CN100363088C - Method for removing hydrargyrum from coal burning boiler flue gas by ozone oxidation - Google Patents

Method for removing hydrargyrum from coal burning boiler flue gas by ozone oxidation Download PDF

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Publication number
CN100363088C
CN100363088C CNB2005100611237A CN200510061123A CN100363088C CN 100363088 C CN100363088 C CN 100363088C CN B2005100611237 A CNB2005100611237 A CN B2005100611237A CN 200510061123 A CN200510061123 A CN 200510061123A CN 100363088 C CN100363088 C CN 100363088C
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China
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mercury
flue gas
hydrargyrum
water
ozone
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CNB2005100611237A
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Chinese (zh)
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CN1768904A (en
Inventor
岑可法
周俊虎
王智化
刘建忠
杨卫娟
周志军
黄镇宇
程军
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浙江大学
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Abstract

The present invention relates to the technical field of environmental protection, which provides a method for controlling mercury discharge in boiler smoke gas. The method provided by the present invention comprises: ozone is sprayed in a low temperature section of a smoke channel of a boiler with the temperature range of 110 to 150 DEG C, water-insoluble zero valence mercury in boiler smoke gas is oxidized into water soluble divalent mercury, smoke gas is washed by water in a washing tower, divalent mercury is dissolved in water, H2S fixing agents are added in the solution, and divalent mercury generates Hg precipitates. Compared with the existing condition that the mercury discharge elimination efficiency of coal-fired power stations is below 50 to 60% presently, the total mercury elimination efficiency of the method provided by the present invention for eliminating mercury in smoke gas can reach more than 80%.

Description

Method for removing hydrargyrum from coal burning boiler flue gas by ozone oxidation

Technical field

The present invention relates to environmental protection technical field, be specifically related to a kind of boiler smoke mercury emissions control method, be applicable to fire coal, oil burning boiler and Industrial Stoves.

Background technology

Mercury is a kind of poisonous trace heavy metal element, and the mercury of various forms forms methyl mercury after entering atmosphere, water body from pollution sources under biological agent.Methyl mercury can enrichment in water body organisms such as algae, fish, enters human body by biological chain, because mercury can not be discharged by detoxifcation at inside of human body, cause the long-term hazards to health.The annual mercury total amount to airborne release in the whole world is 5000 tons, and wherein 4000 tons is artificial result.It mainly is the factories and miness of producing mercury that the anthropogenic discharge of mercury originates, the smelting of non-ferrous metal, chlorine industry, the burning of electrical equipment industry and fossil fuel.With the U.S. is example, and the discharge capacity of the annual mercury of the U.S. accounts for the whole world to 3% of atmosphere mercury emissions,, about about 158 tons, wherein 87% derive from the burning industry, 10% derives from manufacturing, and 1% derives from other industry.35% mercury is arranged from coal combustion in the nineteen eighty-three atmospheric environment, coal accounts for more than 75% in China's energy resource structure, 80% is used for direct burning, 1978-1995 China accumulative total is to 2493 tons of airborne release mercury, average annual growth rate 4.8%, and along with expanding economy, mass rate of emission also will further increase.

The mercury pollution that is caused by fire coal has caused the attention of countries in the world, U.S. EPA is in the preliminary standard of the discharging of 2004.1 months promulgation coal fired power plant mercury, on December 15th, 2004, Congress formally issued coal-fired power station boiler mercury emissions ultimate criterion, and station boiler all must be carried out the mercury emissions standard before the end of the year 2007.China also will control for coal-fired mercury emissions in the near future.

Present mercury emissions control method mainly contains:

Active carbon adsorption, in higher occasions of mercury concentration such as incinerators, adopt suitable C/Hg ratio, can reach the removal of mercury efficient more than 90%, and, need to adopt higher C/Hg ratio for the lower coal-burning boiler of concentration, just can reach the removal of mercury efficient more than 30%, the active carbon consuming cost is higher, often is difficult to accept.

The calcium-base absorbing agent method is utilized CaO, Ca (OH) 2, CaCO 3, CaSO 42H 2O removes mercury, Ca (OH) 2To HgCl 2Adsorption efficiency can reach 85%, but to simple substance mercury (Hg 0), only at SO 2Under the situation about existing, just can remove 18% Hg 0, and the mercury central 50~60% of coal-fired power station boiler discharging is nonvalent mercury, therefore, calcium-base absorbing agent is not high to the total mercury removal efficiency, still less than 50%.

Utilize wet process of FGD (WFGD) demercuration, because the Hg in the flue gas 2+As HgCl 2Be water-soluble, can in wet desulphurization device, it be caught.Studies show that wet flue gas desulfurizer can catch the Hg of 80-95% 2+Remove, but for Hg 0Catch DeGrain.According to statistics, WFGD for the capture rate of total mercury in 45~55% scopes.

Utilize the suction-operated demercuration of flying dust, the coal-fired flying dust that produces has suction-operated for mercury, and higher phosphorus content is favourable to the energy of adsorption of mercury, but the increase of unburned carbon in flue dust can reduce boiler efficiency, influence flying dust resistivity, reduce the arresting efficiency of electrostatic precipitator for flying dust.This method is lower for the removal efficiency of coal-burning boiler total mercury in addition, is difficult to large-scale promotion application.

