LIQUID HYDROCARBON FLUID TRANSFER SYSTEM

Abstract

A fluid transfer system within a berm surrounding at least one bulk fluid storage tank includes: a rotary positive displacement pump; and an air motor adapted to be in fluid communication with an air supply and in operable communication with the rotary positive displacement pump, for driving the pump, the air supply provided by an air compressor outside of the berm, wherein the rotary positive displacement pump is adapted to pump from a first bulk fluid storage tank to a second bulk fluid storage tank, wherein the second bulk fluid storage tank may have a greater potential energy than the first bulk fluid storage tank.

Claims

1. A fluid transfer system comprising: a rotary positive displacement pump, said pump containing an inlet and an outlet; and an air motor adapted to be in fluid communication with a compressed air supply and in operable communication with said rotary positive displacement pump, for driving said pump, said rotary positive displacement pump adapted to pump 0-250 gallons per minute from a first bulk fluid storage tank to a second bulk fluid storage tank, said pump and at least one of said first and second bulk fluid storage tanks surrounded by a berm, wherein said rotary positive displacement pump is a hydrocarbon or oil pump, and said compressed air supply is located outside of said berm and spaced away from said rotary positive displacement pump, in operable communication therewith.

2. The fluid transfer system of claim 1, wherein said second bulk storage tank has a greater second potential energy of a second bulk fluid therein as compared to a first potential energy of a first bulk fluid in said first bulk storage tank.

3. The fluid transfer system of claim 1 wherein said rotary positive displacement pump is adapted to pump 0.1-250 gallons per minute.

4. The fluid transfer system of claim 1 wherein said rotary positive displacement pump is adapted to pump 50-250 gallons per minute.

5. A fluid transfer system within a berm surrounding at least one bulk fluid storage tank comprising: a rotary positive displacement pump; and an air motor adapted to be in fluid communication with an air supply and in operable communication with said rotary positive displacement pump, for driving said pump, said air supply provided by an air compressor outside of said berm, wherein said rotary positive displacement pump is adapted to pump from a first bulk fluid storage tank to a second bulk fluid storage tank, and wherein said second bulk fluid storage tank has a greater second potential energy of a second bulk fluid therein, as compared to a first potential energy of a first bulk fluid in said first bulk fluid storage tank.

6. The fluid transfer system of claim 5 wherein said rotary positive displacement pump contains an inlet, adapted to be in fluid communication with said first bulk fluid storage tank, and, said rotary positive displacement pump contains an outlet adapted to be in fluid communication with said second bulk fluid storage tank.

7. The fluid transfer system of claim 5 wherein said rotary positive displacement pump is adapted to pump 0-250 gallons per minute from a first bulk storage tank to a second bulk storage tank.

8. The fluid transfer system of claim 5 wherein said rotary positive displacement pump is adapted to pump 0.1-250 gallons per minute.

9. A method of pumping a hydrocarbon fluid comprising the following steps: providing an air-driven rotary positive displacement pump having a pumping capacity of 0-250 gallons per minute; providing an air-supply in fluid communication with the pump, to drive the pump; providing a hydrocarbon fluid to an inlet of the pump; and pumping the hydrocarbon fluid through the pump and out an outlet of the pump.

10. The method of claim 9 wherein the air supply is provided through an air compressor located outside of a berm surrounding the rotary positive displacement pump.

11. A fluid transfer system comprising: a rotary positive displacement pump, said pump containing an inlet and an outlet; and an air motor adapted to be in fluid communication with a compressed air supply and in operable communication with said rotary positive displacement pump, for driving said pump, said rotary positive displacement pump adapted to pump 0-250 gallons per minute from a first bulk fluid storage tank to a second bulk fluid storage tank, said pump and at least one of said first and second bulk fluid storage tanks surrounded by a berm, wherein said rotary positive displacement pump is a hydrocarbon or oil pump, and said compressed air supply is located outside of said berm and spaced away from said rotary positive displacement pump, in operable communication therewith, and wherein said rotary positive displacement pump is adapted to pump fluid from a first storage tank to a second storage tank, and said second storage tank may have a greater potential energy as compared to said first storage tank.

