CN218864154U

CN218864154U - Low-nitrogen combustion system of circulating fluidized bed boiler

Info

Publication number: CN218864154U
Application number: CN202223093969.7U
Authority: CN
Inventors: 邬佳康; 王凤彬; 李美喜
Original assignee: Xinneng Energy Co Ltd
Current assignee: Xinneng Energy Co Ltd
Priority date: 2022-11-21
Filing date: 2022-11-21
Publication date: 2023-04-14
Anticipated expiration: 2032-11-21

Abstract

The utility model discloses a circulating fluidized bed boiler low nitrogen combustion system, it is including fluidized bed boiler, cyclone, the flue of pipe connection in proper order, still including the female pipe of air inlet, the entry and the air supply intercommunication of the female pipe of air inlet, the exit linkage of the female pipe of air inlet has an at least air inlet branch pipe, and air inlet branch pipe's export is fixed with cyclone's top, and communicates with cyclone's inside. The advantages are that: the fuel adaptability is wide, the structure of the existing circulating fluidized bed boiler is not obviously changed, a combustion system and a steam-water system of the boiler are not influenced, and the investment cost is low; the air inlet branch pipe is added at the outlet of the cyclone separator, and the air inlet branch pipe supplies post-combustion air to the interior of the cyclone separator, so that the combustion efficiency of the boiler is ensured, meanwhile, the unburned fly ash and carbon residue are fully combusted, and the problems of slag bonding and blockage of subsequent equipment are solved; after the technology is adopted, extra reducing agents such as ammonia water and urea are not needed to be added, the technology of really no ammonia is realized, and the pollutant control operation cost is reduced.

Description

Low-nitrogen combustion system of circulating fluidized bed boiler

The technical field is as follows:

the utility model relates to a fluidized bed technical field, concretely relates to circulating fluidized bed boiler low-nitrogen combustion system.

The background art comprises the following steps:

circulating fluidized bed boiler systems are generally composed of a fluidized bed combustion chamber (furnace), a circulating ash cyclone, a fly ash returning device, a tail heating surface, auxiliary equipment and the like. The fuel is burnt in the fluidized bed boiler, and because the fuel contains nitrogen elements, the fuel reacts with oxygen in the burning process to generate nitrogen oxides.

The technological measures for treating the excessive nitrogen oxides in the market mainly comprise low-oxygen combustion and addition of an SNCR (selective non-catalytic reduction) denitration system, wherein the low-oxygen combustion adopts lower oxygen content (excess air coefficient), at the moment, dense-phase zone combustion is carried out under the condition of excess fuel, and due to insufficient air, in a reducing atmosphere, the intermediate product of nitrogen combustion cannot be further oxidized into oxynitride and is reduced into neutral N2, so that the generation of NOX can be effectively controlled; the SNCR denitration system is added, under the condition that no catalyst is needed, a reducing agent (generally urea solution, ammonia water and other ammonia sources) is sprayed only in a region with the temperature of 850-1100 ℃ in a hearth, and the ammonia source reacts with oxynitride in smoke gas at high temperature to generate nitrogen and water and reduce the content of oxynitride in the smoke gas, so that the process is also referred to as high-temperature denitration for short.

The technical problems existing in the current method for reducing the concentration of oxynitride are as follows: the consumption of denitration ammonia water in an SNCR denitration system is increased to be higher, in order to control the discharge of oxynitride to be within a standard value of 100mg/m < 3 >, the consumption of the denitration ammonia water (with the concentration of 20%) is 220kg/h, and the cost is higher; carbon monoxide and smoke and dust emission concentration can increase in the low oxygen combustion process, and the efficiency of burning can reduce, leads to the combustion efficiency of fuel to be difficult to guarantee, appears the problem of equipment slagging scorification, jam.

The utility model has the following contents:

an object of the utility model is to provide a circulating fluidized bed boiler low nitrogen combustion system.

The utility model discloses by following technical scheme implement: circulating fluidized bed boiler low-nitrogen combustion system, it is including pipeline connection's fluidized bed boiler, cyclone, flue in proper order, still including the female pipe of air inlet, the entry and the air supply intercommunication of the female pipe of air inlet, the exit linkage of the female pipe of air inlet has an at least air inlet branch pipe, the export of air inlet branch pipe with cyclone's top is fixed, and with cyclone's inside intercommunication.

