CN114682067B - Device and process for removing nitric oxide in airflow - Google Patents
Device and process for removing nitric oxide in airflow Download PDFInfo
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- CN114682067B CN114682067B CN202111680085.9A CN202111680085A CN114682067B CN 114682067 B CN114682067 B CN 114682067B CN 202111680085 A CN202111680085 A CN 202111680085A CN 114682067 B CN114682067 B CN 114682067B
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
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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
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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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
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/54—Nitrogen compounds
- B01D53/56—Nitrogen oxides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/77—Liquid phase processes
- B01D53/78—Liquid phase processes with gas-liquid contact
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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
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/80—Semi-solid phase processes, i.e. by using slurries
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/96—Regeneration, reactivation or recycling of reactants
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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Abstract
The device consists of an absorption tower, a material storage tank, a regeneration reactor, a dehydration air extractor group, a related material conveying pipeline and a valve, wherein the nitrogen oxide absorption tower has the functions of absorbing and removing nitrogen oxide gas in the air flow by adopting ferric chloride absorbent slurry, the regeneration reactor has the functions of removing the absorbed nitrogen oxide in the absorbent slurry and regenerating the absorbent slurry, the dehydration air extractor group has the function of dehydrating the absorbent of the regeneration reactor, and the material storage tank has the function of providing the absorbent slurry for the absorption tower to work.
Description
Technical Field
The invention relates to a device and a process for removing nitric oxide in air flow, belonging to the technical field of air pollution control and environmental protection.
Background
Nitrogen Oxides (NO) produced by human activity x ) Harmful gases, mainly including NO and NO 2 Wherein the majority is generated by the combustion of the fuel. Nitrogen oxides have toxic effects on human bodies, and a large amount of nitrogen oxide discharge is one of the main causes of atmospheric photochemical fog and acid rain. In general, the concentration of nitrogen oxides in flue gas generated by combustion of fossil fuel in a thermal power plant or the like is about several hundred to several thousand ppm, of which about 95% or more is nitrogen monoxide.
The inventors of the present invention have disclosed a method for removing nitric oxide from a gas stream using ferric chloride slurry as a denitrification absorber (CN 111167263) by utilizing the chemical adsorption reaction of solid ferric chloride in the slurry and nitric oxide gas in the gas stream under certain conditions to obtain the corresponding coordination compound, thereby removing the corresponding coordination compound from the gas stream. The invention provides a device and a process for removing nitric oxide in airflow by adopting the absorbent slurry.
Disclosure of Invention
The device is composed of a nitrogen oxide absorption system, an absorbent regeneration system, a related material conveying pipeline, a control auxiliary system and the like, wherein the nitrogen oxide absorption system mainly comprises an absorption tower, a material storage tank and a material conveying pump, and the absorbent regeneration system mainly comprises a regeneration reactor, a vacuum air pump, an air compressor, a dehydration air pump set, a nitrogen oxide recovery air pump and the like.
The material storage tank is communicated with the nitric oxide absorption tower through a material storage tank material discharge pipe, a material delivery pump and an absorption tower material inlet, the absorption tower material outlet is communicated with the material storage tank through a material storage tank circulating material inlet, the material outlet is communicated with a regeneration reactor through a regeneration reactor material inlet after the material storage tank is reacted, the regeneration reactor is communicated with the material storage tank through a regeneration reactor material outlet and a material storage tank new material inlet, and the regeneration reactor is also respectively communicated with a vacuum air pump, an air compressor, a nitric oxide recovery air pump and a dehydration air pump unit. The dehydration air extractor unit mainly comprises a liquid storage tank, a circulating water pump, a venturi tube and a condenser, and the regeneration reactor is also provided with an auxiliary material inlet.
