CN105032160A - Method for improving mercury removal efficiency of flue gas desulphurization system - Google Patents
Method for improving mercury removal efficiency of flue gas desulphurization system Download PDFInfo
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- CN105032160A CN105032160A CN201510392974.3A CN201510392974A CN105032160A CN 105032160 A CN105032160 A CN 105032160A CN 201510392974 A CN201510392974 A CN 201510392974A CN 105032160 A CN105032160 A CN 105032160A
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- mercury
- flue gas
- desulphurization
- calcium hypochlorite
- sodium formate
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Abstract
The invention provides a method for improving mercury removal efficiency of a flue gas desulphurization system. According to method, a desulphurization and mercury-removing additive composed of, by mass, 30 to 40% of sodium formate and 60 to 70% of calcium hypochlorite is added into desulphurization absorption slurry. The method comprises the following steps: preparing a desulphurization and mercury-removing additive uniform liquid with a concentration of 20 to 30% from sodium formate and calcium hypochlorite in a ground pit or filtrate pit of a flue gas desulfurization tower; pumping the uniform liquid into the desulfurization tower by using a ground pit pump or filtrate pump; and increasing air quantity of an oxidation fan so as to improve oxidation effect. According to method, the desulphurization and mercury-removing additive is applied to flue gas desulphurization, and the additive can effectively accelerate desulphurization reaction speed, reduce limestone content in gypsum, promote oxidation of elemental mercury in flue gas into oxidized mercury, inhibit reduction of oxidized mercury in the slurry and improve efficiency of the desulphurization system in removing sulfur dioxide and mercury in flue gas.
Description
Technical field
The present invention relates to and a kind ofly improves the method for flue gas desulphurization system to mercury removal efficiency, belongs to technical field of waste gas treatment.
Background technology
The SO of coal-burning power plant's discharge
2atmosphere pollution main source and the principal element causing acid rain.Wet method lime stone-gypsum flue gas desulfurization technology has the advantages such as technical maturity, desulfuration efficiency is high, reliable, byproduct can fully utilize, and is the flue gas desulfurization technique that our times is most widely used.
In boiler of power plant process of coal combustion, the mercury in coal enters flue gas, mainly exists with gas phase mercury (Elemental Mercury and oxidation state mercury) and solid phase particles mercury.Entering atmospheric environment for reducing Mercury In Coal Combustion Flue Gas, needing to adopt relevant technologies to control effectively to the mercury in flue gas.
In wet method lime stone-gypsum flue gas desulfurization process, desulphurization system temperature is relatively low, is conducive to the oxidation of mercury, oxidation state Hg in flue gas
2+be soluble in lime stone and absorb slurries, to mercury in flue gas, there is certain removal effect.But in desulfurization cleaning solution, part high concentration metal ingredient impurity makes oxidation state mercury be reduced into element mercury by reduction reaction sometimes, causes the secondary pollution of mercury.Utilizing flue gas desulfurization facilities, adjusting and optimizing sulfur removal technology, strengthen the oxidation efficiency of Elemental Mercury in flue gas, improve the content of mercury oxide, and then improve the demercuration efficiency of wet desulfurization system, is economical and practical demercuration technical measures.The mercury pollution of coal-burning power plant controls also to be in the starting stage in China, external removal of mercury technology be mostly for low-sulfur coal exploitation, and the sulfur content of China's coal for power generation is higher, exploitation is applicable to burning high sulfur coal unit, have cooperative effect, the technology that simultaneously can improve smoke desulfurization efficiency and demercuration efficiency is particularly necessary.
Summary of the invention
The object of the invention is, in order to solve the demercuration problem in flue gas desulfurization course, the present invention proposes a kind ofly to improve the method for flue gas desulphurization system to mercury removal efficiency.
The technical scheme realizing the object of the invention is, absorb in slurries to desulfurization and add the desulfuration demercuration additive be made up of sodium formate and calcium hypochlorite, the mass percent of sodium formate and calcium hypochlorite is: sodium formate 30%-40%, calcium hypochlorite is 60%-70%, and strengthen the oxidized input air of absorption tower oxidation pond, assist the oxidation effectiveness improving mercury.
