Patent Application
20230313659
The presently disclosed technologies are directed to an apparatus and method that processes natural gas, and in particular, a transportable apparatus for processing natural gas at the wellhead.
It is often uneconomical or impractical to capture and transport natural gas in a special pipeline from the wellhead to a refinery. In these cases the gas is flared off, or burned. It is thus wasted, both as a source of energy and as a valuable commodity.
In those instances where a pipeline is built, other problems develop. Natural gas at the wellhead usually contains impurities such as carbon dioxide (CO2), and hydrogen sulfide (H2S). When dissolved in water, CO2 is known as carbonic acid. Similarly, H2S becomes hydrosulfuric acid. Either of these acids will cause corrosion problems in pipelines and related equipment during transportation of natural gas.
The natural gas product at retail comprises almost pure methane, but source natural gas from the wellhead contains a variety of contaminants. In addition to the CO2 and H2S, other gases such as nitrogen and carbon dioxide may be found in oil and gas wells. Solid impurities include sand and dirt from the reservoir; and scale and corrosion products from the piping. The wells produce a mixture of hydrocarbon gas, condensate, or oil; and water with dissolved minerals such as salt. The oil and gas is processed to separate these components.
Some limited processing of source natural gas is often carried out at the well site. However, the complete processing of natural gas is typically carried out at a centralized process plant, or refinery. Gas from the wellhead is transported by pipeline or tanker vehicle to the refinery.
There are benefits for oil and gas companies to utilize natural gas on site to power engines, rather than trucking in diesel fuel or gasoline. Such engines, for example, would power drilling rigs or pump trucks during fracking. Using refined products, such as LNG or CNG, requires offsite processing, trucking and specialized equipment to deliver the fuel to the site. On site natural gas is source or field gas from a well or pipeline. The benefits include cost savings, employee safety, and less environmental disturbance.
Natural gas engines maintain the best performance and require the least maintenance when utilizing a dry, consistent BTU gas delivered at an optimal pressure and temperature. Various engine manufacturers spec different ideal BTU ranges but typically 1000 to 1100 BTU is the prime range that balances horsepower required to do the job with engine and exhaust heat that causes engine and maintenance issues. It is not economical to develop a pipeline infrastructure to a well pad for pre-processed gas to power engines.
Accordingly, there is a need to provide a system that is transportable to the wellhead site, and that is self-contained, and is capable of processing of source natural gas of varying quality found at the natural gas source.
There is a further need to provide a system of the type described, and that can remove water and particulate contaminants.
There is a still further need to provide a system of the type described, and that is capable of being powered by fuels recovered at the wellhead, and of providing fuels of adequate quality to power hybrid fuel engines on site.
There is a yet further need to provide a system of the type described, and that needs no air compressor to operate instruments and control valves.
In one aspect, a natural gas processing system is used in connection with a natural gas source and raw source natural gas produced by the source. The natural gas processing system comprises a mobile platform that can be transported to the natural gas source. A liquid drain is juxtaposed with the mobile platform for discharging liquid contaminants from the natural gas processing system. A source natural gas valve is connected in fluid communication with the natural gas source for controlling the source natural gas entering the natural gas processing system.
A water separator is mounted on the mobile platform, and is connected in fluid communication with the source natural gas valve. The water separator is connected to the liquid drain. The water separator removes water liquid from the natural gas. The water separator allows passage of the natural gas through the water separator.
A particulate filter is mounted on the mobile platform, and is connected in fluid communication with the water separator and the liquid drain. The particulate filter removes particulate matter from the natural gas. The particulate filter allows passage of the natural gas through the particulate filter.
At least one natural gas outlet valve is connected in fluid communication with the particulate filter, and controls the natural gas exiting the natural gas processing system. At least one natural gas outlet is connected in fluid communication with the outlet valve.
In another aspect, a natural gas processing system is used in connection with a natural gas source and raw source natural gas produced by the source. The natural gas processing system comprises a mobile platform that can be transported to the natural gas source. A liquid drain is juxtaposed with the mobile platform for discharging liquid contaminants from the natural gas processing system. A source natural gas inlet is connected in fluid communication with the natural gas source. A source natural gas valve is connected in fluid communication with the natural gas source and controls the source natural gas entering the natural gas processing system.
