CN113522012A - Flue gas denitration ammonia injection mixing system, static mixer thereof and ammonia injection control method - Google Patents

Flue gas denitration ammonia injection mixing system, static mixer thereof and ammonia injection control method Download PDF

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Publication number
CN113522012A
CN113522012A CN202010293832.2A CN202010293832A CN113522012A CN 113522012 A CN113522012 A CN 113522012A CN 202010293832 A CN202010293832 A CN 202010293832A CN 113522012 A CN113522012 A CN 113522012A
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ammonia
static mixer
dust
flue
pipe
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CN113522012B (en
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李磊
李欣
金平
韩天竹
李睿
高峰
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Sinopec Dalian Petrochemical Research Institute Co ltd
China Petroleum and Chemical Corp
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China Petroleum and Chemical Corp
Sinopec Dalian Research Institute of Petroleum and Petrochemicals
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8628—Processes characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/346—Controlling the process
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/76—Gas phase processes, e.g. by using aerosols
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/206—Ammonium compounds
    • B01D2251/2062—Ammonia
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases
    • 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
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/10—Capture or disposal of greenhouse gases of nitrous oxide (N2O)

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Dispersion Chemistry (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

The invention discloses a static mixer, which is arranged in a flue, and comprises: a plurality of flow guide assemblies distributed in the flue, each flow guide assembly comprising: an inlet duct extending in an axial direction of the flue; the outer pipe is of a tubular structure with a thin lower part and a thick upper part, the lower end of the outer pipe is connected with the outer wall of the air inlet pipe, and the upper end of the outer pipe is higher than the air inlet pipe; a top plate disposed above the outer tube; an air outlet channel extending obliquely downward from the top end periphery of the outer tube; and a dust exhaust hole provided at a lower end of the outer pipe; and the ash collecting layer is connected with the inner wall of the flue in a sealing way, and an ash collecting groove is formed between the flow guide assemblies. The invention also discloses a flue gas denitration ammonia injection mixing system and an ammonia injection control method thereof. According to the invention, the guide assembly is arranged, so that twice flue gas dust removal is realized, and dust particles with larger particle sizes in the flue gas can be effectively removed; the static mixer can also effectively block large dust falling from the upper flue, and prevent the ammonia nozzle from being blocked.

Description

Flue gas denitration ammonia injection mixing system, static mixer thereof and ammonia injection control method
Technical Field
The invention relates to the technical field of flue gas denitration, in particular to a flue gas denitration ammonia injection mixing system, a static mixer of the flue gas denitration ammonia injection mixing system and an ammonia injection control method.
Background
At present, the most widely applied method in the flue gas denitration method is a Selective Catalytic Reduction (SCR) denitration technology. The main principle of the SCR denitration technology is that reducing agent ammonia is sprayed into flue gas with the temperature of 280-420 ℃, is uniformly mixed with the flue gas, and NH is generated under the action of a catalyst3Removing NO from flue gasxReducing the nitrogen into non-toxic and pollution-free nitrogen and water, thereby realizing the removal of NO from the mixed gasxThe purpose of (1).
Flue gas denitration efficiency and NH3The escape rate is two core performance indexes of the SCR denitration technology. Researches show that the flow field uniformity of the mixed gas on the cross section in the SCR reactor is a key factor for ensuring the complete SCR denitration reaction, improving the denitration efficiency and the ammonia utilization rate and keeping the low ammonia escape rate. The mixed gas flow field uniformity mainly comprises gas velocity distribution uniformity and reducing agent NH3The uniformity of the concentration distribution.
In the prior art, the mainstream technical means for adjusting the uniformity of the mixed gas flow field at the inlet of the SCR catalyst bed layer depends on an ammonia spraying mixing device (system) arranged in a flue gas pipeline, a guide plate (linear and arc) and a rectifying grating and other devices at the downstream of the ammonia spraying mixing device (system). Wherein, the guide plate and the rectifying grating are mainly used for the uniform distribution of gas velocity and the adjustment of velocity vector direction, and for NH3Limited regulation of concentration profile; the ammonia spraying mixing device (system) is used for gas velocity distribution uniformity and NH3The concentration distribution uniformity has ideal effects in two aspects. Thus, the ammonia injection mixing deviceResearch and optimization of the (system) become research hotspots of SCR denitration technology in recent years.
GB/T34339 and 2017 coal-fired flue gas denitration ammonia injection mixing system divides the ammonia injection mixing system into an Ammonia Injection Grid (AIG) and an ammonia injection static mixer, wherein the AIG is defined as an injection device for injecting ammonia gas into a flue in the form of a grid pipeline and comprises an ammonia injection pipeline, a nozzle, a support and accessories; the definition of the ammonia-spraying static mixer is that a certain fixed part is utilized, and the flowing state of ammonia gas and flue gas is changed to ensure that the ammonia gas and the flue gas are fully mixed, so that higher NH is obtained3/NOxThe efficiency of mixing. Typical ammonia injection static mixers have the structural forms of vortex, rotational flow, longitudinal vortex, V-shaped and the like.
The ammonia spraying mixing system is generally arranged in front of the dust remover, the dust content in the flue gas is high, the nozzle is easily blocked, a large amount of dust enters the SCR catalyst bed layer through the ammonia spraying mixing system, and the pore channel of the catalyst bed layer is easily blocked locally. In recent years, under the influence of factors such as economic acceleration and slowing, environmental protection pressure increase and the like, the utilization hours of coal-fired units, heating furnaces, incinerators, waste heat boilers and the like are continuously reduced, the coal-fired units, the heating furnaces, the incinerators, the waste heat boilers and the like are in low-load operation for a long time, the smoke gas quantity is reduced, the ammonia injection quantity is reduced, and at the moment, nozzles are easy to block.
At present, ammonia injection control in the SCR denitration technology mainly focuses on two aspects: (1) controlling the total amount of sprayed ammonia, and arranging NO on the inlet and outlet flues of the flue gas denitration reactorxAn online detector is arranged on the flue, and the online detector for the flue gas flow is arranged on the flue, so that the opening of an ammonia gas valve is adjusted through online detection and calculation of gas at the inlet and the outlet of the denitration reactor, the total ammonia spraying amount is controlled, and NO at the outlet of the denitration reactor is ensuredxAnd (5) reaching the standard. (2) The uniformity of the sprayed ammonia is controlled, and the uniformity of the sprayed ammonia is generally adjusted when the device is started, and NO in an inlet flue or an outlet flue of the SCR reactor is actually measured according to the sitexThe concentration distribution adjusts the manual regulating valve for ammonia injection one by one, NOxIn the area with higher concentration, the corresponding ammonia spraying manual regulating valve increases the opening degree, otherwise, the opening degree is reduced, the ammonia spraying uniformity (ammonia nitrogen molar ratio) is ensured by repeatedly adjusting for many times, and the ammonia nitrogen molar ratio in different areas is made to be as great as possibleThe ratio tends to be uniform. Because the time consumption for adjusting the ammonia spraying uniformity is long and the technical content is high during the startup each time, a professional company is generally entrusted to adjust the SCR denitration device during the startup, and the opening degree of the manual ammonia spraying adjusting valve is not adjusted after the adjustment is finished.