Furthermore, a first electric damper and a flowmeter are installed on the air inlet branch pipe.

Further, the air source comprises a fan.

Furthermore, a secondary air preheater is installed in the flue.

Furthermore, an air outlet of the secondary air preheater is communicated with an inlet pipeline of the air inlet main pipe.

Furthermore, the air outlet of the secondary air preheater is communicated with a secondary air inlet pipeline of the fluidized bed boiler, and a second electric air adjusting door is installed on the secondary air inlet pipeline.

Furthermore, a primary air inlet pipeline is arranged at the bottom end of the fluidized bed boiler, and a third electric air adjusting door is installed on the primary air inlet pipeline.

The utility model has the advantages that: the fuel adaptability is wide, the influence of fuel granularity and coal types is avoided, the modification period is short, the normal operation of the boiler is not influenced, the structure of the existing circulating fluidized bed boiler is not obviously changed, the combustion system and the steam-water system of the boiler are not influenced, the investment cost is low, and the method is suitable for both the modification of old boilers and newly-built boilers;

the air inlet branch pipe is added at the outlet of the cyclone separator, the air inlet branch pipe supplies post-combustion air to the interior of the cyclone separator, and because the post-combustion chamber has only 10-20% of combustion share, the concentration of oxynitride generated by the combustion of fuel nitrogen in the coke is 10-20% of the concentration of total oxynitride released in the combustion process, and the existence of carbon monoxide also reduces the oxynitride in the flue gas into nitrogen gas, thereby obviously reducing the emission of the oxynitride, ensuring the combustion efficiency of a boiler, fully burning out unburned fly ash carbon residue, and solving the problems of slag formation and blockage of subsequent equipment;

when the technology is not adopted in the boiler, in order to control the NOx emission to be within 100mg/m < 3 >, the consumption of SNCR denitration ammonia water (with the concentration of 20%) is 220kg/h, after the technology is adopted, the original NOx emission of the boiler can directly reach within 100mg/m < 3 >, finally, the NOx emission easily meets the ultra-low emission requirement, extra reducing agents such as ammonia water and urea do not need to be added, the real ammonia-free technology is realized, and the pollutant control operation cost is greatly reduced.

Description of the 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 these drawings without creative efforts.

Fig. 1 is a schematic structural view of embodiment 1 of the present invention;

fig. 2 is a schematic structural view of embodiment 2 of the present invention;

in the figure: the device comprises a fluidized bed boiler 1, a cyclone separator 2, a flue 3, a secondary air preheater 4, a primary air inlet pipeline 5, a third electric damper 6, a secondary air inlet pipeline 7, a second electric damper 8, a main air inlet pipe 9, an air inlet branch pipe 10, a first electric damper 11, a flowmeter 12 and a fan 13.

The specific implementation mode is as follows:

the technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

Example 1:

as shown in fig. 1, the circulating fluidized bed boiler low-nitrogen combustion system includes a fluidized bed boiler 1, a cyclone separator 2, and a flue 3 connected in sequence by pipes, wherein a secondary air preheater 4 is installed in the flue 3, a primary air inlet pipeline 5 is arranged at the bottom end of the fluidized bed boiler 1, a third electric damper 6 is installed on the primary air inlet pipeline 5, an air outlet of the secondary air preheater 4 is further communicated with a secondary air inlet pipeline 7 of the fluidized bed boiler 1, a second electric damper 8 is installed on the secondary air inlet pipeline 7, and the air intake of the primary air and the secondary air is controlled by the third electric damper 6 and the second electric damper 8, so that based on the combustion characteristics of the circulating fluidized bed and the nitrogen oxide generation control principle, a dense-phase region reduction strength and an increased reduction reaction region are utilized to expand a dense-phase low-oxygen reduction region at the lower part of a hearth in a conventional combustion manner to the whole hearth, so that 80-90% of combustion share of fuel is completed in a weak reduction atmosphere, and volatile fuel nitrogen in the hearth is completely converted into nitrogen; the fuel adaptability is wide and is not influenced by the fuel granularity and the coal type.

