Method and system for co-adsorption removal of sulfur dioxide and nitrogen oxide in flue gas of coal-fired power plant

Abstract

The invention provides a method and system for co-adsorption removal of sulfur dioxide and nitrogen oxides in flue gas of a coal-fired power plant, and the method comprises the following steps: S1, introducing the flue gas into a spray cooling tower for spray cooling, and controlling the temperature of the outlet flue gas of the spray cooling tower to-17 DEG C to-13 DEG C to obtain low-temperature flue gas; s2, the low-temperature flue gas is introduced into a molecular sieve dryer for dehumidification, and the humidity of the low-temperature flue gas at an outlet of the molecular sieve dryer is controlled to be 20-50 ppm; s3, the dehumidified low-temperature flue gas is introduced into an adsorption tower, sulfur dioxide and nitric oxide in the dehumidified low-temperature flue gas are adsorbed and removed through activated carbon in the adsorption tower, and purified flue gas is obtained. According to the method, key process parameters such as temperature and humidity in the co-adsorption removal process are strictly controlled, so that the sulfur dioxide and the nitrogen oxide in the flue gas of the coal-fired power plant are integrally adsorbed and removed, and the near-zero emission effect is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of flue gas purification, and in particular, the present invention relates to a method and system for co-adsorbing and removing sulfur dioxide and nitrogen oxides in flue gas of a coal-fired power plant. Background Art

[0002] Sulfur dioxide (SO2) and nitrogen oxides (NO X ) is the main cause of air pollution and acid rain, and it can also directly harm the human body. Therefore, SO2 and NO in industrial flue gas X The removal technology is crucial.

[0003] At present, the pollutant removal technology usually adopts the system series method to remove pollutants one by one. For example, in large coal-fired boilers, wet desulfurization is widely used to remove SO2 in the flue gas, and then the desulfurized flue gas is denitrified through selective catalytic reduction (SCR) or non-selective catalytic reduction (SNCR) technology, so as to remove SO2 and NO in the flue gas in sequence. X However, this process has many problems such as complicated process and high operating cost, and the current related technology has limited SO2 and NO in industrial flue gas. X The removal capacity of SO2 and NO in industrial flue gas is limited. X Ultra-low emissions (SO2≤35mg / Nm 3 , NO X ≤50mg / Nm 3 ), but due to the huge total amount of industrial flue gas emissions, SO2 and NO X The absolute value of emissions is still not negligible. SO2 and NO in industrial flue gas X Near-zero emissions are imperative. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the embodiment of the present invention provides a method and system for co-adsorbing and removing sulfur dioxide and nitrogen oxides in flue gas of a coal-fired power plant.

[0005] In a first aspect, an embodiment of the present invention provides a method for co-adsorbing and removing sulfur dioxide and nitrogen oxides from flue gas in a coal-fired power plant, comprising the following steps:

[0006] S1: passing the flue gas into a spray cooling tower for spray cooling, controlling the temperature of the flue gas at the outlet of the spray cooling tower to be -17°C to -13°C, and obtaining low-temperature flue gas;

[0007] S2: passing the low-temperature flue gas into a molecular sieve dryer for dehumidification, and controlling the humidity of the low-temperature flue gas at the outlet of the molecular sieve dryer to be 20ppm to 50ppm;

[0008] S3: passing the dehumidified low-temperature flue gas into an adsorption tower, and the activated carbon in the adsorption tower adsorbs and removes sulfur dioxide and nitrogen oxides in the dehumidified low-temperature flue gas to obtain clean flue gas.

[0009] The method of the embodiment of the present invention, on the one hand, achieves matching of the adsorption capacity of activated carbon for sulfur dioxide and nitrogen oxides by controlling the temperature of low-temperature flue gas at -17°C to -13°C, thereby improving removal efficiency, while reducing the amount of adsorption material used and reducing costs. When the flue gas temperature is controlled at -17°C to -13°C, the moisture in the flue gas can be reduced to below 0.2%, further reducing the dehumidification load of the molecular sieve dryer. On the other hand, the method of the embodiment of the present invention strictly controls the humidity of the low-temperature flue gas entering the adsorption tower to 20ppm to 50ppm, thereby avoiding to the greatest extent the influence of moisture in the flue gas occupying the adsorption position of the activated carbon and thus affecting the adsorption capacity of the activated carbon, as well as the influence of the heat release of water absorption by the activated carbon on the low-temperature adsorption performance, thereby achieving the efficient integrated co-adsorption removal of sulfur dioxide and nitrogen oxides to the greatest extent.

[0010] In some embodiments, the adsorption tower is a moving bed adsorption tower, and the pressure drop of the adsorption bed in the adsorption tower is controlled to be 1.5 kpa to 3 kpa. Since the adsorption tower used is a moving bed adsorption tower, as the activated carbon particles in the adsorption tower flow for a long time, the activated carbon particles will produce fine powder due to wear, resulting in an increase in the pressure drop of the adsorption bed, thereby affecting normal operation. Therefore, by controlling the pressure drop of the adsorption bed within the range of 1.5 kpa to 3 kpa, the normal operation of the adsorption tower can be ensured, and the efficient adsorption of the adsorption tower is further guaranteed.

