CN111359413A - Method for treating nitrogen oxides in flue gas of biomass-fired boiler - Google Patents

Method for treating nitrogen oxides in flue gas of biomass-fired boiler Download PDF

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Publication number
CN111359413A
CN111359413A CN202010101058.0A CN202010101058A CN111359413A CN 111359413 A CN111359413 A CN 111359413A CN 202010101058 A CN202010101058 A CN 202010101058A CN 111359413 A CN111359413 A CN 111359413A
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China
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water
aqueous solution
water film
flue gas
denitration
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Pending
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CN202010101058.0A
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Chinese (zh)
Inventor
马明超
胡曼曼
胡晓
孙永先
王理想
牟杰
胡江
胡润东
胡丹红
胡伟
张伟
王庆华
杜防震
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Anhui Ruisai Biochemical Technology Co ltd
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Anhui Ruisai Biochemical Technology Co ltd
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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
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/54—Nitrogen compounds
    • B01D53/56—Nitrogen oxides
    • 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
    • B01D53/96—Regeneration, reactivation or recycling of reactants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/10—Oxidants
    • B01D2251/106—Peroxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/10—Oxidants
    • B01D2251/108—Halogens or halogen compounds
    • 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)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Treating Waste Gases (AREA)

Abstract

The invention relates to a method for treating nitrogen oxides in flue gas of a biomass-fired boiler, which is characterized in that a strong oxidant is dissolved in water, strong base is added to form a circulating water solution for removing the nitrogen oxides, the water solution is sprayed into a water film denitration tower to form a water film, and the nitrogen oxides are contacted with the water film to be oxidized and efficiently absorbed, so that the aim of denitration is fulfilled. The treatment method has simple operation, low requirements on technical conditions, good removal effect of nitrogen oxides, and can reach the national ultra-low emission limit of atmospheric pollutants of 50mg/Nm after flue gas treatment3It is a boiler flue gas treatment method worthy of popularization.

