CN113154429B - Denitrification system with combustion and heating in the flue - Google Patents
Denitrification system with combustion and heating in the flue Download PDFInfo
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- CN113154429B CN113154429B CN202110482791.6A CN202110482791A CN113154429B CN 113154429 B CN113154429 B CN 113154429B CN 202110482791 A CN202110482791 A CN 202110482791A CN 113154429 B CN113154429 B CN 113154429B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/08—Arrangements of devices for treating smoke or fumes of heaters
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/02—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone
- F23D14/04—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone induction type, e.g. Bunsen burner
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/26—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid with provision for a retention flame
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/46—Details, e.g. noise reduction means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/46—Details, e.g. noise reduction means
- F23D14/62—Mixing devices; Mixing tubes
- F23D14/64—Mixing devices; Mixing tubes with injectors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/46—Details, e.g. noise reduction means
- F23D14/72—Safety devices, e.g. operative in case of failure of gas supply
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/003—Arrangements of devices for treating smoke or fumes for supplying chemicals to fumes, e.g. using injection devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2215/00—Preventing emissions
- F23J2215/10—Nitrogen; Compounds thereof
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2215/00—Preventing emissions
- F23J2215/10—Nitrogen; Compounds thereof
- F23J2215/101—Nitrous oxide (N2O)
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- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Chimneys And Flues (AREA)
- Treating Waste Gases (AREA)
Abstract
The invention relates to a denitration system for combustion heating in a flue, which comprises a flue before denitration, a flue after denitration and a control system, wherein heat exchangers are communicated with the flue before denitration and the flue after denitration, a low-temperature flue gas channel before denitration and a high-temperature flue gas channel after denitration are arranged in the heat exchangers, an SCR denitration reactor and a flue gas sampling structure are arranged in the flue after denitration, a direct-fired heating device is arranged on the flue before denitration and comprises a plurality of flame burners, the flame flow center line of each flame burner is tangent with an imaginary tangent circle, the flame spraying direction of each flame burner is opposite to the flue gas flow direction, and the flame spraying length of each flame burner is adjustable. The direct-fired heating device is arranged in the invention to directly heat the flue gas, so that the temperature of the flue gas reaches the temperature range of the ideal denitration reaction of the catalyst, the expected denitration reaction is realized, the ultra-low emission requirement is met, and the running economic benefit of the equipment is improved.
Description
Technical Field
The invention relates to the technical field of flue gas denitration, in particular to a denitration system for heating up combustion in a flue.
Background
The treatment of atmospheric pollution is an important component of environmental treatment, and with the development of industry and the improvement of living standard, people are increasingly focusing on environmental problems and atmospheric environmental problems.
Nitrogen oxides (NOx) are a major class of atmospheric pollutants, one of the major contributors to the formation of acid rain, photochemical smog, and PM2.5 pollution. At present, the emission of industrial source NOx in China accounts for more than 70% of the total emission amount of NOx, and the emission control technology of NOx in industrial flue gas mainly comprises a combustion control technology and a post-combustion control technology. Combustion control techniques include low nitrogen combustion techniques, reburning techniques, and flue gas recirculation techniques. Among the post-combustion control technologies, selective Catalytic Reduction (SCR), selective non-catalytic reduction (SNCR), and SCR-SNCR hybrid technologies are major technologies. From an economic and technical standpoint, selective catalytic reduction is the most effective post-NOx control technique.
A large amount of atmospheric pollutants such as SO 2, NOx and the like can be generated in the coal burning process, SO that serious atmospheric pollution and economic loss are caused. The pollutants in the exhaust smoke of industries such as thermal power, steel and the like are various, and strict requirements are put on the emission of NOx. The aim of denitration is mainly to remove Nitric Oxide (NO) and nitrogen dioxide (NO 2).
The proportion of Nitric Oxide (NO) in the flue gas is very high and is often more than 90%. Nitric oxide is a polluting gas, and after being directly discharged to the atmosphere, the nitric oxide easily pollutes the atmosphere, soil and water sources, so that when the factory discharges smoke, especially the discharged smoke contains nitric oxide, and the smoke needs to be subjected to denitration treatment. The existing flue gas denitration technology mainly comprises a dry method and a wet method, and has the main advantages of low basic investment, simple equipment and process, higher NOx removal efficiency, no wastewater and waste treatment and difficult secondary pollution compared with the wet flue gas denitration technology.
The completion of the SCR reaction requires the use of a catalyst. At present, a medium-temperature catalyst with the operation temperature of 320-450 ℃ is widely applied, so that the reaction temperature of catalytic reduction denitration is controlled to be 320-450 ℃. When the reaction temperature is lower than 300 ℃, side reactions occur on the surface of the catalyst, ammonia reacts with sulfur trioxide and water to generate (NH 4)2SO4 or NH 4SO4 reduces the reaction with NOx, the generated products adhere to the surface of the catalyst to block catalyst channels and micropores and reduce the activity of the catalyst, and if the reaction temperature is higher than the applicable temperature of the catalyst, the catalyst channels and the micropores deform to deactivate the catalyst.
In the denitration process, the flue gas needs to be heated to the preset temperature to be efficiently and stably subjected to the denitration process, in the prior art, a heating source is arranged below a denitration flue gas, and the flue gas is uniformly mixed with the flue gas after rising through high-temperature gas so as to realize the heating purpose, and because the pipeline of the denitration system is generally longer in size, therefore, heat loss is inevitably caused in the rising process of the high-temperature gas below the mixing layer, and meanwhile, the mixing length of the high-temperature gas and the flue gas in the axial direction is long enough in the rising process of the high-temperature gas, but the radial mixing surface cannot be ensured to be large enough in the radial direction, so that the complete and uniform mixing of the high-temperature gas and the flue gas cannot be ensured.
In the industries of iron and steel, metallurgy and coal chemical industry, the exhaust gas temperature of equipment such as a sintering machine is low, and the exhaust gas is required to be heated in order to meet the requirements of denitration treatment or other processes in the subsequent SCR equipment. There are various modes of flue gas heating, such as directly adding a heat exchanger, setting electric heating, etc., by introducing a high-temperature heat source, and these modes result in higher running cost due to the need of adding an additional heat source.
