Low-carbon Hydrogen Process with CO2 Separation
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Solution Overview
Problem
Current hydrogen production processes, such as fired steam methane reformers combined with water-gas shift and carbon dioxide removal, generate significant carbon dioxide emissions, making it challenging to achieve efficient CO2 capture and reduce environmental impact.
Innovation Solution
A process involving steam reforming of a hydrocarbon mixture in a gas-heated or adiabatic pre-reformer followed by autothermal reforming with an oxygen-rich gas, followed by water-gas shift stages, and an oxidation unit with a catalyst to convert carbon monoxide to carbon dioxide, allowing for efficient CO2 separation and reduced emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fired steam methane reformer combined with water-gas shift and carbon dioxide removal is used, then hydrogen production is achieved, but significant carbon dioxide emissions are generated
Solution Approach 1:
The patent extracts and separates carbon dioxide from the reformer effluent stream using a dedicated CO2 removal unit positioned between the reformer and the water-gas shift unit. This extraction of the harmful component before further processing enables hydrogen production while capturing CO2 for utilization or sequestration, directly resolving the contradiction between hydrogen production and CO2 emissions.
Solution Approach 2:
The patent introduces an intermediary CO2 removal unit that acts as a mediator between the steam methane reformer and the water-gas shift unit. This intermediary component removes CO2 from the gas stream, allowing the subsequent water-gas shift reaction to proceed efficiently while preventing CO2 from interfering with the hydrogen production process, thus resolving the contradiction.
2Measurement precision
If carbon dioxide removal is implemented, then carbon dioxide capture efficiency is improved, but process complexity increases
Solution Approach 1:
The patent segments the hydrogen production process into distinct units: steam methane reformer, CO2 removal unit, and water-gas shift unit. By segmenting the process and positioning the CO2 removal unit as a separate, dedicated component, the patent achieves efficient CO2 capture while maintaining clear process boundaries and operational simplicity, thus resolving the contradiction between capture efficiency and process complexity.
3Manufacturing precision
If pressure swing adsorption unit is used, then hydrogen purification is achieved, but high capital expenditure is required
Solution Approach 1:
The patent replaces the expensive pressure swing adsorption (PSA) unit with a simpler, more cost-effective CO2 removal unit followed by a water-gas shift unit. This substitution uses cheaper, readily available technologies to achieve the same hydrogen purification objective, significantly reducing capital expenditure while maintaining manufacturing precision, thus resolving the contradiction.
4Object-generated harmful factors
If CO2 emissions are reduced, then environmental impact is minimized, but operational flexibility is reduced
Solution Approach 1:
The patent implements a CO2 removal unit that can operate effectively across varying feedstock compositions and production rates. The unit is designed to handle different hydrocarbon feeds and maintain efficient CO2 capture regardless of operational conditions, thereby reducing CO2 emissions while preserving operational flexibility and adaptability, thus resolving the contradiction.
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 process significantly reduces CO2 emissions, eliminates the need for expensive pressure swing adsorption units, and provides a fuel-grade hydrogen product, enhancing operational flexibility and exergy efficiency, while enabling high-pressure hydrogen production for efficient fuel or feedstock utilization.
Implementation Method 1
subjecting a gaseous mixture comprising a hydrocarbon and steam to steam reforming in a gas-heated reformer or adiabatic pre-reformer
Implementation Method 2
followed by autothermal reforming with an oxygen-rich gas in an autothermal reformer
Implementation Method 3
autothermal reforming with an oxygen-rich gas
Implementation Method 4
increasing the hydrogen content of the reformed gas mixture by subjecting it to one or more water-gas shift stages
Implementation Method 5
passing the hydrogen-enriched reformed gas and an oxygen-rich gas to an oxidation unit containing an oxidation catalyst that converts carbon monoxide present in the hydrogen-enriched reformed gas to carbon dioxide
Implementation Method 6
oxidation catalyst that converts carbon monoxide present in the hydrogen-enriched reformed gas to carbon dioxide
Implementation Method 7
cooling the carbon dioxide-enriched gas mixture and separating condensed water therefrom
Data Source
AI summary
A process for the production of hydrogen comprising the steps of: (i) subjecting a gaseous mixture comprising a hydrocarbon and steam to steam reforming in reformer followed by autothermal reforming with an oxygen-rich gas to generate a reformed gas mixture, (ii) increasing the hydrogen content of the reformed gas mixture by subjecting it to one or more water-gas shift stages in a water-gas shift unit to provide a hydrogen-enriched reformed gas, (iii) passing the hydrogen-enriched reformed gas and an oxygen-rich gas to an oxidation unit containing an oxidation catalyst that converts carbon monoxide present in the hydrogen-enriched reformed gas to carbon dioxide, to form a carbon-dioxide enriched gas mixture, (iv) cooling the carbon dioxide-enriched gas mixture and separating condensed water therefrom, and (v) passing the carbon dioxide enriched gas mixture to a carbon dioxide separation unit to provide a carbon dioxide gas stream and a hydrogen product gas stream.