GB2132326A

GB2132326A - Vapour separator

Info

Publication number: GB2132326A
Application number: GB08235606A
Authority: GB
Inventors: Richard Eli James Martin
Original assignee: APV Corp Ltd
Current assignee: SPX Flow Technology Crawley Ltd
Priority date: 1982-12-14
Filing date: 1982-12-14
Publication date: 1984-07-04
Also published as: GB2132326B

Abstract

An absorption type heat pump or chiller includes various heat exchanger and other plant stages. In order to economise on space, it is proposed that the heat exchange stages should be plate heat exchangers mounted in a common frame with a vapour separator also mounted in the frame. In order to provide a suitable vapour separator, there is provided a vapour separator comprising a body 41 and means 53 for suspending the body 41 in a plate heat exchanger frame. A first upper corner port 44 is an inlet for a vapour/liquid stream which is guided by baffles 49 to flow down towards the bottom of a flow zone 42, formed with the frame 41 by facing sheets, then across the bottom and then to turn upwardly to flow to a second upper corner port 45 forming a vapour exit. <IMAGE>

Description

SPECIFICATION Vapour separator This invention relates to vapour separators, particularly for use in absorption type heat transfer apparatus.

One problem of this type of heat transfer apparatus is that the use of multiple stages of heat transfer between the streams, via an absorbent medium, requires the use of a number of heat exchangers and other pieces of plant, so that the apparatus tends to be not only expensive, but also requires a great deal of space.

It is proposed in our copending application number 8235608 filed simultaneously herewith and entitled "Heat Transfer Apparatus", to provide a heat pump or chiller in which the heat exchange stages are formed by plate heat exchangers mounted in a common frame. It is also suggested that other pieces of plant should be mounted in the frame.

According to one aspect of the present invention, there is provided a heat pump or chiller in which the heat exchange stages are formed by plate heat exchangers, mounted in a common frame and in which a vapour separator is also mounted in the frame.

In accordance with a second aspect of the invention, there is provided a vapour separator for mounting in the frame of a plate heat exchanger, comprising a body with means for suspending the body from a top bar of a heat exchanger frame, a first upper corner port for admitting a stream of vapour with suspended liquid from an adjacent heat exchanger section in the frame, a second upper corner port providing a vapour outlet to a heat exchanger section, a chamber formed within the body and including means for providing a path from the said upper port towards, across and then away from the bottom of the chamber towards the second upper corner port, and means for withdrawing liquid from the bottom of the chamber.

In order to enable the separator also to act as a connection to adjacent heat exchanger sections, the body may include a lower section having connections therein to enable supply and discharge of media to and from sections of the plate heat exchanger adjacent to the separator.

The path for the vapour and liquid may be formed by baffles.

The invention wili be further described with reference to the accompanying diagrammatic drawings, in which: Figure 1 illustrates the components of a heat transfer apparatus of the absorption type adapted for mounting in a conventional common heat exchanger frame; Figure 2 illustrates the basic components of a heat exchanger frame; Figure 3 is an elevation of a vapour separator; and Figure 4 is a section of the Line IV--IV of Figure 3.

The flow diagram of Figure 1 shows five flow streams related to a typical generally conventional absorption type heat pump or water chiller, using a lithium bromide/water system as the absorbant/refrigerant pair and low pressure steam or hot water as the driving heat source.

The arrangement is drawn up in such a way that it can be incorporated in the frame of a heat exchanger, of which a follower is shown at 1 and a head at 2. The flow of a heat source, which is chilled in operation, is shown by the chain dotted line 3. The flow of liquid, such as the product to be warmed, is shown by the dashed line 4. The flow of lithium bromide solution is shown by the full line 5 and the flow of water derived from and reabsorbed into the flow of lithium bromide solution is shown by the line of long dashes 6. A further chain dotted line 7 illustrates the flow of the driving steam or hot water.

The heat exchanger frame contains five heat exhanging sections denoted by the reference numerals 11, 12, 13, 14 and 15. Physically between the sections 11 and 1 2 there is located an absorber 1 6 also mounted in the heat exchanger frame. Between the sections 12 and 13 there is located a connecting grid or intermediate header 17, and between the sections 13 and 14 there is a further similar connecting grid or intermediate header 1 8. Between the sections 14 and 1 5 there is located a vapour separator 19, also mounted in the heat exchanger frame.

Dealing first with the flow of water, this first arises as vapour separated from the lithium bromide solution in the separator 19, and it is passed from there to the heat exchange section 14 where it is condensed and warms the stream 4 just prior to the withdrawal of that stream from the system in its fully warmed state. The water is fed by a pump 21 through an expansion valve 22 and arrives at the heat exchanger section 11, which acts as an evaporator operating at low pressure (in the region of 20 mm mercury). This evaporation is achieved by extracting heat from the heat source stream 3, which has this as its only active involvement in the system, and is thus cooled, thereby feeding energy into the system.

The water vapour from the evaporator section 11 is then fed into the absorber 16 where it is condensed into the circulating lithium bromide solution and raises the temperature thereof.

The thus warmed and diluted lithium bromide solution is fed by a pump 23 into the heat exchanger section 1 2 in heat exchange with the stream 4 which is thus heated. It will be appreciated that the stream 4 is further heated in the condensation stage 14 before leaving the system. The lithium bromide solution passes from the heat exchanger section 12 to the heat exchanger section 1 3 where it is regeneratively heated by the concentrated lithium bromide solution fed from the separator 1 9 by a pump 20.