Existing SCR inlet and outlet NOxThe concentration detection is generally carried out by adopting single-point measurement, the monitoring point is generally arranged at the center of the flue, but NO on the same cross section of the fluexThe concentration difference is large, the single-point detection has poor representativeness, and the faithful reflection of NO is difficultxThe case of average concentration; when the load, the combustion mode and the combustion coal type of the device are changed, the distribution of the smoke gas flow field in the flue is changed under different working conditions, and NO in the smoke gasxThe concentration distribution also changes, the opening degree of an ammonia spraying manual regulating valve which is arranged when the device is started can not meet the requirements under other working conditions, the ammonia spraying uniformity is worsened, the deviation between the ammonia nitrogen molar ratio of a local area and the average value is increased, and the area with the excessively small ammonia nitrogen molar ratio has low denitration efficiency and low NO outletxThe ammonia escape in the area with excessively large ammonia nitrogen molar ratio exceeds the standard. Along with the increase of the environmental protection attention of the state, the local environmental protection agency pays attention to the NO of the flue gasxThe punishment degree of exceeding standard is gradually increased, and NO in the exhaust smoke of enterprises is discharged by the environmental protection bureauxThe concentration is dynamically monitored in real time, the ammonia escape value is not brought into the monitoring range, and in order to ensure that the environmental protection reaches the standard, enterprises generally discharge the NO out of the smoke by increasing the ammonia injection amountxThe ammonia escape of the SCR denitration device is greatly increased due to the control in a lower interval, equipment such as a rear-end air preheater or an economizer is corroded and leaked or is seriously blocked, and the content of ammonia nitrogen in the desulfurization wastewater is greatly exceeded if a wet desulfurization device is arranged subsequently.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Disclosure of Invention
One of the purposes of the invention is to provide a flue gas denitration ammonia spraying mixing system, a static mixer thereof and an ammonia spraying control method, so that the blockage of structures such as an ammonia gas nozzle, catalyst bed layer pore channels in the flue gas denitration technology, rear-end equipment and the like is relieved.
Another objective of the present invention is to provide an ammonia spraying mixing system for flue gas denitration, a static mixer thereof, and an ammonia spraying control method, so as to improve the mixing uniformity of ammonia gas and flue gas and reduce the ammonia escape rate.
The invention further aims to provide a flue gas denitration ammonia injection mixing system, a static mixer thereof and an ammonia injection control method, so that the problems of blockage, corrosion leakage and over-standard ammonia nitrogen of desulfurization wastewater in subsequent treatment caused by ammonia escape of an air preheater or an economizer are avoided.
To achieve the above object, according to a first aspect of the present invention, there is provided a static mixer provided in a flue, the static mixer comprising: a plurality of flow guide assemblies distributed in the flue, each flow guide assembly comprising: an inlet duct extending in an axial direction of the flue; the outer pipe is of a tubular structure with a thin lower part and a thick upper part, the lower end of the outer pipe is connected with the outer wall of the air inlet pipe, and the upper end of the outer pipe is higher than the air inlet pipe; a top plate disposed above the outer tube; an air outlet channel extending obliquely downward from the top end periphery of the outer tube; and a dust exhaust hole provided at a lower end of the outer pipe; and the ash collecting layer is connected with the inner wall of the flue in a sealing way, and an ash collecting groove is formed between the flow guide assemblies.
Further, in the above technical scheme, the air inlet pipe is of a tubular structure with a thick lower part and a thin upper part.
Furthermore, in the above technical scheme, the dust exhaust hole is communicated with the dust exhaust pipe, the dust exhaust pipe inclines upwards, and the lower end face of the outlet of the dust exhaust pipe is higher than the upper end face of the dust exhaust hole.
Further, among the above-mentioned technical scheme, the dust exhaust hole intercommunication dust exhaust pipe, the dust exhaust pipe downward sloping, the export of dust exhaust pipe is equipped with first apron, and first apron can be closed or open the dust exhaust pipe.
Further, in the above technical scheme, the pipe orifice of the dust exhaust pipe is wedge-shaped, and the first cover plate covers the pipe orifice so as to close the dust exhaust pipe; when the pressure of the dust accumulated in the dust exhaust pipe on the first cover plate exceeds the gravity of the first cover plate, the first cover plate is lifted so as to open the dust exhaust pipe.
Furthermore, in the above technical scheme, the air outlet channel is formed by enclosing an upper wing plate and a lower wing plate, the upper wing plate is connected with the top plate, and the lower wing plate is connected with the top end of the outer pipe.
Further, in the above technical solution, the top plate is circular, rectangular, regular polygonal, inverted conical or inverted pyramidal.
Furthermore, among the above-mentioned technical scheme, be equipped with the deep bead on the lateral wall of outer tube, the deep bead is to the bottom slope of dust collecting tank.
Furthermore, in the above technical scheme, the dust collecting groove is a V-shaped groove or an arc-shaped groove.
Further, in the above technical solution, the static mixer further includes: and the ash discharge pipeline is used for discharging the dust in the ash collection groove out of the flue.
Further, among the above-mentioned technical scheme, be equipped with a plurality of row's ash holes on the collection ash layer, row's ash hole sets up the bottom at the collection ash groove, and row's ash hole is linked together with the ash discharge pipeline.
Further, among the above-mentioned technical scheme, the ash discharge pipe includes: the first vertical sections are respectively communicated with the ash discharge holes; and the discharge pipe section is communicated with the lower end of the first vertical section, the discharge pipe section is arranged in a downward inclined mode, and the tail end of the discharge pipe section extends to the outside of the flue.
Further, in the above technical scheme, the discharge pipe section is provided with an on-off valve.
Further, in the above technical scheme, the end of the discharge pipe section is provided with a second cover plate, and the second cover plate can close or open the discharge pipe section.
Further, in the above technical solution, the end of the discharge pipe section is wedge-shaped, and the second cover plate covers the end to close the discharge pipe section; when the pressure of the dust accumulated in the discharge pipe section on the second cover plate exceeds the gravity of the second cover plate, the second cover plate is lifted so as to open the discharge pipe section.
Further, in the above technical solution, the first vertical sections in the same row share one discharge pipe section.
Further, among the above-mentioned technical scheme, when static mixer is the multilayer, the end of the discharge tube section that corresponds from top to bottom communicates through the vertical section of second, and the dust is discharged by the vertical section of second.
According to a second aspect of the present invention, the present invention provides a flue gas denitration ammonia injection mixing system, which comprises in sequence along the flow direction of flue gas: a plurality of ammonia gas nozzles; and according to the static mixer in any one of the technical schemes, the plurality of flow guide assemblies are arranged corresponding to the ammonia gas nozzle.
Further, in the above technical scheme, each flow guide assembly corresponds to the same number of ammonia nozzles.
Further, in the above technical solution, the flue at the upstream of the static mixer is divided into a plurality of first ammonia injection zones, each first ammonia injection zone corresponds to one or more diversion assemblies, the ammonia nozzle in each first ammonia injection zone is connected with an ammonia injection main pipe, the ammonia injection main pipes of the plurality of first ammonia injection zones are connected with an ammonia injection main pipe, the ammonia injection main pipe is provided with a first flow regulating valve, and the ammonia injection main pipe is provided with a second flow regulating valve; the flue at the downstream of the static mixer is divided into a plurality of second ammonia spraying subareas, each second ammonia spraying subarea corresponds to one or more first ammonia spraying subareas, and each second ammonia spraying subarea is provided with a flue gas detector.
