Turboexpander Compressor Inlet Vanes for Off-Design Efficiency Control
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Solution Overview
Problem
Conventional turboexpander-compressor systems can only adjust the pressure of the incoming gas, limiting the ability to optimize efficiency in off-design conditions, as they lack control over the rotating speed of the shaft, which affects both turboexpander and compressor efficiency.
Innovation Solution
Incorporating a controller and two sets of moveable inlet guide vanes, one for the expander and one for the compressor, to monitor and adjust the pressure and temperature of the gas input, allowing for optimization of the ratio between the shaft's rotating speed and enthalpy drop across the expander, thereby maximizing efficiency in off-design conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If only the pressure of incoming gas is adjusted in conventional turboexpander-compressor systems, then the system can operate under varying conditions, but the ability to optimize efficiency in off-design conditions is limited due to lack of control over shaft rotating speed
Solution Approach 1:
The patent applies dynamics by making the inlet guide vanes moveable rather than fixed. The expander inlet guide vanes can adjust the flow angle and pressure of gas entering the expander, while the compressor inlet guide vanes can adjust the flow characteristics of gas entering the compressor. This dynamic adjustment capability allows independent control of expander and compressor operations, enabling optimization of shaft rotating speed and efficiency ratio in off-design conditions without compromising operational flexibility.
2Reliability
If the pressure of incoming gas is controlled to maintain predetermined values, then the shaft speed can be kept close to design value, but in off-design conditions the turboexpander efficiency is not optimized
Solution Approach 1:
The patent applies parameter changes by enabling independent adjustment of multiple system parameters through moveable inlet guide vanes. The expander inlet guide vanes can change the pressure and flow angle parameters of incoming gas to the expander, while the compressor inlet guide vanes can change the flow parameters of gas entering the compressor. This allows the shaft speed to be optimized for maximum efficiency in off-design conditions while maintaining stable operation through controlled parameter adjustments.
Solution Approach 2:
The patent applies feedback by implementing a control system that monitors the ratio of shaft rotating speed to enthalpy drop and adjusts the inlet guide vanes accordingly. The control system receives information about shaft rotating speed, pressures, and temperatures, calculates the efficiency ratio, and automatically positions the expander and compressor inlet guide vanes to optimize performance. This closed-loop feedback mechanism ensures both stable operation and maximum efficiency in off-design conditions.
3Ease of operation
If a single parameter (pressure of incoming gas) is adjusted, then the system operation can be controlled, but the operator ability to optimize turboexpander efficiency is limited
Solution Approach 1:
The patent applies segmentation by dividing the control system into two independent control mechanisms: expander inlet guide vanes for controlling expander-side parameters and compressor inlet guide vanes for controlling compressor-side parameters. This segmentation allows operators to independently adjust each component's inlet conditions, providing multiple control variables to optimize efficiency while maintaining ease of operation through modular, independent control of each subsystem.
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 system effectively adjusts the compressor's input pressure to align the rotating speed and enthalpy drop ratio with predetermined values, enhancing turboexpander efficiency and operational stability in off-design conditions.
Implementation Method 1
a first set of moveable inlet guide vanes (IGV1) attached to the expander and configured to control a pressure of the incoming gas
Implementation Method 2
The expander is configured to expand an incoming gas, and has an expander impeller
Implementation Method 3
The gas expansion produces mechanical work causing a rotation of an expander impeller
Implementation Method 4
The compressor is configured to compress a gas received from the expander, and has a compressor impeller
Implementation Method 5
the rotation of the expander impeller causes the rotation of the compressor impeller. In this manner, the mechanical work produced in the turboexpander is transferred to the compressor
Data Source
AI summary
A turboexpander-compressor system includes an expander configured to expand an incoming gas, a first set of moveable inlet guide vanes configured to control a pressure of the incoming gas, a compressor configured to compress a gas received from the expander, a shaft configured to support and rotate an expander impeller and a compressor impeller, a second set of moveable inlet guide vanes attached to the compressor and configured to control a pressure of the gas input into the compressor, and a controller configured to acquire information about a rotating speed of the shaft, a pressure and a temperature of the incoming gas, a pressure and a temperature of the gas output from the expander, and to control the second set of moveable inlet guide vanes to maximize a ratio between the rotating speed of the shaft and a drop of an enthalpy across the expander, in off-design conditions.