CN113559693A - Apparatus and method for removing pollutants from flue gas flowing through flue - Google Patents

Apparatus and method for removing pollutants from flue gas flowing through flue Download PDF

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Publication number
CN113559693A
CN113559693A CN202010359453.9A CN202010359453A CN113559693A CN 113559693 A CN113559693 A CN 113559693A CN 202010359453 A CN202010359453 A CN 202010359453A CN 113559693 A CN113559693 A CN 113559693A
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China
Prior art keywords
flue
flue gas
spraying
dry
particulate matter
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Inventor
夏刚
吴其荣
黎方潜
袁亮
陈建宏
王刚
王进
周川雄
聂华
喻江涛
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Spic Yuanda Environmental Protection Engineering Co ltd Chongqing Science And Technology Branch
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Spic Yuanda Environmental Protection Engineering Co ltd Chongqing Science And Technology Branch
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Priority to CN202010359453.9A priority Critical patent/CN113559693A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/77—Liquid phase processes
    • B01D53/78—Liquid phase processes with gas-liquid contact
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/26—Drying gases or vapours
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/48—Sulfur compounds
    • B01D53/50—Sulfur oxides
    • B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
    • B01D53/502—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound characterised by a specific solution or suspension
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/48—Sulfur compounds
    • B01D53/50—Sulfur oxides
    • B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
    • B01D53/504—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound characterised by a specific device
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G7/00—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals
    • F23G7/06—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Treating Waste Gases (AREA)

Abstract

The invention provides a device for removing pollutants in flue gas flowing through a flue, which comprises: a spray device in the flue, the spray device configured to spray an alkaline aqueous solution and an oxidant to the flue gas, respectively; a flue gas drying section downstream of the spray device in the flue, the length of the flue gas drying section configured to be sufficient to dry the liquid phase in the flue; and the solid particulate matter dry separation and recovery device is arranged at the downstream of the flue gas drying section in the flue, and is configured to dry separate and recover the solid particulate matter in the flue gas. The invention also provides a related method. The equipment and the method have the advantages of low cost, no waste water generation, recyclable absorbent and the like.

Description

Apparatus and method for removing pollutants from flue gas flowing through flue
Technical Field
The invention relates to the field of flue gas pollutant treatment, in particular to a device and a method for removing pollutants in flue gas flowing through a flue.
Background
At present, the key industry in the aspect of treating the smoke pollution in China is the thermal power industry based on coal burning, so the technology for removing the smoke pollutants is mainly developed aiming at the characteristics of the smoke of a coal burning power plant. The coal-fired flue gas emission has the characteristics of large flue gas amount, high sulfur content, wide load fluctuation and the like, so that a treatment technology with higher design margin is required.
However, in order to deal with the possible risks and to comply with the development of the era, the fume treatment emphasis in China has gradually expanded to the non-electric industry.
The main pollutants in flue gases include sulfur dioxide (SO)2) Nitrogen Oxide (NO)X) And dust. Heretofore, in order to simultaneously remove SO from flue gas2And NOXWet absorption, adsorption, high-energy radiation, and the like have been proposed. 95% NO in flue gasXIt exists in the form of NO with very low solubility, and has great difficulty in dissolving in the wet absorption process. Depending on the way of treating NO, an oxidation absorption method, a complex absorption method, and a reduction absorption method have been proposed.
The oxidation absorption method is that the smoke firstly passes through a strong oxidizing environment to oxidize NO in the smoke into water-soluble nitrite or nitrate, and then the smoke is absorbed by alkali liquor. The proposed oxidizing agents includeHClO3、NaClO2、H2O2Etc., the absorption alkali liquor is usually Na2S solution or NaOH solution. For example, using HClO3And NaClO2Simultaneously remove SO in the flue gas2And NOXGenerally, an oxidation absorption tower and an alkali absorption tower are adopted, wherein the oxidation absorption tower adopts an oxidant HClO3And NaClO2The basic absorption tower adopts Na2S or NaOH is used as an absorbent. For another example, it has also been proposed to inject hydrogen peroxide into the flue gas stream to oxidize NO to nitrous or nitric acid and then remove the nitrous or nitric acid with a downstream wet scrubber.
These two-stage wet oxidation absorption methods are complicated in equipment, require at least two absorption apparatuses, and the absorption by the second absorption apparatus produces waste water (waste liquid). In order to treat the waste water, further subsequent equipment and processes are required. The above characteristics result in a high cost of the two-stage wet oxidation absorption method.
Development and improvement are still needed for comprehensive treatment of smoke pollutants.
