---
title: "Hopper"
description: "A hopper is an inverted-pyramid or conical vessel designed to store bulk solids and discharge them through a converging outlet. Hoppers appear under ESPs, baghouses, economisers, air heaters and process equipment of every kind across cement, power, WtE, biomass, refining, pharma, food and mining."
canonical_url: "https://sylio.co/glossary/hopper"
last_updated: "2026-06-28T02:29:32.984Z"
---

A **hopper** is an inverted-pyramid or conical vessel designed to store bulk solids and discharge them through a converging outlet. Hoppers appear under [ESPs](/glossary/electrostatic-precipitator), [baghouses](/glossary/baghouse), [economisers](/glossary/economiser), [air heaters](/glossary/air-heater) and process equipment of every kind across cement, power, [WtE](/glossary/waste-to-energy), [biomass](/glossary/waste-to-energy), refining, pharma, food and mining.

## Universal failure modes

- **Bridging** — stable arch forms above the outlet
- **Rat-holing** — narrow channel above the outlet; surrounding material packs and hardens
- **Pluggage** — total blockage that stops discharge
- **Funnel flow vs mass flow** — first-in, last-out behaviour leading to ageing material remaining indefinitely

## Why acoustic cleaning works on hoppers

[Sonic horns](/glossary/sonic-horn) excel on hoppers because the geometry is small enough for the sound wave to fill the whole vessel and the dust is dry and friable. Compared with mechanical alternatives — [bin vibrators](/glossary/bin-vibrator), [air cannons](/glossary/air-cannon-air-blaster), [whip hammers](/glossary/whip-hammer) — they cause no structural stress, no fatigue, and no impact damage to the hopper itself.

## Related terms

- [Silo](/glossary/silo)
- [Bunker / coal bunker](/glossary/bunker-coal-bunker)
- [Bin](/glossary/bin)
- [Bridging](/glossary/bridging)
- [Rat-holing](/glossary/rat-holing)
- [Mass flow vs funnel flow](/glossary/mass-flow-vs-funnel-flow)
- [Sonic horn](/glossary/sonic-horn)