Wellhead Gas Expansion for Cold CNG Without Fuel Heating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Geobaric energy production faces challenges due to low outlet temperatures from pressure reduction through conventional choke valves, which can lead to inefficient energy conversion and increased greenhouse gas emissions when attempting to counteract these temperatures with additional heat.
Innovation Solution
Utilizing the low outlet temperature from a geobaric expander by sealing cold gas in a rigid CNG container, allowing it to absorb heat and increase pressure, thereby producing CNG without fuel or electricity consumption, thus minimizing carbon emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If pressure reduction is performed through a conventional choke valve, then the gas temperature decreases, but this causes operational issues and requires additional heating that increases fuel consumption and emissions
Solution Approach 1:
The patent converts the harmful low temperature effect (Joule-Thomson cooling) into a beneficial pre-cooling function for the CNG storage process. Instead of viewing the temperature drop as a problem requiring heating correction, the invention utilizes it as a free cooling resource that reduces or eliminates the need for active cooling during CNG compression, thereby converting an adverse thermal effect into an energy-saving advantage.
Solution Approach 2:
The system uses the gas stream itself to provide the cooling effect needed for CNG storage. The expanding gas naturally cools itself through the Joule-Thomson effect, and this self-cooling property is harnessed to achieve the required temperature for CNG compression without requiring external cooling energy input, making the system self-sufficient in meeting its thermal requirements.
2Power
If an expander is used to extract geobaric energy, then work is extracted from the gas, but the outlet temperature becomes even lower requiring more heating
Solution Approach 1:
The patent transforms the excessively low expander outlet temperature from a detrimental condition into a valuable asset. The deep cooling effect, which would normally require energy-intensive reheating, is instead utilized as free pre-cooling for the CNG storage process, eliminating the need for external cooling energy and turning what was considered a waste (excessive cooling) into a resource.
Solution Approach 2:
The invention changes the target temperature parameter from ambient or pipeline temperature to a lower temperature suitable for CNG storage. By adjusting the desired outlet temperature parameter to match the requirements of CNG compression (which benefits from lower temperatures), the system transforms the expander's low temperature output from a mismatched condition into an optimized operating parameter for the overall process.
3Reliability
If additional heat is added to counteract low outlet temperatures, then operational issues are avoided, but more salable product must be burned as fuel increasing emissions
Solution Approach 1:
The patent converts the need for heating (which causes emissions) into a cooling opportunity. By utilizing the natural Joule-Thomson cooling effect and the expander's cooling output, the system eliminates or reduces the need for fuel burning, thereby converting a harmful process (combustion for heating) into a beneficial emission-reduction outcome while maintaining operational reliability.
Solution Approach 2:
The system operates in the gas phase throughout the process, utilizing the Joule-Thomson effect which is a thermal phenomenon occurring during gas expansion. The gas undergoes temperature changes during pressure reduction and storage without requiring phase change, allowing the system to leverage thermodynamic properties of gas expansion to achieve both pressure reduction and cooling simultaneously.
4Temperature
If the gas is cooled to achieve CNG storage conditions, then CNG can be produced, but conventional cooling methods consume energy
Solution Approach 1:
The gas stream performs its own cooling function through the Joule-Thomson effect during pressure reduction. The system requires no external cooling energy input because the gas naturally cools itself as it expands from high wellhead pressure to lower storage pressure, making the cooling process self-powered and eliminating the need for separate cooling energy consumption.
Solution Approach 2:
The patent transforms the energy that would normally be lost as waste heat during expansion into a useful cooling effect. Instead of dissipating thermal energy to the environment, the system captures and utilizes the temperature drop generated during Joule-Thomson expansion to achieve the cooling required for CNG storage, converting what was previously a thermal loss into a productive resource.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances economic efficiency and reduces environmental impact by eliminating the need for on-site fuel burning and lowering emissions, while capturing energy associated with wellhead pressure.
Implementation Method 1
when gas is sealed in a rigid container, its absolute pressure will remain directly proportional to its absolute temperature, since the molar density is fixed. Thus, if cold gas is sealed in a rigid CNG container at a relatively low pressure, it may increase in pressure up to a customary level by gradually absorbing heat from its surroundings
Implementation Method 2
pressure reduction through a geobaric expander may only exacerbate the problem. In fact, use of an expander may exacerbate the problem in proportion to how much geobaric energy is produced
Implementation Method 3
the gas stream is: (1) throttled from wellhead pressure to pipeline pressure by a choke valve; and (2) heated before and/or after the choke valve to compensate for the Joule-Thomson effect
Data Source
AI summary
Methods and compositions for processing a gas produced from an oil and gas well are provided. In some embodiments, the compositions include a wellbore penetrating at least a portion of a subterranean formation. The compositions further include one or more fluid flow paths in fluid communication with the wellbore, the one or more fluid flow paths having at least a first segment and a second segment. The compositions further include at least one heat exchanger. The compositions further include an expander coupled to a generator in fluid communication with the gas in the second segment. The gas in the first segment flows through the at least one heat exchanger wherein it is cooled to the point of forming CNG, and the gas in the second segment flows through the expander to generate electricity.