Numerical and Experimental Study on Nonlinear Phenomena and Thermal Deviation Control in a 1000 MW Tower-Type Boiler

Abstract

Numerical and experimental studies were conducted to study the nonlinear phenomena of a 1000 MW ultra-supercritical four-corner tangential pulverized coal boiler. In this paper, (1) a 3D model of a furnace with a symmetrical structure was established to analyze the asymmetric flow phenomenon and multi-solution phenomenon of flow for multiple timepoints under the same boundary conditions. (2) The visual experiment verified that the flow in the furnace also behaved asymmetrically. (3) On the basis of correctly predicting the nonlinear law, the “diagonal start up” method and the “sequential start up” method are proposed. (4) An uneven coefficient of velocity distribution M, deviation coefficient of flue gas mass flow rate Eq and gas temperature deviation coefficient ET are proposed to quantitatively analyze the degree to which the actual tangent circle deviates from the ideal tangent circle. The tangent circle under the “sequential start up” method is the closest to the ideal, which can reduce the thermal deviation of the furnace outlet from 67 K under the “simultaneous start up” method to 41 K. In this paper, the initial steady-state flow field in the furnace is established by using the initial value sensitivity of the nonlinear system through different burner-opening methods, so as to reduce the thermal deviation at the furnace outlet and achieve the purpose of accurate control.

Keywords

• four-corner tangential boiler
• non-linear dynamic system
• initial value sensitivity
• precise control
• thermal deviation