DE1551445A1 - Heat exchanger - Google Patents

Description

410-12.4llP (12.412H) I6.5.I967

Patent attorney " DIpL-Ing. R. Beetz and 1551445

Dipl.-ing. Lcmprecht

Munich 22, Stelnsdorfrtt. 10

Goßiiaißsariat ä l '& nergie Afcoraique, Paris (France)

Heat exchanger

The invention has a heat exchanger for the subject sur enabling heat exchange between two at risk Bringing way fluids reacting with each other thought and in particular for the evaporation of water by heat exchange with a liquid metal, such as sodium is.

In the case of nuclear power plants, in general and in particular

then, if the reactor is one of the types that work with fast neutrons, the steam generator is heated with liquid sodium, which is the reactor's secondary coolant. As is known, however, the heat exchange between liquid sodium and water raises complicated security problems , in practice it is necessary to eliminate all contact between the two liquids, since they would react violently with one another.

For the production of such steam generators is sometimes used double-exchanger tubes, optionally with 'a circulation of a zwischengeeshalteten Str & mmgsmediums, the j is the detection of burst pipes permitted.

O0IS17 / 0648

8AD

However, systems are extremely expensive, which is why single-walled heat exchangers are preferred today because of their greater economic efficiency which consist of pipes through which liquid sodium flows and into which pipes with a very small cross-section are immersed, in which the water circulates. However, it is necessary to consider the quality of the cables and welded joints used to be able to control in a suitable manner.

The invention therefore proposes a heat exchanger of the type with simple walls which is constructed so that the welds which are simultaneously in contact with the water and the sodium are limited because these internal welds are and are a potential source of danger particularly expensive because of the quality of the controls to be carried out on them. The invention also aims at avoiding the presence of curved water pipes immersed in the sodium, since any curvature can compromise the integrity of the walls of these pipes.

The heat exchanger according to the invention is essentially characterized by:

- A plurality of essentially parallel flow mediums, generally liquid sodium, which are involved in heat exchange, flowed through © lines, each of which is closed at both ends by curved bottoms and alternately transversely running on its side walls near one or the other band , connecting the lines with each other * Rohrstutzen Aufwelsen;

0 Q 9 8 1 1 ^s QS 4 f BAD ORIGINAL

- and by a ζ many times in heat exchange involved flow medium, generally water, through-flow pipes with a very small cross-section, of which each having rectilinear sections extending inside the various ducts which form the bottoms of the Lines through and with each other over outside of the Lines located, circular arc-shaped curved sections are connected.

In the following, a particular embodiment for a heat exchanger according to the invention will be described with reference to FIGS. 1 to 3. However, this description is only to be understood as an example and in no way restricts the scope of the invention. The description refers to a steam generator in which water is heated by liquid sodium , which is the secondary coolant of a nuclear reactor with fast neutrons.

Fig. 1 is a schematic front view of a heat exchanger according to the invention;

Fig. 2 is a side view of the same heat exchanger;

and . -,

Fig. 5 shows details at one end of a line ■. for the sodium.

The steam generator described uses liquid sodium as the heating fluid, which is the secondary coolant of a nuclear reactor with fast neutrons. This secondary coolant is in turn exchanged with the main

BATH ORIGINAL

009817/0646

Coolant of the reactor is heated up, also made of liquid Sodium is made up.

The steam generator consists of several units that resemble each other and are connected in parallel to each other. FIG. 1 shows one of these units and the block of FIG has dx 1 of them. The choice of the number of units results from a compromise between reducing the number the facing pipes and the Qesajnta measurements on the one hand and the possibility of one of the units for to be able to shut down the case of a pipe burst without reducing the exchanged heat output too much on the other side. Each unit is fed with water, one after the other, exchanging heat with that circulating in the opposite direction

liquid sodium is preheated, evaporated and superheated. In addition, reheating for the partially expanded steam is provided in parallel to the superheating zone.

