Study On Effective Utilization Of Natural Gas And Heat And Mass Transfer

With the optimization of energy structure, the construction of energy save-type economy in China, and the implement of"medium and long period plan for energy save", effective utilization of natural gas is becoming a hotspot in the field of heat science and energy and environment engineering.In this paper, the influence of the specialty of different anticorrosion surfaces on the flue gas forced convection heat transfer with condensation and its rule were mainly studied by means of theoretical and experimental methods, in order to devising condensing natural gas-fired equipment; under the help of Beijing natural science found.Meanwhile, the feasibility that the flue gas condensing heat exchangers were applied in the heating field was studied, and their application projects were discussed..Based on theoretical analysis and numerical evaluation ,and the comparison with experimental values, the conclusion that Nu and super-cool degree increases as the contact angle decreases under the film condensation was obtained .Therefore , the rule of the influence of the specialty of different anticorrosion surfaces on the flue gas forced convection heat transfer with condensation was obtained.Contact angles of Cu and three different anticorrosion surfaces were measured by the Pheonix 300 contact angle analysis device; it shows that the heat transfer capability of condensing heat exchanger with nickel-phosphorus amorphous composite eletroless surface is the best ,the one with nickel-phosphorus amorphous eletroless surface is the second, the one with nickel eletroless surface is worse .It is consistent with the conclusion obtained from the heat transfer experiment of condensing heat exchangers.The heat transfer performance of condensing heat exchangers with three different anticorrosion surfaces were studied by means of experimental method. It shows that the heat transfer capability of condensing heat exchanger with nickel-phosphorus amorphous composite eletroless surface and organic compound surface is the best, because the film condensation drives to dropwise condensation in the condensing heat exchanger, and the connection between the anticorrosion surface and the backing is good; the one with nickel-phosphorus amorphous composite eletroless surface and the one with organic compound surface is equivalent.Meanwhile, the experimental correlations of condensing heat exchangers with different anticorrosion surfaces were set up, which could present a reasonable guide for designing similar heat exchangers and predicting their performance.The study on the feasibility that condensing heat exchangers were installed in the natural gas-fired heating boiler rooms shows that the heat efficiency of boilers can be improved 9%～13%, the first cost is about 20,000yuan /t, saving fuel cost is about 17～20yuan /h per ton, the recovery period is about 88～120days, when the temperature of flue gas decreases from below 200℃to 50℃. If condensing heat exchangers are only applied in the reconstruction projects of natural gas-fired boiler rooms in beijing , the natural gas can be saved 76.80～116.48million m~3/a, the fuel cost can be saved 150～230million yuan/a, and the NOx can be decreased. 384～760t/a。Application projects that condensing heat exchangers were applied in the natural gas heating system were discussed, and the feature of reconstruction projects of different natural gas-fired boiler rooms was analyzed. Therefore, the best reconstruction project was obtained when flue gas condensing heat exchangers were installed in natural gas-fired boiler rooms under different conditionsThe above result presents a guide for studying the rule of heat and mass transfer in the condensing heat-exchange equipment and similar multi-component heat and mass transfer, and designing natural gas condensing heat-exchange equipment.