Heat exchanger, combination with heat exchanger and method of manufacturing the heat exchanger

Abstract

A heat exchanger for heat exchange between a first and a second fluid and comprising a cylindrical casing 2 , a cylindrical fluid conduit 5 arranged inside the casing such that an axially extending tubular space 8 is defined, at least one helical coil 9, 10 of a finned or corrugated tube being arranged inside the tubular space, and adjustable throttle means 17, 17 a , 18 adapted and arranged for adjustably throttling flow of the first fluid through the conduit 5 to adjust the flow of the first fluid through the conduit and the first tubular space for adjusting the heat exchange between the first fluid and the second fluid flowing through the helical coils 9, 10.

1 . A heat exchanger for heat exchange between a first fluid and a second fluid and comprising: 
 a generally cylindrical casing with a first inlet and a first outlet for allowing said first fluid to flow through said casing in a generally axial direction,    a generally cylindrical fluid conduit arranged inside said casing generally coaxial therewith so that an axially extending first tubular space is defined between said conduit and said casing, said conduit having a second inlet and a second outlet for allowing said first fluid to flow through said conduit in a generally axial direction, and said first tubular space having a third inlet and a third outlet for allowing said first fluid to flow through said tubular space in a generally axial direction,    at least one helical coil comprising a tube selected from the group consisting of a finned tube and a corrugated tube arranged inside said first tubular space generally coaxial therewith and having a fourth inlet and a fourth outlet for allowing said second fluid to flow through said tube.    
   
   
       2 . A heat exchanger according to  claim 1  further comprising first adjustable throttle means for adjustably throttling said flow of said first fluid through said conduit and second adjustable throttle means for adjustably throttling said flow of said first fluid through said first tubular space.  
   
   
       3 . A heat exchanger according to  claim 2 , wherein said first throttle means comprise a first butterfly valve, arranged adjacent one of said second inlet and said second outlet, and said second throttle means comprise a second butterfly valve, arranged adjacent one of said third inlet and said third outlet.  
   
   
       4 . A heat exchanger according to  claim 2 , wherein said first throttle means comprise a first butterfly valve, arranged adjacent one of said second inlet and said second outlet, and said second throttle means comprise a ring having planar dimensions corresponding to the cross section of said first tubular space and being arranged for being displaced from a heating position wherein said flow of first fluid through said tubular space is substantially unhindered to a bypass position wherein said flow is substantially obstructed.  
   
   
       5 . A heat exchanger according to  claim 2 , wherein said first and second throttle means comprise: 
 a fixedly arranged stationary plate with first and second apertures provided therein arranged such that said second and third inlets or outlets are obstructed by said plate such that the flow of first fluid through said conduit and said first tubular space takes place through said first and second apertures, respectively, in said stationary plate, and    at least one movable plate with third and fourth apertures provided therein and arranged so as to be displaceable from a bypass position overlying said stationary plate, wherein said third apertures coincide with said first apertures and said fourth apertures do not coincide with said second apertures, to a heating position overlying said stationary plate wherein said fourth apertures coincide with said second apertures and said third apertures do not coincide with said first apertures.    
   
   
       6 . A heat exchanger according to any of the claims  2 - 5  and further comprising actuating means for adjusting the throttling effect of said first and second throttle means.  
   
   
       7 . A heat exchanger according to  claim 6 , wherein said throttling means and said actuating means are adapted such that substantially any rate of flow between a maximum and minimum rate of flow of said first fluid through said second inlet and said third inlet may be obtained.  
   
   
       8 . A heat exchanger according to  claim 7 , wherein said minimum rate is substantially equal to zero.  
   
   
       9 . A heat exchanger according to  claim 1  and comprising at least two coil arranged concentrically and such that mutually adjacent coils are radially spaced such that an axially extending second tubular space is provided between said mutually adjacent coils.  
   
   
       10 . A heat exchanger according to  claim 1 , wherein the outer surface of said conduit is spaced radially from the coil adjacent said surface such that an axially extending third tubular space is provided between said surface and said adjacent coil.  
   
   
       11 . A heat exchanger according to  claim 9  or  10 , wherein the radial dimensions of said second and third tubular spaces are adapted so as to achieve a certain pressure loss for a given rate of flow of said first fluid through said first tubular space.  
   
   
       12 . A heat exchanger according to  claim 1 , wherein the coil has mutually adjacent individual windings that are mutually axially spaced such that a helically extending space is provided between said adjacent windings.  
   
   
       13 . A heat exchanger according to  claim 1  and comprising three or more helical coils arranged concentrically, each comprising a finned tube one of the coils being an innermost coil and another of the coils being an outermost coil, the interior diameter of the finned tubes constituting the coils being the same, wherein third throttling means are provided in the tubes constituting the coils located radially inwards of the outermost coil for increasing the pressure loss through the tubes of the remaining coils so as to compensate for the shorter length of said tubes relative to the length of the tubes of the outermost coil such that the rate of low of said second fluid through the tubes of all the coils is substantially the same for a given uniform pressure in said second fluid at said fourth inlets.  
   
