Integrated mixing pump
A mixing pump includes a power cylinder and a second cylinder wherein one of the power cylinder and the second cylinder is interchangeable between single and double acting and wherein a working fluid is supplied to the power cylinder under pressure.
1. Field of the Invention
The present invention generally relates to a mixing system. More particularly, the invention relates to a mixing system for pumping two or more liquids from storage tanks to a supply tank.
2. Background Art
There are numerous situations in which it is necessary to pump a mixture of fluids created from multiple sources. In the chemical industry and the fuel industry, it is desirable to control proportions within a mixture. For example, offshore oil drilling rigs often use water based fluids for hydraulic power for subsea control systems. Hydraulic fluids are typically low viscosity fluids used for the transmission of useful power by the flow of the fluid under pressure from a power source to a load. A liquid hydraulic fluid generally transmits power by virtue of its displacement under a state of stress with low compressibility.
Hydraulic power is often used to actuate subsea tools. One example of a subsea control system that uses hydraulic power is a blowout preventer (“BOP”). A BOP forms a seal around drill string to seal off well-head pressure when an area of high pressure, such as a high pressure gas pocket, has been contacted during drilling. A BOP may use hydraulic fluid to actuate numerous components of the BOP. For example, hydraulic actuators may be used to move BOP rams axially within a bonnet assembly in a direction generally perpendicular to a wellbore axis.
At present, many conventional hydraulic fluids are not suitable for subsea applications due to their low tolerance to sea water contamination or to contamination by hydrocarbons. For example, conventional hydraulic fluids tend to readily form emulsions with small amounts of hydrocarbons. Furthermore, in marine environments, problems may arise due to bacterial infestations in the hydraulic fluid, especially from anaerobic bacteria, such as sulfate reducing bacteria prevalent in sea water. Additionally, though some conventional hydraulic fluids are substantially non-corrosion-resistant, many, in fact, cause corrosion with metals in contact with the fluid. Other conventional hydraulic fluids are reactive with paints, metal coatings, and elastomeric substances. Further, depending on the location of the control systems in which hydraulic fluids are used, the freezing point of the hydraulic fluid may need to be lowered.
Accordingly, in order to create a hydraulic fluid that may be used in a particular system, multiple additives may be combined with a base fluid. The majority of base fluids are potable water. In some instances, a hydraulic or BOP control fluid concentrate may be added to potable water. Control fluid concentrates are additive fluids that may be used, for example, to provide lubricity for moving parts in the control system, prevent corrosion of ferrous metal alloys, provide anti-wear properties, and provide a biocide. A biocide, also known as a bactericide, is an additive that prevents growth of micro-organisms. Commercially available examples of control fluid concentrates include Erifon HD 603HP, provided by MacDermid (Pasadena, Tex.), and Stack Magic, provided by Houghton Offshore (Houston, Tex.). At standard dilution ratios, control fluid concentrates and working fluids may be used at temperatures down to 32° F. (0° C.). In instances having operational temperatures below 32° F. (0° C.), a glycol additive may be used to lower the freezing point of the hydraulic fluid.
These fluids (working and additive fluids) are commonly mixed on a rig and stored in a supply tank. The ratio of the components of the mixture must be accurate enough to provide the right amount of biocide, lubricity, wear, and anti-freeze protection. Incorrect ratios of the components of the mixture may cause premature wear or failure of control system components. Alternatively, excess additive amounts are costly.
Generally, once the ratios of components of a control system fluid are determined for a particular application, the ratio does not change. However, if the ratio is changed, it is usually based on a change in operational temperature to accommodate fluctuations for the need of glycol.
Currently, there are generally two types of mixing systems used to mix multiple fluids into a hydraulic fluid for use in subsea control systems. The first mixing system includes an individual pump and motor for each fluid component. In this system, each component fluid may be stored in a separate storage tank and separate motor driven pumps supply each component fluid to a supply tank. Accordingly, variations in the calibrations of the pumps or variations in the water supply pressure may result in an inaccurate mixture. Additionally, failure of a single motor may result in an inaccurate mixture. Further, as space is limited on ocean rigs, it is often difficult to provide sufficient space for three storage tanks, three pumps, and three motors, in addition to a supply tank.
A second, less common, mixing system includes a single motor with multiple drive belts coupled to multiple pumps. In this system, each component fluid may be stored in a separate storage tank and separate pumps driven by a single common motor with multiple belt drives supply each component to a supply tank. Variations in water supply pressure, however, may result in inaccurate mixture ratio. Additionally, maintenance of the belt drives and pulleys for the belt drives may cause variations in the mixture ratio. Further, as pump calibration is critical to maintaining a desired ration, variations in the calibrations of the pumps may result in inaccurate mixtures.
Accordingly, there exists a need for a mixing system that provides accurate ratios of each component of a mixture. Additionally, there exists a need for accurate ratios of each component of a mixture when fluid inlet pressures may vary. Further, there exists a need for a mixing system that requires a small amount of space on an ocean rig.
