BASIC STEAM CYCLE / BOILERS

INTRODUCTION

Steam is the working substance used for the propulsion of many surface ships, including nuclear and conventionally powered steam ships. Central to understanding the operation of steam propulsion is the basic steam cycle, a process in which we generate steam in a boiler, expand the steam through a turbine to extract work, condense the steam into water, and finally feed the water back to the boiler. This is accomplished by a series of heat transfers and work exchanges throughout system. We will introduce the basics of naval propulsion and auxiliary boilers, review the basic steam cycle, and examine the major components of this cycle in detail, focusing on required temperatures and pressures and where heat and work are added and removed.

LESSON TOPIC LEARNING OBJECTIVES

Terminal Objective:

2.0 EXPLAIN the fundamentals and principles of thermodynamics and fluid mechanics in relation to the design, construction and operation of engineering plant equipment. (JTI:A)

Enabling Objectives:

2.10 DESCRIBE the theory of natural circulation and how it applies to boiler operations.

2.11 DEFINE boiler end points.

2.12 DRAW and LABEL a diagram of the basic steam cycle to include the function of the following major components:

a. Boiler.

b. Superheater.

c. High pressure turbine.

d. Low pressure turbine (with astern elements).

e. Main condenser.

f. Main air ejector.

g. Main condensate pump.

h. Main air ejector condenser.

I. Deaerating feed tank (DFT).

j. Main feed booster pump.

k. Main feed pump.

l. Economizer.

m. Ship's service turbine generator (SSTG).

n. LP turbine exhaust trunk.

o. Hotwell.

p. Reduction gear assembly.

q. Desuperheater.

2.13 DESCRIBE the types of propulsion boilers:

a. 1200 PSI, single-furnace D.

b. 600 PSI, single-furnace D.

2.14 DESCRIBE the types of auxiliary boilers:

a. Water tube-natural circulation.

b. Waste heat boilers.

2.15 STATE which systems/equipments use main steam.

2.16 DESCRIBE cross connected and split plant operations.

2.17 STATE the normal operating values of the following items as they apply to steam propulsion.

a. Desuperheater outlet temperature and pressure.

b. Superheater outlet temperature and pressure.

c. LP turbine exhaust temperature.

d. Main air ejector condenser outlet temperature.

e. Deaerating feed tank pressure and temperature.

f. Main feed booster pump discharge pressure.

g. Main feed pump discharge pressure.

h. Economizer inlet and outlet temperature.

I. Main condenser pressure.

j. Main condenser vacuum.

k. Main condenser hot well temperature.

l. Steam drum pressure.

2.18 DISCUSS temperature and pressure at all phases in the basic steam cycle.

2.19 Unassigned; reserved for future use.

2.20 Unassigned; reserved for future use.

2.21 Unassigned; reserved for future use.

STUDY ASSIGNMENT

1. Read Information Sheet 60B-102.

2. Outline Information Sheet 60B-102 using the enabling objectives for lesson 60B-102 as a guide.

3. Answer study Scenarios.