WO2015161676A1

WO2015161676A1 - Method for removing nitrogen oxides in flue gas and nano flue gas denitration system

Info

Publication number: WO2015161676A1
Application number: PCT/CN2015/000272
Authority: WO
Inventors: 傅国琳
Original assignee: 林小晓; 车道岚
Priority date: 2014-04-23
Filing date: 2015-04-17
Publication date: 2015-10-29
Also published as: CN103949145A; CN103949145B

Abstract

A method for removing nitrogen oxides in a flue gas: (1) pretreating a flue gas containing nitrogen oxides in a pretreatment vessel, removing solid particles greater than 10 micrometers in diameter in the flue gas during the pretreatment, and oxidizing NO into NO₂; (2) introducing the pretreated flue gas into a denitration vessel, where the nitrogen oxides react with an oxidizer to produce nitric acid; and, (3) discharging a purified gas from the denitration vessel. A nano flue gas denitration system characterized in being constituted by a pretreatment chamber and a denitration chamber. An output end of the pretreatment chamber is connected to an input end of the denitration chamber. Advantage: the method and system provided effectively convert nitrogen oxides into nitric acid; therefore, benefits from recycling far exceed operating costs of the equipment itself, thus allowing a user to acquire further profits. This is applicable in other industry markets, including cement plants, steel mills, municipal waste incineration plants, medical waste incineration plant, chlorine production plants, pulp and paper mills.

Description

Method for eliminating nitrogen oxides in flue gas and nano-smoke denitration system

(1) Technical field:

The invention relates to an exhaust gas treatment method and system, in particular to a method for eliminating nitrogen oxides in flue gas and a nano-smoke denitration system.

(2) Background technology:

Nitrogen (NOx) is a generic term for nitrogen oxides, and the term refers to the combined concentration of NO and NO ₂ (nitrogen monoxide and nitrogen dioxide). Nitrogen oxides and volatile organic compounds (VOCs) in the air react chemically in the sun to form ozone. Children and people who work or exercise outdoors are vulnerable to the adverse effects of ozone. Ozone can cause asthma, damage lung tissue, and reduce lung function. Ozone can also be transported through wind and air, and its health effects far exceed the original nitrogen oxides. Other effects of ozone also include damage to plant growth leading to a decline in crop yields. In addition, nitrogen oxides and sulfur dioxide react with other substances in the air to form acid rain, which is mixed with rain, fog, snow or micro particles falling on the ground. Acid rain damages cars, buildings and the deterioration of historical monuments; acid rain causes lakes and streams to become acidic, resulting in an ecological imbalance in natural waters. Acidic microparticles penetrate deep into sensitive parts of the lungs and can cause or exacerbate respiratory diseases such as emphysema, bronchitis, and exacerbation of existing heart disease. Acidic microparticles also block the transmission of light and reduce visibility, resulting in hazy weather, and people can't see the blue sky all year round. Even if nitrogen oxides do not become ozone, acid rain, or adsorb on microparticles, additional nitrogen is dissolved in streams and lakes, accelerating the “eutrophication” of water, resulting in excessive oxygen consumption, thus reducing fish and The number of shellfish.

According to China Electric Power's report, the cost of a 300,000-kilowatt unit for denitrification transformation construction should be about 60 million yuan. In September 2013, Beijing Longdian Hongtai Environmental Protection Technology Co., Ltd. of Huadian Energy Engineering Co., Ltd. and Henan Coal Chemical Group Shangqiu Yudong Power Generation Co., Ltd. officially signed the EPC general contracting of 2x315MW (315,000 kW) unit flue gas denitration project. Contract, the total contract amount is 120 million yuan. This universal cost is also confirmed. In addition to manufacturing costs, the operating costs of denitrification are also very high. According to the report: "A 300,000 kW denitration retrofit equipment must implement denitrification electricity prices, indeed 1.2 points / kW to just offset the cost, the unit with the highest operating cost reached 2.7 points / kW." In addition, the current efficiency of domestic denitration can only reach 40% to 70%. An engineer from a power plant in Zhejiang Province once said on the professional newspaper that the domestically selected thermal power unit denitration facilities were not built or put into operation. More, the technology of flue gas monitoring and automatic control is not mature enough, and related technologies are still in the process of exploration and absorption conversion. The existing SCR denitration technology, the accuracy of lasing ammonia slip monitoring, the control of ammonia injection under low load and the efficiency control have yet to be resolved. At present, the most mature and widely used technology for denitration in China is selective catalytic reduction (SCR), which lacks other new technologies with practical value and application prospects. The key to SCR technology is the catalyst. At present, the catalysts are in short supply in the domestic market. The products supplied in the market are basically foreign products. The research and application of domestic catalysts has just begun. Therefore, on the whole, domestic SCR equipment and materials all rely on foreign imports, which inevitably increases its manufacturing and operating costs.

(3) Invention content:

The invention aims to provide a method for eliminating nitrogen oxides in flue gas and a nano-smoke denitration system, which can solve the deficiencies of the prior art, and the invention can eliminate all nitrogen oxides NOx emitted by coal-fired boilers without The current RSC denitration system uses any urea and ammonia to control air pollution in a more economical and efficient way.

