CN110665336A - Liquid-phase flue gas denitration and absorption liquid regeneration integrated method and device - Google Patents
Liquid-phase flue gas denitration and absorption liquid regeneration integrated method and device Download PDFInfo
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- CN110665336A CN110665336A CN201911118237.9A CN201911118237A CN110665336A CN 110665336 A CN110665336 A CN 110665336A CN 201911118237 A CN201911118237 A CN 201911118237A CN 110665336 A CN110665336 A CN 110665336A
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1425—Regeneration of liquid absorbents
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- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1493—Selection of liquid materials for use as absorbents
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/18—Absorbing units; Liquid distributors therefor
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- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
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- B01D53/18—Absorbing units; Liquid distributors therefor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
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Abstract
The invention discloses an integrated method for liquid-phase flue gas denitration and denitration liquid regeneration, which comprises the following steps of firstly, continuously conveying flue gas into an absorption tower from a flue gas inlet at the middle lower part of the absorption tower; then preparing absorption liquid, filtering the absorption liquid, spraying the absorption liquid from the top of the absorption tower to absorb NO in the flue gas, and enabling the absorption liquid after reaction to fall into a second liquid storage tank at the bottom of the absorption tower; pumping the absorption liquid in the second liquid storage tank into the top of the absorption tower again, spraying the absorption liquid downwards, and carrying out counter-current contact with the flue gas to carry out denitration; pumping the absorption liquid to be regenerated in the second liquid storage tank into an absorption liquid regeneration unit, adding zinc powder into the regeneration unit, stirring to enable the zinc powder to be completely reacted with ferric ions in the denitration liquid, completing regeneration, finally pumping the regenerated absorption liquid into the top of the absorption tower, spraying, dropping into the second liquid storage tank again, and repeating the steps; finally, the flue gas is discharged through a flue gas outlet after dehumidification treatment. The method can effectively remove NO in the flue gas and regenerate the absorption liquid.
Description
The technical field is as follows:
the invention belongs to the technical field of air pollution control, and relates to a flue gas denitration integrated device, in particular to an iron complex compound mixed absorption system denitration and zinc powder reduction regeneration absorption liquid, which is suitable for industrial high-moisture flue gas denitration occasions.
Background art:
with the rapid development of modern economy, the rapid advance of industry also causes a series of problems. The combustion of fossil fuels causes atmospheric pollution. The influence of sulfides, nitrogen oxides, dust particles and the like on the environment is large. Among them, nitrogen oxides and sulfides are pollutants having relatively large emission amounts. The sulfur compounds and nitrogen oxides not only have influence on the environment but also have threat on the health of human beings, such as acid rain with other compounds, corrosion of buildings, influence on the normal growth of plants, and also generate chemical smog, and influence on the daily life of human beings. After many years of continuous efforts, the treatment of sulfide has formed a more mature process, but the treatment of nitrogen oxide has some problems. The control method of nitrogen oxides is divided into dry denitration and wet denitration. Currently, the most common dry denitration is Selective Catalytic Reduction (SCR), which involves NH3Reaction with NO to form N2And H2And O. Although this method is highly efficient, it has some disadvantages. For example, the temperatures required for the catalytic process are high, and other components in the flue gas can adversely affect the activity of the catalyst, meaning that the life of the catalyst will be shortened. In particular, the moisture content of flue gases discharged from smelting plants and industrial boilers is relatively large, and the SCR treatment apparatus does not have any advantage in this respect. Therefore, a denitration method for treating high moisture content flue gas is highly needed. Complex denitration is one of effective methods for liquid denitration, and has attracted extensive attention due to high efficiency and low temperature, so that the complex denitration not only has good denitration effect, but also has good denitration effectTherefore, the complex denitration method has obvious advantages for the treatment of the high-moisture-content flue gas. The so-called complex denitration is to use transition metal ions (such as cd)2+,Fe2+,Co2 +,Ni+) And an aminocarboxylic acid ligand (EDTA) or a sulfenyl ligand to form a complex, and then the complex is finally rapidly reacted with NO to generate a metal nitrosyl compound, so that the solubility of the metal nitrosyl compound in water is increased, and the aim of removing nitrogen oxides is fulfilled. For example, patent CN105032152B discloses a synchronous flue gas desulfurization and denitration process combining chemical absorption with microbial fuel cell, which adopts ferrous complexing agent (II) (L) to absorb NO in flue gas in a denitration absorption tower, and the reaction between fe (II) EDTA and NO is (taking EDTA as an example): fe (II) EDTA + NO → Fe (II) EDTA NO, because bivalent iron ion is easy to be oxidized into trivalent iron ion in the process, part of the adsorbent Fe (II) EDTA and the product Fe (II) EDTA NO after adsorption are both oxidized, in order to realize the recycling of the adsorbent, Fe (III) EDTA and Fe (III) EDTA NO are reduced generally, in the patent, an ultrasonic transducer is adopted to strengthen sulfate radical reduction and regenerate the complexed iron ion, and the reduction reaction rate is accelerated. The invention solves the problem of recycling of the absorption liquid in the complex denitration process from another aspect.