SUMMARY OF INVENTIONIn one aspect, the present invention relates to a mixing pump having a power cylinder and a second cylinder, wherein one of the power cylinder and the second cylinder is interchangeable between single and double acting and wherein a working fluid is supplied to the power cylinder under pressure.
In another aspect, the present invention relates to a mixing pump including a power cylinder, a second cylinder, and a third cylinder, wherein a working fluid is supplied to the power cylinder under pressure.
In another aspect, the present invention relates to a mixing pump including a first cylinder, a second cylinder, and a piston assembly. Preferably, a first piston of the piston assembly divides the first cylinder into a first chamber and a second chamber and a second piston of the piston assembly divides the second cylinder into a third chamber and a fourth chamber. Preferably, a pressurized working fluid is connected to a switching mechanism wherein the switching mechanism is configured to alternately communicate the pressurized working fluid between the first and second chambers of the first cylinder to displace the first piston. Preferably, a first additive fluid is connected to an inlet of one of the third and the fourth chambers of the second cylinder, wherein the pressurized working fluid and the additive fluid are outputted to a supply tank as the piston assembly reciprocates within the fist and second cylinders.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
In one aspect, embodiments of the present invention relate to mixing systems that supply a pre-determined ratio of at least two fluids to a supply tank. In another aspect, embodiments of the present invention relate to mixing systems that provide three fluids to a mixing pump that pumps a pre-determined ratio of the three fluids to a supply tank. In another aspect, embodiments of the present invention relate to mixing pumps that control a ratio of components of a mixture being pumped into a supply tank.
Referring initially to
As shown in cross-sectional view of mixing pump 102 in
As discussed above, a base fluid and at least one additive fluid may be combined with mixing system 100. The base fluid and at least one additive fluid may be any fluids known in the art. For example, in the embodiment shown in
Referring still to
In the embodiment shown in
In the embodiment shown in
As first piston 120 moves to the left, pressurized water 113 in first chamber 140 of power cylinder 114 is forced through outlet 162 to the supply tank (not shown). Simultaneously, piston rod 126 moves second piston 122 of second cylinder 116 to the left. As second piston 122 moves to the left, glycol 106 in first chamber 144 is forced through outlet 152 of second cylinder 116 to the supply tank (not shown) and glycol 106 enters through inlet 151 and fills second chamber 146. Check valves 188 may be disposed on the additive fluid lines entering and exiting second cylinder 116 to prevent reverse flow of additive fluids 106, 108 therethrough. Therefore, switch valve 138 may be used to alternately fill first chamber 140 and second chamber 142 of power cylinder 114 such that pistons 120 and 122 reciprocate to pump and mix base working fluid 112 and glycol 106 together.
In another embodiment, if glycol 106 is no longer preferred in the mixture, selector valve 138 may change additive fluid supply to second cylinder 116 from glycol 106 to control system concentrate 108, for example. Additionally, in another embodiment, selector valve 138 may change additive fluid supply to each chamber 144 and 146 of second cylinder 116, for example, allowing glycol 106 to enter into first chamber 144 and control system concentrate 108 to enter into second chamber 146. Accordingly, the mixing pump 102 performs in the same manner described above. Those having ordinary skill in the art will appreciate that selector valve 138 may be actuated by any method known in the art, for example, manually, or electrically.
Further, in another embodiment, power cylinder 114 may instead be single acting. In this embodiment, power cylinder 114 may include a biasing mechanism to push against first piston 120. For example, with a spring disposed within second chamber 142 of power cylinder 114, pressurized working fluid may fill first chamber 140, move piston 120 to the right, and compress the spring disposed within chamber 142. When compressed, the spring may be used to then push first piston 120 to the left, rather than needing pressurized working fluid to switch from flowing across inlets 160, 161. Those having ordinary skill in the art will appreciate other biasing mechanisms, such as elastomer, may be used without departing from the scope of the present invention. Furthermore, in such circumstances, second chamber 142 of single acting power cylinder 114 may be vented to prevent accumulation of pressure within second chamber 142 as first piston 120 moves. As such, those having ordinary skill in the art will appreciate that any of the chambers may be vented when used within a single acting cylinder of the present invention.
Referring now to
As shown in
Referring still to
As shown in
In the embodiment shown in
Referring now to
Referring now to
Those having ordinary skill in the art will appreciate that the size of the cylinders, the size of the pistons, and the size of the piston rod may vary without departing from the scope of the present invention. Specifically, the sizes and volumes of the cylinders, pistons, and piston rod may be used to vary the ratio of individual components required for the mixture. For example, in one embodiment, by increasing the size of chambers E, F in
As shown and described with reference to
Those having ordinary skill in the art will appreciate that the present invention is not limited to the use of pistons. For example, in another embodiment, instead of a piston, a flexible diaphragm may be used. As pressurized working fluid enters the chambers of a cylinder, the flexible diaphragm may transfer pressure from one chamber to another chamber, allowing fluid to enter and exit the respective chambers. Additionally, in another embodiment, a plunger pump may be used instead of piston. Thus, the present invention is not limited by specific means to translate pressure from one chamber of a cylinder to another.
