阅读说明：本技术 双泵筒管式泵接替生产管柱及不动管柱检泵的工艺 (Process for replacing production string with double-pump-barrel tubular pump and detecting pump without moving string ) 是由 谢文献 郭立谦 苏庆欣 袁杰 崔洁 孙喆 蒲浩 吕凤梅 许建华 孙雯 于 2019-03-25 设计创作，主要内容包括：本发明公开了双泵筒管式泵接替生产管柱及不动管柱检泵的工艺,包括上泵筒和下泵筒,两泵筒中间安装有可投式固定阀阀座,下泵筒底部安装有固定阀,下泵筒采油时,抽油杆连接下柱塞下入下泵筒中,可投式固定阀不下入,上泵筒仅是下泵的排油通道；检泵时,提出抽油杆及下柱塞,下入抽油杆与上柱塞及可投式固定阀,下到位后使上柱塞与可投式固定阀脱开,更换上泵筒生产,此时下泵筒及固定阀不参与工作,仅是上泵的进油通道。实现了管式泵不动管柱,只是提出抽油杆即可换泵接替生产,保护油管丝扣不受作业损伤,降低作业强度,延长管式泵生产管柱工作寿命。(The invention discloses a process for replacing a production string with a double-pump barrel pipe type pump and detecting the pump without moving the string, which comprises an upper pump barrel and a lower pump barrel, wherein a throwing type fixed valve seat is arranged between the two pump barrels, a fixed valve is arranged at the bottom of the lower pump barrel, when the lower pump barrel is used for oil extraction, a sucker rod is connected with a lower plunger and is put into the lower pump barrel, the throwing type fixed valve is not put into the lower pump barrel, and the upper pump barrel is only an oil discharge channel of the lower pump; when the pump is checked, the pumping rod and the lower plunger are lifted, the pumping rod, the upper plunger and the throw-type fixed valve are put in, the upper plunger and the throw-type fixed valve are separated after the pumping rod, the upper pump cylinder is replaced for production, and the lower pump cylinder and the fixed valve do not participate in the work and are only an oil inlet channel of the upper pump. Realized the motionless tubular column of tubular pump, only proposed the sucker rod and can change the pump and take over production promptly, the protection oil pipe screw thread does not receive the operation damage, reduces operation intensity, extension tubular pump production tubular column working life.)

1. The double-pump-barrel tubular pump replacing production string comprises an oil pipe, an upper pump barrel and a lower pump barrel, wherein the upper end of the upper pump barrel is connected with the oil pipe.

2. The dual pump spool tubular pump take-over production string of claim 1, wherein the lower pump spool lower port mounts a standing valve.

3. The dual pump spool tubular pump take-over production string of claim 1, wherein when the outer diameter of the lower plunger in the lower pump barrel is greater than the inner diameter of the valve seat of the drop-in standing valve, the upper end of the lower plunger is connected to the lower end of the sucker rod through a disconnect coupling; when the outer diameter of a lower plunger in the lower pump barrel is smaller than the inner diameter of a valve seat of the drop-type fixed valve, the upper end of the lower plunger is directly connected with the lower end of the sucker rod in a screw thread mode or welded.

4. The dual-pump spool tube type pump take-over production string as claimed in claim 1, wherein the throwing type fixed valve can be mounted on the throwing type fixed valve seat, the upper end of the throwing type fixed valve is connected with the lower end of the upper plunger in the upper pump barrel through a disconnecting device, and the upper end of the upper plunger is connected with the sucker rod.

5. A dual barrel tubing pump take-over production string as claimed in claim 3 or claim 4 wherein the disconnect comprises a screw and a threaded sleeve of mating threaded connection, disconnected and connected by relative rotation.

6. A dual barrel tubing pump take-over production string as claimed in claim 1 or 2 or 3 or 4 wherein the inner diameter of the seat of the flushable standing valve is smaller than the inner diameter of the upper barrel which is smaller than the inner diameter of the tubing.

