Hydrogen Production via Tail Gas Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing processes for hydrogen production from hydrocarbon feedstocks are complex and costly, with inefficiencies in recycling tail gas from Fischer-Tropsch plants, particularly in integrating it effectively into separate hydrogen production plants.
Innovation Solution
The process involves passing hydrocarbon feedstock through sequential stages of steam methane reforming, water gas shift, and hydrogen separation, with tail gas from a separate diesel or gasoline production plant added downstream the steam methane reforming stage and upstream the water gas shift stage, optimizing the hydrogen production process by reducing capital costs and plant complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If tail gas is recycled to the ATR section to adjust H2/CO ratio, then the H2/CO ratio is optimized for FT synthesis, but the process complexity and capital costs increase
Solution Approach 1:
A water gas shift unit is introduced as an intermediary component between the tail gas recycling stream and the FT synthesis reactor. This unit converts CO and H2O into H2 and CO2, enabling precise adjustment of the H2/CO ratio without requiring complex blending systems or multiple recycling streams. The water gas shift unit acts as a mediator that simplifies the overall process architecture while achieving the desired compositional stability.
2Productivity
If tail gas is treated by sequential hydrogenation, steam reforming, and shift stages, then hydrogen production is maximized, but the plant complexity and investment costs increase
Solution Approach 1:
The tail gas is pre-treated in a water gas shift unit before entering the FT synthesis reactor. This preliminary action converts a portion of CO to H2, pre-adjusting the gas composition to be more suitable for FT synthesis. By performing this adjustment beforehand, the need for complex post-synthesis adjustments or multiple treatment stages is eliminated, simplifying the overall plant configuration while maintaining high hydrogen production efficiency.
3Productivity
If larger reforming sections and catalyst volumes are used, then hydrogen production capacity is increased, but capital costs and plant complexity increase
Solution Approach 1:
The process utilizes parameter changes in the water gas shift reaction to optimize hydrogen production. By controlling temperature, pressure, and catalyst composition in the water gas shift unit, the conversion of CO to H2 is maximized within a compact reactor design. This allows achieving high hydrogen production capacity without requiring excessively large reforming sections or catalyst volumes, as the shift reaction efficiently converts available CO to H2 under optimized conditions.
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 results in a more economical hydrogen production process with reduced capital costs and improved efficiency, as it allows for smaller reforming sections and catalyst volumes, enhancing hydrogen recovery and reducing undesirable off-gas production.
Implementation Method 1
passing the feedstock through the sequential stages of steam methane reforming
Implementation Method 2
water gas shift
Implementation Method 3
hydrogen separation
Data Source
Figure 1
AI summary
Process for producing hydrogen in which tail gas from a separate plant for production of gasoline or diesel is added downstream the steam methane reforming stage and upstream the water gas shift stage of a hydrogen production plant.