EP3034965A1

EP3034965A1 - A shell-and-plate condenser, a method for removing oil from a refrigerant and use of a shell-and-plate condenser

Info

Publication number: EP3034965A1
Application number: EP14199301.4A
Authority: EP
Inventors: Christian Per Bunde-Pedersen; Simon Stubkier
Original assignee: Johnson Controls Denmark ApS
Current assignee: Johnson Controls Denmark ApS
Priority date: 2014-12-19
Filing date: 2014-12-19
Publication date: 2016-06-22
Anticipated expiration: 2034-12-19
Also published as: DK3034965T3; EP3034965B1; WO2016095919A1

Abstract

Disclosed is a shell-and-plate condenser (1) comprising a stack of corrugated heat transfer plates (5) arranged inside a tubular outer shell (8), wherein the outer shell (8) comprises at least one entrance hole (2) for leading oil-containing refrigerant into the condenser (1) and the condenser (1) further comprises an integrated oil separator unit (3) arranged above the plate stack. The oil separator unit (3) includes at least one flow distribution chamber (4) being connected to at least one of the entrance holes (2), wherein the flow distribution chamber (4) substantially extends in a longitudinal direction of the tubular outer shell (8) and wherein the flow distribution chamber (4) comprises at least one sidewall (6) comprising a plurality of exit holes (7) through which the oil-containing refrigerant leaves the flow distribution chamber (4) in a direction substantially transversal to the longitudinal direction of the outer shell (8) and flows out into a flow guide channel (9) of the oil separator unit (3). The oil separator unit (3) further includes at least one outflow demister element (10) arranged in a demister part (11) of the flow guide channel (9).

A method for removing oil from a refrigerant by means of an oil separator unit (3) arranged inside a tubular outer shell (8) of a shell-and-plate condenser (1) and use of a shell-and-plate condenser (1) is also disclosed.

Description

Field of the Invention

The present invention relates to a shell-and-plate condenser comprising a stack of corrugated heat transfer plates arranged inside a tubular outer shell. The invention further relates to a method for removing oil from a refrigerant by means of an oil separator unit arranged inside a tubular outer shell of a shell-and-plate condenser. The invention also relates to use of a shell-and-plate condenser.

Background of the Invention

Shell-and-plate (or plate-and-shell) condensers consist of a series of corrugated plates peripherally welded or bonded to each other in pairs (so-called cassettes) which in turn are welded to each other along the entrance holes and exit holes to form a complete plate stack (or plate pack). The plate pack is inserted within a tubular shell, typically formed from steel. Shell-and-plate condensers are often used in refrigeration cycles typically also comprising an evaporator and a compressor. In large refrigeration cycles the compressor is oil lubricated, and over time some of this oil will be diluted and mixed with the refrigerant circulating in the refrigeration cycle. If this oil is not removed it will form a layer or a coating on the plates in the condenser and/or the evaporator which will severely reduce the efficiency.
Thus, from WO 2007/057025 it is therefore known to arrange oil separator elements inside the condenser so that the oil-containing refrigerant is guided through these elements before the supposedly oil-free refrigerant is lead through the plate pack. However, a desire to improve the oil separation efficiency has emerged.
It is therefore an object of the present invention to provide for a more efficient oil separation technique for use in relation with condensers.

