CN104028087B - A kind of method and device thereof removing dioxin in high-temperature flue gas - Google Patents

Abstract

The method for removing dioxins in high-temperature flue gas disclosed by the present invention first uses waste heat and quenched flue gas to remove fly ash through the first dust removal equipment; then passes it into a dioxin absorption tower containing an absorbent for absorption and separation Dioxins in the flue gas; and then passed into the second dust removal equipment to remove the absorbent dust in the flue gas, the purified flue gas is discharged, and the absorbent dust recovered by the second dust removal equipment and the dioxin absorption tower are saturated The adsorbed absorbent is sent to the absorbent recovery reactor, and input ozone to react and decompose dioxin, and the purified absorbent is sent to the dioxin absorption tower for recycling. The device for implementing the above method includes two dust removal equipment, a dioxin absorption tower containing an absorbent, an absorbent recovery reactor and an ozone generator. The invention combines the advantages of absorbent absorbing dioxins and ozone promoting catalytic decomposition of dioxins, and can remove dioxins in high-temperature flue gas efficiently and cheaply.

Description

A method and device for removing dioxins from high-temperature flue gas

technical field

The invention relates to a treatment method and device for high-temperature flue gas, in particular to a method and a device for removing dioxins in high-temperature flue gas.

Background technique

Dioxins are a class of tricyclic aromatic organic compounds composed of 2 or 1 oxygen atom connected to 2 chlorine-substituted benzene rings, including polychlorinated dibenzodioxins and polychlorinated dibenzofurans, with a total of 210 isomers/congeners. Dioxins are a class of very stable lipophilic solid compounds with a high melting point and a decomposition temperature above 700°C. They are extremely difficult to dissolve in water but soluble in most organic solvents. Microbial degradation, hydrolysis and photolysis in nature have little effect on the molecular structure of dioxins, making them difficult to degrade naturally. Some isomers in dioxin are highly toxic substances, and their acute toxicity is equivalent to 1000 times that of potassium cyanide. A large number of animal experiments have shown that very low concentrations of dioxins have lethal effects on animals. Dioxins also cause skin acne, headache, deafness, depression, insomnia, etc., and may cause chromosomal damage, heart failure, cancer, etc. Its greatest danger is its irreversible teratogenic, carcinogenic and mutagenic toxicity. In addition, dioxin also affects reproductive function and interferes with the endocrine system, so it is called "the poison of the century". As highly persistent pollutants, dioxins have a strong affinity for soil and sediment, and are easy to accumulate in biological tissues, and eventually accumulate in a large amount in the human body through the food chain, and accumulate in a relatively stable form. Once the concentration of dioxin in the human body (especially women and children) reaches a certain value, its own reproductive toxicity, immunotoxicity and endocrine toxicity will cause skin diseases, internal organ diseases, cancer and deformed children, affecting human survival And development.

Dioxins are mainly produced unintentionally in various high-temperature processes. For example, flue gases from waste incineration, metal smelting, and cremators often contain relatively high concentrations of dioxins. In view of the toxicity of dioxins, all countries have made strict restrictions on the discharge of dioxins. In China, the dioxin discharge standard for industrial waste incinerators is less than 1.0ngI-TEQ/Nm ³ , and for medical waste incinerators is less than 0.5ngI-TEQ/Nm ³ . Since 2008, Beijing's dioxin emission standard has been fully raised to 0.1ngI-TEQ/Nm ³ . Dioxin emission standards in developed countries are usually lower than 0.1ngI-TEQ/Nm ³ . Soon, the dioxin emission standard of domestic waste incinerators in China will be lower than 0.1ngI-TEQ/Nm ³ . The establishment of more stringent emission standards and the rapid increase in the public's attention to environmental protection have posed severe challenges to high-temperature facilities such as waste incineration facilities in operation and soon to be built. How to control the emission of dioxins cheaply and effectively has become an urgent problem to be solved.

The emission control of dioxins in the high temperature process, on the basis of the well-known control of incineration temperature, turbulence and flue gas residence time, can also inhibit the formation of dioxins, absorb and separate dioxins, and dioxins through inhibitors The decomposition eliminates three pathways, further reducing the emission of dioxins.

