GB2069867A

GB2069867A - Device for separating liquid droplets from gases

Info

Publication number: GB2069867A
Application number: GB8103080A
Authority: GB
Original assignee: Carl Munters Euroform GmbH and Co KG
Current assignee: Carl Munters Euroform GmbH and Co KG
Priority date: 1980-02-06
Filing date: 1981-02-02
Publication date: 1981-09-03
Also published as: NL8100360A; DE3004241A1; FR2474886A1; BE887395A

Abstract

A device for separating liquid droplets from gases comprises a stack of corrugated plates 14 joined together peak-to-trough to define a plurality of flow channels 9 for droplet-laden gases, each channel 9 having an inlet section 8 whose axis is inclined relative to the gas flow direction 7, and vertical flow surfaces 13, upstream of the sections 8, parallel to the gas flow direction and serving to drain off liquid running back from section 8. Surfaces 13 may be moulded on to the plate stack or may be separate strips intersecting the flow channels. The device operates in a cooling tower, downstream of heat exchanger plates. <IMAGE>

Description

SPECIFICATION Device for separating liquid droplets from gases The invention relates generically to a device for separating liquid droplets from gases. In particular it is applicable to a device for separating water droplets from air in cooling towers, the device consisting of a plurality of plates which are curved or angled to form corrugations and which are assembled, with the peaks and valleys of the corrugations being align relative to each other, to form flow channels for the droplet-laden gases, and joined to each other where they are in contact.

Droplet separators of this type are customary, for example, in cooling towers in which water is cooled by cooling air in counter-current or in crossflow. During direct contact with the water in the heat exchanger, the air entrains droplets. The purpose of the droplet separator is to separate the droplets out again, which have been entrained by the air, before the latter leaves the cooling tower.

Devices of the generic type have been disclosed by U.S. Patent Specification 2 555 125. As described in this specification, the corrugations in the plates run almost sinusoidally, so that the plates are in line contact when they are assembled, with the peaks and valleys of the corrugations aligned. In the droplet separator device known from German Patent Specification 2 738 257, however, the corrugations in the plates are formed trapezoidally. The flow channels, formed by assembly of the corrugated plates, for the dropletladen gas are meandering, so that deflection points are formed where the droplets precipitate, collect on the bottom of the channel and flow off downwards. Run-out toes formed at the base of the channels then facilitate the collection and outflow of the liquid.

It is the aim of the invention to increase the gas velocity in order to intensity the heat exchange.

For this purpose, it is necessary to achieve the object of improving the droplet separator in such a way that rapid and thorough separation of droplets from the gas is ensured even at a higher gas velocity.

According to a first aspect of the invention there is provided a device for separating liquid droplets from gases, in particular from air in cooling towers, consisting of a plurality of plates which are curved or angled into corrugations and which are assembled, with the peaks and valleys of the corrugations being aligned in each case, to form flow channels for the droplet-laden gases and which are joined to each other where they are in contact, characterised in that the inflow section of the flow channels is inclined at an angle ct to the direction of flow, forming an impingement surface, and parallel vertical surfaces are formed on the inflow side.

According to a second aspect of the invention there is provided a device for separating liquid droplets from gases comprising a stack of corrugated plates defining a plurality of flow channels for droplet-laden gases each channel having an inlet section with a port for receiving gas flowing in a predetermined direction and an impingement surface forming part of the channel wall and in the immediate vicinity of the port for deflecting the gas from this direction as well as having parallel flow surfaces parallel to the gas flow direction for guiding droplet flow to the channel bottom.

Whilst the known separators have, in the flow channels, an inflow section which is parallel to the direction of flow of the droplet-laden gases, the inflow section of the flow channel in the solution according to the invention, which inflow section is inclined obliquely to the direction of flow, already represents a first impingement surface for the separation of the droplets, where an intesive droplet separation already takes place because the droplet content is still high. Since this quantity of separated liquid can leave the droplet separator again by the shortest route, the separator is not so heavily loaded since the quantity of liquid separated therein along the further path of the gases is smaller, and this also makes it impossible for the air again to pick up and carry over droplets from the water flowing in counter-current to the air.

With particular advantage, the device according to the invention is suitable for crossflow-operated cooling towers, wherein the cooling air flows horizontally in the heat exchanger and is deflected into the vertical direction after the droplets have been separated out, since the outflow section, according to the invention, then has an upward inclination in the direction of flow. In fact, the air is thus deflected into the desired direction even before it leaves the droplet separator.

According to a further advantageous embodiment of the device according to the invention, the channels are to be formed by straight sections which are assembled in an angled arrangement, the mutual angles ss and y being > 900, but smaller than 1800. A further intensification of droplet separation is effected by the abrupt deflection of the gases at the bending points of the flow channel.

Whilst the known droplet separators according to U.S. Patent Specification 2 555 125 and P 27 38 257.6-43 can be installed in crossflow cooling towers only when inclined at an angle the device according to the invention can be installed vertically due to the inclined inlet channels; this leads to a considerable saving of space, and this design is easier to construct.

The parallel vertical surfaces can extend in the plane of the plates. According to a further advantageous embodiment of the device according to the invention, however, it is envisaged to insert, as downflow surfaces, vertical strips extending parallel to the plane of the plates between the corrugated plates on the inflow side.

On the one hand, the surfaces act as flow straighteners and, on the other hand, they form downflow surfaces for the liquid droplets which have been separated out and which, after leaving the flow channels, can flow off downwards in an orderly manner along these surfaces, without dropping back into the gas stream.