Technical Solution of the Invention: A method for eliminating nitrogen oxides in flue gas, characterized in that it comprises the following steps:

(1) The nitrogen oxide-containing flue gas is pretreated in a pretreatment vessel, and the pretreatment process removes solid particles having a diameter larger than 10 μm in the flue gas and oxidizes NO to NO ₂ :

Adding a solution containing an oxidizing agent and having a pH of 3 or less to the pretreatment vessel;

The flue gas is introduced into the pretreatment vessel, and is sufficiently contacted with the liquid to leave solid particles having a diameter larger than 10 μm in the solution, and NO is oxidized to NO ₂ ;

Exporting the solution containing the solid particles to the pretreatment vessel;

(2) The pretreated flue gas enters the denitration vessel, and the nitrogen oxide reacts with the oxidant to form nitric acid:

Adding a solution containing an oxidizing agent and having a pH of 3 or less to the denitration vessel;

The pretreated flue gas is introduced into the denitration vessel and fully reacted with the oxidant to form nitric acid;

(3) The purified gas is discharged to the denitration vessel.

The pretreatment vessel and the denitration vessel are first adjusted to a pH of 3 or less using nitric acid, and then an oxidizing agent is added.

The oxidizing agent in the pretreatment vessel and the denitration vessel is a mixture of hydrogen peroxide, molybdenum oxide and tungsten oxide, a mixture of magnesium oxide and magnesium hydroxide or ferric oxide, wherein molybdenum oxide, tungsten oxide, magnesium oxide, hydrogen Magnesium oxide and ferric oxide solid particles having a diameter of less than 20 nm, hydrogen peroxide and water The volume ratio is 1:18-22, the molar ratio of molybdenum oxide to tungsten oxide is 1:1, the molar ratio of magnesium oxide to magnesium hydroxide is 1:1, and the ratio of molybdenum oxide to water is 10 mol/L or more. The ratio of tungsten to water is 10 mol/L, the ratio of magnesium oxide to water is 10 mol/L, the ratio of magnesium hydroxide to water is 10 mol/L, and the ratio of ferric oxide to water is greater than or equal to 20 mol/L.

The hydrogen peroxide is produced by reacting magnesium peroxide, sodium peroxide or calcium peroxide having a diameter of less than 50 nanometers in water.

The liquid in the pretreatment vessel is ejected through a shower device to increase the area and time of contact of the flue gas with the liquid.

The gas in the denitration vessel is directly introduced into the liquid to increase the area and time of contact of the flue gas with the liquid, or the liquid is ejected through the sprinkler to increase the area and time of contact of the flue gas with the liquid; or both.

In the step (1), when hydrogen peroxide is used as the oxidant, the concentration of the oxidant is regularly monitored through the liquid outlet, and the oxidant concentration is stabilized in the solution by adding the oxidant as needed; the consumption of the hydrogen peroxide is collected periodically. The samples were closely monitored and the hydrogen peroxide consumption rate was observed using an iodine/potassium permanganate (I/KMnO4) titration method.

In the step (1), the flue gas enters the pretreatment container and enters from the lower part of the container; the direction is horizontal and is at an angle of 40 to 50 degrees with the container wall, so that the flue gas generates a spiral effect when moving upward to increase the time of contact with the liquid. .

The liquid flowing out of the pretreatment vessel in the step (1) is transported by a water pump to the spray device of the pretreatment vessel after removing the particulate matter larger than 10 micrometers.

In the step (2), the solution after the reaction is derived. When hydrogen peroxide is used as the oxidant, the concentration of the oxidant in the solution is periodically monitored. According to the monitoring situation, a new solution containing the oxidant is added to keep the solution component in the container. Stable; the consumption of hydrogen peroxide was closely monitored by periodic collection of samples, and the consumption rate of hydrogen peroxide was observed using an iodine/potassium permanganate (I/KMnO4) titration method.

The solution in the step (2) is transported by a water pump through a pipe to a shower device of the denitration vessel.

A nano-flue gas denitration system, characterized in that it is composed of a pretreatment chamber and a denitration chamber; an output end of the pretreatment chamber is connected to an input end of the denitration chamber;

The pretreatment bin includes a pretreatment bin body, a pretreatment bin sprinkler system, a pretreatment bin inlet, a pretreatment bin pump, a reservoir, a pretreatment bin outlet, a pretreatment bin inlet, and Pre-processing the gas outlet of the warehouse; the bottom of the pre-treatment silo body is a liquid storage device, and the liquid outlet of the pre-treatment chamber is disposed at the liquid storage device, the air inlet of the pre-treatment chamber, the liquid inlet of the pre-treatment chamber, and the pre-treatment The treatment chamber outlet is arranged on the pretreatment bin body above the liquid storage device, and the pretreatment chamber outlet port is above the intake port of the pretreatment chamber, and the pretreatment chamber is sprayed The system is disposed in the pretreatment bin, and the pretreatment bin pump is connected to the output end of the accumulator and the input end of the pretreatment bin sprinkler system through a pipeline;