[0011] In some embodiments, the molecular sieve is a 3A molecular sieve with a particle size of 3 to 5 mm. By using a 3A molecular sieve (effective pore size is about 0.3 nm), it has a uniform pore structure and a high specific surface area, and can effectively absorb moisture in the flue gas, thereby achieving a dehumidification effect.

[0012] In some embodiments, the particle size of the activated carbon is 4 to 8 meshes, and the iodine value is 1000 to 1200. The inventors have found through research that when the particle size of the activated carbon is small, there is a large resistance in the process of countercurrent contact with the flue gas, which affects the adsorption effect; and when the particle size of the activated carbon is large, although the contact resistance between the activated carbon and the flue gas can be reduced to a certain extent, the adsorption area of ​​the activated carbon will be greatly reduced, resulting in a decrease in the adsorption capacity of the activated carbon for sulfur dioxide and nitrogen oxides in the flue gas, and more activated carbon needs to be consumed to achieve the adsorption effect, which greatly increases the use cost of the activated carbon. Therefore, the present application selects activated carbon with a particle size of 4 to 8 meshes, and the iodine value of the activated carbon is 1000 to 1200, to ensure that the activated carbon has a sufficiently large specific surface area, improve the adsorption capacity, and at the same time, the resistance is small in the process of countercurrent contact with the flue gas, which improves the adsorption effect.

[0013] In some embodiments, the content of sulfur dioxide in the clean flue gas is ≤1 mg / Nm 3 , nitrogen oxide content ≤1mg / Nm 3 The method of the embodiment of the present invention achieves near-zero emission of sulfur dioxide and nitrogen oxides in flue gas from coal-fired power plants by strictly controlling key process parameters such as temperature, humidity and pressure drop during the adsorption removal process.

[0014] In some embodiments, the method further comprises: passing the activated carbon after adsorption saturation in step S3 into a regeneration tower for heating and regeneration, the regeneration temperature is 300-350° C., and the regenerated activated carbon is reused as an adsorbent of the adsorption tower. At 300-350° C., sulfur dioxide and nitrogen oxide gases can be fully desorbed to achieve regeneration of the activated carbon.

[0015] In a second aspect, an embodiment of the present invention further provides a system for co-adsorbing and removing sulfur dioxide and nitrogen oxides from flue gas in a coal-fired power plant, comprising:

[0016] Spray cooling tower, used to cool flue gas to -17℃~-13℃;

[0017] A molecular sieve dryer is used to dehumidify the flue gas cooled by the spray cooling tower to make the humidity of the outlet flue gas 20ppm to 50ppm;

[0018] The multiple adsorption towers connected in parallel are used to allow the flue gas after dehumidification to contact with the adsorbent activated carbon for adsorption in the adsorption towers.

[0019] The characteristics and advantages described above for the method for co-adsorption removal of sulfur dioxide and nitrogen oxides in flue gas from coal-fired power plants are also applicable to the system for co-adsorption removal of sulfur dioxide and nitrogen oxides in flue gas from coal-fired power plants, and will not be repeated here.

[0020] In some embodiments, a temperature sensor is provided on the connecting pipeline between the spray cooling tower and the molecular sieve dryer. The temperature sensor is interlocked with the variable frequency motor of the low-temperature spray water pump of the spray cooling tower to control the outlet flue gas temperature of the spray cooling tower to -17°C to -13°C.

[0021] In some embodiments, a humidity sensor is provided on the connecting pipe between the molecular sieve dryer and the adsorption tower for monitoring the humidity of the outlet flue gas of the molecular sieve dryer.

[0022] In some embodiments, the adsorption tower is a moving bed adsorption tower.

[0023] In some embodiments, the system for co-adsorption and removal of sulfur dioxide and nitrogen oxides in flue gas from a coal-fired power plant further comprises:

[0024] A first material conveying device is used to convey the adsorbent activated carbon saturated with adsorption discharged from the adsorption tower to the regeneration inlet of the regeneration tower;

[0025] A regeneration tower, the regeneration tower is used to heat and regenerate the adsorbent activated carbon that is saturated with adsorption; the regeneration tower has a regeneration inlet and a regeneration outlet;

[0026] An air screen connected to the regeneration outlet and used to screen out carbon powder in the adsorbent activated carbon after regeneration in the regeneration tower;

[0027] The second material conveying device is used to convey the adsorbent activated carbon after the air screen to the adsorption tower.

[0028] In some embodiments, a pressure sensor is provided on the air inlet pipeline of the adsorption tower, and the pressure sensor is interlocked with the wind screen to control the pressure drop of the adsorption bed layer of the adsorption tower to 1.5 kpa to 3 kpa.

