Method and device for improving calcium-based dry desulfurization efficiency by dynamic jetting of nanofluid

Abstract

The invention belongs to the technical field of flue gas purification, and relates to a method and a device for improving calcium-based dry desulfurization efficiency by nano-fluid dynamic jetting, the method comprises the following steps: delivering flue gas to be treated into a desulfurization reactor through a flue gas pipeline, and jetting a desulfurizing agent into the flue gas pipeline and / or the desulfurization reactor for flue gas desulfurization; and dynamically spraying the nanofluid into a desulfurization reactor and / or a flue gas pipeline so as to be mixed with a desulfurizing agent in the desulfurization reactor and / or the flue gas pipeline to form a desulfurization reaction area. According to the invention, the nanofluid is dynamically jetted into the desulfurization reactor and / or the flue gas pipeline through the control system by utilizing the nano-jet, the nanofluid can enable a desulfurizing agent to expose reaction active sites in time, meanwhile, the nanofluid contains nano-particles for improving desulfurization reaction, and the nanofluid can properly reduce the flue gas temperature, so that the desulfurization effect is improved. A liquid film is formed on the surface of the desulfurizing agent, so that SO2 and the desulfurizing agent quickly react in an ionic state, and the aim of improving the calcium-based dry desulfurization efficiency is fulfilled.

Description

Technical Field

[0001] The invention belongs to the technical field of flue gas purification and relates to a method and a device for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid. Background Art

[0002] To meet the national requirements for ultra-low emission of flue gas SO2 (<35mg / Nm 3 ), calcium-based dry desulfurization technology is currently used. However, due to the low activity of Ca(OH)2 in the dry state, the slow diffusion rate of SO2 in the desulfurizer, the product calcium sulfate in the desulfurization reaction process will hinder the exposure of the active sites inside the desulfurizer, and the low activity of a single calcium-based desulfurizer, the efficiency of calcium-based dry desulfurization is only about 70%, and the actual Ca / S molar ratio is about 4, and a large amount of Ca(OH)2 is wasted. At present, the industry mainly focuses on the preparation of highly active and multifunctional calcium-based desulfurizers. There is little research on how to strengthen the reaction process of Ca(OH)2 and SO2, and how to in-situ strengthen the efficiency of Ca(OH)2 desulfurizers during the reaction process. Analysis of the calcium-based desulfurization process revealed that: (1) After the reaction of Ca(OH)2 and SO2, calcium sulfate that is insoluble in water will be generated on the surface of the desulfurizer, which hinders the further reaction of the internal desulfurizer with SO2 and greatly wastes the desulfurizer; (2) The activity of the single Ca(OH)2 desulfurizer itself is low, and the reaction process with SO2 is relatively slow; (3) The reaction of Ca(OH)2 and SO2 is an exothermic reaction. A proper reduction in the flue gas temperature is conducive to the desulfurization reaction; (4) The activity of Ca(OH)2 is low in the dry state. A proper increase in the relative humidity of the flue gas can form a liquid film on the surface of the desulfurizer, so that the diffusion of SO2 gas molecules in the desulfurizer pores and product layer is transformed into ion diffusion in the liquid phase, reducing the diffusion path and resistance. At the same time, water absorbs the dissolved SO2 to form new reaction components. Etc., which is beneficial to the desulfurization reaction.

[0003] In the existing dry desulfurization technology, the method of producing highly active Ca(OH)2 desulfurizer is usually used to solve the problem of low activity of single Ca(OH)2 desulfurizer itself. However, as the reaction proceeds, calcium sulfate that is insoluble in water is generated on the surface of the desulfurizer, which hinders the further reaction process of the internal desulfurizer with SO2. Therefore, using only highly active Ca(OH)2 desulfurizer cannot achieve a good effect. In addition, some technologies use continuous water spraying or spraying to achieve humidification of the desulfurizer during the reaction process, which still cannot solve the problem of calcium sulfate that is insoluble in water generated on the surface of the desulfurizer blocking the reaction active sites during the reaction; when the humidity is too high, it will also cause the desulfurizer to fall off, the material to be hardened, the bed pressure to fluctuate or even collapse, and it is impossible to achieve dynamic control of the humidification process to adapt to the flue gas fluctuations. Therefore, how to solve the problems of calcium sulfate generated on the surface of the desulfurizer blocking the catalytic active sites, low activity of single Ca(OH)2 desulfurizer in dry state, and high flue gas temperature affecting the desulfurization reaction efficiency during the desulfurization reaction is the core of improving the efficiency of calcium-based dry desulfurization. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a method and device for dynamically injecting nanofluid to improve the efficiency of calcium-based dry desulfurization. The nanofluid is dynamically injected into the desulfurization reactor and / or the flue gas duct through a control system using a nanoinjector. The nanofluid can expose the reaction active sites of the desulfurizer in time. At the same time, the nanofluid contains nanoparticles that improve the desulfurization reaction. The nanofluid can appropriately reduce the flue gas temperature and form a liquid film on the surface of the desulfurizer, so that SO2 and the desulfurizer react quickly in an ionic state, so as to achieve the purpose of improving the efficiency of calcium-based dry desulfurization.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluids comprises the following steps:

[0007] Step 1. The flue gas to be treated is sent to the desulfurization reactor through the flue gas pipeline, and the desulfurizer is sprayed into the flue gas pipeline and / or the desulfurization reactor to desulfurize the flue gas;

[0008] Step 2. Dynamically injecting the nanofluid into the desulfurization reactor and / or the flue gas duct to mix with the desulfurizer in the desulfurization reactor and / or the flue gas duct to form a desulfurization reaction zone.

[0009] Furthermore, the nanofluid is a fluid containing a solute for dissolving the desulfurization reaction product on the desulfurizer, nanoparticles for improving the desulfurization efficiency, and a solvent.

[0010] or a combination of a fluid containing a solute and a solvent for dissolving the desulfurization reaction product on the desulfurization agent, and a fluid containing nanoparticles and a solvent for improving the desulfurization efficiency,

[0011] Or it can be a combination of a fluid containing a solute and a solvent for dissolving the desulfurization reaction product on the desulfurization agent, a fluid containing nanoparticles for improving the desulfurization efficiency and a solvent, and a fluid containing a solvent but no solute and nanoparticles.

[0012] Further, it also includes step 3,

[0013] Step 3. The mixed flue gas after the desulfurization reaction is transported to the bag filter for dust removal, and then discharged into the atmosphere through the chimney.

[0014] Furthermore, the solute is ammonia water and / or ammonium salt, the mass concentration of the solute in the nanofluid is 1-5%, and when the solute is a combination of multiple solutes, the ratio of the minimum mass concentration to the maximum mass concentration of the multiple solutes is 0-0.5:1.

[0015] Furthermore, the nanoparticles are a combination of one or more of vanadium oxide, iron oxide, iron oxyhydroxide, magnesium sulfate, calcium oxide, aluminum oxide, and silicon dioxide; the mass concentration of the nanoparticles in the nanofluid is 0.5 to 5%, and when the nanoparticles are a combination of multiple types, the ratio of the minimum mass concentration to the maximum mass concentration of the multiple nanoparticles is 0 to 0.5:1.

[0016] Furthermore, the temperature of the high-efficiency desulfurization zone is controlled between 50°C and 350°C.

[0017] Further, the relative humidity W1 of the flue gas to be treated before the desulfurization reaction in the flue gas zone m1 to be treated is obtained;

[0018] Obtaining the relative humidity W2 of the flue gas to be treated after desulfurization in the desulfurization reaction zone m2, and / or the relative humidity W3 in the mixed flue gas zone m3 before entering the dry dust collector after the desulfurization reaction;

[0019] At the same time, the SO2 concentration value of the flue gas at the chimney outlet is obtained;

[0020] Take the maximum value among the relative humidity W1, W2 and / or W3, and coordinate with the flue gas SO2 concentration value at the chimney outlet to dynamically control the injection point γ1, injection flow rate Q1, injection direction α1, injection duration t1, and injection interval φ1 of the nanofluid to control the change in flue gas humidity caused by the injection of the nanofluid, so that the flue gas relative humidity does not reach the flue gas saturation humidity due to the increase in the fluid injection, so that the flue gas to be treated has a certain relative humidity without condensation, so as to improve the desulfurization efficiency, and thereby make the flue gas SO2 concentration at the chimney outlet meet the emission standard requirements.

[0021] Furthermore, the desulfurizer is a calcium-based desulfurizer.

[0022] Furthermore, the flue gas to be treated has a SO2 concentration lower than 400 mg / Nm 3 of smoke.

[0023] A device for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluids is used to implement the method of improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluids. The device includes a nanofluid supply facility for providing nanofluids, a nanofluid injector for injecting nanofluids into a desulfurization reaction zone, and a control system for controlling the dynamic injection of nanofluids.

