CN110665336A - Liquid-phase flue gas denitration and absorption liquid regeneration integrated method and device - Google Patents

Abstract

The invention discloses an integrated method for liquid-phase flue gas denitration and denitration liquid regeneration. First, the flue gas is continuously transported into the absorption tower from the flue gas inlet in the middle and lower part of the absorption tower; then the absorption liquid is arranged, and after the absorption liquid is filtered, It is sprayed down from the top of the absorption tower to absorb NO in the flue gas, and the reacted absorption liquid falls into the second liquid storage tank at the bottom of the absorption tower; then the absorption liquid in the second liquid storage tank is pumped into the absorption tower again The top is sprayed down, and is in countercurrent contact with the flue gas for denitrification; the absorption liquid that needs to be regenerated in the second liquid storage tank is pumped into the absorption liquid regeneration unit, and zinc powder is added to the regeneration unit. The ferric ions are completely reacted to complete the regeneration. Finally, the regenerated absorption liquid is pumped into the top of the absorption tower, sprayed down, and falls into the second liquid storage tank again, and the process is repeated; emission. The method can effectively remove NO in the flue gas and regenerate the absorption liquid at the same time.

Description

An integrated method and device for liquid-phase flue gas denitrification and absorption liquid regeneration

Technical field:

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 mixed absorption system denitration and zinc powder reduction regeneration absorption liquid, which is suitable for industrial high-moisture flue gas denitration occasions.

Background technique:

With the rapid development of modern economy, the rapid development of industry has also caused a series of problems. The burning of fossil fuels causes air pollution. Sulfides, nitrogen oxides and dust particles have a relatively large impact on the environment. Among them, nitrogen oxides and sulfides are the pollutants with relatively large emissions. Sulfide and nitrogen oxides not only have an impact on the environment but also pose a threat to human health, such as forming acid rain with other compounds, corroding buildings, affecting the normal growth of plants, and producing chemical smog that affects human daily life. After years of unremitting efforts, a relatively mature process has been formed in the treatment of sulfides, but there are still some problems in the treatment of nitrogen oxides. The control methods of nitrogen oxides are divided into dry denitrification and wet denitration. Currently, the most commonly used dry denitration is selective catalytic reduction (SCR), which involves the reaction of _NH3 with NO to generate _N2 and _H2O . While this approach is highly efficient, it has some drawbacks. For example, the high temperatures required for the catalytic process and other components in the flue gas can adversely affect the activity of the catalyst, which means that the life of the catalyst will be shortened. In particular, the flue gas discharged from some smelters and some industrial boilers has a relatively large moisture content, and the SCR treatment device does not have any advantages in this regard. Therefore, there is a great need for a denitrification method for processing high-moisture flue gas. Complex denitrification is one of the effective methods of liquid denitrification, and it has received widespread attention because of its high efficiency and low temperature. Not only that, complex denitrification also has obvious advantages for the treatment of high-moisture flue gas. The so-called complex denitration is to use transition metal ions (such as cd ²⁺ , Fe ²⁺ , Co ^{2 +} , Ni ⁺ ) and aminocarboxylic acid ligands (EDTA) or sulfur-based ligands to form complexes, and then finally It reacts rapidly with NO to form metal nitrosyl compounds, increases its solubility in water, and achieves the purpose of removing nitrogen oxides. For example, patent CN105032152B discloses a process for synchronous flue gas desulfurization and denitrification with chemical absorption combined with microbial fuel cells, which adopts ferrous complexing agent (II) (L) in the denitration absorption tower to absorb NO, Fe (II) EDTA in the flue gas The reaction with NO is (taking EDTA as an example): Fe(II)EDTA+NO→Fe(II)EDTA NO. During the process, since ferrous ions are easily oxidized to ferric ions, some adsorbents Fe(II) Both EDTA and the adsorbed product Fe(II)EDTA NO are oxidized. In order to realize the recycling of the absorbent, Fe(III)EDTA and Fe(III)EDTA NO are generally reduced. In this patent, ultrasonic transducers are used to strengthen sulfuric acid. Root reduction regenerates the complexed iron ions, accelerating the reduction reaction rate. The invention solves the problem of cyclic regeneration of the absorption liquid in the complex denitration process from another aspect.

