DE19959467B4 - Double tube safety heat exchangers - Google Patents

Abstract

The device for transmission between two fluids (A, B) has in an elongated housing (1) with frontal inflow and outflow chambers (20, 23) for the second fluid (B) two spaced apart (X), one with the first fluid (A) act on exchange space (2) axially bounding first tube sheets (9, 10). In these, the ends (8) of a plurality of mutually parallel, from the first fluid (A) flow around the first exchanger tubes (6) are tightly fixed. These are traversed in the longitudinal direction by the second fluid (B) through which the second exchanger tubes (13) flow. Their ends (14) are tightly fixed in second tube sheets (15, 16), which extend parallel to the first tube sheets (9, 10). Between each with the wall (11) of the exchange space (2) welded first tube sheet (9, 10) and the adjacent second tube sheet (15, 16) is in the longitudinal direction of the wall (11) of the exchange space (2) extending , shell-side compensating element (17) reacting to changes in temperature.

Description

The The invention relates to a double tube heat exchanger according to the features in Preamble of the claim.

The Main applications of such a double tube heat exchanger (DSWÜ) are the cooling of oils as well as the chemical and process technology. Due to the facts, that the 1st exchanger tubes of 2nd exchanger tubes in the longitudinal direction interspersed and on the one hand the first exchanger tubes and on the other hand the 2nd exchanger tubes each with their ends in 1. tube sheets and 2nd tube sheets are tight, is in case of leakage with certainty prevents mixing of the heat exchanging fluids can be done. As a result, a safe operation is achieved. The particular device, the process fluids and the environment will be protected.

Provided the operating and load condition of a DSWÜ as largely uncritical can be considered, the practice in the scope of the prospectus "TECHNICAL DOCUMENTATION DOUBLE TUBE TECHNOLOGY "the Company Renzmann & Grünewald GmbH, Monzingen ago, the mutually adjacent 1st and 2nd tube sheets through Fastening directly to each other. Because due none of the largely uncritical operating and load conditions greater voltages between the adjacent 1st and 2nd tube plates on the one hand and between the double tubes (1st and 2nd exchanger tubes) on the other hand occur can, is no danger for a damage-free operation of the DSWÜ given. Essentially this is usually a stationary operating state.

If however, e.g. at the transient Operation, the expected load is greater, the DSWÜ is also thermal higher and stronger loaded. Also become frequent Approach and departure during the Lifetime of a DSWÜ required. So can it be e.g. in the gas preheating (among other things with natural gas), where as medium to be heated water, steam, oil or hot air is used for supercritical Stress come. In particular, can on arrival and departure the DSWÜ hot or forming cold plugs in the device. It can especially the gas-side connection between the 1st tube sheet and the jacket of the Exchange space between the two first tube sheets with a temperature shock be charged. Also the connections between each one adjacent 1st and 2nd tube bottoms pose critical points represents.

The FR 2 603 693 A1 discloses an apparatus for cooling a liquid sodium heated in a nuclear reactor. These extend between an inflow chamber for cold water and a discharge chamber for water vapor inner tubes. The ends of the inner tubes are welded into plates which separate the chambers from spaces which are exposed to an inert gas, such as nitrogen.

The the inflow chamber with the outflow chamber connecting inner tubes pass through with radial distance outer tubes, which are tightly secured in second panels by welding. The space between the inner tubes and the outer tubes is good due to a heat conductive material, such as in particular porous copper filled. With longitudinal grooves provided pods in the area of the second plates, this material is chambered.

The Liquid sodium is over an annular space and a peripheral opening at the upper end of a cylindrical shell portion introduced, which between the second Plates the outer tubes encloses. The sodium can then be the outer tubes flow around and passes through a peripheral opening at the bottom of the Sheath area cooled in an annulus from which it is returned to the nuclear reactor.

In the wall of the jacket area is integrated with a compensator. Further is a compensator between the wall of the lower annulus and the the lower inflow chamber incorporated limiting plate.

From the DE 1 117 148 B shows a device that largely corresponds to that according to the aforementioned prospectus, only with the difference that the spaces between the first tube sheets and the second tube sheets are dimensioned axially longer.

