Steam Reforming Feed Gas Coking Mitigation
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Solution Overview
Problem
Current steam reforming processes face challenges in minimizing coke formation in reformer tubes due to inadequate prediction and control of coking potential, particularly with unsaturated C2+ hydrocarbons, leading to equipment expenditure and operational inefficiencies.
Innovation Solution
Implementing a method that continuously measures the concentration of unsaturated C2+ hydrocarbons in the superheated feed gas before the main reforming stage, using online analysis methods, and adjusting the steam/carbon ratio and heat exchanger configurations to prevent coke deposition, potentially eliminating the need for a pre-reforming step and optimizing steam reforming conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a pre-reforming step is installed upstream of the main reformer, then coke deposit formation risk is reduced and energy consumption is lowered, but device complexity and equipment size increase
Solution Approach 1:
The patent implements online analytical measurement of unsaturated C2+ hydrocarbons in the superheated feed gas, creating a feedback loop that continuously monitors coking potential. Based on this real-time data, the steam flow rate is dynamically adjusted to maintain unsaturated C2+ hydrocarbon concentrations below 1% by volume, thereby preventing coke formation without requiring additional pre-reforming equipment.
Solution Approach 2:
The patent changes the operational parameters of the existing reforming process by controlling the steam flow rate through the feed gas superheater based on measured unsaturated C2+ hydrocarbon concentrations. This parameter adjustment allows the main reformer to operate without pre-reforming while maintaining low coking potential, thus avoiding increased device complexity.
2Object-affected harmful factors
If the concentration of unsaturated C2+ hydrocarbons is controlled below 1% by volume in the superheated feed gas, then coke formation is minimized, but measurement and control complexity increases
Solution Approach 1:
The patent replaces complex offline laboratory analysis methods with online analytical measurement systems that continuously monitor unsaturated C2+ hydrocarbon concentrations directly in the superheated feed gas. This substitution enables real-time detection without manual sampling and analysis, reducing the difficulty of measurement and control while maintaining precise monitoring of coking potential.
3Object-affected harmful factors
If steam flow rate is increased to reduce unsaturated C2+ hydrocarbon concentration, then coking potential is reduced, but energy consumption increases
Solution Approach 1:
The patent uses feedback control where the steam flow rate through the feed gas superheater is dynamically adjusted based on real-time measurements of unsaturated C2+ hydrocarbon concentrations. This ensures steam is added only to the extent necessary to maintain concentrations below 1% by volume, minimizing energy consumption while effectively reducing coking potential.
Solution Approach 2:
The patent applies partial action by adding steam only to the extent necessary to achieve the target concentration threshold rather than using excessive steam throughout the process. This optimized approach reduces energy consumption compared to conventional methods that use higher steam/carbon ratios, while still effectively controlling coking potential.
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 precise control of the reforming process, reducing coke formation, lowering equipment costs, and enhancing operational efficiency by accurately predicting and mitigating coking potential, thereby extending equipment lifespan and reducing energy consumption.
Implementation Method 1
The feed gas is heated to the steam reforming inlet temperature in a feed gas superheater
Implementation Method 2
injection of steam into the superheated feed gas in order to reduce the concentration of unsaturated C2+ hydrocarbons
Implementation Method 3
concentration of unsaturated C2+ hydrocarbons in the feed gas heated to the steam reforming inlet temperature is determined repeatedly by means of online analysis methods
Implementation Method 4
the hydrocarbon vapor mixture, after final heating to approximately 500 to 800 °C, enters the reformer tubes and is converted to carbon monoxide and hydrogen by the reforming catalyst
Implementation Method 5
this so-called steam reforming is the most widely used method for the production of synthesis gas... This process is strongly endothermic
Implementation Method 6
Heat is transferred to the reformer tubes via thermal radiation and convective heat transfer from the hot flue gases
Implementation Method 7
Heat is transferred to the reformer tubes via thermal radiation and convective heat transfer from the hot flue gases
Implementation Method 8
pre-reforming achieves reaction equilibrium at significantly lower temperatures. The main characteristic of pre-reforming is the irreversible, complete conversion of the higher hydrocarbons in the feedstock mixture to methane and, in some cases, to synthesis gas components
Data Source
Figure 1
Figure 2~3
AI summary
A process and a plant for producing a synthesis gas product containing hydrogen and carbon oxides are proposed, wherein, according to the invention, the concentration of unsaturated C2+ hydrocarbons in the feed gas is determined before its introduction into the main reforming stage, and water or cold steam is added to the feed gas if the determined concentration of unsaturated C2+ hydrocarbons exceeds a predefined maximum value.