The boiler also comprises a main air inlet pipe 9, an inlet of the main air inlet pipe 9 is communicated with an air source, an outlet of the main air inlet pipe 9 is connected with at least one air inlet branch pipe 10, an outlet of the air inlet branch pipe 10 is fixed with the top end of the cyclone separator 2 and is communicated with the inside of the cyclone separator 2, the air inlet branch pipe 10 is added to the outlet of the cyclone separator 2, post-combustion air is supplemented into the cyclone separator 2 by the air inlet branch pipe 10, as only 10-20% of combustion share exists in a post-combustion chamber, the concentration of oxynitride generated by combustion of fuel nitrogen in the part of coke is 10-20% of the concentration of total oxynitride released in the combustion process, and the existence of carbon monoxide also reduces the nitrogen oxide in the flue gas into nitrogen gas, so that the emission of the nitrogen oxide can be remarkably reduced, the combustion efficiency of the boiler is ensured, meanwhile, the unburned fly ash carbon residue is fully combusted, and the problems of slag formation and blockage of subsequent equipment are solved.

When the technology is not adopted in a boiler, in order to control the NOx emission to be within 100mg/m < 3 >, the consumption of the SNCR denitration ammonia water (with the concentration of 20%) is 220kg/h; after the technology is adopted, the original emission of the NOx in the boiler can directly reach within 100mg/m & lt 3 & gt, finally, the emission of the NOx easily meets the requirement of ultralow emission, extra reducing agents such as ammonia water and urea are not needed to be added, the real ammonia-free technology is realized, and the pollutant control operation cost is greatly reduced.

The air inlet branch pipe 10 is provided with a first electric damper 11 and a flowmeter 12, the air inlet amount entering the cyclone separator 2 can be controlled through the first electric damper 11, and carbon monoxide and unburned fly ash carbon residue in the cyclone separator 2 are ensured to be fully combusted.

The air supply comprises a fan 13, and the fan 13 is used for adding post-combustion air into the cyclone separator 2.

Example 2:

as shown in fig. 2, the circulating fluidized bed boiler low-nitrogen combustion system is different from embodiment 1 in that an air outlet of the secondary air preheater 4 is communicated with an inlet pipeline of the air inlet main pipe 9, hot air at the air outlet of the secondary air preheater is used as post-combustion air of the cyclone separator 2, and the hot air has a certain temperature, so that the ambient temperature in the cyclone separator 2 is ensured, the combustion reaction is promoted, and ash and slag collected by a material returning device at the bottom of the cyclone separator 2 are returned to the fluidized bed boiler 1 for reuse.

The above description is only for the preferred embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. Circulating fluidized bed boiler low-nitrogen combustion system, it is including the fluidized bed boiler, cyclone, the flue of pipe connection in proper order, its characterized in that, still including the female pipe of air inlet, the entry and the air supply intercommunication of the female pipe of air inlet, the exit linkage of the female pipe of air inlet has an at least air inlet branch pipe, the export of air inlet branch pipe with cyclone's top is fixed, and with cyclone's inside intercommunication.

2. The circulating fluidized bed boiler low-nitrogen combustion system according to claim 1, wherein a first electric damper and a flow meter are installed on the air inlet branch pipe.

3. The circulating fluidized bed boiler low nitrogen combustion system of claim 1 or 2, wherein the air source comprises a fan.

4. The circulating fluidized bed boiler low nitrogen combustion system of claim 1 or 2, wherein a secondary air preheater is installed in the flue.

5. The circulating fluidized bed boiler low-nitrogen combustion system as claimed in claim 4, wherein the air outlet of the secondary air preheater is communicated with the inlet pipeline of the air inlet main pipe.

6. The circulating fluidized bed boiler low-nitrogen combustion system as claimed in claim 5, wherein the air outlet of the secondary air preheater is further communicated with a secondary air inlet pipeline of the fluidized bed boiler, and a second electric damper is installed on the secondary air inlet pipeline.

7. The circulating fluidized bed boiler low-nitrogen combustion system according to claim 6, wherein a primary air inlet pipeline is arranged at the bottom end of the fluidized bed boiler, and a third electric damper is installed on the primary air inlet pipeline.