The denitration bin comprises a denitration bin body, a denitration bin outlet, a denitration bin sprinkler system, a denitration bin inlet, a denitration bin inlet, a gas-liquid mixing channel, a denitration bin outlet, and a denitration tank pump; The denitration tank inlet port and the denitration tank outlet port are disposed at an upper portion of the denitration bin body; the denitration bin inlet port is disposed at a middle portion of the denitration bin body; the denitration bin outlet port is disposed in the denitration bin body The gas-liquid mixing channel and the denitration chamber spraying system are located in the denitration bin; the input end of the gas-liquid mixing channel is connected to the denitration port inlet, and the output end is placed in the liquid in the denitration bin; the denitration bin The pump is connected to the output of the bottom of the denitration bin and the input of the denitration sprinkler system through a pipe.

An inspection cover is arranged on the top of the pre-treatment silo body, an inspection door is arranged on the side wall of the storage body, a funnel-shaped collecting plate is arranged on the top of the liquid storage device, and a pre-treatment tank liquid level device and a sampling port are arranged on the side wall of the liquid storage device.

The pretreatment chamber sprinkling system is a pressure sprinkler device disposed on the top of the pretreatment bin, or a pressure sprinkler disposed on the top of the pretreatment bin and disposed on the inner wall of the pretreatment bin Spray sprinkler.

The spray droplets of the pressurized spray device are uniform wires; each drop has a diameter of 2 to 3 mm, and each drop is separated by 6 to 10 mm.

The pretreatment bin body is made of a stainless steel metal plate.

The pretreatment tank pump is an acid resistant water pump.

A denitration tank liquid level device is arranged on the side wall of the denitration bin body, and an inspection cover is arranged on the top of the denitration bin body.

The gas-liquid mixing channel comprises three medium-sized gas-liquid mixing channels and three small gas-liquid mixing channels, or five large mixing channels.

The denitration bin body is made of a stainless steel metal plate.

A working method of the above nano-flue gas denitration system:

Pretreatment method:

(1) watering the body of the pretreatment warehouse, using nitric acid to adjust the pH to below 3, and then adding an oxidant;

(2) Turn on the pre-treatment tank pump, and the pre-treatment tank sprinkler system starts to work;

(3) The flue gas enters the pretreatment bin from the angle between the inlet of the pretreatment bin and the inner wall of the pretreatment bin, so that the flue gas produces a spiral effect when moving upward;

(4) NO in the flue gas reacts with the oxidant to form NO ₂ ;

(5) Periodically collect samples through the sampling port to monitor the consumption of oxidant, and add oxidant to the pre-treatment silo according to the NO content in the flue gas.

The oxidizing agent is hydrogen peroxide, a mixture of molybdenum oxide and tungsten oxide, a mixture of magnesium oxide and magnesium hydroxide or ferric oxide, wherein molybdenum oxide, tungsten oxide, magnesium oxide, magnesium hydroxide and ferric oxide solids The diameter of the particles is less than 20 nm, the volume ratio of hydrogen peroxide to water is 1:18-22, the molar ratio of molybdenum oxide to tungsten oxide is 1:1, the molar ratio of magnesium oxide to magnesium hydroxide is 1:1, molybdenum oxide The ratio of use of water to water is 10 mol/L or more, the ratio of tungsten oxide to water is 10 mol/L or more, the ratio of magnesium oxide to water is 10 mol/L or more, and the ratio of magnesium hydroxide to water is 10 mol/L or more. The ratio of the amount of ferric oxide to water is 20 mol/L or more.

When the oxidizing agent is hydrogen peroxide, the consumption of hydrogen peroxide is closely monitored by sample collection per hour, and the consumption rate of peroxide is observed using an iodine/potassium permanganate (I/KMnO4) titration method.

Denitration method:

(1) adding an oxidant solution to the denitration chamber body, and the pretreated flue gas enters the gas-liquid mixing passage through the air inlet;

(2) NO ₂ in the flue gas reacts with the oxidant to produce HNO ₃ ;

(3) Regularly collect the sample to monitor the consumption of oxidant, and add the oxidant to the denitrification warehouse according to the NO content in the flue gas.

A portion of the NO ₂ molecules in the pretreated flue gas react with water to form HNO ₃ and NO; in the pretreatment chamber, NO that is not oxidized plus NO ₂ molecules will react with water to produce NO. HNO ₃ reacts with H ₂ O and produces intermediate HNO ₂ ; this intermediate is further reacted with H ₂ O ₂ to form the final product: HNO ₃ plus H ₂ O.

