Sugar Cane Diffusion

Topics: Sugar beet, Sugarcane, Sugar Pages: 10 (2218 words) Published: September 15, 2010
Sugar Cane Diffusion

The advantages of diffusion

The advantages of diffusion over conventional milling have been confimed by the performances of DE SMET diffusers in industrial operation. De Smet diffusers have processed several million tons of cane in different countries and proved their : √ √ √ √ √ √ Simplicity Efficiency Low maintenance costs Low operation costs Mechanical reliability Adaptation to changes in capacity.

Types of De Smet diffusers

De Smet supplies two types of diffusers : √ The BAGASSE (TS) DIFFUSER to process first mill bagasse, √ and the CANE (TN) DIFFUSER, to process shredded cane. De Smet can therefore give you unbiased advice on the type of diffuser best suited to your conditions. Both types of diffusers are mechanicallly similar and the TS type can be converted into a TN diffuser.

Auxiliary equipment

DE SMET does not manufacture cane preparation and bagasse dewatering equipment but has thoroughly studied these problems and keeps in close touch with new developments in these fields. This enables DE SMET to advise on how to make maximum use of existing equipment and to assume responsibility for the performance of the whole extraction plant when supplied through DE SMET.

Principles of operation

Operation of the diffuser is based on systematic counter current washing of the cane or bagasse by means of imbibition water. In practice, this is achieved by forming a bed of shredded cane or first mill bagasse on a conveyor. Water is added at the discharge end of the conveyor and percolates through the bed of bagasse and the perforated slats of the conveyor. The water dissolves the sugar in the bagasse and the thin juice thus formed is collected in a hopper.

This juice is moved forward one stage by pumping and the process is repeated until the juice reaches maximum concentration at the feed end of the diffuser. The diffuser may be conditioned either for single-flow or for parallel-flows juice circulation.

Description of the diffuser

The housing of the DE SMET diffuser is of welded steel construction.

It is from 35 meters (110 ft) to 52 meters (170 ft) long; the cross section is rectangular and diffusers of different capacities are made in different widths.

The conveyor grids and screens are supported by two outboard type roller chains with a pitch of about 3 feet. These chains are supported at the extreme ends by sprockets.

At the driven end, the sprockets are coupled through a gearwheel and pinion to a variable speed hydraulic drive or electric gearmotor drive.

Flow Sheet of a De Smet Cane Diffusion Plant (TN)

Flow Sheet of a De Smet Bagasse Diffusion Plant (TS)

The conveyor itself is made or articulated frames to which the screens are fixed. The screens and frames are rigidly attached to corresponding links of the two chains. These chains are fitted with self-lubricating bushings. The rollers ride on parallel rails. The return rails are completely exposed underneath the housing, giving full visibility and accessibility to the screens.

Feed conveyor

View of cane diffuser inlet

The thickness of the bed varies from 1.5 meters (5 ft) to 2 metres (6 ft). The space between the two conveyor spans is occuped by a large tank with a sloping bottom split into individual hoppers by means of vertical plates. These vertical plates have horizontal slots, at specified levels, through which the juice overflows to the next hopper. At the end of the conveyor, there is a revolving scraper to even out the flow of bagasse which falls in an outlet hopper. This hopper is provided with a conveyor for removing the bagasse. The diffuser is equipped with lifting screws in the presswater feedback area.

Juice distributors and pumps

During the whole duration of its passage through the diffuser, the bed of cane is submitted to intensive sprays of juice of progressively decreasing concentration. The juice is evenly sprayed above the bed by a series of overflowing troughs...
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