Boiler Drum-Level Modeling

Abstract

In this paper, a mathematical model is developed to describe the dynamics of the drum-level of a natural circulation boiler. A boiler-drum is divided into two parts; the upper part contains saturated steam while the lower part contains a steam/water mixture. The ratio of the steam in that mixture is defined in this work as the steam volumetric ratio. On the other hand, balance equations are applied to the drum. The resulting equations are used to model the drum-level. The importance of the resulting model comes from the direct modeling of drum level which is usually computed off-line with the aid of empirical formulas and assumptions. Safe operation of boilers requires perfect level controller which cannot be designed without proper modeling. Simulation of the water level dynamics for step changes in heat rate and steam demand are compared with those in the literature. The results show that the drum level can be obtained from the basic balance equations.

Dynamic Modeling and Simulation of a Subcritical Coal-Fired Power Plant under Load-Following Conditions

“…The other variables of interest here include the drum pressure ( P ) and drum water level ( l dr ). The original modeling work including detailed descriptions, parameters, and further simplifications of these equations into a more compact system of equations is available in the literature. − …”

Dynamic modeling of a water tube boiler

“…All of these models use a steady‐state momentum equation for downcomer flow analysis. Tawfeic 9 presents a generalized approach for boiler drum level modeling by introducing pressure, water volume, dryness fraction, water level, downcomer flow, and steam volumetric fraction as variables. The model uses a transient momentum conservation equation for downcomer flow analysis.…”

An Experimental Investigation of The Dynamic Effects in Upper Drum Boiler Under Steam Mass Flow Rate Variation

“…The furnace of a boiler can convert the chemical energy in the fuel to heat, and it is the function of the boiler to transfer this heat to the contained water in the most efficient technique. This heat is transferred by radiation, conduction, and convection to the water in the boiler [1]. The relative percentage of each depends on the type of boiler, the heat transfer surface built for, and the type of fuel.…”