12. The fluid transfer system of claim 11, wherein said first storage tank is equal in size, dimensions, and volume to said second storage tank, and wherein the rotary positive displacement pump is adapted to pump fluid from the first storage tank to the second storage tank as the fluid height of the second storage tank exceeds the fluid height of the first storage tank.

13. The fluid transfer system of claim 12 wherein during operation of the fluid transfer system, the potential energy of the second storage tank ranges from 10 to 40 times the potential energy of the first storage tank as the fluid from the first storage tank is pumped into the second storage tank.

14. The fluid transfer system of claim 11, wherein said first storage tank is lesser in size, dimensions, and volume as compared to said second storage tank, and wherein the rotary positive displacement pump is adapted to pump fluid from the first storage tank to the second storage tank as the fluid height of the second storage tank exceeds the fluid height of the first storage tank.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Presently preferred embodiments of the invention are disclosed in the following description and in the accompanying drawings, wherein:

[0022] FIG. 1 illustrates a schematic view of a portable and mobile pump assembly, in accordance with the present invention.

[0023] FIG. 2 schematically illustrates a perspective and schematic view of a portable and mobile pump assembly of the present invention.

[0024] FIG. 3 schematically illustrates a first bulk fluid storage tank in fluid communication with a second bulk fluid storage tank, in accordance with the present invention.

[0025] FIG. 4 schematically illustrates a fluid transfer system, in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] In accordance with the present invention, a liquid hydrocarbon transfer apparatus 10 includes an air compressor 12 at a location preferably spaced away from a storage tank 14 (that is, outside of the berm 324 containing the storage tank 14), wherein the storage tank 14 contains a bulk fluid such as a hydrocarbon fuel, for example. A liquid hydrocarbon transfer pump assembly 16 is positioned adjacent to the storage tank 14, preferably somewhere within the berm 324 containing the storage tank 14. The hydrocarbon transfer pump assembly 16 is operably connected to the air compressor 12 by an elongated air supply hose 20. The air compressor 12 is preferably located outside of the berm containing the storage tanks. The fuel transfer pump assembly 16 is connected to a first outlet valve 22 on the storage tank 14 by a primary flexible hydrocarbon discharge pipe. 28.

[0027] The hydrocarbon transfer pump assembly 16 may also be connected to a second outlet valve 24 by a secondary flexible hydrocarbon discharge pipe 30. As shown in the Figures, an inlet 15 contained within the hydrocarbon transfer pump assembly 16 may contain a plurality of sub-inlets (not shown) that each fluidly communicate with a flexible hydrocarbon discharge pipe such as first and second flexible hydrocarbon discharge pipes 28 and 30. A pump discharge port 32 is connected to a receiving valve 34 on a receiving storage tank 36 by a flexible hydrocarbon transfer pipe 38.

[0028] The exemplary air compressor 12 of one embodiment has a rated capacity of one hundred and eighty cubic feet per minute (cfm). The air compressor 12 may include an enclosed housing 42. The compressor housing 42 protects a drive unit and an air compressor 12 from rain and snow. The compressor drive unit that is employed may be an internal combustion engine or an electric motor, for example. Diesel engines are generally chosen for use in a tank farm and may be used to drive the compressor. A muffler 43 is typically used to reduce noise. The compressor housing 42 may be mounted on a trailer frame (not shown), for example. The trailer may be moveable by a motor vehicle. However, the housing 42 can be carried on a truck or in a van. The compressor housing 42 may also be provided on skids and unloaded onto the ground during use. In this embodiment, compressed air is provided from the compressor housing 42 through an insulated hose 44 with a 0.75 inch inside diameter. An insulated hose 44 is used to prevent condensation and freezing of water inside the insulated hose 44 during relatively cooler weather. Again, the air compressor 12 is preferably located outside of the tank berm, to enhance the safety of the operation.

