Sustainable Operations

Drivers, key trends and best practices in O&M

The role of coal-based power is ch­anging rapidly with the increasing integration of renewables. Th­er­mal power plants (TPPs), which were the ma­in source of baseload power in the past, are now expected to play a supp­ortive role to balance the variable rene­wable energy generation. These chang­es, coupled with tougher environmental norms and ageing thermal plant fleets, have posed challenges for utilities in terms of efficiency, generation and availability, thereby necessitating a move towards advanced operations and maintenance (O&M) practices.

Key drivers

As a result of the growing penetration of green energy, TPPs are required to un­dergo several rounds of load cycling by quick ramping up and ramping down. Owing to temperature and pressure ch­an­ges in the process, plant eq­uip­ment undergoes extreme stress, often leading to creep-related failures. With further increase in the integration of renewab­les, which are projected to meet 50 per cent of the country’s energy requirements by 2030 as announced by the pri­me minister at COP26, thermal utilities will be required to run the­ir plants at technical minimum levels, though these were originally designed for baseload operation. This is likely to lead to unstable furnaces, high secon­dary heat rates and increased secon­dary oil consumption.

Moreover, the increasing stringency of emission norms for TPPs and the introduction of a penalty mechanism for non-compliant operations means that ex­isting pollution control systems (su­ch as electrostatic precipitators [ESPs]) need to be overhauled. In addition, with the installation of new equipment such as flue gas desulphurisation systems and NOx control systems, the capital and operational expen­ses of utilities are set to rise. In order to ensure smooth plant operations, it is imperative for gencos to implement ef­fe­ctive O&M strategies.

Additionally, the ageing of power plants means that utilities need to invest in renovation and modernisation (R&M) for efficiency improvement. R&M can help utilities achieve an increase in generation by about 30 per cent and an efficiency improvement of up to 23 per cent. While the addition of 1 MW of generating capacity requires a capex of around Rs 60 million per MW, an equivalent capacity can be achieved by investing around one-third of this amount in R&M activities.

Best practices and technology trends

In recent times, new and innovative technologies are gaining popularity for efficient O&M. For instance, data analytics, machine learning and artificial in­telligence can be used to track operating parameters for early detection of excursions or defects. Utilities can de­p­loy data analytics tools for improvement of cyclic efficiency through the detection of energy losses. These tools can also help optimise the maintena­nce strategy by res­tric­ting unscheduled outages and eliminating unnecessary preventive maintenance. Equip­me­nt hea­lth monitoring can also be undertaken through real-time monitoring of critical parameters and condition monitoring. Fu­r­ther, robotics can be used for the detection of silting in underwater pipes, while drones can be used to measure the volume of coal piles and inspect bunkers.

On the fuel side, utilities often undertake thermal imaging of coal yards to reduce heat loss. In addition, pile age monitoring can assist in reducing heat loss and maximising heat value utilisation. Further, selective bunkering can help in the utilisation of low calorific value coal during technical minimum load.

Other key O&M practices include the use of gamma rays to detect ESP hoppers’ health, installation of exfoliation meters, furnace mapping for boilers and furnaces, usage of smart soot blowing, optimisation of cooling tower fans, and insulation surveys of critical piping and furnaces. Some common flexibilisation measures include optimisation of burners, reduced mill operation, application of advanced process control and predictive analytics, and enhanced digitalisation for boiler and turbine feed monitoring.

Conclusion

Cycling and part-load operation of TPPs close to technical minimum levels leads to thermal stress, component deterioration, poor heat rate and increased auxiliary power consumption, resulting in higher opex and outages, and consequ­ent loss of revenue. Improved O&M pra­ctices such as real-time asset monitoring, along with data and predictive analytics, can help gencos mitigate these is­sues and ensure higher efficiency as well as cost savings. Gencos should un­der­take a thorough techno-economic ana­ly­sis, as certain measures and technologies can entail significant capex, while others may be carried out through mi­nor modifications.

In addition, the increased operational expenditure on account of a higher heat rate, wear and tear of components due to cycling, and oil consumption for frequent start-ups also needs to be factored in. In the near future, generation utilities need to scale up their O&M strategies manyfold in order to ensure sustainable operations in times to come.

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