In addition, since a large amount of fuel gas such as blast furnace gas, converter gas, coke oven gas and the like is generally produced in industrial equipment in the iron and steel, metallurgy and coal chemical industries. Therefore, in the prior art, many enterprises can utilize the fuel gas, and by arranging an independent heating furnace outside a flue, one or more blast furnace gas or coke oven gas burners are arranged according to the power of the heating furnace, and the fuel gas in the burners is combusted to generate high-temperature flue gas which is sent into the flue through a branch and mixed with the original flue gas in the flue, so that the original flue gas is heated. According to the method, the heating furnace is required to be arranged outside the flue, so that on one hand, the investment cost is high, and on the other hand, after the high-temperature flue gas generated by burning the fuel gas is mixed with the original flue gas in the flue, the total amount of the flue gas in the flue is increased sharply, so that a flue gas system is influenced greatly, and the problem of insufficient output of the existing induced draft fan is caused.
At present, the environment-friendly situation of the steel industry is becoming severe, and the steel enterprises need to develop ultra-low emission reformation step by step. The most widely used technology of the steel plant with low-emission reconstruction is to construct a set of SCR denitration device, and then utilize the combustion of blast furnace gas of the steel plant to heat the flue gas, thereby meeting the flue gas temperature requirement of a denitration inlet.
Because the heat value of the blast furnace gas is low, the blast furnace gas is not easy to catch fire, an insulating ignition air duct which is independently laid with casting materials is generally adopted, natural gas or a light oil gun and the like are firstly adopted for ignition, the blast furnace gas is introduced for combustion after the temperature in the ignition air duct is raised, and finally, the high-temperature flue gas after combustion is mixed into a denitration flue for heating the denitration flue gas. The high temperature flue gas generated by the combustion of the blast furnace gas in the heat insulation flue has a low heat value, the temperature of the high temperature flue gas can reach 1200-1400 ℃, in the ignition process, if natural gas or an oil gun is adopted for ignition, the combustion temperature can be higher and can reach 1500-1700 ℃, the use temperature of common refractory castable is about 1300 ℃, so that the ignition flue castable is easy to fall off, then the steel plate of the air duct is subjected to high temperature deformation, the service life is shortened, if the refractory castable with better use performance such as alumina hollow sphere castable is high in price, the manufacturing cost is greatly increased, and in addition, the large excess air coefficient is adopted in the prior art to reduce the temperature of the combustion flue gas, but the mode greatly increases the extra air for heating, so that more fuel gas is required to be added, and the economical efficiency is poor.
In the prior art, a denitration system (CN 209576247U) for directly burning and heating a low-load flue of a boiler, a direct-fired temperature rise heating device (CN 209501296U) for the denitration system, and a flue gas heating system (CN 110160066A) are arranged in a butt-impact way, wherein the flue gas heating areas are smaller and cannot heat the flue with a large section, the temperature of the area close to the flame area of the direct-fired furnace is higher, the temperature of the area close to the peripheral wall surface of the flue is lower, the air flow mixing effect is poorer at the section axis, the quick heat transfer and the uniform heat distribution are not facilitated, the flame combustion area is relatively fixed, the ideal mixing of the air flow on the section of the flue and the quick heat transfer cannot be realized, and the uniform temperature distribution cannot be realized.
Therefore, the inventor provides a denitration system for combustion heating in a flue by virtue of experience and practice of related industries for many years so as to overcome the defects of the prior art.
Disclosure of Invention
The invention aims to provide a denitration system for combustion heating in a flue, which overcomes the problems in the prior art, and the denitration system is internally provided with a direct-fired heating device for directly heating flue gas, so that the temperature of the flue gas is promoted to reach the temperature range of ideal denitration reaction of a catalyst, the expected denitration reaction is realized, the ultralow emission requirement is met, and the running economic benefit of equipment is improved.
The invention aims to realize that a denitration system for combustion heating in a flue comprises a pre-denitration flue, a denitration treatment flue and a control system, wherein a flue gas inlet is formed in the first end of the pre-denitration flue, a flue gas outlet is formed in the first end of the denitration treatment flue, and the second end of the pre-denitration flue and the second end of the denitration treatment flue are in sealed communication; the flue before denitration and the flue after denitration are communicated and provided with heat exchangers, a low-temperature flue gas channel before denitration and a high-temperature flue gas channel after denitration are arranged in the heat exchangers, an SCR denitration reactor is arranged between the second end of the flue before denitration and the heat exchangers, a flue gas sampling structure is arranged between the SCR denitration reactor and the heat exchangers on the flue before denitration and is perpendicular to the axial direction of the flue before denitration, an ammonia spraying uniform distribution structure is arranged between the second end of the flue before denitration and the heat exchangers on the flue before denitration, at least two ammonia spraying units are arranged on the ammonia spraying uniform distribution structure at intervals, each ammonia spraying unit is perpendicular to the axial direction of the flue before denitration, flue gas sampling holes corresponding to each ammonia spraying unit are arranged on the flue gas sampling structure, a direct-fired heating device is arranged between the second end of the flue before denitration and the ammonia spraying structure and comprises a plurality of flame burners penetrating through the side walls of the flue before denitration, the flame burners are tangential to the flame spraying center lines of each burner in a tangential direction with the flame, the flame spraying center lines of each flame are tangential to the flame spraying direction of each flame burner in a tangential direction, and the flame injection length of each flame burner is adjustably arranged, and the SCR denitration reactor and the direct-fired heating device are electrically connected with the control system.
