Speaking at the U.S. Poultry & Egg Association’s 2012 Feed Mill Management Seminar in Nashville, Tenn., Marc Shockley, feed mill manager for Perdue Farms, noted that “When a boiler accident occurs, it is usually not minor.”
Shockley added that most feed mills do not have a dedicated boiler operator. As a result, it is usually a maintenance person that does basic maintenance on boilers. Often this maintenance consists simply of a water analysis, a bottom blow-down and a check of the primary and secondary low water cut off switches. After that, the employee then returns to their normal duties, leaving the boiler to operate on its own. While it may not be necessary to have a dedicated boiler operator, Shockley advised that boilers need more than minimal attention.
Water is most important
“A correctly sized and installed boiler will generally do fine on a day-to-day basis,” Shockley said. However, he emphasized that the most important thing about boilers is water, noting that if a feed mill’s boiler has water problems they need to be fixed right away. Water problems can make a boiler less efficient and can lead to complete boiler failure if left unchecked.
Shockley added that boiler inspectors are there to help mill managers and should be viewed as a resource. “If your boiler is in good shape, then ask what you can do to make it safer,” he said.
Shockley offered a list of operational tests and checks that should help keep a mill’s boiler running correctly.
- Water analysis: know your water and select the best program for your plant’s needs.
- Feed water pumps: if you have more than one pump, check to make certain they are all working and alternate them daily.
- Deaerator tank water column blow-down test: this test should be done daily for the purpose of prolonging sensor life and to reduce pump cavitations.
- Primary and secondary low water cut-off test: this test should also be done daily to make certain that the burner doesn’t run when the water level is low.
- Feed water cut-off test: this test should be done once a month to simulate a real low water event through pump failure.
- Bottom drain test: this is a test that should be done once per quarter. The purpose is to simulate a real low water event through valve failure.
Keeping track of checks and tests is extremely important, according to Shockley. “Document, document, document,” he said. “If you don’t document it, then you haven’t been doing it.”
Maximum burner restarts
Shockley also spoke about the importance of maximum burner restart attempts as they can be a potential cause for burner/furnace explosions. There are a number of things that can cause these explosions, including fuel source issues, fuel metering devices, improper control system purging and faulty igniters, among others.
“Each plant needs to develop a plan that regulates the maximum number of restarts,” he said. “Man made it, and it can fail.”