The process flow for removing nitric oxide in the air flow by utilizing the device comprises the steps of leading the air flow containing nitric oxide to be treated into an absorption tower through an air inlet, conveying absorbent slurry in a material storage tank into the absorption tower through a material discharge pipe of the material storage tank, a material conveying pump and a material inlet of the absorption tower, enabling absorbent slurry droplets sprayed in the tower after being atomized through a spray head to contact with the air flow, enabling nitric oxide in the air flow to react with solid ferric chloride crystals in the absorbent slurry to be absorbed, discharging the removed air flow from an air outlet at the upper part of the absorption tower, and returning the sprayed absorbent slurry to the material storage tank for recycling through a material circulating material inlet after being discharged through the material outlet of the absorption tower; the absorbent to be regenerated after reaction is led into the regeneration reactor through a material outlet of a material storage tank after reaction, an electromagnetic valve (1) and a material inlet of the regeneration reactor, wherein the leading-in mode adopts a vacuum pump for pumping (or adopts a material pump for conveying and other forms, the effect is the same), then a certain amount of water or hydrochloric acid solution added into the regeneration reactor through an auxiliary material adding port is fully mixed with the absorbent material, so that the slurry is diluted and absorbed nitric oxide gas is released, and the slurry is further recycled after being pumped out through a gas outlet of the regeneration reactor and an electromagnetic valve (9) through a nitric oxide recycling suction pump; the absorbent slurry after absorbing nitric oxide and nitric oxide is removed is dehydrated through a gas outlet of a regeneration reactor, an electromagnetic valve (8) and a dehydration air extractor unit consisting of a Venturi air suction pipe, a liquid storage tank, a liquid circulating pump and a condenser, tail gas containing hydrogen chloride is returned to the regeneration reactor through the electromagnetic valve (4), and the lower end of the condenser is provided with a liquid discharge electromagnetic valve (7) for periodically discharging the removed water; after the absorbent in the regeneration reactor is regenerated, the absorbent slurry is led into the material storage tank through the material outlet of the regeneration reactor, the electromagnetic valve (2) and the new material inlet of the material storage tank, and the leading-in mode adopts air compressor air pressure conveying (or material pump conveying and other modes) to complete the regeneration cycle of the nitric oxide absorbent material from newly participating in the absorption reaction of nitric oxide. The whole system equipment and the pipeline are insulated, and a jacket is adopted for heating when the regeneration reactor is dehydrated; the liquid storage tank of the dehydration air extractor group is cooled by a jacket, and the condenser is cooled by cooling water or chilled water; the nitric oxide gas pumped by the nitric oxide recovery air pump can be used for preparing high-purity nitric oxide gas through the processes of water washing, drying and dehydration (including freeze drying and adsorption drying) and the like, and can also be directly used as a primary raw material of chemical products to enter the next working procedure.
Furthermore, the material storage tank is also provided with the stirring motor and the stirrer, the liquid inlet of the material discharge pipe of the material storage tank is positioned below the liquid level of the material slurry and is higher than the bottom of the storage tank container by a certain height, generally more than 50mm at the bottom, and the liquid inlet is arranged in the vertical direction and the horizontal direction, so that the effect is equivalent. The blades of the agitator are immersed in the slurry and may be positioned generally below the inlet of the material discharge pipe. The material outlet of the material storage tank after the material storage tank is reacted is arranged above the liquid inlet position of the material discharge pipe of the material storage tank below the liquid level of the slurry, and the distance between the material outlet and the liquid inlet position is more than 50mm, preferably 150-300 mm, so as to ensure that a certain amount of material is always stored in the storage tank for the continuous operation of the material conveying pump (the lowest storage amount of the material between the two distances is larger than the sum of the liquid holdup of the material in each system such as a pipeline, a tower and the like during the operation of the material conveying pump).
Further, the stirrer is generally an electric stirrer, and can be replaced by air bubbling, ultrasonic stirring, magnetic stirring and the like, so that the effect is equivalent. When an electric stirrer is used, the rotation frequency is generally 0 to 100 rpm, preferably 20 to 50 rpm, and the stirrer can be rotated positively or reversely, and is not particularly required as required. The content of solid ferric chloride crystals in the conveyed slurry can be increased by about 1-15% every 10 revolutions per minute when the rotation frequency is increased, and the content increasing rate is reduced along with the further increase of the rotation speed. When the rotation frequency exceeds 50 revolutions per minute, the materials in the material storage tank are basically and uniformly stirred, and the effect of increasing the solid material content of the slurry in the discharge pipe is not great. The stirrer blade can be selected from a plurality of blades or impellers such as radial flow, axial flow and the like, and specific parameters can be referred to related manual of chemical equipment.
Because the absorbent slurry is supersaturated ferric chloride slurry, the difference of specific gravity between solid ferric chloride crystals in the slurry and solid-liquid materials of the solution is large, and the ferric chloride crystals are easy to deposit at the bottom of the container. The solid material content in the absorbent slurry of the material discharge pipe can be controlled by adjusting the rotating speed of the stirrer (when mechanical stirring is adopted), so that the nitrogen monoxide removal effect in the absorption tower can be controlled according to the load of nitrogen monoxide in different air flows, the material utilization efficiency is improved, and the material discharge pipe can be prevented from being blocked.
Further, the regeneration reactor structure is substantially the same as the material storage tank, and an electric stirrer is also used. The regeneration reactor can adopt the conventional bottom discharge, clear water or hydrochloric acid solution is added into an auxiliary material adding port as required, and the adding amount is about 3% or more, preferably 5-10% of the material conveying amount; the tail gas containing hydrogen chloride returns to the regeneration reactor when the slurry in the regeneration reactor is dehydrated, so as to maintain the dehydration of materials in an acidic environment, ensure that the ferric chloride is not decomposed when dehydrated, and generally maintain the pH of the slurry below 2-3.