Furthermore, in the above technical scheme, the flue gas detector monitors NO of the second ammonia injection partition in real timexConcentration and ammonia concentration.
Further, among the above-mentioned technical scheme, spout the female pipe of ammonia and be equipped with first ammonia flowmeter, spout the ammonia house steward and be equipped with second ammonia flowmeter.
According to a third aspect of the present invention, the present invention provides an ammonia injection control method, which is used in the flue gas denitration ammonia injection mixing system according to any one of the above technical solutions, and the ammonia injection control method at least includes the following steps: dividing a flue at the upstream of the static mixer into a plurality of first ammonia spraying subareas, wherein the first ammonia spraying subareas are arranged corresponding to the flow guide assembly of the static mixer; dividing a flue at the downstream of the static mixer into a plurality of second ammonia injection zones, wherein each second ammonia injection zone corresponds to one or more first ammonia injection zones; obtaining NO from multiple second ammonia injection zonesxAverage concentration, average ammonia nitrogen molar ratio, and each second sprayAmmonia nitrogen molar ratio of the ammonia subareas; according to NOxCalculating the total flow of the ammonia injection required by the concentration average value and the flue gas flow; adjusting the actual total flow of ammonia injection to the required total flow of ammonia injection; and adjusting the ammonia injection flow of each first ammonia injection subarea to enable the ammonia nitrogen molar ratio of each second ammonia injection subarea to be equal to the average ammonia nitrogen molar ratio.
Compared with the prior art, the invention has the following beneficial effects:
1. the static mixer is provided with the flow guide assembly, so that the flow velocity of flue gas entering the outer pipe from the air inlet pipe is reduced, dust particles with larger particle sizes sink to the joint of the lower end of the outer pipe and the air inlet pipe under the action of self gravity, and are discharged through the dust discharge hole, and the first separation of dust and the flue gas is realized; the flue gas after first dust removal changes the flow direction through air outlet channel and leaves the water conservancy diversion subassembly, and the flue gas flow direction becomes to incline downwards, and the mutual striking takes place for two strands of flue gases of adjacent water conservancy diversion subassembly, and the dust in the flue gas falls into the ash collecting layer, realizes dust and flue gas secondary separation. The static mixer can realize twice dust removal, effectively remove dust particles in the flue gas, and prevent the dust particles from entering a subsequent SCR denitration reactor to block pore passages of a catalyst bed or generate abrasion on the catalyst bed, thereby prolonging the service life of the catalyst.
2. The flue gas enters the air inlet pipe of the flow guide assembly, particularly, when the air inlet pipe is a reducer pipe with a thick lower part and a thin upper part, the flow area of the flue gas is reduced, the flow speed is increased, dust in the flue gas collides and is converged in the process, and the particle size of dust particles is increased; the smoke enters the outer pipe through the air inlet pipe, the smoke flow area is increased, the flow speed is reduced, the retention time of the smoke in the outer pipe is increased, dust is settled under the action of self gravity, the outer pipe is of a tubular structure with a thin lower part and a thick upper part, and the dust falling onto the inner wall of the outer pipe can slide downwards along the inner wall of the outer pipe under the action of self gravity and is discharged through the dust discharge hole; when the flue gas turns to and gets into outlet channel, because the flue gas flow area of outlet channel reduces, therefore the flue gas velocity of flow increases once more, and the dust in the flue gas collides and gathers at this in-process, and the particle size of dust granule increases, is favorable to subsequent collision desorption. The flue gas flows through the diversion component of the static mixer, the flow velocity is increased firstly and then reduced and then increased, dust in the flue gas collides and gathers in the process, the particle size is increased, and the high-efficiency removal of the dust is facilitated.
3. The top plate is designed into an inverted cone shape or an inverted pyramid structure, and the flue gas moves towards the position far away from the center of the top plate under the action of the airflow and the top plate inclined structure when impacting the top plate, so that the dust is prevented from falling into the air inlet pipe again to form secondary entrainment.
4. The dust exhaust hole of water conservancy diversion subassembly communicates the dust exhaust pipe, through sealed design, can effectively prevent the flue gas by the discharge hole discharge, but the dust can get into the dust collecting layer by the discharge hole, effectively realizes the discharge of dust in the water conservancy diversion subassembly.
5. The dust collecting groove is provided with the wind shield, so that most of smoke is blocked above the dust collecting groove, a large amount of smoke is prevented from entering the dust collecting groove to blow dust, and even if a small amount of smoke entering the dust collecting groove can blow the dust, most of the blown dust can fall into the dust collecting groove again under the action of the wind shield, and secondary entrainment of the dust is effectively avoided; the wind shield inclines towards the bottom of the dust collecting groove, so that dust falling on the wind shield can slide into the dust collecting groove; under unusual operating mode, the flue gas takes place the bias flow, and when flue cross section local temperature was too high, the gap between two deep beads and the V type or the arc groove structure of dust collecting tank can effectively cushion the thermal energy that local temperature was too high to cause, prevents local deformation.
6. The static mixer is arranged above the ammonia nozzle, ammonia and flue gas enter the flow guide assembly of the static mixer together, the flow rate of the gas is increased and then decreased, the flow direction of the gas is changed and the gas collides with the wall of the device, the ammonia and the flue gas are effectively mixed in the process, then the mixed gas leaves the flow guide assembly from the gas outlet channel and collides with the flue gas of the adjacent flow guide assembly, and two mixed flue gases are forcibly mixed, so that the mixing effect of the flue gas and the ammonia gas is effectively enhanced, the mixing uniformity is improved, the distance required by uniform mixing is shortened, the ammonia escape rate is greatly reduced, the blockage or leakage of equipment such as a rear-end air preheater or a coal economizer is relieved, and the operation period of the device can be effectively prolonged.
7. Static mixer can set up to the multilayer to the specification size of water conservancy diversion subassembly can be different, can realize the striking of different regional flue gases in the flue and mix, has strengthened the mixing uniformity of ammonia and flue gas, reduces gas velocity distribution deviation and ammonia concentration distribution deviation on the same cross section of flue, improves the denitration rate of flue gas and the utilization ratio of catalyst, thereby effectively reduces ammonia and escapes.
8. The ash discharge pipeline can be provided with an on-off valve to discharge the dust regularly or irregularly; the dust discharging device can also be provided with an automatically opened and closed cover plate to control the dust discharge, when a certain amount of dust is accumulated in the dust discharging pipeline, the cover plate is pushed to lift up to discharge the dust, and the dust discharging process is unmanned; when the dust amount in the dust discharging pipeline is reduced, the cover plate can be automatically closed under the action of self gravity, and the smoke gas leakage is avoided.
