Method and system for preparing urea by denitrification coupled with electrocatalytic reduction

A technology of coupling electricity and urea, which is applied in the direction of chemical instruments and methods, preparation of organic compounds, separation methods, etc., can solve the problem of not considering the combination of nitrogen oxide removal process, and achieve the effect of enhancing the absorption effect

Active Publication Date: 2022-03-25
TSINGHUA UNIV
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Problems solved by technology

However, this technology does not consider how to combine it with the NOx removal process in the flue gas

Method used

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  • Method and system for preparing urea by denitrification coupled with electrocatalytic reduction

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Embodiment 1

[0102] A cement kiln, after adopting a flue gas circulation process, the flue gas emission is 660000m 3 / h, the flue gas temperature is about 200°C; the concentrations of sulfur dioxide and nitric oxide in the flue gas are 800mg / Nm 3 ,300mg / Nm 3 . Ozone is used to oxidize nitric oxide, calcium hydroxide solution is used as alkaline absorption liquid, nanofiltration membrane is used to filter nitrate and nitrite, and copper-palladium alloy is used as a catalyst for electrocatalytic reduction.

[0103] The specific process is:

[0104] The exhaust gas first enters the oxidation device 2, according to the molar ratio O 3 Ozone is added at a ratio of / NO=1.5 to oxidize NO to NO 2 and N 2 o 5 . Contains NO 2 and N 2 o 5 The flue gas enters the spray absorption tower 8, and after contacting with the calcium hydroxide solution as the alkaline absorption liquid, it is absorbed by the absorption liquid. due to NO 2 The absorption coefficient is relatively low, and a gas-liq...

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Abstract

The invention relates to a method and a system for preparing urea by denitrification coupled with electrocatalytic reduction. Specifically, the method of the present invention includes: introducing the absorbing liquid containing nitrite and nitrate produced by the denitrification process of the flue gas containing nitric oxide into the separation process to separate the nitrite and nitrate, thereby obtaining A solution rich in nitrite and nitrate; the solution rich in nitrite and nitrate produced in the separation process is introduced into the electrocatalytic process, and electrocatalytic reduction is carried out in the presence of carbon dioxide or carbonate, thereby generating urea solution. The system of the present invention includes: a denitration device, a separation device connected with the denitration device, and an electrocatalytic device connected with the separation device. The method and system of the invention can be used for deep removal of nitrogen oxides in industrial flue gas at relatively low temperature, and can realize nitrogen resource utilization.

Description

technical field [0001] The invention belongs to the field of environmental protection, and relates to a method and system for preparing urea through denitrification coupled with electrocatalytic reduction, in particular to a method and device for purifying nitrogen oxides in industrial flue gas and recycling nitrogen. Background technique [0002] Nitrogen oxides produced during the combustion of fossil fuels in industrial boilers and various medium- and high-temperature processes are important air pollutants and important precursor pollutants that lead to the formation of photochemical smog and haze, threatening human life, health and the living environment. Therefore, in-depth control of nitrogen oxide emissions has an urgent need for environmental protection, and is of great significance to the construction of ecological civilization and sustainable development. [0003] At present, selective catalytic reduction denitrification (SCR) technology is commonly used for medium...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C273/02C07C273/16B01D53/78B01D53/56
CPCC07C273/02C07C273/16B01D53/78B01D53/56B01D2258/0283
Inventor 彭悦李俊华陈阵尹海波王驰中王荣
Owner TSINGHUA UNIV
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