In a preferred embodiment of the invention, a flue gas analyzer, a flue gas velocity measuring instrument and a first temperature detecting device are arranged between the heat exchanger and the ammonia spraying uniform distribution structure, a second temperature detecting device is arranged in the SCR denitration reactor, the flue gas sampling structure is connected with the ammonia analyzer, the flue gas analyzer is used for measuring the content of nitrogen oxides in flue gas, the flue gas velocity measuring instrument is used for measuring the flow velocity of flue gas in a flue before denitration, the ammonia analyzer is used for detecting the amount of ammonia in the flue gas after denitration treatment of the SCR denitration reactor, the first temperature detecting device and the second temperature detecting device are used for monitoring the temperature in real time, and the flue gas analyzer, the flue gas velocity measuring instrument, the first temperature detecting device, the ammonia analyzer and the second temperature detecting device are all electrically connected with the control system.
In a preferred embodiment of the invention, the plurality of flame burners of the direct-fired heating device form at least 2 burner groups, the number of the burner groups is even, the flame flow center line of each flame burner of each burner group is tangential to an imaginary tangent circle, the flame flow center lines of the adjacent two burner groups are opposite to the cutting direction of the imaginary tangent circle, the center axis of each flame burner is arranged at a first included angle with the horizontal direction, and the center axis of each flame burner is arranged at a second included angle with the vertical direction.
In a preferred embodiment of the present invention, the first included angle ranges from 10 ° to 50 °, and the second included angle ranges from 15 ° to 85 °.
In a preferred embodiment of the invention, each flame burner comprises a stable combustion flue structure, wherein a flame injection port is arranged at a first end of the stable combustion flue structure, a central axis of the stable combustion flue structure forms the central axis of the flame burner, a combustion-supporting air cavity and a fuel air cavity are arranged at a second end of the stable combustion flue structure in a communicating way, a stable combustion central hole is arranged on the stable combustion flue structure in an axial penetrating way, the stable combustion central hole forms a combustion mixing chamber, an igniter is arranged in the combustion mixing chamber and is electrically connected with a control system, a fuel-assisting air inlet is arranged on the combustion air cavity in a communicating way, a fuel inlet is arranged on the fuel air cavity in a communicating way, ejectors are arranged in the combustion air cavity and the combustion-supporting air cavity in a penetrating way, the ejectors and the stable combustion flue structure are coaxially arranged, the ejectors are used for accelerating the fuel gas in the ejection air cavity to the combustion mixing chamber, a necking ejection channel is formed between the combustion air cavity and the combustion mixing chamber, and the combustion-supporting air cavity passes through the ejection channel to the combustion mixing chamber.
In a preferred embodiment of the invention, the stable combustion flue structure comprises a stable combustion inner pipe and a stable combustion outer pipe which are coaxially and radially arranged at intervals, the cross section of the stable combustion inner pipe is arranged in a closed contour formed by splicing a plurality of sections of circular arcs, the cross section of the stable combustion outer pipe is circularly arranged, a stable combustion annular space is formed between the stable combustion inner pipe and the stable combustion outer pipe, and a refractory pouring material unit is filled in the stable combustion annular space.
In a preferred embodiment of the invention, a flame detector and a temperature detector are arranged in the combustion mixing chamber, the flame detector and the temperature detector are electrically connected with a control system, the flame detector is used for detecting the combustion condition of flame in the combustion mixing chamber, and the temperature detector is used for detecting the temperature in the combustion mixing chamber.
In a preferred embodiment of the invention, the ejector comprises a straight pipe section, a contraction section, a throat pipe section, an expansion section and a rectification section, wherein the straight pipe section is positioned in the gas cavity, the contraction section, the throat pipe section, the expansion section and the rectification section are positioned in the combustion-supporting gas cavity, the first end of the straight pipe section is provided with a gas inlet pipe orifice, the second end of the straight pipe section is communicated with the first end of the contraction section, the diameter of the contraction section is gradually reduced from the first end to the second end, the second end of the contraction section is communicated with the first end of the throat pipe section, the second end of the throat pipe section is communicated with the first end of the expansion section, the diameter of the expansion section is gradually expanded from the first end to the second end, the second end of the expansion section is communicated with the first end of the rectification section, and the second end of the rectification section is provided with a gas outlet pipe orifice.
In a preferred embodiment of the present invention, the rectifying section includes a rectifying inner pipe and a rectifying outer pipe which are coaxially and radially arranged at intervals, the cross section of the rectifying inner pipe is arranged in a closed contour formed by splicing a plurality of sections of circular arcs, the cross section of the rectifying outer pipe is arranged in a circular shape, a rectifying annular space is formed between the rectifying inner pipe and the rectifying outer pipe, and a refractory pouring unit is filled in the rectifying annular space.
In a preferred embodiment of the present invention, the pre-denitration flue and the denitration treatment flue are vertically disposed, the second end of the pre-denitration flue is communicated with the second end of the denitration treatment flue through a horizontal flue, and a horizontal rectifying grid is disposed at an outlet of the horizontal flue.
In a preferred embodiment of the present invention, the control system includes a measurement data summarizing and analyzing module, where the measurement data summarizing and analyzing module is configured to calculate and obtain a load of nitrogen oxides according to measurement data of the flue gas analyzer, the flue gas velocity measuring instrument, and the ammonia analyzer, and calculate an ammonia injection amount of each ammonia injection unit according to the load of nitrogen oxides.
In a preferred embodiment of the present invention, each flame burner is fixedly disposed on a side wall of the flue before denitration, and the first included angle and the second included angle are fixedly disposed.
In a preferred embodiment of the present invention, each of the flame burners is adjustably disposed on a side wall of the flue before denitration, and the first included angle and the second included angle are adjustably disposed.
