Mist Elimination

Mist Elimination In any process where gas and liquid come into contact, the gas will entrain some liquid droplets. These mists can cause process inefficiencies, product loss, and serious equipment damage. Entrainment Mechanisms The way that droplets are formed determines the size of droplets to be removed. Knowledge of the mechanisms that cause droplet formation and the resulting droplet size is essential to proper mist eliminator selection and design. Entrainment is generated by one or more of three basic mechanisms: ► Mechanical action ► Chemical reaction ► Condensation Figure 1 illustrates...

Types of Mist Eliminators Almost all mist limination equipment falls into one of four gn驩ral classes: ► Knitted wire mesh pads (DEMISTER® mist eliminators) ► Vane assemblies (FLEXICHEVRON® mist eliminators) ► Fiberbed candles and panels (FLEXIFIBER® mist eliminators) ► Cyclone assemblies DEMISTER® Mist Eliminators When the vessel size is not set by the mist eliminator (such as is normally the case for distillation towers, steam drums, or evaporators), the practical starting point is often the knitted wire mesh pad type. DEMISTER knitted mesh mist eliminators provide high separation efficiency...

Common Applications Knockout Drums Designing knockout drums to include mist eliminators will reduce capital equipment costs and improve efficiency. Knockout drums relying solely on gravity settling remove only drops larger than 100 microns. Using an efficient mist eliminator will prevent entrainment of all drops larger than 5 to 10 microns. This higher efficiency reduces product loss; downstream corrosion; contamination; and damage to equipment such as compressors, molecular sieve driers, and blowers. Vessel weights can easily be reduced to half, and handling of liquid slugs is improved. Evaporators...

Process Applications Process industries use KOCH-OTTO YORK® mist eliminators wherever gas and liquid come into contact. Some of the major process applications are described below. Refineries Mist eliminators in fractionators increase throughput capacity and allow deeper cuts for greater yields. Gas Absorption Systems Designers and operators of systems using glycols, amines and other proprietary solvents to remove water vapor, H2S, CO2 or other contaminants from gas streams often follow equipment specifications that have not been optimized to minimize losses of these expensive chemicals. Losses...

DEMISTER® Mist Eliminators The DEMISTER® mist eliminator is an assembly of YORKMESH knitted mesh that is supported with high open area grids. DEMISTER mist eliminators are made to any size and shape from a wide range of materials, both metal and non-metal. Stainless steels and exotic alloys are fully annealed to provide maximum corrosion resistance. Based on years of actual in-plant performance, Koch-Glitsch engineers utilize special families of mesh styles for particular equipment and processes to meet customer efficiency requirements. Benefits of DEMISTER® Mist Eliminators ► Easy to install...

Design Parameters For gnral design, Equation 1 has been used as a velocity guideline for many years. State-of-the-Art DEMISTER® Mist Eliminators In the 1990s, Koch-Glitsch developed and refined a new family of styles, replacing traditional styles that Otto York originally introduced shortly affer founding the company in 1947. These new styles take advantage of improved knowledge about the way internal wire geometry affects capacity and performance in the same way that structured packing surpassed random packing performance in distillation columns. Compared to the older styles, the new KOCH-OTTO...

FLEXICHEVRON® Mist Eliminators FLEXICHEVRON® mist eliminators are baffle or zigzag blade modules tailored for either vertical or horizontal flow installations. These mist eliminators collect essentially 100% of all particles greater than 8 to 40 microns in diameter, depending on design parameters and operating conditions. Manufactured in virtually any size from a wide range of metal alloys, thermal-set plastics and fiber-reinforced plastic (FRP), over 20 different styles can be designed and fabricated. Applications for which FLEXICHEVRON mist eliminators are ideal include: ► Scrubbers in utility...

Design Parameters The reentrainment point is a function of gas velocity, as well as other physical properties, e.g., vapor density, liquid density, and liquid surface tension. The reentrainment point is also highly sensitive to the geometry of the chevron. A chevron with superior liquid draining capability and optimum chevron blade spacing can be operated at a higher reentrainment point, yielding a higher capacity. The difference between droplet penetration and reentrainment is often misunderstood. Droplets that penetrate the chevron are too small to be effectively removed by impaction. On the...

High Capacity FLEXICHEVRON® Mist Spcial designs are needed for higher pressure Systems. The FLEXICHEVRON® style 250 and 350 mist eliminators rely primarily on separate liquid drainage channels for their high capacity. Eliminators Benefits of High Capacity FLEXICHEVRON® Mist Eliminators ► Custom engineered to fit any vessel shape ► Allows reduced vessel sizes and weights ► Sturdy, durable construction ► Efficiency maintained at higher pressures Materials of Construction ► Carbon steel ► All 300 and 400 series stainless steel ► Alloy 400 ► Alloy 200 ► Alloy 20 Horizontal and Vertical Style 250...

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