廢氣主要是NaOH、H2SO4、SO2、H2S、HCl、NO2、HNO3等氣體，按照清潔生產(chǎn)的要求，在處理工藝上，首先考慮將這類物質(zhì)盡可能地凈化處理，要求做到達(dá)標(biāo)排放。

工藝流程的說明：

廢氣由風(fēng)機(jī)引出后，首入酸霧廢氣凈化塔。吸收塔中堿性洗滌液由循環(huán)泵抽至塔中經(jīng)填料向下流動，酸霧廢氣逆流上升，在填料的濕潤表面氣液接觸，發(fā)生一系列的物理化學(xué)反應(yīng)，并由于濃度差而發(fā)生傳質(zhì)過程，從而完成了將氣體的凈化過程，凈化后的廢氣脫水后經(jīng)離心風(fēng)機(jī)引出后達(dá)標(biāo)排放。循環(huán)液定期排放至污水處理站。

工藝流程的系統(tǒng)組成：

本工藝主要由廢氣收集系統(tǒng)、引風(fēng)系統(tǒng)、廢氣凈化系統(tǒng)、排氣系統(tǒng)構(gòu)成。

廢氣收集與管路系統(tǒng)：

廢氣收集和管路系統(tǒng)，主要分為廢氣收集系統(tǒng)、廢氣輸送系統(tǒng)以及應(yīng)急排放和凈化后尾氣排放系統(tǒng)。

對本廢氣治理工程，廢氣有甲方(生產(chǎn)廠家)收集、本工程的廢氣收集直接從甲方收集后的引風(fēng)機(jī)出口連接。

廢氣輸送采用防爆引風(fēng)機(jī)，以克服本系統(tǒng)阻力。風(fēng)機(jī)的壓頭根據(jù)凈化系統(tǒng)的結(jié)構(gòu)進(jìn)行確定。

工藝流程選擇：

針對該單位的廢氣排放所含物質(zhì)，治理方案考慮采用填料噴淋塔進(jìn)行處理。噴淋塔是利用吸收的原理來達(dá)到處理廢氣的目的。

吸收法處理是利用液態(tài)吸收劑處理氣體混合物以除去其中某一種或幾種氣體的過程。在這過程中會發(fā)生某些氣體在溶液中溶解的物理作用，這是物理吸收。也有氣液中化學(xué)物質(zhì)之間發(fā)生化學(xué)反應(yīng)，這是化學(xué)吸收。吸收作用常用于氣體污染物的處理與回收。

吸收法的特點(diǎn)是既能吸收有害氣體，又能除掉排氣中的粉塵，吸收法分為物理吸收和化學(xué)吸收兩種。物理吸收是用液體吸收有害氣體和蒸氣時純物理溶解過程。它適用于在水中溶解度比較大的有害氣體和蒸氣,一般吸收效率較低?；瘜W(xué)吸收是在吸收過程中伴有明顯的化學(xué)反應(yīng),不是純?nèi)芙膺^程。化學(xué)吸收效率較高,是目前應(yīng)用較多的有害氣體處理方法。

本工藝采用的方法就是利用物理與化學(xué)的方法處理廢氣的，化學(xué)吸收過程采用NaOH溶液做吸收劑。

應(yīng)用堿液吸收有害氣體時，堿液濃度的高低對化學(xué)吸收的傳質(zhì)速度有很大的影響。當(dāng)堿液的濃度較低時，化學(xué)傳質(zhì)的速度較低;當(dāng)提高堿液濃度時，傳質(zhì)速度也隨之增大;當(dāng)堿液濃度提高到某一值時，傳質(zhì)速度達(dá)到值，此時堿液的濃度稱為臨界濃度;當(dāng)堿液濃度高于臨界濃度時傳質(zhì)速度并不增大。

酸霧凈化塔凈化原理：

(1)吸風(fēng)罩--進(jìn)風(fēng)管道--風(fēng)機(jī)(或進(jìn)風(fēng)段)--進(jìn)風(fēng)段段濾料層(級中和反應(yīng)段)--第二級濾料層(第二級中和反應(yīng)段)旋流板--出風(fēng)帽蓋--排風(fēng)管(或吸入段風(fēng)機(jī))

(2)酸霧凈化塔工作原理：酸霧凈化塔采用氫氧化鈉溶液為吸收中和液來凈化酸霧廢氣。氣體由離心通風(fēng)機(jī)壓入或吸入進(jìn)風(fēng)段，再向上流動，至濾料層，與級噴咀噴出的中和液接觸反應(yīng)。吸收后的廢氣繼續(xù)向上流動至第二濾料層，與第二級噴咀噴出的中和液接觸，再次發(fā)生中和反應(yīng)，然后通過旋流板，由風(fēng)帽和排風(fēng)管或風(fēng)機(jī)排入大氣中。

酸霧凈化塔的特點(diǎn)：

聚丙烯酸霧凈化塔具有效率高、耐腐蝕性強(qiáng)，高強(qiáng)度、低噪聲、耗電省、體積小，拆裝維修方便，輕巧耐用，外形美觀大方等優(yōu)點(diǎn).

