Method for starting and operating a plant for the liquefaction of a gaseous product
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for starting and operating liquefaction plants require a variable frequency drive for each high-power electric motor, leading to increased costs and larger plant footprints due to the complexity and need for multiple devices.
Innovation Solution
A method involving a plant with at least two machine strings, where a single variable frequency drive is used to sequentially start and regulate the speed of the motors, with the power supply grid taking over once the predefined thresholds are reached, allowing for efficient operation and reduced infrastructure requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a variable frequency drive is provided for each high-power electric motor in the plant, then the motors can be started and controlled independently, but the plant footprint and costs increase due to the complexity and quantity of devices required
Solution Approach 1:
The patent merges the control function of multiple variable frequency drives into a single device. The single variable frequency drive sequentially controls multiple high-power electric motors (first motor, second motor, third motor) that are connected in parallel to the power supply grid, eliminating the need for multiple separate drives and reducing plant footprint while maintaining independent motor control capability
Solution Approach 2:
The single variable frequency drive performs multiple functions by sequentially controlling different motors during the startup sequence. It first controls the first motor, then the second motor, and finally the third motor, making one device universal for controlling multiple motors that would traditionally require individual drives
2Ease of operation
If a variable frequency drive is provided for each high-power electric motor, then precise speed control is achieved, but the plant costs increase due to the complexity and quantity of devices
Solution Approach 1:
The patent combines multiple speed control functions into a single variable frequency drive device. This single device provides precise speed control for the first motor, second motor, and third motor sequentially, reducing the number of control devices from three to one while maintaining the same level of control precision
Solution Approach 2:
The variable frequency drive operates in a periodic sequence, controlling the first motor first, then the second motor, and finally the third motor. This sequential periodic control allows one device to perform the work of multiple devices while maintaining precise speed control at each stage of the startup process
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 reduces the need for multiple variable frequency drives, lowering costs and plant size while maintaining efficient operation by leveraging the constant frequency power supply grid to manage motor speeds effectively.
Implementation Method 1
The plant also comprises a variable frequency drive, which can be connected to a power supply grid having an its own frequency and which can be associated to the electrical motors
Data Source
Figure 1~2a
Figure 2b~3
AI summary
A method for starting and operating a plant (1) for the liquefaction of a gaseous product comprising the steps of electrically connecting a variable frequency drive (6) to a motor (5) of a first machine string (2a); increasing the speed of the motor (5) of the first machine string (2a) up until a first predefined threshold; electrically disconnecting the variable frequency drive (6) from the motor (5) of the first machine string (2a); electrically connecting the variable frequency drive (6) to a motor (5) of a second machine string (2b); the first predefined threshold is function of said frequency of the power supply grid (7). The variable frequency drive (6) can be switched during operation of the plant among the strings according to process requirements.