A method for purifying nitrogen oxide waste gas using a solid-phase liquid membrane method

Abstract

The present invention discloses a method for purifying nitrogen oxide waste gas by solid phase liquid membrane method, which comprises: x Flue gas is partially oxidized by ozone, ClO2 or O2 to reduce NO x The components are converted into a certain proportion of NO2-NO mixed flue gas, which is then passed into an absorption bed filled with an absorbent material to absorb and remove nitrogen oxides. The absorbent material is loaded with an absorption liquid membrane, including a porous solid-phase material and a liquid membrane. The mass ratio (solid-to-liquid ratio) of the porous solid-phase material to the liquid membrane is 1:0.05-10. The liquid membrane is mainly composed of three parts: a pH regulator, a liquid film forming agent, and a liquid film stabilizer. The pH regulator includes an organic base and an inorganic base, the liquid film stabilizer includes urea, and the liquid film forming agent includes water and a C1-C4 lower alcohol. The present invention provides a liquid-phase absorption purification method for industrial nitrogen oxide flue gas. This method has the advantages of high low-temperature denitrification efficiency, simple operation, economic feasibility, environmental protection and safety, and has great prospects in industrial denitrification.

Description

Technical Field

[0001] The present invention relates to the technical field of nitrogen oxide treatment in flue gas, and in particular to a method for purifying nitrogen oxide waste gas using a solid-phase liquid membrane method. Background Art

[0002] Nitrogen oxides (NO x ) Waste gas is one of the main pollutants of air pollution, which can cause acid rain and photochemical smog, causing varying degrees of harm to human health and the living environment. In order to reduce air pollution, China has issued and implemented the control of NO x Relevant policies and standards for pollutant emissions, including NO x The emission requirements are becoming increasingly stringent. The Ministry of Environmental Protection issued the "Work Plan for Comprehensively Implementing Ultra-low Emission and Energy-saving Transformation of Coal-fired Power Plants", which proposed that the nitrogen oxide emission concentration of coal-fired power plants that meet the transformation conditions should reach 50mg / m 3 Therefore, it is necessary to carry out efficient denitrification of nitrogen oxide waste gas in industry, which is of great significance to improving environmental quality and practicing the concept of green development.

[0003] Existing denitrification technologies are primarily categorized as dry and wet methods. Dry methods include selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR), a combination of selective non-catalytic reduction and selective catalytic reduction (SNCR-SCR), activated carbon, and plasma. Wet methods include alkaline absorption, acid absorption, complex absorption, reduction absorption, and oxidation absorption. Currently, the most widely used dry denitrification technology in industry is the SCR method, which involves spraying liquid ammonia solution into high-temperature flue gas and then reducing nitrogen oxides in the flue gas to N2 under the action of a catalyst. Wet denitrification technology, on the other hand, primarily relies on oxidation absorption, which chemically oxidizes NO in the flue gas into water-soluble, high-valent nitrogen oxides for liquid absorption.

[0004] According to the temperature range of industrial flue gas, flue gas can be divided into high-temperature flue gas (450-800℃), medium-temperature flue gas (300-450℃), medium-low temperature flue gas (160-300℃), low-temperature flue gas (60-160℃) and ultra-low temperature flue gas (20-60℃).

[0005] For high-temperature flue gas, the SNCR method is generally used; for medium-temperature and medium-low-temperature flue gas, the SCR method is generally used; for low-temperature and ultra-low-temperature flue gas (<160°C), if the flue gas temperature is raised by SCR (SCR requires the flue gas temperature to be greater than 160°C), it will greatly increase energy consumption. Wet oxidation absorption technology is a relatively feasible low-temperature denitrification technology, but the absorption liquid of wet denitrification technology is easy to volatilize, resulting in reduced efficiency. In addition, wet denitrification has high equipment requirements and its efficiency is limited due to the influence of gas-liquid mass transfer. Therefore, neither SCR nor wet oxidation denitrification technology can effectively solve the problem of low-temperature denitrification. Efficient denitrification of low-temperature flue gas is a bottleneck problem that urgently needs to be solved.

