Odorized Methane Fluids Using Ethyl Acrylate Carriers

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Solution Overview

Problem

Existing odorants for methane-based fluids, such as LNG, face challenges in maintaining solubility at very low temperatures and ensuring detectability of boil-off gases, as they often crystallize out or have high odor threshold values, making it difficult to detect low concentrations.

Innovation Solution

The use of ethyl acrylate or a mixture of ethyl acrylate and ethyl mercaptan as odorants, carried by propane, n-butane, or iso-butane, which are added to methane fluids, ensuring solubility and detectability even at temperatures around -162 °C or -185 °C, and remaining in the fluid phase during phase transitions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional odorants are used in LNG, then they can provide odor detection capability, but they crystallize out at very low temperatures around -162 °C

Engineering Contradiction:
Improveodor detection capabilityVSAvoidsolubility at low temperature
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent introduces a carrier compound (such as ethyl mercaptan or other sulfur-containing compounds) that acts as an intermediary between the odorant and the LNG matrix. This carrier remains soluble at cryogenic temperatures and facilitates the delivery of odorant molecules, preventing direct crystallization of the odorant while maintaining odor detection capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical parameters of the odorant system by selecting specific odorant molecules with appropriate molecular weight, polarity, and intermolecular interaction characteristics that prevent crystallization at LNG operating temperatures. The odorant is chosen to have optimal solubility parameters that match the LNG composition at -162 °C.

Inventive Principle:
Principle #35Parameter changes

2Difficulty of detecting and measuring

If odorants are used to detect boil-off gas, then detectability is improved, but the odor threshold value is too high for low concentration detection

Engineering Contradiction:
Improvedetectability of boil-off gasVSAvoidodor threshold value
Core Design Contradiction:
Difficulty of detecting and measuringVSMeasurement precision

Solution Approach 1:

The patent uses sulfur-containing compounds that replicate the strong odor characteristics of traditional odorants while having significantly lower odor threshold values. These compounds serve as superior copies that enhance detection sensitivity, allowing people to detect much lower concentrations of boil-off gas in air with greater ease and precision.

Inventive Principle:
Principle #26Copying

3Reliability

If odorants are added to methane fluid, then boil-off gas detectability is enabled, but the odorant does not remain in the fluid during phase transition from liquid to gas

Engineering Contradiction:
Improvedetectability of boil-off gasVSAvoidodorant retention during phase transition
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent ensures continuous presence of odorant molecules throughout the phase transition process by selecting odorants with volatility characteristics that match the boil-off gas generation rate. The odorant evaporates continuously alongside the LNG boil-off, maintaining a consistent odor signature from liquid through gas phase without interruption or loss of detection capability.

Inventive Principle:
Principle #20Continuity of useful action

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 odorized methane fluids demonstrate excellent solubility and detectability, with ethyl acrylate and ethyl mercaptan maintaining their effectiveness in both liquid and gas phases, allowing for easy detection of low concentrations of boil-off gases, thus addressing the limitations of previous odorants.

Implementation Method 1

The odorant needs to have a good solubility in a methane comprising liquid or slush at very low temperatures, even at temperatures around -162 °C, or even -185 °C

Methodology Applied
Scientific EffectSolubility: Solvation

Implementation Method 2

the odorant needs to remain in the methane comprising fluid when it transfers from the liquid phase to the gas phase

Methodology Applied
Scientific EffectPhase transition: Phase Change

Data Source

PatentEP3368641B1Odorized methane fluid and processes for producing odorized methane fluids and the use thereof
Publication Date: 2020.09.16 SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ BV

AI summary

The present invention relates to an odorized methane comprising liquid, and to an odorized methane comprising slush of liquid and solids. The invention especially relates to odorized LNG. The odorant is ethyl acrylate and/or ethyl mercaptan. The carrier for the odorant is propane, n-butane, iso-butane, or a mixture of two or more thereof. The present invention also relates to a process for preparing such an odorized liquid or slush by liquefying odorized methane comprising gas. The invention also relates to a process in which odorant is added to a methane comprising liquid or slush.