A water separator is mounted on the mobile platform, and is connected in fluid communication with the source natural gas valve. The water separator is connected to the liquid drain. The water separator removes water liquid from the natural gas. The water separator allows passage of the natural gas through the water separator.
A particulate filter is mounted on the mobile platform, and is connected in fluid communication with the water separator and the liquid drain. The particulate filter removes particulate matter from the natural gas. The particulate filter allows passage of the natural gas through the particulate filter.
A high natural gas outlet is connected in fluid communication with the particulate filter, and controls the natural gas pressure at a predetermined pressure as the gas exits the natural gas processing system. A high natural gas outlet valve is connected in fluid communication with the high natural gas outlet.
A low natural gas outlet is connected in fluid communication with the particulate filter, and controls the natural gas pressure at a pressure less than the predetermined pressure as the gas exits the natural gas processing system. A low natural gas outlet valve is connected in fluid communication with the low natural gas outlet.
A thermoelectric generator is mounted on the mobile platform, and supplies process electricity to the natural gas processing system. The thermoelectric generator is powered by the natural gas.
A process control is operatively connected to the natural gas processing system, and to the thermoelectric generator, for controlling the natural gas processing system.
An emergency shutdown valve is connected in fluid communication with the natural gas outlet. At least one emergency shutdown control is operatively connected to the emergency shutdown valve and to the process control.
In still another aspect, a method is disclosed for processing natural gas through a natural gas processing system. The method is used in connection with a natural gas source and raw source natural gas produced by the source. The method comprises providing a mobile platform and adapting the mobile platform for transporting to the natural gas source.
Mounting a water separator on the mobile platform, and connecting a source natural gas valve in fluid communication with the water separator and the natural gas source. Controlling the source natural gas entering the water separator with the source natural gas valve. Allowing passage of the natural gas through the water separator. Removing water liquid from the natural gas with the water separator, and draining the water liquid from the water separator through a liquid drain.
Mounting a particulate filter on the mobile platform, connecting the particulate filter in fluid communication with the water separator, and allowing passage of the natural gas through the particulate filter. Removing particulate matter from the natural gas with the particulate filter, and allowing water to drain from the particulate filter through the liquid drain.
Connecting a high natural gas outlet in fluid communication with the particulate filter, and controlling the natural gas pressure at a predetermined pressure exiting the natural gas processing system through the high natural gas outlet.
Connecting a low natural gas outlet in fluid communication with the particulate filter, and controlling the natural gas pressure at a pressure less than the predetermined pressure exiting the natural gas processing system through the low natural gas outlet.
Mounting a thermoelectric generator on the mobile platform, supplying process electricity with the thermoelectric generator, and powering the thermoelectric generator with the natural gas.
Operatively connecting a process control to the natural gas processing system and to the thermoelectric generator, and controlling the natural gas processing system with the process control.
Connecting an emergency shutdown valve in fluid communication with the natural gas outlet, operatively connecting at least one emergency shutdown control to the emergency shutdown valve and to the process control, so as to shut down the natural gas processing system in the event of an emergency.
These and other aspects, objectives, features, and advantages of the disclosed technologies will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.
It should be noted that the drawings herein are not to scale.
Describing now in further detail these exemplary embodiments with reference to the Figures as described above, the natural gas processing system is typically used to process natural gas sourced from a well or a pipeline. However, the source is non-limiting, and can be a truck tanker, a marine tanker, a stationary storage tank, or any source.
As used herein, a “processing assembly” or “processing system” refers to one or more devices used to condition or transform or process natural gas into another form or product.
As used herein, “natural gas” refers to raw source natural gas, or refined natural gas, or a gaseous fuel product in any stage of processing from the source to the finished product ready to ship. As used herein, “source gas” refers to raw natural gas or field gas as it comes directly from the wellhead.