Disclosure of Invention
In one aspect, the present invention provides an apparatus for removing contaminants from flue gas flowing through a flue, said contaminants comprising one or more of sulphur dioxide, nitrogen oxides and dust, characterised in that the apparatus comprises:
a spray device in the flue, the spray device configured to spray an alkaline aqueous solution and an oxidant to the flue gas, respectively;
a flue gas drying section in the flue downstream of the spray device, the flue gas drying section having a length configured to be sufficient to dry a liquid phase in the flue; and
and the dry-method solid particle separation and recovery device is arranged at the downstream of the flue gas drying section in the flue and is used for dry-method separation and recovery of the solid particles in the flue gas.
Preferably, a solid particulate matter blowing device in the flue, the solid particulate matter blowing device being between the spraying device and the solid particulate matter dry separation and recovery device.
Preferably, the solid particulate matter conveying line is configured to convey the solid particulate matter recovered by the solid particulate matter dry separation and recovery device to the solid particulate matter blowing device.
Preferably, the spray means comprises an atomising nozzle.
Preferably, the spraying devices are 1-6 stages of spraying devices arranged along the flue.
Preferably, the spraying coverage of the spraying device is 200% -360%.
Preferably, the flue is a horizontal flue.
Preferably, the apparatus further comprises a flue temperature measuring device.
Preferably, the dry separation and recovery device for solid particles is a bag-type dust remover.
In another aspect, the present invention provides a method of removing contaminants from flue gas flowing through a flue, the contaminants comprising one or more of sulphur dioxide, nitrogen oxides and dust, the method comprising:
respectively spraying an alkaline aqueous solution and an oxidant to the flue gas by using a spraying device in the flue;
drying the liquid phase in the flue in a flue gas drying section at the downstream of the spraying device by using the heat of the flue gas; and
and the solid particles in the flue gas are separated and recovered by a dry method by utilizing a dry method separation and recovery device for the solid particles at the downstream of the flue gas drying section.
Preferably, the temperature in the flue is measured and the spraying is controlled in dependence on the temperature.
Preferably, between the spraying device and the dry separation and recovery device for solid particles, the recovered solid particles are blown back into the flue.
Drawings
Fig. 1 shows a schematic structural diagram of the apparatus of the present invention.
Fig. 2 shows a schematic diagram of the working principle of the device of the invention.
Figure 3 shows a schematic diagram of a particular embodiment of the apparatus of the present invention.
Figure 4 shows a schematic view of yet another embodiment of the apparatus of the present invention.
Detailed Description
In non-electric industries such as steel, aluminum industry, glass and the like, smoke with low sulfur content and stable smoke quantity is generated in some production sections. The inventor of the invention finds that if the flue gas is treated by using the treatment means for the thermal power coal-fired flue gas, the energy consumption is high, the investment is large, and the waste is caused. Especially in the case of low pollutant concentrations in the flue gas, the relative effectiveness of conventional two-stage wet oxidation absorption equipment is lower.
The invention provides an apparatus for removing pollutants from flue gas flowing through a flue, the pollutants comprising one or more of sulfur dioxide, nitrogen oxides and dust, the apparatus comprising:
a spray device in the flue configured to spray a respective alkaline aqueous solution and an oxidant onto the flue gas;
a flue gas drying section in the flue downstream of the spray device, the flue gas drying section having a length configured to be sufficient to dry a liquid phase in the flue; and
and the dry-method solid particle separation and recovery device is arranged at the downstream of the flue gas drying section in the flue and is used for dry-method separation and recovery of the solid particles in the flue gas.
The equipment of the invention is used for removing pollutants in flue gas flowing through a flue. The pollutants may contain sulfur dioxide, nitrogen oxides or dust, especially both or three of them. In other words, the invention provides a desulfurization, denitrification and dust removal device, or a flue gas multi-pollutant integrated synergic removal device. In addition, flue gas contaminants may also include acid gases such as HF, HCl, etc., which may also be removed by the apparatus of the present invention.
The apparatus of the present invention is disposed directly in the flue. Different from the conventional equipment for purifying the flue gas by adopting one or more independent absorption towers, the equipment provided by the invention can directly finish the processes of desulfurization, denitrification and dust removal in the flue without arranging an independent absorption tower or a spray tower. This in itself saves considerable equipment investment and can be easily implemented by retrofitting existing flues without additional construction of, for example, absorption towers.
The equipment comprises a spraying device, a flue gas drying section and a solid particulate matter dry separation and recovery device.
The spraying device is directly arranged in the flue, and respectively sprays alkaline aqueous solution and oxidant to the flue gas flowing through the flue. The spray device of the present invention is not provided in a separate absorption tower.
