Flue gas treatment method for simultaneous desulfurization, denitrification and demercuration by calcium and magnesium method

A technology for desulfurization, denitrification, mercury removal, and flue gas treatment, which is applied in the field of flue gas treatment for simultaneous desulfurization, denitrification, and mercury removal by the calcium-magnesium method, can solve the problems of high cost, fast consumption of sulfite, etc. The effect of set rate

Active Publication Date: 2014-05-21
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in this process, the consumption rate of sulfite is relatively fast. If sodium sulf...

Method used

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  • Flue gas treatment method for simultaneous desulfurization, denitrification and demercuration by calcium and magnesium method

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Effect test

Embodiment 1

[0050] With device and process of the present invention, at 5m 3 The flue gas denitrification process is simulated on the experimental simulation device of / h scale. Flue gas volume 5m 3 / h, the flue gas composition is as follows: O 2 5%, NO 200ppm, SO 2 500ppm, the rest is nitrogen, Hg concentration is 20μg / Nm 3 , the flue gas temperature is 150 degrees Celsius, and the pressure is 1 atmosphere. Ozone according to the molar ratio O 3 : The ratio of NO=1.1 is injected, the oxidation rate of NO at the outlet can reach 90%, the concentration of the absorbed MgO slurry is 5%, the concentration of limestone slurry is 5%, and 0.1% iodine chloride slurry is added as a mercury removal agent. Spray absorption device, the number of spray layers is six, and the liquid-gas ratio is 5L / m 3 , the pH is controlled at 6.5, the desulfurization rate can reach 90%, the denitrification efficiency can reach 85%, and the mercury removal efficiency can reach more than 80%.

Embodiment 2

[0052] With device and process of the present invention, at 5m 3 The flue gas denitrification process is simulated on the experimental simulation device of / h scale. Flue gas volume 5m 3 / h, the flue gas composition is as follows: O 2 12%, NO 230ppm, SO 2 550ppm, Hg concentration 20μg / Nm 3 , and the rest is nitrogen, the flue gas temperature is 110 degrees Celsius, and the pressure is 1 atmosphere. Ozone according to the molar ratio O 3 : The ratio of NO=1.2 is injected, the oxidation rate of NO at the outlet can reach 95%, the absorbed MgO slurry concentration is 10%, the limestone slurry concentration is 5%, and 1% ammonium iodide slurry is added as a mercury removal agent. The pH is controlled at 6.5, combined with the bubbling absorption device, the desulfurization rate can reach 90%, the denitrification efficiency can reach more than 85%, and the mercury removal efficiency can reach more than 90%.

Embodiment 3

[0054] With the device and process of the present invention, the flue gas flow rate is 4000Nm 3 / h,O 2 9%, NO 250ppm, SO 2 500ppm, Hg concentration 20μg / Nm 3 , and the rest is nitrogen, the flue gas temperature is 90 degrees Celsius, and the pressure is 1 atmosphere. Ozone according to the molar ratio O 3 : The ratio of NO=1.2 is injected, the oxidation rate of NO at the outlet can reach 95%, the absorbed MgO slurry concentration is 8%, the limestone slurry concentration is 10%, and 0.5% ammonium hypochlorite slurry is added as a mercury removal agent , combined with the spray absorption device, the number of spray layers is six, and the liquid-gas ratio is 8L / m 3 , the pH is controlled at 6.5, the desulfurization rate can reach 95%, the denitrification efficiency can reach 90%, and the mercury removal efficiency can reach more than 85%.

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Abstract

The invention discloses a flue gas treatment method for simultaneous desulfurization, denitrification and demercuration by a calcium and magnesium method. The method comprises the steps of (1) carrying out dust removal on the flue gas of a boiler, then enabling the flue gas to enter a static mixer, spraying ozone into the static mixer at the same time, and carrying out mixed oxidation on the flue gas of the boiler and the ozone; (2) after mixed oxidation, enabling the mixed gas to enter an absorption tower from the bottom of the absorption tower, spraying the mixed slurry of magnesium oxide and limestone or magnesium oxide and lime in a circulating way in the absorption tower, and feeding a demercuration agent into the absorption tower; (3) finally, discharging the sprayed and absorbed flue gas via a chimney from the top of the absorption tower. After the method is adopted, the denitration performance of the whole technology is maintained to be at a higher level, and high efficiency of desulfurization and demercuration is realized.

Description

technical field [0001] The invention belongs to the technical field of environmental protection, and relates to a treatment process for flue gas such as coal-fired boilers, especially the treatment involving simultaneous nitrogen oxides (NO x ), sulfur dioxide (SO 2 ) and mercury (Hg) coal-fired flue gas, the front-end ozone (O 3 ) Oxidation combined with lime / limestone-gypsum desulfurization slurry absorption, and adding magnesium oxide to it to improve the absorption efficiency. Background technique [0002] The main methods of flue gas denitrification are selective catalytic reduction technology (SCR), selective non-catalytic reduction technology (SNCR), wet complexation absorption technology, oxidation-absorption technology, etc. SCR is currently the most commonly used denitrification method. Although this technology has high denitrification efficiency, the basic investment and operating costs are expensive. In addition, this technology has poor adaptability to medium...

Claims

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Application Information

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IPC IPC(8): B01D53/75B01D53/80B01D53/60B01D53/64
Inventor 吴忠标王海强孙承朗刘越
Owner ZHEJIANG UNIV
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