Liquid pump and method for pumping a liquid that may have gas coming out of solution
The present invention increases the pumping efficiency when pumping liquids whose liquid source is at a temperature and pressure close to the liquidus, or having entrained gas or gas coming out of solution, referred to as vapor, in several ways. First, the pump is oriented to allow liquid flowing into the compression chamber by the natural tendency of liquid to flow downward and residual vapor to return to the supply tank, by the natural tendency of vapor to flow upward. The location of the large smooth inlet line at the top of the pump encourages any vapor to escape and be piped back to the supply tank. The flow of vapor back to the supply tank is also encouraged by the vapor outlets and conduit leading back, at a positive slope, to the supply tank. Second, the inlet chamber located above the inlet valve reduces cavitation because this chamber prepares a new discrete volume of inlet liquid while the current discrete volume is being power-stroked out of the compression chamber. This is furthered by setting the inlet valves in angled pockets which encourage and facilitates the release any released vapor bubbles back to the top of the inlet line during the power stroke. Finally, the current invention discourages cavitation because the unswept volume is minimized. This is critical to the efficiency of the pump as well as reduction of the adverse effects of cavitation because this residual liquid tends to vaporize when subjected to depressurization during the intake stroke.
This invention relates generally to pumps for pumping a liquid from a source with a temperature and pressure near its liquidus or containing entrained or dissolved gas.
BACKGROUND OF THE PRESENT INVENTIONThe invention relates to the apparatus and methods suitable for either mobile or stationary liquid reciprocating pumping systems whose liquid source is at a temperature and pressure close to its liquidus. Liquid carbon dioxide (CO2) is an example of this type of liquid source. Liquids having dissolved or entrained gas, may also be pumped using the current invention.
While a number of pumps are disclosed in the art, such pumps tend to have an overly large unswept volume. The unswept volume is that volume of liquid remaining in the pumping chamber at the end of the power stroke of the pump. The present invention reduces the unswept volume to a minimum by fitting the inlet valves at an angle which allows delivery of the liquid from the inlet valves directly into the pumping chamber. The unswept residual liquid tends to vaporize when subjected to depressurization during the intake stroke, a phenomena known as cavitation which can cause excessive wear on the internal pump components and will reduce the efficiency of the pump.
Cavitation occurs when vapor bubbles are formed as a result of the lowered pressure of the liquid as it is drawn into the suction of the pump during the intake stroke. Some pumps reduce the liquid's pressure below the vapor pressure of the liquid at the existing temperature, causing it to vaporize. In the extreme situation, the pump can become filled with vapor and may be unable to pump. More importantly, the vapor bubbles will violently recondense into liquid form as the pressure is increased during the liquid's travel during the power stroke of the pump. The pressure pulse from the implosion of the vapor bubble attacks adjacent materials. The effects of cavitation may also combine with corrosion further increasing the speed of wear of the pump materials. In some cases, the original protective layers provided on the pump materials will be destroyed, rendering the exposed metal surface permanently activated for chemical attack.
The present invention reduces cavitation in several ways. First, the pump is oriented to allow liquid flowing into the compression chamber by the natural tendency of liquid to flow downward and residual vapor to leave the compression chamber, and return to the supply tank, by the natural tendency of vapor to flow upward. The location of the large smooth inlet line at the top of the pump encourages any vapor to escape and be piped back to the supply tank. The flow of vapor back to the supply tank is also encouraged by the conduit leading back, at a positive slope, to the supply tank. This principle will also apply to liquids where dissolved gas can come out of solution or where gas is entrained.
Second, the inlet chamber located above the inlet valve reduces cavitation because this chamber prepares a new discrete volume of inlet liquid while the current discrete volume is being power-stroked out of the compression chamber. This is furthered by setting the inlet valves in angled pockets that encourage and facilitate the buoyancy and upward movement of any released bubbles back to the top of the inlet line during the power stroke.
Third, the current invention discourages cavitation because the unswept volume, as discussed above, is minimized. This is critical to the efficiency of the pump as well as reduction of the adverse effects of cavitation because this residual liquid tends to vaporize when subjected to depressurization during the intake stroke.
