A Simulation Of Sintering Waste Heat Recovery Based On Organic Rankine Cycle

Iron and steel industry in our country is one of the high energy consumption fields,Sintering circuit is next only the puddling circuit which has very abundant waste heat resource most of the existing technologies are used for recovering the medium temperature gas waste heat resources,the low temperature gas waste heat resources are basically unused.one way we can reduce the production cost is to recover the rich waste heat resources.With the features of high thermal efficiency,simple equipment and environmental friendly,Organic Rankine Cycle is widely used in low temperature waste heat power generation.In this paper,the low temperature waste heat recovery of sintering based on ORC is discussed.First of all,the principle of ORC and the working fluid selection are introduced,based on the working fluid selection principle,six kinds of working fluids are selected as candidate working fluids.Then take the 435m2 sintering machine for an example,one ORC system is proposed which recovers the waste heat of outlet HRSG and the N0.4 section of the annular cooler,and one ORC system model is built by the Aspen Plus,then the thermal characters of the ORC system is investigated by analyzing the influence of key parameters,including evaporation temperature,condensation temperature,superheat and supercooling.The results indicate that the ORC most suitable working fluid is R236 ea which tends to maximum net work when the temperature and flow rate of gas are given.And it is confirmed that the optimal evaporation temperature is 87 when the pinch point is 5? ?.Meanwhile,exergy loss model of each parts are established in ORC system.The results show that the largest exergy loss exists in evaporator side and the optimization of cycle should be focused on the improvement of pre-heater and evaporator.Then,in order to improve the thermal efficiency and reduce the exergy loss of the ORC,the recuperative ORC system and the regenerative ORC system are built.Calculation models of two systems are established by Aspen Plus and the influence of the evaporation temperature,superheat and extraction pressure ratio of the system are analyzed to get the optimal parameter.The result shows that compared to the standard cycle,the thermal efficiency efficiency of both two complex cycles are raised,and the net work of the regenerative decreases while the recuperative one is constant.Finally,with the analysis before,the optimal parameter is presented.Then the economic model of heat exchangers,expander and pump are presented,and the heat transfer coefficients correlations of pre-heater,evaporator and condenser are proposed to calculate the heat transfer coefficients and the heat transfer area.The costs of these Components are estimated by these economic model and heat transfer coefficients correlations mentioned before.The research indicates that the total cost of pre-heater and evaporator accounts for the largest proportion,follows by expander.Meanwhile,the NPV and DPP are different with the different pinch point,and the minimum DPP is 5.68 years.