The working principle of the invention: the liquid in the pre-treatment silo contains an oxidant, which acts to oxidize NO to NO ₂ . The oxidant we chose was hydrogen peroxide (H ₂ O ₂ ). Choosing H ₂ O ₂ reason is H ₂ O ₂ in the reaction in an acidic environment, which is equivalent to the behavior of a strong oxidizing agent. It reacts immediately with NO in the flue gas. The velocity of the flue gas in the ventilation duct exceeds 6 m/s; at this rate, any material carried by the flue gas does not have much time to generate a chemical reaction unless the reaction is exothermic and spontaneous. In addition, hydrogen peroxide is relatively cheaper and safer than other strong oxidants, so that when the technology is applied to the industry on a large scale, the cost can be greatly reduced and the safety factor can be improved.

If the peroxide is in a gaseous state, then although the gas reaction has a higher reaction kinetics and usually occurs very quickly, the reverse reaction can also occur immediately after equilibrium is reached. Due to the oxides produced by the peroxides, NO ₂ is in a transition state and they are not very stable. If there is no effective way to convert the NO ₂ transition state to other final products, the intermediate can be immediately converted back to the reactants thereby reducing the effectiveness of the oxidant. We have successfully and effectively solved this problem by placing the denitration chamber immediately behind the pretreatment chamber.

The pretreatment chamber can further eliminate particulate matter (PM) in the flue gas. In order for the chemical reaction to occur without any hindrance, the solution in the chamber should be free of any contaminants. PM can cause turbidity of the solution, which in turn causes problems with denitrification after pretreatment. And PM entering the atmosphere has become a huge problem recently. Therefore, the pretreatment bin can handle this problem in situ. We placed a shower system on the top and side of the chamber to ensure adequate long-term contact between the flue gas and the solution. The flue gas will enter the chamber at an angle, creating a spiral effect when the smoke moves up. Both the shower system and the spiral effect will increase the amount of time the smoke stays inside the chamber. The shower drops are evenly connected; each drop has a diameter of 2 to 3 mm with a spacing of 6 to 10 mm between each drop. This design is to ensure maximum contact between the exhaust gas and the liquid without any back pressure on the exhaust system. Any drop less than 2 mm will be easily carried into the denitration tank by the exhaust force. Cross-contamination reduces the efficiency of the equipment and therefore needs to be avoided.

In the denitration chamber, convert NO ₂ to nitric acid (see Figure 5): In theory, if all NO molecules in the flue gas are completely converted to NO ₂ in the pretreatment chamber (Formula 1), it should be in this denitration tank. Reacts with H ₂ O ₂ to produce HNO ₃ (Formula 2). However, in order to reduce costs, only 5% peroxide (v/v) was placed in the denitration bin. Therefore, a part of NO ₂ molecules may react with water to form HNO ₃ and NO (Formula 3). NO not oxidized by peroxide in the pretreatment tank plus NO produced from Equation 3 will react with HNO ₃ and H ₂ O and produce intermediate HNO ₂ (Formula 4); this intermediate is again with H ₂ O _{2 is} further reacted to form the final product: HNO ₃ plus H ₂ O (Formula 5). Due to the low solubility of NO (Henry constant = 28700 atmospheres / mole) and the complexity of converting NO to NO ₂ and then to HNO ₃ reaction kinetics, the denitrification bin is designed to ensure that the contact time between the flue gas and the solution is extended to the most Long is the most important.

Advantages of the invention: 1. The invention effectively converts nitrogen oxides into nitric acid; therefore, the benefit of the invention is far more than the operating cost of the device itself, and the user can obtain more profits; 2. The invention can The existing systems incorporated into coal-fired power plants are used to improve their effectiveness or completely replace the old systems; 3. The invention can be applied to other industrial markets, including cement plants, steel plants, municipal waste combustion plants, Medical waste burning plant, chlorine gas manufacturing plant, pulp and paper production plant, etc.; 4. The invention has a small footprint and simple transformation, and the manufacturing and operating costs are less than about 50% of the current RSC denitration technology. Under the premise of strictly following the operating procedures, the invention can be used for 15 to 20 years without engineering modification, and can be repaired and maintained in synchronization with the operating coal-fired boiler.

Technical effects of the present invention:

1. The test report of the invention for purifying automobile exhaust gas:

Unit: mg / cubic meter

2. Test report of the invention for purifying boiler exhaust gas:

Unit: mg / cubic meter

3. Test report of the invention for purifying boiler exhaust gas:

Unit: mg / cubic meter

4. The technical effect of the invention for eliminating nitrogen oxides:

(4) Description of the drawings:

1 is a schematic view showing the structure of a pretreatment chamber of two kinds of sprinklers in a nano-flue gas denitration system according to the present invention.

2 is a schematic view showing the structure of a top pressure spray device in a nano-flue gas denitration system according to the present invention.

3 is a schematic structural view of a denitration chamber having a medium-sized gas-liquid mixing channel and a small gas-liquid mixing channel in a nano-flue gas denitration system according to the present invention.

4 is a schematic structural view of a denitration tank having a large gas-liquid mixing passage in a nano-flue gas denitration system according to the present invention.

Figure 5 is a reaction diagram for converting nitrogen oxides to nitric acid in a method for eliminating nitrogen oxides in flue gas according to the present invention.