Description

Method for treating nitrogen oxides in flue gas of biomass-fired boiler
Technical Field
The invention belongs to the technical field of environmental protection, and relates to a method for treating nitrogen oxides in flue gas of a biomass-fired boiler.
Background
The biomass-fired steam boiler is used for replacing a coal-fired steam boiler, which is a significant measure for improving the smoke pollution of the steam boiler in China. In fact, in 5 years, the control of the atmospheric pollution of the boiler flue gas in China already comes from the original limit value (120 mg/Nm of particulate matters) of the atmospheric pollution emission of the boiler flue gas3、SO2900mg/Nm3And NOx 400mg/Nm3) Up to the special emission limits (20 mg/Nm of particulate matter)3、SO250mg/Nm3And NOx 150mg/Nm3) And up to the present ultra-low emission limit (particulate matter 10 mg/Nm)3、SO235mg/Nm3And NOx 50mg/Nm3). The industrial steam boiler is suitable for gradual improvement of national air pollution prevention and control technical indexes, and the industrial steam boiler is used for burning coal, fuel oil, biomass and natural gas. The treatment of the boiler flue gas is from simple dust removal to comprehensive treatment of high-end dust removal, desulfurization and denitrification and then to the treatment of the current deep dust removal, desulfurization and denitrification system. However, the cost of steam used in industrial production ranges from about 160 yuan per ton of steam to about 350 yuan per ton of steam to over 810 yuan per ton of steam. In order to achieve the standard emission of the flue gas of the steam boiler, enterprises have to spend a large amount of funds to change a new biomass-fired boiler into a natural gas-fired boiler. Large enterprises are forced to shut down or shut down due to large amounts of lost investment and the inability to withstand the expensive operating costs of natural gas boilers. Whether the smoke of the biomass boiler can be treated to reach the ultralow emission limit of atmospheric pollutantsThe value is the key technical problem to be solved, and related researches are reported at present: the Malefan researches the boiler flue gas dust removal and desulfurization and denitrification technologies, mainly uses the limestone, gypsum and ammonia absorption methods and other desulfurization technologies, and also outlines the low-nitrogen combustion control and the denitrification technologies such as reduction, oxidation and adsorption methods; the application of the SCR desulfurization and denitrification process in the flue gas treatment of the pulverized coal fired boiler is studied by the Baijing technology, and the core is that reducing agent ammonia water is sprayed to the downstream of the flue gas, and NOx is reduced into N under the action of a catalyst2And H2O; the selection of the technical scheme of the flue gas desulfurization and denitration of the biomass boiler is reviewed by Gaohao and the like, and wet and semi-dry desulfurization technologies, low-nitrogen combustion, ozone oxidation, SNCR and other denitration technologies are mainly introduced. In view of the problems of popularization limitation of the existing research results on the biomass boiler flue gas treatment technology, high investment, high operation cost and the like, a treatment method with low research investment, good treatment effect and economic operation is very necessary.
The invention relates to a method for treating nitrogen oxides in flue gas of a biomass-fired boiler, which is characterized in that a strong oxidant is dissolved in water, strong base is added to form a circulating water solution for removing the nitrogen oxides, the water solution is sprayed into a water film denitration tower to form a water film, and the nitrogen oxides are contacted with the water film to be oxidized and efficiently absorbed, so that the aim of denitration is fulfilled. By adding a proper amount of strong oxidant and strong alkali into the water film circulating liquid, the nitrogen oxides can be oxidized and removed, and the industrial problem of removing the nitrogen oxides in the flue gas of the biomass boiler is solved. The treatment method is based on the existing biomass boiler device, and can realize good effects of low investment, good treatment effect and economic operation by simple equipment modification and addition of auxiliary facilities for desulfurization and denitrification by a chemical method. After long-term operation, the treatment system is proved to have the characteristics of operability, economy, popularization and application and the like, and is a treatment method worthy of popularization.
Disclosure of Invention
The invention aims to provide a method for treating nitrogen oxides in flue gas of a biomass-fired boiler, which is characterized in that a strong oxidant is dissolved in water, strong base is added to form a circulating water solution for removing the nitrogen oxides, the water solution is sprayed into a water film denitration tower to form a water film, and the nitrogen oxides are contacted with the water film to be oxidized and efficiently absorbed, so that the aim of denitration is fulfilled.
The invention is realized by the following method:
firstly, adding water into a water collecting tank, respectively adding quantitative strong base and strong oxidant, starting a stirrer to completely dissolve the added substances, and preparing into a denitration aqueous solution.
And the second step, opening a water circulating pump, spraying the aqueous solution into the denitration tower to form a water film, contacting with flue gas, oxidizing and absorbing nitrogen oxide, returning to the water collecting tank along with the water flow, and supplementing strong base and strong oxidant at any time along with continuous circulating absorption of the aqueous solution to keep the concentration in the aqueous solution, thereby ensuring the stability of the removal effect of the nitrogen oxide.
Detailed Description
The present invention will be further illustrated with reference to specific examples, but the present invention is not limited to these specific examples.
Example one:
