Liquid CO2 Solvent Separation of Sulfurous Materials
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Solution Overview
Problem
Current methods for removing hydrogen sulfide (H2S) and carbon dioxide (CO2) from natural gas streams are energy-intensive, costly, and result in significant CO2 emissions, with existing processes often requiring additional treatment steps and failing to confine H2S content effectively, leading to high capital and operating costs.
Innovation Solution
A method involving the use of liquid carbon dioxide as a solvent in a contacting column to selectively separate sulfur species from mixed gaseous streams, operating near the triple point of CO2 to avoid solidification and reduce energy requirements, thereby producing a purified gas stream with minimal sulfur content and low CO2 emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional amine scrubbing or membrane treatment is used to remove H2S and CO2, then the sulfur compounds are removed from natural gas streams, but the processes are energy-intensive and result in significant CO2 emissions
Solution Approach 1:
The patent changes the temperature parameter to operate near the triple point of CO2 (approximately -56.6°C at 5.11 atm), transforming the separation mechanism from conventional thermal or pressure-based methods to one utilizing phase equilibrium at low temperatures. This parameter change enables selective condensation of CO2 and H2S while maintaining methane in the gas phase, reducing energy consumption compared to amine scrubbing or membrane treatment
Solution Approach 2:
The patent utilizes phase transitions by operating near the triple point of CO2, where CO2 can transition between solid, liquid, and gas phases. By controlling temperature and pressure near this critical point, the process selectively condenses CO2 and H2S into liquid or solid phases while methane remains gaseous, enabling separation without the high energy input required by conventional methods
2Reliability
If cryogenic processes such as Ryan-Holmes or Controlled-Freeze zone are used, then separation of hydrocarbons is achieved, but additional treatment steps are required for H2S removal and capital costs are high
Solution Approach 1:
The patent merges hydrocarbon separation and H2S/CO2 removal into a single integrated process by operating near the triple point of CO2. The same low-temperature conditions that enable hydrocarbon condensation also selectively condense H2S and CO2, eliminating the need for separate treatment steps required by conventional cryogenic processes like Ryan-Holmes
Solution Approach 2:
The low-temperature separation process performs multiple functions simultaneously: it separates hydrocarbons by condensation, removes H2S and CO2 by selective condensation near the CO2 triple point, and produces a purified natural gas stream, making the process universally applicable to sour gas treatment without requiring additional specialized equipment
3Reliability
If conventional amine processes are used for high H2S and CO2 gas, then removal of sulfur compounds is achieved, but investment and operating costs are high
Solution Approach 1:
The patent employs self-service by using the natural phase equilibrium properties of the gas components at the CO2 triple point. The process relies on the inherent condensation behavior of CO2 and H2S at low temperatures without requiring chemical reagents like amines, reducing both capital investment in chemical handling equipment and operating costs associated with reagent purchase and disposal
4Use of energy by moving object
If the process operates at lower temperatures near the triple point of CO2, then energy requirements are reduced, but solidification of CO2 must be avoided
Solution Approach 1:
The patent applies dynamics by continuously adjusting operating parameters (temperature, pressure, and flow rates) to maintain conditions near but not at the exact triple point of CO2. This dynamic control prevents CO2 solidification while maximizing the energy efficiency of the separation process, allowing the system to adapt to varying feed compositions and load conditions
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 provides a cost-effective and energy-efficient process for separating sulfur compounds, achieving low sulfur content in the gas stream and enabling the reuse of CO2 for enhanced oil recovery or geologic sequestration, while minimizing atmospheric CO2 emissions.
Implementation Method 1
contacting the mixed gaseous stream with a solvent, and particularly wherein the solvent comprises carbon dioxide
Implementation Method 2
operating near the triple point of CO2 to avoid solidification
Data Source
AI summary
The present disclosure relates to systems and methods for separation of sulfurous material(s) from a multi-component feed stream. The systems and methods can comprise contacting the multi-component feed stream with a solvent in a contacting column so that at least a portion of the sulfurous material(s) is transferred from the multi-component feed stream to the solvent. A stream of a substantially purified gas can thus be provided along with a liquid stream comprising at least a majority of the sulfurous material. In particular, the solvent can comprise liquid carbon dioxide, which can be particularly beneficial for removing sulfurous materials from multi-component feed streams.