The invention content is as follows:
the invention aims to overcome the defect of low efficiency of treating high-moisture flue gas by dry denitration, and provides a low-temperature high-efficiency liquid-phase integrated denitration method and a low-temperature high-efficiency liquid-phase integrated denitration device. Ferrous ammonium sulfate, disodium ethylene diamine tetraacetate and sodium citrate are prepared into a composite solution according to a certain proportion, the obtained solution has the capability of absorbing nitric oxide, and meanwhile, zinc powder is used as a reducing agent to reduce the absorbed nitric oxide into nitrogen and partial ammonium salt and also reduce oxidized ferric iron into ferrous iron to continuously play a role, and the device comprises a spraying process and a reduction process.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention relates to an integrated method for liquid-phase flue gas denitration and denitration liquid regeneration, which specifically comprises the following steps:
(1) continuously conveying the flue gas from a flue gas inlet at the middle lower part of the absorption tower into the absorption tower;
(2) preparing absorption liquid, wherein the absorption liquid comprises ammonium ferrous sulfate, disodium ethylene diamine tetraacetate and sodium citrate, the absorption liquid is filtered and sprayed down from the top of the absorption tower, the absorption liquid is in countercurrent contact with the flue gas to react, NO in the flue gas is absorbed, and the reacted absorption liquid falls into a second liquid storage tank at the bottom of the absorption tower;
(3) pumping the absorption liquid falling into the second liquid storage tank into the top of the absorption tower again, spraying the absorption liquid downwards, contacting with the flue gas in a counter-current manner for denitration, and then returning the absorption liquid into the second liquid storage tank;
(4) pumping the absorption liquid to be regenerated in the second liquid storage tank into an absorption liquid regeneration unit, adding zinc powder into the regeneration unit, stirring to enable the zinc powder to be completely reacted with ferric ions in the denitration liquid, completing regeneration, finally pumping the regenerated absorption liquid into the top of the absorption tower, spraying, dropping into the second liquid storage tank again, and repeating the steps;
(5) and (4) continuously absorbing NO in the flue gas, rising to the tower top, and finally discharging through a flue gas outlet after dehumidification treatment.
In the denitration stable operation process of the steps (2) - (4), the temperature in the first liquid storage tank is 45 ℃, the temperature in the third liquid storage tank is 30 ℃, and the temperature in the absorption tower is 50-60 ℃; the temperature of the flue gas at the flue gas inlet is 70-80 ℃, the pressure is 101.325kpa, the temperature of the flue gas at the flue gas outlet is 30-40 ℃, and the pressure is 96-97 kpa.
Preferably, the mol ratio of the ferrous ammonium sulfate to the ethylene diamine tetraacetic acid to the sodium citrate in the absorption liquid is 1:1: 1.
The invention relates to a liquid-phase flue gas denitration and denitration liquid regeneration integrated device which comprises an absorption liquid preparation unit, a first circulating pump, a third circulating pump, a fourth circulating pump, an absorption tower, an absorption liquid regeneration unit, a first filter and a second circulating pump, wherein the absorption liquid preparation unit is connected with the first circulating pump; the absorption tower is fixedly provided with a first spray pipe, a second spray pipe, a third spray pipe, a packing layer and a second liquid storage tank from top to bottom in sequence, a flue gas inlet pipe is arranged between the packing layer and the second liquid storage tank on one side of the absorption tower, and a flue gas outlet pipe is arranged at the top of the absorption tower; the absorption liquid preparation unit is communicated with the first spray pipe in a pipe mode through the first circulating pump in sequence, the prepared absorption liquid is pumped into the absorption tower and is sprayed through the nozzles on the first spray pipe to react with NO in the flue gas in the absorption tower; the second liquid storage tank is in pipe connection with a third spraying pipe through a third circulating pump, and the incompletely reacted absorption liquid in the second liquid storage tank is pumped into the absorption tower again for recycling, so that the cyclic spraying of the absorption liquid is realized; the second liquid storage tank is connected with the absorption liquid regeneration unit through a fourth circulating pump, and absorption liquid to be regenerated in the second liquid storage tank is pumped into the absorption liquid regeneration unit to realize regeneration; the absorption liquid regeneration unit is connected with the second spraying pipe pipeline sequentially through the first filter and the second circulating pump and used for pumping the regenerated spraying liquid into the absorption tower and regenerating the absorption liquid for use.
