Boiler Back-Pass Layout for Compact Air Preheater Integration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Large thermal power boilers face challenges with increasing size, leading to higher construction costs and complex channel structures due to the conventional arrangement of flue gas and combustion air channels, which results in long and complicated designs.
Innovation Solution
The thermal power boiler design features two adjacent channel portions for the flue gas inlet connected to opposite sides of the back pass, allowing for a compact and symmetrical arrangement of the pre-heater for combustion air, with the flue gas channels being mostly vertical and the pre-heater positioned close to the furnace, reducing channel length and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the furnace, back pass and pre-heater for combustion air are arranged conventionally one after another, then the boiler capacity can be increased, but the channel structure becomes long and complicated
Solution Approach 1:
The pre-heater is repositioned from a linear sequential arrangement to a spatial configuration where it extends sideways from the back pass. This dimensional change allows the flue gas channel to connect directly to the pre-heater without requiring long horizontal or inclined channel portions, thereby reducing channel complexity while maintaining boiler capacity.
Solution Approach 2:
Instead of extending the flue gas channel away from the furnace in conventional directions, the channel is redirected to extend sideways from the back pass. This inverted arrangement approach simplifies the channel structure by eliminating the need for complex bends and long channel portions while still achieving the required heat exchange function.
2Ease of operation
If the flue gas channel comprises long horizontal or inclined channel portions, then the pre-heater can be positioned away from the furnace, but the overall boiler size increases
Solution Approach 1:
The pre-heater is positioned by extending it sideways from the back pass rather than using long horizontal or inclined channel portions. This spatial reconfiguration achieves positioning flexibility in a compact volume, reducing the overall boiler size while maintaining operational flexibility.
3Ease of manufacture
If the flue gas channel is arranged with multiple bends and portions, then the pre-heater can be connected to the back pass, but the construction costs increase
Solution Approach 1:
Instead of using multiple bends and channel portions to connect the pre-heater to the back pass, the invention inverts the conventional approach by extending the flue gas channel sideways from the back pass. This simplified arrangement reduces construction complexity and costs while achieving the required connection.
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 arrangement minimizes the size of the boiler, reduces construction costs, and decreases pressure losses in the air channels, resulting in lower power consumption and simpler geometry, while maintaining efficient particle separation and pre-heating of combustion air.
Implementation Method 1
In the recuperative pre-heaters, heat is conducted through heat surfaces directly from the flue gas to the combustion air
Implementation Method 2
In the regenerative pre-heaters, the flue gas first heats storage mass, usually a metal or a ceramic battery, which, in the second stage, emits heat to the combustion air
Data Source
AI summary
A thermal power boiler includes a furnace having a rear wall. A flue gas channel connected to the furnace includes a vertical back pass arranged on the rear wall side of the furnace. An ash hopper in the lower portion of the back pass has (i) a front wall, (ii) a rear wall, and (iii) two sidewalls. A pre-heater preheats combustion air and is provided with an inlet channel for flue gas connected to the preheater. The inlet channel has vertical portions, with an upper portion being attached to the lower portion of the back pass near the ash hopper. The inlet channel includes two adjacent channel portions connected to opposite sides of the back pass. One of the two portions is directly connected to the front wall of the ash hopper, and the other is directly connected to the rear wall of the ash hopper.