Degasifier for a liquid
The present invention concerns an apparatus for removing air or gas mixed with different
kinds of liquids. Above all, the apparatus is applicable to hydraulic and circulation
lubrication systems, where the air mixed with the liquid causes various problems with
respect to the operation and durability of the apparatus. For example the pumps used in
these systems easily suffer from the cavitation phenomenon boosted by the air contained
in the liquid to be pumped.
It has been tried to remove the air bubbles for example from the circulation lubrication
systems of big machines like paper machines by leading the circulating lubricant to a
space where an underpressure is prevailing. Separation of the air bubbles from the
lubricant in the underpressurized space has been boosted by different arrangements like
by pressure variations, by guiding the lubricant in the underpressurized space to flow or
pass along different surfaces, by mixing the lubricant in the underpressurized space with
a beater, etc. With apparatus based on these operation principles a problem has been
especially the weak effect, as a result of which the apparatuses have been big in order-to
guarantee the sufficient degasing effect.
These problems have been solved by means of an apparatus in accordance with the
present invention comprising a treatment container, through which the liquid to be treated
is led. Characterizing to the invention, the container comprises a chamber being closed by
immersing in the liquid led to the container, and the apparatus comprises means for
creating underpressure in the chamber. The chamber is provided with a screen fabric
rotating along an endless loop path and extending to immerse in the liquid closing the
chamber and extending above the surface thereof.
According to a special feature of the invention, the liquid, from which the mixed gas must
be removed, is led to the container so that it passes through the screen fabric.
A principle application of the apparatus in accordance with the invention is shown in the
enclosed Figure 1.
The apparatus comprises a container 1, through which the liquid to be treated is led. The
container can be, for example, a part of a circulation lubrication system, like a circulation
lubrication system of a paper machine. These kinds of containers are already known as
parts of corresponding circulation lubrication systems, and the lubricant circulating in the
system has been treated in them to remove the air muted therewith. One treatment
arrangement is to locate inclined plates in the container, along the surface of which the
lubricant entering the container is made to flow as a thin film. The container is kept under
underpressure. Air bubbles mixed with the lubricant are released from the lubricant and
aspirated through the device providing the underpressure.
According to the basic idea of the present invention, a chamber 2 is located in the
container 1. The width of the chamber is substantially congruent with the width of the
container and it is open at its lower end, extending, however, so deep in the container 1
that it immerses below the prevailed liquid level of the container. The chamber is
separated by the liquid from the rest of the space of the container 1.
A screen fabric 4 is arranged in the chamber 2, extending over the cross section thereof,
said screen fabric 4 being arranged as a loop path over two sheaves. The lower sheave is
arranged near the bottom of the chamber 1, and the upper sheave clearly above the
prevailing liquid level of the chamber. Driving force is transmitted to the sheave or
sheaves causing a rotational movement of the screen fabric along its path, to immerse in
the liquid and to rise from it.
The screen fabric 4 can be for example a wire-cloth screen or some other suitable cloth
coherent with the liquid to be treated. When the screen fabric immerses in the liquid, the
gas bubbles in it attach to the holes of the screen, and rise together with the screen above
the liquid level. The liquid naturally tends to flow downwards, thereby thinning the liquid
membrane retaining the bubbles, and facilitating the separation of the bubbles from the surface forces. The released gas is sucked by means of a vacuum pump 3, and led away
from the apparatus, eventually through a liquid separator.
The mesh size of me screen fabric (ranging from 0,3 to 3,0 mm), rotating speed of the screen fabric and the underpressure prevailed in the chamber 2 are selected according to
respective purpose of use, said selections being effected primarily by the viscosity of the
liquid to be treated.
Claims
1. An apparatus for removing air from a liquid, said apparatus comprising a liquid
treating container (1), through which the liquid to be treated is led, characterized
in that the container includes a chamber (2) to be closed by immersing in the
liquid that is led to the container, that the apparatus comprises means (3) for
creating underpressure in the chamber and that the chamber is provided with a
screen fabric (4) rotating along an endless loop path extending to immerse in the
liquid closing the chamber and extending above the surface thereof.
2. An apparatus in accordance with Claim 1, characterized in that the liquid led to
the container (1) is guided to pass through the screen fabric.

An apparatus for
removing air from a liquid, said
apparatus comprising a liquid
treating container (1), through which
the liquid to be treated is led, said
container including a chamber (2) to
be closed by immersing the chamber
(2) in the liquid that is led to the
container. The apparatus comprises
means (3) for creating underpressure
in the chamber, and the chamber is
provided with a screen fabric (4)
rotating along an endless loop path
extending to immerse in the liquid
closing the chamber and extending
above the surface thereof.