[0029] The liquid hydrocarbon transfer pump assembly 16 includes a filter assembly 46 with a filter inlet flange 48 and a filter outlet flange 50. Both flanges 48 and 50, may as provided in this embodiment, have a four-inch diameter. In yet another embodiment, the flanges may both have a three-inch diameter. The inlet flange 48 is fixed to a filter housing 52. A filter 51 is removably contained within the filter housing 52, for straining or filtering the inlet flow of fuel or bulk fluid. The filter outlet flange 50 is also fixed to the filter housing 52, opposite to the inlet flange 48. A top cover 54 of the filter assembly 46 is clamped to the filter housing 52 by bolts 56. The filter assembly 46 and the filter 51 therefore separates materials mixed with the bulk fluid or hydrocarbons that might damage the fuel transfer pump assembly 16. The top cover 54 may be removed when necessary to clean the filter assembly 46. An inlet adapter 58 has an inlet adapter flange 60, and an inlet tube 62 fixed to the inlet adapter flange 60. Bolts 64 clamp the inlet adapter flange 60 to the filter inlet flange 48. An outlet adapter 66 has an outlet adapter flange 68, and an outlet tube 70 fixed to the outlet adapter flange 68. Bolts 72 clamp the outlet adapter flange 68 to the filter outlet flange 50. The inlet tube 62 and the outlet tube 70 may have tube passages with a three-inch or four-inch diameter, for example, or they may be varied depending on design criteria. The inlet tube 62 may, in a preferred embodiment, be coaxially aligned with the outlet tube 70.

[0030] The inlet tube 62 of inlet adapter 58 is connected to the primary flexible fuel discharge pipe 28. As stated above, the discharge pipe 28 is connected to the first outlet valve 22. An exemplary first outlet passage 76 extends through a cylindrical wall 78 of the hydrocarbon storage tank 14, and is positioned above a tank horizontal floor 80 and below a tank roof 82. The first outlet valve 22 fluidly communicates with the first outlet passage 76 to facilitate flow out of the tank 14. A plurality of roof support blocks 84 are attached to the tank 14 and support the tank roof 82 when it is in a bottom-most position. As shown in FIG. 3, the support blocks 84 vertically extend above the outlet passage 76 to ensure that the tank roof 82 is suspended above all such outlet passages.

[0031] The first outlet valve 22 therefore fluidly communicates with the flexible hydrocarbon fuel discharge pipe 28 which in turn, fluidly communicates with the inlet tube 62 of the inlet adapter 58. The primary flexible hydrocarbon discharge pipe 28 has an inside diameter that is preferably the same as the inside diameter of the inlet tube 62 attached to the filter assembly 46. However, in yet another embodiment, the ratio of the diameter of the flexible discharge pipe 28 to the diameter of the inlet tube 62 may range from a 1.0 to 1.0 ratio to a 1.0 to 1.5 ratio. It is believed that this relationship advantageously assists the pump in more efficiently pumping the contents from a tank.

[0032] The hydrocarbon transfer pump assembly 16 has an inlet port 86 and an outlet port 88. The pump assembly 16 is a rotary positive displacement pump 16. Importantly, an air-driven diaphragm positive displacement pump is not contemplated because of the disadvantages discussed above. Gorman Rupp, Roper, and Blackmer are exemplary manufacturers of positive displacement pumps that could also be used in accordance with the present invention. As shown in the Figures, in one embodiment, the pump assembly 16 is actually a Roper positive displacement pump 16a combined with an exemplary Gast air pump 150 to drive the Roper positive displacement pump 16a. The inlet pump port 86 is connected to the pump housing 90 by bolts, for example. A cam lock quick connector 94, attached to the outlet tube 70 on the filter assembly 46, engages the inlet port 86 and locks the filter assembly 46 to the transfer pump assembly 16. The passage through the filter assembly 46 and into the transfer pump 16a has a preferred three-inch diameter that defines a passage 96. The primary flexible discharge pipe 28 preferably has a minimal length and a three-inch inside diameter. Hydrocarbon liquid in the storage tank 14 above the first outlet valve 22 provides pressure to force hydrocarbon liquid through the pipe 28 and toward the transfer pump assembly 16. In accordance with the present invention, the hydrocarbon transfer pump assembly 16 evacuates liquid from the storage tank 14 and synergistically operates with the potential energy of the hydrocarbon fuel flowing from the tank 14.