Invention content:

The purpose of the present invention is to overcome the disadvantage of low efficiency of dry denitration treatment of high-moisture flue gas, and to find and design a low-temperature high-efficiency liquid phase integrated denitration method and device. A composite solution is prepared by using ferrous ammonium sulfate, disodium EDTA and sodium citrate in a certain proportion. The obtained solution has the ability to absorb nitric oxide. At the same time, zinc powder is used as a reducing agent to reduce the absorbed nitric oxide. For nitrogen and some ammonium salts, the oxidized ferric iron can also be reduced to ferrous iron to continue to function, and the device includes a spray process and a reduction process.

In order to achieve the above object, the present invention adopts the following technical solutions:

The invention relates to an integrated method for liquid-phase flue gas denitrification and denitrification liquid regeneration, which specifically includes the following steps:

(1) The flue gas is continuously transported into the absorption tower from the flue gas inlet in the middle and lower part of the absorption tower;

(2) Configure an absorption liquid, which includes ferrous ammonium sulfate, disodium EDTA and sodium citrate. After the absorption liquid is filtered, it is sprayed down from the top of the absorption tower, and the absorption liquid is countercurrent to the flue gas. Contact and react to absorb NO in the flue gas, and the reacted absorption liquid falls into the second liquid storage tank at the bottom of the absorption tower;

(3) the absorption liquid that falls in the second liquid storage tank is pumped into the top of the absorption tower again, sprayed down, contacts with flue gas countercurrently to carry out denitrification, and then returns to the second liquid storage tank;

(4) pump the absorbing liquid that needs to be regenerated in the second liquid storage tank into the absorbing liquid regeneration unit, add zinc powder to the regeneration unit, stir to make it completely react with the ferric ions in the denitration liquid, complete the regeneration, and finally put the The regenerated absorption liquid is pumped into the top of the absorption tower, sprayed down, and falls into the second liquid storage tank again, and so on;

(5) Through steps (2)-(4), NO in the flue gas is continuously absorbed, rises to the top of the tower, and finally is discharged through the flue gas outlet after dehumidification treatment.

During the stable operation of steps (2)-(4), the temperature in the first liquid storage tank is 45°C, the temperature in the third liquid storage tank is 30°C, and the temperature inside the absorption tower is 50-60°C; The temperature at the inlet of the flue gas is 70-80°C, and the pressure is 101.325kpa, and the temperature of the flue gas at the outlet of the flue gas is 30-40°C, and the pressure is 96-97kpa.

Preferably, the molar ratio of ferrous ammonium sulfate, disodium EDTA and sodium citrate in the absorption solution is 1:1:1.

The invention relates to an integrated device for liquid-phase flue gas denitration and denitrification liquid regeneration, comprising an absorption liquid preparation unit, a first circulation pump, a third circulation pump, a fourth circulation pump, an absorption tower, an absorption liquid regeneration unit, a first circulation pump The filter and the second circulating pump; the absorption tower is fixedly installed with the first spray pipe, the second spray pipe, the third spray pipe, the packing layer and the second liquid storage tank in sequence from top to bottom. A flue gas inlet pipe is arranged between the packing layer and the second liquid storage tank, and a flue gas outlet pipe is arranged at the top of the tower; the absorption liquid preparation unit is connected with the first spray pipe through the first circulation pump in sequence, and the prepared absorption liquid is connected with the first spray pipe in turn. The liquid is pumped into the absorption tower and sprayed down 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 connected to the third spray pipe through the third circulation pump. , the incompletely reacted absorption liquid in the second liquid storage tank is pumped into the absorption tower again, and recycled to realize the circulating spray of the absorption liquid; the second liquid storage tank is connected with the absorption liquid regeneration unit through the fourth circulation pump, and the The absorption liquid that needs to be regenerated in the second liquid storage tank is pumped into the absorption liquid regeneration unit to realize regeneration; The last spray liquid is pumped into the absorption tower, and the absorption liquid is used after regeneration.

