BACKGROUND OF THE INVENTION
The present invention relates to the field of oil and gas process equipment burner systems, specifically to methods and apparatuses for preventing unignited methane emissions from said burner systems.
Traditional burner control of oil and gas process equipment, such as separators, tank heaters, dehydrators, in-line heaters and other process equipment, is defined here as a burner system with pneumatic thermostatic temperature control means, known in the art as T12 thermostats. It is most common for oil and gas processing equipment to utilize natural gas (primarily composed of methane) as the pneumatic supply gas and as the fuel gas supply consumed by the main burner and standing pilot flame. These pneumatic thermostats use a thermal expansion rod in direct contact with vessel contained fluid. When the contained fluids cools to point lower than the pneumatic thermostat setpoint, the thermal expansion rod cools proportionally and contracts, opening a valve to supply control gas pressure to a pressure-open valve. This pressure-open valve is responsible for the fuel gas supply to a main burner, which is ignited by a standing pilot flame. Once fuel gas is sent to the main burner, the heat transfer rate is increased, the fluid temperature rises, the thermal expansion rod expands, and control gas pressure to the pressure-open valve is terminated. This process is continued indefinitely in maintaining vessel temperature.
The process and equipment discussed above, if performing properly, is effective in maintaining vessel temperature. This reliability coupled with the simplicity of operation and simplicity of maintenance of traditional burner control, has driven mass deployment in today's oil and gas fields. Additionally, electronic burner management systems and auto-igniters are a relatively recent invention and with active process equipment dating as far back as the 1950's or further, traditional burner control are the majority of burner control systems in today's oil and gas fields.
The short coming of traditional burner control is the system's complete in-ability to recognize or solve the extinguishment of the standing pilot. Extinguishment of the standing pilot can be caused by numerous conditions. Examples are: liquid can condense in the pilot fuel gas line causing a momentary obstruction in the pilot orifice while exiting the orifice; the condensed fluid can also freeze when ambient temperatures are low enough causing the halt of pilot fuel gas flow; solid particulates can plug the small pilot orifice; strong gusts of wind can blow the pilot flame out; or other scenarios not mentioned. Once the pilot flame is extinguished, the system cannot recognize such, and when vessel temperature cools to a point that fuel gas is supplied to the main burner, unignited fuel gas is vented from the main burner uncontrollably until manual intervention to relite the standing pilot flame. With the remoteness of some locations, manual intervention can be delayed by periods of days. With the large size of process equipment burners, substantial volumes of fuel gas (primarily methane) can be emitted to the atmosphere increasing the world's greenhouse gas concern. This short coming not only creates a serious emission issue, but the fact that substantial amounts of fuel gas are essentially lost forever, a considerable loss of revenue can be experienced during the lifetime of a producing oil or gas well.
There are currently marketed burner management control systems and auto-igniters that can address this emission issue, and re-light the pilot or act as the ignition source for the main burner. Inherent issues lie within these products that cause resistance in wide deployment into a vast market with legitimate needs. One such issue is the added complexity these systems add to the burner system. As described above, traditional burner control is mechanical and simple. Additionally, technicians have more experience with traditional burner control and pneumatic gas systems in general. The addition of igniters, flame sensors, electrical harnesses and other required components, increase complexity during maintenance. Furthermore, marketed burner management systems and auto-igniters have the issue of introducing the dependency of the process equipment for vessel temperature. For example, if the battery bank has run down or an electrical component has failed, the equipment has no capability of re-introducing heat into the vessel. The remoteness of locations and the inexperience of technicians with electrical automation cause for real issues, especially during winter months. Another, and perhaps the larger source of resistance to widely addressing the market issue, is the cost of these complex units in both cost of goods sold and in installation. Well economics on many low producing wells does not allow for the purchase of these products. This issue is especially apparent in older, existing locations. Original Equipment Manufacture (OEM) installation of burner management systems and auto-igniters is much more economical compared to retrofitting existing locations that can be remote and are most likely equipped with traditional burner control.
Accordingly, there is a need for a-methods and apparatuses for supervision and control of the burner system that are sufficiently simple, reliable and rugged for oil and gas process equipment.
SUMMARY OF THE INVENTION
The present invention provides apparatuses and methods for monitoring vessel temperature and shutting off the burners if undesired vessel temperature characteristics are recorded. Further, the present invention provides methods and devices for the control of process equipment burners as to avoid natural gas emissions and overheating scenarios.
Advantages and novel features will become apparent to those skilled in the art upon examination of the following description and can be learned by the practice of the invention.
DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts an embodiment of the present invention installed on a typical, horizontal, 3 phase separator.
FIG. 2 depicts an embodiment of the mounting and thermowell access fixture for the embodiment of FIG. 1.