The invention

The invention relates to a shell-and-plate condenser comprising a stack of corrugated heat transfer plates arranged inside a tubular outer shell, wherein the outer shell comprises at least one entrance hole for leading oil-containing refrigerant into the condenser and the condenser further comprises an integrated oil separator unit arranged above the plate stack. The oil separator unit includes at least one flow distribution chamber being connected to at least one of the entrance holes, wherein the flow distribution chamber substantially extends in a longitudinal direction of the tubular outer shell and wherein the flow distribution chamber comprises at least one sidewall comprising a plurality of exit holes through which the oil-containing refrigerant leaves the flow distribution chamber in a direction substantially transversal to the longitudinal direction of the outer shell and flows out into a flow guide channel of the oil separator unit. The oil separator unit further includes at least one outflow demister element arranged in a demister part of the flow guide channel.
Forming the oil separator as a separate unit is advantageous in that the risk of oil-containing refrigerant getting in contact with the plate pack is hereby reduced. And placing the unit inside the condenser is advantageous in that the oil separator unit hereby does not have to be formed as a pressure vessel since the pressure inside and outside the unit is substantially the same.
Arranging the oil separating unit above the plate stack is advantageous in that in the condenser the refrigerant - that has changed from gaseous to liquid phase - will naturally seek downwards due to gravitational pull. It is therefore advantageous to lead the refrigerant downwards through the plate stack. Thus, if the refrigerant has to be de-oiled before it enters the plate stack it is advantageous that the oil separator unit is arranged above the plate stack, because it provides a less space consuming design and because it reduces the risk of refrigerant condensation before the refrigerant reaches the plate stack.
It is also advantageous to lead the oil-containing refrigerant into the oil separator unit through a flow distribution chamber in that the flow hereby is distributed better before the oil-containing refrigerant reaches the demister element i.e. the flow of oil-containing refrigerant is better distributed throughout the entire area of the demister element hereby increasing its efficiency substantially without increasing its size.
It should be noted that in the above and in the following all references to orientation - such as above, below, under, downwards, horizontal etc. - refers to the condenser's orientation during normal use i.e. where the refrigerant is lead down through the plate stack so that the condensed liquid refrigerant can be drained from the bottom of the condenser. The condenser might function even if it is not orientated as intended but the skilled person would recognise that the condenser is most efficient if it is orientated as intended and the skilled person would therefore not question which orientation of the condenser would be the correct one to use during normal use of the condenser.
It should also be noted that in this context the term "demister element" is to be understood as any kind of device designed to enhance the removal of liquid droplets entrained in a vapour stream. I.e. the demister element may be any kind of mesh type coalescer, knitted mesh, nonwoven filament structure, vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapour stream.
In an aspect of the invention, the demister part of the flow guide channel is arranged in an angle of between 5° and 85°, preferably between 15° and 75° and most preferred between 30° and 60° upwards in relation to a horizontal plane.
If the demister part of the flow guide channel is too steep the risk of separated oil being suspended by the upward gas flow is increased and such suspended oil will decrease the efficiency of the demister element or at least increase the drop of pressure across the demister element. However, if the demister part of the flow guide channel is too flat the risk of separated oil being dragged out of the demister element by the gas flow is increased thus reducing the efficiency of the demister element. Thus, the present angle ranges are particularly advantageous regarding efficiency of the demister element.
In an aspect of the invention, the exit holes constitutes between 1% and 90%, preferably between 2% and 50%, and most preferred between 3% and 25% of the total area of the flow distribution chamber.
If the exit holes constitute too much of the total area of the flow distribution chamber most of the entering oil-containing refrigerant will leave the flow distribution chamber at the far end opposite from the entrance hole and the incoming flow will hereby not be efficiently distributed in the oil separator unit. And if the exit holes constitute too little of the total area of the flow distribution chamber, the pressure drop across the flow distribution chamber becomes too high and the energy required for circulating the refrigerant is increased. Thus, the present exit hole area ratios presents an advantageous relationship between gas flow distribution efficiency and power consumption.
In an aspect of the invention, the flow distribution chamber comprises an inflow demister element arranged inside the flow distribution chamber.
Arranging an inflow demister element inside the flow distribution chamber is advantageous in that even though the flow speed is so high through the flow distribution chamber that substantially no oil will be separated in the inflow demister element, the inflow demister element will still increase the size of the oil particles or aerosols of the oil-containing refrigerant, thus making the subsequent oil separation more efficient.
In an aspect of the invention, the shell-and-plate condenser comprises an inflow demister element arranged at the at least one entrance hole.
Arranging the inflow demister element at the entrance hole is advantageous in that hereby the oil droplet distribution of the entire oil-containing refrigerant is altered before the gas flow leaves the flow distribution chamber.
In an aspect of the invention, the flow distribution chamber's length in the longitudinal direction is substantially the same as the plate stack's length in the longitudinal direction.