There are several absorbing liquid regeneration units. During the process, the fourth circulating pump pumps the absorbing liquid that needs to be regenerated into one of the absorbing liquid regeneration units for regeneration, and the absorbing liquid in the other absorbing liquid regeneration unit that has completed regeneration passes through the first one in turn. A filter and a second circulating pump are pumped into the absorption tower to realize the continuous operation of denitrification and denitrification liquid regeneration, which is not limited by the regeneration time.

Further, the absorption liquid preparation unit includes 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 sensor The first liquid level gauge, the first water inlet pipe and the second feed pipe are respectively connected to the first liquid storage tank, and are used to input process water and absorption liquid raw materials into the first liquid storage tank respectively. The first agitator 5 It 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.

Further, the absorbing liquid regeneration unit includes a regeneration liquid storage tank, a regeneration heating device, a regeneration agitator, a regeneration feed valve, a regeneration discharge valve, a regeneration liquid level gauge, a regeneration temperature sensor, a regeneration concentration sensor and a regeneration feeding device, The regeneration heating device is fixed on the regeneration storage tank. The regeneration agitator, regeneration level gauge, regeneration temperature sensor and regeneration concentration sensor are all fixedly installed in the regeneration storage tank. The regeneration feed valve is placed in the feed of the regeneration storage tank. On the pipeline, the regeneration discharge valve is installed on the discharge pipeline of the regeneration liquid storage tank, and the feeding device is communicated with the regeneration liquid storage tank.

Further, a third liquid level gauge and a third concentration sensor are fixedly installed in the second liquid storage tank.

Further, a third temperature sensor is fixedly arranged in the middle of the absorption tower, a mist eliminator is arranged at the top of the absorption tower, the mist eliminator is externally connected to a water inlet pipe, a second water inlet pipe valve is arranged on the water inlet pipe, and is connected to the bottom of the second liquid storage tank. The drain pump is fixedly installed on the drain pipe.

Compared with the prior art, the present invention has the following advantages: 1. determine the concentration ratio of ferrous ammonium sulfate, disodium EDTA, and sodium citrate in the solution according to the content of nitric oxide in the flue gas, ensuring that The absorbent can be used efficiently. On the one hand, as a ligand, sodium citrate can also be complexed with ferrous iron to achieve the purpose of absorbing NO. The acidity and alkalinity of the solution are well controlled, which is also beneficial to absorption, and at the same time, sodium citrate is green and environmentally friendly, with little harm to the environment. 2. The absorption tower is a counter-current spray packing absorption tower, which has good anti-blocking performance and small resistance loss. The spray method can obtain a larger gas-liquid contact area, thereby obtaining a higher denitration efficiency; 3. Zinc powder can be dissolved in the solution. Ineffective iron ions are reduced and regenerated for divalent iron ions to continue to play a role, reducing the replenishment of new solutions, reducing waste of resources and saving costs.

Description of drawings:

FIG. 1 is a schematic diagram of the main structure principle of the liquid-phase flue gas denitrification integrated device involved in the present invention.

In the figure, 1. the first water inlet pipe, 2. the first feeding pipe, 3. the first water inlet valve, 4. the first feeding pipe valve, 5. the first agitator, 6. the first liquid storage tank, 7. the first concentration sensor, 8 The first pH meter, 9 The first temperature sensor, 10 The drain pump, 11 The first circulation pump, 12 The first spray pipe, 13 The packing layer, 14 The second liquid storage tank, 15 The third circulation pump, 16 The third spray Shower pipe, 17 third concentration sensor, 18 fourth circulation pump, 19 first heating device, 20 first regeneration feed valve, 21 first regeneration agitator, 22 first regeneration concentration sensor, 23 first regeneration temperature sensor, 24 The first feeding device, 25 The first regeneration tank, 26 The first filter, 27 The second circulation pump, 28 The mist eliminator, 29 The second spray pipe, 30 The second regeneration feed valve, 31 The second regeneration Concentration sensor, 32, second regeneration agitator, 33 second regeneration liquid storage tank, 34 first regeneration discharge valve, 35 second regeneration discharge valve, 36 third liquid level gauge, 37 second water inlet pipe valve, 38 The third temperature sensor.

Detailed ways:

The present invention will be further described below through embodiments and in conjunction with the accompanying drawings.

