Produced liquids compressor cooler

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of the filing of U.S. Provisional Patent Application Ser. No. 61/895,356, entitled “Produced Liquids Compressor Cooler”, filed on Oct. 24, 2013, and the specification thereof is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention (Technical Field)

Embodiments of the present invention relate to a system, method, and apparatus for cooling compressed gases at a well site without the use of fans.

Description of Related Art

Compressors at well sites require cooling between various stages of compression and after passing through the compressor so as to avoid excessive temperatures which can damage the compressor and any down-stream components. Such cooling is typically achieved via air-cooling with large fans. Because such fans are often quite large and must move a significant volume of air to achieve the desired effect, they produce a large amount of noise. Further, these mechanical fans are prone to failure and require ongoing maintenance to ensure that they are functioning properly. The excessive noise generated by such large fans often inhibits their use near homes and businesses.

In addition, because fans rely on ambient air temperature, which is non-controllable, their use, particularly during periods of cold weather, can cause the formation of liquids from condensation within the compressed gases.

There is thus a present need for a method, system, and apparatus which cool compressed gases at a well site while avoiding the many draw-backs of air-cooling.

Objects, advantages novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention.

BRIEF SUMMARY OF EMBODIMENTS OF THE PRESENT INVENTION

An embodiment of the present invention relates to a cooling apparatus having at least one heat exchanger disposed within a cooling vessel, the cooling vessel configured to receive a flow of liquid produced by a hydrocarbon-producing well such that heat is passed from the heat exchanger to the liquid, an outlet of a suction scrubber communicably coupled to an inlet of at least one stage of a compressor, a valve positioned to selectively cause at least a portion of a flow of compressed gas to bypass at least one of the heat exchangers, a temperature sensor positioned downstream of the valve; and the temperature sensor and the valve configured such that the valve is activated in response to an output of the temperature sensor.

In one embodiment, the heat exchanger has an inlet that is communicably coupled to an outlet of at least one stage of the compressor. The flow of liquid can be a flow of liquids that includes hydrocarbons and/or hydrocarbons and salt water. In addition, communicable couplings can be provided which connect to a condensation outlet of the suction scrubber such that liquid removed by the suction scrubber is passed to a vapor recovery system.

At least one of the one or more heat exchangers is communicably coupled to an outlet of a first stage of the compressor and the valve is positioned to bypass the heat exchanger that is communicably coupled to the outlet of the first stage of the compressor and the temperature sensor is positioned to detect a temperature of the compressed gas before it enters a second stage of the compressor.

Optionally, at least one of the one or more heat exchangers can be communicably coupled to an outlet of a final stage of the compressor and the valve can be positioned to selectively cause at least a portion of the flow of gas to bypass the heat exchanger that is communicably coupled to the outlet of a final stage of the compressor. The cooling vessel can include a water outlet and the outlet can include a weir system, a float-activated valve, a continuously flowing drain arranged on a lower portion of the cooling vessel, combinations thereof, and the like.

Optionally, an inner chamber can be disposed in the cooling vessel, a final stage of heat exchangers can be disposed in the inner chamber, and an inlet of the cooling vessel can be positioned such that flow of liquid first passes the final stage before then exiting the inner chamber and passing to remaining heat exchangers. An outlet of a subsequent stage of the compressor can be communicably connected to the first stage of the compressor so as to ensure a constant positive pressure to an inlet of the first stage of the compressor.

An embodiment of the present invention also relates to a cooling method which includes directing a flow of liquid from a hydrocarbon-producing well through a cooling vessel in which at least one heat exchanger is disposed, directing gas exiting a first stage of a compressor through a first of the at least one heat exchangers such that heat from the gas is absorbed by the liquid, configuring a first valve to at least partially bypass the first heat exchanger in response to a first sensed temperature of the gas, the first sensed temperature comprising a temperature of the gas prior to it entering a second stage of the compressor, and directing gas from the first heat exchanger to a suction scrubber prior to directing the gas into the second stage of the compressor.

