Boiler Feedback System Ensures Safety and Reliability
EP Editorial Staff | September 2, 2003
Baylor College of Medicine in Houston, TX—a high-tech research facility—has one of the first installations of an updated watertube boiler online feedback system.
Previously, the online data reporting system for its boilers fed information to the boiler manufacturer’s headquarters. There, the manufacturer could anticipate maintenance and repair problems from the operation data. In turn, it could advise the customer’s local service representative of adjustments the customer should make on site. In addition, some adjustments could be made online from headquarters.
Now, Baylor’s on site boiler operations staff can receive feedback similar to what was formerly available only to the boiler manufacturer.
Need for usage trends
Baylor wanted the system to ensure an uninterrupted supply of process and heating steam for its campus of buildings enclosing 1.4 million sq ft. The director of facilities, Rock Morille, and project engineer, James Kisiel, wanted the benefits of the new feedback technology in addition to switching from firetube to watertube boilers.
“We like to know what is happening with our equipment so we can extend the life cycle, conserve on energy, reduce emissions, and operate in a safer manner,” Kisiel explained. Morille added: “This was the best and most efficient way for us to get the campus ‘usage trends’ information that we must track in order to comply with regulatory standards. For instance, it will be a good thing to see a trend for low water cutoffs. It also validates what we are doing.”
Baylor has to contend with greater restrictions from government regulatory agencies. Texas has mandated that Houston plants have continuous metering of their gas usage to ensure compliance. Kisiel commented that “one of the great benefits of our particular brand of watertube boiler is that it allows you to add sensing and measuring devices and record critical operating information which then is seen in the software package that organizes and displays the other measured points.
“ The monitoring system feeds back gas-related data in a number of forms (focusing the operator’s attention on total system performance). There is data on high and low gas pressure, how long the boilers actually run in high fire or low fire, fluctuations in flue gas temperatures, etc. This feedback from the monitoring system can verify that a plant is in compliance.”
Flame signal failure solved
Joe Regini, supervisor of the Baylor Central Plant, noted the new feedback system has already eliminated costly service calls. “Recently, I had a flame signal failure. It is supposed to read 5 V on the flame signal, but it did not.” The flame signal failure showed up on the boiler monitoring system’s day-by-day, 31-day report of data from the various signal, pressure, temperature, conductivity, and gas usage (square cubic ft/hr or SCF) monitors.
Regini was puzzled; “The boilers were operating perfectly, but I could not get a flame signal.” With the boiler monitoring system, the company has a choice: diagnose a problem or call the boiler manufacturer, who receives more complex diagnostic data—the “black box” information on the 4 sec before shutdown.
The manufacturer can select the reports or “signatures” on all the operating data related to steam pressure, flame signal, water levels, surface blow down valve, feed water pump, damper position, and conductivity sensor. The signature also shows the last 4 sec measurements of the scale monitor, temperatures, conductivity, mode timing, etc., as bar graphs.
Regini decided to call the manufacturer for a diagnosis. The manufacturer identified the flame signal connections as the source of the problem. The connections are in a little plug, similar to a headphone plug, and they were loose on the controller. “Once I plugged them completely in, they were fine,” Regini said.
Switch to watertube technology
Baylor’s decision to switch to newer watertube technology from firetube boilers evolved over time. As Baylor expanded, it increased its firetube boiler capacity to 2100 boiler hp. The 21st century physical plant that Baylor is striving to complete had to confront redundancy, capacity, regulatory, and space issues.
Morille and Kisiel evaluated conventional systems as well as systems differing from standard U.S. installations in order to find the best fit for the campus. “It became evident that if the performance and advanced computerized monitoring promised by Miura Boiler worked, it would offer substantial and measurable benefits to the campus,” Kisiel said.
Regini, who has been with Baylor for 15 years, felt the old firetube boilers were not meeting Baylor’s needs, “The firetubes take a long time to bring up steam pressure. If you start one from cold, it would take you at least an hour to an hour and a half to bring it up to steam pressure. We wanted an on-demand steam generator and we needed redundancy built into our system.”
To meet its on-demand steam needs, Baylor decided to switch to watertube boilers. According to Regini, “They only hold about 78 gal of water, each. So instead of heating a firetube boiler that holds thousands of gallons of water that I have to keep bubbling and hot all the time, I’m heating a smaller surface area and I’m directly changing the water into steam at a much more efficient rate. I’m running, virtually, a one-pass system. Water is coming in the bottom and going out as steam at the top. It is not sitting there simmering like a pot on the stove. With the watertube boiler, I could be cold-start to full-fire in less than 5 min.”
At the time of the switch from firetube to watertube, Baylor replaced 2100 bhp of firetube boiler capacity with seven 300 bhp watertube boilers, retaining one 600 bhp firetube boiler. The seven boilers fit in the footprint of two 600 bhp firetube boilers.
Daisy chain the boilers
The redundancy Baylor wanted is provided by a multiple installation (MI) terminal. The MI terminal daisy chains the seven boilers. It keeps track of run time, letting demand on the system determine how many boilers go on or off line. According to Regini, “When you have a multiple installation, the MI controller can start and stop each of the boilers at will, so I have the seven boilers in automatic standby mode.”
In the hard-wired daisy chain, one cable going from boiler to boiler transmits data. As many as 15 boilers can be included in the daisy chain.
The computer that formats and displays the data can be up to 3000 ft from the boilers. Thirty-one days of operating data can be viewed on the screen. The customer can see everything that is transmitted by modem to Miura headquarters, except for the event summary, that last 4 sec diagnostic view.
With the Miura Boiler Monitor (MBM), the customer can do basic troubleshooting on site. According to Mark Utzinger, vice president of the company’s USA operations, “For instance, if they get flame failure, their qualified personnel can make their own adjustment. But for analysis of the flame failure, they would call us. MBM would not tell them where in the sequence the boiler went down.”
Boiler data organized
The monitoring system is an intuitive approach to the organization of boiler data. Since an operator always wants a reminder of what a boiler’s settings are, the settings are grouped on one screen. Another screen pictures (in diagram form) the real time, current boiler status (valves on or off, temperatures, psi, and conductivity).
Once the current situation has been checked, the operator can monitor three aspects of boiler feedback—the alarms, cautions, and combustion—by looking through historical data to see if there are any indications of a development that needs attention. The alarms, cautions, and combustion histories are on separate screens. Alarms totals include various flame, water level, power, temperature, and pressure alarm totals. Cautions totals include times reminded about filters, blowdowns, softeners, batteries, sensors, etc. The combustion history records the time period’s cycles, low and high firing, blowdowns, and blower and pump cycles.
A scrolling screen shows the various signal, pressure, temperature, conductivity, and SCF monitors that are listed, day by day, for the prior 31 days.
And, finally, a monthly report screen provides a recap of the month with comparative data from the prior month, including a gas consumption graph when an optional gas flow meter is installed.
Regini finds the system easy and useful. “The screen information is user friendly. It is Windows based and gives me all the pertinent information that has to do with this boiler. It gives me a history; I can go back 31 days, I can go back 48 hours, and so on. It can tell me how many times the boiler has fired high fire and how many times it has fired low fire. The automation of the system makes it user friendly. All our operators (the boilers are manned 24 hours a day) are qualified to handle anything that comes up.” MT