Improving the Flexibility and Reliability of Steam Power Units at Thermal Power Plants

Information about the research activities conducted at the All-Russia Thermal Engineering Institute (VTI) in the field of flexibility of steam power units at thermal power plants (TPPs) is given. Many of these activities were conducted jointly with specialists of Firm ORGRES, TsKTI, power machinery building works, and power plants. As a result of these activities, thermal cycle and starting process circuits, standardized technologies, and instructions on starting TPP power units for capacities of 200-800 MW and power units of combined heat and power plants (CHPPs) equipped with 100-250-MW turbines have been developed. An important line of activities on substantiating the power equipment's flexibility characteristics was concerned with ensuring the thermal and cyclic strength of highly stressed parts of power-generating boilers and steam turbines, which led to the development of mathematical models of drums and boiler steam superheater outlet headers, steam lines, cylinders, and turbine rotors and the casings of high- and intermediate-pressure valves. Regulatory documents, technical requirements for power unit flexibility, starting fuel loss values, minimum loads and their variation rate within the adjustment range, keeping the power unit in the idle mode and in the mode of supplying power to in-house loads after full load rejection and generator disconnection from the grid, fast turbine valving, and the number of these operations were developed. Efforts aimed at improving the flexibility generated the need to automate the control and develop the appropriate process algorithms, the implementation of which has led to widespread introduction of microprocessor-based automated process control systems. Among the persons who made a great contribution in the arrangement and implementation of these activities were the leading specialists of VTI and the power industry V.B. Rubin, G.I. Moseev, E.R. Plotkin, B.I. Shmukler, A.L. Shvarts, N.I. Davydov, N.F. Komarov, E.N. Sergievskaya, V.F. Rezinskikh, A.Sh. Leizerovich, and others. The fundamental solutions adopted for steam power units were used in the last 20 years in elaborating the technology for starting combined cycle plants equipped with heat recovery steam generators. Among the totality of problems, the article addresses improvement of steam power unit flexibility, one of the basic lines the relevance of which is doubtless also at present.