As used herein, the term “process” refers to a procedure of moving or transporting a raw source natural gas, or a refined natural gas, or a gaseous fuel product, and converting the natural gas into a gaseous fuel product in any stage of processing. The “flow path” is the conduit through which the natural gas moves during the process. The natural gas moves in a “process direction” along the flow path, shown by arrows.
As used herein, “particulate” is defined as solid or liquid contaminant matter. A “particulate filter” removes entrained mists and oils. An example is a Xebec® coalescing type filter. This example is non-limiting.
As used herein, “water separator” is an apparatus that removes liquid or vapor water contaminants from the gas stream. An example is a Xebec® water separator liquid removal tank. This example is non-limiting.
As used herein, “pressure control valve” is a pressure regulator.
As used herein, “flame detector” is an instrument that senses a flame or heat signature indicating a fire due to gas leak or an electrical short in the system that is potentially dangerous. Flame detector includes an infrared sensor.
As used herein, “methane detector ” is an instrument that senses a gas leak in the system that is potentially dangerous.
Energy companies benefit by using natural gas at the well head, rather than diesel fuel, to power engines for on-site processes such as drilling, pumping various fluids, and for electricity. This results in cost savings, worker safety, and environmental protection. This disclosure is one embodiment of the invention that conditions natural gas from the well head for use in these multi-fuel engines. Referring to the drawing figures, a natural gas processing system is shown at 20. The system 20 is used in connection with a natural gas source 22 (not shown) which typically comprises, but is not limited to, a natural gas well or a natural gas pipeline. Raw source natural gas 24 (not shown) is produced by the source 22. The natural gas 24 enters the system through natural gas inlet 26. The natural gas processing system 20 comprises a mobile platform 28 that can be transported to the natural gas source 22. The mobile platform 28 is typically a trailer or a skid, but is not limited to these structures. The mobile platform 28 can be any structure capable of receiving and mounting equipment and of being transported to the site of the natural gas source 22.
Turning to the drawing
A water separator 32 is mounted on the mobile platform 28, and is connected in fluid communication with the source natural gas valve 36. The water separator 32 is connected to the liquid drain 30. The water separator 32 removes water liquid from the natural gas 24. The water separator 32 allows passage of the natural gas 24 through the water separator 32.
A particulate filter 46 is mounted on the mobile platform 28, and is connected in fluid communication with the water separator 32 and the liquid drain 30. The particulate filter 46 removes particulate matter from the natural gas 24. The particulate filter 46 allows passage of the natural gas 24 through the particulate filter 46. The particulate filter 46 has a particulate filter bypass valve 50 for vessel maintenance.
At least one natural gas outlet valve is connected in fluid communication with the particulate filter for controlling the natural gas exiting the natural gas processing system. At least one natural gas outlet is connected in fluid communication with the outlet valve.
In the preferred embodiment, the gas flow will split, after the particulate filter 46, into two streams. A high natural gas outlet 56 is connected in fluid communication with the particulate filter 46, and controls the natural gas pressure at a predetermined pressure as the gas exits the natural gas processing system 20. A high natural gas outlet valve 88 is connected in fluid communication with the high natural gas outlet 56.
A low natural gas outlet 54 is connected in fluid communication with the particulate filter 46, and controls the natural gas pressure at a pressure less than the predetermined pressure as the gas exits the natural gas processing system 20. A low natural gas outlet valve 86 is connected in fluid communication with the low natural gas outlet 54.
A process control 66 is operatively connected to the natural gas processing system 20, and to the thermoelectric generator 64, for controlling the natural gas processing system 20. The process control 66 receives data from the plurality of temperature, pressure, gas, and flow measuring sensors operatively connected to the process control.
An emergency shutdown valve 72 is connected in fluid communication with the natural gas outlets 54, 56. At least one emergency shutdown control 71 is operatively connected to the emergency shutdown valve 72 and to the process control 66. The emergency shutdown control and valve is monitored by the process control 66.
A high flow sensor 60 is connected in fluid communication with the high natural gas outlet 56. A low flow sensor 58 is connected in fluid communication with the low natural gas outlet 54. The high 60 and low 58 flow sensors are operatively connected to the process control 66.
