Light-Hydrocarbon Cracking Riser for Hydrogen and Solid Carbon
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Solution Overview
Problem
Current technologies for catalytic cracking of light hydrocarbons, such as steam methane reforming with or without carbon capture sequestration, produce carbon dioxide and are not cost-effective in producing high-quality hydrogen and value-added solid carbon, such as carbon nanotubes, with inefficient reactor designs and energy usage.
Innovation Solution
A reactor system and process that includes a riser for combusting spent catalyst to regenerate it and provide reaction heat, a separator to separate catalyst and gas effluents, and a heating unit to maintain an optimized temperature profile for catalytic cracking, utilizing renewable energy to minimize carbon dioxide generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If steam methane reforming is used to produce hydrogen, then hydrogen can be produced, but carbon dioxide is generated and carbon intensity is high
Solution Approach 1:
The patent converts the harmful solid carbon byproduct of hydrocarbon cracking into a beneficial heat source by combusting it in the riser. This regenerated heat then serves the cracking reaction, creating a self-sustaining process that eliminates CO2 emissions while producing hydrogen and valuable solid carbon products.
Solution Approach 2:
The spent catalyst stream containing solid carbon serves dual purposes: it is regenerated in the riser and simultaneously provides the heat required for the cracking reaction in the reactor. The system is self-sufficient, requiring no external fuel input as the solid carbon byproduct fuels its own process.
2Productivity
If conventional reactor designs are used for hydrocarbon cracking, then the process can operate, but energy efficiency is low and operating costs are high
Solution Approach 1:
The patent merges the catalyst regeneration function and the heating function into a single integrated riser unit. The solid carbon combustion that regenerates the catalyst also provides the necessary heat for cracking, eliminating the need for separate external heating systems and improving overall energy efficiency.
Solution Approach 2:
The riser serves multiple functions simultaneously: it regens the catalyst by combusting solid carbon, it heats the feedstock for cracking, and it maintains the thermal balance of the overall process. This multi-functionality reduces equipment complexity and energy consumption.
3Quantity of substance
If light hydrocarbons are cracked to produce hydrogen, then hydrogen is produced, but solid carbon byproduct must be managed
Solution Approach 1:
Instead of discarding the solid carbon as waste, the patent recovers it by combusting in the riser to generate heat. This recovered energy is then used to sustain the cracking reaction, turning a waste stream into a valuable resource that drives the process.
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
Produces high-quality hydrogen and value-added solid carbon efficiently with minimal carbon dioxide emissions, regenerating catalysts and utilizing solid carbon byproduct for reaction heat, thus overcoming energy inefficiencies and reactor design challenges.
Implementation Method 1
a riser operatively connected to a bottom portion of a reactor, the riser being configured to receive a first spent catalyst stream comprising catalyst particles and solid carbon flowing downwards from a reaction zone
Implementation Method 2
the heated catalyst solid stream flows downwards to the reaction zone in the reactor at a temperature sufficient to crack a light hydrocarbon feed stream flowing upwards in the presence of fresh catalyst
Implementation Method 3
a heating unit located internally in the reactor, the heating unit configured to heat the light hydrocarbon feed stream flowing upwards to produce a heated light hydrocarbon stream
Data Source
AI summary
A reactor system including a riser operatively connected to a bottom portion of a reactor, the riser being configured to receive a first spent catalyst stream comprising catalyst particles and solid carbon flowing downwards from a reaction zone in a top portion of the reactor and to combust the first spent catalyst stream to produce a mixture of a heated catalyst solid stream and a heated gas effluent, and a separator operatively connected to the top portion of the reactor and a top portion of the riser, the separator being configured to separate the heated catalyst solid stream from the heated gas effluent, wherein the heated catalyst solid stream flows downwards to the reaction zone at a temperature sufficient to crack a light hydrocarbon feed stream in the presence of fresh catalyst to produce a product effluent including hydrogen and a second spent catalyst stream.