Coal Flow Monitoring System (CFMS): Driving Efficiency in Thermal Power Plants
Introduction
In the complex world of thermal power generation, every ton of coal matters. The efficiency of a coal-fired power plant relies not only on the coal type but also on the way it is distributed to the burners, evenly and effectively. Uneven distribution results in less efficient combustion, greater emissions and costs for fuel. This is where the Coal Flow Monitoring System (CFMS) creates a revolutionary change.
What is a Coal Flow Monitoring System (CFMS)?
The Coal Flow Monitoring System (CFMS) is an online, real-time system for measuring and facilitating the flow of pulverised coal from the pipe to the coal-fired boiler. In a large majority of power plants, pulverised coal is carried from the mills to a coal-fired furnace via numerous pipes. Because of length, bends, and pipe resistance, coal distribution is inevitably unbalanced.
With CFMS, coal mass flow, velocity and temperature are measured continuously, and any imbalance can be adjusted with adjustable coal flow balancing valves. The CFMS technology supersedes a traditional coagulation of fixed orifices, replacing it with dynamic control that reacts in real time with changing operating conditions.
Why is CFMS Important?
- Efficiency Improvement: Equal share coal distribution equals full combustion, which realises boiler efficiency and reduces specific coal consumption.
- Emission Control: Coal flow equalisation maintains the unburnt carbon in fly ash and bottom ash and reduces NOx emissions. At DSPM Korba, the implementation of a CFMS led to a reduction in NOx emissions.
- Cost Savings: Optimised combustion is directly linked to savings in coal. At DSPM, the CFMS balancing saved approximately ₹6 crores annually.
- Operational Stability: CFMS stabilises the differential temperature in superheaters and stabilises the flame when running the unit at low load, maximising reliability.
How Does CFMS Work ?
The CFMS utilises technology with sensors and software to provide a real-time balance:
- Microwave-based Mass flow Sensors: These are located on each pipe to measure coal mass flow and are also able to identify roping of coal (coal clumps together).
- Electrostatic Velocity Sensors: These are located on top of the mass flow sensors to measure coal particle velocity and coal temperature.
- Coal Flow Balancing Valves: Adjustable valves use a manual process to effectively control coal flow for all pipes, not just a fixed orifice.
- User-Initiated Software Interface: The operator uses the software interface to manage real-time data trending, which allows the operator to manipulate the adjustment valves to maintain flow balance.
Case Study: DSPM Korba, Chhattisgarh
CSPGCL’s DSPM 250 MW unit in Korba demonstrated, first hand, the CFMS, where they use their dynamic Coal Flow Monitoring and Manipulation Systems.
Key Outcomes:
- Coal Savings: After balancing using the system, coal consumption improved by 1% resulting in great savings.
- Heat Rate Improvement: Overall heat rate increased by ~1.08%, which is to say the fuel-to-energy efficiency improved.
- Ash Quality Improvement: Partial unburnt carbon fraction in fly ash decreased by 17.3% and bottom ash showed a 10% improvement.
- Emissions Improvement: NOx emissions were reduced by 25.18%.
- Operational Improvement: Superheater temperature difference was up to 6.5 degrees.
This case study illustrated considerable environmental and economic improvements from implementing CFMS with coal power plants.
Challenges in Coal Flow Balancing
Coal flow is dynamic and is affected by mill loading, coal quality, and system design. A balanced system will be disrupted by extreme changes, such as a mill loading change, and the balancing will require adjustments continuously afterwards. DSPM Mill-A has some longer piping resistance that could lead to a problem and require more than one balancing valve to fix.
The Way Ahead
As India maintains a significant coal-based generation for base load power, technology such as CFMS will be necessary for effective and sustainable power generation. For the future:
- Whole Plant Use: Apply a permanent system, CFMS, for all coal pipes at each plant.
- Dynamic Load Adaptive Valves: DCS integrated with automatic valves will allow this.
- Larger Application: Encourage generation across India to install CFMS for cost savings and regulatory compliance.