Modelling spontaneous ignition of wood, char and RDF in a lab-scale packed bed

Many municipal waste combustors use preheated primary air in the first zone to dry the waste. In most cases the preheat temperature does not exceed 140°C. In previous experiments it is found that at temperatures around 200°C, in some circumstances, self- or spontaneous ignition can be achieved. Using preheated air can be a powerful tool to...

Modelling piloted ignition of wood and plastics

To gain insight in the startup of an incinerator, this article deals with piloted ignition. A newly developed model is described to predict the piloted ignition times of wood, PMMA and PVC. The model is based on the lower flammability limit and the adiabatic flame temperature at this limit. The incoming radiative heat flux, sample thickness and...

Spontaneous ignition of wood, char and RDF in a lab scale packed bed

Many municipal waste combustors use preheated primary air in the first zone to dry the waste. In most cases the preheat temperature does not exceed 140 °C. In previous experiments it is found that at temperatures around 200 °C, in some circumstances, self- or spontaneous ignition can be achieved. Using preheated air can be a powerful tool to...

Experimental comparison of biomass chars with other catalysts for tar reduction

In this paper the potential of using biomass char as a catalyst for tar reduction is discussed. Biomass char is compared with other known catalysts used for tar conversion. Model tar compounds, phenol and naphthalene, were used to test char and other catalysts. Tests were carried out in a fixed bed tubular reactor at a temperature range of 700...

On-line determination of the calorific value of solid fuels

In thermal processes with highly inhomogeneous fuels it is desirable to know real time fuel characteristics. In the case of municipal solid waste combustion (MSWC) it was up till now not possible to determine the calorific value of the waste on-line with a high accuracy. In this paper, a new method is presented where the calorific value is...

The effect of air preheating on the combustion of solid fuels on a grate

Combustion of solid fuels on a grate is widely used. Mostly, the combustion behaviour is explained by the classical theory of Rogers. However, that theory cannot explain the combustion process when primary air preheating is applied. Solid fuel grate combustion is studied by experiments in a pot furnace. Experiments with and without primary air...

Advanced waste incineration concepts

On-line calorific value sensor and validation of dynamic models applied to municipal solid waste combustion

This paper deals with two aspects concerning the optimization of municipal solid waste combustion (MSWC) processes. First of all, an on-line calorific value sensor is discussed by means of which the calorific value of the waste can be estimated from actual process data. Experimental results on a MSWC process are discussed which show that the...

Computer simulation of waste combustion in a moving grate furnace as a tool for process optimization and operator trainings

A computer model has been developed to simulate the waste combustion process in a moving grate furnace. The computer model describes the main processes occurring both in the waste layer on the grate, and in the gas phase in the furnace. The boiler section and the flue gas cleaning equipment are also included in the model. The computer simulation...

A dynamic model of biomass gasification in a circulating fluidized bed as a tool for optimising designand operation

Biomass gasification, followed by a combined cycle seems to be an attractive option to generate electricity from sustainable sources. However using wood gas in engines is difficult due to tar, variations in calorific value of the gas and variations in volume flux. A dynamic model of an !BGCC installation helps to improve design and operation of...

Mathematical modeling of coal conversion processes with application to atmospheric fluidized bed combustion

The main goal of the present thesis is to develop mathematical models for coal conversion processes, to improve the understanding of the underlying physical processes and to support the experimental work in the fieId. Therefore, emphasis is given on developing analytical descriptions for variables involved with conversion of solid particlesin a...