Described method implementation step is as follows: in fume desulfurizing tower melt pit or filtrate hole, sodium formate, calcium hypochlorite are mixed with the uniform liquid that mass concentration is 20%-30%, squeeze in desulfurizing tower with sump pump or filtrate pump, strengthen oxidation fan air quantity, improve oxidation effectiveness.
The minimum useful effect concentration of desulfuration demercuration additive is greater than 1000mg/L.
The mechanism of action of the present invention is as follows:
In wet method lime stone-desulfurization of gypsum technique, the major control step affecting desulphurization reaction speed is the mass transport process of gas-liquid two-phase interface, and sodium formate can H in reinforcing desulfuration chemical reaction process
+transmission, cushioned the pH value of slurries, facilitated SO
2and CaCO
3dissolving, accelerate SO
2chemical absorbing, thus improve desulfuration efficiency.Calcium hypochlorite in process can promote that in sweetening process Elemental Mercury is converted into oxidation state mercury, avoids oxidation state mercury to be reduced, and oxidation state mercury is desulfurized slurries and absorbs and removed, and improves the removal efficiency of desulphurization system to mercury.Calcium hypochlorite in technique can promote the oxidation conversion of sulfur dioxide in flue gas, improves the removal efficiency of sulfur dioxide, can also improve the ratio of sulfate ion in desulfurization slurry, improve the water separation capability of desulfurated plaster in vacuum belt dewaterer.Strengthen the oxidized input air of absorption tower oxidation pond in technique, can assist to improve the conversion ratio that elemental mercury oxidation is oxidation state mercury.
The beneficial effect of the inventive method is, the inventive method by desulfuration demercuration additive application in flue gas desulfurization, can effectively accelerate desulphurization reaction speed, reduce limestone content in gypsum, promote that in flue gas, elemental mercury oxidation becomes oxidation state mercury, and suppress oxidation state mercury in slurries to be reduced, improve sulfur dioxide and the removal efficiency of mercury in desulphurization system contained by flue gas simultaneously.
Detailed description of the invention
Embodiment 1
The desulfuration demercuration additive of the present embodiment is made up of sodium formate, calcium hypochlorite, and each constituent and mass percent thereof are: sodium formate 35%, and calcium hypochlorite is 65%.
Certain coal-burning power plant 700MW is equipped with the wet method limestone desulfurization unit of SCR, adds the desulfuration demercuration additive of above-mentioned proportion of composing, desulfurizing tower run duration desulfurization slurry volume 2400m
3, add additive 3600 kilograms from filtrate hole, additive is mass concentration 1500mg/L in desulfurization slurry, 3 days test periods, coal-fired sulfur content 0.83%-1.02%.
System desulfuration efficiency 91.5%-93.8% before additive test, in desulfurizing tower inlet flue gas, mercury mean concentration is 53.4 μ g/m3, and mercury mean concentration 24.4 μ g/m3 in desulfurizing tower exiting flue gas, desulphurization system is to the removal efficiency 54.7% of mercury.After desulfuration demercuration additive uses, system desulfuration efficiency 94.3%-97.9%, in desulfurizing tower inlet flue gas, mercury mean concentration is 61.2 μ g/m3, and mercury mean concentration 12.6 μ g/m3 in desulfurizing tower exiting flue gas, desulphurization system is to the removal efficiency 79.4% of mercury.
Embodiment 2
The desulfuration demercuration additive of the present embodiment is made up of sodium formate, calcium hypochlorite, and each constituent and mass percent thereof are: sodium formate 40%, and calcium hypochlorite is 60%.
Certain coal-burning power plant 350MW is not equipped with the wet method limestone desulfurization unit of denitrating system, adds the desulfuration demercuration additive of above-mentioned proportion of composing, desulfurizing tower run duration desulfurization slurry volume 1500m
3, add additive 2000 kilograms from desulfurizing tower melt pit for the first time, additive is initial mass concentration 1300mg/L in desulfurization slurry, 5 days test periods, adds desulfuration demercuration additive 200 kilograms later every day, coal-fired sulfur content 0.65%-0.78%.
