Gas separation: apparatus – Apparatus for selective diffusion of gases – Immobilized liquid membrane
Reexamination Certificate
2002-07-08
2004-10-05
Hopkins, Robert A. (Department: 1724)
Gas separation: apparatus
Apparatus for selective diffusion of gases
Immobilized liquid membrane
C095S044000, C261S152000
Reexamination Certificate
active
06800118
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gas/liquid separation element, a gas/liquid separator and a gas/liquid separation unit for use in a wide range of gas/liquid separation applications, and in particular to a humidifying element, humidifier and humidifier unit adapted for use in a wide range of air conditioning applications requiring humidification, and especially in humidified air conditioning applications for office buildings, factory environments, households and vehicles.
2. Description of Related Art
To date, gas/liquid separators employing gas/liquid separation membranes to separate gases from liquids have been employed in various fields such as humidification, dehumidification, degassing, gas dissolving and so on (gas dissolving, i.e. dissolving a gas into a liquid, is included in the definition of gas/liquid separation herein). In particular, membrane type humidifiers have enjoyed a sudden surge in popularity in recent years due to their more efficient and cleaner humidification relative to the evaporator plate type humidifiers used to date.
Humidifiers of this type, namely, moisture permeable membrane type humidifiers employing porous sheeting hydrophilic polymer material (herein below also termed “first type humidifiers”), have been proposed (Unexamined Patent Applications H05-286039, H07-4701). Humidifiers of this kind employ a tubular membrane element formed from sheet material, which itself is a laminate of reinforcing material with a hydrophobic polymer membrane that blocks passage of water, but allows water vapor to pass. A liquid spacer is arranged within the tubular membrane element to ensure an internal flow channel for the humidification water, which is coiled into a spiral configuration together with a corrugated spacer for ensuring a gas flow channel, and accommodated within a mounting frame. In some instances an air bleed line is provided to enhance humidification efficiency.
To operate a first type humidifier, humidifying water is supplied into the tubular membrane element from a water inlet, and air is introduced into an opening in the mounting frame. The water inside the tubular membrane element is released in the form of water vapor through the hydrophilic polymer membrane, to effect humidification.
Humidifiers of the first type, however, have a number of problems, such as the following.
(1) A pinhole or liquid flow channel blockage, even at a single location in the tubular membrane, may result in the entire humidifier becoming nonfunctional, or in reduced humidifying performance.
(2) The tubular membrane may expand due to the pressure of the humidification water, thereby constricting the gas flow passage, resulting in increased pressure loss in the gas system and diminished gas flow. Expansion of the tubular membrane may also result in increased contact area between the waterproof/moisture permeable membrane and the corrugated spacer defining the gas flow channel, so that humidifying performance is depressed.
(3) The corrugated spacer for defining the gas flow channel has a large number of peaks spaced at relatively small intervals so as to ensure gas flow, as a result of which there is a large contact area between the corrugated spacer and the waterproof/moisture permeable membrane, and significant loss of humidifying performance.
(4) In order to achieve the desired humidifying performance, it is necessary to coil a very long tubular membrane (as long as 10 m or more) together with a corrugated spacer to produce the humidifier, resulting in a complex manufacturing process and high costs.
(5) It is necessary for tubular membrane connections to the water feed line or air bleed line to be liquid-tight; the difficulty of fabrication of these components results in significant loss, and consequently increased cost.
A humidifier plate type has been proposed by way of another type of humidifier (herein below also termed “second type humidifier”) (Unexamined Patent Application H08-128682). This kind of humidifier has a structure wherein a stack of a plurality of independent humidifier plates (these consist of porous films of hydrophobic polymer) of thin foliate configuration is accommodated within a mounting frame, with each humidifier plate having waterproof/moisture permeable membrane stacked on the two principal faces of a frame having an opening therein, and with the humidifier plate supplied with water from an end thereof to a humidifier portion situated between the waterproof/moisture permeable membranes in the frame. Accordingly, each frame is thicker in the portion thereof defining the water feed portion than in the portion thereof defining the humidifier portion; the humidifier plates are stacked together with the water feed portions thereof juxtaposed, so that gaps are produced between humidifier plates due to the thickness difference between the water feed portion and humidifier portion of the frame, to ensure that gaps, serving as gas flow channels, are present between the humidifier plates.
To operate a second type of humidifier of this kind, humidifying water is supplied from a water inlet, and air is introduced into an air inlet opening in the mounting frame. The water supplied to the humidifier plates is released in the form of water vapor through the hydrophobic polymer membrane, to effect humidification.
However, since the design of the humidifier of the second type employs a stack of a plurality of humidifier plates of thin foliar configuration, while problems (1) and (4) pertaining to the humidifier of the first type described above are solved, other problems, such as the following, remain.
(1) Where no corrugated spacer is used in the gas flow channel, the waterproof/moisture permeable membranes can expand due to water pressure, thereby constricting the gas flow passage, resulting in increased pressure loss in the gas system and diminished air flow. Deformation of the waterproof/moisture permeable membranes can be reduced to some extent by providing the frame with ribs (the back face of the waterproof/moisture permeable membrane being stuck to the ribs), but where water pressure is high the waterproof/moisture permeable membrane will tend to come away from the rib, possibly resulting in rupture of the waterproof/moisture permeable membrane and water leakage.
(2) Where a corrugated spacer is used in the gas flow channel, the corrugated spacer that defines the gas flow channel will have a large number of peaks spaced at relatively small intervals so as to ensure gas flow, as a result of which will be a large contact area between the corrugated spacer and the waterproof/moisture permeable membrane, and significant loss of humidifying performance. High water pressure will result in larger contact area between the waterproof/moisture permeable membrane and the corrugated spacer, depressing humidifying performance.
(3) Fabricating a humidifier composed of a stack of a plurality of humidifier plates involves first bonding or fusing waterproof/moisture permeable membranes to a frame to produce the humidifier plate, and then stacking and bonding the desired number of humidifier plates one at time, resulting in a production process that is complicated, involves numerous steps, and is costly.
(4) Since the water feed portion of the humidifier plate has an open mouth structure, individual humidifier plates cannot be inspected for pressure-induced water leaks; rather the assembled humidifier must be inspected for pressure-induced water leaks, so leakage in even a single humidifier plate renders the entire humidifier unusable.
As yet another type of humidifier, there has been proposed one employing a humidifier sheet of unified triple-layer construction (herein below also termed “third type humidifier”) (Unexamined Patent Application 2000-274754). This kind of humidifier employs a humidifier sheet of unified triple-layer construction, comprising waterproof/moisture vapor permeable membranes that block passage of water but allow passage of water vapor, arranged on both sides of a humidifying water re
Kusunose Ryo
Nishi Kojiro
Yokota Takushi
Ellis Richard W.
Gore Enterprise Holdings Inc.
Hopkins Robert A.
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