What are the common waste gas treatment methods?
Hello, landlord, according to your question, here are your detailed answers:
Common waste gas treatment methods:
1, absorption purification method
Absorption method is a common method to purify gaseous pollutants Z. Absorption method is defined as: treating waste gas with a suitable liquid absorbent, so that the gaseous pollutants in the waste gas can be dissolved in the absorption solution or chemically react with the active components in the absorption solution to enter the liquid phase, thereby separating the gaseous pollutants from the waste gas; In other words, the process of selective absorption and separation of one or more components in mixed gas by absorbent is called absorption.
Absorption is usually divided into physical absorption and chemical absorption, and the difference is shown in the following table:
2. Adsorption purification method
Adsorption is to treat the fluid mixture with porous solid adsorbent, so that one or more components contained in it can be adsorbed on the solid surface to achieve the purpose of separation. The difference between adsorption process and absorption is that after absorption, the absorption components are evenly distributed in the absorption phase, and after adsorption, the absorption components accumulate or concentrate on the adsorbent, which is only a heterogeneous process.
At present, adsorption operation has been widely used in organic chemical industry, petrochemical industry and other production departments. This method is also widely used in environmental engineering, mainly because of the high selectivity of adsorbent, which can separate mixtures that are difficult to separate in other processes, effectively remove low-concentration harmful substances, and has simple equipment, convenient operation, high purification efficiency and automatic control.
The adsorption process is a dynamic process. In this process, adsorbate diffuses from the fluid to the surface of adsorbent and the inner surface of micropores, releasing heat and being adsorbed on the surface of adsorbent. Desorption is the opposite of adsorption.
After adsorbate is adsorbed on the surface of adsorbent, the internal energy of adsorbate molecules decreases due to the changes of molecular motion forms, such as diffusion, vibration, rotation, etc., thus releasing energy, which is called adsorption heat. Vaporization heat and bonding heat are two components of adsorption heat. The adsorption heat is about 1.5 times larger than the vaporization heat, and the existence of special circumstances is not excluded. Generally speaking, the heat of adsorption is affected by adsorption capacity, adsorption temperature, and fluid evacuation speed during adsorption. If the adsorption heat is not led out in time, part of the heat absorbed by desorption molecules will have a negative impact on the adsorption process.
3, condensation purification method
Condensation purification method is to make use of the different properties of saturated vapor pressure of substances at different temperatures, and use the methods of cooling and pressurizing to condense gas in vapor state and separate it from waste gas, so as to achieve the purpose of purification or recovery.
The removal degree of harmful gases by condensation purification is related to cooling temperature and saturated vapor pressure of harmful components. The lower the cooling temperature, the closer the harmful components are to saturation and the higher the removal degree. It is especially suitable for treating organic solvent vapor with waste gas concentration above 10000* 10-6, but not suitable for treating low-concentration waste gas. The condensation process can be realized by increasing the pressure at constant temperature, or by decreasing the temperature at constant pressure. Exhaust gas can be purified by condensation, but cooling water at room temperature can not meet the high purification requirements. In order to purify Q, it is necessary to cool and pressurize, which is more difficult and costly to treat. Therefore, adsorption, combustion and condensation are usually used as pretreatment of net high concentration organic gas to achieve the purpose of reducing organic load and recovering valuable products. In addition, condensation purification is generally only applicable to the case of high vapor concentration in the air, so the vapor concentration entering the condensation device can be above the explosion limit, and the concentration when the condensation device comes out can be below the explosion lower limit, just between the explosion upper limit and the explosion lower limit during condensation, which is not conducive to A- safety.
