Hydrogen Generator Valve Prevents Recycled Gas Backflow
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Solution Overview
Problem
Conventional hydrogen generating apparatuses face issues with backflow of raw material into the recycled gas flow path due to low flow rates, leading to poisoning of the catalysts and fuel cells, as the Venturi effect is insufficient to draw hydrogen-containing gas when the raw material flow rate is below a certain threshold.
Innovation Solution
Incorporating a valve in the recycled gas flow path that closes when the raw material flow rate into the ejector is lower than a predetermined rate, preventing backflow and ensuring reliable operation by maintaining the Venturi effect for hydrogen gas recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the raw material flow rate into the ejector is reduced, then energy consumption is reduced, but the Venturi effect becomes insufficient and hydrogen-containing gas cannot be drawn properly
Solution Approach 1:
The valve is positioned upstream in the raw material feed path to preemptively control the flow rate before it reaches the ejector. By closing the valve when flow rate drops below the threshold, the system prevents the condition where the ejector would fail to draw hydrogen-containing gas, rather than reacting after the failure occurs.
Solution Approach 2:
The control unit continuously monitors the raw material flow rate and provides feedback control by adjusting the valve position. When the flow rate falls below the predetermined threshold necessary for proper Venturi effect operation, the control unit closes the valve to maintain optimal operating conditions.
2Productivity
If the raw material flow rate is maintained above a predetermined threshold, then the Venturi effect operates properly and hydrogen-containing gas is drawn effectively, but the system cannot operate efficiently at low flow rates
Solution Approach 1:
The system dynamically adjusts the valve opening based on the required flow rate conditions. When high hydrogen-containing gas recycling is needed, the valve remains open to maintain sufficient flow rate for the Venturi effect. When lower flow rates are acceptable or during shutdown, the valve closes to reduce raw material consumption and energy usage.
Solution Approach 2:
The control unit changes the flow rate parameter by adjusting the valve position. By maintaining the raw material flow rate above the predetermined threshold only when necessary for effective hydrogen-containing gas drawing, the system optimizes the balance between recycling efficiency and energy consumption.
3Reliability
If the valve closes the recycled gas flow path at low flow rates, then backflow of raw material is prevented and catalyst poisoning is avoided, but the hydrogen-containing gas recycling is interrupted
Solution Approach 1:
The valve closure, which interrupts hydrogen-containing gas recycling, converts a potentially harmful situation (raw material backflow causing catalyst poisoning) into a controlled shutdown. By preventing backflow at low flow rates, the system protects the catalyst from sulfur compound poisoning, which would cause much more severe and permanent damage to the reforming catalyst and fuel cell stack catalyst.
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 effectively prevents backflow and maintains the reliability and stability of the hydrogen generating apparatus and downstream fuel cell systems by ensuring the hydrogen gas is recycled efficiently, even at low raw material flow rates, thereby preventing catalyst poisoning and ensuring long-term operation.
Implementation Method 1
the hydrogen-containing gas is drawn by a Venturi effect by the ejector
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A hydrogen generating apparatus includes: hydrodesulfurizer (2) for reducing a concentration of a sulfur compound contained in raw material fed from a raw material feed path; reformer (1) for reforming the raw material discharged from hydrodesulfurizer (2) to generate hydrogen-containing gas; and recycled gas flow path (3) for feeding a part of the hydrogen-containing gas discharged from reformer (1) to the raw material feed path. The hydrogen generating apparatus further includes: ejector (4) provided at a junction of the raw material feed path and recycled gas flow path (3), and configured to draw the hydrogen-containing gas from recycled gas flow path (3) into the raw material feed path; and valve (5) provided in recycled gas flow path (3) to close when the raw material flowing into the ejector (4) is not larger than a predetermined flow rate. In this way, it is possible to achieve hydrogen generating apparatus (100) in which backflow in recycled gas flow path (3) is prevented.