Natural Gas Dehydration via Pressure Reduction and Heat Exchange
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Solution Overview
Problem
Current natural gas dehydration methods using TEG absorbers and motor-driven pumps result in undesirable emissions such as hydrocarbons and VOCs, and require external energy, which is inefficient and environmentally harmful.
Innovation Solution
A method and system that involves reducing the pressure and temperature of natural gas and water vapor streams using a heat exchanger and eductor pump, followed by separation in a centrifugal separator, with a controller managing heat extraction based on temperature to minimize energy use and emissions, and incorporating a freezing inhibitor to prevent hydrate formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If TEG absorber with reboiler system is used for dehydration, then water vapor content is reduced, but emissions of hydrocarbons and VOCs increase
Solution Approach 1:
The invention extracts water vapor from natural gas through a separator that removes condensed water as liquid, eliminating the need for a reboiler system that would generate harmful emissions. The water separation is achieved by cooling the gas stream to condense water vapor, then physically separating the liquid condensate.
Solution Approach 2:
The invention converts the harmful effect of water vapor in natural gas into a benefit by condensing it through cooling. The condensed water, which would otherwise be a contaminant, is separated and removed, achieving dehydration without the harmful emissions associated with traditional thermal regeneration methods.
2Quantity of substance
If motor driven pumps are used for dehydration process, then water separation is achieved, but external energy consumption increases
Solution Approach 1:
The system uses the natural pressure differential between the wellbore and surface equipment to drive the dehydration process. The natural gas flow itself provides the driving force for water condensation and separation, eliminating the need for motor-driven pumps and external energy input.
Solution Approach 2:
The invention replaces motor-driven mechanical pumping systems with a passive thermal and gravitational separation process. Cooling coils condense the water vapor, and gravity causes the liquid water to separate and drain, substituting active mechanical energy input with passive physical processes.
3Quantity of substance
If pressure and temperature are reduced for dehydration, then water vapor condenses and separates, but gas flow rate decreases
Solution Approach 1:
The cooling process is applied locally to specific zones where water condensation is desired, rather than cooling the entire gas stream uniformly. This allows water vapor to condense in designated heat exchange areas while maintaining higher temperatures and flow rates in other portions of the system.
Solution Approach 2:
The system performs preliminary cooling and condensation of water vapor before the gas enters the main flow distribution system. By removing water content in advance, the subsequent gas flow experiences fewer restrictions and maintains higher effective flow rates through the distribution network.
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 effectively reduces water vapor content in natural gas without relying on external energy, minimizing emissions and operational costs, while ensuring efficient dehydration and storage or distribution of natural gas.
Implementation Method 1
reducing a pressure and a temperature of a first stream of natural gas and water vapor
Implementation Method 2
separating at least part of the water from the first stream of step (a) to form a second stream of natural gas and water vapor
Implementation Method 3
incorporating a freezing inhibitor to prevent hydrate formation
Data Source
AI summary
In a natural gas dehydration system, a heat exchanger has first and second passages in thermal communication but fluidly isolated from each other. A pressure reduction valve receives a first stream of natural gas and water vapor from the first passage and outputs a reduced temperature and pressure first stream to a separator which separates at least part of the water from the first stream to form a second stream of natural gas and water vapor that is output via the second passage to a distribution pipeline or a storage system. A temperature sensor senses a temperature of the first stream and a controller controls a valve coupled in parallel with the second passage to be in an open or closed state for passage or blocking of at least part of the second stream therethrough based on a temperature of the first stream determined by the temperature sensor.