4. Catalytic purification method
Catalytic purification method is a purification method that makes gaseous pollutants pass through the catalyst bed and undergo catalytic reaction under the action of catalyst, and transform them into harmless substances or substances that are easy to treat and recycle. There are two kinds of catalytic purification methods: catalytic oxidation and catalytic reduction. Catalytic oxidation method: pollutants in waste gas are oxidized under the action of catalyst. For example, SO2 in exhaust gas can be decomposed into H2O and CO2 through the oxidation process of burning organic compounds in catalytic exhaust gas. Catalytic reduction method is a purification process in which pollutants in waste gas react with reducing gas under the action of catalyst. For example, nitrogen oxides in waste gas react with NH3 under the action of catalyst to generate harmless gas N2. Catalytic purification is characterized by avoiding secondary pollution that may be produced by other methods, simplifying the operation process and having high conversion rate for pollutants with different concentrations. Its main application is to convert hydrocarbons into carbon dioxide and water, nitrogen oxides into nitrogen, and sulfur dioxide into sulfur trioxide for recycling, catalytic combustion of organic waste gas and odor, and catalytic purification of automobile exhaust. Its disadvantage is that the price of catalyst is high, and the preheating of exhaust gas consumes a certain amount of energy.
The pollutant content in waste gas is usually low, and it often has the following characteristics after catalytic purification treatment: 1) Because of the low pollutant content in waste gas, small thermal effect in the process and simple reactor structure, fixed bed catalytic reactor is often used. 2) The amount of waste gas to be treated is often large, which requires that the catalyst can withstand the influence of fluid scouring and pressure drop. 3) Due to high purification requirements, complex exhaust gas components and great changes in some reaction conditions, the catalyst is required to have high selectivity and thermal stability.
5. Biological methods
In Genf-Villetted, the waste gas is purified once by a biological purification device. The technology of waste gas biological treatment developed rapidly in 1980s and 1990s, and the Netherlands and Germany became the G countries that applied waste gas biological treatment on a large scale. Subsequently, the application of biotechnology in waste gas treatment has become more and more extensive. At present, there are more than 7,500 biogas purification devices in Europe, half of which are used to treat sewage and compost odor. It has also formed an important system in the purification principle and engineering application experience of biodegradable gases. Biological purification technology makes up for the shortcomings of traditional physical and chemical treatment technology. The traditional method needs special safety operation procedure management, which has high energy consumption and large economic investment. In contrast, biological purification is a clean treatment method, which has become the frontier and hot spot of waste gas treatment, especially biochemical waste gas treatment.
Biological waste gas purification technology is a multi-disciplinary environmental protection high-tech. Specifically, it is a mature method based on microbial treatment of wastewater and a frontier hot technology for purifying low-concentration industrial waste gas. The existing research in China shows that low-concentration industrial waste gas cannot be purified economically and effectively by conventional technology, while biological waste gas purification technology is effective and has obvious technical and economic advantages.
6. Membrane separation and purification
Membrane purification method is that when mixed gas permeates a specific membrane under the action of pressure gradient, different gases have different permeation speeds, so that different components in the gas mixture can be separated. Pressure difference, concentration difference and potential difference promote the membrane separation process. Membrane separation technology is a new separation technology which uses membrane to separate, purify and concentrate the mixture according to the difference of selective permeability of each component in the mixture. There are at least two interfaces between two separated phases or two parts, which can limit and transfer specific forms of fluid substances. These two interfaces are bridges for fluid contact and transfer between the two sides. For fluids, the separation membrane can be translucent or completely transparent to ultraviolet rays, but it cannot be completely impermeable to ultraviolet rays.
The main feature of membrane separation is to realize the separation of the molecular size of mixture and substance, and it will choose osmotic membrane as the separation means. There is no phase change in the membrane separation process, so the operation can be carried out at room temperature, which avoids the disadvantage that the properties of the concentrate and concentrate change due to high temperature. Membrane separation is widely used in food, medicine and other industries because of its many advantages. It has the advantages of low energy consumption, low cost, high efficiency, no pollution and recoverable useful substances. For the separation of isomers, components with similar properties, heat-sensitive components and biological components, membrane separation method is very suitable, and sometimes it can replace chemical unit operations such as distillation, extraction, evaporation and adsorption. Practice shows that membrane separation will become a very useful technology if conventional separation cannot be realized by economic methods. The combination of conventional separation and membrane separation is more economical and effective. Based on the above advantages, membrane science and membrane technology have developed rapidly in the past two or three decades, and have become indispensable separation means in industrial and agricultural production, national defense, science and technology and people's daily life, and are more and more widely used in chemical industry, environmental protection, food, medicine, electronics, electric power, metallurgy, textile, seawater desalination and other fields.
