RENOVATION AND MODERNIZATION OF THERMAL STATIONS - BOILERS

摘要

With the present day energy requirement increasing at an alarming rate and very fewer stations being set up by various utilities and IPPs, there is certain need for renovation and modernization of older power stations which will generate power as per the design conditions after R&M. It is generally seen that out of thermal capacity of 60,000 MW in India, at least 25% are aged between 20 to 25 years which need massive R&M programme to meet the energy requirements in India. Fossil-fuel-fired generating stations have traditionally been built with an assumed nominal design and economic life of about 30 years. The implicit expectation was that these units would be replaced at the end of this period with new units that would meet load requirements and, through the use of technological improvements, produce power at lower cost, higher availability and higher efficiency. These expectations have not been realized because of a number of factors that include escalating construction costs, historically high interest rates, siting difficulties, and increasingly uncertain regulatory restraints. Utilities have recognized that the potential lifetime for existing plant may be far in excess of the nominal economic life, and that there are numerous inherent economic and system planning advantages in the continued usage of older plants. Thus, they have increasingly turned to R & M which is life extension method as a way of retaining units in service for 50-60 years or longer. Also these units had increased startups, shutdowns and load swings, and complicates the technical assessment for life extension. Life extension can be broadly defined as a utility program that integrates the long-range planning function with a rigorous program of equipment condition assessment, refurbishment as required, monitoring, and improvement in maintenance and operating procedures. The purpose is typically to extend or improve one or more aspects of plant performance (availability, reliability, or heat rate) in a financially beneficial manner. The useful life of a generating unit is limited by an assumed nominal design or economic life, but by the total cost of retaining the unit in service at some specified reliability relative to the total cost of alternative sources of generation. Consideration of life extension includes the same cost components (capital equipment expenditures, operations and maintenance expenses, fuel costs) as for other generation methods. The integration of performance measures (availability, reliability and heat rate) with the cost factors (capital equipment, operation and maintenance), and with other issues (safety, environmental, regulatory, accounting, rate setting, financial issues, and risks (uncertainty) is required to make logical life extension decisions. The complexity of these decisions requires a commitment of utility planning resources on a par with other utility system decisions.