Further, the working temperature of the nitric oxide absorption tower is generally 30-130 ℃, preferably 65-110 ℃, the pH of the slurry is generally kept below 2-3 during working, so that the hydrolysis of ferric chloride in the slurry is inhibited, the absorption efficiency is improved, and the nitric oxide absorption tower can be realized by adding hydrogen chloride gas (the concentration is generally above 0.05%) into a gas phase, and the like. The temperature of the regeneration reactor is generally 65 ℃ or higher, preferably 100-160 ℃, during slurry dehydration, and other stages are generally maintained at 50-65 ℃ so that the materials in the reactor are kept in a flowing state. The working temperature of the material storage tank should be above 50 ℃, preferably 60-80 ℃. The pipeline of the material conveying system can be insulated by an electric heating belt or a jacket, and the temperature is generally 50-80 ℃; the regeneration reactor or the storage tank jacket is heated for heat preservation.
Furthermore, the dehydration air extractor set adopts hydrochloric acid or salt solution or mixed solution of the hydrochloric acid and the salt solution as an air extracting medium, so that the dehydration air extractor set can absorb moisture in an air extracted body and can avoid absorbing hydrogen chloride gas in air flow. The salt is mainly chloride or bromide of alkali metal or alkaline earth metal, preferably salt with good hygroscopicity and salting-out effect, such as lithium chloride, magnesium chloride, calcium chloride or lithium bromide and their mixed solution, the concentration is generally above 10%, preferably 40-60%, the concentration of salt solution is high, the corresponding saturated water vapor pressure is low at the same temperature, the dehydration of material is more facilitated, and the salt solution can also be saturated solution or supersaturated slurry. When hydrochloric acid solution is used as the air extracting medium, the hydrochloric acid concentration is generally 5% or more, preferably 15 to 30%. One of the advantages of using a mixed solution of hydrochloric acid and salt as an air extraction medium is that the equilibrium concentration of hydrochloric acid in the solution is low, and hydrogen chloride gas in the gas is not easy to be absorbed. The liquid storage tank and the condenser are dehydrated by cooling water or chilled water, the temperature is generally below 45 ℃, and the condenser can be lower, preferably 0-15 ℃. The salt solution in the liquid storage tank can be dehydrated and regenerated by heating (or decompressing) after being absorbed and saturated, and the temperature of the heated and dehydrated salt solution is generally 65 ℃ or above, preferably 90-110 ℃. In particular, the selection can be made according to different media. When hydrochloric acid solution is adopted, the concentration of the dehydrated hydrochloric acid reaches 20 percent. In order to prevent the hydrolysis of ferric chloride, the pH value of the slurry is below 2-3 in the dehydration process, and correspondingly, when the dehydration temperature is 65 ℃, the gas-phase hydrogen chloride concentration should be above 0.1%, the dehydration temperature is high, and the gas-phase hydrogen chloride concentration should be correspondingly improved, and can be specifically determined according to the equilibrium vapor pressure and the related thermodynamic parameters of the vapor pressure of the ferric chloride slurry.
Further, slurry density sensors (which can adopt vibrating tuning fork type, gamma rays, ultrasonic wave and other densimeters) and temperature sensors are arranged in the material storage tank, the regeneration reactor and the related material conveying pipelines to obtain related material density, temperature and other parameters, and an electromagnetic flowmeter can be adopted for slurry flow in the pipelines. The density of the slurry material can also be obtained by detection after manual sampling, and then the relevant operation is carried out, so that the effect is equivalent. The liquid level in the material storage tank can be measured and controlled by ultrasonic wave, radar or floating ball type liquid level meter to keep the slurry liquid level in the material storage tank in a certain range. The system process can adopt a PLC control system to work according to an absorption-regeneration-absorption circulation program, and the valves of the pipeline system adopt normally closed electromagnetic valves. The main process comprises the following steps:
a starting stage: adding a required amount of ferric chloride slurry into a material storage tank, starting stirring to uniformly mix the materials, wherein the slurry material density (average) in the storage tank is generally 2.1 (g/cm) 3 The same applies below) above (the amount of solid ferric chloride-containing crystals is above about 20%, depending on the temperature and the hydrochloric acid content of the slurry, etc.), preferably 2.2-2.6, and the start-up phase is completed.
Absorption working phase: starting the material conveying pump absorption tower to work, and adjusting the rotating speed of the material storage tank stirring motor according to the concentration of nitric oxide in the processed airflow at the stage so as to increase or reduce the supply of effective solid components in the circulating slurry; when the density of the slurry material in the storage tank is below 1.7 (the solid content is below 5 percent, and the concentration of nitric oxide at the outlet of the absorption tower can be set as required) or the concentration of nitric oxide at the outlet of the absorption tower is increased to a preset value, the absorption reaction is finished, and the absorbent enters the regeneration stage of the absorbent.
An absorbent regeneration stage: (a) The vacuum pump works, the electromagnetic valves (1) and (5) are opened, and the recycled materials are fed into the regeneration reactor. When the pressure difference between the material storage tank and the regeneration reactor is zero, the vacuum air pump is stopped, and after the material feeding is finished, the vacuum pump and the electromagnetic valve (1) (5) are closed.
(b) Opening an auxiliary material adding port electromagnetic valve (3), adding quantitative water or dilute hydrochloric acid solution, and closing after the addition.