The absorption liquid regeneration unit is provided with a plurality of absorption liquid regeneration units, in the process, the fourth circulating pump pumps the absorption liquid to be regenerated into one of the absorption liquid regeneration units for regeneration, and the absorption liquid in the other absorption liquid regeneration unit completing regeneration is pumped into the absorption tower through the first filter and the second circulating pump in sequence, so that continuous operation of denitration and denitration liquid regeneration is realized, and the denitration and denitration liquid regeneration unit is not limited by regeneration time.
Further, the absorption liquid preparation unit comprises a first liquid storage tank, a first water inlet pipe, a first stirrer, a first heating device, a first temperature sensor, a first concentration sensor, a first pH meter and a first liquid level meter, wherein the first water inlet pipe and the second inlet pipe are respectively connected with the first liquid storage tank and are respectively used for inputting raw materials of process water and absorption liquid into the first liquid storage tank, the first stirrer 5 is fixed in the first liquid storage tank, and the first temperature sensor, the first concentration sensor, the first pH meter, the first liquid level meter and the first heating device are fixedly installed in the first liquid storage tank.
Furthermore, the absorption liquid regeneration unit comprises a regeneration liquid storage tank, a regeneration heating device, a regeneration stirrer, a regeneration feeding valve, a regeneration discharging valve, a regeneration liquid level meter, a regeneration temperature sensor, a regeneration concentration sensor and a regeneration feeding device, wherein the regeneration heating device is fixed on the regeneration liquid storage tank, the regeneration stirrer, the regeneration liquid level meter, the regeneration temperature sensor and the regeneration concentration sensor are all fixedly installed in the regeneration liquid storage tank, the regeneration feeding valve is arranged on a feeding pipeline of the regeneration liquid storage tank, the regeneration discharging valve is installed on a discharging pipeline of the regeneration liquid storage tank, and the feeding device is communicated with the regeneration liquid storage tank.
Further, a third liquid level meter and a third concentration sensor are fixedly installed in the second liquid storage tank.
Further, fixedly set up third temperature sensor in absorption tower middle part, set up the defroster at the absorption tower top, the external inlet tube of defroster sets up second inlet tube valve on this inlet tube, connects the fixed mounting drain pump on the fluid-discharge tube of second stock solution tank bottom.
Compared with the prior art, the invention has the following advantages: 1. the concentration ratio of ammonium ferrous sulfate, disodium ethylene diamine tetraacetate and sodium citrate in the solution is determined according to the content of nitric oxide in the flue gas, so that the efficient utilization of the absorbent can be ensured, on one hand, the sodium citrate can be used as a ligand and can also be complexed with ferrous iron to achieve the purpose of absorbing NO, on the other hand, the sodium citrate can play a role of a buffering agent in the solution, the pH value of the solution can be better controlled, the absorption is also favorable, and meanwhile, the sodium citrate is green and environment-friendly and has little harm to the environment. 2. The absorption tower is a countercurrent spray packing absorption tower, the anti-blocking performance is good, the resistance loss is small, and a large gas-liquid contact area can be obtained by adopting a spraying mode, so that high denitration efficiency is obtained; 3. the zinc powder can reduce and regenerate the invalid iron ions in the solution into ferrous ions to play a role continuously, so that the supplement of new solution is reduced, the resource waste is reduced, and the cost is saved.
Description of the drawings:
fig. 1 is a schematic diagram of a main structure principle of a liquid phase flue gas denitration integrated device related by the invention.
In the figure, 1 a first water inlet pipe, 2 a first feed pipe, 3 a first water inlet valve, 4 a first feed pipe valve, 5 a first stirrer, 6 a first liquid storage tank, 7 a first concentration sensor, 8 a first pH meter, 9 a first temperature sensor, 10 a water discharge pump, 11 a first circulation pump, 12 a first spray pipe, 13 a filler layer, 14 a second liquid storage tank, 15 a third circulation pump, 16 a third spray pipe, 17 a third concentration sensor, 18 a fourth circulation pump, 19 a first heating device, 20 a first regeneration feed valve, 21 a first regeneration stirrer, 22 a first regeneration concentration sensor, 23 a first regeneration temperature sensor, 24 a first feeding device, 25 a first regeneration liquid storage tank, 26 a first filter, 27 a second circulation pump, 28 a demister, 29 a second spray pipe, 30 a second regeneration feed valve, 31 a second regeneration concentration sensor, 32, a second regeneration stirrer, 33 a second regeneration liquid storage tank, 3 a first regeneration concentration sensor, 32, 34 a first regeneration discharge valve, 35 a second regeneration discharge valve, 36 a third liquid level meter, 37 a second water inlet pipe valve and 38 a third temperature sensor.