[0033] As shown in FIG. 1, a secondary flexible hydrocarbon discharge pipe 30 may be attached to a second outlet passage 98 through the tank cylindrical wall 78 of the hydrocarbon storage tank 14. The second outlet passage 98 may be in communication with a tank trough 100 adjacent to the cylindrical wall 78, and below the tank horizontal floor portion 80. The tank trough 100 encircles the horizontal floor portion 80 and forms a radially extending portion of the tank floor 80. The secondary flexible hydrocarbon discharge pipe 30 joins the primary flexible hydrocarbon discharge pipe 28 adjacent to the filter inlet flange 48. Flow of liquid hydrocarbon from two pipes 28 and 30 are joined at the filter inlet flange 48. The two joined pipes enhance the flow rate into the pump assembly 16. The hydrocarbon flexible transfer pipe 38 has another end attached to a receiving valve 34 on a receiving storage tank 36.

[0034] The flexible hydrocarbon transfer pipes 28, 30, and 38 are sized to accommodate the distance between the storage tank 14 and the receiving tank 36. Stated another way, in operation, the pump assembly 16 fluidly communicates with the inlet tank 14 and a receiving tank 36, thereby obviating the need to handle the pumping system and the bulk fluid more than once when transferring the bulk fluid from the inlet tank 14 and the receiving tank 36. Ideally, the pump assembly 16 is positioned between the holding tank 14 and the transfer or receiving tank 36, thereby reducing the transfer time of the fluid, and thereby only requiring one transfer of the fluid and resulting in minimal tank disturbance. Stated another way, with the present system, the fluid is transferred from tank to tank, as opposed to being transferred from a tank to a truck, then moved and transferred to a second tank. This mitigates the likelihood of a spill while also minimizing the amount of fuel fumes into the air within the berm. Another result is a relatively faster pumping rate than that presented by the standard methods, with less open hoses during transfer, and with considerably less stress on the transfer hoses. As such, the present invention provides a relative reduced down time for the tanks as the fuel is expeditiously transferred, as compared to known transfer systems.

[0035] Referring back to the hydrocarbon transfer pump assembly 16, the gear box 148 is attached to and driven by an air motor 150, which is driven by air supplied by the air compressor 12. As stated above the gear ratio may range from 3:1 to 4:1 in a preferred embodiment. It has been found that this gear ratio results in greater efficiency with the present inventive pumping system. Yet further, in addition to other benefits of the present system, the suction rate can be easily controlled to transfer the last few gallons more thoroughly through the emptying process, with considerably less vortex during transfer.

[0036] The air motor 150 in a preferred embodiment has a nine-horsepower rating, however, any suitable power may be applied. Air from the air compressor 12 in an enclosed compressor housing 42 supplies compressed air through an air supply hose 20 (to the air motor 150). The compressed air is received by an air dryer and oiler 152. Dried air and some oil is discharged through a dry air supply pipe 154. Separated water is drained through a drainpipe 156. The dry air supply pipe 154 is connected to air supply port 158 on the air motor 150. An air discharge port 159 on the air motor 150 receives a discharge pipe 160, wherein the discharge pipe 160 may include a muffler 162. Oil is inserted into the air dryer and oiler 152 through an oil reservoir cap 164. In yet another aspect of the invention, the oil may be mixed with a fuel antifreeze constituent, in effective amounts. For example, in a preferred embodiment, the oil/antifreeze ratio may range anywhere from 20:80 to 80:20 by volume, and is preferably at 50:50 by volume. It has been found that the freezing normally attendant during cold temperatures, with air-driven pumps such as a diaphragm pump, can be alleviated by using a fuel antifreeze combined with the oil in the oiler 152. Not only is there less stress on the pump, but there is also less stress on the transfer hose as a result of mitigating the tendency for a freeze within the pump. A speed reduction gear box 148 attached to the air motor 150 drives a gear box drive shaft 146, wherein internal gears thereby drive the pump 16. In a preferred embodiment, the gear ratio of the gear box 148 may range from a three-to-one ratio to a four-to-one ratio.

[0037] A pipe 180 is attached to the pump outlet 88. A pressure gauge 182 is attached to the pipe 180 to measure the output pressure of liquid hydrocarbons at the outlet from the pump 16. A first ball valve (not shown) may be provided to be closeable to protect the pressure gauge 182 when a pressure measurement is not needed. A second ball valve (not shown) may be provided in the pipe 180 and would be openable to vent air from the system prior to the start of liquid hydrocarbon fuel transfer. The second ball valve would normally be closed.