7, combustion purification method
Burning is used to destroy toxic gas, steam or smoke and dust, so that it becomes a non-toxic and harmless substance, which is called combustion purification. Combustion purification can only destroy toxic gases and smoke that are flammable or can be decomposed at high temperature. Its chemical action is mainly combustion oxidation and in some cases thermal decomposition. Combustion purification can be widely used in the purification of organic solvent vapors and hydrocarbons. These toxic substances are flammable and harmful gases with high concentration and high calorific value during combustion and oxidation, and the combustion temperature is generally 600~800℃. C. The combustion method is simple and easy to operate, and can recover heat energy, but it can't recover harmful gases, which is easy to cause secondary pollution.
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What are the good methods for waste gas treatment in factories?
√ Hello, landlord. According to your questions, here are your detailed answers:
The purification treatment of industrial waste gas discharged from factories is roughly divided into three important links, from waste gas collection, to waste gas treatment equipment and process purification, and then to exhaust the atmosphere from the chimney after the end gas reaches the standard. Let's take a closer look. If the factory has any waste gas treatment needs, please contact us immediately! Look forward to cooperating with you.
What treatment must the waste gas discharged from the factory go through?
I. Exhaust gas collection
According to the actual production situation of working conditions, suitable side suction or top suction exhaust hood is selected at each pollution source of factory exhaust emission, and connected with air ducts one by one to form a complete exhaust gas collection system. After ZI, the exhaust gas is collected under the power of induced draft fan.
Due to the different waste gas treatment processes, before waste gas collection, it is necessary to consider whether the composition of waste gas discharged from the factory is complex and whether the waste gas with different properties is collected in a classified way, so as to facilitate the purification of the end waste gas to meet the standard.
Second, choose waste gas treatment equipment and purification process
After a clear understanding of the composition, concentration and displacement value of the waste gas discharged from the factory, the waste gas treatment process is determined first, and then the waste gas treatment equipment is purchased from the manufacturer.
In the idle place of the factory, choose the installation site according to the size of the waste gas treatment system, then level and harden the ground with cement, and the equipment can be installed after entering the factory.
Or consult the environmental protection company, explain the parameters of the waste gas discharged by the factory, and provide the waste gas treatment scheme, and then purchase the corresponding waste gas treatment equipment from the manufacturer according to the requirements of the waste gas process design.
Contact the environmental protection engineering company. If the company's qualification meets the requirements, it will install waste gas treatment equipment at the designated waste gas treatment site until the equipment installation is completed, and then carry out debugging and operation.
Third, exhaust emission detection.
There is a waste gas detection link after Zui, which will affect or affect whether the gas detection at the chimney discharge port meets the standard and meets the emission requirements of national J or local environmental protection departments after the waste gas discharged from the factory is purified. Exhaust emission detection can be divided into offline detection and online monitoring. Most small and medium-sized enterprises monitor offline. The installation requirements of online monitoring are determined by J Environmental Protection Department of China according to the nature, scale and emission characteristics of different industries.
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What are the general methods of waste gas treatment?
The treatment method of organic waste gas is as follows:
One is the masked dilution method. As the name implies, masking dilution is to use gases with other smells to cover up the boring and uncomfortable stench in the exhaust gas, so as to achieve the purpose of deodorization; The dilution rule is to dilute high-concentration odor by blowing air until it is difficult to be detected by human senses. This method essentially eliminates the negative influence of odor from the level of sensory perception, but the odor factors that lead to odor still exist.
