Compressor System Variable Speed Gears

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Solution Overview

Problem

Compressor systems driven by a single machine face challenges in maintaining stable operation and wide operating ranges when operating at constant outlet pressure, particularly when high and low pressure compressors are serially connected via step-up or reduction gears.

Innovation Solution

A compressor system configuration featuring a driving machine with two output shafts, a variable speed step-up gear for the low pressure side compressor and a constant speed step-up gear for the high pressure side compressor, allowing for adjustable rotational speeds and maintaining constant outlet pressure across varying operating conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single driving machine drives both high pressure and low pressure compressors via step-up or reduction gears, then the system structure is simplified, but the operating range is limited and stable operation at constant outlet pressure is difficult to maintain

Engineering Contradiction:
Improvesystem structureVSAvoidoperating range
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The driving machine is divided into two independent output shafts, each capable of independent rotation. The first output shaft drives the low pressure compressor and the second output shaft drives the high pressure compressor. This segmentation allows each compressor to operate independently within its optimal range, expanding the overall system operating range while maintaining a relatively simple single-machine structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces variable speed step-up gears and constant speed step-up gears to create dynamic speed adjustment capabilities. The variable speed step-up gear allows the rotational speed of the first output shaft to be adjusted according to operating conditions, while the constant speed step-up gear maintains stable speed for the second output shaft. This dynamic adjustment enables stable operation at constant outlet pressure across a wider operating range.

Inventive Principle:
Principle #15Dynamics

2Device complexity

If both compressors are driven at the same rotational speed, then the driving machine structure is simplified, but the outlet pressure stability deteriorates when operating conditions vary

Engineering Contradiction:
Improvedriving machine structureVSAvoidoutlet pressure stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The driving machine employs two separate output shafts instead of a single shared shaft, allowing independent speed control for each compressor. This segmentation enables the low pressure compressor and high pressure compressor to operate at different rotational speeds optimized for their respective pressure stages, maintaining outlet pressure stability under varying operating conditions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the rotational speed parameter differently for each compressor based on operating conditions. The variable speed step-up gear adjusts the speed ratio dynamically, allowing the first output shaft speed to vary while the second output shaft maintains constant speed through the constant speed step-up gear. This parameter differentiation ensures stable outlet pressure across the operating range.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If the low pressure compressor operates at high rotational speed, then the compression efficiency is improved, but the outlet pressure becomes unstable when flow rate varies

Engineering Contradiction:
Improvecompression efficiencyVSAvoidoutlet pressure stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The variable speed step-up gear provides dynamic speed adjustment capability for the first output shaft driving the low pressure compressor. When flow rate varies, the rotational speed can be adjusted to maintain optimal compression efficiency while preventing outlet pressure instability. This dynamic control allows the system to adapt to changing operating conditions without sacrificing efficiency or stability.

Inventive Principle:
Principle #15Dynamics

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 enables a wider operating range and stable operation by minimizing outlet pressure decrease and ensuring stable output, with the high pressure side compressor operating at a constant speed and the low pressure side compressor's rotational speed being variable, while the high pressure side compressor compresses further, maintaining constant outlet pressure.

Implementation Method 1

a variable speed step-up gear (14) which increases the rotational speed of the first output shaft (11a) and transmits the increased rotational speed to the low pressure side compressor (12) and varies the increased rotational speed

Methodology Applied
Scientific EffectGear mechanism: Gear

Implementation Method 2

a constant speed step-up gear (15) which increases the rotational speed of the second output shaft (11b) to transmit the rotational speed to the high pressure side compressor (13) and causes the increased rotational speed to be constant

Methodology Applied
Scientific EffectGear mechanism: Gear

Implementation Method 3

a low pressure side compressor (12) configured to receive rotation of the first output shaft (11a) and compress a working fluid

Methodology Applied
Scientific EffectImpeller compression: Impeller

Implementation Method 4

a high pressure side compressor (13) configured to receive rotation of the second output shaft (11b) and further compress the working fluid compressed by the low pressure side compressor (12)

Methodology Applied
Scientific EffectImpeller compression: Impeller

Data Source

PatentEP3159547B1Compressor system
Publication Date: 2019.06.19 MITSUBISHI HEAVY INDUSTIES COMPRESSOR CORP
  • EP3159547B1 patent drawingFigure 1
  • EP3159547B1 patent drawingFigure 2
  • EP3159547B1 patent drawingFigure 3

AI summary

This compressor system (10) is provided with: a driving machine (11) having a rotary-driven first output shaft (11a) and a second shaft (11b) that is rotary driven so as to reach the same speed as the first output shaft (11a); a working-ftuid-compressing first compressor (12) to which the rotation of the first output shaft (11a) is transmitted; a working-fluid-compressing second compressor (13) to which the rotation of the second output shaft (11b) is transmitted; a variable-speed step-up gear (14) for increasing the speed of the first output shaft (11a) and transmitting the increased speed to the first compressor (12), said step-up gear (14) being capable of varying the increased speed; and a constant-speed step-up gear (15) for increasing the speed of the second output shaft (11b) and transmitting the increased speed to the second compressor (13), said step-up gear (15) keeping the increased speed constant.