Agitating – Stirrer within stationary mixing chamber – Pump type
Reexamination Certificate
2000-02-18
2002-01-29
Cooley, Charles E. (Department: 1723)
Agitating
Stirrer within stationary mixing chamber
Pump type
C366S325100, C366S326100, C366S328200, C366S601000
Reexamination Certificate
active
06341889
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid ejection apparatus and a liquid ejection method using the liquid ejection apparatus. More particularly, the invention relates to a liquid ejection apparatus and a liquid ejection method for ejecting liquid inside a tank towards a peripheral wall of the tank and for distributing the liquid onto an inner peripheral surface of the tank peripheral wall and/or into a space above the liquid surface inside the tank.
2. Description of the Related Art
In fermentation and culturing, the fermenting liquids and culturing liquids are both very prone to foaming. Due to agitation during the process, there is a considerable amount of foaming so that operability is often impaired. In order to inhibit such foaming, and to disperse the temporarily created foam, defoaming agents such as silicone are added to both the fermenting liquids and culturing liquids. The addition of such defoaming agents however not only involves significant cost, but also poses a risk adversely affecting the fermentation and culturing processes, because these defoaming agents are in themselves foreign substances to the liquids. In addition, the defoaming agents are mixed with the product as impurities so that the quality of the product is degraded. Therefore the defoaming agent must be removed from the product and this removal of the defoaming agent takes time. Furthermore the defoaming agents added to both the fermenting liquids and culturing liquids are mixed in the waste liquid and thus impede the treatment of the waste liquid. Hence the addition of defoaming agents is an undesirable means, which should be avoided as much as possible.
Moreover, in order to disperse the foam, experiments have been made to collapse the foam with shearing forces using mechanical means involving turning a disk within the foam layer on the liquid surface, or turning a hollow cylindrical body of truncated cone shape with a lower opening of the large diameter facing the liquid surface inside the tank. However with such means, not only is a considerable amount of energy required, but also the foam is often only merely broken up finely, and is not ultimately dispersed.
Another problem is that the inner peripheral surface of the peripheral wall of the agitating tank used as both a fermenting tank and a culturing tank becomes contaminated by microorganisms or solid raw materials or products being deposited thereon. This often causes a decrease in reaction yield or a reduction in heat transfer coefficient of the agitating tank peripheral wall. In this case, it is practically impossible to wash the inner peripheral surface of the inner wall of the agitating tank in order to remove the extraneous matter from the inner peripheral surface of the agitating tank without stopping the operation in the agitating tank.
Yet another problem arises with agitating tanks which are used as crystallization tanks or the like, when apparatus such as jackets and coiled pipes, and multi-tube heating units are respectively provided on the outer peripheral surface of the peripheral wall of the agitating tank, and/or are immersed into the liquid inside the agitating tank, as apparatus for heating or cooling the liquid inside the agitating tank, so that the inner peripheral surface of the peripheral wall and/or the surface of the portion of the heating or cooling apparatus which is immersed into the liquid becomes a heat transmission surface. In this case there is often the situation where the volume of liquid inside the agitating tank decreases due for example to evaporation, so that with time, the liquid level inside the agitating tank drops, and hence the heat transfer area of the heating or cooling apparatus cannot be effectively utilized.
In order to increase and hence recover the reduced heat transfer area, there are a method wherein fresh liquid is supplied to the tank so that the liquid surface is raised; or a method wherein the remaining liquid inside the tank is circulated by means of a pump provided outside of the tank until the liquid is distributed onto the inner peripheral surface of the tank peripheral wall. The former wherein fresh liquid is supplied to the tank, has the defect that there is an abrupt change in the composition of the liquid inside the tank, requiring an abrupt change in operational conditions to counter this, and also the quality of the product changes. Moreover, the latter has the defect that it requires a pump and piping for circulating the remaining liquid, so that, after operation, residual liquid remains in the tank as well as inside the piping. Consequently, the former means cannot be practically employed. Moreover, the latter requires improvements in order to be practical. Accordingly, means which can be put into practice to solve the defect that the heat transfer area cannot be effectively used have yet to be found.
When desired, in order to evaporate the liquid inside the agitating tank, normally methods are adopted which involve immersing a heating device into the liquid, or mounting a heating device on the outer peripheral surface of the agitating tank. The liquid is heated thereby to cause evaporation from the liquid surface either while agitating or not agitating the liquid. The methods are sometimes effected under reduced pressure or under pressure. With these methods there is the defect that heat in the space above the surface of the liquid which is heated by the heating device only heats the surface of the liquid and hence cannot be effectively utilized, and that the heating of the liquid inside the tank is limited to the contact surface of the heating device and the liquid surface. Accordingly, the heat from the heating device cannot be effectively utilized. Hence, the rate of the evaporation of the liquid is slow.
The present inventors, by using only mechanical agitation, have effectively overcome all of the heretofore various defects such as; the uncertain defoaming using shearing forces, the contamination of the inner peripheral surface of the agitating tank, the reduction in heat transfer area at the inner peripheral surface of the agitating tank, the contamination and reduction of the heat transfer area of the heating or cooling apparatus provided inside the tank, and the delayed evaporation of the liquid inside the agitating tank. Moreover, the present inventors made a thorough study on apparatus and methods enabling with good efficiency and reliable defoaming, all of washing of the inner peripheral surface of the agitating tank, retention of the heat transfer area on the inner peripheral surface of the agitating tank, washing of the heat transfer surface of the heating or cooling apparatus, and promotion of evaporation of the liquid inside the agitating tanks.
SUMMARY OF THE INVENTION
It is an object of the present invention to take into consideration the above situation with conventional liquid ejection apparatus and provide an improved liquid ejection apparatus and improved liquid ejection method using the liquid ejection apparatus.
The present inventors, with these apparatus and methods, have found that, in order to distribute the liquid inside the tank over the widest possible area of the inner peripheral surface of the tank, the liquid as much as possible is ejected from the liquid-transporting body and is allowed to reach as high as possible on the inner peripheral surface of the tank. Therefore, if the inclination angle of the liquid-transporting body remains the same, the rotational speed of the agitating shaft on which the liquid-transporting body is mounted can be increased in accordance with the drop in the liquid level as the liquid depth becomes shallower. In this way, the construction can be simplified. The present invention has been achieved based on this new knowledge.
According to a first aspect of the invention there is provided a liquid ejection apparatus wherein a liquid-transporting body having a lower opening and an upper opening at respective lower and upper end portions thereof is mounted on an a
Inoue Takaya
Noda Hideo
Yamaji Hiroshi
Jagtiani & Associates
Kansai Chemical Eng. Col. Ltd.
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