Presentation is loading. Please wait.

Presentation is loading. Please wait.

Main Condensate & Feed Systems

Similar presentations

Presentation on theme: "Main Condensate & Feed Systems"— Presentation transcript:

1 Main Condensate & Feed Systems
We Love Engineering!

2 Objectives Components of Main Condensate System and purposes of each
Components of Main Feed System and purposes of each Operation of Automatic Control Systems Interrelationship of systems during operations

3 Main Condensate System
Provides condensation phase of the main steam cycle Condenses steam from turbines to liquid Pumps condensate from main condenser to the Main Feed System

4 Main Condensate System

5 Main Condenser Indirect, shell-and-tube, cross flow heat exchanger
Maintained at vacuum of 25-29” Hg How is the vacuum initiated & maintained? Two flow paths through condenser Condensate collects in hotwell Provides NPSH to condensate pumps

6 Main Condenser

7 Main Seawater System (MSW)
Provides cooling water for main condenser to condense steam Scoop Injection System Used at higher speeds (> 8 knots) Uses ship’s speed and scoop to cause flow Not on SSN/SSBN’s MSW Pump Used when going slow or astern All SSN/SSBN’s

8 Main Condensate Pumps Centrifugal pumps, either steam or electrical power (subs all electrical) Usually 2 pumps per condenser Check valve on discharge of pump to prevent backflow Lowest pressure in MS cycle at suction of pumps

9 Condensate Depression
Amount of subcooling of condensate in the hotwell of the main condenser If too little (< 2oF), then cavitation of condensate pumps can occur If too much (> 5oF), then lose efficiency (since condensate must be reheated later) Controlled by regulating MSW flow

10 Main Feed System Purpose: to deaerate, preheat, store, and transport water from DFT to the boiler or S/G

11 Deaerating Feed Tank (DFT)
Preheats feed using 150# Auxiliary Steam Stores feed (provides NPSH for MFBP) Deaerates feed (removes dissolved air)

12 Deaerating Feed Tank (DFT)
Operation 150# Aux Steam enters in for heating Condensate sprayed in thru nozzles (foglike) Baffles collect condensate/condensed steam and directed to atomizer assembly Atomizer uses high-velocity steam to redirect condensate-> remove last gases (scrubbing)

13 More Components Main Feed Booster Pump (MFBP) Main Feed Pump (MFP)
Single-stage centrifugal pump Provides NPSH to MFP Main Feed Pump (MFP) Multi-stage centrifugal pump Raises feed pressure > S/G pressure Feedwater Control Valve Regulates quantity of feed flow to S/G

14 Makeup-and-Excess Feed System
During normal operations, necessary to add/remove water from steam cycle System stores feed and provides it if needed DFT level control system provides control If level low, make-up feed valve opened If level high, excess feed valve opened

15 Makeup-and-Excess Feed System

16 Automatic Boiler / S/G Level Control System
Uses closed loop feedback principle of operation Measure actual output Compare actual output with desired output Compute necessary correction signal Correct actual output

17 Automatic Boiler / S/G Level Control System
Automatic Combustion Control (ACC) Maintains boiler’s steam drum pressure by controlling rate of combustion (air/fuel) Feedwater Control System (FCS) Regulates flow of feedwater to boiler to maintain level Diff Control System of MFP (DCS) Maintains feedwater supply pressure above steam drum pressure

18 Automatic Combustion Control (ACC) System

19 Feedwater Control System (FCS)

20 Differential Control System of MFP (DCS)

21 Interrelation of Systems
Answering AA2/3 -> OOD orders AAII Open throttles -> steam flow -> steam pressure ACC system air & fuel to combustion rate FWC system feed to match steam flow DCS of MFP speed of MFP to discharge pressure

22 Boiler Chemistry Control
High temperature water and steam at neutral pH can be very corrosive Holes in piping Chemicals are added to the water to ensure pH stays low (basic) Must analyze for proper levels of these chemicals to ensure corrosion prevented. Can’t have too much – will cause fouling and scale deposits

23 Questions?

Download ppt "Main Condensate & Feed Systems"

Similar presentations

Ads by Google