Forming the flow distribution chamber substantially as long as the plate stack is advantageous in that in that the inflow hereby can be distributed over a large area - thus enabling better oil separation.
In an aspect of the invention, the outflow demister element's length in the longitudinal direction is substantially the same as the plate stack's length in the longitudinal direction.
Forming the outflow demister element substantially as long as the plate stack is advantageous in that it hereby is possible to form the outflow demister element with a large area - thus enabling better oil separation.
In an aspect of the invention, the flow distribution chamber is formed as a circular tube.
Forming the flow distribution chamber as a circular tube is advantageous in that the circular shape is space-efficient and it enables a more efficient and even flow distribution.
In an aspect of the invention, the flow guide channel is arranged to guide the oil-containing refrigerant downwards towards an impact surface before the oil-containing refrigerant is lead through the outflow demister element.
Guiding the oil-containing refrigerant downwards before it enters the demister element is advantageous in that it provides for a more space-efficient and compact design of the oil separator unit. And arranging an impact surface where the oil-containing refrigerant changes direction and continues through the outflow demister element is advantageous in that larger drops and particles will be flung out of the gas flow and collected on the impact surface before the gas flow enters the outflow demister element - thus, increasing the overall efficiency of the oil separator and reducing the risk of clogging the demister element.
In an aspect of the invention, a perforated flow distribution device is arranged across the flow guide channel between the flow distribution chamber and the outflow demister part of the flow guide channel.
Arranging a perforated flow distribution device across the entire flow guide channel is advantageous in that it enables better distribution of the flow before it hits the outflow demister element.
In an aspect of the invention, the degree of perforation of the flow distribution plate is increased upwards in the flow distribution plate.
In the outflow demister element the separated oil will travel downwards due to gravitational pull and if the flow speed through the bottom of the outflow demister element is too high the risk of separated oil being drawn out of the outflow demister element is increased. Increasing the open area of the flow distribution plate upwards is therefore advantageous in that it will decrease the flow at the bottom of the outflow demister element.
In an aspect of the invention, the entrance hole is arranged at an entrance hole end of the flow distribution chamber and wherein the inner volume of the flow distribution chamber is larger at the entrance hole end than at the opposite end of the flow distribution chamber.
The more holes in the outer shell of the condenser the more complex it is to manufacture and the more expensive it becomes e.g. due to strength compensation. It is therefore advantageous to provide the condenser with only one entrance hole. But no matter if this entrance hole is positioned at the middle or at one end of the flow distribution chamber the outgoing flow of oil-containing refrigerant will not be substantially evenly distributed over the length of a flow distribution chamber with a constant cross sectional area due to pressure drop. This could be solved by varying the size of the exit holes over the length of the oil-containing refrigerant but in this embodiment this problem is solved by decreasing the inner volume of the flow distribution chamber in a direction away from the entrance hole.
In an aspect of the invention, the oil separator unit comprises at least two outflow demister elements arranged on either sides of the flow distribution chamber.
Arranging an outflow demister element on either sides of the flow distribution chamber is advantageous in that it is a simple way forming a small and compact oil separator unit while increasing the size of the outflow demister element.
In an aspect of the invention, a centre of the flow distribution chamber is arranged above a centre of the outflow demister element.
As previously explained it is advantageous that the oil-containing refrigerant at least to some degree flows upwards while passing the outflow demister element. Thus, to form a compact oil separator unit suited for being arranged over a plate stack inside a very crammed outer shell it is advantageous that the centre of the flow distribution chamber is arranged above the centre of the outflow demister element to enable that the flow is directed downwards before reaching the outflow demister element.
In an aspect of the invention, the tubular outer shell comprises endplates and wherein the at least one entrance hole is arranged in at least one of the endplates.
Strength- and cost-wise it is advantageous to arrange the entrance hole in an endplate.
In an aspect of the invention, the tubular outer shell is formed as a circular tube provided with endplates.
The round shape of the outer shell ensures an even distribution of mechanical loads, without the stress concentrations that occur in the corners of polygonal constructions.
In an aspect of the invention, the endplates are welded to the outer shell.
Welding the endplates is an inexpensive way of ensuring that the pressure vessel is both strong and tight.
In an aspect of the invention, the tubular outer shell is a pressure vessel designed and/or approved to withstand a pressure between 0.7 and 15 MPa, preferably between 1.5 and 10 and most preferred between 2.5 and 7.5 MPa.
If the pressure, the shell is designed to withstand, is too low, the risk of leakage or even explosion is too big. However, if the pressure, the shell is designed to withstand, is too high the shell becomes too heavy and expensive. Thus, the present pressure ranges presents an advantageous relationship between safety and cost.
The invention further relates to a method for removing oil from a refrigerant by means of an oil separator unit arranged inside a tubular outer shell of a shell-and-plate condenser. The method comprises the steps of:

leading oil-containing refrigerant into a flow distribution chamber of the oil separator unit, wherein the oil separator unit is arranged at a upper part of the tubular outer shell and wherein the flow distribution chamber will change the general flow direction of the oil-containing refrigerant from being substantially parallel with a longitudinal direction of the tubular outer shell to being substantially transversal to the longitudinal direction of the tubular outer shell,
leading the oil-containing refrigerant through an outflow demister element of the oil separator unit, the outflow demister element being arranged in the substantially transversal flow path to separate oil from the refrigerant, and
leading the substantially oil-free refrigerant down through a stack of corrugated heat transfer plates arranged below the oil separator unit.

Changing the general flow direction of the oil-containing refrigerant from being substantially parallel with a longitudinal direction of the tubular outer shell to being substantially transversal to the longitudinal direction of the tubular outer shell is advantageous in that it provides for a more even flow distribution and because it enables a larger oil separator design extending in the longitudinal direction of the shell.
In an aspect of the invention, the shell-and-plate condenser is a shell-and-plate condenser according to any of the previously mentioned shell-and-plate condensers.
The invention also relates to use of a shell-and-plate condenser according to any of the previously mentioned shell-and-plate condensers for removing oil from a refrigerant and for condensing the refrigerant in a refrigeration cycle also comprising an evaporator and a compressor.
Using a shell-and-plate condenser comprising an oil separator unit according to the present invention for condensing and removing oil from a refrigerant in a refrigeration cycle is advantageous in that it ensures a more efficient and less expensive refrigeration cycle.

Figures

The invention will be explained further herein below with reference to the figures in which:

Fig. 1: shows an embodiment of a shell-and-plate condenser, as seen in perspective,
Fig. 2: shows a cross section through the middle of a shell-and-plate condenser, as seen from the front,
Fig. 3: shows an oil separator unit, as seen in perspective,
Fig. 4: shows an oil separator unit, as seen from the front,
Fig. 5: shows a cross section through an oil separator unit, as seen from the side, and
Fig. 6: shows a flow distribution chamber, as seen in perspective.

