渣浆泵脱硫烟气档板的概述
  一、概述
  为了保证FGD的停运，不影响发电机组的正常运行，在烟道上分别设置了原烟气挡板门、净烟气挡板门和旁路烟气挡板门。烟气挡板门一般采用双百叶窗形式。其作用主要是隔离设备、控制烟气流量和排空烟气。
    原烟气挡板门设在增压风机之前，在启动FGD时开启，FGD停运时关闭:旁路挡板门设在烟囱之前的净烟道和原烟道之间，在启动FGD时，旁路挡板关闭，将烟气切换至脱硫系统。FGD停止或故障状态时快速开启。
    脱硫系统故障时，为了保证锅炉机组风烟系统的正常运行，三个挡板门设连锁保护。当FGD装置运行时，烟道旁路挡板门关闭；FGD装置停运时，旁路门打开，FGD装置进出口挡板门关闭，烟气通过旁路挡板门进入烟囱，由烟囱直接排入大气。在调试中，旁路挡板一般要放在微开位置。
  二、烟气挡板门
    通常，由于对隔离挡板和烟气流量控制挡板有不同的运行要求。FGD装置的烟气挡板有单百叶窗式、双百叶窗式和闸板门三种类型。
  1.百叶窗挡板门
  百叶窗挡板门有单百叶窗和双百叶窗两种类型，由本体、一系列平行的叶片、轴密封、驱动机构和控制部分构成，如图4-10和图4-11所示。

百叶窗挡板门的叶片通过外部联动机构连接在一起，多数情况下由一个电动机来驱动所有叶片旋转。也有的将百叶窗式旁路挡板门的叶片分成2-3组，分别由2-3个执行机构驱动，其目的是在FGD系统启动、关闭旁路挡板时最大限度地降低对护膛压力的影响；在需要快速开启旁路门时，降低所有叶片不能开启的风险。
    百叶窗挡板门的每个叶片的边缘一般都设计有需封条，在挡板门关闭时起叶片之间相互密封作用。门框的密封(他叫侧面密封)布置在叶片两端的门框边缘上，侧面密封是防止烟气从叶片两端泄漏。采用双百叶窗挡板门可以进一步提高密封性能，除了每层挡板上配备密封元件外，在两层挡板门中间还通入密封空气。当双百叶窗挡板门关闭时，两层挡板门中间通入的密封空气，能阻止烟气由挡板门一侧泄漏到另一侧，如图4-11所示。
    挡板密封空气系统包括密封风机、密封风加热器、检测仪表、调节设备及其管路等。一般每套FGD配两台密封风机，2X100%容量，一台运行一台备用。
    入口、出口挡板门的密封空气和旁路挡板门的密封空气不同时运行。不同挡板密封风的切换通过装在挡板门上的阀门来实现，该与挡板门为机械连锁。
    密封空气压力维持比烟气最高压力至少高500-700Pa，因此风机必须设计有是够的容量和压头。
    密封空气加热器有电加热和蒸汽加热两种形式，密封空气加热器加热至100°C有左右，减少与烟气之间的温差，使挡板门的变形控制在允许范围内。

2. 闸板式挡板门  

闸板式挡板门简称闸板门，如图4-12所示，

当闸板从烟道内完全抽出时，烟道全开，当闸板完全落入烟道时，烟道关闭。这是一种零泄漏的挡板门，检修人员在其下游工作，能保障人身安全，
    闸板顺着挡板门框架的内侧插入到周围有空气密封的密封室内。喷入密封室的空气压力要大于烟气侧压力，以防止烟气漏入密封空气室。挡板框架内侧的挡板槽内装有密封薄片，以减少密封空气的用量，当闸板被提升起来时，密封片紧靠在一起。
    挡板在烟道中提升和落下，最常用的方法是在挡板上部两端装有固定的链条，用一个链条驱动装置来提升挡板。根据挡板的尺寸和质量，一般用2~4根链条。另一种提升方法是用齿轮驱动机构沿挡板两侧的齿条提升挡板。
  闸板门和双百叶窗挡板隔断性好，但占据的空间大，造价高。渣浆泵

Overview of FGD baffle plate of slurry pump

I. overview

In order to ensure the shutdown of FGD and not affect the normal operation of the generator set, the original flue gas damper, net flue gas damper and bypass flue gas damper are set on the flue. The flue gas baffle door is generally in the form of double leaf windows. Its main functions are to isolate equipment, control flue gas flow and exhaust flue gas.

