WO2004059231A1

WO2004059231A1 - Large-diameter labyrinthine tube heat exchanger

Info

Publication number: WO2004059231A1
Application number: PCT/IL2002/001061
Authority: WO
Inventors: Pessach Seidel
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-12-31
Filing date: 2002-12-31
Publication date: 2004-07-15
Anticipated expiration: 2005-06-30
Also published as: AU2002360208A1

Abstract

A free-flowing, large diameter labyrinthine tube heat exchanger (10) for non-free flowing liquids includes: a support structure; a first fluid conveyor (14) including a plurality of large-diameter pipes or tubes (22) mounted onto the support structure, defining a first fluid flow path having an inlet (16) and an outlet (18), for conveying a non-free flowing liquid such as sludge to be subjected to heat exchange while passing there through; and a second fluid conveyor (20) mounted onto the support structure, defining a second flow path in a direction that is generally non-parallel to the first fluid flow path, for conveying a heat transfer medium in heat transfer communication with the non-free flowing liquid.

Description

FREE FLOW HEAT EXCHANGER

FIELD OF THE INVENTION The present invention relates to tree flow heat exchangers, such as those used for viscous liquids or for liquids containing large particulate matter in suspension.

BACKGROUND OF THE INVENTION

Free flow heat exchangers are known in the art, particularly for the extraction of heat from, or pasteurization of, sewage sludge, industrial waste water, and highly viscous and/or contaminated wastewater, such as contains fibrous and particulate matter in suspension.

Heat exchangers of this type are formed of a large diameter labyrinthine tube which carries a viscous medium to be treated by heat exchange along a first flow path, and a heat transfer medium carried in a generally transverse flow and in heat conductive contact with the viscous medium.

A particular problem of known constructions is the fact that they have a high incidence of fouling, i.e. they readily become clogged by suspended solids, and must therefore be cleaned regularly so as to prevent blockage. The labyrinthine tubes are also particularly difficult to clean. The nature of the connections which are required in order to enable access for maintenance and inspection of the tubes also prevents the use thereof for high pressure flows.

SUMMARY OF THE INVENTION

The present invention aims to provide a free flow heat exchanger characterized by a simple construction, low fouling, easy maintenance and the ability to convey high pressure flows at high temperatures, and at high heat transfer efficiency.

There is thus provided, in accordance with a preferred embodiment of the invention, a free flow heat exchanger for non-free flowing liquids, which includes: a support structure, a first fluid conveyor mounted onto the support structure, defining a first fluid flow path having an inlet and an outlet, for conveying a non-free flowing liquid to be subjected to heat exchange while passing therealong, and a second fluid conveyor mounted onto the support structure, defining a heat transfer medium carried in a flow direction that is generally non-parallel to the first fluid flow path, and in heat transfer communication with the non-free flowing liquid.

In accordance with a preferred embodiment of the invention, the first fluid conveyor includes a labyrinthine tube arrangement extending between the inlet and the outlet, and includes

(i) a plurality of generally parallel, linear tube portions, each defining a first and second free ends, wherein the first free ends form a plurality of first free ends at a first side of the first fluid conveyor, and the second free ends form a plurality of second free ends at a second side of the first fluid conveyor;

(ii) a first, integral fluid flow transfer element, configured for sealed engagement with the plurality of first free ends so as to facilitate flow of the non-free flowing liquid between the plurality of first free ends, while substantially preventing leakage therefrom; and (iii) a second, integral fluid flow transfer element similar to the first integral fluid flow transfer element, configured for sealed engagement with the plurality of second free ends so as to facilitate flow of the non-free flowing liquid between the plurality of second free ends, while substantially preventing leakage therefrom.

There is also provided fastening apparatus for facilitating selectable fastening of the first and second integral fluid flow transfer elements to the pluralities of first and second free ends, respectively, so as to assemble the first fluid conveyor and thus facilitate fluid flow therealong, the fastening apparatus also facilitating selectable removal of the first and second integral fluid flow transfer elements from the pluralities of first and second free ends, respectively, so as to expose the free ends for inspection and cleaning of the interior of the first fluid conveyor. Additionally in accordance with a preferred embodiment of the invention, the free ends of the linear tube portions, and the first and second integral fluid flow transfer elements are formed so as to form non-linear bend portions therebetween, each permitting a volumetric flow comparable to the volumetric flow through the linear tube portions.

