Net Zero Ethane Cracker Using Hydrogen Fuel
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Solution Overview
Problem
Steam-cracking furnaces emit significant CO2 due to the combustion of methane in the tail gas, which can be reduced by eliminating or reducing methane from the fuel gas.
Innovation Solution
The method involves cracking ethane with steam to produce a cracked gas, separating hydrogen from the cracked gas to create a hydrogen-enriched stream, preheating combustion air, mixing the hydrogen-enriched stream with preheated combustion air, and burning the mixture in the furnace, thereby utilizing hydrogen as the primary fuel and minimizing CO2 emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If tail gas containing methane is burned as fuel in the furnace, then the furnace receives sufficient heat for cracking, but significant CO2 is released
Solution Approach 1:
The patent extracts and removes methane from the tail gas stream through a separation system before the gas is burned as fuel. This extraction of the harmful component (methane) allows the remaining hydrogen-rich gas to be used as a low-CO2 fuel source, resolving the contradiction between maintaining furnace temperature and reducing CO2 emissions
Solution Approach 2:
The patent converts the previously harmful methane-containing tail gas into a beneficial low-CO2 fuel source by removing methane and using the hydrogen-enriched gas for combustion. The tail gas that would have been a source of CO2 emissions is transformed into a clean fuel that provides necessary heat while minimizing carbon emissions
2Object-generated harmful factors
If hydrogen is separated from cracked gas and used as fuel, then CO2 emissions are reduced, but additional equipment and process complexity are required
Solution Approach 1:
The patent designs the separation system to serve multiple functions: it removes methane from tail gas, enriches hydrogen concentration for efficient combustion, and potentially prepares the gas for other uses. This multi-functionality justifies the added complexity by providing multiple benefits from a single integrated system
Solution Approach 2:
The system uses the tail gas itself as the feedstock for the separation process, and the separated hydrogen-rich gas automatically becomes the fuel source. The process is self-sufficient, using its own waste stream as the basis for creating a low-CO2 fuel source without requiring external hydrogen imports
3Object-generated harmful factors
If external hydrogen is imported to fuel the furnace, then CO2 emissions are reduced, but system cost and external dependency increase
Solution Approach 1:
The patent makes the system self-sufficient by using its own tail gas as the source of fuel hydrogen. The cracking process produces hydrogen as a byproduct, which is then separated and used to fuel the furnace. This eliminates the need for external hydrogen imports while maintaining low CO2 emissions, achieving both environmental and operational independence
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 reduces CO2 emissions by using high purity hydrogen as the primary fuel, achieving a low or zero carbon emission system, and eliminating the need for external hydrogen import by balancing the fired duty within the system.
Implementation Method 1
Heating the combustion air may include a resistive element transmitting electrical current to generate heat for heating the stream of air
Implementation Method 2
A common method of manufacturing light olefins is steam-cracking, where a hydrocarbon feed (e.g., ethane) is heated in a furnace to very high temperatures in the presence of steam. The high temperature cracks the hydrocarbons into smaller molecules
Implementation Method 3
mixing the hydrogen enriched stream with the preheated combustion air stream to create a combustion mixture, and burning the combustion mixture in the furnace
Data Source
AI summary
A system for controlling a steam cracking furnace may include a controller configured to control an electric heater to pre-heat a combustion air feed to a radiation section of the cracking furnace, and one or more sensors configured to sense properties of a recovered pure hydrogen stream fed to the radiation section of the cracking furnace as fuel. The controller can be configured to receive the sensed properties from the one or more sensors and control the electric heater based on the one or more sensed properties.