Improving gin stand performance to benefit Australian cotton

Improving gin stand performance to benefit Australian cotton

This investigation was into the processing of long, fine Australian cotton in high-mass throughput saw gins. The research was conducted at the Auscott Narrabri gin in New South Wales, Australia using Australian cotton with a UHML of 30.9 mm and 31.8 mm, with a micronaire value of 3.85. Mass production rates trials ranged between 3200 and 3800 kg/h of lint.

In particular, the feed and discharge of seed was investigated, and the results demonstrate that the gin stand motor load frequently fluctuates due to the varying mass input of seed cotton. Furthermore, the distribution of seed cotton presented to the gin stand is laterally non-uniform. It is thought that a non-uniform vertical feed results in elevated nep and seed-coat nep due to the changing seed-roll density. The source of the uneven lateral distribution of seed cotton to the gin stand lies within the design of distributor conveyor, which feeds seed cotton to the gin stand. Because of the high speed required to transport seed cotton in the conveyor distributor, the drop zone of seed cotton to each feed hopper is overshot. The trailing edge of the hopper is further seed cotton deficient. The auger blade together with the auger housing create a nip point allowing for the seed cotton to be pulled out of the feed hopper. Methods to overcome the problem were trialled,, including redirecting the seed cotton on the gin stand apron, modifying the conveyor distributor, and increasing the seed cotton mass in the affected areas to improve the uniformity of the seed roll density.

The uneven input of seed cotton creates an uneven output of fuzzy seed. The region of the gin stand most affected was the corresponding delivery side. This output region expelled up to four times more fuzzy seed than other expulsion areas of the gin stand. The uneven fuzzy seed expulsion is attributed to the seed roll density, as the roll box is unevenly loaded with incoming seed cotton. Uneven loading of seed cotton creates areas within the roll box that experience a reduction in density, and this creates a movement of fuzzy seed from high-density areas to the neighbouring lower-density areas. Therefore, high levels of fuzzy seed expulsion occur in areas of lesser density. The output distribution curve of fuzzy seed equates approximately to the inverse curve of the seed cotton input.

Elongation of the leading and trailing edge angle on the hopper of the gin stand was not finalised because of time constraints. This method is believed to enable the elimination of the uneven seed roll. The elongation length may be required up to 60 cm. Overcoming the uneven vertical flow can be achieved through electrical settings of the feed hopper motor. Eliminating the uneven lateral feed has the potential to increase production by approximately 12 per cent. It is envisaged that tight seed roll occurrence will reduce with an evenly loaded seed roll, further increasing productivity. Saw blade wear should also reduce, together with the event of fires as a result of tight seed rolls.

Roll box geometry was also investigated, and this highlighted frictional properties, mechanical interaction of the saw teeth, and seed roll densities. Decreasing the time that the seed cotton is present in the roll box would reduce mechanical interaction. Further, the lint mass production rate was investigated, and results indicated that reducing mass production rates decreased nep and seed-coat nep because of a decrease in the seed roll density.

Research was conducted on Continental Eagle 161 gin stands.