FIG. 3 depicts a second embodiment of the present invention installed on a typical, horizontal, 3 phase separator.
FIG. 4 depicts an embodiment of the controller of the FIG. 1 embodiment of the present invention.
FIG. 5 depicts an embodiment of the controller of the FIG. 3 embodiment of the present invention.
FIG. 6 depicts an embodiment of the mounting feature and temperature reading device of the FIG. 3 embodiment of the present invention.
FIG. 7 depicts a cross-section of an embodiment of the mounting feature and temperature reading device of the FIG. 3 embodiment of the present invention.
FIG. 8 depicts an embodiment of the circuit board for the present invention.
DETAILED DESCRIPTION
FIG. 1 depicts an embodiment of the present invention installed on a 3 phase, horizontal separator. Traditional control consists of the same components, minus controller 24, reset input 5, exhaust port 9 and mounting/sensor fixture 7. Additionally, output line 10 and input line 23 would be combined into one line connecting the output of the pneumatic thermostat 8 and the input to pressure-open valve 11. Fuel gas supply 4 supplies fuel pressure to pneumatic thermostat 8, pressure-open valve 11 (which in-turn controls fuel gas flow to main burner fuel gas line 12), and pilot burner fuel gas line 13. Pilot burner fuel gas line would lead into burner housing 1 to supply fuel gas to the standing pilot when pilot burner manual valve 15 is open. Main burner fuel gas line 12 would lead into burner housing 1 to supply the main burner with fuel gas when both the main burner manual valve 14 and pressure-open valve 11 are open. The burner system would then function traditionally as described in the background section above with pressure-open valve 11 supplying and terminating fuel gas to the main burner depending on the state of pneumatic thermostat 8, which is in turn dependent upon vessel 2 fluid temperature.
The present invention embodiment depicted in FIG. 1 integrates with the traditional control system. Mounting/sensor fixture 7 would be installed into the thermowell of analog temperature gauge 6. Mounting/sensor fixture 7 would be designed in such a way as to not impede the installation of analog temperature gauge 6 into the same thermowell. Analog temperature gauge 6, typically of the bimetallic variety, consists of a dial fixed to a stem, with said dial having a male NPT fitting that threads into the female NPT fitting of the thermowell. Once mounting/sensor fixture 7 is installed, analog temperature gauge 7 would still retain proper contact with vessel 2 contained fluids for proper indication of said fluid temperature as not eliminate the technician's ability to read vessel 2 fluid temperature. Mounting/sensor fixture 7 would hold a temperature sensor for installment into the analog temperature gauge 6 thermowell. Additionally, mounting/sensor fixture 7 comprises a mounting bracket for installation of controller 24. Once fixed in position, controller 24 has input supply gas line 23 plumbed into it from the output of pneumatic thermostat 8 and controller 24 output plumbed to output line 10 connected to the pressure-open valve 11. Controller 24 is capable of interrupting supply gas pressure from pneumatic thermostat 8 to pressure-open valve 11, thus ceasing fuel gas flow to the main burner. Controller 24 can through microprocessor control logic make state changes based on vessel 2 fluid temperature trendline characteristics. Vessel 2 fluid temperature is measured via mounting/sensor fixture 7.
FIG. 2 depicts an embodiment of mounting/sensor fixture 7 of FIG. 1.
Mounting/sensor fixture 7 will thread into the dedicated thermowell for analog temperature gauge 6 utilizing male fixture threads 17, preferably matching the female threads of the thermowell. Additionally, female fixture threads 18, preferably matching the thermowell threads as well, allows access for the analog temperature gauge 6 into the thermowell as well. Temperature sensor lead 19 connects circuit board 29 to temperature probe 16 through temperature sensor port 20. Temperature senor probe 16 is preferably made of a rigid material forming a column that parallels the stem of analog temperature gauge 6. Another embodiment of temperature probe 16 is a composition of flexible material and a clip located at the end of temperature probe 16 that attaches temperature probe 16 to analog temperature gauge 6 stem. In either embodiment, temperature probe 16 is held in proper contact with vessel 2 fluid. Mounting fixture 22 acts in fixing controller 24 to vessel 2 via fasteners installed through fastener ports 21. Furthermore, temperature sensor lead 19 can be communicated through temperature sensor port 20 and into controller 24.