The heated solution is then passed into the heat exchanger section 1 5 where it comes into heat exchange with the driving heat source stream 7 to raise the temperature still further and enable the absorbed water to be flashed off in the separator 19.

The concentrated solution then returns to the heat exchanger section 1 3 as already described and then to the absorber 1 6. As indicated above, the absorption cycle is substantially conventional, and the description of it is included to indicate how the necessary equipment to carry out this complex cycle can be incorporated into the frame of a plate heat exchanger.

For completeness, Figure 2 illustrates a typical plate heat exchanger frame which has the head 2 already referred to and an end stop member 31.

These are interconnected by a top rail 32 and a bottom rail 33. The follower 1 already referred to is suspended on the top rail 32 and supported by the bottom rail 33 and the pack of plates and other equipment, including the absorber 1 6, the separator 1 9 and the intermediate headers 1 7 and 1 8, is compressed between the follower 1 and the head 2 and the whole pack is secured in position after compression by means of tie bars illustrated at 34 and extending between the head 2 and follower 1.

The grids or intermediate headers 1 7 and 1 8 are currently available commercial pieces of equipment which are provided with corner porting to cooperate with the corner ports of the adjacent packs of plates, and also provided with external connections for supply and discharge of media to and from these corner ports.

Turning now to Figures 3 and 4, the vapour separator is shown in rather more detail. It is shown as consisting of a body 41 surrounding a separating chamber 42 which is closed by facing sheets 43. These facing sheets may be either welded to the body, or if it is desired that the chamber 42 may be opened up for cleaning, then they may be removably secured to the body and sealed by gaskets. The body is provided with a first upper corner port 44 and a second upper corner port 45. Each of these corner ports communicates with the interior of the chamber 42, and the corner port 44 acts as an inlet port for the flow of vapour and liquid, and a port 45 is an outlet port for the separated vapour.A liquid outlet 46 is located in the tower part of the chamber, for withdrawal of the separated liquid, and in order to maintain a minimum level of liquid in the chamber to seal the outlet 46, a level detecting means, such as a float 47, is provided to control a valve 48 in the liquid discharge line.

Extending between the facing sheets 43 there are provided a pair of baffles 49, the upper parts of which are imperforate, but the lower parts of which are provided with holes 51 as illustrated in Figure 4 in particular, so that the flow of liquid and vapour entering via the port 44 is at first constrained to flow downwardly towards a pool of liquid 52 in the bottom of the chamber, and is then allowed to turn to flow across the top of the pool 52, as permitted by the apertures 51, and is then caused to turn to flow upwardly towards the port 45. The changes of direction involved cause the liquid droplets to separate from the vapour, so that effectively only vapour is discharged through the port 45 to the next stage.The liquid collects in the pool 52 and is drawn off by the pump 20 whenever the level is sufficiently high for the valve 48 to be opened by means of the level probe 47. - The separator is shown as being provided with a roller 53 to enable it to be suspended from the top bar 32 of the frame, and attached to the lower end of the body 41 there is a standard lower end portion 54, such as is used on the commercially available grids or intermediate headers, and this lower portion contains porting illustrated at 55 and connection unions 56 to enable the lower portion 54 to be used for the supply and discharge of media from the adjacent heat exchange sections. The portion 54 is shown as being provided with a recess 57 to cooperate with the bottom rail 33.

It may occasionally be necessary to purge the system of non-condensibles, and for this purpose a vent 61 is shown, to enable the chamber 42 to be connected to a vacuum when required.

Corrosion by the lithium bromide solution used in the absorption process may be prevented by suitable coating of the metal parts. The pipe work carrying the lithium bromide is preferably in a suitable plastics material, as are the pumps. The plates in the heat exchanger sections in contact with the lithium bromide solution are preferably of titanium.

Various modifications may be made within the scope of the invention.

Claims

1. An absorber for mounting in the frame of a plate heat exchanger, comprising a body with means for suspending the body from a top bar of a heat exchanger frame, a first upper corner port for admitting a stream of vapour with suspended liquid from an adjacent heat exchanger section in the frame, a second upper corner port providing a vapour outlet to heat exchanger sections, a chamber formed within the body and including means for providing a path from the said upper port towards, across and then away from the bottom of the chamber towards the second upper corner port, and means for withdrawing liquid from the bottom of the chamber.

2. A separator as claimed in claim I,compn'sing a lower section having connections therein to enable supply and discharge of media to and from sections of the plate heat exchanger adjacent to the separator.

3. A separator as claimed in claims 1 or 2, in which the chamber is defined by facing sheets.

4. A separator as claimed in claim 3, in which the facing sheets are welded to the body.

5. An absorber as claimed in claims 1, 2, 3 or 4, in which the flow path is defined by baffles.

6. A separator as claimed in claim 5 (as dependent on claims 3 and 4), in which the baffles extend between the facing sheets.

7. A separator as claimed in any of claims 1 to 6, including a liquid level detection arrangement to prevent withdrawal of liquid if the liquid level falls below a predetermined level.

8. A separator as claimed in any of claims 1 to 7, including a vent connectable to a vacuum pump to purge the chamber of non-condensibles.

9. A separator substantially as hereinbefore described with reference to the accompanying drawings.

10. A heat pump or chiller in which the heat exchanger stages are formed by plate heat exchangers mounted in a common frame, and in which a vapour separator is also mounted in the frame.