[0024] Furthermore, the nanofluid supply facility comprises a nanofluid generator, a nanofluid delivery switch valve, a fluid pump, a nanofluid injection time control solenoid valve, a nanofluid injection flow control regulating valve and a nanofluid injection site switch valve which are sequentially connected along the flow direction of the nanofluid, and the outlet of the nanofluid injection site switch valve is connected to the nanofluid injector to realize the nanofluid supply to the nanofluid injector;

[0025] The nanofluid generator, nanofluid delivery switch valve, nanofluid injection time control solenoid valve, nanofluid injection flow control regulating valve and nanofluid injection site switch valve are all connected to the control system to realize the dynamic injection of nanofluid.

[0026] Furthermore, the nanofluid injector is arranged in the flue gas duct and / or the desulfurization reactor, and the nanofluid injector is a multi-fluid injector and has at least two groups of forward / reverse spraying injection heads, and each group of injection heads is distributed in a ring shape.

[0027] Furthermore, the diameter of the droplets sprayed by the multi-fluid injector is not greater than 50 microns, and the angle between the nanofluid outlet direction of the injector head and the direction of the incoming smoke flow velocity is between -180° and 180°.

[0028] Furthermore, an automatic flue gas monitoring system connected to the control system is arranged at the inlet of the flue gas duct and the outlet of the chimney to detect the SO2 concentration of the flue gas, and a temperature and pressure detector and a relative humidity detector connected to the control system are provided on the flue gas duct and / or the desulfurization reactor on the outlet side of the desulfurization reaction zone.

[0029] The beneficial effects of the present invention are:

[0030] The present invention proposes a method and device for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluids. The core of the method is that the dynamic injection of nanofluids can significantly improve the desulfurization efficiency and reduce the desulfurization cost, meeting the national requirements for ultra-low emissions of flue gas SO2. The method innovatively uses a nano-injector to inject nanofluids containing specific solutes, nanoparticles and solvents into a desulfurization reactor and / or a flue gas duct, and mixes with a desulfurizer to form an efficient desulfurization reaction zone. The solutes in the nanofluid can dissolve the reaction products on the surface of the desulfurizer and expose the reaction sites in time; the nanoparticles can be "fixed" on the desulfurizer in situ to improve the desulfurization reaction efficiency; at the same time, the injection of the nanofluid can also appropriately reduce the flue gas temperature, form a liquid film on the surface of the desulfurizer, and accelerate the reaction of SO2 and the desulfurizer.

[0031] The present invention can increase the calcium-based dry desulfurization efficiency from 70% to 90% through the dynamic injection of nanofluids, which is difficult to achieve with the dry desulfurization technology using the traditional spray powder desulfurizer. Secondly, through the implementation of the present invention, the actual Ca / S ratio of the calcium-based dry desulfurizer is reduced from 4 to about 3, which greatly improves the utilization rate of the desulfurizer, reduces the cost of flue gas desulfurization, and has significant economic benefits.

[0032] In addition, the device of the present invention is reasonably designed and easy to operate. The control system realizes dynamic regulation of nanofluid injection, ensuring the stable progress of the desulfurization reaction. The perfect combination of nanofluid supply facilities, nanofluid injectors and control systems makes the present invention not only innovative but also highly practical. The device can be widely used in various flue gas desulfurization scenarios, providing a new solution for industrial waste gas treatment.

[0033] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0035] Figure 1 A schematic diagram of the structure of a device for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid in Example 1 Figure 1 ;

[0036] Figure 2 A schematic diagram of the structure of a device for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid in Example 1 Figure 2 ;

[0037] Figure 3 Schematic diagram of the microstructure of the desulfurizer in Example 1;

[0038] Figure 4 Schematic diagram of the microstructure of nanoparticles in situ fixed on the desulfurizer in Example 1;

[0039] Figure 5 is a schematic diagram of the partial structure of the nanofluid ejector in Example 1;

[0040] Figure 6 This is a schematic diagram of the structure of a device for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid in Example 2.

[0041] Figure numerals: 1-flue gas to be treated; 2-desulfurizer storage bin; 3-flue gas pipeline; 4-desulfurizer; 5-nanofluid injector; 6-control system; 7-nanofluid generator; 8-nanofluid delivery switch valve; 9-fluid pump; 10-desulfurized flue gas; 11-bag filter; 12-flue gas pump; 13-chimney; 14-flue gas automatic monitoring system; 15-nanofluid injection time control solenoid valve; 16-nanofluid injection flow control regulating valve; 17-nanofluid injection site switch valve; 18-temperature and pressure detector; 19-relative humidity detector; 20-desulfurization reactor; 41-calcium hydroxide particles; 42-calcium sulfate particles; 43-nanoparticles; 44-pores left after the calcium sulfate particles are dissolved; 51-nanofluid injector nozzle; 52-nanofluid injector annular distribution ring; 53-annular distribution ring support tube. DETAILED DESCRIPTION

