Search results

The purpose of this paper is to develop a cyclone with an internal electric field to capture dust and fine carbon particles with less than 5 μm diameter.

The cyclone collection efficiency model described by Cooper and Alley was used to design a conventional cyclone, which was later modified by introduction of the solenoid around it to introduce an electric field. The cyclone design performance was later established using ferrosilicon powder with less than 5 μm diameter.

The cyclone was found to have a particle collection efficiency of around 25 per cent for ferrosilicon powder before the introduction of the solenoid; the introduction of the solenoid increased the particle collection efficiency to around 50 per cent and the charging of the solenoid further increased the collection efficiency to 85 per cent at 2 kV DC and 97 per cent at 3 kV DC. When the cyclone was placed back on the gasifier system and supplied with 2 kV DC, it collected up to 270 g of fine carbon particles within 150 min of operation.

The major drawback was that the highest particle collection efficiency for the cyclone could only be achieved at very high voltage (3 kV) but this could not be supplied when the cyclone was back in the gasifier system due to air ionization that results in the corona effect.

The collection of very fine particles (less than 5 μm diameter) in hot gas streams is always a challenge, particularly in biomass gasifier systems. This resulted in a high cost of gas purification or initial investments in downstream processes. The developed cyclone could cut down this expenditure since most of the particles will not go beyond the cyclone.

Electrostatics has been applied in the development of gas cleaning devices, however most of these devices tend to be too cumbersome. The developed cyclone is based on the conventional design, which is less complicated and cheap to manufacture.

The aim of this research is to build a low‐cost gas and temperature profiling system for data acquisition at a biomass gasifier.

A gas and temperature profiling system was developed from NDIR sensors, Pd/Ni sensor, a number of type K thermocouples and a data logger interfaced to a computer.

The results obtained using the system were in agreement with the results obtained using a gas chromatograph for gasses. The temperature recorded during the testing also followed the expected temperature of the gasifier used.

The lifetime of the developed system depends on the lifetime of the sensors used. NDIR sensors have a lifetime of three years working on a continuous basis and the Pd/Ni sensor has a lifetime of ten years. Replacement of the Pd/Ni sensor after ten years is not a problem as the payback period of biomass gasifier systems is around eight to ten years.

The major implication for this research was that low‐cost gas and temperature measuring systems could be developed. These could be useful particularly for PhD students and other researchers who need to get onsite data on gas and temperature profiles at a gasifier system for a period of three years.

Biomass gasifier technologies can be used to provide power in rural areas that are outside the national utility grid but endowed with biomass resources. The provision of electricity to these communities could solve social challenges such as exposure to smoke in open fire normally used by rural women for cooking. The developed data acquisition system is therefore necessary to conduct research on gasification.

The findings of this paper are of importance to researchers who need online data but do not have funding to purchase bulky and expensive equipment's for gas analysis at biomass gasifier systems.