CN111992012A

CN111992012A - Supplementary type resource cooperative control system for flue gas of coal-fired unit

Info

Publication number: CN111992012A
Application number: CN202010707355.XA
Authority: CN
Inventors: 朱晓磊; 李剑宁; 崇培安; 何翔; 陶丽
Original assignee: Shanghai Shangfayuan Power Generation Complete Equipment Engineering Co ltd; Shanghai Power Equipment Research Institute Co Ltd
Current assignee: Shanghai Shangfayuan Power Generation Complete Equipment Engineering Co ltd; Shanghai Power Equipment Research Institute Co Ltd
Priority date: 2020-07-21
Filing date: 2020-07-21
Publication date: 2020-11-27

Abstract

The invention provides a supplementary type resource cooperative control system for flue gas of a coal-fired unit, which comprises a flue, an ozone supply unit, an ozone nozzle, a supplementary washing tower, a liquid ammonia solution supply unit with a liquid ammonia solution tank, a liquid ammonia nozzle and a byproduct recovery unit, wherein the ozone nozzle is arranged in the flue and connected with the ozone supply unit, the supplementary washing tower is arranged in the flue, the liquid ammonia solution supply unit is arranged in the liquid ammonia solution tank, the liquid ammonia nozzle is arranged in the supplementary washing tower and connected with the liquid ammonia solution tank, and the byproduct recovery unit comprises a fan, a supplementary oxygenation pipeline, a delivery pump and a dryer which are arranged in the. The method can efficiently remove residual SOx and NOx in the tail flue gas of the coal-fired unit, supplement desulfurization, denitrification, dedusting and purification of the coal-fired unit, and achieve the purpose of further cooperative control of flue gas pollutants; by adopting oxidation denitration, the oxidation denitration reaction has no obvious requirement on temperature, and low-temperature denitration is realized, so that the application has strong adaptability to the system temperature; the by-products obtained after desulfurization and denitrification can be recycled as ammonia fertilizers, and the synergistic matching of emission reduction and resource utilization is realized.

Description

Supplementary type resource cooperative control system for flue gas of coal-fired unit

Technical Field

The invention relates to the field of tail flue gas treatment in a coal-fired unit, in particular to a supplementary type resource cooperative control system for flue gas of the coal-fired unit.

Background

In a conventional coal-fired unit, tail flue gas treatment equipment comprises an SCR denitration device, an electrostatic dust collector and a desulfurization tower, wherein flue gas at the outlet of the desulfurization tower is saturated wet flue gas at the temperature of 50-60 ℃. At present, the emission concentrations of smoke, sulfur dioxide and nitrogen oxide of atmospheric pollutants of a coal-fired unit are required to be respectively not higher than 10, 35 and 50mg/Nm³。

Under the requirement of the current ultra-low emission standard, the provincial and urban departments and the power generation group actively self-code-add and customize the near-zero emission standard for turning the impression of high pollution and strong emission of the public to the coal-fired unit, namely the emission concentrations of smoke dust, sulfur dioxide and nitrogen oxide of atmospheric pollutants are respectively not higher than 1, 10 and 25mg/Nm³. Under the standard, the conventional SCR denitration and wet Ca desulfurization process can hardly meet the index requirements, and a power plant needs to invest huge funds to carry out effect improvement treatment on the process, and the operation cost is huge, so that the operation economy of the boiler is influenced.

In addition, under the conditions of furnace starting and low load, the existing flue gas temperature cannot meet the operation temperature requirement of the denitration SCR. Aiming at the requirement of flexibility of operation of a coal-fired unit, various wide-load denitration improvement technologies are provided by research units, but denitration at a start-up stage cannot be realized comprehensively, a denitration system at the start-up stage cannot be put into operation and cannot enjoy denitration electricity price subsidy, and full-working-condition denitration cannot be really realized.

Further, chinese patent application publication No. CN106000048A discloses a low-temperature desulfurization and denitration system, which uses an orifice plate corrugated packing absorption tower to fully absorb pollutants in the exhaust gas with alkali solution, and then adds the alkali solution into an evaporation concentration cycle to regenerate the solution without discharging waste liquid to the outside; however, this technique is applicable to medium NO₂Is the dominant organic waste gas and can not be adapted to the coal-fired flue gas with NO as the dominant gas.

Further, the chinese patent application publication No. CN106334423A discloses a low-temperature denitration process based on activated carbon material, which uses activated carbon as a carrier to trap SO in a denitration and treatment system₂NOx is removed in the denitration fixed bed reactor, and the purpose of synchronously removing pollutants is realized; but the process still has certain requirements on the reaction temperature, the efficiency is sharply reduced when the temperature is lower than 80 ℃, and in addition, the cost of the activated carbon is higher, thereby influencing the further popularization and application.

