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VOCs废气处理技术中三剑客
2020-04-21 11:22:48 shuanhe

VOCs废气处理技术中三剑客

催化燃烧废气处理装置

主要是利用焚烧炉在催化剂的作用下将有机废气进行燃烧或氧化转化为水和CO2,适用于漆包线、机械、电机、化工、仪表、汽车、发动机、塑料、电器等行业的有机废气净化。

催化燃烧由于起燃温度低,是一种较为理想的通过催化反应(无明火)处理有机污染物的方法,具有适用范围广、结构简单、净化效率高、节能、无二次污染等优点,已在国内外得到了广泛应用。我公司研发的催化燃烧净化装置具有操作简单、自动化程序高、能有效地处理各种有机废气污染物,处理浓度<=10g/m3,深受广大客户的欢迎。催化燃烧处理技术结构及原理:催化燃烧净化装置主要由阻火器、热交换器、催化反应床、风机这几个主要部件组成,与直接燃烧相比,催化燃烧温度较低,燃烧比较完全。催化燃烧所用的催化剂为具有大比表面的贵金属和金属氧化物。催化燃烧法是将有机污染物的废气、催化剂在催化剂铂、钯等催化剂的作用下,可以在较低温度下将废气中的有机污染物氧化成二氧化碳和水。

废气经阻火器过滤后,通过主进阀、旁通阀的同步反向切换调节进入热交换器,热交换器的热气升高一定温度后进入预热室、经过预热室的加热使废气升温到催化起燃温度(250度)然后进入催化反应床,在催化剂的活性作用下,有机废气进行氧化反应生成无害的水和二氧化碳,并放出一定的热量。反应后的高温气体再次进入热交换器,经换热后,最后以较低的温度经引风机排入大气。催化燃烧是借助催化剂在低温下(200-400度)实现对有机物的完全氧化,因此,操作简单、安全、净化效率高,在有机废气特别是回收价值大的有机废气净化等领域应用广泛。

不同的排放场所和不同的废气,有不同的催化燃烧废气处理工艺流程。但无论采取哪种工艺流程,都由如下工艺单元组成:

废气预处理---预热装置---催化燃烧装置。

催化燃烧性能特点

1、用优质金属铂、钯镀在蜂窝陶瓷载体上作为催化剂、净化效率高达97-99%,设备寿命长、且可再生、气体流淌阻力小;

2、安全设施完备:阻火除尘器、泄压孔、超温报警等保护设施齐全;

3、预热15-30分钟全功率加热。工作时只消耗电机功率即可,当废气浓度较低时,自动间歇补偿加热;

4、余热可以返回烘道用来烘干工作,降低原烘道中消耗功率;也可供工厂其它方面热能回用

催化燃烧处理注意事项

1、废气成分中,不能含有下列物质;有高粘性的油脂类。如磷、铋、砷、锑、汞、铅、锡;高浓度的粉尘;

2、设备选型时,注明废气的成分、浓度及出口温度;

3、设备安装场所无腐蚀性气体,并有良好的防雨措施;

4、设备所需电源为:三相交流380V频率50Hz;

催化燃烧适用范围

1、用于有机溶剂的净化处理如:苯类、醇类、酯类、酚类、醚类、烷类等混合性有机废气;

2、适用于漆包线、机械、电机、化工、仪表、汽车、发动机、塑料、电器等行业的有机废气净化;

3、适用于各种烘道、印刷油墨、电机绝缘处理等烘干流水线等。

低温等离子废气处理设备的技术机理

等离子体去除恶臭是通过两个途径实现的:一个是在高能电子的瞬间是高能量作用下,打开某些有害气体分子的化学键,使其直接分解成单质原子或无害分子;另一个是在大量高能电子、离子、激发态粒子和氧自由基、氢氧自由基(自由基因带有不成对电子而具有很强的活性)等作用下的氧化分解成无害产物。主要有下面几个过程:

1、在高能电子作用下,强氧化性自由基O、OH、OH2的产生;

2、有机物分子受到高能电子碰撞被激发,及原子键断裂形成小碎片基团和原子;

3、O、OH、HO2与激发原子、有机物分子、废气处理公司破碎的基团、其他自由基等发生一系列反应,有机物分子最终被氧化降解为CO、CO2、H2O。去除率的高低与电子能量和有机物分子结合键能的大小有关。

从除臭机理上分析,主要发生以下反应:

H2O+O2、O2-、O2+——SO3+H2O

NH3+O2、O2-、O2+——NOx+H2O

H2S去除率可达91.9%,NH3去除率可达93.4%,臭气浓度去除率可达93.6%。

从上述反应来看,恶臭组分经过处理后,转变为NOx、SO2、CO2、H2O等小分子,在一定的浓度下,各种反应的转化率均在95%以上,而且恶臭浓度较低,因此产物的浓度极低,均能被周边的大气所接受。