Of the Invention is - starting from the prior art - the The object of the invention is to provide a double tube safety heat exchanger in which independently from the respective operating and load condition (stationary or transient) one fatigue critical points is avoided.

The solution This object is according to the invention in the features of the claim.

Thereafter, the adjacent first and second tubesheets at the ends of the Doppelrohrsicherheitswärmeübertragers (DSWÜ) specifically arranged at a greater distance from each other. Furthermore, jacket-side compensating elements are welded in between the first tube sheets welded to the wall of the central exchange space and the respectively adjacent second tube sheet. The integration of compensating elements between the first tubesheets and the second tubesheets on the one hand absorbs the temperature-induced expansion between the 1st and 2nd tube plates and on the other hand reduces the risk of shearing off the exchanger tubes at the tubesheets. In other critical load situations, such as natural gas preheaters, the inventive design leads to advantages for safe operation. The range of possible applications of a DSWÜ is increasing, so that in addition to energy technology, applications in chemistry and process technology as well as in other critical operating modes in industry are now manageable.

The Erfindungs divides an optimal design solution, because they both the Thermal loads during heating and shutdown as well as Termperaturschockbedingungen can intercept perfectly. It can Operating conditions up to a pressure of over 200 bar and temperatures from up to 1200 ° C fulfilled without risk of default become. As in heat exchange standing fluids are gaseous, liquid, condensing or vaporizing fluids into consideration.

The Wall thickness of the compensating elements depends on the local Operating conditions, such as pressure, temperature, fluid, etc. from. she must be sized to suit the respective maximum operating loads both on the pipe as can withstand even on the shell side. The length of the compensation elements hangs beside the above conditions as well from the respective mode of operation of the DSWÜ. In particular, the arrival and Downhill situations of the DSWÜ and determine the unsteady operating conditions that occur during operation the dimensions of the compensating elements. These dimensions can be without further be finely fixed by finite element calculations. Thus, the invention in terms of the design of the DSWÜ and in the free choice of operating pressures and temperatures as well as the materials on the tube or shell side very flexible. Material combinations, such as Steel, stainless steel etc. are easily imaginable.

The casing of the DSWÜ is preferably elongated and cylindrical. But it is also conceivable in the Cross-section polygonal housing with the result that the compensation elements then adapt to this contour are.

imaginable is also an embodiment according to which the compensation elements are designed as compensators.

The Invention is described below with reference to a in the drawing schematically illustrated embodiment explained in more detail.

The FIG. 1 shows a vertical longitudinal section half a double tube safety heat exchanger, hereafter referred to as DSWÜ, which used for example in the power plant industry for preheating of oils becomes.

The DSWÜ has an elongated cylindrical housing 1 with a central exchange room 2 that has a connection piece 3 with a first fluid A, for example, water, is applied. The first fluid A then flows through the exchange space 2 along a choked by baffles 4 predetermined, repeatedly deflected according to the arrows PF way and occurs via a connecting piece 5 out again. During his way through the exchange room 4 flows around the 1st fluid A 1. exchanger tubes 6 with ribs on the perimeter 7 are provided. The ends 8th the 1st exchanger tubes 6 are tight in 1st tube sheets 9 . 10 attached, which are arranged at a distance X to each other. The 1st tube sheets 9 . 10 are on the circumference with the cylindrical wall 11 the exchange room 2 welded. The connecting pieces 3 and 5 are in corresponding openings 12 in the wall 11 shrink wrapped.

The 1st exchanger tubes 6 be in the longitudinal direction of 2. exchanger tubes 13 interspersed with their ends 14 in 2nd tube sheets 15 . 16 are tightly fixed. The 2nd tube sheets 15 . 16 extend at a distance L parallel to the 1st tube sheets 9 . 10 ,

The respectively adjacent 1st and 2nd tube sheets 9 . 15 and 10 . 16 are by a longitudinally of the wall 11 the exchange room 2 extending cylindrical, shell-side compensation element 17 through welds 18 connected with each other. The wall thickness D of these compensation elements 17 and its length L1 is determined by finite element calculations depending on the respective operating and loading conditions of the DSWÜ. The compensation elements 17 Thermal loads during heating and shutdown of the DSWÜ as well as the thermal shock conditions are safe.