In summary, the prior art has at least the following problems: has poor adaptability to the flue gas of a coal-fired unit and removes SO₂And the cost of NOx is too high, and the denitration effect needs to be improved.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a supplementary resource cooperative control system for flue gas of a coal-fired unit, which can efficiently remove SOx (mainly SO) remaining in the tail flue gas of the coal-fired unit in a low-temperature environment₂) And NOx.

In order to achieve the above purpose, the present invention provides a supplementary type resource cooperative control system for flue gas of a coal-fired unit, which comprises a flue, an ozone supply unit, an ozone nozzle arranged in the flue, a supplementary washing tower, a liquid ammonia solution supply unit, a liquid ammonia nozzle arranged in the supplementary washing tower, and a byproduct recovery unit, wherein the flue is used for conveying tail flue gas desulfurized in the coal-fired unit, the ozone supply unit is connected with the ozone nozzle, the liquid ammonia solution supply unit comprises a liquid ammonia solution tank arranged at the bottom of the supplementary washing tower, the liquid ammonia solution tank is connected with the liquid ammonia nozzle, a flue gas inlet of the supplementary washing tower is connected with the flue, a chimney is arranged at a flue gas outlet of the supplementary washing tower, the liquid ammonia nozzle is positioned at the upper side of the flue gas inlet of the supplementary washing tower, and the byproduct recovery unit comprises a fan, a, Supplementary oxygenation pipeline, delivery pump and the desicator of setting in liquid ammonia solution case, the fan passes through the pipeline and links to each other with supplementary oxygenation pipeline, the entry end of delivery pump links to each other with liquid ammonia solution case, the exit end of delivery pump passes through the pipeline and links to each other with the desicator.

Further, the ozone supply unit comprises a fan, an air separator, an ozone generator and an ozone distributor which are sequentially connected in series through pipelines, wherein the fan, the air separator and the ozone generator are arranged outside the flue, the ozone distributor is arranged inside the flue, and the ozone nozzle is arranged on the ozone distributor.

Furthermore, a section of straight tube extending straightly is arranged in the flue, and the ozone nozzle is arranged in the section straight tube and sprays ozone in the reverse direction of the flow direction of the tail flue gas in the section straight tube.

Further, the segmented straight tube extends vertically.

Further, the ozone uniform distributor is in a grid shape or a crotch shape and is provided with a plurality of ozone conveying pipes which are arranged in a staggered mode.

Further, the adoption of the ozone distributor is SS 316L.

Further, the supplementary resource cooperative control system further comprises a controller, a concentration detector arranged at the flue gas outlet, and a flow control valve arranged on a connecting pipeline of the fan and the air separator, wherein the concentration detector, the flow control valve and the ozone generator are all connected with the controller.

Further, liquid ammonia solution supply unit still includes ammonia station and volumetric pump, the ammonia station passes through the pipeline with liquid ammonia solution case and links to each other, liquid ammonia solution case passes through the pipeline with the liquid ammonia nozzle and links to each other, the volumetric pump is installed on the pipeline of connecting liquid ammonia solution case and liquid ammonia nozzle.

Further, the output end of the supplementary oxygen adding pipeline is immersed at the bottom of the liquid ammonia solution tank.

Further, supplementary resource cooperative control system still includes air heater, fan, air heater and desicator pass through the pipeline and concatenate in proper order.

Further, the top of the supplementary washing tower is provided with a dehydrator positioned on the lower side of the flue gas outlet.

As described above, the supplementary resource cooperative control system for the flue gas of the coal-fired unit according to the present invention has the following beneficial effects:

the application can oxidize NO insoluble in water in tail smoke gas into NO₂And N₂O₅After the oxidized tail flue gas progresses and liquid ammonia solution sprayed down in the supplementary washing tower is subjected to countercurrent heat-mass exchange, SO in the tail flue gas is obtained₂And NOx by NH₃Absorption to form (NH)₄)₂SO₃And NH₄NO₂The clean flue gas is discharged through a flue gas outlet and a chimney, SO that residual SO in the flue gas at the tail part of the coal-fired unit is efficiently removed₂And NOx, the desulfurization, denitrification, dust removal and purification of the coal-fired unit are supplemented, the aim of further cooperative control of the smoke pollutants is achieved, and the requirement of near zero emission standard is met. Particularly, oxidation denitration is adopted in the denitration system, and oxidation denitration reaction has no obvious requirement on temperature, so that low-temperature denitration is realized, the denitration system has strong adaptability to system temperature, denitration can be performed under the conditions of furnace starting and low load, and full-working-condition denitration is really realized. And the by-product recovery unit recovers the by-product (NH) generated₄)₂SO₃And NH₄NO₂The ammonium sulfate and the ammonium nitrate are oxidized, so that the byproducts generated in the washing tower are supplemented to be used as ammonia fertilizer for recycling, and the synergistic matching of emission reduction and resource utilization is realized.

