Steam Turbines vs. Reciprocating Steam Engines – Comparative Advantages Which statements correctly compare steam turbines with reciprocating steam engines in terms of achievable speed, efficiency, and steam consumption?

Introduction / Context:
Steam turbines displaced reciprocating engines in large-scale power generation because of superior performance characteristics. Understanding why helps in appreciating plant design choices and matching prime movers to applications ranging from power stations to marine propulsion.

Given Data / Assumptions:

• Comparing mature designs operating near their practical scales.
• Steam quality and pressure ranges typical of utility plants.
• Focus on steady-state operation and overall plant metrics.

Concept / Approach:

Steam turbines are rotary, continuous-flow devices with minimal reciprocating masses. They readily achieve very high rotational speeds (thousands of rpm) with smooth torque. Their isentropic and internal efficiencies are generally higher than those of piston engines at comparable ratings due to reduced mechanical losses, continuous expansion, and better utilization of high inlet pressures/temperatures. Consequently, for a given shaft output, turbines typically require less steam flow (lower specific steam consumption), especially at utility scales with multi-stage expansions and reheats.

Step-by-Step Solution:

Verification / Alternative check:

Historical data: utilities shifted from large piston engines to condensing steam turbines early in the 20th century because turbines offered better thermal efficiency, more compactness at high power, and smoother operation compatible with AC generators.

Why Other Options Are Wrong:

Choosing any single advantage ignores the others, while ‘‘none of these’’ contradicts well-established practice and performance records.

Common Pitfalls:

Comparing very small turbines with large slow-speed reciprocating engines; at tiny scales, economics and part-load behavior may differ, but the general statements remain true for power generation scales.

Final Answer:

all of these