9. Due to the fact that large blocks of dust fall off due to impact or disturbance of flowing smoke gas, the falling large blocks of dust can stay on a top plate or fall on a dust collecting layer under the blowing of the smoke gas, and therefore the dust is prevented from falling onto an ammonia nozzle through an air inlet pipe; the flue is sealed with the ash collecting layer, and the bold dust that drops can be collected by the ash collecting layer, avoids the bold dust to fall the ammonia nozzle. The static mixer disclosed by the invention realizes a dust separation function, avoids uneven ammonia gas injection caused by the blockage of the nozzle by dust, and can improve the denitration efficiency, so that the normal injection of the ammonia gas nozzle is realized in the whole operation period of the denitration device, the uniformity of ammonia gas on the same flue cross section is further ensured, the effective utilization of the whole denitration catalyst bed layer is ensured, the ammonia escape rate is reduced, the blockage or leakage of equipment such as a rear-end air preheater or an economizer is reduced, and the overhaul period and the service life of the device are prolonged.
10. The flue gas flow field deviation and the concentration deviation are greatly reduced after passing through the static mixer, then the horizontal cross section of the downstream flue of the static mixer is divided into a plurality of second ammonia spraying subareas, and NO of the second ammonia spraying subareas is adoptedxThe average concentration value is used as the regulation basis of the total flow of the ammonia gas. And adopts single point to measure NO in the flue gasxConcentration comparison, NO after the ammonia injection control method of the invention is adoptedxThe concentration measurement is more accurate, so the total flow of the injected ammonia gas is more accurate.
11. The ammonia nitrogen molar ratio average value of the second ammonia spraying subarea is used as the ammonia gas flow adjusting basis of the first ammonia spraying subarea, the two-stage adjustment is adopted to be more favorable for accurately controlling the ammonia gas flow, the uniformity of ammonia nitrogen distribution on the same cross section of a flue at the rear part of the static mixer is improved, the ammonia gas utilization rate is further improved, and the ammonia escape is reduced. The problems that equipment such as a rear-end air preheater or an economizer is corroded and leaked or is seriously blocked due to excessive ammonia injection and the content of ammonia nitrogen in the desulfurization wastewater of a subsequent wet desulfurization device exceeds the standard are solved.
The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood and to make the technical means implementable in accordance with the contents of the description, and to make the above and other objects, technical features, and advantages of the present invention more comprehensible, one or more preferred embodiments are described below in detail with reference to the accompanying drawings.
Drawings
Fig. 1 is a schematic cross-sectional view of a static mixer according to an embodiment of the present invention.
Fig. 2 is a schematic top view of the static mixer shown in fig. 1.
Fig. 3 is a schematic bottom view of the static mixer shown in fig. 1.
Fig. 4 is a schematic cross-sectional view of a static mixer according to another embodiment of the present invention.
Fig. 5 is a schematic top view of the static mixer shown in fig. 4.
Fig. 6 is a schematic bottom view of the static mixer of fig. 4.
Fig. 7 is a schematic cross-sectional view of a static mixer according to another embodiment of the present invention.
Fig. 8 is a schematic sectional view of a flue gas denitration ammonia injection mixing system according to an embodiment of the invention.
FIG. 9 is a schematic view of the first ammonia injection zone of FIG. 8.
FIG. 10 is a schematic view of the second ammonia injection zone of FIG. 8.
Description of the main reference numerals:
100-flue, 120-flow guide assembly, 121-air inlet pipe, 122-outer pipe, 123-top plate, 124-air outlet channel, 1241-upper wing plate, 1242-lower wing plate, 125-dust exhaust hole, 1251-dust exhaust pipe, 130-dust collection layer, 131-V-shaped groove, 132-dust exhaust hole, 140-dust exhaust pipeline, 141-first vertical section, 142-discharge pipe section and 143-on-off valve;
200-flue, 220-flow guide assembly, 221-air inlet pipe, 222-outer pipe, 223-top plate, 224-air outlet channel, 2241-upper wing plate, 2242-lower wing plate, 225-dust exhaust hole, 2251-dust exhaust pipe, 2252-first cover plate, 230-dust collection layer, 231-arc groove, 2311-wind shield, 232-dust exhaust hole, 240-dust exhaust pipeline, 241-first vertical section, 242-discharge pipe section, 243-second cover plate;
300-flue, 344-second vertical section, 345-second cover plate;
400-flue, 411-first ammonia injection zone, 412-second ammonia injection zone, 420-flow guide assembly, 430-ash collecting layer, 440-ash discharge pipeline, 450-ammonia nozzle, 451-ammonia injection main pipe, 4511-first flow regulating valve, 4512-first ammonia flowmeter, 452-ammonia injection main pipe, 4521-second flow regulating valve, 4522-second ammonia flowmeter, 460-flue gas detector, 470-dilution air pipeline, 471-ammonia air mixer.
Detailed Description
The following detailed description of the present invention is provided in conjunction with the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the specific embodiments.
Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.
Spatially relative terms, such as "below," "lower," "upper," "above," "upper," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the object in use or operation in addition to the orientation depicted in the figures. For example, if the items in the figures are turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the elements or features. Thus, the exemplary term "below" can encompass both an orientation of below and above. The article may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative terms used herein should be interpreted accordingly.
In this document, the terms "first", "second", etc. are used to distinguish two different elements or portions, and are not used to define a particular position or relative relationship. In other words, the terms "first," "second," and the like may also be interchanged with one another in some embodiments.
Referring to fig. 1 to 3, a static mixer according to an embodiment of the present invention is disposed in a flue 100, and includes a plurality of flow guide assemblies 120 distributed in the flue, each flow guide assembly 120 includes an air inlet pipe 121 extending along an axial direction of the flue, and the air inlet pipe 121 is externally sleeved with an outer pipe 122. The outer tube 122 is a tubular structure with a thin lower part and a thick upper part, the lower end of the outer tube 122 is connected with the outer wall of the air inlet tube 121, and the upper end of the outer tube 122 is higher than the air inlet tube 121. A top plate 123 is arranged above the outer pipe 122, an air outlet channel 124 is obliquely and downwardly extended from the periphery of the top end of the outer pipe 122, and a dust exhaust hole 125 is formed at the joint of the lower end of the outer pipe 122 and the air inlet pipe 121 and used for discharging dust out of the flow guide assembly 120. The ash collection layer 130 is connected with the inner wall of the flue 100 in a sealing manner, and forms an ash collection groove between the guide assemblies 120. For example, the dust collecting groove may be a V-shaped groove 131, and may also be an arc-shaped groove 231 (shown in fig. 4), which is not limited by the present invention. After entering the outer pipe 122 from the gas inlet pipe 121, the flow rate of the flue gas is reduced, dust particles with larger particle sizes in the flue gas sink to the joint of the lower end of the outer pipe 122 and the gas inlet pipe 121 under the action of self gravity, and are discharged through the dust discharge holes 125, so that the first separation of the dust and the flue gas is realized; the flue gas after the first dust removal changes the flow direction through the air outlet channel 124 and leaves the flow guide assembly 120, the flow direction of the flue gas changes to be inclined downwards, two streams of flue gas of the adjacent flow guide assemblies 120 collide with each other, and dust in the flue gas falls into the dust collecting layer 130, so that the secondary separation of the dust and the flue gas is realized. The static mixer can realize twice dust removal, effectively remove dust particles in the flue gas, and prevent the dust particles from entering a subsequent SCR denitration reactor to block pore passages of a catalyst bed or generate abrasion on the catalyst bed, thereby prolonging the service life of the catalyst. The static mixer can also realize a dust separation function, and prevent the nonuniform ammonia gas injection caused by the nozzle blockage of dust, so that the normal injection of the ammonia gas nozzle is realized in the whole operation period of the denitration device, the uniformity of the ammonia gas on the cross section of the same flue is further ensured, the whole denitration catalyst bed layer can be effectively utilized, the ammonia escape rate is reduced, and the blockage of equipment such as a rear-end air preheater or an economizer is reduced; in addition, corrosive substances can be generated due to ammonia escape, the ammonia escape rate is reduced, and leakage of structures such as an economizer and the like caused by corrosion can be reduced, so that the overhaul period and the service life of the device are prolonged.
