Method for simultaneously removing SO.SUB.2 .and NO.SUB.X .in flue gas

Abstract

The invention discloses a method for simultaneously removing SO.sub.2 and NO.sub.x in flue gas: uniformly mixing a water-soluble ruthenium salt with ammonia water to obtain an aqueous solution of a ruthenium-amine complex; subjecting the flue gas and the aqueous solution of the ruthenium-amine complex to a countercurrent contact reaction under the temperature of 5-60 C., pH of 7.5-12 to obtain a solution A and purified gas; discharging the solution A of the step (2) into a crystallization tank to crystallize and separate an ammonium salt to obtain a solution B, returning the solution B to replace the aqueous solution of the ruthenium-amine complex. The invention utilizes the ruthenium-amine complex having a strong capability of complexing with NO as well as residual oxygen in the flue gas to carry out liquid phase catalytic oxidation to convert the NO.sub.x into ammonium nitrate, and the removal efficiency of the NO.sub.x and the SO.sub.2 is high.

Claims

1. A method for simultaneously removing SO.sub.2 and NO.sub.x in flue gas, wherein the specific steps are as follows: (1) uniformly mixing a water-soluble ruthenium salt with ammonia water to obtain an aqueous solution of a ruthenium-amine complex, wherein ruthenium ions in the aqueous solution of the ruthenium-amine complex have a concentration of 0.03-0.20 mol/L, and nitrogen in the ammonia water and ruthenium in the water-soluble ruthenium salt have a molar ratio of (8-50):1; (2) subjecting the flue gas and the aqueous solution of the ruthenium-amine complex of the step (1) to a countercurrent contact reaction under the temperature of 5-60 C. and pH of 7.5-12 to obtain a solution A and purified gas, wherein oxygen in the flue gas has a volume content of 0.5%-10%, and the flue gas and the aqueous solution of the ruthenium-amine complex have a gas-liquid volume ratio of (0.05-8):1; and (3) discharging the solution A of the step (2) into a crystallization tank to crystallize and separate an ammonium salt to obtain a solution B, and returning the solution B to the step (2) to replace the aqueous solution of the ruthenium-amine complex.

2. The method for simultaneously removing SO.sub.2 and NO.sub.x in flue gas according to claim 1, wherein the water-soluble ruthenium salt is one or a mixture of two of ruthenium trichloride and ruthenium iodide.

3. The method for simultaneously removing SO.sub.2 and NO.sub.x in flue gas according to claim 1, wherein in the step (1), the ruthenium ions in the aqueous solution of the ruthenium-amine complex have a concentration of 0.08-0.15 mol/L, and the nitrogen in the ammonia water and the ruthenium in the water-soluble ruthenium salt have a molar ratio of (20-50):1.

4. The method for simultaneously removing SO.sub.2 and NO.sub.x in flue gas according to claim 1, wherein in the step (2), the temperature is 15-40 C., and the pH is 9-12.

5. The method for simultaneously removing SO.sub.2 and NO.sub.x in flue gas according to claim 1, wherein in the step (2), the flue gas and the aqueous solution of the ruthenium-amine complex have a gas-liquid volume ratio of (0.05-5):1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of a ruthenium-amine complex desulfurization and denitration process.

DETAILED DESCRIPTION

(2) The present invention will be further described in detail below with reference to specific implementations, but the protection scope of the present invention is not limited thereto.

Embodiment 1

(3) In this embodiment, the flue gas to be treated is copper smelting flue gas, including 2,500 mg/m.sup.3 of SO.sub.2, 300 mg/m.sup.3 of NO.sub.x, and 0.5% of O.sub.2 (volume content).

(4) As shown in FIG. 1, a method for simultaneously removing SO.sub.2 and NO in flue gas, where the specific steps are as follows:

(5) (1) uniformly mix a water-soluble ruthenium salt with ammonia water to obtain an aqueous solution of a ruthenium-amine complex, where ruthenium ions in the aqueous solution of the ruthenium-amine complex have a concentration of 0.03 mol/L, and nitrogen in the ammonia water and ruthenium in the water-soluble ruthenium salt have a molar ratio of 8:1;

(6) (2) add the flue gas and the aqueous solution of the ruthenium-amine complex of the step (1) to a reaction device for a countercurrent contract reaction under the temperature of 5 C. and pH of 8.0 to obtain a solution A and purified gas, where oxygen in the flue gas has a volume content 0.5%, and the flue gas and the aqueous solution of the ruthenium-amine complex have a gas-liquid volume ratio of 0.05:1; and

(7) (3) discharge the solution A of the step (2) into a crystallization tank to crystallize and separate an ammonium salt to obtain a solution B, and return the solution B to the step (2) to replace the aqueous solution of the ruthenium-amine complex;

(8) by analysis by an industrial mass spectrometer, an emission concentration of SO.sub.2 in a gas outlet is 65 mg/m.sup.3, and an emission concentration of NO.sub.x is 15 mg/m.sup.3.

Embodiment 2

(9) In this embodiment, the flue gas to be treated is copper smelting flue gas, including 3,000 mg/m.sup.3 of SO.sub.2, 250 mg/m.sup.3 of NO.sub.x, and 2% of O.sub.2 (volume content).

