Sense of lambda probe in the gasifications boilers.
As every modern car is equipped with a lambda probe, as well as every modern gasification boiler should be equipped with lambda probe. Recognizes the importance of lambda probe in the boilers, so our boilers PYROGAS have already lambda probe as standard.
European technical standards for all devices, that by its operation produces harmful emissions / in particular CO, CO2, NOx, OGC, dust, etc./ establish according to the ever-worsening environment just by the influence of miss of these emissions into the atmosphere, very strict limits.
For not overload these limits during the use / see. the table below / such devices are now equipped with trickyl and structurally sophisticated electronic control technology.
Just one of the necessary conditions, that the gasification boiler in each heating mode discharges through the exhaust chimney-pipe emissions into the air in standard allowable limit and while achieving a high combustion efficiency, it is essential to be equipped with a lambda probe.
The lambda sensor is a ceramic, an electrochemical oxygen analyzer, mounted in the mouth of the flue of the boiler associated with the electronic controller. The role of the oxygen sensor is measuring the amount of oxygen in the pipeline and pass on in the form of an electrical signal that value to the electronic controller , which this value during the operation evaluate and then manage the entire combustion process so, that to the burning fuel - in this case to burning wood or wood briquettes was supplied continuously optimal amount of combustion air, which is in the boiler divided into primary and secondary atmospheric oxygen and the optimum ratio of these two components with the possible highest efficiency and uniformity of combustion without power fluctuations. Primary air is supplied into the boiler to the primary combustion firebeton nozzle by a separate channel and secondary air is supplied directly to the combustion chamber with another separate channel and secure so complete burning of the burning gases. The primary air together with a fan is responsible mainly on the performance of the boiler and secondary air is important for low-emission combustion. Each channel has mounted inside generally a rotary flaps, which are automatic and independent operated by servomotors currently under evaluation of the amount of oxygen in the exhaust gases.
The entire process of air supply, combustion process and exhaust gas flow through the boiler body to the flue, with quality and under all operating conditions ie. after fully loading the boiler with the fuel, a progressive consumption during combustion, after-burning fuel of varying quality and type of wood / but always max. 20% humidity /, different chimney draft and others can ensure only boiler equipped with a lambda probe. For these reasons, during the heating process in the boiler, is constantly changing the needs and ratio of delivery of primary and secondary air to the combustion process. In the boilers with fixed, respectively by manually adjusting the amount of air intake and fan speed it is not reliable possible to achieve a long-term very low emissions and high efficiency equal to the lowest limit in European Standard EN 303.5. In order for these ever-changing effects on the combustion process have been eliminated, it is necessary to run the boiler with an electronically controlled regulator, which is based on continuous assessment of the amount of oxygen in the exhaust gas with sophisticated algorithms and automatically controls the servo motors and fan speed so that combustion was the most perfect. Such burning by wood burning, respectively wood briquettes, responds to 5,3% of residual oxygen measured in the exhaust gas oxygen sensor, which is a lambda value λ = 1,35.
Combustion is a chemical process occurring in the combustion chamber from fireproof firebeton at high temperatures up to 1200ºC. The hot exhaust gases from the combustion chamber crosses a hot water circuit of the boiler body, which are the water surface and water lamellas or tube plate, intto the chimney. The rate of flow of exhaust gases, water area size, robustness and shape of the combustion firebeton chamber and time until the flue gas comes to the mouth of the flue of the boiler, are also important for the efficiency of the boiler.
The well-constructed modern boilers with lambda probe can achieve emission levels even lower than that stated in the Class 5 in EN 303.5, / see table below / with an efficiency 88-93%.
Table of the emission limit values for the wood and wood briquettes in mg/m³ by 10% O2:
boiler class CO OGC dust
3 5000 150 150
4 1200 50 75
5 700 30 60