[0029] In some embodiments, the adsorption tower is provided with an inlet air chamber, an adsorption bed layer and an outlet air chamber in order from bottom to top; wherein,

[0030] A first inserted thermal resistance thermometer is provided inside the inlet air chamber for monitoring the temperature of the inlet flue gas of the adsorption tower;

[0031] And / or, a second inserted thermal resistance thermometer is provided inside the adsorption bed layer for monitoring the temperature of the adsorption bed layer; and the second inserted thermal resistance thermometer is interlocked with the air inlet cut-off valve of the adsorption tower;

[0032] And / or, a third inserted thermal resistance thermometer is provided inside the outlet air chamber for monitoring the temperature of the outlet flue gas of the adsorption tower; and the third inserted thermal resistance thermometer is interlocked with the outlet cut-off valve of the adsorption tower. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The present invention is a flow chart of a method for co-adsorbing and removing sulfur dioxide and nitrogen oxides from flue gas of a coal-fired power plant according to an embodiment of the present invention.

[0034] Figure 2 The present invention is a schematic structural diagram of a system for co-adsorbing and removing sulfur dioxide and nitrogen oxides from flue gas in a coal-fired power plant according to an embodiment of the present invention.

[0035] Figure 3 It is a schematic diagram of the structure of an adsorption tower according to an embodiment of the present invention.

[0036] Figure 4 is the saturated adsorption capacity of sulfur dioxide and nitrogen oxides of activated carbon in different temperature ranges.

[0037] Figure markings: 1-spray cooling tower; 2-molecular sieve dryer; 3-adsorption tower; 301-inlet air chamber, 302-adsorption bed, 303-outlet air chamber, 304-first inserted thermal resistance thermometer; 305-second inserted thermal resistance thermometer; 306-third inserted thermal resistance thermometer; 4-regeneration tower; 5-wind screen; 6-temperature sensor; 7-humidity sensor; 8-pressure sensor; 9-first material conveying device; 10-second material conveying device. DETAILED DESCRIPTION

[0038] Embodiments of the present invention are described in detail below. The embodiments described below are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0039] In this article, the term "and / or" is merely a term used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent three situations: A exists alone, A and B exist at the same time, and B exists alone.

[0040] As used herein, the term "plurality" refers to more than two (including two).

[0041] Where values ​​are described herein as a range, it should be understood that such disclosure includes disclosure of all possible sub-ranges within that range, as well as specific values ​​falling within that range, regardless of whether a specific value or a specific sub-range is explicitly stated.

[0042] As used herein, the terms "about" or "around" refer to + / - 10% of the recited value.

[0043] The following describes a method and system for co-adsorbing and removing sulfur dioxide and nitrogen oxides from flue gas in a coal-fired power plant according to an embodiment of the present invention with reference to the accompanying drawings.

[0044] The embodiment of the present invention provides a method for co-adsorbing and removing sulfur dioxide and nitrogen oxides in flue gas from a coal-fired power plant, comprising the following steps:

[0045] S1: passing the flue gas into a spray cooling tower for spray cooling, controlling the temperature of the flue gas at the outlet of the spray cooling tower to be -17°C to -13°C, and obtaining low-temperature flue gas;

[0046] S2: passing the low-temperature flue gas into a molecular sieve dryer for dehumidification, and controlling the humidity of the low-temperature flue gas at the outlet of the molecular sieve dryer to be 20ppm to 50ppm;

[0047] S3: The dehumidified low-temperature flue gas is passed into an adsorption tower, and the activated carbon in the adsorption tower adsorbs and removes sulfur dioxide and nitrogen oxides in the dehumidified low-temperature flue gas to obtain clean flue gas.

[0048] It should be noted that the flue gas of coal-fired power plants contains a lot of sulfur dioxide (SO2) and nitrogen oxides (NO X ), where the concentration of SO2 is 2000mg / Nm 3 ~4000mg / Nm 3 , NO X The concentration of (mainly including NO2 and NO) is 200mg / Nm 3 ~400mg / Nm 3 , while SO2 and NO2 can be directly removed by activated carbon through physical adsorption, but NO in flue gas cannot be directly removed by activated carbon adsorption. NO can be removed by oxidation adsorption mechanism with O2 in flue gas under the action of low temperature and activated carbon, that is, NO and O2 in flue gas are enriched on the surface of activated carbon at low temperature to form a local high concentration, which is quickly oxidized into NO2, and then adsorbed in the pores of activated carbon in the form of NO2, so that NO in flue gas can be removed.

[0049] Figure 4 The results show that activated carbon has a high concentration of SO2 and NO at different temperature ranges. X The inventors found that activated carbon has a saturated adsorption capacity of SO2 and NO X Although the adsorption capacity of activated carbon will increase significantly with decreasing temperature, as the temperature decreases, the adsorption capacity of activated carbon for SO2 and NO X The increase in the adsorption capacity of activated carbon is not the same, but in the temperature range of -17℃~-13℃, it can make the activated carbon adsorb SO2 and NO X The adsorption capacity of activated carbon is more matched, so that activated carbon can achieve saturation of NO while adsorbing SO2. X adsorption saturation.