Therefore, the denitration system for combustion heating in the flue provided by the invention has the following beneficial effects:
(1) In the denitration system for combustion and heating in the flue, the direct-fired heating device is arranged in the flue before denitration, and the flame combustion heat of the flame burner is utilized to directly heat the flue gas, so that the heat utilization efficiency is improved, and the heat loss is reduced;
(2) The flame burners form a swirl zone, so that a dynamic swirl effect of the flue gas is realized, turbulent flow of the flue gas is promoted, heat exchange between the flue gas and high-temperature flame is promoted, the length of the heat exchange zone in the flue is shortened, and homogenization of the temperature is realized;
(3) The flame burner adopts ejector jet technology, reduces the load of a system fan, reduces the resistance loss of a flue, improves the running stability of equipment, and has the advantages that the cross sections of the stable combustion inner pipe of the stable combustion flue structure and the rectifying section of the ejector are spliced by a plurality of sections of circular arcs, so that the contact area of combustible gas and combustion-supporting gas is increased, the combustion stability is maintained, meanwhile, the good gathering effect of jet flames is realized, the premature divergence and attenuation of the flames are avoided, the flames jetted by a plurality of flame burners are ensured to have higher kinetic energy, the efficient turbulent stirring is carried out on the flue gas of the flue, and the heat exchange is promoted;
(4) In the flue internal combustion temperature-rising denitration system, the heat exchanger utilizes the high-temperature flue gas after denitration to preheat the low-temperature flue gas before denitration, fully utilizes the waste heat, and reduces the energy consumption required by heating of the direct-fired heating device; the direct-fired heating device directly heats the flue gas, promotes the flue gas temperature to reach the temperature range of the ideal denitration reaction of the catalyst, realizes the expected denitration reaction, achieves the ultra-low emission requirement, and improves the running economic benefit of equipment;
(5) In the denitration system for combustion heating in the flue, a spoiler or a guide plate is not required to be arranged in the flue before denitration and the flue for denitration treatment, so that the equipment structure is simplified, and the whole system is simple and convenient to process and manufacture and install and easy to implement.
Drawings
The following drawings are only for purposes of illustration and explanation of the present invention and are not intended to limit the scope of the invention.
Wherein:
FIG. 1 is a schematic diagram of a denitration system for combustion and heating in a flue of the invention when flue gas enters from bottom to top.
Fig. 2 is a schematic diagram of the internal structure of the flue before denitration in fig. 1.
FIG. 3 is a cross-sectional view A-A of FIG. 2.
FIG. 4 is a side view of the flame burner of the present invention.
FIG. 5 is a cross-sectional view of a flame burner of the present invention.
Fig. 6 is a view from direction B in fig. 5.
FIG. 7 is a schematic view of an ejector according to the present invention.
Fig. 8 is a view from direction C in fig. 7.
FIG. 9 is a schematic diagram of a denitration system for heating flue gas by combustion in a flue of the invention when the flue gas enters from top to bottom.
FIG. 10 is a schematic view of the structure in the flue before denitration in FIG. 9.
In the figure:
100. A denitration system for heating up by combustion in the flue;
1. A heat exchanger;
2. an SCR denitration reactor;
3. A smoke sampling structure;
4. an ammonia spraying uniform distribution structure;
5. a direct combustion heating device;
50. Virtual tangential circle, 51, flame burner, 511, stable combustion flue structure, 512, flame injection port, 513, stable combustion central hole, 514, stable combustion inner pipe, 515, stable combustion outer pipe, 52, combustion air cavity, 521, combustion air inlet, 53, gas cavity, 531, gas inlet, 54, igniter, 55, injector, 551, straight pipe section, 552, contracted section, 553, throat section, 554, expanded section, 555, rectifying section, 5551, rectifying inner pipe, 5552, rectifying outer pipe, 556, air inlet pipe opening, 557, air outlet pipe opening, 56, flame detector, 57, temperature detector, 58, refractory casting unit;
61. A flue gas analyzer; 62 parts of a flue gas velocity measuring instrument, 63 parts of a first temperature detecting device, 64 parts of an ammonia analyzer, 65 parts of a second temperature detecting device;
91. Front flue for denitration, 911, front side wall, 912, rear side wall, 92, flue for denitration treatment, 93, flue gas inlet, 94, flue gas outlet, 95, horizontal flue, 96, rectifying grille, 97, turning elbow, 98 and deflector.
Detailed Description
For a clearer understanding of technical features, objects, and effects of the present invention, a specific embodiment of the present invention will be described with reference to the accompanying drawings.
The specific embodiments of the invention described herein are for purposes of illustration only and are not to be construed as limiting the invention in any way. Given the teachings of the present invention, one of ordinary skill in the related art will contemplate any possible modification based on the present invention, and such should be considered to be within the scope of the present invention. It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "mounted," "connected," "coupled," and "connected" are to be construed broadly, and may be, for example, mechanically or electrically connected, may be in communication with each other in two elements, may be directly connected, or may be indirectly connected through an intermediary, and the specific meaning of the terms may be understood by those of ordinary skill in the art in view of the specific circumstances. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
As shown in fig. 1 to 10, the present invention provides a denitration system 100 for heating combustion in a flue, which includes a pre-denitration flue 91, a pre-denitration flue 92, and a control system (not shown in the drawings), wherein a flue gas inlet 93 is disposed at a first end of the pre-denitration flue 91, a flue gas outlet 94 is disposed at a first end of the pre-denitration flue 92, and a second end of the pre-denitration flue 91 and a second end of the pre-denitration flue 92 are disposed in sealing communication.
The heat exchanger 1 is arranged at the position close to the flue gas inlet 93 and the flue gas outlet 94, the low-temperature flue gas channel before denitration and the high-temperature flue gas channel after denitration (the low temperature and the high temperature are in relative meanings) are arranged in the heat exchanger 1, the flue gas temperature entering through the flue gas inlet is lower than the flue gas temperature after denitration treatment, the SCR denitration reactor 2 is arranged between the second end of the denitration flue and the heat exchanger, the heat exchanger 1 utilizes the high-temperature flue gas after denitration after the SCR denitration reactor, which is preheated, to enter the low-temperature flue gas before denitration of the SCR denitration reactor, so that waste heat is fully utilized, and the energy consumption required by flue gas temperature rising before denitration is reduced.
