Hydrogen Plant Low-Temperature CO2 Removal With Integrated Drying
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Solution Overview
Problem
Existing hydrogen production processes face inefficiencies in integrating low temperature CO2 removal from off-gas, particularly in the hydrogen purification unit, which requires drying before cryogenic separation and involves high energy consumption and large equipment sizes.
Innovation Solution
A plant and process that integrates a reforming unit, shift section, hydrogen purification, and low temperature CO2 removal, utilizing a drying unit with heat exchange to preheat regeneration gas, reducing energy consumption and equipment size, and recycles CO2-depleted off-gas for further use in the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If off-gas is dried before feeding to cryogenic CO2 separation unit, then CO2 removal efficiency is improved, but energy consumption increases due to additional drying requirements
Solution Approach 1:
The patent combines the drying function and CO2 separation function into a single integrated unit. The absorbent material performs both water adsorption and CO2 absorption simultaneously, eliminating the need for a separate drying unit and its associated energy consumption while maintaining CO2 removal efficiency
Solution Approach 2:
The absorbent bed is designed to perform multiple functions: drying the off-gas and separating CO2. This multi-functional approach replaces the conventional two-unit sequence (drier + CO2 separator) with a single unit that accomplishes both tasks, reducing overall system energy requirements
2Reliability
If conventional drying unit is used before CO2 separation, then off-gas is properly dried, but equipment size increases
Solution Approach 1:
The patent merges the drying unit and CO2 separation unit into a single absorbent bed system. This integration eliminates the need for separate equipment, reducing the total equipment volume while ensuring proper off-gas drying through the same absorbent material that subsequently captures CO2
3Measurement precision
If off-gas is compressed and dried before CO2 removal, then CO2 separation is improved, but both energy consumption and equipment complexity increase
Solution Approach 1:
The patent combines multiple process functions (drying and CO2 separation) into a single integrated absorbent bed system. This reduces process complexity by eliminating intermediate steps and equipment while maintaining effective CO2 separation performance through the dual-function absorbent material
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 integration reduces energy consumption, minimizes equipment size, and enhances CO2 capture efficiency while lowering carbon emissions and hydrocarbon feed consumption.
Implementation Method 1
a heat exchanging unit which is arranged to preheat the inlet regeneration gas stream (19) by indirect cooling of a heat exchanging medium selected from any of: steam (13'') from said steam header, syngas stream (3), shifted syngas stream (5)
Implementation Method 2
preheating the inlet regeneration gas stream (19) by indirect cooling of a heat exchanging medium
Implementation Method 3
a drying unit (190) arranged to receive the compressed CO2-rich off-gas stream (9') and provide a dried compressed CO2-rich off-gas stream (9'')
Implementation Method 4
a low temperature CO2-removal section (180) arranged to receive said dried compressed CO2-rich off-gas stream (9'') for removal of CO2
Implementation Method 5
low temperature CO2 removal from off-gas, particularly in the hydrogen purification unit, which requires drying before cryogenic separation
Data Source
AI summary
A plant and process for producing a hydrogen rich gas are provided, said process including the steps of: steam reforming a hydrocarbon feed into a synthesis gas; shifting the synthesis gas and conducting the shifted gas to a hydrogen purification unit, subjecting CO2-rich off-gas from the hydrogen purification unit to a carbon dioxide removal in a low temperature CO2-removal section and recycling CO2-depleted off-gas rich in hydrogen to the process. A drying unit upstream the CO2-removal section is provided, under the addition of regeneration gas produced in the plant and process.