[0050] In the method of the embodiment of the present invention, the temperature of the low-temperature flue gas is controlled at -17°C to -13°C to achieve the activation of activated carbon for SO2 and NO X Matching the adsorption capacity improves the removal efficiency, reduces the amount of adsorption materials, reduces costs, and is conducive to achieving near-zero emissions of flue gas pollutants. When the flue gas temperature is higher than -13°C, it is not only unfavorable for activated carbon to absorb SO2 and NO X It is difficult to achieve near-zero emission due to adsorption, and more activated carbon adsorbents are needed, increasing costs; when the flue gas temperature is lower than -17°C, the refrigeration energy consumption is too high, which increases costs and places too high demands on refrigeration equipment; in addition, if the temperature is too low, condensation water will easily appear in the adsorption tower, causing the adsorbent to stick and clog, affecting adsorption. In addition, when the flue gas temperature is controlled at -17°C to -13°C, the moisture in the flue gas can be reduced to below 0.2%, thereby reducing the dehumidification load of the molecular sieve dryer. Therefore, the present application controls the temperature of the low-temperature flue gas within the range of -17°C to -13°C, which can not only reduce the use of activated carbon and save costs, but also facilitate the integrated adsorption and removal of flue gas pollutants, thereby achieving near-zero emissions of flue gas pollutants.

[0051] In some embodiments, in step S1, the temperature of the low-temperature flue gas is controlled by adjusting the circulation amount of the low-temperature spray water. As a specific example, when the temperature of the low-temperature flue gas is higher than -13°C, the circulation amount of the low-temperature spray water is increased; when the temperature of the low-temperature flue gas is lower than -17°C, the circulation amount of the low-temperature spray water is reduced.

[0052] The inventors found through research that the moisture in the flue gas not only occupies the adsorption position of activated carbon, but also reduces the activated carbon's absorption of SO2 and NO in the flue gas. X adsorption capacity; and because activated carbon releases heat after absorbing water, the temperature of the adsorption bed rises, which in turn affects the low-temperature adsorption performance; in addition, since the pollutant SO2 in the flue gas reacts with water on the surface of the activated carbon to generate sulfuric acid, forming sulfuric acid adsorption, and the adsorbed sulfuric acid has a high desorption temperature, which is not conducive to the regeneration of activated carbon. Therefore, the present application first dehumidifies the low-temperature flue gas through a molecular sieve before physical adsorption to remove moisture from the low-temperature flue gas, but if the dehumidification effect is too high, more molecular sieves are required, and the quality requirements of the molecular sieves are high, resulting in increased costs. Therefore, the present application controls the humidity of the low-temperature flue gas to 20ppm~50ppm.

[0053] In some embodiments, in step S2, when the humidity of the low-temperature flue gas is greater than 50 ppm, the molecular sieve in the molecular sieve dryer is replaced to control the humidity of the low-temperature flue gas to 20 ppm to 50 ppm. The replaced molecular sieve is subsequently regenerated and dried for reuse.

[0054] In some embodiments, the adsorption tower is a moving bed adsorption tower, and the pressure drop of the adsorption bed in the adsorption tower is controlled to be 1.5kpa to 3kpa. In the method of the embodiment of the present invention, the adsorption tower used is a moving bed adsorption tower. As the activated carbon particles in the adsorption tower flow for a long time, the activated carbon particles will produce fine powder due to wear, resulting in an increase in the pressure drop of the adsorption bed, thereby affecting normal operation. The method of the embodiment of the present invention ensures the normal operation of the adsorption tower by controlling the pressure drop of the adsorption bed within the range of 1.5kpa to 3kpa, thereby further ensuring the efficient adsorption of the adsorption tower.

[0055] In some embodiments, the molecular sieve is a 3A molecular sieve with a particle size of 3 to 5 mm. The embodiment of the present invention uses a 3A molecular sieve (effective pore size is about 0.3 nm), which has a uniform pore structure and a high specific surface area, and can effectively absorb moisture in the flue gas, thereby achieving a dehumidification effect.

[0056] In some embodiments, the particle size of the activated carbon is 4-8 meshes, and the iodine value is 1000-1200. The inventors have found through research that when the particle size of the activated carbon is small, there is a large resistance in the process of countercurrent contact with the flue gas, which affects the adsorption effect; and when the particle size of the activated carbon is large, although the contact resistance between the activated carbon and the flue gas can be reduced to a certain extent, the adsorption area of ​​the activated carbon will be greatly reduced, resulting in the activated carbon's adsorption of SO2 and NO in the flue gas. X The adsorption capacity is reduced, and more activated carbon is needed to achieve the adsorption effect, which greatly increases the use cost of activated carbon. Therefore, this application selects activated carbon with a particle size of 4 to 8 meshes, and the iodine value of the activated carbon is 1000 to 1200, to ensure that the activated carbon has a sufficiently large specific surface area and improve the adsorption capacity. At the same time, the resistance during the countercurrent contact with the flue gas is small, thereby improving the adsorption effect.

