Pressure Reduction System Using Electrolyser for Energy Recovery
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Solution Overview
Problem
The existing pressure reduction technologies in natural gas pipelines, such as Joule Thomson valves, result in significant energy loss and increased carbon footprint due to the need for preheating, which is inefficient and environmentally harmful, while turbo expanders face challenges with intermittent energy production and geographical limitations for energy export and storage.
Innovation Solution
A system incorporating a load-following proton exchange membrane electrolyser and heat pump that converts electrical energy from gas expansion into hydrogen, using waste heat for preheating and eliminating the need for external electrical substation connections, thereby reducing carbon footprint and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If Joule Thomson valves are used for pressure reduction, then pressure is reduced from 60-80 bar to household mbar pressure, but significant mechanical energy is lost and preheating is required due to temperature drop
Solution Approach 1:
The patent replaces the traditional Joule Thomson valve (mechanical pressure reduction device) with an electrolyser system that uses electrical energy from gas expansion to drive water electrolysis. This substitution converts the wasted mechanical energy into useful chemical energy (hydrogen) while eliminating the need for separate preheating equipment.
Solution Approach 2:
The patent changes the operating parameters by using the temperature and pressure conditions during gas expansion to drive the electrolysis process. The expanding gas directly powers the electrolyser, transforming the thermodynamic parameters (pressure, temperature) into electrical energy for hydrogen production, thereby resolving the energy loss issue.
2Reliability
If preheating is used to prevent condensation and freezing, then equipment damage and pipe blockage are avoided, but gas consumption and CO2 release increase
Solution Approach 1:
The system uses the own expanding gas to power the electrolyser, which in turn generates heat through the electrolysis process. This self-contained system eliminates the need for external fuel consumption for preheating, reducing carbon emissions while maintaining equipment protection.
Solution Approach 2:
The patent converts the previously harmful effect (cold expanding gas causing condensation and freezing) into a beneficial effect by using the expansion energy to drive electrolysis. The process transforms the cold gas that would cause problems into a power source for hydrogen production and heat generation.
3Loss of energy
If turbo expanders are used to recover energy, then electrical energy is generated, but the PRS needs to be in close proximity to an electrical substation with sufficient generation capacity
Solution Approach 1:
The patent introduces hydrogen as an intermediary energy carrier between the gas expansion process and the final energy utilization. The electrolyser converts expansion energy into stored chemical energy (hydrogen), which can be transported and used anywhere without requiring proximity to electrical substations, thus eliminating geographical constraints.
Solution Approach 2:
The system operates periodically based on gas flow conditions, using the expanding gas whenever available to drive the electrolyser. This periodic operation allows flexible deployment without requiring continuous connection to electrical infrastructure, reducing geographical limitations.
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 solution enables efficient energy recovery and reduction in carbon emissions by utilizing hydrogen produced from electrolysis for preheating, allowing for decentralized operation and significant cost savings, while meeting the energy demands of the gas grid with low-carbon hydrogen injection.
Implementation Method 1
an electrolyser that produces hydrogen
Implementation Method 2
a heat pump, a heat exchanger through which natural gas flows on one half and heating fluid flows on the other half
Implementation Method 3
a heat exchanger through which natural gas flows on one half and heating fluid flows on the other half, such that the heat exchanger is adapted to heat the natural gas
Implementation Method 4
a device adapted to extract energy from expansion of the natural gas
Implementation Method 5
the extracted energy is used to power the electrolyser and the heat pump, and wherein the heating fluid is heated by the heat pump and waste heat from the electrolyser
Data Source
Figure 1~2
Figure 3
AI summary
A system for reducing pressure and extracting energy from natural gas pipelines or the cryogenics industry comprises an electrolyser that produces hydrogen, a heating device adapted to heat the natural gas in the pipeline and a device adapted to extract energy from expansion of the natural gas, wherein the extracted energy is used to power the electrolyser and/or heat the natural gas. The system can be used to extract energy from gas expansion.