[0006] For room temperature flue gas, Chinese invention patent CN 103977680A discloses a low-concentration NO2 filter for semi-enclosed spaces such as road tunnels and underground parking lots. x Denitrification method for pollutants, low concentration NO x After the high-performance NO2 room-temperature oxidation catalyst is used, it is absorbed by a solid alkaline absorbent. However, the efficiency of this technology is around 10-40%, which is low and has not been applied. Patent publication number CN 104190223 A provides a liquid-phase oxidation flue gas desulfurization and denitrification absorption process and device, which uses a three-stage absorption method to remove nitrogen oxides from flue gas. The first stage is pre-washed to avoid SO2 consumption of the oxidant. The second stage uses ozone and other oxidants for oxidation absorption. However, the third stage only uses a single alkaline absorption liquid for absorption, and the denitrification efficiency is only 85%. The outlet concentration of nitrogen oxides reaches 300mg / m 3 Patent publication number CN 1768902A provides a method for denitrification of boiler flue gas by ozone oxidation. The method involves first oxidizing ozone with NO in the boiler to form highly soluble water-soluble high-valent nitrogen oxides, which are then absorbed by alkaline solution. However, the utilization rate of the alkaline solution absorbent in this process is low, resulting in a denitrification efficiency of less than 80%.

[0007] To sum up, in order to focus on solving the technical difficulties of low-temperature flue gas denitrification, the patent of this invention has developed a solid-phase liquid membrane absorption technology that can efficiently purify nitrogen oxide waste gas at low temperatures (<160°C). While making up for the shortcomings of existing technologies, it has high denitrification efficiency, strong economic applicability, and easy operation, and has a relatively broad application prospect. Summary of the Invention

[0008] The purpose of the present invention is to provide a solid-phase liquid membrane method for efficiently purifying nitrogen oxide waste gas at low flue gas temperature (<160°C). NO is partially oxidized to NO2 by oxidation, and then absorbed by a high-specific-surface-area solid material containing an absorption liquid membrane on its surface, so that the emission concentration of nitrogen oxides reaches 50mg / m 3 the following.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A method for purifying nitrogen oxide waste gas by a solid-phase liquid membrane method comprises the following steps:

[0011] (1) NO with different initial concentrations x Flue gas will contain NO x The flue gas is continuously passed into the flue gas oxidation device, and the NO is oxidized by ozone (O3), ClO2, and O2 in the flue gas. x The flue gas is partially oxidized into a certain proportion of NO2-NO mixed flue gas;

[0012] (2) NO after oxidation x The flue gas is absorbed and removed by the absorption bed filled with absorption material. The absorption material is a porous solid material combined with a liquid film. x Concentration, different temperatures, different absorption space velocities, different absorbent solid-liquid ratios, different absorbents are used for absorption, and the flue gas after absorption meets the emission conditions and is discharged;

[0013] (3) The porous solid material combined with the liquid membrane is mainly composed of a liquid membrane with absorption properties combined with a porous solid phase material, and the mass ratio of the porous solid phase material to the liquid membrane (solid-liquid ratio) is 1:0.05-10;

[0014] (4) The absorption liquid film is formed by combining a pH regulator, a liquid film forming agent, and a liquid film stabilizer. x Composite solution with strong absorption capacity;

[0015] (5) The pH regulator accounts for 2 to 8% of the total mass of the liquid membrane and is mainly composed of inorganic bases and organic bases, wherein the inorganic bases mainly include: one or more of NaOH, Na2CO3, KOH, K2CO3, Na2S, etc.; the organic bases mainly include: one or more of organic amines such as ethanolamine, diethanolamine, and triethanolamine.

[0016] (6) The liquid film forming agent mainly comprises water and a C1-C4 lower alcohol, wherein the C1-C4 lower alcohol is one or more of ethylene glycol, propylene glycol, glycerol, butylene glycol, etc. The mass ratio of water to the C1-C4 lower alcohol is 1:0.05-0.5.