Drawings

Fig. 1 is a block diagram illustrating a supplementary resource cooperative control system for flue gas of a coal-fired unit according to the present application.

Figure 2 is the structure schematic diagram of ozone uniform distributor in this application.

Description of the element reference numerals

10 flue

11 segmented straight pipe

20 ozone nozzle

30 supplementary scrubbing tower

31 flue gas inlet

32 flue gas outlet

40 liquid ammonia nozzle

50 chimney

60 blower

70 air separator

80 ozone generator

90 ozone uniform distributor

91 ozone delivery pipe

110 ammonia station

120 liquid ammonia solution tank

130 displacement pump

140 supplementary oxygen adding pipeline

150 delivery pump

160 dryer

170 air heater

180 water remover

190 original desulfurizing tower

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

It should be understood that the structures, proportions, and dimensions shown in the drawings and described herein are for illustrative purposes only and are not intended to limit the scope of the present invention, which is defined by the claims, but rather by the claims. In addition, the terms such as "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for convenience of description only and are not intended to limit the scope of the present invention, and changes or modifications of the relative relationship thereof may be made without substantial technical changes and modifications.

The application provides a supplementary type resource cooperative control system for coal-fired unit flue gas for tail flue gas after denitration desulfurization carries out low temperature desulfurization denitration treatment in to coal-fired unit. On the basis of the existing SCR denitration and wet Ca desulfurization, the supplementary type resource cooperative control system related by the application is cooperatively used with the existing pollutant treatment system in the coal-fired unit, and the existing pollutant treatment system in the coal-fired unit is usually an SCR denitration system and a desulfurization tower.

As shown in fig. 1, the supplementary resource cooperative control system for flue gas of a coal-fired unit according to the present application includes a flue 10, an ozone supply unit, an ozone nozzle 20 disposed in the flue 10, a supplementary washing tower 30, a liquid ammonia solution supply unit, a liquid ammonia nozzle 40 disposed in the supplementary washing tower 30, and a byproduct recovery unit; the flue 10 is used for conveying tail flue gas after denitration and desulfurization by a pollutant treatment system in the coal-fired unit, so that the inlet end of the flue 10 is connected with the outlet end of the original desulfurization tower 190; the ozone supply unit is connected with the ozone nozzle 20 and used for supplying ozone to the ozone nozzle 20; the liquid ammonia solution supply unit comprises a liquid ammonia solution tank 120 arranged at the bottom of the supplementary washing tower 30, and the liquid ammonia solution tank 120 is connected with the liquid ammonia nozzle 40 and is used for supplying liquid ammonia solution to the liquid ammonia nozzle 40; the flue gas inlet 31 of the supplementary washing tower 30 is connected with the outlet end of the flue 10; a chimney 50 is arranged at the flue gas outlet 32 of the supplementary washing tower 30; the liquid ammonia nozzle 40 is positioned at the upper side of the flue gas inlet 31 of the supplementary washing tower 30; the byproduct recovery unit comprises a fan 60, a supplementary oxygen adding pipeline 140 arranged in the liquid ammonia solution tank 120, a delivery pump 150 and a dryer 160, wherein the fan 60 is connected with the supplementary oxygen adding pipeline 140 through a pipeline, the inlet end of the delivery pump 150 is connected with the liquid ammonia solution tank 120, and the outlet end of the delivery pump 150 is connected with the dryer 160 through a pipeline. The ozone nozzle 20 and the ozone supply unit form an ozone oxidation system, and the original desulfurizing tower 190, the ozone oxidation system, the supplementary washing tower 30 and the chimney 50 are sequentially connected in series along the flow direction of the tail flue gas.

