阅读说明：本技术 低温干式单塔同步治理烧结烟气二氧化硫、氮氧化物方法 (Method for synchronously treating sulfur dioxide and nitrogen oxide in sintering flue gas by low-temperature dry single tower ) 是由 李和平 石振仓 韩加友 于 2018-06-01 设计创作，主要内容包括：本发明涉及一种低温干式单塔同步治理烧结烟气二氧化硫、氮氧化物的方法,所述方法包括以下步骤：1)机头电除尘,2)O<Sub>3</Sub>制备及喷入,3)NO被氧化,4)SO<Sub>2</Sub>、NO<Sub>2</Sub>脱除,5)布袋除尘。该技术方案主要解决了现有烧结烟气治理技术或只能单独脱硫,或虽能分步脱硫脱硝,但工艺复杂、装置投资大、脱除效率低、操作管理难度大、运行成本高、脱硫脱硝产物对环境造成二次污染等问题。(The invention relates to a method for synchronously treating sulfur dioxide and nitrogen oxide in sintering flue gas by a low-temperature dry single tower, which comprises the following steps of 1) electric precipitation of a machine head, 2) preparation and injection of O 3 , 3) oxidation of NO, 4) removal of SO 2 and NO 2 , and 5) bag-type dust removal.)

1. A method for synchronously treating sulfur dioxide and nitrogen oxide in sintering flue gas by a low-temperature dry single tower is characterized by comprising the following steps:

1) The electric dust removal is carried out on the machine head,

2) The preparation and the injection of O ₃ are carried out,

3) The NO is oxidized and,

4) SO ₂ and NO ₂ are removed,

5) and (4) bag dust removal.

2. The method for synchronously treating sulfur dioxide and nitrogen oxide in sintering flue gas by a low-temperature dry single tower as claimed in claim 1, wherein the step 1) comprises the following steps of (1) carrying out electric dust removal on a machine head, wherein the sintering flue gas contains a large amount of dust under the action of air draft, arranging an electric dust remover in front of an inlet of a main exhaust fan, enabling dust particles to be charged in the process of ionizing the dust-containing gas by a high-voltage electric field, enabling the charged dust particles to move to electrodes with opposite polarities under the action of the electric field force and to be deposited on the electrodes, separating the dust particles from the dust-containing gas, enabling the dust to fall into a collecting hopper at the lower part of the dust remover by a method of vibrating the electrodes, and enabling the dust concentration of the sintering flue gas to be reduced to below 50mg/m ³ after.

3. The method for synchronously treating sulfur dioxide and nitrogen oxides in sintering flue gas by using a low-temperature dry single tower as claimed in claim 2, wherein the step 2) of O ₃ preparation and injection is specifically that an ozone generator is used as a core device for O ₃ preparation, oxygen molecules are dissociated into oxygen atoms under the bombardment of high-speed electron flow when oxygen passes through a discharge electric field between high-voltage alternating current electrodes, the oxygen atoms rapidly react with the oxygen molecules to generate ozone molecules, the optimal injection point and injection position are determined by adopting CFD simulation design and flow field calculation, and a special injection grid with mixing and uniform distribution functions is adopted at a proper position of an inlet flue of an absorption tower to inject O ₃, so that the O ₃ and the sintering flue gas are rapidly and uniformly mixed.

4. The method for synchronously treating sulfur dioxide and nitrogen oxides in sintering flue gas by using the low-temperature dry single tower as claimed in claim 3, wherein NO is oxidized in the step 3), specifically, the temperature of the sintering flue gas is 80-150 ℃, the selective oxidation of NO by O ₃ is very strong through thermodynamic analysis and calculation, the free energy delta G of the reaction of NO + O ₃ → NO ₂ + O ₂ is less than 0, the concentration of O ₃ is controlled to be proper, namely the molar ratio of O ₃/NO is 0.50-0.95, O ₃ does not react with SO ₂ and CO in the flue gas, and only reacts with NO (accounting for more than 90% of the nitrogen oxides in the sintering flue gas) which is oxidized into main components of the nitrogen oxides in the sintering flue gas (NO + O ₃ → NO ₂ + O ₂), and NO is quickly oxidized into NO ₂, and the reaction can be completed within 0.05 seconds.

