Natural Gas Heavy Hydrocarbon Removal Using Scrubbing and TSA
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Solution Overview
Problem
Conventional methods for removing heavy hydrocarbons from natural gas streams, such as temperature swing adsorption (TSA) and scrub columns, face inefficiencies and operational challenges, especially when the gas stream is lean in C3-C5 hydrocarbons or contains high concentrations of heavy hydrocarbons, leading to energy inefficiencies and risks of adsorbent deactivation.
Innovation Solution
A dual-system approach combining a gas-liquid separation system, preferably a stripping column or phase separator, with a temperature swing adsorption system, where the gas-liquid separation system initially removes bulk heavy hydrocarbons, reducing the load on the TSA system and allowing for more efficient processing and preventing adsorbent deactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a scrub column is used to remove heavy hydrocarbons from natural gas, then heavy hydrocarbon removal is achieved, but the operating pressure must be lower than the mixture's critical pressure, leading to lower liquefaction process energy efficiency
Solution Approach 1:
The heavy hydrocarbon removal process is divided into two distinct stages: (1) a scrubbing stage that removes the bulk of heavy hydrocarbons at high pressure, and (2) a TSA stage that removes remaining traces at lower pressure. This segmentation allows each stage to operate under optimal pressure conditions, with the scrubbing stage maintaining high pressure for energy efficiency and the TSA stage operating at lower pressure for effective removal.
Solution Approach 2:
The scrubbing process is performed as a preliminary action before the TSA process. By removing the majority of heavy hydrocarbons first through scrubbing at high pressure, the subsequent TSA process only needs to handle trace amounts, allowing it to operate at lower pressures without compromising overall removal effectiveness.
2Reliability
If TSA is used to remove heavy hydrocarbons from natural gas streams that are lean in C3-C5 hydrocarbons, then heavy hydrocarbon removal is achieved, but the adsorbent beds become very large and regeneration gas requirements become economically infeasible
Solution Approach 1:
The removal process is segmented into two stages: bulk removal by scrubbing and trace removal by TSA. This segmentation significantly reduces the load on the TSA system, allowing for smaller adsorbent beds and lower regeneration gas requirements while maintaining effective heavy hydrocarbon removal.
Solution Approach 2:
The scrubbing process acts as a preliminary action that removes the bulk of heavy hydrocarbons before the gas enters the TSA beds. This preliminary removal dramatically reduces the concentration of heavy hydrocarbons that the TSA system must handle, making the adsorbent bed size and regeneration gas requirements economically feasible.
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 combination enhances energy efficiency in natural gas liquefaction by allowing higher-pressure operation of the gas-liquid separation system, reduces the risk of adsorbent deactivation, and maintains operational flexibility across varying heavy hydrocarbon concentrations, thereby improving overall process efficiency and preventing freezing issues in liquefied natural gas.
Implementation Method 1
a gas-liquid separation system for separating a heavy hydrocarbon containing natural gas into a heavy hydrocarbon depleted natural gas vapor and a heavy hydrocarbon enriched liquid
Implementation Method 2
an adsorption system that comprises one or more beds of adsorbent for adsorbing and thereby removing heavy hydrocarbons from a heavy hydrocarbon containing natural gas
Data Source
AI summary
A method and apparatus of removing heavy hydrocarbons from a natural gas feed stream, the method comprising using first and second hydrocarbon removal systems in series such that the first system processes the natural gas feed stream to produce a heavy hydrocarbon depleted natural gas stream and the second system processes at least a portion of the heavy hydrocarbon depleted natural gas stream from the first system to produce a natural gas stream lean in heavy hydrocarbons, wherein one of said systems is a adsorption system that comprises one or more beds of adsorbent for adsorbing and thereby removing heavy hydrocarbons from a heavy hydrocarbon containing natural gas, and the other of said systems is a gas-liquid separation system for separating a heavy hydrocarbon containing natural gas into a heavy hydrocarbon depleted natural gas vapor and a heavy hydrocarbon enriched liquid.