摘要：随着改革开放的不断深化和全球环保意识的提高，近年来燃气锅炉在国内得到了广泛的使用，具有很好的发展前景。

  本次设计锅炉额定热功率：0.7MW，允许工作压力：0.7MW，额定进水温度70℃，出口温度95℃的卧式内燃燃气热水锅炉。主要内容包括燃料的燃烧计算，确定空气量和烟气量，编制烟气焓温表；热力计算，确定锅炉各部件尺寸及烟气在各个位置的温度；烟气阻力计算，确定引风机的型号；强度计算，确定各受压元件壁厚以及校核。本次设计重难点在烟管的设计，每个对流换热面的设计传热量与烟气侧放热量的误差必须在误差允许范围之内，同时还必须考虑到锅炉的尺寸设计烟管根数。第一回程管采用螺纹管，使用螺纹管主要目的不是为了增加受热面积，而是在烟气流经这些凸起时，破坏了烟管内壁的层流边界层，增加了紊流并使烟气主流产生不不同程度的旋转，一般可使换热系数增大20%～25%。

关键词：燃气；热水锅炉；热力计算；烟风 阻力计算；强度计算

Abstract: With the development of reform and openning up and the improvement of global awareness of environmental protection, gas boiler have enjoyed both extensive use and good development prospects in China recently. 

Rated thermal power in the project:0.7MW, safe working pressure: 0.7MW,Rated inlet temperature: 70℃,outlet temperature:  95℃ horizontal internal combustion gas-fired hot water boiler. The project mainly includes: calculating fuel burn, determining air amount and exhaust gas volume, establishing flue gas enthalpy temprature chart; calculating heat, deciding the size of spare parts in boiler and the temprature of flue gas in different places, calculting flue gas resistance, deciding the kind of draft fan; calculating strength, deciding and checking thickness of each pressure component. The most difficult and important part of this project lies in the design of fire tube. What is equally difficult and important is that the error between convective heat trasnfer surface and flue gas side heat should be kept within the permissible range. In the meanwhile, the size of boiler and amount of fire tubes should also be taken into consideration. Threaded pipe used in the first return pipe is not for expanding heating surface area but for the reason that flowing across those bumps, flue gas destroys the laminar flow boundary layer inside the tube which causes eddies and makes the mainstream of flue gas swirl at different rates, usually waxing heat transfer coefficient by 20% to 25%.

Key words:  fuel gas; hot water boiler; calculation of heat; calculation of flue gas resistance; calculation of strength