Precombustion Chamber Gas Engine Torch Control

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Solution Overview

Problem

Precombustion-chamber type gas engines face challenges in achieving high thermal efficiency while minimizing NOx emissions and combustion variation, with existing control methods not effectively managing torch strength and pressure dynamics.

Innovation Solution

The implementation of a system that includes a torch strength information acquisition device, a precombustion-chamber gas supply amount calculation device, and a supply pressure control valve, which adjusts fuel gas pressure based on differential pressure and ratio between the precombustion and main chambers to optimize torch strength for high thermal efficiency and stable combustion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fuel gas supply pressure is increased to strengthen torch combustion, then combustion completeness improves, but thermal efficiency decreases due to excessive energy loss

Engineering Contradiction:
Improvecombustion completenessVSAvoidthermal efficiency
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The system dynamically adjusts the fuel gas supply pressure parameter based on real-time differential pressure measurements between precombustion and main chambers. By changing the pressure parameter adaptively rather than maintaining a fixed high pressure, the system achieves complete combustion only when necessary, thereby improving thermal efficiency while maintaining combustion completeness.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The control system uses feedback from differential pressure sensors to regulate the fuel gas supply pressure. The measured pressure difference between precombustion chamber and main chamber feeds back to the pressure control valve, which adjusts the fuel gas pressure accordingly. This closed-loop feedback mechanism prevents excessive pressure application, reducing energy loss while ensuring adequate torch strength for complete combustion.

Inventive Principle:
Principle #23Feedback

2Reliability

If check valve is added to prevent fuel gas reverse flow, then fuel gas supply reliability improves, but device complexity increases

Engineering Contradiction:
Improvefuel gas supply reliabilityVSAvoidgas supply passage complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The check valve acts as an intermediary component in the fuel gas supply passage, automatically preventing reverse flow without requiring complex control systems or additional active components. This passive intermediary device simplifies the overall system while improving fuel gas supply reliability by eliminating the need for complex reverse flow prevention mechanisms.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Speed

If precombustion-chamber gas supply amount is increased to strengthen torch, then combustion speed improves, but NOx emissions increase

Engineering Contradiction:
Improvecombustion speedVSAvoidNOx emissions
Core Design Contradiction:
SpeedVSObject-generated harmful factors

Solution Approach 1:

The system optimizes the precombustion-chamber gas supply amount by dynamically adjusting the fuel gas pressure parameter based on differential pressure conditions. Rather than maintaining a constantly high gas supply rate, the system adjusts the parameter to provide sufficient torch strength for complete combustion while avoiding excessive gas amounts that would generate NOx emissions, thus resolving the contradiction between combustion speed and emissions.

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 solution enhances thermal efficiency, reduces NOx emissions, and stabilizes combustion by precisely controlling the precombustion-chamber gas supply pressure, thereby improving engine operation and reducing combustion variation.

Implementation Method 1

a check valve disposed in the precombustion-chamber gas supply passage

Methodology Applied
Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

a supply pressure control valve disposed upstream of the check valve in the precombustion-chamber gas supply passage and capable of adjusting the pressure of the fuel gas supplied to the precombustion chamber

Methodology Applied
Scientific EffectMechanical pressure control: Valve

Implementation Method 3

the ignition plug sparks in the precombustion chamber

Methodology Applied
Scientific EffectElectrical discharge: Electric Spark

Implementation Method 4

flame propagation combustion occurs in the precombustion chamber. The combustion gas produced in the precombustion chamber is injected into the main chamber via the injection nozzle as a torch, and combusts the air-fuel mixture in the main chamber through torch combustion and flame propagation combustion

Methodology Applied
Scientific EffectCombustion: Combustion

Implementation Method 5

The combustion gas produced in the precombustion chamber is injected into the main chamber via the injection nozzle as a torch

Methodology Applied
Scientific EffectPressure-driven flow: Jet

Data Source

PatentEP3392487B1Auxiliary chamber gas engine and method for controlling operation of said engine
Publication Date: 2020.02.05 MITSUBISHI HEAVY IND ENGINE & TURBOCHARGER LTD
  • EP3392487B1 patent drawingFigure 1
  • EP3392487B1 patent drawingFigure 2
  • EP3392487B1 patent drawingFigure 3

AI summary

A precombustion-chamber type gas engine, comprising includes: a check valve disposed in the precombustion-chamber gas supply passage and configured to block a backflow of fuel gas from a precombustion chamber; a supply pressure control valve which is disposed on an upstream side of the check valve in the precombustion-chamber gas supply passage and which is capable of adjusting a pressure of the fuel gas to be supplied to the precombustion chamber; a torch strength information acquisition device configured to obtain torch strength information correlated to strength of a torch from the injection nozzle, on the basis of a pressure in the main chamber and a pressure in the precombustion chamber; a precombustion-chamber gas supply amount calculation device configured to calculate an amount of the fuel gas to be supplied to a precombustion-chamber gas supply amount, on the basis of the torch strength information and correlation information representing a correlation between the torch strength information, a thermal efficiency, and the precombustion-chamber gas supply amount; and a precombustion-chamber gas supply pressure control device configured to control the supply pressure control valve on the basis of the precombustion-chamber gas supply amount calculated by the precombustion-chamber gas supply amount calculation device.