Balancing power in split mixed refrigerant liquefaction system

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Solution Overview

Problem

Existing natural gas liquefaction systems face inefficiencies due to power imbalance between propane and mixed refrigerant compression systems, particularly at varying ambient temperatures, leading to reduced LNG production and wasted power potential.

Innovation Solution

A split mixed refrigerant liquefaction system that adjusts the power requirements of the high-pressure MR compressor to balance power usage between propane and MR compression systems by using a suction throttle valve, adjustable inlet guide vanes, or a variable speed gearbox, allowing for optimal power distribution across different ambient temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a split arrangement with two gas turbine drivers is used to balance compression power, then power utilization is optimized at design temperature, but power imbalance occurs at varying ambient temperatures leading to reduced LNG production

Engineering Contradiction:

ImproveLNG productionVSAvoidpower balance adaptability to ambient temperature

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The system dynamically adjusts the power distribution between the two compression systems by varying the speed of the HP MR compressor using a variable speed gearbox. This allows the compression system to adapt to changing ambient temperatures and power availability, maintaining optimal power utilization across different operating conditions rather than being fixed at design conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the operational parameters of the HP MR compressor by adjusting its speed through a variable speed gearbox. This parameter change allows the compressor to operate at different power levels depending on ambient temperature and available driver power, thereby balancing power usage between the propane and MR compression systems under varying conditions.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If identical turbine drivers are used on both compression systems, then mechanical load balance is achieved at design conditions, but power potential is wasted due to imbalance at varying temperatures

Engineering Contradiction:

Improvewasted power potentialVSAvoidcompression system configuration

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The system transitions from a static power distribution arrangement to a dynamic one by incorporating a variable speed gearbox on the HP MR compressor. This allows the system to continuously adjust power distribution to match available driver power and ambient conditions, eliminating wasted power potential while maintaining manageable complexity through a single adjustable component.

Inventive Principle:

Principle #15Dynamics

3Productivity

If the HP MR compressor operates at fixed power requirements, then system design is simplified, but power utilization efficiency decreases at temperatures different from design conditions

Engineering Contradiction:

Improvepower utilization efficiencyVSAvoidcompressor control mechanism

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The invention implements parameter changes by allowing the HP MR compressor speed to vary through a variable speed gearbox. This enables the compressor to operate at optimized power levels matching ambient temperature and driver power availability, significantly improving power utilization efficiency. The added complexity is limited to the gearbox mechanism, which is a standard industrial component.

Inventive Principle:

Principle #35Parameter changes

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 enhances LNG production efficiency by maximizing the use of available power across a wide range of temperatures, ensuring consistent performance regardless of ambient conditions.

Implementation Method 1

using a suction throttle valve

Methodology Applied

Scientific EffectThrottling: Pressure Drop

Implementation Method 2

adjustable inlet guide vanes

Methodology Applied

Scientific EffectInlet guide vane flow control:

Implementation Method 3

variable speed gearbox

Methodology Applied

Scientific EffectVariable speed transmission: Gear

Implementation Method 4

Natural gas is cooled, liquefied, and/or sub-cooled by indirect heat exchange against the refrigerants in the heat exchangers

Methodology Applied

Scientific EffectIndirect heat exchange: Heat Exchanger

Implementation Method 5

a first driver (such as a gas turbine) and a second driver (such as a gas turbine)

Methodology Applied

Scientific EffectGas turbine power conversion: Heat Engine

Data Source

PatentUS10935312B2Balancing power in split mixed refrigerant liquefaction system

Publication Date: 2021.03.02 HONEYWELL LNG LLC

AI summary

A split mixed refrigerant (“MR”) natural gas liquefication system, where low-pressure (“LP”) and medium pressure (“MP”) MR compressors are driven by a first gas turbine and a propane compressor and a high-pressure (“HP”) MR compressor is driven by a second gas turbine, is disclosed. The split MR liquefication system is configured to adjust the characteristics of the HP MR compressor to require less power when less power is available and more power when more power is available compared to the system's design point. Such adjustments allow for shifting the balance of power between the propane compressor and the HP MR compressor to improve LNG production efficiency.