A nonlinear dynamic model for natural circulation drum-boilers is presented. The model describes the complicated dynamics of the drum, downcomer, and riser components. It is derived from "rst principles, and is characterized by a few physical parameters. A strong e!ort has been made to strike a balance between "delity and simplicity. Results from validation of the model against unique plant dat...

The control effect of steam pressure is one of the most important factors influencing stability in chain type boiler. Aimed at the problem that the control of steam pressure is restricted by many factors, a kind of fuzzy neural network (FNN) is presented in this paper. The controller has the advantage of self-adapting, self-learning and tuning on-line. In simulation, this system exerts stably, ...

The objective of life extending control (LEC), also known as damage mitigating control, is to design a controller to achieve a good tradeoff between structural durability and dynamic performance in a system. In this paper, continuum fatigue damage theory for a boiler system is discussed. To reduce the accumulated damage, a variance constrained model predictive control (VCMPC) problem is develop...

This paper presents a methodology to simulate the combustion of fixed beds of biomass particles using computational fluid dynamics (CFD) techniques. The models presented were used in the simulation of a domestic pellet boiler working under operating conditions and the model predictions were compared with measurements of heat transfer, temperature and species concentration. The same procedure wa...

A laboratory study was carried out to determine the effect of bark boiler ash on AOX concentration in bleach plant effluent. The removal of A O X was found not to be significant at typical daily discharge rates of boiler ash. To remove significant amounts of AOX, extremely large quantities of ash were required. When incremental quantities of ash were added to the bleach plant effluent, an incre...

In this paper we model a hybrid system consisting of a continuous steam boiler and a discrete controller. Our model uses the Lynch-Vaandrager Timed Automata model to show formally that certain safety requirements can be guaranteed under the described assumptions and failure model. We prove incrementally that a simple controller model and a controller model tolerating sensor faults preserve the ...

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 app...