to the collecting water tank, 20m of water was injected3Adding 6kg of potassium perchlorate and 15kg of sodium hydroxide, starting the stirrer for 0.5-1.0 hour, and preparing the denitration aqueous solution after the added substances are completely dissolved. And (4) starting a water circulating pump, spraying the water solution into the denitration tower to form a water film, allowing the boiler flue gas to be in contact oxidation and absorption with the water film, and following the backwater to come into the water collecting tank. Along with the recycling of the denitration aqueous solution, the potassium perchlorate and the sodium hydroxide are supplemented in time, and the concentration of effective substances in the aqueous solution is kept. After the boiler flue gas emission speed and the denitration operation condition are normal, taking a flue gas sample from the denitration device to detect that the nitrogen oxide emission concentration value is 35.65-36.12mg/Nm3。
Example two:
to the collecting water tank, 20m of water was injected34kg of potassium perchlorate and 10kg of sodium hydroxide are added, the stirrer is started for 0.5 to 1.0 hour, and the denitration aqueous solution is prepared after the added substances are completely dissolved. Starting a water circulating pump, spraying the water solution into the denitration tower to form a water film, and enabling the boiler flue gas to contact with the water film to form oxygenDissolving and absorbing, and returning water to the water collecting tank. Along with the recycling of the denitration aqueous solution, the potassium perchlorate and the sodium hydroxide are supplemented in time, and the concentration of effective substances in the aqueous solution is kept. After the boiler flue gas emission speed and the denitration operation condition are normal, taking a flue gas sample from the denitration device to detect that the nitrogen oxide emission concentration value is 40.32-41.30mg/Nm3。
Example three:
to the collecting water tank, 20m of water was injected3Adding 8kg of sodium chlorate and 16kg of sodium hydroxide, starting the stirrer for 0.5-1.0 hour, and preparing the denitration aqueous solution after the added substances are completely dissolved. And (4) starting a water circulating pump, spraying the water solution into the denitration tower to form a water film, allowing the boiler flue gas to be in contact oxidation and absorption with the water film, and following the backwater to come into the water collecting tank. Along with the recycling of the denitration aqueous solution, sodium chlorate and sodium hydroxide are supplemented in time, and the concentration of effective substances in the aqueous solution is kept. After the boiler flue gas emission speed and the denitration operation condition are normal, taking a flue gas sample from the denitration device to detect that the nitrogen oxide emission concentration value is 42.50-43.29mg/Nm3。
Example four:
to the collecting water tank, 20m of water was injected310kg of sodium chlorate and 15kg of sodium hydroxide are added, the stirrer is started for 0.5 to 1.0 hour, and the denitration aqueous solution is prepared after the added substances are completely dissolved. And (4) starting a water circulating pump, spraying the water solution into the denitration tower to form a water film, allowing the boiler flue gas to be in contact oxidation and absorption with the water film, and following the backwater to come into the water collecting tank. Along with the recycling of the denitration aqueous solution, sodium chlorate and sodium hydroxide are supplemented in time, and the concentration of effective substances in the aqueous solution is kept. After the boiler flue gas emission speed and the denitration operation condition are normal, taking a flue gas sample from the denitration device to detect that the nitrogen oxide emission concentration value is 41.79-42.37mg/Nm3。
Example five:
to the collecting water tank, 20m of water was injected3Adding 85kg of 10% sodium hypochlorite aqueous solution and 12kg of potassium hydroxide, starting the stirrer for 0.5-1.0 hour, and preparing the denitration aqueous solution after the added substances are completely dissolved. Starting a water circulating pump to spray the aqueous solution into the denitration towerAnd a water film is formed, so that the boiler flue gas is in contact oxidation and absorption with the water film and then comes into the water collecting tank along with the return water. Along with the recycling of the denitration aqueous solution, 10% of sodium hypochlorite and potassium hydroxide are supplemented in time, and the concentration of effective substances in the aqueous solution is kept. After the boiler flue gas emission speed and the denitration operation condition are normal, taking a flue gas sample from the denitration device to detect that the nitrogen oxide emission concentration value is 43.30-45.51mg/Nm3。
Example six:
to the collecting water tank, 20m of water was injected3Adding 60kg of 10% sodium hypochlorite aqueous solution and 15kg of potassium hydroxide, starting the stirrer for 0.5-1.0 hour, and preparing the denitration aqueous solution after the added substances are completely dissolved. And (4) starting a water circulating pump, spraying the water solution into the denitration tower to form a water film, allowing the boiler flue gas to be in contact oxidation and absorption with the water film, and following the backwater to come into the water collecting tank. Along with the recycling of the denitration aqueous solution, 10% of sodium hypochlorite and potassium hydroxide are supplemented in time, and the concentration of effective substances in the aqueous solution is kept. After the boiler flue gas emission speed and the denitration operation condition are normal, taking a flue gas sample from the denitration device to detect that the nitrogen oxide emission concentration value is 42.65-43.11mg/Nm3。
Example seven:
to the collecting water tank, 20m of water was injected3Adding 15kg of sodium hydroxide, starting an ozone generator and a circulating water pump to drive internal circulation, mixing and dissolving ozone prepared by the ozone generator and the aqueous solution, detecting the content of ozone in the aqueous solution, and preparing the aqueous solution for denitration when the content of ozone in the water reaches more than 100 mg/L. And (4) starting a water circulating pump, spraying the water solution into the denitration tower to form a water film, allowing the boiler flue gas to be in contact oxidation and absorption with the water film, and following the backwater to come into the water collecting tank. With the recycling of the denitration aqueous solution, the ozone generator continuously prepares and supplies ozone to the aqueous solution to maintain the concentration of the effective substances in the aqueous solution. After the boiler flue gas emission speed and the denitration operation condition are normal, taking a flue gas sample from the denitration device to detect that the nitrogen oxide emission concentration value is 37.10-38.42mg/Nm3。

