CN209865734U - Sintering flue gas circulation is united ozone preoxidation's SOx/NOx control system - Google Patents
Sintering flue gas circulation is united ozone preoxidation's SOx/NOx control system Download PDFInfo
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Abstract
The utility model provides a sintering flue gas circulation unites SOx/NOx control system of ozone preoxidation, the system includes: the device comprises an ozone preparation device, a denitration device and a denitration device, wherein the ozone is used for carrying out primary ozone pre-oxidation treatment on the flue gas before desulfurization reaction in a main flue of the sintering machine and carrying out secondary ozone pre-oxidation treatment on the flue gas before denitration reaction; the desulfurization reaction device is used for performing desulfurization treatment and first denitration treatment on the flue gas; the denitration reaction device is used for carrying out denitration treatment on the flue gas for the second time; the sintering flue gas circulating device can supply oxygen to high-temperature flue gas and then recycle the high-temperature flue gas; the utility model discloses a SOx/NOx control system can improve the flue gas circulation rate to more than 30%, improves denitration reaction rate, reduces catalyst quantity and increase of service life, makes NOx discharge and reaches and surpasss the flue gas ultralow emission even.
Description
Technical Field
The utility model belongs to the technical field of steel industry flue gas desulfurization denitration and waste heat utilization, concretely relates to sintering flue gas circulation unites ozone pre-oxidation's SOx/NOx control system.
Background
The iron and steel industry belongs to the high pollution industry, a large amount of flue gas is generated in the iron ore sintering process, and in addition, the air leakage rate of a domestic sintering machine is up to more than 40%, a considerable part of air directly enters a subsequent flue gas treatment device without passing through a sinter bed, so the sintering flue gas amount is very large. Such as a 360m stand2When the sintering machine is normally produced, the discharged flue gas amount is up to more than 216 ten thousand cubic meters per hour. Besides large amount of sintering flue gas, the method also has the advantages of concentrated emission source, large flue gas temperature fluctuation (changed along with the condition of the sintering process), much carried dust, higher CO content and SO2The concentration is lower, the moisture content is large, corrosive gas and dioxin substances are contained, and the like, so that the influence on the local atmospheric quality is large, and serious environmental pollution can be caused, and therefore, the sintering flue gas pollutants need to be purified, and the effects of environmental protection and emission reduction are achieved.
At present, the atmospheric pollutant treatment measures of steel enterprises in China can be roughly summarized into three categories: 1. basic conditions of raw material control and flue gas emission reduction; 2. an effective means of controlling the sintering process and reducing the emission of flue gas; 3. the final means and the final guarantee of the flue gas treatment. Among the three treatment measures, people often pay more attention to the tail end treatment of the flue gas. At present, the tail end treatment of sintering flue gas mainly comprises active coke desulfurization and denitration integration, flue gas desulfurization (wet method, dry method and semi-dry method), medium-low temperature SCR denitration integration and other technologies. SCR (Selective Catalytic Reduction) is a Selective Catalytic Reduction technology, wherein the denitration principle of the medium-low temperature SCR technology is as follows: under the action of a catalyst, spraying reducing agent ammonia into the flue gas with the temperature of about 220-280 ℃ to reduce NOx into N2And H2O。
The integrated technology of desulfurization and denitrification of active coke mainly has the defects of huge investment, large loss of the active coke, high operation cost, complex process, reduced pressure of flue gas passing through an adsorption bed, increased energy consumption, pipeline blockage in the ammonia injection process, low desulfurization rate and the like.
The integrated technology of flue gas desulfurization and medium-low temperature SCR denitration also has a plurality of defects: 1) the temperature window exists, the reaction temperature is above 220 ℃, and when the temperature is lower than the temperature, SO in the flue gas2Will react with NH3Ammonia sulfate and ammonium bisulfate which are easy to corrode and block equipment are generated by reaction, and simultaneously, the ammonia sulfate and the ammonium bisulfate can be adhered to the surface of the catalyst, so that the catalyst is blocked, sulfur poisoning and the like, and the utilization rate of ammonia is reduced; 2) the catalyst consumption is large, the service life is short, and the investment cost is high; 3) the waste catalyst is used as solid hazardous waste, and has high treatment cost and great difficulty; 4) the flue gas quantity is large, so that the fuel consumption required by the temperature rise of the flue gas is large; 5) the denitration efficiency is close to the limit value.
With the continuous departure of national and local standards such as the modification of the atmospheric pollutant emission standards of the steel sintering and pelletizing industry (GB 28662 and 2012), the emission limit of flue gas pollutants in the steel industry is becoming lower and lower, and the end desulfurization/denitration treatment technology can only reach the emission limit by increasing the scale of the device and increasing the amount of materials such as absorbents and catalysts, but at the same time, a series of problems such as increase in investment and operation pressure of enterprises and increase in ammonia escape occur.
Therefore, it is necessary to provide an improved technical solution not only limited to the flue gas end treatment, but also focused on the whole flow treatment of the sintering flue gas.
SUMMERY OF THE UTILITY MODEL
The utility model aims to provide a sintering flue gas circulation and ozone preoxidation combined desulfurization and denitrification system, which at least solves the problems of large catalyst consumption and short service life in the current flue gas desulfurization and denitrification process; the flue gas treatment capacity is large, so that a large amount of fuel is consumed for heating the flue gas, and the investment and running cost of the desulfurization and denitrification device are increased; in addition, the denitration effect is difficult to reach the ultralow emission standard.
