Motors: expansible chamber type – Hydro-pneumatic
Reexamination Certificate
2000-06-22
2002-01-08
Denion, Thomas (Department: 3745)
Motors: expansible chamber type
Hydro-pneumatic
C091S354000, C092S137000
Reexamination Certificate
active
06336389
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to compressed gas in situations where, in utilizing the potential energy of the compressed gas through pneumatic devices, it is preferable to recover the gas exhausted from the pneumatic device, including, but not limited to, natural gas production facilities and wells. The present invention also relates to the injection of liquids into compressed gas.
BACKGROUND OF THE INVENTION
In many situations it is necessary to utilize the potential energy of a compressed gas to power pneumatic devices so as to drive equipment. Pneumatic devices are devices which operate by converting the potential mechanical energy of a compressed gas into motion. Pneumatic devices utilize the tendency of gases to flow from an area of higher pressure to an area of lower pressure and therefore they require a pressure differential in order to operate. Typically, this pressure differential is between the exterior of the pneumatic device, typically the atmosphere, and a supply of gas at a higher than atmospheric pressure, which is fed into the interior of some of the components of the pneumatic device.
In general terms, the components of a pneumatic device may be divided into pressure differential components and non-pressure differential components. The pressure differential components are those components of a pneumatic device which face a pressure differential between their interiors and exteriors during normal operation. Examples of pressure differential components include: pipes and other forms of gas conduits; pneumatic cylinders; and valves. Non-pressure differential components are those components of a pneumatic device which do not face a pressure differential between their interiors and exteriors during normal operation. Examples of non-pressure differential components include: power output means such as shafts; and switch linkages.
In natural gas production facilities, it is often necessary to periodically or continually inject liquids into a high pressure gas pipeline. An example is methanol, which may be injected to prevent any water present in the natural gas from freezing. Such liquids are injected by means of pumps which overcome the pressure of the compressed gas to force the liquid into the pipeline. These injection pumps are often powered by pneumatic devices, particularly in remote locations. In some situations, the compressed gas flowing in the pipeline is used to drive the pump, but typically, only after it has been regulated down to a pressure suitable for the pneumatic device, often around 10 pounds per square inch. The exhaust gas from the pneumatic device comes out of the device at a lower pressure than the gas in the pipeline, so it can't be reinjected into the pipeline unless it is first compressed. Therefore the exhaust gas is usually vented to atmosphere. In some situations a gas such as propane is brought to the site, stored in a pressure vessel, and used to drive a pneumatic device. This gas is also vented to atmosphere from the pneumatic device.
This venting of the exhaust gas to atmosphere is a problem because it is a waste of valuable gas and because it raises environmental concerns, particularly in the case of sour gas. A means of utilizing the potential energy of the compressed gas, and of injecting liquids into a high pressure gas pipeline, which does not require venting of the gas is required.
BRIEF SUMMARY OF THE INVENTION
In accordance with the invention, it is found in using pneumatic devices that pressurizing the work environment of a variety of pneumatic devices and containers to the same pressure as the compressed gas with which the devices and containers are associated produces many benefits, including, but not limited to, the emission-free operation of pneumatic devices and the efficient injection of liquids into compressed gases.
In accordance with the invention, if a pressure differential exists within a compressed gas system, in a natural gas pipeline for example, and the working environment of the pneumatic device is pressurized by means of direct contact with that compressed gas in the compressed gas system which is at the lower pressure, and the pneumatic device is driven by compressed gas from that portion of the compressed gas system which is at the higher pressure, then the pneumatic device can operate so as to exhaust gas back into the compressed gas system; and the pressure differential components of the pneumatic device will face a maximum pressure differential between their interiors and exteriors equal to the pressure differential within the compressed gas system, rather than the pressure differential between the compressed gas system and the atmosphere.
Natural gas often comes out of the well at a high pressure, for example, 1,000 pounds per square inch. The natural gas often undergoes some processing immediately downstream of the well, for example, water is often removed by running the gas through a dehydrator. A usual side effect of this processing is that it lowers the pressure of the gas downstream of the processing equipment relative to the pressure upstream of the processing equipment, typically by constricting the flow of the gas. Therefore, there is usually a pressure differential between the gas upstream of the processing equipment and the gas downstream of the processing equipment. In situations where there is no processing equipment, a similar pressure differential can be created merely by constricting the flow of the gas.
One embodiment of this invention receives gas from the upstream, higher pressure side of the processing equipment, uses it to power a pneumatic device and then exhausts the gas at a pressure high enough so that the gas can be reinjected at the downstream, lower pressure side of the processing equipment.
A feature of this invention is a pressure vessel strong enough to withstand the highest pressure found in the compressed gas system to which the pressure vessel is attached. The pressure vessel contains some or all of the pressure differential components of a pneumatic device, whereby, although the device operates at a high ambient pressure, such as 1,000 pounds per square inch, the differential pressure faced by the bodies and seals of the various components (not including those seals between the exterior and interior of the pressure vessel) is low, such as 25 to 30 pounds per square inch.
The pneumatic drive unit or pneumatic device can be any device that operates by converting the potential mechanical energy of a compressed gas into motion.
In one embodiment of this invention, the pressure vessel contains a valve means connected by suitable conduit to the relatively higher pressure compressed gas in the pipeline; to a pneumatic cylinder; and to the interior of the pressure vessel, such that the valve means can be actuated to restrict the flow of gas between two of the three conduits connected to the valve means, being between the conduit to the relatively higher pressure compressed gas in the pipeline and the conduit to the pneumatic cylinder; and between the conduit to the pneumatic cylinder and the conduit to the interior of the pressure vessel. The interior of the pressure vessel is connected by suitable conduit to the relatively lower pressure compressed gas in the pipeline, wherein the pressure in the pressure vessel is essentially the same as the relatively lower pressure compressed gas in the pipeline. The pneumatic cylinder contains a piston. The piston in the pneumatic cylinder is connected to a spring which acts to move the piston so as to evacuate the compressed gas from the cylinder. The piston in the pneumatic cylinder is connected to a means for actuating the valve means such that when the piston is at the top of its stroke, being the position of its stroke where the compressed gas is substantially evacuated from the pneumatic cylinder, the valve means is actuated to permit the compressed gas to flow from the pipeline to the pneumatic cylinder, and such that when the piston is substantially at the bottom of its stroke, being the position of its
English Glendon Elmer
English Rodney Ralph
Denion Thomas
Envirodrive Inc.
Leslie Michael
Miller & Thomson LLP
LandOfFree
High-pressure pneumatic and liquid injection apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with High-pressure pneumatic and liquid injection apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High-pressure pneumatic and liquid injection apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2874328