The invention relates to an integrated method for liquid-phase flue gas denitrification and denitrification liquid regeneration, which specifically includes the following steps:

(1) The flue gas is continuously transported into the absorption tower from the flue gas inlet in the middle and lower part of the absorption tower;

(2) Configure an absorption liquid, which includes ferrous ammonium sulfate, disodium EDTA and sodium citrate. After the absorption liquid is filtered, it is sprayed down from the top of the absorption tower, and the absorption liquid is countercurrent to the flue gas. Contact and react to absorb NO in the flue gas, and the reacted absorption liquid falls into the second liquid storage tank at the bottom of the absorption tower;

(3) the absorption liquid that falls in the second liquid storage tank is pumped into the top of the absorption tower again, sprayed down, contacts with flue gas countercurrently to carry out denitrification, and then returns to the second liquid storage tank;

(4) pump the absorption liquid (denitrification liquid) that needs to be regenerated in the second liquid storage tank into the absorption liquid regeneration unit, add zinc powder to the regeneration unit, stir to make it completely react with the ferric ions in the denitration liquid, and complete Regenerate, and finally pump the regenerated absorption liquid (regeneration liquid) into the top of the absorption tower, spray down, and fall into the second liquid storage tank again, repeating like this;

(5) Through steps (2)-(4), NO in the flue gas is continuously absorbed, rises to the top of the tower, and finally is discharged through the flue gas outlet after dehumidification treatment.

During the stable operation of steps (2)-(4), the temperature in the first liquid storage tank is 45°C, the temperature in the third liquid storage tank is 30°C, and the temperature inside the absorption tower is 50-60°C; The temperature at the inlet of the flue gas is 70-80°C, the pressure is 101.325kpa (normal pressure), the temperature of the flue gas at the outlet of the flue gas is 30-40°C, and the pressure is 96-97kpa.

Preferably, the molar ratio of ferrous ammonium sulfate, disodium EDTA and sodium citrate in the absorption solution is 1:1:1.

The present invention relates to an integrated device for liquid-phase flue gas denitration and denitrification liquid regeneration, comprising an absorption liquid preparation unit, a first circulating pump 11, a third circulating pump 15, a fourth circulating pump 18, an absorption tower, and an absorption liquid regeneration unit , the first filter 26 and the second circulating pump 27; the first spray pipe 12, the second spray pipe 29, the third spray pipe 16, the packing layer 13 and the second reservoir are fixedly installed in the absorption tower from top to bottom. Liquid tank 14, a flue gas inlet pipe A is set between the packing layer 13 on one side of the absorption tower and the second liquid storage tank 14, and a flue gas outlet pipe B is set at the top of the tower; the absorption liquid preparation unit passes through the first circulating pump 11 in turn It is in tubular communication with the first spray pipe 12, and the prepared absorption liquid is pumped into the absorption tower, and sprayed down through the nozzle on the first spray pipe 12 to react with NO in the flue gas in the absorption tower; the second The liquid storage tank 14 is connected with the third spray pipe 16 through the third circulation pump 15, and the incompletely reacted absorption liquid in the second liquid storage tank 14 is pumped into the absorption tower again, and the circulation of the absorption liquid is realized. spraying; the second liquid storage tank 14 is connected to the absorption liquid regeneration unit through the fourth circulation pump 18, and the absorption liquid that needs 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 It is connected to the second spray pipe 29 through the first filter 26 and the second circulation pump 27 in sequence, and is used for pumping the regenerated spray liquid into the absorption tower, and the absorption liquid is used after regeneration.

There are several absorbing liquid regeneration units. During the process, the fourth circulating pump 18 pumps the absorbing liquid to be regenerated into one of the absorbing liquid regeneration units for regeneration, and the absorbing liquid in the other absorbing liquid regeneration unit that has completed the regeneration passes through in turn. The first filter 26 and the second circulating pump 27 are pumped into the absorption tower to realize the continuous operation of denitrification and denitrification liquid regeneration, which is not limited by the regeneration time.

Further, the absorption liquid preparation unit includes a first liquid storage tank 6, a first water inlet pipe 1, a first feed pipe 2, a first stirrer 5, a first heating device 19, a first temperature sensor 9, a first The concentration sensor 7, the first pH meter 8 and the first liquid level meter, the first water inlet pipe 1 and the second feed pipe 2 are respectively connected to the first liquid storage tank 6, and are used to input the process water and the raw material of the absorption liquid into the first liquid storage tank 6 respectively. In a 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 level gauge and the first heating device 19 .

