CN1137759C - Method and device for comprehensive purification of waste incineration tail gas - Google Patents

Abstract

The present invention discloses a method and a device for comprehensively purifying tail gas produced in refuse incineration. After accelerated by an expansion jet-pipe, tail gas produced in refuse incineration is sprayed into a circulating fluid bed purifier taking calcium-based eliminating agents and adsorbing agents as the bed material, and the bed material is driven together for fluidization; gas, solution and solid are intensively mixed, and both heat transfer and mass transfer are sufficiently carried out, so that acid gas and ultra-fine particles, such as heavy metal, dioxin, etc., in the tail gas are neutrally reacted in the process of mass transfer and absorbed by the absorbing agents. As compared with the prior art, the present invention has the advantages of simple processing steps, easy realization, obvious purifying effect, compact device structure, small occupation area, and low investment and running cost.

Description

Method and device for comprehensive purification of waste incineration tail gas

The invention relates to the technical field of combustion furnace tail gas purification and dust removal, in particular to a method and device for dry desulfurization and dechlorination of waste incineration tail gas and adsorption and removal of fine particles, heavy metals, dioxins, etc.

Air pollution has always been the focus of environmental protection work in many countries in the world, and more than 200 flue gas desulfurization technologies have been developed successively by various countries. However, there are only a dozen kinds that can be applied industrially. For the tail gas produced by waste incineration, in addition to conventional coal-fired flue gas pollutants such as nitrogen oxides, sulfur oxides, fine particles and heavy metals, it also contains a larger amount of harmful substances such as elemental chlorine, hydrogen chloride, and dioxins. Desulfurization and dust removal technology cannot meet the strict purification requirements of waste incineration tail gas. Most of the existing foreign waste incineration tail gas purification technologies use wet methods. For example, US Patent No. 4,789,532 uses conventional lime spray slurry to absorb acid gases in the tail gas, such as sulfur dioxide, hydrogen chloride, and elemental chlorine, and then connects a bag filter after the reactor to remove dust. . Although the above method can remove acid gas and fly ash in the tail gas, it has the problems of high equipment investment and operating costs, large floor area, and inability to effectively remove heavy metals and dioxin fine particles produced by waste incineration.

In view of the above-mentioned problems in the prior art, the object of the present invention is to provide a method and device for comprehensive purification of waste incineration tail gas. Using the method, the process steps are simple, and not only the effect of purifying acid gas and fly ash in the tail gas is remarkable, but more prominently, it can effectively remove heavy metals and dioxin fine particles produced by garbage incineration. The device for implementing the method has a compact structure, a small occupied area, and low investment and operation costs.

In order to achieve the above-mentioned purpose of the invention, the technical solution of the present invention is realized in the following manner: a method for comprehensive purification of waste incineration tail gas, the steps of which are: ① spray the flue gas discharged from the combustion equipment into a calcium-based The removal agent and adsorbent are bed materials in the fluidized bed purifier and drive the bed materials to fluidize together; ② During the co-fluidization process of tail gas and bed materials, strong mixing of gas, liquid and solid and sufficient heat transfer and Mass transfer, so that the acid gases in the tail gas, such as sulfur dioxide, sulfur trioxide, hydrogen chloride, elemental chlorine and nitrogen oxides, etc., react with the calcium-based remover bed material, and make the heavy metals and dioxins in the tail gas ultra-fine The particles are adsorbed by the adsorbent in the bed material during the mass transfer process; ③The material formed after the reaction and adsorption remains in the remover in solid form and enters the gas-solid separator together with the incompletely reacted bed material along with the flue gas; ④After After the gas-solid separator, the solid particles enter the buffer bin, and more than 90% of the solid particles enter the mixing granulator and are mixed with fresh lime powder, activated carbon and a small amount of water for granulation, and the excess materials in the buffer bin are discharged. The purified flue gas is discharged up to the standard through the induced draft fan from the chimney; ⑤The mixed and granulated particles enter the fluidized bed purifier for recycling.

