Pre-wetting Fischer-Tropsch Catalyst to Control Temperature
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The Fischer-Tropsch process is challenging to start up due to the initial higher activity of new catalyst material, which can lead to over-conversion and temperature sensitivity, requiring careful control to maintain optimal operation conditions and desired hydrocarbon product selectivity.
Innovation Solution
Wetting an activated synthesis gas conversion catalyst in a fixed bed reactor with a liquid before contacting it with synthesis gas reduces the catalyst's initial activity by filling its pores, preventing hot spots and over-conversion, and controlling the synthesis gas partial pressure and temperature during start-up simulates steady-state conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If new catalyst material is used in the Fischer-Tropsch process, then the catalytic activity is initially higher, but this leads to over-conversion and temperature sensitivity issues
Solution Approach 1:
The catalyst is pre-wetted with liquid hydrocarbon before introducing synthesis gas into the reactor. This preliminary wetting action fills the catalyst pores with liquid, which then moderates the catalyst activity during the actual reaction process, preventing over-conversion and temperature spikes while maintaining high productivity
2Reliability
If the catalyst activity is reduced to prevent over-conversion, then temperature control is improved, but the hydrocarbon production rate decreases
Solution Approach 1:
Liquid hydrocarbon acts as an intermediary substance that fills the catalyst pores and moderates the catalyst activity. This intermediary allows the system to maintain both good temperature control and high hydrocarbon production rate simultaneously by preventing direct over-conversion while preserving catalytic functionality
3Loss of time
If synthesis gas is introduced directly to the activated catalyst, then the process starts quickly, but hot spots and over-conversion occur
Solution Approach 1:
The catalyst is pre-wetted with liquid hydrocarbon before synthesis gas introduction. This preliminary action prevents hot spots and over-conversion during start-up while maintaining quick process initiation, as the wetting step can be performed rapidly before gas flow is established
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 method effectively moderates the catalyst activity, preventing over-conversion and maintaining optimal temperature control, allowing for a smooth transition to steady-state operation with minimal initial conversion and high-quality steam production.
Implementation Method 1
contacting the activated catalyst with a liquid to obtain a wetted activated catalyst... filling its pores
Implementation Method 2
contacting the activated catalyst with a liquid to obtain a wetted activated catalyst... filling its pores
Implementation Method 3
catalytically converting the synthesis gas at an elevated temperature and pressure to obtain the normally gaseous, normally liquid and optionally normally solid hydrocarbons
Implementation Method 4
The Fischer-Tropsch reaction is very exothermic and temperature sensitive
Data Source
AI summary
The present invention provides a method to start a steady state process for producing normally gaseous, normally liquid and optionally normally solid hydrocarbons from synthesis gas, which method comprises the steps of: (i) providing an activated catalyst in tubes of a fixed bed reactor, preferably a multitubular fixed bed reactor, the catalyst being suitable to convert synthesis gas to normally gaseous, normally liquid and optionally normally solid hydrocarbons; (ii) contacting the activated catalyst with a liquid to obtain a wetted activated catalyst; (iii) contacting the wetted activated catalyst with synthesis gas and catalytically converting the synthesis gas at an elevated temperature and pressure to obtain the normally gaseous, normally liquid and optionally normally solid hydrocarbons.