Tuesday | January 23, 2018

Plant Quality Primer

Drum Inside

The type and placement of flights in the drum, and how the material is veiled through the hot gases, will have an effect on both the drying temperature and the baghouse temperature. Positioning of the flights is another area filled with options, which are discussed further online.

The material handlers at the plant are instrumental to quality production. These employees include your plant operator, loader operator and ground personnel. They have a whole lot of say regarding the quality of mix your plant produces.

You need to have trust in your loader operator. “You can’t make quality mix without a good loader operator,” Ted Brommenshenkel said. He’s the plant maintenance supervisor for Brannan Sand & Gravel Co., Denver. “A good loader hand will know to remove wet material on the shell of the pile and not feed it into the plant. Inconsistent material with varying moisture contents fed into the bins will greatly influence plant operations.”

To properly handle materials in plant operations, all personnel must follow proper protocols, such as performing a visual inspection of materials. The plant operator will perform a visual inspection of the plant as well.

While performing a visual inspection of the plant, he will want to open the pump valves to get the oil circulating. Completing this step in the early stages of a cold start will help homogenize the binder and assist with getting a consistent asphalt content during initial production. The exhaust fan on the baghouse should be kicked on, followed by purging the burner blower. Next, the operator should turn on the drum, slat conveyor, scale belts and weigh feeders.  Remember that most equipment performs best when it is warmed up prior to production.

As the operator turns on these components, he should be aware of the gauge readings to assure everything is in working order. Check the amperage on the slat. Assure a zero on the scale belts. Make sure the settings are correct. Make a checklist and put a checkmark next to each item as you visually inspect it.

The operator then will start the fire on the burner and get the baghouse warmed up.  Temperatures going into the baghouse should not exceed 300⁰F during the warm up process and should be monitored. While the plant components are warming, a plant operator or ground person should walk around the plant again and visually assess the equipment while it’s running.  Next to vision, one of the best senses this person has is hearing.  Unfamiliar sounds, such as abnormal screeches, bangs or squeaks, are signs of trouble, and should be investigated. Following this step will allow the plant operator to inspect the belts for wear, find a squeaky bearing that may need some grease, confirm safety items are in place, and look for potential items that need addressed.

When the operator feels that the plant is ready to go, he will enter the target tons per hour and mix design into the computer, start the aggregate feed from the bins and the AC pump. Timing is critical during this stage; good timing can reduce plant waste.

The operator has a host of components to monitor at this point:

  • Baghouse temperatures
  • Bin sequencing
  • Mineral filler feeds
  • Aggregate temperatures vs. RAP feed
  • Injection timing
  • Drag slat temp and amp readings
  • Heating circuit readings
  • Truck loadout

Following basic guidelines will help assure a quality asphalt pavement is produced. Having the proper components in place is critical; having good employees who know their plant and their roles at the helm is even moreso.

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