The device for realizing the comprehensive purification method of waste incineration tail gas for the purpose of the above invention, which includes a fluidized bed purifier with calcium-based removal agent and adsorbent as bed material, high-efficiency cyclone dust collector, electrostatic precipitator, bag filter or their organic Combined gas-solid separator, buffer bin with feeding and discharging device and mixing granulator. Its structural features are: the inlet end of the fluidized bed purifier is provided with a scaling nozzle and a bed material inlet that can accelerate the tail gas. The other end of the scaling nozzle is connected to the waste incineration tail gas inlet. The bed material inlet is connected with the outlet of the mixing granulator. The mixing granulator is equipped with multiple ingredient inlets and is connected with the feeder. The other end of the feeder is connected with the buffer bin. A gas-solid separator and a discharge machine are installed above and beside the buffer bin. There are purified gas outlets and horizontal connecting pipes on the top and side of the gas-solid separator. The other end of the horizontal connecting pipe is connected with the outlet end of the fluidized bed purifier.

According to the above-mentioned technical scheme, the multiple batching inlets of the mixing granulator are water inlets, activated carbon feeding inlets and lime powder feeding inlets; the shape of the scaling nozzle is a hyperbolic circle with a thin middle and thick ends. Tube.

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

(1) Based on the traditional dry circulating fluidized bed flue gas purification technology, according to the characteristics and purification requirements of waste incineration tail gas pollutants, through the organic combination of circulating fluidized bed purifier, gas-solid separator and mixing granulator Integrated, using calcium-based remover to remove acid gas in tail gas, and adding adsorbents such as fly ash and activated carbon to effectively remove heavy metals and dioxins. Not only is the process simple, the equipment structure is compact, saving investment and floor space, but also the exhaust gas purification effect is good, which fully meets the environmental protection requirements and achieves waste incineration exhaust emission standards.

(2) Use a mixing granulator for granulation, which can timely adjust the addition of fresh materials, addition speed, granulation size and other parameters according to the exhaust gas temperature, pollutant concentration and airflow velocity, forming rich active adsorption sites and pores Structured particles are beneficial to ensure the best state of system operation and the best purification efficiency, while improving the utilization rate of additives and reducing their operating costs.

(3) During the process of removing pollutants, the bed material remains relatively dry, which effectively avoids the problems of pipeline corrosion and blockage in the wet purification system.

(4) Due to the use of dry circulating fluidized bed tail gas purification technology, the system requires very little water, and the product is in a dry state, which reduces water consumption, avoids the water pollution problem in the wet process, and reduces the processing cost of the product .

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Accompanying drawing is the method step of the present invention and its device connection schematic diagram.

Referring to the accompanying drawings, the waste incineration exhaust gas coming out from the combustion equipment enters the fluidized bed purifier 2 after being accelerated by the zoom nozzle 1 through the thin hyperbolic circular pipe in the middle and thick at both ends by the exhaust gas inlet 13. The exhaust gas drives the bed material composed of calcium-based remover, fly ash and activated carbon adsorbent to fluidize together in the fluidized bed purifier 2. The fluidization speed is as high as 5-10 m/s, and the heat and mass transfer are fully carried out at the same time. . During this process, acid gases such as sulfur dioxide, sulfur trioxide, hydrogen chloride, elemental chlorine and nitrogen oxides in the tail gas undergo neutralization reactions with calcium-based basic compounds to form solid calcium salts. At the same time, ultrafine particles such as heavy metals and dioxins in the tail gas are adsorbed and removed by the adsorbent fly ash and activated carbon during the process of fully mixing with the bed material. The reacted and adsorbed solid particles enter the gas-solid separator 4 through the horizontal transition pipe 3 with the airflow, and a dust collector is used in the gas-solid separator 4. The dust collector can be a bag filter, a cyclone dust collector, an electrostatic precipitator or a Their organic combination achieves efficient separation of gas and solid particles, with a dust removal rate as high as 99.9%, and further removes acid gases, dioxins and heavy metals in the flue gas. The desulfurization efficiency of the invention can reach more than 95%, the dechlorination efficiency is greater than 97%, and the removal rates of heavy metals and dioxins are both greater than 90%. The purified gas is discharged to the chimney from the purified gas outlet 14 through the induced draft fan. The solid particles removed by the gas-solid separator 4 , the completely reacted remover particles and the incompletely reacted remover particles enter the buffer bin 5 . More than 90% of the solid materials in the buffer bin 5 enter the mixing granulator 8 through the feeder 7, and the rest of the non-circulating materials are discharged from the ash bin by the discharger 6 for further processing. The circulating material entering the mixing granulator 8 is fully mixed with the lime powder from the lime powder feed port 9, the activated carbon from the activated carbon feed port 10, and the water from the water feed port 11. The particle size range is 200-300um, and the maximum 500um. The granulated mixed material is used as the bed material of the circulating fluidized bed purifier 2, and enters the fluidized bed purifier 2 through the mixing granulator 8 through the bed material inlet 12 for recycling.