[0057] In some embodiments, the SO2 content in the clean flue gas is ≤1 mg / Nm 3 , NO X Content ≤1mg / Nm 3 The method of the embodiment of the present invention achieves SO2 and NO in flue gas by strictly controlling key process parameters such as temperature, humidity and pressure drop during the process. X Nearly zero emissions.

[0058] In some embodiments, the above method further includes monitoring the temperature in the adsorption tower in all directions. When the temperature of the adsorption bed of the adsorption tower or the temperature of the outlet flue gas of the adsorption tower is higher than the temperature of the inlet flue gas of the adsorption tower by more than 50°C, the inlet and outlet valves of the adsorption tower are automatically cut off, and the adsorption tower is filled with nitrogen for protection. The main reason is that: since activated carbon is a flammable substance and the flue gas contains a small amount of oxygen, there is a risk of fire in the adsorption tower under high temperature environment. Therefore, it is necessary to monitor the temperature in the adsorption tower in all directions so that protection can be carried out in time when the temperature in the adsorption tower is abnormal.

[0059] In some embodiments, the method further comprises: passing the activated carbon after adsorption saturation in step S3 into a regeneration tower for heating and regeneration, the regeneration temperature is 300-350°C, and the regenerated activated carbon is reused as an adsorbent in the adsorption tower. At 300-350°C, SO2 and NO can be fully desorbed. X Gas to achieve regeneration of activated carbon.

[0060] As a specific example, the heating regeneration can be indirect heating regeneration, by using hot air at 400-450°C to heat the activated carbon after physical adsorption saturation to 300-350°C to desorb SO2 and NO X Gas is then used to obtain regenerated activated carbon for recycling.

[0061] In some embodiments, before the flue gas is introduced into the spray cooling tower for spray cooling, a dust removal step is also included.

[0062] Figure 1 A method flow chart of an embodiment of the present invention is shown, wherein SO2 and NO in flue gas of a coal-fired power plant are X The method for co-adsorption removal comprises the following steps:

[0063] The flue gas is passed into a spray cooling tower for spray cooling, and the temperature of the flue gas at the outlet of the spray cooling tower is controlled to be -17°C to -13°C to obtain low-temperature flue gas;

[0064] The low-temperature flue gas is passed into the molecular sieve dryer for dehumidification, and the humidity of the low-temperature flue gas at the outlet of the molecular sieve dryer is controlled to be 20ppm to 50ppm;

[0065] The dehumidified low-temperature flue gas is passed into the adsorption tower, and the activated carbon in the adsorption tower removes SO2 and NO in the dehumidified low-temperature flue gas. X Adsorption removal, the SO2 content in the obtained clean flue gas is ≤1mg / Nm 3 , NO X Content ≤1mg / Nm 3 , directly empty;

[0066] The activated carbon that has been saturated with adsorption is passed into a regeneration tower for heating and regeneration, and the regenerated activated carbon is reused as an adsorbent in the adsorption tower.

[0067] like Figure 2 , Figure 3 As shown, the embodiment of the present invention also provides a method for detecting SO2 and NO in flue gas of a coal-fired power plant. X The co-adsorption removal system comprises the following connected in sequence:

[0068] Spray cooling tower 1, used to cool the flue gas to -17℃~-13℃;

[0069] The molecular sieve dryer 2 is used to dehumidify the flue gas cooled by the spray cooling tower 1, so that the humidity of the outlet flue gas is 20ppm to 50ppm;

[0070] The multiple adsorption towers 3 connected in parallel are used to make the flue gas after dehumidification contact with the adsorbent activated carbon in the adsorption tower 3 for adsorption.

[0071] In some embodiments, a temperature sensor 6 is provided on the connecting pipeline between the spray cooling tower 1 and the molecular sieve dryer 2. The temperature sensor 6 is interlocked with the variable frequency motor of the low-temperature spray water pump of the spray cooling tower 1 to control the outlet flue gas temperature of the spray cooling tower 1 to -17°C to -13°C.

[0072] In some embodiments, a humidity sensor 7 is provided on the connecting pipe between the molecular sieve dryer 2 and the adsorption tower 3 for monitoring the humidity of the flue gas at the outlet of the molecular sieve dryer 2 .

[0073] In some embodiments, the adsorption tower 3 is a moving bed adsorption tower.

[0074] In some embodiments, SO2 and NO in flue gas from coal-fired power plants X The co-adsorption removal system also includes:

[0075] The first material conveying device 9 is used to convey the adsorbent activated carbon saturated with adsorption discharged from the adsorption tower 3 to the regeneration inlet of the regeneration tower 4;

[0076] The regeneration tower 4 is used to heat and regenerate the adsorbent activated carbon that is saturated with adsorption; the regeneration tower 4 has a regeneration inlet and a regeneration outlet;

[0077] The wind screen 5 is connected to the regeneration outlet and is used to screen out carbon powder in the adsorbent activated carbon after regeneration in the regeneration tower 4;

[0078] The second material conveying device 10 is used to convey the adsorbent activated carbon after the air screen to the adsorption tower 3 .

