[0067]
[0068] The present invention also provides a method for preparing a desulfurization and denitrification agent, which includes the following steps:
[0069] (1) The following components will be formulated into a mixture;
[0070] (2) The prepared mixture is made into a nano-level desulfurization and denitrification agent.
[0071] The components include MgO, SiO 2 , CaO, Fe 2 O 3 , Al 2 O 3 , CuO and MnO 2; Optionally, it also includes KMnO 4.
[0072] The preparation method according to the present invention preferably includes the following steps:
[0073] (1) Prepare a mixture of the above components according to the ratio;
[0074] (2) The prepared mixture is made into a nano-level desulfurization and denitrification agent.
[0075] The desulfurization and denitrification agent includes:
[0076] MgO is 40-50 parts by weight, preferably 45-48 parts by weight;
[0077] CaO is 0.1 to 1 part by weight, preferably 0.5 to 0.8 part by weight;
[0078] SiO 2 10-20 parts by weight, preferably 12-15 parts by weight;
[0079] Fe 2 O 3 5-20 parts by weight, preferably 6-15 parts by weight;
[0080] Al 2 O 3 5-10 parts by weight, preferably 6-8 parts by weight;
[0081] CuO is 1-10 parts by weight, preferably 5-8 parts by weight;
[0082] MnO 2 It is 1 to 4 parts by weight, preferably 1.5 to 2 parts by weight.
[0083] Preferably, the content of active magnesium oxide in the MgO is 60 wt% or more, preferably 60-80 wt%, and more preferably 65-70 wt%.
[0084] Preferably, the desulfurization and denitrification agent also includes KMnO 4. KMnO 4 The amount used is 1 to 10 parts by weight, preferably 1 to 8 parts by weight, more preferably 1 to 6, still more preferably 1 to 4, still more preferably 1 to 2 parts by weight.
[0085] In the present invention, preferably, step (2) includes the following steps:
[0086] ① Crush the mixture into nanometer powder;
[0087] ② Formulate the nano-sized powder into a paste-like substance;
[0088] ③ Roasting the slurry material to obtain the desulfurization and denitrification agent.
[0089] The pulverization of step ① can use any equipment, as long as it can pulverize the above-mentioned mixture to nanometer level; preferably, it is pulverized by a high-energy ball mill; the number of ball milling using a ball mill is not particularly limited, for example, it can be ball milled once or twice or more, as long as It is sufficient to reach the required particle size range. The particle size of the components after pulverization ranges from 10 to 60 nm; the particle size is more preferably 10 to 50 nm; more preferably 15 to 40 nm; still more preferably 20 to 30 nm.
[0090] Step ② It is preferable to use water to prepare the nanometer powder into a slurry; preferably, a thickener can be used in the preparation; the thickener can be any industrial or edible thickener with a constant pH value, preferably alkali Sexual thickeners, such as HPMC (hydroxypropyl methyl cellulose) and the like.
[0091] Preferably, in step ②, the nano powder is added to water, mixed evenly, and then added into the industrial thickener HPMC to prepare a slurry-like substance.
[0092] The roasting in step ③ can use any roasting equipment, preferably a single furnace chamber; preferably, the roasting temperature is 600-800°C, preferably 650-750°C; and the roasting time is 1.5-2 hours, preferably 1.6-1.8 hours.
[0093] The firing can be performed once or twice or more.
[0094] Preferably, the present invention uses secondary roasting. In the second firing, the first firing is performed at 300-500°C, preferably 350-450°C, more preferably 380-420°C, and then the second firing at 600-800°C, preferably 650-750°C Roasting.
[0095] Preferably, step ③ is performed as follows: the mixed slurry material is sent to a single-chamber furnace, and it is roasted at a temperature ranging from 300°C to 500°C, preferably 350 to 450°C, more preferably 380 to 420°C for 1 hour. After forming, it is sent to a single-chamber furnace for secondary roasting at a temperature range of 600°C to 800°C for 1.5 hours to obtain a desulfurization and denitrification agent.
[0096] Or preferably, step ③ is performed as follows: the mixed slurry material is sent into a single-chamber furnace, and calcined at a temperature range of 600°C to 800°C, preferably 650 to 750°C, for 1.5 to 2 hours to obtain desulfurization Denitrification agent.