After the supplementary type resource cooperative control system is started, tail flue gas which is subjected to denitration by the SCR denitration system and desulfurization by the original desulfurization tower 190 in the coal-fired unit enters the flue 10 of the supplementary type resource cooperative control system in sequence, and ozone sprayed by the ozone nozzle 20 in the flue 10 oxidizes NO which is insoluble in water in the tail flue gas into NO₂And N₂O₅，NO₂And N₂O₅The ratio of (a) to (b) is related to the amount of ozone added; the oxidized tail flue gas enters a supplementary washing tower 30 and flows from bottom to top, a liquid ammonia nozzle 40 in the supplementary washing tower 30 sprays liquid ammonia solution downwards, the liquid ammonia solution and the oxidized tail flue gas perform countercurrent heat and mass exchange, and SO in the tail flue gas₂And NOx by NH₃Absorption to form (NH)₄)₂SO₃And NH₄NO₂The remainder is exhausted to the atmosphere via the flue gas outlet 32 and the stack 50. The byproduct recovery unit will replenish the byproduct (NH) generated in the scrubber 30₄)₂SO₃And NH₄NO₂The ammonium sulfate and the ammonium nitrate are oxidized into the ammonium sulfate and the ammonium nitrate, and the ammonium sulfate and the ammonium nitrate are recovered and used for the agricultural fertilizer, so that the aim of resource utilization is fulfilled; in particular, (NH) is generated₄)₂SO₃And NH₄NO₂Deposited at the bottom of the liquid ammonia solution tank 120, the blower 60 pressurizes and delivers the air to the supplemental oxygen adding pipe 140, and the supplemental oxygen adding pipe 140 delivers the air into the liquid ammonia solution tank 120, so that oxygen in the air generates (NH) in the liquid ammonia solution tank 120₄)₂SO₃And NH₄NO₂Is further oxidized into NH₄NO₃And (NH)₄)₂SO₄So that the concentrated liquid is generated at the bottom of the liquid ammonia solution tank 120,transfer pump 150 will contain NH₄NO₃And (NH)₄)₂SO₄The concentrated solution is conveyed to a dryer 160 for dehydration and drying treatment, and the finished product ammonia fertilizer is obtained. Therefore, supplementary denitration desulfurization purification is realized from this application, reaches further flue gas pollutant cooperative control's purpose. Particularly, oxidation denitration is adopted in the denitration system, and oxidation denitration reaction has no obvious requirement on temperature, so that low-temperature denitration is realized, the denitration system has strong adaptability to system temperature, denitration can be performed under the conditions of furnace starting and low load, and full-working-condition denitration is really realized. Therefore, the method can be used for efficiently removing SOx and NOx in the tail flue gas of the coal fired unit in a low-temperature environment, and meets the index requirements of near zero emission and full-load denitration.

Further, as shown in fig. 1, the ozone supply unit includes a blower 60, an air separator 70, an ozone generator 80, and an ozone distributor 90 connected in series in sequence through a pipeline, the blower 60, the air separator 70, and the ozone generator 80 are all disposed outside the flue 10, the ozone distributor 90 is disposed inside the flue 10, and the ozone nozzle 20 is mounted on the ozone distributor 90. Air is pressurized by a fan 60 to enter a pipeline and is conveyed to an air separator 70, the air separator 70 carries out oxygen enrichment and conveys oxygen to an ozone generator 80, the ozone generator 80 carries out ozone preparation and conveys ozone to an ozone distributor 90, the ozone distributor 90 uniformly conveys ozone to each ozone nozzle 20, finally the ozone nozzles 20 spray ozone into a flue 10 to mix the ozone with NO insoluble in water in the flue 10, and NO is oxidized into NO₂And N₂O₅. This ozone supply unit has advantages such as equipment independence, operation flexibility, operation maintenance cost are low, need not have with SCR's reaction temperature interval, does not receive the influence of boiler combustion condition, at the field that traditional denitration technique can't satisfy, and application prospect is extensive.

Preferably, a buffer tank may be disposed between the blower 60 and the air separator 70, and the blower 60, the buffer tank, the air separator 70, the ozone generator 80, and the ozone distributor 90 are sequentially arranged in series, and pressure balancing is performed through the buffer tank. Preferably, the air separation machine adopts a VPSA molecular sieve technology to perform oxygen enrichment, the VPSA molecular sieve adsorbs other gas components under normal pressure to generate oxygen, and the molecular sieve is analyzed and regenerated under a vacuum condition, so that the air separation machine alternately operates in a circulating manner; the ozone generator 80 preferably employs a high-voltage discharge type to decompose oxygen, and the combination of the two greatly reduces the power consumption required for ozone production. In this embodiment, the air separator 70 can operate at a concentration of 150-180 mg/L to provide the ozone generator 80 with an oxygen-rich source having an oxygen content of about 93%.

