Liquid purification or separation – Casing divided by membrane into sections having inlet – Cylindrical membrane
Patent
1993-10-29
1995-03-07
Dawson, Robert A.
Liquid purification or separation
Casing divided by membrane into sections having inlet
Cylindrical membrane
21032188, 422 45, 422 48, 96 8, 96 10, B01D 6300
Patent
active
053955250
DESCRIPTION:
BRIEF SUMMARY
FIELD OF TECHNOLOGY
The present invention relates to a hollow fiber membrane-type substance exchanger apparatus such as an artificial lung, of a construction wherein a fluid flow generating means for generating a flow of liquid to be supplied to hollow fiber membranes is integrated radially inwardly of a substance exchanger unit comprising the hollow fiber membranes arranged in a tubular or annular column; said apparatus can achieve high efficiency in exchanging substances and suitably structured to be made compact in size.
BACKGROUND ART
The hollow fiber membranes have an advantage in that a substance exchange such as a gas exchange through a membrane is achieved in a high efficiency, and are therefore utilized in various fields for exchanging substances.
By way of example, an artificial lung utilizing the hollow fiber membranes is so designed that, with the use of microporous hollow fiber membranes made of hydrophobic polymer such as polyolefin or gas-permeable homogeneous hollow fiber membranes made of, for example, silicone, gas exchange takes place between oxygen-containing gas and blood through membranes, and is available in two types; an intracapillary-flow type in which the gas flows exteriorly of the hollow fiber membranes while the blood flows through hollow part of the hollow fiber membranes and an extracapillary-flow type in which, in a sense opposite to the intracapillary-flow type, the gas flows through hollow part of the hollow fiber membranes while the blood flows exteriorly of the hollow fiber membranes.
In the intracapillary-flow type, although no channeling (biased flow) of the blood flow occur substantially if the blood is supplied so as to be uniformly distributed to the multiplicity of the hollow fiber membranes, the blood flowing through the hollow part of the hollow fiber membranes represents a laminar flow and, therefore, the hollow fiber membranes must have a reduced inner diameter in order to increase the oxygenating ability (oxygen transfer rate per unitary membrane surface area). In view of this, the hollow fiber membranes having an inner diameter of about 150 to 300 .mu.m have been developed for use in an artificial lung. However, even though the diameter is so reduced, the oxygenating ability does not increase remarkably so long as the blood flows in a laminar fashion. Moreover, the smaller the inner diameter of the hollow fiber membranes, the more does the clogging (choking of the inside of the hollow fiber membranes due to blood clotting) occurs frequently, posing an obstruction to the practical use.
On the other hand, generally in the artificial lung, several tons of thousands of hollow fiber membranes are bundled and, because of this, special care is required to supply the gas so as to be distributed sufficiently and uniformly over the individual outer walls of the hollow fiber membranes. In the event that the gas is not sufficiently distributed, the carbon dioxide removing ability (CO.sub.2 transfer rate per unitary membrane surface area) is lowered.
On the other hand, the extracapillary-flow type is superior to the intracapillary-flow type in that the gas can be distributed satisfactorily accompanied by a minimized loss of pressure of the liquid and, also, it can be easily structured to cause a turbulence in the flow of the blood.
In the extracapillary-flow type, the internal structure of the blood passage has close relations to a shortage of oxygenation due to blood channeling and an occurrence of blood clotting due to stagnation of blood flow, and therefore, proper selection of the structure of the blood passage is extremely important in avoiding these problems.
The extracapillary-flow type artificial lung module comprising the hollow fiber membranes and having a structure to prevent an occurrence of the channeling in the blood flow hither to known includes a module in which baffle plates are disposed in the blood passage.
By way of example, as shown in FIGS. 6A and 6B, the Japanese Laid-open Patent Publication No. 60-193469 discloses an extracapillary-flow type a
REFERENCES:
patent: 3934982 (1976-01-01), Arp
patent: 4312757 (1982-01-01), Brumfield
patent: 5043140 (1991-08-01), Combs
patent: 5263924 (1993-11-01), Mathewson
patent: 5266265 (1993-11-01), Raible
patent: 5270005 (1993-12-01), Raible
Akagi Haruhiko
Aoyagi Takanobu
Kamo Jun
Taenaka Yoshiyuki
Takano Hisateru
Dawson Robert A.
Fortuna Ana M.
Takano Hisateru
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