Detailed description

Figure 1 shows an embodiment of a shell-and-plate condenser 1, as seen in perspective.
In this embodiment the shell-and-plate condenser 1 according to the present invention is used for condensing a refrigerant in a refrigeration cycle. I.e. after the condensed refrigerant leaves the shell-and-plate condenser 1 it is typically directed to an expansion valve, which will reduce the pressure making at least some of the refrigerant evaporate and thus making its temperature drop drastically. At this stage the cold refrigerant is then used for cooling purposes by which the entire refrigerant evaporates. The gaseous refrigerant is then directed through a compressor compressing the refrigerant, which in turn raises its temperature drastically. The hot gaseous refrigerant is then lead to the condenser 1 where the gaseous refrigerant is condensed into a liquid refrigerant. In an embodiment the gaseous refrigerant could also be lead through a de-superheater, where the refrigerants temperature is lowered to just above the condensation temperature before it enters the condenser 1. And in an embodiment the liquid refrigerant could be cooled further in a subcooler before the cycle is repeated.
In this embodiment the shell-and-plate condenser 1 comprises a single stack of heat transfer plates 5 and an oil separator unit 3 arranged inside a circular tubular outer shell 8. However in another embodiment the shell-and-plate condenser 1 could comprise two stacks of heat transfer plates 5 e.g. separated by a wall or plate arranged at the middle of the condenser 1 so that the two plate stacks 5 could be separately fed from either ends of the condenser 1. In another embodiment the condenser 1 could also comprise more than two plate stacks 5 such as three, four, six or more.
In this embodiment the shell 8 is formed by rolling a single sheet and then welding it together along the longitudinal seam. Forming the shell 8 as a single monolithic cylindrical tube increases the strength of the shell 8 and reduces the risk of unwanted stress concentrations in the shell 8. In another embodiment the shell 8 could also be formed by a number of shell parts welded together or bolted together either axially or radially to ensure that the shell 8 subsequently can be opened e.g. in case of maintenance and/or repair.
The shell-and-plate heat condenser 1 is a versatile design which combines the strength of a shell-and-tube heat exchanger with the thermal efficiency of a plate heat exchanger in that the shell-and-plate heat exchanger combines the pressure and temperature capabilities of a typically cylindrical shell with the excellent heat transfer performance of a plate heat exchanger. The round or oblong shell and plates ensure an even distribution of mechanical loads, without the stress concentrations that occur in the corners of rectangular plates. Thus, the shell-and-plate condenser combines the benefits of a traditional shell and tube type heat condenser but with the high efficiency provided for in a plate type condenser.
Fig. 2 shows a cross section through the middle of a shell-and-plate condenser 1, as seen from the front.
In this embodiment the oil separator unit 3 is arranged directly above the plate stack 5 in an upper part 18 of the tubular outer shell 8 and in this embodiment the entrance hole 2 of the oil separator unit 3 is arrange in an endplate 21. Thus, in this embodiment the oil-containing refrigerant vapour enters the oil separator unit 3 at the top of the condenser 1 as illustrated by the arrows. During its passage through the oil separator unit 3 oil will be separated from the refrigerant vapour which then will continue downwards through the plate stack 5 which will condense the refrigerant vapour to liquid refrigerant. The liquid refrigerant will then continue downwards towards the bottom of the shell 8 from which it will be drained from the condenser 1 through the refrigerant exit hole 24.
In this embodiment the heat transfer plates 5 are welded (or bonded) back to back along the outer periphery to form so-called cassettes. A number of these cassettes are then welded together around respective inlet openings and outlet openings to form a heat transfer plate pack 5. A coolant flow is then established inside the cassettes by leading coolant into the stack 5 through a plate stack outlet opening 19 and out again through a plate stack inlet opening 20 arranged in an endplate 21. Inside the cassettes the coolant will flow from inlet opening to outlet opening (in alternate directions) while the refrigerant flows across the outside of (i.e. between) the cassettes.
In this embodiment the plate stack outlet opening 19 and the plate stack inlet opening 20 of the plate stack 5 are arranged in the same endplate 21 - as also illustrated in figure 1 - and in this embodiment the oil separator unit 3 is substantially symmetrically arranged inside the shell 8 so that the entrance hole 2, the plate stack outlet opening 19 and the plate stack inlet opening 20 are all substantially vertically aligned.
