Gas Filters and Separators FGWS

Construction and Function

The separators for dust and fluids are of the vertical type. Their function is to  separate solid and liquid contaminants from the gas flow using the kinetic energy of the gas flow.

The separator is a welded steel construction (see drawing). Observation of UDT guidelines and pressure-vessel directive 97/23/CE as well as ASME requirements is guaranteed during planning and calculation of the equipment. Separation of fluids happens in the "wet" part (e.g., axis cyclone), where the gas flows through the inlet. The gas then enters the "dry" part where it is filtered.

In the inlet, the gas should have a speed of at least 10 m/s. At the entrance to the fluid separation part, there is a baffle that rotates the gas forcefully. A vortex develops where the velocity increases towards the middle. (Not unlike what happens when water drains from a bath tub). The centrifugal forces acting on the particles of dusts and fluids are many times stronger than gravity.

Due to the aforementioned effect, contaminants are thrown against the outer wall of the separator body. As the speed of the gas is lower at the wall, the centrifugal forces there are reduced. The pressure distribution inside the vortex (with higher pressures at the edges) causes a secondary gas flow in the middle of the vortex. This flow carries the contaminants away and prevents them from
accumulating on the walls of the body. The contaminants follow the main gas flow until the force of gravity acting upon them, and the force resulting from the pressure difference within the vortex, cancel each other out. In the end, it is gravity that prevails and the contaminants fall to the bottom of the separator.

The separating wall in the middle of the separator makes sure the accumulated contaminants are not carried away by the gas flow again. Next, the gas flows into the upper part of the filter, where it undergoes additional cleaning thanks to the insert. After the gas has passed the insert, it leaves the gas filter and the separator through the outlet.

Efficiency of the Separator

FGWS Filter Separators are highly effective for cleaning gas and combine the properties of filter inserts and cyclones.

Efficiencies:

Liquids: – 99.5 % for particles > 10 – 12 μm
Solid particles: – 99.8 % for particles > 5 – 12 μm

The indicated efficiency for liquids is reached with a gas velocity of at least 10 m/s in the inlet. With a lower velocity, the separation efficiency (e.g., liquids from gas) is significantly lower. This task is then taken over by the insert. The downside, however, is a significantly faster contamination or even conglutination
of the insert with high viscosity liquids (such as oils, grease, etc.). The efficiency of solid particles separation, on the other hand, is independent of the gas velocity in the inlet.

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