Process and apparatus for treating contaminated gas

Abstract

The present invention provides a process and apparatus for treating contaminated gas. A contaminated gas containing volatile organic compounds is continuously introduced into a reactor to allow the gas to contact a metal oxide catalyst and an oxidant for a period of time. The concentration of the volatile organic compounds can be thus reduced. The treated gas is then continuously emitted from the reactor. The concentration of the organic compounds of the emitted gas and/or the concentration of the oxidant are continuously monitored, and the oxidant feeding amount is controlled according to the monitored concentration. By means of the process of the present invention, volatile organic compound-containing waste gas with high humidity can be effectively treated, and the utility rate of the oxidant can be increased.

What is claimed is:  
     
         1 . A process for treating a contaminated gas, comprising the following steps: 
 continuously introducing a contaminated gas containing volatile organic compounds into a reactor;    treating the contaminated gas by allowing the contaminated gas into the reactor to contact a metal oxide catalyst and an oxidant for a period of time to decrease the concentration of the volatile organic compounds;    continuously expelling the treated gas from the reactor;    continuously monitoring a value selected from the group consisting of the concentration of the organic compounds of the emitted gas, the concentration of the oxidant of the emitted gas, and a combination thereof; and    controlling the oxidant feeding amount according to the monitored value.    
     
     
         2 . The process as claimed in  claim 1 , wherein 
 the monitoring step continuously monitors the concentration of the organic compounds of the emitted gas,    the controlling step increases the oxidant feeding amount when a second concentration monitored is higher than a first concentration monitored, and decreases the oxidant feeding amount when a second concentration monitored is lower than a first concentration monitored,    wherein the second concentration is monitored at a time after the first concentration is monitored.    
     
     
         3 . The process as claimed in  claim 1 , wherein 
 the monitoring step continuously monitors the concentration of the oxidant of the emitted gas,    the controlling step decreases the oxidant feeding amount when a second concentration monitored is higher than a first concentration monitored,    wherein the second concentration is monitored at a time after the first concentration is monitored.    
     
     
         4 . The process as claimed in  claim 1 , wherein the monitoring step continuously monitors both the concentration of the organic compounds of the emitted gas and the concentration of the oxidant of the emitted gas.  
     
     
         5 . The process as claimed in  claim 1  wherein the volatile organic compound is selected from the group consisting of chlorinated alkanes, chlorinated alkenes, alkanes, alkenes, aromatic compounds, ketones, ethers, alcohols, organic acids, amines, and mixtures thereof.  
     
     
         6 . The process as claimed in  claim 1 , wherein the contaminated gas further contains an ill-smelling material.  
     
     
         7 . The process as claimed in  claim 6 , wherein the ill-smelling material is selected from the group consisting of nitrogen-containing compounds, sulfur-containing compounds, and mixtures thereof.  
     
     
         8 . The process as claimed in  claim 1 , wherein the metal oxide catalyst is selected from the group consisting of iron oxide, manganese oxide, and nickel oxide.  
     
     
         9 . The process as claimed in  claim 1 , wherein the oxidant is selected from the group consisting of hydrogen peroxide (H 2 O 2 ), ozone (O 3 ), and a mixture thereof.  
     
     
         10 . The process as claimed in  claim 1 , wherein the contaminated gas to be introduced has a humidity higher than 10%.  
     
     
         11 . The process as claimed in  claim 10 , wherein the contaminated gas to be introduced has a humidity between 20% and 100%.  
     
     
         12 . The process as claimed in  claim 11 , further comprising increasing the temperature of the contaminated gas in the treating step by 5° C. to 70° C.  
     
     
         13 . A process for treating a contaminated gas, comprising the following steps: 
 continuously introducing a contaminated gas containing volatile organic compounds into a reactor;    treating the contaminated gas by allowing the contaminated gas into the reactor to contact a metal oxide catalyst and an oxidant for a period of time to decrease the concentration of the volatile organic compounds; and    continuously expelling the treated gas from the reactor;    wherein the contaminated gas to be introduced has a humidity between 20% and 100% and a temperature of T° C., and the contaminated gas is heated to a temperature between (T+5)° C. and (T+70)° C. in the treating step.    
     
     
         14 . A process for treating a contaminated gas, comprising the following steps: 
 continuously introducing a contaminated gas containing ozone into a reactor;    treating the contaminated gas by allowing the contaminated gas into the reactor to contact a metal oxide catalyst for a period of time to decrease the concentration of ozone; and    continuously expelling the treated gas from the reactor;    wherein the contaminated gas to be introduced has a humidity between 20% and 100% and a temperature of T° C., and the contaminated gas is heated to a temperature between (T+5)° C. and (T+70)° C. in the treating step.    
     
     
         15 . An apparatus for treating a contaminated gas, comprising: 
 an oxidant generator for generating an oxidant;    a reactor for accommodating a metal oxide catalyst, a continuously introduced contaminated gas containing volatile organic compounds, the oxidant generated from the oxidant reactor, such that the concentration of the volatile organic compounds in the contaminated gas is decreased and the treated gas is continuously emitted from the reactor;    a monitoring device for continuously monitoring a value of the emitted gas, the value being selected from the group consisting of the concentration of the organic compounds of the emitted gas, the concentration of the oxidant of the emitted gas, and a combination thereof; and    a controlling device for controlling the oxidant feeding amount according to the monitored value.