[0097] According to the preparation method of the above-mentioned desulfurization and denitrification agent, preferably, the figure 1 The process shown is, that is, the mixture is ball milled once, roasted once, then ball milled again, roasted again after molding, and then tested. If the particle size of the desulfurization and denitrification agent meets the above-mentioned nanometer level after roasting, the temperature will be lowered. To make a finished product, if the above-mentioned nanometer level is not met, the above-mentioned ball milling-roasting process is repeated until the particle size meets the requirements.
[0098]
[0099] The present invention also provides the use of the desulfurization and denitrification agent for simultaneous desulfurization and denitration of flue gas; the flue gas can be any flue gas containing sulfur dioxide, nitrogen monoxide, nitrogen dioxide and other components. The desulfurization and denitrification agent is used to remove SO in flue gas 2 And NO X (E.g. NO, NO 2 Etc.); The desulfurization and denitrification agent can use any flue gas desulfurization technology, such as dry desulfurization technology, wet desulfurization technology, and can simultaneously remove NO during the desulfurization process X.
[0100] According to the application of the present invention, it is preferably used for simultaneous removal of NO during flue gas desulfurization in a wet desulfurization tower X.
[0101] According to the use of the present invention, it preferably includes the following steps:
[0102] (A) Pulping step: the above-mentioned desulfurization and denitrification agent is made into a slurry.
[0103] Since the desulfurization and denitrification agent is in powder form, the present invention requires a pulping step.
[0104] Preferably, the desulfurization and denitrification agent is added to water to make a slurry, and it is more preferable to form a metal oxide-based slurry after aging.
[0105] (B) Desulfurization and denitration steps: contact the flue gas with the slurry to remove SO in the flue gas 2 , NO X.
[0106] The method of contact is not particularly limited, and it may be a method of spraying the slurry or a method of passing flue gas into the slurry; the method of slurry spraying is more preferred.
[0107] The desulfurization and denitrification equipment used in the desulfurization and denitrification step is not particularly limited, as long as it can realize the contact between the desulfurization and denitrification agent and the flue gas, and is preferably a desulfurization tower used in a wet conventional calcium method or a magnesium method.
[0108] According to the use of the present invention, preferably, the oxygen content in the flue gas is adjusted; preferably, the oxygen content in the flue gas is controlled at 8-15 vt%, more preferably 10-12 vt%. Due to the adsorbent for NO 2 The adsorption is better than the adsorption of NO, so as far as possible to promote the oxidation of NO to NO 2 , Which is conducive to the effect of nano-oxide-based adsorbent on NO X Removal. In the present invention, the nitric oxide in the flue gas reacts with oxygen in the strong oxygen section of the flue gas in the system process and is converted into NO 2 , The conversion efficiency is about 30%. This process will reduce the pressure of the chemical and physical adsorption reaction in the subsequent towers and increase the denitration efficiency by more than 20%.
[0109] According to the use of the present invention, it preferably includes the following steps:
[0110] <1> Steps to adjust the oxygen content in the flue gas;
[0111] <2> Pulping step: prepare nano-scale desulfurization and denitrification agent into slurry for use;
[0112] <3> Desulfurization and denitrification step: contact the flue gas after adjusting the oxygen content with the slurry.
[0113] Preferably, the oxygen content in the flue gas is controlled at 8-15 vt%.
[0114] Preferably, the step of adjusting the oxygen content in the flue gas is performed before the flue gas enters the end of the desulfurization and denitration equipment.
[0115] Preferably, the step of adjusting the oxygen content in the flue gas is realized by an oxygen adjusting device.
[0116] Preferably, the oxygen regulating device is arranged in the flue before the flue gas enters the end of the desulfurization and denitration equipment (for example, the desulfurization tower).
[0117] Preferably, the oxygen content in the flue gas is adjusted in the flue gas section with a temperature of 125-145°C, preferably 130-140°C. That is, the oxygen regulator is arranged in the flue gas section where the temperature in the flue before the flue gas enters the end of the desulfurization and denitration equipment (for example, the desulfurization tower) is 125-145°C, preferably 130-140°C.
[0118] The inventor of this application found in practice that NO, NO 2 There is a phenomenon of reaction acceleration or deceleration between oxygen and oxygen in a certain temperature environment. In the present invention, when the acceleration phenomenon occurs, NO can generate NO with oxygen in a short time. 2 , Because NO is commonly called inert gas, it is difficult to react with other substances, so in the process of designing the denitration system, how to increase NO production as much as possible 2 The ratio of is the key to whether the denitration efficiency reaches the set value. When the flue gas temperature is 125~145℃, the reaction between NO and oxygen is the fastest. On the contrary, the reaction speed starts to decay when the temperature is higher than 145℃ or lower than 125℃, so In the present invention, before the flue gas enters the desulfurization tower end, a suitable temperature section is selected, and an oxygen content control and adjustment device is installed, so as to allow the NO in the flue gas to be adsorbed enough at this temperature end to react and generate NO 2 Of oxygen.
