TU Clausthal Institut für Energieverfahrenstechnik und Brennstofftechnik

The swirl combustion chamber (TBK) offers the IEVB a variable platform with which a number of questions concerning combustion with a thermal output of up to 1 MW can be investigated. In the past, this plant system was already implemented in a large number of research projects and industrial contracts in the area of gaseous, liquid and solid fuel combustion.

The 3.30 m long combustion chamber (5) is vertically oriented (Figure 3.3.2). Secondary air inlets at various heights as well as opportunities for exhaust gas recirculation are integrated into the combustion chamber. Certain measures can be implemented in the ensuing, nearly 10m long, horizontal tube reactor, for example to reduce polutants or to improve product quality (e.g. grain size, see Section 2.4). It is followed by a gas heat exchanger and a gas cleaning apparatus (fabric filters and activated carbon filters).

In general, prior to initial testing, the combustion chamber is fired with natural gas to heat the combustion chamber to the desired operating temperature. If a determined temperature (refractory lined walls; quasi-stationary state) is reached, then the natural gas is replaced over time by the pulverized or liquid fuel until the combustion chamber is exclusively operated with these dust or liquid fuels. During the entire trial period, the composition of the exhaust gas is analyzed for the following components: O2, CO2, CO, NOx, SO2. In order to assess the burnout behaviors of different coals, samples of the solid matter in the exhaust gas are taken. These samples undergo a proximate analysis to determine of Cfix, volatile compounds, water, and ash contents. Sampling can take place at a distances of 1 m from one another in the pipe reactor, whereby the particles collected in the exhaust gas have different residence times.

There exists the possibility of conducting a variety of experiments using the MILD-experimental furnace. The IEVB has a wide range of measuring instruments available for determining combustion and heat transfer parameters.

Ressurized gas (air or nitrogen) charges are blown into a heated muffle furnace over a suitable apparatus with a defined amount of pulverized fuel of a specific quality. The ignition of the pulveniged fuel sample depends on its ignitability as well as the temperature and composition of the gases in the chamber. The time that elapses until ignition occurs (the so called ignition time) is measured and then evaluated. The following parameters can be varied during implementation of the experiments: particle size of the investigated dust, reaction gas composition (air, O 2 , CO 2 , N x ), and reaction temperature (400°C - 1100°C).