Pulverised-fuel fired furnace burner arrangements: Which fuel-firing arrangements are employed in pulverised fuel fired furnaces/boilers?

Introduction / Context:
Pulverised coal firing uses fine coal and air injected through burners to create intense, controllable flames. Burner geometry affects flame shape, heat flux distribution, and slagging tendencies, and multiple arrangements are used in practice.

Given Data / Assumptions:

• Common arrangements include wall-fired horizontal, vertical down-shot/up-shot, and tangential firing at furnace corners.
• Objectives include uniform heat release, good mixing, and low unburnt carbon.

Concept / Approach:
Tangential firing creates a rotating fireball; wall-fired systems place burners on opposing walls; vertical firing directs flames up or down. All are valid, selected based on furnace size, ash characteristics, and retrofit constraints.

Step-by-Step Solution:
List prevalent commercial configurations.Confirm that horizontal, vertical, and tangential arrangements are all used.Therefore, choose the inclusive option.

Verification / Alternative check:
Utility boiler designs from major OEMs show all three layouts in service across decades.

Why Other Options Are Wrong:
They are incomplete subsets of the full set of practical arrangements.

Common Pitfalls:
Assuming tangential firing is the only modern approach; neglecting successful wall-fired retrofits and vertical down-shot units for certain coals.

Final Answer:
All (a), (b) and (c)