Among them, 1-1 is the inspection cover, 1-2 is the pretreatment chamber sprinkler system, 1-3 is the funnel-shaped collecting plate, 1-4 is the pre-treatment tank inlet, 1-5 is the sampling port, 1-6 For the pre-treatment tank pump, 1-7 is the accumulator, 1-8 is the pre-treatment tank outlet, 1-9 is the pre-treatment tank level, 1-10 is the pre-treatment tank inlet, 1- 11 is the inspection door, 1-12 is the pre-treatment tank outlet, 1-13 is the pre-treatment tank body, 2-1 is the denitration tank outlet, 2-2 is the denitration tank sprinkler system, 2-3 is the denitration tank Air inlet, 2-4 is the denitration tank inlet, 2-5 is the gas-liquid mixing channel, 2-6 is the denitration tank level, 2-7 is the denitration tank outlet, 2-8 is the denitration tank The water pump, 2-9 is the inspection cover, and 2-10 is the denitration bin body.

(5) Specific implementation methods:

Embodiment 1: A method for eliminating nitrogen oxides in a flue gas, characterized in that it comprises the following steps:

(3) The purified gas is discharged to the denitration vessel.

The oxidant in the pretreatment vessel and the denitration vessel is hydrogen peroxide, and the volume ratio of hydrogen peroxide to water is 1:20.

The gas in the denitration vessel is directly introduced into the liquid and the liquid is sprayed through the shower device in two ways to simultaneously increase the area and time of contact of the flue gas with the liquid.

In the step (1), the concentration of the oxidant is monitored every hour through the liquid outlet, and the oxidant concentration in the solution is stabilized by supplementing the oxidant as needed; the consumption of the hydrogen peroxide is collected by periodically collecting samples. Close monitoring was carried out and the consumption rate of hydrogen peroxide was observed using an iodine/potassium permanganate (I/KMnO4) titration method.

In the step (1), the flue gas enters the pretreatment vessel and enters from the lower portion of the vessel; the direction is horizontal and at an angle of 45 degrees to the vessel wall, so that the flue gas generates a spiral effect when moving upward to increase the time of contact with the liquid.

In the step (2), the solution after the reaction is taken out, and the concentration of the oxidant in the derivatized solution is monitored every hour. According to the monitoring situation, a new solution containing the oxidizing agent is added to keep the solution component in the container stable; the hydrogen peroxide is The consumption was closely monitored by collecting samples periodically, and the consumption rate of hydrogen peroxide was observed using an iodine/potassium permanganate (I/KMnO4) titration method.

A nano-flue gas denitration system (see FIG. 1 and FIG. 3), characterized in that it is composed of a pretreatment chamber and a denitration chamber; an output end of the pretreatment chamber is connected to an input end of the denitration chamber;

The pretreatment bin includes a pretreatment bin body 1-13, a pretreatment bin sprinkler system 1-2, a pretreatment bin air inlet 1-4, a pretreatment bin pump 1-6, and a reservoir 1-7 , pre-treatment tank outlet port 1-8, pre-treatment tank inlet port 1-10 and pre-treatment tank outlet port 1-12; the bottom of the pre-treatment bin body 1-13 is the reservoir 1-7, The pre-treatment tank outlet ports 1-8 are disposed at the accumulator 1-7, the pre-treatment tank inlet ports 1-4, the pre-treatment tank inlet ports 1-10, and the pre-treatment tank outlet ports 1-12 are set. On the pretreatment bin body 1-13 above the accumulator 7, the pretreatment bin outlets 1-12 are above the pretreatment bin inlets 1-4, and the pretreatment bin sprinkler system 1-2 is set In the pretreatment bin body 1-13, the pretreatment bin pump 1-6 is connected to the output end of the accumulator 1-7 and the input end of the pretreatment bin sprinkler system 1-2 through a pipe;

The denitration bin comprises a denitration bin body 2-10, a denitration bin outlet 2-1, a denitration bin sprinkler system 2-2, a denitrification bin inlet 2-3, a denitration bin inlet 2-4, a gas-liquid Mixing channel 2-5, denitration tank outlet port 2-7 and denitrification bin pump 2-8; said denitrification bin inlet port 2-3 and denitrification bin outlet port 2-1 are set in denitrification bin body 2-10 Upper portion; the denitration tank inlet port 2-4 is disposed in the middle of the denitration bin body 2-10; the denitration bin outlet port 2-7 is disposed at the bottom of the denitration bin body 2-10; The liquid mixing channel 2-5 and the denitration chamber spraying system 2-2 are located in the denitration bin body 2-10; the input end of the gas-liquid mixing channel 2-5 is connected to the denitration bin inlet 2-3, and the output end is placed in the denitration The liquid in the warehouse body 2-10; the denitration tank pump 2-8 is connected by piping to the output end of the denitration bin body 2-10 and the input end of the denitration tank sprinkler system 2-2.

