Compliance with the specifications of the BImSchV and also the requirements of market monitoring ensure that firing systems have to be shut down or else equipment to reduce emissions has to be retrofitted.
Catalytic converters, which are integrated directly into the combustion chamber of wood firing systems, are an inexpensive and very effective way to remain safely below the emission limits in the future.
Blue Fire GmbH has developed a special catalytic converter for such furnaces and applications. With the use of these catalysts, lower emission limits can also be safely undercut in the future.
The Blue Fire catalysts are installed directly in the upper area of the combustion chamber of wood firing systems. Only in this area are the temperatures sufficiently high for oxidation at the catalyst. Blue Fire catalysts are oxidation catalysts. They therefore require an excess of oxygen in the combustion process in order to bring the exhaust gas components into contact with the excess oxygen. The catalytic reaction takes place on the catalyst surface.
The exhaust gases from the combustion flow through the catalytic converter and come into contact with the special active surface of the Blue Fire catalytic converter. The catalyst reduces the activation energy of the reactants, which is necessary for the reaction of oxidisable exhaust gas components and thus for the uptake of oxygen in order to obtain CO2 from them.
The reaction at the catalyst surface is an additional reaction step in which the oxidisable exhaust gas components can react with oxygen. In principle, the oxidisable gases of a wood burner react at high temperatures already in the gas phase, i.e. directly in the flame. This happens directly above the burning logs and below the flame baffle in the combustion chamber. The gases then cool down on their way to the flue pipe. Thus, the reaction speed of the oxidation also decreases. However, there are still many oxidisable components in the gas, such as CO, which must be converted with oxygen to CO2. For this purpose, the activation energy of the reaction partners is reduced by the catalyst and thus the reaction to CO2 is accelerated.
In order to offer the exhaust gas components the largest possible catalytically effective surface, Blue Fire uses sponge ceramics as catalyst carriers. However, all other common catalyst carrier systems are also possible for coating with the Blue Fire catalyst.
Blue Fire catalysts are not consumed in the process described above. The catalyst is therefore to be regarded as an aid to bring about the activation energy for a reaction of CO and VOC at an already reduced temperature.
If the Blue Fire catalysts are properly dimensioned, it is possible to reduce the CO concentration in the exhaust gas by at least 50 %.
When flowing through the catalytic converter, the exhaust gas flow becomes turbulent in order to create as much surface contact as possible on the catalytic converter. Blue Fire customers report a slight increase in combustion efficiency when using the Blue Fire catalyst. .
The operator should be aware of the following: The catalytic converter can be damaged by the user if it is permanently exposed to an excessively high temperature of over 800 °C or if, for example, logs are struck against the catalytic converter. When used properly, a Blue Fire catalytic converter will last at least three heating periods without deactivation being detected. Long-term tests were carried out during the development of the catalytic converter and are still being carried out.
Lighting the wood burner does not damage the Blue Fire catalytic converter, even if the flames briefly strike the catalytic converter. It is recommended that catalytic converters are always installed so that they are protected by a flame baffle plate. Such a flame baffle plate ensures that the flame tips strike this element and not the catalysts directly.
Dust accumulates on the surface of the Blue Fire catalytic converter facing the combustion chamber. This dust, which originates from wood combustion, accumulates on the upstream side of the catalytic converter. The dust contains soot, which in turn consists of unburnt carbon and other low-volatile CnHm molecules. When the dry dust is deposited on the catalyst surface, the soot is decomposed and brought into contact with oxygen and reacts to form CO2 and mineral residual dust. The Blue Fire catalytic converter therefore also reduces the soot content of the deposited dust. This in turn reduces the total mass of dust emitted. Due to this effect, the Blue Fire catalytic converter can reduce the dust content in the exhaust gas by up to 20 %. The residual dust deposited on the catalytic converter surface must be cleaned at regular intervals and depending on the frequency of use. This is best done using a suitable hoover and an attached brush, in boiler systems by means of compressed air cleaning.
Blue Fire GmbH has developed standard catalytic converters which, due to their external dimensions, can be installed in many different combustion chamber geometries. In this way, manufacturers and operators of wood-burning stoves, fireplace inserts but also log or wood chip boilers can use the same catalytic converter. For larger quantities, Blue Fire GmbH can reduce the manufacturing costs accordingly, so that manufacturers and operators benefit from the price advantage.
The engineers at Blue Fire GmbH look after each application personally, since every furnace, every stove, every fireplace insert and every boiler has different temperatures in the upper combustion chamber area and since the composition of the flue gases is also different for each type of furnace. For these reasons, the composition of the catalyst coating is always adapted to the respective application. Because Blue Fire GmbH has its own production facilities, the catalytic converters can be quickly and flexibly adapted to the customer's wishes and then manufactured. In complex cases, a 3D flow analysis can be carried out to determine on the computer how the catalyst must be arranged and designed in order to ensure the most complete and turbulent flow possible and thus maximum turnover of CO.
If the catalytic converters are fitted with a support system made of highly heat-resistant sheet steel, retrofitting can also be carried out in existing furnaces. The support system is precisely adapted to the dimensions of the combustion chamber of the furnace to be retrofitted and the bypass required by the EN standards is also already integrated into the support system.
In this way, fireplaces can be retrofitted that are no longer allowed to be operated.
After the retrofit kit has been installed in the fireplace, the responsible district chimney sweep must carry out a subsequent type test on site. For this purpose, the retrofitted combustion system is subjected to an emission measurement. Blue Fire GmbH expressly recommends speaking to the responsible district chimney sweep master before retrofitting, as he must assess whether the combustion system is still technically capable of continued operation before retrofitting.
At the world's leading trade fair ISH 2019 in Frankfurt/Main, Blue Fire GmbH will be using a cutaway model of the modern Corna Tec stove from Leda to demonstrate how Blue Fire catalytic converters are integrated into the combustion chamber of small combustion systems. In addition, the optimum operation of the Blue Fire catalytic converters is ensured by the electronic heating aid developed by Leda. This electronic device supports the user by means of a visual display and ensures that the Corna Tec is always operated with the correct parameters.
By using the Blue Fire catalytic converters in combination with Leda's electronic heating aid, it is now possible to make stoves available to the market with a small output in line with demand. Owners of passive or low-energy houses in particular are looking for such low-emission stoves, which produce only as much heat as is necessary for such modern houses.
If you want to safely undercut the emission limits of the future today, then please feel free to contact us or visit us at the ISH 2019 trade fair. You will find us in Hall 9.2 at Stand A0.2. We look forward to your visit and to exciting discussions with you.