7. The double-pump-barrel tubing pump take-over production string of claim 1, 2, 3 or 4, wherein when the pump barrel is needed for oil production, the sucker rod is connected with the lower plunger and is put into the lower pump barrel, the throw-able fixed valve is not put in, the lower plunger moves up and down along with the sucker rod, and the upper pump barrel does not participate in the work at the moment and is only an oil discharge channel of the lower pump; when the lower pump barrel is used for oil extraction, a centralizer matched with the upper pump barrel is arranged on the sucker rod, so that eccentric wear of the sucker rod on other parts is avoided; when the lower pump barrel is lost and a pump needs to be checked, the pumping rod and the lower plunger are lifted, then the pumping rod and the upper plunger are connected, the lower part of the upper plunger is connected with the throw-type fixed valve, and after the lower plunger descends to the throw-type fixed valve seat, the throw-type fixed valve and the throw-type fixed valve seat are sealed; the plunger on the rotary lifting sucker rod is separated from the throw-type fixed valve, so that the pump replacement production is realized; when the upper pump barrel is needed for oil extraction, the sucker rod is connected with the upper plunger to move up and down in the upper pump barrel, the upper pump barrel and the throw-type fixed valve participate in working, and the lower pump barrel and the fixed valve do not participate in working at the moment and are only oil inlet channels of the upper pump.

8. The process method for detecting the pump by using the double-pump barrel tubular pump to replace the fixed tubular column of the production tubular column is characterized by comprising the following steps of:

the method comprises the following steps: when the lower pump barrel is needed for oil extraction, a production string consisting of the upper pump barrel, the throw-able fixed valve seat, the lower pump barrel and the fixed valve is lowered to a designed pump depth position, the sucker rod is connected with the lower plunger and is lowered into the lower pump barrel, the throw-able fixed valve is not lowered, the lower plunger moves up and down at the moment, the upper pump barrel does not participate in the work at the moment, and only is an oil discharge channel of the lower pump;

step two: when the lower pump barrel is lost and a pump needs to be checked, the sucker rod and the lower plunger or the sucker rod and the upper part of the disjointing device are lifted, then the sucker rod and the upper plunger are connected, the lower part of the upper plunger is connected with the throw-type fixed valve, and after the lower part of the upper plunger reaches the position of the throw-type fixed valve, the throw-type fixed valve and the valve seat are sealed; the plunger on the rotary lifting sucker rod is separated from the throw-type fixed valve, so that the pump replacement production is realized;

step three: when the upper pump barrel is needed for oil extraction, the sucker rod is connected with the upper plunger to move up and down in the upper pump barrel, the upper pump barrel and the throwing type fixed valve participate in work, at the moment, the lower pump barrel does not participate in work, and only is an oil inlet channel of the upper pump.

9. The process of claim 8, wherein the sucker rod is provided with a centralizer cooperating with the upper pump barrel to prevent eccentric wear of the upper pump barrel and the seat of the retractable standing valve with the sucker rod.

Technical Field

The invention relates to the field of oil extraction production and operation in oil fields, in particular to a process for replacing a production string with a double-pump bobbin type pump and detecting the pump without moving the string.

Background

The existing tubular pump often has pump leakage in the oil production process, and needs to be checked. The conventional pump detection operation method is to put the sucker rod out first and then put the pipe column out, which wastes time and labor and has high operation cost. The special pump detection operation method is that when the tubular pump adopts the salvageable fixed valve, the fixed valve is salvaged by using the sucker rod, the plunger and the salvageable fixed valve are replaced to complete the pump detection, and the pump barrel is not replaced. If the pump barrel is damaged due to eccentric wear corrosion, the tubing string and the pump barrel still need to be pulled out.

Along with oil pipe's technical progress, current inside lining oil pipe life-span prolongs greatly, because of the pump leak cause examine the pump cycle far away be less than inside lining oil pipe's life-span, move the tubular column and examine the pump operation at every turn and all can cause the damage of certain degree to inside lining oil pipe screw thread, reduce inside lining pipe life.

Application No.: 201320315761.7 discloses a fixed valve assembly of a tubular pump, which comprises a fixed valve cover, a fixed valve joint and a valve ball, wherein the fixed valve cover is in threaded connection with the fixed valve joint, the upper end surface of the fixed valve cover is provided with an oil-gas channel, and the upper end of the fixed valve joint is provided with a valve seat; the valve ball is arranged in a cavity formed by the fixed valve cover and the fixed valve joint. The beneficial effects of the utility model are that with the integration of disk seat and solid fixed valve joint, change the seal structure of original solid fixed valve assembly, solve solid fixed valve joint up end and easily puncture and influence sealed problem, reduce the oil well operation, practice thrift the operating cost.