An access cover 1-1 is disposed on the top of the pre-treatment bin body 1-13, an access door 1-11 is disposed on the sidewall of the cartridge body 1-13, and a funnel-shaped collecting plate 1-3 is disposed on the top of the accumulator 1-7. Pretreatment tank levelers 1-9 and sampling ports 1-5 are provided on the side walls of the accumulator 1-7. (see picture 1)

The pretreatment chamber sprinkler system 1-2 is a pressure sprinkler device 1-2-1 disposed at the top of the pretreatment bin body 1-13 and a spray disposed on the inner wall of the pretreatment bin body 1-13 Type sprinkler device 1-2-2. (see picture 1)

The spray droplets of the pressurized shower device 1-2-1 are uniform connections; the diameter of each drop is 2 to 3 mm, and the interval between each drop is 8 mm.

The pretreatment bin body 1-13 is made of a stainless steel metal plate.

The pretreatment bin pump 1-6 is an acid resistant water pump.

A denitration tank level device 2-6 is disposed on the side wall of the denitration bin body 2-10, and an access cover 2-9 is disposed at the top of the denitration bin body 2-10. (See Figure 3)

The gas-liquid mixing channel 2-5 includes three medium-sized gas-liquid mixing channels and three small gas-liquid mixing channels. (See Figure 3)

The denitration bin body 2-10 is made of a stainless steel metal plate.

A working method of the above nano-flue gas denitration system, characterized in that it comprises the following steps:

Pretreatment method:

(1) injecting water into the pretreatment bin body 1-13, using nitric acid to adjust the pH to below 3, and then adding an oxidizing agent;

(2) The pretreatment bin pump 1-6 is opened, and the pretreatment bin sprinkler system 1-2 starts to work;

(3) The flue gas enters the pre-treatment silo body 1-13 from the direction of the pre-chamber air inlet 1-4 and the inner wall of the pre-treatment silo body 1-13 into the pre-treatment silo body 1-13, so that the flue gas is in a spiral effect when moving up;

(4) NO in the flue gas reacts with the oxidant to form NO ₂ ;

(5) Periodically collect samples through the sampling port to monitor the consumption of oxidant, and add oxidant to the pre-treatment silo body 1-13 according to the NO content in the flue gas.

Denitration method:

(1) adding an oxidizing agent solution to the denitration bin body 2-10, and the pretreated flue gas enters the gas-liquid mixing channel 2-5 through the inlet port 2-3;

(2) NO ₂ in the flue gas reacts with the oxidant to produce HNO ₃ ;

(3) Regularly collect the sample to monitor the consumption of the oxidant, and add the oxidant to the denitrification bin body 2-10 according to the NO content in the flue gas.

Taking a 15 ton coal-fired boiler that burns about 30 tons of coal per day as an example, the expected diameter and height of the pre-treatment bin are 2.7 meters and 3 meters, respectively. The denitration bin is expected to have a diameter and height of 2.7 meters and 2.25 meters, respectively. The denitration chamber contained 5725 liters of water, 817 liters of 35% H ₂ O ₂ (density 1.135 g/ml, 27 K moles), and 855 liters of 70% nitric acid (density 1.42 g/ml, 13.5 K moles). The consumption of hydrogen peroxide (H ₂ O ₂ ) was closely monitored by hourly sample collection, and the consumption rate of peroxide was observed using an iodine/potassium permanganate (I/KMnO ₄ ) titration method. Based on the NO content in the flue gas, the metering pump will replenish the peroxide from the reservoir to the bin. The present invention is capable of removing 90% of NOx from flue gas. The NOx concentration in the flue gas fluctuates between 50 ppm and 120 ppm depending on the temperature of the on-site boiler. Usually, if the combustion temperature of the boiler exceeds 900 degrees Celsius, the concentration of NOx in the flue gas easily exceeds 200 ppm.

Embodiment 2: A method for eliminating nitrogen oxides in flue gas, characterized in that it comprises the following steps:

(3) The purified gas is discharged to the denitration vessel.

The oxidant in the pretreatment vessel is hydrogen peroxide, and the volume ratio of hydrogen peroxide to water is 1:18.

The oxidizing agent in the denitration vessel is a mixture of magnesium oxide and magnesium hydroxide. The diameter of the magnesium oxide and magnesium hydroxide solid particles is less than 20 nm, the molar ratio of magnesium oxide to magnesium hydroxide is 1:1, and the amount of magnesium oxide and water is used. When the ratio is 10 mol/L, the ratio of magnesium hydroxide to water is equal to 10 mol/L.

The gas in the denitration vessel is directly introduced into the liquid, and the liquid is sprayed out through the shower device in two ways to increase the area and time of contact of the flue gas with the liquid.

The step (1) monitors the concentration of the oxidant every 8 hours through the liquid outlet, and supplements the oxidant to stabilize the concentration of the oxidant in the solution as needed; the consumption of the hydrogen peroxide is closely monitored by periodically collecting samples, and iodine is used. / Potassium permanganate (I/KMnO4) titration method to observe the consumption rate of hydrogen peroxide.