Claims (8)

1, a kind of method of comprehensive garbage incinerating tail gas purifying the steps include: 1) tail gas that combustion apparatus is discharged sprays into after quickening through de Laval noz(zle) to remove in the fluid bed clarifier that agent and adsorbent are the bed material and drive bed with the calcium base and expects fluidisation together; 2) in a tail gas and the process of material, take place to conduct heat and mass transfer strong mixing of gas, liquid, solid with sufficient in fluidisation, make sour gas such as sulfur dioxide, tri-chlorination sulphur, hydrogen chloride, simple substance chlorine and nitrogen oxide etc. in the tail gas remove agent bed material generation neutralization reaction with the calcium base, and make in the tail gas ultra-fine grain such as heavy metal and dioxin in mass transport process by adsorbents adsorb in the bed material; 3) material that forms with absorption back of reaction stay remove in the agent with solid form and not the bed of complete reaction expect to send into gas-solid separator with flue gas; 4) behind gas-solid separator, solid particle enters in the surge bunker, make solid particle more than 90% enter the mixing granulation device and with fresh pulverized limestone, active carbon and mixes with small amount of water granulation, object unnecessary in the surge bunker is discharged, the clean flue gas after the purification by air-introduced machine by the chimney qualified discharge; 5) particle behind the mixing granulation enters in the fluid bed clarifier again and recycles.

2, according to the method for the described comprehensive garbage incinerating tail gas purifying of claim 1, it is 5-10m/S with bed materials flow speed designs in the fluid bed clarifier that its feature is appointed in: the flue gas that described combustion apparatus is discharged.

3, according to the method for the described comprehensive garbage incinerating tail gas purifying of claim 2, it is characterized in that: described adsorbent is a porous mass, comprises flying dust, active carbon and coke.

4, according to the method for the described comprehensive garbage incinerating tail gas purifying of claim 3, it is characterized in that: described mixing granulation diameter range is 200um-500um.

5, a kind of device of realizing claim 1 or 4 described comprehensive garbage incinerating tail gas purifyings, it comprises with the calcium base and removes the sulfuration bed clarifier (2) that agent and adsorbent are the bed material, gas-solid separator (4), surge bunker (5) and mixing granulation device (8), the arrival end of described fluid bed clarifier (2) is provided with de Laval noz(zle) (1) and the bed material inlet (12) that tail gas is quickened, de Laval noz(zle) (1) other end and garbage incinerating tail gas inlet (13) join, it is characterized in that: bed material inlet (12) joins with the outlet of mixing granulation device (8), mixing granulation device (8) is equipped with a plurality of batching inlets and joins with batcher (7), batcher (7) other end and surge bunker (5) join, surge bunker (5) top and side top are equipped with gas-solid separator (4) and discharge machine (6), gas-solid separator (4) top and side top are equipped with clean gas outlet (14) and horizontal connection tube (3), and the outlet of horizontal connection tube (3) other end and fluid bed clarifier (2) is joined.

6, to come the 5 described devices that are used for comprehensive garbage incinerating tail gas purifying according to right, it is characterized in that: be provided with deduster between described horizontal connection tube (3) and gas-solid separator (4) junction, this deduster can be sack cleaner, cyclone dust collectors, electrostatic precipitator or their organic assembling body; Described clean gas outlet is provided with air-introduced machine in (14).

7, according to the described device that is used for comprehensive garbage incinerating tail gas purifying of claim 6, it is characterized in that: a plurality of batching inlets of described mixing granulation device (8) are admission port (11), active carbon material inlet (10) and pulverized limestone material inlet (9).

8, according to the described device that is used for comprehensive garbage incinerating tail gas purifying of claim 7, it is characterized in that: thin, the thick hyperbola pipe in two ends in the middle of the shape of described de Laval noz(zle) (1) is.

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