[0038] The filter assembly 46, the positive displacement pump assembly 16 and the air motor 150 are mounted on a carriage frame 190. One or more wheels may support a front end of the frame 190. Accordingly, one end of the frame 190 may contain a single wheel 192, for steering the assembly 16. A second end of the frame 190 is supported by an axle 196 and two wheels 198. The entire frame 190 and attached components may be moved over a berm and up to a storage tank 14 that is to be emptied, by a small all-terrain vehicle or manually by one or two people depending on the terrain.

[0039] The air motor 150 and gear box 148 are mounted on a support beam 202 contained within the frame 190. A hitch assembly 200 may be attachable to a tow vehicle or pulled manually. The carriage frame 190 may be mounted on the two wheels 198, for example, or the carriage frame 190 may be mounted on two skids without wheels, or in lieu of wheels.

[0040] In yet another aspect of the invention, method of pumping a hydrocarbon fluid contains the following steps: providing an air-driven rotary positive displacement pump; providing an air- supply in fluid communication with the pump, to drive the pump; providing a hydrocarbon fluid to an inlet of the pump; and pumping the hydrocarbon fluid through the pump and out an outlet of the pump. The aforementioned method may further contain the additional step of: providing an oiler containing an oily composition in fluid communication with the air supply; and injecting the composition into the air supply to oil the air motor. Yet further, the aforementioned method may further contain the step of providing an oiler containing a composition containing an oil and a fuel antifreeze, in fluid communication with the air supply; and injecting the composition into the air-supply, to oil and de-ice the air motor. The fuel antifreeze may be any antifreeze or de- icing agent that is typically added to automotive vehicles, for example, to prevent icing of the fuel within a carburetor.

[0041] Referring now to FIGS. 1 and 2, and in yet another aspect of the invention, and as schematically exemplified in FIG. 2, a fluid transfer system 300 contains a liquid hydrocarbon transfer apparatus 10. The liquid hydrocarbon transfer apparatus 10 includes an air compressor 12 at a location preferably spaced away from a first bulk fluid storage tank 14, that is outside of a berm 324 containing the storage tank 14, wherein the storage tank 14 contains a bulk fluid 330 such as a hydrocarbon fuel, for example. Stated another way, it is contemplated that the air compressor 12 will be located proximate to the berm 324, but outside of the berm 324. A liquid hydrocarbon transfer pump assembly 16 or a rotary positive displacement pump 16, as exemplified and described above and in FIGS. 1 and 2, and herein incorporated by reference as if fully stated, is positioned adjacent to the first bulk fluid storage tank 14, or preferably somewhere within the berm 324 containing the storage tank 14. The hydrocarbon transfer pump assembly 16 is operably connected to the air compressor 12 by an elongated air supply hose 20. The air compressor 12 is preferably located outside of the berm 324 containing at least the first bulk fluid storage tank 14, and in another embodiment, the first storage tank 14 and the second storage tank 36. The fuel or hydrocarbon transfer pump assembly 16 is connected to a first outlet valve 22 on the storage tank 14 by a primary flexible hydrocarbon discharge pipe 28. A second bulk fluid storage tank 36 may also be located within the berm 324 or within a second berm (not shown) proximate or near the berm 324.

[0042] In accordance with the present invention, the transfer pump assembly 16 is adapted to pump at least 0-250 gallons per minute, and more preferably 0.1-250 gallons per minute, and even more preferably 50-250 gallons per minute, from the first storage tank 14 to the second storage tank 36, wherein at some point the second storage tank 36 may have a greater volume of fluid contained therein. As such, a second potential energy presented by a second volume within the second storage tank 36 for an identical or substantially similar fluid, a hydrocarbon fluid for example, is greater than a first potential energy presented by a first volume of bulk fluid contained within the first storage tank 14. As referred to herein, potential energy is defined to be the density of the bulk fluid being transferred multiplied by the gravitational constant multiplied by the height of the volume of fluid within a given bulk fluid tank. Accordingly, the potential energy may be defined by the formula: Gh, where is the density of the bulk fluid, in grams per cubic centimeter, G is the gravitational constant equal to 9.8 m/s.sup.2, and h (in meters) is the height of the bulk fluid in the respective storage tank.