The spraying device sprays alkaline aqueous solution and oxidant to the flue gas flowing through the flue. This can be performed by providing the alkaline aqueous solution injection means and the oxidizing agent injection means in the shower device. The alkaline aqueous solution injection means and the oxidizer injection means may be appropriately disposed in the flue. In one embodiment, the two kinds of injection means are alternately arranged from the upstream direction to the downstream direction, for example, the first oxidizing agent injection means, the first alkaline aqueous solution injection means, the second oxidizing agent injection means, the second alkaline aqueous solution injection means, the third oxidizing agent injection means, and the third alkaline aqueous solution injection means are arranged in this order. Wherein the spray member may be an array of atomising nozzles. In this way, the flue gas is repeatedly passed through multiple layers of spray liquid, thereby obtaining sufficient purification. Other arrangements can also be adopted as long as the alkaline aqueous solution and the oxidant can be respectively sprayed to the flue gas. For example, the oxidizer and the aqueous alkaline solution may be sprayed into the same flue space simultaneously.
The spraying direction of the spraying means can be appropriately selected. When the amount of dust in the flue gas is small, the spraying can be carried out in the direction basically facing the flow of the flue gas, and the gas-liquid mixing effect is enhanced by forming turbulence. When the dust amount in the flue gas is larger, the spraying can be carried out along the flowing direction of the flue gas basically, so that the blockage of a nozzle is avoided. Spraying can also be carried out along the cross section direction of the flue. The present invention is not particularly limited to a specific spraying direction.
The spraying device of the invention is used for spraying the alkaline aqueous solution and the oxidant to the flue gas and enabling the alkaline aqueous solution and the oxidant to be contacted and mixed with the flue gas as uniformly as possible. Preferably, the spraying may be performed using an atomizing nozzle. The atomizing nozzle can cause the sprayed liquid to be in the form of micro-droplets, thereby sufficiently increasing the gas-liquid contact area to facilitate absorption, while later facilitating drying and solid particulate formation as described below. A plurality of nozzles can be arranged in one flue cross section. The plurality of nozzles may be independently controlled. Furthermore, nozzles can be arranged in a plurality of flue cross sections, i.e. a multi-stage or multi-layer spray.
Preferably, the spraying means are 1-6 stages of spraying means arranged along the flue, each stage comprising suitably arranged alkaline aqueous solution injection means and/or oxidant injection means, and there is no overlap between the injection zones between the stages. The multistage spraying can make liquid drops fully contact with flue gas so as to carry out desulfurization and denitrification. However, excessive numbers of stages will lead to increased equipment and operating costs, and the effectiveness of improved contaminant removal will gradually saturate. When multi-stage spraying is adopted, the multi-stage spraying can be simultaneously implemented according to specific working conditions, or only part of stages participate in the spraying, namely, each stage can be independently controlled.
Preferably, the spray coverage of the spray device is 200% -360%. Spray coverage is a measure of the number of times flue gas is sprayed by the nozzles in the direction of the flue. For example, when the spray coverage is 200%, it means that the flue gas is sprayed by two nozzles on average after passing through the spraying device of the multi-stage nozzles. When the spray coverage is low, insufficient absorption may result; too high a spray coverage will lead to increased equipment and operating costs, while the effectiveness of improved pollutant removal will gradually saturate.
Obviously, the spray device should be resistant to alkaline aqueous solutions and oxidizing agents.
The spraying device of the invention sprays alkaline aqueous solution and oxidant respectively. The oxidant refers to an oxidant that can oxidize nitrogen oxide contaminants to nitrogen dioxide and is in liquid form. It may be in the form of a non-solution or an aqueous solution. Examples of oxidizing agents include perchloric acid, hydrogen peroxide, hypochlorous acid, potassium permanganate, sodium hypochlorite, and the like. The alkaline aqueous solution refers to an alkaline aqueous solution, and can be an alkaline solution or a solution of strong base and weak acid salt. On one hand, the alkaline aqueous solution plays a role in absorbing sulfur dioxide in the flue gas, and on the other hand, nitric acid generated by the reaction of nitrogen dioxide generated after nitrogen oxide is oxidized and water can react with the alkaline aqueous solution to generate corresponding nitrate. The device of the invention respectively sprays alkaline aqueous solution and oxidant as sulfur dioxide absorbent and nitrogen oxide oxidant, so that sulfur dioxide and nitrogen oxide in the flue gas are respectively treated in a harmless way. Furthermore, since the aqueous alkaline solution is also sprayed in the flue, it will also function as an absorbent for the oxidation products of nitrogen oxides. Thus, the simultaneous desulfurization and denitrification in the flue are realized, and a separate absorption tower is not needed to be arranged at the downstream. The invention is particularly suitable for the non-electric industry flue gas treatment with low sulfur content and stable flue gas amount.
Examples of the alkaline aqueous solution include an aqueous sodium hydroxide solution, an aqueous sodium bicarbonate solution, and an aqueous sodium carbonate solution. Examples of oxidizing agents include perchloric acid, hydrogen peroxide, hypochlorous acid, potassium permanganate, sodium hypochlorite.