The specific implementation mode is as follows:
the invention is further illustrated by the following examples in conjunction with the accompanying drawings.
The invention relates to an integrated method for liquid-phase flue gas denitration and denitration liquid regeneration, which specifically comprises the following steps:
(1) continuously conveying the flue gas from a flue gas inlet at the middle lower part of the absorption tower into the absorption tower;
(2) preparing absorption liquid, wherein the absorption liquid comprises ammonium ferrous sulfate, disodium ethylene diamine tetraacetate and sodium citrate, the absorption liquid is filtered and sprayed down from the top of the absorption tower, the absorption liquid is in countercurrent contact with the flue gas to react, NO in the flue gas is absorbed, and the reacted absorption liquid falls into a second liquid storage tank at the bottom of the absorption tower;
(3) pumping the absorption liquid falling into the second liquid storage tank into the top of the absorption tower again, spraying the absorption liquid downwards, contacting with the flue gas in a counter-current manner for denitration, and then returning the absorption liquid into the second liquid storage tank;
(4) pumping the absorption liquid (denitration liquid) to be regenerated in the second liquid storage tank into an absorption liquid regeneration unit, adding zinc powder into the regeneration unit, stirring to enable the zinc powder to be completely reacted with ferric ions in the denitration liquid, completing regeneration, finally pumping the regenerated absorption liquid (regeneration liquid) into the top of the absorption tower, spraying down, dropping into the second liquid storage tank again, and repeating the steps;
(5) and (4) continuously absorbing NO in the flue gas, rising to the tower top, and finally discharging through a flue gas outlet after dehumidification treatment.
In the denitration stable operation process of the steps (2) - (4), the temperature in the first liquid storage tank is 45 ℃, the temperature in the third liquid storage tank is 30 ℃, and the temperature in the absorption tower is 50-60 ℃; the temperature of the flue gas at the flue gas inlet is 70-80 ℃, the pressure is 101.325kpa (normal pressure), the temperature of the flue gas at the flue gas outlet is 30-40 ℃, and the pressure is 96-97 kpa.
Preferably, the mol ratio of the ferrous ammonium sulfate to the ethylene diamine tetraacetic acid to the sodium citrate in the absorption liquid is 1:1: 1.
The invention relates to a liquid-phase flue gas denitration and denitration liquid regeneration integrated device, which comprises an absorption liquid preparation unit, a first circulating pump 11, a third circulating pump 15, a fourth circulating pump 18, an absorption tower, an absorption liquid regeneration unit, a first filter 26 and a second circulating pump 27, wherein the absorption liquid preparation unit is connected with the first circulating pump; a first spray pipe 12, a second spray pipe 29, a third spray pipe 16, a packing layer 13 and a second liquid storage tank 14 are fixedly installed on the absorption tower from top to bottom in sequence, a flue gas inlet pipe A is arranged between the packing layer 13 and the second liquid storage tank 14 on one side of the absorption tower, and a flue gas outlet pipe B is arranged on the tower top; the absorption liquid preparation unit is communicated with the first spray pipe 12 in a pipe mode through the first circulating pump 11 in sequence, the prepared absorption liquid is pumped into the absorption tower and is sprayed by the nozzles on the first spray pipe 12 to react with NO in the flue gas in the absorption tower; the second liquid storage tank 14 is in tubular connection with a third spraying pipe 16 through a third circulating pump 15, and the absorption liquid which is not completely reacted in the second liquid storage tank 14 is pumped into the absorption tower again for recycling, so that the cyclic spraying of the absorption liquid is realized; the second liquid storage tank 14 is connected with the absorption liquid regeneration unit through a fourth circulating pump 18, and the absorption liquid to be regenerated in the second liquid storage tank 14 is pumped into the absorption liquid regeneration unit to realize regeneration; the absorption liquid regeneration unit is connected with a second spraying pipe 29 through a first filter 26 and a second circulating pump 27 in sequence, and is used for pumping the regenerated spraying liquid into the absorption tower, and the absorption liquid is used after regeneration.