The first approach is to add inhibitors that inhibit dioxin formation during high temperature processes. For example, CN101725989A discloses a method of using sulfur, high-sulfur coal, calcium oxide, calcium hydroxide or calcium carbonate as inhibitors to suppress the formation of dioxins during waste incineration. CN101485955 discloses a method for putting pyrite and rubbish into an incinerator, and controlling the amount of pyrite added to suppress the generation of dioxins in the rubbish incineration process. CN201419076 discloses a method for reducing dioxin emissions by controlling the sulfur content in coal.

The second way is to use activated carbon absorption to separate dioxins from flue gas. CN201537442U discloses a device for absorbing dioxins in the flue gas by injecting activated carbon and calcium oxide into the flue gas and strongly contacting the flue gas in a Venturi reactor. CN201949799U discloses a device that adopts double cloth bags to control dioxins. Lime is sprayed into the first cloth bag through a Venturi reactor, and activated carbon is sprayed into the second cloth bag. Increase the contact between activated carbon and flue gas to achieve the purpose of effectively absorbing dioxins, and the activated carbon can be reused until the adsorption of dioxins is saturated, which reduces the operating cost of the system. CN1246597 discloses a method for eliminating dioxin emissions by injecting activated carbon into the flue gas, separating the activated carbon adsorbed with dioxin, and sending it to a combustion chamber for combustion treatment. CN201997249U discloses the method of spraying alkaline cooling liquid into flue gas to reduce the emission of dioxins.

The third way is decomposition, usually under the action of a catalyst, allowing dioxins to oxidize and decompose at a lower temperature. For example, CN1626277 discloses a catalyst based on V ₂ O ₅ (WO ₃ , MoO ₃ ) and TiO ₂ , which can effectively remove dioxins in flue gas at a temperature of 240-320°C. CN101559362 discloses that TiO ₂ is loaded on volcanic rock first, and then V ₂ O ₅ is loaded, which can effectively remove dioxin at a temperature of 200-450°C. The catalyst for removing dioxins disclosed in European Patent (Patent No.: 634206) also supports vanadium oxide on TiO ₂ . The catalyst active components disclosed in US Patent (Patent No.: 5227356) are transition metal oxides and noble metals. The catalyst active components disclosed in Japanese Patent (Patent No.: 200024460 Heping-11047592) include V, W, Cu, Mn, Cr, Pd, Ru, Pt and other metal oxides and noble metals. The catalyst carrier can be TiO ₂ , SiO ₂ , Al ₂ O ₃ , ZrO ₂ . The catalyst disclosed in Japanese Patent (Patent No. Hei-11226397) is oxides of transition metals such as V, W, Mo, Cu, Mn, Fe, Co, Cr, Ni, etc. supported on activated carbon. Catalytic active components and polytetrafluoroethylene fibers can also be prepared into catalytically active filter bags, such as CN101580973, CN101255615 and US Patent (Patent No.: 5620669). In addition, CN201921634U discloses the use of ultraviolet light emitting devices to activate photocatalyst coatings to achieve the purpose of catalytically decomposing dioxins. CN101485958 discloses a photocatalytic reactor for degrading dioxins in flue gas and a photocatalyst activation method. It has recently been found that ozone can effectively promote the catalytic decomposition of dioxins. For example, CN102814108A discloses that ozone can effectively promote the low-temperature decomposition of dioxins on metal oxide catalysts.

However, the above patents all have some obvious disadvantages, for example, the addition of inhibitors usually causes other pollution. Simply using activated carbon to absorb dioxin technology is not only expensive, but also the activated carbon after absorbing dioxin must be treated as hazardous waste, or directly incinerated as fuel, and the operating cost is high. Using catalytic filter bag technology, because the pressure drop is too large, the flow rate of flue gas is slow, and there is a problem of catalyst loss, which also increases the operating cost. The catalytic decomposition technology also faces problems such as huge scale of facilities, catalyst poisoning and the need for regular replacement, flue gas needs to be reheated, and so on. Even if ozone is used to promote the catalytic decomposition of dioxins, it still faces problems such as large-scale facilities, large-scale use of ozone, and regular replacement of catalysts.

Contents of the invention

The purpose of the present invention is to provide an efficient and cheap method and device for removing dioxins in high-temperature flue gas.