In order to achieve the above object, the present invention provides the following technical solutions:
a desulfurization and denitrification system combining sintering flue gas circulation and ozone pre-oxidation, comprising: the desulfurization reaction device and the denitration reaction device of setting on sintering machine flue and ozone preparation facilities, wherein:
the ozone preparation device is used for preparing ozone, and the ozone is used for carrying out primary ozone pre-oxidation treatment on the flue gas in the main flue of the sintering machine before entering the desulfurization reaction device and carrying out secondary ozone pre-oxidation treatment on the flue gas in the main flue of the sintering machine before entering the denitrification reaction device;
the flue gas subjected to the first ozone pre-oxidation enters the desulfurization reaction device, and the desulfurization reaction device is used for performing desulfurization treatment and first denitration treatment on the flue gas;
and the flue gas from the desulfurization reaction device enters the denitration reaction device after being subjected to secondary ozone pre-oxidation, and the denitration reaction device is used for carrying out secondary denitration treatment on the flue gas.
In the desulfurization and denitrification system combining sintering flue gas circulation and ozone pre-oxidation, preferably, the system further comprises a sintering flue gas circulation device, the sintering flue gas circulation device comprises a circulation flue, and the circulation flue and the sintering equipment form a loop;
one end of the circulating flue is communicated with an air box of the sintering machine, and the other end of the circulating flue is communicated with the charge level of the sintering machine; more preferably, one end of the circulating flue is communicated with the middle front section and the rear section of the air bellow of the sintering machine;
the sintering flue gas circulating device is sequentially provided with a first dust remover, a first fan and an oxygen supply device along the flow direction of flue gas in the circulating flue; the oxygen supply device is used for supplying oxygen to the flue gas in the circulating flue; preferably, the first dust collector is a multi-cyclone dust collector.
In the above desulfurization and denitrification system combining sintering flue gas circulation and ozone pre-oxidation, preferably, the oxygen supply device comprises an oxygen distributor connected to an outlet of the oxygen buffer tank, and oxygen ejected from the oxygen distributor enters the circulation flue.
In the above desulfurization and denitrification system combining sintering flue gas circulation and ozone pre-oxidation, preferably, the sintering flue gas circulation device further comprises a plurality of sealing hoods, flue gas supplemented with oxygen enters the plurality of sealing hoods through a plurality of branch pipelines respectively, the sealing hoods are communicated with the charge level of the sintering machine, and the plurality of branch pipelines are provided with flue gas regulating valves for regulating the flue gas entering the sealing hoods;
the sealing cover is fixed above the material level of the middle section of the sintering machine, one end of the main flue of the sintering machine is at least connected with the machine head and the middle section air box of the sintering machine, and the flue gas in the circulating flue enters the middle section of the sintering machine from the sealing cover and enters the main flue of the sintering machine from the middle section air box;
the sealed cover is provided with a pressure gauge and an oxygen concentration analyzer, the oxygen concentration analyzer is connected with the oxygen supply device, and the oxygen supply process is automatically controlled according to the oxygen concentration in the sealed cover.
In the desulfurization and denitrification system combining sintering flue gas circulation and ozone pre-oxidation, preferably, the ozone prepared by the ozone preparation device is diluted and mixed with air;
the ozone is transmitted through a first pipeline and is injected into a main flue of the sintering machine through a first ozone uniform distributor to carry out primary ozone pre-oxidation treatment; the ozone is transmitted through a second pipeline and is injected into the main flue of the sintering machine through a second ozone uniform distributor to carry out secondary ozone pre-oxidation treatment;
the first ozone uniform distributor is arranged at a first ozone spraying part of the main flue of the sintering machine; and the second ozone uniform distributor is arranged at a second ozone spraying part of the main flue of the sintering machine.
In the desulfurization and denitrification system combining sintering flue gas circulation and ozone pre-oxidation, preferably, a second dust remover is further arranged on the main flue of the sintering machine, the second dust remover is preferably a machine head electric dust remover, and the machine head electric dust remover is arranged in front of the first ozone injection part;
a first NOx concentration analyzer is arranged on the main flue of the sintering machine in front of the nose electric dust remover; a second NOx concentration analyzer is arranged on the sintering machine main flue behind the second ozone injection part; a third NOx concentration analyzer and O are arranged on the main flue of the sintering machine behind the denitration reaction device3A concentration analyzer.
In the desulfurization and denitrification system combining the sintering flue gas circulation and ozone pre-oxidation, it is preferable that the system further includes a control device at least connected to the first NOx concentration analyzer, the second NOx concentration analyzer, the third NOx concentration analyzer, and the O3The concentration analyzer, the first ozone injection part and the second ozone injection part are connected to analyze the concentration of the first NOx, the concentration of the second NOx, the concentration of the third NOx and the concentration of the O3The concentration analyzer data adjusts the amount of ozone in the first and second ozone injection portions.
In the above desulfurization and denitrification system combining flue gas circulation and ozone pre-oxidation, preferably, a heat recovery device is provided in the main flue of the sintering machine behind the denitrification reactor.