The ratio of the sprayed alkaline aqueous solution and the oxidizing agent can be appropriately selected. Combinations of multiple aqueous alkaline solutions and/or combinations of multiple oxidizing agents may also be used. An exemplary combination of an aqueous alkaline solution and an oxidizing agent may be, for example: sodium hydroxide + hydrogen peroxide, sodium hydroxide + sodium bicarbonate + potassium permanganate, sodium carbonate + hypochlorous acid + chloric acid, and the like. The proportion of the combination can be prepared according to the specific conditions of the flue gas and the flue. For example, there may be 3 parts of sodium hydroxide +7 parts of hydrogen peroxide, 1 part of sodium hydroxide +2 parts of sodium bicarbonate +7 parts of potassium permanganate, 4 parts of sodium carbonate +2 parts of hypochlorous acid +4 parts of chloric acid, and the like.
The apparatus of the present invention further comprises a flue gas drying section in the flue downstream of the spraying means, the length of the flue gas drying section being configured to be sufficient to dry the liquid phase in the flue.
The flue gas drying section is a section of flue duct of sufficient length downstream of the spraying device. The device of the invention utilizes the length of the flue to fully carry out the desulfurization and denitrification processes, and simultaneously utilizes the temperature of the flue gas in the flue to fully gasify the liquid (mainly moisture) in the injected alkaline aqueous solution and the oxidant in the length of the flue. After passing through the flue gas drying section, there is no longer a liquid phase in the flue, i.e. only substantially dry solids and a gas phase. It should be understood that the drying of the liquid phase as described in the present invention means that no significant amount of the liquid phase is present in the flue gas section, so that gas and solids can be separated by the solids separation device.
Thus, after the liquid drops absorbing the oxidation products of sulfur dioxide and nitrogen oxides pass through the flue gas drying section along with the flue gas, the liquid water in the liquid drops is essentially completely gasified or volatilized, so that the liquid drops become the drying products of the liquid drops. The droplet dry product is typically a salt. For example, when an aqueous sodium hydroxide solution is sprayed with hydrogen peroxide, sulfur dioxide absorbed by the sodium hydroxide may form sodium sulfate, sodium sulfite, and nitrogen oxides absorbed by the sodium hydroxide may form nitrogen dioxide, react with water to form nitric acid, and then may form sodium nitrate with the sodium hydroxide. In addition, the droplets may also contain unreacted sodium hydroxide. After the water was evaporated and the liquid phase was dried, the resulting dried products, sodium hydroxide, sodium sulfate, sodium sulfite, sodium nitrate were in the form of solid particles.
The equipment of the invention is provided with a solid particle dry separation and recovery device at the downstream of the flue gas drying section. The dry separation and recovery device for the solid particles is configured to separate and recover the solid particles in the flue gas by a dry method, and on one hand, the dry product of the liquid drops in the form of the solid particles can be separated and recovered, and on the other hand, the inherent dust in the flue gas can also be separated.
The equipment of the invention comprehensively absorbs and solidifies sulfur dioxide and nitrogen oxide in the flue gas in the flue through the spraying device, the flue gas drying section and the solid particulate dry separation and recovery device, thereby removing the sulfur dioxide and the nitrogen oxide together with dust. The equipment investment is low, particularly no waste water/waste liquid is generated, and the environmental protection property is high.
The apparatus of the present invention may further include a solid particulate matter blowing device in the flue, the solid particulate matter blowing device being between the spraying device and the solid particulate matter dry separation and recovery device. The solid particulate matter blowing device may be used to blow the recovered solid particulate matter into the flue and into contact with the flue gas. As described above, in the solid particulates recovered by the solid particulates dry separation and recovery apparatus, there may be a considerable amount of unreacted alkaline substance, such as sodium hydroxide, or unreacted oxidizing agent, such as sodium hypochlorite. The inventors have found that such recovered solid particles can also be reused for removing pollutants from flue gases. The equipment of the invention is provided with a solid particle blowing device in the flue, so that the recovered solid particles are contacted with the sprayed flue gas at the downstream of the spraying device. In a water-containing environment, alkaline substances or oxidizing agents in the particles can participate in removing pollutants in the smoke again, so that materials are saved, and the cost is reduced. Moreover, the solid particles can help to adsorb liquid drops, avoid liquid sedimentation and improve drying efficiency.
The blowing means may be a solids injection tube and the blowing driving force may be provided by a fan. When the spraying device is in a multi-stage form, the spraying device and the solid particulate dry separation and recovery device are arranged between the spraying device and the first stage spraying device.
In one embodiment, a solid particulate matter conveying line configured to convey the solid particulate matter recovered by the solid particulate matter dry separation and recovery device to the solid particulate matter blowing device may be provided. The solid particulate matter conveying pipeline may be a pipeline system connecting the solid particulate matter dry separation and recovery device and the solid particulate matter blowing device, and may include a buffer tank, a storage tank, and the like. Compared with a semi-open mode or a batch mode such as a material transporting vehicle for transporting solid particles, the pipeline mode can reduce dust pollution, and can continuously transport the solid particles, so that the transport efficiency is improved.
