23.10.2014

Key development area: fluidised-bed steam drier (WVT)

Fluidised-bed steam driers as an integral part of the energy concept for sugar factories bring more than just energy savings. This drying technology can also help dramatically reduce emissions and thus has excellent prospects. Which is why BMA has decided to place it at the centre of its development efforts.

Additional test installations

BMA has extended its pilot plant with new test installations, where a wide range of factors can be studied:

  • Behaviour of the product in the fluidised bed
  • Improving internal dust separation
  • Design of the distribution plate
  • Performance enhancement of the complete system

A plant for tests in an atmosphere of superheated water vapour and at a system pressure of approx. 4 bar was already installed several years ago. It is still indispensable for new products and will therefore be further optimised.

With these new opportunities, almost all process-engineering problems that may occur during installation of a WVT drier can be solved. Developments in the early detection of blockages (PPC system) and product volume control in the fluidised bed, together with the required measuring system, have been implemented as part of the newly defineddevelopment programme. Both modifications have stood their test in practical operation: enhanced reliability and higher throughputs with converted driers.

Comprehensive service package for Nordic Sugar

The beginning of the year 2013 marked the first success of BMA’s activities with an order placed by Nordic Sugar for a WVT to be installed in their Örtofta plant and to be commissioned for the 2014 beet campaign. This drier comes with several new solutions for improved reliability and availability. Supplies from BMA include a size 10 WVT fluidised-bed drier with a nominal water evaporation rate of 55 t/h. The drier is equipped with a split superheater, so two different steam pressures can be used for drying: a relatively low pressure for the first, and a much higher pressure for the second heating stage. As a result, the available steam can also be optimally used for electric power generation in the factory.

The engineering services for this project consist of the layout plan, the provision of the necessary process-engineering parameters for connected media, and enquiry documentation for conveyors and tanks. Also included are the P&ID concept, as well as a detailed description of the measuring and control requirements with interlocking diagrams.

The rotary air locks at the drier’s inlet and outlet ends, with the control system and ancillary equipment, as well as the installation of the complete drier at the Örtofta site, followed by commissioning and a performance run, complement the service package. At the end ofJanuary 2014, BMA deliveredthe components of the major drier assemblies on schedule.

The future of the WVT

After the success that the WVT concept with thermal utilisation of the drying vapour has achieved in sugar factories, BMA is now striving to also establish it in other sectors of industry. Responsibility for this type of drier has therefore been shifted to the newly created “Biomass” department that will be looking into WVT application options in various other industries. Here again, the BMA pilot plant will play a crucial role.

BMA’s activities and results were presented at an international user workshop in Braunschweig, which also provided an excellent platform for discussing and sharing the sometimes completely different experiences that users have made with the operation of fluidised-bed steam driers.

Hartmut Hafermann
BMA AG

engineering@bma-de.com