The second is the absorption method. This is also one of the technologies with the highest penetration rate and the widest application range in municipal and industrial deodorization at present. It mainly uses adsorbents such as activated carbon, and its porous structure has huge specific surface area and van der Waals force to adsorb various gas molecules including odor factors in waste gas, so as to achieve the effect of separation from gas flow. Although the technology is mature and the cost is relatively low, the malodorous components are not really removed, and the adsorbate needs to be desorbed and secondary treated in the later stage, so the service life is short and the effect is not good when dealing with high-concentration malodor.
The third is the cracking method. Through various means to decompose and destroy malodorous gas molecules, the problem of waste gas treatment can be solved directly from the source of malodor. With the development of environmental protection industrial technology, combustion method, pyrolysis method, chemical method, ultraviolet photolysis method, plasma method and biological method have been born in industry. Among them, super plasma method and biological method, as new application technologies in deodorization industry, are being widely used because of their advantages of high deodorization efficiency, low energy consumption, high safety factor and no secondary pollution.
The ion tube developed by Kewei Environmental Protection adopts high-tech core components imported from bioclimatic in Germany, and rare elements such as titanium, neodymium and cerium are added to the material structure of the ion tube. The main structure of the generator consists of a synchrotron and a mesh electrode. The ion tube is wrapped in the timing cavity and does not contact with the external mesh electrode. Compared with the general ion tube competitors with immature technology in the market, the distribution of electric field lines is formed in a very fine annular space as low as 0. 1mm, ensuring full contact with air and polluted gas molecules.
The ion tube is sealed and reinforced by high-density PVC sealing ring, and the bottom is connected with the ion seat by screws, which is convenient to assemble and disassemble; The mesh electrode is connected to the steel column on the ion base through the contact of the metal paddle, which is more suitable for later maintenance. The control device includes ion concentration adjustment and power supply. The shape of internal wire is clear and regular, which is convenient for maintenance and reflects the quality of German seiko everywhere. The mesh electrode is made of 304 stainless steel, the circuit is protected by wear-resistant, high-temperature resistant and corrosion-resistant insulating rubber winding, and the base is upgraded with anti-corrosion and rust-proof technology.
The special transformer for super ion tube has the characteristics of light and thin structure, strong stability and high durability. Built-in custom chip dynamically controls the voltage and current in the equipment. Compared with transformers commonly used in ultraviolet throttling and plasma competing products, this kind of equipment is easy to be paralyzed due to excessive temperature or unstable voltage. By matching the special transformer, the service life of the product is greatly prolonged and the maintenance cost is saved. Although the price of ordinary transformers is lower than that of special transformers, for example, the price of ordinary transformers in the market is generally 200~600 yuan, and the price of Abach, a famous special power supplier, has exceeded 2,000 yuan, but the German bioclimatic super plasma tube supporting special transformers adopted by our company have been included in the plasma tube group on the premise of "quality reaching Abach and more affordable price", realizing one-time investment and lifelong benefit.
Introduction of effective methods for waste gas treatment?
√ Hello, landlord, according to your question, here are your detailed answers:
Biodecomposition method
According to the invention, the pollutants in the gas are contained in the water by using the circulating water flow, and then the microorganisms are cultured by using the underwater culture bed to degrade the pollutants, so that the odor can be effectively deodorized.
active carbon adsorption
Using the structural principle of adsorption of malodorous gas molecules by activated carbon, the initial treatment efficiency is relatively high, but this industrial waste gas treatment method also has certain limitations. Because activated carbon is extremely saturated, it will fail in a few days and needs to be replaced frequently, so the maintenance cost is high.
Plasma method
Manufacturers of environmental protection equipment use high-voltage electrodes to emit ions and electrons, destroy the structure of malodorous molecules and crack them. This method is mainly suitable for the purification of low concentration malodorous gas, and the treatment effect is obvious.
Activated carbon adsorption
It is an efficient, economical and practical organic waste gas purification and treatment device. It is an environmental protection equipment product for filtering and adsorbing the odor of waste gas. Activated carbon adsorption tower has the advantages of high adsorption efficiency, wide application range and convenient maintenance, and can treat a variety of mixed waste gas at the same time.
I hope this answer will help you!