Cryogenic Turbine Expander With Integrated J-T Bypass Flow Control
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Solution Overview
Problem
Existing LNG plants face inefficiencies due to the use of Joule-Thomson valves, resulting in approximately 7% loss in production through expander bypass flow, and struggle to optimize performance across varying operational conditions.
Innovation Solution
Integration of cryogenic turbine expanders with a three-way cross-flow J-T valve system, allowing for variable speed operation and optimized performance specification by shifting the best efficiency point, reducing pipe cooling leakage flow, and enabling processing of flammable gases within a stainless steel pressure vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cryogenic turbine expander is installed to replace the Joule-Thomson valve, then thermodynamic efficiency is substantially improved and LNG output increases by 5-7%, but device complexity increases due to the integration of turbine and J-T valve systems
Solution Approach 1:
The patent combines the cryogenic turbine expander and Joule-Thomson valve into a single integrated unit. The turbine expander handles the primary expansion function while the integrated J-T valve provides supplemental throttling capability, eliminating the need for separate bypass piping and valves. This merging of functions reduces overall system complexity while maintaining the productivity benefits of turbine expansion.
Solution Approach 2:
The integrated system design allows the expander unit to perform multiple functions: primary gas expansion through the turbine, supplemental pressure control through the J-T valve, and safety bypass capabilities. This multi-functionality consolidates what would otherwise require separate equipment into a single universal unit, improving productivity without proportionally increasing complexity.
2Reliability
If a bypass pipe and J-T valve are installed for safety reasons, then reliability is improved, but production loss increases by approximately 7% due to bypass flow
Solution Approach 1:
The safety bypass function is integrated directly into the expander unit rather than requiring separate external piping. The integrated J-T valve is positioned within the main flow path, allowing it to handle safety bypass flows without creating the 7% production loss associated with external bypass systems. This merging eliminates the productivity penalty while maintaining safety reliability.
Solution Approach 2:
The integrated J-T valve acts as an intermediary component that can redirect flow internally within the compact expander housing. This internal mediation allows safety bypass flows to be handled without creating the external piping loops that cause production losses in conventional systems, thereby maintaining both reliability and productivity.
3Adaptability or versatility
If the expander operates at fixed speed, then device complexity is reduced, but adaptability deteriorates when facing varying operational conditions
Solution Approach 1:
The patent implements variable speed control for the turbine expander, allowing it to adapt to varying operational conditions and maintain optimal performance across different load scenarios. The speed control mechanism adjusts the turbine rotation speed to match demand, maximizing efficiency under varying conditions while the integrated J-T valve provides additional flexibility for pressure regulation.
Solution Approach 2:
The system changes operational parameters by varying the turbine speed and adjusting the J-T valve opening to optimize performance under different conditions. This parameter adjustment capability allows the expander to adapt to varying gas flows and pressure requirements without requiring a completely different device configuration, achieving versatility through controlled parameter variation.
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 enhances thermodynamic efficiency, reduces production losses, and allows for optimal performance across different operational conditions, achieving maximum economic benefits with payback times of less than one year.
Implementation Method 1
Turbine expanders convert the hydraulic energy of the LNG fluid stream into electric energy, thus reducing the internal energy or enthalpy from the LNG
Implementation Method 2
the high pressure of the condensed liquid natural gas is reduced by expansion across a Joule-Thomson valve
Data Source
AI summary
A cryogenic turbine expander system which consists essentially of a cryogenic liquid pressure vessel, and the vessel further accommodating a turbine expander, an internal bypass configuration, which are operable in parallel, a three-way valve to direct incoming high pressure liquefied gas flow to the turbine expander, or the internal bypass configuration, which further consists a Joule-Thomson valve, when the turbine expander is not operational.