WO1988002282A1 - A liquid distribution apparatus - Google Patents

Abstract

An apparatus for distribution of a liquid flow (1') as equal part flows (m) to any number of outlet apertures (32) comprises an open vessel (2) fed by said flow (1') and any number of straight, parallel channels (3) of equal cross section feeding individually said apertures (32) and fed from a liquid bath (11) in said vessel (2). The apertures (32) are thus positioned (4) that a static liquid pressure (h) for flow propulsion in any one of the channels (3k) is essentially proportioned to the channel length (1).

Description

A LIQUID DISTRIBUTION APPARATUS

The present invention relates to an apparatus for distribution of a flow of liquid to a plurality of outflow apertures.

The invention may be applied for distribution of a liquid flow in any desired manner as liquid films along any number of vertical surfaces e. g. for the purpose of heat or mass transfer i n known manner .

The invention may also be applied for sprinkling of a liquid flow in any desired pattern over a surface.

Objects of the invention are as follows.

An apparatus that is cheap and simple in construction and that may be operated in a reliable mode for a great variation of distribution patterns and liquids of a varied viscosity.

An apparatus that may be operated with a neglible pressure drop.

An apparatus that may be operated unaffected by contamination of the liquid by solids and that further is simple to rinse even during its proper operation.

These objects and others listed below are according to the invention achieved by a liquid distribution apparatus for distribution of a flow of liquid as equal part flows to a plurality of outlet apertures by means of gravity characterized in that it comprises an open vessel, means to supply said flow to said vessel; a plurality of parallel channels of equal cross section for propulsion of said part flows, said channels being positioned with their inlet apertures coupled to said vessel and with their said outlet appertures along an inclining plane parallel to a horizontal axis.

One further object of the invention is an apparatus that may retain the same distribution pattern within a range of liquid mass flow.

Another further object of the invention is open ventilation of all inherent conduits for effective release of gas bubbles enclosed in the liquid flow, thus preventing the forming of air pockets detrimental to liquid flow.

A basic principle according to the invention is that each of a plurality of outlet apertures is feeded by a separate flow channel from an open bath of liquids common to all channels, and that for any channel rules that a static liquid pressure for flow propulsion is essentially proportional to channel length. Hence a uniform mass flow is achieved for all channels concerned. The use of straight flow channels with in this connexion fairly wide cross sections reduces further sharply a sensitivity to settling of solids or gas bubbles. These facts allow a controlled ditribution of liquid in any range of mass flow, distibution pattern and viscosity and admits further a certain grade of solid pollution of the liquid. The working mode differs fundamentally from a generally used and in many forms developed liquid distribution technique, namely the use of dispersed outflow apertures with high pressure drops, combined with head conduits with relatively small pressure drop. These techniques show the inherent drawbacks of relatively high working pressures, sensitivity to contamations and difficulty of cleaning.

The invention will be described in more detail below, reference being made to the accompanying drawings, in which figure 1 and figure 2 illustrate in section and plan a distribution apparatus.

Fig 3 illustrates in section the formation of liquid films on vertical surfaces and fig 4 illustrates a working mode of sprinkling over a horizontal surface.

Referring to fig 1 and fig 2 the invention comprises a vessel 2 containing an open bath 11 of liquid 1, supplied to the vessel as a liquid flow 1'.

A plurality of straight channels 3 of equal flow cross section 33 and parallel to each other eire anchored to the vessel 2 with their inlet apertures 3 communicating with the liquid bath 11. The outlet apertures 32 of the channels 3 are positioned along an inclining plane 4, that is parallel to a horizontal axis 21. The plane 4 strikes the bath 11 at a liquid level 41 above the inlet apertures 31.

For a straight plane 4 rules geometrically that a ratio h/l is equal to all channels 3, where "h" denotes the vertical distance from said liquid level 41 to any one 32k of the outlet apertures and " 1 " denotes the length of the corresponding channel 3k.

The factor "h" also represents a static liquid pressure in meter water pressure, exercised by a bath 11 at the level 41 for propulsion of a part flow mk in the channel 3k. For a nonturbulent flow rules that mK = const.- h/l. Equal part flows m are accordingly obtained in all the channels 3, if the said level 41 of the bath 11 is maintained by an appropriate liquid supply flow 1'.

Preferably the channels 3 are confined groupwise as channels 3n in flat strips 34, that are cut out of a plastic or metal well material. Such a material can be exemplified by an extruded plastic well under trade name "Corrox", composed in referance to fig 3 by two parallel sheets 61, 62 and equidistant transversal partitions 63, thus forming straight, parallel channels with a square cross section. Inside dimensions may be 3 x 3, 4 x 4 or 5 x 5 mm and wall thickness around 0.1 mm.

Any strip 34 is anchored to and penetrates in a liquid sealed manner an essentially vertical slot 22 of a side wall 23 of the vessel 2 and is extended along an essentially vertically oriented plane 5 that is transversal to said horizontal axis 21.