Further in accordance with a preferred embodiment of the invention, the linear tube portions are separated via a dividing element formed therebetween so as to separate the respective flows therealong, and wherein the dividing element is shorter than the linear tube portions so as to form thereat a non-linear bend portion therebetween, each permitting a volumetric flow comparable to the volumetric flow through the linear tube portions.

Additionally in accordance with a preferred embodiment of the invention, the integral fluid flow transfer elements have an inward-facing, generally flat, contact surface for engaging the free ends of the linear tube portions when assembled therewith.

Further in accordance with a preferred embodiment of the invention, the integral fluid flow transfer elements have a plurality of inward-facing, generally rounded, concave contact portions, for engaging the free ends of the linear tube portions when assembled therewith, so as to form the non-linear bend portions therewith.

Additionally in accordance with a preferred embodiment of the invention, each integral fluid flow transfer element has a door like construction, and the fastening apparatus includes: hinge apparatus for connecting the fluid flow transfer element to the support structure; and a plurality of selectably releasable fastening elements.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully understood and appreciated, from the following detailed description, taken in conjunction with the drawings, in which:

Fig. 1A is a side elevational view of a free flow heat exchanger, constructed and operative in accordance with a preferred embodiment of the invention;

Fig. IB is a side view of the heat exchanger of Fig. 1A;

Fig. 1C is an end view of the heat exchanger of Figs. 1A and IB, with the illustrated integral fluid flow transfer element seen in a closed position, such that the illustrated first fluid conveyor is in an assembled state; Fig. ID is an end view of the heat exchanger of Figs. 1A and IB, similar to Fig. 1C, but wherein the illustrated integral fluid flow transfer element is open, thereby exposing the free ends of the linear tube portions;

Fig. IE is an enlarged detail of the portion indicated IE in Fig. 1A;

Fig. IF shows an alternative detail, corresponding to that seen in Fig. IE, in accordance with an alternative embodiment of the present invention; and

Figs. 2A, 2B and 2C are pictorial illustrations showing the first fluid conveyor mounted onto its support structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention seeks to provide a free flowing heat exchanger, referenced generally 10 in the drawings, for the treatment of non-free-flowing liquids, such as, sewage sludge, industrial wastes and, generally, any non-free-flowing liquid by virtue of high viscosity and/or liquids with high volumes and/or large sized suspended solids, including fibers and solid particles, and which it is desired to subject to heat exchange. The necessity for this treatment may be so as to effect pasteurization of such liquids, or to extract heat therefrom, or any other reason known in the art.

The free flow heat exchanger 10 of the present invention is characterized by low fouling, due to its simple interior construction, and easy access for inspection, cleaning, and other maintenance tasks. Due to the simplicity of construction and thus small number of joints, it is also able to withstand liquids at high pressure, as well as at high temperatures, such as may be encountered when dealing with industrial waste liquids.

In general, the heat exchanger 10 of the present invention includes a plurality of large diameter pipes or tubes 22 which are connected so as to constitute a first fluid conveyor 14, through which the non-free-flowing liquid is conveyed. This first fluid conveyor 14 is itself immersed either in a box-like volume, or in larger diameter pipes, each of which maybe used to provide a second fluid conveyor 20 through which a heat exchange medium is conveyed. The respective fluids are conveyed so as to be non-parallel, so as to cause an effective heat exchange therebetween. The second fluid conveyor 20 is not shown in detail, but merely depicted by way of its inlet and outlet, respectively referenced 21 and 23, in Figs. 1 A-IC.

Furthermore, the various tubes 22 of first fluid conveyor 14, may be arranged so as to provide linear or parallel fluid flow circuits, as required. As shown in the drawings, the non-free flowing liquid flows typically from the bottom of the heat exchanger to the top, while the heat exchange medium flows in the opposite direction.

The heat exchange medium can be water or a relatively clean, free flowing liquid or gas.

It will also be noted that, at each of the exterior ports to which the inlets and outlets of the first and second fluid conveyors are connected, there is provided a pair of removable flanges. At each port, one flange is removed so as to form an inlet/outlet for the respective fluid inflow or outflow, while the other flange, depicted F, which is normally mounted so as to close an otherwise open port, can be removed periodically for inspection, cleaning, or other maintenance purposes.

