Imidazole-Modified Glycol Dehydration Composition
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Solution Overview
Problem
Existing gas dehydration methods using glycols are inefficient in removing water from natural gas streams, leading to residual moisture and corrosion issues due to pyrolysis products formed during regeneration, which are exacerbated by the thermal instability of commonly used alkanolamines.
Innovation Solution
A dehydration composition comprising triethylene glycol and an imidazole compound, optionally with additional additives like alkali metal carboxylates or alkanolamines, is used in a continuous counter-current process to effectively remove water from gas streams, maintaining thermal stability and preventing corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the temperature during regeneration is raised to drive off more moisture, then the efficiency of gas drying operation is improved, but the dehydrating agent undergoes thermal degradation forming pyrolysis products
Solution Approach 1:
The patent introduces imidazole compounds as additives to modify the thermal stability parameter of the dehydrating agent system. This allows the regeneration temperature to be raised (changing the operating parameter) without suffering from the usual thermal degradation, as the imidazole compound stabilizes the system against pyrolysis.
Solution Approach 2:
The imidazole compound acts as an intermediary substance that mediates between the heat input required for regeneration and the dehydrating agent. It absorbs or mitigates the harmful thermal effects, allowing efficient water removal while protecting the glycol from degradation.
2Object-affected harmful factors
If alkanolamines are added to combat corrosion from pyrolysis products, then corrosion protection is improved, but thermal instability increases at dehydration reboiler temperatures
Solution Approach 1:
The patent replaces the conventional alkanolamine corrosion inhibitors with imidazole compounds that have superior thermal stability at reboiler temperatures. This parameter change in the chemical composition allows maintaining corrosion protection while withstanding the high temperatures of the regeneration process without decomposing.
Solution Approach 2:
Instead of using thermally unstable alkanolamines that decompose at high temperatures, the patent employs imidazole compounds that are specifically selected for their thermal stability, effectively replacing a short-lived inhibitor with a more durable alternative suited for high-temperature service.
3Device complexity
If simple heating is used for regeneration, then the process complexity is reduced, but water removal efficiency is insufficient
Solution Approach 1:
The imidazole compound enhances the inherent water-stripping capability of the glycol system during simple heating, allowing the regeneration process to be more effective without adding complex equipment or multi-step procedures. The additive enables the simple heating process to achieve better water removal efficiency.
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
The composition achieves improved thermal stability and corrosion inhibition, enhancing the efficiency of gas drying operations by effectively removing water while minimizing degradation and corrosion risks.
Implementation Method 1
the wet gas is contacted with a lean drying agent solution, such as a glycol, in an absorbent step to remove the water
Implementation Method 2
The rich glycol (i.e., glycol containing the water) is then passed to a reconcentration or regeneration process typically comprising a reboiler wherein the absorbed water is driven off
Implementation Method 3
Raising the temperature during regeneration tends to drive off more moisture, but the use of excess heat also promotes degradation of the dehydrating agent by formation of pyrolysis products
Implementation Method 4
The presence of the water vapor is undesirable as the water vapor can result in corrosion of pipes and cause corrosion of, and stoppages in, valves and fittings in gas pipe transmission systems
Data Source
AI summary
The present invention relates to a dehydration composition and method of use thereof for drying gas streams, in particular natural gas streams, wherein the dehydration composition comprises (i) a glycol, (ii) an imidazole compound, and optionally (iii) one or more of an alkali metal carboxylate, an additional glycol different than (i), an alkanolamine, a phosphate acid, a salt of a phosphate acid, a borate acid, a salt of a borate acid, a sweetening agent, a low temperature viscosity improver, a corrosion inhibitor, an antifoaming agent, or mixtures thereof.