Natural Gas Pre-heating via Electrical Heaters and Expanders
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Solution Overview
Problem
Current methods for pre-heating natural gas at Pressure Reduction Stations are inefficient and rely on fossil fuels, leading to energy wastage and emissions, as they require boilers, gas turbines, or fuel cells to prevent hydrate formation during pressure drops.
Innovation Solution
A method involving an electrical heater to pre-heat high-pressure gas, which then passes through a gas expander and power generator, utilizing the generated electricity to maintain the power generator's efficiency and recycle energy by heating the gas further, reducing the need for fossil fuel-based pre-heating systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fossil fuel-based boilers or heaters are used to pre-heat natural gas, then the gas temperature increases to prevent hydrate formation, but energy is wasted and emissions are generated
Solution Approach 1:
The invention converts the harmful waste heat from the gas expander into a beneficial resource by using it to pre-heat the incoming natural gas through a heat exchanger. This eliminates the need for separate fossil fuel-based heating systems while preventing hydrate formation, thus converting what would be wasted energy into a useful function.
Solution Approach 2:
The invention merges the gas expansion process with the gas heating process by integrating a heat exchanger that uses the cold expanded gas to cool the power generator and simultaneously pre-heats the incoming high-pressure gas. This combination eliminates the need for separate heating systems and reduces overall energy consumption.
2Temperature
If fossil fuel-based boilers or heaters are used to pre-heat natural gas, then the gas temperature increases to prevent hydrate formation, but emissions are generated
Solution Approach 1:
The invention eliminates emissions by replacing fossil fuel-based heating systems with a waste heat recovery system. The heat exchanger uses the temperature difference between hot incoming gas and cold expanded gas to achieve pre-heating without combustion, thus converting a potentially harmful process into an emission-free operation.
3Power
If the power generator is kept cooler, then its efficiency increases, but additional cooling mechanisms are required
Solution Approach 1:
The system uses the cold expanded gas from the gas expander to cool the power generator through the heat exchanger. The cold gas, which would otherwise be wasted, automatically serves the cooling function without requiring additional active cooling mechanisms, thus simplifying the system while improving efficiency.
Solution Approach 2:
The invention merges the gas heating function with the power generator cooling function in a single heat exchanger unit. The hot incoming gas passes through the heat exchanger, transferring heat to the cold expanded gas that cools the power generator, thus combining two functions into one integrated system.
4Loss of energy
If energy recovery systems are added to pressure reduction stations, then energy efficiency improves, but the device complexity increases due to multiple variables affecting economics
Solution Approach 1:
The invention merges the gas expansion process with the gas heating process by integrating a heat exchanger that uses the cold expanded gas to cool the power generator and simultaneously pre-heats the incoming high-pressure gas. This combination eliminates the need for separate heating systems and reduces overall energy consumption.
Solution Approach 2:
The heat exchanger performs multiple functions simultaneously: it pre-heats the incoming natural gas to prevent hydrate formation, cools the power generator to improve efficiency, and recovers waste heat from the expanded gas. This multi-functionality reduces the need for separate systems and simplifies the overall configuration.
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 significantly reduces energy wastage and emissions by recovering energy at pressure reduction stations, enhancing the efficiency of power generation and eliminating the need for gas slipstreams, thereby improving the overall energy recovery and reducing operational costs.
Implementation Method 1
at least one line heater, with a first flow path for passage of incoming high pressure cold gas that passes through coils heated by electricity
Implementation Method 2
The high pressure heated gas expands in the gas expander, generating shaft work and a drop in temperature
Implementation Method 3
The shaft rotates a power generator producing electricity
Implementation Method 4
The heated gas then enters an enclosed vessel
Data Source
AI summary
A method to pre-heat gas at gas Pressure Reducing Stations. A first step involve providing at least one electrical line heater having a flow path for passage of natural gas through electrical heating elements. A second step involves passing the high pressure cold natural gas stream along electrical heating elements and heating it up before de-pressurization. A third step involves the expansion of the high pressure heated gas in a enclosed vessel that houses a gas expander and power generator. The expansion of the gas generates shaft work which is converted into electrical power by the power generator and the expanded low pressure gas cools the power generator. This process results in the recovery of energy to replace the slipstream of natural that is presently used to pre-heat gas at Pressure Reduction Stations.