Hydrogen Generation System Liquid Heat Medium Temperature Control
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Solution Overview
Problem
The prior art systems face challenges in maintaining the dehydrogenation reaction temperature within an appropriate range when using exhaust gas as a heat source, leading to catalyst degradation and reduced reaction selectivity due to poor heat transfer efficiency and excessive temperature, resulting in undesired byproducts like benzene.
Innovation Solution
A system utilizing a liquid heat medium with a higher heat transfer coefficient to control the inlet, outlet, and temperature difference of the heat medium in the dehydrogenation reaction, along with steam generation units for efficient waste heat utilization, and a heating unit for adjusting the reaction temperature, ensuring stable and efficient hydrogen production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If exhaust gas is used as the heat source for the dehydrogenation reaction, then waste heat utilization is improved, but the heat transfer efficiency deteriorates leading to poor temperature control
Solution Approach 1:
A liquid heat medium is introduced as an intermediary between the exhaust gas and the dehydrogenation reaction system. The exhaust gas heats the liquid heat medium in a heat exchanger, and the heated liquid medium then transfers heat to the reaction mixture. This intermediary approach enables efficient waste heat utilization while providing stable temperature control through the superior heat transfer properties of liquids.
Solution Approach 2:
The system replaces direct gas-phase heat transfer with liquid-phase heat transfer. By substituting the exhaust gas (gas phase) with a liquid heat medium for the actual heat transfer to the reaction system, the invention exploits the higher heat transfer coefficient of liquids to achieve both energy efficiency and temperature stability.
2Productivity
If the temperature of the dehydrogenation reaction is increased to improve reaction rate, then productivity is improved, but catalyst degradation and coking worsen
Solution Approach 1:
The invention changes the thermal parameters of the heating system by using a liquid heat medium with controlled temperature and flow rate. This enables precise adjustment of the heat input to the dehydrogenation reaction, maintaining the temperature within the optimal range (350-380°C) that maximizes reaction rate while preventing catalyst degradation and coking that occur at excessive temperatures.
3Productivity
If the temperature of the dehydrogenation reaction is increased to improve hydrogen production efficiency, then productivity is improved, but reaction selectivity deteriorates producing undesired byproducts
Solution Approach 1:
By using a liquid heat medium with controllable temperature and flow rate, the invention enables precise control of the dehydrogenation reaction temperature within the optimal range. This parameter control ensures high reaction selectivity for hydrogen production while minimizing the formation of undesired byproducts such as benzene that occur at excessive temperatures.
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 allows for efficient and stable hydrogen production by maintaining the dehydrogenation reaction temperature within the desired range, minimizing catalyst degradation and improving reaction selectivity, while effectively utilizing waste heat and maintaining a stable hydrogen supply balance.
Implementation Method 1
a heat medium (in liquid form) demonstrating a higher heat transfer coefficient than the exhaust gas is used as the heat source for the dehydrogenation reaction
Implementation Method 2
it has become possible to control the inlet temperature of the heat medium entering the dehydrogenation reaction unit, the outlet temperature of the heat medium leaving the dehydrogenation reaction unit and the temperature difference of the heat medium as it enters and leaves the dehydrogenation reaction unit
Implementation Method 3
produces hydrogen by the dehydrogenation reaction of an organic hydride in the presence of a dehydrogenation catalyst
Implementation Method 4
a heating unit for adjusting the reaction temperature
Data Source
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AI summary
Provided is a system and a method which allow hydrogen to be produced both efficiently and in a stable manner when using exhaust gas produced by power generation as a heat source for the dehydrogenation reaction, controlling the temperature of the dehydrogenation reaction within an appropriate range. The system (1) for producing hydrogen comprises a dehydrogenation reaction unit (51) for producing hydrogen from an organic hydride by a dehydrogenation reaction in presence of a dehydrogenation catalyst; a first power generation unit (2) for generating electric power from energy of combustion gas produced by combustion of fuel; a waste heat recovery unit (3) for receiving heat from exhaust gas expelled from the first power generation unit; a heat exchanger (21) provided in the waste heat recovery unit for exchanging heat between the exhaust gas and a heat medium; and a circulation line (L1 - L3) for introducing the heat medium heated in the heat exchanger to the dehydrogenation reaction unit in liquid form, and returning the heat medium expelled from the dehydrogenation reaction unit to the heat exchanger; wherein the heat medium is introduced into the dehydrogenation reaction unit at an introduction temperature ranging between 352 °C and 392 °C, the heat medium is expelled from the dehydrogenation reaction unit at an expulsion temperature ranging between 337 °C and 367 °C, and a difference between the introduction temperature and the expulsion temperature ranges between 10 °C and 50 °C.