GB2273980A

GB2273980A - Concentric tube heat exchanger

Info

Publication number: GB2273980A
Application number: GB9300041A
Authority: GB
Inventors: William Tak Ming Tsui
Original assignee: Falmer Investments Ltd
Current assignee: Falmer Investments Ltd
Priority date: 1993-01-04
Filing date: 1993-01-04
Publication date: 1994-07-06
Anticipated expiration: 2013-01-04
Also published as: GB9300041D0; CN1092156A; GB2273980B; CN1064126C

Abstract

A heat exchange connection 1 comprises an inner pipe 2 with connectors 3 and 4 to supply fluid to a process. Surrounding the pipe 2 at a spacing therefrom is a concentric pipe 5 which forms a space 6 provided with connectors 9 and 10 so that steam or water can be supplied to removed from space 6. Surrounding pipe 5 and spaced therefrom is a pipe 11 which defines, a space 12 provided with connectors 15 and 1650 that outlet fluid can pass through the space 12. Thus, inlet fluid flowing in the pipe 2 is in heat exchange relationship with the steam or water flowing in the space 6 and outlet fluid flowing in the space 12 is in heat exchange relationship with the steam or water flowing in the space 6. In the preferred embodiment the fluid is a dyeliquor. A further annular duct may be provided outside the outer flow or return duct 12. <IMAGE>

Description

HEAT EXCHANGE The invention relates to heat exchange and particularly to heat exchange between a process fluid and a heating or cooling fluid. The invention has particular though by no means exclusive application to increasing the temperature of dyeliquors using steam and reducing the temperature of dyeliquors using water.

Tubular devices have been used to bring heat from steam into contact with dyeliquor in a heating mode or to remove heat from dyeliquor by passing cold water through tubes of the device in a cooling mode.

One previously proposed method has involved providing a large tubular coil in the bottom of a dyeing vessel. This however involves disadvantages:1 The coil is necessarily located in a region of the machine where liquor velocity is at its lowest and in consequence heat transfer is at lowest efficiency resulting in a requirement for a large heating surface; 2 The coil increases the height requirement of the vessel and results in much of this height being wasted due to a lot of unoccupied space existing around and between the spirals of the coil.This increases the liquor ratio in the machine and reduces efficiency; 3 With tight packages to be dyed and low flow rates of dyeliquor, the liquor in contact with the heating coil may become overheated and even boil causing it to rise to the top of the almost static liquor in the vessel and creating a potential safety hazard; 4 Excessive temperature with reduced flow may have undesirable effects on the dyestuff causing deterioration thereof and giving rise to light or off-shade dyeings since particular components in complex formula dyeliquors can be more temperature sensitive than others.

It is also been proposed to use a heat exchanger externally of a dyeing vessel and comprising a bundle of parallel tubes through which dyeliquor is caused to flow, the tubes being contained in a pressure vessel in a manner such that steam under pressure for heating or water for cooling are in contact with outer surfaces of the tubes. This involves considerable entry and exit losses and requires a considerable proportion of the performance of the pump to be used up in forcing the liquor through the tubes.

A converse construction may be used where steam or cooling water is passed through the tubes and the dyeliquor surrounds them in a vessel but all previously proposed solutions suffer from severe disadvantages in attempts to maintain high velocities in the heat transfer media.

According to the invention a heat exchange connection provided between a process vessel and a pump, through which connection process fluid can be passed between the process vessel and the pump, comprises concentric flow and return ducts with, provided therebetween, an annular duct through which heating or cooling fluid can be passed to heat or cool the fluid flowing in the flow and return ducts.

Thus the connection is advantageously formed as a two-pass vertical column heat exchanger.

Advantageously an inner flow or return duct is of circular form and the outer flow or return duct is of annular form.

Preferably the inner duct is a flow duct and the outer duct is a return duct. The flow duct can be of a size such that there will be no measurable pressure drop therein as the process fluid passes therethrough from the pump to a process vessel and pressure losses in the outer return pass can be minimised by good design and can in any event be lower than in comparable existing designs.

