Fiber bed mist eliminator, Mist Eliminator HANGING FIBER BED, Candle Mist eliminator

One of the new directions in the production of filtering equipment is the cartridge mist eliminators launched by us into mass production (Fiber bed mist eliminator, Mist Eliminator HANGING FIBER BED, Candle Mist eliminator).

The purpose of filter mist eliminators is to remove mist from an air or gas stream using the Brownian diffusion trapping method at a relatively low gas flow velocity (less than 0.2 m/s). When gas passes through a layer of a very thin fiber, fine mist particles interact with the surrounding gas molecules, causing the particles to move randomly in different directions, thereby coalescence of the trapped liquid particles occurs upon contact with the surface of the fibers and the formation of a liquid film on them. Then, the droplets enlarge, followed by flowing down from the layers of fibers as liquid accumulates in the form of streams or large drops moving inside the layer from its back side of the filter element and, under the action of gravity and an increase in gas flows and capillary forces, flow into the hydraulic seal. In this case, no mechanical effects on the filter layers are usually required, i.e. filters operate with constant resistance in the stationary mode of self-regeneration (self-cleaning).

Structurally, mist eliminators consist of two coaxially cylindrical grids welded to the bottom and inlet flange. Frame material: stainless steel AISI 316L. The space between the grids is filled with fiber, the bottom of the element is equipped with a tube immersed in a water seal, from which the trapped liquid flows into the body of the apparatus. On the base plate of the column, the mist eliminators are fixed through the P.T.F.E gasket with studs and nuts. Depending on the performance of the installations, from 1 to 50-70 elements can be mounted in one body of the device. At existing sulfuric acid plants, such elements are often installed in a separate building, and in new shops - in the upper parts of absorbers (with a capacity of up to 170 thousand м³/ч).

Fiber mist filters are divided into two types:

- low-velocity (ʊ ≤ 0.2 m/s), equipped with fibers with a diameter of 5-20 microns and designed to capture submicron particles due to Brownian diffusion and the entanglement effect; their efficiency increases with a decrease in filtration rate, particle size and fiber diameter;

- high-velocity (ʊ ≤ 0.5 + 1.2 m/s) with a layer of coarse fibers with a diameter of 20-100 µm, used to release gas from particles larger than 1 µm due to the mechanism of inertial settling, the efficiency of which increases with increasing particle size and speed filtration to a certain (critical) value (usually 1-2.5 m / s), at which the secondary spray of the trapped liquid begins from the layer in the form of large drops.

Technical characteristics of mist eliminators:

ME FGM cartridge type low speed mist eliminators.

For equipping low-speed mist eliminators, a mixture of glass fibers with a certain ratio of coarse and fine fibers is optimal. Coarse elastic fibers provide a uniform distribution of thinner ones, increase the rate of liquid withdrawal from the layer, give the latter mechanical strength and stability, making it possible for thinner fibers to work throughout the entire depth of the layer. Typically, layers of a mixture of fibers with a diameter of 5 to 20 microns with a porosity of 88-92% are used. The most commonly used fibers are 8 to 15 microns in size with a layer thickness of 50-60mm.

The main material of the filtering part used by us is a special chemical resistant glass fiber FGM 145 in the form of a multilayer needle-punched fabric resistant to concentrated and di-lute acids.

In addition, other types of synthetic fibers may be used depending on the application. The hydraulic resistance of the mist eliminator is no more than 150 mm. water art.

The efficiency of this type of mist eliminator can be reduced if there are insoluble organic, metallic or mineral particles in the working gas stream, which can enter the mist eliminator from the equipment installed before it. It can also be particles of sulfates or chemically formed salts, such as ammonium sulfate, ammonium nitrate, nitrosyl-sulfur

Anhydride, nitrosyl pyrosulfate:

- if there is any amount of HF gas or alkaline PH in the working flow, which cause corrosion for glass fiber and can destroy the filter part.

- when the gas flow velocity exceeds 0.2 m/s.

- at insignificant humidity of the purified gas. filter part

effective when wet and, in addition to the density of the fibers, moisture forms "additional resistance" and the effect of Brownian diffusion.