The absorption liquid regeneration units are a plurality of absorption liquid regeneration units, in the process, the fourth circulating pump 18 pumps the absorption liquid to be regenerated into one of the absorption liquid regeneration units for regeneration, and the absorption liquid in the other absorption liquid regeneration unit completing regeneration is pumped into the absorption tower sequentially through the first filter 26 and the second circulating pump 27, so that continuous operation of denitration and denitration liquid regeneration is realized, and the denitration and denitration liquid regeneration is not limited by regeneration time.
Further, the absorption liquid preparation unit comprises a first liquid storage tank 6, a first water inlet pipe 1, a first inlet pipe 2, a first stirrer 5, a first heating device 19, a first temperature sensor 9, a first concentration sensor 7, a first pH meter 8 and a first liquid level meter, wherein the first water inlet pipe 1 and the second inlet pipe 2 are respectively connected with the first liquid storage tank 6 and are respectively used for inputting process water and absorption liquid raw materials into the first liquid storage tank 6, the first stirrer 5 is fixed in the first liquid storage tank 6, and the first temperature sensor 9, the first concentration sensor 7, the first pH meter 8, the first liquid level meter and the first heating device 19 are fixedly installed in the first liquid storage tank 6.
Furthermore, the absorption liquid regeneration unit comprises a regeneration liquid storage tank, a regeneration heating device, a regeneration stirrer, a regeneration feeding valve, a regeneration discharging valve, a regeneration liquid level meter, a regeneration temperature sensor, a regeneration concentration sensor and a regeneration feeding device, wherein the regeneration heating device is fixed on the regeneration liquid storage tank, the regeneration stirrer, the regeneration liquid level meter, the regeneration temperature sensor and the regeneration concentration sensor are all fixedly installed in the regeneration liquid storage tank, the regeneration feeding valve is arranged on a feeding pipeline of the regeneration liquid storage tank, the regeneration discharging valve is installed on a discharging pipeline of the regeneration liquid storage tank, and the feeding device is communicated with the regeneration liquid storage tank.
Specifically, the absorption liquid regeneration unit according to the present embodiment includes a first absorption liquid regeneration unit and a second absorption liquid regeneration unit, the first absorption liquid regeneration unit includes a first regeneration reservoir 25, a first regeneration heating device, a first regeneration stirrer 21, a first regeneration feed valve 20, a first regeneration discharge valve 34, a first regeneration level meter, a first regeneration temperature sensor 23, a first regeneration concentration sensor 22 and a first feeding device 24, the first regeneration heating device is fixed on the first regeneration reservoir 25, the first regeneration stirrer 21, the first regeneration level meter, the first regeneration temperature sensor 23 and the first regeneration concentration sensor 22 are all fixedly installed in the first regeneration reservoir 25, the first regeneration feed valve 20 is disposed on a feed pipe of the first regeneration reservoir 25, the first regeneration discharge valve 34 is installed on a discharge pipe of the regeneration reservoir, the first feeding device 24 is in communication with the first regeneration reservoir 25. The second absorption liquid regeneration unit has the same structure as the first absorption liquid regeneration unit.
Further, a third liquid level gauge 36 and a third concentration sensor 17 are fixedly installed in the second reservoir 14.
Further, a third temperature sensor 38 is fixedly arranged in the middle of the absorption tower, a demister 28 is arranged at the top of the absorption tower, the demister is externally connected with a water inlet pipe, a second water inlet pipe valve 37 is arranged on the water inlet pipe, and a drainage pump 10 is fixedly arranged on a drainage pipe connected to the bottom of the second liquid storage tank 14.
The specific removal process steps of the liquid-phase flue gas denitration and denitration liquid regeneration integrated device related by the embodiment are as follows:
(1) continuously conveying the flue gas from a flue gas inlet pipe A at the middle lower part of the absorption tower into the absorption tower;
(2) preparing an absorption liquid: firstly, a first water inlet valve 3 and a first feed pipe valve 4 are opened, so that process water and absorption liquid raw materials respectively enter a first liquid storage tank 6 through a first water inlet pipe 1 and a first feed pipe 2, then a first stirrer 5 in the first liquid storage tank is started, so that the absorption liquid raw materials in the first liquid storage tank are diluted and uniformly mixed, a first heating device 19 is used for heating, and a temperature sensor 9, a first concentration sensor 7, a first pH meter 8 and a first liquid level sensor are used for monitoring in real time.
