Pneumatic Mixture Formation in Premix Burner
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Solution Overview
Problem
Existing pneumatic control systems for premix burners face issues with reference pressure fluctuations due to pressure losses downstream of the throttle point, leading to potential fuel gas under-supply and system shutdowns.
Innovation Solution
The introduction of an inlet preliminary stage with a narrowed area and pressure removal openings upstream of the throttle point reduces the reference pressure, making it less susceptible to downstream pressure losses, ensuring a stable fuel gas supply by measuring the reference pressure in a dynamic and static pressure-dependent manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the reference pressure is taken between the blower and the fuel gas inlet, then the reference pressure reflects the air flow generated by the blower, but downstream pressure losses cause the reference pressure to become too high, leaving the control range and reducing fuel gas supply
Solution Approach 1:
The control line is divided into two separate lines: a first control line that taps reference pressure upstream of the throttle point (Venturi nozzle) and a second control line that taps reference pressure downstream of the throttle point. This segmentation allows the system to compensate for downstream pressure losses by combining pressure information from both locations, maintaining reliable fuel gas supply control even when downstream pressure varies.
2Productivity
If a throttle point (Venturi nozzle) is used to generate air flow, then air flow is directed to the burner, but pressure losses downstream of the throttle point strongly influence the reference pressure, potentially causing system shutdown
Solution Approach 1:
The system applies preliminary anti-action by introducing a compensating pressure signal from downstream of the throttle point into the control line upstream of the throttle point. This compensating signal counteracts the harmful influence of downstream pressure losses before they can affect the reference pressure and fuel gas supply control, preventing system shutdown.
3Quantity of substance
If the reference pressure becomes too high due to downstream pressure losses, then the difference between reference pressure and fuel gas supply pressure becomes too small, but this causes the fuel gas flow to approach zero and reduces combustion stability
Solution Approach 1:
The system uses feedback by continuously monitoring the reference pressure at two locations (upstream and downstream of the throttle point) and using this information to adjust the fuel gas control valve. The feedback mechanism ensures that the fuel gas flow is maintained within the optimal control range, preventing the flow from approaching zero and maintaining stable combustion even when downstream pressure conditions change.
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 solution maintains a reliable fuel gas supply even with high pressure losses, preventing system shutdowns and ensuring consistent combustion by calibrating the fuel gas control valve to compensate for reduced reference pressure.
Implementation Method 1
a blower (2) generates an air flow (4) which is fed to the burner (3) via a throttle point (6), here in the form of a Venturi nozzle
Implementation Method 2
throttle point (6), here in the form of a Venturi nozzle
Implementation Method 3
fuel gas is added upstream of or in the throttle point via a fuel gas control valve (9)... the reference pressure (Pref) determines whether and to what extent the fuel gas control valve (9) opens
Data Source
Figure 1~2
AI summary
The invention relates to a method and an arrangement for the pneumatic formation of a mixture for a burner (3) with a blower (2) for generating an airflow which is fed to the burner (3) via a throttle point (6), wherein fuel gas can be added upstream or in the throttle point (6) via a fuel gas control valve (6), with a reference pressure measuring point (13) between the blower (2) and the throttle point (6) in an inlet pre-stage (8) upstream of the throttle point (6) which influences the airflow and is connected to the fuel gas control valve (9) via a control line (14). In particular, the inlet pre-stage (8) is designed such that a reduced reference pressure (Pref) can be taken from the reference pressure measuring point (13), wherein the inlet pre-stage (8) has a constricted section (16) in which at least one pressure sampling port (12) is provided which is connected to the reference pressure measuring point (13).Each pressure tap opening (12) can have a chamfer (15) at least on a downstream edge (17). The present invention makes it possible to tap a reduced reference pressure (Pref) for controlling the fuel gas supply in a heating device (1), whereby pressure losses in the exhaust gas duct (10) of the heating device (1) no longer have a negative effect and reliable control of a fuel gas control valve (9) is possible even with changing pressure losses.