The flue gas sampling structure 3 is arranged between the SCR denitration reactor 2 and the heat exchanger 1 on the denitration flue 92, the flue gas sampling structure 3 is arranged vertically to the axial direction of the denitration flue 92, the ammonia spraying uniform structure 4 is arranged between the second end of the flue gas before denitration and the heat exchanger 1 on the flue 91 before denitration, at least two ammonia spraying units are arranged on the ammonia spraying uniform structure 4 at intervals, each ammonia spraying unit is arranged vertically to the axial direction of the flue gas before denitration 91, flue gas sampling holes corresponding to each ammonia spraying unit are arranged on the flue gas sampling structure 3, the direct-fired heating device 5 is arranged between the second end of the flue gas before denitration and the ammonia spraying uniform structure 4, the direct-fired heating device 5 comprises a plurality of flame burners 51 penetrating through the side wall of the flue gas before denitration, the flame flow center line of each flame burner 51 is tangential to an imaginary tangential circle 50, the flame spraying direction of each flame burner 51 is opposite to the flue gas flow direction, the flame spraying lengths of each flame burner 51 are adjustable, and the SCR denitration reactor 2 and the direct-fired heating device 5 are electrically connected with a control system.
The flue gas is directly heated in the flue, so that the flue gas amount can be saved, and the engineering cost and the in-plant land can be greatly saved. The existing flue has the technical problems that the negative pressure in the flue is large, the burner is not easy to burn stably, the temperature of the flue which is in direct contact with the flame is high, the temperature of the flue which is far away from the flame is low, so that the temperature of the flue is uneven, the flame is easy to extinguish due to the scouring of the flame by the flue, the ignition point of the combustible gas is high, the content of inert gas is high, and the burner is not easy to burn stably. The direct-fired heating device for the denitration system can effectively solve the problems.
In a specific embodiment of the present invention, before direct combustion heating, the flow direction of flue gas is from bottom to top in the flue gas before denitration, the flame flow center line of the flame burner in the direct combustion heating device 5 of the present invention faces the flow direction of flue gas and is opposite to the flow direction of flue gas (from top to bottom and is in an inclined state), as shown in fig. 1, the flame burner 51 is arranged in a downward inclined manner, flame and flue gas before heating flow opposite to each other, the turbulence degree of heat exchange between high temperature flue gas and original flue gas is increased, the time required for heat exchange is shortened, the contact area between flame and flue gas is increased, the heat exchange time between high temperature flame and flue gas is increased, and the uniformity of flue gas temperature is facilitated.
In another embodiment of the present invention, as shown in fig. 9 and 10, before the direct combustion heating, the flue gas flow direction is from top to bottom in the flue before the denitration, and the flame flow center line of the flame burner in the direct combustion heating device 5 of the present invention is disposed opposite to the flue gas flow direction (from bottom to top and in an inclined state), and as shown in fig. 2, the flame burner 51 is disposed to be inclined upward.
The flame jet length of each flame burner 51 can be adjusted, the diameter and the height position of an imaginary tangential circle tangential to the flame flow center line of each flame burner can be correspondingly adjusted, different swirl mixing area control can be realized under different flue gas flow conditions, and the position of a flame high-temperature area in a flue is adjustable, so that dynamic adjustment of flue gas mixing is realized.
The ammonia spraying and uniformly distributing structure 4 comprises a plurality of ammonia spraying areas which are arranged at intervals in the cross section direction of the flue 91 before denitration, the areas of the ammonia spraying areas are the same, the ammonia spraying areas form independent ammonia spraying units, the ammonia spraying units are arranged at intervals in the cross section of the flue 91 before denitration, at least 2 ammonia spraying units are arranged transversely, at least 2 ammonia spraying units are arranged longitudinally, and the flue gas sampling structure 3 comprises flue gas sampling holes corresponding to the ammonia spraying areas one by one.
In the denitration system for combustion and heating in the flue, the direct-fired heating device is arranged in the flue before denitration, and the flame combustion heat of the flame burner is utilized to directly heat the flue gas, so that the utilization efficiency of the heat is improved, and the heat loss is reduced; the flue gas temperature-rising denitration system comprises a flue gas sampling structure, a flue gas sampling hole and an ammonia spraying unit, wherein the flue gas sampling hole is arranged corresponding to the ammonia spraying unit of the ammonia spraying uniform distribution structure, the flue gas sampling structure is used for reducing energy consumption required by heating, the flue gas sampling hole is used for reducing ammonia spraying amount control, the direct-fired heating device is used for directly heating the flue gas, promoting the flue gas temperature to reach the temperature range of the ideal denitration reaction of a catalyst, realizing the expected denitration reaction and ultra-low emission requirements, and improving the economic benefit of equipment operation.
Further, as shown in fig. 1, a flue gas analyzer 61, a flue gas velocity measuring instrument 62 and a first temperature detecting device 63 are arranged between the heat exchanger 1 and the ammonia spraying uniformly distributed structure 4, the flue gas analyzer 61 can also be arranged between the heat exchanger 1 and the flue gas inlet 93, the flue gas sampling structure 3 is connected with an ammonia analyzer 64, a second temperature detecting device 65 is arranged in the SCR denitration reactor 2, the second temperature detecting device 65 can also be arranged at the downstream of the SCR denitration reactor 2, the flue gas analyzer 61 is used for measuring the content of nitrogen oxide in flue gas, the flue gas velocity measuring instrument 62 is used for measuring the flow velocity of flue gas in a flue gas before denitration, the ammonia analyzer 64 is used for detecting the amount of ammonia in the flue gas after denitration treatment of the SCR denitration reactor, the first temperature detecting device 63 and the second temperature detecting device 65 are used for temperature real-time monitoring, the first temperature detecting device 63 detects the flue gas temperature before the direct combustion heating device 5, and the heat required by a theoretical flame burner is calculated, and the flue gas analyzer 61, the flue gas velocity measuring instrument 62, the first temperature detecting device 63, the ammonia analyzer 64 and the second temperature detecting device 65 are electrically connected with a control system.
In the denitration system, the second temperature detecting device 65 is arranged at the downstream of the SCR denitration catalyst and is used for detecting the actual temperature of the flue gas for denitration reaction, if the temperature is within the process requirement range, the flow and the proportion of the flame burner 51 are not required to be adjusted, if the temperature is lower than the process requirement, the combustion heating value of the flame burner 51 is increased, the further increase of the flue gas temperature is realized, if the temperature is higher than the process requirement, the combustion heating value of the flame burner 51 is reduced, the further decrease of the flue gas temperature is realized, the combustion heat released by the flame burner 51 is controlled through the feedback of the second temperature detecting device 65, and the flue gas temperature is controlled in the optimal temperature range of the denitration reaction.
