US3171477A - Heat exchanger using an intermediate liquid - Google Patents

Description

March 2, 1965 A. HUET HEAT EXCHANGER USING AN INTERMEDIATE LIQUID Filed July 3, 1962 IN VENTOR ANDRE HUET ATTORNEY United States Patent Ofiice 3,171,477v Patented Mar. 2, 1965 3,171,477 HEAT EXCHAN GER USING AN INTERMEDIATE LIQUID Andre Huet, 48 Ave. du President Wilson, Paris, France Filed July 3, 1962, Ser. No. 207,276 Claims priority, application France, Sept. 18, 1961, 873,478 2 Claims. (Cl. 165106) For apparatus designed to produce an exchange of heat between two fluids there are generally used nests of tubes through the inside of which there flows one of the fluids, while the other fluid flows over the outside thereof, the exchange of heat being effected through the wall of said tubes.

In the case of viscous fluids having a fouling action, such as those which are encountered, for example, in the petroleum industry, these fluids cause fouling or choking of the tubes of the exchanger at both of their faces and this results in a loss of exchange of heat and the need for frequent cleaning operations interrupting the use of the apparatus. This cleaning is moreover practically impossible where the inside of the tubes is concerned.

The present invention has for its object a heat exchanger specially designed for the exchange of heat between two viscous fluids having a fouling action and in which an intermediate or secondary fluid, for example water, circulating in closed circuit inside nests of tubes is used for transmitting the heat to be exchanged. These tubes are arranged in such manner as to transfer the heat from one of the viscous fluids circulating around a part of the nest of tubes containing the intermediate liquid to the other viscous fluid which it is desired to heat and which circulates around another part of the nest of tubes.

In its practical construction which forms the object of the present invention, the heat exchanger is constituted by half-casings, or small towers, which are superposed in pairs. Inside them are mounted and assembled, in closed circuit, from the lower half-casings to the upper half-casings, the nests of tubes containing the intermediate liquid securing the transfer of the heat. The viscous heating fluid circulates around the nests of tubes of the lower half-casings and the viscous fluid to be heated circulates around the nests of tubes of the upper half-casings. The circulation of the intermediate fluid, for example water, may be effected either by natural circulation or by forced circulation, the water circulating in the nest of tubes of the lower half-casing being heated on contact with the viscous heating fluid, or being vaporised, and passing from there into the nest of tubes of the upper half-casing in which it is cooled or condensed, giving up its heat to the viscous liquid to be heated. It is possible to provide a large number of these half-casings operating in series, or in parallel, in order to achieve all the heat exchange conditions which occur in practice.

The nests of tubes may be produced with the aid of straight tubes or of tubes coiled in helices, which may be either of circular section or of flattened section of lenticular form, the arrangement of these tubes being devised so that the cleaning of their outer surfaces is easy and rapid.

The inside of the tubes of the nests containing the intermediate liquid is never fouled, since this is a liquid such as water, and the cleaning of the apparatus is confined to the outer surfaces of the nests of tubes.

The description which follows with reference to the accompanying drawings, which are given by way of example, will make it better understood how the invention can be carried into effect.

FIG. 1 shows, in partially diagrammatic vertical section a first form of embodiment of a unit forming the object of the invention.

FIG. 2 relates to a modified constructional form;

FIG. 3 shows diagrammatically the arrangement of a plurality of units through which the viscous fluids flow in parallel.

In the form of embodiment shown in FIG. 1, each heat-exchanger unit is composed of two identical jackets or casings a and b in the form of two small superposed columns or towers. Inside each of these columns a, b there are disposed nests of tubes coiled in helices having as their common axis the axis XX of the columns. In the form of embodiment shown, there are three coils c, d, e of tubes in the form of helices through which the intermediate or secondary fluid, which is water, flows in parallel. The tubes of the coils are either of circular section or, as shown in the drawing, of lenticular section, preferably with unequally convex faces. Three coaxial drums or cylinders c, d, 2, preferably having their turns in contact, are thus formed.

In each of the columns a or b an axial header communicates through an expansion turn g with a header h to which the circuits of the cylinders c, d, e are connected in parallel. The headers h are shown with horizontal axes, but could have vertical axes. In the upper portion of the columns, the cylinders c, d, e open into a headeri which could have a vertical axis.