Application No.: 201020218986.7 discloses a double-stage pump barrel and double-stage plunger combined pump barrel tubing pump, which is a device in oil well production, overcomes the defects of other devices, and is formed by connecting an upper double-stage pump barrel, a lower double-stage pump barrel, an upper double-stage plunger and a lower double-stage plunger.

Application No.: 200420038916.8A high-efficiency oil-well tubing pump with double pump barrels is provided, which belongs to an oil-well pumping device of oil field, and comprises a large pump barrel, a small pump barrel connected with the upper part of the large pump barrel, a large pump plunger in the large pump barrel, a small pump plunger in the small pump barrel, two plungers connected together through a connecting rod, a traveling valve on the upper and lower parts of the large pump plunger, a driven valve on the upper and lower parts of the small pump plunger, a pull rod on the upper end of the small pump plunger, a fixed valve seat fixed on the bottom of the large pump barrel, and a fixed valve oil on the fixed valve seat, wherein when the pumping rod is used, the down resistance is greatly reduced, the pumping efficiency is obviously improved, the pumping rod is always pulled, the probability of fatigue damage is reduced, when in stroke, the liquid column pressure is exerted on the driven valve, the hydraulic impact of liquid on the fixed valve is reduced, the probability of damage to the fixed valve is also greatly reduced, thereby the maintenance cycle of the oil-well pump is prolonged, the eccentric wear between the well bore and the sucker rod is also reduced.

Application No.: 201621456646.1A modified oil-well tubing pump comprises an oil-well tubing pump matched with a pump barrel and a salvageable fixed valve connected with the pump barrel through a disconnecting device, wherein the pump barrel is connected with an oil pipe, a sealing surface of a baffle platform arranged on the salvageable fixed valve is matched with a sealing surface of a boss on the inner wall of the pump barrel, flexible sealing devices are arranged in sealing ring grooves uniformly distributed on a plunger of the oil-well tubing pump in a matched manner, and the plunger of the oil-well tubing pump is matched with the pump barrel through the flexible sealing devices. The oil well pump maintenance device is reasonable in structure and reliable in performance, the oil well pump can be maintained only by lifting the sucker rod string without lifting the oil pipe string, the operation intensity of a pump to be detected is reduced, the friction condition of the plunger and the pump cylinder is improved, the leakage is reduced, the pump efficiency is improved, and the service life is prolonged. Although the technology discloses a disconnecting device and a salvageable fixed valve, the pump barrel cannot be replaced without moving the pipe column, and the pump can be detected only by moving the pipe column when the pump barrel is damaged and leaked.

The technical solutions of the above-disclosed technologies, the technical problems to be solved, and the advantageous effects thereof are all different from the present invention, and no technical inspiration exists in the above-disclosed technical documents for more technical features, technical problems to be solved, and advantageous effects thereof.

Disclosure of Invention

The invention aims to provide a process for replacing a production string with a double-pump-barrel tubular pump and detecting the pump without moving the string, and the pump detection operation can be realized only by extracting a sucker rod without extracting an oil pipe, so that the operation intensity is reduced, and the service life of the production string is prolonged.

In order to achieve the purpose, the invention adopts the following technical scheme that the double-pump bobbin type pump take-over production string comprises an oil pipe, an upper pump barrel and a lower pump barrel, wherein the upper end of the upper pump barrel is connected with the oil pipe, the double-pump bobbin type pump take-over production string also comprises a throwing type fixed valve seat, the lower end of the upper pump barrel is connected with the upper end of the throwing type fixed valve seat, and the upper end of the lower pump barrel is connected with the lower end of the throwing type fixed valve seat.

And a fixed valve is arranged at the lower port of the lower pump barrel.

When the outer diameter of a lower plunger in the lower pump barrel is larger than the inner diameter of the valve seat of the drop-type fixed valve, the upper end of the lower plunger is connected with the lower end of the sucker rod through a disconnecting connector; when the outer diameter of a lower plunger in the lower pump barrel is smaller than the inner diameter of a valve seat of the drop-type fixed valve, the upper end of the lower plunger is directly connected with the lower end of the sucker rod in a screw thread mode or welded.