Further, in one or more exemplary embodiments of the present invention, the dust exhaust hole 125 communicates with the dust exhaust pipe 1251 inclined upward, and a lower end surface of an outlet of the dust exhaust pipe 1251 is higher than an upper end surface of the dust exhaust hole 125, so as to use dust in the dust exhaust pipe 1251 to perform a sealing function and prevent the smoke from leaking through the dust exhaust hole 125.
Further, in one or more exemplary embodiments of the present invention, the air outlet passage 124 is enclosed by an upper wing plate 1241 and a lower wing plate 1242, the upper wing plate 1241 is connected to the top plate 123, and the lower wing plate 1242 is connected to the top end of the outer tube 122. Illustratively, upper wing 1241 and lower wing 1242 are disposed parallel and in correspondence. The flue gas flowing through the guide assembly 120 adjacent to the inner wall of the flue 100 may collide with the inner wall of the flue 100, the dust falls on the dust collecting layer 130, and a V-shaped groove 131 may be formed between the inner wall of the flue 100 and the guide assembly 120 for dust collection, which is not limited in the present invention. Illustratively, the cross section of the outer tube 122 is circular, rectangular or regular polygonal, and the shape of the top plate 123 matches the shape of the top end of the outer tube 122 to block dust falling above from entering the outer tube 122. Illustratively, the top plate 123 may have a circular shape, a rectangular shape (as shown in fig. 2), a regular polygon shape, an inverted conical shape (as shown in fig. 4 and 5), or an inverted pyramid shape, but the present invention is not limited thereto. The top plate 123 and the upper wing plate 1241 may be integrally formed to improve the sealing property therebetween.
Further, in one or more exemplary embodiments of the present invention, a plurality of dust discharge holes 132 (as shown in fig. 2) are formed in the dust collecting layer 130, and the dust discharge holes 132 are formed at the bottom of the V-groove 131. The plurality of dust discharge holes 132 may have the same size, may have different sizes, may be uniformly distributed, and may also be distributed according to different areas. The dust discharging hole 132 is communicated with the dust discharging pipe 140, and the dust collected in the V-shaped groove 131 can be discharged out of the flue 100 through the dust discharging pipe 140. Illustratively, each ash discharge hole 132 is respectively communicated with a first vertical section 141 of the ash discharge pipe 140, the lower end of the first vertical section 141 is communicated with a discharge pipe section 142, and the discharge pipe section 142 is arranged in a downward inclined manner, and the tail end of the discharge pipe section 142 extends to the outside of the flue 100. The discharge duct section 142 is provided with an on-off valve 143 to periodically or aperiodically discharge the dust out of the flue 100. The end of the discharge pipe section 142 may be bent downward, and the on-off valve 143 is provided on the bent section, as shown in fig. 1; the discharge pipe section 142 may not be bent, and the on-off valve 143 is provided at the end (lower end) of the discharge pipe section 142. Illustratively, the first vertical segments 141 in the same row may share one discharge pipe segment 142. The specific form of the ash discharge pipe 140 may be designed according to actual needs, and the invention is not limited thereto.
Referring to fig. 4 to 6, a static mixer according to an embodiment of the present invention is disposed in a flue 200, and includes a plurality of flow guide assemblies 220 distributed in the flue, each flow guide assembly 220 includes an air inlet pipe 221 extending along an axial direction of the flue, and the air inlet pipe 221 is externally sleeved with an outer pipe 222. The outer tube 222 is a tubular structure with a thin lower part and a thick upper part, the lower end of the outer tube 222 is connected with the outer wall of the air inlet pipe 221, and the upper end of the outer tube 222 is higher than the air inlet pipe 221. A top plate 223 is arranged above the outer pipe 222, an air outlet channel 224 is obliquely and downwardly extended from the periphery of the top end of the outer pipe 222, and a dust exhaust hole 225 is formed at the joint of the lower end of the outer pipe 222 and the air inlet pipe 221 and used for discharging dust out of the flow guide assembly 220. The ash collection layer 230 is connected with the inner wall of the flue 200 in a sealing way, and an ash collection groove is formed between the flow guide assemblies 220. Illustratively, the dirt collection groove may be an arc-shaped groove 231. After the flue gas enters the outer pipe 222 from the gas inlet pipe 221, the flow rate is reduced, dust particles with larger particle sizes in the flue gas sink to the joint of the lower end of the outer pipe 222 and the gas inlet pipe 221 under the action of self gravity, and are discharged through the dust discharge holes 225, so that the first separation of the dust and the flue gas is realized; the flue gas after the first dust removal changes the flow direction through the air outlet channel 224 and leaves the flow guide assembly 220, the flow direction of the flue gas changes to be inclined downwards, two streams of flue gas of the adjacent flow guide assemblies 220 collide with each other, dust in the flue gas falls into the dust collection layer 230, and the second separation of the dust and the flue gas is realized.
Further, in one or more exemplary embodiments of the present invention, the dust exhaust hole 225 communicates with the dust exhaust pipe 2251 inclined downward. For example, the outlet of the dust exhaust pipe 2251 may be provided with a first cover 2252, and the first cover 2252 may close or open the dust exhaust pipe 2251 to drop the dust exhaust guide assembly 220 into the arc groove 231. The nozzle of the dust exhaust pipe 2251 may be wedge-shaped, and the first cover plate 2252 covers the nozzle to close the dust exhaust pipe 2251; when the pressure of the dust accumulated in the dust exhaust pipe 2251 on the first cover 2252 exceeds the gravity of the first cover 2252, the first cover 2252 is lifted to open the dust exhaust pipe 2251 to exhaust the dust; when the amount of dust in the dust exhaust pipe 2251 is reduced, the first cover 2252 will automatically close under the action of its own weight, thereby sealing the dust exhaust pipe and preventing the leakage of the flue gas through the dust exhaust hole 225.