Further, the absorbing liquid regeneration unit includes a regeneration liquid storage tank, a regeneration heating device, a regeneration agitator, a regeneration feed valve, a regeneration discharge valve, a regeneration liquid level gauge, a regeneration temperature sensor, a regeneration concentration sensor and a regeneration feeding device, The regeneration heating device is fixed on the regeneration storage tank. The regeneration agitator, regeneration level gauge, regeneration temperature sensor and regeneration concentration sensor are all fixedly installed in the regeneration storage tank. The regeneration feed valve is placed in the feed of the regeneration storage tank. On the pipeline, the regeneration discharge valve is installed on the discharge 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 involved in this embodiment includes a first absorption liquid regeneration unit and a second absorption liquid regeneration unit, and the first absorption liquid regeneration unit includes a first regeneration liquid storage tank 25, a first regeneration heating device, a first regeneration heating device, and a The regeneration agitator 21, the first regeneration feed valve 20, the first regeneration discharge valve 34, the first regeneration liquid level gauge, the first regeneration temperature sensor 23, the first regeneration concentration sensor 22 and the first feeding device 24, in the first A first regeneration heating device is fixed on a regeneration liquid storage tank 25, and the first regeneration agitator 21, the first regeneration liquid level gauge, the first regeneration temperature sensor 23, and the first regeneration concentration sensor 22 are all fixedly installed in the first regeneration storage liquid. In the tank 25, the first regeneration feed valve 20 is placed on the feed pipe of the first regeneration liquid storage tank 25, the first regeneration discharge valve 34 is installed on the discharge pipe of the regeneration liquid storage tank, and the first feeding device 24 It communicates with the first regeneration liquid storage tank 25 . The second absorbing liquid regeneration unit has the same structure as the first absorbing liquid regeneration unit.

Further, a third liquid level gauge 36 and a third concentration sensor 17 are fixedly installed in the second liquid storage tank 14 .

Further, a third temperature sensor 38 is fixedly arranged in the middle of the absorption tower, a mist eliminator 28 is arranged at the top of the absorption tower, the mist eliminator is externally connected to a water inlet pipe, and a second water inlet pipe valve 37 is arranged on the water inlet pipe, which is connected to the second storage tank. The drain pump 10 is fixedly installed on the drain pipe at the bottom of the liquid tank 14 .

The specific removal process steps of the integrated device for liquid-phase flue gas denitrification and denitrification liquid regeneration involved in this embodiment are:

(1) the flue gas is continuously transported into the absorption tower from the flue gas inlet pipe A in the lower part of the absorption tower;

(2) Preparation of absorbing liquid: first open the first water inlet valve 3 and the first feeding pipe valve 4, so that the process water and the raw material of the absorbing liquid enter the first liquid storage through the first water feeding pipe 1 and the first feeding pipe 2 respectively In tank 6, then turn on the first stirrer 5 in the first liquid storage tank, so that the raw materials of the absorption liquid in the first liquid storage tank are diluted and mixed evenly, the first heating device 19 is heated, the temperature sensor 9, the first The concentration sensor 7, the first pH meter 8, and the first liquid level sensor perform real-time monitoring.

(3) Circulation spraying of absorption liquid: when the liquid level in the first liquid storage tank 6 reaches a predetermined height, the first circulation pump 11 is turned on, and the absorption liquid in the first liquid storage tank 6 passes through the first circulation pump 11, from the absorption It is sprayed from the nozzle of the first spray pipe 12 at the top of the tower, and is in reverse contact with the flue gas in the absorption tower to absorb NO in the flue gas; at the same time, the liquid level of the second liquid storage tank 14 below the absorption tower passes through the third liquid level The meter 36 is monitored in real time. When a certain height is reached, the third circulating pump 15 is turned on, and the absorption liquid enters the top of the absorption tower through the third spray pipe, sprays down, and performs denitration reaction with the rising flue gas, and the absorption liquid returns to the first Two liquid storage tanks 14 .

