Hydrogen Stream Production Using Condensate-Fed Autothermal Reforming
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Solution Overview
Problem
Existing methods for producing hydrogen result in significant carbon dioxide emissions due to the use of steam reforming and inefficient CO2 scrubbing, particularly in the production of synthesis gas for ammonia synthesis, leading to high residual emissions.
Innovation Solution
Increasing the molar steam-to-carbon ratio (S/C ratio) in autothermal reforming by using process condensate preheated with waste heat, combined with multiple-stage water-gas shift reactions and efficient CO2 scrubbing, to reduce methane slip and enhance CO2 recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam reforming is used to produce synthesis gas, then hydrogen production is achieved, but CO2 emissions increase significantly
Solution Approach 1:
The patent changes the fundamental parameter of the reforming process from steam reforming to autothermal reforming with catalytic partial oxidation. This parameter change allows hydrogen production while significantly reducing CO2 emissions by replacing the steam-based endothermic process with an oxidation-based exothermic process that uses process condensate instead of external steam generation.
2Loss of energy
If autothermal reforming is used to reduce CO2 emissions, then energy efficiency improves, but methane slip increases
Solution Approach 1:
The patent adjusts the steam-to-carbon ratio parameter in the autothermal reforming process by optimizing the amount of process condensate added. This parameter optimization ensures sufficient steam for the water-gas shift reaction while preventing excessive methane slip, achieving a balance between energy efficiency and methane management.
Solution Approach 2:
The patent implements a feedback mechanism where the off-gas from the PSA unit is used for preheating the synthesis gas before autothermal reforming. This feedback loop recycles hydrogen-rich gas to improve energy efficiency and reduce methane slip by optimizing the thermal conditions of the reforming process.
3Object-generated harmful factors
If CO2 scrubbing is implemented to capture CO2, then CO2 emissions are reduced, but process complexity increases
Solution Approach 1:
The patent extracts and removes CO2 from the synthesis gas stream using a CO2 scrubber positioned after the autothermal reforming unit. This extraction approach selectively captures CO2 while leaving the hydrogen-rich stream intact for PSA processing, achieving CO2 reduction with manageable process complexity by placing the scrubber at an optimal point in the flow sequence.
4Productivity
If high-pressure steam is generated for autothermal reforming, then the reforming process operates efficiently, but energy consumption increases
Solution Approach 1:
The patent applies self-service by using process condensate generated within the system itself as the steam source for autothermal reforming, rather than requiring external high-pressure steam generation. The condensate from the water-gas shift reaction and condensation stages is recycled back to provide the necessary steam, making the system energy-autonomous and eliminating the need for separate high-pressure steam generation 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
Reduces CO2 emissions by up to two-thirds while maintaining energy efficiency, eliminating the need for additional steam generation and natural gas combustion, and optimizing hydrogen production for ammonia synthesis.
Implementation Method 1
a synthesis gas reactor arrangement (4) for obtaining a synthesis gas stream (5) containing hydrogen and carbon oxides from a carbon-containing energy carrier stream (3) through autothermal reforming
Implementation Method 2
In autothermal reforming, in which the required temperature is generated by catalytic partial oxidation
Implementation Method 3
a shift device (15a-c) to which the synthesis gas stream (5) is fed, wherein in the shift device (15a-c) a water gas shift reaction takes place to convert at least a portion of the carbon monoxide of the synthesis gas stream (5) with steam of the synthesis gas stream (5) into carbon dioxide and hydrogen
Implementation Method 4
a carbon dioxide scrubber (30) arranged downstream of the shift device (15a-c) in terms of process technology for scrubbing at least part of the carbon dioxide from the synthesis gas stream (5)
Implementation Method 5
a saturation stage (11) arranged upstream of the synthesis gas reactor arrangement (4) in terms of process technology for supplying condensate (12) generated in the plant (2) and preheated with process waste heat to the energy carrier stream (3)
Implementation Method 6
the synthesis gas stream (5) is fed to a plurality of heat exchanger stages (22a-c) for cooling the synthesis gas stream (5)
Implementation Method 7
the purge stream (25) is used to underfire a plurality of gas-fired feedstock heaters (26a-d)
Data Source
Figure 1
AI summary
The invention relates to a method for providing a hydrogen stream (7) in a plant (2) for providing the hydrogen stream (7), wherein a carbon-containing energy carrier stream (3) is fed to a synthesis gas reactor arrangement (4) for obtaining a synthesis gas stream (5) comprising hydrogen and carbon oxides, wherein the synthesis gas reactor arrangement (4) obtains the synthesis gas stream (5) from the energy carrier stream (3) by autothermal reforming, wherein the synthesis gas stream (5) is fed to a shift device (15a-c), wherein a water gas shift reaction takes place in the shift device (15a-c) for converting at least part of the carbon monoxide of the synthesis gas stream (5) with steam of the synthesis gas stream (5) into carbon dioxide and hydrogen,wherein the synthesis gas stream (5) is fed downstream of the shift device (15a-c) to a carbon dioxide scrubber (30) for scrubbing at least a portion of the carbon dioxide from the synthesis gas stream (5), wherein a flash gas stream is released from a regeneration stage of the carbon dioxide scrubber (30), which flash gas stream is fed to a heating device of the plant (2) for underfiring, wherein the synthesis gas stream (5) is fed downstream of the carbon dioxide scrubber (30) at least partially to a separation arrangement (6) for separating the synthesis gas stream (5) at least into a hydrogen stream (7) containing hydrogen and into an exhaust gas stream (8) containing carbon oxides. The method is characterized in that the energy carrier stream (3) is fed to a saturation stage (11) before being fed to the synthesis gas reactor arrangement (4), in which saturation stage (11) preheated condensate (12) is added to the energy carrier stream (3),which has accrued in the plant (2), and that a vapor content of at least 80% of the synthesis gas stream (5) is already present when fed to the shift device (15a-c) when the synthesis gas stream (5) exits the synthesis gas reactor arrangement (4). The invention also relates to a corresponding plant (2) for providing a hydrogen stream (7),