A sophisticated kiln telemetry system is helping Acme Brick maximize product quality and consistency while minimizing energy consumption.
For Acme Brick's Elgin plant, located 30 miles east of Austin, Texas, quality and consistency are paramount. The plant manufactures high-end molded brick, which are fired in one 400-ft-long kiln. When Acme built the plant in 2000, the company knew that controlling its firing process as carefully as possible was key to optimizing its products. It had used Datapaq temperature profiling systems in numerous other facilities and considered the technology to be the standard in temperature profiling. Then, in mid-2002, Datapaq released a new radio frequency telemetry system that was designed to monitor temperatures in real-time during the firing process. To Eric Gregory, burning supervisor at Acme Brick's Elgin plant, this new technology seemed like the ideal solution.
"The old Datapaq technology was the best available at the time, but it had to run all the way through the firing cycle before we could collect the data and make any necessary adjustments. This typically required two to four days, and a lot of problems can happen in that amount of time," he says. "With the new system, data collection was instantaneous, so any problems could be corrected immediately. This was a significant advancement."
The data logger is placed under the kiln car, and up to 20 thermocouples can be led through the car's base to take product or ambient temperature measurements.
As with the previous system, the data logger, encased in a protective thermal barrier, is placed under the kiln car. Up to 20 thermocouples can be led through the car's base to take product or ambient temperature measurements, and up to 110,000 measured values can be recorded in the data logger's internal memory.* While this data could not be accessed until the end of the firing cycle with the previous technology, the new technology uses a radio telemetry system that allows the information to be continually received by a computer during firing, and powerful software enables fast and accurate analysis of the recorded temperature profile. The software can be used for an at-a-glance display of the temperatures at individual points around the kiln car, as well as the set holding times at specific temperature levels.
In addition, the software features a pass/fail analysis function that indicates instantly whether the firing process is progressing within the permitted tolerances. Format-specific firing curves from previous measurements can be referenced for comparative analysis. If an out of tolerance condition is detected, the kiln operator can immediately intervene in the firing process and adjust the burners so that the temperature is corrected for successive kiln cars. The operator can then run follow-up profiles to prove the changes were successful. Some companies use a second system located several cars after the initial system to verify the effect of changes made using the information received from the first system.
*The newest model, introduced in 2004, records up to 130,000 data readings.
Other benefits of the telemetry system include:
- Routine monitoring of a process generates a database of profile information that can help manufacturers develop new processes accurately and efficiently.
- Routine analysis of profiles will reveal how and where operations can be optimized. Rebalancing the time at temperature and heat ratios can often allow plants to increase line speed and product throughput. Additionally, by knowing exactly what is happening to the product in the process, plants can minimize time spent on test runs and process setups and maximize the number of profitable production runs.
- All of the data files are fully traceable, and each includes operator name, product type and data logger serial number in addition to temperature information to prove that the process is being performed in a controlled and repeatable manner as scheduled.
- The information provided by the system enables plants to make the best possible product with the highest efficiency, thereby saving fuel. Less fuel consumption also means lower emissions.
The software allows the operator to see exactly where probes have been positioned in relation to the profile in a 3-D view of the kiln car.
Despite its sophisticated tracking and analysis capabilities, the telemetry system is designed to be user-friendly. According to Gregory, anyone who knows how to operate a computer can easily operate the kiln telemetry device. "There was really no learning curve associated with this technology," he says. "I had about a two-hour training session with our kiln operators, and that was really all that was needed for them to effectively use the new system."
The portability of the system has also been a significant benefit. In addition to using the device to carefully track firing conditions, the Elgin plant also regularly runs the system through its dryers to optimize its drying process.
Since the Elgin plant purchased the kiln telemetry system in 2002, additional advances have been made in the capabilities of the profiling and analysis software, and the plant has taken advantage of many of these upgrades. For each thermocouple, the latest version of the software calculates quartz inversion slopes and a quartz inversion index; the heat work index; the maximum, mean, and minimum temperatures at the precise time they were reached, as well as the deviation from set temperature; the time spent above predetermined temperature thresholds; the rates of heating and cooling for each probe over user-defined temperature ranges, along with the time the temperature is within each range; and the maximum rate of heating and cooling for each probe, the times at which these occurred, and the average rate of change of temperature for each probe.
A profile animation feature provides a visual impression of the heating and cooling at each thermocouple position throughout the process. While the above example is from a whiteware facility, the same feature can be used in brick manufacturing.
The software also identifies the two probes with the biggest temperature difference within the profile and the time when that occurred. This information can be used to identify where the worst imbalances of heating are occurring around a kiln car. A "view data" function allows the operator to view the raw temperature and time data for each thermocouple throughout the run. All of the various functions have alarms that can be set in real time to warn the operator if the firing process is exceeding optimum parameters.
If the push rate changes while a test car is in the kiln, variable push rate settings allow the software to continue to record the temperature profile. The settings can accommodate a virtually unlimited number of changes in push rate speed, which allows the kiln operator to accurately locate faults such as a burner failure, even if the push rate changes throughout the trial.
The software also allows the operator to see exactly where probes have been positioned in relation to the profile in a 3-D view of the kiln car. If thermocouples have been set at different positions within the brick packs anywhere on the kiln car, the operator can "rotate" the car mimic to get a good visual view of the heat balance around the car.
Graphic "mimics," representing burners, cooling jets, fans, etc., can be set up below the kiln profile graph to show their position relative to the kiln profile.
Additionally, a profile animation feature provides a visual impression of the heating and cooling at each thermocouple position throughout the process. Rather than simply viewing data on a chart, operators can actually watch the thermal balance change around the kiln car as it progresses through the kiln. The color of the area around each thermocouple changes as the temperature rises and falls.
Graphic "mimics," representing burners, cooling jets, fans, etc., can be set up below the kiln profile graph to show their position relative to the kiln profile. Mimics can be positioned at both sides and the top of the kiln to give a true representation of their actual position.
As with earlier versions of the software, all of the modifications have been designed to be as easy to use as possible. User-friendly "wizards" can be used to guide kiln operators through any task they want to perform. Additionally, a help button that appears on most screens can take operators directly to the area of help specific to the function being viewed.
According to Gregory, it all comes down to the bottom line. "Using the kiln telemetry system has enabled us to keep our product quality and consistency at the highest levels possible, and we've also been able to carefully control our fuel consumption. These are all benefits that directly affect our profitability.
"Acme Brick has always been very aggressive in adopting new technologies, and the kiln telemetry system is just one example," he adds. "We believe that the more we advance our manufacturing capabilities, the more successful and profitable we will be."
For more information about the kiln telemetry system, contact Datapaq at 187 Ballardvale St., Wilmington, MA 01887; (978) 988-9000; fax (978) 988-0666; e-mail firstname.lastname@example.org ; or visit http://www.datapaq.com .
For more information about Acme Brick, contact the company at P.O. Box 425, Fort Worth, TX 76107-0425; (817) 332-4010; e-mail email@example.com ; or visit http://www.brick.com .