The intermediate or secondary fluid, for example water, flows through the cylinders c, d, e of the lower column, passes through the conduit j to the header 1' of the upper column a, where it flows through the cylinders c, d, e of the column a, and leaving through the lower header 1 of the column a, returns through the conduit k to the lower header of the column b.

Through the column b flows the viscous fluid which is the heating fluid. This fluid arrives, in the direction of the arrow F, at the axial inlet 1 at the top, flows through the column b from top to bottom and issues in the direction of the arrow G at the bottom through the conduit m.

In the upper column a, the viscous fluid to be heated enters the inlet orifice n at the bottom of the lower portion in the direction of the arrow H and issues, in the direction of the arrow I, at the top through the axial conduit 0.

The operation of the apparatus is as follows: the viscous heating fluid circulating through the lower column b from F to G flows around the cylinders c, d, e and gives up its heat to the water circulating in these cylinders, which is heated and vaporised. This water passes through the conduit j into the upper column a and circulates inside the cylinders c, a, e of this column, where it gives up its heat to the viscous fluid to be heated, which enters the column a at H and leaves it at I.

The water flows in closed circuit by natural circulation or else by forced circulation obtained by means of a pump p.

In order to procure the external cleaning of the circuits c, d, e of the upper column a, these circuits are preferably fast with the upper head q of the upper column a, which head is mounted removably. After the intermediate fluid circuit has been cut at r and s, it is possible to withdraw the complete nest of tubes 0, d, e from the casing a. In the case of the lower column b, the assembly of circuits or cylinders c, d, e is fast with the lower head I and, after the intermediate fluid circuit has been cut at u and y, the cylinders c, d, e are withdrawn from the column b at the bottom.

.and arranged in ring form around 'said' axis.

In the form of embodiment shown in FIG. 2, the general arrangement is the same, but the tubes constituting the nests in which the intermediate fluid'circulat'es are rectilinear tubes parallel to the axis XX The circulation of intermediate fluid and the circulation of the viscous fluid are carried out as in the case of FIG. 1;

Likewise, the removal of the nests of tubes c, d, e toenable their external surface to be cleaned is effected as in the case of FIG. 1.

Carrying into effect may comprise, asshown in FIG. 3,

the arrangement in parallel of a plurality of assemblies or units similar to those which have just been described.

The viscous heating fluid circulates in parallel through the lower columns b, in the direction indicated by the arrows, if necessary under the effect'of the'pump we The viscous fluid tobe heated circulates'in parallel through the upper columns a, in the direction indicated by the arrows, if necessary under the ettect of the pump w. Each pair of columns a and b contain the nest of tubes in which flows the intermediate-fluid circulating in closed circuit as indicated in dash lines y in FIG. 3.

I claim: 7 p i 1. A heat exchanger apparatus for exchanging heat between a secondary fluid and viscous fluids having fouling action comprising, a lower, elongated, tubular casing and an upper elongated, tubular casing disposed above the lower casing, a secondary closed circuit in operation for containing therein in operation a secondary fluid comprising an upper and a lower heat transfer tube nest in each of saidcasings respectively extending longitu 4 secondary fluid flows in said lower tube nest generally upwardly and in said upper tube nest generally in an opposite downwardly direction, said lower casing having an upper inlet and a lower outlet for flowing therethrough a viscous fluid in a generally'counter-flow direction to the direction of flow of said secondary fluid for transferring heat therefrom to said secondary fluid, said'up'per casing having a lower inlet and'an upper outlet forvflowing through said lower 'casinga'viscous fluid in a generally counter-flow direction'to'the "general direction of flow of'the secondary fluidflowing through said upper tube nest thereby 'to extract heat from said secondary fluid, said upper casing having an upper heat removable therefrom, said upper tube nestbeing connected to said upper head for withdrawal of the tube nest longitudinally fromthe'upper casing when said head is removed, a tubularfitting slidably mounted in a fluid-tight manner extending through said-upper head and to whichsaid upper tube nest is connected and to which thefirst conduit means is connected, said lower-casing having a removable lower head and means comprising another tubular fitting extending through said lower head in a fluid-tight condition for connecting-the lower tube nest to said lower head for withdrawal of said lower tube nest longitudinally from said lower casing upon removal of said lower head. 7 a a 2. A heat exchanger apparatus according to claim 1,

inwhich each of said casings is internally free of baffles.