The through the 1st tube sheet 9 , the 2nd tube sheet 15 and a compensation element 17 formed compensation room 19 is over the 2nd tube bottom 15 with a connection 20 provided for leakage monitoring.

Both the compensation room 19 as well as the through the 1st tube sheet 10 , the 2nd tube sheet 16 and the compensation element 17 limited compensation room 21 can be flooded if necessary with a medium to be determined. The purpose is, in case of damage in the compensation rooms 19 . 21 to introduce a neutralizing medium, eg nitrogen, in order to lower the ignition limit (for combustible gases) or to create an overall neutral atmosphere.

The 2nd tube sheets 15 . 16 each limit an inflow chamber on the opposite sides 22 and a downstream chamber 23 for the second fluid B in the form of z. B. natural gas. The 2nd fluid B flows through a connecting piece 24 in the inflow chamber 22 , flows through the 2nd exchanger tubes 13 , arrives in the area of the exchange space 2 in a heat exchanging indirect contact with the first fluid A and then enters the outflow chamber 23 from where the second fluid B is sent for further use.

The inflow chamber 22 is from one with the 2nd tube sheet 15 welded wall 25 , the 2nd tube sheet 15 and one by screws 26 releasably arranged lid 27 limited, on an annular flange 28 is fixed, which with the wall 25 is welded.

It can also be seen that the inflow chamber 22 through partitions 29 is divided into chamber sections. The connecting piece 24 is in an opening adapted to it 30 in the wall 25 shrink wrapped.

The outflow chamber 23 is from the 2nd tube sheet 16 and a domed lid 31 limited by screws 32 on the 2nd tube sheet 16 is releasably attached.

1

casing

2

exchange space

3

spigot

4

Harassment in 2

5

spigot

6

1. exchanger tubes

7

Ribs on 6

8th

Ends of 6

9

1. tube sheet

10

1. tube sheet

11

Wall of 2

12

Openings for 3 and 5 in 11

13

Second exchanger tubes

14

Ends of 13

15

Second tube sheet

16

Second tube sheet

17

compensating elements

18

welds

19

compensation space

20

connection

21

compensation space

22

inflow chamber

23

current chamber

24

spigot

25

Wall of 22

26

Screws for 27

27

Lid of 22

28

annular flange

29

chamber sections

30

Opening in 25

31

Lid of 23

32

Screws for 31

DSWÜ

Double tube safety heat exchangers

A

fluid

B

fluid

D

Wall thickness of 17

L

distance between 9 and 15 respectively. 10 and 16

L1

length of 17

PF

arrows

X

Distance from 9 and 10

Claims (1)

Double tube safety heat exchanger, which in an elongated housing ( 1 ) with frontal inflow and outflow chambers ( 22 . 23 ) for a second fluid (B) two at a distance (X) to each other, one with a first fluid (A) acted upon and with welded baffles ( 4 ) exchange space ( 2 ) axially delimiting 1. tube sheets ( 9 . 10 ), in which the ends ( 8th ) of a plurality of mutually parallel, of the first fluid (A) flows around, circumferentially finned 1. exchanger tubes ( 6 ) are fixed in the longitudinal direction of the second fluid (B) flows through the second exchanger tubes ( 13 ) are interspersed, whose ends ( 14 ) in 2nd tube sheets ( 15 . 16 ) are tightly fixed, which are parallel to the first tube sheets ( 9 . 10 ), characterized in that between each at its periphery with the cylindrical wall ( 11 ) of the exchange space ( 2 ) by welds ( 18 ) connected to the first tube sheet ( 9 . 10 ) and the respectively adjacent second tubesheet ( 15 . 16 ) in the longitudinal direction of the wall ( 11 ) of the exchange space ( 2 ) extending, to temperature changes of the adjacent first tube sheet ( 9 . 10 ) and second tube bottom ( 15 . 16 ) reactive shell-side compensation element ( 17 ), the circumference of the second tube sheets ( 15 . 16 ) by welds ( 18 ), wherein the wall thickness (D) of the compensating element ( 17 ) and its length (L1) is determined by finite element calculations depending on the respective operating and loading conditions of the double tube safety heat exchanger.