Wet Gas Lateral Sampling Probe for Accurate BTU Measurement
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Solution Overview
Problem
Current natural gas sampling technologies are inadequate for accurately capturing representative samples of wet gas, which contains entrained liquids, due to phase changes and velocity differences between gas and liquid phases, leading to inaccuracies in BTU content measurement and operational safety issues during transportation.
Innovation Solution
An integral slice sampling process using a streamlined container with a narrow slot and outflow passage that captures a thin slice of the fluid stream at the same velocity as the pipeline flow, preventing liquid disassociation and ensuring a representative sample, even in high HC dew point conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sampling methods are used to capture wet gas samples, then the sampling process is simple, but the sample accuracy deteriorates due to phase changes and velocity differences between gas and liquid phases
Solution Approach 1:
The sampling system is divided into distinct functional segments: a sampling probe with slot opening for lateral sample intake, a separation section with coalescing elements to separate liquid from gas, and a heating section. This segmentation allows each component to address specific problems (phase separation, heating, filtering) independently, improving sample accuracy without requiring complete system redesign.
Solution Approach 2:
A heating element is introduced as an intermediary component between the sampling probe and the analysis system. This heating element prevents condensation and maintains the gas phase throughout the sampling and transport process, ensuring accurate representation of the original wet gas composition without direct mechanical separation of phases.
2Reliability
If isokinetic sampling technique is used to maintain velocity equality, then liquid disassociation is prevented, but the device complexity and operational difficulty increase significantly
Solution Approach 1:
The invention extracts only the essential requirement for representative sampling (lateral sample intake at pipeline velocity) while eliminating the complex isokinetic control mechanisms. The slot opening in the probe wall allows sample acquisition without requiring precise velocity matching or complex flow control systems, simplifying operation while maintaining reliability.
Solution Approach 2:
The system changes the sampling approach from velocity-matched isokinetic sampling to lateral extraction through a slot opening. This parameter change in the sampling mechanism allows the sample to be taken at the same velocity as the pipeline flow naturally, without requiring active velocity control or complex operational procedures.
3Object-affected harmful factors
If liquid is removed from the sample to meet transportation standards, then safety and operational problems are resolved, but the BTU content measurement accuracy deteriorates
Solution Approach 1:
The heating element performs preliminary action by maintaining the gas phase and preventing condensation during sampling and transport. This preliminary heating action ensures that when the sample reaches the analysis system, the liquid components are still present in their original proportions, allowing accurate BTU measurement while meeting transportation safety standards through controlled phase management.
Solution Approach 2:
The heating element acts as an intermediary that reconciles the conflicting requirements of safety and accuracy. By maintaining controlled temperatures, it prevents unwanted condensation during transport (ensuring safety) while preserving the original composition for accurate BTU measurement (ensuring precision).
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 method provides a more accurate and practical sampling solution for wet gas streams, maintaining the composition of the fluid stream and preventing liquid accumulation, thus enhancing the reliability of BTU content measurement and operational safety.
Implementation Method 1
captures a thin slice of the fluid stream at the same velocity as the pipeline flow, preventing liquid disassociation
Implementation Method 2
directing said sampled fluid into a heating zone to vaporize any liquids present in said sampled fluid
Implementation Method 3
High velocity gas in the small internal diameter bore of the probe will prevent any significant layer of liquid from accumulating on the surfaces
Data Source
AI summary
A system for on-stream sampling of pressurized process gas such as natural gas or the like, said system optimized for use with pressurized process gas having liquid entrained therein, or otherwise referenced as “wet”. In the preferred embodiment, the probe tip is situated laterally from one side of the inner pipe wall to the other so as to span the entire inner diameter (ID) of the pipe, the probe tip having formed along its outer surface sample collection slot along the length of said outer surface, providing a “linear sample” of the fluid flow of the entire breadth of the flow, providing an accurate sample of even disassociated flow with entrained liquid particles and flow. Embodiments for continuous sampling, batch mode, spot sampling are provided, as well as an anti-vibration feature.