Further, in one or more exemplary embodiments of the present invention, the air outlet passage 224 is enclosed by an upper wing 2241 and a lower wing 2242, the upper wing 2241 is connected to the top plate 223, and the lower wing 2242 is connected to the top end of the outer tube 222. Illustratively, the upper and lower wing panels 2241 and 2242 are disposed in parallel and correspond to each other. The flue gas flowing through the guide assembly 220 adjacent to the inner wall of the flue 200 may collide with the inner wall of the flue 200, the dust falls on the dust collecting layer 230, and an arc-shaped groove 231 may be formed between the inner wall of the flue 200 and the guide assembly 220 to collect the dust, which is not limited by the present invention. Illustratively, the outer tube 222 is circular in cross-section, and the top plate 223 is shaped to match the top end of the outer tube 222 to block dust falling above from entering the outer tube 222. Illustratively, the top plate 223 may have an inverted conical shape, the center line of which coincides with the center line of the air inlet pipe 221. Illustratively, the air inlet pipe 221 is a reducing tubular structure with a thick lower part and a thin upper part. Illustratively, the flow area between the top plate 223 and the upper end surface of the inlet pipe 221 is larger than the cross-sectional area of the lower end surface of the inlet pipe 221; the flow area of the flue gas between the upper wing 2241 and the lower wing 2242 is smaller than the flow area between the top plate 223 and the upper end surface of the intake pipe 221. The gas inlet pipe 221 is a reducer pipe with a thick lower part and a thin upper part, the flow area of the flue gas is reduced, the flow speed is increased, dust in the flue gas collides and coalesces in the process, and the particle size of dust particles is increased; the flue gas enters the outer pipe 222 through the gas inlet pipe 221, the flow area of the flue gas is increased, the flow speed of the flue gas is reduced, the retention time of the flue gas in the outer pipe 222 is increased, dust is settled under the action of self gravity, the outer pipe 222 is of a tubular structure with a thin lower part and a thick upper part, and the dust falling onto the inner wall of the outer pipe 222 can slide down along the inner wall of the outer pipe 222 under the action of self gravity and is discharged through the dust discharge hole 225; because the top plate 223 is in an inverted cone shape, when the flue gas impacts the top plate 223, the flue gas moves towards a position far away from the center of the top plate 223 under the action of the airflow and the inclined structure of the top plate 223, so that the dust is prevented from falling into the air inlet pipe 221 again to form secondary entrainment; when the flue gas turns to and gets into air outlet channel 224, because air outlet channel 224's flue gas flow area is less than the flow area between roof 223 and the intake pipe 221 up end, therefore the flue gas velocity of flow increases once more, and the dust in the flue gas collides and gathers at this in-process, and the particle size of dust particle increases, is favorable to subsequent collision desorption. The flue gas flows through the diversion component 220 of the static mixer, the flow velocity is increased and then reduced, in the process, dust in the flue gas collides and gathers, the particle size is increased, and the high-efficiency removal of the dust is facilitated.
Further, in one or more exemplary embodiments of the present invention, a plurality of dust discharge holes 232 are formed on the dust collection layer 230, and the dust discharge holes 232 are disposed at the bottom of the arc-shaped groove 231. The plurality of dust discharge holes 232 may have the same size, may also have different sizes, may be uniformly distributed, and may also be distributed according to different areas. The dust discharging hole 232 is communicated with the dust discharging pipe 240, and the dust collected in the arc groove 231 can be discharged out of the flue 200 through the dust discharging pipe 240. Illustratively, the side wall of the outer tube 222 is provided with a wind guard 2311, and the wind guard 2311 is inclined toward the bottom of the arc groove 231. The wind shield 2311 blocks most of smoke above the arc-shaped groove 231, so that a large amount of smoke is prevented from entering the arc-shaped groove 231 to blow up dust, and even if a small amount of smoke entering the arc-shaped groove 231 can blow up dust, most of the blown-up dust can fall into the arc-shaped groove 231 again under the action of the wind shield 2311, and secondary entrainment of the dust is effectively avoided; the wind shield 2311 is inclined towards the bottom of the arc-shaped groove 231, so that dust falling on the wind shield 2311 can also slide into the arc-shaped groove 231; the gap between the two wind shields 2311 and the dust collection groove structure can effectively buffer thermal expansion caused by over-high local temperature, and local deformation is avoided.
Illustratively, each ash discharge hole 232 is respectively communicated with a first vertical section 241 of the ash discharge pipe 240, the lower end of the first vertical section 241 is communicated with a discharge pipe section 242, the discharge pipe section 242 is arranged in a downward inclined manner, and the tail end of the discharge pipe section 242 extends to the outside of the flue 200. Illustratively, the end of the discharge duct segment 242 may be provided with a second cover plate 243, the second cover plate 243 being capable of closing or opening the discharge duct segment 242 to periodically or aperiodically discharge the dust out of the flue 200. The end of the discharge pipe section 242 may be wedge-shaped, and a second cover plate 243 covers the wedge-shaped surface to close the discharge pipe section 242; when the pressure of the dust accumulated in the discharge pipe section 242 reaches a certain height and exceeds the gravity of the second cover plate 243, the second cover plate 243 is automatically lifted so as to open the discharge pipe section 242 to discharge the dust, and the dust discharging process realizes unmanned operation; when the amount of dust in the discharge pipe section 242 is reduced, the second cover plate 243 is automatically closed under the action of self gravity, so that the leakage of smoke is avoided. Illustratively, the end of the discharge pipe segment 242 may be bent downward, with a second cover plate 243 being provided at the final outlet, as shown in fig. 4; the discharge pipe section 242 may not be bent, and a second cover plate 243 is provided at the end (lower end) of the discharge pipe section 242. Illustratively, the first vertical segments 241 in the same row may share a discharge pipe segment 242. The specific form of the ash discharge pipe 240 may be designed according to practical needs, and the invention is not limited thereto.
As shown in connection with FIG. 7, a static mixer according to one or more embodiments of the present invention is two-layered. Illustratively, the upper layer adopts a static mixer structure as shown in fig. 1, and the lower layer adopts a static mixer structure as shown in fig. 4, and the exemplary structures can be known by combining the descriptions of the corresponding figures and are not described again. The ends of the discharge pipe sections of the two-layer static mixer are connected through a second vertical section 344, and dust is discharged from the second vertical section 344. Illustratively, a second cover 345 may be disposed at an end of the second vertical section 344, and the second cover 345 may automatically close or open the second vertical section 344 to discharge the dust out of the flue 300. It should be appreciated that the end of second vertical section 344 may also be provided with a shutoff valve (not shown) to periodically or non-periodically discharge dust out of flue 300. It should be understood that the number of the static mixers can be set according to the structure of the flue and the actual requirement, for example, 1 to 5 layers, and the invention is not limited thereto.
Referring to fig. 8 to 10, a flue gas denitration ammonia injection mixing system according to one or more embodiments of the present invention sequentially includes, in a flue gas flowing direction: a plurality of ammonia gas nozzles 450; and a static mixer according to any of the above embodiments, wherein a plurality of flow guide assemblies 420 are disposed corresponding to the ammonia gas nozzle 450. The static mixer has the functions of dust removal and dust isolation, the guide assembly 420 of the static mixer can enable smoke to collide, dust in the smoke falls after collision, and the smoke flows upwards. The dust collecting layer 430 can catch dust falling after smoke collision, and can also block large dust falling above the flue 400, so that the dust is prevented from falling onto the ammonia nozzle 450 to block the ammonia nozzle. The dust collected on the dust collection layer 430 is discharged out of the flue 400 by the dust discharge duct 440. Illustratively, each flow guide assembly 420 corresponds to the same number of ammonia gas nozzles 450, for example, each flow guide assembly 420 corresponds to four ammonia gas nozzles 450, and the invention is not limited thereto.