Further as seen in Figs. 1A-1C, each fluid conveyor has inlet and outlet connections, at upper and lower portions of the housing 12. In a typical arrangement, illustrated herein, the sludge inlet is located at the bottom and the sludge outlet is at the top. The inlet 21 and outlet 23, for the water, which serves here as an exemplary heat exchange fluid, are at upper and lower portions of the housing 12, respectively, thereby to provide a flow which is opposite or transverse to the that of the non-free-flowing liquid.

While any suitable materials can be used for the heat exchanger of the present invention, a preferred material is carbon steel.

By way of example, only, the channels have a diameter of approximately 100 mm, which is retained as a minimum "bend" or "elbow" diameter.

Referring now to Figs. 1A-1D, there is provided, in accordance with a preferred embodiment of the invention, a free flow heat exchanger, referenced generally 10, for non- free flowing liquids, which includes a support structure or housing 12, a first fluid conveyor referenced 14, mounted onto the support structure 12, and defining a first fluid flow path having an inlet 16 and an outlet 18, for conveying therebetween a non-free flowing liquid to be subjected to heat exchange while passing therealong; and a second fluid conveyor 20.

The second fluid conveyor 20 is mounted onto the support structure 12, and is operative to carry a heat transfer medium, such as water, in a flow direction that is generally non-parallel to the first fluid flow path, and in heat transfer communication with the non-free flowing liquid in the first fluid conveyor.

First fluid conveyor 20 includes, as seen particularly in the pictorial illustrations in Figs. 2A-2C, a labyrinthine tube arrangement extending between the inlet 16 and outlet 18, and includes (i) a plurality of generally parallel, linear tube portions 22, each defining first and second free ends, respectively referenced 24 and 26, wherein the first free ends 24 form a plurality of first free ends at a first side 28 of the first fluid conveyor 20; and the second free ends 26 form a plurality of second free ends at a second side 30 of the first fluid conveyor 20; (ii) a first, generally door-like, integral fluid flow transfer element 32 (seen in Figs. 1A- 1F), configured for sealed engagement with the plurality of first free ends 24 so as to facilitate flow of the non-free flowing liquid between the plurality of first free ends 24, while substantially preventing leakage therefrom; and

(iii) a second, generally door-like, integral fluid flow transfer element 34 (seen in Figs. 1 A- 1B) similar to the first integral fluid flow transfer element 32, configured for sealed engagement with the plurality of second free ends so as to facilitate flow of the non-free flowing liquid between the plurality of second free ends 26, while substantially preventing leakage therefrom.

The first and second integral fluid flow transfer elements 32 and 34 are selectably fastened to the pluralities of first and second free ends 24 and 26, respectively, by means of fastening apparatus which includes a plurality of bolted connections 36 (as seen in Figs. 1C- 1D). The first and second integral fluid flow transfer elements 32 and 34 are further mounted to the support structure 12 by means of hinge constructions 38 (as seen in Figs. IB-ID). The hinge constructions 38 and bolted connections 36 are operative to hold the integral fluid flow transfer elements 32 and 34 in place so as to permit operation of the heat exchanger, but also to facilitate relatively easy removal of the transfer elements 32 and 34, so as to expose the free ends 24 and 26 of the tubular portions 22 for inspection and cleaning of the interior of the first fluid conveyor 14.

It is a particular feature of the invention that the free ends 24 and 26 of the linear tube portions 22, and the first and second integral fluid flow transfer elements 32 and 34, are formed so as to form therebetween non-linear bend portions, generally referenced 40, as seen in Fig. IE and 2A-2C. Each bend portion 40 is configured so as to permit therethrough a volumetric flow comparable to the volumetric flow through the linear tube portions 22.

Referring now particularly to Fig. IE, it is seen that the illustrated first integral fluid flow transfer element 32 has a plurality of inward-facing, generally rounded, concave contact portions 42, for engaging the adjacent, first free ends 24 of the linear tube portions 22 when assembled therewith, so as to form a rounded, non-linear bend portion 40 therewith. As seen, suitable sealing gaskets 43, such as O-rings, are preferably provided so as to ensure a leak proof seal between contact portions 42 and the tube free ends. It will be appreciated that, while only the first integral fluid flow transfer element 32 and the first free ends 24 of the linear tube portions 22 are shown and described herein in detail, the construction of second integral fluid flow transfer element 34 and second free ends 26 of the linear tube portions 22 are similar thereto, and thus are not shown and described specifically in detail, herein.

