Spring Startup Brings on the Heat for Heater Maintenance

Believe it or not, spring is just around the corner. As part of pre-startup service, don’t overlook the heating systems for your asphalt cement (AC) tanks.

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Fossil-fuel Burners

Today, almost all fossil-fuel-fired tank heating systems utilize hot oil, which is heated via a burner that runs on diesel, fuel oil or natural gas/propane. Each manufacturer should list specific maintenance steps in the manual, but in general, you will want to conduct your maintenance on a cold system, taking these steps.

1. Test all safety systems.
2. Examine all the hoses across the entire system to ensure they are not brittle, cracked or leaking. If they are, then they will need to be replaced.
3. Inspect the oil pump to make sure the seal is not leaking and that the drive belts and guard are in good condition.
4. Check to make sure the hot oil holding tank’s low-level shutdown device is working properly.
5. Test the control temperature sensor and the over-temperature protection thermometer to ensure accuracy with both.
6. Have the heat transfer fluid analyzed by a qualified vendor (some will provide test kits; other vendors will handle the analysis for you). This oil should be changed every five to seven years at maximum.
7. If you have a hot oil filtration system, it will need to be checked and you will want to replace the filter. If your plant does not have a filtration system, you may want to consider adding one to your system, as it will greatly reduce the amounts of debris and coking circulating throughout the plant. In fact, the money spent on a filtration system will quickly be recouped in heat transfer efficiency and reduced pump wear due to the elimination of debris is going through seals, etc.
8. Inspect and test the system’s auto-start to verify the timeclock is accurate and that the unit will start and stop at the scheduled hours.
9. Check the exhaust damper system and stacks for deterioration and proper operation.
10. Have your burner vendor use a gas analyzer in the stack to tune your burner by reading the emissions coming out of the stack. This step will drastically help control both fuel costs and emissions.
11. Every 10 to 15 years, you will want to check the hot-oil heating coils within the asphalt tank for coking and buildup. This task involves draining the tank and sending in a crew to chip away at the coked buildup and clean out all of that material.
12. If your burner is older than five years old, you may want to consider replacing it. Burners of this age can drop to 50-percent efficiency, and that efficiency will continue to drop each season. You’ll also realize better fuel savings and avoid downtime after startup if you replace an older burner.

Additional Steps for Diesel- or Oil-fired Units:

13. Examine the fuel system, checking for leaking lines and seals.
14. Change the fuel filter.
15. Check the exhaust damper system for deterioration and proper operation.

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Electric Drywell-style Heaters

Electric drywell-style heater systems for direct heating or hot oil circulation generally do not need to be replaced—but they do require some minimal maintenance. You should follow these steps. (Note: There is no need to drain the tank.)

1. Check the wiring and connections, and repair or replace any that might be loose or oxidized.
2. Check the contacts on the contactors. Replace the contactor if worn.
3. Check all fuses to ensure they are all still intact
4. Remove heater cover plate and check to make sure the high-temperature terminals are tight and that the terminal box is dry and free of moisture.

Todd Fields of Butler-Justice Inc., Anaheim, California, and Dan Simpson of Process Heating Company Inc., Seattle, Washington, contributed to this article. For more information, visit bluesmokecontrol.com/  or www.processheating.com/.