Further, in one or more exemplary embodiments of the invention, the flue 400 upstream of the static mixer is divided into a plurality of first ammonia injection zones 411, each of the first ammonia injection zones 411 corresponds to one or more diversion assemblies 420, the ammonia gas nozzle 450 in each of the first ammonia injection zones 411 is connected with an ammonia injection mother pipe 451, and the ammonia injection mother pipes of the plurality of first ammonia injection zones 411The pipe 451 is connected with an ammonia injection main pipe 452, the ammonia injection main pipe 451 is provided with a first flow regulating valve 4511, and the ammonia injection main pipe 452 is provided with a second flow regulating valve 4521; the flue 400 downstream of the static mixer is divided into a plurality of second ammonia injection zones 412, each second ammonia injection zone 412 corresponds to one or more first ammonia injection zones 411, and each second ammonia injection zone 412 is provided with a flue gas detector 460. Illustratively, the flue 400 is divided into four first ammonia injection zones 411 (shown in fig. 9) and four second ammonia injection zones 412 (shown in fig. 10), the second ammonia injection zones 412 are in one-to-one correspondence with the first ammonia injection zones 411, and each first ammonia injection zone 411 corresponds to two flow guide assemblies 420. The eight ammonia nozzles 450 in each first ammonia injection zone 411 are connected with an ammonia injection header 451, and the four ammonia injection header 451 is connected with an ammonia injection header 452. The ammonia injection main pipe 451 is provided with a first ammonia gas flowmeter 4511, and the ammonia injection main pipe 452 is provided with a second ammonia gas flowmeter 4521. Illustratively, the flue gas detector 460 is capable of monitoring NO in the second ammonia injection zone 412 in real timexConcentration and ammonia concentration, etc.
Further, in one or more exemplary embodiments of the present invention, an ammonia-air mixer 471 is disposed on the ammonia injection mother pipe 451, and the ammonia-air mixer 471 is connected to the dilution air line 470, so that the ammonia gas is injected into the flue 400 through the ammonia gas nozzle 450 after being reduced to below the explosion limit thereof.
Referring to fig. 8 to 10, an ammonia injection control method according to one or more embodiments of the present invention is applied to a flue gas denitration ammonia injection mixing system according to any one of the above technical solutions, and the ammonia injection control method at least includes the following steps: dividing the flue 400 at the upstream of the static mixer into a plurality of first ammonia injection partitions 411, wherein the first ammonia injection partitions 411 are arranged corresponding to the guide flow components 420 of the static mixer; dividing the flue 400 downstream of the static mixer into a plurality of second ammonia injection zones 412, each second ammonia injection zone 412 corresponding to one or more first ammonia injection zones 411; capturing NO from multiple second ammonia injection zones 412xThe average concentration, the average ammonia nitrogen molar ratio, and the ammonia nitrogen molar ratio of each second ammonia injection partition 412; according to NOxCalculating the total flow of the ammonia injection required by the concentration average value and the flue gas flow of the flue; the actual total flow of ammonia injection is regulatedTo the total flow of the ammonia spraying; and adjusting the ammonia injection flow rate of each first ammonia injection subarea 411 to enable the ammonia nitrogen molar ratio of each second ammonia injection subarea 412 to be equal to the average ammonia nitrogen molar ratio.
The present invention will be described in more detail by way of specific examples, which should be construed as being illustrative only and not limiting.
Example 1
Referring to fig. 1 to 3, the static mixer of the present embodiment is a single-layer mixer, and includes eight flow guiding assemblies 120, wherein the flow guiding assemblies 120 are composed of an air inlet pipe 121, an outer pipe 122, a top plate 123, four upper wing plates 1241 and four lower wing plates 1242. The air inlet pipe 121 is a straight pipe, the cross section of the outer pipe 122 is rectangular, and the upper wing plate 1241 and the lower wing plate 1242 are trapezoidal. The dust exhaust hole 125 is communicated with an upward inclined dust exhaust pipe 1251, and the lower end surface of the outlet of the dust exhaust pipe 1251 is higher than the upper end surface of the dust exhaust hole 125. The dust collecting groove is a V-shaped groove 131. In the dust discharging pipe 140, three rows of first vertical sections 141 are respectively communicated with three discharging pipe sections 142 to discharge dust. An on-off valve 143 is provided for periodic ash discharge.
The static mixer of this example was used for flue gas from a coal-fired boiler, and the particulate (dust) content before the static mixer was 1530mg/Nm in the flow direction of the flue gas3The particulate (dust) content after the static mixer was 528mg/Nm3The dust removal efficiency was 65.5%.
Example 2
Referring to fig. 4 to 6, the static mixer of the present embodiment is a single-layer mixer, and includes thirty-two flow guiding assemblies 220, wherein the flow guiding assemblies 220 are composed of an air inlet pipe 221, an outer pipe 222, a top plate 223, an upper wing plate 2241, and a lower wing plate 2242. The air inlet pipe 221 is a reducing circular pipe with a thick lower part and a thin upper part, the cross section of the outer pipe 222 is circular, the top plate 223 is in an inverted cone shape, and the upper wing plate 2241 and the lower wing plate 2242 are in a circular truncated cone shape. The dust exhaust hole 225 communicates with a downward inclined dust exhaust pipe 2251, and an outlet of the dust exhaust pipe 2251 is provided with a first cover 2252. The dust collecting groove is an arc-shaped groove 231, the notch is provided with a wind shield 2311, one end of the wind shield 2311 is connected with the outer pipe 222, the other end of the wind shield 2311 is inclined downwards and extends, and a gap is reserved between the wind shields 2311 on two sides of the notch so that dust can fall into the arc-shaped groove 231. In the ash discharge pipeline 240, five rows of first vertical sections 241 are respectively communicated with five discharge pipe sections 242 to discharge dust, and the discharge pipe sections 242 are provided with cover plates 243 for automatically discharging ash.
The static mixer of this example was used for flue gas from a coal-fired boiler, and the particulate (dust) content before the static mixer was 1728mg/Nm in the flow direction of the flue gas3The particulate matter (dust) content after the static mixer was 586mg/Nm3The dust removal efficiency was 66.1%.
Example 3
Referring to fig. 7, the static mixer of the present embodiment is two-layered, wherein the structure of the static mixer of the lower layer is the same as that of embodiment 2; the structure of the static mixer on the upper layer is basically the same as that of the static mixer in the embodiment 1, and only the ash discharge pipeline in the embodiment 1 is changed into a first vertical section with five rows from a first vertical section with three rows, and five discharge pipeline sections are respectively communicated. The opposite discharge pipes of the upper layer and the lower layer are respectively communicated with five second vertical sections 344 to discharge dust, and the second vertical sections 344 are provided with second cover plates 345 for automatically discharging dust.
The double-layer static mixer of the embodiment is adopted for the smoke of a certain coal-fired boiler, and the content of particulate matters (dust) in front of the static mixer is 2272mg/Nm along the flow direction of the smoke3The content of particulate matter (dust) after the static mixer was 597mg/Nm3The dust removal efficiency was 73.7%.
