Uninsulated steam distribution and condensate return lines are a constant source of wasted energy. The table shows typical heat loss from uninsulated steam distribution lines. Insulation can typically reduce energy losses by 90% and help ensure proper steam pressure at plant equipment. Any surface over 120°F should be insulated, including boiler surfaces, steam and condensate return piping, and fittings.
Insulation frequently becomes damaged or is removed and never replaced during steam system repair. Damaged or wet insulation should be repaired or immediately replaced to avoid compromising the insulating value. Eliminate sources of moisture prior to insulation replacement. Causes of wet insulation include leaking valves, external pipe leaks, tube leaks, or leaks from adjacent equipment. After steam lines are insulated, changes in heat flows can influence other parts of the steam system.
Example: In a plant where the fuel cost is $8.00 per million Btu ($8.00/MMBtu), a survey of the steam system identified 1,120 feet (ft) of bare 1-inch-diameter steam line, and 175 feet of bare 2-inch line, both operating at 150 pounds per square inch gauge (psig). An additional 250 ft of bare 4-inch-diameter line operating at 15 psig was found. From the table, the quantity of heat lost per year is:
- 1-inch line: 1,120 ft x 285 MMBtu/yr per 100 ft = 3,192 MMBtu/yr
- 2-inch line: 175 ft x 480 MMBtu/yr per 100 ft = 840 MMBtu/yr
- 4-inch line: 250 ft x 415 MMBtu/yr per 100 ft = 1,037 MMBtu/yr
Total Heat Loss = 5,069 MMBtu/yr
Given a boiler efficiency of 80%, the annual cost savings from installing 90% efficient insulation is: (0.90 x $8.00/MMBtu x 5,069 MMBtu/yr)/0.80 = $45,620
Use Insulating Jackets
Removable insulating jackets are available for valves, flanges, steam traps, and other fittings. Remember that a 6-inch gate valve may have more than 6 square feet of surface area from which to radiate heat. Install insulating jackets on steam traps according to steam trap manufacturer’s directions to maintain proper trap operation.
Campbell-Sevey carries a complete line of Shannon Insultech insulation blankets to meet your needs, along with the ability to custom fit any application. Contact the team at Campbell-Sevey for more details.
Click to ownload the original DOE Steam Tip document – Steam_Tip_2_-_Insulate_Steam_and_Condensate_LInes.pdf
This tip is provided by the U.S. Department of Energy – Energy Efficiency and Renewable Energy and originally published by the Industrial Energy Extension Service of Georgia Tech.