[0043] In one embodiment, the first storage tank 14 is equal in size, volume, and dimensions (e.g., height and circumference) to the second storage tank 36. In a second embodiment, the first storage tank 14 may be smaller in size, volume, and dimensions as compared to the second storage tank 36, having a height and volume that are 20-30% smaller than that of the second storage tank 36, for example. In accordance with the present invention, as the height of the fluid is increased in the second tank 36 wherein the fluid from the first tank is being transferred, a substantial head is created, of which the present fuel or hydrocarbon transfer pump assembly 16 readily overcomes during operation.

[0044] In a first exemplary situation, the height h2 of the bulk fluid 334 in the second bulk fluid storage tank 36, having identical fluid as in the first bulk fluid storage tank 14, is twenty feet greater than the height h1, [x], of the bulk fluid in the first bulk fluid storage tank 14, that is the height of the bulk fluid 330, that is h2=[x+20]. In a second exemplary situation, the height h2 of the bulk fluid 334 in the second bulk fluid storage tank 36, having identical fluid as in the first bulk fluid storage tank 14, is thirty feet greater than the height of the bulk fluid in the first bulk fluid storage tank 14, that is h2=[x+30]. In a third exemplary situation, the height of the bulk fluid in the second bulk fluid storage tank 36, having identical fluid as in the first bulk fluid storage tank 14, is thirty-five feet greater than the height of the bulk fluid in the first bulk fluid storage tank 14, that is h2=[x+35]. In a fourth exemplary situation, the height of the bulk fluid in the second bulk fluid storage tank 36, having identical fluid as in the first bulk fluid storage tank 14, is greater than the height of the bulk fluid in the first bulk fluid storage tank 14, that is h2=y[x], wherein y is a multiple of the height x of the first bulk fluid storage tank 14. Accordingly, because of the difference in heights, the potential energy of the second bulk fluid storage tank can range in certain embodiments from 10-40 times that of the first bulk fluid storage tank, whereby the pumping assembly 16 is robust enough to overcome the head created by such a difference in potential energy, while still pumping rapidly at anywhere from 100-250 gallons per minute, for example.

[0045] In each situation, the present fluid transfer system 300 results in superior transfer rates as compared to other fluid transfer systems known in the art, such as diesel-powered PTO-driven pumps. It is believed that as the potential energy of the receiving tank (e.g., the second bulk fluid storage tank 36) increases, the pumping capacity of the present fluid transfer system 300 actually increases. Unexpectedly, the present fluid transfer system 300 and the hydrocarbon transfer pump assembly 16 are able and adapted to transfer 13000 to 15000 gallons of hydrocarbons or fuel per hour using an air motor-actuated rotary positive displacement pump, or up to 250 gallons per minute.

[0046] In contrast to known diesel-powered transfer pumps that are able to pump similar volumes per minute, when using air-driven pump assemblies 16 of the present invention, there are little or no volatile organic compounds (VOC) or fuel or hydrocarbon vapor emissions escaping into the surrounding atmosphere within the berm. It is well-recognized that the industry is moving away from diesel-powered pumps or other hydrocarbon-fueled pumps that contribute to substantial environmental concerns, particularly within the berm containing one or more bulk fluid storage tanks.

[0047] In yet another aspect of the present invention, the air-driven pump assembly 16 of the present invention may be easily throttled back to reduce the pumping capacity to thereby limit the amount of air that is drawn through the discharge pipe 28 as the level of bulk fluid is reduced in the bulk fluid storage tank being evacuated. By readily reducing the compressed air being supplied to the air motor, by valving for example, the present fluid transfer system 300 reduces the pumping capacity, and the consequential pump cavitation typically caused by suction of air as the level in the storage tank is reduced. In contrast, typical diesel-powered PTO pumps for example oftentimes are designed to run at non-variable and continuous speeds or revolutions per minute (rpms) (such as 540 or 1000 rpms), whereby mitigating the amount of air drawn into the pump as the tank level is reduced, becomes more challenging. Stated another way, the air-driven pump assembly 16 may be characterized as having an adjustable speed, by manual or automatic valves that attenuate or enlarge the air pressure coming from the air compressor to the air motor, for example.

[0048] It should further be understood that the preceding is merely a detailed description of various embodiments of this invention and that numerous changes to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the scope of the invention. The preceding description, therefore, is not meant to limit the scope of the invention. Rather, the scope of the invention is to be determined only by the appended claims and their equivalents.