The throwing type fixed valve can be installed on the throwing type fixed valve seat, the upper end of the throwing type fixed valve is connected with the lower end of an upper plunger in the upper pump barrel through a disconnecting device, and the upper end of the upper plunger is connected with a sucker rod.

The disconnecting device comprises a screw rod and a screw sleeve which are matched with each other and are in thread-type connection, and the disconnecting device is disconnected and connected through relative rotation.

The inner diameter of the valve seat of the throwing type fixed valve is smaller than the inner diameter of the upper pump cylinder, and the inner diameter of the upper pump cylinder is smaller than the inner diameter of the oil pipe.

When the lower pump barrel is needed for oil extraction, the sucker rod is connected with the lower plunger and is put into the lower pump barrel, the throw-type fixed valve is not put in, the lower plunger moves up and down along with the sucker rod, and the upper pump barrel does not participate in the work at the moment and is only an oil discharge channel of the lower pump; when the lower pump barrel is used for oil extraction, a centralizer matched with the upper pump barrel is arranged on the sucker rod, so that eccentric wear of the sucker rod on other parts is avoided; when the lower pump barrel is lost and a pump needs to be checked, the pumping rod and the lower plunger are lifted, then the pumping rod and the upper plunger are connected, the lower part of the upper plunger is connected with the throw-type fixed valve, and after the lower plunger descends to the throw-type fixed valve seat, the throw-type fixed valve and the throw-type fixed valve seat are sealed; the plunger on the rotary lifting sucker rod is separated from the throw-type fixed valve, so that the pump replacement production is realized; when the upper pump barrel is needed for oil extraction, the sucker rod is connected with the upper plunger to move up and down in the upper pump barrel, the upper pump barrel and the throw-type fixed valve participate in working, and the lower pump barrel and the fixed valve do not participate in working at the moment and are only oil inlet channels of the upper pump.

In order to achieve the purpose, the invention adopts the following technical scheme that the process method of the double-pump bobbin type pump replacing the immobile pipe column pump detection of the production pipe column comprises the following steps:

the method comprises the following steps: when the lower pump barrel is needed for oil extraction, a production string consisting of the upper pump barrel, the throw-able fixed valve seat, the lower pump barrel and the fixed valve is lowered to a designed pump depth position, the sucker rod is connected with the lower plunger and is lowered into the lower pump barrel, the throw-able fixed valve is not lowered, the lower plunger moves up and down at the moment, the upper pump barrel does not participate in the work at the moment, and only is an oil discharge channel of the lower pump;

step two: when the lower pump barrel is lost and a pump needs to be checked, the sucker rod and the lower plunger or the sucker rod and the upper part of the disjointing device are lifted, then the sucker rod and the upper plunger are connected, the lower part of the upper plunger is connected with the throw-type fixed valve, and after the lower part of the upper plunger reaches the position of the throw-type fixed valve, the throw-type fixed valve and the valve seat are sealed; the plunger on the rotary lifting sucker rod is separated from the throw-type fixed valve, so that the pump replacement production is realized;

step three: when the upper pump barrel is needed for oil extraction, the sucker rod is connected with the upper plunger to move up and down in the upper pump barrel, the upper pump barrel and the throwing type fixed valve participate in work, at the moment, the lower pump barrel does not participate in work, and only is an oil inlet channel of the upper pump.

When the lower pump barrel is used for oil extraction, the centralizer matched with the upper pump barrel is arranged on the sucker rod, so that eccentric wear of the upper pump barrel, the throw-type fixed valve seat and the sucker rod is avoided.

Compared with the prior art, the invention has the following beneficial effects:

the inner diameter matching of the upper pump cylinder and the lower pump cylinder is divided into two conditions: one is that the inner diameter of the lower pump cylinder is smaller than the drift diameter of the throw-type fixed valve seat, the lower plunger piston can smoothly pass through the upper pump cylinder and the throw-type fixed valve seat, and the lower plunger piston is directly connected with the sucker rod; and in the other case, the inner diameter of the lower pump barrel is larger than or equal to the drift diameter of the throw-type fixed valve seat, and the lower plunger is butted with the sucker rod by adopting a disconnecting connector. The upper part of the disconnecting device is arranged at the lower end of the sucker rod, and the lower part of the disconnecting device connected with the upper end of the lower plunger reserved in the lower pump cylinder is butted after passing through the upper pump cylinder and the valve seat of the throw-type fixed valve, so that the lower pump plunger is driven to move up and down.