[0042] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0043] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0044] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0045] Example 1

[0046] like Figure 1 and Figure 2 As shown, a method for improving the efficiency of calcium-based dry desulfurization by dynamic nanofluid injection is shown, wherein the flue gas 1 to be treated is delivered to the desulfurization reactor through the flue gas pipeline 3, the desulfurizer 4 is injected into the flue gas pipeline 3 from the desulfurizer storage bin 2, and the nanofluid generated by the nanofluid generator 7 is sequentially delivered to the nanofluid injector 5 through the nanofluid delivery switch valve 8 and the fluid pump 9, and then injected into the flue gas pipeline 3 through the nanofluid injector 5, so that the nanofluid is mixed with the desulfurizer 4 in the flue gas pipeline 3 to form an efficient desulfurization reaction zone;

[0047] The desulfurized flue gas 10 after desulfurization treatment in the desulfurization reaction zone enters the bag filter 11 (dry dust collector) to remove dust, and then is transported to the chimney 13 through the flue gas pump 12 and discharged into the atmosphere.

[0048] On the other hand, this embodiment provides a device for implementing the method, including a nanofluid supply facility (the nanofluid supply facility includes a nanofluid generator 7, a nanofluid delivery switch valve 8 and a fluid pump 9 connected in sequence along the flow direction of the nanofluid), a control system 6, an automatic flue gas monitoring system 14, a nanofluid injection time control solenoid valve 15, a nanofluid injection flow control regulating valve 16, a nanofluid injection site switch valve 17, a temperature and pressure detector 18, a relative humidity detector 19 and a nanofluid injector 5.

[0049] like Figure 1 and 5As shown, the nanofluid injector 5 has two groups of longitudinal spraying injection heads arranged at intervals along the flue gas flow direction, each group of injection heads includes an injector nozzle 51, an injector annular distribution ring 52 and an annular distribution ring support tube 53, a plurality of the injector nozzles 51 are evenly distributed on the injector annular distribution ring 52 along the circumferential direction, and the annular distribution ring support tube 53 is used to fix the injector annular distribution ring 52 to the flue gas duct 3.

[0050] The nanofluid injection point switch valve 17 is connected to two groups of injection heads respectively, so as to control the injection point of the nanofluid injector 5. In another embodiment, the nanofluid injector 5 has one group of injection heads for forward spraying and one group of injection heads for reverse spraying arranged at intervals along the flow direction of the smoke, or a combination of multiple groups of injection heads for reverse spraying and injection heads for forward spraying.

[0051] like Figure 1 As shown, the nanofluid injector 5 has two groups of injection heads arranged at intervals along the flow direction of the smoke; Figure 2 As shown, the nanofluid injector 5 has two groups of reverse-spraying injection heads arranged at intervals along the flue gas flow direction.

[0052] The flue gas automatic monitoring system 14 is respectively arranged at the entrance of the flue gas duct 3 and the exit of the chimney 13, so as to obtain the parameters of the flue gas zone m1 to be treated before the desulfurization reaction, such as SO2 concentration, temperature T1, pressure P2, relative humidity W1, and the parameters of the clean flue gas at the exit of the chimney 13 after desulfurization and dust removal, such as SO2 concentration; the temperature and pressure detector 18 and the relative humidity detector 19 are arranged in the desulfurization reaction zone m2 in the flue gas duct 3 and the mixed flue gas zone m3 before entering the dry dust collector after the desulfurization reaction zone, so as to obtain the temperature T2, pressure P2, relative humidity W2 of the desulfurization reaction zone m2, and the temperature T3, pressure P3, relative humidity W3 of the mixed flue gas zone m3, and the desulfurizer storage bin 2, the flue gas automatic monitoring system 14, the temperature and pressure detector 18 and the relative humidity detector 19 are all connected to the control system 6;

[0053] The nanofluid injection time control solenoid valve 15, the nanofluid injection flow control regulating valve 16 and the nanofluid injection site switch valve 17 are arranged in sequence between the fluid pump 9 and the nanofluid injector 5 along the nanofluid conveying direction, and are connected to the control system 6 to realize dynamic injection of the nanofluid and dynamic adjustment of the desulfurizer injection amount.

[0054] Specifically, the flue gas 1 to be treated is flue gas containing SO2, which is introduced into the flue gas pipeline 3 and mixed with the desulfurizer powder sprayed from the desulfurizer storage bin 2. After the desulfurization reaction, it enters the bag filter 11 to obtain clean flue gas, and then is transported to the chimney 13 through the flue gas pump 12 and discharged into the atmosphere. In order to improve the reaction activity of the desulfurizer and strengthen the contact between the desulfurizer and the flue gas containing SO2, the nanofluid injector 5 placed on the flue gas pipeline 3 sprays the nanofluid in a direction 180° to the flue gas flow direction to strengthen the contact between the flue gas and the desulfurizer.

