How it works
ClearSign’s Electrodynamic Combustion Control technology introduces computer-controlled high-voltage (but very low power) electric fields to manipulate the movement of electrically charged molecules (ions) that are a natural product of the combustion process. This pulsed field creates very powerful electrostatic forces (body forces) within the flame and the surrounding gas cloud. These forces can be manipulated to precisely control flame shape and the transfer of heat to, through, or away from a surface as desired. Because we can selectively target and mobilize specific charged molecules, our technology provides an unprecedented level of precision for optimizing combustion chemistry to suppress formation of pollutants at the flame source.
These short videos, narrated by ClearSign Chief Technology Officer, Joe Colannino, provide an excellent introduction to Electrodynamic Combustion Control and the key features of our technology:
This approach provides a powerful new set of tools to system operators, which can be used individually or in combination. These new tools include:
- Better combustion – less unburned fuel and better fuel/air mixing increases efficiency and reduces pollutant formation.
- Superior flame quality – optimizes flame shape and flame stability to maximize energy efficiency.
- Precision control of heat transfer – increases thermal efficiency, and therefore fuel efficiency.
- Flame attachment – safely “anchors” the flame where the operator requires, allowing for reduced NOx and lowering the risk of unstable flame conditions.
- Control over combustion reaction chemistry – enables control over flame chemistry, which can selectively promote, suppress, retard or accelerate chemical reactions as desired to minimize formation of pollutants and enhance pollution abatement.
- Agglomeration of particulate – particulate matter in exhaust is formed into large, more easily removed clusters, which is much more efficiently removed compared to particulate generated by existing technologies.
The gain in energy efficiency provided by our technology in boilers, kilns, furnaces and turbines stems in part from our ability to precisely control the flow of hot gases within a gas volume. In most cases, efficiency is increased by increasing heat flux onto targeted surfaces and reducing heat loss from other surfaces. Additionally, because the formation of pollutants is greatly reduced at the source, the ‘load’ placed on downstream pollution control equipment is also reduced, lowering both capital and operating expense and yielding a positive return on investment for system operators.
Our technology consists, in its simplest form, of four major components:
- A computer controller consisting of a standard PC
- Software delivering proprietary algorithms
- A power amplifier (resident outside the combustion chamber)
- Electrodes (placed inside the combustion chamber)
PROTOTYPES AND EXPERIMENTAL DATA
The results we have obtained from prototype systems suggest our technology will address some of the key challenges and priorities expressed by our market partners, indicating what we believe will be a rapid path to commercialization and a robust product pipeline. ClearSign’s ability to control and improve both flame chemistry and heat transfer in commercial-scale configurations for multiple fuels indicates a wide range of potential applications.
Our repeated tests using multiple fuel types including coal, tire-derived-fuel (TDF) and wood, have shown reductions in visible particulate matter (PM) of over 90% (using EPA test Method 9, a measure of visible opacity at timed intervals), with significant, simultaneous reductions in carbon monoxide (CO) and exit gas temperature (indicative of superior heat transfer to the process). In testing we have achieved such reductions in unburned carbon, CO, and particulates without increased NOX emissions. We have also demonstrated the ability to selectively and precisely control flame shape, heat transfer and heat distribution.
Early experiments and designs by the company also suggest improvements in flame stability and that the technology could be retrofitted to or even replace Low and Ultra-Low NOX burners. This may result in the potential efficiency increases on the order of 20% to 30% for a large number of industrial gas-fired boilers.
Through tests and studies conducted by our own personnel on our 5,000 Btu and 25,000 Btu scale prototypes, we have obtained the following results:
A 95% reduction in stack gas opacity is observed when ECC is engaged. A ‘birds-eye’ view down the stack demonstrates dramatically increased flame turbulence (and mixing) with the system in the “on” condition. This is achieved without the introduction of excess air and with all other parameters unchanged. When the system is deactivated, the flame
immediately returns to its previous laminar (undisrupted flow) and sooting state.
Schlieren photographs, (a laser imaging technique which enables us to view otherwise transparent heat columns) demonstrate the ability of ECC technology to impact both the flame and hot gases.
Figure (5a) is the system in the ‘off’ condition: the heat column (black bar) above the flame is unperturbed. Figure (5b) is the same flame and heat column with the system engaged. Increased turbulence and vorticity (the tendency for fluid elements to ‘spin’) is observed. Figure (5c) introduces a ground plane (right). Both the flame and heat column are strongly directed toward its surface, suggesting an increase in heat actively directed to the ‘load’, which is a primary design objective of a combustion system and directly impacts energy efficiency.
A thermal imaging camera captures a significant increase in average furnace temperature and more uniform heat distribution within two minutes of system activation. A reduction in exit gas temperature is also observed, suggesting heat transfer is shifted from the exiting flue gas and into the system. Less waste heat ‘up the stack’ results in greater system efficiency and lower fuel costs.