The method for removing dioxins in high-temperature flue gas of the present invention is characterized in that the flue gas after waste heat utilization and rapid cooling is first passed into the first dust removal equipment to remove fly ash in the flue gas; The ash flue gas is passed into the dioxin absorption tower containing absorbent to absorb and separate the dioxin in the flue gas; then the flue gas after the removal of dioxin is passed into the second dust removal equipment to remove the absorbent in the flue gas Dust, the flue gas purified by the second dust removal equipment is discharged from the flue, the absorbent dust recovered by the second dust removal equipment is sent to the absorbent recovery reactor, and the dioxin absorption tower containing the absorbent is saturated with dioxins The adsorbed absorbent is also sent to the absorbent recovery reactor, and ozone is input into the absorbent recovery reactor to react and decompose dioxin at 25°C~350°C, and the absorbent purified by the absorbent recovery reactor is sent to the dioxin British absorption tower, recycling.

In the present invention, the absorbent can be activated carbon, carbon nanotubes, activated carbon modified by metal oxides or carbon nanotubes modified by metal oxides, wherein the metal oxides account for 0 to 50% of the total mass of the absorbent. %, the metal oxide is one or more of the oxides of manganese, cerium, copper, vanadium, iron, molybdenum, tungsten, chromium or nickel.

The device for implementing the above method for removing dioxins from high-temperature flue gas includes the first dust removal equipment, the dioxin absorption tower containing absorbent, the second dust removal equipment, the absorbent recovery reactor and the ozone generator, and the first dust removal equipment The flue gas outlet of the absorbent is connected to the flue gas inlet of the dioxin absorption tower containing absorbent, the flue gas outlet of the dioxin absorption tower containing absorbent is connected to the flue gas inlet of the second dust removal equipment, and the flue gas inlet of the second dust removal equipment The gas outlet is connected to the chimney, the outlet of the dioxin absorption tower containing absorbent is connected to the inlet of the absorbent recovery reactor, and the outlet of the second dust collector is connected to the inlet of the absorbent recovery reactor , the discharge port of the absorbent recovery reactor is connected with the feed port of the absorbent-containing dioxin absorption tower, and the absorbent recovery reactor is connected with the ozone generator.

The above-mentioned first dust removal equipment may be a bag filter, an electric dust collector, a cyclone dust collector or a combination thereof. The second dust removal equipment may also be a bag filter, an electric dust collector, a cyclone dust collector or a combination thereof.

In the present invention, the absorbent-containing dioxin absorption tower can be a fixed-bed absorption tower, a fluidized-bed absorption tower or a fluidized-bed absorption tower.

The advantage of the present invention is that it combines the advantages of absorbent absorbing dioxin and ozone promoting catalytic decomposition of dioxin. Not only can the absorbent be recycled, but also the catalytic decomposition temperature of dioxin is low, the scale of the facility is small, and the operating cost is low. And when ozone is used to catalyze the decomposition of dioxins, it will not be affected by other components in the flue gas, thereby achieving the effect of efficiently and cheaply removing dioxins in high-temperature flue gas. The facility and method for removing dioxins in high-temperature flue gas with high efficiency and low cost provided by the present invention can be applied to dioxins in high-temperature flue gas including waste incineration, iron and steel smelting, cement kiln, cremator, etc. And efficient removal of other volatile organic compounds.

Description of drawings

Figure 1 is a schematic diagram of a device for removing dioxins from high-temperature flue gas.

In the figure: 1. First dedusting equipment, 2. Dioxin absorption tower containing absorbent, 3. Second dedusting equipment, 4. Absorbent recovery reactor, 5. Ozone generator.

detailed description

Further illustrate the present invention below in conjunction with accompanying drawing

Referring to Fig. 1, the device of the method for removing dioxins in high-temperature flue gas of the present invention comprises the first dedusting equipment 1, the dioxin absorption tower 2 containing absorbent, the second dedusting equipment 3, absorbent recovery reactor 4 and Ozone generator 5, the flue gas outlet of the first dedusting equipment 1 is connected with the flue gas inlet of the dioxin absorption tower 2 containing the absorbent, and the flue gas outlet of the dioxin absorption tower 2 containing the absorbent is connected with the second dedusting equipment 3 is connected to the flue gas inlet, the flue gas outlet of the second dedusting device 3 is connected to the chimney, the discharge port of the dioxin absorption tower 2 containing absorbent is connected to the feed port of the absorbent recovery reactor 4, and the second dedusting device 3 is connected to the chimney. The discharge port of the absorber is connected with the feed port of the absorbent recovery reactor 4, and the discharge port of the absorbent recovery reactor 4 is connected with the feed port of the dioxin absorption tower 2 containing the absorbent, and the absorbent recovery reactor 4 links to each other with ozone generator 5. Both the first dust removal equipment 1 and the second dust removal equipment 3 here can be bag filter, electric dust collector, cyclone dust collector or a combination thereof. The activated carbon-containing dioxin absorption tower 2 can be a fixed-bed absorption tower, a fluidized-bed absorption tower or a fluidized-bed absorption tower.

