Stirling Engine Driven Reciprocating Compressor Waste Heat Recovery

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Solution Overview

Problem

Industrial sites using reciprocating compressors typically generate waste heat, which is not effectively utilized, leading to high power consumption in driving these compressors.

Innovation Solution

A system that integrates a Stirling engine with a reciprocating compressor, utilizing waste heat for energy recovery, and includes a supplemental electric machine to provide additional mechanical power when needed, allowing the Stirling engine and compressor to operate at the same rotational speed without the need for gearboxes, thereby improving efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a Stirling engine is used to drive the reciprocating compressor using waste heat, then power consumption is reduced and energy efficiency is improved, but the system complexity increases due to the need for thermal energy integration

Engineering Contradiction:
Improvepower consumptionVSAvoidsystem complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent converts waste heat, which is normally a harmful or useless byproduct, into useful mechanical energy to drive the reciprocating compressor. The Stirling engine utilizes the temperature difference between waste heat sources and ambient temperature to generate power, thereby reducing the need for additional energy input and improving overall system efficiency.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The Stirling engine serves multiple functions: it acts as a power source to drive the compressor, utilizes available waste heat resources, and can operate with various heat sources (combustion gases, hot water, steam). This multi-functionality reduces system complexity by using a single device for multiple purposes rather than requiring separate heating and cooling systems.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Loss of energy

If the Stirling engine and reciprocating compressor are mechanically connected to rotate at the same rotational speed, then gearboxes can be dispensed with and efficiency is improved, but the adaptability to different operational speeds is reduced

Engineering Contradiction:
Improveenergy lossVSAvoidspeed adaptability
Core Design Contradiction:
Loss of energyVSAdaptability or versatility

Solution Approach 1:

The patent merges the Stirling engine and reciprocating compressor into a directly coupled mechanical system, eliminating the need for intermediate gearboxes or speed conversion mechanisms. This direct coupling reduces energy losses associated with mechanical transmission and improves overall system efficiency by maintaining consistent rotational speed between the two components.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If a supplemental driver is provided to provide supplemental mechanical power when insufficient power is made available by the Stirling engine, then the reliability of compressor operation is improved, but the device complexity increases

Engineering Contradiction:
Improveoperational reliabilityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The supplemental driver is designed to dynamically engage or disengage based on the power requirements of the system. When the Stirling engine produces sufficient power, the supplemental driver remains inactive; when additional power is needed, the supplemental driver automatically engages to provide the necessary supplemental mechanical power, ensuring continuous reliable operation without requiring constant complex control mechanisms.

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

The system reduces power consumption by leveraging waste heat to drive the compressor, enhancing overall efficiency and allowing for flexible operation using both thermal and electric power sources.

Implementation Method 1

the Stirling engine exploits waste heat from a thermal energy source for waste heat recovery (whr) purposes

Methodology Applied
Scientific EffectStirling cycle: Stirling Cycle

Implementation Method 2

When operating as a generator, the electric machine converts surplus mechanical power from the Stirling engine into electric power. When operating in the motor mode the electric machine can operate as a helper to supplement mechanical power

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentEP3099917B1A compressor train with a stirling engine
Publication Date: 2023.10.11 NUOVO PIGNONE TECH SRL
  • EP3099917B1 patent drawingFigure 1A
  • EP3099917B1 patent drawingFigure 1B~2
  • EP3099917B1 patent drawingFigure 3~4

AI summary

The system for driving a reciprocating compressor comprises a reciprocating compressor (1) with a crankshaft (31). A Stirling engine (50) is drivingly connected to the crankshaft (31) of the reciprocating compressor (1). A heat source (71), for example a waste heat source, provides heat to the hot end of the Stirling engine. Heat is partly converted into mechanical power to drive the reciprocating compressor (1).