Production Description

The mist tubular eliminator on the first layer removes coarse particle fog drops and the weir type mist eliminator on the second layer removes fine particle fog drops.

Flushing system

Flushing system including: nozzle, pipeline, pipe clamp, etc.

Water pipe of mist eliminator is made by anti-corrosive carbon steel or stainless steel and the nozzle is made of 316L. The layout form of flushing pipe is the top and bottom side of the first-degree mist eliminator and bottom side of the second-degree mist eliminator. 200% flushing water spray overlap rate ensures demister run with low resistance. Critical separation size of weir type mist eliminator: 15-30um for second level, 20-30um for first level.

Advantages

The advantage of weir type mist eliminator is that the velocity of flue gas passing through the normal of blade is smaller than the average velocity when passing through horizontal cross-section in tower. In this way, even if the velocity of flue gas in tower flow is high, it decreases when passing through the mist eliminator as the flow area increases. Weir type mist eliminator needs a rectangular channel on the surface of the cross section in absorption tower. However, the absorption tower is round, so part of it requires to be sealed with blind ram to set off a part of the edge. In addition, the structure of wire type mist eliminator is more stable than that of flat type mist eliminator. It can stand higher temperature, therefore, it is recommended when the desulphurization system is not on GGH setting. The general height of weir type mist eliminator with single beam is 2850mm while that of two-stage plate type mist eliminator is 3230mm, namely, weir type mist eliminator with single beam occupies little space. However, considering decreasing the amount of water, it is usually required that the flue gas changes flow direction and improves the flow velocity at 1m above the blade of mist eliminator. In this way, big particles can fall back on the mist eliminator. If adding this 1 m of reserved space, weir type and plate type mist eliminator occupies similar total space.

Operating Principle

Flue gas separates droplets away under the action of inertia force and gravity when passing bending channel of the mist eliminator. Then desulfurized flue gas flows through mist eliminator in a certain speed and changes running direction quickly and continuously. Droplets in the flue gas are captured while crashing into mist eliminator blades under the action of centrifugal force and inertial force. They gather and form into a stream and then drop back to the slurry pool under gravity. Finally gas and liquid are separated, and the flue gas which flows through mist eliminator is discharged after meeting the standard of mist removal. Demisting efficiency of mist eliminator increases as the air velocity gets higher. The high flow velocity and the large inertia force acting on the droplets are conducive to the separation of gas and liquid. However, flow velocity improvement will increase system resistance and energy consumption. The increase of flow velocity has certain limits, because over-high flow velocity will bring water. It may reduce demisting efficiency. The highest flow velocity of flue gas with no secondary water when passing through the cross-section of mist eliminator is always defined as the critical flow velocity. The velocity has relation with the structure of mist eliminator, the water load of system, flow direction, arrangement form of mist eliminator and other factors.