When working, the flue gas after waste heat utilization and quenching is first passed into the first dedusting equipment, and the fly ash and other particles in the flue gas are filtered and removed in the first dedusting equipment; then enters the dioxin absorption tower containing absorbent, so that The absorbent is in full contact with the flue gas, effectively absorbing and separating dioxins in the flue gas. Use the second dedusting equipment to filter and capture the dioxin-containing absorbent dust escaping from the dioxin absorption tower, and the purified flue gas that meets the national emission standard is discharged from the flue. The absorbent dust collected from the second dedusting plant is sent to the absorbent recovery reactor. The absorbent that has adsorbed dioxin in the dioxin absorption tower and reaches adsorption saturation is also sent to the absorbent recovery reactor. The ozone generated by the ozone generator is input into the absorbent recovery reactor and reacted at 25°C~350°C, and the dioxin adsorbed on the absorbent is completely decomposed by using the super oxidation ability of ozone and the catalytic activity of the absorbent. The treated absorbent is sent to the dioxin absorption tower for recycling.

Claims (5)

1. remove a method for dioxin in high-temperature flue gas, it is characterized in that first the flue gas after UTILIZATION OF VESIDUAL HEAT IN and chilling being passed into the first cleaner, the flying dust in removing flue gas; Then, the flue gas eliminating flying dust is passed into the dioxins adsorption tower containing absorbent, the dioxin in absorption and separation flue gas; Again by remove the flue gas after dioxin pass into second cleaner removing flue gas in absorbent dust, flue gas after the second cleaner purification is from air flue emission, the absorbent dust that second cleaner reclaims is sent into absorbent and is reclaimed reactor, reactor is reclaimed by also sending into absorbent containing the absorbent reaching dioxin saturated adsorption in the dioxins adsorption tower of absorbent, reactor input ozone is reclaimed to absorbent, reaction decomposes dioxin at 25 DEG C ~ 350 DEG C, the absorbent reclaiming reactor purification through absorbent is sent into dioxins adsorption tower, recycles; Above-mentioned absorbent is active carbon, CNT, the active carbon through metal oxide modified or the CNT through metal oxide modified, wherein metal oxide accounts for 0 ~ 50% of absorbent gross mass, and described metal oxide is one or more in the oxide of manganese, cerium, copper, vanadium, iron, molybdenum, tungsten, chromium or nickel.

2. implement the claims the device removing dioxin method in high-temperature flue gas described in 1, it is characterized in that comprising the first cleaner (1), containing the dioxins adsorption tower (2) of absorbent, second cleaner (3), absorbent reclaims reactor (4) and ozone generator (5), the exhanst gas outlet of the first cleaner (1) is connected with the gas approach of the dioxins adsorption tower (2) containing absorbent, exhanst gas outlet containing the dioxins adsorption tower (2) of absorbent is connected with the gas approach of the second cleaner (3), the exhanst gas outlet of the second cleaner (3) is connected with chimney, discharging opening containing the dioxins adsorption tower (2) of absorbent is connected with the charging aperture that absorbent reclaims reactor (4), the charging aperture that discharging opening and the absorbent of the second deduster reclaim reactor (4) is connected, the discharging opening that absorbent reclaims reactor (4) is connected with the charging aperture of the dioxins adsorption tower (2) containing absorbent, absorbent reclaims reactor (4) and is connected with ozone generator (5).

3. the device removing dioxin method in high-temperature flue gas according to claim 2, is characterized in that described the first cleaner (1) is sack cleaner, electric cleaner, cyclone dust collectors or their combination.

4. the device removing dioxin method in high-temperature flue gas according to claim 2, is characterized in that described the second cleaner (3) is sack cleaner, electric cleaner, cyclone dust collectors or their combination.

5. the device removing dioxin method in high-temperature flue gas according to claim 2, is characterized in that the described dioxins adsorption tower (2) containing absorbent is fixed bed absorption tower, fluid bed absorption tower or thermopnore absorption tower.