5. the method for synchronously treating the sulfur dioxide and the nitrogen oxides in the sintering flue gas by the low-temperature dry single tower according to claim 3 or 4, characterized in that the SO ₂ and the NO ₂ are removed in the step 4), specifically, the sintering flue gas enters a circulating fluidized bed body through acceleration of a venturi tube in an absorption tower, gas-solid two phases generate strong turbulence and mixing due to the action of air flow, the gas-solid two phases are fully contacted, floccules are continuously formed and return downwards in the rising process, the floccules are continuously decomposed and are continuously lifted by the air flow in the strong turbulence, the sliding speed between the gas-solid phases is as high as dozens of times of the sliding speed of single particles, the top structure of the absorption tower further strengthens the return of the floccules, the density of the particles in the tower is further improved, the Ca/S ratio in the bed is as high as higher than 50, the gas-solid two-phase flow mechanism in the circulating fluidized bed greatly strengthens mass transfer and heat transfer between the gas-solid phases, SO that the reaction of the Ca ₂, the NO ₂ and the Ca and the SO ₂ are converted into an ionic reaction which can be instantly completed, that Ca + 8672, the Ca + 8672 and SO 368672 are removed (Ca, the Ca + 366342, SO 368642, the Ca + 869, the SO 368672, the Ca + 368672, the SO 368672, the Ca + 368672 absorption reaction is carried out, the Ca + 368672 absorption tower 366342 is carried.

6. the method for synchronously treating sulfur dioxide and nitrogen oxides in sintering flue gas by a low-temperature dry single tower according to claim 5, characterized in that the step 5) is implemented by bag-type dust removal, specifically, the sintering flue gas after desulfurization and denitrification enters a bag-type dust remover from an absorption tower in an upward air inlet mode, because the cross-sectional area of the air flow is suddenly enlarged and the flow rate is reduced, a part of dust particles with coarse particles and high density in the air flow are settled down in an ash bucket under the action of gravity, the dust particles with fine particles and low density enter a bag filter chamber and are deposited on the surface of a filter bag through the comprehensive effects of inertial collision, screen filtration and the like on the surface of the filter bag, the dust is dropped into the ash bucket at the lower part of the dust remover in an uninterrupted rotation pulse dust removal mode, and the dust concentration of the sintering flue gas is reduced to below 5mg/m ³ after the.

Technical Field

The invention relates to a method, in particular to a method for synchronously treating sulfur dioxide and nitrogen oxide in sintering flue gas by using a low-temperature dry single tower, belonging to the technical field of ferrous metallurgy sintering environmental protection.

Background

The sintering process is one of important process units of iron and steel enterprises, provides high-quality sinter for blast furnace smelting, has obvious status and effect, but has NO environmental protection problem caused by the sintering process, has large sintering flue gas emission and high concentration of toxic and harmful substances, and statistically, the emission of SO ₂ and NO _X contained in the sintering flue gas respectively accounts for 40-60% and 50-55% of the emission of the iron and steel enterprises.

In order to enhance the environmental protection, the national emission standard of atmospheric pollutants for the steel sintering and pelletizing industry puts forward strict requirements on the emission concentration of sintering flue gas; and as the area with special emission limit of atmospheric pollutants, a higher standard is provided for the emission concentration of sintering flue gas. Therefore, the technical scheme of strengthening the sintering flue gas treatment and selecting the proper and reasonable integrated comprehensive treatment of desulfurization and denitrification of the sintering flue gas is not only a necessary condition for the survival and development of enterprises, but also responsibility and obligation for the enterprises to protect the environment and establish a harmonious society and urban steel plants.

In recent years, most of the sintering machines in China have completed flue gas desulfurization transformation, the adopted processes are mainly wet and semi-dry methods, the absorbent comprises ammonia water, limestone slurry, slaked lime, magnesium oxide slurry and the like, and an activated carbon adsorption process is selected by individual plants, so that the activated carbon adsorption process is stably operated at present and has good effect; but the sintering flue gas denitration technology is difficult, and no recognized denitration process with moderate investment, low operation cost and stable operation exists at present; the research of the sintering flue gas denitration technology mainly centers on the denitration technologies such as Selective Catalytic Reduction (SCR), selective non-catalytic reduction (SNCR), catalytic oxidation, activated carbon, plasma method and the like, but the denitration technologies except the activated carbon and the SCR technology are applied to individual domestic steel mills, and other technical popularization problems are encountered. Because these technologies have more or less passed on the coal fired power plant flue gas desulfurization denitration technique, do not conform to sintering flue gas characteristics, direct continuation has desulfurization, denitration inefficiency, and the running cost is high, the desulfurization denitration product causes secondary pollution scheduling problem to the environment. The main process technology is as follows:

The active carbon desulfurization and denitrification technology has the principle that after sintered flue gas is subjected to desulfurization (physical adsorption), a reducing agent NH ₃ is introduced into the flue gas, NO _X in the flue gas is reduced into harmless nitrogen (N ₂) and water (H ₂ O), and the advantages of short process, mature process, five-in-one (desulfurization, denitrification, dioxin removal, heavy metal removal and acid gas removal) synergistic purification function, realization of good resource recycling of byproducts (sulfuric acid can be produced as a byproduct of high-concentration SO ₂, and carbon powder can be used as sintering or blast furnace fuel), and disadvantages of low denitrification efficiency (30-40% of single-tower efficiency), high denitrification efficiency due to the configuration of double towers, increased system resistance, high investment and running cost, huge equipment and high manufacturing cost, high operation and management difficulty, prominent corrosion problem, complex peripheral system, low adsorption rate after the repeated use of active carbon, high consumption, high energy consumption due to the fact that the active carbon needs to be heated to 450 ℃, high regeneration and desorption and ammonia escape exist.

A technology for desulfurization and SCR denitration of a circulating fluidized bed is characterized in that after sintering flue gas is desulfurized (SO ₂ reacts with slaked lime to generate calcium sulfite), a reducing agent NH ₃ is introduced into the flue gas under the conditions of a certain temperature (200 ℃ and 400 ℃ and the need of heating the flue gas) and the existence of a catalyst, NO _X in the flue gas is reduced into harmless nitrogen (N ₂) and water (H ₂ O).

A wet desulfurization and ozone oxidation absorption denitration technology based on calcium agents and the like has the advantages that NO is oxidized into NO _{2 2} by O ₃ and reacts with limestone slurry in a tower to generate nitrous acid and calcium nitrite, SO ₂ reacts with the limestone slurry to generate calcium sulfite, the process is simple, the adaptability to the amount and components of flue gas is good, the structure in the tower is simple, the flue gas does not need to be reheated, the defects that the denitration efficiency is low, the nitrous acid and the calcium nitrite are dissolved in water and are easy to saturate, the problem of NO ₂ escape exists at a chimney outlet, and secondary pollution is caused to water and soil by a byproduct calcium nitrite solution.

Therefore, in order to overcome the defects of the existing sintering flue gas treatment technology, a new sintering flue gas desulfurization and denitration technical method needs to be developed, and the aims of high desulfurization and denitration efficiency, low investment, low operation cost, simple control, high reliability, good load adaptability and no secondary pollution of desulfurization and denitration products to the environment are fulfilled.

Disclosure of Invention

The invention provides a method for synchronously treating sulfur dioxide and nitrogen oxide in sintering flue gas by a low-temperature dry single tower, aiming at the technical problems in the prior art, and the technical scheme relates to a technical method for synchronously treating sulfur dioxide and nitrogen oxide in sintering flue gas by a dry method in a low-temperature condition, and mainly solves the problems that the prior sintering flue gas treatment technology can only realize single desulfurization or can realize step desulfurization and denitrification, but has the disadvantages of complex process, large device investment, low removal efficiency, high operation management difficulty, high operation cost, secondary pollution of desulfurization and denitrification products to the environment and the like.

In order to achieve the purpose, the technical scheme of the method is that on the basis of removing SO ₂ by adopting the current mature circulating fluidized bed desulfurization process (dry method), the flue gas does not need to be heated, a special spraying grid with mixing and uniform distribution functions is adopted at a proper position of an inlet flue of an absorption tower to spray O ₃, main components NO (accounting for more than 90 percent of the nitrogen oxide in the sintering flue gas) of the nitrogen oxide in the sintering flue gas are quickly oxidized into NO ₂, NO ₂ in the absorption tower reacts with slaked lime, calcium sulfite and the like, and NO ₂ is absorbed, cured and removed, and the quality of desulfurized gypsum is improved.

