Simulation And Study On Safety Of Hydro-power Under Low-load For Utility Boiler

At present, the over-temperature and tube burst of heaters has become the important factors that influence the safety and economy of utility boilers. It is estimated that 50% of all power-plant breakdowns are caused by tube failures of boiler tubes. In general, a lot of all tube failures in riser tubes of boilers are caused by overheating. Therefore, for the safe and economic operation of boilers, it is worth with studying ,analyzing and resolving all-sidely. This paper has set up the mathematical model of the hydraulics and calculated it. It has also studied the characteristics about the hydraulics of the utility boiler, the heat exchange between water and wall, and the wall temperature.Firstly, the thesis finished the thermodynamic calculation by the way of dividing the wall into several sections, and gave the function of the heat distribution. Then based on the analysis about the Nature circulation boiler and the researching object, the hydraulics mathematical model on circulating in one stair in parallel tubes has been set up and calculated by the way of analytic method. The paper has discussed in details the characteristics about the hydraulics of Natural circulation boiler and the real value of variables in pipe under such conditions as various loads and several kinds of factors affecting it, then checked out the safety. The results demonstrate that water circulation is safety when load is more than 50%. Water circulation is safety, but circulation velocity shows fluctuation when load is 40%. 30% load is not suitable to long-term run of water circulation. Water circulation is not safety when load is 20%.Finally, on the basis of calculation about heat exchange and analysis upon the ruptured tube in riser tube wall, the thesis has calculated the temperatures about interior water wall tube by utilizing the numerical calculated method and analyzed its safety. Water circulation is not safety when load is 20%.