(3) Circularly spraying absorption liquid: when the liquid level in the first liquid storage tank 6 reaches a preset height, a first circulating pump 11 is started, absorption liquid in the first liquid storage tank 6 is sprayed out from a nozzle of a first spray pipe 12 at the top of the absorption tower through the first circulating pump 11 and is in reverse contact with the flue gas in the absorption tower, and NO in the flue gas is absorbed; meanwhile, the liquid level of the second liquid storage tank 14 below the absorption tower is monitored in real time through the third liquid level meter 36, the third circulating pump 15 is started when a certain height is reached, the absorption liquid enters the top of the absorption tower through the third spraying pipe, the absorption liquid is sprayed downwards and undergoes a denitration reaction with rising flue gas, and the absorption liquid returns to the second liquid storage tank 14 again.
(4) Regeneration of circulating liquid: monitoring in real time through the third concentration sensor 17, when the ferrous ion content in the second liquid storage tank 14 reaches a certain concentration, opening the first regeneration feed valve 20, starting the fourth circulating pump 18, allowing the absorption liquid to be regenerated to enter the first regeneration liquid storage tank 25, adding the reducing agent zinc powder in the first feeding device 24 into the first regeneration liquid storage tank 25, heating the first regeneration heating device, and simultaneously opening the first regeneration stirrer 21, the first regeneration concentration sensor 22 and the first regeneration temperature sensor 23 to monitor in real time until regeneration is completed. At this time, after the absorption liquid in the second absorption liquid regeneration unit is regenerated (the content of ferrous ions reaches a set value), the second circulating pump 27 is started, the second regeneration discharge valve 35 is opened, so that the regeneration liquid enters the absorption tower through the second filter 26 and the second spray pipe 29, reversely contacts with the flue gas in the absorption tower, absorbs NO in the flue gas, finally returns to the second reservoir 14, is absorbed by NO in the flue gas through the steps (3) and (4), and then enters the flue gas outlet pipe B through the flue gas outlet after being dehumidified by the demister 28 to be discharged.
(5) Discharging waste liquid: when the density of the absorption liquid in the second liquid storage tank 14 reaches a preset value, the drainage pump 10 is started, and the absorption liquid is discharged.
(6) Cleaning the absorption tower: and finally, opening a second water inlet pipe valve 37 at regular time, and enabling the process water in the water inlet pipe to enter the absorption tower through the second water inlet pipe valve 37 to clean the interior of the demister 28.
According to the invention, ammonium ferrous sulfate, disodium ethylene diamine tetraacetate and sodium citrate are used as the composite solution for flue gas denitration, the moisture content in the treated flue gas is large, the required temperature is low, and the denitrated composite solution can be regenerated and recycled, so that the supplement of a new solution is reduced, the operation cost is reduced, and the removal efficiency is high.
The reaction process in the liquid phase flue gas denitration and denitration liquid regeneration integrated device related to this embodiment is as follows:
(l) The main reaction in the absorption process is as follows:
NO from gas phase to liquid phase:
NO(g)→NO(aq)
the complexing agent absorbs NO:
FeII(L)(aq)+NO(aq)→FeII(L)NO(aq)
Fe(II)(C6H5O7)+NO(aq)→Fe(II)(C6H5O7)NO(aq)
(2) the side reaction in the absorption process is as follows:
2NO+O2→2NO2
2NO+H2O→2H++NO2 -+NO3 -
FeII(L)+NO3 -+2H+→FeII(L)NO+H2O
2FeII(L)NO+FeII(L)+4H+→4FeⅢ(L)+N2+2H2O
FeII(EDTA)+O2→FeII(EDTA)-O2
FeII(EDTA)-O2→FeII(EDTA)+O2 -
O2 -+H+→H2O
FeII(L)+H2O+H+→FeⅢ(L)+H2O2
2FeII(L)++H2O2→2FeⅢ(L)+H2O
FeII(EDTA)-O2+H2→Fe(Ⅲ)EDTA+H2O
Fe(II)(C6H5O7)-NO+O2→Fe(Ⅲ)(C6H5O7)+NO2
Fe2++2OH-→Fe(OH)2
(3) the reduction process equation is:
Zn+2H+→Zn2++H2
2Fe3++H2+OH-→2Fe2++H2O
Fe(Ⅲ)(C6H5O7)+Zn→Fe(II)(C6H5O7)+Zn2+
example 1
The invention relates to an integrated method for liquid-phase flue gas denitration and denitration liquid regeneration, which specifically comprises the following steps:
(1) continuously conveying the flue gas from a flue gas inlet at the middle lower part of the absorption tower into the absorption tower;
(2) preparing an absorption liquid, wherein the mol ratio of ammonium ferrous sulfate to disodium ethylene diamine tetraacetate to sodium citrate in the absorption liquid is 1:1:1, the pH value is 5, the temperature is 45 ℃, the absorption liquid is fully mixed and then sprayed down from the top of an absorption tower, the absorption liquid and the flue gas are in countercurrent contact for reaction, NO in the flue gas is absorbed, and the reacted absorption liquid falls into a second liquid storage tank at the bottom of the absorption tower;
(3) pumping the absorption liquid falling into the second liquid storage tank into the top of the absorption tower again, spraying the absorption liquid downwards, carrying out a denitration reaction by countercurrent contact with the flue gas, then returning the absorption liquid into the second liquid storage tank, and repeating the steps;
(4) pumping the absorption liquid to be regenerated in the second liquid storage tank into an absorption liquid regeneration unit, adding zinc powder into the regeneration unit, stirring to enable the zinc powder to be completely reacted with ferric ions in the denitration liquid, completing regeneration, finally pumping the regenerated absorption liquid (regeneration liquid) into the top of the absorption tower, spraying, dropping into the second liquid storage tank again, and repeating the steps.