[0079] In some embodiments, a pressure sensor 8 is provided on the air inlet pipeline of the adsorption tower 3, and the pressure sensor 8 is interlocked with the wind screen 5 to control the pressure drop of the adsorption bed of the adsorption tower to be 1.5 kpa to 3 kpa.

[0080] As a specific example, both the first material conveying device 9 and the second material conveying device 10 can be chain bucket conveyors.

[0081] In some embodiments, the adsorption tower 3 is provided with an inlet air chamber 301, an adsorption bed 302 and an outlet air chamber 303 from bottom to top;

[0082] A first insertion type thermal resistance thermometer 304 is provided inside the inlet air chamber 301 to monitor the temperature of the inlet flue gas of the adsorption tower 3;

[0083] And / or, a second inserted thermal resistance thermometer 305 is provided inside the adsorption bed 302 for monitoring the temperature of the adsorption bed 302; and the second inserted thermal resistance thermometer 305 is interlocked with the air inlet cut-off valve of the adsorption tower;

[0084] And / or, a third inserted thermal resistance thermometer 306 is provided inside the outlet air chamber 303 for monitoring the temperature of the outlet flue gas of the adsorption tower 3 ; and the third inserted thermal resistance thermometer 306 is interlocked with the outlet cut-off valve of the adsorption tower 3 .

[0085] It can be understood that the embodiment of the present invention can realize all-round monitoring of the temperature in the adsorption tower 3 by setting the first inserted thermal resistance thermometer 304, the second inserted thermal resistance thermometer 305, and the third inserted thermal resistance thermometer 306. When the temperature of the adsorption bed of the adsorption tower 3 or the temperature of the outlet flue gas of the adsorption tower 3 is higher than the temperature of the inlet flue gas of the adsorption tower 3 by more than 50°C, the inlet and outlet valves of the adsorption tower 3 are automatically cut off, and the adsorption tower is filled with nitrogen for protection.

[0086] It is understandable that the embodiment of the present invention is provided with a plurality of adsorption towers 3 connected in parallel. Figure 2 Two are given as examples, including a first adsorption tower and a second adsorption tower. When the first adsorption tower needs to be filled with nitrogen for protection, the dehumidified low-temperature flue gas can be introduced into the second adsorption tower for adsorption.

[0087] SO2 and NO in flue gas from coal-fired power plants according to the present invention X The co-adsorption removal system is equipped with temperature sensors, humidity sensors, pressure sensors and other equipment to monitor and strictly control key process parameters such as temperature, humidity and pressure drop in the co-adsorption removal process in real time, so as to achieve the removal of SO2 and NO in the flue gas of coal-fired power plants. X Co-adsorption and removal ensure that the system can operate safely and effectively.

[0088] It is understandable that SO2 and NO in the flue gas of the coal-fired power plant in the embodiment of the present invention are X The co-adsorption removal method can utilize the SO2 and NO in the flue gas of the above-mentioned coal-fired power plant X Co-adsorption removal system.

[0089] As a specific exemplary embodiment, this embodiment provides a method for determining the SO2 and NO in flue gas of a coal-fired power plant. X The co-adsorption removal method comprises the following steps:

[0090] The flue gas from coal-fired power plants (main component: SO2: about 4000mg / Nm 3 ; NO X : About 400mg / Nm 3 ) is transported to the spray cooling tower 1 for spray cooling. A temperature sensor 6 is provided on the connecting pipe between the spray cooling tower 1 and the molecular sieve dryer 2, and the temperature sensor 6 is interlocked with the variable frequency motor of the low-temperature spray water pump of the spray cooling tower 1. When the temperature value displayed by the temperature sensor 6 is higher than -13°C, the circulation amount of the low-temperature spray water is increased; when the temperature value displayed by the temperature sensor 6 is lower than -17°C, the circulation amount of the low-temperature spray water is reduced; after spray cooling, the outlet flue gas temperature of the spray cooling tower 1 is about -15°C, that is, low-temperature flue gas is obtained.

[0091] The low-temperature flue gas is transported to the molecular sieve dryer 2, and the molecular sieve in the molecular sieve dryer 2 is used to dehumidify the low-temperature flue gas to remove moisture in the low-temperature flue gas. A high-precision humidity sensor 7 is provided on the outlet flue of the molecular sieve dryer 2. When the humidity value fed back by the humidity sensor 7 is greater than 50ppm, the molecular sieve in the molecular sieve dryer 2 is replaced to ensure that the humidity of the low-temperature flue gas at the outlet of the molecular sieve dryer 2 is 20ppm to 50ppm; the replaced molecular sieve is subsequently regenerated and dried for reuse.

[0092] The dehumidified low-temperature flue gas enters the inlet air chamber 301 of the adsorption tower 3 from the bottom and flows from bottom to top, and contacts with the activated carbon moving from top to bottom in the adsorption bed 302 in countercurrent, so that SO2 and NO in the low-temperature flue gas are removed. X The SO2 content in the obtained clean flue gas is ≤1mg / Nm 3 , NO X Content ≤1mg / Nm 3 , achieving SO2 and NO in flue gas X Nearly zero emissions.

