Lakeland Electric, the third-largest public power utility in Florida, reported that it saved $12 million in fiscal year 2015 through the use of a coal treatment at its McIntosh Power Plant Unit 3. The savings represent up to 20% of the unit’s annual coal supply costs.
A typical coal-fired power plant will spend about 70% of its operating budget on fuel. When coal prices were increasing, Lakeland Electric began searching for ways to burn different types of less-expensive, “opportunity coals.” The challenge with opportunity coals is that they can be more difficult to burn, and using them may cause plants to experience an increase in ash slag deposits on the boiler wall, superheater, and reheater tubes. Those deposits reduce efficiency and increase operational costs, which can negate the opportunity coal’s fuel cost savings.
Chemicals Solve Slagging Issues
In an effort to overcome deposit problems at McIntosh (Figure 3), Lakeland Electric chose to try GE’s FuelSolv fuel treatment program for deposit control. FuelSolv is a combination of specialty chemical additives designed to minimize combustion challenges and allow utilities to burn different coals without jeopardizing boiler efficiency (Figure 4). The chemical additives reduce slagging, which in turn allows plants to operate at maximum loads while minimizing the need to shut down for cleaning. Deposits that do form in the combustion zone are generally much easier to remove, reducing the downtime required for mechanical cleaning.
3. McIntosh Power Plant. With a total capacity of 941 MW, McIntosh is Lakeland Electric’s largest generation facility. Courtesy: GE Water
4. Tweaking the system. A Lakeland Electric operator balances and improves local furnace gas temperatures to help control slagging, corrosion, and carbon burnout. Courtesy: GE Water
“Using GE’s FuelSolv application has allowed our McIntosh station to burn the lower-cost opportunity coal without the problems of slagging or de-rating in our boilers, which ultimately is saving our plant and the city of Lakeland a lot of money in operational costs and coal supply costs,” said Ken Riddle, supervisor of chemical processes for Lakeland Electric.
The company’s deployment of FuelSolv comes at a time when coal power plants are facing increasingly stiff competition from lower natural gas prices. For many years, McIntosh had burned Eastern bituminous Central Appalachian (CAPP) coal. However, while prices for CAPP coal increased due to various factors, natural gas prices decreased. That cost difference has placed coal-fired electric generation at a competitive disadvantage with natural gas–fired combined cycle units.
The lowest cost producers in the power pool run baseload, while more expensive units often sit idle until peak demand requires their use. To remain competitive, utilities have been seeking options to use more of the lower-quality opportunity coals, such as Northern Appalachian and Illinois Basin coal, as blends with or replacements for CAPP coal.
According to Riddle, Lakeland Electric has been increasing the percentage of opportunity coal used in its boilers for quite some time and was able to reach the point where 100% of its fuel burned in Unit 3 is now opportunity coal. In addition to the 2015 fuel cost savings, the company said Unit 3 has saved $500,000 in operating costs from 2010 to 2014. ■
—Tom McCafferty is account manager for central and north Florida for GE Water and Process Technologies.