[0055] like Figure 3 and Figure 4 As shown, after the nanofluid is sprayed into the desulfurization reaction zone, the solute (ammonia water) contained in the nanofluid for dissolving the desulfurization reaction product (calcium sulfate) on the desulfurizer dissolves the calcium sulfate 42 generated by the reaction of the desulfurizer 41 with SO2, thereby leaving a number of pores 44 left after the calcium sulfate particles are dissolved, so that the desulfurizer 41 timely exposes the surface reaction active sites;

[0056] At the same time, the nanofluid contains nanoparticles 43 (iron oxide nanoparticles) that enhance the desulfurization reaction. Under the action of the nanofluid ejector 5, the reactive active sites can be increased in situ on the surface of the powdered desulfurizer 41 in the desulfurization reaction zone;

[0057] At the same time, the solvent (water) in the nanofluid can increase the relative humidity of the powdered desulfurizer 41 and the SO2-containing flue gas, forming a liquid film on the surface of the desulfurizer 41, so that SO2 and the desulfurizer can quickly undergo a desulfurization reaction in an ionic state.

[0058] The method in this embodiment also includes: the control system obtains the relative humidity W1 of the untreated flue gas zone m1 before the desulfurization reaction through the flue gas automatic monitoring system 14; obtains the relative humidity W2 of the flue gas passing through the desulfurization reaction zone m2 and / or the relative humidity W3 of the mixed flue gas zone m3 before entering the dry dust collector after the desulfurization reaction; and obtains the SO2 concentration value of the flue gas at the chimney at the same time. Take the maximum value of the relative humidity W1, W2 and / or W3, and coordinate the feedback of the flue gas SO2 concentration value at the chimney to dynamically control the injection point γ1, injection flow Q1, injection direction α1, injection duration t1, and injection interval duration φ1 of the nanofluid to control the change in flue gas humidity caused by the injection of the nanofluid, so that the relative humidity of the flue gas does not reach the saturated humidity of the flue gas due to the increase of the fluid injection, ensure that the flue gas has a certain relative humidity without condensation, maintain the efficiency of high-efficiency desulfurization, and make the outlet flue gas SO2 concentration meet the emission standard requirements.

[0059] Generally, when the temperature T5 is between 50°C and 100°C, the relative humidity W2 of the desulfurization reaction zone is between 0% and 50%, preferably between 5% and 20%; when the temperature T5 is above 100°C, the relative humidity W2 of the desulfurization reaction zone is between 0% and 1%, so as to ensure that while ensuring high desulfurization efficiency, there is no condensation in the flue gas, and there is no desulfurizer lumping, material compaction, bed pressure fluctuation or even bed collapse.

[0060] The principle of coordinated control of outlet flue gas SO2 concentration and relative humidity is as follows: for example, the relative humidity W1 of the flue gas zone m1 to be treated is 10%, the relative humidity W2 of the desulfurization reaction zone m2 and the relative humidity W3 of the mixed flue gas zone m3 after the desulfurization reaction are detected, and the outlet SO2 concentration value is coordinated (when the concentration increases, the injection amount is increased), and the amount of nanofluid sprayed is dynamically adjusted to make the maximum humidity value fall within the range of 10% to 20%, and maintain the efficiency of high-efficiency desulfurization, so that the outlet flue gas SO2 concentration meets the emission standard requirements.

[0061] Specifically, the solvent in the nanofluid is preferably water, and the solute used to dissolve the desulfurization reaction product on the desulfurizer is ammonia water, ammonium salt (ammonium chloride, ammonium nitrate, ammonium chloride, ammonium acetate, carbon carbonate, ammonium bicarbonate), etc., preferably ammonia water; the solute can be one, two or a combination of multiple; the mass concentration of the combined solute is 1-5%, preferably 1-3%, and the ratio of the minimum mass concentration to the maximum mass concentration of the multiple solutes is 0-0.5:1; the nanoparticles used to improve the desulfurization efficiency are vanadium oxide, iron oxide, oxyhydroxide iron, magnesium sulfate, calcium oxide, aluminum oxide, silicon dioxide, etc., preferably iron oxide and oxyhydroxide iron. The single Ca(OH)2 desulfurizer itself has low activity and reacts slowly with SO2. The main reason is that the oxidation reaction of SO2 to SO3 or CaSO3 to CaSO4 is the key to restricting the reaction rate of Ca(OH)2 fixing SO2, and catalyzes the oxidation reaction. Therefore, adding nanoparticles such as iron oxide or oxyhydroxide iron can improve the calcium-based desulfurization efficiency;

[0062] The nanoparticles are one, two or more combinations; the mass concentration of the combined nanoparticles is 0.5-5%, preferably 1-3%, and the ratio of the minimum mass concentration to the maximum mass concentration of the multiple nanoparticles is 0-0.5:1.