A second of the at least one heat exchangers disposed within the cooling vessel, the second heat exchanger having an inlet communicably coupled to an outlet of the second stage of the compressor, a second valve configured to at least partially bypass the second heat exchanger in response to a second sensed temperature of the gas, the second sensed temperature of the gas comprising a temperature of the gas downstream of the second valve. The method can also include directing condensation from an outlet of the suction scrubber to a vapor recovery system, and/or drawing water from a lower portion of the cooling vessel.

The method can also include directing the flow of liquid past a final one of the one or more heat exchangers and then past others of the one or more heat exchangers. The method can also optionally include connecting an outlet of a subsequent stage of the compressor to an inlet of the first stage of the compressor such that a constant positive pressure is maintained at the inlet of the first stage of the compressor.

An embodiment of the present invention also relates to a cooling system that includes a cooling apparatus having at least one heat exchanger disposed within a cooling vessel, the cooling vessel configured to receive a flow of liquid that is produced by a hydrocarbon-producing well such that heat is passed from the at least one heat exchanger to the liquid, an outlet of a suction scrubber communicably coupled to an inlet of at least one stage of a compressor, a valve positioned to selectively cause at least a portion of a compressed gas to bypass at least one of the heat exchangers, a temperature sensor positioned downstream of the valve; and the temperature sensor and the valve configured such that the valve is activated in response to an output of the temperature sensor. The system further includes the steps of directing a flow of liquid from the hydrocarbon-producing well through the cooling vessel in which the at least one heat exchanger is disposed, directing gas exiting a first stage of a compressor through a first of the one or more heat exchangers such that heat from the gas is absorbed by the liquid, configuring a first valve to at least partially bypass the first of the at least one heat exchangers in response to a first sensed temperature of the gas, the first sensed temperature comprising a temperature of the gas prior to entering a second stage of the compressor, and directing the gas through a suction scrubber before passing it to at least one of the stages of the compressor.

Objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a part of the specification, illustrate an embodiment of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating one or more preferred embodiments of the invention and are not to be construed as limiting the invention. In the drawings:

FIG. 1 is a flow diagram illustrating an embodiment of the present invention;

FIG. 2 is a flow diagram illustrating an embodiment of the present invention wherein incoming liquids first pass a final heat exchanger; and

FIG. 3 is a flow diagram illustrating an embodiment of the present invention wherein the cooling vessel comprises a water outlet.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention are directed to a method, system, and apparatus for cooling a compressed gas at a well site without relying on air cooling.

Referring now to the drawings, FIG. 1 is a flow diagram which illustrates a produced liquids compressor cooler connected to a three-stage compressor according to an embodiment of the present invention. In the drawing, for convenience, reference number 10 is used to identify the cooler. However, it is to be understood that one or more of the components contained in the drawing (including but not limited to the first stage suction scrubber and the 3-stage compressor) can already be provided and thus need not be provided in order to achieve a cooling effect. Further, a two-stage compressor configuration can also be provided by removing the second stage of compression in the drawing and the accompanying heat exchanger.

In one embodiment, cooler 10 preferably comprises first heat exchanger 12, second heat exchanger 14, and third heat exchanger 16 disposed in cooling vessel 18. Vessel 18 is preferably connected to receive liquid from a production unit and pass liquid to down-stream equipment, such as an existing vapor recovery unit. Thus, in operation, vessel 18 is filled with produced liquids, which act as a heat sink for compressed gases which travel through the heat exchangers. The liquids which are thus heated from their interaction with the heat exchangers then continue flowing on to down-stream equipment. The fluid within vessel 18 is thus continuously being replaced with a fresh supply of liquids to act as a continuous heat sink.