The transfer line also has a purge port to discharge solid particulates that are not recycled.
Preferably, the flue is a horizontal flue. The device is arranged in the horizontal flue, and is beneficial to the downstream movement and the full drying of liquid drops in the flue gas drying section. If the flue is too low upstream and too high downstream, the dried solid particles may not be moved downstream. If the flue is too high upstream and too low downstream, the droplets will move too fast in the flue, and a longer flue gas drying section will be required. The horizontal flues of the present disclosure are meant to be substantially horizontal, e.g., within ± 15 °, within ± 10 °, or within ± 5 ° of the horizontal. Of course, it is also possible to arrange the apparatus of the invention in, for example, a vertical flue.
Preferably, the apparatus further comprises a flue temperature measuring device. A flue temperature measurement device is configured to measure a temperature in the flue. The flue temperature measuring device may be arranged at the spraying device or upstream or downstream thereof. For example, the flue temperature measuring device may be arranged in the flue gas drying section. Can monitor the temperature in the flue through flue temperature measuring device, and then control spray set's spray capacity, atomizing particle diameter isoparametric to realize abundant absorption and abundant drying afterwards.
Preferably, the dry separation and recovery device for solid particles is a bag-type dust remover. The bag-type dust collector has simple structure and good separation effect, and can directly collect solid particles.
The invention also provides a method for removing pollutants in flue gas flowing through a flue, which comprises the following steps:
respectively spraying an alkaline aqueous solution and an oxidant to the flue gas by using a spraying device in the flue;
drying the liquid phase in the flue in a flue gas drying section at the downstream of the spraying device by using the heat of the flue gas; and
and the solid particles in the flue gas are separated and recovered by a dry method by utilizing a dry method separation and recovery device for the solid particles at the downstream of the flue gas drying section.
As mentioned above, the method of the invention can directly complete the desulfurization, denitrification and dust removal process in the flue without a separate absorption tower or spray tower. This saves considerable equipment investment. The method of the invention comprehensively absorbs and solidifies sulfur dioxide and nitrogen oxide in the flue gas in the flue, thereby removing the sulfur dioxide and the nitrogen oxide together with dust. The equipment investment is low, particularly no waste water/waste liquid is generated, and the environmental protection property is high.
Preferably, the method of the present invention further comprises: and measuring the temperature in the flue, and controlling spraying according to the temperature. The control may be implemented by means of, for example, a PLC. A plurality of temperature measurement points may be provided in the flue to obtain the temperature distribution within the flue which is then fed back to the spray system to control the atomized particle size and spray volume of the absorbent solution at each nozzle. When the temperature is high, larger atomization particle size and spraying amount can be implemented; at low temperatures, smaller particle sizes and spray levels should be used. Preferably, the atomized particle size may be 100 μm to 2000 μm. The particle size range is suitable for liquid phase to fully contact and absorb gas phase, is beneficial to fully gasifying moisture and subsequently drying, and cannot excessively atomize.
Preferably, between the spraying device and the dry separation and recovery device for solid particles, the recovered solid particles are blown back into the flue. As mentioned above, there are absorbents in the solid particles that do not react with the contaminants and these absorbents can be recycled. Thus, the separated and recovered solid particulates can be recycled to the flue.
The invention is described below with reference to the accompanying drawings.
Fig. 1 shows a schematic structural diagram of the apparatus of the present invention. The equipment comprises a spraying device arranged in a flue, a flue gas drying section and a solid particulate matter dry separation and recovery device.
Fig. 2 shows a schematic diagram of the working principle of the device of the invention. In fig. 2, the arrow to the right indicates the high temperature flue gas flow. n1 and n2 denote nozzles of a spray device, and may be, for example, an oxidizer spray part n1 and an aqueous alkaline solution spray part n2, respectively, and may spray oxidizer droplets d1 and aqueous alkaline solution droplets d2 into the flue. After contacting with the flue gas, the liquid drops react with sulfur dioxide and nitrogen oxides in the flue gas, are absorbed and move downstream along with the high-temperature flue gas, and moisture in the liquid phase is continuously gasified and dried, so that the liquid drops become solid particles s. After all the liquid drops are dried into solid particles, the solid particles are separated and removed from the flue by a dry separation and recovery device such as a filter, and meanwhile, the original dust p of the flue gas is also separated. The flue gas after passing through the dry separation and recovery device is clean flue gas.
Figure 3 shows a schematic diagram of a particular embodiment of the apparatus of the present invention. Labeled as: atomizing nozzles (13, 14), centrifugal pumps (1, 2), an oxidant tank (10), an alkaline aqueous solution tank (11), a flue inlet (5), a flue outlet (6), a temperature sensor (7) and a dust remover (8).