Out of geometrical reasons the outlet apertures 32 along the top of the vertically positioned flat strip 34 will be evenly distributed along the plane 5 and accordingly a uniform liquid distribution is achieved along the strip 34. Any number of said strips 34 may be attached to the vessel 2, which accordingly is extended parallel to said axis 21.

For a nonturbulent liquid flow in a channel of square cross section applies the formulas:

h/l = 54a. m/s

Re = m.10⁶/(a.s.60)

where m = liquid flow 1/min h = flow resistance, MWp 1 = channel length, m s = channel sidelength, mm and a is a viscosity coefficient, which for water has following values, according to temperature:

tºC 0 +10 +20 +30 +40 +50 +60 +70 +80 a 1.78 1.31 1.00 0.82 0.68 0.56 0.48 0.42 0.38

A design example

For a heat transfer operation the vertical side walls of a heat exchanger shall be fed each with a water flow of +20ºC and a mass flow = 9 1/min.

The side walls are 1 m wide.

Use a str ip 34 with 30 channels 3n. Use a cross sect ion 33 = 4 x 4 mm.

Thus the slope of the outflow aperture plane 4 will be: h/l = 54. 1.9/(4⁴. 30) = 0.06 or 60 mm/m

A control of the Reynolds number Re = 0.3.10⁶ /(1.4. 60) = 1200 shows that flow conditions are nonturbulent.

Since the strip of 30 channels is from the inlet end 30 x 4 = 120 mm high, the channels 3n will slope upwards in direction of flow in a rate of 60 mm/m.

It is a preferred embodiment of the invention to have the channels 3 sloping upwards in the direction of flow as described previously. Thus air bubbles or air pockets will not be trapped in any channel, but be will be pushing upwards and escape at the outlet aperture. This embodiment may be achieved for any liquid flow by using appropriate design parameters such as number of channels 3 and dimensions of cross section 33 of the channels.

The mass flow of liquid uniformly distributed in a given apparatus is thus proportional to the slope h/l of the outlet aperture plane 4. Consequently a given" apparatus can be adopted to a range of mass flows by variation of said slope, i. e. by tilting the apparatus around a rotary axis zz parallel to axis 21 and fixing it in the appropriate position. This tilting should however not exceed into an inclination, where the channels 3n slope downwards in direction of flow.

In addition to channel flow resistance a small resistance is provided by channel inlet apertures 31. This resistance will automatically be met by a balancing liquid level 111 in the bath 11 correspondingly above said level 41.

Negliable differences in the liquid level 111 in the bath along the elongation od the bath may be achieved by a combination of an ample cross section of the vessel 2 and an outspred supply of the liquid flow 1' along the elongation of the bath.

Referring to fig 3 is illustrated the forming of uniformly distributed liquid films 12 on vertical surfaces 7, positioned along said vertical planes 5 .

A channel strip 33 is positioned at a small distance from and parallel to the surface 7. Due to an inclined cutting 321 of the outlet apertures 32 the liquid will be directed towards the surface and spread further under capillary action between the surface 7 and the adhering surface 61 of the strip 33.

Referring to fig 4 a liquid sprinkling pattern over a surface is achieved by attaching to the strip 33 a deflection-dripping plate 8, causing the same flow relations as described previously referring to fig 3. The deflection plate 8 may also serve as structural support of the channel strip.

Claims

1.

A liquid distribution apparatus for distribution of a flow (1') of a liquid (1) as equal part flows (m) to a plurality of outlet apertures (32) by means of gravity c h a r a c t e r i z e d in that it comprises an open vessel (2); means to supply said flow (1') into said vessel (2); a plurality of parallel straight channels (3) of equal cross section (33) for propulsion of said part flows (m); said channels being positioned with their inlet apertures (31) coupled to said vessel (2) and with their said outlet apertures (32) along an inclining straight plane (4) parallel to a horizontal axis (21).

2.

An apparatus as claimed in claim 1, c h a r a c t e r i z e d in that said channels (3) groupwise (3n) are confined in flat strips (34), cut out of plastic or metal well sheet material; that said strips (34) liquid tight penetrate and are anchored to essentially vertical slots (22) in a sidewall (23) of said vessel (2) and that said strips are positioned along essentially vertical planes (5) transversal to said axis (21).

3.

An apparatus as claimed in claim 2 c h a r a c t e r i z e d in that said channels (3, 3n) slope upwards in direction of said part flows (m).

4.

An apparatus as claimed in claim 3 c h a r a c t e r i z e d in that it comprises means for tilting around a rotary axis (22) parallel to said axis (21) and means for fixing in any desired inclination.

5.

An apparatus as claimed in claim 2 c h a r a c t e r i z e d in that said strips (34) comprise two parallel sheets (61, 62) combined with equidistant tranversal partitions (63).