Process and apparatus for cracking hydrocarbon gases
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Solution Overview
Problem
Current processes for cracking methane are energy-intensive, slow, and difficult to manage, requiring high temperatures and resulting in incomplete dissociation, with maintenance challenges due to carbon deposits, and lack a cost-effective method using solar energy.
Innovation Solution
A solar process for methane cracking using a receiver reactor with stratified temperature zones and a solid-state heat accumulator, where methane is heated incrementally and brought into contact with a reaction accelerator, achieving complete dissociation efficiently and reducing maintenance needs through the use of a cloud of particles or replaceable absorber elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high temperatures (500-1200°C) are used for methane cracking, then complete dissociation is achieved, but the process becomes energy-intensive and slow
Solution Approach 1:
The reactor is divided into multiple zones with different temperature levels (preheating zone, cracking zone, and cooling zone). Methane undergoes incremental heating through disc-shaped temperature zones rather than being exposed to uniform high temperatures throughout, reducing overall energy consumption while achieving complete dissociation in the cracking zone.
Solution Approach 2:
Different regions of the reactor are assigned different thermal characteristics. The preheating zone uses lower temperatures, the cracking zone maintains high temperatures for complete dissociation, and the cooling zone reduces temperatures. This localized temperature control optimizes energy usage by applying high heat only where necessary for the cracking reaction.
2Manufacturing precision
If high temperatures are maintained for complete dissociation, then reaction completeness improves, but reaction time increases indefinitely
Solution Approach 1:
Methane is preheated in the preheating zone before entering the cracking zone. This preliminary heating reduces the time required for complete dissociation in the high-temperature zone, as the methane molecules already possess thermal energy closer to the activation energy required for cracking, thereby reducing the theoretically infinite steady-state time.
Solution Approach 2:
The process rapidly passes methane through the high-temperature cracking zone to achieve complete dissociation before quickly cooling it in the cooling zone. This rushing through the critical high-temperature phase minimizes the time methane spends at temperatures where slow steady-state equilibrium would otherwise occur.
3Use of energy by moving object
If solar energy is used for methane cracking, then energy cost is reduced, but the process becomes difficult to manage and control
Solution Approach 1:
The patent introduces a heat carrier gas (such as CO2, steam, or nitrogen) as an intermediary between the solar radiation and the methane. The heat carrier absorbs solar energy in the absorption chamber and then transports this energy to heat the methane in the cracking zone. This intermediary system makes solar energy management more controllable and manageable compared to direct solar heating of methane.
4Productivity
If conventional cracking processes are used, then methane dissociation occurs, but carbon deposits require frequent maintenance
Solution Approach 1:
The harmful carbon deposits are extracted and removed from the reactor system through the cooling zone, where methane is cooled after cracking. The rapid cooling prevents carbon from redepositing on reactor walls and facilitates its removal with the product stream, reducing maintenance requirements while maintaining high dissociation efficiency in the cracking zone.
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
The process enables a highly efficient and complete methane dissociation with reduced energy input and maintenance requirements, allowing for continuous operation and overnight cracking, producing syngas for industrial fuel synthesis.
Implementation Method 1
an absorber region (9) which is located in the path of incident solar radiation (7), designed for absorption thereof
Implementation Method 2
which emits blackbody radiation upstream into the flow channel (2) during operation
Implementation Method 3
the hydrocarbon gas is heated to beyond its cracking temperature by absorption of blackbody radiation
Data Source
AI summary
Process for cracking hydrocarbon gases, wherein the hydrocarbon gas is passed through a flow channel of an absorptive receiver reactor (1, 30, 40), characterized in that cracking takes place during the passing through the receiver reactor (1, 30, 40), wherein in a first region (21) of the flow channel (2) the hydrocarbon gas is heated to its cracking temperature, in an adjoining second, downstream flow region (22) is heated to beyond its cracking temperature and in a third, further downstream region (23) of the flow channel is heated yet further and is brought therein into physical contact, over the cross-section of said region, with a reaction accelerator, after which the stream of products downstream of the reaction accelerator is discharged from the receiver reactor (1, 30, 40), and wherein the heating of the hydrocarbon gas to above its cracking temperature is achieved by absorption of blackbody radiation (20) which is given off by the reaction accelerator heated by solar radiation (7) incident thereupon to the hydrocarbon gas flowing towards it, in such a way that the hydrocarbon gas in the flow channel (2) and extending up to the reaction accelerator forms disc-shaped, consecutive temperature zones (60 to 67) of ever-increasing temperature extending transversely to the flow channel (2).