However, in another embodiment the entrance hole 2, the plate stack outlet opening 19 and the plate stack inlet opening 20 would not be aligned and/or one or more of the entrance hole 2, the plate stack outlet opening 19 and the plate stack inlet opening 20 would also or instead be arranged in the other endplate 21 and/or in the shell 8.
In this embodiment the plates 5 are formed substantially semi-circular to fit into a circular shell 8 and to allow room above the plate stack 5 for the oil separator unit 3 but in another embodiment the plates 5 could be formed differently e.g. if the oil separator unit was formed differently or to fit into a shell 8 of a different shape.
In this embodiment the plates 5 are provided with an embossed pattern of channels (not shown) so that when a cassette is formed the coolant can flow through these channels from the inlet opening to the outlet opening. The embossed pattern also increases the surface area of the plates 5 thus increasing its heat transferring ability.
In this embodiment the oil separator unit 3, the shell 8, and the endplates 21 are all made from steel and all the plates 5 are made from stainless steel because of this materials strength and durability but in another embodiment all, some or parts of the condenser parts could be made from another material such as titanium, aluminium, a composite material or other.
In this embodiment the coolant flowing through the cassettes of the plate stack 5 is water e.g. circulating through an external air cooled heat exchanger or transporting the absorbed heat to a particular place where it can be utilised.
However, in another embodiment the coolant could be brine or another form of natural or artificial coolant suitable for flowing through a condenser 1.
In this embodiment the refrigerant being condensed in the condenser 1 is ammonia but in another embodiment the refrigerant could be carbon dioxide, Butane, a HFC gas, water vapour or another fluid suitable for acting as a refrigerant in a shell-and-plate condenser 1.
Fig. 3 shows an oil separator unit 3, as seen in perspective and fig. 4 shows an oil separator unit 3, as seen from the front.
In this embodiment the oil separator unit 3 comprises a flow distribution chamber 4 substantially extending the entire length of the oil separator unit 3 and a flow guide channel 9 formed around the flow distribution chamber 4. The flow guide channel 9 will guide the refrigerant from the flow distribution chamber 4 and downwards to an impact surface 13 arranged at the bottom of the oil separator unit 3 from which the refrigerant will be flow upwards through one of two outflow demister elements 10 arranged substantially symmetrical on either sides of the flow distribution chamber 4 and the impact surface 13.
The outflow demister elements 10 are arranged in a demister part 11 of the flow guide channel 9 and in this embodiment the demister part 11 is formed with a demister part angle DA of approximately 45° upwards so that the refrigerant is directed upwards while passing through the outflow demister elements 10. However in another embodiment the demister part 11 could be formed with another angle such as 20°, 35°, 55°, 70° or other.
The substantially oil-free refrigerant will leave the oil separator unit 3 at the upper end of the demister part 11 and travel down through the plate stack 5 as illustrated by means of the arrows on fig. 2.
However, in another embodiment the oil separator unit 3 could comprise only a single demister part 11 and/or a single outflow demister element 10 and/or in another embodiment the outflow demister element 10 could be arranged in more or less direct succession of the flow distribution chamber 4 e.g. if the outflow demister element 10 where surrounding or at least partly surrounding the flow distribution chamber 4 or at least only separated by a short flow guide channel 9.
During the flow through the outflow demister elements 10 oil will be separated from the refrigerant and the liquid oil will be pulled downwards by gravity towards the oil collection tray 22 at the bottom of the oil separator unit 3. The bottom of the oil collection tray 22 is sloping to one side so that the liquid oil may be drained from the oil separator unit 3 through an oil drainage hole 23 arranged in one of the endplates 21 as illustrated in fig. 1 and 2. In an embodiment the drained oil can be lead back to the compressor for reuse.
In this embodiment a perforated flow distribution device 14 is arranged all the way across the flow guide channel 9 just before each of the two outflow demister elements 10. The perforated flow distribution device 14 will distribute the refrigerant flow better before it enters the outflow demister elements 10. The increased degree of perforation upwards of the perforated flow distribution device 14 is shown more clearly on fig. 5.