Claims (4)

1. The invention relates to a method for treating nitrogen oxides in flue gas of a biomass-fired boiler, which is characterized in that a strong oxidant is dissolved in water, strong base is added to form a circulating water solution for removing the nitrogen oxides, the water solution is sprayed into a water film denitration tower to form a water film, and the nitrogen oxides are contacted with the water film to be oxidized and efficiently absorbed, so that the aim of denitration is fulfilled.
2. The method as claimed in claim 1, wherein a strong oxidant is dissolved in water, and a strong base is added to form a circulating aqueous solution for removing nitrogen oxides, and the strong oxidant used is potassium perchlorate, sodium chlorate, ozone and sodium hypochlorite; the used strong base is potassium hydroxide and sodium hydroxide, and the contents of the strong oxidant and the strong base in the aqueous solution are 0.1-3.0% and 0.1-5.0% respectively.
3. The method according to claim 1, wherein the aqueous solution is sprayed into a water film denitration tower to form a water film, and the nitrogen oxide is oxidized and efficiently absorbed by contacting with the water film, and the denitration tower is a general water film dust remover made of marble or stainless steel, and the aqueous solution is pumped into the denitration tower by using a water circulating pump to form the water film, and the water film is contacted with the oxidized nitrogen oxide to be absorbed.
4. The method of claim 1, wherein the specific processing steps are:
firstly, adding water into a collecting tank, respectively adding quantitative strong base and strong oxidant, starting a stirrer to completely dissolve the added substances, and preparing into a denitration aqueous solution;
the second step, open water circulating pump, spout aqueous solution into the denitration tower in, form the water film, carry out and the flue gas contact, with nitrogen oxide oxidation and absorption wherein, follow rivers again and return to the collecting vat in, along with the continuous circulation absorption of aqueous solution, need in time supply strong alkali and strong oxidizer, keep the concentration of active ingredient in the aqueous solution to guarantee that nitrogen oxide gets rid of the stability of effect.
CN202010101058.0A 2020-02-19 2020-02-19 Method for treating nitrogen oxides in flue gas of biomass-fired boiler Pending CN111359413A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040062697A1 (en) * 2002-10-01 2004-04-01 Airborne Pollution Control Inc. Flue gas purification method
CN102225303A (en) * 2011-04-25 2011-10-26 张蕊 Combined apparatus and method for dedusting, desulphurization, denitration, demercuration and smoke extraction of coal-fired flue gas
CN106512681A (en) * 2016-12-20 2017-03-22 南通春光自控设备工程有限公司 Denitrification device
CN107029539A (en) * 2017-04-07 2017-08-11 上海盛剑环境系统科技有限公司 A kind of processing method of the waste gas containing oxynitrides
CN108671732A (en) * 2018-07-23 2018-10-19 山东恒科环保设备有限公司 A kind of boiler and kiln tail gas minimum discharge integrated apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040062697A1 (en) * 2002-10-01 2004-04-01 Airborne Pollution Control Inc. Flue gas purification method
CN102225303A (en) * 2011-04-25 2011-10-26 张蕊 Combined apparatus and method for dedusting, desulphurization, denitration, demercuration and smoke extraction of coal-fired flue gas
CN106512681A (en) * 2016-12-20 2017-03-22 南通春光自控设备工程有限公司 Denitrification device
CN107029539A (en) * 2017-04-07 2017-08-11 上海盛剑环境系统科技有限公司 A kind of processing method of the waste gas containing oxynitrides
CN108671732A (en) * 2018-07-23 2018-10-19 山东恒科环保设备有限公司 A kind of boiler and kiln tail gas minimum discharge integrated apparatus

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