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De Smet constructing a new sugar refinery near Algiers

De Smet Engineers & Contractors (DSEC), the complete plant supplier and internationally renowned engineering, equipment and construction services provider in the agro-food sector, is currently executing on behalf of N’Gaous Sugar Spa, subsidiary of the Algerian industrial group Mazouz, the construction of a greenfield sugar refinery in a new industrial zone in Larbatache, a few kilometres to the east of Algiers.

This factory, with capacity of 2000 tonnes per day, will be able to simultaneously produce white refined sugar, liquid sugar and refined brown sugar in a wide range of packaging options. The site will be equipped with a combined heat and power generation unit (CHP), making the factory completely self-sufficient in electricity, as well as necessary utilities required for refining processes.

Raw sugar remelting and purification

Raw sugar unloaded at the Port of Algiers nearby is transported to the site by lorry and stored in bulk in a large capacity sugar warehouse facilitating secure supply of raw materials to the factory. The sugar is then melted down before being purified through double carbonation then filtered on candle filters. Thick sludge is then filtered and desugared on a filter press. The purified and clarified liquor is concentrated by means of dual-effect evaporation.

Crystallisation and drying

Thanks to its proprietary modelling tool (see more details below), DSEC is simulating the colour transfer in the crystal layer by layer while an optimized process concept developed by the company avoids the use of ionic exchange decolourisation, all this ensuring a maximum energy efficiency.

The crystallisation operation is conducted by 3 strikes R1-R2-R3. The R1 and R2 strikes produce white sugar. A portion of R1 refined sugar is melted to create liquid sugar. The remaining R1 sugar, along with the R2 sugar are dried in a rotary dryer then cooled in a fluid-bed cooler before being sent to a maturing silo in order to prevent caking of the packaged refined sugar.

Refined sugar packaging

The factory has several bagging lines, from 50kg bags to 1kg packs. On leaving the maturing silo, the refined white sugar is packaged and dispatched by lorry. The refined brown sugar is dried in a dryer/cooler before being packaged and dispatched. The factory is also set up for future plans to package sugar in cubes.

Production and use of energy

The energy used in the refinery is supplied by a CHP unit. This unit produces the required electricity for the operation of the plant as well as steam used in the processing. It is comprised of a gas fired water tube boiler and a turbo alternator. Latter is supplied by high pressure steam produced by the boiler while the turbo exhaust steam is used in the refinery with additional desuperheated steam. The exhaust steam supplies the first evaporation stage and a steam transformer that feeds the various vacuum pans. The exhaust steam condensates are collected and sent back to the CHP unit. All other heaters for the refinery are supplied with steam generated by the concentration of the liquor, at the first and second stage. The condensates from this processing steam are collecting in the refinery. Vapours extracted from the various vacuum pans are connected to a shared vacuum network supplying an air condenser. The condensates generated in the air condenser are collected and used in the process.

DSEC’s expertise mobilised

DSEC was selected at the end of 2015 by the Mazouz Group for the construction of this new factory due to its proven expertise in the sugar sector. The process implemented by DSEC affords particular attention to energy saving as well as to the quality of the refined white sugar. For this, DSEC developed several years ago a predictive modelling programme (DSEC IPM® – Integrated Predictive Model) making it possible to simulate the complete installation in a single integrated calculation tool. This tool, based on a Matlab/Simulink® architecture, allows for the optimisation of the process and energy requirements. The model simultaneously allows for the consolidation of not only material and thermal balance but also the prediction of the colour transfer through the growing of the various layers of sugar crystals.

Thanks to this tool and a solid knowledge of sugar processing, DSEC has designed and successfully implemented numerous optimised solutions in the raw sugar refinery sector. It is on the basis of this proven model that DSEC was able to propose to the Mazouz Group a sugar refinery producing high purity white sugar from VHP sugars available on the market. Further,  the proposed refining process requires no decolourization equipment. This has enabled N’Gaous Sugar Spa to make substantial savings, both in terms of CAPEX and OPEX, while still maintaining a hugely flexible installation.

For DSEC it represents a second sugar project concluded in Algeria in just a few years, thus establishing its presence in the country and demonstrating its ability to manage large scale projects in the sugar sector. DSEC’s mission includes, within the context of this project, preliminary and detailed studies, management of construction operations as well as sourcing the vast majority of the equipment that go into making the new factory. This equipment, sized by DSEC engineers in Waterloo, Belgium, primarily originates from well-known European suppliers and with proven expertise in the sugar sector.

The factory is located on a site with several particular features that DSEC had to consider: the significant gradient of the site was a major constraint impacting smooth flow of lorries and products; and plus, due to the presence of a high voltage electricity line crossing from one end of the site to the other it was imperative  to observe a safe distance. . These two constraints required DSEC to show particular ingenuity in the plans in order to design an efficient and functional facility.

With regard to the process, concern for saving clean water for the region also directed DSEC towards solutions limiting consumption by avoiding the use of high throughput cooling towers in favour of air condensers.

Earthworks and civil engineering commenced shortly after signing the contract. This very much demonstrated the desire on the part of N’Gaous Sugar Spa to progress quickly with the project.

De Smet

De Smet Engineers & Contractors
Waterloo Office Park
Building O – Box 32
Drève Richelle 161
1410 Waterloo