Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/674527
AGGREGATES MANAGER Voices of Experience Arnold Connelly and Mark Cohen Matt Etheridge t t A ccording to Arnold Connelly, area manager of aggregates, and Mark Cohen, electrical maintenance manager — both employees of Tilcon New Jersey, it is better to have total automation in a plant versus automating individual pieces of equipment. "Single machine automation is good, but it's like having a limb missing," says Connelly. "You're not getting all of the information you need, and it's difficult to make good management decisions." Total plant automation gets the operator and management the accurate data they need from throughout the plant. "The whole quarry is one big electrical system. It monitors amp draw from every piece of equipment, and helps the operator in determining problems. It tracks the scales, the tons-per-hour — anything you want," Cohen says. "You can see problems before something breaks down. For instance, if the conveyor belts are slipping or the screen is running outside of the correct amp parameters, you can schedule preventive maintenance, rather than running into unexpected downtime for a repair." For historical information, a total plant automation system will track and record data from every piece of equipment, so that decisions can be made for running the plant more efficiently. Scheduled maintenance is much more accurate because the operator has true knowledge of tonnage history and amp draw. "The ability to track history tells the truth about every- thing that has happened in the plant. Before automation, we had to rely on information from the operator, who didn't have all of the information. It's a lie detector, so to speak, because you have accurate data to review," Connelly says. "The ability to monitor the plant remotely through the boardroom allows area and upper management to see the entire plant from a remote office at any time, and ask questions of the operator." Tilcon New Jersey is in the process of automating all of the plants in the area. And Cohen says the learning curve for using the automation system is typically quick because the system on the monitor looks graphically like the plant the operator has been running all along. Similarly, gaining buy-in from operators has been fairly easy. "A 20- or 30-year plant veteran might be a bit nervous about it. Younger guys who grew up using computers adapt quicker," Cohen says. "After the system is installed, the manufacturer stays behind and works with the operators until they are comfortable with running the plant through the system. The manufacturer also gives great phone support and helps online if there are questions. Once the operators actually start using it, they love it. It makes their jobs easier and takes away a lot of the stress," he adds. "A lmost all manufacturing processes in the U.S. are fully automated. Think of automotive manufacturing, food processing, etc.," says Matt Etheridge, president of Etheridge automation. "Our industry (the aggregates industry) is the only one that has lagged in the ability to be fully automated." Why is this so? Etheridge explains that other industries that automate rely on uniform input into a process. The automo- tive industry purchases its automation systems in packages. The philosophy is that the robots handling welding and other tasks are handling uniform tasks for identical automobiles that advance along the assembly line. "It's easy to automate be- cause the controls all repeat," Etheridge says. "Compared to our industry, it would be the same as trying to build a compact car, followed by an SUV, followed by a van coming down the line. The robots can't work with these variations because the parameters are constantly changing. There's no uniformity." Etheridge says the number-one reason all quarries are not automated is that simple process automation doesn't work for them. When automating a quarry, the automation provider must be intimately familiar with the industry and the processes. "There are so many variables you have to work with when automating an aggregates operation," he says. "There are variables with blasting — how the material fractures, moisture content, gradations, etc. We have to write our own unique control loops into the PID (proportional integral derivative) every time. The automated system has to adapt to all variables and be flexible because no two quarries are alike. It must drive the process variables to a set-point value and then control the output. "In a typical retrofit, we build the PLC (programmable logic controller) in the shop with all the relays and terminals. This is mounted in the MCC (motor control center). A wire goes to each starter for each piece of equipment," Etheridge says. "All wiring is in the MCC. We add some sensors out in the plant for bins, maximizer probes, levels in the crusher. We are able to use fewer of these than we did in the early years." Etheridge adds that automation packages today can monitor what is going on in the plant without a lot of outside sensors, which are easily damaged by the harsh conditions. The PLC runs the plant and also talks to the computer, where the operator can see everything that is going on in the plant with one or more monitors. "The system has to be hard-wired so that every piece of equipment communicates be- tween the PLC in the MCCs. We also can build systems that communicate with fiber optics or even wirelessly," Etheridge says, adding "Wireless has gotten better and better and better."