Siemens Aktiengesellschaft

Wolfgang Kastner

Eberhard Wittchow

Wolfgang Kohler

Wolfgang K&ouml;hler

Konrad Kunstle

A pipe includes a pipe wall having an inner wall surface. Ribs are disposed on the inner wall surface forming a multiple thread. The ribs define a mean inside pipe diameter and the ribs have a lead which is equal to between 0.6 and 0.9 times the square root of the mean inside pipe diameter. Such pipes may be used in a fossil-fuel steam generator, a solar-heated steam generator, or a heated steam generator serving as a waste-heat steam generator, a heat exchanger or a steam generator for absorbing after-heat in a nuclear power plant.

Pipe with ribs on its inner surface forming a multiple thread and steam generator for using the pipe

Method for operating a once-through steam generator and once-through steam generator for carrying out the method

The combustion chamber of a once-through steam generator is formed with walls of vertical tubes through which a flow medium flows from the bottom upwards. The tubes have a surface structure on their inner wall surfaces. Particularly favorable mass flow density m is established in the tubes at the load at which critical pressure prevails in the tubes according to the formula: ##EQU1## wherein q.sub.i is a heat flow density on an inner tube wall surface, T.sub.max is a maximum permissible material temperature of the tubes, T.sub.crit is a temperature of the flow medium at the critical pressure, .DELTA.T.sub.W is a temperature difference between the outer and inner wall surfaces of the tubes, and C is a constant.

Once-through steam generator and a method of configuring a once-through

Steam is generated by conducting a medium through a line which is exposed to solar irradiation. The line has a starting point where a medium supply line issues into the line. The heated medium is conducted away from the at least one line through a drain line. The medium, prior to feeding in at the starting point, is prepared in a power plant component and the medium is supplied at a pressure which is higher than the prevailing pressure in the at least one line, and at an enthalpy which is greater than an enthalpy of saturated water in the line. The medium is fed in as water or water and steam.

Method and device for solar steam generation

In once-through flow steam generators including a burner for fossil fuels and having a vertical gas flue with essentially vertically disposed tubes, inlet ends of the tubes are connected to an inlet header and outlet ends of the tubes are connected to an outlet header. According to the invention, a pressure-equalization tube branches off from each tube at the same height. The tube is connected to a pressure-equalization vessel. The height H is chosen in such a way that in the case of an individual tube being more strongly heated between the inlet header and the branching-off point of the pressure-equalization tube, the mass flow through the individual tube increases as compared to a mean value of the heating of all of the tubes.

Fossil fuel-fired once-through flow stream generator

A once-through steam generator includes tubes together forming combustion chamber walls and carrying fossil fuel burners. The tubes are frequently provided on their inner surfaces with fins forming a multiple thread and are connected parallel to one another for conducting a coolant flow. According to the invention, the internal tube diameter is a function of a quotient, and points determined by pairs of values of the internal tube diameter and of the quotient lie in a coordinate system between a curve and a straight line. A summated mass throughput of all of the tubes at 100% steam output divided by the circumference of the gas flue in a horizontal section through the combustion chamber is used to form the quotient, and four defined points then lie on the curve which has a steady ascending slope. Application of this configuration is advantageously possible even for once-through steam generators having nominal outputs down to far below 500 MW.

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Herzogenaurach, Germany

Wolfgang Kastner