Integrated purification method and system for the industrial exhaust gas containing cyanides, hydrocarbons and NOx

Patent metadata

Field	Value
Publication number	US-10315160-B2
Application number	US-201615568461-A
Country	US
Kind code	B2
Filing date	Mar 4, 2016
Priority date	Jan 12, 2016
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

An integrated purification method and an integrated purification system for an industrial exhaust gas containing cyanides, hydrocarbons and NO x . The method comprises the steps of: 1) subjecting the exhaust gas containing pollutants such as cyanides, hydrocarbons and nitrogen oxides (NO x ) to a gas-liquid separation device ( 1 ) to separate the free fluid, then mixing with the air blown by the air blower ( 201, 202 ), and preheating by the heating unit; 2) the mixture entering into the selective catalytic combustion (SCC) reactor ( 5 ) for the selective catalytic combustion reaction to convert harmful substances into CO 2 , H 2 O and N 2 , the catalysis being performed in two stages: the earlier stage is catalyzed by supported molecular sieve catalyst, and the latter stage is catalyzed by supported precious metal catalyst; and 3) the gas came out from the SCC reactor ( 5 ) entering into the heating unit to recover the heat, and then the purified exhaust gas being discharged directly through the chimney ( 6 ). The system comprises a gas-liquid separation device ( 1 ), a heating unit and a selective catalytic combustion reactor ( 5 ), a gas outlet of the gas-liquid separation device ( 1 ) being connected to the selective catalytic combustion reactor ( 5 ) through the heating unit, and an exhaust gas outlet of the selective catalytic combustion reactor ( 5 ) being connected to a chimney ( 6 ) through the heating unit.

First claim

What is claimed is:

1. An integrated purification method for an industrial exhaust gas of cyanides, hydrocarbons and NO x , wherein the industrial exhaust gas is an industrial exhaust gas containing multi-component pollutants, comprising:
1) subjecting the exhaust gas containing pollutants comprising cyanides, hydrocarbons and nitrogen oxides to a gas-liquid separation device to separate the free fluid, then mixing with the air blown by the air blower, and preheating by a heating unit;
2) entering into a selective catalytic combustion reactor for the selective catalytic combustion reaction, wherein the catalysis is performed in two stages in the selective catalytic combustion reactor, the earlier stage is catalyzed by a supported molecular sieve catalyst, and the latter stage is catalyzed by a supported precious metal catalyst, the temperature of the inlet for entering into the selective catalytic combustion reactor is 280-350° C., the temperature of the catalyst in the earlier stage is controlled at 300-550° C., the temperature of the catalyst in the latter stage is controlled at 500-650° C., and the harmful substances are converted into CO 2 , H 2 O and N 2 under the condition of a bed pressure of 0.5-25 kPa; and
3) the gas emitted from the selective catalytic combustion reactor entering into the heating unit to recover the heat, and then the purified exhaust gas being discharged directly through a chimney.

2. The integrated purification method for the industrial exhaust gas according to claim 1 , wherein in operation 1) the total oxygen volume concentration in the exhaust gas before entering into the SCC reactor is controlled by the flow rate of the air supplemented by the air blower at 3% to 8%.

3. The integrated purification method for the industrial exhaust gas according to claim 1 , wherein in operation 2) the temperature of the inlet of the selective catalytic combustion reactor is 325° C., the temperature of the catalyst in the earlier stage bed is controlled at 430±20° C., and the temperature of the catalyst in the latter stage bed is controlled at 560±20° C.

4. The integrated purification method for the industrial exhaust gas according to claim 1 , wherein in operation 2) the supported molecular sieve catalyst in the earlier stage is a honeycomb monolithic catalyst or granular bundling catalyst, wherein the molecular sieve is one or more molecular sieves selected from a group consisting of ZSM-5 to ZSM-48 series, Beta, Y, MCM-22 to MCM-56 series, SAPO-5 to SAPO-47 series, SBA-15, SBA-16 and TS-1, the supported metal ion is one or more ions selected from a group consisting of copper, iron, cobalt, manganese, nickel, aluminum, and silver.

5. The integrated purification method for the industrial exhaust gas according to claim 1 , wherein in operation 2) a cordierite ceramic or a metal corrugated plate is used as the matrix in the precious metal catalyst in the latter stage, the precious metal is one or more of platinum, palladium, rhodium, silver and ruthenium.

6. The integrated purification method for the industrial exhaust gas according to claim 1 , wherein in operation 2) the ratio of the catalysts filling amounts in the earlier stage and the latter stage is in the range of 1-5:0-3.

7. An integrated purification treatment system for an industrial exhaust gas containing cyanides, hydrocarbons and NO x , comprising:
a gas-liquid separation device, a heating unit and a selective catalytic combustion reactor,
the gas-liquid separation device is provided with a gas outlet, a pipe connecting the gas outlet is connected to an exhaust gas inlet of the selective catalytic combustion reactor through the heating unit, the pipe connecting the gas outlet is provided with an air blower; an exhaust gas outlet of the selective catalytic combustion reactor is connected to a heating medium inlet of the heating unit through a pipe, and a heating medium outlet of the heating unit is connected with a chimney wherein the heating unit includes a heat recovery device and an electric heater, wherein the heat recovery device includes a steam exchanger, an exhaust heat boiler, and an exhaust gas heat exchanger.

8. The integrated purification treatment system for the industrial exhaust gas according to claim 7 , wherein the selective catalytic combustion reactor, a gas distributor, a molecular sieve honeycomb catalyst, an air re-distributor and a precious metal catalyst bed are sequentially provided in the direction from the exhaust gas inlet to the exhaust gas outlet.

9. The integrated purification treatment system for the industrial exhaust gas according to claim 7 , wherein the purification treatment system for the exhaust gas includes two air blowers, wherein the outlet of the first air blower is connected to the pipe connecting the gas outlet, the outlet of the second air blower is connected to the selective catalytic combustion reactor, and the inlet position is located between the molecular sieve honeycomb catalyst and the air re-distributor.

Assignees

• Univ Beijing Chem Tech

Inventors

• Chen Biaohua
• Zhang Runduo
• Zhang Jie
• Shi Dongjun
• Li Yingxia

Classifications

• B01D2258/0283

  Flue gases · CPC title

• B01D53/8621

  Removing nitrogen compounds · CPC title

• B01D53/78

  with gas-liquid contact · CPC title

• B01D53/8628

  Processes characterised by a specific catalyst · CPC title

• B01D2255/1023

  Palladium · CPC title