Throughout the mid-to-late 19th century, steam produced by boilers was the leading energy source for driving industrial machinery, locomotives and steamboats. Today, steam still is often used as a heat transfer medium and motive force in industrial process and commercial heating applications. Because of the amount of energy required to operate boiler systems, keeping them running as efficiently as possible is key to minimizing fuel costs.
Advancing burner management and combustion control technologies have helped boiler manufacturers produce systems that burn cleaner and more efficiently by enabling more precise control of boiler firing rate, fuel-to-air ratio and excess air. Keeping pace with today’s changes, boiler manufacturer Cleaver-Brooks, Milwaukee, has upgraded its control platform to incorporate more advanced features such as enhanced communication, diagnostics and control capabilities. The company has built the control system around off-the-shelf technology and open network communications to improve reusability of code and installation time. To ensure maximum reliability, the controls ease access to real-time operating data as well as historical trending so users can plan for needed maintenance. In all, Cleaver-Brooks has designed a fully integrated boiler system with single-source responsibility for ongoing service, support, training and replacement parts to make the boiler easier to operate, maintain and troubleshoot.
“We needed a control platform that would give our customers maximum reliability, efficiency and the information gathering-capabilities they need to optimize boiler performance and track energy costs, while allowing us to build a library of code that we can leverage for our other customers - reducing development time,” says Sarkis Krikorian, Cleaver-Brooks’ director of new product development.
Rockwell Automation’s Allen-Bradley CompactLogix programmable automation controller was Cleaver-Brooks’ choice for the new system. As one of the first small controllers to connect to Ethernet/IP, the controller enables users with less than 2,000 I/O to exchange system-wide information while still providing powerful processor and I/O functionality. The mid-sized unit directs all burner management functions required for startup, shutdown and online operation of Cleaver-Brook’s CB-Hawk.
With RSLogix 5000 programming software, the user can take advantage of built-in function blocks and tag-based addressing. The software program configures each boiler by enabling and disabling routines. Input modules process signals from field sensors and pushbuttons, and precise control capabilities help increase fuel-to-steam efficiency. Output modules provide signals to final control devices such as vent valves and safety shut-off valves as well as to status-indicating lights.
The CompactLogix controller provides both discrete and process control for users to make on-the-fly adjustments and monitor all boiler activity from a central platform. An Allen-Bradley PanelView operator interface provides a graphical representation of process information, so operators can change setpoints, monitor alarms, improve tuning parameters and select between automatic or manual control.
The ethernet/IP network allows remote monitoring and control via the internet. Used with its text-string handling capabilities, the CompactLogix processor can initiate e-mails to multiple addresses to deliver complete operation reports. This feature can be used to alert maintenance personnel to manufacturing problems, provide manufacturing proficiency data back to management, or provide machine diagnostic data back to the OEM.
Cleaver-Brooks also is using the new control technology as a retrofit to existing boilers, and incorporating it into some of its accessory products, including an expanding line of column, spray and tray deaerators.
“Historically, the boiler room has been one of the least automated areas of the plant,” according to Cleaver-Brooks’ Krikorian. “With the CB-Hawk ICS, plants now are able to cost-efficiently equip their boiler rooms with integrated control technology that improves boiler efficiency, reduces emissions and improves reliability while enhancing safety, all from a single source.”