For any given rate of temperature rise, the temperature pickup per flow or return pass will only need to be half as much as in existing designs so that the stability of delicate dyestuffs will be improved.

Temperature differences around the circulating system can be minimised as can pressure losses in the system.

If desired a further annular duct could be provided outside the outer flow or return duct for passage of heating or cooling fluid.

If desired the inner flow or return duct could be provided of annular form so that flow of liquor is through a first annular space, flow of heating or cooling fluid is in an outer annular space and return flow of process fluid is through a next outer annular space.

Such a configuration can have the advantage that the heating surface can be increased without decreasing the velocity of the liquor over the heating or cooling surface.

The invention is diagrammatically illustrated by way of example in the accompanying drawing, in which: Figure 1 is a sectional elevation through a heat exchange connection according to the invention; Figure 2 is a plan view corresponding to Figure 1; Figure 3 is a sectional elevation taken on line A-A of Figure 2; and Figure 4 is a sectional view to an increased scale taken on line B-B of Figure 3.

Referring to the drawings, a heat exchange connection generally indicated at 1 comprises an inner pipe 2 having a flanged connector 3 at its upper end and a connector 4 at its lower end. The pipe 2 is provided to supply inlet dyeliquor to a process vessel and remove it therefrom and the process vessel is therefore connected to one or other of the connectors 3 and 4 with the other one of the connectors 3 and 4 not so connected connected to a supply pump.

Surrounding the outer wall of the pipe 2 at a spacing therefrom is a concentric pipe 5 which forms with the outer wall of the pipe 2 a space 6. The space 6 is closed off at its ends where the pipe 5 is sealed at positions 7 and 8 to the outer wall of the pipe 2. A connection 9 is provided at the lower end of the pipe 6 and a connection 10 is provided at the upper end so that steam or water can be supplied to and removed from the space 6 by the connections 9 and 10.

Surrounding the pipe and at a spacing therefrom is a pipe 11 which defines, with the outer wall of the pipe 6, a space 12. The pipe 11 is sealed at its ends to the outer wall of the pipe 6 at positions 13 and 14. A flanged connection 15 is provided at the lower end of the pipe 11 to communicate with the space 12 and a further flanged connection 16 is provided at the upper end in communication with the space 12. Outlet dyeliquor can pass into the space 12 through the flanged connections 15 and 16 and leave by the other of the flanged connections 15 and 16.

It can be seen from Figure 4 that inlet dyeliquor flowing in the pipe 2 is in heat exchange relationship with the steam or water flowing in the space 6 over the whole of the inner wall surface of the pipe 2 and outlet dyeliquor flowing in the space 12 is in heat exchange relationship with the steam or water flowing in the space 6 over the whole of the outer surface of the pipe 5.

Claims

1. A heat exchange connection provided between a process vessel and a pump, through which connection process fluid can be passed between the process vessel and the pump, comprising concentric flow and return ducts with, provided therebetween, an annular duct through which heating or cooling fluid can be passed to heat or cool the fluid flowing in the flow and return ducts.

2. A heat exchange connection according to claim 1, formed as a two-pass vertical column heat exchanger.

3. A heat exchange connection according to claim 1 or claim 2, in which an inner flow or return duct is of circular form and the outer flow or return duct is of annular form.

4. A heat exchange connection according to any one of claims 1 to 3, in which the inner duct is a flow duct and the outer duct is a return duct.

5. A heat exchange connection according to any one of claims 1 to 4, in which the flow duct is of a size such that there will be no measurable pressure drop therein as the process fluid passes therethrough from the pump to a process vessel.

6. A heat exchange connection according to any one of claims 1 to 5, in which a further annular duct is provided outside the outer flow or return duct for passage of heating or cooling fluid.

7. A heat exchange connection according to claim 1 or claim 2, in which the inner flow or return duct is provided of annular form so that flow of liquor is through a first annular space, flow of heating or cooling fluid is in an outer annular space and return flow of process fluid is through a next outer annular space.

8. A heat exchange connection substantially as hereinbefore described and illustrated with reference to the accompanying drawing.