In fig. 3, there are atomizing nozzles 13 and 14, a temperature sensor 5 and a dust separator 8 in the flue between the flue inlet 5 and the flue outlet 6. The atomizing nozzles 13 and 14 both belong to a spraying system. The atomizing nozzle 13 is an oxidizer nozzle, and the centrifugal pump 2 pumps the oxidizer from the oxidizer tank 10 to the oxidizer nozzle 13 and ejects it. The oxidizing agent may be, for example, an aqueous sodium hypochlorite solution, a hydrogen peroxide liquid, or the like. The atomizing nozzle 11 is an alkaline aqueous solution nozzle, and the centrifugal pump 1 pumps the alkaline aqueous solution from the alkaline aqueous solution tank 11 to the alkaline aqueous solution nozzle 14 and ejects it. The aqueous alkaline solution may be, for example, an aqueous sodium hydroxide solution.
It should be noted that fig. 3 is only a schematic diagram, and parameters such as the number of spraying layers, the spraying coverage rate, the atomized particle size of the absorbent and the like in an actual spraying system can be dynamically adjusted according to the smoke condition. The temperature sensor 7 is arranged between the flue inlet 5 and the flue outlet 6, 3-6 sensors are arranged at one temperature measuring point along the extending direction of the flue, and the temperature output data is the average value of the sensors at each measuring point. The dust separator 8 is arranged downstream of the spraying system, upstream of the flue gas outlet 6, and the area between it and the atomizing nozzles 14 is the flue gas drying section. The untreated flue gas passes through the flue inlet 5 and sprays droplets of an oxidizing agent and an aqueous alkaline solution through the atomizing nozzles 13 and 14 of the spraying system, the alkaline substances in the droplets and SO in the flue gas2The acid gas such as HCl, HF, etc. reacts, the oxidant reacts with NOx, and the oxidation product also reacts with the alkaline substance, and after the acid gas such as sulfur dioxide, etc. and NOx are all removed by reaction after being mixed in the flue for a sufficient time. According to accurate temperature measuring point measurement in the flue, temperature distribution in the flue is obtained and then fed back to the spraying system, so that the atomized particle size and the spraying amount of the absorbent solution are controlled, and pollutants in the flue gas are prevented from being sprayedShould be complete and the absorbent solution can be dried before reaching the dust separator. The dried solid particles are intercepted and recovered by a dust remover 8. The dust collector may be a bag-type dust collector. The device has simple integral process flow and lower investment and operation cost, and is suitable for low-sulfur flue gas purification treatment in various fields.
Figure 4 shows a schematic diagram of another embodiment of the apparatus of the present invention. Labeled as: atomizing nozzles (13, 14), centrifugal pumps (1, 2), an oxidant tank (10), an alkaline aqueous solution tank (11), a buffer tank (4), a storage tank (3), a fan (15), a solid injection pipe (12), a flue inlet (5), a flue outlet (6), a temperature sensor (7), a dust remover (8) and an ejector (9).
In contrast to the embodiment of fig. 3, the solid particulates recovered in the embodiment of fig. 4 may be transported back to the buffer tank 4 by the ejector 9 and subsequently to the storage tank 3. By means of the drive of the fan 15, the solid particles are fed to the solid injection pipe 12 and blown into the flue downstream of the spraying device. In this way, the alkaline substance or the oxidizing agent in the recovered solid particulates can be recycled.
The effects of the present invention will be further described below by way of examples.
Example 1:
the equipment and the method of the invention are adopted to treat the electrolytic aluminum flue gas. The pollutant content in the smoke to be treated is 220mg/m3SO of (A)2、120mg/m3NOx, the flue gas inlet area is 28m2The flow rate of the horizontal flue with the circular cross section is 800000m3H, temperature 120 ℃.
4 stages of atomizing nozzles are arranged at the downstream of the flue inlet, 6 atomizing nozzles are arranged at each stage, and the coverage rate is 250%.
The alkaline aqueous solution of sodium hydroxide with the concentration of 30 percent is sprayed in the first stage spraying system and the second stage spraying system, and the hypochlorous acid oxidant with the concentration of 20 percent is sprayed in the third stage spraying system and the fourth stage spraying system. Temperature sensors are arranged at the inlet and the tail of the flue, and 3 temperature sensors are arranged at each position in the cross section. When the measured temperatures were 110 ℃ and 80 ℃ respectively, the atomized particle size and the amount of spray were adjusted to 100 μm and 21t/h by calculation using a designed water-spray evaporation model software.
The length of the smoke drying section is 40 m. And a bag-type dust collector is arranged behind the flue gas drying section.
