The Simulation And Research On Static Pressure Distribution And Flow Deviation Of The Header

Tube bursting of superheater or reheater often happens in large capacity power plants,which severely threatens safety of boiler. The main factors for superheater and reheater's leakage include heat flux deviation on the gas side,flow deviation on the steam side and heating surface's structure deviation.The flow condition of steam in manifold systems will directly affect the operation security of superheater and reheater. Firstly this dissertation introduces the existing calculating methods and points out the unsatisfactory expressions. And then this dissertation completely analyzes the discrete model,which coincides with actual structure feature and the changing principle of the characteristic parameters of flow.This dissertation establishes hydrodynamic mathematics models for both distribution-headers and collection-headers and discusses static pressure distribution and flow deviation in the unheated condition and heated condition. In unheated condition,this dissertation studies the structure factors which have different effect on distribution-headers and collection-headers and calculates the static pressure distribution and the flow imbalance between panels. Meanwhile this dissertation simulates the Z-header and U-header and the manifolds whose inlet and outlet pipes use T-junction. Because of the inherent limitation of pulverized coal tangentially fired boiler,there is heat flux deviation in the flue. And there is also flow deviation in manifold systems. If they don't coincide,it would result in superheater and reheater's leakage. So in the heated condition,this dissertation discusses static pressure distribution and flow distribution characteristics in some common heat flux distributions. Meanwhile the flow distribution characteristics in different load are also studied.