(10) As shown in FIG. 1, a method for simultaneously removing SO.sub.2 and NO.sub.x in flue gas, where the specific steps are as follows:

(11) (1) uniformly mix a water-soluble ruthenium salt with ammonia water to obtain an aqueous solution of a ruthenium-amine complex, where ruthenium ions in the aqueous solution of the ruthenium-amine complex have a concentration of 0.08 mol/L, and nitrogen in the ammonia water and ruthenium in the water-soluble ruthenium salt have a molar ratio of 15:1;

(12) (2) add the flue gas and the aqueous solution of the ruthenium-amine complex of the step (1) to a reaction device for a countercurrent contract reaction under the temperature of 20 C. and pH of 9.0 to obtain a solution A and purified gas, where oxygen in the flue gas has a volume content 2%, and the flue gas and the aqueous solution of the ruthenium-amine complex have a gas-liquid volume ratio of 2:1; and

(13) (3) discharge the solution A of the step (2) into a crystallization tank to crystallize and separate an ammonium salt to obtain a solution B, and return the solution B to the step (2) to replace the aqueous solution of the ruthenium-amine complex;

(14) by analysis by an industrial mass spectrometer, an emission concentration of SO.sub.2 in a gas outlet is 50 mg/m.sup.3, and an emission concentration of NO.sub.x is 8 mg/m.sup.3.

Embodiment 3

(15) In this embodiment, the flue gas to be treated is copper smelting flue gas, including 2,800 mg/m.sup.3 of SO.sub.2, 270 mg/m.sup.3 of NO.sub.x, and 5% of O.sub.2 (volume content).

(16) As shown in FIG. 1, a method for simultaneously removing SO.sub.2 and NO.sub.x in flue gas, where the specific steps are as follows:

(17) (1) uniformly mix a water-soluble ruthenium salt with ammonia water to obtain an aqueous solution of a ruthenium-amine complex, where ruthenium ions in the aqueous solution of the ruthenium-amine complex have a concentration of 0.15 mol/L, and nitrogen in the ammonia water and ruthenium in the water-soluble ruthenium salt have a molar ratio of 40:1;

(18) (2) add the flue gas and the aqueous solution of the ruthenium-amine complex of the step (1) to a reaction device for a countercurrent contract reaction under the temperature of 40 C. and pH of 10.0 to obtain a solution A and purified gas, where oxygen in the flue gas has a volume content 5%, and the flue gas and the aqueous solution of the ruthenium-amine complex have a gas-liquid volume ratio of 5:1; and

(19) (3) discharge the solution A of the step (2) into a crystallization tank to crystallize and separate an ammonium salt to obtain a solution B, and return the solution B to the step (2) to replace the aqueous solution of the ruthenium-amine complex;

(20) by analysis by an industrial mass spectrometer, an emission concentration of SO.sub.2 in a gas outlet is 19 mg/m.sup.3, and an emission concentration of NO is 3.2 mg/m.sup.3.

Embodiment 4

(21) In this embodiment, the flue gas to be treated is copper smelting flue gas, including 3,500 mg/m.sup.3 of SO.sub.2, 330 mg/m.sup.3 of NO.sub.x, and 10% of O.sub.2 (volume content).

(22) As shown in FIG. 1, a method for simultaneously removing SO.sub.2 and NO in flue gas, where the specific steps are as follows:

(23) (1) uniformly mix a water-soluble ruthenium salt with ammonia water to obtain an aqueous solution of a ruthenium-amine complex, where ruthenium ions in the aqueous solution of the ruthenium-amine complex have a concentration of 0.2 mol/L, and nitrogen in the ammonia water and ruthenium in the water-soluble ruthenium salt have a molar ratio of 60:1;

(24) (2) add the flue gas and the aqueous solution of the ruthenium-amine complex of the step (1) to a reaction device for a countercurrent contract reaction under the temperature of 60 C. and pH of 12.0 to obtain a solution A and purified gas, where oxygen in the flue gas has a volume content 10%, and the flue gas and the aqueous solution of the ruthenium-amine complex have a gas-liquid volume ratio of 8:1; and

(25) (3) discharge the solution A of the step (2) into a crystallization tank to crystallize and separate an ammonium salt to obtain a solution B, and return the solution B to the step (2) to replace the aqueous solution of the ruthenium-amine complex;

(26) by analysis by an industrial mass spectrometer, an emission concentration of SO.sub.2 in a gas outlet is 22 mg/m.sup.3, and an emission concentration of NO is 4.3 mg/m.sup.3.

Comparative Example

(27) The flue gas to be treated is copper smelting flue gas, including 2,800 mg/m.sup.3 of SO.sub.2, 270 mg/m.sup.3 of NO.sub.x, and 5% of O.sub.2 (volume content).

(28) The copper smelting flue gas is used as to-be-treated gas, and ammonia water is added into a reaction device to fully react with SO.sub.2 and NO.sub.x in the copper smelting flue gas by countercurrent contact; a gas-liquid ratio of the flue gas to aqueous ammonia is controlled to be 5, the reaction temperature is 40 C., and the reaction pH was 10; emission concentrations of the SO.sub.2 and NO.sub.x in a gas outlet are analyzed by an industrial mass spectrometer to be 80 mg/m.sup.3 and 212 mg/m.sup.3, respectively.