Electrically Heated Reformer Tubes for Uniform Syngas Heating
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Solution Overview
Problem
Existing steam reforming processes face challenges in efficiently heating reformer tubes while minimizing physical loading and emissions, particularly due to the reliance on reformer burners which cause uneven heat distribution and reduce tube lifetime, and the use of fossil fuels leads to CO2 and NOx emissions.
Innovation Solution
Incorporating an electrically heatable heating element within the reformer tubes, such as inductively heatable or electrical resistance heating elements, allows for flexible and uniform heating, reducing physical stress on the tubes and improving temperature profiles, thereby enhancing catalyst efficiency and reducing methane slip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If reformer burners are used to heat the reformer tubes, then the necessary thermal energy for the endothermic reforming reaction is provided, but the reformer tubes experience excessive thermal loading and reduced lifetime
Solution Approach 1:
The heating function is segmented between external reformer burners and internal electric heating elements. The electric heating elements are distributed along the reformer tube length and divided into multiple heating zones, allowing localized temperature control and reducing peak thermal stress on any single tube section.
Solution Approach 2:
Electric heating elements serve as an intermediary heating mechanism between the external burners and the process materials. These elements transfer energy directly to the catalyst and gas/steam mixture through conduction and convection, reducing the need for excessive external heating and thereby protecting the reformer tubes from excessive thermal loading.
2Productivity
If reformer burners operate at full load to maximize synthesis gas production, then productivity increases, but thermal radiation causes uneven heat distribution and catalyst underutilization
Solution Approach 1:
Electric heating elements are distributed at specific locations along the reformer tube length, creating localized heating zones that match the catalyst bed distribution. This ensures uniform heat distribution throughout the catalyst volume, preventing cold spots and maximizing catalyst utilization while maintaining high productivity.
Solution Approach 2:
The patent replaces part of the external thermal radiation heating mechanism with internal electric heating elements. This substitution provides more direct and controllable heat transfer to the process materials, eliminating the uneven heat distribution caused by external thermal radiation while maintaining or enhancing synthesis gas production.
3Temperature
If natural gas is used as heating fuel in the reformer, then the endothermic reforming reaction is sustained, but CO2 and nitrogen oxides emissions increase
Solution Approach 1:
The patent substitutes electric heating elements for natural gas burners as the primary heating source. This replacement eliminates or significantly reduces the combustion of fossil fuels, thereby eliminating CO2 and NOx emissions associated with natural gas burning while maintaining the necessary reforming reaction temperature through electric heating.
Solution Approach 2:
The heating method is changed from chemical combustion (natural gas) to electrical heating. This parameter change in the energy source fundamentally alters the emission profile, eliminating harmful emissions while maintaining the thermal conditions required for the endothermic reforming reaction.
4Quantity of substance
If large tube diameter reformer tubes are used to accommodate more catalyst, then catalyst volume increases, but heat cannot reach the internal catalyst near the tube axis
Solution Approach 1:
The heating function is segmented into multiple electric heating elements positioned at different locations within or around the reformer tube. This segmentation allows heat to be introduced at multiple points along the tube length and radius, ensuring that even in large diameter tubes, heat reaches all catalyst regions including those near the tube axis that would otherwise be inaccessible to external heating.
Solution Approach 2:
Electric heating elements act as an intermediary heat transfer medium positioned closer to the catalyst bed than external burners. This intermediary placement enables more effective heat conduction and convection to the catalyst particles, including those in the central regions of large diameter tubes, thereby achieving uniform temperature distribution across the entire catalyst volume.
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 solution enables more effective utilization of catalysts with reduced thermal loading on reformer tubes, improving heat distribution and reducing methane slip, while also reducing the need for fossil fuels and associated emissions.
Implementation Method 1
an electrically heatable heating element (5) is disposed within the first reactor tube (2a)
Implementation Method 2
such as inductively heatable or electrical resistance heating elements
Implementation Method 3
the reformer burners, through the combustion of the air/natural gas mixture, transfer the heat by means of thermal radiation to the outer walls of the reformer tubes
Implementation Method 4
These subsequently transfer the heat by means of thermal conduction to the catalyst
Implementation Method 5
and subsequently by convection to the gas/steam mixture
Implementation Method 6
Disposed within the first reactor tube (2a) is a catalyst (3)
Implementation Method 7
methane is split by means of steam into hydrogen and carbon monoxide (and also, in part, CO2)
Data Source
AI summary
A reformer for steam reforming a hydrocarbon-containing mixture, including a combustion chamber, a burner arranged within the combustion chamber, a first reactor tube which is arranged at least in sections within the combustion chamber, a catalyst arranged inside the first reactor tube, and an electrically heatable heating element is arranged inside the first reactor tube.