废气行业酸雾废气处理方案

       废气主要是NaOH、H2SO4、SO2、H2S、HCl、NO2、HNO3等气体，按照清洁生产的要求，在处理工艺上，首先考虑将这类物质尽可能地净化处理，要求做到达标排放。

工艺流程的说明：

废气由风机引出后，首先进入酸雾废气净化塔。吸收塔中碱性洗涤液由循环泵抽至塔中经填料向下流动，酸雾废气逆流上升，在填料的湿润表面气液接触，发生一系列的物理化学反应，并由于浓度差而发生传质过程，从而完成了将气体的净化过程，净化后的废气脱水后经离心风机引出后达标排放。循环液定期排放至污水处理站。

工艺流程的系统组成：

本工艺主要由废气收集系统、引风系统、废气净化系统、排气系统构成。

废气收集与管路系统：

废气收集和管路系统，主要分为废气收集系统、废气输送系统以及应急排放和净化后尾气排放系统。

对本废气治理工程，废气有甲方(生产厂家)收集、本工程的废气收集直接从甲方收集后的引风机出口连接。

废气输送采用防爆引风机，以克服本系统阻力。风机的压头根据净化系统的结构进行确定。

工艺流程选择：

针对该单位的废气排放所含物质，治理方案考虑采用填料喷淋塔进行处理。喷淋塔是利用吸收的原理来达到处理废气的目的。

吸收法处理是利用液态吸收剂处理气体混合物以除去其中某一种或几种气体的过程。在这过程中会发生某些气体在溶液中溶解的物理作用，这是物理吸收。也有气液中化学物质之间发生化学反应，这是化学吸收。吸收作用常用于气体污染物的处理与回收。

吸收法的特点是既能吸收有害气体，又能除掉排气中的粉尘，吸收法分为物理吸收和化学吸收两种。物理吸收是用液体吸收有害气体和蒸气时纯物理溶解过程。它适用于在水中溶解度比较大的有害气体和蒸气,一般吸收效率较低。化学吸收是在吸收过程中伴有明显的化学反应,不是纯溶解过程。化学吸收效率较高,是目前应用较多的有害气体处理方法。

本工艺采用的方法就是利用物理与化学的方法处理废气的，化学吸收过程采用NaOH溶液做吸收剂。

应用碱液吸收有害气体时，碱液浓度的高低对化学吸收的传质速度有很大的影响。当碱液的浓度较低时，化学传质的速度较低;当提高碱液浓度时，传质速度也随之增大;当碱液浓度提高到某一值时，传质速度达到最大值，此时碱液的浓度称为临界浓度;当碱液浓度高于临界浓度时传质速度并不增大。

酸雾净化塔净化原理：

(1)吸风罩--进风管道--风机(或进风段)--进风段第一段滤料层(第一级中和反应段)--第二级滤料层(第二级中和反应段)旋流板--出风帽盖--排风管(或吸入段风机)

(2)酸雾净化塔工作原理：酸雾净化塔采用氢氧化钠溶液为吸收中和液来净化酸雾废气。气体由离心通风机压入或吸入进风段，再向上流动，至第一滤料层，与第一级喷咀喷出的中和液接触反应。吸收后的废气继续向上流动至第二滤料层，与第二级喷咀喷出的中和液接触，再次发生中和反应，然后通过旋流板，由风帽和排风管或风机排入大气中。

酸雾净化塔的特点：

聚丙烯酸雾净化塔具有效率高、耐腐蚀性强，高强度、低噪声、耗电省、体积小，拆装维修方便，轻巧耐用，外形美观大方等优点.

目前国内对于腐蚀性气体(如酸、碱性废气)的治理，采用最多的就是液体吸收法治理。采用液体吸收法治理该废气，关键在于酸雾净化塔的选择。

酸雾净化塔具有净化效率高、操作管理简单、使用寿命长的酸、碱性废气净化工艺与设备。它具有结构简单、能耗低、净化效率高和适用范围广的特点，能有效去除氯化氢气体(HCl)、硝酸气体(HNO3)、氟化氢气体(HF)、氨气(NH3)、硫酸雾(H2SO4)、铬酸(CrO3)、氰氢酸气体(HCN)、碱蒸气(NaOH)、硫化氢气体(H2S)、等水溶性气体。采用氢氧化钠为吸收中和液，溶液浓度为8%-16%。

酸雾废气由风管引入净化塔，经过填料层，废气与氢氧化钠吸收液进行气液两相充分接触吸收中和反应，酸雾废气经过酸雾净化塔净化后，再经除雾板脱水除雾后由风机排入大气。吸收液在塔底经水泵增压后在塔顶喷淋而下，最后回流至塔底循环使用。

   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.