The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. Any simple modifications, equivalent changes and modifications made to the above exemplary embodiments shall fall within the scope of the present invention.

Claims (23)

1. A static mixer disposed in a flue, the static mixer comprising:
a plurality of flow guide assemblies distributed in the flue, each flow guide assembly comprising:
an inlet duct extending in an axial direction of the flue;
the outer pipe is of a tubular structure with a thin lower part and a thick upper part, the lower end of the outer pipe is connected with the outer wall of the air inlet pipe, and the upper end of the outer pipe is higher than the air inlet pipe;
a top plate disposed above the outer tube;
an air outlet channel extending obliquely downward from the top end periphery of the outer tube; and
the dust exhaust hole is arranged at the lower end of the outer pipe; and
and the ash collecting layer is connected with the inner wall of the flue in a sealing manner, and an ash collecting groove is formed between the flow guide assemblies.
2. The static mixer of claim 1, wherein said inlet tube is of a tubular configuration having a lower diameter and an upper diameter.
3. The static mixer of claim 1, wherein the dust exhaust hole communicates with a dust exhaust pipe, the dust exhaust pipe is inclined upward, and a lower end surface of an outlet of the dust exhaust pipe is higher than an upper end surface of the dust exhaust hole.
4. The static mixer of claim 1, wherein the dust exhaust hole is communicated with a dust exhaust pipe, the dust exhaust pipe is inclined downwards, and an outlet of the dust exhaust pipe is provided with a first cover plate which can close or open the dust exhaust pipe.
5. The static mixer of claim 4, wherein the nozzle of the dust exhaust pipe is wedge-shaped, and the first cover plate covers the nozzle to close the dust exhaust pipe; when the pressure of dust accumulated in the dust exhaust pipe on the first cover plate exceeds the gravity of the first cover plate, the first cover plate is lifted so as to open the dust exhaust pipe.
6. The static mixer of claim 1, wherein the outlet channel is enclosed by an upper wing and a lower wing, the upper wing being connected to the top plate and the lower wing being connected to the top end of the outer tube.
7. The static mixer of claim 1, wherein the top plate is circular, rectangular, regular polygonal, inverted conical, or inverted pyramidal.
8. The static mixer of claim 1, wherein the outer tube has wind deflectors on its side walls, the wind deflectors being inclined toward the bottom of the dust collection trough.
9. The static mixer of claim 1, wherein the ash chute is a V-groove or an arcuate groove.
10. The static mixer of claim 1, further comprising:
and the ash discharge pipeline is used for discharging the dust in the ash collection groove out of the flue.
11. The static mixer of claim 10, wherein a plurality of ash discharge holes are formed in the ash collection layer, the ash discharge holes are formed in the bottom of the ash collection groove, and the ash discharge holes are communicated with the ash discharge pipeline.
12. The static mixer of claim 11, wherein the ash discharge conduit comprises:
a plurality of first vertical sections which are respectively communicated with the plurality of ash discharge holes; and
and the discharge pipe section is communicated with the lower end of the first vertical section, the discharge pipe section is arranged in a downward inclined mode, and the tail end of the discharge pipe section extends to the outside of the flue.
13. The static mixer of claim 12, wherein said discharge pipe section is provided with an on-off valve.
14. The static mixer of claim 12, wherein the end of the discharge pipe section is provided with a second cover plate, which can close or open the discharge pipe section.
15. The static mixer of claim 14, wherein the discharge tube segment terminates in a wedge shape, said second cover flap covering said end to close said discharge tube segment; when the pressure of the dust accumulated in the discharge pipe section on the second cover plate exceeds the gravity of the second cover plate, the second cover plate is lifted so as to open the discharge pipe section.
16. The static mixer of claim 12, wherein said first vertical segments in the same row share one said discharge tube segment.
17. The static mixer of claim 12, wherein when the static mixer is multi-layered, ends of the discharge pipe sections corresponding to the upper and lower sides are communicated through the second vertical section, and the dust is discharged from the second vertical section.
18. The utility model provides a flue gas denitration spouts ammonia hybrid system which characterized in that includes in proper order along flue gas flow direction:
a plurality of ammonia gas nozzles; and
the static mixer of any one of claims 1-17, wherein the plurality of flow guide assemblies are disposed in correspondence with the ammonia gas nozzle.
19. The flue gas denitration ammonia injection hybrid system of claim 18, wherein each flow guide assembly corresponds to the same number of ammonia gas nozzles.
20. The flue gas denitration ammonia-injection hybrid system of claim 19, wherein a flue upstream of the static mixer is divided into a plurality of first ammonia-injection zones, each first ammonia-injection zone corresponds to one or more diversion assemblies, an ammonia gas nozzle in each first ammonia-injection zone is connected with an ammonia-injection main pipe, the ammonia-injection main pipes of the plurality of first ammonia-injection zones are connected with an ammonia-injection main pipe, the ammonia-injection main pipe is provided with a first flow regulating valve, and the ammonia-injection main pipe is provided with a second flow regulating valve; and a flue at the downstream of the static mixer is divided into a plurality of second ammonia spraying subareas, each second ammonia spraying subarea corresponds to one or more first ammonia spraying subareas, and each second ammonia spraying subarea is provided with a flue gas detector.
21. The flue gas denitration ammonia injection mixing system of claim 20, wherein the flue gas detector monitors NO of the second ammonia injection zone in real timexConcentration and ammonia concentration.
22. The flue gas denitration ammonia injection hybrid system of claim 20, wherein the ammonia injection main pipe is provided with a first ammonia gas flowmeter, and the ammonia injection main pipe is provided with a second ammonia gas flowmeter.
23. An ammonia injection control method for the flue gas denitration ammonia injection mixing system of claim 18, the ammonia injection control method at least comprising the following steps:
dividing a flue at the upstream of the static mixer into a plurality of first ammonia injection zones, wherein the first ammonia injection zones are arranged corresponding to the flow guide assemblies of the static mixer;
dividing a flue at the downstream of the static mixer into a plurality of second ammonia injection zones, wherein each second ammonia injection zone corresponds to one or more first ammonia injection zones;
obtaining NO of the plurality of second ammonia injection zonesxThe average concentration value, the average ammonia nitrogen molar ratio and the ammonia nitrogen molar ratio of each second ammonia spraying subarea;
according to said NOxCalculating the total flow of the ammonia injection required by the concentration average value and the flue gas flow;
adjusting the actual total flow of ammonia injection to the required total flow of ammonia injection; and
and adjusting the ammonia injection flow of each first ammonia injection partition so that the ammonia nitrogen molar ratio of each second ammonia injection partition is equal to the average ammonia nitrogen molar ratio.
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CN116036853A (en) * 2021-10-28 2023-05-02 中国石油化工股份有限公司 Flue gas denitration ammonia spraying mixed dust removal equipment and system
CN114682088A (en) * 2022-04-02 2022-07-01 大唐林州热电有限责任公司 Ejector applied to matrix nozzle
CN114682088B (en) * 2022-04-02 2023-08-08 大唐林州热电有限责任公司 Injector applied to matrix nozzle

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