Oxy-Combustion System for Power Network Stabilization
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Solution Overview
Problem
Current electricity storage and management technologies face inefficiencies in peak demand stabilization and energy storage, particularly in systems relying on non-renewable energy sources for liquefied natural gas production and air separation, which affect power network stability and environmental sustainability.
Innovation Solution
A method involving a combined oxy-combustion cycle that uses liquefied natural gas to produce and store liquid oxygen and oxygen-depleted air, integrating air and refrigeration cycles with heat exchange steps to stabilize power networks and generate electricity, optionally producing liquefied natural gas, thereby addressing energy storage and peak demand management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional electricity storage technologies (batteries, flywheels, compressed air) are used, then energy storage capacity is achieved, but system complexity and cost increase
Solution Approach 1:
The patent combines multiple functions into a single integrated system: air separation, oxygen storage, refrigeration, and power generation are merged into one plant. The air separation unit produces liquid oxygen and oxygen-depleted air, which are stored in insulated vessels. During peak demand, liquid oxygen is vaporized and combusted with natural gas to generate electricity, while oxygen-depleted air is used for refrigeration to maintain storage temperatures.
Solution Approach 2:
The system performs multiple functions simultaneously: it separates air into oxygen and oxygen-depleted air, stores both products, generates electricity through combustion of stored oxygen with natural gas, and provides refrigeration using the expansion of oxygen-depleted air. This multi-functionality reduces the need for separate storage and generation systems.
2Loss of energy
If oxy-combustion cycle with Rankine steam cycle is used, then heat recovery is improved, but system complexity and efficiency loss at low temperature occur
Solution Approach 1:
The patent extracts the Rankine steam cycle from the oxy-combustion system, simplifying the overall process. Instead of using a complex Rankine cycle for heat recovery, the system directly expands combustion gases through a turbine and uses a simpler heat exchanger network to recover heat for preheating combustion air and condensing water vapor.
Solution Approach 2:
The system changes the operating parameters of the oxy-combustion cycle to optimize efficiency without requiring a Rankine cycle. By adjusting the pressure and temperature levels in the turbine expansion process and using direct heat exchange between exhaust gases and combustion air, the system achieves effective heat recovery with reduced complexity.
3Quantity of substance
If cryogenic air distillation is used for oxygen production, then large amounts of oxygen are produced, but energy consumption increases
Solution Approach 1:
The system performs preliminary air separation and oxygen liquefaction during off-peak hours when electricity demand and prices are lower. Liquid oxygen is produced and stored in insulated vessels for later use during peak demand periods, avoiding the need to produce oxygen on-demand when energy costs are higher.
Solution Approach 2:
The system uses its own oxygen-depleted air product to provide refrigeration for maintaining the liquid oxygen storage temperature. The expansion of oxygen-depleted air through a turbine or valve produces cold temperatures that are used to cool the liquid oxygen storage vessels, reducing the need for external refrigeration energy input.
4Power
If liquid air is pumped and heated for energy recovery, then power generation is achieved, but the process requires high pressure and complex heating stages
Solution Approach 1:
The patent merges the heating stages into a single integrated heat exchanger system that uses waste heat from the combustion process. Instead of requiring multiple separate heating stages, the liquid oxygen is heated in one continuous process using heat recovered from combustion exhaust gases, simplifying the overall heating process while maintaining power generation efficiency.
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 method achieves high efficiency in energy utilization, stabilizes power networks by managing excess energy, produces liquefied natural gas and high-pressure gaseous oxygen, and is environmentally sustainable by minimizing carbon dioxide release, with simpler technical processes compared to existing oxy-combustion and LAES technologies.
Implementation Method 1
During this step, at least a part or all of the liquefied natural gas is vaporized and fed into the network or, alternatively, stored
Implementation Method 2
integrating air and refrigeration cycles with heat exchange steps
Implementation Method 3
burning a fuel in an appropriate combustor in an atmosphere of CO2, H2O, and O2 at high pressure, with the conversion of the fuel and oxygen to carbon dioxide and water
Implementation Method 4
expanding the combustion gases in a machine which produces power and reduces the temperature of the combustion gases
Implementation Method 5
recovering heat from the exhaust fumes by means of a Rankine steam cycle
Implementation Method 6
condensing the water vapor from the fumes expanded in the preceding step
Implementation Method 7
re-compressing the exhaust fumes, consisting of CO2 and water, through a sequence of compression stages
Implementation Method 8
cryogenic air distillation is typically employed for large amounts
Data Source
AI summary
A system for storing or producing electricity, which allows stabilization of a power network under conditions of excess availability of electricity or lack thereof and for producing liquefied natural gas is provided.