Fuel Cell Tail-Gas Carbon Capture for Hydrocarbon Cracking
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Solution Overview
Problem
Hydrocarbon cracking systems face challenges in reducing carbon emissions due to the presence of hydrogen in tail gases, which complicates carbon capture techniques and increases carbon dioxide concentrations in flue gases.
Innovation Solution
A process involving the separation of cracking product streams into hydrogen-rich methane and other streams, followed by the use of a fuel cell to convert methane and hydrogen into carbon dioxide and water, generating electricity and shifting carbon capture focus to the tail gas, thereby reducing flue gas carbon dioxide levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If carbon capture process is applied to furnace flue gas, then carbon dioxide is removed from flue gas, but the presence of hydrogen in tail gases complicates the carbon capture technique and increases carbon dioxide concentration in flue gases
Solution Approach 1:
The patent extracts the carbon capture function from the furnace flue gas system and relocates it to the fuel cell anode exhaust stream. By introducing a carbon capture process specifically针对 the fuel cell anode exhaust stream rather than the furnace flue gas, the system separates the carbon capture function from the complex furnace exhaust that contains hydrogen and other complicating factors.
Solution Approach 2:
The fuel cell acts as an intermediary device between the hydrocarbon cracking system and the carbon capture process. It converts methane and hydrogen from the tail gas into electricity while producing a concentrated carbon dioxide stream in its anode exhaust, which is then fed to the carbon capture process. This intermediary transformation simplifies the carbon capture task.
2Object-generated harmful factors
If traditional carbon capture is applied to furnace flue gas, then carbon dioxide is captured, but nitrogen-related issues complicate the carbon capture methods
Solution Approach 1:
The patent extracts the carbon capture operation from the nitrogen-rich furnace flue gas environment and relocates it to the fuel cell anode exhaust stream, which has significantly lower nitrogen content. This separation removes the carbon capture function from the problematic nitrogen-containing atmosphere.
Solution Approach 2:
The fuel cell serves as an intermediary that transforms the composition of the gas stream, converting methane and hydrogen into electricity and producing a carbon dioxide-rich exhaust with minimal nitrogen. This intermediary step eliminates nitrogen-related complications before the carbon capture process begins.
3Loss of energy
If fuel cell is used to convert methane and hydrogen, then electricity is generated and carbon emissions are reduced, but additional equipment is introduced to the system
Solution Approach 1:
The fuel cell utilizes the waste methane and hydrogen from the hydrocarbon cracking tail gas to generate electricity that can be used to power system equipment. The system serves itself by converting its own waste products into useful energy, reducing the need for external power sources and offsetting the added equipment complexity.
Solution Approach 2:
The patent converts the harmful methane and hydrogen in the tail gas, which were previously wasted or required special handling, into a beneficial source of electricity generation. This transformation turns environmental liabilities into energy assets, justifying the introduction of the fuel cell equipment.
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 effectively reduces carbon emissions by capturing carbon dioxide from the tail gas, generates electricity for system use, and avoids nitrogen-related issues that complicate traditional carbon capture methods.
Implementation Method 1
converting, at the anode of the fuel cell, methane and hydrogen received from the hydrogen-rich methane stream or from the methane product stream to carbon dioxide and water to generate electricity
Implementation Method 2
a separating element (e.g., a solid oxide element or a molten carbonate element) positioned between the anode and the cathode
Data Source
AI summary
Processes and systems that utilize a fuel cell for carbon capture from a petrochemical stream that contains hydrogen and methane. The petrochemical stream can be the tail gas of a hydrocarbon cracking system, or any other petrochemical stream containing hydrogen and methane. The petrochemical stream can be separated into a hydrogen product stream and a methane product stream, before sending the methane product stream to the fuel cell. The fuel cell converts methane to carbon dioxide and hydrogen to water, while generating electricity that can be used to power equipment.