A Small Condensing Gas Boiler for Emitting Low NOx by Exhaust Gas Recirculation

摘要

The present invention relates to a structure and a combustion method of a condensation type small gas boiler applying the theory of reducing nitrogen oxides (NOx) to the exhaust gas recirculation combustion method. As a matter of reduction and efficiency improvement, it minimizes the emission of NOx, an environmental pollutant generated in the combustion process while maintaining a stable combustion state of the boiler, and actively recovers the heat of moisture contained in the combustion flue gas. It relates to the structure of domestic and small gas boilers to maximize the thermal efficiency of the.;For this purpose, the exhaust gas is sucked and mixed by the supply power of the combustion air by using a non-powered ejector to easily apply the recirculation combustion method of the exhaust gas. Complementing the disadvantages of poor internal boiler layout and poor boiler construction due to the use of two separate heat exchangers connected in series to expand heat exchange heat transfer surfaces and recover condensation heat in order to improve efficiency in existing domestic boilers. It is a heat exchanger that has a heat transfer area that can recover sufficient condensation heat to improve heat transfer performance.The plate fin-shaped bulkhead is installed in the middle of the fin while using the existing plate fin shape. Flow structure of combustion gas focusing on separating hot surface 2 have the structure by way of a path simplify the structure compared to the conventional condensing type boiler, reduce the pollutant emissions of the exhaust gas, and has a boiler structure in which increase the thermal efficiency.;Such a boiler structure can prevent the efficiency deterioration due to the high air ratio combustion to reduce the nitrogen oxides compared to the existing small boilers including the home, and the change in the location of the condensate generation according to the combustion amount of the boiler, that is, the load, and the combustion It can alleviate the damage caused by the condensation in the chimney due to the rapid temperature decrease of gas, prevent the overheating of the bulkhead due to heat pinning of the bulkhead, and maintain stability by applying the exhaust gas recirculation method to the premixed combustion method. It has many advantages, such as the reduction of the boiler size according to the application of the firebox.;The method of recirculating some of the exhaust gas and pre-mixing it together with air and fuel gas to supply it to the combustor for combustion is delayed the combustion reaction as compared to the case of the boiler that does not recycle, thereby lowering the temperature of the flame primarily to fundamentally generate heat NOx. In general, it is relatively easy to maintain safety for mixers that are outside the flame or flammable limit, such as diffusion flames or semi-bunsen flames.However, in premixed combustion, if the exhaust gas temperature is high, it can ignite itself and combust inside the combustor. Therefore, this flue gas recirculation method can be applied to premixed combustion only when the flue gas temperature is low, such as condensing boilers, to suppress generation during combustion, and at the same time, by arranging a finned water pipe in the flame to lower the flame temperature, heat NOx is generated. Minimize. At the same time, the finned water pipe heat transfer surface of the boiler is expanded and disposed in a two-pass manner to recover the latent heat of condensation of the exhaust gas, thereby maximizing thermal efficiency and easily discharging condensate.