DOP FILTER

DOP RECOVERY FILTER FROM PVC COATING LINES

Process description

The vapours leaving the PVC coating lines are conveyed to a prefilter for the removal of the foreign matter before entering into the cooling section.
The vapours temperature is reduced to 40° C about and the organic substances are caught by condensation with possible formation of a mist.
The mist of air containing DOP, DNP or other phthalates is conveyed to a special filter where the DOP is removed and collected into a basin. The clean air is sent to the atmosphere through a blower having the necessary head. Fiberbed filters are used to trap, collect and remove liquids and soluble particulate matter suspended in the gas stream. Collection can be achieved with an efficiency as high as 99.5% depending on particle sizes. Typical concentration of DOP in the gaseous stream is around 500 mg/Nm³ and after filtration, DOP content in the effluent is less than 10 mg/Nm³. Airstream and process gases can be vented free of pollution; the recovered material can be collected into drums for reutilization.

Construction

Filters are typically constructed in annular cylindrical form. The cylinder is formed by rolled screens of selected special material; the filter material, selected from a wide range of media, is placed between the two frames to form the filter bed. The diameter of the fibre, fibre material, and the material’s packing density determines the operating parameters of the filter (such as pressure drop, collection rate, efficiency, gas through-put, etc.)

Filter process

Mist laden gas passes in a horizontal direction perpendicular to one side of the fibre bed and cleaned gas exits from the opposite side. As the particles try to pass through the fibre bed, they are trapped and held by the fibres. The collected particles are coalesced into drops on the filter’s fibre surface and drain by gravity.
To save energy can be provided the air fan with an inverter receiving the controlling signal from the relevant pressure control.