Turboexpander Inlet Guide Vanes for Speed Control
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Solution Overview
Problem
Turboexpander-compressor systems face efficiency challenges during off-design conditions due to interdependent variations in gas expansion parameters and rotating speed, requiring precise control of inlet guide vanes to maximize efficiency.
Innovation Solution
A turboexpander-driven turbomachine system with separate sets of moveable inlet guide vanes at the turboexpander and driven turbomachine, controlled by a mechanical transmission and controller to adjust rotary speed and optimize power production, utilizing a fixed transmission ratio and independent control of each set of vanes for optimal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single set of inlet guide vanes is used to control both turboexpander and compressor speeds, then the system structure is simpler, but the ability to independently optimize each component's efficiency is reduced
Solution Approach 1:
The patent divides the single control system into two separate sets of inlet guide vanes: one set for the turboexpander and another set for the compressor. This segmentation allows each component to be controlled independently, enabling separate optimization of their operating points and efficiency characteristics without being constrained by a unified control mechanism.
Solution Approach 2:
The patent implements dynamic control capabilities by making both sets of inlet guide vanes adjustable during operation. This allows the system to adapt to varying operating conditions by dynamically modifying the flow characteristics at each component, thereby maintaining optimal efficiency across different load conditions while preserving structural simplicity through standardized actuation mechanisms.
2Reliability
If the rotary speed is fixed to maintain design efficiency, then the turboexpander operates at optimal efficiency point, but the system cannot adapt to off-design conditions and process variations
Solution Approach 1:
The patent employs dynamic adjustment of inlet guide vanes at both the turboexpander and compressor. This allows the system to maintain optimal efficiency by adjusting the flow angles and velocities in response to varying operating conditions, thereby adapting to off-design scenarios while preserving the benefits of designed operating points through active control.
Solution Approach 2:
The patent utilizes parameter changes by modifying the inlet guide vane positions to alter flow parameters such as mass flow rate, inlet angle, and velocity distribution. These parameter adjustments enable the system to shift operating points dynamically, maintaining high efficiency across a broader range of conditions including off-design scenarios where fixed-speed operation would be suboptimal.
3Power
If inlet guide vanes are controlled to maximize power output, then the turboexpander produces more mechanical work, but the rotary speed may deviate from optimal values reducing overall efficiency
Solution Approach 1:
The patent segments the control functions by providing separate inlet guide vane sets for the turboexpander and compressor, each with independent actuation. This allows the turboexpander's inlet guide vanes to be optimized for maximum power extraction while the compressor's vanes are adjusted to maintain optimal rotating speed, thereby decoupling the conflicting objectives of power maximization and efficiency preservation.
Solution Approach 2:
The patent implements feedback control mechanisms that monitor operating parameters such as rotating speed, pressure ratio, and power output. Based on this feedback, the control system adjusts the inlet guide vane positions in real-time to balance power output and efficiency requirements, ensuring that deviations from optimal operating points are corrected while maximizing mechanical work production.
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 configuration allows for independent control of turboexpander and driven turbomachine speeds, maximizing efficiency and power output while maintaining desired rotary speed values, thereby enhancing the overall performance and reducing energy losses.
Implementation Method 1
Inside the turboexpander 210 the gas may expand and thus cause rotation of the turboexpander impeller 212
Implementation Method 2
The compressor impeller 226 therefore rotates due to the mechanical work generated during the expansion of the gas in the turboexpander 210. The rotation of the compressor impeller 226 provides energy used to compress the gas in the compressor 224.
Data Source
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AI summary
The turboexpander and driven turbomachine system comprises: a turboexpander (13) configured for expanding a first fluid and comprising an expander stage with one ex- pander impeller; a first set of moveable inlet guide vanes (23) at the inlet of the ex- pander stage; a driven turbomachine (21) configured for processing a second fluid and comprising a turbomachine impeller; a second set of moveable inlet guide vanes (27) at the inlet of the turbomachine impeller; a mechanical transmission (19) between the turboexpander and the driven turbomachine; and a controller (25, 29) connected to the second set of moveable inlet guide vanes (27) and configured for controlling the second set of moveable inlet guide vanes (27) for adjusting the rotary speed of the driven turbomachine and said turboexpander.