A particular advantage of the construction, is the fact that, due to the rounded shape of the contact portions, there is very little tendency for suspended particles or fibers to become stuck or to accumulate in a short time, thereby leaving the passageways open for longer, and thus maintaining a high operating efficiency and enabling a longer time between maintenance. This construction is also able to withstand higher pressures than known in conventional constructions.

It will also be noted that adjacent linear tube portions 22 are separated via a dividing element 42' formed therebetween, wherein the dividing element is shorter than the linear tube portions 22, per se, thereby to complement the contact portions 42.

Referring now to Fig. IF, in accordance with an alternative embodiment of the invention, the contact portions 42 need not be rounded, but simply flat, as illustrated. In such a case, dividing element 42 may be shortened, so as to enable a desired volumetric flow through the elbow or bend portion 40, thus formed.

It will be appreciated by persons skilled in the art that the scope of the present invention is not limited by what has been shown and described hereinabove, solely by way of example. Rather, the scope of the invention is limited solely by the claims, which follow:

Claims

1. A free flow heat exchanger for non-free flowing liquids, which includes: a support structure a first fluid conveyor mounted onto said support structure, defining a first fluid flow path having an inlet and an outlet, for conveying a non-free flowing liquid to be subjected to heat exchange while passing therealong, and a second fluid conveyor mounted onto said support structure, defining a heat transfer medium carried in a flow direction that is generally non-parallel to said first fluid flow path, and in heat transfer communication with the non-free flowing liquid, wherein said first fluid conveyor includes a labyrinthine tube arrangement extending between said inlet and said outlet, and includes: a plurality of generally parallel, linear tube portions, each defining a first and second free ends, wherein said first free ends form a plurality of first free ends at a first side of said first fluid conveyor, and said second free ends form a plurality of second free ends at a second side of said first fluid conveyor; a first, integral fluid flow transfer element, configured for sealed engagement with said plurality of first free ends so as to facilitate flow of the non-free flowing liquid between said plurality of first free ends, while substantially preventing leakage therefrom; and a second, integral fluid flow transfer element similar to said first integral fluid flow transfer element, configured for sealed engagement with said plurality of second free ends so as to facilitate flow of the non-free flowing liquid between said plurality of second free ends, while substantially preventing leakage therefrom; and fastening apparatus for facilitating selectable fastening of said first and second integral fluid flow transfer elements to said pluralities of first and second free ends, respectively, so as to assemble said first fluid conveyor and thus facilitate fluid flow therealong, said fastening apparatus also facilitating selectable removal of said first and second integral fluid flow transfer elements from said pluralities of first and second free ends, respectively, so as to expose said free ends for inspection and cleaning of the interior of said first fluid conveyor.

2. A free flow heat exchanger according to claim 1, wherein said free ends of said linear tube portions, and said first and second integral fluid flow transfer elements are formed so as to form non-linear bend portions therebetween, each permitting a volumetric flow comparable to the volumetric flow through said linear tube portions.

3. A free flow heat exchanger according to claim 2, wherein said linear tube portions are separated via a dividing element formed therebetween so as to separate the respective flows therealong, and wherein said dividing element is shorter than said linear tube portions so as to form thereat a non-linear bend portion therebetween, each permitting a volumetric flow comparable to the volumetric flow through said linear tube portions.

4. A free flow heat exchanger according to claim 3, wherein said integral fluid flow transfer elements have an inward-facing, generally flat, contact surface for engaging said free ends of said linear tube portions when assembled therewith.

5. A free flow heat exchanger according to claim 2, wherein said integral fluid flow transfer elements have a plurality of inward-facing, generally rounded, concave contact portions, for engaging said free ends of said linear tube portions when assembled therewith, so as to form said non-linear bend portions therewith.

6. A free flow heat exchanger according to claim 1, wherein each said integral fluid flow transfer element has a door like construction, and said fastening apparatus includes: hinge apparatus for connecting said fluid flow transfer element to said support structure; and a plurality of selectably releasable fastening elements.