Innovative control system for HUBER Belt Dryer BT

HUBER develops a revolutionary control system for BT Belt Dryers: The system is able to adjust the plant throughput fully automatically to varying dry substance contents in the dewatered sewage sludge. Operator attendance is thus reduced to a minimum.  

Dewatered sewage sludge, even if coming from a sewage treatment plant, does usually not show constant properties. Variations in organic content, chemical composition or polymer necessarily lead to varying dewatering results. Minor variations can normally be balanced quite well, but variations greater than +/– 1% DR per hour may impair the drying process. Throughput performance will decrease or the required degree of drying may not be achieved. The plant operates less efficiently and operating costs increase.

The gap between costs and efficiency will increase even more if also larger amounts of external sludge are fed to the plant. Jumps from several percentage points DR per hour are frequently unavoidable as the sludges are in most cases stored in a large bunker and fed to the dryer as an undefined mixture. Under these circumstances, it is a great challenge for the plant operators to run the plant at full capacity. With an increasing number of different sludge sources it is becoming virtually impossible to achieve a homogenisation of the sludges with justifiable operator attention and personnel expenses.

The number of plants which accept also external sludge will rise in the future due to the tendency to build large sludge centres. HUBER has therefore dealt intensively with this topic and developed a fully automatic control system which continuously measures the DR content of the sludge before the sludge is fed to the drying plant. This ensures that the drying parameters can be set correctly at the moment the sludge is fed to the dryer. This method is unique on the sludge drying market.

The control system consists of a continuously working measuring system which measures the dry substance content of the sewage sludge before the sludge is fed to the dryer. A complex control system fully automatically adjusts all operating parameters of the sludge drying plant to the specific requirements. It is thus possible to adjust jumps of several percentage points DR per hour reliably and without notable fluctuations in performance. The dryer can be operated continuously at the full water evaporation capacity. The following diagram shows dry substance content and water evaporation during a 24-hour measurement period on the test plant.

Despite major variations in inlet DR the dryer adjusts itself fully automatically to the required water evaporation of 1,400 kg/h.
 

The HUBER throughput and performance control system guarantees continuously full plant performance and maximum energy efficiency without the need for plant operators to intervene. In daytime, at night and on weekends.