Method for burning a liquid or gaseous fuel in a boiler, boiler for carrying out the method and thermal bath having a boiler
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Solution Overview
Problem
Conventional boiler burners face challenges in achieving soot-free, low-emission combustion in miniaturized spaces with complex adjustment requirements, limited output regulation, and issues with 'metal dusting' when using renewable fuels, while also requiring fuel preheating and having inefficient combustion processes.
Innovation Solution
A method that adjusts blower pressure to create a differential pressure zone in the flame tube, allowing for a stable blue flame with immediate exhaust gas values compliance, wide output regulation, and eliminating the need for fuel preheating, using a design with a short flame tube and recirculation of low-oxygen combustion gases to ensure complete combustion and prevent 'metal dusting'.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a yellow flame burner is used with high combustion air pressure, then the fuel vaporizes completely and combustion is intense, but nitrogen oxide emissions increase and soot is produced
Solution Approach 1:
The invention changes the pressure parameter by generating negative pressure in the combustion chamber (between -0.5 and -2.0 mbar) instead of using positive pressure. This parameter change fundamentally alters the combustion dynamics, allowing complete vaporization and intense combustion without the harmful effects of high positive pressure, thereby reducing nitrogen oxide emissions and soot formation.
Solution Approach 2:
The invention inverts the conventional approach by using negative pressure instead of positive pressure to drive combustion. The exhaust fan creates a vacuum that pulls air through the burner and fuel vaporization chamber, reversing the traditional pressure-driven combustion mechanism and eliminating the associated harmful emissions.
2Object-generated harmful factors
If a blue flame burner is used with negative pressure to reduce emissions, then nitrogen oxide emissions decrease, but the combustion chamber pressure becomes too low allowing exhaust gases to enter the boiler room
Solution Approach 1:
The invention uses dynamic pressure control through a variable speed exhaust fan that continuously adjusts the negative pressure in the combustion chamber. This dynamic adjustment maintains the pressure within the optimal range of -0.5 to -2.0 mbar, ensuring emissions are reduced while preventing exhaust gases from leaking into the boiler room.
Solution Approach 2:
The system incorporates feedback control where the exhaust fan speed is automatically adjusted based on the combustion chamber pressure conditions. This feedback mechanism ensures that the negative pressure remains within the specified range, balancing emission reduction with combustion chamber integrity and preventing exhaust gas leakage.
3Volume of stationary object
If the boiler is miniaturized to reduce space, then the compactness increases, but the combustion chamber volume decreases making it difficult to achieve complete combustion
Solution Approach 1:
The invention uses pneumatic principles by creating controlled negative pressure flow conditions that enhance fuel vaporization and air-fuel mixing efficiency. The vacuum-driven flow dynamics ensure complete combustion occurs rapidly in the small combustion chamber volume, allowing miniaturization without sacrificing combustion performance or chamber load capacity.
Solution Approach 2:
The invention changes the pressure parameter to negative values, which fundamentally alters the combustion characteristics. This parameter change enables efficient fuel vaporization and combustion in a compact space by creating strong flow velocities and enhanced mixing, thereby maintaining high combustion chamber load despite reduced volume.
4Device complexity
If renewable fuels are used without preheating, then the system complexity is reduced and energy costs decrease, but incomplete combustion and metal dusting occur
Solution Approach 1:
The invention performs preliminary vaporization of the fuel in a dedicated vaporization chamber before combustion. The negative pressure draws air through this chamber, where fuel droplets are vaporized by the hot air stream. This preliminary action ensures complete combustion and prevents metal dusting without requiring external preheating systems, thereby reducing device complexity.
Solution Approach 2:
The system uses the combustion process itself to provide the heat needed for fuel vaporization. The hot exhaust gases and combustion air automatically vaporize incoming fuel droplets in the vaporization chamber, creating a self-sustaining process that eliminates the need for separate preheating equipment while ensuring complete combustion.
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 solution enables a soot-free, low-emission combustion process with a stable blue flame, high combustion chamber load, and wide output regulation, reducing energy costs and extending burner service life, while being suitable for renewable fuels without preheating and minimizing 'metal dusting'.
Implementation Method 1
a blower pressure is adjusted such that downstream of the faceplate, at full load of the burner, a differential pressure zone is generated in the flame tube with a differential pressure of at least 0.25 mbar
Implementation Method 2
a negative pressure generated behind the nozzle sucks hot exhaust gases back out of the flame tube. These vaporize the oil mist and enable a much better mixture with the combustion air
Implementation Method 3
Recirculation openings at the beginning of the flame tube also draw cooled combustion gases out of the combustion chamber. These reduce the combustion temperature and therefore also the nitrogen oxide emissions
Implementation Method 4
a blue flame burner, which burns independently of the furnace chamber with low exhaust gas emissions and calm combustion
Implementation Method 5
A further advantage lies in higher CO2 content of the exhaust gases. This is because the higher CO2 content raises the dew point and thus promotes the condensing effect
Data Source
AI summary
A method and a boiler for burning a liquid or gaseous fuel. The boiler comprises a boiler housing with a cylindrical heat exchanger arranged therein and has slot-like pass-through openings for the combustion gases and has a flame tube. A flame-deflecting part for deflecting the combustion gases at a right angle is provided at an axial distance from the flame tube. The flame tube contains a baffle plate with a faceplate through which combustion air is fed into the flame tube. A blower ensures the supply of combustion air into the combustion chamber. Blower pressure is so that a differential pressure zone with a differential pressure of at least 0.25 mbar is generated between the flame tube and the heat exchanger, downstream of the faceplate at full load of the burner in relation to the pressure in the combustion chamber in the region of the recirculation slots.