Summary of the invention

At deficiency of the prior art, the invention provides a kind of method for removing hydrargyrum from coal burning boiler flue gas by ozone oxidation, may further comprise the steps:

(1) be that 110~150 ℃ boiler flue low-temperature zone sprays into ozone O in temperature range 3, water-fast nonvalent mercury in the boiler smoke is oxidized into divalence mercury soluble in water, the reaction time was at least 0.5 second;

(2) in scrubbing tower, flue gas is washed, divalence mercury is soluble in water, in solution, add H 2The S fixative makes divalence mercury generate the HgS precipitation.

Spray into ozone in the boiler flue low-temperature zone, a position that sprays into of ozone is before the flue dust collector or after flue dust collector.

The described O that sprays into 3With the molal weight ratio of NO in the boiler smoke be 1.1~1.5: 1.

Described scrubbing tower adopts water or alkali lye as absorbent, and scrubbing tower is spray column or packed tower.

Described alkali lye as absorbent is that NaOH, potassium hydroxide or calcium hydroxide are wherein at least a.

The invention has the beneficial effects as follows: contrast present coal fired power plant mercury emissions removal efficiency and be not higher than 50~60% present situation, flue gas hydrargyrum-removing method provided by the invention, the total mercury removal efficiency can reach more than 80%.

Description of drawings

Fig. 1 is a kind of coal-burning boiler fume ozone oxidation mercury emissions control dust-laden arrangement

Fig. 2 is the dustless arrangement of a kind of coal-burning boiler fume ozone oxidation mercury emissions

The specific embodiment

Below in conjunction with the drawings and specific embodiments the present invention is described in further detail.

Discover that wet desulphurization device can remove 80~95% divalence mercury Hg 2+Yet, for nonvalent mercury Hg 0Powerless, 50~60% mercury is Hg in the flue gas 0This method is utilized the NO in the fire coal boiler fume, with ozone it is oxidized to NO 3, utilize NO 3Change the form of Hg, with gaseous state Hg 0Convert Hg to 2+Thereby, total mercury is control effectively in conjunction with wet scrubbing device or existing wet flue gas desulfurizer.All contain a large amount of NO in the fire coal boiler fume, its concentration is about 100~500ppm even higher.The chemical equation of its basic principle is:

NO+O 3→NO 2

NO 2+O 3→NO 3

Hg+NO 3→HgO+NO 2

The solid mercury reaction that takes place in the cleaning solution is:

Hg 2++H 2S→HgS↓+2H +

Detailed process is: spray into ozone in 110~150 ℃ of temperature ranges of boiler back end ductwork, spraying into the position can be before or after electrostatic precipitator, and the ozone straying quatity is pressed O according to NO concentration in the flue gas 3/ NO mol ratio 1.1~1.5: 1 is chosen, can be with nonvalent mercury Hg 0Be oxidized to divalence mercury Hg soluble in water 2+, removing by the wet scrubbing tower, absorption liquid adopts water, and absorption liquid is recycling, and the mercuric absorption liquid of enrichment feeds H 2S generates stable HgS precipitation, separates out back landfill or further processing.If be equipped with limestone/gypsum wet process of FGD equipment, can integrate with this method.

Be removing hydrargyrum from coal burning boiler flue gas by ozone oxidation method wet scrubbing dust-laden arrangement in the specific embodiment 1, implementation as shown in Figure 1.The air drying is sent into dry filter oxygenerator 2 after purifying, the oxygen that produces is sent into ozone generating-device 3 with the preparation high-concentrated ozone, it is 110 ℃ dust-laden flue that ozone is sent into temperature before the electrostatic precipitator 5 behind the air preheater, and straying quatity is pressed O according to flue gas NO concentration 3/ NO mol ratio is constantly adjusted at 1.1: 1, guarantees the 0.5s reaction time at least.Spout adopts perforated grill to spray, and sprays into the position at air preheater exhanst gas outlet 1m place.After electrostatic precipitator 5, enter wet scrubbing tower 7, with Hg 2+Dissolving absorbs, and utilizes H 2S handles to generate and stablizes mercuric sulphide HgS, and absorption liquid is recycling, does further processing after the mercuric sulphide precipitation is separated out, and flue gas is sent into chimney through wet scrubbing tower 7, demister 8 after handling.Scrubbing tower adopts water or alkali lye as absorbent, and scrubbing tower is spray column or packed tower.Alkali lye as absorbent is NaOH, also can be water, potassium hydroxide or calcium hydroxide.

1 is boiler furnace among the figure; 2 is the dry filter oxygenerator; 3 is ozone generating-device; 4 is back-end ductwork; 5 is electrostatic precipitator; 6 is reservoir; 7 are the wet scrubbing tower; 8 is demister; 9 is chimney; 10 mercuric sulphide precipitation process devices.11H 2The S adding set.

