脱硫岛

0.1 Plant description脱硫岛介绍The FGD plant consists of flue gas path, which includes the absorber vessel, booster fan, GGH and bypass dampers, which ensure the operation of the boiler in two modes – FGD operation and a bypass operation. Limestone slurry preparat ion system gets ready the absorbent needed in the process. The only by-product is gypsum slurry, which is transported to the dewatering system consisting prim ary and secondary dewatering stages. Gypsum, as a byproduct of dewatering is te mporary storied for further use and water is partly led back to the process, pa rtly to the waste water treatment.脱硫岛包括烟气系统、石灰浆液制备系统、石膏浆液脱水系统、石膏库和废水处理等。

在烟气系统中包括吸收塔、升压风机和旁路档板，旁路档板的作用是它能够满足锅炉在两种模式下运行，一是在脱硫岛在线，二是脱硫岛旁路。

石灰浆液制备系统的功能是准备工艺流程中所需的吸收剂。

反应后生成的唯一的辅产品是石膏浆液，石膏浆液分别经过一级脱水和二级脱水，经过脱水产生的辅产品是石膏被临时储存起来为以后用，脱出的水一部分返回系统中，而另一部分被送到废水处理站。

0.1.1 Absorber system吸收塔系统A wet limestone process with forced oxidation with the SO2 absorber system is used to remove flue gas SO2 and to produce a gypsum by-product. SO2 removal efficiency of 96% is reached for all specified boiler loads and scope of the fu els.The absorber utilizes a perforated scrubber tray and four absorber spray le vels for SO2 removal, which are above the absorber tray. The absorber recircula tion pumps feed separately each header when operating.在吸收塔中，湿石灰石与氧化风机鼓送的氧气和吸收塔中的二氧化硫发生反应，达到了除掉烟气中的二氧化硫的目的，并且产生了唯一的辅产品石膏。

在指定的所有锅炉负荷和燃料范围内，二氧化硫除去率能达到96%。

吸收塔装备有穿孔的托盘和四个喷淋层。

为了便于二氧化硫的去除，喷淋层都安装在托盘的上方。

在运行时，吸收塔浆液循环泵分别为每一个联箱提供浆液。

The SO2 removal process starts as the hot flue gas entering the absorber is cooled and saturated by the slurry falling from the absorption zone. The flue gas then flows through the absorber tray. The absorber tray helps the re-distri bution of the flue gas to optimize the contact between the gas and the absorber. As the gas passes through the layer of scrubber slurry on the tray, the increa sed gas velocity, caused by tray perforations, generates a violent frothing act ion, thereby assuring spray zones, where absorber slurry spraying counter curre nt to the flue gas flow completes the sulphur dioxide removal process.当热烟气进入吸收塔被冷却，被从吸收剂区落下的浆液渗透时，去除二氧化硫的工艺开始了。

烟气进入吸收塔之后再流过托盘，托盘的作用是使流过它的烟气重新分配而达到优化烟气与吸收剂接触的目的。

当烟气流过托盘时，托盘上的孔使烟气加速，并且同时产生强烈的泡沫，这样就使托盘上的浆液和喷射区的浆液逆流到烟气流，从而完成了去除二氧化硫的工艺。

The gas flows then upwards the first stage mist eliminator (ME) located nea r the top of the absorber. Above and below the first stage ME are a series of h eaders with spray nozzles that spray process water onto the first stage of mist eliminator. These sprays keep the surface of the ME wet and wash away slurry s olids reaching the ME. After passing through the first stage ME, the gas then e nters the second stage ME. Another series of headers with spray nozzles are loc ated below the second stage ME. After passing through the second stage ME, the flue gas exits the scrubber through the outlet hood.烟气流经托盘后，继续往上流向第一级除雾器，第一级除雾器靠近吸收塔顶部。

在第一级除雾器的上面和下面是一系列带有喷嘴的联箱，这些喷嘴喷射出的工艺水喷溅到第一级除雾器，使除雾器的表面保持潮湿且同时冲洗掉粘附在上面的浆液。

当烟气通过第一级除雾器后，流向第二级除雾器，在第二级除雾器的下面也有一系列带有喷嘴的联箱。

经过第二级除雾器后，烟气通过出口罩排出吸收塔。

The absorber slurry and ME wash water pass down through the absorber and is collected in the lower section of the absorber, which is referred to as the ab sorber reaction tank. Four side entering agitators on absorber reaction tank ke ep the absorber slurry solids in suspension. The absorber reaction tank is supp lied with a absorber overflow that is designed to protect the absorber and the absorber inlet flour work from flooding and a seal box to prevent the flue gas from escaping through the overflow.石灰浆液和除雾器的冲洗水从上而下地通过吸收塔，最后汇集到吸收塔底部的吸收塔反应箱。

在吸收塔反应箱装有四个搅拌器，使石灰浆液保持悬浮状。

吸收塔反应箱带有溢流管和密封箱，溢流管的作用是为了保护吸收塔以防止它过满而产生满溢，密封箱作用是为了防止烟气从溢流管中渗出。

Absorber slurry pH is controlled by the addition of fresh limestone slurry to the absorber. The amount of the limestone slurry added to the scrubber to ma intain a given pH is a function of boiler load and sulphur dioxide loading. The slurry pH in the reaction tank is a function of the excess limestone in the la nk, the sulphur dioxide removed and a solid residence time in the absorber reac tion tank. Two redundant in-line pH probes are provided in the discharge piping of the gypsum slurry hydro cyclone feed pumps to measure scrubber slurry pH.吸收塔PH值是通过重新添加石灰浆液到吸收塔里来控制的。

为了维持所给定的PH值，加入到吸收塔中的石灰浆液量是由锅炉负荷和二氧化硫负荷共同决定的。

在吸收塔反应箱里的石灰浆液PH值是由在箱里过剩的浆液、被去除的二氧化硫和石灰在反应箱里滞留的时间共同决定的。

另外两个内嵌式PH值探头被安装在石膏浆液泵的出口以测量吸收塔浆液的PH值。

As the hot inlet flue gas is quenched, water is evaporated and carried out of the absorber. In addition, the sulphur dioxide removal process forms solid p roducts. These two processes result in an increase of absorber solids content, referred to in the industry as, slurry density. Absorber slurry density is cont rolled by the addition of ME wash water to the absorber. A density meter is loc ated in the gypsum slurry hydro cyclone feed pump discharge pipeline measures s crubber slurry density. A signal from the absorber slurry density meter opens o r closes the absorber density control valve.当热烟气被淋湿时，水被蒸发并且被带出吸收塔。