Further, as shown in fig. 1, a section of straight section tube 11 extending straight is provided in the flue 10, the straight section tube 11 extends vertically and is a vertical tube section, the ozone nozzle 20 is disposed in the straight section tube 11, and the ozone nozzle 20 reversely sprays ozone along the flow direction of the tail flue gas in the straight section tube 11, that is, the ozone nozzle 20 is reversely arranged with the tail flue gas, so as to enhance the mixing effect of ozone and the tail flue gas. As shown in figure 2, the ozone distributor 90 is in a grid shape or a fork shape and is provided with a plurality of ozone conveying pipes 91 which are arranged in a staggered way, and a plurality of ozone nozzles 20 are uniformly distributed and installed on the plurality of ozone conveying pipes 91, which is beneficial to the uniform injection of ozone in the segmented straight pipe 11. Based on this, the ozone distributor 90 in a grid shape or a crotch shape uniformly injects ozone gas into the plane of the vertical section straight pipe 11 in a state of fine aerosol particles, the tail flue gas flows downwards in the vertical pipe section, and the ozone nozzle 20 sprays ozone upwards, so that the mixing uniformity of the tail flue gas and the ozone gas can be greatly improved, and NO in the tail flue gas can be fully oxidized by the ozone. Preferably, the ozone sparger 90 is made of stainless steel under the material designation SS 316L.

Further, the supplementary resource cooperative control system further comprises a controller, a concentration detector arranged at the flue gas outlet 32, and a flow control valve arranged on a connecting pipeline of the fan 60 and the air separator 70, wherein the concentration detector, the flow control valve and the ozone generator 80 are all connected with the controller, and the controller is preferably a PID controller. The concentration detector is used for detecting the content of SOx and NOx at the flue gas outlet 32, and the controller controls the opening of the flow control valve and the power of the ozone generator 80 according to the feedback of the concentration detector, thereby adjusting the oxygen inlet flow flowing into the air separator 70 and the power of the ozone generator 80, and further adjusting the ozone adding amount in the vertical segmented straight pipe 11 in the flue 10, and realizing PID feed-forward control. In addition, a control valve is arranged between the ozone uniform distributor 90 and each ozone nozzle 20, the control valves are all connected with a controller, the control valves are independently controlled, the controller can adjust the ozone injection speed in the vertical segmented straight pipe 11 in the flue 10 by independently controlling the opening degrees of the control valves, the ozone adding amount is further matched with the content of SOx and NOx at the flue gas outlet 32, and the optimization of resource utilization is realized.

Further, as shown in fig. 1, the liquid ammonia solution supply unit further includes an ammonia station 110 and a volumetric pump 130, the ammonia station 110 is connected to the liquid ammonia solution tank 120 through a pipe, the liquid ammonia solution tank 120 is connected to the liquid ammonia nozzle 40 through a pipe, and the volumetric pump 130 is installed on the pipe connecting the liquid ammonia solution tank 120 and the liquid ammonia nozzle 40. The liquid ammonia solution tank 120, the volumetric pump 130 and the liquid ammonia nozzle 40 are connected to form a closed loop, the liquid ammonia solution ejected by the liquid ammonia nozzle 40 and the tail flue gas react and then fall into the liquid ammonia solution tank 120, and the volumetric pump 130 conveys the liquid ammonia solution in the liquid ammonia solution tank 120 to the liquid ammonia nozzle 40. While the liquid ammonia solution is circulated, the liquid ammonia solution is supplemented by the ammonia station 110, so that the material balance in the supplementary washing tower 30 is realized. The ammonia station 110 is preferably an existing ammonia station of a power plant, improving equipment and raw material utilization.

Preferably, as shown in fig. 1, the top of the supplementary washing tower 30 is provided with a water remover 180 located at the lower side of the flue gas outlet 32, and the water remover 180 is used for eliminating the solution entrainment in the flue gas after denitration and desulfurization. The liquid ammonia nozzle 40 in the supplementary washing tower 30 is a layer, or only one spraying layer is arranged in the supplementary washing tower 30, so that the energy consumption is reduced; the liquid ammonia nozzle 40 adopts a pressure nozzle and is a spiral nozzle, converts liquid ammonia solution in the pipeline into fine liquid ammonia solution particles, realizes spiral atomization and enables the fine liquid ammonia solution particles to perform sufficient heat and mass exchange with flue gas; meanwhile, the nozzle is sprayed out by small fog drops generated after liquid is tangent to and collides with the continuously-branched spiral line body, and due to the smooth channel design, the blocking phenomenon of the nozzle is reduced to the maximum extent, and the resistance coefficient is reduced to the minimum by the streamline design from the inlet to the outlet in the nozzle cavity. The supplementary washing tower 30 is provided with a guide plate at the flue gas inlet 31, and the tail flue gas entering the supplementary washing tower 30 is rectified and optimized to promote the uniform distribution of the tail flue gas, so that the reaction efficiency is improved, and the reaction effect is improved. The supplementary scrubbing tower 30 still is provided with W type defroster in dehydrator 180's top, and the interval is 0.03mm, carries out defogging dust removal processing to the flue gas after the dewatering to prevent that the liquid drop from taking place to escape along with the flue gas, avoid consequently causing liquid ammonia solution loss and flue 10 to corrode.