In the desulfurization and denitrification system combining sintering flue gas circulation and ozone pre-oxidation, preferably, the heat recovery device comprises a gas heat exchanger and a waste heat boiler which are sequentially arranged along the flue gas transmission direction; more preferably, the gas heat exchanger is communicated with the main flue of the sintering machine at the flue gas inlet of the denitration reaction device and communicated with the main flue of the sintering machine at the outlet of the denitration reaction device;
the desulfurization reaction device is a circulating fluidized bed desulfurization reactor; the denitration reaction device is an SCR reaction device.
In the above desulfurization and denitrification system combining sintering flue gas circulation and ozone pre-oxidation, preferably, a heating furnace and an ammonia injection system are sequentially arranged on the main flue of the sintering machine in front of the denitrification reaction device along the flue gas transmission direction.
Compared with the closest prior art, the utility model provides a technical scheme has following excellent effect:
1. the utility model adopts the sintering flue gas circulation process, and oxygen is supplemented in the flue gas circulation process, so that the sintering flue gas circulation rate is improved, the flue gas circulation rate is improved to more than 30 percent, and the total amount of discharged flue gas can be reduced to a greater extent; the quality and the yield of finished ore are improved under the condition of not modifying a sintering machine trolley; the operating cost of pollutant control facilities such as dust removal, desulfurization and the like which are put into operation is reduced; the investment and the operation cost of pollutant control facilities of the newly built sintering machine are reduced.
2. The utility model discloses an ozone preoxidation technology, be equipped with ozone injection point before desulfurization reaction unit, ozone is NO partial oxidation for NO in the flue gas before the desulfurization reaction2、N2O5The high-valence NOx is partially removed in the desulfurization reaction device, and the concentration of the NOx at the inlet of the denitrification reaction device is reduced; in addition, the flue gas before denitration reaction is also subjected to ozone preoxidation treatment to control NO/NO of the flue gas2The mol ratio realizes the rapid denitration reaction in the SCR reactor, improves the denitration reaction rate, reduces the catalyst dosage, prolongs the service life of the catalyst, and ensures that the NOx emission reaches or even exceeds the ultra-low emission target of the flue gas.
Drawings
The accompanying drawings, which form a part of the present application, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. Wherein:
FIG. 1 is a flow chart of a desulfurization and denitrification system combining sintering flue gas circulation with ozone pre-oxidation.
In the figure: 1. sintering machine; 2. a multi-cyclone dust collector; 3. a first fan; 4. an oxygen buffer tank; 5. an oxygen uniform distributor; 6. adjusting a valve; 7. an oxygen concentration analyzer; 8. a pressure gauge; 9. sealing cover(ii) a 10. A first NOx concentration analyzer; 11. a nose electric dust remover; 12. a first ozone sparger; 13. a desulfurization reaction device; 14. a gas mixer; 15. an ozone generating device; 16. a second ozone uniform distributor; 17. a second NOx concentration analyzer; 18. a gas heat exchanger; 19. heating furnace; 20. an ammonia injection system; 21. a denitration reaction device; 22. a waste heat boiler; 23. a second fan; 24. a third NOx concentration analyzer; 25. a third fan; 26. a chimney; 27. circulating the flue; 28. a main flue of the sintering machine; 29. a dilution fan; 30. a first conduit; 31. a second conduit; 32. o is3A concentration analyzer.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments. It should be noted that, in the present invention, the embodiments and features of the embodiments may be combined with each other without conflict.
In the description of the present invention, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description of the present invention and do not require that the present invention must be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention. The terms "connected" and "connected" used in the present invention should be understood in a broad sense, and may be, for example, either fixed or detachable; the connection may be direct connection, indirect connection through intermediate components, circuit connection, or communication connection, and a specific meaning of the above terms may be understood by those skilled in the art according to specific situations.
During the sintering process of the sintering machine 1, the heat of the flue gas of the sintering machine 1 is unevenly distributed, wherein the temperature of the flue gas of the head air box (i.e. the front section) of the sintering machine 1 is lower and is generally below 150 ℃, the temperature of the rear section in the air box of the sintering machine is gradually increased to about 300-450 ℃, the temperature of the flue gas of the tail of the sintering machine is higher, but the total heat of the flue gas of each air box of the sintering machine is conserved. Simultaneous burningFlue gas pollutant SO of knot-tying machine 12The concentrations of pollutants such as NOx, CO and the like present the situation that the flue gas of different windboxes has different emission characteristics.
If only the high-temperature flue gas of the air box at the rear section of the sintering machine 1 is introduced into the circulating flue 27, the temperature of the flue gas in the circulating flue 27 is very high and can reach about 300 ℃, which is beneficial to the circulating process of the sintering flue gas; however, due to the conservation of heat of the flue gas of the air box, the temperature of the flue gas in the main flue 28 of the sintering machine is inevitably lower than 120 ℃, and is reduced to be lower than the acid dew point, so that the flue is corroded, the electric dust remover 11 of the machine head cannot be normally used, and the fuel consumption of the heating furnace 19 is huge.
If only the low-temperature flue gas of the front segment air box in the sintering machine 1 is introduced into the circulating flue 27, the temperature of the flue gas in the circulating flue 27 is very low, which is expected to be below 100 ℃, so that the sintering flue gas circulating process is not facilitated, and the flue is corroded and the multi-pipe cyclone dust collector 2 and the first fan 3 cannot be normally used due to the fact that the flue gas is lower than an acid dew point; due to the conservation of the flue gas heat of the air box, the temperature of the flue gas in the main flue 28 of the sintering machine is inevitably too high and can reach more than 300 ℃, the flue gas volume and the power consumption of the first fan 3 are inevitably increased, and the fan and the motor can not meet the load requirement.