[0063] Furthermore, the temperature of the desulfurization reaction zone is controlled between 50°C and 350°C.

[0064] Further, the implementation content and effect of the present invention are explained, and a representative experiment of flue gas desulfurization under typical working conditions is carried out by using the method of nanofluid dynamic injection in this embodiment to improve the efficiency of calcium-based dry desulfurization. The initial experimental conditions are as follows:

[0065] 1) Inlet conditions of the flue gas to be treated: flue gas temperature 72°C, relative humidity W1 of the flue gas area to be treated m1 is 1%, SO2 concentration value 132mg / Nm 3 ;

[0066] 2) Spray calcium-based desulfurizer alone to adjust the inlet Ca / S molar ratio of desulfurized flue gas (~4.0) and control the outlet SO2 concentration to 35 mg / Nm 3 .

[0067] Experimental conditions and results of adding nanofluids:

[0068] 1) The solvent is preferably water, and 5% ammonia water is added to dilute it to 1%; an appropriate amount of iron oxide and aluminum oxide nanoparticles are added, and the ratio of the two is 2:1, so that the total mass concentration of nanoparticles in the solvent is 3%, and the nanofluid configuration is completed;

[0069] 2) Start the nanofluid supply system and refine it into particles below 40 μm through an atomizing spray gun and spray it into the desulfurization reaction zone m2; at the same time, detect the SO2 concentration value and relative humidity W3 of the mixed flue gas zone m3.

[0070] 3) Gradually increase the injection amount of nanofluid and reduce the injection amount of calcium-based desulfurizer to maintain the SO2 concentration of flue gas at the chimney outlet at 35mg / Nm 3 The relative humidity W3 detected is recorded as follows: When W3 increases from 1% to 5%, the Ca / S ratio decreases from 4.0 to 3.6, and the SO2 concentration of the flue gas at the chimney outlet increases from 35 mg / Nm 3 Reduced to 30mg / Nm 3 When W3 increases to 10.2%, the Ca / S ratio decreases to 3.1, and the SO2 concentration of the flue gas at the chimney outlet is 23 mg / Nm 3 When W3 increases to 19.8%, the Ca / S ratio decreases to 2.5, and the SO2 concentration of the flue gas at the chimney outlet is 9.8 mg / Nm 3 .

[0071] The method and device for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluids described in this embodiment were used for flue gas desulfurization, and the efficiency of calcium-based dry desulfurization was successfully increased from 70% to 90%, which is difficult to achieve with traditional dry desulfurization technology. Secondly, the method significantly improved the utilization efficiency of the desulfurizer, reducing the SO2 concentration in the flue gas from 132mg / Nm 3 Reduced to 10mg / Nm 3 Below, reaching the national requirement of 35mg / Nm 3Ultra-low emission standards have made positive contributions to environmental protection. Finally, through the implementation of the present invention, the actual Ca / S ratio of the calcium-based dry desulfurizer is reduced from 4 to below 3, which greatly improves the utilization rate of the desulfurizer, reduces the cost of flue gas desulfurization, and has significant economic benefits.

[0072] Example 2

[0073] The difference between this embodiment and embodiment 1 is that the method is to directly inject the nanofluid into the desulfurization reactor 20 connected to the flue gas pipeline 3 through the nanofluid injector 5, so as to form an efficient desulfurization reaction zone m2 in the desulfurization reactor. The solvent of the nanofluid supplied by the nanofluid supply facility is a mixture of water and ethanol, the solute is 10% ammonia water, the nanoparticles are 0.5% iron oxide and 1% aluminum oxide, and the temperature is 90°C. The nanofluid injector 5 injects the nanofluid into the desulfurization reactor along a direction of 160° with the flue gas flow direction. After the nanofluid is sprayed into the desulfurization reaction zone m2, the solute ammonia water used to dissolve the desulfurization reaction product calcium sulfate in the nanofluid dissolves the calcium sulfate 42 generated by the reaction of the desulfurizer 41 and SO2, so that the desulfurizer 41 exposes the surface reaction active sites in time; at the same time, the nanofluid contains nanoparticles of iron oxide and aluminum oxide 43 that improve the desulfurization reaction. Under the action of the injector, the reaction active sites can be increased in situ on the surface of the powdered desulfurizer 41 in the desulfurization reaction zone; at the same time, the solvent in the nanofluid can increase the relative humidity of the powdered desulfurizer 41 and the SO2-containing flue gas, and form a liquid film on the surface of the desulfurizer, so that SO2 and the desulfurizer can quickly undergo a desulfurization reaction in an ionic state, so as to achieve the purpose of improving the efficiency of calcium-based dry desulfurization.

