Thermal plants are the mainstay of power production, accounting for about 65 per cent of the total electricity generated in India. Coal-based plants account for the bulk of the thermal power capacities. However, the efficiency levels of the thermal power plants in the country are below par for various reasons.
According to a study carried out by the Centre for Science and Environment (CSE), the efficiency level of India is lowest among the major coal-based thermal power generating countries, with the emissions from these plants being high. Also, the maintenance costs for thermal plants can be quite high, especially in the case of units that are old. The legacy components of these plants are prone to inefficient functioning and downtime, which can adversely impact their performance. These factors drag down the efficiency levels of the thermal plants and add to the environmental and social burdens.
At present, the future technologies would need to address the triple constraints of energy efficiency, reduced emission and cost-effectiveness at the same time. The impetus on infrastructure growth following the numerous initiatives launched by the government would necessitate reliable quality power. Thermal power would continue to significantly contribute in this regard. What's more! Digitalisation would play a vital role in augmenting these initiatives further.
Arvos Energy India with its two divisions-Ljungström and Raymond Bartlett Snow-has been at the forefront of technology innovations and has recently introduced new technologies, which is key for thermal power generation.
Since 1920, Ljungström has been serving the market with air preheaters and gas heaters. With over 15,000 installations worldwide, Ljungström air preheaters and gas heaters are more widely used in thermal power plants than any other brand of rotary regenerative heater. Meanwhile, the company's Raymond Bartlett Snow division enables efficient combustion of fuel (<100 MWe) by providing state-of-the-art high-performance mills for coal grinding. Superior coal grinding ensures better combustion, thereby significantly lowering the consumption of precious fossil fuel, as well as lowering the cost of power production.
Innovative processing solutions
Ljungstrom is focused on leading competition in areas of new product development to provide meaningful benefits to plant operators, such as emissions reduction compatibility, boiler efficiency and flexible operation.
"The products manufactured at our new facility in Chennai include our latest advanced technology heating transfer surfaces DNF+ and DUN8, both protected by patents. These surfaces represent a significant amount of R&D developed by Ljungström," says Pankaj Chopra, Managing Director. "The key feature of our DNF+ product is its superior cleanability while still achieving high heat exchange efficiency. Our DUN8 surface uses technology to increase heat transfer and remove the "skew flow' associated with old surfaces such as DU."
One of most recent and exciting innovations of the company is the AdvX plant upgrade solution to maximise waste heat recovery with an ultra-efficient air preheater, which improves plant efficiency and reduces emissions by enhancing the performance of the air quality control systems (AQCS).
Boosting equipment reliability
The Ljungström air preheater and gas heater are two of the most reliable heat exchangers in the world. This is one of the reasons why they are so widely adopted in all sectors of industrial steam generation heat recovery.
For Ljungström air preheaters and gas heaters, two types of reliability are pertinent: structural or mechanical reliability and performance reliability. Structural or mechanical reliability includes (but is not limited to) the support structure, rotor, drive system and bearings. Performance reliability includes the sealing system, soot blowing system, water washing system and heat transfer surface configuration.
The structure and mechanical components for high reliability is achieved by accounting for all environmental factors, applying appropriate factors of safety, introducing redundancies when deemed necessary, considering maintainability and having the experience and capabilities to implement all of these requirements.
Just as with any machine, the equipment has defined maintenance schedules that should be followed to maintain it in optimum working order and maximum reliability. The parameter that generally defines equipment reliability is the mean time to failure (MTTF). Based on a survey, a majority of the components in the Ljungström air preheater have MTTF of greater than 15 years.
"The heat exchangers are designed with robust drive and bearing systems. But these should be periodically checked for fluid levels, alignment, noise, vibration, etc. to identify equipment problems, which can lead to the stopping of the rotor. This is considered by many as one of the most critical areas of a rotary heat exchanger because if it is rotating, it is working," explained Chopra.
To maintain optimum working efficiency, other focused checks are required on subsystems of the equipment, such as the sealing system, the heat transfer surfaces and the cleaning systems, all of which will enable the heat exchanger to have the highest efficiency and provide the operators with the most return on their investment.
"We have made a great deal of effort to design our equipment to have easily replaceable components. This means that improvements are easy to implement to refresh older models with our new technologies and upgraded components, and to ensure the equipment can meet the demands of today's customers," Chopra added.
On a concluding note, Chopra adds: "Adoption of more efficient technologies can help bridge this gap.
To this end, AdvX technology can save Indian thermal power plant owners more than $2 billion in compliance costs."
FEATURES
Air preheaters: Air preheaters are heat exchangers that recover waste heat from boiler flue gas to preheat combustion air and fuel. The use of air preheaters can improve boiler efficiency by up to 20 per cent and accordingly reduce emissions (more than 2,000 tonne of CO2/day for an 800 MW plant). Efficiency benefits have eliminated emissions of 50 billion tonne of CO2 since 1923. The Ljungström air preheater is more widely used than any other rotary heat exchanger in the steam generating industry.
Gas heaters:Gas-gas heaters are heat exchangers used in conjunction with flue gas desulphurisation (FGD) systems to cool flue gas prior to FGD and then reheat flue gas prior to stack allowing better (i) FGD performance and (ii) dispersion of plume and particulate, besides avoiding acid rains. Ljungstrom gas-gas heaters have an unrivalled track record for highest availability with trouble-free operation. The Ljungström gas-gas heater has an impressive operating pedigree of more than 30,000,000 hours with over 500 units installed globally.
Key benefits of AdvX technology