A nano-flue gas denitration system (see Fig. 2, Fig. 4), characterized in that it is composed of a pretreatment chamber and a denitration chamber; an output end of the pretreatment chamber is connected to an input end of the denitration chamber;

An access cover 1-1 is disposed on the top of the pre-treatment bin body 1-13, an access door 1-11 is disposed on the sidewall of the cartridge body 1-13, and a funnel-shaped collecting plate 1-3 is disposed on the top of the accumulator 1-7. Pretreatment tank levelers 1-9 and sampling ports 1-5 are provided on the side walls of the accumulator 1-7. (See Figure 2)

The pretreatment chamber sprinkler system 1-2 is a pressurized sprinkler device 1-2-1 disposed at the top of the pretreatment bin body 1-13. (See Figure 2)

The spray droplets of the pressurized shower device 1-2-1 are uniform connections; each droplet has a diameter of 2 to 3 mm, and each droplet is spaced 10 mm apart.

The pretreatment bin body 1-13 is made of a stainless steel metal plate.

The pretreatment bin pump 1-6 is an acid resistant water pump.

A denitration tank level device 2-6 is disposed on the side wall of the denitration bin body 2-10, and an access cover 2-9 is disposed at the top of the denitration bin body 2-10. (See Figure 4)

The gas-liquid mixing channel 2-5 includes five large mixing channels. (See Figure 4)

The denitration bin body 2-10 is made of a stainless steel metal plate.

Pretreatment method:

(4) NO in the flue gas reacts with the oxidant to form NO ₂ ;

When the oxidizing agent was hydrogen peroxide, the consumption of hydrogen peroxide was closely monitored by sample collection every 8 hours, and the consumption rate of peroxide was observed using an iodine/potassium permanganate (I/KMnO4) titration method.

Denitration method:

(2) NO ₂ in the flue gas reacts with the oxidant to produce HNO ₃ ;

Claims

A method for eliminating nitrogen oxides in flue gas, characterized in that it comprises the following steps:

(1) The nitrogen oxide-containing flue gas is pretreated in a pretreatment vessel, and the pretreatment process removes solid particles having a diameter larger than 10 μm in the flue gas and oxidizes NO to NO 2 :

Adding a solution containing an oxidizing agent and having a pH of 3 or less to the pretreatment vessel;

The flue gas is introduced into the pretreatment vessel, and is sufficiently contacted with the liquid to leave solid particles having a diameter larger than 10 μm in the solution, and NO is oxidized to NO 2 ;

Exporting the solution containing the solid particles to the pretreatment vessel;

(2) The pretreated flue gas enters the denitration vessel, and the nitrogen oxide reacts with the oxidant to form nitric acid:

Adding a solution containing an oxidizing agent and having a pH of 3 or less to the denitration vessel;

The pretreated flue gas is introduced into the denitration vessel and fully reacted with the oxidant to form nitric acid;

(3) The purified gas is discharged to the denitration vessel.
A method of eliminating nitrogen oxides in a flue gas according to claim 1, wherein the pretreatment vessel and the denitration vessel are first adjusted to a pH of 3 or less using nitric acid, and then an oxidizing agent is added.
A method for eliminating nitrogen oxides in a flue gas according to claim 1, wherein the oxidizing agent in the pretreatment vessel and the denitration vessel is a mixture of hydrogen peroxide, molybdenum oxide and tungsten oxide, magnesium oxide and hydroxide. a mixture of magnesium or ferric oxide, wherein the solid particles of molybdenum oxide, tungsten oxide, magnesium oxide, magnesium hydroxide and ferric oxide have a diameter of less than 20 nm, and the volume ratio of hydrogen peroxide to water is 1:18 to 22, The molar ratio of molybdenum oxide to tungsten oxide is 1:1, the molar ratio of magnesium oxide to magnesium hydroxide is 1:1, the ratio of molybdenum oxide to water is 10 mol/L, and the ratio of tungsten oxide to water is 10 mol or more. /L, the ratio of magnesium oxide to water is 10 mol/L, the ratio of magnesium hydroxide to water is 10 mol/L, and the ratio of ferric oxide to water is 20 mol/L or more.
A method of eliminating nitrogen oxides in a flue gas according to claim 3, wherein said hydrogen peroxide is produced by reacting magnesium peroxide, sodium peroxide or calcium peroxide having a diameter of less than 50 nm in water.
A method of eliminating nitrogen oxides in a flue gas according to claim 1, wherein the liquid in said pretreatment vessel is ejected through a sprinkler to increase the area and time of contact of the flue gas with the liquid.
A method for eliminating nitrogen oxides in a flue gas according to claim 1, wherein the gas in the denitration vessel is directly introduced into the liquid to increase the area and time of contact of the flue gas with the liquid, or the liquid is sprayed through the shower device. To increase the area and time of exposure of the flue gas to the liquid; or to use both methods simultaneously.
A method for eliminating nitrogen oxides in a flue gas according to claim 1, wherein when hydrogen peroxide is used as the oxidant in the step (1), the concentration of the oxidant is periodically monitored through the liquid outlet, and It is necessary to supplement the oxidizing agent to stabilize the concentration of the oxidizing agent in the solution; the consumption of the hydrogen peroxide is closely monitored by periodically collecting the sample, and the consumption rate of hydrogen peroxide is observed using an iodine/potassium permanganate (I/KMnO4) titration method.
A method for eliminating nitrogen oxides in a flue gas according to claim 1, wherein in the step (1), the flue gas enters the pretreatment vessel and enters from the lower portion of the vessel; the direction is horizontal and is 40 to 50 with the vessel wall. The angle of the angle causes the smoke to produce a spiral effect when moving upwards to increase the time of contact with the liquid.
A method for eliminating nitrogen oxides in a flue gas according to claim 1, wherein the liquid flowing out of the pretreatment vessel in the step (1) is transported by a water pump to a pretreatment after removal of particles larger than 10 micrometers. The spray device of the container.
A method for eliminating nitrogen oxides in a flue gas according to claim 1, wherein in the step (2), the solution after the reaction is derived, and when hydrogen peroxide is used as the oxidant, the oxidant in the solution is periodically monitored and derived. The concentration, depending on the condition of the monitoring, adds a new solution containing the oxidizing agent to keep the composition of the solution in the container stable; the consumption of hydrogen peroxide is closely monitored by collecting samples periodically, and using iodine/potassium permanganate (I) /KMnO4) The titration method was used to observe the consumption rate of hydrogen peroxide.
A method for eliminating nitrogen oxides in a flue gas according to claim 1, wherein the solution in the step (2) is transported by a water pump through a pipe to a shower device of the denitration vessel.
A nano-smoke denitration system for realizing a method for eliminating nitrogen oxides in flue gas, characterized in that it is composed of a pretreatment chamber and a denitration chamber; an output end of the pretreatment chamber is connected to an input end of the denitration chamber;