吸附法已广泛应用于净化室内空气、大气污染治理、石油化工等领域VOCs的回收处理。它分为固定床吸附法、流动床吸附法和浓缩轮吸附法。其原理是利用具有密集的细孔结构、内表面积比较大的粒状活性炭、炭纤维、硅胶、人工沸石等吸附剂的多孔结构,将VOCs组分吸附在固体表面,利用吸附剂不断吸附、脱附的循环,达到净化回收目的。研究表明,活性炭吸附VOCs性能最佳。吸附剂吸附VOCs的效果除与吸附剂本身性质有关外还与VOCs的种类、浓度、性质以及吸附系统的温度、压力有关,一般来说吸附剂对VOCs的吸附能力随气体分子量的增加而增加,低分压的气体比高分压气体更易吸附。

吸附法适用于中低浓度、高通量VOCs的回收,它具有去除效率高、净化彻底、能耗低、工艺成熟、易于推广使用等优点,表现出良好的环境和经济效益。缺点是吸附剂的容量小,需要的吸附剂量大,设备庞大;吸附后的吸附剂不仅需要定期再生处理和更换,而且在此过程中,VOCs有散逸的风险;由于全过程的复杂性,费用相对较高。

活性炭纤维是以有机化合物纤维(如聚丙烯、酚醛树脂、聚乙烯醇等)为基本原料经特殊加工制成的。它是一种很细的纤维状物质,具有巨大的比表面积、外表面积和非常发达的微孔结构,纤维上有很多微孔可以直接与有机物接触而不是像颗粒活性炭那样要先通过大孔、过渡孔,才能到达微孔,因此,活性炭纤维更易于吸附低浓度的VOCs。与颗粒活性炭相比,其吸附有机物的能力高出115~210倍,吸附速度也快3倍左右。由于活性炭纤维的吸附能力强,故吸附装置可以小型化,吸附剂的用量也可以少些,降低处理费用。活性炭纤维VOCs回收装置以活性炭纤维(ACF)作为吸收剂,处理各类工厂或设备排放的含有有机溶剂(VOCs)的废气,将其中的VOCs变成液体进行分离,并进行回收再利用。

活性炭吸附箱在处理废气过程中相对较安全,适用范围也很广,多数用在化工厂,塑料厂,医药厂,喷漆房等。

活性炭吸附箱原理

由于活性炭吸附剂表面上存在着未平衡和未饱和的分子引力或化学键力,当废气由风机提供动力,负压进入吸附箱后进入活性炭吸附层,因此当活性炭吸附剂的表面与气体接触时,就能吸引气体分子,使其浓聚并保持在活性炭表面,此现象称为吸附。利用活性炭吸附剂表面的吸附能力,使废气与大气表面的多孔性活性炭吸附剂相接触,废气中的污染物被吸附在活性炭表面上,使其与气体混合物分离,净化后的气体高空排放。活性炭吸附箱是一种干式废气处理设备,由箱体和填装在箱体内的吸附单元组成。

活性炭吸附箱性能特点:

1、全密闭型,室内外皆可使用。

2、吸附效率高,能力强;

3、采用自动化控制运转设计,操作简易、安全;

4、能够同时处理多种混合有机废气;净化效率≥95%;

5、设备构造紧凑,占地面积小,维护管理简单,运转成本低廉;