Measuring the smoke discharged from the downstream of the bag-type dust collector, wherein the pollutant content is reduced to 25mg/m3SO of (A)2、40mg/m3The NOx, indicating that the apparatus of the present invention can sufficiently remove sulfur dioxide and nitrogen oxides.
The solid particles collected in the bag-type dust remover are blown into the flue through the fan and can react with sulfur dioxide and nitrogen oxide again after contacting with the liquid drops.
And flexibly controlling the introduction amount of the solid particles according to the measured value of the pollutants in the downstream flue gas. Under the condition that the measured value of pollutants in the downstream flue gas is kept safe, the spraying amount in the spraying device is properly reduced, and the reutilization rate of solid particles is kept high. When the measured value of the pollutants in the downstream flue gas enters a safety warning area (for example, 90%, 85%, 80% and the like which meet the emission standard value), the spraying amount in the spraying device is increased again, the reutilization rate of the solid particles is reduced, and therefore the proportion of the fresh absorbent is increased. When the active ingredients in the solid particles tend to be exhausted, they can no longer be blown back into the flue again. And the specific parameters are fed back according to the measurement result to carry out logic control.
After the continuous operation for 48 hours in the mode, the content of the discharged pollutants does not obviously rise, which indicates that the recovered absorbent is fully utilized.
Example 2:
the equipment and the method of the invention are adopted to treat the electrolytic aluminum flue gas. The pollutant content in the smoke to be treated is 220mg/m35O of (2)2、120mg/m3NOx, the flue gas inlet area is 28m2The flow rate of the horizontal flue with the circular cross section is 800000m3H, temperature 120 ℃.
5 stages of atomizing nozzles are arranged at the downstream of the flue inlet, 5 atomizing nozzles are arranged at each stage, and the coverage rate is 220%.
And (3) spraying a 30% concentration sodium hydroxide and sodium bicarbonate mixed alkaline aqueous solution into the first-stage spraying system, the second-stage spraying system and the third-stage spraying system, and spraying a 30% concentration potassium permanganate and hydrogen peroxide mixed oxidant into the fourth-stage spraying system and the fifth-stage spraying system. Temperature sensors are arranged at the inlet and the tail of the flue, and 3 temperature sensors are arranged at each position in the cross section. When the measured temperatures were 115 ℃ and 70 ℃ respectively, the atomized particle size and the amount of spray were adjusted to 120 μm and 32t/h by calculation using a designed water-jet evaporation model software.
The length of the flue gas drying section is 45 m. And a bag-type dust collector is arranged behind the flue gas drying section.
Measuring the smoke discharged from the downstream of the bag-type dust collector, wherein the pollutant content is reduced to 20mg/m3SO of (A)2、25mg/m3The NOx, indicating that the apparatus of the present invention can sufficiently remove sulfur dioxide and nitrogen oxides.
And blowing the solid particles collected in the bag-type dust collector, wherein unreacted alkaline substances and oxidants exist in the solid into the flue through a fan, and reacting with sulfur dioxide and nitrogen oxides again after contacting with water.
And flexibly controlling the introduction amount of the solid particles according to the measured value of the pollutants in the downstream flue gas. Under the condition that the measured value of pollutants in the downstream flue gas is kept safe, the spraying amount in the spraying device is properly reduced, and the reutilization rate of solid particles is kept high. When the measured value of the pollutants in the downstream flue gas enters a safety warning area (for example, 90%, 85%, 80% and the like which meet the emission standard value), the spraying amount in the spraying device is increased again, the reutilization rate of the solid particles is reduced, and therefore the proportion of the fresh absorbent is increased. When the active ingredients in the solid particles tend to be exhausted, they can no longer be blown back into the flue again. And the specific parameters are fed back according to the measurement result to carry out logic control.
After the continuous operation for 48 hours in the mode, the content of the discharged pollutants does not obviously rise, which indicates that the recovered absorbent is fully utilized.
The equipment and the method can realize low-sulfur flue gas, realize the aims of high-efficiency desulfurization, denitration and dust removal in the flue, and have the advantages of low investment, easy modification, small system pressure loss and stable operation. Through arranging multistage, high coverage's spraying system and using mixed absorption liquid at the flue, can realize the high-efficient desorption of pollutant in the low sulphur flue gas, utilize the long characteristics of flue simultaneously, increased gas-liquid contact time to desulfurization, denitration efficiency have effectively been improved. The spraying amount of the spraying system and the atomizing particle size of the atomizing nozzle can be accurately adjusted in real time through multi-temperature point control, so that the absorbent solution in the flue is completely evaporated, no waste water is generated, and the influence on subsequent equipment is effectively reduced. The absorbent intercepted by the dust remover can be recycled, and the operation cost is saved.