Those having ordinary skill in the art will appreciate that the present invention may be provided with a feedback mechanism. A feedback mechanism may be used to provide a relative position of a piston within its corresponding cylinder, thereby providing the current volumes of the chambers with the cylinder. Common examples that may be used for a feedback mechanism may be a linear variable displacement transducer (“LVDT”), a microswitch, or a magnet.
While embodiments described above refer to a mixing system and mixing pump with three cylinders (i.e., one power, two additive cylinders), those having ordinary skill in the art will appreciate that additional fluids may be combined at differing ratios by providing additional cylinders and pistons. These additional pistons may be coupled to the piston rod and powered by a fluid pressure acting within a power cylinder. For example, in another embodiment, a fourth cylinder having a fourth piston disposed therein may be added to the mixing pump. As such, the fourth cylinder may be attached to the third cylinder with the fourth piston may be coupled to the third piston through the piston rod. As the piston rod, and therefore the third piston, moves from the fluid pressure within the power cylinder, the fourth piston would correspondingly move within the fourth cylinder, pumping the fluids supplied to the fourth cylinder to a supply tank.
Advantageously, the present invention provides a mixing system with accurate and reliable ratios of components in a mixture. The present invention provides a mixing system that requires less space for operation. Further, the present invention provides a mixing system with fewer pumps and motors, allowing a mixing pump to be most cost effective.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
Claims
1. A mixing pump comprising:
- a power cylinder; and
- a second cylinder;
- wherein one of the power cylinder and the second cylinder is interchangeable between single and double acting;
- wherein a working fluid is supplied to the power cylinder under pressure.
2. The mixing pump of claim 1, wherein the power cylinder includes a biasing mechanism.
3. The mixing pump of claim 1, further comprising a third cylinder.
4. The mixing pump of claim 1, wherein one of the working fluid and an additive fluid is supplied to the second cylinder.
5. The mixing pump of claim 4, wherein the additive fluid is at least one of glycol and control system concentrate.
6. The mixing pump of claim 1, further comprising a fluid selector valve coupled to the second cylinder.
7. The mixing pump of claim 1, further comprising a switch valve to alternately direct the working fluid between a first chamber and a second chamber of the power cylinder.
8. A mixing pump comprising:
- a power cylinder;
- a second cylinder; and
- a third cylinder;
- wherein a working fluid is supplied to the power cylinder under pressure.
9. The mixing pump of claim 8, wherein at least one of the power cylinder, the second cylinder, and the third cylinder is interchangeable between single and double acting.
10. The mixing pump of claim 8, wherein at least one of the working fluid and an additive fluid is supplied to at least one of the second cylinder and the third cylinder.
11. The mixing pump of claim 10, wherein the additive fluid is at least one of glycol and control system concentrate.
12. The mixing pump of claim 8, wherein the working fluid is potable water.
13. The mixing pump of claim 8, further comprising a switch valve to alternately direct the working fluid between a first chamber and a second chamber of the power cylinder.
14. A mixing pump comprising:
- a first cylinder, a second cylinder, and a piston assembly;
- a first piston of the piston assembly dividing the first cylinder into a first chamber and a second chamber;
- a second piston of the piston assembly dividing the second cylinder into a third chamber and a fourth chamber, wherein the second piston is displaced by the first piston;
- a pressurized working fluid connected to a switching mechanism, wherein the switching mechanism is configured to alternately communicate the pressurized working fluid between the first and second chambers of the first cylinder to displace the first piston; and
- a first additive fluid connected to an inlet of one of the third and the fourth chambers of the second cylinder;
- wherein the pressurized working fluid and the additive fluid are outputted to a supply tank as the piston assembly reciprocates within the first and second cylinders.
15. The mixing pump of claim 14, wherein the first and second cylinders are sized to output a specified ratio of the pressurized working fluid and the first additive fluid.
16. The mixing pump of claim 14, wherein a second additive fluid is connected to an inlet of the other of the third and fourth chambers of the second cylinder.
17. The mixing pump of claim 16, wherein the first and second cylinders are sized to output a specified ratio of the pressurized working fluid, the first additive fluid, and the second additive fluid.
18. The mixing pump of claim 14, wherein the first additive fluid is connected to an inlet of the other of the third and fourth chambers of the second cylinder.
19. The mixing pump of claim 14, further comprising:
- a third cylinder;
- a third piston of the piston assembly dividing the third cylinder into a fifth chamber and a sixth chamber, wherein the third piston is displaced by the first piston; and
- a second additive fluid connected to an inlet of at least one of the fifth and sixth chambers of the third cylinder.
20. The mixing pump of claim 19, wherein the first, second, and third cylinders are sized to output a specified ratio of the pressurized working fluid, the first additive fluid, and the second additive fluid.
21. The mixing pump of claim 14, wherein the pressurized working fluid is switchably connected to an inlet of at least one of the third and fourth chambers of the second cylinder.
Type: Application
Filed: Jun 9, 2006
Publication Date: Dec 13, 2007
Inventor: Maynard Chance (Houston, TX)
Application Number: 11/450,615
International Classification: F04B 35/00 (20060101);