Screw Conveyors Aid in Production of Ammonium Sulfate

February 9, 2015

4 Min Read
Screw Conveyors Aid in Production of Ammonium Sulfate

In the new ammonium sulfate plant that DSM is building in Geleen (the Netherlands) there will be as many as 17 Van Beek screw conveyor systems. These conveyor systems play an important part in the production of ammonium sulfate - a substance that is mainly used as artificial fertilizer, but can also be used as a raw material for medicines and foodstuffs.
    The building of the more energy-efficient plant started in 2012 under the project name, ‘Next Generation Sulfa’. Ammonium sulfate in solution is a by-product of DSM’s caprolactam plant (caprolactam is a raw material for nylon 6). The ammonium sulfate plant was due for replacement after over 40 years of service. The caprolactam plant produces a constant stream of ammonium sulfate solution, so by building the new plant directly alongside the caprolactam plant, the constant stream of ammonium sulfate can be processed immediately.

The Ammonium Sulfate Treatment Process
The feedstock for the new plant is pumped to a crystallizer, where the mixture is evaporated. This causes supersaturation, resulting in the production of ammonium sulfate crystals (solid ammonium sulfate). These crystals grow in size until granules of solid ammonium sulfate are produced. Then a centrifuge separates the liquid and crystals from one another and the product is dried, screened, and stored.
    But where in the process are the 17 Van Beek screw conveyor systems located? Twelve of the 17 screw systems (trough conveyors) form part of the transport route for the still wet crystals from the various crystallization units to the dryer. The other five screw systems form part of the transport route for the dry product to storage and transfer.

Not the Blacksmith around the Corner
During the first contact with Van Beek and a visit to the company, Peter Steegs, engineering manager at DSM Fibre Intermediates, was immediately struck by a number of positive things. “Technically Van Beek meets the requirements,” said Steegs. “Among other things, SS and CS are kept well separated in the shop and there was no problem in meeting the implementation of the client’s ‘hygienic design requirements’. Due to the way in which the organization is set up – clear structures and communication lines and with a sound documentation system – Van Beek seems to have things under control. In view of the size of the order and the importance for DSM of prompt delivery, we decided not to give the order to the blacksmith round the corner but to a mature company that supplies good quality equipment and has often worked with this type of orders and requirements from its principals.”
    Joram van der Heijden, sales engineer at Van Beek and intensively involved in the ‘Next Generation Sulfa’ project, is very satisfied with the cooperation with principal Tebodin and end client DSM Geleen. “Tebodin was our client and managed this part of the project as regards engineering and purchasing for DSM,” said van der Heijden. “I found both parties to be experienced professionals, demanding companies - which in my opinion are a perfect fit within our definition of `the Van Beek client’.”
    Peter Steegs added, “We also found the cooperation a pleasant experience because with Van Beek we were sitting at the table with the right people; partners who helped us think and could solve problems and not just salesmen with no substantive knowledge. Their structured way of working really struck me, because a project of this size requires a structured approach.”
    DSM’s Next Generation Sulfa project requires a huge quantity of documents such as manuals, construction books, and certificates. Van Beek manages its information and documentation flows in a CRM system it has developed itself and which is therefore unique. As a result information is quick and easy to retrieve, for both Van Beek staff and the client, not only during the production process, but also after delivery and during servicing operations in the future.
Management, Operation and Use
If ammonium sulfate comes into contact with moisture it becomes aggressively corrosive. This is why in the new plant all the installations, piping, and the screw conveyor systems were made of SS316L. The screw conveyor systems are of the trough conveyor type and convey the ammonium sulfate horizontally or at a slightly inclined angle. The dimensions of the screw range in diameter from 300 to 500 mm inclusive, and in length from 3 to 12 m inclusive. The longer systems are made with special intermediate bearings (made of SS316L) and special gaskets and inspection hatches. Four of the 17 screw conveyor systems are used for raw material production for the foodstuffs industry. Here the screw conveyors have a ground finish. In addition application-specific options are incorporated, such as level detection, moisture measurement, and the fitting of sampling points, CIP piping, and spray nozzles. Van Beek makes high demands of itself as regards the technical documentation for maintenance and use. For each screw conveyor among other things drawings, manuals, spare parts lists, motor data, tag numbers, and certificates are supplied.
    “Finally I can say that Van Beek screw conveyors fit within the state-of-the-art plant that DSM is building,” concluded Steegs. “We will certainly recommend Van Beek within DSM for any future projects.”

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