Fume By-Pass for Condensing Boilers to Prevent Stack Acid Condensation

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Solution Overview

Problem

Condensing boilers face issues with acid condensation in stacks due to cooling, requiring expensive, sealed, and specific stack designs, limiting their installation to traditional systems, and existing solutions are complex and invasive.

Innovation Solution

A fume by-pass system that heats combustion fumes from condensing boilers to prevent condensation by mixing hot and cold fumes outside the condensation zone, ensuring they remain above the dew point, using a tubular body with a discharge section and insulating layer to maintain temperature and prevent re-evaporation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If condensing boilers are installed in traditional stacks, then cost is reduced and installation versatility is improved, but acid condensation occurs and reliability deteriorates

Engineering Contradiction:
Improveinstallation versatilityVSAvoidreliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces an intermediary heating device that heats the combustion fumes before they enter the stack. This intermediary device acts as a mediator between the condensing boiler and the traditional stack, preventing acid condensation by maintaining fume temperature above the dew point, thus enabling reliable operation in traditional stacks without requiring specialized corrosion-resistant stacks.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If specialized sealed and chemically resistant stacks are used, then reliability is improved and acid condensation is prevented, but cost increases

Engineering Contradiction:
ImprovereliabilityVSAvoidcost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of using expensive specialized stacks, the patent employs a simpler intermediary heating device that maintains fume temperature. This approach achieves the same reliability benefit (preventing acid condensation) through a lower-cost solution that can be installed in existing traditional stacks, avoiding the need for expensive specialized stack construction.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the temperature parameter of the combustion fumes by introducing a heating device that maintains fume temperature above the dew point. This parameter change prevents acid condensation formation, achieving the same effect as specialized stacks but through a different, more cost-effective mechanism.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If fumes are heated to prevent condensation, then reliability is improved and acid condensation is prevented, but energy consumption increases

Engineering Contradiction:
ImprovereliabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent optimizes the heating parameter to maintain fume temperature only above the dew point threshold, rather than excessive heating. This controlled parameter change prevents acid condensation while minimizing unnecessary energy consumption, achieving the minimum required temperature maintenance for reliable operation.

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

Enables condensing boilers to connect to any stack type, preventing acid condensation and promoting natural draft without performance reduction, allowing for unified boiler models that transform from condensing to non-condensing boilers, and reducing energy consumption.

Implementation Method 1

A fume by-pass system that heats combustion fumes from condensing boilers to prevent condensation by mixing hot and cold fumes outside the condensation zone

Methodology Applied
Scientific EffectMixing:

Implementation Method 2

using a tubular body with a discharge section and insulating layer to maintain temperature and prevent re-evaporation

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 3

using a tubular body with a discharge section and insulating layer to maintain temperature and prevent re-evaporation

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 4

A fume by-pass system that heats combustion fumes from condensing boilers to prevent condensation by mixing hot and cold fumes outside the condensation zone, ensuring they remain above the dew point

Methodology Applied
Scientific EffectCondensation prevention: Condensation

Data Source

PatentEP2667112B1Fume by-pass for condensing boilers
Publication Date: 2017.05.03 ARISTON THERMO SPA
  • EP2667112B1 patent drawingFigure 1
  • EP2667112B1 patent drawingFigure 2
  • EP2667112B1 patent drawingFigure 3~4

AI summary

The object of the present invention is a by-pass (5) installable in a heat exchanger (1) of a thermal generator for room heating and/or for the production of domestic hot water, in particular of the condensation type, apt to place in direct communication the hot chamber (21) of the sensitive portion (SS) of said heat exchanger (1) with the cold chamber (22) of the condensing portion (SC) of said exchanger (1). The by-pass (5) allows a portion P of the hot combustion fumes F generated therein by a burner to be withdrawn from said sensitive portion (SS) for mixing them with the cold fumes F-P, escaping from said condensing portion (SC), cold by the effect of the thermal exchange with said heat exchanger (1). Said mixing brings the combustion fumes F escaping from said heat exchanger (1) to a sufficiently high temperature to prevent the condensation thereof in the discharge system to the atmosphere.