[0074] Correspondingly, in this embodiment, the temperature and pressure detector 18 and the relative humidity detector 19 are arranged after the desulfurization reaction zone m2 in the desulfurization reactor 20 to obtain the relative humidity W3 of the mixed flue gas m3 after the desulfurization reaction.

[0075] The method in this embodiment also includes: obtaining the relative humidity W1 of the flue gas zone m1 to be treated before the desulfurization reaction; obtaining the relative humidity W3 of the mixed flue gas zone m3 before entering the dry dust collector after the desulfurization reaction; and obtaining the SO2 concentration value of the flue gas at the chimney at the same time. Take the maximum value of the relative humidity W1 and W3, and coordinate the feedback of the flue gas SO2 concentration value at the chimney to dynamically control the injection point γ1, injection flow Q1, injection direction α1, injection duration t1, and injection interval φ1 of the nanofluid to control the change in flue gas humidity caused by the injection of the nanofluid, so that the relative humidity of the flue gas does not reach the saturated humidity of the flue gas due to the increase of the fluid injection, ensure that the flue gas has a certain relative humidity without condensation, maintain the efficiency of high-efficiency desulfurization, and make the outlet flue gas SO2 concentration meet the emission standard requirements.

[0076] Example 3

[0077] The difference between this embodiment and embodiment 1 is that the method is to inject the nanofluid to the desulfurizer 4 through the nanofluid injector 5; or directly inject the nanofluid to the upstream position of the desulfurizer 4; or directly inject the nanofluid into the desulfurizer injection pipeline to first form a mixture of the nanofluid and the desulfurizer, and then inject it into the desulfurization reactor and / or the flue gas pipeline to form an efficient desulfurization reaction zone m2. The purpose of improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid is also achieved.

[0078] Example 4

[0079] The difference between this embodiment and embodiment 1 is that the method is to simultaneously inject the nanofluid into the desulfurization reactor connected to the flue gas duct 3 and the flue gas duct 3 through the nanofluid injector 5, thereby forming a desulfurization reaction zone m2 in the desulfurization reactor 20 and the flue gas duct 3 at the same time.

[0080] Example 5

[0081] The difference between this embodiment and the above embodiment is that the method realizes the combination of dynamic injection of solvent, solute for dissolving the desulfurization reaction product, and nanoparticles for improving the desulfurization efficiency of the desulfurizer through a control system. First, a solvent containing solutes and nanoparticles that are easily soluble reaction products, calcium sulfate, is sprayed for a period of t2 to increase the humidity of the desulfurizer; then, a solvent and a mixed solution containing solutes for dissolving the desulfurization reaction product, calcium sulfate, are sprayed for a period of t3 to expose the reactive sites on the surface of the desulfurizer; then, a nanofluid is sprayed for a period of t4. Alternatively, the injection sequence is used to randomly combine the operating parameters such as the temperature and pressure of the actual desulfurization reaction zone. Through the above combination, the purpose of improving the efficiency of SDS calcium-based dry desulfurization is further achieved by combining dynamic humidification and gas mixing.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluids, characterized in that: The following steps are involved: Step 1. The flue gas to be treated is sent to the desulfurization reactor through the flue gas pipeline, and the desulfurizer is sprayed into the flue gas pipeline and / or the desulfurization reactor to desulfurize the flue gas; Step 2. Dynamically injecting the nanofluid into the desulfurization reactor and / or the flue gas duct to mix with the desulfurizer in the desulfurization reactor and / or the flue gas duct to form a desulfurization reaction zone.

2. The method for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid according to claim 1, characterized in that: The nanofluid is a fluid containing a solute for dissolving the desulfurization reaction product on the desulfurizer, nanoparticles for improving the desulfurization efficiency, and a solvent. or a combination of a fluid containing a solute and a solvent for dissolving the desulfurization reaction product on the desulfurization agent, and a fluid containing nanoparticles and a solvent for improving the desulfurization efficiency, Or it can be a combination of a fluid containing a solute and a solvent for dissolving the desulfurization reaction product on the desulfurization agent, a fluid containing nanoparticles for improving the desulfurization efficiency and a solvent, and a fluid containing a solvent but no solute and nanoparticles.