When the lower pump barrel is used for oil extraction, the sucker rod is connected with the lower plunger and is put into the lower pump barrel, the throw-type fixed valve is not put into the lower pump barrel, and the upper pump barrel is only an oil discharge channel of the lower pump; when the pump is checked, the pumping rod and the lower plunger are lifted, the pumping rod, the upper plunger and the throw-type fixed valve are put in, the upper plunger and the throw-type fixed valve are separated after the pumping rod, the upper pump cylinder is replaced for production, and the lower pump cylinder and the fixed valve do not participate in the work and are only an oil inlet channel of the upper pump. The invention realizes that the tubing pump can be replaced by the replaceable pump for production without pulling out the sucker rod, protects the oil pipe screw thread from being damaged by operation, reduces the operation intensity and prolongs the service life of the tubing pump production tubing string.

Drawings

FIG. 1 is a schematic sectional view of the lower pump barrel of the present invention.

Fig. 2 is a schematic sectional structure view of the upper pump cylinder in operation.

The labels in the figure are: the device comprises a sucker rod 1, an oil pipe 2, an upper pump barrel 3, a throw-able fixed valve seat 4, a lower plunger 5, a lower pump barrel 6, a fixed valve 7, an upper plunger 8 and a throw-able fixed valve 9.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1 to 2, the present invention provides a technical solution:

a double-pump-barrel tubular pump replacing production string comprises an oil pipe 2, an upper pump barrel 3 and a lower pump barrel 6, wherein the upper end of the upper pump barrel is connected with the oil pipe, the double-pump-barrel tubular pump replacing production string further comprises a throwing type fixed valve seat 4, the lower end of the upper pump barrel is connected with the upper end of the throwing type fixed valve seat, and the upper end of the lower pump barrel is connected with the lower end of the throwing type fixed valve seat.

And a fixed valve 7 is arranged at the lower port of the lower pump barrel.

When the outer diameter of a lower plunger 5 in the lower pump barrel is larger than the inner diameter of a valve seat of the drop-type fixed valve, the upper end of the lower plunger is connected with the lower end of the sucker rod 1 through a disconnecting connector; when the outer diameter of a lower plunger in the lower pump barrel is smaller than the inner diameter of a valve seat of the drop-type fixed valve, the upper end of the lower plunger is directly connected with the lower end of the sucker rod in a screw thread mode or welded.

The throwing type fixed valve 9 can be installed on the throwing type fixed valve seat, the upper end of the throwing type fixed valve is connected with the lower end of an upper plunger 8 in the upper pump barrel through a disconnecting device, and the upper end of the upper plunger is connected with the sucker rod 1.

The disconnecting device comprises a screw rod and a screw sleeve which are matched with each other and are in thread-type connection, and the disconnecting device is disconnected and connected through relative rotation. The connecting-disconnecting device acting on the upper end of the lower plunger can adopt a mode that a screw sleeve is arranged at the lower end of the sucker rod, and a screw rod is arranged at the upper end of the lower plunger. The disconnecting and connecting device acting on the lower end of the upper plunger piston can adopt a mode that a screw sleeve is fixed at the lower end of the upper plunger piston and a screw rod is fixed at the upper end of a throwing type fixed valve. Of course, other types of disconnectors commonly used in the art may be used as the disconnector.

The inner diameter of the valve seat of the throwing type fixed valve is smaller than the inner diameter of the upper pump cylinder, and the inner diameter of the upper pump cylinder is smaller than the inner diameter of the oil pipe.

The interconnection of all components in the present invention is conventional in the art, such as threaded connections, welding, unibody construction, and the like.

