Industrial waste gas pollution is currently one of the main sources of pollution in my country. If it is not treated in time, it will easily cause diseases after being absorbed by the human body and affect peoples health. Therefore, effecti
Industrial waste gas pollution is currently one of the main sources of pollution in my country. If it is not treated in time, it will easily cause diseases after being absorbed by the human body and affect people's health. Therefore, effective measures must be taken to treat waste gas, especially organic waste gas, to improve air quality and reduce the occurrence of diseases. The article analyzes and discusses the technologies and methods for the treatment of organic waste gas.
1. The main composition and characteristics of organic waste gas
By analyzing the components of most organic waste gas, it can be concluded that its composition mainly includes: formaldehyde, benzene, toluene, xylene and other benzene series, acetone and methyl ketone, ethyl acetate, oil, furfural, styrene, acrylic acid, Resin, additives, paint mist, and some organic gases containing hydrocarbons, hydrogen and oxygen. Organic waste gas has the following characteristics: toxic, explosive, flammable, insoluble in water, soluble in organic solvents, and difficult to handle. If it is not effectively managed, it will pose a threat to people's health. By adopting corresponding treatment technologies, organic waste gas can be effectively treated, and some of the treated substances can be reused.
2. Treatment technology and method of organic waste gas
After years of research, there are many technologies and methods that can effectively treat organic waste gas and have achieved good results.
(1) . Adsorption method
① Direct adsorption method
Activated carbon is used to directly adsorb organic waste gas. The adsorption rate is very high, reaching above 96%, and the method is small and simple. But when the activated carbon is in a saturated state of adsorption, the degree of adsorption of organic waste gas will be greatly reduced, only about 35%, and the adsorption of "triphenyl" waste gas can only reach 20% to 25%, which means that one ton of activated carbon can adsorb "Triphenyl" gas is only 200-250kg. However, the saturated activated carbon cannot be regenerated. If the adsorption effect of the activated carbon is to be improved, the activated carbon needs to be replaced, which causes high processing costs and secondary pollution problems.
② Adsorption-regeneration method
This method uses adsorbents such as fibrous activated carbon or granular activated carbon to adsorb organic waste gas. After reaching saturation, the activated carbon is blown back with superheated steam for desorption and regeneration. The water vapor and the desorbed "triphenyl" gas are condensed and separated, and can be recovered. Benzene" liquid. Using this method has the advantages of fast desorption and good condensation adsorption effect, but it has obvious shortcomings: such as the corresponding steam and high corrosiveness; and the need to separate the recovered liquid twice, and the residual moisture in the activated carbon must be dried After that, second adsorption is performed, which is costly.
This method is suitable for waste gas treatment with high concentration, small air volume and certain recycling value. Otherwise, this process should not be selected. In addition, the technology needs to be further improved and improved.
③ Adsorption-catalytic oxidation.
The new type of activated carbon is used to adsorb organic waste gas with low concentration. After the adsorption reaches the corresponding saturation, it is heated by hot air to desorb the exhaust gas such as "triphenyl" in the adsorption, and then the organic waste gas purification treatment is achieved through the catalytic combustion method. Purpose, in addition, the hot gas can be recycled and used as waste heat.
Using this method, various adsorption methods can be used comprehensively to effectively solve the problem of large air volume and low concentration organic waste gas. This method is a relatively mature method in China. Since organic waste gas contains many impurities such as phosphorus, lead, tin, mercury, etc., it is easy to cause catalyst poisoning.
Therefore, when using a catalyst, a certain carrier should be added to reduce the use of the catalyst, while increasing its use area, reducing sintering, and improving the stability of the catalyst. The commonly used catalyst carriers include asbestos, clay, activated carbon and other materials, which can be selected according to actual conditions in specific applications.
(2). Process characteristics and technological progress of catalytic combustion technology
According to the preheating method and enrichment method of organic waste gas, catalytic combustion is divided into the following three types:
① Preheating: This is the most common method of catalytic combustion. The temperature of the organic waste gas is below 100°C, the concentration is also low, and the heat is not self-sufficient, so it needs to be heated in the preheating chamber before entering the reactor. After combustion, the purified gas exchanges heat with the untreated exhaust gas in the heat exchanger to recover some heat. This skill generally uses coal gas or electric heating to raise the temperature to the light-off temperature required for the catalytic reaction.
② Self-heat balance type: When the exhaust temperature of organic waste gas is higher than the light-off temperature (about 300℃) and the content of organic matter is high, the heat exchanger recovers some of the heat generated by the purified gas, and the heat balance can be maintained under normal operation. To make up for the heat, it is generally only necessary to install an electric heater in the catalytic combustion reactor for use during light-off.
③ Adsorption-catalytic combustion: When the flow rate of organic waste gas is large, the concentration is low, the temperature is low, and the selection of catalytic combustion requires a lot of fuel, the adsorption method can be used to adsorb the organic waste gas on the adsorbent for concentration, and then pass through the hot air Purging, desorption and concentration of organic waste gas into high-concentration organic waste gas (can be concentrated more than 10 times), and then catalytic combustion. At this time, the normal operation can be maintained without compensating for the heat source.
(3). Biological Law
Biological purification is commonly referred to as an oxidation process: biological purification depends on the organic matter attached to the active microorganisms and moist media as the energy of life for timely conversion, generally converting it into inorganic matter (CO2, H2O) and common Cellular material. The current biological purification process mainly includes three types: biological filtration method, biological trickling filter bed and biological washing bed.
3. (1) Among the many organic waste gas treatment technologies, biological treatment technology is a technology with good application prospects. Its operating cost is low, energy consumption is small, and no obvious secondary pollution is generated. With the continuous improvement of its technology, waste gas has attracted more and more attention and is widely used in industrial organic waste gas treatment. The focus of the research on biological treatment technology should be to strengthen the improvement of filler performance, equipment structure and process conditions, as well as the research on the processing capacity of different strains.
(2) Adsorption technology is currently one of the more mature and well-formed technologies in the treatment of organic waste gas, but it has problems such as insufficient capacity of the treatment equipment and the need for regeneration of the adsorbent, which limits the application and development of the technology.
(3) Catalytic combustion technology has low investment, simple equipment, convenient operation, thorough purification, and can treat low and high concentrations of organic waste gas. It is currently the most widely used and cost-effective treatment technology. The future research direction of this technology should focus on how to prevent catalyst deactivation caused by non-VOC substances and poisoning caused by heavy metals.