System desulfuration efficiency 90.9%-92.6% before additive test, in desulfurizing tower inlet flue gas, mercury mean concentration is 103.1 μ g/m3, and mercury mean concentration 65.8 μ g/m3 in desulfurizing tower exiting flue gas, desulphurization system is to the removal efficiency 36.1% of mercury.After desulfuration demercuration additive uses, system desulfuration efficiency 95.0%-98.3%, in desulfurizing tower inlet flue gas, mercury mean concentration is 98.9 μ g/m3, and mercury mean concentration 28.5 μ g/m3 in desulfurizing tower exiting flue gas, desulphurization system is to the removal efficiency 71.2% of mercury.
Claims (3)
1. one kind is improved the method for flue gas desulphurization system to mercury removal effect, it is characterized in that, described method absorbs in slurries to desulfurization and adds the desulfuration demercuration additive be made up of sodium formate and calcium hypochlorite, the mass percent of sodium formate and calcium hypochlorite is: sodium formate 30%-40%, and calcium hypochlorite is 60%-70%.
2. according to claim 1ly a kind ofly improve the method for flue gas desulphurization system to mercury removal effect, it is characterized in that, described method implementation step is: in fume desulfurizing tower melt pit or filtrate hole, sodium formate, calcium hypochlorite are mixed with the desulfuration demercuration additive uniform liquid that mass concentration is 20%-30%, squeeze in desulfurizing tower with sump pump or filtrate pump, strengthen oxidation fan air quantity, improve oxidation effectiveness.
3. according to claim 1ly a kind ofly improve the method for flue gas desulphurization system to mercury removal effect, it is characterized in that, the minimum useful effect concentration of described desulfuration demercuration additive is greater than 1000mg/L.
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| CN201510392974.3A CN105032160A (en) | 2015-07-07 | 2015-07-07 | Method for improving mercury removal efficiency of flue gas desulphurization system |
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| CN201510392974.3A CN105032160A (en) | 2015-07-07 | 2015-07-07 | Method for improving mercury removal efficiency of flue gas desulphurization system |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6279836A (en) * | 1985-10-03 | 1987-04-13 | Nippon Kokan Kk <Nkk> | Process of removing mercury and mercury compound contained in waste gas |
| JPH091160A (en) * | 1995-06-13 | 1997-01-07 | Chiyoda Corp | Removing method of oxidizing substance and wet type flue gas desulfurization equipment |
| CN1226841A (en) * | 1997-05-26 | 1999-08-25 | 波立登工程有限公司 | Method and apparatus for removing gaseous elementary mercury from gas |
| CN1960795A (en) * | 2004-04-29 | 2007-05-09 | 索鲁科普工业有限公司 | Air pollution control |
| CN102284242A (en) * | 2011-06-16 | 2011-12-21 | 华电电力科学研究院 | Composite additive for synergic removal of various pollutants and preparation method thereof |
-
2015
- 2015-07-07 CN CN201510392974.3A patent/CN105032160A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6279836A (en) * | 1985-10-03 | 1987-04-13 | Nippon Kokan Kk <Nkk> | Process of removing mercury and mercury compound contained in waste gas |
| JPH091160A (en) * | 1995-06-13 | 1997-01-07 | Chiyoda Corp | Removing method of oxidizing substance and wet type flue gas desulfurization equipment |
| CN1226841A (en) * | 1997-05-26 | 1999-08-25 | 波立登工程有限公司 | Method and apparatus for removing gaseous elementary mercury from gas |
| CN1960795A (en) * | 2004-04-29 | 2007-05-09 | 索鲁科普工业有限公司 | Air pollution control |
| CN102284242A (en) * | 2011-06-16 | 2011-12-21 | 华电电力科学研究院 | Composite additive for synergic removal of various pollutants and preparation method thereof |
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