Atmosphere Furnace  Maintenance Tips

Water Cooling System Troubleshooting for Fan Shafts, Doors and Door Seals

Fan shafts are usually water cooled to prevent heat conduction to the bearings. Some shafts are air cooled, but this means the bearing must run at higher temperature and therefore require special lubrication and will have a shorter life. Likewise, doors and door seals are cooled to prevent distortion of the steel from heat. Any distortion of the steel causes gaps to open up and oxygen to get into the furnace.

Problems with water cooling are mostly caused by debris in the water and water hardness. Water that is hard deposits lime or stone at any point where the water is heated – even a little. One of the best ways to minimize water problems is to set the flow adjusting valves full open. A partially closed valve can easily stop all of the flow if a small piece of trash comes through the line. Stopped flow can cause failure of a fan bearing and the repair can cause 2 or 3 days of downtime. It just isn’t worth trying to save a little water. Running the water line full open also reduces the buildup of hardness deposits because the deposits increase greatly when the water gets warmer due to restricted flow. Another benefit is that full flow gives high velocity, which contributes greatly to keeping the pipes clean of sediment and algae, etc.

In cases where the plant cooling water system is overloaded and wide open flow cannot be accepted, the best system is to install a pressure regulator in the supply line to the furnace. Valves are still set wide open but pressure can be reduced to reduce the total flow. If debris starts to plug the restriction in the regulator, the regulator will open up to maintain the desired pressure and flow and the debris will be flushed out of the regulator.

The latest design, materials and equipment specifications should be obtained from the company before any reliance is placed on the enclosed since changes may occur due to product improvement.