dinally therein, conduit means including a tubular fitting extending through the top of said lower casing and slidably'rnounted therein in a fluid-tight condition'connected for flowing secondary fluid from an upper end portion of said lower tube nest of each lower casing to an upper end portion'of said upper tube nest in said upper casing and conduit means including a tubular fitting extending through the, bottom of said upper casing and slidably mounted therein in a fluid-tight condition connected for flowing secondary fluid from a lower end portion of said upper tube nest to a lower end portion of said lower tube vnest thereby to provide a flow path in which said References Cited by the Examiner W UNITED STATES PATENTS 2,595,195

5/52 Arbuckle 165108 2,911,199 1159 Huet 165177 FOREIGNPATENTS r 1,175,619 11/58 France. j 1,224,106 2/60 France. 343,231 2/31 Great Britain.

' 823,904 11/59 Great Britain.

Claims (1)

1. A HEAT EXCHANGER APPARATUS FOR EXCHANGING HEAT BETWEEN A SECONDARY FLUID AND VISCOUS FLUIDS HAVING FOULING ACTION COMPRISING, A LOWER, ELONGATED, TUBULAR CASING AND AN UPPER ELONGATED, TUBULAR CASIG DISPOSED ABOVE THE LOWER CASING, A SECONDARY CLOSED CIRCUIT IN OPERATION FOR CONTAINING THEREIN IN OPERATION A SECONDARY FLUID COMPRISING AN UPPER AND A LOWER HEAT TRANSFER TUBE NEST IN EACH OF SAID CASINGS RESPECTIVELY EXTENDING LONGITUDINALLY THEREIN, CONDUIT MEANS INCLUDING A TUBULAR FITTING EXTENDING THROUGH THE TOP OF SAID LOWER CASING AND SLIDABLY MOUNTED THEREIN IN A FLUID-TIGHT CONDITION CONNECTED FOR FLOWING SECONDARY FLUID FRON AN UPPER END PORTION OF SAID LOWER TUBE NEST OF EACH LOWER CASINGS TO AN UPPER END PORTION OF SAID UPPER TUBE NEST IN SAID UPPER CASING AND CONDUIT MEANS INCLUDING A TUBULAR FITTING EXTENDING THROUGH THE BOTTOM OF SAID UPPER CASING AND SLIDABLY MOUNTEED THEREIN IN A FLUID-TIGHT CONDITION CONNECTED FOR FLOWING SECONDARY FLUID FROM A LOWER END PORTION OF SAID UPPER TUBE NEST TO A LOWER END PORTION OF SAID LOWER TUBE NEST THEREBY TO PROVIDE A FLOW PATH IN WHICH SAID SECONDARY FLUIDS FLOW IN SAID LOWER TUBES NEST GENERALLY UPWARDLY AND IN SAID UPPER TUBE NEST GENERALLY IN AN OPPOSITE DOWNWARDLY DIRECTION, SAID LOWER CASING HAVING AN UPPER INLET AND A LOWER OUTLET FOR FLOWING THERETHROUGH A VISCOUS FLUID IN A GENERALLY COUNTER-FLOW DIRECTION TO THE DIRECTION OF FLOW OF SAID SECONDARY FLUID FOR TRANSFERRING HEAT THEREFROM TO SAID SECONDARY FLUID, SAID UPPER CASING HAVING A LOWER INLET AND AN UPPER OUTLET FOR FLOWING THROUGH SAID LOWER CASING A VISCOUS FLUID IN A GENERALLY COUNTER-FLOW DIRECTION TO THE GENERAL DIRECTION OF FLOW OF THE SECONDARY FLUID FLOWING THROUGH SAID UPPER TUBE NEST THEREBY TO EXTRACT HEAT FROM SAID SECONDARY FLUID, SAID UPPER CASING HAVING AN UPPER HEAT REMOVABLE

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