[0119] According to the use of the present invention, it preferably includes the following steps:
[0120] a. The oxygen regulator is installed at the front end of the flue gas entering the desulfurization tower to control the oxygen content in the flue gas between 8-15vt%;
[0121] b. Send the above-mentioned nano-level desulfurization and denitrification agent to the storage tank, add water in the storage tank to prepare a slurry for use;
[0122] c. Blow the slurry into the desulfurization tower through the circulating pump, and complete the desulfurization and denitration process in the tower.
[0123] According to the application of the present invention, preferably, the oxygen regulating device includes an aeration system. When the oxygen content in the flue gas is lower than 8vt%, the aeration system is automatically turned on for oxygenation, and it stops when the oxygen content reaches 15vt%.
[0124] Preferably, the aeration system is general industrial oxygen production equipment, such as pressure swing adsorption oxygen production equipment, cryogenic oxygen production equipment.
[0125]
[0126] Denitration:
[0127] (1) NO reaches the surface of the nano-scale desulfurization and denitrification agent with the flue gas, and at the same time, NO is converted into NO under the catalytic action of the active sites of metal oxides. 2 , Accelerate its removal.
[0128] (2)NO 2 Reach the surface of the adsorbent (that is, the magnesium oxide and other components in the desulfurization and denitrification agent, the same below), and part of it is adsorbed by the surface;
[0129] (3) NO adsorbed on the surface of the adsorbent 2 Gas and water molecules react with MgO on the surface to form nitrite, and react with oxygen in the flue gas to form nitrate; part of NO 2 Enter the inside of the adsorbent through the pores of the adsorbent;
[0130] (4) NO reacts with MgO inside the adsorbent to form nitrite, and part of the nitrite reacts with oxygen entering the pores to form nitrate.
[0131] The basic reaction principle of denitrification (oxidation-catalysis)
[0132] NO 2 +H 2 O+desulfurization and denitrification agent (ESE)+catalytic oxidation→HNO 2 +Catalytic oxidation→
[0133] Stable compound+O 2 →HNO 3 +ESE
[0134] Nitric oxide (NO) is hardly soluble in water and needs to be oxidized before it can be absorbed in an aqueous solution.
[0135] When NO X Converted into nitrous acid (HNO 2 ), the desulfurization and denitrification agent (ESE) is combined with it to form a stable complex, and they are continuously oxidized to nitric acid.
[0136] HNO 2 +ESE=ESE·HNO 2
[0137] 2ESE·HNO 2 +O 2 =2ESE+2HNO 3
[0138] The combination of nano-scale desulfurization and denitrification agent with oxygen regulator can better realize the above reaction.
[0139] Desulfurization:
[0140] (1)SO 2 As the flue gas reaches the surface of the adsorbent, part of it is absorbed by the surface;
[0141] (2) Active sites of active nano-metal oxide mixture and NO in flue gas X , And also promote SO in flue gas 2 Combine with oxygen to SO 3 Conversion.
[0142] (3) SO adsorbed on the surface of the adsorbent 2 Gas and water molecules react with metal oxides on the surface to form sulfite, and react with oxygen in the flue gas to form sulfate; part of SO 2 Enter the inside of the adsorbent through the pores of the adsorbent;
[0143] (4)SO 2 It reacts with metal oxides inside the adsorbent to form sulfite, and part of the sulfite reacts with oxygen entering the pores to form sulfate.
[0144] The basic reaction principle of desulfurization:
[0145] SO 2 +H 2 O+Nano-level desulfurization and denitrification agent (ESE for short)→H 2 SO 3 +ESE→
[0146] Stable compound+O 2 →H 2 SO 4 +ESE
[0147] When SO 2 Converted into sulfurous acid (H 2 SO 3 ), desulfurization and denitrification agents (ESE) combine with them to form stable complexes, which are continuously oxidized to sulfuric acid, and then functional groups are separated from it.
[0148] H 2 SO 3 +ESE=ESE·H 2 SO 3
[0149] 2ESE·H 2 SO 3 +O 2 =2ESE+2H 2 SO 4
