Written by Bill Looman, Sales & Business Development for Webcast Experts℠, a division of Krishnan & Associates
Heat rate is how many power plants measure efficiency. Heat rate equals heat input per electricity generated. The less fuel input needed for a unit of electricity output means a more efficient use of fuel. Lower plant heat rates result in lower costs and lower emissions. You would think this would be of great importance for the coal fired power fleet in an increasingly competitive industry under environmental regulatory strain. Heat rate is affected by a number of conditions, including the weather, the quality of the coal that's available to the plant, and operating conditions such as unit cycling. Although heat rate is of growing importance to many power plants, why do some plants deprioritize low cost improvements in new technologies? There is a lot of low hanging fruit that plants can act on to improve heat rate.
Better balance of combustion through improved instrumentation is a good example of a small investment of capital that can produce great returns. So why aren’t plants implementing this technology? This requires an aging fleet to embrace new technologies similar to moving from analog to digital or the old carburetor to fuel injection and in some cases like Fred Flintstone's car to fuel injection. Using instrumentation to first measure combustion factors such as fuel and gas flow (O2), then correlating this data to controllable variables which can result in the balancing of combustion. Once the unit is balanced, the plant is enabled to make a reduction in excess air increasing heat input, effectively reducing heat rate and auxiliary power without risk of damaging the boiler.
I know it seems simple but of course it’s more complicated than that. You will need a site champion to make certain the instrumentation and controls are functioning and calibrated properly. Anyone who has worked in a coal fired power plant knows, that is quite a challenge. This is an ultra-harsh environment; it is hot and it is dirty. You will also need a proven return on investment case. Utilities are particularly prudent in regards to new technology. They have been burnt before by technologies that promise to be “plug and play” and offer an incredible ROI but within a year these technologies are no longer operating and have been abandoned. Plants no longer want an incredible ROI, they want to see sustained improvement with limited maintenance and engineering resources.
Heat rate is important to the coal fleet especially plants that are running at high capacity factors. These plants are making money, however budgets are tight and capital spending needs to be justified by an air tight economic case and quantifiable evidence of sustained improvement.