Single-Casing Centrifugal Compression for High-Ratio LNG Refrigerant Gas

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Solution Overview

Problem

Current LNG plants face challenges in compressing light gases with high compression ratios using a single compressor, leading to inefficient and non-compact designs due to the low molecular weight of gases like mixed refrigerant, ethylene, or methane, which typically require multiple compressors.

Innovation Solution

A centrifugal compression train with a single compressor, configured to achieve a high compression ratio of over 10:1, utilizing a single casing with multiple sections of compression and intercooling, and featuring a gearbox to increase rotational speed, allowing for efficient compression of light gases with molecular weights less than 30 g/mol.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple compressors are used to compress light gases with high compression ratios, then the compression efficiency is improved, but the number of machines and footprint increase

Engineering Contradiction:
Improvecompression efficiencyVSAvoidfootprint
Core Design Contradiction:
ProductivityVSArea of stationary object

Solution Approach 1:

The patent combines multiple compression sections into a single centrifugal compressor unit, integrating what would traditionally require separate compressors into one unified machine. This merging achieves high compression ratios for light gases while reducing the number of individual machines and overall footprint.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single centrifugal compressor is divided into multiple compression sections, each handling a stage of compression. This segmentation allows the system to achieve high overall compression ratios through multiple staged compression within one machine, maintaining efficiency while consolidating equipment.

Inventive Principle:
Principle #1Segmentation

2Productivity

If multiple compressors are used to compress light gases with high compression ratios, then the compression capability is improved, but the device complexity increases

Engineering Contradiction:
Improvecompression capabilityVSAvoidnumber of machines
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent merges multiple compression functions into a single centrifugal compressor with multiple sections, reducing the number of separate machines from three or more to just one. This consolidation maintains the required compression capability while significantly simplifying the overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single centrifugal compressor is designed to perform multiple compression stages within one machine, making it a multi-functional device that replaces what would traditionally require several specialized compressors. This universality reduces complexity while maintaining comprehensive compression capability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Area of stationary object

If a single centrifugal compressor is used to achieve high compression ratio, then the footprint is reduced, but the compression efficiency decreases

Engineering Contradiction:
ImprovefootprintVSAvoidcompression efficiency
Core Design Contradiction:
Area of stationary objectVSProductivity

Solution Approach 1:

The single centrifugal compressor is segmented into multiple compression sections that work in sequence, with each section contributing to the overall compression ratio. This segmentation enables the machine to achieve high compression efficiency through staged compression while maintaining a compact single-unit footprint.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a horizontal arrangement of multiple separate compressors to a vertical or multi-sectional arrangement within a single centrifugal compressor. This dimensional reorganization allows high compression ratios to be achieved within a compact footprint by utilizing the vertical or radial space within the single machine.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 solution enables the compression of light gases with high compression ratios in a single casing, reducing the number of machines and footprint, improving LNG production efficiency, and simplifying maintenance and installation while minimizing gas leakages and complexity.

Implementation Method 1

a centrifugal compressor machine driven in rotation by said driver machine; the compressor being configured to compress a refrigerant gas with a molecular weight less than 30 g/mol from a suction pressure to a discharge pressure; wherein the ratio between discharge and suction pressures is higher than 10

Methodology Applied
Scientific EffectCentrifugal compression: Centrifugal Force

Implementation Method 2

the compressor machine comprises a first section of compression, a second section of compression and a third section of compression arranged in series

Methodology Applied
Scientific EffectIntercooling: Cooling

Data Source

PatentEP3351882B1Compression train including one centrifugal compressor and LNG plant
Publication Date: 2024.05.01 NUOVO PIGNONE TECH SRL
  • EP3351882B1 patent drawingFigure 1~2
  • EP3351882B1 patent drawingFigure 3~4
  • EP3351882B1 patent drawingFigure 5

AI summary

Compression train for a natural gas liquefaction process. The compression train comprises a driver machine and only one centrifugal compressor machine driven in rotation by said driver machine; the compressor is configured to compress a refrigerant gas with a molecular weight less than 30 g/mol from a suction pressure to a discharge pressure; the ratio between discharge and suction pressures is higher than 10, preferably higher than 12, more preferably higher than 15. LNG plant comprising one or more compression train according to the present invention.