Gas Expansion Device Liquid Injection Torque Control
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Solution Overview
Problem
Existing gas expansion devices face inefficiencies and reliability issues due to varying inlet pressures, leading to potential structural overload and complex, costly control mechanisms, especially when dealing with high torque and variable speed conditions, which can result in hazardous operating conditions and system downtime.
Innovation Solution
A gas expansion device with a liquid injection system, where liquid is injected upstream or downstream of the inlet port to manage torque by altering the pressure ratio and mass flow, utilizing a three-way valve to control liquid flow and integrate with a generator's control unit for operational management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a precisely dimensioned expansion device is used, then efficiency is optimised at normal inlet pressure, but structural damage can be expected at high peaks in inlet pressure
Solution Approach 1:
The patent applies beforehand cushioning by introducing a liquid (typically water) into the expansion chamber before the high-pressure gas arrives. This liquid cushion absorbs and distributes the impact forces of pressure peaks, preventing structural damage to the expansion device while allowing the device to be precisely dimensioned for optimal efficiency at normal operating pressures.
2Reliability
If quick-closing valves are used to limit torque, then hazardous operating conditions are prevented, but temporary vacuum and high transient loads occur
Solution Approach 1:
The liquid in the expansion chamber serves as a cushion that gradually absorbs torque peaks and prevents hazardous operating conditions without requiring sudden valve closure. This eliminates the temporary vacuum and high transient loads that would otherwise occur with quick-closing valves, while still preventing dangerous situations.
3Reliability
If overdimensioned expansion machine is used, then structural overload is prevented, but efficiency suffers at every inlet pressure
Solution Approach 1:
By using a liquid cushion to absorb pressure peaks and torque variations, the expansion device can be precisely dimensioned for optimal efficiency at normal operating conditions rather than being overdimensioned for safety. The liquid cushion provides the necessary protection against structural overload, allowing the machine to operate efficiently across the full range of inlet pressures.
4Ease of operation
If VSD is used to control volume flow, then precise control and high efficiency are achieved, but complex and expensive speed control is required
Solution Approach 1:
The patent uses hydraulic principles by introducing a liquid into the gas expansion chamber. This liquid-gas interaction provides inherent flow control and torque limitation without requiring complex electronic speed control systems. The liquid acts as a natural regulator that simplifies the overall control system while maintaining precise control over volume flow and torque.
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 liquid injection system effectively limits torque, reduces the risk of structural overload, and enables continuous operation without losing time, even during emergency situations, by using standard valves and reducing the need for quick-closing mechanisms, thus enhancing efficiency and reliability.
Implementation Method 1
liquid is injected upstream or downstream of the inlet port to manage torque by altering the pressure ratio and mass flow
Implementation Method 2
liquid is injected upstream or downstream of the inlet port to manage torque by altering the pressure ratio and mass flow
Data Source
AI summary
Gas expansion device for expanding a gas or a gas-liquid mixture, where the gas expansion device includes a gas expansion element with an inlet port for the gas to be expanded and an inlet pipe for the gas to be expanded. The inlet pipe is connected to the inlet port where the gas expansion device includes a first liquid injection point for the injection of liquid, where the first liquid injection point is at a position level with the inlet port or upstream from the inlet port.