In conclusion, the low-temperature flue gas at the front section of the sintering machine and the high-temperature flue gas at the tail (i.e. the rear section) of the air box need to be matched and enter the circulating flue 27, the rest of the flue gas enters the main flue 28 of the sintering machine, the temperature of the mixed flue gas in the main flue 28 of the sintering machine is 140-160 ℃, and the mixed flue gas enters the subsequent flue gas purification system.
The utility model provides a "preceding" and "back" are based on the shown position relation of direction of flue gas transmission.
As shown in fig. 1, according to the embodiment of the utility model, a desulfurization and denitrification system of sintering flue gas circulation combined ozone pre-oxidation is provided, including:
sintering flue gas circulating device utilizes sintering flue gas circulating device, carries out waste heat circulation rational utilization to 1 wind box flue gas in the sintering machine, guarantees under the prerequisite that does not influence sintering production, the maximize utilizes sintering flue gas waste heat. The sintering flue gas circulating device comprises a circulating flue 27, the circulating flue 27 and the sintering machine 1 form a loop, one end of the loop is communicated with an air box of the sintering machine 1, and the other end of the loop is communicated with the charge level of the sintering machine 1; preferably, in order to ensure the normal operation of the whole system and ensure a high flue gas circulation rate, one end of the circulation flue 27 is communicated with the middle front segment and the rear segment of the air boxes of the sintering machine 1, the other air boxes are communicated with the main flue 28 of the sintering machine, an oxygen supply device is arranged on the circulation flue 27 and used for supplying oxygen to the circulation flue gas, the oxygen supply device comprises an oxygen buffer tank 4 and an oxygen distributor 5 connected to the outlet of the oxygen buffer tank 4, and oxygen ejected from the oxygen distributor 5 enters the circulation flue 27 to supply oxygen to the circulation flue gas. The oxygen uniform distributor 5 can ensure that the injection of the oxygen and the flue gas are mixed more uniformly. According to the difference of the flue gas emission characteristics of the air boxes of the sintering machine 1, on the premise of not influencing the quality of the sintering ore, selecting specific air box section flue gas to circulate back to the surface of the trolley of the sintering machine 1 through a circulating flue 27 for hot air sintering; in the embodiment of the present invention, under the condition of 23 total bellows, the flue gas in the bellows with the bellows numbers of 4# -8# and 20# -23# is selected to enter the circulating flue 27, and the flue gas in the other bellows enters the main flue 28 of the sintering machine.
The sintering flue gas circulating device also comprises a sealing cover 9, sintering circulating flue gas after oxygen supply enters the sealing covers 9 through a plurality of branch pipelines respectively, the flue gas in the sealing covers 9 is communicated with the sintering machine 1, the sealing covers 9 are fixed above the material level of the middle section of the sintering machine 1, so that the flue gas of the circulating flue enters the material level of the middle section of the sintering machine from the sealing cover 9 and then enters the middle section air box downwards, then enters the main flue 28 of the sintering machine connected with the middle segment air box, in the specific embodiment of the utility model, the fixed position of the sealing cover 9 is above the charge level layer corresponding to the air boxes 9# -19#, the circulating flue gas enters the sintering machine 1 through the sealing cover 9 and then is led out from the air boxes 9# -19# and enters the main flue 28 of the sintering machine, SO that the flue gas supplemented by oxygen can enter a subsequent flue gas purification system after being circulated once, and pollutants (SO) in the flue gas caused by repeated circulation of the flue gas can be avoided.2NOx, particulate matter). The plurality of branch pipelines are provided with flue gas regulating valves 6 for regulating flue gas entering the sealing cover 9; in the embodiment of the utility model, the circulating flue gas is led out by the 1 wind box of the sintering machine and then passes through the first air boxAfter the dust remover (preferably, the multi-cyclone dust remover 2) and the first fan 3 are divided into four paths, namely four branch pipelines, and the sealing cover 9 is introduced, of course, other number of branch pipelines can be arranged according to the smoke condition, and the utility model discloses do not limit this; the flue gas in the sealing cover 9 is sucked into the sinter bed under the negative pressure generated by the second fan 23, participates in the secondary sintering process, enters the main flue 28 of the sintering machine after sintering, and is discharged into the main flue 28 of the sintering machine to enter a subsequent flue gas purification system. Four flue gas regulating valves 6 are respectively arranged on the four branch pipelines, and the opening degree of the regulating valves 6 is regulated and controlled according to the air permeability and the air demand difference of material layers in different regions of the sintering machine 1, so that the flue gas pressure is kept stable in the sealing cover 9, the micro negative pressure state is maintained, the pressure is kept at-100 Pa-0 Pa, and the flue gas is prevented from leaking. In order to ensure real-time monitoring of the flue gas pressure, a pressure detection device pressure gauge 8 is arranged on each sealing cover 9.
Preferably, the seal cover 9 is provided with an oxygen concentration analyzer 7, the oxygen concentration analyzer 7 is connected with an oxygen supply device, the oxygen supply process is automatically controlled according to the oxygen concentration in the seal cover 9, and the oxygen supply amount is controlled and adjusted through a PID program; the oxygen content (oxygen concentration) of the flue gas in the sealing cover 9 after oxygen supply is ensured to be more than 18 percent, and when the oxygen content is reached, the sintering production is not influenced.