[0017] (7) The liquid film stabilizer accounts for 0.5-4% of the total mass of the liquid film, and mainly includes: urea and additives. The additives are selected from one or more of NaCl, CaCl2, NaHCO3, EDTA, Na2SO3, etc. The liquid film stabilizer must contain urea, and other one or more can be added to improve the absorption of NOx stability.

[0018] (8) The porous liquid membrane immobilization carrier mainly includes porous materials such as activated carbon, macroporous resin, molecular sieve or porous alumina beads, and its specific surface area is greater than 50m 2 / g, the material needs to have good microporous and mesoporous structure.

[0019] Furthermore, the combination of a pH regulator, a liquid film forming agent, and a liquid film stabilizer is used to x The composite solution with absorption capacity is combined with the porous carrier, so that the anions on the surface are combined with the carrier to form a uniformly dispersed liquid film on the surface. This liquid film is the main absorption material. The porous liquid film immobilized carrier is used to capture NO in the gas phase. x components and are absorbed and removed through the liquid membrane.

[0020] According to the present invention, the liquid film components used include a plurality of pH adjusters, a plurality of liquid film forming agents, and a plurality of liquid film stabilizers.

[0021] According to the present invention, the preferred pH adjuster is a combination of an organic base and an inorganic base. The inorganic base can adjust the pH more quickly, while the organic base can combine with the liquid film forming agent while adjusting the pH to form a more stable liquid film structure. The most preferred absorbing components are a pH adjuster formed by three substances: NaOH, Na2S, and ethanolamine. The total weight of the pH adjuster accounts for 1% to 6% of the total weight of the liquid film, preferably 4.8% to 5.5%.

[0022] According to the present invention, the addition of a liquid film stabilizer can improve the stability of the liquid film, thereby increasing the absorption efficiency and effective absorption time. Urea can significantly enhance the stability of the absorbent. The most preferred liquid film stabilizer is a mixture of urea and NaHCO3, with the mass ratio of urea to additive being 1:0.3-2, preferably 1:0.5-1. The total mass of the liquid film stabilizer accounts for 1-2% of the total mass of the liquid film.

[0023] According to the present invention, the preferred liquid film forming agent is a mixed solution of water and C1-C4 lower alcohols, with the mass ratio of the two being 1:0.2 to 1:5 (water:polyol, mass ratio), preferably 1:0.1 to 0.3, and more preferably 1:0.2. Among them, the most preferred is a mixed solution of water and propylene glycol.

[0024] According to the present invention, the specific surface area used in the invention is> 50m 2 / g, porous materials with good microporous and mesoporous structures. In addition to the role of immobilized liquid membrane, the carrier also has the function of using porous materials for capture and combining with liquid membrane for absorption. In the absorption process, it plays a very important role. In actual operation, the preferred specific surface area is> 500m 2 / g, the most preferred specific surface area is >1,000m 2 / g.

[0025] Furthermore, after passing through the flue gas oxidation device, the volume ratio of NO2 / NO in the flue gas is 1:10 to 1:0.01, and there is no escape of the oxidant, thus avoiding secondary pollution.

[0026] Furthermore, NO x The main components of flue gas removed are NO and NO2. The initial NO x Concentration ranges from 10 to 2,000 mg / m 3 .

[0027] According to the present invention, preferably, the volume ratio of NO2 / NO in the flue gas is 1:5 to 1:0.1, more preferably 1:1 to 0.1. x The concentration is preferably 50 to 1500 mg / m 3 , more preferably 50 to 500 mg / m 3 .

[0028] Furthermore, the absorption temperature is 0-160°C and the absorption space velocity is 1,000h -1 ~1,000,000h -1 .

[0029] Furthermore, the mass ratio of the porous solid phase material to the liquid membrane (solid-liquid ratio) is 1:0.05-10, preferably 1:0.05-5.

[0030] According to the present invention, preferably, the absorption temperature is 40-120°C.

[0031] According to the present invention, preferably, the absorption space velocity is 1,000h -1 ~200,000h -1 .

