Hydraulic Calculation Of High-Capacity Gas Corner-Tube Steam Boiler

With individual environmental awareness increasing, the corner-tube boiler’s application is enlarged as well, especially corner-tube steam boiler.A reliable corner-tube boiler’s water circulation, high structural strength, less steel consumption, convenient assembly, these advantages make it widely be researched and applied. But corner-tube steam boiler’s hydraulic circulation is more complicated than general boiler, the boiler water circulation system of nested loop is mutually associated, is not in simple parallel relationship. As a result, the differential pressure method cannot be used to solve the hydraulic characteristic calculation of the corner-tube steam boiler. The main purpose of this article is to research corner-tube steam boiler pipeline network, propose the directed graph of hydraulic circulation system, establish mathematical model for directed graph using the law of conservation of mass and the law of conservation of energy, and calculate the hydraulic characteristic of boiler through a program.A 130 t/h corner-tube steam boiler as the research object, to ensure the water circulation running well, this article is going to do researches as follow.1.As hydraulic system of different types of boiler is similar, therefore, hydraulic system can be seen as a network system with sort of pipe supplying hot water. Using the knowledge of graph theory, the drum, header, and so on as a "node", each tube as a "segment", to make the boiler pipe network into "digraph model", and find out the directed graph characteristic matrix.2.Corner-tube boiler flue gas flow model is established by using boiler calculation software, and finish the thermodynamic calculation, find out the boiler’s heating surface absorption heat and other thermal parameters. This article gives an improved boiler hydraulic calculation method based on pipeline network analysis and boiler hydraulic parameters. The method is that based on boiler system directed graph and the boiler’s heating surface absorption heat, the node equation and loop equation is established by using the law of conservation of mass and the law of conservation of energy.3.Mathematical model of the boiler system consists of node equation and loopequation, this is a set of nonlinear equations, which are only solved by numerical calculation.Thenit is going to solve the equations by MATLAB software programming and find out the hydraulic characteristics of boiler, such as rate of circulation, evaporated quantity of water, void fraction, pressure drop and so on. Then, checking circulate stagnation to make sure whether the boiler runs well.The results show that when heat load is over 50%, the boiler water circulation can run safely and reliably. Heat load is 40% of limit condition of boiler, and the water circulation has become unreliable. Running under 30% heat load, rate of circulation and the circulate stagnation coefficient are below the safe value, water circulation cannot provide enough water to cool down the heating pipes.