The conventional sintering flue gas circulating device can reduce the total amount of discharged flue gas by 20 percent; the utility model discloses in choose pure oxygen to carry out the oxygenating for use, compare conventional sintering gas recirculation, the outer row's of reducible more than 30% flue gas total amount can reduce gas cleaning system load to the bigger degree.
Flue gas in an air box of the sintering machine can flow to two directions, wherein one path is a circulating flue 27, and the other path is a main flue 28 of the sintering machine; one end of the circulating flue 27 is connected to part of the bellows at the front and rear stages of the sintering machine, respectively, and one end of the main flue 28 of the sintering machine is connected to all the bellows outlets of the sintering machine. In the embodiment of the present invention, for the air box connected to the circulation flue 27 and the sintering machine main flue 28 at the same time, a branch pipeline connected to the sintering machine main flue 28 may be provided on the main pipeline connecting a certain air box and the circulation flue, and the main pipeline and the branch pipeline are both provided with a flue gas flow control valve, so that under the condition of normal sintering circulation, flue gas in the front section air box and the rear section air box enters the circulation flue 27 to participate in primary circulation, and then the circulated flue gas enters the middle section air box and then enters the sintering machine main flue 28; under the condition of equipment maintenance or debugging, the flue gas in the front-section air box and the rear-section air box enters the main flue 28 of the sintering machine from the branch pipeline through the regulation and control of the flue gas flow regulation and control valve on the branch pipeline, and the flue gas in the sintering machine can flow to any path under the control of the flue gas flow regulation and control valve on the main pipeline and the branch pipeline.
Under the action of negative pressure of the charge level of the sintering machine, circulating flue gas above the charge level of the sintering machine is sucked into the charge level, and complex physical and chemical processes including secondary combustion heat release of CO, pyrolysis of dioxin and the like occur in a sintering material layer, so that all sensible heat of the flue gas is supplied to the sintering material while the total emission amount of pollutants is reduced, and the consumption of solid fuel in the sintering process is reduced; in addition, the high-temperature flue gas uniformly heats the sinter bed above the sinter bed, so that the quality of surface sinter can be improved, the temperature uniformity, the crushing strength and other physical and chemical indexes of the sinter bed are improved, and the multifunctional coupling of energy conservation, emission reduction and yield increase is realized.
The ozone preparation device is used for preparing ozone, and respectively performs primary ozone pre-oxidation treatment on the flue gas before desulfurization reaction and secondary ozone pre-oxidation treatment on the flue gas before denitration reaction; the ozone prepared by the ozone preparation device is diluted and mixed with air; the ozone preparation device comprises an ozone generation device 15, and the ozone generation device 15 is used for preparing high-purity ozone.
The specific process of ozone preparation is that oxygen enters the ozone generating device 15, and the prepared high-purity ozone and air sent by the dilution fan 29 are mixed in the gas mixer 14 to form ozone for standby. Preferably, the volume ratio of ozone to air is (7-9): 1 (e.g., 7:1, 7.2:1, 7.4:1, 7.6:1, 7.8:1, 8:1, 8.2:1, 8.5:1, 8.7: 1).
The high-purity ozone gas has strong oxidizability and corrosivity to metal materials, and the action of diluting ozone has two effects: firstly, the ozone concentration is reduced, and the influence on a metal flue is reduced to a certain extent; and secondly, the ozone is diluted by air, the volume of the mixed gas is increased, the ozone is favorably and uniformly mixed with the flue gas after being sprayed into the flue, and the chemical reaction of the ozone and NOx in the flue gas is favorably realized.
Preferably, ozone is transmitted through the first pipeline 30 and is injected into the main flue 28 of the sintering machine through the first ozone uniform distributor 12, and the flue gas before desulfurization reaction is subjected to primary ozone pre-oxidation treatment; the ozone is transmitted through the second pipeline 31 and is injected into the main flue 28 of the sintering machine through the second ozone uniform distributor 16, and the flue gas after the desulfurization reaction and before the denitration reaction is subjected to secondary ozone pre-oxidation treatment. The first ozone uniform distributor 12 is arranged at a first ozone spraying part of the main flue 28 of the sintering machine; the second ozone distributor 16 is arranged at the second ozone spraying part of the main flue 28 of the sintering machine, and is used for uniformly spraying ozone into the main flue 28 of the sintering machine, uniformly mixing with flue gas and fully reacting.
The main flue 28 of the sintering machine is also provided with a second dust remover which can be a dust remover commonly used in the field, the preferable dust removal effect reaches more than 99.5%, the second dust remover is preferably a nose electric dust remover 11, the nose electric dust remover 11 is arranged in front of the first ozone injection part, and the flue gas after dust removal is subjected to primary ozone pre-oxidation treatment. The first ozone pre-oxidation treatment is arranged to oxidize NO in the flue gas into NO partially before the flue gas enters the desulfurization reaction device 132、N2O5The high valence state NOx is partly got rid of in desulfurization reaction unit 13, reduces denitration reaction unit 21 entrance NOx concentration, alleviates denitration reaction unit 21's denitration pressure to flue gas NOx concentration after denitration reaction unit 21 handles can reach or even exceed flue gas minimum emission standard.
Preferably, a first NOx concentration analyzer 10 is arranged on the main flue 28 of the sintering machine in front of the electric dust remover 11 for monitoring NOx concentration data in raw flue gas.
