Case study
Industry: Commercial and industrial coal-fired power plant
ISSUE
Start-up/shutdown costs are increasing for power generating facilities due to low generation
Coal-fired power plant is a baseload power source that offers outstanding supply stability and economic efficiency. It is now expected to play a role as a regulated power supply to maximize utilization of renewables, which are growing in use. With the growth in renewable energy use, coal-fired power plants are generating less power, but are still being utilized for their regulating capabilities. In these instances, there may be cases in which power demand falls below the facilities’ minimum operating loads. This raises concerns about increasing numbers of start-ups and shutdowns. As a result, plants will face challenges regarding higher than usual costs related to shutting down and restarting. By lowering coal-fired power plants’ minimum operating loads through effective use of existing facilities as a means of stabilizing the grid, their value as power generation facilities can be enhanced.
SOLUTION
KEY POINTS TO THE SOLUTION
- Performance evaluation for all plants’ facilities leads to optimized retrofitting
- Outstanding ignitability and flame stability enable stable operation even in low-load conditions
- Flexible pulverizer operation expands operating range
Performance evaluation for all plants’ facilities leads to optimized retrofitting
Lowering the minimum operation load of coal-fired power plants enables not only an increase in the amount of renewable energy generation but also operation without having to shut down units at night or low load demand period. Considerations for lowering the minimum operational load require individual evaluations for changes in boiler characteristics when the load is lowered, along with the impact this has on auxiliary equipment and associated facilities. Mitsubishi Power has an extensive track record in the supply of all main products involved in coal-fired power generation, including boilers, steam turbines, generators, and air quality control systems. This means Mitsubishi Power can independently evaluate the performance of the entire plant, and can also identify the areas necessary for retrofitting. This allows us to flexibly propose optimal modifications according to the customer's desired operating condition.
Outstanding ignitability and flame stability enable stable operation even in low-load conditions
Mitsubishi Power offers the core technologies for high-performance burners that can maintain excellent ignitability and flame stability even at low loads, which are requirements for lowering minimum operational load. Consideration of plant conditions is essential for each unit. But it is possible, for example, to lower minimum operating load from 30% ECR to about 15% ECR by changing to the newest burners with high ignitability.
Flexible pulverizer operation expands operating range
By applying an inverter control to the pulverizer motor (VVVF *1), rotation speed can be made variable according to coal feed quantity, expanding the range with the minimum to maximum coal feed and enabling greater flexibility in operation from existing pulverizers. This will allow for continuous plant operation with stability even in low-demand periods. Applying an inverter control to the pulverizer motor not only contributes to lower minimum operational load, but can also expand the operable load conditions without changing the number of operating pulverizers, helping to enhance the load variability rate. *1 Variable Voltage Variable Frequency / Same as VFD (Variable Frequency Drive)
EXPECTED OUTCOME
- Enables stable operation of coal-fired power plants at low loads
- Helps to maximize plant value by realizing flexible regulating capabilities for coal-fired power
- Improves reputations with increased usage ratio of renewable energy