(c) And (3) starting a stirrer of the regeneration reactor, an electromagnetic valve (9) and a nitric oxide recovery air pump (22) to pump out nitric oxide gas, pumping air for a preset time, and closing the electromagnetic valve (9) and the nitric oxide recovery air pump (22) after pumping air.
(d) In the dehydration process, an electromagnetic valve (8), a liquid circulating pump and an electromagnetic valve (4) are opened, a heater is opened to heat a regeneration reactor to 100-150 ℃ from 50-65 ℃, when a material density parameter (or a material density parameter detected after manual sampling) obtained by a slurry density sensor arranged in the regeneration reactor is about 2.1 (the solid content is more than about 25 percent, and the material density parameter is set as required) and reaches a preset requirement, the electromagnetic valve (8), the liquid circulating pump and the electromagnetic valve (4) are closed, an air compressor and the electromagnetic valve (2) are opened to guide regenerated materials into a material storage tank, when the pressure difference between the material storage tank and the regeneration reactor is zero, an air compressor is stopped, the material feeding is completed, the air compressor and the electromagnetic valve (2) are closed, and the material storage tank and the regeneration reactor reenter an absorption working stage.
After the salt solution in the liquid storage tank of the dehydration vacuum air extractor group contains too much water, part of water can be removed by heating (or decompressing) at a temperature of over 65 ℃, preferably 85-110 ℃ and the dehydration amount is controlled by a liquid level meter arranged in the liquid storage tank. The lower end of the condenser is provided with a liquid discharge electromagnetic valve (7) for periodically discharging the removed water, and the liquid level meter is used for controlling automatic liquid discharge.
In actual use, a plurality of regeneration reactors can be connected in parallel and alternately work.
Compared with the prior art, the invention consists of a nitric oxide absorption system, an absorbent regeneration system, a related material conveying pipeline valve, a control system and other auxiliary systems, the absorbent is recycled after regeneration, the structure of the material storage tank can control and regulate the content of effective solid materials in absorbent slurry in the material discharge pipe, thereby improving the utilization efficiency of the materials, the material dehydration in the regeneration reactor adopts a dehydration vacuum air extractor unit taking hydrochloric acid or salt solution or mixed solution of the hydrochloric acid and the salt solution as a medium, the tail gas containing hydrogen chloride returns to the regeneration reactor, the hydrolysis of ferric chloride is avoided, and the device and the process are simple and reliable.
Drawings
Fig. 1 is a schematic diagram of a device and process for removing nitric oxide from a gas stream.
FIG. 2 is a schematic diagram of the internal structure of a material storage tank.
In the figure: 101 an absorption tower; 102 a material storage tank; 103 regenerating the reactor; 104 a liquid storage tank; 1, a gas inlet; 2, a gas outlet; 3, material inlet of absorption tower; 4, a material conveying pump; 5 an absorption tower material outlet; 6 a circulating material inlet of the material storage tank; 7 a material discharge pipe of the material storage tank; 8 a material outlet after the material storage tank reacts; 9 new material inlet of material storage tank; 10 regenerating a reactor material outlet; 11 auxiliary material adding ports; 12 regenerating the reactor material inlet; 13 a regeneration reactor gas outlet; 14 a vacuum pump; 15 an air compressor; 16 a liquid storage tank liquid outlet; 17 a liquid circulation pump; 18 a condenser; 19 a liquid storage tank gas outlet; 20 a gas-liquid mixture inlet of a liquid storage tank; a venturi suction tube 21; 22 nitric oxide recovery air pump; 23, a stirring motor; 24 agitators; (1) and (9) is an electromagnetic valve.
Detailed Description
The invention is described in further detail below with reference to the drawings and examples.
Example 1: a device and a process flow for removing nitric oxide in a gas stream are shown in figure 1. The system comprises an absorption tower 101, a material storage tank 102, a regeneration reactor 103, a liquid storage tank 104, related material conveying pipeline valves and other auxiliary systems. Wherein the material storage tank 102 is communicated with the absorption tower 101 through a material storage tank material discharge pipe 7, a material delivery pump 4 and an absorption tower material inlet 3, the absorption tower material outlet 5 is communicated with the material storage tank 102 through a material storage tank circulating material inlet 6, and a material outlet 8 after the material storage tank reaction is communicated with the regeneration reactor 103 through an electromagnetic valve (1) and a regeneration reactor material inlet 12; the bottom of the regeneration reactor 103 is communicated with the upper part of a material storage tank 102 through a material outlet 10 of the regeneration reactor and an electromagnetic valve (2), the upper part of the regeneration reactor 103 is communicated with a nitrogen monoxide recovery suction pump 22 through an electromagnetic valve (9) after passing through a gas outlet 13 of the regeneration reactor, the other path is communicated with a liquid storage tank 104 through an electromagnetic valve (8), a venturi suction pipe 21 and a gas-liquid mixture inlet 20 of the liquid storage tank, a liquid outlet 16 of the liquid storage tank at the lower part of the liquid storage tank 104 is communicated with the venturi suction pipe 21 through a liquid circulating pump 17, a gas outlet 19 of the liquid storage tank is communicated with the regeneration reactor 103 through a condenser 18 and an electromagnetic valve (4), and a liquid discharge electromagnetic valve (7) is further arranged at the lower end of the condenser 18; the upper part of the regeneration reactor 103 is respectively communicated with a vacuum air pump 14 and an air compressor 15 through a pipeline and valves (5) and (6), and the nitric oxide absorption tower 101 is also provided with a gas inlet 1 and a gas outlet 2; the regeneration reactor 103 is also provided with an auxiliary material adding port 11 and an auxiliary material adding amount control electromagnetic valve (3), and both the material storage tank and the regeneration reactor are internally provided with stirrers. The electromagnetic valve is normally closed, and can be replaced by a manual valve or a pneumatic valve.