Desulfurization reaction unit 13, the flue gas after ozone preoxidation for the first time gets into desulfurization reaction unit 13, carries out desulfurization treatment to the flue gas, the embodiment of the utility model provides an, desulfurization reaction unit 13 is circulating fluidized bed desulfurization reactor, because circulating fluidized bed desulfurization reactor device is simple, and no waste water produces in the operation process, consequently, is fit for very much as the reaction site of high valence state NOx in the flue gas. In other embodiments, of course, the desulfurization reaction device 13 may also be a dense-phase dry tower, a limestone-gypsum method, a magnesium method, or other wet or semi-dry desulfurization methods, which is not limited by the present invention; the circulating fluidized bed desulfurization device can remove a part of NOx, reduce the concentration of NOx at the inlet of the denitration reaction device 21, namely the SCR reaction device, and reduce the load of the denitration reaction device 21. A second fan 23 is arranged between the first ozone injection part and the desulfurization reaction device 13 and is used for introducing flue gas in the main flue of the sintering machine into the desulfurization reaction device 13.
During the first ozone pre-oxidation treatment, O is controlled3The molar ratio of NO is about 3:2, and N can be generated2O5Thereby facilitating the first denitration reaction in the desulfurization reaction device 13; n is a radical of2O5Is very easy to remove and is mostly absorbed in the desulfurization reaction device 13.
Ozone oxidation NO chemical reaction equation:
NO+O3→NO2+O2 (1)
2NO2+O3→N2O5+O2 (2)
the first denitration reaction equation in the desulfurization reaction device 13:
3NO2+H2O→2HNO3+NO
N2O5+H2O→2HNO3
NO2+NO+H2O→2HNO2
Ca(OH)2+2HNO3→Ca(NO3)2+2H2O
Ca(OH)2+2HNO2→Ca(NO2)2+2H2O
the denitration reaction device 21 is configured to pre-oxidize the flue gas subjected to the desulfurization reaction by ozone for the second time and then enter the denitration reaction device 21, the denitration reaction device 21 is configured to perform denitration treatment on the flue gas for the second time, and the flue gas is subjected to SCR reaction in the denitration reaction device 21. The heating furnace 19 and the ammonia injection system 20 are sequentially arranged on the main flue 28 of the sintering machine in front of the denitration reaction device 21 along the flow direction of the flue gas, and are used for heating and spraying ammonia on the flue gas to pretreat the flue gas before entering the denitration reaction device 21.
In the embodiment of the present invention, the second ozone spraying portion is provided in front of the heating furnace 19, and the ozone sprayed from the second ozone distributor 16 can control the NO/NO in the flue gas2Molar ratio, NO/NO2The molar ratio is preferably 0.95-1.05 (such as 0.96, 0.97, 0.98, 0.99, 1, 1.01, 1.02, 1.03 and 1.04), the flue gas reaching the ratio enters the denitration reaction device 21 to carry out rapid SCR reaction, and compared with the standard SCR reaction, the denitration reaction rate can be greatly improved; fast SCR reaction equation:
2NH3+2NO2→NH3NO3+N2+H2O；
NH3NO3+NO→NO2+N2+2H2O；
and (3) total reaction: 2NH3+NO2+NO→2N2+3H2O；
And a second NOx concentration analyzer 17 is arranged on the main flue 28 of the sintering machine behind the ammonia injection system 20 and is used for monitoring the concentration of NOx in the flue gas after the secondary ozone pre-oxidation.
When O is present3When the molar ratio of NO is about 1:1, the formula (1) is the main reaction, and the product is NO2(ii) a When O is present3When the molar ratio of NO is about 1:1 to 3:2, equations (1) and (2) occur simultaneously, and the product is NO2And N2O5(ii) a Due to N2O5Most of the NOx is absorbed in the desulfurizing tower, so that the NOx in the flue gas is mainly NO and NO after the desulfurizing reaction device 132By controlling O in the second ozonation3The molar ratio of NO is about 1:1, and N is generated as little as possible2O5NO in the flue gas before the second denitration treatment2The molar ratio is 0.95-1.05, which is beneficial to the rapid denitration reaction.
In order to fully save heat sources and reduce the gas consumption of the heating furnace 19, a primary heat recovery device gas heat exchanger 18 is arranged in front of the heating furnace 19 at the inlet of the denitration reaction device 21, the gas heat exchanger 18 is positioned on the main flue 28 of the sintering machine in front of and behind the denitration reaction device 21, and low-temperature flue gas before denitration reaction and high-temperature flue gas after denitration reaction are subjected to heat exchange. In addition, after the hot flue gas after denitration treatment passes through the gas heat exchanger 18, the temperature of the discharged flue gas is still about 200 ℃, so a secondary heat recovery device waste heat boiler 22 is further arranged on the main flue 28 of the sintering machine, the waste heat boiler 22 is used for heat exchange to generate steam or hot water, the temperature of the flue gas is reduced to below 170 ℃, and the flue gas is discharged from a chimney 26 through a third fan 25.
The flue gas discharged from the sintering machine 1 sequentially passes through a nose electric dust remover 11, a second fan 23, a desulfurization reaction device 13, a gas heat exchanger 18, a heating furnace 19, an ammonia injection system 20, a denitration reaction device 21, the gas heat exchanger 18, a waste heat boiler 22 and a third fan 25, and is finally discharged through a chimney 26.
