A new controller system allows easy access to kiln operating information and gives the operator total control of all the kiln processes.

Kiln used for firing ceramic slide gates

Ceramic slide gates used to control the flow of molten steel from ladles are fired in a kiln to impart the necessary strength properties for the harsh service environment. Servsteel Inc., a small manufacturing company based outside of Pittsburgh in Morgan, Pa. uses two bell kilns to heat treat the slide gates they produce. Production at the company's manufacturing plant came to a halt in the summer of 2002 due to a devastating fire caused by a lightning strike, which completely destroyed more than one half of the 40,000-ft2 (3,700 m2) facility. Damage to the manufacturing facility included the total destruction of the control system-a Leeds and Northrup Micromax Loop and Logic Controller-for the two bell kilns.

workload ready for treatment

Rebuilding the plant and getting production back on-line as soon as possible was a top priority of the company. Servsteel's owner Mark McQuillen turned to Pittsburgh-based Swindell Dressler International Co., an original equipment manufacturer that built the kilns around 1995, to get them up and running. Swindell Dressler was able to assist them by offering a system that it was very familiar with, and was able to do the job quickly and cost effectively.

Melted kiln control panel due to fire from lightning strike

Experience is a valuable asset

Swindell Dressler was a frequent user of the Micromax Loop and Logic Controller and also had a long relationship with Honeywell (who bought Leeds and Northrup in 1996). So, when Honeywell was developing its HC900 Hybrid Controller, Swindell Dressler was asked to serve as a beta site for the new product. An HC900 test unit was installed on its two in-house lab kilns, which previously had been controlled using a Micromax system. According to Swindell Dressler's John Arnold, the company performed extensive testing and trouble-shooting on the HC900 and was able to provide Honeywell with valuable feedback on the features and operation of the HC900.

Because it had first hand knowledge of the HC900's capabilities, including its application flexibility, its operator-friendly preformatted displays, and understanding its many cost and time-saving features, Swindell Dressler felt very confidant in recommending the HC900 to Servsteel. In addition, the company could provide enhanced customer service capabilities as a result of being involved with the HC900 project and having considerable experience with the controller.

Kiln No.1 setpoint programmers and zone controllers screen. Three setpoint programmers can be controlled from this screen. The operator can view and modify the setpoint programs by pressing the View/Modify button and also start/stop/hold/ advance/load the programmers. Individual control zone loops are also displayed and controlled from the control screen. A button below each control loop gives access to loop trend and tuning.

Easier, faster and less costly

One of the advantages of the HC900 is its flexibility, which results in the ability to satisfy a wide range of applications. The rack-based HC900 controller is a modular, scalable platform available in 3 rack sizes (4, 8, and 12 I/O slots) to handle a wide range of automation requirements. To maximize installation flexibility, up to 4 remote I/O racks can be connected to a single controller, reducing wiring and installation costs. A variety of analog and digital modules are available to support up to a total of 256 I/O points. Up to 128 universal analog inputs minimize the number of input cards and spare parts required. Honeywell tried to size the product so that it would easily meet the vast majority of application needs.

Setpoint Programmer View/Modify screen allows easy operator access to create and modify profiles. With a click of the mouse, the operator can enter desired rates, segment type or desired events.

In recommending the HC900 to Servsteel, Swindell Dressler believed that a major benefit was the availability of the fully integrated, factory floor Model 1042 operator interface (OI). The large screen OI makes the system very operator friendly and easy to use. "It makes the system simple and easy to learn," said Servsteel operator foreman Brian Caldwell. "It is all visible and provides easy access to everything. It is pretty much self-explanatory once you get on it and start working," he added.

With over 100 preformatted color displays available, the integrated controller/operator interface design automatically updates the correct information on the displays. This shortens design time (reducing engineering costs) and facilitates easy operator interaction with the process.

Analog data tables

Both analog data and digital status information can be viewed in multiple formats on a 10.4-in. LCD display for clear process monitoring. Displays are available for viewing and changing control loops, setpoint programs, recipes, alarm groups, trends and other analog or digital functions. A standard floppy disk drive or optional zip drive stores process data and stores and retrieves configuration information, recipes, setpoint profiles and schedules.

Another advantage is that both the model 1042 operator interface and the HC900 controller are configured by a common Hybrid Control Designer package. Most alternative solutions require two different configuration tools: one to configure the controller and one to configure the operator interface. Hybrid Control Designer reduces the cost of software configuration tools and simplifies configuration revision control.

Digital data tables show status of digital inputs and outputs

Although the Model 1042 O/I provides users with a large variety of local trending and data archiving, Servsteel needed even greater data acquisition and reporting capabilities. The SpecView Supervisory Software met this need. SpecView, which runs on a standard PC, provides customers with much more data storage space along with custom displays and reports.

According to Arnold, "The SpecView Software also offers a redundancy benefit. If one of the operator interfaces goes down, the operator would still have control of the kiln via SpecView."

Loop trending and tuning screen

Upgraded control performance

"The Micromax systems that Servsteel had been using prior to the fire were obsolete, making the HC900 Controllers a major upgrade for the company," Arnold said. The HC900 Hybrid Controller with the Specview Supervisory Software is capable of doing all the things the company did using its old system plus much more.

The company noted that the control system is more advanced than what was used previously. For example, the Micromax limited the company to only using the computer in the kiln trailer. By comparison, with the new system, if something happens with the computer inside the kiln trailer, it is possible to simply go to the individual kiln and all the information is displayed there on the board. No time is lost waiting for the computer. In addition, the HC900 allows easy access and the operator can be assured that he has total control of all the kiln processes.

Owner Mark McQuillen agrees that the controllers are the right choice for this application. They have a more power and flexibility than the previous controllers and they make kiln management more efficient, as well as make the job much easier for the kiln operators.

Although progress is rarely as swift as one would like during a rebuilding process, McQuillen was very pleased with the quick service and the easy-to-use, time and money saving system they got from Swindell. "We got the kilns up and running in the time frame Swindell Dressler figured it would take," McQuillen said.

Controller screen for No. 2 kiln

"The system works great," he added. "We haven't had any problems with it, and it has done everything we wanted it to do. The new system is so much better because I can go in there, hit one button, and get the screen up. Then I can see everything that's going on inside the kiln, from kiln pressure to individual burners. Everything is broken down individually. I don't have to go through a bunch of steps to see what I want to see. I can bring up one screen and basically it tells me everything I need to know," Caldwell said.

While it was unfortunate that it took a major fire for Servsteel to get to this point, the company definitely is in much better shape now than it was before the fire as far as the controllers for its kilns are concerned.