To improve the liquid run-off in the flow channels, a section of the surface in contact with the adjoining plate can be bent off from at least one plate at the bottom of the flow channel, to form a run-out toe. Preferably, this run-out toe should have the form of a capillary groove. These run-out toes improve the run-off of the separated droplets and thus permit a higher flow velocity in the channels.

One embodiment of the invention will now be described, by way of example with reference to the accompanying drawing: Figure 1 is a diagrammatic representation of a water cooler using air for cooling and comprising a droplet separator according to the invention; Figure 2 is a partial longitudinal section of the droplet separator according to Figure 1; Figure 3 is a section along the line A-A from Figure 2; Figure 4 is a view of part of the separator; Figure 5 shows the-section B from Figure 4 on an enlarged scale, with an embodiment of the runout groove; Figure 6 is as Figure 5 but with another form of the run-out toe; Figure 7 shows a partial longitudinal section of another droplet separator according to the invention with a downflow surface inserted; and Figure 8 shows the inflow side of the droplet separator corresponding to the embodiment according to Figure 7.

The cooler shown in Figure 1 consists of the heat exchanger units 1 which are formed by a plurality of parallel plates, water from containers 2 flowing through between these plates and air flowing through in crossflow thereto in the direction of the arrows 3. The water thus delivers its heat to the air and is then collected in a catch vessel 4 and passed on from there to further use.

The droplet separators 5 are located on the air outlet side of the heat exchangers 1, the liquid droplets which have been carried over are separated out of the air while the latter flows through the separators, and the droplets are likewise collected in the catch vessel 4. The air freed from liquid droplets then passes into the open due to the suction draught of the fan 6.

The form of the droplet separator, according to the invention, can be seen from Figures 2 to 8.

According to Figures 3 and 4, the flow channels 9 are formed by the corrugated design of plates 14 which are assembled with the peaks 15 and valleys 1 6 of the corrugations in alignment and are joined to each other at the contact surfaces.

The most essential features of the droplet separator 5 according to the invention are the inflow section 8 of the flow channel 9, which inflow section is inclined at the angle a to the direction 7 of flow of the air which enters the droplet separator 5 and is laden with liquid droplets, and the downflow surfaces, arranged vertically in the plane of the plates, for the separated liquid droplets. The flow channels 9 in the droplet separator 5 are each formed by three straight sections 8, 10, 1 1 the mutual angles p and y of these being greater than 900 but smaller than 1 800. For crossflow-operated cooling towers, the outflow section 11 can have an obliquely upward inclination in order to deflect the cooling air, which leaves the separator in the direction of the arrow 12, into the desired outflow direction.

Parallel vertical surfaces 13, along which the liquid flowing out of the flow channels 9 is passed out into a collection basin, are moulded, as a flow straightener and droplet run-off surface, onto the inflow side of the droplet separator 5. To minimise the pressure drop, the run-off surface moulded on according to Figures 2 and 4 can be replaced by run-off surfaces 1 9, which, corresponding to Figures 7 and 8, are separately inserted in the form of thin strips between the corrugated plates, so that the separator channels at the inlet are fully open.

As the details B in Figures 5 and 6 show, sections 1 7 on at least one of the plates 14 can be angled off at the contact surface of the plates 14, thereby forming run-out toes 18, in which the water dripping off can collect and run out, on the bottom of the flow channel 9. Forming the runout toe 18 as a capillary groove is therefore particularly advantageous, since even very small droplets collect therein.

Claims

1. Device for separating liquid droplets from gases, in particular from air in cooling towers, consisting of a plurality of plates which are curved or angled into corrugations and which are assembled, with the peaks and valleys of the corrugations being aligned in each case, to form flow channels for the droplet-laden gases and which are joined to each other where they are in contact, characterised in that the inflow section of the flow channels is inclined at an angle a to the direction of flow, forming an impingement surface, and parallel vertical surfaces are formed on the inflow side.

2. Device according to claim 1 for crossflowoperated cooling towers, wherein the cooling air flows horizontally in the heat exchanger and is deflected into the vertical direction after the droplets have been separated out, characterised in that the outflow section has an upward inclination in the direction of flow.

3. Device according to one of claims 1 or 2, characterised in that the channels are formed by straight sections which are assembled in an angled arrangement, the mutual angles P and y being > 900, but smaller than 1800.

4. Device according to one of claims 1 to 3, characterised in that vertical strips extending parallel to the plane of the plates are inserted, as downflow surfaces, between the corrugated plates on the inflow side.

5. Device according to one of claims 1 to 4, characterised in that, at least on one plate, at the bottom of the flow channel, a section of the surfaces in contact with the adjoining plate is bent to form a run-out toe.

6. Device according to claim 5, characterised in that the run-out two is formed as a capillary groove.

7. Device for sepatating liquid droplets from gases comprising a stack of corrugated plates defining a plurality of flow channels for dropletladen gases each channel having an inlet section with a port for receiving gas flowing in a predetermined direction and an impingement surface forming part of the channel wall and in the immediate vicinity of the port for deflecting the gas from this direction as well as having parallel flow surfaces parallel to the gas flow direction for guiding droplet flow to the channel bottom.

8. Device for separating liquid droplets from gases substantially as hereinbefore described with reference to the embodiment of Figures 7 and 8 of the accompanying drawings.