Material comparison

PPS vs PTFE vs fibreglass for incinerator flue gas

These three media cover most incinerator baghouse specifications. On paper their service temperatures overlap enough that buyers assume they are interchangeable and choose on price. In practice they fail in completely different ways, and the cheapest per square metre is often the most expensive per year.

Side by side

PPS: the default, with one condition

PPS is the standard choice for waste incineration and coal boilers because it handles acid and alkali well at a temperature that most incinerator baghouses actually reach after a heat exchanger. If your gas enters the baghouse at 150–170 °C, is acidic, and the oxygen is under control, PPS with a PTFE membrane is usually the correct engineering answer.

The condition is oxygen. Above about 8% continuous O₂ — and especially with NO₂ present — the polymer oxidises. The felt turns brittle, bags crack at the fold lines where they contact the cage, and life collapses to twelve months or less. If you run high excess air, or the unit has frequent high-temperature excursions with the ID fan pulling air through, PPS is a trap.

PTFE: the answer when the gas is unpredictable

PTFE is chemically inert to almost everything in incinerator flue gas, tolerates 260 °C continuously, and does not care whether the gas is wet or dry. Where a plant has variable waste, frequent upsets, or a scrubber outlet that occasionally carries moisture over, PTFE removes an entire category of failure.

The trade-off is mechanical rather than chemical. PTFE has lower abrasion resistance and lower tensile strength, so it needs careful cage condition, moderate pulse pressure and a sensible air-to-cloth ratio. It also costs significantly more per square metre — but at two to three times the life, the cost per year of service is often lower than PPS.

Fibreglass: high temperature, dry gas only

Fibreglass earns its place where the baghouse really does run hot — 250 °C and above, typically upstream of a heat exchanger or where the plant wants to avoid reheating. It is dimensionally stable and resists oxidation well.

Its weakness is flex fatigue. Glass fibre has limited ability to bend repeatedly, so bags fail where they flex against the cage during pulsing. It also tolerates acid and alkali only moderately, and hydrolytic attack in wet gas is a real risk. Fibreglass belongs in dry, continuously hot service with gentle cleaning — not in a wet incinerator baghouse with aggressive pulsing.

How to decide in practice

1. Establish the real baghouse inlet temperature, continuous and peak, measured rather than assumed. Everything follows from this.
2. Check whether the gas is above its acid dew point. If not, no media will give you long life; fix the thermal side first.
3. Log the oxygen level. Above 8% continuous, treat PPS as unsuitable regardless of what the last supplier said.
4. Look at abrasion and cage condition. If cages are worn or misaligned, PTFE and fibreglass will disappoint; fix the hardware before choosing premium media.
5. Compare cost per year, not cost per bag. Divide price by expected life at your conditions.

A common and expensive mistake: buying PPS because it is what the plant has always used, in a unit that has since been re-rated and now runs at 12% oxygen. The media did not get worse. The duty changed.

Frequently asked

Can PPS and PTFE bags be mixed in one collector?

They can physically, but do not do it. Different pressure drop characteristics across compartments cause uneven flow, and the lower-resistance media takes more dust load and wears faster.

Does a PTFE membrane change the base media choice?

No. The membrane improves dust release and fine-particle capture, but the base felt still has to survive the chemistry and temperature.

What about P84?

P84 is a high-temperature option with excellent fine-dust efficiency, but it is pH-sensitive and hydrolyses in wet acid gas. It suits dry, hot processes more than incinerators.