Mercury Removal in Glycol Dehydration via Complexing Agent
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Solution Overview
Problem
Existing gas processing plants face challenges in efficiently removing mercury from natural gas, particularly in glycol dehydration systems, where mercury is not effectively captured and removed, leading to mercury vapor emissions.
Innovation Solution
A process is introduced where a complexing agent is added to the recirculated glycol solvent in the dehydration liquid contactor, selectively reacting with mercury to form non-volatile complexes. The rich glycol with the complexing agent is then fed to a regenerator, and the overhead containing water and mercury vapor is contacted with an adsorbent to capture mercury.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complexing agent is added to the recirculated glycol solvent, then mercury removal efficiency is improved, but the device complexity and operational complexity increase
Solution Approach 1:
A complexing agent is introduced as an intermediary substance that facilitates mercury removal by forming stable complexes with mercury ions in the glycol solvent. The complexing agent acts as a mediator between the glycol solvent and mercury, enabling selective mercury capture while allowing the existing glycol dehydration system to continue functioning. This resolves the contradiction by adding a chemical intermediary rather than requiring complete system redesign.
Solution Approach 2:
The invention changes the chemical composition parameter of the glycol solvent by adding the complexing agent, which alters the solvent's affinity for mercury. This parameter change enables the system to selectively complex and remove mercury while maintaining water removal capabilities. The regenerator parameters are also adjusted to facilitate decomposition of mercury complexes and regeneration of the complexing agent.
2Reliability
If the complexing agent is continuously recirculated with the glycol solvent, then mercury removal is improved, but the energy consumption and operational complexity increase
Solution Approach 1:
The complexing agent is continuously recirculated with the glycol solvent through the dehydration system and regenerator, maintaining continuous mercury removal capability. The regenerator operates continuously to decompose mercury complexes and regenerate the complexing agent, which then returns to the glycol solvent. This continuous circulation ensures sustained mercury removal efficiency while allowing the system to process gas continuously without interruption.
Solution Approach 2:
The regenerator utilizes phase transition and thermal decomposition to separate mercury from the complexing agent. By heating the rich glycol solvent, the mercury complexes decompose and mercury is vaporized, allowing separation from the liquid phase glycol solvent. This phase transition enables energy-efficient regeneration without requiring additional mechanical separation equipment.
3Reliability
If the overhead of the regenerator is contacted with an adsorbent, then mercury vapor capture is improved, but the device complexity and loss of substance increase
Solution Approach 1:
The invention converts the harmful mercury vapor emitted from the regenerator overhead into a recoverable resource. By contacting the overhead stream with an adsorbent, the harmful mercury vapor is captured and concentrated on the adsorbent material. The adsorbed mercury can then be periodically desorbed and recovered, transforming the emission problem into a resource recovery opportunity. This resolves the contradiction by converting harm (mercury emission) into benefit (mercury recovery and reduced environmental impact).
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 process achieves significant mercury removal from natural gas, with mercury concentrations reduced to below 0.1 µg/Nm³ in the dry gas product, effectively addressing the challenge of mercury emission in gas processing plants.
Implementation Method 1
The complexing agent selectively reacts with mercury in the wet natural gas to remove the mercury from the dry natural gas product
Implementation Method 2
The overhead of the regenerator containing water and mercury vapor is contacted with an adsorbent that captures mercury
Data Source
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AI summary
A process for removal of mercury in a gas dehydration system comprising (a) adding a complexing agent to a recirculated glycol solvent as part of the glycol solution feed prior to or at the dehydration liquid contactor and recirculating continuously with the glycol solvent, (b) selectively reacting the complexing agent with mercury in the wet natural gas to remove the mercury from the dry natural gas product, (c) and feeding the rich glycol with the complexing agent to a regenerator and continuously regenerating.