Although the foregoing art addresses some of the various needs of the industry, the devices and methods described present an improvement in cavitation reduction and pump efficiency.
SUMMARY OF THE INVENTIONThe present invention increases the pumping efficiency of liquids whose liquid source is at a temperature and pressure close to its liquidus, or liquids with entrained or dissolved gas, referred to as a vapor in several ways. First, the pump is oriented to allow liquid flowing into the compression chamber by the natural tendency of liquid to flow downward and residual vapor to return to the supply tank, by the natural tendency of vapor to flow upward. The location of the large smooth inlet line at the top of the pump encourages any vapor to escape and be piped back to the supply tank. The flow of vapor back to the supply tank is also encouraged by the vapor outlet and conduit leading back, at a positive slope, to the supply tank. The vapor outlet can be slightly higher than the liquid inlet to improve the purging of the vapor. Second, the inlet chamber located above the inlet valve reduces cavitation because this chamber prepares a new discrete volume of inlet liquid while the current discrete volume is being power-stroked out of the compression chamber. This is furthered by setting the inlet valves in angled pockets which encourages and facilitates the release of any released vapor bubbles back to the top of the inlet line during the power stroke. Finally, the current invention discourages cavitation because the unswept volume is minimized. This is critical to the efficiency of the pump as well as reduction of the adverse effects of cavitation because this residual liquid tends to vaporize when subjected to depressurization during the intake stroke. The effects of liquid compressibility are reduced with reduced unswept volume.
An object and advantage of the invention is to provide an improved apparatus and method of pumping liquids that removes vapor from the pump and returns the vapor to the supply tank in a more efficient manner.
Another object and advantage of the invention allows the pumping of liquids whose liquid source is at a temperature and pressure close to its liquidus or has entrained gas or gas coming out of solution.
An object and advantage of the invention is to provide an apparatus and method of pumping liquids that decreases the unswept volume of the pump.
Yet another object and advantage of the invention is to provide an apparatus and method of pumping liquids with reduced cavitation.
Another object and advantage of the invention is to provide an apparatus and method of pumping liquids that increases the efficiency of the pump.
The foregoing objects and advantages of the invention will become apparent to those skilled in the art when the following detailed description of the invention is read in conjunction with the accompanying drawings and claims. Throughout the drawings, like numerals refer to similar or identical parts.
BRIEF DESCRIPTION OF THE DRAWINGS
With reference to the accompanying figures,
As
The pump 10 is drivingly connected to a drive means, e.g., an electric motor 11. Actuation of the pump 10 by the motor 11 will result in liquid being drawn from the bottom of the supply tank 12 into the pump 10 with the liquid ultimately being pumped out of the pump 10 through a liquid outlet conduit 18. Any vapor released inside the pump 10 will tend, as a result of the invention, to be released into the upwardly inclined vapor outlet conduit 16, thus preventing the bubbles from moving through the internal valved chambers of the pump 10. Thus, cavitation is minimized and volumetric efficiency maximized.
Turning now to
The downwardly declined liquid-vapor inlet conduit 14, shown in
A displacement element, shown as a plunger 24, an alternate embodiment may be a piston, is in communication with the compression chamber 62 and is drivingly connected to the crankshaft 22 which is, in turn, driven by the motor 11. The plunger 24 moves backward in a suction stroke to draw liquid into the compression chamber 62 and forward in a power stroke to push liquid out of the compression chamber 62. The preferred embodiment provides a valve chamber 42 volume that is greater than the volume vacated by the plunger 24 after completing a full suction stroke in the compression chamber 62.
The lower portion of the compression chamber 62 is in valved fluid communication with the liquid outlet chamber 76. The outlet valve 66 consists preferably of a valve seat 68, a spring retainer 70, a valve spring 72 and a valve plug 74.
Operation of the preferred embodiment may now be described. Initially, it is ensured that the liquid is in equilibrium through the pumping system. When this is achieved, liquid is allowed to substantially fill the upper inlet chamber 40, the vapor release conduit 16 up to the fluid equilibrium level 19, and the valve chambers 42.
