A boiler system for producing steam from water includes a plurality of serially arranged oxy fuel boilers. Each boiler has an inlet in flow communication with a plurality of tubes. The tubes of each boiler form at least one water wall. Each of the boilers is configured to substantially prevent the introduction of air. Each boiler includes an oxy fuel combustion system including an oxygen supply for supplying oxygen having a purity of greater than 21 percent, a carbon based fuel supply for supplying a carbon based fuel and at least one oxy-fuel burner system for feeding the oxygen and the carbon based fuel into its respective boiler in a near stoichiometric proportion. The oxy fuel system is configured to limit an excess of either the oxygen or the carbon based fuel to a predetermined tolerance. The boiler tubes of each boiler are configured for direct, radiant energy exposure for energy transfer. Each of the boilers is independent of each of the other boilers.

A back-up boiler system for a solar thermal power plant (201) for transferring solar energy into electricity, said back-up boiler system comprising a combustion chamber (70) and a convection section (80) in fluid connection with said combustion chamber (70), wherein in the convection section (80) at least a first heat exchanger (92) is provided for heating a molten salts mixture of the solar thermal power plant and a second heat exchanger (90) for pre-heating boiler feed water of the solar thermal power plant, wherein the back-up boiler system (25) is configured to allow selection between only providing heat to the first heat exchanger (92), only providing heat to the second heat exchanger (90) and providing heat to both heat exchangers (90, 92), preferably dependent on availability of solar radiation and/or dependent on demand of power generation. The invention also relates to a solar thermal power plant (201) for transferring solar energy into electricity and a method for operating a solar thermal power plant.

A back-up boiler system for a solar thermal power plant (201) for transferring solar energy into electricity, said back-up boiler system comprising a combustion chamber (70) and a convection section (80) in fluid connection with said combustion chamber (70), wherein in the convection section (80) at least a first heat exchanger (92) is provided for heating a molten salts mixture of the solar thermal power plant and a second heat exchanger (90) for pre-heating boiler feed water of the solar thermal power plant, wherein the back-up boiler system (25) is configured to allow selection between only providing heat to the first heat exchanger (92), only providing heat to the second heat exchanger (90) and providing heat to both heat exchangers (90, 92), preferably dependent on availability of solar radiation and/or dependent on demand of power generation. The invention also relates to a solar thermal power plant (201) for transferring solar energy into electricity and a method for operating a solar thermal power plant.

A steam turbine includes a boiler unit, first supply pipes, a second supply pipe, a plurality of valve units, a drain valve unit, and a controller. The controller is configured to control, before rotation of the turbine starts, an operation time and temperature of the auxiliary boiler so that the temperatures of the high-pressure turbine and the intermediate-pressure turbine are increased to the first setting temperature. The controller is configured to control, when the temperatures of the high-pressure turbine and the intermediate-pressure turbine are maintained at the first setting temperature, operation of the main boiler such that the temperature of the intermediate-pressure turbine reaches a second setting temperature while operation of the auxiliary boiler is interrupted, and control, when the temperature of the intermediate-pressure turbine is maintained at the second setting temperature, the operation of the main boiler such that steam is supplied only to the high-pressure turbine.

A steam turbine includes a boiler unit, first supply pipes, a second supply pipe, a plurality of valve units, a drain valve unit, and a controller. The controller is configured to control, before rotation of the turbine starts, an operation time and temperature of the auxiliary boiler so that the temperatures of the high-pressure turbine and the intermediate-pressure turbine are increased to the first setting temperature. The controller is configured to control, when the temperatures of the high-pressure turbine and the intermediate-pressure turbine are maintained at the first setting temperature, operation of the main boiler such that the temperature of the intermediate-pressure turbine reaches a second setting temperature while operation of the auxiliary boiler is interrupted, and control, when the temperature of the intermediate-pressure turbine is maintained at the second setting temperature, the operation of the main boiler such that steam is supplied only to the high-pressure turbine.

A feedwater heater (10) for a steam generator communicating feedwater through an external heat exchanger (12), a deaerator (14) that allows the use of carbon steel feedwater tubes, a first heater (16), an evaporator section (18) and steam drum (17) for communicating a portion of the feedwater in the form of steam to the deaerator (14), and a second heater (20).

A steam utilization system for producing a concrete pipe pile includes a steam conveying device, a steam curing pool, a plurality of reaction vessels, a steam generating device, a first steam distributor, a first pressure booster, a second pressure booster and a blowdown flash tank. A high-pressure steam inlet of the first steam distributor is communicated with the steam generating device, and a first steam inlet of the first pressure booster is communicated with a first high-pressure steam outlet of the first steam distributor. A second steam inlet of the first pressure booster is communicated with the steam conveying device, the steam outlet of the first booster is communicated with the steam inlet of each reaction vessel, a first steam inlet of a second pressure booster is communicated with the first steam distributor, a second steam inlet of the second pressure booster is communicated with the blowdown flash tank.