[0032] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0033] (1) Solid-phase liquid membrane method: solid and liquid are combined to remove nitrogen oxides, which makes up for the shortcomings of single solid and single liquid in terms of efficiency, applicable temperature, cost, etc., and can treat nitrogen oxide waste gas at a relatively low temperature (0-160℃), achieving a removal efficiency of more than 95%, reducing the emission concentration of nitrogen oxides to 50mg / m 3Below, meet the requirements of ultra-low emissions.

[0034] (2) Industrial applicability and strong adaptability: The equipment requirements are low, and the denitrification efficiency is less affected by the changes in the device. It avoids the poor industrial applicability caused by the influence of gas-liquid mass transfer on the efficiency in wet denitrification, and is applicable to most NO-containing products that need denitrification. x smoke.

[0035] The present invention provides a liquid-phase absorption purification method for industrial nitrogen oxide flue gas, which has the advantages of high low-temperature denitrification efficiency, simple operation, economic feasibility, greenness and safety, and has great prospects in industrial denitrification. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the pore size distribution diagram of the porous liquid membrane immobilized carrier - activated carbon. DETAILED DESCRIPTION

[0037] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0038] Example:

[0039] In the embodiment of the present invention, a porous solid material combined with a liquid membrane is used as an absorbent to efficiently remove nitrogen oxides in flue gas at a relatively low temperature (0 to 160° C.).

[0040] A method for purifying nitrogen oxide waste gas using a solid-phase liquid membrane method according to an embodiment of the present invention comprises the following steps:

[0041] The present invention is further described below by means of specific examples, but the protection scope of the present invention is not limited thereto.

[0042] (1) Contains NO x The flue gas is introduced into the flue gas oxidation device, and a certain amount of ozone (O3) is introduced at the same time to reduce the NO in the flue gas. x Perform partial oxidation;

[0043] (2) NO after oxidation x Flue gas passes through the absorption bed to undergo absorption and denitrification;

[0044] (3) Use a flue gas analyzer to detect the concentration C at the flue entrance in , the concentration at the flue outlet C out , calculate the concentration difference, and use Equation 1 to calculate the absorption efficiency;

[0045] (4) The flue gas after denitrification meets the emission requirements and is discharged through the flue outlet.

[0046] (5) Change the composition of the liquid film, the porous liquid film immobilization carrier, change the NO2-NO ratio, different NO x The absorption is carried out under different concentrations, different temperatures, different absorption space velocities, different absorbent solid-liquid ratios, and different absorbents to test the absorption capacity of the porous material with liquid film on different flue gases.

[0047] The porous liquid membrane immobilized carrier used in this embodiment includes porous materials such as activated carbon, macroporous resin, molecular sieve or porous alumina beads, and its specific surface area is greater than 50m 2 / g, the material needs to have good microporous and mesoporous structure. Among them, activated carbon is used, which has microporous or mesoporous structure, the pore size distribution is concentrated in 1~3nm, and the specific surface area is 887.4m 2 / g, and the average pore diameter is 1.88nm. Figure 1 This is the pore size distribution diagram of the porous liquid membrane immobilized carrier - activated carbon (AC).

[0048]

[0049] η: Absorption efficiency (%), C in : Imported NO measured at the flue inlet x Concentration (mg / m 3 ), C out : Imported NO measured at the flue inlet x Concentration (mg / m 3 ).

[0050] Example 1

[0051] Containing NO x Concentration is 500mg / m 3 As an example, the flue gas is fed into the flue gas oxidation device and 660mg / m 3 The O3 is oxidized, and the volume ratio of NO2 to NO after oxidation is 1:0.2. The oxidized flue gas is passed into the absorption tower, passes through the absorption bed, and reacts with the porous material with a liquid film. The liquid film supported on the porous material is composed of three parts: pH regulator, liquid film forming agent, and liquid film stabilizer.

