Liquid purification or separation – With gas-liquid surface contact means
Reexamination Certificate
1999-12-08
2001-05-15
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
With gas-liquid surface contact means
C210S097000, C210S456000, C210S541000, C239S001000, C239S071000, C239S254000, C239S256000
Reexamination Certificate
active
06231756
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
Not applicable.
BACKGROUND OF THE INVENTION
The present invention relates to a speed control system for a rotary distributor having multiple distribution arms that distribute waste water over a porous media of a trickling filter by discharging it through ports or nozzles spaced along the length of each distribution arm. The rotary distributor of the present invention uses hydraulic forces to control the rotational speed of the distribution arms.
Currently, when speed control is used, motor driven rotary distributors are commonly used to distribute waste water over porous media in trickling filter applications. A motor driven rotary distributor has a motor driven gear reducer that is mounted on the center column of the rotary distributor or on the end of one of the distribution arms. The motor has an adjustable speed controller so that the rotary distribution arms can be rotated at various desired speeds. When using a motor driven gear reducer, the hydraulic thrust normally associated with rotary distributors is nulled out by balancing the forward and reverse discharge from the arms so as to have a configuration that yields a near net zero thrust.
One disadvantage with motor driven rotary distributors is that they require significant amounts of energy from an outside source. Another disadvantage with motor driven rotary distributors is that larger units with higher flow rates become difficult to start and stop without damaging equipment.
Because the distribution arms are filled with water and may be up to 100 feet long, their mass creates a high moment of inertia that can lead to operating problems. When the arms are initially rotated from a rest condition, the strain placed on the gear reducer is significant, particularly if the acceleration is excessive. Therefore, the acceleration must be carefully controlled to prevent premature failure of the gear reduction mechanism. Conversely, if deceleration is not carefully controlled, the gear reducer can fail prematurely due to the friction, viscous drag and inertia of the motor and drive components. An over torque condition can destroy various parts of the system if an arm is caught on an obstruction. All of these potential problems can create situations where the treatment equipment is out of commission for an extended period, which may occur at an inappropriate time.
Prior to the addition of motor drives to rotary distributors, the distribution arms were designed to be rotatively driven by the hydraulic thrust produced by the discharging water. However, controlling the speed ofthe arms was difficult because it involved manually repositioning spreaders and caps along each arm so as to change the amount of forward and reverse discharge exiting the arms. Still another disadvantage with these manually controlled rotary distributors is that slow operating speeds, which sometimes are desirable, are difficult to achieve reliably because wind forces may work against the speed of the arms. In addition, a period of lower flows can cause the arms to stop moving when they are operating at low operating speeds, which is detrimental to the trickling filter performance.
In order to overcome these disadvantages, an improved speed control system for a rotary distributor is needed. This speed control should be able to use hydraulic forces to control the rotational speed of the distribution arms of the rotary distributor, thereby taking advantage of the hydraulic energy already present and eliminating the need for additional power.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide hydraulic speed control for a rotary distribution arm arranged so that the system does not experience significant adverse effects from power failures, a change in influent feed flow, or a change in arm speed.
It is a further object of the present invention to provide a speed control system that is able to slow the distribution arm rotational speed below conventional speeds.
According to the present invention, the foregoing and other objects are achieved by a rotary distributor speed control system that uses hydraulic forces. This rotary distributor includes distribution arms each having a forward side and a reverse side wherein each of said forward sides and each of said reverse sides define at least one orifice, slide gates coupled with the arms wherein the gates can be moved so as to selectively cover the orifices, and slide gate valve operators coupled with each arm for moving the slide gates. Another aspect of the present invention is a method of controlling the speed of a rotary distributor by using hydraulic forces. Still another embodiment of the present invention is to provide an entire waste water treatment plant that uses the hydraulically controlled rotary distributor described above.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
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Drodge Joseph W.
Shook Hardy & Bacon LLP
Wes-Tech, Inc.
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