3. The method for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid according to claim 2, characterized in that: Also includes step 3, Step 3. The mixed flue gas after the desulfurization reaction is transported to a dry dust collector for dust removal, and then discharged into the atmosphere through a chimney.

4. The method for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid according to claim 2, characterized in that: The solute is ammonia water and / or ammonium salt, the mass concentration of the solute in the nanofluid is 1-5%, and when the solute is a combination of multiple solutes, the ratio of the minimum mass concentration to the maximum mass concentration of the multiple solutes is 0-0.5:

1.

5. The method for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid according to claim 4, characterized in that: The nanoparticles are a combination of one or more of vanadium oxide, iron oxide, iron oxyhydroxide, magnesium sulfate, calcium oxide, aluminum oxide, and silicon dioxide. The mass concentration of the nanoparticles in the nanofluid is 0.5-5%. When the nanoparticles are a combination of multiple types, the ratio of the minimum mass concentration to the maximum mass concentration of the multiple nanoparticles is 0-0.5:

1.

6. The method for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid according to claim 1, characterized in that: The temperature of the high-efficiency desulfurization zone is controlled between 50°C and 350°C.

7. The method for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid according to claim 3, characterized in that: Obtaining the relative humidity W1 of the flue gas to be treated before the desulfurization reaction in the flue gas zone m1 to be treated; Obtaining the relative humidity W2 of the flue gas to be treated after desulfurization in the desulfurization reaction zone m2, and / or the relative humidity W3 in the mixed flue gas zone m3 before entering the dry dust collector after the desulfurization reaction; At the same time, the SO2 concentration value of the flue gas at the chimney outlet is obtained; Take the maximum value among the relative humidity W1, W2 and / or W3, and coordinate with the flue gas SO2 concentration value at the chimney outlet to dynamically control the injection point γ1, injection flow rate Q1, injection direction α1, injection duration t1, and injection interval φ1 of the nanofluid to control the change in flue gas humidity caused by the injection of the nanofluid, so that the flue gas relative humidity does not reach the flue gas saturation humidity due to the increase in the fluid injection, so that the flue gas to be treated has a certain relative humidity without condensation, so as to improve the desulfurization efficiency, and thereby make the flue gas SO2 concentration at the chimney outlet meet the emission standard requirements.

8. The method for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid according to claim 1, characterized in that: The desulfurizer is a calcium-based desulfurizer.

9. The method for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid according to claim 1, characterized in that: The flue gas to be treated has a SO2 concentration lower than 400 mg / Nm 3 of smoke.

10. A device for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluids, characterized in that: The device is used to implement the method described in any one of claims 1 to 9, comprising a nanofluid supply facility for providing nanofluid, a nanofluid injector for injecting the nanofluid into a desulfurization reaction zone, and a control system for controlling the dynamic injection of the nanofluid.

11. The device for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid according to claim 10, characterized in that: The nanofluid supply facility comprises a nanofluid generator, a nanofluid delivery switch valve, a fluid pump, a nanofluid injection time control solenoid valve, a nanofluid injection flow control regulating valve and a nanofluid injection site switch valve which are sequentially connected along the flow direction of the nanofluid, and the outlet of the nanofluid injection site switch valve is connected to the nanofluid injector to realize the nanofluid supply to the nanofluid injector; The nanofluid generator, nanofluid delivery switch valve, nanofluid injection time control solenoid valve, nanofluid injection flow control regulating valve and nanofluid injection site switch valve are all connected to the control system to realize the dynamic injection of nanofluid.

12. The device for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid according to claim 10, characterized in that: The nanofluid injector is arranged in the flue gas duct and / or the desulfurization reactor. The nanofluid injector is a multi-fluid injector and has at least two groups of forward / reverse injection heads, and each group of injection heads is distributed in a ring shape.

13. The device for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid according to claim 12, characterized in that: The diameter of the droplets sprayed by the multi-fluid injector is no more than 50 microns, and the angle between the nanofluid outlet direction of the injector head and the direction of the incoming smoke flow velocity is between -180° and 180°.

14. The device for improving the efficiency of calcium-based dry desulfurization by dynamic injection of nanofluid according to claim 10, characterized in that: An automatic flue gas monitoring system connected to the control system is arranged at the inlet of the flue gas duct and the outlet of the chimney, and a temperature and pressure detector and a relative humidity detector connected to the control system are provided on the flue gas duct and / or the desulfurization reactor at the outlet side of the desulfurization reaction zone.

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