A third NOx concentration analyzer 24 is further provided on the main flue 28 of the sintering machine located behind the third fan 25, for detecting NO in the flue gas before being discharged from the chimney 26xAnd (4) concentration.
According to a first NOx concentration analyzer 10 for detecting the original smoke, a second NOx concentration analyzer 17 at the denitration inlet and a third NOx concentration analyzer 24 and O in front of the inlet of a chimney 263And the data of the concentration analyzer 32 is fed back to perform PID automatic control and regulation on the ozone spraying amount of the first ozone spraying part and the second ozone spraying part. By automatically adjusting the ozone injection amount, the two ozone injection points are arranged to adjust NO/NO of an SCR reaction inlet2The mol ratio ensures that the rapid SCR reaction is carried out in the catalyst bed layer as much as possible, thereby improving the denitration reaction rate, reducing the dosage of the catalyst and prolonging the service life of the catalyst.
In order to further understand the utility model discloses a SOx/NOx control system, the utility model discloses still provide a SOx/NOx control method that sintering flue gas circulation unites ozone preoxidation, specifically include following step:
step one, sintering flue gas circulation
The flue gas led out from the specific bellows of the sintering machine 1 passes through the multi-tube cyclone dust collector 2, the first fan 3, the oxygen supply device and the sealing cover 9 and then is circulated into the sintering machine 1 again, the oxygen content of the flue gas in the sealing cover 9 after being supplied is ensured to be more than 18 percent and is used for hot air sintering, and the sintered flue gas enters the purification system for desulfurization and denitrification through the main flue 28 of the sintering machine.
Step two, desulfurization and denitrification reaction of ozone preoxidation treatment
The flue gas of the main flue 28 of the sintering machine sequentially passes through the handpiece electric dust remover 11, the first ozone preoxidation treatment and the second fan 23 and then enters the desulfurization reaction device 13 for desulfurization treatment and first denitration treatment, and part of high valence NO is removedXAnd then the flue gas enters a denitration reaction device 21 after passing through secondary ozone pre-oxidation treatment, a gas heat exchanger 18, a heating furnace 19 and an ammonia injection system 20, and is subjected to secondary denitration treatment, so that rapid SCR denitration reaction occurs.
Step three, discharging the flue gas
The flue gas after the denitration reaction is again subjected to heat recovery by the gas heat exchanger 18 and the waste heat boiler 22, the temperature of the flue gas is reduced, and the flue gas is discharged from the chimney 26.
To sum up, the utility model adopts the desulfurization and denitrification reaction combining the sintering flue gas circulation process and the ozone pre-oxidation treatment, and the pure oxygen is supplemented in the sintering flue gas circulation process, and the spraying amount can be automatically adjusted, so that the sintering flue gas circulation rate is improved, the flue gas circulation rate is improved to more than 30%, and the total amount of the discharged flue gas can be reduced to a greater extent; the quality and the yield of finished ore are improved under the condition of not modifying a sintering machine trolley; the operating cost of pollutant control facilities such as dust removal, desulfurization and the like which are put into operation is reduced; the investment and the operation cost of pollutant control facilities of the newly built sintering machine are reduced.
The adopted ozone pre-oxidation process is characterized in that an ozone injection point is arranged in front of the desulfurization reaction device, and the ozone partially oxidizes NO in the flue gas before the desulfurization reaction into NO2、N2O5The high-valence NOx is partially removed in the desulfurization reaction device, the concentration of NOx at the inlet of the denitrification reaction device is reduced, and the load of subsequent denitrification reaction is reduced; in addition, the flue gas before denitration reaction is also subjected to ozone preoxidation treatment to control NO/NO of the flue gas2Mole ofAnd (3) realizing rapid denitration reaction. The utility model discloses a SOx/NOx control system and technology have reduced solid fuel consumption, have improved denitration reaction rate, reduce the catalyst quantity, and extension catalyst life practices thrift investment running cost, through two denitration reaction places, makes NOx discharge and reaches and surpass the ultralow emission target.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A desulfurization and denitrification system combining sintering flue gas circulation and ozone pre-oxidation is characterized by comprising: the desulfurization reaction device and the denitration reaction device of setting on sintering machine flue and ozone preparation facilities, wherein:
the ozone preparation device is used for preparing ozone, and the ozone is used for carrying out primary ozone pre-oxidation treatment on the flue gas in the main flue of the sintering machine before entering the desulfurization reaction device and carrying out secondary ozone pre-oxidation treatment on the flue gas in the main flue of the sintering machine before entering the denitrification reaction device;
the flue gas subjected to the first ozone pre-oxidation enters the desulfurization reaction device, and the desulfurization reaction device is used for performing desulfurization treatment and first denitration treatment on the flue gas;
and the flue gas from the desulfurization reaction device enters the denitration reaction device after being subjected to secondary ozone pre-oxidation, and the denitration reaction device is used for carrying out secondary denitration treatment on the flue gas.
2. The desulfurization and denitrification system combining sintering flue gas circulation and ozone pre-oxidation as claimed in claim 1, wherein the system further comprises a sintering flue gas circulation device, the sintering flue gas circulation device comprises a circulation flue, and the circulation flue and the sintering equipment form a loop;
one end of the circulating flue is communicated with part of air boxes of the sintering machine, and the other end of the circulating flue is communicated with the charge level of the sintering machine; one end of the circulating flue is communicated with the middle front section and the rear section of the air box of the sintering machine;
the sintering flue gas circulating device is sequentially provided with a first dust remover, a first fan and an oxygen supply device along the flow direction of flue gas in the circulating flue; the oxygen supply device is used for supplying oxygen to the flue gas in the circulating flue; the first dust remover is a multi-cyclone dust remover.