In one embodiment, each of heat exchangers 12, 14, and 16 are connected to a respective control valve 20, 22, and 24. In this embodiment, control valves are the only moving components. In this embodiment, control valves 20, 22, and 24 are preferably 3-way temperature control valves which permit the respective heat exchanger to be at least partially bypassed if the temperature at the location of a corresponding temperature sensor is below a predetermined amount. Thus, the control valves and temperature sensors work to maintain an at least substantially constant temperature at a predetermined set point. In this embodiment, temperature sensor 26, which is used in controlling control valve 20 is preferably disposed just prior to or at an inlet of the second stage of the compressor. Temperature sensor 28, which is used in controlling control valve 22 is preferably disposed prior to or at the inlet of a third stage of compression. Temperature sensor 30, which is used in controlling control valve 24 is preferably disposed downstream of control valve 24.

In one embodiment, pressure regulator 32 is preferably provided between an outlet of third stage of compression and an inlet of the first stage of compression to ensure a minimum constant pressure to the inlet of the first stage of compression.

In one embodiment, second stage suction scrubber 34 is preferably connected to an inlet of the second stage of the compressor. In addition, third stage suction scrubber 36 is preferably connected to an inlet of the third stage of the compressor. In this embodiment, compressed gases from the first stage of the compressor enter into second stage suction scrubber 34 without passing through heat exchanger 12 if the temperature of gases passing temperature sensor 26 are less than a predetermined amount. If, however, the temperature of gases passing temperature sensor 26 are at or above a predetermined amount, then gases which exit the first stage of the compressor pass through heat exchanger 12 before entering second stage suction scrubber 34 before then entering the second stage of the compressor. Likewise, compressed gases from the second stage of the compressor enter into third stage suction scrubber 36 without passing through heat exchanger 14 if the temperature of gases passing temperature sensor 28 are less than a predetermined amount. If, however, the temperature of gases passing temperature sensor 28 are at or above a predetermined amount, then gases which exit the second stage of the compressor pass through heat exchanger 14 before entering third stage suction scrubber 36 before then entering the third stage of the compressor. Optionally, temperature sensors 26 and 28 can be disposed before or after each of respective suction scrubbers 34 and 36. In one embodiment, the outlet of every stage of the compressor comprises a heat exchanger connected to it. Optionally, however, all except the final stage of the compressor comprises a heat exchanger connected to it. Thus for embodiments wherein a two stage compressor is used, there can be used one or two heat exchangers. For embodiments wherein a three stage compressor is used, there can be used two or three heat exchangers. For embodiments having more than three stages of compression, the number of heat exchangers used can be equal to the number of stages of compression or the number of heat exchangers used can be one less than the number of stages of compression.

As best illustrated in FIG. 2, in one embodiment, cooling vessel 18 can comprise inner chamber formed by divider 40. Although numerous configurations of divider 40 can be used and will provide desirable results, divider 40 is preferably configured such that incoming liquids are first caused to pass a final heat exchanger, before exiting the inner chamber formed by divider 40 and thus coming into contact with the other heat exchangers. This configuration thus permits the coolest liquids which enter cooling vessel 18 to first interact with the final heat exchanger before being further heated by the remaining heating coils, thus resulting in the greatest cooling effect being provided to the final heat exchanger.

As best illustrated in FIG. 3, in one embodiment, cooling vessel 18 preferably comprises a water outlet. Although numerous apparatuses, methods, and systems can be used to remove water from below oil in cooling vessel 18, including but not limited to a weir system, a float valve is preferably provided which dumps water from vessel 18. In an alternative embodiment, a quantity of liquid can be continuously removed from the bottom of cooling vessel 18 to ensure that the vessel does not gradually become filled with saltwater.

Embodiments of the present invention preferably keep the discharge temperature of the compressed gases above the dew point of the gases at the compressed pressure. If the temperature of the compressed gases is below the dew point of the gases, liquid hydrocarbons that are in a vapor state at the suction pressure of a compressor stage will begin to condense. Condensation of liquid hydrocarbons in the compressed gas can potentially damage the compressor as well as creating high vapor liquids which will flash when dumped by the scrubbers to a lower pressure. If a vapor recovery system is being used, downstream of the present invention, the flash vapors will again be recovered by the vapor recovery system, thus creating recycle loops that can overload the vapor recovery system.

Although the invention has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above and/or in the attachments, and of the corresponding application(s), are hereby incorporated by reference.