Thermal control system

A thermal control system and method of using same are disclosed. Preferably, the thermal control system includes at least a combination data logger and control module interacting with a heat transfer medium circulation device, a heat transfer medium distribution system communicating with a heat transfer medium circulation device, and a service object interacting with a heat transfer distribution system, wherein the heat transfer medium distribution system facilitates heat transfer between the service object and a heat transfer medium confined within the heat transfer medium distribution system. Preferably, the thermal control system further includes a pair of motors each configured for driving the heat transfer medium circulation device, and a motor control and switching circuit responsive to a predetermined signal provided by the data logger and control module for selecting one of the pair of motors for use in driving the heat transfer medium circulation device.

FIELD OF THE INVENTION

This invention relates to new and useful improvements in thermal control systems. In particular, but not by way of limitation, to thermal control systems, which generates, controls, and utilizes its own source of energy for maintaining a desired temperature of a service item, such as an oil or gas well head, an output line associated with the well head, or a combination of both.

BACKGROUND

Freezing of wellhead equipment is a common risk for oil wells and gas wells in regions that experience extremely cold winters, such as Alaska, Colorado and northern Canada. Natural gas contains hydrates, which may condense out of the gas and then solidify when temperatures are very low, particularly when the situation is aggravated by a drop in gas pressure. Unless sufficient heat is provided, or unless other means are provided for preventing condensation of hydrates, the wellhead equipment installed on a producing well to control and regulate flow of oil or gas, as the case may be, can “freeze off” and cease to function when temperatures fall below freezing (i.e., zero degrees Celsius). When this happens, valuable production is lost, and additional expense must be incurred to have skilled technicians attend at the well site to remedy the freeze-off and restore flow from the well.

U.S. Pat. No. 6,032,732, issued to Yewell on Mar. 7, 2000, discloses a wellhead heating system that circulates heated coolant, from a liquid-cooled engine driving an oil well pumper, through insulated conduit arranged as desired in thermal contact with the wellhead equipment, such that heat from the circulating coolant is transferred to the equipment. The Yewell apparatus has a serious drawback, however, in that it is applicable only at well sites where a source of heated fluid is readily available, such as where a liquid-cooled engine has been provided for one reason or another.

Other approaches to the problem have included provision of heat tracing loops circulating hot water or steam from heaters or boilers, or direct injection of antifreeze fluids such as methanol. Once again, such approaches are excessively expensive if not entirely impractical for remote well sites, because of the cost and inconvenience of maintaining a reliable source of power or fuel for the heaters or boilers, or providing injection pumps and sufficient supplies of antifreeze fluids. In fact, well-operating companies may find it less costly overall to incur occasional production losses from wellhead freeze-off at remote well locations, plus the expense of sending technicians out to remedy freeze-off situations, than to provide means for keeping the remote wellheads warm, given the cost of providing heat sources (e.g., electric power, diesel generators, or propane heaters) or antifreeze injection equipment needed to prevent freeze-off.

For the foregoing reasons, there is a need in the oil and gas industry for improved apparatus and methods for preventing freezing of wellhead equipment associated with gas wells and oil wells. In particular, there is a need for such apparatus and methods that minimize or eliminate the need for antifreeze injection, or for supplementary power or fuel.

SUMMARY OF THE INVENTION

In accordance with preferred embodiments, a thermal control system and method of using same are provided. Preferably, the thermal control system includes at least a combination data logger and control module interacting with a heat transfer medium circulation device, a heat transfer medium distribution system communicating with a heat transfer medium circulation device, and a service object interacting with a heat transfer distribution system, wherein the heat transfer medium distribution system facilitates heat transfer between the service object and a heat transfer medium confined within the heat transfer medium distribution system. Preferably, the thermal control system further includes a pair of motors each configured for driving the heat transfer medium circulation device, and a motor control and switching circuit responsive to a predetermined signal provided by the data logger and control module for selecting one of the pair of motors for use in driving the heat transfer medium circulation device.

In an alternate preferred embodiment, the thermal control system is used by steps that include at least sensing a condition of a service object, determining a condition of a heat transfer medium, and activating a heat transfer medium circulation device when the sensed condition of the service object attains a predetermined condition. Preferably, the method of using the thermal control system further includes the steps of engaging a heat exchanger when the condition of the heat transfer medium attains a predetermined condition, disengaging an electric motor driving the heat transfer medium circulation device when a power source for the electric motor drops below a predetermined voltage level, and using a non-electric motor to drive the heat transfer medium circulation device when the electric motor driving a heat transfer medium circulation device is disengaged.

These and various other features and advantages that characterize the claimed invention will be apparent upon reading the following detailed description and upon review of the associated drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The use of “consisting of” and variations thereof herein is meant to encompass only the items listed thereafter. The use of letters to identify steps of a method or process is simply for identification and is not meant to indicate that the steps should be performed in a particular order. Other modifications and variations to the described embodiments are also contemplated within the scope and spirit of the invention.