   
       14 . A heat exchanger according to  claim 13 , wherein said third throttling means are constituted by a reduction of the cross sectional area of the flow of said second fluid relative to the internal cross sectional area of said tubes.  
   
   
       15 . A heat exchanger according to  claim 14  and further comprising an inlet header tube and an outlet header tube in fluid communication with said fourth inlets and fourth outlets, respectively, of all said tubes through corresponding communication apertures in said header tubes, said reduction of flow cross sectional area being constituted by reduced size of said communication apertures in one of said inlet header tube and said outlet header tube.  
   
   
       16 . A heat exchanger according to  claim 1 , wherein the helical coil comprises two or more helically wound finned tubes extending adjacent one another with the same pitch.  
   
   
       17 . A combination of a heat exchanger according to  claim 1  and an exhaust gas generating combustion means selected from the group consisting of at least one of a natural gas fired turbine, an internal combustion engine, a furnace, a burner, an incinerator, the combination comprising interconnection means for interconnecting an exhaust gas outlet of the combustion means with said second and third inlets of the heat exchanger such that said exhaust gas constitutes said first fluid.  
   
   
       18 . A combination according to  claim 17  and further comprising 
 heat exchanging means for heat exchange between said second fluid and at least one of a third fluid and the surroundings of said heat exchanging means, said heat exchanging means being in fluid communication with said fourth outlet,    measuring means for measuring the rate of heat exchange of said heat exchanging means,    signal output means for emitting a signal representing the result of a measurement carried out by said measuring means, and    first control means for controlling the adjustment of said first and second throttle means and adapted for receiving said signal.    
   
   
       19 . A combination according to  claim 17  or  18  and further comprising second control means for controlling the adjustment of said first throttle means such that the throttling effect thereof is at a minimum during the start up phase of the combustion means.  
   
   
       20 . A combination of a heat exchanger for heat exchange between a first fluid and a second fluid and an exhaust gas generating combustion means, the heat exchanger comprising: 
 a generally cylindrical casing with a first inlet and a first outlet for allowing said first fluid to flow through said casing in a generally axial direction,    a generally cylindrical fluid conduit arranged inside said casing generally coaxial therewith so that a axially extending first tubular space is defined between said conduit and said casing, said conduit having a second inlet and a second outlet for allowing said first fluid to flow through said conduit in a generally axial direction, and said first tubular space having a third inlet and a third outlet for allowing said first fluid to flow through said tubular space in a generally axial direction, and    at least one helical coil comprising a tube selected from the group consisting of a finned tube and a corrugated tube arranged inside said first tubular space generally coaxial therewith and having a fourth inlet and a fourth outlet for allowing said second fluid to flow through said finned tube,    the combination comprising interconnection means for interconnecting an exhaust gas outlet of the combustion means with said second and third inlets of the heat exchanger such that said exhaust gas constitutes said first fluid.    
   
   
       21 . A combination according to  claim 20  further comprising first adjustable throttle means for adjustably throttling said flow of said first fluid through at least one of said conduit and second adjustable throttle means for adjustably throttling said flow of said first fluid through said first tubular space.  
   
   
       22 . A combination according to  claim 21 , wherein said first throttle means comprise a first butterfly valve, arranged adjacent one of said second inlet and said second outlet, and said second throttle means comprise a second butterfly valve, arranged adjacent one of said third inlet and said third outlet.  
   
   
       23 . A combination according to  claim 21 , wherein said first throttle means comprise a first butterfly valve, arranged adjacent said one of second inlet and said second outlet, and said second throttle means comprise a ring having planar dimensions corresponding to the cross section of said first tubular space and being arranged for being displaced from a heating position wherein said flow of first fluid through said tubular space is substantially unhindered to a bypass position wherein said flow is substantially obstructed.  
   
   
       24 . A combination according to  claim 21 , wherein said first and second throttle means comprise: 
 a fixedly arranged stationary plate with first and second apertures provided therein arranged such that either said second and third inlets or said second and third outlets are obstructed by said plate such that the flow of first fluid through said conduit and said first tubular space takes place through said first and second apertures, respectively, in said stationary plate, and    at least one movable plate with third and fourth apertures provided therein and arranged displaceable from a bypass position overlying said stationary plate, wherein said third apertures coincide with said first apertures and said fourth apertures do not coincide with said second apertures, to a heating position overlying said stationary plate wherein said fourth apertures coincide with said second apertures and said third apertures do not coincide with said first apertures.    
   
   
       25 . A combination according to  claim 21  and further comprising actuating means for adjusting the throttling effect of said first and second throttle means.  
   
