Reciprocating Steam Engine (ES) flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Saturation temperature

The temperature at which steam and water coexist in equilibrium at a given pressure; it rises with pressure and reaches 374 °C at the critical point.

Dryness fraction

The mass fraction of vapor in a wet steam mixture, used in h = hf + x·hfg to compute mixture enthalpy from tables.

Latent heat of vaporization

The enthalpy needed to convert saturated liquid to saturated vapor at constant pressure; it decreases with rising pressure and vanishes at the critical point.

Isentropic efficiency

The ratio of actual work produced by expansion to the ideal isentropic work between the same inlet and outlet pressures.

Rankine cycle efficiency

Net work (expansion work minus feed pump work) divided by heat added in the boiler; the ideal reference for steam power cycles.

Double-acting cylinder

A cylinder in which steam acts on both sides of the piston, producing work on each stroke; crank-end area is reduced by the piston rod.

Compound engine

An engine that expands steam in two or more cylinders in series, with high-pressure exhaust feeding the low-pressure cylinder through a receiver.

Crosshead and guide

A sliding assembly that absorbs the connecting rod's side thrust and keeps the piston rod aligned with the cylinder bore.

Indicator diagram

A pressure-volume or pressure-crank angle plot of the cylinder cycle, used to find mean effective pressure and diagnose valve timing.

Cylinder clearance volume

The volume remaining at the end of the stroke, expressed as a percentage of swept volume; it stores steam that re-expands on the next stroke.

Valve lead

Admission of steam slightly before dead center, allowing pressure to build at the start of the stroke and improving power and smoothness.

Cutoff point

The fraction of the stroke at which admission ends; earlier cutoff at light load reduces throttling loss and improves economy.

Stephenson link motion

A reversing valve gear in which a slotted link shifts the die block to change valve travel, cutoff, and direction of rotation.

Governor droop

The percentage speed drop from no load to full load; typically 2–5 % for stable parallel operation of mechanical governors.

Governor hunting

Cyclic speed oscillation caused by excessive governor sensitivity, lost motion in linkage, or mismatched governor and engine response.

Safety valve function

An automatic valve that opens at set pressure to relieve the boiler and reseats when pressure falls, protecting against overpressure.

Low-water cutoff

A boiler safety device that stops fuel firing when water level falls below a safe limit, preventing overheating and vessel failure.

Boiler blowdown

Controlled discharge of boiler water to remove dissolved solids and sludge, protecting against scale, foaming, and carryover into the steam.

Steam trap

A device that discharges condensate and air while retaining live steam; a failed-open trap wastes steam and lowers plant efficiency.

Superheater

A boiler section that raises steam temperature above saturation at the same pressure, improving cycle efficiency and reducing condensation in the engine.

Cylinder warming procedure

Admitting steam slowly with drains and cylinder cocks open until condensate clears, avoiding thermal shock and hydraulic lock.

Water hammer risk

Condensate driven at high velocity by steam can strike piping and cylinders, causing pressure spikes, bent rods, or cracked heads.

Overspeed trip test

A pre-service check confirming that the trip mechanism stops steam admission at the set overspeed limit; a failed trip bars operation.

Barring after shutdown

Slow rotation of a stopped engine during cooling to prevent uneven contraction and shaft bow on large units.

Cylinder oil feed rate

The lubricator setting delivering high-temperature steam-cylinder oil, scaled to steam consumption and load to limit wear without excess carryover.

Bearing temperature trend

A rise of roughly 10 °C above baseline at constant load signals inadequate oil flow, misalignment, or contamination and warrants investigation.

Oil analysis program

Laboratory testing of viscosity, water content, acidity, and wear metals to schedule oil changes and detect wear before failure.

Gland leakage correction

Adjusting or replacing piston rod packing to stop steam blow-by; overtightening scores the rod and increases friction.

Late release timing

Exhaust opening later than designed raises cylinder pressure against the piston, reducing power and raising exhaust line pressure.

Lockout/tagout

Isolation of steam, electrical, and mechanical energy sources with locks and tags, verified by test before maintenance begins.

Confined space entry

Entry into boilers or receivers requiring atmosphere testing, an entry permit, a standby attendant, and a rescue plan.

Boiler emissions limits

Jurisdictional caps on NOx, CO, and particulates from boiler firing, met by burner tuning, fuel choice, and monitoring records.