Referring to the drawings,FIG. 1shows a preferred embodiment of an inventive thermal control system100that includes a data logger and control module102(also referred to herein as “controller102”) programmed with a code for tracking the operational events of the thermal control system100, and providing overall control of the thermal control system100. In a preferred environment, the data logger and control module102communicates with a plurality of ambient sensors104, which are used to collect the environmental conditions in which the thermal control system100is operating. The environmental conditions collected by the ambient sensors104include temperature readings, wind speed, the amount of ambient light present, and the angle of attack of the source of the ambient light.

Preferably the inventive thermal control system100further includes a solar panel106, and a solar circuit controller108. The solar circuit controller108is responsive to information provided by the data logger and control module102by aligning the solar panel106with the angle of attack of the source of the ambient light coming and further provides control over a charging circuit interacting with the solar panel106to charge a battery110of the thermal control system100. In a preferred embodiment the charging circuit includes at least a diode112in series with a fuse114and the battery110. The battery110preferably provides power to all of the electronic components and assemblies of the thermal control system100, the preferred embodiment includes: the data logger and control module102, the plurality of ambient sensors104, the solar circuit controller108, a motor control and switching circuit116, a flow sensor118, which monitors flow of a heat transfer medium120as the heat transfer medium flows through a heat transfer distribution system122.

The battery110preferably further provides power to a demand sensor124, which is operatively connected to a service object126for collecting a condition of the service object126and providing that information to a heat exchanger controller128and the data logger and control module102. The heat exchanger controller128service to control the operation of a heat exchanger130, used to modulate the thermal condition of the heat transfer medium120. In a preferred embodiment, the battery110further provides power to an electric powered motor132that is configured for operating a heat transfer medium circulation device134, which can be a pump when the heat transfer medium120is a coolant, or a compressor when the heat transfer medium120is a refrigerant.

An additional feature of the preferred embodiment of the inventive thermal control system100is the inclusion of the non-electric powered motor136. A non-electric powered motor136is also configured for operation with the heat transfer medium circulation device134. During the operation of the inventive thermal control system100, the primary drive force for the heat transfer medium circulation device134is the electric powered motor132. However, when the voltage of the battery110drops below a predetermined voltage level of substantially 11 volts, the motor control and switching circuit disengages the electric powered motor132from providing the driving force for the heat transfer medium circulation device134, and engages the non-electric powered motor for use in providing the drive force for the heat transfer medium circulation device134. Preferably, the electronic circuits provided by and included in the thermal control system100operating at a nominal operating voltage of five (5) volts, therefore the electronics associated with the thermal control system100will continue to operate even when the voltage of the battery110drops below the 11 volts threshold.

Turning toFIG. 2, shown therein is a flow chart200, which depicts a method of operating a thermal control system (such as100). The method commences at start process step202and proceeds to process step204with a sensing of a condition of a service object (such as126), wherein in a preferred embodiment the condition sensed is the temperature of the service object, and the service object is a wellhead, or production line leading from the wellhead, or both. At process step206, the method continues with the determining of a condition of a heat transfer medium (such as120), which in the case of a coolant is the temperature of a coolant, and in the case of the refrigerant it is the pressure of the refrigerant present in the system.

At process step208, a heat transfer medium circulation device (such as134) is activated when the sensed condition of the service object obtains a predetermined condition, and at process step210a heat exchanger is engaged when the condition of a heat transfer medium obtains a predetermined condition. Continuing with process step212, an electric motor (such as132) driving the heat transfer medium circulation device is disengaged when a power source (such as battery110) providing energy to the electric motor drops below a predetermined voltage level.

At process step214, a non-electric motor (such as136) is engaged in use to drive the heat transfer medium circulation device in response to the disengagement of the electric motor. To facilitate this function each of the motors communicates with the drive shaft of the heat transfer medium circulation device through corresponding clutches that are responsive to solenoids, which assure the clutches are inactive when the solenoids are in a normally opened state, and the process concludes at end process step224.

In concert with process steps204through214, the method of operating a thermal control system shown by flow chart200further includes process step216, which includes monitoring the condition of the heat transfer medium. At process step218, the heat transfer medium circulation device is activated when the condition of the heat transfer medium obtains a predetermined level, and at process step220, the heat exchanger is engaged when the difference between the condition of the heat transfer medium exiting interaction with the service object and entering interaction with the service object obtains a predetermined differential level. At process step222, a solar panel (such as106) is initiated when the voltage level of power source drops to a predetermined level and the ambient conditions available to the thermal control system are conducive for generation of solar power, and the process concludes at end process step224.

It will be clear that the present invention is well adapted to attain the ends and advantages mentioned as well as those inherent therein. While presently preferred embodiments have been described for purposes of this disclosure, numerous changes may be made which will readily suggest themselves to those skilled in the art and which are encompassed by the appended claims.