Power plants – Combustion products used as motive fluid
Reexamination Certificate
1999-05-17
2001-08-14
Thorpe, Timothy S. (Department: 3746)
Power plants
Combustion products used as motive fluid
Reexamination Certificate
active
06272839
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to hydraulic air compressors, systems employing hydraulic air compressors and systems and methods for aerobic, biological treatment of waste water.
BACKGROUND
Compression of air using an hydraulic air compressor (HAC) is generally known. In Richardson, U.S. Pat. No. 4,797,563, the disclosure of which is hereby incorporated by reference, discloses a HAC to compress air which is provided to the burners of a turbine to generate electrical power. According to this reference, air is drawn into the down shaft through open pipes into the flowing water to be compressed. The compressed air and water emerge from the shaft at a tunnel where the compressed air liberates from the water and is conducted to a turbine. Richardson does not show any means to forcible entrain air or for efficiently entraining air into the flowing liquid for compression thereof.
In Angle, U.S. Pat. No. 5,099,648, a HAC is also disclosed which, similarly to Richardson '563 does not provide any means to forcibly entrain air into the liquid for compression thereof.
Accordingly, a drawback of the type of systems discussed above is that the volume of air for compression relies upon a configuration to naturally draw air into the liquid flow as the volume of air to be compressed. Means are not disclosed to increase the volume of air to be compressed to provide for more versatility and efficiency in a HAC or system incorporated the same. Still further, these systems provide no convenient means to control either or both of the flow of liquid through the HAC or the volume of compressed air produced. It would be desirable to provide means to control the flow of liquid and the volume of air produced by the HAC.
Still further, these prior HACs are subject to slug flow in their down shafts which can result in blowback of compressed air up the down shaft.
The systems described above also provide no means to aerobically treat effluence such as waste water, sewage effluent or the like.
It would be desirable to provide a more versatile and efficient HAC to compress air for any purpose such as to provide combustion air to a burner or a fuel-fired turbine for the production of steam, work or electricity. It would also be desirable to provide a system incorporating a HAC to provide compressed air according to the foregoing which also uses and aerobically treats waste water such as sewage effluent or the like.
Regarding treatment of waste, it has been known in the prior art to treat effluent such as domestic and industrial waste through aeration to reduce the biologic oxygen demand (BOD) imposed by biodegradation of the waste on the environment. For treatment of sewage it has been known to provide large surface area sludge ponds, aerators, sprinklers and bubblers to supply the BOD for biodegradation of the waste. It has also been known to provide vertical shaft bioreactors as described in Pollock, U.S. Pat. No. 5,660,724. In vertical shaft bioreactors, the effluent is supplied at the top of a vertical shaft to flow downwardly to the bottom. At the bottom of the vertical shaft, air may be injected. From the bottom a riser returns the effluent for recirculation. Air is injected at the bottom of the riser to not only aerate the effluent but to create an air lift for circulation of the effluent. These systems aerobically treat the effluent but do not provide any byproduct such as compressed air which can be utilized to produce energy or work. Further injection of air at the bottom of the vertical shaft cannot provide for any significant compression thereof.
It would be highly desirable if a system could be devised which could not only aerobically treat and agitate a waste water effluent but which could also produce a byproduct of compressed air which can be utilized to, for example, supply combustion air to a burner or a turbine.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved hydraulic air compressor (HAC) which reduces if not eliminates the likelihood of down shaft blowback, which is adapted to produce larger quantities of compressed air and in which the flow of liquid can be controlled.
It is a further object to provide a system and method for treating water and waste water using a high-rate activated sludge process incorporating a HAC for acting as a bioreactor and for the production of compressed air.
There is, therefore, provided according to the present invention a more versatile and efficient HAC and method for compression of large volumes of air by which air and water flow volumes can be adjusted and a system and method incorporating such a HAC which also is adapted to aerobically treat waste water such as sewage effluent and the like.
Toward this end, a HAC is set forth for compressing air using a liquid head which includes a substantially vertical down shaft having an upper end, a lower end and tapered along its length to accelerate flow of liquid from the upper end to the lower end. Means are provided for introducing a liquid head at the upper end of the down shaft such as by from a free-flowing source of water (river, dam or pump), the liquid flowing downward and accelerating through the shaft to a lower end to compress air carried with the liquid. A separation chamber communicates with the down shaft lower end, the compressed air separating from the liquid in the separation chamber. Means such as a blower are provided for injecting air into the liquid flowing in the down shaft for compression thereof. Preferably a blower or compressor is used to introduce air proximate the down shaft upper end for compression thereof. Still more preferably, a restriction defined as a throat is provided proximate the down shaft upper end at which the air is injected into the flowing liquid for capture thereof.
The compressed air at the separation chamber is delivered to, for example, the compression air inlet of a fuel-fired turbine, burner or for any other purpose. The liquid in the separation chamber is directed upwardly through a return shaft for discharge from the HAC. Preferably a control valve is provided in the return riser for controlling the flow of the liquid returning through the return riser to, in turn, control the volume of air contained within the flowing water and ultimately the separation chamber. By virtue of the control means provided by a control valve or the like, the air and water flow can be controlled to provide versatility to the system.
The HAC, according to the present invention, may be incorporated into any system using any liquid. According to a further embodiment of the present invention, however, the HAC is incorporated into a system and method which not only compresses air for any suitable purpose but also acts to aerobically treat water such as waste water including sewage effluent. According to this feature of the present invention, a source of liquid effluent is provided which may be water and a sludge liquor from a waste water treatment facility. The waste water effluent becomes the HAC influent delivered to the upper end of the down shaft of the HAC. By forcibly introducing air into the liquid, according to the HAC of the present invention, the waste water influent is aerobically treated and agitated as it flows through the HAC for compression of the air providing for bioreaction between the oxygen of the supplied air and oxygen requiring microbes in the effluent. The treated water is returned from the separation chamber to a waste water holding pond or the like. By introducing greater amounts of air than could naturally be captured by the liquid of HACs which use the nature capture of air, the additional introduction of air aerobically treats the biological waste of the effluent and increases the volume of air compressed by the HAC. Re-circulation of the effluent through the HAC continues to aerobically treat the effluent.
As can be appreciated, a HAC according to the present invention incorporated into a waste water treatment system not only provides for the efficient and versatile compression of air but a
Anderson Philip J.
Anderson & Morishita, LLC
Rodriguez William
Thorpe Timothy S.
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