Further, as shown in fig. 2 and 3, the direct combustion heating device 5 adopts the swirl effect of the laval nozzle injection, the plurality of flame burners 51 of the direct combustion heating device 5 form at least 2 burner groups, the number of the burner groups is even, the flame flow center line of each flame burner 51 of each burner group is tangential to an imaginary tangential circle 50, the flame flow center lines of the adjacent two burner groups are opposite to the cutting direction of the imaginary tangential circle, the center axis of each flame burner 51 is arranged at a first included angle alpha with the horizontal direction, and the center axis of each flame burner 51 is arranged at a second included angle with the vertical direction. The center lines of the flame streams of the two adjacent burner groups are opposite to the cutting-in direction of the imaginary tangential circle, namely, the center lines of the flame streams of the two adjacent burner groups and the cutting-in direction of the imaginary tangential circle adopt opposite rotational flow modes, so that the opposite impact of the two groups of rotational flow flame burners is eliminated, and the stable operation of rotational flow is realized. The number of the burner groups is even, so that the stable operation of the heating device is ensured.
Further, the first included angle alpha is in the range of 10-50 degrees, preferably in the range of 15-30 degrees, and the second included angle alpha is in the range of 15-85 degrees, preferably in the range of 30-65 degrees.
In a specific embodiment of the present invention, the pre-denitration flue 91 is a rectangular flue and is vertically disposed, and the central connecting line of two opposite side walls (a front side wall 911 and a rear side wall 912) of the pre-denitration flue 91 is a hedging central line, so that flame burners are divided into 2 groups, each of the burner groups includes 4 flame burners 51, the flame burners are in a tangential-circle combustion mode, the flame burner gas streams are fed in a tangential-circle mode, and each of the flame burners 51 forms an octagonal double-tangential-circle combustion structure. The center line of flame flow sprayed by each group of flame burners is tangential to the same imaginary tangential circle (ellipse or circle), and the rotation directions of the two groups of imaginary tangential circles (ellipse or circle) are opposite, one is clockwise, and the other is anticlockwise.
In practical engineering application, according to the size of the cross section of the denitration front flue 91, flame burners can be appropriately added on the front side wall 911 and the rear side wall 912, and flame burners can be appropriately added on the other two side walls of the denitration front flue 91.
In an embodiment of the present invention, as shown in fig. 3, the angles between the 8 flame burners and the side wall of the vertical denitration front flue 91 (i.e., the second angles) are β 1、β2、β3、β4、β5、β6、β7、β8, respectively, which ranges from 15 ° to 85 °, and preferably ranges from 30 ° to 65 °.
The flame burners 51 can be in a full swing mode (namely, the first included angle and the second included angle are adjustable) which swings up and down and left and right, so that the dynamic adjustment of flame jet flow strands of the flame burners 51 can be realized, the flame burners 51 can also be in a fixed mode, the flame burners are fixedly arranged on the side wall of the denitration front flue, and the first included angle and the second included angle are fixedly arranged. The dynamic adjustment of the size of the imaginary tangential circle is realized by adjusting the flame length of the flame burner, the cyclone mixing effect of different smoke ranges is realized, and the uniformity of the smoke temperature is realized.
Further, as shown in fig. 4, 5 and 6, each flame burner 51 comprises a stable combustion flue structure 511, the stable combustion flue structure 511 adopts a cylindrical structure, a flame injection port 512 is arranged at a first end of the stable combustion flue structure 511, a central axis of the stable combustion flue structure 511 forms the central axis of the flame burner, a combustion-supporting air cavity 52 and a fuel gas cavity 53 are arranged at a second end of the stable combustion flue structure 511 in a communicating manner, a stable combustion central hole 513 is arranged on the stable combustion flue structure 511 in an axial penetrating manner, the stable combustion central hole 513 forms a combustion mixing chamber, an igniter 54 is arranged in the stable combustion flue structure 511, the igniter 54 is electrically connected with a control system, a fuel gas inlet 521 is arranged on the combustion-supporting air cavity 52 in a communicating manner, a fuel gas inlet 531 is arranged on the fuel gas cavity 53 in a communicating manner, an ejector 55 is arranged in the fuel gas cavity 53 and the combustion-supporting air cavity 52 in a penetrating manner, the ejector 55 and the stable combustion flue structure 511 are coaxially arranged, the ejector 55 is used for accelerating combustible gas in the fuel gas cavity 53 to the combustion mixing chamber, an ejector channel is formed between the air cavity 52 and the combustion mixing chamber, and the combustion mixing chamber forms an ejector channel of a necking down, the combustion-supporting air cavity 52 is ejected through the ejector channel to the combustion mixing chamber.
The flame burner 51 adopts ejector jet technology, so that the load of a system fan is reduced, the resistance loss of a flue is reduced, and the running stability of equipment is improved. The combustion-supporting gas inlet 521 and the gas inlet 531 are connected with corresponding pipelines through flanges, and a flowmeter and a flow regulating valve are arranged on the corresponding pipelines and are electrically connected with a control system. The required amounts of combustible gas and combustion-supporting gas are calculated from the control model using the detection data of the first temperature detection device 63, and flow rate adjustment is performed by a flow rate adjustment valve (electric adjustment valve) until the flow rate reaches a predetermined required amount.
The combustion-supporting gas can be connected with the flue gas after the heat exchanger in the flue before denitration through the pipeline, and the flue gas in the flue before denitration is used as the combustion-supporting gas to carry out the combustion reaction of the flame burner, so that the combustion of the combustible gas under the condition of low oxygen concentration is realized, NOx is avoided, and the low-nitrogen combustion of the fuel gas is realized.