Once equilibrium is achieved, the liquid resident in the upper inlet chamber 40 and in the valve chambers 42 is prepared by the invention design by allowing time for any released vapor bubbles to move upwardly. The natural tendency for vapor to move upward is facilitated by the angling of the valve chamber 42. The preferred embodiment further includes a substantially smooth upper surface 48 within the valve chamber 42 to allow the released vapor bubbles to move more readily upwardly along the upper surface 48 and ultimately, into the upper inlet chamber 40.
Actuation of the crankshaft 22 by the motor 11 results in the plunger 24 moving either forward in a power stroke or backward in a suction stroke.
As illustrated in
As discussed above, during the power stroke, the liquid that is in contact with the valve chamber 42 has time to allow any released vapor bubbles to flow upwardly which will occur since the bubbles are lighter than the liquid. The upwardly angled valve chamber 42 then facilitates the escape of the bubbles into the upper inlet chamber 40. When the pump is operating, the natural flow of the bubbles will be upward and toward the region of least pressure. Since the flow will be sustained from the downwardly declining liquid inlet conduit 14 that connects with the bottom of supply tank 12 there will be a natural tendency for the bubbles to move to the upwardly inclining gas outlet conduit 16 which connects with the tank 12 at a point above the fluid equilibrium level 19. As a result, the bubbles are released from the pump system and returned to the supply tank 12.
The angling of the valve chamber 42 also reduces cavitation by reducing the unswept volume of the compression chamber 62. The unswept volume is the volume of liquid remaining in the compression chamber 62 when the plunger 24 is at the end of its power stroke. Vaporization of the liquid remaining unswept in the compression chamber 62 when subjected to depressurization during the suction stroke results in cavitation and reduces the efficiency of the pump 10. The present invention places the valved liquid inlet aperture 60 as near to the plunger as possible by angling the second end of the valve chamber 46 downwardly with respect to the first end of the valve chamber 44. As seen in
The above specification describes certain preferred embodiments of this invention. This specification is in no way intended to limit the scope of the claims. Other modifications, alterations, or substitutions may now suggest themselves to those skilled in the art, all of which are within the spirit and scope of the present invention. It is therefore intended that the present invention be limited only by the scope of the attached claims below:
Claims
1. A pump for pumping a liquid that may have gas coming out of solution, comprising:
- a manifold having an upper inlet chamber connected to at least one lower valve chamber with first and second ends, the first end adjacent and below the upper inlet chamber and the second end adjacent and above a compression chamber with an inlet valve between the second end of the at least one valve chamber and the compression chamber;
- a plunger displaceable in the compression chamber; and
- an outlet valve in a lower portion of the compression chamber.
2. The pump of claim 1, further comprising downwardly angling the at least one valve chamber such that the second end of the valve chamber is positioned lower than the first end of the valve chamber to facilitate the upward escape of released vapor and the downward flow of liquid.
3. The pump of claim 1, further comprising the valve chamber having a substantially smooth upper side.
4. The pump of claim 1, wherein the volume of the at least one valve chamber is greater than the volume vacated by the plunger in moving its full stroke in the compression chamber.
5. The pump of claim 1, further comprising:
- a downwardly declining inlet conduit in fluid communication with the upper inlet chamber;
- an upwardly inclining vapor release conduit in fluid communication with the upper inlet chamber; and
- a supply tank containing liquid in liquid communication with the inlet conduit and vapor with the vapor release conduit, wherein the pump is at a lower level than the level of liquid in the supply tank to facilitate the downward flow of liquid and the upward escape of released vapor, the inlet conduit and vapor release conduits being in fluid communication with the upper inlet chamber.
