Liquid purification or separation – Processes – Making an insoluble substance or accreting suspended...
Reexamination Certificate
1999-06-29
2001-04-10
Hruskoci, Peter A. (Department: 1724)
Liquid purification or separation
Processes
Making an insoluble substance or accreting suspended...
C209S005000, C210S710000, C210S713000, C210S738000, C210S768000, C210S787000, C210S803000, C210S804000, C588S256000
Reexamination Certificate
active
06214237
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process and apparatus for treating a solid waste slurry formed from solid waste particles mixed with a liquid.
2. Description of the Prior Art
Increased environmental awareness has resulted in more stringent laws regulating the disposal of various kinds of waste. For instance, numerous laws have been enacted both at the federal and state levels (as well as in many countries throughout the world) regulating the disposal of solid waste generated by many different types of industry.
One industry in particular that has had to deal with solid waste and the disposal thereof is the electric utility and power generation industry. Large quantities of solid waste are created during the power generation process, particularly in power generation processes utilizing fossil fuels, such as coal. One of the known ways for the electric utility and power generation industry to deal with such solid waste is to employ sedimentation ponds wherein a solid waste is deposited within the sedimentation ponds and allowed to settle over an extended period of time. The solid portion is then withdrawn and relocated to a suitable disposal site. However, the more stringent laws regulating the disposal of solid waste have made it more difficult for the electric utility and power generation industry to continue employing such disposal techniques. Still, there are numerous existing sedimentation ponds, and the use of such a technique by the electric utility and power generation industry continues to serve as a temporary solution to the solid waste disposal problem that ultimately must be addressed. Of course, the problem of eventually dealing with solid waste contained in sedimentation ponds is further complicated by the solid waste's admixture with the water contained in the sedimentation pond. Prior to properly disposing of the solid waste, it is necessary to remove or separate the solid waste from the water.
There do exist techniques for the treatment or processing of a water or slurry having solid waste materials admixed therewith. For example, generally known are waste water treatment facilities, such as those used by municipalities, that employ, among other equipment, centrifuges, thickeners, and water clarifiers. However, such facilities require large capital investments and include high operating expenses.
U.S. Pat. No. 3,788,469 discloses a process for removing ash generated during a power generation process from the precipitators. This process provides for removing fuel ash from the precipitator bottoms by circulating water through the bottoms of the precipitators to carry off the ash and then employing hydrocyclone separation to produce a major overflow fraction of reduced solids content and a minor overflow fraction of increased solids content.
U.S. Pat. No. 4,571,301 discloses a method and apparatus for cleaning chemical water solutions. A slurry is subjected to a combination of screening, hydrocyclone separation, and media filter separation in order to separate the particulate materials from the slurry.
U.S. Pat. No. 4,039,425 discloses a method for preparing a coal slurry substantially depleted in mineral-rich particles. This method employs an elutriation step for removing the mineral-rich particles and is directed primarily toward obtaining a slurry with particles of a uniform size.
U.S. Pat. No. 4,909,950 discloses a process and apparatus for separating solid-liquid compositions. Separation is achieved by employing one or more hydrocyclones in combination with a ceramic filtering process.
U.S. Pat. No. 2,381,760 discloses an apparatus and method for supplying clarified liquid. This process includes screen separation and hydrocyclone separation. The process is particularly adaptable for clarification of sea water.
There remains a need for a process and apparatus for treatment of a solid waste slurry formed from solid waste particles mixed with a liquid that is effective, reliable, and economically feasible, particularly for industries not primarily involved with water/solid waste treatment, such as the electric utility and power generation industry.
SUMMARY OF THE INVENTION
The present invention has met the above-described need. The invention includes a process for treatment of a solid waste slurry formed from solid waste particles mixed with a liquid, including the step of delivering the solid waste slurry to a first solid-liquid separation means for separating a first amount of the solid waste particles from the solid waste slurry. The process further includes the step of delivering the solid waste slurry from the first solid-liquid separation means to a tank and stirring the solid waste slurry contained within the tank to maintain the solid waste particles in suspension. Next, the process provides for discharging the solid waste slurry from the tank and into a pumping means and then recirculating by the pumping means a first portion of the solid waste slurry back to the tank. The process also provides for the step of discontinuing the stirring of the solid waste slurry within the tank and allowing the solid waste particles to settle to a bottom area of the tank. Next, decanting of the liquid from the tank is performed at a level above the bottom area of the tank, followed by sampling of the liquid decanted from the tank in order to determine the amount of solid waste particles contained in the solid waste slurry on a weight percent basis.
The process may also include the step of delivering by the pumping means a second portion of the solid waste slurry to second solid-liquid separation means for separating a second amount of the solid waste particles from the solid waste slurry. Alternatively, the process may include delivering by the pumping means a second portion of the solid waste slurry for mixing with a combustion ash.
The process may also include the additional steps of decanting the liquid from the tank at additional levels above the bottom area of the tank and further sampling the liquid decanted from the additional levels of the tank in order to determine the amount of solid waste particles contained in the solid waste slurry on a weight percent basis. In addition, the process may include the step of adding a coagulant aid to the slurry to concentrate the solid waste particles.
Alternatively, the process may provide for allowing the solid waste particles to settle to a bottom area of the tank, decanting the liquid from the tank at a level above the bottom area of the tank, followed by sampling the liquid decanted from the tank to determine the amount of solid waste particles contained in the solid waste slurry on a weight percent basis prior to stirring the solid waste slurry and discharging the same from the tank into a pumping means, as described herein. This allows for the amount of solid waste particles contained in the solid waste slurry to be determined at an early stage of the process.
The invention also includes an apparatus for treating a solid waste slurry formed from solid waste particles mixed with a liquid, where the apparatus comprises first solid-liquid separation means for separating a first amount of the solid waste particles from the solid waste slurry. The apparatus further comprises a tank for receiving the solid waste slurry, where the tank is in communication with the first solid-liquid separation means. The tank includes a discharge opening adjacent to a bottom area of the tank. The apparatus also comprises means for stirring the solid waste slurry contained in the tank, means for decanting the liquid from the tank at a level above the bottom area of the tank, and means for recirculating a first portion of the solid waste slurry discharged through the discharge opening of the tank back to the tank.
The apparatus may further comprise second solid-liquid separation means for receiving a second portion of the solid waste slurry discharged through the discharge opening of the tank for separating a second amount of the solid waste particles from the solid waste slurry.
The
Kustra Raymond J.
Vozel Jacob A.
Weaver Charles J.
Zimmerman Thomas L.
Allegheny Energy Supply Company
Eckert Seamans Cherin & Mellott , LLC
Hruskoci Peter A.
Jenkins David C.
Silverman Arnold B.
LandOfFree
Process for treating solid waste slurry does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for treating solid waste slurry, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for treating solid waste slurry will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2522209