Increasing average temperature of heat supply in steam turbine plant by mixing steam after overheaters with products of combustion of natural gas in the oxygen. Development of this idea consists in maintaining steam temperature on the major part of expansion in the turbine at level, close to initial temperature. Increasing efficiency of gas turbine plant by way of regenerative heating of the air by gas after its expansion in high pressure turbine and before expansion in the low pressure turbine. Due to this temperature of air, entering combustion chamber, is increased and average temperature of heat supply is consequently increased. At the same time average temperature of heat removal is decreased. Increasing efficiency of combined cycle power plant by avoiding of heat transfer from gas to wet steam and transferring heat from gas to water and superheated steam only. Steam will be generated by multi stage throttling of the water from supercritical pressure and temperature close to critical, to the pressure slightly higher than condensation pressure. Throttling of the water and separation of the wet steam on saturated water and steam does not require complicated technical devices. Introduction.Steam, gas and combined cycle turbine power plants are generating major part of the energy used by humanity. Thus increase of their efficiency is important. Steam turbine plants are characterized by high thermodynamical efficiency for achievable maximum temperature of steam but relatively low values of this maximum temperature. Gas turbine plants are characterized by high values of maximum temperature of working substance due to direct combustion of fuel in the stream of the working substance (compressed air which turns into gas in combustion chamber) but high temperature of exhaust gas which means high average temperature of heat removal in the cycle. Combined cycle power plants are incorporating positive features of steam and gas turbine power plants, however transfer of substantial part of the heat from gas to steam causes substantial losses of efficiency due to irreversibility of heat transfer processes.

This paper describes two methods of increasing steam turbine plants efficiency by raising average temperature of heat supply in thermodynamic cycle. In the first method it is proposed to raise maximum temperature of steam in the cycle by mixing steam, exiting from super-heater of boiler, with products of combustion of methane in oxygen. In the second method it is proposed to raise maximum temperature of working substance and to continue heat supply on major part of expansion process in the turbine in order to make it quasi isothermal. This is done by mixing steam, exiting from super-heater of boiler, with products of combustion of hydrogen in oxygen and excess of hydrogen. Combustion of hydrogen during expansion in the turbine due to gradual admixing of oxygen to the working substance will produce heat required for quasi isothermal expansion. Methods yields increase in effective efficiency 7.9 and 18.8% respectively. Repayment term of modified plants will be 3.8 years for first method and 2.8 years for the second. Implementation of either of these methods will result in output of considerable quantities of pure carbon dioxide, which can be utilized or buried thus reducing its release into atmosphere.