On-Board Flex-Fuel H2 Generator Using Parallel Autothermal Reformers
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Solution Overview
Problem
Current on-board hydrogen generators for internal combustion engines and gas turbines face challenges such as coke formation, bulky designs, and short operational life due to uncontrolled O2/C, H2O/C, and CO2/C ratios, leading to inefficient hydrogen production and reduced engine efficiency.
Innovation Solution
The development of an on-board Flex-Fuel H2 Generator using parallel autothermal reformers with supported Pt group metal catalysts, an automatic control system, and precise flow control to maintain optimal ratios, allowing self-startup without external heat or power, and storing high-pressure reformate for efficient combustion and catalyst regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If on-board hydrogen generators are designed to be compact, then space utilization is improved, but hydrogen production efficiency deteriorates
Solution Approach 1:
The reformer is divided into multiple reaction zones (partial oxidation zone, steam reforming zone, water-gas shift zone) arranged in series, allowing each zone to perform a specific function efficiently within a compact volume. This segmentation enables high hydrogen production efficiency without increasing overall reformer size.
2Productivity
If O2/C ratio is increased to improve hydrogen production rate, then productivity is improved, but coke formation increases
Solution Approach 1:
Different O2/C ratios are applied in different reaction zones: higher O2/C ratio in the partial oxidation zone to maintain high temperature and productivity, and lower or zero O2/C ratio in the steam reforming and water-gas shift zones to prevent coke formation. This local differentiation of composition enables both high productivity and low coke formation.
3Productivity
If reformer operating temperature is increased to improve hydrogen production efficiency, then productivity is improved, but catalyst durability deteriorates
Solution Approach 1:
The reformer is segmented into zones with different temperature profiles: the partial oxidation zone operates at high temperature (800-1000°C) for efficient hydrogen production, while subsequent zones operate at progressively lower temperatures, protecting the catalyst from excessive thermal degradation and extending its durability.
4Object-generated harmful factors
If steam reforming is used to prevent coke formation, then harmful factors are reduced, but additional water supply infrastructure is required
Solution Approach 1:
The reformer system is designed to accept various fuel types (natural gas, propane, butane, gasoline, diesel, alcohol) and adaptively adjust operating parameters including water-to-fuel ratios. This multi-functionality allows steam reforming to prevent coke formation across different fuel types without requiring separate water supply infrastructure for each fuel type.
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 solution extends the durability and service life of the hydrogen generator by preventing coke formation, improving engine efficiency, reducing emissions, and enabling flexible operation under varying load conditions, while maintaining catalyst durability and reducing pollutant emissions.
Implementation Method 1
reacting the stream of inlet fuel mixture over the catalysts inside the ATR reformer with the system's own heat and electricity to produce a reformate containing H2 and CO from fuels
Implementation Method 2
autothermal (ATR) reformers for producing H2 and CO from hydrocarbons and/or bio-fuels
Implementation Method 3
steam reforming reactions of hydrocarbons over the Ni/Al2O3 pellet catalyst
Implementation Method 4
The produced reformate will be cooled, the condensed water will be recycled as one of the ATR reactant and the dry gas will be compressed and stored
Data Source
AI summary
An on-board Flex-Fuel H2 Generator provides devices and the methods of operating these devices to produce H2 and CO from hydrocarbons and bio-fuels. One or more parallel autothermal reformers are used to convert the fuels into H2 over the Pt group metal catalysts without external heat and power. The produced reformate is then cooled and the dry gas is compressed and stored in vessels at a pressure between 1 to 100 atmospheres. For this system, the pressure of the storage vessels and the flow control curves are used directly to control the amount of the reformers' reformate output. To improve thermal efficiency of a mobile vehicle or a distributed power generator, a portion of the reformate from the storage vessels is used to mix with the primary fuels and air as part of a lean burn fuel mixture for the engine/gas turbine. Also, this on-board Flex-Fuel H2 Generator can provide H2 to regenerate the NOx and diesel particulate traps for diesel engines, and/or it can provide H2 for a mobile or a portable fuel cell power generator.