目前國內(nèi)對于腐蝕性氣體(如酸、堿性廢氣)的治理，采用最多的就是液體吸收法治理。采用液體吸收法治理該廢氣，關(guān)鍵在于酸霧凈化塔的選擇。

酸霧凈化塔具有凈化效率高、操作管理簡單、使用壽命長的酸、堿性廢氣凈化工藝與設(shè)備。它具有結(jié)構(gòu)簡單、能耗低、凈化效率高和適用范圍廣的特點(diǎn)，能有效去除氣體(HCl)、硝酸氣體(HNO3)、氟化氫氣體(HF)、氨氣(NH3)、硫酸霧(H2SO4)、鉻酸(CrO3)、氰氫酸氣體(HCN)、堿蒸氣(NaOH)、硫化氫氣體(H2S)、等水溶性氣體。采用氫氧化鈉為吸收中和液，溶液濃度為8%-16%。

酸霧廢氣由風(fēng)管引入凈化塔，經(jīng)過填料層，廢氣與氫氧化鈉吸收液進(jìn)行氣液兩相充分接觸吸收中和反應(yīng)，酸霧廢氣經(jīng)過酸霧凈化塔凈化后，再經(jīng)除霧板脫水除霧后由風(fēng)機(jī)排入大氣。吸收液在塔底經(jīng)水泵增壓后在塔頂噴淋而下，最后回流至塔底循環(huán)使用。

   Exhaust gas mainly NaOH, H2SO4, SO2, H2S, HCl, NO2, HNO3 and other gases, in accordance with the requirements of clean production in the treatment process, first consider the substance of such purification treatment possible is required to meet emissions standards.

Process description:

    After the exhaust fan leads from the first into the exhaust gas purification tower mist. Absorber alkaline washing solution is pumped by the circulation pump to the column by packing flows down countercurrent gas mist rise in the gas-liquid filler wetted surface contact, a series of physical and chemical reactions, and due to the concentration difference occurs Biography transfer process, thereby completing the purge process gas, the exhaust gas after dehydration purified by centrifugation extraction fan discharge. Circulating fluid periodically discharged to sewage treatment station.

Process system components:

    This process consists of the exhaust gas collection systems, the wind system, exhaust gas purification system, exhaust system structure.

Gas gathering and pipeline system:

    Gas gathering and pipeline systems, mainly divided into the exhaust gas collection systems, exhaust systems, and post-emergency transport emissions and clean exhaust emission systems.

Of the emission control projects, there are exhaust Party (manufacturer) collection, gas collection and this project is directly connected from the lead after the fan outlet Party collection.

Gas explosion-proof transport induced draft fan to overcome the system resistance. Fan pressure head determined according to the structure of the purification system.

Process selection:

    Substances contained in exhaust emissions for the unit, consider packing governance programs spray tower for processing. Spray tower using the principle of absorption to achieve the purpose of treating exhaust.

    Absorption process using a liquid absorbent process gas mixture to remove one or a few gas process. Some physical effects in the gas dissolved in the solution will occur in this process, which is physical absorption. There is also a chemical reaction between the gas and liquid chemicals, which is chemical absorption. Absorption of gaseous pollutants commonly used in the treatment and recycling.

    Absorption of law not only absorb harmful gases, but also to get rid of the dust in the exhaust gas, absorption into physical absorption and chemical absorption of two kinds. Purely physical process of dissolution is the physical absorption liquid absorbs harmful gases and vapors. It is suitable for relatively large solubility in water of harmful gases and vapors, generally lower absorption efficiency. Chemical absorption is associated with significant chemical reaction in the absorption process, it is not a pure dissolution process. High chemical absorption efficiency, is the application of more harmful gas treatment.

   The method used in this process is the use of physical and chemical methods of waste gas treatment, chemical absorption process using NaOH solution as absorbent.

   The application of lye absorb harmful gases, alkali concentration level has a great influence on the absorption of chemical mass transfer rate. When a lower concentration of lye, chemical mass transfer speed is low; when the alkali concentration increase, the mass transfer rate also increases; when the alkali concentration is increased to a certain value, the maximum rate of mass transfer in this case the concentration of lye called the critical density; mass transfer rate does not increase when the alkali concentration above the critical concentration.

Mist purification tower purification principle:

(1) suction hood - inlet pipe - fan (or inlet section) - the first paragraph of section inlet filter layer (first stage reaction section) - the second stage filter layer ( and two in the reaction zone) cyclone - a hood cover - exhaust pipe (or suction fan section)

(2) mist purification tower works: mist purification tower sodium hydroxide solution to absorb the liquid and to purify exhaust fumes. Gas by the centrifugal fan pressed or sucked into the wind section, and then flows upward to the first filter layer, and the first stage nozzle and sprayed liquid contact reaction. After absorbing the exhaust gas continues to flow upward to the second filter layer, and in contact with the second stage nozzle fluid ejected, and the reaction from happening again, then swirl plate from the hood and into the exhaust pipe or fan atmosphere.

Mist purification tower Features:

    Polypropylene acid mist purification tower with high efficiency, corrosion resistance, high strength, low noise, low power consumption, small size, easy disassembly and maintenance, lightweight and durable, elegant appearance and so on.

    At present, the corrosive gases (such as acids, alkaline gas) governance, using the most is the liquid absorption method of governance. The exhaust gas treatment by liquid absorption, the key is to select mist purification tower.

   Mist purification tower has a high purification efficiency, operation and management simple, long life acid and alkaline exhaust gas purification technology and equipment. It has a simple structure, low energy consumption, high purification efficiency and a wide range of features, can effectively remove hydrogen chloride gas (HCl), nitric acid gas (HNO3), hydrogen fluoride gas (HF), ammonia (NH3), sulfuric acid mist (H2SO4 ), chromic acid (CrO3), hydrogen cyanide gas (HCN), alkali vapor (NaOH), hydrogen sulfide (H2S), water-soluble gases. Sodium hydroxide to absorb the liquid, solution concentration and 8% -16%.

   Mist exhaust pipe introduced by the wind purification tower, after packing layer, the exhaust gas and absorbing liquid sodium hydroxide liquid two-phase full access to absorption and reaction, acid mist exhaust gas after purification tower mist purification, and then by dehydration defogging board after demisting by the fan into the atmosphere. After absorbing liquid pump pressurized overhead spray down the bottom, and finally back to the bottoms recycle.