Component Cooling Water Heat Exchanger Replacement

1
Component Cooling Water Heat Exchanger
Replacement
MAE 412 Section 002 December 2, 2008

• Lauren Steeb
• Jaret Ruehs
• Krutin Desai
• Garrett Sugg

2
Agenda

• Introduction
• Heat Exchanger Criteria and Results
• Service Water Criteria and Results
• Economic Considerations
• Overview of Alternatives
• Recommendations

3
Introduction

• Current heat exchangers have numerous tube leaks
• Design point - Full load (735MW) maximum lake
  temperature
• Three design areas
• Heat exchanger design
• Service water system design
• Cost-optimization

4
Design Point Criteria

• One heat exchanger in operation
• 10,000 gpm lake water through heat exchanger
• 9,000 gpm of chromated water
• Heat load of 29.4MBtu/hr.
• Shell side velocity of 2.70 ft/s
• 24 ft in length

5
Alternatives

• 1/2 90/10 Cu/Ni
• 2827 tubes
• 56,540 ft
• 3 ft

• 1 90/10 Cu/Ni
• 1913 tubes
• 38,260 ft
• 4 ft, 11 in
• ¾ 90/10 Cu/Ni
• 2211 tubes
• 44,220 ft
• 4 ft

6
Chromated Water Temperatures

• 95 F Lake Temperature
• 1
• Inlet 104.5 F
• Outlet 101.0 F
• ¾
• Inlet 104.1 F
• Outlet 101.0 F
• ½
• Inlet 103.7 F
• Outlet 101.0 F

7
Chromated Water Temperature

• 75 F Lake Temperature
• 1
• Inlet 92.2 F
• Outlet 85.5 F
• ¾
• Inlet 91.6 F
• Outlet 84.9 F
• ½
• Inlet 91.0 F
• Outlet 84.4 F

8
Criteria Service Water System

• Three pumps in operation
• Net Pressure-Suction Head of 15 feet.
• 24,000 gpm of Service Water
• Butterfly valves used to control flow
• Concrete lined, carbon steel piping

9
Service Water System

• Pump Properties
• Discharge Pressure 68.2 psia
• Efficiency 89
• WHP 290hp
• BHP 258hp
• Suction Pressure 7.2psia
• Max. Pump Height 17.3ft

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Service Water System

• Heat Exchanger Outlet Pressure
• 1 63.8 psia
• ¾ 63.5 psia
• ½ 62.1 psia

• Valve Properties (5psig)
• 30 degrees
• 33 open

• Contamination Flow Rate
• 1 110 gpm
• ¾ 51 gpm
• ½ 18 gpm

11
Economic Considerations

• Initial Costs
• 1 488,900
• ¾ 427,900
• ½ 371,500
• Salvage Value
• 1 16,600
• ¾ 14,650
• ½ 12,650
• Total Cost
• 1 617,400
• ¾ 540,500
• ½ 469,200

12
Overview

• 1 inch 90/10 Cu/Ni tubing
• 1913 tubes for system requirements
• Shell diameter of 4 11
• 110 gpm lost if a tube breaks
• Costs 617,400
• ¾ inch 90/10 Cu/Ni tubing
• 2211 tubes
• Shell diameter of 4
• 51 gpm lost if a tube breaks
• Costs 540,500
• ½ inch 90/10 Cu/Ni tubing
• 2827 tubes
• Shell diameter of 3
• 18 gpm lost if a tube breaks
• Costs 469,200

13
Recommendation

• 1/2, 20 BWG
• 90/10 Cu/Ni tubing
• Total Savings
• 117,340 over 1
• 56,420 over ¾
• Present Worth Savings
• 148,200 over 1
• 71,250 over ¾

• Lowest initial investment
• Lowest operating and maintenance costs
• Smallest heat exchanger shell diameter
• Lowest amount of SWS lost in case of tube failure