The absorption tower is a hollow tower made of glass fiber reinforced plastic, the tower diameter phi is 300mm, the total height of the tower is about 3000mm, and the effective spraying height is about 1500mm. The internal structure of the material storage tank is shown in fig. 2, the material storage tank is a glass lining reaction kettle with the effective volume of about 120L and the diameter phi 450mm, a stirrer motor 23 and a stirring paddle 24 are arranged, the stirrer is arranged in a double-paddle mode, and the single paddle blades are about 30mm in height and about 60mm in length and are symmetrically arranged. The height of the liquid inlet of the material discharge pipe 7 of the material storage tank from the bottom is about 200mm, and the material outlet (8) after the material storage tank reacts is arranged at the position about 100mm above the liquid inlet of the material discharge pipe 7 of the material storage tank. The density of the materials in the storage tank is detected by a tuning fork densimeter and is arranged at the position about 150mm below the liquid level. The structural size of the regeneration reactor 103 is approximately the same as that of the material storage tank, the bottom is discharged, and an electric stirrer is used. The whole system pipeline is insulated at 55-65 ℃, the regeneration reactor 103 is heated by a jacket at 100-150 ℃ during dehydration, the liquid medium of the dehydration air extractor group is hydrochloric acid and lithium chloride mixed solution (hydrochloric acid is about 15-20%, lithium chloride is 45%), the addition amount is about 200kg, the liquid storage tank 104 of the dehydration air extractor group is cooled by cooling water at 35-45 ℃, and the condenser (18) is cooled by 0-7 ℃.
The method comprises the following steps of introducing a gas flow containing nitric oxide to be treated into an absorption tower 101 through a gas inlet 1, conveying absorbent slurry in a material storage tank 102 into the absorption tower through a material discharge pipe outlet 7 of the material storage tank, a material conveying pump 4 and a material inlet 3 of the absorption tower, enabling absorbent slurry droplets sprayed in the tower after atomization through an atomization nozzle to fully contact with the gas flow, enabling nitric oxide in the gas flow to be absorbed through chemical reaction with ferric chloride in the absorbent slurry, discharging the removed gas flow from a gas outlet 2 at the upper part of the absorption tower, and returning the reacted absorbent slurry to the material storage tank 102 through a material circulation inlet 6 of the material storage tank through a material outlet 5 of the absorption tower for recycling; the absorbent to be regenerated after reaction is led into the regeneration reactor 103 through a material outlet 8 of a material storage tank after reaction, a valve (1) and a material inlet 12 of the regeneration reactor, the leading-in mode adopts a vacuum suction pump 14 for pumping material, then a certain amount of hydrochloric acid solution added into the regeneration reactor 103 through an auxiliary material adding inlet 11 is fully mixed with the absorbent material and releases absorbed nitric oxide gas, and the absorbed nitric oxide gas is further recovered after being pumped out through a nitric oxide recovery suction pump 22 through a gas outlet 13 of the regeneration reactor and an electromagnetic valve (9); the absorbent slurry after absorbing nitric oxide is removed is subjected to evaporation reduction and dehydration through a gas exhaust port 13 of a regeneration reactor, an electromagnetic valve (8), a dehydration air suction unit consisting of a Venturi air suction pipe 21, a liquid storage tank 104, a liquid circulating pump 17 and a condenser 18, tail gas containing hydrogen chloride is returned to the regeneration reactor 103 through the electromagnetic valve (4) so as to maintain the content of the hydrogen chloride in the absorbent, and a liquid discharge electromagnetic valve (7) is arranged at the lower end of the condenser 18 to periodically discharge the removed water; after the absorbent in the regeneration reactor 103 is regenerated, the absorbent slurry is led into the material storage tank 102 through the material outlet 10 of the regeneration reactor, the electromagnetic valve (2) and the new material inlet 9 of the material storage tank to participate in the absorption reaction of the nitric oxide again, thus completing the regeneration cycle of the nitric oxide absorbent material, and the leading-in mode adopts the pressure feeding mode of the air compressor 15.