(4) Regeneration of circulating liquid: real-time monitoring by the third concentration sensor 17, when the content of ferrous ions in the second liquid storage tank 14 reaches a certain concentration, open the first regeneration feed valve 20 and open the fourth circulating pump 18, so that regeneration is required The absorbing liquid enters the first regeneration liquid storage tank 25, the reducing agent zinc powder in the first feeding device 24 is added into the first regeneration liquid storage tank 25, the first regeneration heating device is heated, and the first regeneration mixer 21 is turned on at the same time. , the first regeneration concentration sensor 22 and the first regeneration temperature sensor 23 perform real-time monitoring until the regeneration is completed. At this time, the absorption liquid in the second absorption liquid regeneration unit has been regenerated (the ferrous ion content reaches the set value), the second circulation pump 27 is turned on, and the second regeneration discharge valve 35 is opened, so that the regeneration liquid passes through the second filter The device 26 and the second spray pipe 29 enter the absorption tower, contact with the flue gas in the absorption tower in a reverse direction, absorb NO in the flue gas, and finally return to the second liquid storage tank 14. After steps (3) and (4), the smoke The NO in the gas is absorbed, and then dehumidified by the demister 28 and then discharged into the flue gas outlet pipe B through the flue gas outlet.

(5) Discharge of waste liquid: when the density of the absorption liquid in the second liquid storage tank 14 reaches a predetermined value, the drainage pump 10 is turned on to discharge the absorption liquid.

(6) Cleaning the absorption tower: Finally, the second water inlet pipe valve 37 is opened regularly, and the process water in the water inlet pipe enters the absorption tower through the second water inlet pipe valve 37 to clean the inside of the mist eliminator 28.

The present invention adopts ferrous ammonium sulfate, disodium EDTA, and sodium citrate as composite solutions for denitrification of flue gas. For regeneration and recycling, the replenishment of new solution is reduced, the operating cost is reduced, and the removal efficiency is high.

The reaction process in the integrated device for liquid-phase flue gas denitrification and denitrification liquid regeneration involved in this embodiment is as follows:

(1) The main reaction in the absorption process is:

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)(C ₆ H ₅ O ₇ )+NO(aq)→Fe(II)(C ₆ H ₅ O ₇ )NO(aq)

(2) The side reactions in the absorption process are:

2NO+O ₂ →2NO ₂

2NO+H ₂ O→2H ⁺ +NO ₂ ^- +NO ₃ ^-

FeII(L)+NO ₃ ^- +2H ⁺ →FeII(L)NO+H ₂ O

2FeII(L)NO+FeII(L)+4H ⁺ →4FeIII(L)+N ₂ +2H ₂ O

FeII(EDTA)+O ₂ →FeII(EDTA)-O ₂

FeII(EDTA)-O ₂ →FeII(EDTA)+O ₂ ^-

O ₂ ^- +H ⁺ →H ₂ O

FeII(L)+H ₂ O+H ⁺ →FeIII(L)+H ₂ O ₂

2FeII(L)++H ₂ O ₂ →2FeIII(L)+H ₂ O

FeII(EDTA)-O ₂ +H ₂ →Fe(Ⅲ)EDTA+H ₂ O

Fe(II)(C ₆ H ₅ O ₇ )-NO+O ₂ →Fe(III)(C ₆ H ₅ O ₇ )+NO ₂

Fe ²⁺ +2OH ^- →Fe(OH) ₂

(3) The reduction process equation is:

Zn+2H ⁺ →Zn ²⁺ +H ₂

2Fe ³⁺ +H ₂ +OH ^- →2Fe ²⁺ +H ₂ O

Fe(III)(C ₆ H ₅ O ₇ )+Zn→Fe(II)(C ₆ H ₅ O ₇ )+Zn ²⁺

Example 1

The invention relates to an integrated method for liquid-phase flue gas denitrification and denitrification liquid regeneration, which specifically includes the following steps:

(1) The flue gas is continuously transported into the absorption tower from the flue gas inlet in the middle and lower part of the absorption tower;