Preferably, the delivery pump 150 is a pneumatic delivery pump 150, and NH is delivered by pneumatic delivery₄NO₃And (NH)₄)₂SO₄Is discharged to the outside of the makeup scrubber 30.

Further, as shown in FIG. 1, supplemental oxygen supply line 140 is configured in an immersion configuration, i.e., the output end of supplemental oxygen supply line 140 is immersed in the bottom of liquid ammonia tank 120 to enhance supplemental oxidation of air (NH)₄)₂SO₃And NH₄NO₂The supplemental oxygen supply line 140 performs both supplemental oxidation and pneumatic transport functions, as the resulting concentrate is also being pushed to the exterior of the supplemental scrubber 30. The supplementary resource cooperative control system further comprises an air heater 170, the fan 60, the air heater 170 and the dryer 160 are sequentially connected in series through a pipeline, the fan 60 pressurizes air and conveys the air to the air heater 170 for heating, and then hot air is conveyed to the dryer 160 for drying ammonium salt, so that the drying effect of byproducts is improved, and the recovery efficiency of the byproducts is improved. Therefore, the heat source of the dryer 160 in the present application is from hot air. The heating power of the air heater 170 is adjustable, thereby controlling the dehydration drying effect of the ammonium salt.

Preferably, the blower 60 used in the ozone supply unit, the blower 60 connected to the supplemental oxygen supply pipeline 140, and the blower 60 connected to the air heater 170 are the same blower 60, so that the air for ozone preparation, the air for supplemental oxygen supply, and the air for drying and dewatering are all from the same blower 60, and therefore, the blower 60 in the present application adopts a "one-driving-three" operation mode, which is beneficial to improving the utilization rate of the equipment. Further, the fan 60 is preferably a centrifugal fan 60.

The following provides specific application examples of the supplementary resource cooperative control system according to the present application.

The supplementary type resource cooperative control system is used for a 660MW ultra-supercritical wet cooling unit of a certain power plant, and the 660MW ultra-supercritical wet cooling unit is operated by basic pressure lines of NOx and SOx concentration at a total discharge port of a chimney 50 even if small fluctuation exceeds 50 and 35mg/Nm because a boiler is W-shaped and burns high-sulfur coal³The baseline of the method, however, needs to strictly control the operation of the low index, can cause a series of problems such as reduction of boiler efficiency, high-temperature corrosion, great increase of air preheater resistance and the like, and the contradiction between environmental protection and economic index brings great troubles to the operation of the power plant. In addition, in the boiler starting stage and the rapid load lifting stage, the denitration catalyst needs to be withdrawn from operation because the smoke temperature cannot reach the requirement of 320 ℃, and the power plant needs to face an assessment step when the power plant cannot obtain denitration power price subsidies seriously. Aiming at a series of problems brought by emission indexes, the supplementary resource cooperative control system is introduced.

The tail flue gas purified by the original pollutant treatment system of the power plant is clean saturated wet flue gas with the temperature of 52 ℃, and the SOx content is 35mg/Nm³NOx content 50mg/Nm³Of which 95% are NO. About 5000Nm under the driving of the fan 60³The/h air enters a buffer tank, is subjected to pressure balance by the buffer tank and then enters the air separator 70. Oxygen enrichment is carried out in an air separator 70 by adopting VPSA molecular sieve technology to obtain oxygen with the purity of about 93 percent and the gas flow rate of about 500Nm³H is used as the reference value. Because the system is operated at low voltage, the power consumption level is very low and is 0.4kWh/Nm³O₂Compared with liquid oxygen and PSA oxygen production, the method has obvious cost advantage. The oxygen-enriched gas is prepared and then enters the ozone generator 80, partial oxygen is decomposed by utilizing a high-voltage discharge mode to obtain ozone, the high-frequency high-voltage ozone generator 80 adopts a 3-6kHz high-frequency power supply technology, and the micro-discharge gap design is combined, so that the ozone generation efficiency can be effectively improved, and the volume and the occupied space of the generator are reduced. When cooling with 30 deg.C cooling water, the maximum concentration is 0.18kg/Nm³The ozone yield is 60kg/h, and the required power consumption can be reduced to 7kWh/kgO₃. The produced ozone is delivered by an ozone uniform distributor 90And the ozone and the tail flue gas are fed to an ozone nozzle 20, and then the ozone and the tail flue gas are fully mixed and reacted in a vertical sectional straight pipe 11 in a flue 10. In the sectional straight pipe 11, the ozone reacts with NOx in the tail flue gas, mainly NO, to oxidize the NOx into NH₃Reacted NO₂And a small amount of N₂O₅。