(5) And (4) continuously absorbing NO in the flue gas, rising to the tower top, and finally discharging through a flue gas outlet after dehumidification treatment.
In the denitration stable operation process of the steps (2) to (4), the temperature in the first liquid storage tank is 45 ℃, the temperature in the regeneration liquid storage tank is 30 ℃, and the temperature in the absorption tower is 50-60 ℃; the temperature of the flue gas at the flue gas inlet is 70-80 ℃, the pressure is 101.325kpa (normal pressure), the temperature of the flue gas at the flue gas outlet is 30-40 ℃, and the pressure is 96-97 kpa.
The liquid-gas ratio of the flow of the first circulating pump to the flow of the flue gas is 10-12L/m3The liquid-gas ratio of the flow of the second circulating pump to the flow of the flue gas is 5-8L/m3And the flow rates of the first circulating pump, the second circulating pump and the extracting pump are all according to the flow rate of the flue gas and the condition of pollutants in the flue gas.
During stable operation, the NO content at the flue gas inlet is 500mg/m3The denitration efficiency is about 85 percent.
Comparative example 1
The comparative example is the same as the example 1 except that the absorption liquid adopted in the step (2) is different from the example 1, and the molar ratio of ammonium ferrous sulfate, disodium ethylene diamine tetraacetate and sodium citrate in the absorption liquid is 2:1: 2.
During stable operation, the NO content at the flue gas inlet is 500mg/m3The denitration efficiency is about 65%.
Claims (9)
1. A liquid-phase flue gas denitration and denitration liquid regeneration integrated method is characterized by comprising the following steps:
(1) continuously conveying the flue gas from a flue gas inlet at the middle lower part of the absorption tower into the absorption tower;
(2) preparing absorption liquid, wherein the absorption liquid comprises ammonium ferrous sulfate, disodium ethylene diamine tetraacetate and sodium citrate, the absorption liquid is filtered and sprayed down from the top of the absorption tower, the absorption liquid is in countercurrent contact with the flue gas to react, NO in the flue gas is absorbed, and the reacted absorption liquid falls into a second liquid storage tank at the bottom of the absorption tower;
(3) pumping the absorption liquid falling into the second liquid storage tank into the top of the absorption tower again, spraying the absorption liquid downwards, contacting with the flue gas in a counter-current manner for denitration, and then returning the absorption liquid into the second liquid storage tank;
(4) pumping the absorption liquid to be regenerated in the second liquid storage tank into an absorption liquid regeneration unit, adding zinc powder into the regeneration unit, stirring to enable the zinc powder to be completely reacted with ferric ions in the denitration liquid, completing regeneration, finally pumping the regenerated absorption liquid into the top of the absorption tower, spraying, dropping into the second liquid storage tank again, and repeating the steps;
(5) and (4) continuously absorbing NO in the flue gas, rising to the tower top, and finally discharging through a flue gas outlet after dehumidification treatment.
2. The integrated method for liquid-phase flue gas denitration and denitration liquid regeneration of claim 1, wherein in the denitration stable operation process of the steps (2) to (4), the temperature in the first liquid storage tank is 45 ℃, the temperature in the third liquid storage tank is 30 ℃, and the temperature in the absorption tower is 50-60 ℃; the temperature of the flue gas at the flue gas inlet is 70-80 ℃, the pressure is 101.325kpa, the temperature of the flue gas at the flue gas outlet is 30-40 ℃, and the pressure is 96-97 kpa.