O in specific embodiment 2, the specific embodiment 3 3Spray into a temperature and be respectively 130 ℃ and 150 ℃, guarantee the 0.5s reaction time at least; O 3Straying quatity is pressed O according to flue gas NO concentration respectively 3/ NO mol ratio was adjusted in 1.3: 1 and 1.5: 1.Other steps are identical with specific embodiment 1.

Be the dustless arrangement of removing hydrargyrum from coal burning boiler flue gas by ozone oxidation method in the specific embodiment 4, implementation as shown in Figure 2.Ozone is sent into the dustfree environment of 110 ℃ of temperature after the electric cleaner, the amount of sending into according to NO concentration by O 3/ NO mol ratio is chosen at 1.2: 1, sprays into the position and enters the mouth apart from scrubbing tower after deduster, can determine to spray into the position according to actual pipeline, guarantees the 0.5s reaction time at least.Divalence Hg 2+After entering scrubbing tower, carry out absorbing and removing.Scrubbing tower adopts water or alkali lye as absorbent, and scrubbing tower is spray column or packed tower.Alkali lye as absorbent is calcium hydroxide, also can be potassium hydroxide or NaOH.Other steps are identical with specific embodiment 1.

12 is the dry filter oxygenerator among Fig. 2; 13 is ozone generating-device; 14 is back-end ductwork; 15 is electrostatic precipitator; 16 is reservoir; 17 is scrubbing tower; 18 is demister; 19 is chimney; 20 is mercuric sulphide precipitation process device; 21 is boiler furnace; 22 is H 2The S adding set.

At last, it is also to be noted that what more than enumerate only is specific embodiments of the invention.Obviously, the invention is not restricted to above embodiment, many distortion can also be arranged.The present invention can summarize with other the concrete form without prejudice to spirit of the present invention and principal character.Therefore, no matter from which point, above-mentioned embodiment of the present invention all can only be thought can not limit the present invention to explanation of the present invention, claims have been pointed out scope of the present invention, and scope of the present invention is not pointed out in above-mentioned explanation, therefore, in implication suitable and any change in the scope, all should think to be included in the scope of claims with claims of the present invention.

Claims (5)

1. method for removing hydrargyrum from coal burning boiler flue gas by ozone oxidation may further comprise the steps:
(1) be that 110~150 ℃ boiler flue low-temperature zone sprays into ozone O in temperature range 3, water-fast nonvalent mercury in the boiler smoke is oxidized into divalence mercury soluble in water, the reaction time was at least 0.5 second;
(2) in scrubbing tower, flue gas is washed, divalence mercury is soluble in water, in solution, add H 2The S fixative makes divalence mercury generate the HgS precipitation.
2. flue gas by ozone oxidation method for removing hydrargyrum according to claim 1 is characterized in that, sprays into ozone in the boiler flue low-temperature zone, and a position that sprays into of ozone is before the flue dust collector or after flue dust collector.
3. flue gas by ozone oxidation method for removing hydrargyrum according to claim 1 is characterized in that, the described O that sprays into 3With the molal weight ratio of NO in the boiler smoke be 1.1~1.5: 1.
4. flue gas by ozone oxidation method for removing hydrargyrum according to claim 1 is characterized in that, described scrubbing tower adopts water or alkali lye as absorbent, and scrubbing tower is spray column or packed tower.
5. flue gas by ozone oxidation method for removing hydrargyrum according to claim 4 is characterized in that, described alkali lye as absorbent is that NaOH, potassium hydroxide or calcium hydroxide are wherein at least a.
CNB2005100611237A 2005-10-14 2005-10-14 Method for removing hydrargyrum from coal burning boiler flue gas by ozone oxidation CN100363088C (en)

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CNB2005100611237A CN100363088C (en) 2005-10-14 2005-10-14 Method for removing hydrargyrum from coal burning boiler flue gas by ozone oxidation

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Application Number Priority Date Filing Date Title
CNB2005100611237A CN100363088C (en) 2005-10-14 2005-10-14 Method for removing hydrargyrum from coal burning boiler flue gas by ozone oxidation

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CN100363088C true CN100363088C (en) 2008-01-23

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Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ZA200703388B (en) * 2006-05-01 2009-08-26 Boc Group Inc Ozone production process and its use in industrial processes
CN101947409B (en) * 2010-09-29 2012-05-30 东南大学 Flue gas mercury removal system based on photochemical advanced oxidation
US8409535B2 (en) 2010-11-03 2013-04-02 Calpine Corporation System and method for removing a contaminant from a gas stream
CN102512923A (en) * 2011-12-28 2012-06-27 上海交通大学 Method for removing zero valent mercury by oxidation of iodine chloride cooperated with ozone
CN103341306B (en) * 2013-07-24 2015-12-09 上海交通大学 A kind of method of poor ammonia SNCR reduction and oxidative absorption combined denitration demercuration
CN103990366A (en) * 2014-05-20 2014-08-20 江苏大学 Method and system for removing mercury through free radicals generated based on ozone/hydrogen peroxide
CN103990365B (en) * 2014-05-20 2016-08-17 江苏大学 The flue gas purifying method of a kind of ozone/hydrogen peroxide induced radical and system
CN110527851A (en) * 2018-05-25 2019-12-03 华北电力大学 A method of recycling heavy metal Hg from adsorbent

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