(2) configure an absorption liquid, the molar ratio of ferrous ammonium sulfate, disodium EDTA and sodium citrate in the absorption liquid is 1:1:1, pH=5, and the temperature is 45°C. After mixing, it is sprayed down from the top of the absorption tower, and the absorbing liquid reacts with the flue gas in countercurrent contact, absorbing NO in the flue gas, and the reacted absorbing liquid falls into the second liquid storage tank at the bottom of the absorption tower;

(3) the absorption liquid that falls in the second liquid storage tank is pumped into the top of the absorption tower again, sprayed down, and the countercurrent contact with the flue gas carries out denitration reaction, and then returns to the second liquid storage tank, repeating like this;

(4) pump the absorbing liquid that needs to be regenerated in the second liquid storage tank into the absorbing liquid regeneration unit, add zinc powder to the regeneration unit, stir to make it completely react with the ferric ions in the denitration liquid, complete the regeneration, and finally put the The regenerated absorption liquid (regenerated liquid) is pumped into the top of the absorption tower, sprayed down, and falls into the second liquid storage tank again, and so on.

(5) Through steps (2)-(4), NO in the flue gas is continuously absorbed, rises to the top of the tower, and finally is discharged through the flue gas outlet after dehumidification treatment.

During the stable operation of steps (2)-(4), the temperature in the first liquid storage tank is 45 °C, the temperature in the regeneration liquid storage tank is 30 °C, and the temperature inside the absorption tower is 50-60 °C; The temperature at the inlet of the flue gas is 70-80°C, the pressure is 101.325kpa (normal pressure), the temperature of the flue gas at the outlet of the flue gas is 30-40°C, and the pressure is 96-97kpa.

The liquid-gas ratio of the flow rate of the first circulating pump to the flow rate of flue gas is 10-12L/m ³ , and the liquid-gas ratio of the flow rate of the second circulating pump to the flow rate of flue gas is 5-8L/m ³ . The flow of the pump and extraction pump is based on the flue gas flow and the pollutants in the flue gas.

During stable operation, the NO content at the inlet of the flue gas is 500 mg/m ³ , and the out-of-stock efficiency is about 85%.

Comparative Example 1

Except that the absorption solution adopted in step (2) is different from Example 1, other steps are the same, and the molar ratio of ferrous ammonium sulfate, disodium EDTA and sodium citrate in the absorption solution is 2:1 :2.

During stable operation, the NO content at the inlet of the flue gas is 500 mg/m ³ , and the out-of-stock efficiency is about 65%.

Claims (9)