3. The liquid-phase flue gas denitration and denitration liquid regeneration integrated method of claim 2, wherein the molar ratio of ammonium ferrous sulfate, disodium ethylene diamine tetraacetate and sodium citrate in the absorption liquid is 1:1: 1.
4. A liquid-phase flue gas denitration and denitration liquid regeneration integrated device is characterized by comprising an absorption liquid preparation unit, a first circulating pump, a third circulating pump, a fourth circulating pump, an absorption tower, an absorption liquid regeneration unit, a first filter and a second circulating pump; the absorption tower is fixedly provided with a first spray pipe, a second spray pipe, a third spray pipe, a packing layer and a second liquid storage tank from top to bottom in sequence, a flue gas inlet pipe is arranged between the packing layer and the second liquid storage tank on one side of the absorption tower, and a flue gas outlet pipe is arranged at the top of the absorption tower; the absorption liquid preparation unit is communicated with the first spray pipe in a pipe mode through the first circulating pump in sequence, the prepared absorption liquid is pumped into the absorption tower and is sprayed through the nozzles on the first spray pipe to react with NO in the flue gas in the absorption tower; the second liquid storage tank is in pipe connection with a third spraying pipe through a third circulating pump, and the incompletely reacted absorption liquid in the second liquid storage tank is pumped into the absorption tower again for recycling, so that the cyclic spraying of the absorption liquid is realized; the second liquid storage tank is connected with the absorption liquid regeneration unit through a fourth circulating pump, and absorption liquid to be regenerated in the second liquid storage tank is pumped into the absorption liquid regeneration unit to realize regeneration; the absorption liquid regeneration unit is connected with the second spraying pipe pipeline sequentially through the first filter and the second circulating pump and used for pumping the regenerated spraying liquid into the absorption tower and regenerating the absorption liquid for use.
5. The liquid-phase flue gas denitration and denitration liquid regeneration integrated device of claim 4, wherein the number of the absorption liquid regeneration units is several, in the process, a fourth circulation pump pumps the absorption liquid to be regenerated into one of the absorption liquid regeneration units for regeneration, and the absorption liquid in the other absorption liquid regeneration unit completing regeneration is pumped into the absorption tower through the first filter and the second circulation pump in sequence.
6. The liquid-phase flue gas denitration and denitration liquid regeneration integrated device of claim 5, wherein the absorption liquid preparation unit comprises a first liquid storage tank, a first water inlet pipe, a first feed pipe, a first stirrer, a first heating device, a first temperature sensor, a first concentration sensor, a first pH meter and a first liquid level meter, the first water inlet pipe and the second feed pipe are respectively connected with the first liquid storage tank and are respectively used for inputting process water and raw materials of the absorption liquid into the first liquid storage tank, the first stirrer 5 is fixed in the first liquid storage tank, and the first temperature sensor, the first concentration sensor, the first pH meter, the first liquid level meter and the first heating device are fixedly installed in the first liquid storage tank.
7. The liquid-phase flue gas denitration and denitration liquid regeneration integrated device of claim 6, wherein the absorption liquid regeneration unit comprises a regeneration liquid storage tank, a regeneration heating device, a regeneration stirrer, a regeneration feed valve, a regeneration discharge valve, a regeneration liquid level meter, a regeneration temperature sensor, a regeneration concentration sensor and a regeneration feeding device, wherein the regeneration heating device is fixed on the regeneration liquid storage tank, the regeneration stirrer, the regeneration liquid level meter, the regeneration temperature sensor and the regeneration concentration sensor are all fixedly arranged in the regeneration liquid storage tank, the regeneration feed valve is arranged on a feed pipeline of the regeneration liquid storage tank, the regeneration discharge valve is arranged on a discharge pipeline of the regeneration liquid storage tank, and the feeding device is communicated with the regeneration liquid storage tank.
8. The liquid-phase flue gas denitration and denitration liquid regeneration integrated device of claim 7, wherein a third liquid level meter and a third concentration sensor are fixedly installed in the second liquid storage tank.
9. The integrated device for liquid-phase flue gas denitration and denitration liquid regeneration of claim 7, wherein a third temperature sensor is fixedly arranged in the middle of the absorption tower, a demister is arranged on the top of the absorption tower and externally connected with a water inlet pipe, a second water inlet pipe valve is arranged on the water inlet pipe, and a drain pump is fixedly arranged on a drain pipe connected to the bottom of the second liquid storage tank.
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