[0093] The activated carbon saturated with adsorption in the adsorption tower 3 is transported to the regeneration tower 4 through the first material conveying device 9, and the activated carbon particles are heated to about 330°C by hot air at about 440°C to desorb SO2 and NO. X gas, thereby obtaining regenerated activated carbon; the regenerated activated carbon is then transported to the wind screen 5, and the carbon powder is screened out by the wind screen 5 and then transported to the adsorption tower 3 through the second material conveying device 10, and reused as the adsorbent of the adsorption tower 3, saving resources.

[0094] In this embodiment, the first inserted thermal resistance thermometer 304, the second inserted thermal resistance thermometer 305 and the third inserted thermal resistance thermometer 306 are respectively arranged inside the inlet air chamber 301, the adsorption bed 302 and the outlet air chamber 303 of the adsorption tower 3; and the second inserted thermal resistance thermometer 305 is interlocked with the air inlet cut-off valve of the adsorption tower 3, and the third inserted thermal resistance thermometer 306 is interlocked with the air outlet cut-off valve of the adsorption tower 3. When the temperature of the adsorption bed 302 of the adsorption tower 3 or the outlet flue gas temperature of the adsorption tower 3 is higher than the inlet flue gas temperature of the adsorption tower 3 by more than 20°C, an alarm is given, and the operator should pay close attention to the rising trend of the temperature of the adsorption bed 302 at this time; when the temperature of the adsorption bed 302 of the adsorption tower 3 or the outlet flue gas temperature of the adsorption tower 3 is higher than the inlet flue gas temperature of the adsorption tower 3 by more than 50°C, the inlet and outlet valves of the adsorption tower 3 are automatically cut off, and the adsorption tower 3 is filled with nitrogen for protection.

[0095] In this embodiment, a pressure sensor 8 is provided on the air inlet pipe of the adsorption tower 3, which is used to monitor the pressure drop of the adsorption bed 302 of the adsorption tower 3; and the pressure sensor 8 is interlocked with the wind screen 5. When the pressure drop displayed by the pressure sensor 8 exceeds 3kPa, the wind screen 5 is automatically started to screen out the carbon powder produced by the wear of the activated carbon in the adsorption tower 3 to prevent it from affecting the normal operation of the adsorption tower 3, until the pressure drop displayed by the pressure sensor 8 is 1.5kPa.

[0096] In order to more clearly illustrate the effect of the present application, the inventor provides a comparative example of the test process:

[0097] The comparative example provides a method for determining the content of SO2 and NO in flue gas of a coal-fired power plant. X The co-adsorption removal system comprises the following steps:

[0098] S1: The flue gas from coal-fired power plants (main component: SO2: 4000mg / Nm 3 ; NO X :400mg / Nm 3 ) is passed into a spray cooling tower for spray cooling, so that the temperature of the flue gas at the outlet of the spray cooling tower drops to 5°C;

[0099] S2: passing the flue gas cooled in step S1 into a molecular sieve dryer for dehumidification, and controlling the humidity of the low-temperature flue gas at the outlet of the molecular sieve dryer to be 20ppm to 50ppm;

[0100] S3: The dehumidified low-temperature flue gas is passed into the adsorption tower, and the activated carbon in the adsorption tower is used to remove SO2 and NO in the dehumidified low-temperature flue gas. X Physical adsorption is performed to remove the gas, and the pressure drop of the adsorption bed in the adsorption tower is controlled to be 1.5kpa to 3kpa. Clean flue gas is obtained after adsorption and purification in the adsorption tower and discharged.

[0101] S4: The activated carbon that has been saturated with physical adsorption in step S3 is passed into a regeneration tower for regeneration treatment, and the regenerated activated carbon is reused as an adsorbent in the adsorption tower.

[0102] The SO2 content in the clean flue gas obtained in this comparative example is 5 mg / Nm 3 Left and right, NO X The content is 10mg / Nm 3 About, SO2 and NO in flue gas are not reached X Nearly zero emissions.

[0103] In addition, it should be noted that the above comparative examples are not prior art and are only provided for contrast with the method of the present invention and cannot be used as a limitation of the present invention.

[0104] It can be seen from the examples of the present invention and the comparative examples that the present invention achieves the removal of SO2 and NO in the flue gas of coal-fired power plants by strictly controlling the key process parameters such as temperature, humidity, and pressure drop during the co-adsorption removal process. X Integrated adsorption and removal, and achieve near-zero emission effect.

[0105] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0106] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0107] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0108] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0109] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0110] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for co-adsorption and removal of sulfur dioxide and nitrogen oxides in flue gas from a coal-fired power plant, characterized in that: The following steps are involved: S1: passing the flue gas into a spray cooling tower for spray cooling, controlling the temperature of the flue gas at the outlet of the spray cooling tower to be -17°C to -13°C, and obtaining low-temperature flue gas; S2: passing the low-temperature flue gas into a molecular sieve dryer for dehumidification, and controlling the humidity of the low-temperature flue gas at the outlet of the molecular sieve dryer to be 20ppm to 50ppm; S3: passing the dehumidified low-temperature flue gas into an adsorption tower, and the activated carbon in the adsorption tower adsorbs and removes sulfur dioxide and nitrogen oxides in the dehumidified low-temperature flue gas to obtain clean flue gas.