[0052] The pH regulator is composed of inorganic bases and organic bases, wherein the inorganic bases mainly include one or more of NaOH, Na2CO3, KOH, K2CO3, Na2S, etc., and the organic bases mainly include one or more of ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, etc., and the components are added in equal mass ratios, and the pH regulator accounts for 5% of the total mass of the liquid film. The liquid film forming agent is exemplified by water and propylene glycol (mass ratio = 1:0.2). The liquid film stabilizer is exemplified by urea and NaHCO3, accounting for 2% of the total mass of the liquid film, and the components are added in equal mass ratios. The porous liquid film immobilized carrier is exemplified by activated carbon; at 80°C and absorption space velocity = 50,000h -1 The absorption was carried out under the conditions of 1:0.5 (i.e., the mass ratio of porous material to liquid membrane is 1:0.5, the same below) and the NO in the inlet and outlet were detected and analyzed using a flue gas analyzer (Testo 350). x concentration and calculate the absorption efficiency.

[0053] Table 1 Purification efficiency of different inorganic base pH regulators

[0054]

[0055]

[0056] Table 2 Purification efficiency of different organic base pH regulators

[0057]

[0058] Example 2

[0059] Containing NO x Concentration is 500mg / m 3 As an example, the flue gas is fed into the flue gas oxidation device and 660mg / m 3 The O3 is oxidized, and the volume ratio of NO2 to NO after oxidation is 1:0.2. The oxidized flue gas is passed into the absorption tower, passes through the absorption bed, and reacts with the porous material with a liquid film. The liquid film supported on the porous material is composed of three parts: pH regulator, liquid film forming agent, and liquid film stabilizer.

[0060] The pH regulators are exemplified by NaOH, Na2S, and ethanolamine, which account for 5% of the total mass of the liquid film and are added in equal mass ratios. The liquid film forming agent is composed of water and one or more of C1-C4 lower alcohols such as ethylene glycol, propylene glycol, glycerol, and butanediol, wherein the liquid film forming agent after the mixture of water and C1-C4 lower alcohols is water and C1-C4 lower alcohols (mass ratio = 1:0.2). The liquid film stabilizers are exemplified by urea and NaHCO3, which account for 2% of the total mass of the liquid film and are added in equal mass ratios. The porous liquid film immobilized carrier is exemplified by activated carbon; at 80°C and absorption space velocity = 50,000h -1 The absorption was carried out under the condition of solid-liquid ratio of absorbent = 1:0.5, and the NO in the inlet and outlet were detected and analyzed using a flue gas analyzer (Testo 350). x concentration and calculate the absorption efficiency.

[0061] Table 3 Purification efficiency of different liquid film forming agents

[0062]

[0063] Example 3

[0064] Containing NO x Concentration is 500mg / m 3 As an example, the flue gas is introduced into the flue gas oxidation device and 660mg / m 3 The O3 is oxidized, and the volume ratio of NO2 / NO after oxidation is 1:0.2. The oxidized flue gas is introduced into the absorption tower, passes through the absorption bed, and reacts and absorbs with the porous material with a liquid film; the liquid film loaded on the porous material is composed of three parts: pH regulator, liquid film forming agent and liquid film stabilizer.

[0065] The pH regulator is exemplified by NaOH, Na2S, and ethanolamine, which account for 5% of the total mass of the liquid film, and are added in equal mass ratios. The liquid film forming agent is exemplified by water and propylene glycol (mass ratio = 1:0.2). The liquid film stabilizer is urea, or urea and one or more of NaCl, CaCl2, NaHCO3, EDTA, and Na2SO3, wherein the liquid film stabilizer accounts for 2% of the total mass of the liquid film, and are added in equal mass ratios. The porous liquid film immobilization carrier is exemplified by activated carbon; at 80°C and absorption space velocity = 50,000h -1 The absorption was carried out under the condition of solid-liquid ratio of absorbent = 1:0.5, and the NO in the inlet and outlet were detected and analyzed using a flue gas analyzer (Testo 350). x concentration and calculate the absorption efficiency.

