One day in the future, perhaps the curb will no longer be seen on the roadside barbecue stalls. Barbecue grills are replaced by a closed oven. Boilers will no longer cause pollution to the atmosphere due to exhaust emissions and endanger human life and health. All this, thanks to a new type of combustion - the application of catalytic combustion. Its magic lies in the complete combustion and oxidation of ultra-low-concentration fuels. The conversion efficiency is close to 100%. In the 2nd issue of 2013 Frontier Science published the article “Characteristics and Application of Natural Gas Low-Carbon Catalytic Combustion†by Zhang Shihong, Valerie Dupont, and Alan Williams, we introduced the characteristics, theory, and applications of natural gas catalytic combustion.
Theoretical Study on Catalytic Combustion of Natural Gas
The study of catalytic combustion can be traced back to the early 19th century. However, it was not until the 1970s that people realized that catalytic combustion could bring about huge economic and environmental benefits and that extensive research and application development began. The further development and research of catalysts have opened up new avenues for the study of catalytic combustion. Until today, the main research of catalytic combustion focused on catalysts and preparation processes, as well as catalytic devices and control technologies.
In the theoretical study of methane/oxygen/nitrogen-mixed gas combustion, a stagnation point flow reactor experimental device was used. In the middle of the inner aluminum frame is a thin platinum foil of catalyst immobilized inside the ceramic frame. During combustion, platinum and the reactants participate in the reaction and form a thermal cycle. After the reaction, the test gas is released as exhaust gas. Platinum reverts to its original state and continues to participate in the next such cycle. Through repeated tests and numerical simulations, it was found that due to the presence of catalysts, combustible gases can be catalytically combusted and fully oxidized at low concentrations, without the formation of CO, nitrogen oxides, and incompletely combusted hydrocarbons. Outside the conventional gas phase flammability limit, combustion is therefore more stable. The heterogeneous reaction at the surface of the catalyst suppresses the extent of the gas phase oxidation reaction and increases the surface temperature of the single-phase ignition.
Development and Application of Natural Gas Catalytic Combustion
Zhang Shihong's research team focused on the catalytic combustion mechanism and applied research and conducted in-depth research on industrial products and industrialization of such issues as near-zero pollutant emissions, catalyst poisoning characteristics, and how to adjust the lean natural gas/air mixture ratio. Developed natural gas catalytic combustion V-type condensing boilers, natural gas catalytic combustion ovens, and natural gas catalytic combustion furnaces.
In the study of natural gas catalytic combustion V-type condensing boilers, after the combustion furnace adopts the catalytic combustion method, many disadvantages of the flame combustion method can be avoided. Zhang Shihong’s research team measured the smoke of ordinary fast-fired gas water heaters and domestic gas stoves. It was found that even though the gas emitted by gas water heaters and gas stoves is significantly diluted by air, the pollutant emission concentration is still much higher than catalytic combustion. Therefore, it is evident that the catalytic burn-poor CH4 heterogeneous combustion method can produce fuel savings and reduce environmental pollution. The test data shows that the thermal efficiency of catalytic combustion V-type condensing boilers is significantly higher than that of ordinary gas-fired boilers. Using the analyzer to measure the composition and content of the flue gas in both the catalytic combustion and the gas-phase combustion, it was found that the current catalytic combustion has almost reached the degree of complete combustion and near-zero pollutant emissions.
Another achievement of the research team of Zhang Shihong is that catalytic combustion ovens are closer to our lives. Compared with ordinary ovens, the catalytic combustion oven not only saves electricity, but because the area of ​​the catalytic burner radiates is larger than that of a conventional electric oven, the food in the catalytic combustion oven can better receive high-temperature radiation. The energy passed. By comparing the common oven and the catalytic combustion oven at the same time for two different portions of beef, the beef roasted in the catalytic grill is fresh, refreshing, soft and juicy, easy to chew, and smells more attractive.
In the research of natural gas catalytic combustion furnace, Zhang Shihong's research team has improved the kiln equipment to bring the temperature around the baking pan to 850 degrees Celsius. The characteristics of the baked pottery are obvious, the shape is regular, the surface is smooth, and there are no raised potholes. phenomenon. Compared with ordinary pottery kilns burned out of the pottery, the former because of heat evenly, its quality is more exquisite, the color is elegant and delicate, more close to the natural color, can be used as a container for water.
The application of natural gas catalytic combustion needs to be promoted
Professor Zhang Shihong believes that the catalytic combustion of natural gas achieves a true low-carbon denitrification emission, and the flue gas reaches high temperatures to achieve sterility and the same composition as fresh air. Natural gas catalytic combustion in the heating, food industry, chemical industry and kiln, part of the metallurgical industry and agriculture due to its combustion stability, complete combustion and near-zero pollution can play an irreplaceable role in ordinary combustion.
For example, the results of natural gas catalytic combustion V-type condensing boilers provide new ideas and approaches for air pollution control in Beijing. The achievements of research on natural gas catalytic combustion furnaces are of great significance to the future landscape design, gardening and gardening techniques, art production and ancient building materials production.
With the continuous improvement of people's awareness of environmental protection, this non-polluting combustion method will have wider application and promotion space. Reporter Cao Bingli
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