Wet-type purification treatment method and device for flue gas of domestic garbage incineration power plant

[0042] Example 1:

[0043] Such as figure 1 As shown, the wet purification treatment device for flue gas of a household waste incineration power plant of this embodiment includes an ammonia water quench device, a powder activated carbon spray device, a bag filter, a wet deacidification tower, and a mist removal device. The ammonia water quench device, spray The powder activated carbon device and the bag filter are connected by a ventilation pipe. The gas inlet end of the ammonia water quench device can be connected to the flue gas outlet of the household waste incineration power plant. The ventilation pipe between the ammonia water quench device and the powder activated carbon spray device is also connected Compressed air system. The ash hopper of the bag filter is equipped with a compressed air system. The ash hopper is connected to the fly ash storage through a pipe. The outlet flue of the bag filter is connected to the washing and concentration section of the wet deacidification tower through the pipe. The wet deacidification tower includes an absorption section, a washing and concentration section, and an oxidation section. The absorption section of the wet deacidification tower is provided with a nozzle capable of spraying ammonia water, and the flue gas discharge pipe is connected with the electric mist removal equipment, and the wet deacidification tower The oxidation section of the acid tower is connected with an oxidation fan, and the ammonium chloride and ammonium sulfate outlets of the oxidation section of the wet deacidification tower are connected with the crystallization equipment.

[0044] The specific treatment method is as follows:

[0045] A. Ammonia quenching section: After the domestic waste is burned in the incinerator, high-temperature flue gas is generated. The flue gas temperature at the outlet of the furnace is kept above 850℃ for more than 2 seconds, and reaches the evaporator (water-cooled heating surface), superheater, and coal saving After the heat exchange of the equipment, the temperature is gradually reduced to 200~220℃, and then the flue gas is passed into the ammonia water quenching device, and the ammonia water is sprayed in the ammonia water quenching device, and the flue gas is quenched to 170±5℃ to reach the activated carbon and PTFE ( The temperature at which the bag filter made of polytetrafluoroethylene and polyester needled felt can operate for a long time. The ammonia water quenching device can firstly avoid the re-synthesis of dioxins from part of the organic matter at low temperature, and secondly reduce the flue gas temperature to achieve the purpose of denitration and part of acid removal. The spray gun for spraying ammonia is the key equipment for quenching. The spray gun form is either a mechanical atomized ammonia spray gun or compressed air atomization; no matter the flue is round or rectangular; no matter the spray angle and direction, those skilled in the art can choose according to the actual situation.

[0046] B. Activated carbon section: After quenching, the flue gas is pneumatically transported (compressed air system) to the powder activated carbon spray device, and the powder activated carbon spray device is sprayed with activated carbon to make the powder activated carbon and the dust in the flue gas flow fully in the process Evenly mixed, the activated carbon adsorbs dioxins and some heavy metals in the flue gas, and the adsorption efficiency is high. Maintaining an appropriate amount of activated carbon can fully meet the EU II emission standard and China's latest 2016 emission standard. Because the ammonia water quenching device sprays less water and is fully mixed with the flue gas, the activated carbon absorbs less water and its ability to adsorb dioxins is stronger, far exceeding the traditional semi-dry flue gas spraying process water and lime slurry This results in a working condition with high moisture content in the flue gas. The amount of activated carbon is less than the traditional amount, which can save operating costs.

[0047] C. Bag dust collector section: The gas after the flue gas and powdered activated carbon are fully mixed is passed into the box of the bag dust collector made of PTFE and polyester needle felt, and filtered by the bag dust collector. The material is divided into two ways. One way is for solid dust to stay on the outer surface of the bag. After a certain amount of dust is deposited on the surface of the bag, the pressure difference between the inside and the outside becomes larger. When it reaches a certain level, compressed air is blown back on the top of the bag, which will stay on the outer surface of the bag. The dust is blown away, gravity settles and falls into the ash hopper of the bag filter for collection; the other way of flue gas passes through the inner surface of the bag, enters the clean air chamber and enters the outlet flue of the bag filter. The flue gas is discharged from the outlet flue of the bag filter and enters the wet deacidification tower through the flue.

[0048] The fly ash collected by the ash hopper is transported to the fly ash storage by a pneumatic conveying device (compressed air system) arranged under the ash hopper, and then subjected to heavy metal solidification and stabilization treatment, and landfill treatment after qualified. The compressed air that is pneumatically conveyed is provided by the compressed air system, which needs to remove oil and water.

[0049] D. The acidic flue gas after dust removal is discharged through the outlet flue of the bag filter, and then enters the middle washing and concentration section of the wet deacidification tower. After the flue gas is washed with 10-12% dilute ammonia water, the temperature drops to 60℃~70℃, and then enters the absorption section of the upper part of the wet deacidification tower. There is a nozzle that can spray ammonia in the absorption section. The nozzle is made of acid-resistant steel with no less than 2205 or a better Hastelloy material, which is fully atomized to ensure uniform chemical reaction. Ammonia and flue gas are sprayed through the nozzle. It is fully contacted with ammonia and reacts to remove most of hydrogen chloride (HCI) and sulfide (SOX). Finally, it is defogged by demister equipment to become purified tail gas and discharged through the chimney.

[0050] The absorbent ammonia water is sent to the wet deacidification tower by the ammonia water pump and sprayed by the nozzle. The hydrogen chloride (HCI) in the flue gas reacts with ammonia (NH3+H2O) to form ammonium chloride; the sulfur dioxide (SO2) in the flue gas reacts with the ammonia water, Forms ammonium bisulfite. At this stage, more than 98% of hydrogen chloride and more than 95% of sulfur dioxide are captured by the absorbent, and acid gas is removed. As part of the NOX gas is absorbed by ammonia, the absorption rate is 20%-25%.

[0051] The oxidation and sulfur fixation process of ammonium bisulfite: Ammonium bisulfite is oxidized into ammonium sulfate solution by the air blown by the oxidation fan in the oxidation section at the bottom of the wet deacidification tower. The mixed solution of ammonium sulfate and ammonium chloride is pumped into the scrubbing and concentration section of the wet deacidification tower to cool the flue gas while evaporating its own moisture to form a mixed slurry of ammonium sulfate and ammonium chloride with a higher solid content.