Dual-Flue Firebox With Door-Linked Smoke Bypass Filtration

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Solution Overview

Problem

Existing firebox systems for biomass or biofuel combustion face challenges in controlling smoke emissions and maintaining filters, leading to unsafe conditions and high maintenance costs when the door is open, as they often result in the release of fine powders and ash, and require complex maintenance that may need specialized personnel.

Innovation Solution

A firebox-chimney system with a dual pipe structure where the first pipe is associated with choking means that automatically open when the door is open and close when closed, and a filter positioned near the combustion chamber for easy access and maintenance, using a snap-in attachment mechanism for quick replacement and cleaning, ensuring optimal operativity and reduced emissions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If a filter is disposed in the chimney to reduce emissions, then filtering effectiveness is improved, but maintenance complexity increases and requires specialized personnel

Engineering Contradiction:
Improveemissions of fine powders and carbon monoxideVSAvoidmaintenance complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The filter is extracted from its traditional position within the chimney structure and relocated to the combustion chamber where it can be easily accessed. This allows the filter to remain effective in reducing emissions while enabling simple maintenance operations by ordinary users without requiring specialized personnel or complex disassembly procedures.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

A removable filter holder is introduced as an intermediary component between the combustion chamber and the chimney. This holder can be easily detached and reattached, serving as a mediator that provides both effective filtration when installed and easy access for maintenance when removed, thereby reducing maintenance complexity without compromising filtering effectiveness.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If a choking valve is provided in the chimney to control smoke flow, then smoke control is improved, but the system complexity increases

Engineering Contradiction:
Improvesmoke flow controlVSAvoidsystem complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The choking valve functionality is merged with the door assembly itself. The door incorporates a valve mechanism that automatically adjusts smoke flow based on its position - when the door is open for loading, the valve opens to allow smoke escape; when the door is closed, the valve closes to maintain proper draft. This integration eliminates the need for a separate choking valve in the chimney, reducing system complexity while maintaining effective smoke control.

Inventive Principle:
Principle #5Merging (Combining)

3Object-generated harmful factors

If the filter is positioned in difficult-to-access zones of the chimney, then filtering performance is maintained, but maintenance accessibility worsens

Engineering Contradiction:
Improvepollutant filtrationVSAvoidmaintenance accessibility
Core Design Contradiction:
Object-generated harmful factorsVSEase of operation

Solution Approach 1:

The filter is extracted from the difficult-to-access chimney interior and repositioned within the combustion chamber where it is easily accessible. The filter holder design allows for simple removal and installation from the front of the combustion chamber, enabling users to perform maintenance without needing to access confined spaces within the chimney structure, thereby improving maintenance accessibility while maintaining filtration effectiveness.

Inventive Principle:
Principle #2Taking out (Extraction)

4Ease of operation

If the door is opened during combustion, then loading and inspection are facilitated, but smoke and fine powders escape through the aperture

Engineering Contradiction:
Improveloading and inspection accessVSAvoidsmoke and powder emission through aperture
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The valve mechanism is pre-configured to automatically respond to door position changes. When the door begins to open, the valve mechanism anticipates the need for smoke escape and opens accordingly, preventing smoke and fine powders from being forced back through the aperture. This preliminary action ensures that the valve is already in the correct position to handle smoke flow before the door is fully opened, thereby preventing harmful emissions while facilitating loading and inspection.

Inventive Principle:
Principle #10Preliminary action

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 ensures safe and controlled smoke discharge, reduces maintenance costs, and allows for complete smoke filtration without the need for specialized personnel, maintaining filter effectiveness between 250°C and 450°C.

Implementation Method 1

filter means able to limit to a minimum the emission into the atmosphere of fine powders, carbon monoxide or other pollutants generated during combustion

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Implementation Method 2

a filter of the catalytic type, which, to perform at its best, must operate at temperatures comprised between 250°C and about 450°C

Methodology Applied
Scientific EffectCatalysis: Catalysis

Implementation Method 3

a choking valve is provided, for example a butterfly, normally disposed in a segment of the chimney near the combustion chamber, which serves to choke the transit section of the chimney

Methodology Applied
Scientific EffectFlow control: Valve

Implementation Method 4

The segment is provided with a first pipe and a second pipe for the passage of smoke

Methodology Applied
Scientific EffectFluid flow separation: Two-Phase Flow

Data Source

PatentEP2439446B1Firebox
Publication Date: 2018.04.11 PALAZZETTI LELIO
  • EP2439446B1 patent drawingFigure 1a~1b
  • EP2439446B1 patent drawingFigure 2~3
  • EP2439446B1 patent drawingFigure 4~5

AI summary

A firebox (10) for a combustion apparatus, advantageously but not exclusively using biomass or biofuel, comprises a base structure (11) defining a combustion chamber (12) and a chimney (13) for the smoke, and has a door (16). The chimney (13) comprises at least a segment with a flue, cooperating with the combustion chamber (12), which is provided with a first pipe (19) and a second pipe (20) for the passage of the smoke. The first pipe (19) is associated with choking means (21) and said second pipe (20) is associated with filter means (23) located, according to the direction in which the smoke travels from the combustion chamber (12) toward the outside, before the first pipe (19) merges with the second pipe (20). The choking means (21) are associated, by means of connection means, to the position of the door (16), so that, with the door (16) open, the choking means (21) are in a position of opening the first pipe (19) and with the door (16) closed the choking means (21) are in a position of closing the first pipe (19).