the coal mill 11 is beneficial to safe and economic operation of the coal mill, and the adaptability and adjustability of the coal mill 11 to the coal quality of the coal-fired coal are realized.
Preferably, the invention further comprises a sealing fan 10, wherein the inlet of the sealing fan 10 is communicated with the dilute oxygen outlet of the oxygen separation device 8, and the other end of the sealing fan is communicated with a coal mill 11.
The invention also provides a boiler staged combustion method based on oxygen concentration separation in air, which comprises the following steps:
the primary air is divided into primary air with concentrated oxygen and primary air with diluted oxygen by an oxygen separation device 8; the fresh oxygen primary air enters a coal mill 11;
controlling the temperature of the gas entering the coal pulverizer 11 such that the temperature of the gas entering the coal pulverizer is conducive to economical operation of the coal pulverizer 11;
controlling the oxygen concentration in the gas entering the coal mill 11 to be lower than the oxygen concentration in the air and lower than the critical value of the oxygen concentration in the gas when the deflagration of the pulverized coal and/or combustible gas in the coal mill is caused;
the gas from the coal mill 11 and the pulverized coal enter the boiler 1 together for combustion;
and (3) enabling primary air with the concentrated oxygen amount to enter the boiler 1, and supplementing the oxygen amount required by combustion of gas and pulverized coal from the coal mill.
Preferably, the coal powder in the boiler is combusted in a grading mode in sequence, wherein the coal powder is carried by the primary air with the light oxygen content and enters the boiler to be combusted, the oxygen content required by the primary air with the concentrated oxygen content is supplemented to continue to be combusted, and the oxygen content supplemented by the secondary air is burnt out.
Further, in the invention, the air-powder mixture, the primary air with the concentrated oxygen content and the secondary air from the coal mill 11 are sequentially mixed in the hearth of the boiler 1, so that the low-nitrogen efficient staged combustion of the coal powder is realized.
Furthermore, in the invention, the mixing sequence of the air-powder mixture, the primary air with the concentrated oxygen content and the secondary air from the coal mill 11 in the hearth of the boiler 1 can be changed according to the type of the burner, so that the low-nitrogen efficient staged combustion of the coal powder is realized.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (10)

1. The utility model provides a boiler staged combustion system based on thick or light separation of oxygen volume in air, its characterized in that it includes boiler (1), coal pulverizer (11) and oxygen separator (8), the entry of boiler (1) and the material export intercommunication of coal pulverizer (11), oxygen separator (8) are exported including thick oxygen volume and light oxygen volume, and the thick oxygen volume export communicates with boiler (1), and the light oxygen volume export communicates with the entry of coal pulverizer (11).
2. The staged boiler combustion system as defined in claim 1, wherein the oxygen concentration in the rich oxygen outlet is higher than the oxygen concentration in the air, and the oxygen concentration in the lean oxygen outlet is lower than the oxygen concentration in the air.
3. The staged boiler combustion system as claimed in claim 1 or 2, wherein the oxygen concentration at the light oxygen outlet is lower than the critical value of the oxygen concentration in the gas causing deflagration of the pulverized coal and/or combustible gas in the coal pulverizer.
4. The boiler staged combustion system based on oxygen-rich separation in air as claimed in claim 1 or 2, wherein the inlet of the oxygen separation device (8) is connected to the atmosphere via a primary air blower (7).
5. The boiler staged combustion system based on oxygen concentration and separation in air as claimed in claim 1, further comprising a gas preheater (2), wherein the gas preheater (2) comprises a gas preheater flue gas side channel with an inlet communicated with an outlet of the boiler (1) and a heating pipeline positioned in the gas preheater flue gas side channel, and the air entering into the boiler (1) is heated by the heating pipeline.
6. The boiler staged combustion system based on the separation of oxygen content from air according to claim 5, wherein the heating pipeline comprises a light oxygen content primary air preheating pipeline (5) and a heavy oxygen content primary air preheating pipeline (4), the gas discharged from the heavy oxygen content outlet enters the boiler (1) after being heated by the heavy oxygen content primary air preheating pipeline (4), and the gas discharged from the light oxygen content outlet enters the boiler (1) after being heated by the light oxygen content primary air preheating pipeline (5).
7. The boiler staged combustion system based on oxygen concentration and dilution separation in air as claimed in claim 6, wherein said heating circuit further comprises a secondary air preheating circuit (3) having an inlet in communication with the secondary air blower (6) and an outlet in communication with the inlet of the boiler (1).
8. The boiler staged combustion system based on oxygen concentration and dilution separation in air as claimed in claim 6, wherein bypass pipes are arranged at two ends of the dilute oxygen primary air preheating pipe (5), and a control valve (9) is arranged on the bypass pipes.
9. The boiler staged combustion system based on oxygen concentration and dilution separation in air as claimed in claim 1, further comprising a sealing fan (10), wherein an inlet of the sealing fan (10) is communicated with a diluted oxygen concentration outlet of the oxygen separation device (8), and an outlet is communicated with the coal mill (11).
10. A boiler staged combustion method based on oxygen concentration and dilution separation in air is characterized by comprising the following steps:
the primary air passing through the oxygen separation device (8) is divided into primary air with concentrated oxygen and primary air with diluted oxygen; the fresh oxygen primary air enters a coal mill (11);
controlling the temperature of the gas entering the coal mill (11) such that the temperature of the gas entering the coal mill facilitates economical operation of the coal mill (11);
controlling the oxygen concentration in the gas entering the coal mill (11) to be lower than the oxygen concentration in the air and lower than a critical value of the oxygen concentration in the gas when the deflagration of the pulverized coal and/or combustible gas in the coal mill is caused;
the gas from the coal mill (11) and the pulverized coal enter the boiler (1) together for combustion;
and (3) enabling primary air with a concentrated oxygen amount to enter the boiler (1) to supplement oxygen required by combustion of gas and pulverized coal from the coal mill.
CN201911237828.8A 2019-12-06 2019-12-06 Boiler staged combustion system and staged combustion method based on concentration and dilution separation of oxygen in air Pending CN110906320A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012088016A (en) * 2010-10-22 2012-05-10 Babcock Hitachi Kk Oxygen combustion type boiler and method of operating the same
CN104864392A (en) * 2015-04-15 2015-08-26 同济大学 Total-oxygen coal powder MILD combustion method and device used by same
CN105157020A (en) * 2015-09-25 2015-12-16 中国神华能源股份有限公司 Oxygen-enriched combustion system and method
CN205825011U (en) * 2016-06-06 2016-12-21 日照广源热动有限公司 A kind of fluidized-bed combustion boiler environment protecting power economizer
CN110240944A (en) * 2019-05-21 2019-09-17 浙江大学 The method and device of fine coal constant-pressure and high-temperature cracking oxygen-rich gasification coproduction coal gas and semicoke

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012088016A (en) * 2010-10-22 2012-05-10 Babcock Hitachi Kk Oxygen combustion type boiler and method of operating the same
CN104864392A (en) * 2015-04-15 2015-08-26 同济大学 Total-oxygen coal powder MILD combustion method and device used by same
CN105157020A (en) * 2015-09-25 2015-12-16 中国神华能源股份有限公司 Oxygen-enriched combustion system and method
CN205825011U (en) * 2016-06-06 2016-12-21 日照广源热动有限公司 A kind of fluidized-bed combustion boiler environment protecting power economizer
CN110240944A (en) * 2019-05-21 2019-09-17 浙江大学 The method and device of fine coal constant-pressure and high-temperature cracking oxygen-rich gasification coproduction coal gas and semicoke

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Application publication date: 20200324