The pretreatment bin includes a pretreatment bin body, a pretreatment bin sprinkler system, a pretreatment bin inlet, a pretreatment bin pump, a reservoir, a pretreatment bin outlet, a pretreatment bin inlet, and Pre-processing the gas outlet of the warehouse; the bottom of the pre-treatment silo body is a liquid storage device, and the liquid outlet of the pre-treatment chamber is disposed at the liquid storage device, the air inlet of the pre-treatment chamber, the liquid inlet of the pre-treatment chamber, and the pre-treatment The treatment chamber outlet is disposed on the pretreatment bin body above the reservoir, and the pretreatment chamber outlet is above the inlet of the pretreatment chamber, the pretreatment The warehouse sprinkler system is disposed in the pretreatment bin, and the pretreatment bin pump is connected to the output end of the accumulator and the input end of the pretreatment bin sprinkler system through a pipeline;

The denitration bin comprises a denitration bin body, a denitration bin outlet, a denitration bin sprinkler system, a denitration bin inlet, a denitration bin inlet, a gas-liquid mixing channel, a denitration bin outlet, and a denitration tank pump; The denitration tank inlet port and the denitration tank outlet port are disposed at an upper portion of the denitration bin body; the denitration bin inlet port is disposed at a middle portion of the denitration bin body; the denitration bin outlet port is disposed in the denitration bin body The gas-liquid mixing channel and the denitration chamber spraying system are located in the denitration bin; the input end of the gas-liquid mixing channel is connected to the denitration port inlet, and the output end is placed in the liquid in the denitration bin; the denitration bin The pump is connected to the output of the bottom of the denitration bin and the input of the denitration sprinkler system through a pipe.
A nano-flue gas denitration system according to claim 12, characterized in that the top of the pre-treatment silo body is provided with an access cover, an access door is arranged on the side wall of the storage body, and a funnel-shaped collecting plate is arranged on the top of the liquid storage device. A pre-treatment tank leveler and a sampling port are arranged on the side wall of the liquid device.
A nano-flue gas denitration system according to claim 12, wherein said pretreatment chamber sprinkler system is a pressurized sprinkler device disposed at the top of the pretreatment bin, or is disposed in the pretreatment bin The top pressure spray device and the spray sprinkler disposed on the inner wall of the pretreatment bin.
A nano-flue gas denitration system according to claim 14, wherein the spray droplets of the pressurized shower device are uniformly connected; each droplet has a diameter of 2 to 3 mm, and each drop The interval is 6 to 10 mm.
A nano-flue gas denitration system according to claim 12, wherein said pre-treatment silo body is made of a stainless steel metal plate.
A nano-flue gas denitration system according to claim 12, wherein said pre-treatment tank pump is an acid-resistant water pump.
A nano-flue gas denitration system according to claim 12, wherein a denitration tank level device is arranged on the side wall of the denitration bin body, and an inspection cover is arranged on the top of the denitration bin body.
A nano-flue gas denitration system according to claim 12, wherein said gas-liquid mixing channel comprises three medium-sized gas-liquid mixing channels and three small-sized gas-liquid mixing channels, or five large mixing channels.
A nano-flue gas denitration system according to claim 12, wherein said denitration bin body is made of a stainless steel metal plate.