OVC for Schweizer Zucker AG in Aarberg

On 29 February 2016, a leap day, Schweizer Zucker AG (SZU) based in Aarberg, Switzerland, placed an order with BMA for supply and installation of a vertical cooling crystalliser with oscillating tube bundles (OVC).

The order had been preceded by intensive negotiations and discussions about the plant design. For the customer, it is an investment to replace the existing cooling crystalliser. His aims were to increase reliability and reduce maintenance work, while enjoying the process benefits of an oscillating cooling system, which offers better heat transfer and a lower risk of caking.

SZU wanted to carry out a large share of the project work themselves, while purchasing the necessary core components for the process of the desired quality and from a manufacturer who they had successfully worked with in the past. BMA were also able to offer the extended warranty for drives, gears and material durability requested by SZU, as all our suppliers and production workshops are integrated into the BMA quality system and thus subject to regular inspections.

The plant will be used for the desugaring of low-raw sugar mother liquor, to reduce the sucrose content of the molasses. This is achieved by cooling the massecuite using cooling water that circulates in oscillating cooling packs. The cooling speed and the difference in temperature between the cooling water and the massecuite are controlled.

The BMA scope of supply comprised the complete OVC including the hydraulic unit needed to raise and lower the cooling packs, the molasses-massecuite mingler, and a large package of spare parts. For SZU, it is particularly important that their plants have a long service life. That is why they opted for a stainless steel massecuite distributor as well as having the stainless steel plate in the upper product chamber manufactured 1 mm thicker than the standard.

SZU also commissioned BMA with the necessary engineering services and all assembly work at their Aarberg factory. As the new OVC was due to be commissioned in time for the 2017 juice campaign, the individual parts had to be delivered in October 2016, so the assembly, piping installations and electrical connection could be completed by April 2017. Transporting the components through Germany and Switzerland, some of them as wide loads, presented an additional challenge – also, because their arrival was timed to coincide with the start of the beet campaign at the Aarberg factory, which required careful coordination.

Assembly started as planned and was completed in mid-January 2017 with a successful water test. In this project, BMA used a new, improved hydraulic unit with an integrated control system for the first time; it helps lower operating costs, as it requires less oil and only half the installed power. The speed of the raising movement is steplessly adjusted to the viscosity of the massecuite. As a result, heat transfer to the cooling packs is further improved. The unit was com- missioned in March 2017 by SZU, BMA and the supplier of the hydraulic unit.

Although the juice campaign at the Aarberg sugar factory had been rescheduled to start earlier than planned, in late March, the plant was ready for operation and handoff to SZU.