As shown in fig. 1 and 2, the upper pump cylinder 3 and the lower pump cylinder 6 are provided with a throwing type fixed valve seat 4 in the middle, a fixed valve 7 is arranged at the bottom of the lower pump cylinder 6, and the lower pump cylinder further comprises an upper plunger 8 matched with the upper pump cylinder 3 and a lower plunger 5 matched with the lower pump cylinder 6. The upper part of the throw-type fixed valve 9 and the lower part of the upper plunger 8 are provided with disconnecting devices to realize disconnection and butt joint. The upper pump barrel 3 is connected with an oil pipe 2, the outer diameter of the upper pump barrel 3 is smaller than the drift diameter of the oil pipe 2, and the outer diameter of the throwing type fixed valve 9 is smaller than the inner diameter of the upper pump barrel 3.

The double-pump barrel type pump replaces the immobile pipe column pump detecting process method of the production pipe column, and comprises the following steps:

1. the oil extraction state of the lower pump barrel is as follows: the double-pump-barrel tubular pump replaces an upper pump barrel 3, a throwing type fixed valve seat 4, a lower pump barrel 6 and a fixed valve 7 of a production pipe column to a designed pump depth position, a sucker rod 1 is connected with a lower plunger 5 and is put into the lower pump barrel 6 to move up and down, the throwing type fixed valve 9 is not put in, the upper pump barrel 3 does not participate in the work at the moment, and only is an oil discharge channel of the lower pump; the centralizer matched with the upper pump barrel 3 can be arranged on the sucker rod 1, so that eccentric wear of the upper pump barrel 3 and the throw-type fixed valve seat 4 and the sucker rod 1 is avoided.

2. When the lower pump barrel 6 is lost and a pump needs to be checked, the sucker rod 1 and the lower plunger 5 are lifted, then the sucker rod 1 and the upper plunger 8 are connected, the lower part of the upper plunger 8 is connected with the throw-type fixed valve 9, and after the lower part of the upper plunger 8 reaches the position of the throw-type fixed valve seat 4, the throw-type fixed valve 9 and the valve seat 4 are sealed. The upper plunger 8 of the rotary lifting sucker rod is separated from the fixed valve 9 which can be thrown, so that the pump replacement production is realized;

3. an oil extraction state of an upper pump barrel: the pumping rod 1 is connected with the upper plunger 8 and moves up and down in the upper pump cylinder 3, the upper pump cylinder 8 and the throw-type fixed valve 9 participate in work, and the lower pump cylinder 6 and the fixed valve 7 do not participate in work at the moment and are only oil inlet channels of the upper pump.

The inner diameter matching of the upper pump cylinder and the lower pump cylinder is divided into two conditions: one is that the inner diameter of the lower pump cylinder is smaller than the drift diameter of the throw-type fixed valve seat, the lower plunger piston can smoothly pass through the upper pump cylinder and the throw-type fixed valve seat, and the lower plunger piston is directly connected with the sucker rod; and in the other case, the inner diameter of the lower pump barrel is larger than or equal to the drift diameter of the throw-type fixed valve seat, and the lower plunger is butted with the sucker rod by adopting a disconnecting connector. The upper part of the disconnecting device is arranged at the lower end of the sucker rod, and the lower part of the disconnecting device connected with the upper end of the lower plunger reserved in the lower pump cylinder is butted after passing through the upper pump cylinder and the valve seat of the throw-type fixed valve, so that the lower pump plunger is driven to move up and down.

When the lower pump barrel is used for oil extraction, the sucker rod is connected with the lower plunger and is put into the lower pump barrel, the throw-type fixed valve is not put into the lower pump barrel, and the upper pump barrel is only an oil discharge channel of the lower pump; when the pump is checked, the pumping rod and the lower plunger are lifted, the pumping rod, the upper plunger and the throw-type fixed valve are put in, the upper plunger and the throw-type fixed valve are separated after the pumping rod, the upper pump cylinder is replaced for production, and the lower pump cylinder and the fixed valve do not participate in the work and are only an oil inlet channel of the upper pump. Realized the motionless tubular column of tubular pump, only proposed the sucker rod and can change the pump and take over production promptly, the protection oil pipe screw thread does not receive the operation damage, reduces operation intensity, extension tubular pump production tubular column working life.

In the description of the present invention, it is to be understood that the positional indications or positional relationships are based on those shown in the drawings and are for the purpose of facilitating the description of the present invention, and are not intended to indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and are not to be construed as limiting the present invention.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.