The June 2009 issue of Energy-Tech included a discussion of trends and initiatives in Remote Performance Monitoring, or RPM, to maximize power plant capacity, availability, reliability and performance (CARP). Using a case study, this article illustrates the benefits of implementing an RPM program using an on-line monitoring (OLM) system to achieve and sustain maximum gains in CARP, as described in the June 2009 article.
The case study
The case study discussed here is for a fleet of coal-fired generating power plants that implemented RPM using an OLM system for units ranging in size from 120 MW-300 MW.
Objectives and goals of RPM
The RPM addressed overall performance of the individual units, as well as critical parameters and issues relating to operation, performance, economics, integrity, reliability and environmental compliance of major equipment.
The power plant owner (PPO) set the following goals for implementing the RPM:
- Maximize the PPO’s return on investment (ROI)
- More effectively
utilize the PPO’s limited resources by leveraging technology-based toolsAdvertisement - Provide critical information and alerts to the PPO on a real-time basis when opportunities were identified to improve CARP
Trending/monitoring process data
For each plant, the scope of the RPM for trending and monitoring real-time power plant process data using the OLM included the following:
1. Overall cycle (operation, performance, economics)
- Capacity, heat rate, controllable parameters, cycle isolation
2. Boiler, economizer, air heater (operation, performance, integrity, reliability, environmental compliance)
- Boiler heat input
- Boiler/air heater efficiency
- Boiler tube leaks
- Boiler casing air in-leakage
- Boiler and air heater draft losses
- Windbox-to-furnace differential
- Excessive slagging conditions
- Unallowable boiler and air heater operating conditions
- Air heater gas/air flow imbalance
- Excess air
- Stack opacity
- Flue gas – CO, NOX, O2
3. Main turbine (operation, performance, integrity, reliability)
- High-pressure (HP) and intermediate-pressure (IP) section efficiencies
- Turbine stage pressures
- Unallowable operating conditions
4. Feedwater heaters (operation, performance, integrity, reliability)
5. Boiler feed pump recirculation issues
6. Long-term condenser pressure issues
7. Cooling tower operation and performance issues
8. Controllable parameters losses
Figure 1 shows an overview of the cycle for one of the units monitored in real time by the OLM system. The OLM system routinely monitored key performance indicators (KPIs) to detect changes occurring in plant processes. An example is the ratio of the throttle flow derived from the HP turbine section first stage pressure, and the throttle flow derived using the feedwater flow. Changes in this ratio would be indicative of any number of things, such as a change in the HP turbine steam path (deposits, solid particle erosion, peening, etc.), boiler tube leaks, excessive blowdown, flow bypassing, etc. Other KPIs included actual vs. expected HP turbine enthalpy-drop efficiency and actual vs. expected air heater x-ratio.
Notification/alerting/reporting
The RPM system was implemented with the capabilities to provide timely notification/alerting of KPIs, problems, issues and reports, as follows:
1. Faulty performance-related instrumentation
2. Reports, including:
- Actual vs. expected heat rate
- Summary of KPI alerts and notification
- Capacity reconciliation
- Component level expected vs. actual capacity deviations
- Heat rate reconciliation
- Component level expected vs. actual efficiency deviations
- Primary flow reconciliation
- Feedwater vs. main steam/throttle flow deviations
- Controllable parameter expected vs. actual cost deviations
- “Lost Opportunity” report summarizing all financial opportunities that were not reconciled