The initial absorbent is supersaturated ferric chloride slurry, the water content is about 7-8%, the hydrochloric acid is about 3%, and the temperature of the material storage tank is 65-75 ℃. The material conveying pump adopts a tetrafluoro diaphragm pump, the diameter of a pump inlet pipeline is 40mm, the diameter of a discharge port is 32mm, and the pump circulation volume is about 350L/h. Adding hydrochloric acid solution with concentration of 20% into an auxiliary material adding port of the regeneration reactor, wherein the adding amount is about 5% of the material amount; the dehydration temperature of the regeneration reactor is 120-150 ℃, and the temperature of the air flow in the absorption tower is about 80-90 ℃.
The flow rate of the treated gas is about 150m 3 And/h, the liquid-gas ratio is about 2-8L/m 3 The gas inlet stream had an NO concentration of about 500ppm, a sulfur dioxide concentration of about 500ppm, an oxygen concentration of about 8% (by volume, the same applies hereinafter), a moisture content of about 10%, a carbon dioxide content of about 10%, the balance nitrogen, and an effective residence time of the gas in the reactor of about 1 to 2 seconds, with an average removal rate of nitrogen monoxide of about 85%. The specific treatment process is as follows:
a starting stage: the mass of the ferric chloride slurry is about 250kg, the water content is about 7-8%, the hydrogen chloride content is about 2%, and the stirring motor is started (the rotation speed is about 50 rpm and kept unchanged), so that the materials are uniformly mixed, and the density of the materials in the material storage tank 102 is 2.3-2.4 (the solid content is about 20-30%), and can be measured by a tuning fork densitometer.
Absorption working phase: the material transfer pump is started to start the absorber 101 to work, and when the slurry density in the material storage tank 102 or the transfer pipeline is reduced to 1.7-1.8 (the solid content is about 3-5%) or the nitrogen monoxide removal rate is lower than 50%, the absorber enters the absorber regeneration stage.
An absorbent regeneration stage: (a) The vacuum pump (2.2 kW) is operated, the solenoid valves (1) (5) are opened, and the recycle material is fed to the regeneration reactor 103. When the pressure difference between the material storage tank and the regeneration reactor is zero, after the material feeding is finished, the vacuum pump and the electromagnetic valve (1) (5) are closed;
(b) Opening an auxiliary material adding port electromagnetic valve (3) to add a preset amount of dilute hydrochloric acid solution, and closing the electromagnetic valve (3) after the addition;
(c) Starting a stirrer of the regeneration reactor (the rotating speed is about 50 revolutions per minute and is kept unchanged), pumping out released nitric oxide gas by using an electromagnetic valve (9) and a nitric oxide recovery pumping pump (22) (2.2 kW), pumping out the released nitric oxide gas for about 10-15 minutes, and closing the electromagnetic valve (9) and the nitric oxide recovery pumping pump (22) after the nitric oxide gas is completely released and pumped out;
(d) In the dehydration process, an electromagnetic valve (8), a liquid circulating pump (17) and an electromagnetic valve (4) are opened, a heater is opened to heat the regeneration reactor to 120-150 ℃, when the slurry density in the regeneration reactor is measured to be 2.3-2.4, the regeneration is completed, the electromagnetic valve (8), the liquid circulating pump (17) and the electromagnetic valve (4) are closed, an air compressor (15) (3 kW) and the electromagnetic valve (2) are opened to press regenerated materials into a material storage tank (102), when the material storage tank and a pressure difference meter of the regeneration reactor are zero, the material feeding is completed, the air compressor (15) and the electromagnetic valve (2) are closed, and the absorption working stage is carried out again.
Example 2: other conditions are the same as in example 1, and the effects of the change in rotational speed of the material tank stirrer on the change in solid material content in the material tank discharge tube (using tuning fork densitometer and sample check, respectively) and the nitric oxide removal rate are shown in tables 1 and 2, respectively, below.
TABLE 1 variation of stirrer rotation speed and solid Material content in Material storage tank discharge tube (when there is no absorption)
TABLE 2 stirrer speed vs. nitric oxide removal (fresh 1 hour average)
The above embodiments are only for illustrating the technical solutions of the present invention, and it should be understood that it is within the scope of the present invention to modify the technical solutions described in the embodiments or make any equivalent substitution, modification, variation and improvement on some technical features thereof by those skilled in the art without departing from the spirit and principle of the present invention.