The original flue gas damper is set in front of the booster fan, which is opened when the FGD is started and closed when the FGD is stopped: the bypass damper is set between the clean flue and the original flue in front of the chimney. When the FGD is started, the bypass damper is closed to switch the flue gas to the desulfurization system. FGD stop or fast start in fault state.

When the desulfurization system fails, in order to ensure the normal operation of the air and flue gas system of the boiler unit, three damper doors are provided with interlock protection. When FGD device is running, bypass damper valve of flue is closed; when FGD device is stopped, bypass valve is opened, inlet and outlet damper valve of FGD device is closed, flue gas enters chimney through bypass damper valve, and is directly discharged into atmosphere from chimney. During commissioning, the bypass damper shall be generally placed at the slightly open position.

II. Flue gas damper

Generally, there are different operation requirements for the isolation damper and the flue gas flow control damper. There are three types of flue gas damper in FGD device: single shutter type, double shutter type and gate type.

1. Shutter baffle door

There are two types of shutter door: single shutter and double shutter, which are composed of body, a series of parallel blades, shaft seal, driving mechanism and control part, as shown in Fig. 4-10 and Fig. 4-11.

The blades of the shutter door are connected by an external linkage mechanism, and in most cases, all blades are driven by a single motor. In some cases, the blades of the shutter bypass damper door are divided into 2-3 groups, which are driven by 2-3 actuators respectively. The purpose is to minimize the impact on the chamber pressure when the FGD system starts and closes the bypass damper, and reduce the risk that all blades cannot be opened when the bypass valve needs to be opened quickly.

The edge of each blade of the shutter baffle door is generally designed with sealing strip, which plays the role of mutual sealing between blades when the baffle door is closed. The sealing of the door frame (called side sealing) is arranged on the edge of the door frame at both ends of the blade. The side sealing is to prevent the smoke from leaking from both ends of the blade. The sealing performance can be further improved by adopting double shutter baffle doors. In addition to the sealing elements on each baffle, the sealing air is also introduced into the middle of the two baffle doors. When the double shutter baffle door is closed, the sealing air in the middle of the two-layer baffle door can prevent smoke from leaking from one side of the baffle door to the other side, as shown in Figure 4-11.

The baffle seal air system includes seal fan, seal air heater, testing instrument, regulating equipment and pipeline, etc. Generally, each set of FGD is equipped with two seal fans with capacity of 2x100%, one for operation and one for standby.

The sealing air of the inlet and outlet damper doors and the sealing air of the bypass damper doors do not operate at the same time. The switching of different baffle seal air is realized by the valve installed on the baffle door, which is mechanically interlocked with the baffle door.

The seal air pressure is maintained at least 500-700pa higher than the maximum pressure of flue gas, so the fan must be designed with enough capacity and pressure head.

There are two types of sealed air heater: electric heating and steam heating. When the sealed air heater is heated to 100 ° C, the temperature difference between the sealed air heater and the flue gas will be reduced, and the deformation of the baffle door will be controlled within the allowable range.

2. Gate type damper door

Gate type damper door is referred to as gate plate door, as shown in Figure 4-12.

When the ram is fully drawn out from the flue, the flue is fully open, and when the ram is completely dropped into the flue, the flue is closed. This is a kind of zero leakage baffle door. The maintenance personnel can work in its downstream to ensure personal safety.

The ram is inserted along the inner side of the damper door frame into the surrounding airtight seal chamber. The air pressure injected into the seal chamber shall be greater than the pressure at the flue gas side to prevent the flue gas from leaking into the seal air chamber. The baffle groove inside the baffle frame is equipped with sealing sheet to reduce the amount of sealing air. When the ram is lifted, the sealing sheet is close together.

The most common way to lift and lower the baffle in the flue is to install a fixed chain at both ends of the upper baffle, and use a chain drive device to lift the baffle. According to the size and quality of baffle, 2-4 chains are generally used. Another lifting method is to use a gear driving mechanism to lift the baffle along the rack on both sides of the baffle.

Gate and double shutter baffle have good partition, but they occupy a large space and cost a lot. Slurry pump