Liquid Recovery Dehydration Loop to Prevent Hydrates and Flaring
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Solution Overview
Problem
The formation of hydrates in liquid recovery systems during startup and shutdown poses operational challenges, leading to delays, mechanical malfunctions, and environmental harm due to the flaring of moisture-rich sweet gas, which is inefficient and wasteful.
Innovation Solution
A method involving the circulation and recycling of dry sweet gas through chilldown trains and a dehydrator, using dry regeneration gas to manage moisture levels, reducing the need for flaring by absorbing excess water within the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dry sweet gas is used to dry the liquid recovery system during startup and shutdown, then hydrate formation is prevented, but the moisture-rich gas must be flared which causes environmental harm and resource waste
Solution Approach 1:
The patent recovers the moisture-rich sweet gas that would otherwise be flared by routing it through a dehydration unit (molecular sieve or glycol dehydrator) to remove water, then compressing and recycling it back to the system inlet. This transforms waste gas into a useful resource, eliminating greenhouse emissions while maintaining hydrate prevention
Solution Approach 2:
The patent introduces a dehydration unit as an intermediary between the chilldown train and the compressor. This intermediate device removes moisture from the sweet gas, enabling it to be recycled without causing hydrate formation or environmental harm, thus mediating between the conflicting requirements of hydrate prevention and emissions reduction
2Reliability
If methanol is used to dissolve hydrates, then hydrate formations are broken down, but additional operational costs and complexity are introduced
Solution Approach 1:
The patent implements a self-service system where dry sweet gas is continuously circulated through the liquid recovery system during startup and shutdown, automatically absorbing moisture and preventing hydrate formation without requiring external chemical intervention. The system uses its own operational gas flow to maintain dry conditions, eliminating the need for methanol injection infrastructure and operational complexity
3Reliability
If sweet gas absorbs moisture during the drying process, then the liquid recovery system is dried, but the gas fails to meet quality standards and must be flared
Solution Approach 1:
The patent recovers the moisture-rich sweet gas by routing it through a dehydration unit that removes water using molecular sieves or glycol dehydrators. The dehydrated gas is then compressed and recycled back to the system inlet, transforming what would be waste into a valuable resource and eliminating the need for flaring
Solution Approach 2:
The patent establishes a continuous recycling loop where sweet gas is continuously dehydrated, compressed, and returned to the system. This continuous circulation ensures the liquid recovery system remains dry while preventing gas waste, maintaining both drying effectiveness and resource conservation throughout the startup and shutdown processes
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
Reduces the amount of flared gas significantly, maintaining operational efficiency while adhering to environmental standards by effectively managing moisture and preventing hydrate formation.
Implementation Method 1
dry sweet gas may be employed during both the startup and shutdown phases of the liquid recovery system
Implementation Method 2
introducing the first intermediate stream and a dry regeneration gas into a dehydrator to produce a second intermediate stream
Data Source
AI summary
Methods for removing water from liquid recovery systems may comprise introducing a dry sweet gas into a first chilldown train to produce a first intermediate stream; introducing the first intermediate stream and a dry regeneration gas into a dehydrator to produce a second intermediate stream; introducing the second intermediate stream into a second chilldown train to produce a third intermediate stream; introducing the third intermediate stream into a third chilldown train to produce a first recycle stream; introducing the first recycle stream into the second chilldown train and withdrawing from the second chilldown train to produce a second recycle stream; and introducing the second recycle stream into the first chilldown train withdrawing a wet sweet gas from the first chilldown train, wherein the wet sweet gas has a water concentration higher than in the dry sweet gas introduced to the first chilldown train.