Fuel Cell Exhaust Gas Bypass Control for Water Recovery Balance
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Solution Overview
Problem
In fuel cell power generation systems using hydrocarbon gases like city gas, the inefficiency in water recovery and reuse leads to extra energy consumption, reducing overall system efficiency due to uncontrolled water recovery from exhaust fuel gas.
Innovation Solution
A fuel cell power generation system with a water recovery unit and bypass line, controlled by flow control valves, ensures the right amount of water is supplied to subsequent fuel cells, optimizing water usage and reducing external water supply needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the entire amount of exhaust fuel gas passes through the water recovery unit for water recovery, then water recovery amount increases, but the second fuel cell receives insufficient water for reforming reaction, requiring additional external water supply and extra energy consumption
Solution Approach 1:
The system dynamically adjusts the flow distribution between the water recovery unit and the second fuel cell using flow control valves. The opening degrees of the valves are controlled to optimize the balance between water recovery and water supply to the second fuel cell, allowing the system to adapt to varying operating conditions and fuel gas compositions.
Solution Approach 2:
The system changes the flow rate parameters of exhaust fuel gas to different destinations (water recovery unit vs. second fuel cell) based on operational requirements. By adjusting the flow rates dynamically, the system optimizes water recovery while ensuring adequate water supply for the reforming reaction in the second fuel cell.
2Loss of substance
If water is recovered from exhaust fuel gas by the water recovery unit, then water contained in exhaust fuel gas is removed, but the reforming reaction in the second fuel cell is hindered due to insufficient water
Solution Approach 1:
The flow control valves enable dynamic adjustment of exhaust fuel gas distribution, allowing the system to optimize the balance between water recovery and maintaining adequate water levels for the reforming reaction in the second fuel cell, thereby preserving power generation efficiency.
Solution Approach 2:
The system adjusts the flow rate parameters to ensure that the second fuel cell receives sufficient water for the reforming reaction while still achieving effective water recovery from the exhaust fuel gas, maintaining both water recovery and power generation efficiency.
3Quantity of substance
If additional water is supplied from outside to the second fuel cell after water recovery, then water necessary for reforming reaction is ensured, but system efficiency deteriorates due to extra energy consumption
Solution Approach 1:
The system dynamically controls the flow distribution to ensure the second fuel cell receives the necessary water for reforming reaction directly from the exhaust fuel gas, minimizing or eliminating the need for additional external water supply and reducing energy consumption.
Solution Approach 2:
The system optimizes the flow rate parameters to achieve the right balance between water recovery and water supply to the second fuel cell, ensuring adequate water for reforming reaction without requiring additional external water supply that would consume extra energy.
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 configuration enhances system efficiency by efficiently supplying water to subsequent fuel cells, minimizing energy consumption and improving overall system performance.
Implementation Method 1
a water recovery unit disposed on the exhaust fuel gas line, the water recovery unit being capable of recovering water contained in the exhaust fuel gas
Implementation Method 2
at least one flow control valve disposed on at least one of the exhaust fuel gas line or the bypass line; and a control unit capable of controlling an opening degree of the at least one flow control valve
Implementation Method 3
A fuel cell which generates electric power through chemical reaction of a fuel gas and an oxidizing gas
Data Source
AI summary
A fuel cell power generation system includes: a first fuel cell; and a second fuel cell connected to a downstream side of the first fuel cell via an exhaust fuel gas line, the second fuel cell being capable of generating electric power using an exhaust fuel gas from the first fuel cell. A water recovery unit is disposed on the exhaust fuel gas line, the water recovery unit being capable of recovering water contained in the exhaust fuel gas. A bypass line brings an upstream side and a downstream side of the exhaust fuel gas line with respect to the water recovery unit into communication. At least one flow control valve is disposed on at least one of the exhaust fuel gas line or the bypass line. A control unit controls an opening degree of the at least one flow control valve.