Depth Filter Flue Gas Cleaning for Low-Maintenance Fine Dust Separation

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Solution Overview

Problem

Existing small combustion plants face challenges in reliably separating fine dust and condensate components like tars without frequent maintenance, as conventional electrostatic precipitators are prone to blockage and require manual cleaning, while depth filters are not established for this application.

Innovation Solution

A flue gas cleaning device with a depth filter system, including a flue gas damper and a collection chamber, is integrated into the flue gas path, using a radial fan for operation and incorporating thermal protection mechanisms to manage temperature fluctuations and ensure robust, low-maintenance filtration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If electrostatic precipitators are used for fine dust separation in small combustion systems, then submicrometer separation efficiency of approximately 95% can be achieved, but the free flow cross-section decreases with increasing operating time due to dust deposition on walls, increasing flow resistance and requiring frequent manual maintenance

Engineering Contradiction:
Improveseparation efficiencyVSAvoidoperational reliability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The device segments the filtration function into two independent parts: an electrostatic precipitator for fine dust separation and a depth filter for coarse dust and tar removal. This segmentation prevents coarse dust and tar from accumulating on the electrostatic precipitator walls, maintaining its separation efficiency and reducing maintenance needs.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The depth filter performs preliminary cleaning by removing coarse dust and tar before the flue gas enters the electrostatic precipitator. This preliminary action protects the electrostatic precipitator from contamination, ensuring it operates reliably without frequent manual cleaning.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If a growing layer of fine dust accumulates on the flue gas path surface, then the separation efficiency of the electrostatic precipitator is reduced, but manual cleaning must be performed up to several times a month increasing maintenance effort

Engineering Contradiction:
Improveseparation efficiencyVSAvoidmaintenance time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The filtration system is segmented into a depth filter that handles coarse dust and tar removal, protecting the electrostatic precipitator from materials that would require frequent cleaning. This segmentation reduces maintenance time while preserving separation efficiency.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The depth filter acts as an intermediary between the flue gas and the electrostatic precipitator, removing harmful substances (coarse dust and tar) before they reach the precipitator. This intermediary function prevents accumulation that would reduce efficiency and require maintenance.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If the free flow cross-section decreases due to dust deposition, then flow resistance increases impairing free flue gas discharge, but the furnace operation is negatively impacted

Engineering Contradiction:
Improvedust capture efficiencyVSAvoidflue gas discharge
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The system segments dust capture functions by using a depth filter for coarse dust and tar (which would block flow) and an electrostatic precipitator for fine dust. This segmentation maintains free flow cross-section and flue gas discharge while achieving effective dust capture.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The depth filter serves as an intermediary that removes coarse dust and tar before they can deposit on flue gas path surfaces and block flow. This protects flue gas discharge productivity while the electrostatic precipitator handles fine dust capture efficiently.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 effectively separates fine dust and condensate components, ensuring compliance with emission regulations while reducing maintenance needs and extending the service life of the filtration system.

Implementation Method 1

an electrostatic field is generated in the gas stream to be cleaned using a high-voltage generator and a negatively charged discharge electrode, in which dust particles become electrostatically charged

Methodology Applied
Scientific EffectElectrostatic field: Electric Field

Implementation Method 2

Due to the electrostatic field forces, the negatively charged dust particles move to a positively or neutrally charged discharge electrode, where they adhere and are removed from the gas stream

Methodology Applied
Scientific EffectElectrostatic deposition: Electrostatic Deposition

Implementation Method 3

a filter element (50) arranged between the inlet opening (66) and the outlet opening (68)... a depth filter having a filter material made of plastic (fibres), metal (fibres), textile, felt and/or ceramic is provided, which is designed to separate fine dust, condensate and/or condensate components

Methodology Applied
Scientific EffectPhysical filtration: Filter (physical)

Data Source

PatentEP4382188B1Fine dust separation device for small firing installations
Publication Date: 2026.05.20 DEZENTEC GMBH
  • EP4382188B1 patent drawingFigure 1~3
  • EP4382188B1 patent drawingFigure 4~6
  • EP4382188B1 patent drawingFigure 7~9

AI summary

The present invention relates to a device for filtering fine dust, in particular for small solid fuel combustion plants, comprising an extraction unit (30) and a filter unit (60) with a filter element (50) which is preferably designed as an automatably cleanable electrostatic precipitator or depth filter and has protection against smoldering or glowing fires of the separated and stored quantities of fine dust and/or against the uncontrolled and unnoticed spread of potentially hazardous carbon monoxide emissions.