In this embodiment the centre 16 of the flow distribution chamber 4 is arranged above the centre 17 of the outflow demister elements 10 but in another embodiment the centre 16 of the flow distribution chamber 4 could be substantially horizontally aligned with the centre 17 of the outflow demister elements 10 or the centre 16 of the flow distribution chamber 4 could even be arranged below the centre 17 of the outflow demister elements 10.
Fig. 5 shows a cross section through an oil separator unit 3, as seen from the side.
In this embodiment the oil separator unit 3 is provided with an inflow demister element 12 arranged at the entrance hole end 15 inside the flow distribution chamber 4. However in another embodiment the inflow demister element 12 could be arranged to extend throughout substantially the entire length of the flow distribution chamber 4.
In this embodiment the perforated flow distribution device 14 is formed as a plate arranged at the bottom of the outflow demister element 10 and perforated by elongated holes. The size of the holes increases upwards so that the degree of perforation of the perforated flow distribution device 14 is increased upwards to distribute the flow through the outflow demister element 10 better.
In this embodiment the condenser 1 is only provided with a single entrance hole 2 arranged in a single endplate 21 at the entrance hole end 15 of the flow distribution chamber 4. However in another embodiment entrance holes 2 could be provided in both endplates 21 enabling refrigerant inflow at both ends of the flow distribution chamber 4 and/or the shell 8 could be provided with a centrally arranged, entrance hole 2 or a number of entrance holes 2 distributed along the longitudinal length of the shell 8.
In this embodiment the cross sectional area of the flow distribution chamber 4 is around 9,500 mm² and the area is substantially constant throughout the entire longitudinal length of the flow distribution chamber 4 - thus, in this embodiment the inner volume of the flow distribution chamber 4 is substantially constant throughout the length of the flow distribution chamber 4. However in another embodiment the inner volume at the entrance hole end 15 could be larger than at the opposite end of the flow distribution chamber 4 e.g. to compensate for drop in pressure. The inner volume of the flow distribution chamber 4 could be reduced by forming the flow distribution chamber 4 conically or by providing a solid body inside the flow distribution chamber 4 opposite the entrance hole end 15. Or in another embodiment the pressure drop could be compensated by adjusting the size of the exit holes along the length of the flow distribution chamber 4.
In another embodiment the cross sectional area of the flow distribution chamber 4 could be smaller or bigger e.g. depending on the specific use, the specific capacity, the specific refrigerant or other.
Fig. 6 shows a flow distribution chamber 4, as seen in perspective
In this embodiment the flow distribution chamber 4 is formed as a hollow circular tube comprising a number of elongated exit holes 7 arranged in the sidewall 6 substantially in the entire length of the flow distribution chamber 4.
However in another embodiment the flow distribution chamber 4 could be formed differently such as square, triangular, oval, polygonal or with some other more or less complex shape. Thus, in another embodiment the exit holes 7 could only be arranged in only one or some of the sidewalls 6 i.e. in two or three sidewalls 6.
In this embodiment the exit holes 7 constitute around 8 % of the total area of the effective area or the sidewall 6 of the flow distribution chamber 4 to ensure an efficient flow distribution along the length of the flow distribution chamber 4. However, if the same capacity was needed with a flow distribution chamber 4 having a smaller cross sectional area the exit holes 7 would have to constitute a corresponding larger percentage of the total area and vice versa if the cross sectional area was larger.
In another embodiment the perforation in the perforated flow distribution device 14 and/or the exit holes 7 in the sidewall 6 of the flow distribution chamber 4 could instead or also be formed differently such as circular, oval, polygonal or other or the perforated flow distribution device 14 and/or the flow distribution chamber 4 could be formed by or comprise some sort of mesh, nonwoven filament structure, latticework or other providing the same technical effect as the perforations and the exit holes 7.
In the foregoing, the invention is described in relation to specific embodiments of shell-and-plate condensers 1, oil separator units 3, demister parts 11 and other as shown in the drawings, but it is readily understood by a person skilled in the art that the invention can be varied in numerous ways within the scope of the appended claims.