A high temperature sensor 81 is connected in fluid communication with the high natural gas outlet 56. A low temperature sensor 80 is connected in fluid communication with the low natural gas outlet 54. The high 81 and low 80 temperature sensors are operatively connected to the process control 66.
Typically, one pressure sensor upstream 97 is connected to the bypass piping around the particulate filter 46, and upstream of the gas flow split, as shown in
As an option, one or more pressure regulators may be utilized.
At least one gas sensor 85 is connected in fluid communication with the natural gas outlet 54, 56. The gas sensor 85 is operatively connected to the emergency shutdown control 71 for direct emergency shutdown, in the event that any gas composition parameters should exceed programmed limits. A gas analyzer 84 is operatively connected to the gas sensor 85 and to the process control 66. The gas analyzer will determine the chemical composition of the natural gas 24, and will convey the data to the process control 66. The gas analyzer is preferably a gas chromatograph, but this is understood to be non-limiting, as any type of gas analyzer can be used.
An H2S sensor 89 is connected in fluid communication with the natural gas outlet 54, 56. The H2S sensor 89 is operatively connected to the emergency shutdown control 71 for direct emergency shutdown, in the event that any H2S parameters should exceed programmed limits. An H2S analyzer 83 is operatively connected to the H2S sensor 89 and to the process control 66. The H2S analyzer will determine the H2S composition of the natural gas 24, and will convey the data to the process control 66.
At least one moisture sensor 69 is connected in fluid communication with the natural gas outlet. The moisture sensor 69 is operatively connected to the emergency shutdown control 71 for direct emergency shutdown, in the event that moisture levels should exceed programmed limits. A moisture analyzer 68 is operatively connected to the moisture sensor 69 and to the process control 66. The moisture analyzer 68 will determine the presence and quantity of water and other liquid particle contaminants.
A thermoelectric generator 64 is mounted on the mobile platform 28, and supplies process electricity to the natural gas processing system 20. The thermoelectric generator 64 is powered by the natural gas 24, which is supplied to the thermoelectric generator 64 at approximately 1695 SCFD and 15-25 PSIG.
Instruments are provided that monitor conditions inside the enclosure 29 and signal the presence of flammable gas or flame. In the preferred embodiment, a first methane detector 38, a second methane detector 40, and a third methane detector 42 will detect a methane leak, and alert the emergency shutdown control 71. Similarly, a flame detector 44 will detect any heat signature, and alert the emergency shutdown control 71. The flame detector 44 preferably will be an infrared sensing device, but this is understood to be non-limiting, and any flame detector can be utilized.
HMI (human-machine interface) cabinets include a HMI internal cabinet 100 mounted on the mobile platform 28. A HMI external cabinet 106 is mounted outside of the mobile platform 28, at any desired distance away, and is connected by a cable, although a wireless connection is an option. The HMI internal 100 cabinet includes a keyboard 102 to input commands, and a monitor 104 to display data. The HMI external 106 cabinet is substantially a duplicate, and includes a keyboard 108 to input commands, and a monitor 110 to display data. The HMI will monitor system parameters in real time.
The process control 66 includes at least a central processor, a memory, and input and output connections. Input signals are received from instruments, sensors, and detectors throughout the system. The sensors and detectors are connected by cables to the process control 66, although wireless connections is an option. Input signals comprise temperature, pressure, and flow at various critical points of the system. Input signals further comprise electrical voltage and current. Control logic is programmed to monitor the entire process and is able to provide operator ease of use and real time process status updates.
Output signals are sent to the HMI internal 100, and to the HMI external 106, and the emergency shutdown control 71. Shutdown can be initiated from the HMI internal 100 or the HMI external 106. Shutdown can also be initiated manually from ESD switches 73 located on the outside of the mobile platform enclosure 29. ESD switches 73 are also located on the HMI internal 100, and HMI external 106 cabinets. Shutdown can further be initiated automatically by input from any one of the first methane detector 38, the second methane detector 40, the third methane detector 42, or the flame detector 44.