FIG. 3 depicts another embodiment of the present invention. In this embodiment controller 24, as in the previous embodiment, has input supply gas line 23 plumbed into it from the output of pneumatic thermostat 8 and controller 24 output plumbed to output supply gas line 10 connected to the pressure-open valve 11. As in the previous embodiment, this embodiment does not fix controller 24 to vessel 2 via mounting/sensor fixture 7, nor does this embodiment make a temperature sensor contact via the analog temperature gauge 6 thermowell. Rather, controller 24 is held in position on vessel 2 via a magnet base located on the back of controller 24. This magnet base and vessel 2 temperature reading feature is depicted in later figures and will be discussed in further detail at that point. Additionally, FIG. 3 depicts an embodiment of a battery recharging system, which can be installed on either FIG. 1 or FIG. 3 embodiments. This recharging system is comprised of solar panel 27, magnetic base 26 and solar panel lead 25. Being that vessel 2 is made of steel, not only can controller 24 be held in position by a magnet but also solar panel 27 can be mounted to vessel 2 by magnet in a preferable orientation for maximum solar recharge. Solar panel 27 is connected to controller 24 via solar panel lead 25.
FIG. 4 depicts an embodiment of controller 24 and the internal components of controller 24, ideal for use in FIG. 1 embodiment of the present invention. Internal tubing 36 can carry fuel pressure from the right-side input of controller 24, connected (via input line 23) to the output of pneumatic thermostat 8, to the left-side output of controller 24, connected (via output line 10) to the input of pressure-open valve 11. In other words, input line 23 is connected to input of internal tubing 36 on the exterior of controller 24, supplying fuel pressure first to pressure sensor 31, second to solenoid valve 32, and finally to output of internal tubing 36, which is connected to output line 10. Circuit board 29 has all the inputs and outputs to correctly gather signals and create the corresponding control output. Solar controller 30 is responsible for acquiring voltage and controlling voltage from solar panel 27 via solar panel lead 25. Additionally, solar controller 30 could be configured to receive electrical charge from other sources, for example 120 ACV. Solenoid valve 32 is preferably of the latching variety (as to reduce power consumption), and of the 3 way, venting variety. When solenoid valve 32 is in the open position fuel pressure is unrestricted from the output of pneumatic thermostat 8 to the input of pressure-open valve 11. Solenoid valve 32 in such state allows burner system to function just as described as traditional control. If solenoid valve 32 is shut, fuel pressure to pressure-open valve 11 is ceased and trapped pressure is vented out exhaust port 9, thus shutting pressure-open valve 11. Solenoid valve by-pass lever 35 allows for by-pass of solenoid valve 32 if a disabling failure in the present invention occurs. Solenoid valve by-pass lever 35 can be rotated, which in-turn presses a threaded stem against the plunger of solenoid valve 32 holding it off of seating on solenoid valve 32 orifice, allowing fuel pressure past solenoid valve 32. This feature allows restoration of traditional burner control capabilities if controller 24 is disabled. Alarm LED 38 located preferably on top of controller 24 communicates alarm presence in the present invention. Solar panel lead port 33 allows for the entrance of solar panel lead 25 or any other charging lead. Mounting port 37 is shown to be on the right side of controller 24, but can be positioned anywhere, on any controller 24 wall or multiple mounting ports 37 could be utilized for any mounting orientation. Mounting port 37 approximately matches the profiles of fastener ports 21 and temperature sensor ports 20 for mounting controller 24. Enclosure 28 along with connections made at solar panel lead port 33, mounting port 37, exhaust port 9 and Alarm LED 38, are to be sealed to a point sufficient for identified hazardous location standards. A battery, which would be housed in enclosure 28, is not shown. Additionally not shown in depiction are wire connecting leads, connecting: pressure sensor 31 to circuit board 29, solenoid valve 32 to circuit board 29, alarm LED 38 to circuit board 29, temperature probe lead 19 to circuit board 29, undepicted battery to circuit board 29, solar panel lead 25 to solar controller 30 and solar controller 30 to undepicted battery.
FIG. 5 depicts another embodiment of controller 24. This embodiment has the same features as the embodiment of FIG. 4 minus mounting port 37 and addition of temperature sensor receptacle and box mount 39. This embodiment of controller 24 is ideally suited for the present invention embodiment of FIG. 3. FIG. 3 embodiment description briefly described a magnetic disc for mounting controller 24 to vessel 2 and for measuring surface temperature of vessel 2. This magnetic disc mounts and gains access to controller 24 via temperature sensor receptacle and box mount 39. This embodiment of controller 24 would function just the same as the description of the FIG. 4 embodiment, minus mounting ports 37 and mounting/sensor fixture 7 installation method. Instead, the mounting and sensor input features would be performed by temperature sensor receptacle and box mount 39. Temperature sensor receptacle and box mount 39 would be coupled to controller 24 with one or more fastener components and be sealed to a point sufficient for hazardous location identification standards.