List

1.: Shell-and-plate condenser
2.: Entrance hole
3.: Oil separator unit
4.: Flow distribution chamber
5.: Heat transfer plates
6.: Sidewall
7.: Exit holes
8.: Shell
9.: Flow guide channel
10.: Outflow demister element
11.: Demister part
12.: Inflow demister element
13.: Impact surface
14.: Perforated flow distribution device
15.: Entrance hole end
16.: Centre of flow distribution chamber
17.: Centre of outflow demister element
18.: Upper part of tubular outer shell
19.: Plate stack outlet opening
20.: Plate stack inlet opening
21.: Endplate
22.: Oil collection tray
23.: Oil drainage hole
24.: Refrigerant exit hole
DA.: Angle of demister part

Claims

A shell-and-plate condenser (1) comprising a stack of corrugated heat transfer plates (5) arranged inside a tubular outer shell (8), wherein said outer shell (8) comprises at least one entrance hole (2) for leading oil-containing refrigerant into said condenser (1), said condenser (1) further comprising an integrated oil separator unit (3) arranged above said plate stack (5), wherein said oil separator unit (3) includes
at least one flow distribution chamber (4) being connected to at least one of said entrance holes (2), said flow distribution chamber (4) substantially extending in a longitudinal direction of said tubular outer shell (8) and wherein said flow distribution chamber (4) comprises at least one sidewall (6) comprising a plurality of exit holes (7) through which said oil-containing refrigerant leaves said flow distribution chamber (4) in a direction substantially transversal to said longitudinal direction of said outer shell (8) and flows out into a flow guide channel (9) of said oil separator unit (3), wherein said oil separator unit (3) further includes at least one outflow demister element (10) arranged in a demister part (11) of said flow guide channel (9).
A shell-and-plate condenser (1) according to claim 1, wherein said demister part (11) of said flow guide channel (9) is arranged in an angle (DA) of between 5° and 85°, preferably between 15° and 75° and most preferred between 30° and 60° upwards in relation to a horizontal plane.
A shell-and-plate condenser (1) according to claim 1 or 2, wherein said exit holes (7) constitutes between 1% and 90%, preferably between 2% and 50%, and most preferred between 3% and 25% of the total area of said flow distribution chamber (4).
A shell-and-plate condenser (1) according to one or more of the preceding claims, wherein said flow distribution chamber (4) comprises an inflow demister element (12) arranged inside said flow distribution chamber (4).
A shell-and-plate condenser (1) according to one or more of the preceding claims, wherein said shell-and-plate condenser (1) comprises an inflow demister element (12) arranged at said at least one entrance hole (2).
A shell-and-plate condenser (1) according to one or more of the preceding claims, wherein said flow distribution chamber's length in said longitudinal direction is substantially the same as said plate stack's length in said longitudinal direction.
A shell-and-plate condenser (1) according to one or more of the preceding claims, wherein said outflow demister element's length in said longitudinal direction is substantially the same as said plate stack's length in said longitudinal direction.
A shell-and-plate condenser (1) according to one or more of the preceding claims, wherein said flow distribution chamber (4) is formed as a circular tube.
A shell-and-plate condenser (1) according to one or more of the preceding claims, wherein flow guide channel (9) is arranged to guide said oil-containing refrigerant downwards towards an impact surface (13) before said oil-containing refrigerant is lead through said outflow demister element (10).
A shell-and-plate condenser (1) according to one or more of the preceding claims, wherein a perforated flow distribution device (14) is arranged across said flow guide channel (9) between said flow distribution chamber (4) and said outflow demister part (11) of said flow guide channel (9).
A shell-and-plate condenser (1) according to claim 10, wherein the degree of perforation of said flow distribution plate (14) is increased upwards in said flow distribution plate (14).
A shell-and-plate condenser (1) according to one or more of the preceding claims, wherein said entrance hole (2) is arranged at an entrance hole end (15) of said flow distribution chamber (4) and wherein the inner volume of said flow distribution chamber (4) is larger at said entrance hole end (15) than at the opposite end of said flow distribution chamber (4).
A shell-and-plate condenser (1) according to one or more of the preceding claims, wherein said oil separator unit (3) comprises at least two outflow demister elements (10) arranged on either sides of said flow distribution chamber (4).
A shell-and-plate condenser (1) according to one or more of the preceding claims, wherein a centre (16) of said flow distribution chamber (4) is arranged above a centre (17) of said outflow demister element (10).
A method for removing oil from a refrigerant by means of an oil separator unit (3) arranged inside a tubular outer shell (8) of a shell-and-plate condenser (1), said method comprising the steps of:
• leading oil-containing refrigerant into a flow distribution chamber (4) of said oil separator unit (3), wherein said oil separator unit (3) is arranged at a upper part (18) of said tubular outer shell (8) and wherein said flow distribution chamber (4) will change the general flow direction of said oil-containing refrigerant from being substantially parallel with a longitudinal direction of said tubular outer shell (8) to being substantially transversal to said longitudinal direction of said tubular outer shell (8),

• leading said oil-containing refrigerant through an outflow demister element (10) of said oil separator unit (3), said outflow demister element (10) being arranged in said substantially transversal flow path to separate oil from said refrigerant, and

• leading said substantially oil-free refrigerant down through a stack of corrugated heat transfer plates (5) arranged below said oil separator unit (3).
A method according to claim 15, wherein said shell-and-plate condenser (1) is a shell-and-plate condenser (1) according to any of claims 1-14 and 17-20.
A shell-and-plate condenser (1) according to one or more of claims 1-14, wherein said tubular outer shell (8) comprises endplates (21) and wherein said at least one entrance hole (2) is arranged in at least one of said endplates (21).
A shell-and-plate condenser (1) according to one or more of claims 1-14, wherein said tubular outer shell (8) is formed as a circular tube provided with endplates (21).
A shell-and-plate condenser (1) according to claim 17 or 18, wherein said endplates (21) are welded to said outer shell (8).
A shell-and-plate condenser (1) according to one or more of claims 1-14, wherein said tubular outer shell (8) is a pressure vessel designed and/or approved to withstand a pressure between 0.7 and 15 MPa, preferably between 1.5 and 10 and most preferred between 2.5 and 7.5 MPa.
Use of a shell-and-plate condenser (1) according to any of claims 1-14 and 17-20 for removing oil from a refrigerant and for condensing said refrigerant in a refrigeration cycle also comprising an evaporator (19) and a compressor (20).