Filter for Gas Cleaning - Indirectly Heated Oven Fume Filtration System - Air and Climate - Air Pollution Treatment

• 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 indirectly 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.

Recovered plasticizer and solvent could be re-used.

There are 4 main feature components in this system design :

• An efficient prefilter (type BECOIL) is installed to collect large particles and insolubles, to give maximum protection to the downstream components to maximise their life and minimise maintenance.
• It is usually necessary to fit a water fed fin & tube heat exchanger cool down the gas to 35°C to ensure all plasticizers and the less volatile solvents are in liquid phase.
• High efficiency filters Type HT(2) TGW15, giving the ultimate in sub-micron fume collection.
• Bag liners are fitted inside each candle filter to give final added protection to the fibre ( which is the most expensive component )

Additional benefit features are :

• Pre-filter and Bag Liners can be cleaned and reused when pressure loss indicates solids blockage.
• Pre-filter fitted via a drawer system, for easy access.
• Candle Filters are fitted via removable flat roof sections for easy access to the Candle Filters and  Bag Liners.
• Hot water heat recovery from the Heat Exchanger can be used in the plant.

• Horizontal pre-filter housing and cooler for smaller air volumes or downward flow vertical pre-filter housing and cooler for larger air volumes.
• 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.
• If no corrosive components are present, cooler will be Copper tubes & Aluminium fins. Alternatively, Carbon Steel or Stainless Steel tubes can be used.