Incinerator is mainly used to burn or oxidize the organic waste gas to water and CO2 under the action of catalyst. It is suitable for purifying the organic waste gas of enameled wire, machinery, motor, chemical industry, instrument, automobile, engine, plastic, electric appliance and so on.
Catalytic combustion is an ideal method for treating organic pollutants through catalytic reaction (no open flame) due to its low light-off temperature. It has the advantages of wide application range, simple structure, high purification efficiency, energy saving and no secondary pollution, etc., and has been widely used at home and abroad. Our catalytic combustion purification unit is easy to operate, highly automated, and can effectively treat all kinds of organic waste gas pollutants with concentration < = 10g/m3, which is well received by customers. Structure and Principle of Catalytic Combustion Treatment Technology: Catalytic Combustion Purification Unit is mainly composed of flame arrester, heat exchanger, catalytic reaction bed and fan. The catalysts used for catalytic combustion are noble metals and metal oxides with high specific surface area. The catalytic combustion process is to oxidize the organic pollutants into carbon dioxide and water under the action of the catalysts such as platinum and palladium.
After the waste gas is filtered by the flame arrester, it enters the heat exchanger through the synchronous reverse switching regulation of the main inlet valve and the bypass valve, and the hot gas of the heat exchanger rises to a certain temperature and then enters the preheating chamber, through the heating of the preheating chamber, the waste gas is heated to the catalytic ignition temperature (250 degrees) and then enters the catalytic reaction bed. Under the active action of the catalyst, the organic waste gas carries out oxidation reaction to produce harmless water and carbon dioxide, and gives off certain heat. After the reaction, the high temperature gas enters the heat exchanger again. After heat exchange, it is discharged into the atmosphere by the induced draft fan at a lower temperature. Catalytic combustion is a complete oxidation of organic matter with catalyst at low temperature (200-400 ℃). Therefore, it is easy to operate, safe and efficient to purify the organic waste gas.
Different emission sites and different waste gas, there are different catalytic combustion of waste gas treatment process. However, whichever process is adopted, it consists of the following process units:
Waste Gas Pretreatment - Preheating Unit - Catalytic Combustion Unit.
Characteristics of catalytic combustion
1、 Using high-quality platinum and palladium plating on honeycomb ceramic carrier as catalyst, the purification efficiency is up to 97-99%, the equipment has long service life, can be regenerated and the gas flow resistance is small;
2、 Complete safety facilities: complete fire and dust remover, pressure relief holes, over-temperature alarm and other protection facilities;
3、 Preheating 15- 30 minutes full power heating. Only the power of motor is consumed when working. When the concentration of waste gas is low, automatic intermittent compensation heating;
4、 The waste heat can be returned to the drying path for drying work to reduce the power consumption in the original drying path; it can also be used for the reuse of heat energy in other aspects of the factory.
Considerations for catalytic combustion treatment
1、 Waste gas components shall not contain the following substances; there shall be oils and fats with high viscosity. Such as phosphorus, bismuth, arsenic, antimony, mercury, lead, tin; high concentration of dust;
2、 When selecting equipment, the composition, concentration and outlet temperature of waste gas shall be indicated;
3、 The installation place of equipment shall be free from corrosive gas, and shall have good rainproof measures;
4、 The power supply required by the equipment shall be: 380v frequency of three-phase AC 50Hz;
Range of catalytic combustion
1、 Purification treatment of organic solvents such as mixed organic waste gas such as benzene, alcohol, ester, phenol, ether, alkane, etc.;
2、 It is applicable to the purification of organic waste gas in enameled wires, machinery, motors, chemicals, meters, automobiles, engines, plastics, electrical appliances and other industries;
3、 Applicable to all kinds of drying lines, printing ink, motor insulation processing and other drying lines.
Technical mechanism of low-temperature plasma waste gas treatment equipment:
Plasma deodorization is achieved through two ways: one is to open the chemical bonds of some harmful gas molecules under the action of high-energy electrons at the moment of high-energy electrons, so that they can be directly decomposed into simple atoms or harmless molecules; the other is to be decomposed into harmless products by oxidation under the action of a large number of high-energy electrons, ions, excited particles and oxygen free radicals, hydroxyl free radicals (free genes with unpaired electrons and strong activity). The main processes are as follows:
1、 Generation of strong oxidative free radicals O, OH and OH2 under the action of high-energy electrons;
2、 Organic molecules are excited by high-energy electron collisions and the atomic bonds are broken to form small fragmented groups and atoms;
3、 O、 OH、 HO2 react with excited atoms, organic molecules, broken groups of waste gas treatment companies and other free radicals, and organic molecules are oxidized and degraded to CO、 CO2、 H2O. The removal rate is related to the electron energy and the binding bond energy of organic molecules.
According to the analysis of deodorization mechanism, the following reactions mainly occur:
H2O O2, O2 -, O2 + - SO3 + H2O
NH3 O2, O2 -, O2 + - - NOx + H2O
The removal rates of H2S, NH3 and odor were 91.9%, 93.4% and 93.6%, respectively.
In a certain concentration, the conversion rate of each reaction is above 95%, and the concentration of malodor is lower. Therefore, the concentration of the product is very low, and can be accepted by the surrounding atmosphere.
Adsorption method has been widely used in purification of indoor air, air pollution treatment, petrochemical and other fields VOCs recovery treatment. It can be divided into fixed bed adsorption method, mobile bed adsorption method and concentration wheel adsorption method. The principle is to use the porous structure of granular activated carbon, carbon fiber, silica gel, artificial zeolite and other adsorbents with dense fine pore structure and large internal surface area to adsorb the VOCs components on the solid surface, and to achieve the goal of purification and recovery by the continuous adsorption and desorption of adsorbents. The results showed that the adsorption of VOCs by activated carbon was the best. In general, the adsorption capacity of adsorbent to VOCs increases with the increase of the molecular weight of the gas, and the gas with low pressure is easier to be adsorbed than that with high pressure.
Adsorption method is suitable for the recovery of low concentration and high flux VOCs. It has the advantages of high removal efficiency, complete purification, low energy consumption, mature process and easy to popularize. The disadvantage is that the capacity of the adsorbent is small, the adsorption dose needed is large, and the equipment is large. The adsorbent after adsorption not only needs to be regenerated and replaced regularly, but also in the process,



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