Baghouse design: as the gas flow rate to fabric surface area ratio (air-to-cloth ratio, Nm^3/hr per m^2) increases, how do the size and cost of a bag filter change?

Introduction / Context:
The air-to-cloth ratio (A/C), defined as gas volumetric flow per unit fabric area, is a key sizing parameter for baghouse (fabric) filters. It directly influences the required cloth area, footprint, and capital cost of the dust collection system.

Given Data / Assumptions:

• A/C = gas flow (Nm^3/hr) / cloth area (m^2).
• Comparable dust characteristics and cleaning method (pulse-jet or reverse-air) across alternatives.
• Target outlet emissions and pressure drop limits are fixed.

Concept / Approach:
For a given flow, a higher allowable A/C implies less cloth area is needed. Lower cloth area reduces the number of bags, the housing cross-section, and overall capital cost. However, there is a trade-off: too high A/C can increase pressure drop and shorten bag life.

Step-by-Step Solution:
Required cloth area A = Q / (A/C).As A/C increases, A decreases.Smaller A leads to smaller casing and fewer bags → lower size and cost.Hence, size & cost decrease when A/C increases (within practical limits).

Verification / Alternative check:
Vendor selection charts show families of designs parameterized by A/C; moving to a higher A/C shifts to smaller modules at the same flow.

Why Other Options Are Wrong:
Increases/remain unaffected: contradict the inverse relationship between area and A/C.None of these: not applicable since a definite trend exists.

Common Pitfalls:
Ignoring dust stickiness/abrasiveness that limit maximum A/C; overlooking cleaning energy and pressure drop growth between pulsing cycles.

Final Answer:
decreases