The technical scheme adopted by the invention is that a technical method for synchronously treating sulfur dioxide and nitrogen oxide in sintering flue gas by using a low-temperature dry single tower comprises the following steps: 1) electric dust removal of a machine head: under the action of air draft, the sintering flue gas contains a large amount of dust; an electric dust collector is arranged in front of an inlet of the main exhaust fan; the dust particles are charged in the process of ionizing the dust-containing gas by a high-voltage electric field, and

Under the action of electric field force, the charged dust particles are moved to the electrode with opposite polarity and deposited on the electrode, so that the dust particles are separated from the dust-containing gas, then the dust is dropped into the collecting hopper at the lower part of the dust remover by the method of rapping the electrode, and the dust concentration of the sintering flue gas is reduced to below 50mg/m ³ after the sintering flue gas is treated by the electric dust remover of the machine head.

2) O ₃ preparation and injection, wherein the core equipment of O ₃ is an ozone generator, oxygen molecules are dissociated into oxygen atoms under the bombardment of high-speed electron flow when oxygen passes through a discharge electric field between high-voltage alternating current electrodes, the oxygen atoms rapidly react with the oxygen molecules to generate ozone molecules, the optimal injection point and injection position are determined by adopting CFD simulation design and flow field calculation, and the O ₃ is injected at the proper position of an inlet flue of an absorption tower by adopting a special injection grid with mixing and uniform distribution functions, so that the O ₃ and sintering flue gas are rapidly and uniformly mixed.

3) The method is characterized in that NO is oxidized, the temperature of sintering flue gas is generally 80-150 ℃, NO is insoluble in water and can not be absorbed by water or alkaline substances at the temperature, meanwhile, the NO oxidation reaction is an exothermic reaction, the oxidation reaction is facilitated at the temperature, the oxidant capable of oxidizing NO mainly comprises ozone (O ₃), hydrogen peroxide (commonly called hydrogen peroxide H ₂ O ₂), potassium permanganate (KMnO ₄), chlorine dioxide (ClO ₂) and the like, the oxidation-reduction potential of the ozone is second only to fluorine and is higher than hydrogen peroxide, potassium permanganate and the like, the oxidation property of the ozone is strong, through thermodynamic analysis and calculation, O ₃ is very strong in NO selective oxidation (NO + O ₃ → NO ₂ + O ₂ reaction free energy delta G < 0), the appropriate O ₃ concentration (O ₃/NO molar ratio is 0.50-0.95) is controlled, the O ₃ does not react with SO ₂ and CO in the flue gas, and only reacts with NO (accounting for more than 90% of nitrogen oxides in the sintering flue gas) in the sintering flue gas (NO 82 ₃), and the reaction rate can be studied according to the maximum NO 369685 and NO reaction rate of NO 3605.

4) SO ₂ and NO ₂ are removed, sintering flue gas enters a circulating fluidized bed body through acceleration of a venturi tube in an absorption tower, gas-solid two phases generate violent turbulence and mixing due to the action of air flow, the gas-solid two phases are in full contact, floccules are continuously formed and return downwards in the rising process, the floccules are continuously disintegrated and are lifted again by the air flow in the violent turbulence, the sliding speed between the gas and the solid is as high as dozens of times of the sliding speed of single particles, the returning of the floccules is further enhanced by the top structure of the absorption tower, the bed density of particles in the tower is further increased, the Ca/S ratio in the bed is as high as more than 50, the mass transfer and heat transfer between the gas and the solid are greatly enhanced, the reaction of SO ₂, NO ₂ and the like with Ca (OH) ₂ is converted into ionic reaction which can be instantly completed, namely, Ca (OH) ₂ + SO ₂ → CaSO 9. 1/2H ₂ O +1/2H ₂ O, NO 3NO ₂ + H → O → Ca + ₃ and SO 72 are generated in the absorption tower, and SO ₃ are converted into SO ₃ and SO ₃ (SO) and SO ₃ and SO ₃ are simultaneously absorbed and desulfurized by Ca (₃) and ₃ and 3636363672).

5) the bag-type dust collector has the characteristics of high dust collection efficiency and insensitivity to dust characteristics, sintered flue gas subjected to desulfurization and denitrification enters the bag-type dust collector from an absorption tower (an upper air inlet mode is adopted), as the cross section area of airflow is suddenly enlarged and the flow rate is reduced, a part of dust particles with coarse particles and high density in the airflow are settled down in an ash bucket under the action of gravity, dust particles with fine particle size and low density enter a bag filter chamber, the dust is deposited on the surface of a filter bag through comprehensive effects of inertial collision, screen filtration and the like on the surface of the filter bag, the dust is descended into the ash bucket at the lower part of the dust collector in an uninterrupted rotary pulse dust removal mode, and the dust concentration of the sintered flue gas is reduced to be less than 5mg/m ³ after the sintered flue gas.

