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CO Control on Sintering Machines: The Hardest CO Duty

Part of the CO Oxidation: The Complete Guide — this article is one of the detailed pages in the guide.

Direct answer: Sintering machine flue gas is the most demanding CO oxidation application in industry: large flows, moderate temperature, and CO concentrations that swing from hundreds to thousands of ppm within hours as the sinter bed progresses. Successful control requires a catalyst sized for the peak CO, placed where temperature and dust are manageable, and tolerant of SO₂ and moisture.

Why sintering CO is difficult

  • Concentration swings — CO tracks the combustion state of the sinter bed; charge cycles and upset operation produce order-of-magnitude swings.
  • Large flow — a single sintering line can move millions of Nm³/h; even a small unit dwarfs most process-gas duties.
  • Moderate temperature — flue gas after dedusting often sits near or below light-off, forcing preheating or heat recovery decisions.
  • Co-pollutants — SO₂, moisture and residual dust arrive with the CO.

System architecture

The typical layout is dedusting → temperature management → CO oxidation → stack (or further treatment):

  1. Dedusting — ESP or bag filter protects the catalyst face from blinding.
  2. Temperature management — if the gas is below light-off, heating-tube catalysts or heat exchange with hot wind boxes lift the temperature.
  3. CO oxidation — honeycomb catalyst bed sized for the peak CO with exotherm control.
  4. Optional SCR — where NOx also requires control, SCR follows the CO stage.

Sizing rules for sintering duty

  • Size for the peak CO, not the average — the compliance test can come at any hour.
  • Compute the adiabatic rise at peak CO; single-stage is acceptable only if the bed stays inside its thermal rating.
  • Add dust margin — even after dedusting, residual ash accumulates; choose pitch and face velocity accordingly.
  • Plan bypass or preheat for cold starts and low-load operation.

Field results and expectations

Reported sintering machine tests show outlet CO below 20 ppm from four-digit inlet values under stable conditions — but sustained performance depends on temperature stability and peak management. Plants should measure the full CO range over normal operation before sizing.

Manufacturer perspective

Sintering duty is where our field experience concentrates: we size from measured CO profiles across charge cycles, not from a single design point, and we prefer pilot testing with the plant's real gas before full installation.

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