Autothermal Reforming Reactor Mixing System
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Solution Overview
Problem
At high pressures between 40 and 70 bars, conventional mixing and distribution systems for autothermal reforming of hydrocarbon feedstocks fail to achieve the necessary short residence times to prevent self-ignition and hydrogen yield degradation, especially when using pure oxygen as the oxidant.
Innovation Solution
A process involving the tangential injection of water vapor to create a swirl movement, combined with a multi-point network of injectors for homogeneous distribution, and the use of a single nozzle for hydrocarbon feed injection as a jet of droplets, ensures rapid and efficient mixing and distribution within the catalytic reactor, maintaining residence times below auto-ignition limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If conventional mixing and distribution systems are used at high pressures (40-70 bar), then the reactor can operate at high pressure for improved efficiency, but the residence time becomes too long causing auto-ignition and hydrogen yield degradation
Solution Approach 1:
The mixing and distribution function is segmented into multiple injection points arranged in a matrix pattern across the reactor cross-section. This segmentation allows the reactant mixture to be introduced at numerous locations simultaneously, dramatically reducing the residence time required for mixing and distribution while maintaining high pressure operation.
Solution Approach 2:
The injection system transitions from a single-point or linear arrangement to a two-dimensional matrix arrangement across the reactor cross-section. This dimensional change enables parallel introduction of the mixture at multiple locations, reducing the path length and time required for homogeneous distribution throughout the catalytic bed.
2Productivity
If pure oxygen is used as the oxidant at high pressure, then the reforming efficiency is improved, but the auto-ignition risk increases due to shortened ignition delay
Solution Approach 1:
The reactant mixture (hydrocarbon feedstock, water, and pure oxygen) is prepared and pre-mixed before introduction into the reactor. This preliminary mixing ensures homogeneous distribution of all components, including the pure oxygen, which prevents localized rich zones that could lead to auto-ignition while maintaining the high reforming efficiency enabled by pure oxygen.
Solution Approach 2:
Water acts as an intermediary substance in the mixture with pure oxygen and hydrocarbon feedstock. The water vapor helps control the combustion process by absorbing excess heat and preventing thermal runaway, thereby enabling the use of pure oxygen at high pressures without excessive auto-ignition risk while maintaining high reforming efficiency.
3Stability of the object's composition
If the mixing and distribution processes are extended to ensure thorough mixing, then homogeneity is improved, but the residence time increases allowing pre-combustion upstream of the catalytic zone
Solution Approach 1:
The mixing process is segmented into multiple simultaneous injection events at different locations across the reactor cross-section. This segmentation achieves homogeneous distribution of the reactant mixture throughout the catalytic zone without requiring extended mixing time, as all regions receive the mixture simultaneously through the distributed injection matrix.
Solution Approach 2:
The injection system utilizes pneumatic principles to introduce the reactant mixture through multiple nozzles arranged in a matrix pattern. The gas-phase oxygen and vaporized hydrocarbon feedstock are delivered under pressure through this distributed network, achieving rapid and homogeneous mixing throughout the reactor volume without extending the residence time.
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 prevents pre-combustion and maintains high hydrogen yield by ensuring efficient mixing and distribution, even at high pressures, thereby preventing soot formation and catalyst poisoning.
Implementation Method 1
the water vapor being injected tangentially to the reactor wall into the upper cylindrical part of the mixing chamber by the conduit, the velocities at the level of the steam injection being between 5 and 20 m/s so as to create a 'swirl' motion inside the mixing chamber
Implementation Method 2
vaporization of the hydrocarbon feed if it is liquid; efficient mixing of the reaction components, i.e. hydrocarbon feed, oxidant and vapor; the hydrocarbon feed being injected into the reactor inlet as a jet of droplets along the axis of the reactor by means of a single nozzle
Implementation Method 3
distribute the mixture obtained in step (a) homogeneously over the section of the reforming reactor before being pre-distributed according to step (b), by means of a packing
Implementation Method 4
d) distribute, in the presence of an autothermal reforming catalyst, the mixture obtained in step (c) homogeneously over the section of the reforming reactor by means of a packing; e) reform the mixture distributed in step (d) in the catalytic zone of the reforming reactor
Implementation Method 5
Partial oxidation (POX) is an exothermic reaction, sometimes catalyzed, that produces hydrogen (H2) through the reaction between the hydrocarbon feedstock and oxygen (O2)
Implementation Method 6
Steam reforming (SMR) is an endothermic reaction, also catalytic, that produces hydrogen through the reaction of the hydrocarbon feedstock with water (H2O)
Data Source
Figure 1(A)~1(B)
Figure 2
Figure 3~4
AI summary
The invention relates to a method for the autothermal reforming of a hydrocarbon feed in a catalytic reforming reactor, including the steps that consist of: a) mixing the hydrocarbon feed with water vapour, and vaporising the hydrocarbon feed if not already vaporised; b) pre-distributing the vaporised mix of hydrocarbon feed and water across the section of the reforming reactor using a multipoint injector network; c) injecting a gaseous oxidising flow, preferably pure oxygen, into the pre-distributed mixture from step (b) at the injectors from step (b); d) distributing, in the presence of an autothermal reforming catalyst, the mixture obtained in step (c) homogeneously across the section of the reforming reactor; and e) reforming the mixture distributed in step (d) in the catalytic zone of the reforming reactor.