[0066] Table 4 Purification efficiency of different liquid film stabilizers

[0067]

[0068] Example 4

[0069] Containing NO x Concentration is 500mg / m 3 As an example, the flue gas is fed into the flue gas oxidation device and 660mg / m 3 The O3 is oxidized, and the volume ratio of NO2 / NO after oxidation is 1:0.2. The oxidized flue gas is introduced into the absorption tower, passes through the absorption bed, and reacts and absorbs with the porous material with a liquid film; the liquid film loaded on the porous material is composed of three parts: pH regulator, liquid film forming agent and liquid film stabilizer.

[0070] The pH regulators are exemplified by NaOH, Na2S, and ethanolamine, which account for 5% of the total mass of the liquid membrane and are added in equal mass ratios. The liquid membrane forming agent is exemplified by water and propylene glycol (mass ratio = 1:0.2). The liquid membrane stabilizers are exemplified by urea and NaHCO3, which account for 2% of the total mass of the liquid membrane and are added in equal mass ratios. The porous liquid membrane immobilization carriers are selected from: activated carbon, macroporous resin, molecular sieve, and porous alumina beads; at 80°C and absorption space velocity = 50,000h -1 The absorption was carried out under the condition of solid-liquid ratio of absorbent = 1:0.5, and the NO in the inlet and outlet were detected and analyzed using a flue gas analyzer (Testo 350). x concentration and calculate the absorption efficiency.

[0071] Table 5 Purification efficiency of different porous liquid membrane immobilized carriers

[0072]

[0073] Example 5

[0074] Containing NO x Concentration is 500mg / m 3 As an example, the flue gas is fed into the flue gas oxidation device and 660mg / m 3 The O3 is oxidized, and the volume ratio of NO2 to NO after oxidation is 1:0.2. The oxidized flue gas is passed into the absorption tower, passes through the absorption bed, and reacts with the porous material with a liquid film. The liquid film supported on the porous material is composed of three parts: pH regulator, liquid film forming agent, and liquid film stabilizer.

[0075] The pH regulators are exemplified by NaOH, Na2S, and ethanolamine, which account for 5% of the total mass of the liquid membrane and are added in equal mass ratios. The liquid membrane forming agent is exemplified by water and propylene glycol (mass ratio = 1:0.2). The liquid membrane stabilizers are exemplified by urea and NaHCO3, which account for 2% of the total mass of the liquid membrane and are added in equal mass ratios. The porous liquid membrane immobilization carrier is exemplified by activated carbon; at temperatures of 0, 20, 40, 80, 120, and 160°C, the absorption space velocity is 50,000h -1 The absorption was carried out under the condition of solid-liquid ratio of absorbent = 1:0.5, and the NO in the inlet and outlet were detected and analyzed using a flue gas analyzer (Testo 350). x concentration and calculate the absorption efficiency.

[0076] Table 6 Purification efficiency at different temperatures

[0077]

[0078] Example 6

[0079] Use NO x The concentrations are 10, 50, 100, 250, 500, 1,000, 1,500, and 2,000 mg / m 3 The flue gas was fed into the flue gas oxidation device, with the concentrations of 13.2, 66, 132, 330, 660, 1,320, 1,980, and 2,640 mg / m 3 The O3 is oxidized, and the volume ratio of NO2 / NO after oxidation is 1:0.2. The oxidized flue gas is introduced into the absorption tower, passes through the absorption bed, and reacts and absorbs with the porous material with a liquid film; the liquid film loaded on the porous material is composed of three parts: pH regulator, liquid film forming agent and liquid film stabilizer.

[0080] The pH regulator is exemplified by NaOH, Na2S, and ethanolamine, which account for 5% of the total mass of the liquid membrane and are added in equal mass ratios. The liquid membrane forming agent is exemplified by water and propylene glycol (mass ratio = 1:0.2). The liquid membrane stabilizer is exemplified by urea and NaHCO3, which account for 2% of the total mass of the liquid membrane and are added in equal mass ratios. The porous liquid membrane immobilization carrier is exemplified by activated carbon; at 80°C and absorption space velocity = 50,000h -1 The absorption was carried out under the condition of solid-liquid ratio of absorbent = 1:0.5, and the NO in the inlet and outlet were detected and analyzed using a flue gas analyzer (Testo 350). x concentration and calculate the absorption efficiency.

