Three-Pinion Integral Gear Machine for Dual-Cycle LNG Liquefaction
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Solution Overview
Problem
Conventional small- to mid-scale liquefied natural gas production systems face inefficiencies in heat exchange and power consumption, leading to increased operating costs, which are not adequately addressed by existing design philosophies and liquefaction cycles.
Innovation Solution
The implementation of a liquefaction cycle using two distinct refrigeration circuits with compositionally different working fluids operating at different temperature levels, combined with a mixed service integral gear machine having at least three pinions, optimized to reduce heat exchange inefficiencies and power consumption by pairing turbomachinery for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional single refrigeration cycle systems are used, then device complexity is reduced, but heat exchange inefficiencies and power consumption increase
Solution Approach 1:
The refrigeration system is divided into two distinct cycles: a first refrigeration cycle using nitrogen as working fluid and a second refrigeration cycle using methane as working fluid. Each cycle operates independently at different temperature levels, allowing optimized heat exchange for specific temperature ranges and reducing overall thermal inefficiency.
Solution Approach 2:
Different working fluids are selected for different temperature zones: nitrogen for higher temperature refrigeration and methane for lower temperature refrigeration. This local optimization of fluid properties to match local temperature requirements minimizes heat exchange losses in each specific zone.
2Use of energy by moving object
If conventional separate compression systems are used, then device complexity is reduced, but power consumption increases
Solution Approach 1:
The integral gear machine combines multiple compression functions into a single integrated device. It simultaneously compresses nitrogen in the first cycle and methane in the second cycle using a shared gear mechanism, reducing the number of separate compressors and drive systems while minimizing power consumption through efficient mechanical coupling.
Solution Approach 2:
The integral gear machine serves multiple functions: it acts as a compressor for nitrogen, a compressor for methane, and a synchronized drive mechanism for both cycles. This multi-functionality reduces overall system power consumption by eliminating redundant drive systems and optimizing mechanical efficiency.
3Ease of operation
If nitrogen-based gas expansion refrigeration cycle is used, then safety and ease of operation are improved, but heat exchange inefficiencies persist
Solution Approach 1:
The refrigeration system is divided into two distinct cycles: a first refrigeration cycle using nitrogen as working fluid and a second refrigeration cycle using methane as working fluid. Each cycle operates independently at different temperature levels, allowing optimized heat exchange for specific temperature ranges and reducing overall thermal inefficiency.
Solution Approach 2:
Different working fluids are selected for different temperature zones: nitrogen for higher temperature refrigeration and methane for lower temperature refrigeration. This local optimization of fluid properties to match local temperature requirements minimizes heat exchange losses in each specific zone.
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 minimizes heat exchange inefficiencies and power consumption, enhancing the production capacity and reducing unit power costs in small- to mid-scale liquefied natural gas production systems.
Implementation Method 1
receiving work produced by at least one of the one or more high efficiency radial inflow turbines of the refrigeration circuits
Implementation Method 2
Many of these liquefaction systems employ mechanical refrigeration or a nitrogen-based gas expansion refrigeration cycle to cool to the natural gas feed to subzero temperatures required for natural gas liquefaction
Implementation Method 3
nitrogen-based gas expansion refrigeration cycle to cool to the natural gas feed to subzero temperatures
Implementation Method 4
conditioning of the natural gas containing feed to produce purified, compressed natural gas stream at a pressure equal to or above the critical pressure of natural gas
Data Source
AI summary
A system and method for liquefaction of natural gas using two distinct refrigeration circuits having compositionally different working fluids and operating at different temperature levels is provided. The turbomachinery associated with the liquefaction system are driven by a single three-pinion or four-pinion integral gear machine with customized pairing arrangements. The system and method of natural gas liquefaction further includes the conditioning of a lower pressure natural gas containing feed stream to produce a purified, compressed natural gas stream at a pressure equal to or above the critical pressure of natural gas and substantially free of heavy hydrocarbons to be liquefied.