In the supplementary washing tower 30, the tail flue gas after oxidation conversion and the sprayed liquid ammonia solution are subjected to countercurrent heat and mass exchange from bottom to top, and SO in the tail flue gas₂And NOx by NH₃Absorption to form (NH)₄)₂SO₃And NH₄NO₂The clean flue gas is exhausted to the atmosphere through the flue gas outlet 32 and the chimney 50 to achieve the near-zero index. The liquid ammonia solution sprays downwards to react with tail flue gas and then falls into a liquid ammonia solution tank 120 at the bottom of the supplementary washing tower 30, returns to the liquid ammonia nozzle 40 under the suction action of the volumetric pump 130, and sprays again to form circulation, and the circulating spraying amount is 138 t/h. Since the sprayed liquid ammonia solution is continuously converted into reaction products and deposited at the bottom of the liquid ammonia solution tank 120, 50kg/h of ammonia solution needs to be continuously supplemented from the existing ammonia station of the power plant to enter the liquid ammonia solution tank 120 to maintain the material balance.

(NH) generated in the supplementary washing tower 30 after the pollutants in the flue gas are absorbed by the liquid ammonia solution₄)₂SO₃And NH₄NO₂Depositing on the bottom of the liquid ammonia solution tank 120, and under the action of the fan 60, air enters the bottom of the liquid ammonia solution tank 120 through the supplementary oxygen adding pipe 140 to react with the reactant (NH)₄)₂SO₃And NH₄NO₂Is further oxidized into NH₄NO₃And (NH)₄)₂SO₄And discharged by pneumatic conveyance, and the finally produced by-product is sent into the dryer 160 through a conveying section. And (3) dehydrating and drying in a dryer 160 by using hot air as a heat source, dehydrating, drying and crystallizing the by-product to obtain ammonium salt, and feeding the ammonium salt into a bin for packaging after further tempering to obtain the commercial ammoniated fertilizer for recycling the finished product of the by-product.

Therefore, the supplementary resource cooperative control system according to the present applicationThe system can utilize the existing chatty of the power plant to carry out low-temperature oxidation denitration, and is matched with the original SCR catalyst and Ca desulfurizing tower of the power plant to be used as a supplement to further reduce the concentration of NOx and SOx to 25 and 10mg/Nm³Or the device is replaced under the abnormal operation working conditions of start-stop, ultra-low load and the like for operation, so that the deep standard emission of the smoke under the full working conditions is realized; the waste discharged by the power plant is converted into the ammoniated fertilizer with high value ratio for recycling, so that the waste is changed into valuable, the harm is turned into good, and the resource utilization of the waste of the power plant is realized.

In summary, the supplementary resource cooperative control system according to the present application has the following beneficial effects:

1. the system temperature adaptability is strong. The conventional SNCR needs to be carried out at a high temperature of 800-1000 ℃; the existing SCR needs to react within a range of 320-400 ℃, and has strict temperature control requirements; and oxidation denitration in this application does not have obvious requirement to reaction temperature, consequently can arrange in the afterbody flue, realizes low temperature denitration.

2. The reaction efficiency is high. The heat and mass exchange of the liquid ammonia solution and the flue gas in a countercurrent manner is carried out in the supplementary washing tower 30, and the reaction area is greatly increased after the liquid ammonia solution is made into solution fog drops, so that NOx and SOx in the flue gas can be fully reacted, the effect of supplementary desulfurization and denitrification is achieved, and the synergistic control of pollutants is realized.

3. The system is simple to arrange. Only a supplementary washing tower 30 is added in the tail flue, and the system can be regarded as the tail flue when being stopped, so that the original operation of the power plant is not influenced. The wind and liquid ammonia solution used by the system are the existing materials of the power plant, and only a little equipment is needed to transport the materials into the system, so that the operation cost is greatly reduced. The system absorbs pollutants by adopting the existing materials of the power plant, and the power plant is small in modification amount.