[0081] Table 7 Different initial NO x Purification efficiency at concentration

[0082]

[0083] Example 7

[0084] Containing NO x Concentration is 500mg / m 3 As an example, the flue gas of 10000 tons was introduced into the flue gas oxidation device. The volume ratios of NO2 / NO after oxidation were 1:100, 1:50, 1:25, 1:10, 1:5, 1:1, 1:0.5, 1:0.2, 1:0.1, 1:0.05, 1:0.02 and 1:0.01, respectively. The concentrations of 8, 16, 32, 72, 133, 400, 530, 660, 730, 760, 780 and 800 mg / m 3 The O3 is oxidized and then passed into the absorption tower. After passing through the absorption bed, the flue gas reacts and absorbs with the porous material with a liquid film. The liquid film supported on the porous material is composed of three parts: pH regulator, liquid film forming agent and liquid film stabilizer.

[0085] The pH regulator is exemplified by NaOH, Na2S, and ethanolamine, which account for 5% of the total mass of the liquid membrane and are added in equal mass ratios. The liquid membrane forming agent is exemplified by water and propylene glycol (mass ratio = 1:0.2). The liquid membrane stabilizer is exemplified by urea and NaHCO3, which account for 2% of the total mass of the liquid membrane and are added in equal mass ratios. The porous liquid membrane immobilization carrier is exemplified by activated carbon; at 80°C and absorption space velocity = 50,000h -1 The absorption was carried out under the condition of solid-liquid ratio of absorbent = 1:0.5, and the NO in the inlet and outlet were detected and analyzed using a flue gas analyzer (Testo 350). x concentration and calculate the absorption efficiency.

[0086] Table 8 Purification efficiency under different NO2 / NO (different oxidation degrees)

[0087]

[0088] Example 8

[0089] Containing NO x Concentration is 500mg / m 3 As an example, the flue gas is fed into the flue gas oxidation device and 660mg / m 3 The O3 is oxidized, and the volume ratio of NO2 to NO after oxidation is 1:0.2. The oxidized flue gas is passed into the absorption tower, passes through the absorption bed, and reacts with the porous material with a liquid film. The liquid film supported on the porous material is composed of three parts: pH regulator, liquid film forming agent, and liquid film stabilizer.

[0090] The pH regulators are exemplified by NaOH, Na2S and ethanolamine, which account for 5% of the total mass of the liquid membrane and are added in equal mass ratios. The liquid membrane forming agents are exemplified by water and propylene glycol (mass ratio = 1:0.2). The liquid membrane stabilizers are exemplified by urea and NaHCO3, which account for 2% of the total mass of the liquid membrane and are added in equal mass ratios. The porous liquid membrane immobilized carrier is exemplified by activated carbon; the absorption space velocities are 1,000, 2,500, 5,000, 10,000, 25,000, 50,000, 100,000, 250,000, 500,000, 1,000,000, h-1, respectively. -1 The absorption was carried out under the conditions of 80℃ and absorbent solid-liquid ratio = 1:0.5. The NO in the inlet and outlet were detected and analyzed using a flue gas analyzer (Testo 350). x concentration and calculate the absorption efficiency.

[0091] Table 9 Purification efficiency at different air velocities

[0092]

[0093] Example 9

[0094] Containing NO x Concentration is 500mg / m 3 As an example, the flue gas is introduced into the flue gas oxidation device and 660mg / m 3 The O3 is oxidized, and the volume ratio of NO2 to NO after oxidation is 1:0.2. The oxidized flue gas is passed into the absorption tower, passes through the absorption bed, and reacts with the porous material with a liquid film. The liquid film supported on the porous material is composed of three parts: pH regulator, liquid film forming agent, and liquid film stabilizer.

