Coriolis Meter Case Study: How POND Technical Helped a Local Power Generation Plant Achieve Operational Excellence Through Reliable Fuel Flow Measurement
About a year ago, a large U.S. power producer worked with POND Technical to install an Emerson Micro Motion Coriolis Flow Meter at a local natural gas cogeneration power plant (157 MW). We discussed the performance advantages that Emerson Micro Motion Coriolis flow meters have over the previous mechanical meters with an I&C Technician and Maintenance Manager from the facility.
Problems with Turbine Meters
The continued use of turbine style flow meters on fuel gas at their facility created several ongoing issues, according to the two power plant employees. These meters required frequent line down maintenance, with costly and lengthy lead time for annual calibration. Additionally, there was little or no factory support for the meters.
The maintenance manager said that with these older instruments saw a lot of use, and when outages occurred, certain maintenance procedures had to be followed. “We had to have them calibrated and shipped to a lab in Texas within a certain time frame. It was very costly, and as meters were starting to fail here and there, we were starting to play musical meters with other facilities: do you have one there we can use and vice versa?”
“It became a headache, as well as just any of the repairs,” he added. “They were outdated. If you made a repair, you had to have it certified again. It just wasn’t a good process.” Because the old meters were mechanical in nature, the facility had to do monthly PMs to lubricate their bearings with a hand pump, causing additional interruptions with line availability and higher costs to buy “this really expensive” synthetic oil.
Challenges Relating to Fuel Flow Measurement
The natural gas cogeneration facility, like every other Power Plant, faced challenges involving reduced greenhouse gas emissions requirements over the coming decades and a need for more accurate and reliable fuel flow measurements to keep within ever tightening regulations, avoid fines, and reduce purchase of expensive, taxed, out-of-state power.
Fuel flow is a weighted average over time of fuel vs load. It’s a way to constantly confirm a meter is accurate. “With the turbine meter,” the I&C technician said, “if the bearings were going and it was starting to drag you could see the difference between the actual fuel to load ratio compared to how over time it had started to change, a slight change and sometimes a big change if there was something wrong with the meter.”
The fuel flow to load ratio is used in EPA reporting to the state. “If your heat rate starts to change, that’s basically your fuel to load ratio, you can tell that either something was going wrong with the gas turbine or it wasn’t running correctly,” he added.
If a meter went bad while generating power, they would have to take the system down, causing a loss of revenue. On a couple of occasions, the I&C Technician said, they had to take a day off from generation in order to change a meter. “It’s a lot of money, especially if it happens on a hot summer day when prices are high. It can be hundreds of thousands of dollars.”
Working with POND Technical
The maintenance manager said that the facility had worked with POND Technical over the years as POND was on the vendor list for supplying certain items, “When we started to look for new meters I wasn’t really aware that POND had dealt with these, but my colleague here was always a big advocate of the Coriolis meters based on our experience with the rotary meters that we’ve had and the issues that we’ve experienced over the past several years.”
They are both happy with the service POND has provided. “POND has always given us great service,” the maintenance manager said. “Response time is always good, and we always get what we need pretty quickly. They are good at making recommendations and because of that we continue to use them so they can provide strategic advice that helps us in the long run.”
POND Technical Solutions
POND’s Micro Motion Meter provides extremely accurate and repeatable flow measurement with no moving parts, little or no maintenance, a data recorder with historian, and Smart Meter Verification. The sensor is calibrated in accordance with strict EPA standards for emissions monitoring compliance.
The Smart Meter Verification check enables performance analysis and in-situ diagnostics in between calibrations. With regard to the performance of the meters at the natural gas cogeneration facility, the maintenance manager stated: “They are very accurate, and, with no moving parts, they require little maintenance.”
Final Results
Use of the Coriolis meters helped the facility realize annual savings of $10,000 in O&M costs and $5,000 per meter in calibration costs. Safety was increased as well by not needing to open gas piping and move large, heavy flow meters in and out.
Both credited the meters with helping the facility save on internal resources and hard cash on maintenance. While they still need to have the meters checked in order to maintain compliance with the EPA for emissions, the expense is much less.
The I&C technician noted, “I would expect these meters to be durable, I don’t see having to replace them anytime soon, so ROI should benefit.” He added: “I would recommend this type of installation to other facilities. We have a call every couple weeks with all the other sites in our fleet, and I think everybody’s going to switch over to these meters because the whole fleet has always had issues with the old turbine meters.”