The combustible gas entering the flame burner can be blast furnace gas, converter gas, coke oven gas, natural gas and the like, and can also be mixed gas of blast furnace gas, converter gas, coke oven gas, natural gas and the like. The combustion-supporting gas entering the flame burner can be air, pure oxygen or raw flue gas in a flue containing a certain amount of oxygen.
Further, as shown in fig. 5 and 6, the stable combustion flue structure 511 includes a stable combustion inner pipe 514 and a stable combustion outer pipe 515 which are coaxially and radially arranged at intervals, the cross section of the stable combustion inner pipe 514 is arranged in a closed contour formed by splicing a plurality of sections of circular arcs, the cross section of the stable combustion outer pipe 515 is arranged in a circular shape, a stable combustion annular space is formed between the stable combustion inner pipe 514 and the stable combustion outer pipe 515, and a refractory casting unit 58 is filled in the stable combustion annular space. The cross section of the stable combustion inner tube 514 is spliced by a plurality of sections of circular arcs, so that the contact area of high-temperature flame and smoke is increased, the heat exchange of the smoke is promoted, meanwhile, the combustion flame is favorable for keeping a good gathering effect, the flame length is increased, and the premature divergence and attenuation of the flame are avoided.
Further, as shown in fig. 5, a flame detector 56 and a temperature detector 57 are arranged in the combustion mixing chamber, the flame detector 56 and the temperature detector 57 are electrically connected with a control system, the flame detector 56 is used for detecting the combustion condition of flame in the combustion mixing chamber, if the flame is extinguished, secondary ignition of an igniter is realized through the control system, stable combustion of the flame burner is realized, the flame detector 56 is an electric control ignition device, the temperature detector 57 is used for detecting the temperature in the combustion mixing chamber, and if the local temperature is too high, the flow and proportion relation of combustible gas and combustion-supporting gas are regulated through the control system, the temperature of the combustion mixing chamber is reduced, and low NOx combustion is realized.
Further, as shown in fig. 7 and 8, the ejector 55 comprises a straight pipe segment 551, a contracted segment 552, a throat segment 553, an expanded segment 554 and a rectifying segment 555, wherein the straight pipe segment 551 is positioned in the combustion air cavity 53, the contracted segment 552, the throat segment 553, the expanded segment 554 and the rectifying segment 555 are positioned in the combustion air cavity 52, an air inlet pipe orifice 556 is arranged at the first end of the straight pipe segment 551, a second end of the straight pipe segment 551 is communicated with the first end of the contracted segment 552, the diameter of the contracted segment 552 is gradually reduced from the first end to the second end, the second end of the contracted segment 552 is communicated with the first end of the throat segment 553, the second end of the contracted segment 552 and the throat segment 553 are in smooth transition through arcs, the second end of the throat segment 553 is communicated with the first end of the expanded segment 554, the diameter of the expanded segment 554 is gradually expanded from the first end to the second end, an air outlet pipe orifice 557 is arranged at the second end of the rectifying segment 555, and the air outlet pipe orifice 557 is arranged in the ejection channel. In one embodiment of the present invention, the length of the expansion section 554 is 6-10 times the diameter of the throat section 553, preferably in the range of 7-9 times, and the length of the rectifying section 555 is not less than 100mm. The distance between the air outlet pipe orifice 557 of the ejector and the bottom of the combustion mixing chamber is 100-300 mm, and the preferable range is 150-250 mm.
Further, as shown in fig. 8, the rectifying section 555 includes a rectifying inner tube 5551 and a rectifying outer tube 5552 which are coaxially and radially arranged at intervals, the cross section of the rectifying inner tube 5551 is arranged in a closed contour manner formed by splicing multiple sections of circular arcs, the cross section of the rectifying outer tube 5552 is arranged in a circular manner, a rectifying annular space is formed between the rectifying inner tube 5551 and the rectifying outer tube 5552, and the rectifying annular space is filled with refractory pouring units 58. The multi-arc-shaped circular section of the rectifying section 555 can promote the combustible gas to be separated from the air outlet pipe orifice 557 and still keep the multi-arc-shaped circular section to spray forwards, the multi-arc-shaped circular section increases the contact area of the combustible gas and the combustion-supporting gas, meanwhile, the combustion stability is kept, meanwhile, the jet flame has a good gathering effect, the premature divergence and attenuation of the flame are avoided, the flame jetted by a plurality of flame burners is guaranteed to have higher kinetic energy, efficient turbulent stirring is carried out on the flue gas of the flue, and heat exchange is promoted. Meanwhile, the multi-arc circular cross section structure can reduce the local oxygen content of the combustible gas combustion, reduce the local high temperature of the flame burner, avoid the generation of NOx and realize low-nitrogen combustion.
Further, as shown in fig. 1, the pre-denitration flue 91 and the denitration treatment flue 92 are vertically arranged, the second end of the pre-denitration flue 91 is communicated with the second end of the denitration treatment flue 92 through a horizontal flue 95, and a horizontal rectifying grid 96 is arranged at the outlet of the horizontal flue 95. The flue 91 can be connected with horizontal flue 95 through turning to elbow 97 before the denitration, for making the flue gas pass through smoothly, set up guide plate 98 in the horizontal flue 95, guide plate 98 plays the guide effect to the flue gas, through turning to elbow 97 through flow through horizontal flue 95 after through rectification grid 96 through the flue gas that heats up, realize the further mixing of flue gas and ammonia, carry out the mixing of energy simultaneously and realize flue gas temperature's homogeneity, flue gas and ammonia mixed gas are through rectification grid's rectification effect for flue gas and ammonia mixed gas can be even, inside the catalyst of vertical entering SCR denitration reactor, realize the high-efficient quick even reaction of nitrogen oxide and ammonia in the flue gas under the catalyst catalytic effect.
Further, the control system comprises a measurement data summarizing and analyzing module, wherein the measurement data summarizing and analyzing module is used for calculating and obtaining the load of the nitrogen oxides according to the measurement data of the flue gas analyzer, the flue gas speed measuring instrument and the ammonia analyzer, and calculating the ammonia spraying amount of each ammonia spraying unit according to the load of the nitrogen oxides.