_{3 3 3 2 2 3 3 3 2 3 2 2 2 3 3 2 2 2 2 2 3 2 2 2 2 2 3 2 2 2 2 2 3 3 2 4 2 3 4 2}The technical scheme is that the method is obtained through a large number of experiments, the temperature of general sintering flue gas is generally 80-150 ℃, NO is insoluble in water and cannot be absorbed by water or alkaline substances at the temperature, therefore, NO in the sintering flue gas is removed, a chemical reaction type is not an oxidation method or a reduction method, the NO oxidation reaction is an exothermic reaction and is beneficial to the progress of the oxidation reaction under the temperature condition of the conventional sintering flue gas, the oxidation-reduction potential of O is second to fluorine and is higher than hydrogen peroxide, potassium permanganate and the like, the oxidation performance of O is strong, the selective oxidation of O to NO is very strong (NO + O → NO + O reaction free energy delta G < 0) based on thermodynamic analysis and calculation, the proper O concentration (O/NO molar ratio is 0.50-0.95), the O does not react with SO and CO in the flue gas, the main components NO (accounting for more than 90% of nitrogen oxides in the sintering flue gas) in the flue gas do not react with SO and CO, the main components NO (accounting for more than 90% of nitrogen oxides in the sintering flue gas in the nitrogen oxides) react (NO + O + NO → NO + O + NO + O + NO → NO + CO) in a fluidized bed reaction, the fluidized bed is rapidly absorbed by the CaO adsorption reaction, the CaO adsorption of CaO → NO is rapidly absorbed by CaO adsorption of CaO in the CaO adsorption column, the CaO adsorption of the fluidized bed, the CaO adsorption of Ca + SO, the fluidized bed is improved, the fluidized bed is improved, the Ca + SO, the fluidized bed is improved, the fluidized bed is realized by the Ca + SO and the fluidized bed, the fluidized bed is realized by the fluidized bed.

The method of the invention is based on the removal of SO ₂ by adopting the current mature circulating fluidized bed desulfurization process (dry method), flue gas does not need to be heated, a special injection grid with mixing and uniform distribution functions is adopted to inject O ₃ at a proper position of an inlet flue of an absorption tower, main component NO (more than 90% of nitrogen oxide in the sintering flue gas) of nitrogen oxide in the sintering flue gas is quickly oxidized into NO ₂, NO ₂ reacts with slaked lime, calcium sulfite and the like in the absorption tower, NO ₂ is absorbed, cured and removed, the quality of desulfurized gypsum is improved, and the problems that the existing sintering flue gas treatment technology can only realize single desulfurization or can realize step-by-step desulfurization and denitration, but the process is complex, the device investment is large, the removal efficiency is low, the operation management difficulty is large, the operation cost is high, and the desulfurization and denitration products cause secondary pollution to the environment are mainly solved.

Compared with the prior art, the invention has the following positive effects:

1. The technical scheme has high desulfurization and denitration efficiency, the synchronous removal rate of a single tower respectively reaches more than 98 percent and 70 percent, the concentrations of sulfur dioxide and nitrogen oxide in the outlet flue gas are respectively reduced to below 35mg/m ³ and 100mg/m ³, and the ultra-clean discharge capacity is realized.

2. The technical scheme is a low-temperature dry method, flue gas is not required to be heated, desorption and absorption reaction can be completed at the conventional temperature of 80-150 ℃ of sintering flue gas, the problems that a wet absorption method calcium nitrite solution pollutes water bodies and soil and the like do not exist, and meanwhile, the problem that NO ₂ escapes from a chimney outlet through professional detection does not exist.

3. The technical scheme has the advantages of simple related system, simple process, small occupied area, low investment and low operation cost; the operation control is simple, the reliability is high, and the load adaptability is good; the system does not add extra adsorbent, and can synchronously realize the removal of partial dioxin and heavy metal; provides a better demonstration effect for the comprehensive treatment of sintering flue gas in the industry.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

for the purposes of promoting an understanding and appreciation of the invention, reference will now be made to the following detailed description of the invention taken in conjunction with the accompanying drawings.