Venturi Damper Burner Modulation for High Turndown Heating
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Solution Overview
Problem
Conventional gas fired burner technologies have limited turndown ratios, requiring frequent cycling and increased mechanical complexity, which is costly and inefficient for modulating heat input over a wide range of demands.
Innovation Solution
A burner assembly with a variable speed blower, venturi, and damper valve system that modulates air and fuel flow through smaller and larger gas valves, allowing for a high turndown ratio of at least 25:1 by varying blower speed and air flow restriction, enabling efficient operation across a wide range of heat demands with reduced complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single chamber burner with fixed flow rate is used, then the system is simple, but the turndown ratio is limited and frequent cycling occurs
Solution Approach 1:
The burner is divided into multiple chambers (first chamber and second chamber) with separate fuel and air supply systems. Each chamber can operate independently or simultaneously, allowing the system to achieve a wide turndown ratio (e.g., 25:1) by selectively activating chambers based on heat demand, thereby resolving the contradiction between structural simplicity and adaptability.
2Adaptability or versatility
If dual blower assemblies are used to achieve high turndown ratio, then the turndown ratio increases to 25:1, but the mechanical complexity and cost increase
Solution Approach 1:
A single blower assembly performs multiple functions by selectively supplying air to different chambers based on operational requirements. The blower can serve both the first chamber and the second chamber, eliminating the need for separate dual blower assemblies while maintaining the high turndown ratio capability, thus reducing mechanical complexity and cost.
3Device complexity
If conventional burners cycle on and off frequently, then the mechanical complexity is reduced, but the loss of time and energy efficiency decrease
Solution Approach 1:
The multi-chamber burner enables continuous modulation of heat output by varying the number of active chambers and their individual flow rates, maintaining appliance operation for extended periods without cycling. This continuous operation improves energy efficiency and reduces time loss associated with frequent start-stop cycles, while the control system manages chamber activation to achieve this continuity.
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 achieves efficient modulation of heat input with a high turndown ratio, extending appliance operation periods and reducing mechanical complexity and costs, while maintaining stability and efficiency across varying demand levels.
Implementation Method 1
A venturi includes a venturi inlet, a venturi outlet, and a reduced pressure zone intermediate of the venturi inlet and the venturi outlet. The blower inlet is communicated with the venturi outlet such that the blower pulls air through the venturi. At least one gas valve is communicated with the reduced pressure zone such that the at least one gas valve supplies fuel gas to the reduced pressure zone at a fuel gas flow rate corresponding to a pressure in the reduced pressure zone.
Data Source
AI summary
A modulating burner apparatus includes a burner and a blower placed upstream of the burner. A venturi is placed upstream of the blower. A damper valve is placed upstream of the venturi. The damper valve has an open position and a restricted position. A smaller gas valve and a larger gas valve are communicated with the venturi. A controller is operably associated with the system to select a position of the damper valve and to select the appropriate one of the gas valves so as to provide a low output operation mode and a high output operation mode, which in combination provide an overall turndown ratio of at least 25:1.