[0095] The pH regulators are exemplified by NaOH, Na2S and ethanolamine, which account for 5% of the total mass of the liquid membrane and are added in equal mass ratios. The liquid membrane forming agents are exemplified by water and propylene glycol (mass ratio = 1:0.2). The liquid membrane stabilizers are exemplified by urea and NaHCO3, which account for 2% of the total mass of the liquid membrane and are added in equal mass ratios. The porous liquid membrane immobilized carrier is exemplified by activated carbon; the absorption space velocities are 1,000, 2,500, 5,000, 10,000, 25,000, 50,000, 100,000, 250,000, 500,000, 1,000,000, h-1, respectively. -1 , at 80℃, absorption space velocity = 50,000h -1 The absorption was carried out under the conditions of the example, and the solid-liquid ratio of the absorbent was 1:10, 1:5, 1:1, 1:0.5, 1:0.2, 1:0.1, and 1:0.05 respectively. The flue gas analyzer (Testo350) was used to detect and analyze the NO in the inlet and outlet.x concentration and calculate the absorption efficiency.

[0096] Table 10 Purification efficiency of different absorbent solid-liquid ratios

[0097]

[0098] In summary, the method for absorbing NO2 provided by this patent has high NO2 removal efficiency, low-temperature and normal-pressure reaction, and low energy consumption, and is very promising in industrial denitrification.

[0099] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be considered as being limited to the specific forms described in the embodiments.

Claims

1. A method for purifying nitrogen oxide waste gas by solid phase liquid membrane method, characterized in that Different initial concentrations of NO x Flue gas is partially oxidized by ozone, ClO2 or O2 to reduce NO x The components are converted into a NO2-NO mixed flue gas of a certain proportion, which is then passed into the absorption bed filled with absorption material to achieve the absorption and removal of nitrogen oxides; The absorbent material is loaded with an absorbent liquid film, including a porous solid phase material and a liquid film, and the mass ratio of the porous solid phase material to the liquid film is 1:0.05-0.5; The liquid film is mainly composed of three parts: a pH regulator, a liquid film forming agent and a liquid film stabilizer. The composition content of the liquid film is as follows: 4.8-5.5% of the pH regulator, 1-2% of the liquid film stabilizer, and the rest is the liquid film forming agent. The pH value regulator includes an organic base and an inorganic base, the mass ratio of the organic base to the inorganic base is 1:0.65~1, the organic base is an organic amine, and the inorganic base is one or more of NaOH, Na2CO3, KOH, K2CO3, and Na2S; The liquid film stabilizer includes urea and an additive, the mass ratio of urea to the additive is 1:0.5~1, and the additive is one or more of NaCl, CaCl2, NaHCO3, EDTA, and Na2SO3; Among the components of the liquid film forming agent, the mass ratio of water to C1~C4 lower alcohol is 1:0.1~0.3, and the C1~C4 lower alcohol is propylene glycol; The porous solid phase material is activated carbon, and its specific surface area is 500 m 2 / g or above.

2. The method for purifying nitrogen oxide waste gas by solid phase liquid membrane method according to claim 1, characterized in that The additive is NaHCO3.

3. The method for purifying nitrogen oxide waste gas by solid phase liquid membrane method according to claim 1, characterized in that Among the components of the liquid film forming agent, the mass ratio of water to C1-C4 lower alcohol is 1:0.

2.

4. The method for purifying nitrogen oxide waste gas by solid phase liquid membrane method according to claim 1, characterized in that The specific surface area of the porous solid phase material is 1000 m 2 / g or above.

5. The method for purifying nitrogen oxide waste gas by solid phase liquid membrane method according to claim 1, characterized in that The NO-containing x Initial NO in flue gas x Concentration ranges from 10 to 2000 mg / m 3 After partial oxidation, the volume ratio of NO2-NO in the mixed flue gas is 1:5~1:0.01; the absorption temperature is 40~160℃, and the absorption space velocity is 1000~500000 h -1 .

6. The method for purifying nitrogen oxide waste gas by solid phase liquid membrane method according to claim 5, characterized in that The NO-containing x Initial NO in flue gas x Concentration ranges from 50 to 1500 mg / m 3 After partial oxidation, the volume ratio of NO2-NO in the mixed flue gas is 1:1~0.1; the absorption temperature is 40~120℃, and the absorption space velocity is 1000~200,000 h -1 .

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