   
       26 . A combination according to claims  21 , wherein said throttling means and said actuating means are adapted such that substantially any rate of flow between a maximum and minimum rate of flow of said first fluid through said second inlet and said third inlet may be obtained.  
   
   
       27 . A combination according to  claim 26 , wherein said minimum rate is substantially equal to zero.  
   
   
       28 . A combination according to  claim 21  and comprising two or more helical coils arranged concentrically and such that mutually adjacent coils are radially spaced such that an axially extending second tubular space is provided between said mutually adjacent coils.  
   
   
       29 . A combination according to  claim 21 , wherein the outer surface of said conduit is spaced radially from the coil adjacent said surface such that an axially extending third tubular space is provided between said surface and said adjacent coil.  
   
   
       30 . A combination according to  claim 28 , wherein the radial dimension of said second tubular space is adapted so as to achieve a certain pressure loss for a given rate of flow of said first fluid through said first tubular space.  
   
   
       31 . A combination according to  claim 29 , wherein the radial dimension of said third tubular space is adapted so as to achieve a certain pressure loss for a given rate of flow of said first fluid through said first tubular space.  
   
   
       32 . A combination according to  claim 21 , wherein the mutually adjacent individual windings of a coil are mutually axially spaced such that a helically extending space is provided between said adjacent windings.  
   
   
       33 . A combination according to  claim 21  and comprising three or more helical coils arranged concentrically, one of said coils being an outermost coil, each of the coils comprising a finned tube, the interior diameter of the finned tubes being the same, wherein third throttling means are provided in the tubes of the coils located radially inward of the outermost coil for increasing the pressure loss through the tubes of said radially inward located coils so as to compensate for the shorter length of said tubes of said radially inward located coils relative to the length of the tubes of the outermost coil such that the rate of low of said second fluid through the tubes of all the coils is substantially the same for a given uniform pressure in said second fluid at said fourth inlets.  
   
   
       34 . A combination according to  claim 33 , wherein said third throttling means are constituted by a reduction of the cross sectional area of the flow of said second fluid relative to the internal cross sectional area of said tubes.  
   
   
       35 . A combination according to  claim 34  and further comprising an inlet header tube and an outlet header tube in fluid communication with said fourth inlets and fourth outlets, respectively, of all said tubes through corresponding communication apertures in said header tubes, said reduction of flow cross sectional area being constituted by reduced size of said communication apertures in one of said inlet header tube and said outlet header tube.  
   
   
       36 . A combination according to  claim 21 , wherein a helical coil comprises two or more helically wound finned tubes extending adjacent one another with the same pitch.  
   
   
       37 . A combination according to  claim 21  and further comprising 
 heat exchanging means for heat exchange between said second fluid and at least one of a third fluid and the surroundings of said heat exchanging means, said heat exchanging means being in fluid communication with said fourth outlet,    measuring means for measuring the rate of heat exchange of said heat exchanging means,    signal output means for emitting a signal representing the result of a measurement carried out by said measuring means, and    first control means for controlling the adjustment of said first and second throttle means and adapted for receiving said signal.    
   
   
       38 . A combination according to  claim 21  and further comprising second control means for controlling the adjustment of said first throttle means such that the throttling effect thereof is at a minimum during the start up phase of said combustion means.  
   
   
       39 . A combination according to  claim 20 , wherein said exhaust gas generating combustion means is chosen from the group comprising a natural gas fired turbine, an internal combustion engine, a burner, a furnace and an incinerator.  
   
   
       40 . A method of manufacturing a heat exchanger according to  claim 1  and comprising the steps of: 
 providing a first length of tube selected from the group consisting of a finned tube and a corrugated tube,    providing a body having a substantially circular cylindrical surface,    providing rotating means for causing relative rotation of said tube and said surface,    arranging a lead portion of said tube abutting against said surface,    causing relative rotation of said surface and said lead portion such that said first length of tube is helically wound on said surface to form a first helical coil.    
   
   
       41 . A method according to  claim 40  and comprising the further steps of: 
 providing spacing means,    attaching said spacing means to said first helical coil,    providing a second length of tube selected from the group consisting of a finned tube and a corrugated tube,    arranging a lead portion of said second length of tube abutting against said spacing means,    causing relative rotation of first helical coil and said lead portion of said second length of tube such that said second length of tube is helically wound on said spacing means to form a second helical coil radially spaced from said first helical coil.    
   
   
       42 . A method according to  claim 40  and comprising the further steps of: 
 fixating said helical coil relative to said body, and    subjecting said body and said coil to annealing heat treatment.    
   
   
       43 . A method according to  claim 41  and comprising the further steps of: 
 fixating said second helical coil relative to at least one of said body and said first helical coil, and    subjecting said body and said first and second coils to annealing heat treatment.