Wet flue gas denitration technique for nitrite recovery

A nitrite and flue gas technology, applied in the field of wet flue gas denitrification process, can solve the problems of affecting economy, high waste water treatment cost, unfavorable resource recovery and utilization, etc., and achieve simple process system structure, low investment and operation cost , Realize the effect of resource utilization

Active Publication Date: 2009-01-28
ZHEJIANG TIANLAN ENVIRONMENTAL PROTECTION TECH
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AI Technical Summary

Problems solved by technology

[0005] The Chinese invention patent with the publication number CN1768902 and the Chinese invention patent application with the publication number CN1923341 respectively disclose a boiler flue gas ozone oxidation denitrification method and a coal-fired boiler flue gas ozone oxidation simultaneous desulfurization and denitrification device and its method, but it sprays ozone The amount is relatively large, and the molar ratio to nitric oxide is about 0.5-1.5, which affects the economy of the method, and the high-valence nitrogen oxide NO that is easily soluble in water after oxidation 2 , NO 3 or N 2 o 5 In the process of reacting with lye, a mixture of nitrate and nitrite will be generated, and the waste water after absorption will be expensive to treat, which is not conducive to the recycling of resources

Method used

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  • Wet flue gas denitration technique for nitrite recovery

Examples

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Comparison scheme
Effect test

Embodiment 1

[0041] Example 1: Ozone oxidizes NO combined with calcium hydroxide to absorb denitrification and recover calcium nitrite

[0042] After the air is dried and purified, it is sent to the oxygen generator, and the generated oxygen is sent to the ozone generator to prepare high-concentration ozone, which is sprayed into the oxidation reaction device. The reaction temperature is 80°C, and the reaction time is controlled to be at least 0.2s. The amount of ozone sent is based on the measured NO concentration in the flue gas, according to the O 3 / NO molar ratio is about 0.4 and dynamically adjusted to keep NO x The degree of oxidation is about 40%. The oxidized flue gas enters the absorption tower, and the absorbent is calcium hydroxide slurry with a concentration of 20%. The absorbent is recycled, and the pH value of the absorbent in the control system is 9. After the reaction, the slurry is discharged, concentrated by heating and evaporation, then cooled and crystallized, and ce...

Embodiment 2

[0043] Example 2: Activate hydrogen peroxide to oxidize NO at high temperature, then use sodium hydroxide to absorb and denitrate, and recover sodium nitrite

[0044] Air is used as the atomizing medium, and 50% hydrogen peroxide solution is thermally activated and then sprayed into the gas-phase oxidation reactor. The activation temperature is about 500°C, and the reaction time is controlled to be at least 0.2s. h 2 o 2 The feeding amount is based on the measured NO concentration in the flue gas, according to the H 2 o 2 / NO molar ratio is about 0.4 ~ 0.8 dynamically adjusted to keep NO x The degree of oxidation is about 40%. The oxidized flue gas enters the absorption tower, and the absorbent is sodium hydroxide solution with a concentration of 10%. The absorbent is recycled, and the reacted absorbent is concentrated by heating and evaporation, then cooled and crystallized, and centrifuged to obtain the sodium nitrite crystal product.

Embodiment 3

[0045] Example 3: UV activating hydrogen peroxide to oxidize NO, then using calcium hydroxide to absorb and denitrify, and recovering calcium nitrite

[0046] Using air as the atomization medium, photoactivate 70% hydrogen peroxide solution and spray it into the gas-phase oxidation reactor. A low-pressure mercury lamp with a wavelength of 200-320nm is installed in the activation reactor. The temperature of the activation reactor is 95°C to control the reaction. The time is at least 0.2s. h 2 o 2 The feeding amount is based on the measured NO concentration in the flue gas, according to the H 2 o 2 / NO molar ratio is about 0.4 ~ 0.8 dynamically adjusted to keep NO x The degree of oxidation is about 40%. The oxidized flue gas enters the absorption tower, and the absorbent is calcium hydroxide solution with a concentration of 20%. The absorbent is recycled, and the pH value of the absorbent in the control system is 9. After the reaction, the slurry is discharged, concentrate...

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Abstract

The invention discloses a wet-method smoke denitration process used for recovering nitrite, comprising the steps as follows: hydrogen peroxide or ozone is taken as oxidant; the oxidant is uniformly sprayed into smoke disposed by pre-dedusting and desulfurizing so as to carry out gas oxidation reaction and lead the NO in the smoke to be oxidated as NO2; subsequently, alkali liquid is taken as absorbent so as to absorb the mixture of the oxidated NO and NO2 and generate the nitrite; the absorbent is concentrated after absorbing the NO and NO2 and cooled and crystallized; after centrifuging separation, the nitrite crystal is gained. The process of the invention can effectively remove the NOx in the smoke, gains the nitrite with high economic values at the same time, and realizes the resource utilization of denitration outgrowth.

Description

technical field [0001] The invention relates to the technical field of air pollution control, in particular to a wet flue gas denitrification process for recovering nitrite. Background technique [0002] my country is rich in coal resources and cheap. It is the largest coal producer and consumer in the world, and one of the few countries in the world where coal is the main energy source. It is estimated that in the next 50 years, my country's energy structure dominated by coal will not Significant changes occur. According to statistics, China's total energy production in 2002 was 1.39 billion tons of standard coal, ranking third in the world, and its total energy consumption was 1.48 billion tons of standard coal, ranking second in the world. 70% of the country's soot emissions, 90% of sulfur dioxide emissions, 67% of nitrogen oxides, and 70% of carbon dioxide emissions come from coal combustion. In order to protect the environment and realize the sustainable development of...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D53/56B01D53/78
CPCY02A50/20
Inventor 吴忠标盛重义刘越唐念王海强
Owner ZHEJIANG TIANLAN ENVIRONMENTAL PROTECTION TECH
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