Hydrocarbon Gas Decarbonation Flash System
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Solution Overview
Problem
Current methods for decarbonating hydrocarbon gases using solvents result in significant hydrocarbon content at the regenerator top, leading to increased VOC levels and high energy consumption for post-treatment, particularly when dealing with natural gas at high pressures, which complicates meeting environmental standards and increases operational costs.
Innovation Solution
A low-pressure flash system is employed to separate hydrocarbons co-absorbed by the solvent from acid gases, optimizing pressure and temperature conditions to release a hydrocarbon-rich gaseous fraction, thereby reducing hydrocarbon content at the regenerator top and eliminating the need for costly post-treatment incineration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If thermal regeneration is performed at low pressure (1-5 bar) to reduce energy consumption, then energy efficiency improves, but hydrocarbon content in the acid gas effluent increases significantly
Solution Approach 1:
The patent divides the single thermal regeneration stage into two distinct stages: a first thermal regeneration stage at low pressure (1-5 bar) followed by a second thermal regeneration stage at higher pressure (5-20 bar). This segmentation allows the first stage to operate energy-efficiently while the second stage removes hydrocarbons from the acid gas effluent, thereby resolving the contradiction between energy consumption and hydrocarbon content.
Solution Approach 2:
The patent changes the pressure parameter between two sequential regeneration stages. The first stage operates at low pressure (1-5 bar) to minimize energy consumption, while the second stage operates at elevated pressure (5-20 bar) to reduce hydrocarbon content in the acid gas. This parameter change strategy allows optimization of both energy efficiency and effluent quality.
2Quantity of substance
If expansion stage is added to release dissolved hydrocarbons at intermediate pressure (5-15 bar), then light hydrocarbon release improves, but heavy hydrocarbons remain in the acid gas
Solution Approach 1:
The patent utilizes phase transition (vaporization) in two sequential stages. The expansion stage causes vaporization of light hydrocarbons at intermediate pressure, while the subsequent second thermal regeneration stage at higher pressure vaporizes and removes heavy hydrocarbons. This multi-stage phase transition approach comprehensively removes hydrocarbons of different weights.
Solution Approach 2:
The patent employs a composite process combining expansion vaporization and thermal regeneration in a integrated system. The expansion stage handles light hydrocarbons while the thermal regeneration stage handles heavy hydrocarbons, creating a composite solution that addresses the full spectrum of hydrocarbon removal.
3Object-generated harmful factors
If post-treatment incineration is implemented to meet VOC standards, then environmental compliance improves, but equipment cost and energy consumption increase
Solution Approach 1:
The patent converts the harmful effect of high-pressure operation (which would increase energy consumption) into a benefit by using it to remove hydrocarbons. The second thermal regeneration stage operates at elevated pressure (5-20 bar) specifically to strip heavy hydrocarbons from the acid gas, thereby eliminating the need for separate incineration equipment and meeting VOC standards through the regeneration process itself.
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 compliance with VOC standards without additional post-treatment, reduces energy consumption, and minimizes the size and fuel requirements for incineration, while also simplifying condensate treatment and enabling direct recycling of water in enhanced oil recovery processes.
Implementation Method 1
heating and expanding the CO2-laden absorbent solution at a predetermined pressure and temperature so as to release a hydrocarbon-containing gaseous fraction
Implementation Method 2
heating and expanding the CO2-laden absorbent solution at a predetermined pressure and temperature so as to release a hydrocarbon-containing gaseous fraction
Implementation Method 3
contacting said gas with an absorbent solution so as to obtain a CO2-depleted gas and a CO2-laden absorbent solution
Data Source
AI summary
Method of decarbonating a hydrocarbon gas, a natural gas for example, by washing with a solvent.Said gas is contacted with an absorbent solution so as to obtain a CO2-depleted gas and a CO2-laden absorbent solution. The CO2-laden absorbent solution is then heated and expanded at a predetermined pressure and temperature so as to release a hydrocarbon-containing gaseous fraction and to obtain a hydrocarbon-depleted absorbent solution, said pressure and temperature being so selected that said gaseous fraction comprises at least 50% of the hydrocarbons contained in said CO2-laden absorbent solution and at most 35% of the CO2 contained in said CO2-laden absorbent solution. Finally, the hydrocarbon-depleted absorbent solution is thermally regenerated so as to release a CO2-rich gaseous effluent and to obtain a regenerated absorbent solution.