Method and system for preparing urea by coupling denitration with electrocatalytic reduction

A technology coupled with electricity and electrocatalysis, applied in chemical instruments and methods, preparation of organic compounds, separation methods, etc., can solve problems such as the combination of nitrogen oxide removal process without consideration, and achieve the effect of enhancing the absorption effect

Active Publication Date: 2021-06-08
TSINGHUA UNIV
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  • Abstract
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  • Claims
  • Application Information

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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 coupling denitration 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 coupling denitration with electrocatalytic reduction. Specifically, the method provided by the invention comprises the following steps of introducing an absorption liquid containing nitrite and nitrate, which is generated by carrying out a denitration process on flue gas containing nitric oxide, into a separation process to separate the nitrite and the nitrate so as to obtain a solution rich in the nitrite and the nitrate, and introducing the solution rich in nitrite and nitrate generated in the separation process into an electro-catalysis process, and carrying out electro-catalytic reduction in the presence of carbon dioxide or carbonate so as to generate a urea solution. The system comprises a denitration device, a separation device connected with the denitration device, and an electro-catalysis device connected with the separation device. The method and the system provided by the invention can be used for deeply removing the nitric oxide in the industrial flue gas at a relatively low temperature, and can realize the recycling of nitrogen.

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 Applications(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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