FIG. 6 depicts the back side of controller 24 depicted in the embodiment of FIG. 5. This depiction highlights the magnetic disc features attached to temperature sensor receptacle and box mount 39. Attached to the back of controller 24, disc 41 (preferably made of metal alloy or other rigid material), encompasses a seal 42 (preferably a compressible polymer-like material), encompassing a magnetic disc 40, which further encompasses a temperature sensor 43. FIG. 7 further depicts this embodiment of the magnetic mount assembly. In this cross-section of the embodied assembly, seal 42 is seen compressed between disc 41 and magnetic disc 40. These three components would be fastened together with any means appropriate and known to a person of ordinary skill in the art. The seal 42 would protrude higher than the top of magnetic disc 40 and disc 41 (which are approximately the same height). With the protrusion of seal 42 and the compressible characteristic of seal 42, if the assembly is located onto the steel surface of vessel 2, a seal is made as magnetic disc 40 creates a force normal to the magnetic disc 40 face. Even with the typical radial vessel 2 surface, a seal can be made. Additionally, temperature sensor 43 is set to protrude past the magnetic disc 40 height and is pressed forward by compression spring 44, which can be a compression spring or any other compressible element. Once located on vessel 2 surface, magnetic disc 40 compresses seal 42 and simultaneously, by contact with vessel 2 surface, presses temperature sensor 43 back and in-turn compresses compression spring 44. This action creates a force holding temperature sensor 43 in contact with vessel 2 surface. Constant contact with vessel surface creates a preferable thermal transmission between the steel vessel 2 and temperature sensor 43. This coupled with the isolation of temperature sensor 43 created by a compressed seal 42 allows for greater temperature reading reliability.
FIG. 8 depicts an embodiment of circuit board 29. Primary solenoid output 45 is connected to solenoid valve 32. Primary pressure sensor input 46 would be wired to pressure sensor 31. Secondary solenoid output 47 would be used for an expanded embodiment of the invention which includes a solenoid valve for the standing pilot for complete fuel control. Mode switch 48 is used to set circuit board 29 from intermittent mode, which power is supplied and cut by pressure sensor 31, to continuous mode, in which circuit board 29 power is constant. High voltage module output 49 gives the capability of supplying voltage to a high voltage module to create a high energy spark for an embodiment of the invention that includes an ignition harness. Primary temperature sensor input 50 would be tied to the vessel 2 temperature sensor 16,43. Alarm digital output 51 is included for a digital alarm output for customer preference. Secondary temperature sensor input 52 gives access to a secondary vessel 2 temperature sensor. Communication port 53 is equipped with any appropriate connector and appropriate communication protocol known to an ordinary person skilled in the art. Microprocessor 54 is responsible for executing logic commands based on input parameters. Electronic power limiter 55 to limit power outputs to a point lower than non-incentive standards, for example one of more eFuses. Alarm LED output 56 responsible for controlling power to the alarm LED 38. Digital input 57 one or more digital inputs for a multitude of external commands, for example emergency shut-down commands.
With the essential elements of the present invention described, the typical function will now be described. The primary goal of the present invention in any embodiment is to eliminate uncontrolled methane emissions via the main burner and ultimately exhaust stack 3 of oil and gas process equipment. The preferred method is executed, first, by recognizing the request for main burner from pneumatic thermostat 8. Pressure sensor 31, preferably a normally-open pressure switch with a contact that completes the circuit board 29 power circuit, turns on circuit board 29 when the output pressure of pneumatic thermostat 8 is high enough to close the pressure sensor 31 contact. Circuit board 29 begins recording vessel 2 in either embodiment disclosed. If circuit board 29 registers an unlit main burner, an output will be sent to solenoid valve 32, closing it and ceasing fuel flow to the main burner. Circuit board 29 registers that the main burner is unlit based on the heat transfer rate of the burner system should be increased to a minimum point that vessel 2 temperature should not continue to decline. Due to this characteristic, the logic of circuit board 29 microcontroller 54 can decide to shut-in the main burner based off continued vessel 2 temperature decline or based on a minimum temperature threshold.
During initialization or reset after the shut-in of the main burner by the present invention, reset button 5 is positioned on the outside of controller 24. The technician will press reset button 5 which will set solenoid valve 32 to an open state, at which point the burner system can be initialized as per traditional control protocols. The present invention can then follow a protocol of non-intervention for a period of time or allow fuel pressure to the main burner based on a desired heating characteristic tracked in the vessel 2 temperature trendline.
Another feature of the present invention is, if set to continuous mode (as described in paragraph [0027]), a high temperature shutdown can be implemented. If the present invention is configured to continually observe vessel 2 temperature, it would then be capable of shutting down the main burner if a high temperature threshold is reached. This feature would help process equipment avoid overheating damage to the equipment in cases of pneumatic thermostat 8 malfunction or if pneumatic thermostat 8 is set to high.
For the purpose of disclosure, approximately is defined here as plus or minus 10%.
Patent Application
20220333774
