How to choose the suitable kiln according to local conditions?
At present, the main kilns for sintering bricks and tiles in China are tunnel kilns and rotary kilns (mobile tunnel kilns). Tunnel kilns have various types and they could be classified based on different characteristics: it could be classified as big cross sections tunnel kilns, medium cross sections tunnel kilns and small cross sections tunnel kilns ( such as 2.5m, 3.3m, 3.6m, 4.6m, 4.8m, 6.9m, 9.2m, 10.3m) by the sizes of the tunnel kiln’s cross section; it could be classified as arch ceiling tunnel kiln, micro arc ceiling tunnel kiln and flat ceiling tunnel kiln based on the shape of the tunnel kiln ceiling; it could be classified as long tunnel kiln and short tunnel kiln based on the capacity of the kilns; and it could also be classified as ‘once stack and burning tunnel kiln’ and ‘twice stack and burning tunnel kiln’. The choice of kiln type determines the investment of the brick factory.
The selection of reasonable kiln type is mainly from two aspects:
1) One aspect is the investment and technology level location. There are many kinds of characteristics of current kiln types to meet different customers ‘different requirements. For example, by the control level of kiln production line, there are semi-automatic kiln and semi manual kiln and normal control kiln. When use the kiln, the service life of the kiln is different due to the application of different heat-resistant materials: some factories use high grade heat-resistant materials for the kiln, while other factories may use medium grade or even ordinary heat-resistant materials. In the selection of the supporting equipment of the kiln, some factories choose ‘one for use and one for standby’ and some factories choose one single machine. In the appearance of the kiln, some factories choose to decorate the kilns with decorative heat insulation plates, while some factories do not. In terms of metal structure, some factories use special shaped materials from modeling product of fixed specification, while some factories simply use artificial material structure. There are also many differences in terms of kiln’s multi-function: the kilns in south and that in north, the changes of climates, the use of energy and venting, and etc.
2) Another aspect is to locate from the applicability of raw materials. Now there are many kinds of raw materials for fired brick, such as shale, fly ash, coal gangue, clay, river silt, mountain slag soil, mineral tailings, waste residue and so on. Then locate the kilns from sintering temperature, which determines the size of the material investment. The material investment of high sintering temperature kiln is totally different with that of low sintering temperature kiln. The sintering temperature comes from the choice of fuel. When selecting the fuels, it is necessary to analyze the width of the burning curve is narrow or wide, then determine its temperature.
When selecting the kiln types, we must consider the relationships between above aspects. Reasonable choice of kiln type is crucial for brick factory investors.