Method and system for starting up a distillation tower
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Solution Overview
Problem
Conventional distillation technologies face challenges in achieving appropriate temperature and composition profiles during the startup of a distillation tower, leading to potential solid formation and accumulation issues that interfere with the separation of methane from contaminants like CO2, particularly at cryogenic temperatures.
Innovation Solution
A method and system that involves maintaining a rectifier section and a lower section in the distillation tower, where the lower section forms solids from contaminants, and methane is directly fed to the rectifier section or its outlet line when contaminant concentrations are outside a predetermined range, ensuring optimal connection and operation without solid migration or accumulation in the controlled freeze zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cryogenic distillation is used to separate CO2 from methane, then separation effectiveness is improved, but solid formation occurs outside the controlled freeze zone section interfering with proper operation
Solution Approach 1:
The patent applies preliminary action by establishing appropriate temperature and composition profiles during the startup phase before normal operation begins. The system pre-cools sections and introduces feed at controlled rates to ensure that when full operation starts, solids form only in the designated freeze zone section rather than elsewhere in the tower.
Solution Approach 2:
The patent employs dynamics by making the temperature and composition profiles adjustable during startup. The system dynamically controls feed rate, reflux ratio, and section temperatures to adapt to changing conditions during startup, ensuring proper solid formation location is maintained as the system transitions to normal operation.
2Manufacturing precision
If cryogenic distillation is used to separate CO2 from methane, then separation effectiveness is improved, but undue accumulation of solids occurs in the controlled freeze zone section
Solution Approach 1:
The patent applies parameter changes by controlling the temperature profile and composition distribution in the freeze zone section. By adjusting these parameters during startup, the system optimizes the rate of solid formation to match the melting capacity of the melt tray assembly, preventing undue accumulation while maintaining effective separation.
Solution Approach 2:
The patent utilizes phase transitions by controlling the freezing and melting processes in the controlled freeze zone section. The system manages the phase change of CO2 from vapor to solid in the freeze zone, then melts these solids on the melt tray assembly, creating a controlled cycle that prevents accumulation while maintaining separation effectiveness.
3Productivity
If startup is accelerated to reduce time, then productivity is improved, but appropriate temperature and composition profiles are not achieved leading to solid formation issues
Solution Approach 1:
The patent applies preliminary action by performing essential cooling and profile establishment steps before initiating full feed introduction. The system pre-cools the tower sections and establishes baseline temperature profiles in advance, allowing faster subsequent startup without compromising the accuracy of final temperature and composition profiles.
Solution Approach 2:
The patent maintains continuity of useful action by overlapping cooling, feed introduction, and profile adjustment operations. Rather than completing one step fully before starting the next, the system continuously adjusts multiple parameters simultaneously, maintaining productive action throughout the startup process while ensuring proper profiles are achieved.
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 the achievement of appropriate temperature and composition profiles, ensuring effective separation of methane from contaminants and preventing solid-related operational issues during startup and normal operation of the distillation tower.
Implementation Method 1
The separation of CO2 from methane by distillation involves temperature and pressure conditions that result in solidification of CO2 if a pipeline or better quality hydrocarbon product is desired. The required temperatures are cold temperatures typically referred to as cryogenic temperatures.
Implementation Method 2
Conventional distillation principles and conventional distillation equipment are predicated on the presence of only vapor and liquid phases throughout the distillation tower.
Data Source
AI summary
The present disclosure provides method for clean methane startup of a distillation tower. The method includes maintaining a rectifier section and a lower section in the distillation tower, feeding stream to the lower section, directly feeding methane to at least one of the rectifier section and a rectifier section outlet line of the rectifier section when a contaminant concentration of the contaminant exiting as a vapor in an upper portion of the lower section is outside of a predetermined concentration and introducing the vapor from the lower section to the rectifier section when the contaminant concentration exiting the upper portion of the lower section is within the predetermined concentration.