Claims (6)
1. A device for removing nitric oxide in air flow is characterized in that the device consists of an absorption tower (101), a material storage tank (102), a regeneration reactor (103), a liquid storage tank (104) and a material conveying pipeline and a valve, wherein the material storage tank (102) is communicated with the absorption tower (101) through a material storage tank material discharge pipe (7), a material conveying pump (4), an absorption tower material inlet (3), an absorption tower material outlet (5) is communicated with the material storage tank (102) through a material storage tank circulating material inlet (6), a material outlet (8) after the material storage tank is reacted is communicated with the regeneration reactor (103) through an electromagnetic valve (1) and a regeneration reactor material inlet (12), the bottom of the regeneration reactor (103) is communicated with the upper part of the material storage tank (102) through a regeneration reactor material outlet (10) and an electromagnetic valve (2), the upper part of the regeneration reactor (103) is communicated with the upper part of the material storage tank (102) through a regeneration reactor gas outlet (13), and then is communicated with a nitric oxide recovery pump (22) through the electromagnetic valve (9), the other part is communicated with a venturi gas suction pump (17) through an electromagnetic valve (8), a venturi storage tank (21) and a liquid mixture (20) is communicated with the lower liquid storage tank (17) through a venturi liquid inlet (16), the gas outlet (19) of the liquid storage tank is communicated with the regeneration reactor (103) through a condenser (18) and an electromagnetic valve (4), the lower end of the condenser (18) is also provided with a liquid discharge electromagnetic valve (7), the upper part of the regeneration reactor (103) is respectively communicated with a vacuum suction pump (14) and an air compressor (15) through a pipeline and valves (5) and (6), the absorption tower (101) is also provided with a gas inlet (1) and a gas outlet (2), the regeneration reactor (103) is also provided with an auxiliary material adding inlet (11) and an auxiliary material adding amount control electromagnetic valve (3), and the material storage tank and the regeneration reactor are internally provided with stirrers; the stirring motor (23) and the stirrer (24) are arranged in the material storage tank (102), the rotation frequency of the stirring motor is 20-100 revolutions per minute, the liquid inlet of the material discharge pipe (7) of the material storage tank is below the liquid level of the material slurry and is higher than the bottom of the container by more than 50mm, the material outlet of the material storage tank (102) after reaction is arranged above the liquid inlet of the material discharge pipe (7) of the material storage tank below the liquid level of the slurry by more than 50mm, and the material slurry is ferric chloride slurry containing solid ferric chloride crystals; the dehydration air extractor unit of the absorbent slurry in the regeneration reactor (103) consists of a liquid storage tank (104), a liquid circulating pump (17), a Venturi air suction pipe (21) and a condenser (18), wherein the liquid of the dehydration air extractor unit adopts hydrochloric acid or salt solution or mixed liquid solution of the hydrochloric acid and the salt solution as an air extraction medium, and the salt is alkali metal or alkaline earth metal chloride or bromide and comprises lithium chloride, magnesium chloride, calcium chloride or lithium bromide and mixed solution thereof.
2. The device according to claim 1, characterized in that the material outlet (8) after the reaction of the material storage tank (102) is 150-300 mm above the liquid inlet position of the material discharge pipe (7) of the material storage tank.
3. The device for removing nitric oxide from a gas stream according to claim 1, wherein the stirrer of said material storage tank is rotated at a frequency of 20 to 50 rpm.
4. The device for removing nitric oxide from a gas stream according to claim 1, wherein the concentration of hydrochloric acid solution in the pumping medium is 5% or more and the concentration of salt solution is 10% or more.
5. A process for removing nitric oxide in a gas stream by using the device as claimed in claim 1 is characterized in that the gas stream containing nitric oxide to be treated is led into an absorption tower (101) through a gas inlet (1) of the absorption tower (101), absorbent slurry in a material storage tank (102) is conveyed into the absorption tower (101) through a material discharge pipe (7) of the material storage tank, a material conveying pump (4) and a material inlet (3) of the absorption tower, droplets of the absorbent slurry sprayed down in the tower after atomization through a spray head are contacted with the gas stream, nitric oxide in the gas stream is absorbed by chemical reaction with ferric chloride in the absorbent slurry, the removed gas stream is discharged from a gas outlet (2) at the upper part of the absorption tower (101), the sprayed absorbent slurry is discharged through a material outlet (5) of the absorption tower and returned to the material storage tank (102) for cyclic use through a material circulating material inlet (6), the absorbent to be regenerated after reaction is led into a regeneration reactor (103) through a material outlet (8) of the material reaction tank, a valve (1) and a material inlet (12) of the regeneration reactor, the led into the regeneration reactor (103) is led into the absorption reactor in a suction pump (14) in a manner, nitric oxide and the waste solution is fully discharged through an air pump (13) or an air pump (13) to be fully discharged through an air exhaust valve (13) at the upper part of the absorption tower, and the waste gas is fully discharged through an air pump (13), the absorbent slurry after absorbing nitric oxide is removed passes through a gas exhaust port (13) of a regeneration reactor, an electromagnetic valve (8), moisture is removed through a dehydration pumping unit consisting of a Venturi gas suction pipe (21), a liquid storage tank (104), a liquid circulating pump (17) and a condenser (18), tail gas returns to the regeneration reactor (103) through the electromagnetic valve (4), a liquid discharge electromagnetic valve (7) is arranged at the lower end of the condenser (18), the removed moisture is regularly discharged, after the absorbent in the regeneration reactor (103) is regenerated, the absorbent slurry is led into a material storage tank (102) through a material outlet (10) of the regeneration reactor, the electromagnetic valve (2) and a new material inlet (9) of the material storage tank, the leading-in mode adopts an air compressor (15) for pneumatic conveying, and the absorption reaction of nitric oxide is re-participated, so that the regeneration cycle of nitric oxide absorbent material is completed.