Each group of three building units is located inside a casing 1 made of refractory brick, which normally contains old nitrogen-enriched air. Outside the WäÜffi » This housing contains input collectors 2 and> and 'outlet collector 4 for the sodium, collector 5 for the water / " Collector 6 for the superheated steam, collector 7 for the steam to be superheated again and collector 8 for the steam that is superheated again Steam. The various lines or pipes connected to the collectors are provided with insulating slides on the outside of the housing? 1 lie so that in the event of a Bruotiee each;

009117/06 * 8 ^{BAD 0RK3INAL}

Line and each pipe can be taken out of circulation individually while the rest of the system remains in operation «

Each structural unit consists of substantially horizontally extending lines 10 which are connected in series to input and output Saramler for the sodium. These lines lie one on top of the other and are held in place by a structure 11 made up of bolted beams. Each structural unit also contains tubes 12 with a very small cross-section in which water or steam circulates. In the six lower lines 10 of each structural unit, the preheating and evaporation of the water are carried out. In the upper part there are two rows of four lines 10 each parallel to the sequence © of the six lower lines 10, one being fed from a collector 2 for the sodium * and the other from a collector J for the sodium and the superheater or forms the reheater (Fig. 2). ... , μ.

The lines 10 are at both ends through curved bottoms completed, which are able to withstand the pressure of sodium. They are connected to one another via transverse pipe sockets 14, who alternate at one end and at the other ' of the lines 10 start from their rare wall. The last one The pipe socket at the upper end of the lower lines forming the evaporator is divided into two branches, which carry the sodium for the Lines of the superheater or the lines of the intermediate unit record hitzer. At this height are the lines for the sodium via a pipe 15 'into a safety membrane 16

BAD ORlGiNAt

009117/0646

built in is "connected to a collector 17" which in turn is related to the atmosphere. The membrane 16 protects the device against overpressures «as a result of any Reaction between the water and the sodium could occur.

Each of the tubes 12 for the water or the steam has straight sections 18 ″ which lie parallel to one another in the lines 10. These rectilinear sections traverse the curved bottoms closing off the ends of the lines 10 individually, as is shown in particular in FIG. 3. They are connected to one another outside of the lines 10 via semicircular curved sections 19. Inside the lines, the parallel bores 12 are held in place by grids, which prevent vibrations. ■ *

The device created in this way allows "the appearance of curved parts" that are always awake Place of the system «to report inside the lines transporting the sodium. There is also the Steam under high pressure constantly inside pipes with a relatively small cross-section "which creates a considerable" Savings result from peeling thick tube plates.

SAD ORIGiNAt

009817/0646

Claims (2)

Claims Heat exchangers, in particular for heat exchange between two flow media which react dangerously with one another, such as liquid sodium and water, characterized by a plurality of essentially parallel flow lines (10) through which a first flow medium involved in the heat exchange, generally liquid sodium, flows and through parallel iron "wide flow medium involved in heat exchange, generally water" through-flowing drilling. (12) with a very small cross-section * wmi each of which has straight sections (l8) in the ¥ # i »8ofei« d <& »n lines (10) which lead imgias (HJ) jetftile at both ends through the arched bridge of the @ Baths withstanding the flow medium involved and inte on their side walls; The pipes (10) run up to the ends and have pipe stubs connecting the pipes (10), the straight sections (18) of the pipes (12) flowing through the bottoms of the pipes (lo) and outside the pipes (10) by means of curved joints (19) with one another are connected. 2. Heat exchanger according to claim 1, characterized in that the lines (10) are distributed among each other identical units, which are parallel to each other at common input «and Output samplers for the sodium are connected, the associated tubes (12) parallel to each other with common manifolds for the water and the steam are connected. BATH ORIGINAL 009817/0646 j5. Heat exchanger according to claim 1 or 2, characterized in that each structural unit contains lines (10) one behind the other that form evaporator and superheater and lines (10) parallel to the lines (10) that form superheaters, which form an intermediate superheater, the Pipes (12) are connected to various headers . BAD ORiGiNAIu 009817 / 06A6 Blank page