4. And (5) resource utilization of the waste. And (3) recycling the finished product of the ammonia fertilizer which is the conversion byproduct of NOx and SOx in the exhaust smoke of the power plant, thereby realizing the cooperative matching of the emission reduction and resource utilization of the power plant.

Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A supplementary type resource cooperative control system for coal-fired unit flue gas which characterized in that: comprises a flue (10), an ozone supply unit, an ozone nozzle (20) arranged in the flue (10), a supplementary washing tower (30), a liquid ammonia solution supply unit, a liquid ammonia nozzle (40) arranged in the supplementary washing tower (30) and a byproduct recovery unit, wherein the flue (10) is used for conveying tail flue gas after desulfurization in a coal-fired unit, the ozone supply unit is connected with the ozone nozzle (20), the liquid ammonia solution supply unit comprises a liquid ammonia solution tank (120) arranged at the bottom of the supplementary washing tower (30), the liquid ammonia solution tank (120) is connected with the liquid ammonia nozzle (40), a flue gas inlet (31) of the supplementary washing tower (30) is connected with the flue (10), a chimney (50) is arranged at a flue gas outlet (32) of the supplementary washing tower (30), and the liquid ammonia nozzle (40) is positioned at the upper side of the flue gas inlet (31) of the supplementary washing tower (30), the byproduct recovery unit comprises a fan (60), a supplementary oxygenation pipeline (140) arranged in the liquid ammonia solution tank (120), a delivery pump (150) and a dryer (160), wherein the fan (60) is connected with the supplementary oxygenation pipeline (140) through a pipeline, the inlet end of the delivery pump (150) is connected with the liquid ammonia solution tank (120), and the outlet end of the delivery pump (150) is connected with the dryer (160) through a pipeline.

2. A supplemental resource cooperative control system according to claim 1, wherein: the ozone supply unit comprises a fan (60), an air separator (70), an ozone generator (80) and an ozone distributor (90) which are sequentially connected in series through pipelines, wherein the fan (60), the air separator (70) and the ozone generator (80) are arranged outside the flue (10), the ozone distributor (90) is arranged inside the flue (10), and the ozone nozzle (20) is arranged on the ozone distributor (90).

3. A supplemental resource cooperative control system according to claim 1 or 2, wherein: the flue (10) is internally provided with a straight section of straight pipe (11), the ozone nozzle (20) is arranged in the straight section pipe (11), and the ozone nozzle (20) reversely sprays ozone along the flow direction of the tail flue gas in the straight section pipe (11).

4. A supplemental resource cooperative control system according to claim 3, wherein: the segmented straight pipe (11) extends vertically.

5. A supplemental resource cooperative control system according to claim 2, wherein: the ozone uniform distributor (90) is in a grid shape or a crotch shape and is provided with a plurality of ozone conveying pipes (91) which are arranged in a staggered mode.

6. A supplemental resource cooperative control system according to claim 2, wherein: the adoption of the ozone distributor (90) is SS 316L.

7. A supplemental resource cooperative control system according to claim 2, wherein: the device also comprises a controller, a concentration detector arranged at the flue gas outlet (32) and a flow control valve arranged on a connecting pipeline of the fan (60) and the air separator (70), wherein the concentration detector, the flow control valve and the ozone generator (80) are all connected with the controller.

8. A supplemental resource cooperative control system according to claim 1, wherein: the liquid ammonia solution supply unit further comprises an ammonia station (110) and a volumetric pump (130), wherein the ammonia station (110) is connected with the liquid ammonia solution tank (120) through a pipeline, the liquid ammonia solution tank (120) is connected with the liquid ammonia nozzle (40) through a pipeline, and the volumetric pump (130) is installed on the pipeline connecting the liquid ammonia solution tank (120) and the liquid ammonia nozzle (40).

9. A supplemental resource cooperative control system according to claim 1, wherein: the output end of the supplementary oxygen adding pipeline (140) is immersed at the bottom of the liquid ammonia solution tank (120).

10. A supplemental resource cooperative control system according to claim 1, wherein: the drying device is characterized by further comprising an air heater (170), wherein the fan (60), the air heater (170) and the dryer (160) are sequentially connected in series through pipelines.

11. A supplemental resource cooperative control system according to claim 1, wherein: the top of the supplementary washing tower (30) is provided with a dehydrator (180) positioned on the lower side of the flue gas outlet (32).