Aerator with float chamber and turnable inlet

Details Aerator with float chamber and turnable inlet Aerator with float chamber and turnable inlet

1999-01-29

2001-02-20

Walker, W. L. (Department: 1723)

Liquid purification or separation

Constituent mixture variation responsive

C210S220000, C210S121000, C261S037000, C261S076000

Reexamination Certificate

active

06190544

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention concerns aerators.
2. Description of the Prior Art
Fishing lakes are prone to formation of algae therein. The algae removes oxygen from the water, so that the fish become lazy and do not eat. Chemical treatment is possible but this tends to sink the algae to the bottom of the lake, where oxygen is still absorbed eventually causing the fish to die. One answer to the problem of algae is to ensure that the lake is aerated although that may present practical problems. Thus, there is a need for a simple and effective aerator for use in fishing lakes.
Aerators may have applications in other situatons. In particular, aeration of effluent or sewage is advantageous in enhancing biodegradation thereof. Paddles are presently used for aeration of sewage but are heavy on energy consumption. Additionally, the gear boxes of such paddles frequently breakdown and are expensive to repair.
An object of this invention is to provide an aerator for use in a liquid medium, including solids in suspension.
SUMMARY OF THE INVENTION
According to this invention there is provided an aerator for use in a liquid medium comprising a liquid inlet to a venturi chamber, pump means for drawing liquid through the venturi chamber, an air inlet connected to the venturi chamber, whereby air is drawn into and aerates the liquid drawn through the venturi chamber, an outlet from the venturi chamber for discharging the aerated liquid into the liquid medium and float means for supporting the aerator in the liquid medium.
The liquid inlet and outlet are preferably of substantially the same cross- sectional area.
The air inlet is preferably a pipe or tube on which the float means may be mounted. For some, typically small scale, aerators it may be convenient to have a float chamber slidably mounted on the inlet tube or pipe.
Means may be provided on the inlet or the float chamber to restrict the depth of the aerator in the liquid medium relative to the float chamber.
For other, especially larger scale, aerators it may be more desirable to have the inlet pipe or tube fixed relative to the float means. In such a situation it may be convenient to have the float means clamped to the inlet tube or pipe. The float means may comprise one or more preferably two, hulls coupled together.
The liquid inlet and the liquid outlet are preferably on parallel axes and the liquid inlet is preferably below the outlet. The inlet is preferably turnable between two positions, one where the inlet takes in liquid in the opposite direction to the outlet flow. When suction and discharge of liquid are In opposite directions, the aerator is generally stabilised. In other words pull on securing means, such as anchor chain, be minimised.
Alternatively in a second position the inlet is arranged so that liquid is drawn into and discharged from the aerator in the same direction. With the inlet in the second position liquid movement through the aerator may be maximised.
The pump is preferably in a casing, so that liquid preferably flows into the pump only via the inlet. The pump means is preferably electrically operated. The power output of the pump will be chosen according to the intended use of the aerator. Typically for aerating a fishing lake, a 0.75 kw pump may be suitable. For aeration of, for example, sewage a larger capacity pump, such as a 6 kw pump, may be necessary. However, even larger capacity pumps, for example up to 60 kw may be used for heavier applications.
Control means is preferably provided for the pump means, preferably so that the pump can be controlled remotely. By controlling the speed of the pump the amount of oxygen being introduced into the liquid can be regulated. Preferably the control means is responsive to sensors for determining the biological oxygen demand (BOD) and the chemical oxygen demand (COD) of the liquid medium.
The venturi chamber preferably comprises a flow restriction tube from the liquid medium inlet. The flow restriction tube may have converging sides along its entire length or may terminate with a parallel sided section. Typically a flow restriction tube comprises a hollow frusto-conical section. The air inlet preferably connects with the venturi chamber partially behind the flow restriction tube outlet end.
The aerator of the invention operates by pumping liquid through the venturi chamber, where flow restriction causes a pressure reduction that draws air into the chamber through the air inlet where it mixes with and aerates the liquid.
Another use for aerators of the invention is in the degassing and re-oxygenation of liquids. Again this involves directing output upwardly so that gases entrained in the liquid output can escape to atmosphere from the liquid spray produced.
To facilitate degassing using an aerator of the invention, it is preferred that the aerator of the invention be tiltable relative to the float means whereby the outlet from the aerator may be upwardly directed. Preferably the aerator is connected to the float means by a mechanism allowing the aerator to be tilted to a selectable angle.
It is believed that aerators of the invention can provide considerable energy savings compared to currently used aeration systems. For example, aeration of sewage using paddles typically requires 40 kw motors to drive the paddles. However, comparable aeration of sewage may be achieved using three aerators of the invention each using only a 6 kw motor.
This invention will now be further described, by way of example only, with reference to the accompanying drawings:


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patent: 4514343 (1985-04-01), Cramer et al.
patent: 4710325 (1987-12-01), Cramer et al.
patent: 4997557 (1991-03-01), Andersen
patent: 5344563 (1994-09-01), Noyes
patent: 5514267 (1996-05-01), Machiya et al.
patent: 2447337 (1976-04-01), None
patent: 3434623 (1986-04-01), None
patent: 2230204 (1990-10-01), None
patent: 9901386 (1999-01-01), None

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