6. The process for removing nitric oxide from a gas stream according to claim 5, wherein the process comprises the following steps:
a starting stage: adding supersaturated ferric chloride slurry into a material storage tank (102), and starting a stirring motor to ensure that the average density of the materials in the material storage tank (102) is 2.1g/cm 3 The above;
absorption working phase: starting the material transfer pump (4) to start the absorption tower (101) to work when the slurry density in the material storage tank (102) is reduced to 1.7g/cm 3 Entering an absorbent regeneration stage when the nitrogen monoxide removal rate is lower than 50%;
an absorbent regeneration stage: (a) The vacuum air pump (14) works, the electromagnetic valves (1) and (5) are opened, the recycled materials are fed into the regeneration reactor, and when the differential pressure gauge of the material storage tank (102) and the regeneration reactor (103) is zero, the vacuum air pump (14) and the electromagnetic valves (1) and (5) are closed after the material feeding is finished;
(b) Opening an auxiliary material adding port electromagnetic valve (3) to add a preset amount of dilute hydrochloric acid solution, and closing the electromagnetic valve (3) after the addition;
(c) Opening a stirrer of the regeneration reactor, an electromagnetic valve (9) and a nitric oxide recovery air pump (22) to pump out released nitric oxide gas, and closing the electromagnetic valve (9) and the nitric oxide recovery air pump (22) after the air pumping is finished;
(d) In the dehydration process, an electromagnetic valve (8), a liquid circulating pump (17) and an electromagnetic valve (4) are opened, a heater is opened to heat the regeneration reactor (103) to dehydrate, and the regeneration reaction is performedThe slurry density in the vessel (103) was 2.1g/cm 3 And after the regeneration is finished, closing the electromagnetic valve (8), the liquid circulating pump (17) and the electromagnetic valve (4), opening the air compressor (15) and the electromagnetic valve (2) to press the regenerated material into the material storage tank (102), and when the material storage tank (102) and the regeneration reactor (103) are subjected to material feeding when the differential pressure gauge is zero, closing the air compressor (15) and the electromagnetic valve (2), and re-entering the absorption working stage.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102794097A (en) * | 2012-09-12 | 2012-11-28 | 河南绿典环保节能科技有限公司 | Flue gas wet-type reduction integrated desulfurization and denitration and harmless processing and resource utilization method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| GB1587456A (en) * | 1977-09-28 | 1981-04-01 | Bolme D W | Process for the removal of nitrogen oxides from industrial gases by use of oxidising solutions in which nitrates are the oxidants |
| US4454102A (en) * | 1981-09-18 | 1984-06-12 | Flakt Aktiebolag | Method of purifying flue gases from sulphur dioxide |
| US5658545A (en) * | 1995-03-29 | 1997-08-19 | The Regents Of California | Metal regeneration of iron chelates in nitric oxide scrubbing |
| CN102824836A (en) * | 2012-09-12 | 2012-12-19 | 河南绿典环保节能科技有限公司 | Integrated wet-type oxidation, desulfurization, denitration and recycling method for smoke |
| CN102794098A (en) * | 2012-09-12 | 2012-11-28 | 河南绿典环保节能科技有限公司 | Flue gas wet-type oxidation denitration and resource utilization method |
| CN104084025B (en) * | 2014-07-17 | 2016-04-20 | 湖南平安环保股份有限公司 | A kind of method of boiler smoke removal of nitrogen oxide |
| CN104437051B (en) * | 2014-11-17 | 2017-06-20 | 傅明冲 | A kind of wet desulphurization denitrating system and method |
| CN105032163A (en) * | 2015-07-02 | 2015-11-11 | 黄立维 | Method and apparatus for removing nitrogen oxide and sulfur dioxide from air flow |
| CN105170070A (en) * | 2015-07-08 | 2015-12-23 | 黄立维 | Denitration and desulfurization ferric chloride solid particles and preparation method thereof |
| CN105536501A (en) * | 2016-01-06 | 2016-05-04 | 黄立维 | Regeneration method for ferric chloride for denitration |
| CN111167263B (en) * | 2018-11-13 | 2021-04-13 | 黄华丽 | Nitrogen oxide absorbent slurry and preparation and use methods thereof |
| CN109589792A (en) * | 2018-12-29 | 2019-04-09 | 北京博奇电力科技有限公司 | A kind of device and method of low temperature wet flue gas denitration |
| CN109647165A (en) * | 2019-01-15 | 2019-04-19 | 苏州仕净环保科技股份有限公司 | A kind of technique that NOx, SO2 in flue gas are removed simultaneously with circulating absorption solution |
| CN111151231B (en) * | 2020-01-09 | 2021-10-15 | 浙江工业大学 | Method for regenerating denitration ferric chloride adsorbent |
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