Fluid handling – Processes
Reexamination Certificate
1999-11-05
2001-04-10
Lee, Kevin (Department: 3753)
Fluid handling
Processes
C137S565230, C137S565170, C137S255000, C137S263000
Reexamination Certificate
active
06213139
ABSTRACT:
FIELD OF INVENTION
The present invention generally relates to the field of removal and disposal of viscous waste material including hazardous waste. More particularly, it is concerned with an apparatus and method for transporting highly viscous liquid and sludge waste by a conveying system to a collection area for process or disposal. The material is conveyed by a hybrid pumping system comprising a vacuum pumping means in conjunction with a progressive cavity pump.
BACKGROUND OF INVENTION
There has been an increase in demand in recent years for the cleanup of environmentally contaminated areas such as landfills, waste holding ponds, and storage tanks. Such waste holding sites frequently contain sludge and highly viscous semi-solids that must be removed from theses areas for treatment, processing or disposal elsewhere. The sludge and other materials contained in these sites are often toxic and potentially harmful to the environment. Many of the methods developed to treat or process such waste require a controlled and consistent feed of waste material to the processing equipment in order for the processing equipment to operate at efficient levels.
Systems incorporating vacuum equipment and piping have been used to transport viscous sludge and semi-solid waste material. However, such vacuum systems alone have been found to be insufficient for the effective transport of highly viscous material due to the inherent characteristics of such materials. Highly viscous materials resist flowing due to friction and consequently often clog intake and discharge lines of such vacuum systems. This results in delivery of the waste material in slugs, rather than in a continuous flow, and thus provides an inconsistent delivery of the waste to the intended delivery site.
Combining a vacuum system with a mechanical pump to assist in the transport of viscous sludge has been proposed. One such device is that described in U.S. Pat. No. 4,924,898 to William R. Evenson. This device proposed using a centrifugal pump attached to the sludge receiving end on the intake line of a vacuum hose. The centrifugal pump was intended to serve as a booster for the vacuum pump by pushing sludge into and through the intake line. A disadvantage associated with the system is that the centrifugal pump must be fixed at the end on the vacuum intake line so that it can be placed directly into the sludge to be transported. Locating the centrifugal pump on the intake line increases its weight and makes the intact end of the intake line heavy and difficult to manipulate.
Another method for combining a mechanical pump and a vacuum pump is that proposed in U.S. Pat. No. 4,659,293 to William R. Evenson. There a blower powered vacuum system is utilized to draw sludge to a separator so that it may fall into a sealed hopper. A horizontal axis dual cylinder alternating piston pump is securely attached to the sealed hopper. Within the sealed hopper is an oscillating elbow conduit. The elbow conduit oscillates in alternating registration and communication with the two cylinders of the piston pump to transport the collected sludge from the sealed hopper to a storage location through a discharge line in communication with the elbow conduit of the hopper. A disadvantage of this design is that highly viscous sludge or semi-solids can impede or stop the oscillation of the conduit and shut down the movement of the sludge to the piston pump. Another disadvantage is that some highly viscous materials will not flow sufficiently to the piston to allow for efficient punping. Still another disadvantage is highly viscous semi-solids can cause great wear and tear on the oscillating conduit, the piston pump and the pump motor. This wear and tear will ultimately lead to downtime on the system and additional expense due to the need for increased repair, maintenance and replacement of the system components. Another disadvantage is that the flow of material in a system utilizing a piston pump will be highly pulsed. Finally, the oscillating conduit described in U.S. Pat. No. 4,659,293 is essentially a large valve. Such a valve is disadvantageous because the materials being transported can interfere with the seating of the valve. This interference can cause damage to the system or a shut down of material flow through the system due to blockage of the valve seating by an interfering object.
Still another disadvantage of the traditional vacuum systems is that these systems cannot be utilized on their own for the delivery of material to feed process equipment unless the process equipment is also under a vacuum and the flow of air goes through the equipment. Most process equipment is not designed to hold a vacuum. In addition, storage tanks filled by traditional vacuum systems must be designed for vacuum service. This increases the cost of the storage tanks and eliminates open-air access to the tanks as they are being filled.
Consequently, a need exist for improvements in sludge transporting equipment that will provide a continuous flow of highly viscous sludge and semi-solid material for further processing or disposal at atmospheric pressure with increased efficiency and with a decrease in the maintenance and repair cost of the transporting equipment.
SUMMARY OF INVENTION
The present invention provides a sludge transporting system and apparatus designed to satisfy the aforementioned needs. It is contemplated for use in vacuuming and transporting highly viscous sludge and semi-solids, or slurries having a high solids content, with a continuous flow of the material. This system has a dual conveying means incorporating a vacuum system with a progressive cavity pump. Primary conveyance is achieved by the vacuum system that pulls the material to be conveyed to a transfer chamber that is maintained at a low-pressure environment. The transported material then falls by gravity into the inlet of a progressive cavity pump that is also maintained at a low-pressure environment. The progressive cavity pump provides secondary conveyance to a collection area that is typically at atmospheric pressure.
The system incorporates a vacuum source, a means for creating a vacuum in the vacuum chamber, a plurality of chamber inlet hoses, a progressive cavity pump mounted to the vacuum chamber and a discharge line from the progressive cavity pump. Ideally, the system components may be mounted on skids for ease in transporting the the system to a work site. The progressive cavity pump requires less maintenance that other type pumps such as a piston pump.
The system allows the collection of sludge and semi-solids from a single location or source or from multiple locations or sources with a discharge that is constant and controllable. Slurries having a high solids content are readily transportable as are highly viscous sludges and semi-solids. The system provides for the continuous delivery of slurries or sludges to a container or disposal area maintained in an open atmosphere environment. The system provides for discharge from the vacuum chamber, via the progressive cavity pump, while the vacuum chamber is still in a vacuum state. Water or other additives may be readily added to the vacuum chamber for the treatment of the collected material when the system is in operation. The entire system is readily transportable with a minimum of set up time required.
The vacuum chamber and its inlets are configured to allow non-flowable material to be delivered or dumped into the inlet of the progressive cavity pump without bridging and without becoming lodged in the vacuum chamber. The walls of the vacuum chamber are configured to conform to the pump inlet and sloped to prevent adherence or sticking of highly viscous sludges.
The screw path of the progressive cavity pump used in the system aids in the mixing of additives with the material being conveyed. Such a pump may also be reversed to pull material back into the chamber and clear the discharge line. This is useful when changing the discharge line location.
The system affords many uses in industrial sites. These include the conveyance of semi-s
Lee Kevin
Soloco, L.L.C.
Stagg William W.
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