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Method for preparing sodium nitrite from nitric oxide waste gas through multistage oxidation absorption

A technology of nitrogen oxides and sodium nitrite, applied in chemical instruments and methods, separation methods, dispersed particle separation, etc., can solve the problem of low NOx absorption efficiency, improve absorption efficiency, reduce NOx emissions, and achieve high investment ratio. Effect

Inactive Publication Date: 2011-06-01
NANJING UNIV
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Problems solved by technology

It is reported in China that the nitric acid tail gas is used to produce sodium nitrate, and a higher absorption temperature is used, so the absorption efficiency of NOx is not high

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  • Method for preparing sodium nitrite from nitric oxide waste gas through multistage oxidation absorption
  • Method for preparing sodium nitrite from nitric oxide waste gas through multistage oxidation absorption

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Embodiment Construction

[0028] Three towers are used in series to absorb, the absorbent is NaOH solution, the concentration is 20%, the oxygen content in the oxygenated air is 40%, the intake air is NOx mixed gas, and the gas volume is 600Nm 3 / h, the pressure is 0.3MPa, NO 2 / NO is 0.2. Sodium nitrite solution is obtained through three-stage tower absorption operation, and all three towers use 350Y structured packing. The nitrogen oxide raw gas first enters the molecular sieve fixed bed for dehumidification and drying. After drying, the moisture content is 0.8ppm. In the oxidation box 4, the input amount of oxygen-mixed air is 125Nm 3 / h, the gas pressure at the outlet of the oxidation box is 0.5MPa, the packing height of the absorption tower 7 is 4m, the operating pressure is 0.6MPa, the absorption temperature is 40°C, and the spray density of NaOH liquid is 8.6m 3 / m 2 .h, condensation area is 20m 2 The gas at the top of the absorption tower 7 enters the molecular sieve fixed bed for ...

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Abstract

The invention relates to a method for preparing sodium nitrite from nitric oxide waste gas with low oxidation degree in the industrial process, which comprises the following steps of: after water is removed from the nitric oxide waste gas, mixing the nitric oxide waste gas with oxygen supplying air according to a certain ratio, and introducing the mixture into multistage serial alkaline liquor absorption towers from the bottom of the first stage of absorption tower, wherein the temperature of the absorption liquor is below 50 DEG C, and the pressure inside the tower is 0.03-0.08 MPa; discharging the purified gas up to the standard from the top of the tail tower; and extracting a sodium nitrite solution from the bottom of the first stage of absorption tower. During the serial absorption process, after water is removed from the nitric oxide gas discharged by the last stage of tower, the concentrations of NO2 and NO are measured according to an online nitric oxide analyzer, and the oxygen supplying air is input through PRC control. During the absorption process, the circular absorption liquor of each absorption tower is first conveyed to a cooling device to cool, and thus, the temperature in the absorption tower is controlled. In the invention, common tower equipment with low cost is adopted to obtain sodium nitrate / sodium nitrite (0.02 sodium nitrite solution), the emission of nitric oxide is reduced, and the purposes of energy saving, emission reducing and recycling are achieved.

Description

technical field [0001] The invention relates to the treatment and resource utilization of nitrogen oxide waste gas, in particular to a method for preparing sodium nitrite through multistage oxidation and absorption of nitrogen oxide waste gas. Background technique [0002] Nitrogen oxides (mainly referring to NO and NO 2 , commonly known as NOx) exhaust gas will not only cause acid rain and acid fog, but also destroy the ozone layer, causing serious harm to the natural environment and human production and life. The nitrogen oxides in the atmosphere mainly come from the production waste gas of the nitric acid industry, the fuel combustion waste gas of oil-fired boilers and the exhaust gas of motor vehicles. Therefore, reducing nitrogen oxide emissions and strengthening the control of nitrogen oxide pollution have become a very urgent task in environmental protection. [0003] The mainstream technology of nitrogen oxide removal process can be roughly divided into four categ...

Claims

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Application Information

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IPC IPC(8): B01D53/56B01D53/75B01D53/76B01D53/78
Inventor 耿皎张锋彭璟马少玲张志炳
Owner NANJING UNIV
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