MLM® Multi-Layer Media

Why Layered Construction Works

Deep ceramic monolith fails under thermal cycling because the material cannot accommodate steep temperature gradients across its full depth. MLM solves this by limiting each layer to 1–1.5 inches, cutting the per-layer gradient dramatically. The interleaved horizontal gaps between layers add pressure drop reduction and plugging resistance — particulates pass through rather than accumulating in long vertical channels.

The problem wasn't ceramic material, it was ceramic *geometry*. MLM redesigns the geometry to survive what monolith cannot.

Four Configurations for Different Objectives

MLM comes in four cell densities — MLM-125, MLM-160, MLM-180, and MLM-200 — offering different points on the heat capacity/pressure drop curve. Higher numbers mean more ceramic per cubic foot: higher heat capacity, better thermal efficiency, somewhat higher pressure drop. MLM-200 is the standard choice for new construction and most retrofits; lower-density configurations serve applications where pressure drop is the binding constraint.

Three Retrofit Scenarios

Cost-cutting retrofits replace saddles or random ceramic with MLM. The result is lower pressure drop, reduced fuel consumption, or both — depending on how much MLM is installed per canister. Either way, operating cost savings pay back the media investment rapidly.

Capacity-boosting retrofits use MLM's low pressure drop to enable higher gas velocities — 400 scfm/ft² or more — with good heat recovery. What would otherwise require a second RTO can be accomplished by replacing media and upgrading the fan.

Maintenance-reduction retrofits address RTOs treating dirty air streams. Random packing acts as a particulate filter; MLM's parallel channels allow more particulates to pass through and burn up. The result: less frequent shutdown for media cleaning or replacement.

Revenue, Not Just Savings

Most RTO retrofit cases report cost savings. One municipal biosolids facility tells a different story. After replacing saddles with MLM, RTO throughput increased from 14,000 to 24,000 cfm — 42% more capacity — at lower power cost than the original configuration. At $250 per dry ton processed, that capacity increase generated $1.14 million in additional annual revenue. The RTO became a profit center, not just a compliance cost.

This case was published in *Pollution Engineering* — third-party validation of the revenue impact (Pollution Engineering Case Study).