Projeto de um economizador pós bomba d`água para caldeiras de pequeno e médio porte

Abstract

The search for efficient consumption of the energy sources has become increasingly a global concern, since these are even more scarce. The thermal energy is one of these sources and it is widely used in steam generating units through the combustion process of different fuels. The largest share of losses in boilers is the not taking advantage of the thermal energy still present in the flue gases. Economizers are basically composed of tubular heat transfer surfaces with the aim of recovering share of this energy from the gases after their passage through the final stages of the boiler. However, due to the high capital costs, its use is generally employed in large steam generating units. In this work was developed an economizer for small and medium sized boilers, it having as a differential its installation after the water pump, eliminating temperature restrictions of incoming water from the equipment. For this purpose, it was used as a base a boiler with a steam production capacity of 1500 kg / h, installed in a tire harvester.Thereafter, the type of suitable heat exchanger was determined and the choice of pipe material was as set forth by Michael F. Ashby. For the thermal sizing was used the methodology proposed by Incropera et al. (2008) and Cengel (2009) which aimed to determine the thermal exchange area of the equipment. The results pointed out the unviability of this project due to the low thermal gain of the feed water, only 19,5 ºC, in comparison to the high length of the heat exchanger tubes, 32.33 meters, in a configuration of 50 vertical tubes.It is proposed for future Works, unviability studies of the implementation of the equipment in boilers that are still within the specifications of this work, however of greater capacity and the use of finned tubes in order to increase the convective coefficient on the side of the gas.