Level indicators, typically sight glass windows, on the water separator 32, and on the particulate filter 46 vessels allow operators to monitor the amount of liquid contaminants that have accumulated. The present disclosure provides automatic means for detecting water levels in the water separator 32 and in the particulate filter 46, and draining the liquid contaminants.
A first liquid level sensor 112 is connected in fluid communication with the water separator 32, and senses a first predetermined liquid level in the water separator. The first liquid level sensor 112 is operatively connected to the process control 66 for sending data to the process control.
A first control valve 114 is connected in fluid communication with the water separator 32 and the liquid drain 30. The first control valve 114 is operatively connected to the process control 66 and is responsive to data sent from the first liquid level sensor 112 to the process control 66. When the first predetermined liquid level is reached, the process control 66 will open the first control valve 114 to drain liquid contaminants from the water separator. Natural gas 24 will continue to flow through the system during the draining process.
A second liquid level sensor 116 is connected in fluid communication with the water separator 32 and senses a second predetermined liquid level in the water separator 32 that is higher than the first predetermined liquid level. The second liquid level sensor 116 is operatively connected to the process control 66 for sending data to the process control. The second liquid level sensor 116 is also operatively connected to the emergency shutdown control 71 for direct emergency shutdown in the event of water levels exceeding the second predetermined liquid level.
A second control valve 118 is connected in fluid communication with the water separator 32 and the natural gas inlet 26. The second control valve 118 is operatively connected to the process control 66 and is responsive to data sent from the second liquid level sensor 116 to the process control 66. When the second predetermined liquid level is reached, the water separator 32 is in danger of being overcome by the liquid contaminants with catastrophic consequences. At this time, the process control 66 will close the second control valve 118 to shut off natural gas 24 to the water separator 32 and activate the emergency shutdown control to stop all gas flow through the system, thus precluding damage to the natural gas processing system 20.
A third liquid level sensor 120 is connected in fluid communication with the particulate filter 46 and senses a third predetermined liquid level in the particulate filter 46. The third liquid level sensor 120 is operatively connected to the process control 66 for sending data to the process control.
A third control valve 122 is connected in fluid communication with the particulate filter 46 and the liquid drain 30. The third control valve 122 is operatively connected to the process control 66, and is responsive to data sent from the third liquid level sensor 120 to the process control 66. When the third predetermined liquid level is reached, the process control 66 will open the third control valve 122 to drain liquid contaminants from the particulate filter 46. Natural gas 24 will continue to flow through the system during the draining process.
A fourth liquid level sensor 124 is connected in fluid communication with the particulate filter 46 and senses a fourth predetermined liquid level in the particulate filter 46 that is higher than the third predetermined liquid level. The fourth liquid level sensor 124 is operatively connected to the process control 66 for sending data to the process control 66. The fourth liquid level sensor 124 is also operatively connected to the emergency shutdown control 71 for direct emergency shutdown in the event of water levels exceeding the fourth predetermined liquid level.
A fourth control valve 126 is connected in fluid communication with the particulate filter 46 and the natural gas inlet 26. The fourth control valve 126 is operatively connected to the process control 66 and is responsive to data sent from the fourth liquid level sensor 124 to the process control 66. When the fourth predetermined liquid level is reached, the particulate filter 46 is in danger of being overcome by the liquid contaminants with catastrophic consequences. At this time, the process control 66 will close the fourth control valve 126 to shut off natural gas 24 to the particulate filter 46 and activate the emergency shutdown control to stop all gas flow through the system, thus precluding damage to the natural gas processing system 20.
The source natural gas 24 parameters at the natural gas inlet 26 are as follows. The natural gas processing system 20 is adapted to process the source natural gas 24 having a temperature range from 30° F. to 180° F., but is preferably from 40° F. to 120° F. The BTU composition can range from 1,100 BTU to 1,400 BTU, but is preferably from 950 BTU to 1800 BTU. The source natural gas 24 pressure can range from atmospheric pressure to 2400 PSIG, but is preferably from 50 PSIG to 1200 PSIG. The source natural gas 24 saturation levels are at typically at dewpoint.
Vent connections with associated piping are found on major components throughout the system. All vents typically bleed gases to the atmosphere through a relief valve.
It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
