Multi-Pressure Refrigerant Circuit Using Split Compressors

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Solution Overview

Problem

Existing refrigerant circuits for liquefaction plants face challenges with increasing production rates, requiring larger compressors and higher inlet velocities, which complicates manufacturing and handling, especially when handling multiple refrigerant streams at different pressure levels.

Innovation Solution

A refrigerant circuit design featuring two compressors with multiple inlets and outlets configured to handle five or more refrigerant streams at various pressure levels, allowing for efficient evaporation and compression, with optional relief valves for overpressure protection and economizers for optimized energy distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the mass flow rate of the refrigerant is increased to handle increasing amounts of gas stream to be cooled, then the cooling capacity is improved, but the compressor size and inlet velocity increase

Engineering Contradiction:
Improvecooling capacityVSAvoidcompressor size
Core Design Contradiction:
ProductivityVSVolume of moving object

Solution Approach 1:

The refrigerant circuit is divided into multiple independent loops, each with its own compressor. This segmentation allows each compressor to handle a portion of the total refrigerant flow, preventing the need for a single oversized compressor while maintaining the required cooling capacity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a single-compressor architecture to a multi-compressor multi-loop architecture, adding dimensional complexity to the system design. This allows the refrigerant flow to be distributed across multiple parallel paths, effectively managing high mass flow rates without proportionally increasing individual compressor sizes.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If the mass flow rate of the refrigerant is increased to handle increasing amounts of gas stream to be cooled, then the cooling capacity is improved, but the inlet velocity into the impellers increases

Engineering Contradiction:
Improvecooling capacityVSAvoidinlet velocity
Core Design Contradiction:
ProductivityVSSpeed

Solution Approach 1:

By dividing the refrigerant flow into multiple separate loops with individual compressors, the inlet velocity at each compressor impeller is maintained at manageable levels even when the total system cooling capacity is increased, as each compressor handles only a fraction of the total refrigerant flow.

Inventive Principle:
Principle #1Segmentation

3Productivity

If the diameter of the housing is increased to accommodate higher flow rates, then the cooling capacity is improved, but the manufacturing complexity and handling difficulty increase

Engineering Contradiction:
Improvecooling capacityVSAvoidmanufacturing complexity
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The system uses multiple smaller compressors with standard-sized housings rather than one large compressor with a custom oversized housing. This segmentation allows each compressor to be manufactured using conventional processes and handled with standard equipment, while the aggregate system capacity meets the required cooling demand.

Inventive Principle:
Principle #1Segmentation

4Productivity

If a single large compressor is used to handle high refrigerant flow rates, then the cooling capacity is improved, but the system complexity for pressure relief and protection increases

Engineering Contradiction:
Improvecooling capacityVSAvoidpressure relief system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

Each compressor in the multi-loop system has its own pressure relief valve and protection mechanisms, isolating pressure management to individual units. This eliminates the need for a complex centralized pressure relief system that would be required for a single large compressor handling the same total flow, as each smaller compressor operates within its own pressure envelope.

Inventive Principle:
Principle #1Segmentation

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 design simplifies the refrigerant circuit, reduces the size of the pressure relief system, and enhances evaporation efficiency by enabling the handling of multiple pressure levels, distributing compressor power evenly and reducing manufacturing complexity.

Implementation Method 1

a refrigerator (or 'refrigeration zone') in which the refrigerant is evaporated in one or more stages thereby withdrawing heat from the gas stream to be cooled

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

withdrawing heat from the gas stream to be cooled

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 3

a compressor for recompressing the evaporated refrigerant

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP1960726A1Refrigerant circuit
Publication Date: 2008.08.27 SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ BV

AI summary

The present invention relates to a refrigerant circuit (1), in particular for use in a liquefaction plant, the refrigerant circuit (1) at least comprising: - a refrigerator (2) having an inlet (21) for refrigerant (10) at a refrigeration pressure, and at least five outlets (22, 23, 24, 25, 26, ...) for evaporated refrigerant (20, 30, 40, 50, 60, ...) evaporated at different pressure levels, the at least five outlets (22, 23, 24, 25, 26, ...) being preferably intended for refrigerants evaporated at increasing pressures from the first outlet (22) to the fifth (26) and optional higher outlets; - a first compressor (3) having one or more inlets for receiving evaporated refrigerant from the refrigerator and an outlet (34) that can be connected to the inlet (21) of the refrigerator (2); and - a second compressor (4) having one or more inlets for receiving evaporated refrigerant from the refrigerator and an outlet (44) that can be connected to the inlet (21) of the refrigerator (2).