6. A pump, for pumping liquids that may have gas coming out of solution, comprising:
- a manifold having an upper inlet chamber connected to at least one lower valve chamber with a substantially smooth upper side and having first and second ends, the first end adjacent to the upper inlet chamber and the second end adjacent and above a compression chamber with an inlet valve between the second end of the at least one valve chamber and the compression chamber, then at least one valve chamber being downwardly angled by positioning the second end of the valve chamber lower than the first end of the valve chamber;
- a plunger displaceable in the compression chamber;
- an outlet valve in a lower portion of the compression chamber;
- a downwardly declining inlet conduit in fluid communication with the upper inlet chamber;
- an upwardly inclining vapor release conduit in fluid communication with the upper inlet chamber; and
- a supply tank in fluid communication with the inlet conduit and vapor release conduit, the supply tank containing liquid, wherein the pump is at a lower level than the level of liquid in the supply tank.
7. A method for reducing cavitation in a pump, for pumping liquids that may have gas coming out of solution, the method comprising:
- locating the upper inlet chamber adjacent to and above the valve chamber;
- locating the valve chamber adjacent to and above a compression chamber with an inlet valve therebetween;
- locating an outlet valve in a lower portion of the compression chamber;
- facilitating the removal of vapor released by the liquid while held in the upper inlet chamber and valve chamber; and
- providing an upwardly inclined conduit for vapor released by the liquid while held in the upper inlet chamber and valve chamber to return to the liquid supply tank.
8. The method of claim 7, further comprising facilitating the removal of vapor released by the liquid while held in the upper inlet chamber and valve chamber by downwardly angling the valve chamber so that the second end of the valve chamber is lower with respect to the first end of the valve chamber.
9. The method of claim 8, further comprising ensuring the upper side of the valve chamber is substantially smooth.
10. The method of claim 9, further comprising placing the pump lower than the level of liquid in the supply tank.
11. A method for reducing cavitation in a pump for pumping a liquid that may have gas coming out of solution, the method comprising:
- locating the upper inlet chamber adjacent to and above the valve chamber;
- locating the valve chamber above a compression chamber with an inlet valve therebetween, wherein the valve chamber is downwardly angled so that the second end of the valve chamber is lower with respect to the first end of the valve chamber and the upper side of the valve chamber is substantially smooth;
- facilitating the removal of vapor released by the liquid while held in the upper inlet chamber and valve chamber; and
- providing an upwardly inclined conduit for vapor released by the liquid while held in the upper inlet chamber and valve chamber to return to the supply tank, wherein the pump is placed at a lower level than the liquid in the supply tank.
12. A method for reducing the unswept volume in a pump for pumping a liquid that may have gas coming out of solution, the method comprising:
- locating the upper inlet chamber adjacent to and above the valve chamber;
- locating the valve chamber above a compression chamber with an inlet valve therebetween;
- minimizing the distance between the inlet valve and the compression chamber by downwardly angling the inlet valve;
- facilitating the removal of vapor released by the liquid while held in the upper inlet chamber and valve chamber; and
- providing an upwardly inclined conduit for vapor released by the liquid while held in the upper inlet chamber and valve chamber to return to the liquid supply tank, wherein the pump is lower than the level of liquid in the supply tank.
13. A method for increasing the efficiency of a pump for pumping liquids a liquid source that may have gas coming out of solution, the method comprising:
- locating the upper liquid gas inlet chamber adjacent to and above the valve chamber;
- locating the valve chamber above a compression chamber with an inlet valve therebetween, wherein the valve chamber is downwardly angled so that the second end of the valve chamber is lower with respect to the first end of the valve chamber and the upper side of the valve chamber is substantially smooth;
- facilitating the removal of vapor released by the liquid while held in the upper inlet chamber and valve chamber;
- minimizing the distance between the inlet valve and the compression chamber by downwardly angling the inlet valve; and
- providing an upwardly inclined conduit for vapor released by the liquid while held in the upper inlet chamber and valve chamber to return to the supply tank, wherein the pump is placed at a lower level than the liquid in the supply tank.
Type: Application
Filed: Jul 4, 2003
Publication Date: Sep 28, 2006
Inventor: Leslie Warren (Hampshire)
Application Number: 10/555,828
International Classification: F04B 39/10 (20060101);