It will be apparent to those skilled in the art that various changes and modifications may be made in the embodiments of the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims (12)

1. An apparatus for removing contaminants from flue gas flowing through a flue, said contaminants comprising one or more of sulfur dioxide, nitrogen oxides and dust, said apparatus comprising:
a spray device in the flue, the spray device configured to spray an alkaline aqueous solution and an oxidant to the flue gas, respectively;
a flue gas drying section in the flue downstream of the spray device, the flue gas drying section having a length configured to be sufficient to dry a liquid phase in the flue; and
and the dry-method solid particle separation and recovery device is arranged at the downstream of the flue gas drying section in the flue and is used for dry-method separation and recovery of the solid particles in the flue gas.
2. The apparatus of claim 1, further comprising:
a solid particulate matter blowing device in the flue, the solid particulate matter blowing device being between the spraying device and the solid particulate matter dry separation and recovery device.
3. The apparatus of claim 2, further comprising:
a solid particulate matter conveying line configured to convey the solid particulate matter recovered by the solid particulate matter dry separation and recovery device to the solid particulate matter blowing device.
4. The apparatus of claim 1,
the spraying device comprises an atomizing nozzle.
5. The apparatus of claim 1,
the spraying device is a 1-6 level spraying device arranged along the flue.
6. The apparatus of claim 1,
the spraying coverage rate of the spraying device is 200-360%.
7. The apparatus of claim 1,
the flue is a horizontal flue.
8. The apparatus of claim 1,
the equipment also comprises a flue temperature measuring device.
9. The apparatus of claim 1,
the dry separation and recovery device for the solid particles is a bag-type dust collector.
10. A method of removing contaminants from flue gas flowing through a flue, said contaminants comprising one or more of sulfur dioxide, nitrogen oxides and dust, said method comprising:
respectively spraying an alkaline aqueous solution and an oxidant to the flue gas by using a spraying device in the flue;
drying the liquid phase in the flue in a flue gas drying section at the downstream of the spraying device by using the heat of the flue gas; and
and the solid particles in the flue gas are separated and recovered by a dry method by utilizing a dry method separation and recovery device for the solid particles at the downstream of the flue gas drying section.
11. The method of claim 10, further comprising:
and measuring the temperature in the flue, and controlling the spraying according to the temperature.
12. The method of claim 10,
and blowing the recovered solid particles back to the flue between the spraying device and the solid particle dry separation and recovery device.
CN202010359453.9A 2020-04-29 2020-04-29 Apparatus and method for removing pollutants from flue gas flowing through flue Pending CN113559693A (en)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101632897A (en) * 2009-08-07 2010-01-27 清华大学 Method for simultaneously removing sulfur oxides and nitric oxides in flue gas
CN103691295A (en) * 2013-12-11 2014-04-02 中能东讯新能源科技(大连)有限公司 Horizontal semi-dry process desulfurization device of flue at tail part of boiler
CN105056749A (en) * 2015-07-20 2015-11-18 清华大学 System and method for removing nitric oxides and sulfur oxides in flue gas simultaneously
CN205461734U (en) * 2016-01-11 2016-08-17 北京亚太环保股份有限公司 Desulfurization and prevent scale deposit integration system
CN205550012U (en) * 2016-04-15 2016-09-07 北京宜泽环保科技有限责任公司 Oxidation denitration treatment system of flue gas
CN110354663A (en) * 2018-04-11 2019-10-22 杨晓袆 It is a kind of that dioxin is prevented to generate the method and apparatus with the ultra-clean discharge of flue gas
CN110465169A (en) * 2019-08-20 2019-11-19 张家港市锦明环保工程装备有限公司 A kind of integrative coordinated Processing tecchnics of high-temperature flue gas multi-pollutant and equipment

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101632897A (en) * 2009-08-07 2010-01-27 清华大学 Method for simultaneously removing sulfur oxides and nitric oxides in flue gas
CN103691295A (en) * 2013-12-11 2014-04-02 中能东讯新能源科技(大连)有限公司 Horizontal semi-dry process desulfurization device of flue at tail part of boiler
CN105056749A (en) * 2015-07-20 2015-11-18 清华大学 System and method for removing nitric oxides and sulfur oxides in flue gas simultaneously
CN205461734U (en) * 2016-01-11 2016-08-17 北京亚太环保股份有限公司 Desulfurization and prevent scale deposit integration system
CN205550012U (en) * 2016-04-15 2016-09-07 北京宜泽环保科技有限责任公司 Oxidation denitration treatment system of flue gas
CN110354663A (en) * 2018-04-11 2019-10-22 杨晓袆 It is a kind of that dioxin is prevented to generate the method and apparatus with the ultra-clean discharge of flue gas
CN110465169A (en) * 2019-08-20 2019-11-19 张家港市锦明环保工程装备有限公司 A kind of integrative coordinated Processing tecchnics of high-temperature flue gas multi-pollutant and equipment

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