3. The system for desulfurization and denitrification by combination of sintering flue gas circulation and ozone pre-oxidation as claimed in claim 2, wherein the oxygen supply device comprises an oxygen distributor connected to an outlet of the oxygen buffer tank, and oxygen ejected from the oxygen distributor enters the circulation flue.
4. The system for desulfurization and denitrification by combination of flue gas recirculation and ozone pre-oxidation as claimed in claim 3, wherein the flue gas recirculation device further comprises a plurality of sealing hoods, the flue gas after oxygen supply enters the plurality of sealing hoods through a plurality of branch pipelines respectively, the inner cavities of the sealing hoods are communicated with the charge level of the sintering machine, and a flue gas regulating valve is arranged on each of the plurality of branch pipelines and used for regulating the flue gas entering the sealing hoods;
the sealing cover is fixed above the material level of the middle section of the sintering machine, one end of the main flue of the sintering machine is at least connected with the machine head and the middle section air box of the sintering machine, and flue gas in the circulating flue of the sintering machine enters the middle section of the sintering machine from the sealing cover and enters the main flue of the sintering machine from the middle section air box;
the sealed cover is provided with a pressure gauge and an oxygen concentration analyzer, the oxygen concentration analyzer is connected with the oxygen supply device, and the oxygen supply process is automatically controlled according to the oxygen concentration in the sealed cover.
5. The desulfurization and denitrification system combining sintering flue gas circulation and ozone pre-oxidation as claimed in claim 1, wherein the ozone prepared by the ozone preparation device is diluted and mixed with air;
the ozone is transmitted through a first pipeline and is injected into a main flue of the sintering machine through a first ozone uniform distributor to carry out primary ozone pre-oxidation treatment; the ozone is transmitted through a second pipeline and is injected into the main flue of the sintering machine through a second ozone uniform distributor to carry out secondary ozone pre-oxidation treatment;
the first ozone uniform distributor is arranged at a first ozone spraying part of the main flue of the sintering machine; and the second ozone uniform distributor is arranged at a second ozone spraying part of the main flue of the sintering machine.
6. The desulfurization and denitrification system combining sintering flue gas circulation and ozone pre-oxidation as claimed in claim 5, wherein a second dust remover is further arranged on the main flue of the sintering machine, the second dust remover is a machine head electric dust remover, and the machine head electric dust remover is arranged in front of the first ozone injection part;
a first NOx concentration analyzer is arranged on the main flue of the sintering machine in front of the nose electric dust remover; a second NOx concentration analyzer is arranged on the sintering machine main flue behind the second ozone injection part; a third NOx concentration analyzer and O are arranged on the main flue of the sintering machine behind the denitration reaction device3A concentration analyzer.
7. The desulfurization and denitrification system with combined sintering flue gas circulation and ozone pre-oxidation according to claim 6, further comprising a control device at least connected with the first NOx concentration analyzer, the second NOx concentration analyzer, the third NOx concentration analyzer, and the O3The concentration analyzer, the first ozone injection part and the second ozone injection part are connected to analyze the concentration of the first NOx, the concentration of the second NOx, the concentration of the third NOx and the concentration of the O3The concentration analyzer data adjusts the amount of ozone in the first and second ozone injection portions.
8. The desulfurization and denitrification system combining sintering flue gas circulation and ozone pre-oxidation according to any one of claims 1-7, wherein a heat recovery device is arranged on the main flue of the sintering machine behind the denitrification reaction device.
9. The desulfurization and denitrification system combining sintering flue gas circulation and ozone pre-oxidation as claimed in claim 8, wherein the heat recovery device comprises a gas heat exchanger and a waste heat boiler, which are arranged in sequence along the flue gas transmission direction; the gas heat exchanger is communicated with the sintering machine main flue at the flue gas inlet of the denitration reaction device and is communicated with the sintering machine main flue at the outlet of the denitration reaction device;
the desulfurization reaction device is a circulating fluidized bed desulfurization reactor; the denitration reaction device is an SCR reaction device.
10. The desulfurization and denitrification system combining sintering flue gas circulation and ozone pre-oxidation as claimed in claim 1, wherein a heating furnace and an ammonia injection system are sequentially arranged on a main flue of the sintering machine in front of the denitrification reaction device along the flue gas transmission direction.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110523251A (en) * | 2019-09-24 | 2019-12-03 | 北京中航泰达环保科技股份有限公司 | A kind of system for desulfuration and denitration and method of sintering flue gas circulation joint ozone pre-oxidation |
| CN118416680A (en) * | 2024-07-05 | 2024-08-02 | 深圳市天浩洋环保股份有限公司 | Exhaust gas purifying device |
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2019
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110523251A (en) * | 2019-09-24 | 2019-12-03 | 北京中航泰达环保科技股份有限公司 | A kind of system for desulfuration and denitration and method of sintering flue gas circulation joint ozone pre-oxidation |
| CN118416680A (en) * | 2024-07-05 | 2024-08-02 | 深圳市天浩洋环保股份有限公司 | Exhaust gas purifying device |
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