Boiler water carryover control: In practical boiler operation, foaming and priming (i.e., entrainment of water with steam) can be mitigated most effectively by reducing which impurity parameter in the feedwater?

Introduction / Context:
Foaming and priming are common boiler-house problems that lead to wet steam, scaling in superheaters and turbines, and loss of efficiency. The question asks which feedwater quality parameter, when reduced, most directly cuts the tendency for foamy bubbles to form and be carried over with steam.

Given Data / Assumptions:

• The boiler is operating at typical industrial pressures.
• Feedwater may contain suspended solids, dissolved solids, color-forming organics, and traces of oil/alkalinity.
• We seek the single parameter whose reduction gives the most reliable improvement against foaming/priming.

Concept / Approach:
Foaming is stabilized by high concentrations of dissolved solids and surface-active impurities; priming (water carryover) is also aggravated by excessive total dissolved solids (TDS) because high TDS lowers surface tension and promotes persistent bubbles. While turbidity and color may correlate with organic load, the root driver that operators monitor and control for carryover is total solids (especially TDS), managed by makeup quality, internal treatment, and blowdown strategy.

Step-by-Step Solution:
Identify mechanisms: dissolved solids and surfactants stabilize foam films; high TDS increases carryover likelihood.Operational control: boilers employ continuous/intermittent blowdown to hold TDS within limits, directly mitigating foaming/priming.Therefore, the most impactful reduction target is total solids (particularly dissolved solids).

Verification / Alternative check:
Standard boiler water guidelines limit TDS, silica, and alkalinity. When TDS drifts high, carryover rises; reducing TDS reliably restores dry steam quality.

Why Other Options Are Wrong:
Turbidity: suspended matter is undesirable but less central than TDS for foaming.Color (Hazen): indicates organics but is an indirect indicator, not the primary control knob.All (a), (b) and (c): too broad; the principal parameter is total solids.Oil and grease only: surface-active oils worsen foaming but are controlled separately; TDS remains the routine limiting parameter.

Common Pitfalls:
Confusing visible turbidity with dissolved solids. Clear water can still have very high TDS and severe foaming potential. Always verify TDS and alkalinity, not just clarity.

Final Answer:
Total solids (especially dissolved solids)