Ammonia Cracking Temperature Control for Hydrogen Production
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Solution Overview
Problem
Existing processes for producing hydrogen by ammonia cracking face issues with carbon intensity control, leading to excessive furnace temperatures and undesirable byproduct steam production due to adjustments in fuel ratios.
Innovation Solution
A process that controls the cracking temperature and ammonia feed flow to optimize heat input, utilizing combusted unconverted ammonia and recycled ammonia to minimize ammonia consumption and achieve zero steam export, maintaining thermal efficiency and plant efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the ratio of tail gas to carbon-containing fuel is adjusted to control carbon intensity, then carbon intensity value is reduced, but furnace temperature becomes excessively high or byproduct steam production increases
Solution Approach 1:
The invention extracts and utilizes unconverted ammonia from the cracked gas stream as a dedicated fuel source for the endothermic cracking reaction. By separating and combusting the ammonia component specifically for heat provision, the process eliminates the need to adjust carbon-containing fuel ratios for carbon intensity control, thereby avoiding excessive furnace temperatures and unwanted steam generation.
Solution Approach 2:
The unconverted ammonia serves multiple functions: it is separated from the cracked gas, combusted to provide heat for the endothermic reaction, and its combustion products are integrated into the process. This multi-functional use of ammonia allows simultaneous carbon intensity reduction and thermal condition stabilization without requiring separate fuel ratio adjustments.
2Loss of substance
If the ratio of tail gas to carbon-containing fuel is adjusted to control carbon intensity, then carbon intensity value is reduced, but byproduct steam production increases
Solution Approach 1:
The invention extracts unconverted ammonia as a separate fuel component and combusts it specifically to provide heat for the cracking reaction. This dedicated ammonia combustion approach eliminates the need to adjust carbon-containing fuel ratios, thereby preventing undesirable increases in byproduct steam production while achieving carbon intensity reduction.
Solution Approach 2:
The unconverted ammonia, which would otherwise be a waste stream or require disposal, is converted into a valuable fuel source. By combusting this ammonia to provide process heat, the invention transforms a potential waste product into a beneficial thermal energy source, simultaneously reducing carbon intensity and avoiding steam generation issues.
3Use of energy by moving object
If cracking temperature is reduced to increase unconverted ammonia for fuel, then heat input requirement decreases, but hydrogen product amount decreases
Solution Approach 1:
The invention changes the operating parameters by reducing cracking temperature to increase unconverted ammonia concentration in the cracked gas. This parameter change is compensated by adjusting the ammonia feed rate, allowing the process to maintain hydrogen production levels while utilizing the increased ammonia for fuel to reduce overall heat input requirements.
Solution Approach 2:
The process implements feedback control where the cracking temperature and ammonia feed rate are adjusted based on the concentration of unconverted ammonia in the cracked gas. This feedback mechanism ensures that hydrogen production requirements are met while optimizing the amount of ammonia available for combustion as fuel.
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 process achieves lower ammonia conversion rates, minimizes byproduct steam generation, and operates at an optimal design point with minimal trim fuel, enhancing overall plant efficiency and hydrogen recovery.
Implementation Method 1
performing the endothermic cracking reaction of the ammonia feed, thereby producing a cracked gas containing hydrogen, nitrogen and unconverted ammonia
Implementation Method 2
combusting the separated unconverted ammonia in a combustion step to provide heat to the endothermic cracking reaction
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a process (100) for producing a hydrogen product (81) from an endothermic cracking reaction of an ammonia feed (4), comprising the following steps: - providing (S10) the ammonia feed to a cracking unit (210), - in said cracking unit, performing (S20) the endothermic cracking reaction of the ammonia feed, thereby producing a cracked gas (80) containing hydrogen (81), nitrogen (82) and unconverted ammonia (83), - in said cracking unit, combusting the separated unconverted ammonia in a combustion step (S40) to provide heat to the endothermic cracking reaction, - reducing (S50) a cracking temperature (Tc) of the endothermic cracking reaction, thus increasing the amount of unconverted ammonia in the cracked gas and to be combusted to provide heat to the endothermic cracking reaction, - controlling (S60) the flow of the ammonia feed directed to the cracking unit to produce a desired amount of hydrogen product (Psp).