CS218824B1 - Inverted double-walled steam generator with sodium heat carrier - Google Patents

Abstract

In the embodiment according to the invention, the double heat exchange tubes are formed by outer protective tubes and inner supporting tubes; wherein the protective tubes are fixed to a protective tube sheet having a thickness of 1 and the supporting tubes to a supporting tube sheet having a thickness of m and between the thicknesses of the tube sheets m < 1 holds. The outer protective tubes are further provided with outer ribs and also channels indicating leakage. The inner supporting tube is also provided with similar channels. The invention can be used in nuclear power.

Description

(54) Inverted double-walled steam generator with sodium heat carrier

In an embodiment of the invention, the double heat exchange tubes are formed by outer protective tubes and inner support tubes; wherein the protective tubes are fixed to a protective tube sheet having a thickness of 1 and the supporting tubes to a supporting tube sheet having a thickness of m and m <1 between the tube sheet thicknesses. The outer protective tubes are further provided with external ribs as well as leak indicating channels. The inner support tube is provided with similar channels. The invention can be used in nuclear power.

BACKGROUND OF THE INVENTION The present invention relates to an inverted double-walled, sodium heat-carrying steam generator for maximum operational safety.

Presently, direct sodium steam generators are proposed, ie in which sodium flows in the inter-tube space and water or steam in the heat exchange tubes, with a double-walled heating surface composed of two smooth tubes fitted to each other tightly or with little clearance and delimitation of this clearance or so that on the outer surface of the inner tube or on the inner surface of the outer tube there are channels for indicating fluid, which may be either sodium or indicator gas, for example helium, air, argon, etc.

The disadvantage of the direct steam generators with the so-called sodium indication is that the leak indication is not reliably solved. In the cell type steam generators with a plurality of heat exchanger tubes, the indicating sodium is concentrated and thus the possible products of the reaction of sodium with water in the inlet or outlet piping or even in the buffer tank Nu.

Another disadvantage of direct steam generators with a so-called gas indication, such as helium indication, is that the colder medium, ie water or steam flowing in the heat exchange tubes, and the warmer medium, ie sodium flowing in the inter-tube space, cause The temperature difference between the outer and inner tubes increases, which leads to an increase in the thickness of the indication space between the tubes, but mainly to an increase in the thermal resistance, i.e. a reduction in the heat transfer coefficient. This is reflected in the design of the steam generator by increasing its weight and hence the investment costs.

The above-mentioned disadvantages are overcome by the inverted double-walled, sodium heat-carrying steam generator according to the invention, characterized in that the double heat exchange tubes are formed by outer protective tubes and inner supporting tubes, the protective tubes being fixed to a protective tube sheet having a support tube sheet having a thickness m, and between the thicknesses of the tube sheets, m < 1.

Sodium, i.e., the warmer medium, flows inside the inner heat exchange tube, water or steam, i.e., the colder medium, flows in the inter-tube space, resulting in a decrease in the thickness of the indicating space due to thermal expansion of the tubes and thereby reducing heat resistance as the steam generator increases. The heating surface formed by the double-walled tube may be provided with leak-indicating channels either on the inner surface of the outer protective tube or on the outer surface of the inner tube.

When using tubes with leakage indication channels on the outer protective tube, the arrangement has a distinctive character with a supporting inner tube and a protective outer tube, which may have fins on its surface for intensifying heat transfer, which is particularly advantageous for nuclear power.

The outer protective tubes are fixed to the protective tube sheet, the internal supporting tubes are fixed to the supporting tube sheet, and for manufacturing reasons in particular it is advantageous to make the supporting tube sheet smaller than the protective tube sheet which is expected to be dimensioned for water or steam temperature and pressure. .

An exemplary embodiment of the invention is shown in the accompanying drawings, in which Figures 1, 2, 3 are cross-sections of double heat exchange tubes of a steam generator according to the invention and Figure 4 is a longitudinal section of an arrangement of double heat exchange tubes in a tube sheet of a steam generator according to the invention.

As can be seen from FIG. 1, the inner support tube 1 is in close contact with the outer protective tube 3 on the outer surface being provided with outer ribs 5 in a longitudinal or helical configuration.

Ubi 2 shows an arrangement with an inner support tube 1 which is in close contact with an outer protective tube 3 provided with outer ribs 5 in a longitudinal or helical manner. and leakage indication channels 6 on the inner surface.

Giant. 3 shows an arrangement with an inner support tube 1 provided with channels 2 for leak indication.

As can be seen from Fig. 4, the inner support tube 1 is fixed to the support tube plate 8, the outer protective tube 3 is fixed to the protective tube plate 7.

The protective tube plate 7 and the supporting tube plate 8 can be joined, for example, by welding.

Claims (4)

SUBJECT An inverted double-walled steam generator with a sodium heat carrier in which sodium flows inside the heat exchange tubes and water and steam outside the double heat exchange tubes, characterized in that the double heat exchange tubes consist of outer protective tubes (3) and inner support tubes (1j), the protective tubes (3) are fastened to the protective tube sheet (7) having a thickness of 1 and the supporting tubes (1) to the supporting tube sheet (8) having a thickness m and m <1 between the thicknesses of the tube sheets. 2. Inverted double-walled steam generator A sodium heat carrier according to claim 1, characterized in that the outer protective tubes (3) are provided with outer fins (5). An inverted double-walled steam generator with a sodium heat carrier according to items 1 and 2, characterized in that the outer protective tubes (3) are provided with leak-indicating channels (6). 4. An inverted double-walled, sodium heat-carrying steam generator according to items 1 and 2, characterized in that the inner support tube (Γ) is provided with leak-indicating channels (2).