Performance Analyses Of A Novel Heat Transfer Surface In The Heat Recovery Boiler

The most common way of heat recovery is exchange heat by heating surface.Confronted with low-quality heat source,such as high ash contents,discontinuity and instability in typical waste heat recovery fields,innovations are required in the arrangement of typical heat transfer surface.In this paper a novel aligned cross-flow heat transfer surface is put forward.Numerical simulation and experimental investigations are used to obtain heat transfer performance,flow performance,and ash deposition characteristics in the new structure;moreover obtain the reliable soot blowing manner.The main work includes:1.An experimental platform of once-through heat recovery steam generator(HRSG)is installed,in which the new structure is used in the specified heating surface.Experiments are performed to obtain the working conditions,heat transfer performance,and dynamic responses.The novel aligned cross-flow heating surface can meet basic requirements of heat recovery boilers,and suits for recovery utilization of medium and low temperature waste heat.2.The geometric model of the novel aligned cross-flow heating surface is established in three dimensions.Single-phase gas flow are simulated and studied with ANSYS Fluent software.Experimental data validate the numerical simulation method.The characteristics of streamline,velocity field,temperature field and pressure field are obtained.The variations of surface heat transfer coefficient and flow resistance in the shell side with gas velocity are investigated,and the fitted formulas are given.PEC index and field synergy theory are used to evaluate the comprehensive performance.The results of the novel aligned cross-flow heating surface are compared with that of the common tubes aligned and staggered arrangement.3.Particle transport mechanisms and deposition model are built to discuss the gas-solid two-phase flow in the novel aligned cross-flow heating surface.The Discrete Phase Model(DPM)is used to trace particles in the Lagrangian frame,meanwhile,the user defined function is compiled for boundary condition of deposition walls.The distribution law of particle deposition is obtained.The variations of particle deposition ratio with inlet gas velocity and particle size are investigated.The results of the novel aligned cross-flow heating surface are compared with that of the common tubes aligned and staggered arrangement.Industrial shedding technique is investigated.In the way of the permutation and combination of soot blowing inlets,the optimal design of blowing is determined.4.By summarizing the advantages and disadvantages of the novel aligned cross-flow heating surface,seek the way of the improvement and the performance promotion.Influence of tube and baffle structures on the heat transfer and flow performances are analyzed,and the optimal structure parameters are given,for reference to optimization design of the novel aligned cross-flow heating surface.