Glossary
Steel and refining
Waste-heat boiler
Also known as WHB, waste heat boiler, process waste-heat boiler.
A waste-heat boiler (WHB) is a tube-bundle steam generator that recovers heat from a process gas stream — typically Claus SRU exhaust, sulphuric-acid plant SO₃ converter outlet, BOF off-gas, or similar process-side energy source — to generate steam for site use. Distinct from a heat-recovery steam generator (HRSG), which serves gas-turbine exhaust.
Fouling characteristics
The fouling pattern depends on the source process:
- Claus SRU WHB — sulphur and ammonium-salt deposits on the tube sheet and economiser
- Sulphuric-acid plant WHB — sulphate and sulphuric-acid mist below the dew point
- BOF WHB — fine iron-oxide dust
- Metallurgical off-gas WHB — variable, depends on metal being processed
Sonic-horn duty
Sonic horns on WHB economiser sections and downstream dust hoppers are common where the process side produces particulate-laden gas. Particularly valuable on SRU WHBs where ammonium-salt deposits consolidate quickly and resist conventional cleaning.
Related terms
Related terms
- Claus unit and sulphur recovery unitA Claus / SRU unit recovers elemental sulphur from H2S-bearing refinery acid gas through partial combustion and catalytic conversion. WHB economiser fouling is the principal cleaning issue.
- Heat Recovery Steam GeneratorAn HRSG recovers heat from a gas turbine's exhaust to generate steam, the second cycle of a combined-cycle plant. Finned-tube ash deposition and ABS fouling are the main cleaning concerns.
- EconomiserAn economiser is the final tube bank in a boiler's convective pass that recovers heat from the flue gas by preheating feedwater. Ash bridging in the economiser is a routine cleaning challenge.
- Sonic hornA sonic horn is a pneumatically-driven low-frequency sound emitter (typically 60–400 Hz at 140–180 dB SPL) used to dislodge particulate fouling from boilers, ESPs, baghouses and process vessels.