Multi-pass boiler and retrofit method for an existing single-pass boiler
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Solution Overview
Problem
Existing single-pass boilers are inefficient due to their design, leading to high breech temperatures and excessive heat loss, resulting in increased heating oil consumption and operational costs, making it economically challenging to upgrade to more efficient multi-pass boilers.
Innovation Solution
Retrofitting existing single-pass boilers by replacing one or two intermediate sections with new sections that divert hot flue gases through multiple passes within the heat exchanger, increasing the heat exchange surface area and improving gas flow dynamics, allowing for a multi-pass configuration without the need for complete replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single-pass boiler design is used, then the device complexity is low and ease of manufacture is high, but the heat exchange efficiency is poor and fuel consumption is high
Solution Approach 1:
The boiler is divided into multiple sections (front section, intermediate sections, rear section) that can be assembled together. Each section contains specific flue passage configurations that collectively create the multi-pass flow pattern, allowing the complex heat exchange function to be achieved through modular segmentation rather than a single complex structure
Solution Approach 2:
The flue gas flow is redirected from a simple linear single-pass path to a multi-dimensional multi-pass path that moves horizontally and vertically through different flue passages. The draft diverter creates a three-dimensional flow pattern where gases traverse the heat exchanger multiple times in different directions, increasing heat exchange efficiency without proportionally increasing structural complexity
2Productivity
If a multi-pass boiler configuration is implemented, then heat exchange efficiency improves and fuel consumption decreases, but the cost of complete replacement becomes prohibitively expensive
Solution Approach 1:
Instead of requiring complete boiler replacement to achieve multi-pass configuration, the invention applies partial modification by replacing only critical intermediate sections that contain the draft diverter and target wall components. This partial action is sufficient to redirect flue gas flow into a multi-pass pattern while preserving the majority of the existing boiler structure, dramatically reducing retrofit costs
Solution Approach 2:
The draft diverter and target wall act as intermediary components that mediate between the existing single-pass boiler structure and the desired multi-pass flow pattern. These intermediate components redirect flue gas flow without requiring complete structural overhaul, serving as the key elements that enable efficient multi-pass operation in a retrofitted boiler
3Ease of operation
If intermediate sections are replaced with new sections including draft diverter and target wall, then flue gas flow is redirected for multi-pass operation, but the manufacturing complexity of replacement sections increases
Solution Approach 1:
The replacement intermediate sections are designed as self-contained modular units that include the draft diverter, target wall, and flue passages as integrated components. This segmentation allows each replacement section to be manufactured independently with standardized configurations, making the increased manufacturing complexity manageable through modular production rather than custom fabrication
Solution Approach 2:
The replacement sections utilize standard cast iron materials and conventional casting processes, maintaining consistent manufacturing parameters with existing boiler sections. By keeping material properties and fabrication methods unchanged while modifying only the internal flow geometry, the manufacturing complexity increase is minimized despite the enhanced gas flow control capabilities
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 approach enhances boiler efficiency, reduces fuel consumption, and lowers operational costs by achieving lower exhaust gas temperatures, thereby improving heat transfer and maintaining a more uniform combustion temperature, while being a cost-effective and permanent solution.
Implementation Method 1
heat exchange surface area
Implementation Method 2
gas flow dynamics
Implementation Method 3
multi-pass configuration
Implementation Method 4
combustion temperature
Data Source
AI summary
An existing single-pass sectional boiler is retrofitted with one or two replacement sections to become a multi-pass boiler. One intermediate section of the original boiler is replaced by a new section having a downwardly extending water-filled target wall portion that divides the original combustion chamber into a smaller combustion chamber on the front side and a heat exchange chamber on the rear side of the target wall portion. The target wall portion also forces at least most of the combustion gas to flow from the combustion chamber upwardly through a first flue passage of the boiler's heat exchanger, into the upper flue collector chamber. Another intermediate section of the original boiler may be replaced by a new section having an upwardly extending draft diverter portion, or a draft diverter is installed in the upper flue collector chamber, to divert the flue gas back downwardly through a second flue passage of the heat exchanger to the heat exchange chamber. From there, the flue gas flows again upwardly through a third flue passage of the heat exchanger to the breech.