Vereinigte Edelstahlwerke Aktiengesellschaft

Other

Vereinigte Delstahlwerke Ag. (vew)

Gundolf E Rajakovics

Heinz Gabernig

Guenter Peter Klein

Gunter Peter Klein

The apparatus comprises a first chamber in which there is present a gaseous or vaporous medium under pressure and a second chamber which is predominantly filled with a liquid medium under a pressure independent from the pressure in the first chamber. In addition to these two chambers an intermediate chamber is filled in normal operation with substantially the same gaseous or vaporous medium at substantially the same pressure as present in the first chamber. The first chamber is connected through ducts via the intermediate chamber with the second chamber and at normal operation an unavoidable predetermined pressure drop is caused between said intermediate chamber and said second chamber. The pressure regulation is effected by a piston-operated shut off device adapted to assume an open and a closed position which device is disposed between the first and second chamber. The pressure present in the second chamber through the duct means will act on one end of the piston by means of the liquid medium present in the second chamber. The shut-off device is thereby moved into the normal open position. The pressure present in the first chamber by means of the connecting duct acts on the other end of the piston and will cause the shut-off device to move into the closed position if the pressure differential between the two pressures exceeds the predetermined pressure drop by a predetermined value. This will close the shut-off device and thus prevent an overrun from the first into the second chamber because of an excessive pressure drop in the second chamber.

Apparatus for the purpose of avoiding pressure drop between a gaseous or

An improved technique employing first and second flash vaporization stages for purifying radioactive liquids is described. The liquid is first flash-evaporated in the first vaporization stage and the resulting vapor is conducted to a first direct condenser. Enriched liquid obtained from the second vaporization stage is applied via a circulating pump to the first direct condenser to condense by contact the vapor from the first vaporization stage and to form a mixture with this condensate. The resulting mixture is thus flash-evaporated in the second vaporization stage. A portion of the enriched liquid obtained from the second vaporization stage is withdrawn from the loop formed by said second vaporization stage, said circulating pump, said first direct condenser, and the connecting conduits therebetween for further processing, e.g., recycling to the first vaporization stage, or for discharging.

Two-step flash technique for vaporizing radioactive liquids

In the disclosed thermal power plant an alkali metal vapor energy conversion circuit is arranged in heat transfer relationship with an additional circuit whose working medium does not vigorously react with alkali metal. Diphenyl, terphenyl are disclosed as suitable media. The additional circuit may in turn be in heat transfer relationship with a steam circuit, in which event the additional circuit is interposed between the alkali metal energy conversion circuit and the water vapor (steam) circuit. The upper process temperature of the interposed energy conversion circuit is between about 420.degree. and 480.degree. C, preferably between 440.degree. and 470.degree. C. The transfer of the heat from the interposed circuit to the water vapor circuit preferably takes place in a temperature range in which the absorption by the water vapor circuit proceeds substantially isothermally.

Thermal power plants and method of operating a thermal power plant

A process and installation for vaporizing liquids and in particular radioactive liquids. A two-step flash vaporization is carried out. The vapor exiting from a first vaporizing stage is condensed by means of liquid taken from a second vaporizing stage, the latter liquid being injected into a condenser into which the vapor steam from the first vaporizing stage is being conducted. The thus formed mixture is conducted into the second vaporizing stage.

Process and arrangement for vaporizing of liquids

A float valve arrangement is disposed in a mixing condenser that is arranged intermediate the first and second stage of a two-stage evaporation installation suitable for purifying radio-active liquids. In normal operation, vapor evaporated in the first stage extends via a first conduit into the mixing condenser where such vapor is condensed by contact with a portion of the liquid in the second stage that is circulated back to the mixing condenser via a pump. The normal vapor pressure generated in the first stage keeps the float valve open and permits the steam to displace, into the second stage, liquid present in the mixing condenser. During start-up and shutdown of the installation wherein vapor from the first stage is no longer present, the resulting rise in liquid level in the mixing condenser causes the float valve to close and to prevent any backflow of liquid into the first stage via the first conduit.

Arrangement for preventing undesired fluid backflow during start-up and

Distillate produced by the condensing stage of an evaporation installation is conducted to a reservoir to be preheated to its boiling point in preparation for a further degassing step. The required rise in temperature of the distillate in the reservoir is effected by the heat of condensation of a portion of the steam directed via a main pipe from the evaporating stage of the installation to the condensing stage. The required contacting of such steam portion with the reservoir is effected by diverting, to the reservoir, a portion of the steam in the main pipe via a diaphragm or another blocking member interposed in the main pipe and a branch pipe that communicates with the main pipe upstream of the diaphragm member and extends to the reservoir. A conventional overflow pipe disposed at a predetermined height in the reservoir is effective to conduct the heated distillate to the subsequent degassing stage.

Method and apparatus for preheating distillate to be degassed

An improved arrangement is described for self-controlling the evaporation rate in the first stage of a two-stage expansion type evaporation installation for radio-active liquid purification, as described e.g. in the U.S. patent application Ser. No. 328065 filed on Jan. 30, 1973, in case of failure of the main circulating pump of the second stage. Such failure causes a pressure drop at the mixing condenser between first and second stage and normally, thus, a pressure drop in the first stage too. Such pressure drop leads to unwanted evaporation in the first stage and transfer to the second stage of excessive and insufficiently purified fluid from the first stage. A flow throttle element such as a diaphragm or a necked-down section of steam conduit is interposed between the vapor exit of the first stage and the mixing condenser in which the vapor is condensed by contact with a portion of the liquid from the second stage circulated therethrough by the pump. Any tendency of the amount of liquid evaporating in the first stage to unduly increase due to a pressure drop caused by pump failure of the second stage results in a corresponding increase of the pressure difference across the flow throttle element so that the pressure in the first stage does not decrease by the same amount as in the mixing condenser, thus preventing undue increase of the evaporation rate in the first stage.

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Vienna, Austria

Gundolf E Rajakovics