Ammonia Vaporization Switching for Hydrogen Production Start-Up
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Solution Overview
Problem
Traditional hydrogen production methods face challenges in efficiently vaporizing ammonia during the start-up phase due to insufficient heat from effluent gases, particularly in low-temperature flue gas ducts, leading to inefficiencies in energy usage and hydrogen production.
Innovation Solution
A process utilizing multiple heating media, including steam and cracked gas, to vaporize ammonia, with a heat exchanger system that integrates steam and effluent gas heat exchange to optimize energy use and enhance hydrogen production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If waste heat from effluent gases is used to vaporize ammonia during normal operation, then energy efficiency is improved, but during start-up phase the flue gas temperature is too low to provide sufficient heat for vaporization
Solution Approach 1:
The patent introduces a preliminary heating stage using steam as the heating medium during the start-up phase, before the effluent gases reach sufficient temperature. This preliminary action ensures that ammonia vaporization can commence and continue smoothly until the waste heat recovery system becomes fully operational, thereby resolving the contradiction between energy efficiency and start-up reliability.
2Device complexity
If a single heating medium is used for ammonia vaporization, then the system is simpler, but it cannot adapt to different operational phases (start-up vs. normal operation)
Solution Approach 1:
The patent implements a dynamic heating system that automatically switches between steam and effluent gases as the heating medium based on the operational phase. During start-up, steam is used; during normal operation, effluent gases take over. This dynamic adaptation resolves the contradiction by allowing the system to optimize for simplicity when possible while maintaining adaptability when needed.
Solution Approach 2:
The heating system is designed to perform multiple functions using different heating media for different operational conditions. The same vaporization system can utilize either steam or effluent gases depending on the phase of operation, making it universally applicable across all operational scenarios while maintaining relatively simple overall system architecture.
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
Ensures effective ammonia vaporization throughout different operational phases, including start-up, optimizing energy usage and enhancing hydrogen production efficiency, with the potential to produce a pure hydrogen stream exceeding 90 mol% hydrogen.
Implementation Method 1
sending at least part of the liquid phase of the ammonia stream from the vaporizer to a first heat exchanger arranged to at least partially vaporize said liquid phase by heat exchange with the effluent gas
Implementation Method 2
vaporizing at least a portion of the ammonia stream, optionally by heating the ammonia stream with a heating medium
Implementation Method 3
optionally, performing a combustion to bring a heat input to the process
Data Source
Figure 1~2
Figure 3
AI summary
A process (100) for producing a hydrogen product (20) from a feedstock stream (10), the process (100) comprising the following steps: - discharging an effluent gas stream from the gas conversion unit (S12), - providing heat from the effluent gas to contribute to vaporize the ammonia stream (10) of the vaporizer (5), - wherein vaporizing at least a portion of the ammonia stream (10) in said vaporizer (5) (S2) comprises heating said portion of the ammonia stream (10) with a heating medium different from the effluent gas, - the process (100) further comprising sending the vaporized ammonia (14) from said vaporizer (5) as said feedstock stream (10) and/or sending the vaporized ammonia (14) from said vaporizer (5) as a fuel to said combustion.