Off-Gas Cooling Medium for Reforming System Thermal Efficiency
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Solution Overview
Problem
Conventional reforming systems face limitations in thermal efficiency due to the wastage of thermal energy in cooling systems, as they rely on cooling water for heat exchange, which is not effectively utilized, leading to increased feed gas consumption and reduced hydrogen production efficiency.
Innovation Solution
A reforming system and method that utilizes off-gas as a cooling medium, where the off-gas from a Pressure Swing Adsorption (PSA) unit is reintroduced into a heat exchanger to exchange heat with the feed gas, thereby increasing the off-gas temperature and reducing the amount of feed gas needed for heating in the burner, enhancing thermal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If cooling water is used as the cooling medium in the heat exchanger, then the feed gas can be cooled effectively, but the thermal energy is wasted and not utilized
Solution Approach 1:
The patent recovers the thermal energy that would otherwise be discarded in the cooling water by using the off-gas as the cooling medium. The off-gas absorbs heat from the feed gas in the heat exchanger, increasing its temperature and making it suitable for combustion in the burner, thus converting waste thermal energy into useful heating energy.
Solution Approach 2:
The patent converts the harmful effect of thermal energy waste into a beneficial effect by using the hot off-gas as a cooling medium. The off-gas, which would normally be discarded or used directly in the burner, is first used to cool the feed gas, thereby converting the waste thermal energy into a useful resource for preheating the off-gas before combustion.
2Productivity
If the off gas is introduced into the burner directly without temperature increase, then the heating reaction can proceed, but additional feed gas must be supplied to increase the off gas temperature, deteriorating thermal efficiency
Solution Approach 1:
The patent performs preliminary heating of the off-gas by using it as the cooling medium in the heat exchanger. The off-gas absorbs heat from the hot feed gas before entering the burner, so it is already at a higher temperature when combusted, reducing the additional feed gas needed for heating.
Solution Approach 2:
The off-gas serves dual functions: it cools the feed gas in the heat exchanger and then serves as fuel in the burner. By using itself as the cooling medium, the system eliminates the need for separate cooling water and reduces the feed gas required for heating the off-gas before combustion.
3Loss of energy
If the off gas is used as the cooling medium in the heat exchanger, then the off gas temperature is increased and thermal efficiency is improved, but the system complexity increases
Solution Approach 1:
The off-gas line is configured to serve multiple functions: it transports off-gas from the PSA unit to the heat exchanger, uses the off-gas as the cooling medium in the heat exchanger, and then directs the heated off-gas to the burner. This multi-functional configuration reduces the need for separate cooling water systems and simplifies the overall thermal management.
Solution Approach 2:
The patent merges the cooling function and the heating function into a single integrated system. The off-gas cooling system is combined with the burner heating system, where the heated off-gas from the heat exchanger is directly fed to the burner, eliminating the need for separate cooling water circulation and heating systems.
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
The system increases hydrogen production efficiency by reducing the amount of feed gas consumed in the burner and improves overall thermal efficiency by utilizing waste heat from the cooling system, resulting in higher hydrogen purity and reduced energy costs.
Implementation Method 1
a heat exchanger connected to the compressor and configured to cool the feed gas, the temperature of which has been raised in a compression process, by a cooling medium including cooling water
Implementation Method 2
the heat exchanger utilizes the off gas as the cooling medium
Implementation Method 3
a reformer configured to generate a synthesis gas including hydrogen by reacting the feed gas, which passed through the heat exchanger, with water
Implementation Method 4
a pressure swing adsorption (PSA) unit configured to separate hydrogen from the synthesis gas generated by the reformer and discharge the off gas
Implementation Method 5
the fuel gas is burned by the burner and the reformer is heated to a temperature of 750 degrees or more to supply heat that is necessary for the reaction
Data Source
AI summary
Disclosed is a reforming system using an off gas as a cooling medium, which includes: a compressor configured to compress a feed gas; a cooling system a heat exchanger connected to the compressor and configured to cool the feed gas, the temperature of which has been raised in a compression process, by a cooling medium including cooling water; a reformer configured to generate a synthesis gas including hydrogen by reacting the feed gas, which passed through the heat exchanger, with water; a pressure swing adsorption (PSA) unit configured to separate hydrogen from the synthesis gas generated by the reformer and discharge the off gas; and an off gas line configured to feed the off gas discharged from the PSA unit to the heat exchanger such that the heat exchanger utilizes the off gas as the cooling medium.