PVC Coating/Synthetic Leather

Gas Cleaning › Directly Heated Oven Fume Filtration System

PVC / VINYL COATING – Direct heated oven / Indirect heated oven +lacquer / chlorinated additives

PROCESS INFORMATION

Most common manufacturing applications are Synthetic Leather ( car upholstery, bags, shoes etc.), vinyl coated and linoleum flooring, vinyl coated wallpaper, laminated sheets ( special films, belts, tarpaulins ) and foam products.

Polyvinyl-chloride (PVC) is a thermoplastic and is mixed to additives which improve its properties and enable it to be processed more easily

Most common major additives are:
plasticizers to provide elasticity i.e. DOP (Dioctyl Phthalate)
stabilizers to prevent degradation i.e. PB salts
lubricants (solvents) to prevent plugging on cylinders of the calendering machine
charges i.e. silicium
pigments i.e. anthraquinones

Typical formulation : PLASTICIZERS : 50% + SOLVENTS : 48% + OTHERS : 2%

The emulsion (polymer + additives) is spread coated and heat cured or calenderized in ovens. PVC emulsion is fed to ovens with successive steps of curing/calendering and cooling sections. Gas is extracted from curing/calendering sections and cooling sections.

Exit gas from curing ovens (180 – 150 °C) which has been directly heated.

Depending upon formulation, 500 to 5,000 mg/m³ of plasticizers are present in the exhaust gas. Solvents and other products are also entrained.

PROBLEMS TO SOLVE

Air pollution.

As an average, industrial sites regulations specify a maximum emission of 20 mg/m³ of plasticisers ( = invisible ), or 50 mg/m³ total carbon, or an odour related limit. More stringent levels, e.g. 2 mg/m3 of DOP plasticiser are now sought.

Low volatile solvent removal

Recovered plasticizer and solvent could be re-used.

Avoid blockage by / extra maintenance demands due to :

DOP B HT2 SERIES CANDLES

DESIGN SOLUTION

BECOSOLVE System with ‘Scrubber’ Pre-filter –

In response to the special problems presented by the very dirty fume which is usually
generated by direct fired ovens, we developed a simple solution to avoid ( or at least
minimise) the blockage by hydrocarbons, ‘cracked’ hydrocarbon compounds and
other solid / viscous materials, including chlorinated parafins such as Cereclor
( which forms a waxy film on the Candle Filters when cool ) and lacquers ( which
form a hard coating on the Candle Filters when cool ) .

We have developed a pre-filter scrubbing section, which can be a first stage add-on in any emission treatment line. Such pre-filter scrubbers are working perfectly at various sites in Europe.

A low pressure loss BECOIL demister pad is irrigated with recirculated DOP or other suitable plasticiser which is used in the customer’s process. This creates an efficient, high voidage contact bed to knock out particulates and viscous materials, before they pass to the main Candle Filter vessel.

This is done in a downward flow, vertical arrangement and washes solid or coated materials out of the pre-filter and the cooler below it.

In addition to the same 4 main feature components in the basic system design this enhanced design advantages are :

Options :
In addition to the 1st stage pre-filter in the vertical housing, 2nd and 3rd stage pre-filters can be fitted ( drawer access also ) in the inlet section of the main Candle Filter vessel, to give extra pre-filtration and fibre bed protection in the most ‘dirty’ services.
Candle Filter lengths from 1,220 mm to 3,660 mm, to suit available height above vessel, or to minimise system footprint.
For some installations where the highest possible efficiency is demanded, we have installed An Xtra-Pure concentric double fibre bed candle filter design, which can achieve 5 to 10 mg/Nm3 exit.
Cooler will be Carbon Steel or Stainless Steel tubes & Aluminium fins.