2. The method for co-adsorption and removal of sulfur dioxide and nitrogen oxides in flue gas from a coal-fired power plant according to claim 1, characterized in that: The adsorption tower is a moving bed adsorption tower, and the pressure drop of the adsorption bed in the adsorption tower is controlled to be 1.5 kpa to 3 kpa.

3. The method for co-adsorption and removal of sulfur dioxide and nitrogen oxides in flue gas from a coal-fired power plant according to claim 1, characterized in that: The molecular sieve is 3A molecular sieve, and the particle size is 3-5 mm; And / or, the particle size of the activated carbon is 4-8 meshes, and the iodine value is 1000-1200.

4. The method for co-adsorption and removal of sulfur dioxide and nitrogen oxides in flue gas from a coal-fired power plant according to claim 1, characterized in that: The content of sulfur dioxide in the clean flue gas is ≤1mg / Nm 3 , nitrogen oxide content ≤1mg / Nm 3 .

5. The method for co-adsorption and removal of sulfur dioxide and nitrogen oxides in flue gas from a coal-fired power plant according to claim 1, characterized in that: Also includes: The activated carbon that has been saturated with adsorption in step S3 is passed into a regeneration tower for heating and regeneration. The regeneration temperature is 300-350° C. The regenerated activated carbon is reused as the adsorbent of the adsorption tower.

6. A system for co-adsorption and removal of sulfur dioxide and nitrogen oxides in flue gas from coal-fired power plants, characterized in that: Used to implement the method according to any one of claims 1 to 5, comprising sequentially connecting: Spray cooling tower, used to cool flue gas to -17℃~-13℃; A molecular sieve dryer is used to dehumidify the flue gas cooled by the spray cooling tower to make the humidity of the outlet flue gas 20ppm to 50ppm; The multiple adsorption towers connected in parallel are used to allow the flue gas after dehumidification to contact with the adsorbent activated carbon for adsorption in the adsorption towers.

7. A system for co-adsorption and removal of sulfur dioxide and nitrogen oxides in flue gas from a coal-fired power plant according to claim 6, characterized in that: A temperature sensor is provided on the connection pipeline between the spray cooling tower and the molecular sieve dryer, and the temperature sensor is interlocked with the variable frequency motor of the low-temperature spray water pump of the spray cooling tower to control the outlet flue gas temperature of the spray cooling tower to -17°C to -13°C; And / or, a humidity sensor is provided on the connecting pipe between the molecular sieve dryer and the adsorption tower, for monitoring the humidity of the outlet flue gas of the molecular sieve dryer; And / or, the adsorption tower is a moving bed adsorption tower.

8. A system for co-adsorption and removal of sulfur dioxide and nitrogen oxides in flue gas from a coal-fired power plant according to claim 6, characterized in that: Also includes: A first material conveying device is used to convey the adsorbent activated carbon saturated with adsorption discharged from the adsorption tower to the regeneration inlet of the regeneration tower; A regeneration tower, the regeneration tower is used to heat and regenerate the adsorbent activated carbon that is saturated with adsorption; the regeneration tower has a regeneration inlet and a regeneration outlet; An air screen connected to the regeneration outlet and used to screen out carbon powder in the adsorbent activated carbon after regeneration in the regeneration tower; The second material conveying device is used to convey the adsorbent activated carbon after the air screen to the adsorption tower.

9. A system for co-adsorption and removal of sulfur dioxide and nitrogen oxides in flue gas from a coal-fired power plant according to claim 7, characterized in that: A pressure sensor is provided on the air inlet pipeline of the adsorption tower, and the pressure sensor is interlocked with the wind screen to control the pressure drop of the adsorption bed layer of the adsorption tower to be 1.5kpa to 3kpa.

10. A system for co-adsorption and removal of sulfur dioxide and nitrogen oxides in flue gas from a coal-fired power plant according to claim 9, characterized in that: The adsorption tower is provided with an inlet air chamber, an adsorption bed layer and an outlet air chamber in order from bottom to top; wherein, A first inserted thermal resistance thermometer is provided inside the inlet air chamber for monitoring the temperature of the inlet flue gas of the adsorption tower; And / or, a second inserted thermal resistance thermometer is provided inside the adsorption bed layer for monitoring the temperature of the adsorption bed layer; and the second inserted thermal resistance thermometer is interlocked with the air inlet cut-off valve of the adsorption tower; And / or, a third inserted thermal resistance thermometer is provided inside the outlet air chamber for monitoring the temperature of the outlet flue gas of the adsorption tower; and the third inserted thermal resistance thermometer is interlocked with the outlet cut-off valve of the adsorption tower.

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