The flue gas velocity measuring instrument 62 is used for measuring the flue gas velocity in each different transverse area in the flue before denitration, the flue gas analyzer 61 is used for measuring the content of nitrogen oxides in the flue gas, the removal load of the nitrogen oxides is calculated by utilizing a computer program, the measured data summarizing and analyzing module is used for calculating the load of the nitrogen oxides according to the flue gas flow and the flue gas components of each area, the ammonia spraying amount required by each area is calculated according to the nitrogen oxide load, the ammonia spraying branch pipes are arranged on the ammonia spraying uniformly distributed structure 4, the electric regulating valves or the pneumatic regulating valves are arranged on the ammonia spraying branch pipes, the control system regulates the ammonia spraying amount of each area through the electric regulating valves or the pneumatic regulating valves, the actual ammonia spraying amount is monitored according to the flowmeter on the ammonia spraying branch pipes, the ammonia analyzer 64 is used for detecting the ammonia amount (namely the ammonia escape amount) in the flue gas after denitration treatment of the SCR denitration reactor, the ammonia spraying amount is controlled in a feedback mode according to the ammonia escape amount in each area, and when the ammonia escape amount exceeds a set value, the ammonia spraying amount in the corresponding area is prompted to be too large, the ammonia spraying amount in the area is correspondingly reduced, and the ammonia consumption and the ammonia escape amount in the ammonia is realized.
The following describes the operation of the flue gas inlet 93 at the bottom of the pre-denitration flue, as an example, of the combustion-heating denitration system 100 in the flue of the present invention:
Raw flue gas (unpurified flue gas before denitration) enters the flue gas internal combustion heating denitration system 100 of the invention through the flue gas inlet 93, the flue gas is preheated and heated through the heat exchanger 1, the heated flue gas flows through the flue gas analyzer 61 and the flue gas speed measuring instrument 62, the ammonia spraying and uniformly distributing structure 4 performs ammonia spraying operation, the sprayed ammonia gas is mixed with the flue gas, the flue gas mixed with the ammonia gas continuously rises, the temperature of the flue gas is measured by the first temperature detecting device 63, the high-efficiency combustion of combustible gas and combustion air is performed in the flame burner of the direct-fired heating device 5, the rapid mixing and heat exchange of the high-temperature gas and the flue gas are promoted by the jet swirling action of a plurality of flame burners, and the temperature of the mixed gas of the flue gas and the ammonia gas is further improved;
The flue gas heated and warmed up flows through the horizontal flue 95 through the steering elbow 97 and then passes through the rectification grating 96, so that further mixing of the flue gas and the ammonia gas is realized, meanwhile, energy mixing is carried out to realize uniformity of the temperature of the flue gas, and the mixed gas of the flue gas and the ammonia gas can uniformly and vertically enter the inside of a catalyst of the SCR denitration reactor through the rectification function of the rectification grating, so that efficient, rapid and uniform reaction of nitrogen oxides and the ammonia gas in the flue gas under the catalytic effect of the catalyst is realized;
The flue gas mixed gas after passing through the catalyst of the SCR denitration reactor flows through the flue gas sampling structure 3, the ammonia analyzer 64 detects the ammonia content in the mixed gas, the ammonia concentration is controlled to be lower than a set value, if the ammonia content exceeds the set value, the ammonia content is fed back to the control system, the ammonia spraying amount of the ammonia spraying uniformly distributed structure 4 is reset, the ammonia spraying amount of the ammonia spraying unit is regulated, the residual ammonia content at the downstream of the SCR denitration reactor is continuously monitored, the residual ammonia content is enabled to meet the set value, and the mixed gas after denitration enters the heat exchanger 1 and flows through the flue gas outlet 94 to enter the downstream dust remover (prior art).
Therefore, the denitration system for combustion heating in the flue provided by the invention has the following beneficial effects:
(1) In the denitration system for combustion and heating in the flue, the direct-fired heating device is arranged in the flue before denitration, and the flame combustion heat of the flame burner is utilized to directly heat the flue gas, so that the heat utilization efficiency is improved, and the heat loss is reduced;
(2) The flame burners form a swirl zone, so that a dynamic swirl effect of the flue gas is realized, turbulent flow of the flue gas is promoted, heat exchange between the flue gas and high-temperature flame is promoted, the length of the heat exchange zone in the flue is shortened, and homogenization of the temperature is realized;
(3) The flame burner adopts ejector jet technology, reduces the load of a system fan, reduces the resistance loss of a flue, improves the running stability of equipment, and has the advantages that the cross sections of the stable combustion inner pipe of the stable combustion flue structure and the rectifying section of the ejector are spliced by a plurality of sections of circular arcs, so that the contact area of combustible gas and combustion-supporting gas is increased, the combustion stability is maintained, meanwhile, the good gathering effect of jet flames is realized, the premature divergence and attenuation of the flames are avoided, the flames jetted by a plurality of flame burners are ensured to have higher kinetic energy, the efficient turbulent stirring is carried out on the flue gas of the flue, and the heat exchange is promoted;
(4) In the flue internal combustion temperature-rising denitration system, the heat exchanger utilizes the high-temperature flue gas after denitration to preheat the low-temperature flue gas before denitration, fully utilizes the waste heat, and reduces the energy consumption required by heating of the direct-fired heating device; the direct-fired heating device directly heats the flue gas, promotes the flue gas temperature to reach the temperature range of the ideal denitration reaction of the catalyst, realizes the expected denitration reaction, achieves the ultra-low emission requirement, and improves the running economic benefit of equipment;
(5) In the denitration system for combustion heating in the flue, a spoiler or a guide plate is not required to be arranged in the flue before denitration and the flue for denitration treatment, so that the equipment structure is simplified, and the whole system is simple and convenient to process and manufacture and install and easy to implement.
The foregoing is illustrative of the present invention and is not to be construed as limiting the scope of the invention. Any equivalent changes and modifications can be made by those skilled in the art without departing from the spirit and principles of this invention, and are intended to be within the scope of this invention.
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