1. a liquid-phase flue gas denitration and denitration liquid regeneration integrated method, is characterized in that, specifically comprises the following steps: (1) The flue gas is continuously transported into the absorption tower from the flue gas inlet in the middle and lower part of the absorption tower; (2) Configure an absorption liquid, which includes ferrous ammonium sulfate, disodium EDTA and sodium citrate. After the absorption liquid is filtered, it is sprayed down from the top of the absorption tower, and the absorption liquid is countercurrent to the flue gas. Contact and react to absorb NO in the flue gas, and the reacted absorption liquid falls into the second liquid storage tank at the bottom of the absorption tower; (3) the absorption liquid that falls in the second liquid storage tank is pumped into the top of the absorption tower again, sprayed down, contacts with flue gas countercurrently to carry out denitrification, and then returns to the second liquid storage tank; (4) pump the absorbing liquid that needs to be regenerated in the second liquid storage tank into the absorbing liquid regeneration unit, add zinc powder to the regeneration unit, stir to make it completely react with the ferric ions in the denitration liquid, complete the regeneration, and finally put the The regenerated absorption liquid is pumped into the top of the absorption tower, sprayed down, and falls into the second liquid storage tank again, and so on; (5) Through steps (2)-(4), NO in the flue gas is continuously absorbed, rises to the top of the tower, and finally is discharged through the flue gas outlet after dehumidification treatment. 2. The integrated method for liquid-phase flue gas denitration and denitration liquid regeneration according to claim 1, characterized in that, in the stable operation process of step (2)-(4) denitration, the temperature in the first liquid storage tank is 45 ℃ ℃, the temperature in the third liquid storage tank is 30℃, the temperature inside 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 flue gas is at the flue gas outlet The temperature is 30-40℃, and the pressure is 96-97kpa. 3. The integrated method for liquid-phase flue gas denitration and denitrification liquid regeneration according to claim 2, wherein the mol ratio of ferrous ammonium sulfate, disodium EDTA and sodium citrate in the absorption liquid 1:1:1. 4. An integrated device for liquid-phase flue gas denitration and denitration liquid regeneration, characterized in that it comprises an absorption liquid preparation unit, a first circulation pump, a third circulation pump, a fourth circulation pump, an absorption tower, an absorption liquid regeneration unit, The first filter and the second circulating pump; the first spray pipe, the second spray pipe, the third spray pipe, the packing layer and the second liquid storage tank are fixedly installed in the absorption tower from top to bottom. A flue gas inlet pipe is arranged between the packing layer on the side and the second liquid storage tank, and a flue gas outlet pipe is arranged at the top of the tower; The absorption liquid is pumped into the absorption tower, and sprayed down through the nozzle on the first spray pipe to react with NO in the flue gas in the absorption tower; the second liquid storage tank is connected to the third spray pipe through the third circulation pump The second liquid storage tank is connected with the absorption liquid regeneration unit through the fourth circulation pump, and the incompletely reacted absorption liquid in the second liquid storage tank is pumped into the absorption tower again and used for recycling to realize the circulating spray of the absorption liquid. , pump the absorbing liquid that needs to be regenerated in the second liquid storage tank into the absorbing liquid regeneration unit to realize regeneration; The regenerated spray liquid is pumped into the absorption tower, and the absorption liquid is used after regeneration. 5. The integrated device for liquid-phase flue gas denitrification and denitrification liquid regeneration according to claim 4, characterized in that, there are several absorbing liquid regeneration units, and the fourth circulating pump pumps the absorbing liquid that needs to be regenerated in the process. One of the absorbing liquid regeneration units is regenerated, and the absorbing liquid in the other absorbing liquid regeneration unit that has completed regeneration is pumped into the absorption tower through the first filter and the second circulating pump in turn. 6 . The integrated device for liquid-phase flue gas denitrification and denitrification liquid regeneration according to claim 5 , wherein the absorption liquid preparation unit comprises a first liquid storage tank, a first water inlet pipe, a first feed pipe, The first agitator, the first heating device, the first temperature sensor, the first concentration sensor, the first pH meter and the first liquid level meter, the first water inlet pipe and the second feed pipe are respectively connected with the first liquid storage tank, They are respectively used to input process water and absorbing liquid raw materials into the first liquid storage tank. The first agitator 5 is fixed in the first liquid storage tank, and the first temperature sensor and the first concentration sensor are fixedly installed in the first liquid storage tank. , the first pH meter, the first liquid level meter and the first heating device. 7 . The integrated device for liquid-phase flue gas denitration and denitrification liquid regeneration according to claim 6 , wherein the absorbing liquid regeneration unit includes a regeneration liquid storage tank, a regeneration heating device, a regeneration agitator, and a regeneration feed valve. 8 . , regeneration discharge valve, regeneration level gauge, regeneration temperature sensor, regeneration concentration sensor and regeneration feeding device, fixed regeneration heating device on regeneration storage tank, regeneration stirrer, regeneration liquid level gauge, regeneration temperature sensor, regeneration concentration sensor They are fixedly installed in the regeneration liquid storage tank, the regeneration feeding valve is placed on the feeding pipeline of the regeneration liquid storage tank, the regeneration discharge valve is installed on the discharge pipeline of the regeneration liquid storage tank, and the feeding device is connected with the regeneration liquid storage tank. . 8 . The integrated device for liquid-phase flue gas denitration and denitrification liquid regeneration according to claim 7 , wherein a third liquid level gauge and a third concentration sensor are fixedly installed in the second liquid storage tank. 9 . 9 . The integrated device for liquid-phase flue gas denitrification and denitrification liquid regeneration according to claim 7 , wherein a third temperature sensor is fixedly arranged in the middle of the absorption tower, a mist eliminator is arranged at the top of the absorption tower, and the mist eliminator is externally connected. 10 . A water inlet pipe, a second water inlet pipe valve is arranged on the water inlet pipe, and a drainage pump is fixedly installed on the drainage pipe connected to the bottom of the second liquid storage tank.

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